Monday, December 29, 2014

MCQ on Urinary System Physiology


1) The nephron is:
     a. the site of urine storage
     b. the functional unit of the kidney
     c. the site where ADH is produced
     d. also called the "Bowman's capsule"


2. Which of the following is NOT a stage of urine formation:
     a. glomerular filtration
     b. glomerular secretion
     c. tubular secretion
     d. tubular reabsorption


3. Which of the following is NOT a means of regulating glomerular filtration:
     a. muscular regulation
     b. renal autoregulation
     c. hormonal regulation
     d. neuronal regulation


4. Increased sympathetic nervous system stimulation of afferent arterioles results in:
     a. decreased filtrate production
     b. increased filtrate production
     c. no change in filtration rate
     d. increased kidney function


5. Renin is produced by:
     a. the glomerulus
     b. macula densa
     c. proximal convuluted tubule
     d. juxtaglomerular cells


6. The function of the macula densa cells is to:
     a. prevent water reabsorption in the ascending loop of Henle
     b. add bicarbonate ions to the tubular filtrate
     c. secrete renin in response to decreased afferent arteriole pressure
     d. monitor NaCl concentration in the filtrate
     e. reabsorb Na+ ions into blood from the filtrate


7. Atrial naturiuretic peptide works to:
     a. increase afferent arteriole pressure
     b. increase blood flow to the kidney
     c. enhance the effects of ADH
     d. inhibit the effects of aldosterone
     e. increase blood volume


8. If the level of aldosterone in the blood increases, then:
     a. less sodium is excreted in the urine
     b. less potassium is excreted in the urine
     c. systemic blood pressure will decrease
     d. glomerular filtration will decrease
     e. both c and d


9. The most important function of the juxtaglomerular apparatus (JGA) is to:
     a. secrete water and sodium into the filtrate
     b. reabsorb sodium
     c. generate bicarbonate ions in response to decreased blood pH
     d. secrete renin in response to decreased renal blood pressure or blood flow
     e. constrict the afferent arterioles and decrease sodium reabsorption


10. If the diameter of the afferent arteriole is smaller than the diameter of the efferent arteriole, then:
     a. the net filtration pressure will decrease
     b. blood pressure in the glomerulus will decrease
     c. GFR will increase
     d. a and b only
     e. a, b and c


11. From the distal convoluted tubule, filtrate will then be carried to the:
     a. renal corpuscle
     b. collecting duct
     c. nephron loop
     d. proximal convoluted tubule
     e. glomerular (Bowman's) capsule


12. In a patient who is dehydrated from vomiting and diarrhea, which is likely to be higher than normal in blood:
     a. ADH only
     b. aldosterone only
     c. ANP only
     d. both ADH and aldosterone
     e. both ADH and ANP


13. All of the following are normally found in urine except:
     a. glucose
     b. sodium ions
     c. uric acid
     d. urea
     e. creatinine


14. In some autoimmune diseases, capillaries may become damaged resulting in and high levels of albumin proteins and blood cells appearing in the urine. Which region of the nephron contains capillaries that, when damaged, could cause this appearance in urine:
     a. renal glomerulus
     b. proximal convoluted tubule
     c. nephron loop
     d. distal tubule


15. Regarding the renal circulation:
a) The kidneys receive about 10% of the resting cardiac output
b) As cardiac output increases during exercise renal blood flow rises.
c) Renal blood flow is maintained within narrow limits despite changes in arterial blood pressure.
d) Increased activity in the renal sympathetic nerves results in increased blood flow to the kidneys.

16. Regarding the glomerular filtration rate (GFR):
a) The GFR depends on the pressure in the afferent arterioles.
b) A substance that has a clearance less than the GFR must have been secreted by the renal tubules.
c) The glomerular filtration rate can be determined by measuring the clearance of insulin.
d) The glomerular filtrate has the same composition as plasma.

17. Regarding the transport of glucose by the renal tubules:
a) In a healthy person, the distal tubules reabsorb all of the filtered glucose.
b) Glucose is secreted into the urine in small quantities.
c) The transport maximum for glucose is about 36 mg min-1.
d) Glucose transport by the renal tubules is linked to sodium transport.

18. Concerning the excretion of acid by the kidneys:
a) The filtered bicarbonate is absorbed by anion transport.
b) The intercalated cells of the distal tubule secrete hydrogen ions to reabsorb bicarbonate from the tubular fluid.
c) All of the filtered bicarbonate is normally reabsorbed in the first half of the distal tubule.
d) Urine pH is normally greater than that of plasma.

19. Regarding the control of water balance by the kidneys:
a) The renal medulla has an osmotic gradient that decreases from the border with the cortex to the renal papilla.
b) ADH is secreted by the anterior pituitary in response to a decrease in the osmolality of the blood.
c) A normal person cannot produce urine with an osmolality greater than 300 mOsmol.kg-1.
d) ADH acts on the P cells of the collecting ducts to increase their permeability to water.

20. The term "renal autoregulation" refers in part to the fact that
A. the kidney does not require blood flow to sustain its active transport
B. the kidney contains baroreceptors (pressure receptors) that contribute to the regulation of cardiac output
C. renal blood flow is relatively constant over a wide range of systemic arterial pressures
D. renal blood flow is not affected by activation of the sympathetic nerves that innervate the kidney
E. a combination of both C and D above

21. The nerves that innervate the kidney are essential for regulating which of the following?
A. Na-K-ATPase active transport pump rate
B. renal autoregulation of blood flow
C. urine volume and tonicity (osmolality)
D. all of the above
E. none of the above

22. Which of the following would be expected to cause renal inulin (or creatinine) clearance to increase?
A. dilation of the afferent arteriole
B. dilation of the efferent arteriole
C. constriction of the afferent arteriole
D. constriction of the efferent arteriole
E. both A and D above

23. Kidney inflammation may result in the appearance of albumin (a plasma protein) in the urine because
A. more albumin enters the proximal tubule in the glomerular filtrate
B. reabsorption of albumin from the proximal tubule is inhibited
C. secretion of albumin into the distal tubule and collecting ducts is increased
D. increased peritubular blood flow makes more albumin available for diffusion into the tubule
E. reduced active transport of sodium ion reduces cotransport of other substances, including albumin

24. As blood passes along the glomerular capillaries from the afferent to efferent arteriole, the net filtration pressure (DP - Dp)
A. increases
B. decreases
C. first decreases, reaches a minimum about half way along the capillary, then increases
D. first increases, reaches a maximum about half way along the capillary, then decreases
E. remains constant

25. Sodium is actively reabsorbed from the renal tubule in which of the following nephron segments?
A. proximal tubule
B. distal tubule
C. thick ascending limb of the loop of Henle
D. all of the above
E. none of the above

26. The rate of water reabsorption from the proximal tubule is determined primarily by the
A. rate of dissolved particle (solute) reabsorption from the proximal tubule
B. concentration of ADH (antidiuretic hormone) in the blood
C. osmotic pressure developed by plasma proteins in the proximal tubule
D. active transport of water molecules by the proximal tubule cells
E. passive filtration due to the high hydrostatic pressure in the proximal tubule

27. Urea has a higher concentration in the fluid that leaves the proximal tubule (and enters the loop of Henle) than in blood plasma because
A. urea is synthesized by proximal tubule cells
B. urea is secreted into the proximal tubule
C. urea is reabsorbed from the proximal tubule but at a lesser rate that water is reabsorbed
D. urea diffuses back into the proximal tubule because of the high urea concentration in the renal medulla
E. urea is actively transported into Bowman's capsule from the glomerular capillaries

28. In the proximal tubule, penicillin is
A. actively secreted into the tubule
B. actively reabsorbed from the tubule
C. passively reabsorbed from the tubule
D. metabolized by the tubule cells
E. neither secreted nor reabsorbed nor metabolized

29. At which sites would the concentration of creatinine be expected to be highest? (Note: assume the person is normally hydrated.)
A. glomerular filtrate
B. end of the proximal tubule
C. end of the loop of Henle
D. urine
E. the concentration would be the same in all of the above, since creatinine is neither secreted or reabsorbed

30. Suppose a person loses the function of half his nephrons because of renal degenerative disease. Assuming the person survives and reaches a new steady state and that body urea production remains normal, which of the following would be expected to decrease below normal?
A. plasma urea concentration
B. renal urea excretion
C. renal urea clearance
D. urine urea concentration
E. all of the above

31. The following values are measured for potassium ion in a human subject.
Plasma K+                            5 meq/liter
Urine K+                               50 meq/liter
Renal creatinine clearance  80 ml/min
Urine formation rate             1.5 ml/minute
This patient's potassium clearance is closest to which of the following?
A.   5 ml/minute
B. 7.5 ml/minute
C. 15 ml/minute
D. 50 ml/minute
E. 75 ml/minute

32. Assuming the subject in the preceding question is a normal adult, we can conclude that most likely potassium is
A. filtered but not secreted or reabsorbed
B. secreted but not filtered or reabsorbed
C. reabsorbed but not secreted or filtered
D. filtered and secreted
E. filtered and reabsorbed

33. Stimulation of the osmoreceptors in the hypothalamus would be expected to cause all of the following to increase except
A. ADH release from the pituitary
B. water reabsorption from the renal collecting duct
C. rate of urine formation
D. osmolality of urine
E. none of the above; that is, none are exceptions since all would be expected to increase

33. As fluid passes along a juxtamedullary nephron, where is its osmolality (total concentration of dissolved particles) lowest? (Note: assume a normal concentration of circulating ADH.)
A. Bowman's capsule (glomerular filtrate)
B. fluid leaving the proximal tubule and entering the loop of Henle
C. fluid leaving the descending thin limb and entering the ascending thin limb of the loop of Henle
D. fluid leaving the thick ascending segment of the loop of Henle and entering the distal tubule
E. fluid leaving the collecting ducts (urine)

34 Drinking vodka (a beverage with a high ethanol content, for those of you unfamiliar with this substance) would be expected to cause excretion of a
A. large volume of concentrated urine
B. small volume of concentrated urine
C. large volume of dilute urine
D. small volume of dilute urine
E. normal volume of urine of normal osmolality

35. Drinking which of the following would lead to the highest rate of ADH secretion and release?
A. two liters of distilled water
B. two liters of sea water (mainly hyperosmotic saline)
C. two liters of iso-osmotic (isotonic) saline
D. two liters of human blood plasma
E. none of the above, since drinking two liters of any liquid leads to inhibition of ADH release

36. In a patient with severe renal artery stenosis (narrowing), all of the following would be expected to be increased above normal except
A. plasma renin concentration
B. plasma angiotensin II concentration
C. blood pressure (hydrostatic pressure) in the glomerular capillaries
D. resistance to blood flow in the efferent arteriole
E. systemic arterial blood pressure

37. Administration of an Angiotensin Converting Enzyme inhibitor (ACE inhibitor) to the above patient might lead to acute renal failure by
A. inhibiting renal tubule potassium reabsorption
B. increasing renal resistance to blood flow
C. causing plasma proteins to be excreted in the urine
D. causing systemic arterial hypertension
E. reducing glomerular filtration rate

38. Which of the following is the stimulus for increased secretion of atrial natriuretic peptide (ANP)?
A. increase blood plasma osmolality above normal
B. decrease blood plasma osmolality below normal
C. increase systemic arterial pressure
D. increase venous blood volume and atrial pressure
E. increase cardiac contractility (force of contraction)

39. An increase secretion of renin would be expected to have what effect on sodium excretion and potassium excretion in urine?
A. increase in Na+ excretion and increase K+ excretion
B. increase in Na+ excretion and decrease K+ excretion
C. decrease in Na+ excretion and increase K+ excretion
D. decrease in Na+ excretion and decrease K+ excretion
E. decrease in Na+ excretion but no effect on K+ excretion

40. In which of the following fluids is the pH highest (most alkaline)? (Assume the person is normal.)
A. systemic arterial blood plasma
B. systemic venous blood plasma
C. urine
D. all of the above, since pH is normally of the same for all
E. A and B above, since blood plasma pH is relatively uniform

41. The ammonium (NH4+) ion that may be present in urine is produced by
A. breakdown of urea in the liver
B. metabolism of amino acids in the renal tubule and collecting duct
C. aerobic carbohydrate metabolism
D. gylcolytic pathways during anaerobic metabolism
E. gluconeogensis during starvation

42. The reason that respiratory compensation for metabolic alkalosis can never be complete (return plasma pH to normal) is that (Note: PaCO2 = systemic arterial carbon dioxide partial pressure.)
A. high PaCO2 inhibits respiratory ventilation
B. high PaCO2 stimulates respiratory ventilation
C. low PaCO2 inhibits respiratory ventilation
D. low PaCO2 stimulates respiratory ventilation
E. none of the above, since respiratory compensation for metabolic alkalosis can be complete

43. The appearance of large amounts of ammonium ion (NH4+) in the urine is characteristic of the renal response to
A. respiratory acidosis
B. respiratory alkalosis
C. acidosis resulting from pancreatic diabetes
D. alkalosis resulting from gastric vomiting
E. both A and C above

44. An individual hoping for an LSD "acid high" mistakenly gives himself an intravenous injection of hydrochloric acid. The responses of his body which attempt to compensate for this ignorance of physiology include all of the following except
A. hyperventilation
B. increase in the acid form of the blood fixed buffers
C. decrease in blood bicarbonate ion concentration
D. increase in urine bicarbonate ion excretion
E. increase in urine ammonium ion excretion

45. A systemic arterial blood sample taken from the above individual an hour after his HCl "adventure" might show which of the following?
A. base excess = +10 meq/liter; PaCO2 = 50 mmHg
B. base excess = +10 meq/liter; PaCO2 = 30 mmHg
C. base excess = -10 meq/liter; PaCO2 = 50 mmHg
D. base excess = -10 meq/liter; PaCO2 = 30 mmHg
E. base excess = 0 meq/liter; PaCO2 = 40 mmHg

46.  A young woman is found comatose, having taken an unknown number of sleeping pills an unknown time before. An arterial blood sample yields the following values:
pH      7.02
HCO3-   14 meq/liter
PaCO2   68 mmHg
This patient's acid-base status is most accurately described as
A. uncompensated metabolic acidosis
B. uncompensated respiratory acidosis
C. simultaneous respiratory and metabolic acidosis
D. respiratory acidosis with partial renal compensation
E. respiratory acidosis with complete renal compensation


Question
Regarding the regulation of plasma sodium:
a) The granular cells of the afferent arterioles cells secrete renin when plasma sodium is low.
b) Angiotensin II is formed from renin by the action of an enzyme found on the endothelium of the pulmonary blood vessels.
c) The uptake of sodium ions is regulated by the proximal tubule.

d) Sodium transport by the thick ascending limb of the loop of Henle occurs by the same mechanism as that of the proximal tubule.

Sunday, December 28, 2014

Pigmentation and Discoloration of Oral and Facial Tissues

Pigmentation and Discoloration of Oral and Facial Tissues

Pigmentation is a discoloration of the oral mucosa or gingiva due to the wide variety of lesions and conditions. Oral pigmentation has been associated with a variety of endogenous and exogenous etiologic factors. Also it can be explained as Oral mucosal discolouration, which ranges from brown to black may be due to superficial (extrinsic) or deep (intrinsic in or beneath mucosa) causes.

Types of Oro-maxillofacial Pigmentation
Extrinsic discoloration
Extrinsic discoloration is usually caused by extrinsic pigments. It is rarely of consequence and is usually caused by colored foods, drinks or drugs. Extrinsic discoloration usually affects both mucosae and teeth are discolored. Causes include the following:
Foods and beverages, such as beetroot, red wine, coffee and tea.
Confectionery, such as liquorice.
Drugs, such as chlorhexidine, iron salts, griseofulvin, crack cocaine, minocycline, bismuth subsalicylate, lansoprazole and HRT.
Tobacco: this may cause extrinsic discolouration, but can also cause intrinsic pigmentary incontinence, with pigment cells increasing and appearing in the lamina propria. This is especially likely in persons who smoke with the lighted end of the cigarette within the mouth (reverse smoking), as practiced mainly in some Asian communities. Tobacco is a risk factor for cancer.
Betel: this may cause a brownish-red discolouration, mainly on the teeth and in the buccal mucosa, with an irregular epithelial surface that has a tendency to desquamate. It is seen mainly in women from South and Southeast Asia. Betel chewer’s mucosa epithelium is often hyperplastic, and brownish amorphous material from the betel quid may be seen on the epithelial surface and intra- and intercellularly, with ballooning of epithelial cells. Betel chewer’s mucosa is not known to be precancerous, but betel use predisposes to submucous fibrosis and to cancer.

Intrinsic staining
Causes for intrinsic hyperpigmentation are Increased melanin or number of melanocytes, or other materials. Intrinsic discolouration may have more significance than the extrinsic type. Normal intrinsic pigmentation is due to melanin, produced by melanocytes dendritic cells prominent in the basal epithelium.
Localized areas of pigmentation are usually caused by benign conditions:
Embedded amalgam (amalgam tattoo)
Embedded graphite (graphite tattoo)
Other foreign bodies
Local irritation/inflammation
Melanotic macule
Naevi
Melanoacanthoma.
However, neoplasms, such as Kaposi sarcoma or malignant melanoma, are occasionally responsible. The anterior pituitary gland releases melanocyte stimulating hormone (MSH), which increases melanin production. Melanin pigmentation thus increases under hormonal stimulation, either by MSH, or in pregnancy, or rarely due to the action of adrenocorticotrophic hormone (ACTH), the molecule of which is similar to MSH, or under the influence of other factors (e.g. smoking). Thus in all patients systemic causes should be excluded, such as:
Drugs; including smoking and the contraceptive pill
Hypoadrenalism; there is increased ACTH production
Peutz–Jeghers syndrome
HIV infection
Von Recklinghausen’s disease
Albright syndrome
Rarely, palatal pigmentation from bronchogenic carcinoma.
Amalgam Tattoo

Betel Stains

Peutz Jeghers Syndrome


List Causes of hyperpigmentation
Localized
Amalgam, graphite, carbon, dyes, inks or other tattoos
Ephelis (freckle)
Epithelioid angiomatosis
Kaposi’s sarcoma
Malignant melanoma
Melanoacanthoma
Melanotic macule
Naevus
Pigmented neuroectodermal tumour
Verruciform xanthoma
Multiple or generalized
Genetic:
Racial
Carney syndrome
Complex of myxomas, spotty pigmentation and endocrine overactivity
Laugier–Hunziker syndrome
Lentiginosis profusa
Leopard syndrome
Peutz–Jeghers syndrome

Drugs:
ACTH
amiodarone
antimalarials
betel
busulphan
chlorpromazine
clofazamine
contraceptive pill
ketoconazole
menthol
metals (bismuth, mercury, silver, gold, arsenic, copper, chromium, cobalt, manganese)
methyldopa
minocycline
phenothiazines
smoking
zidovudine

Endocrine:
Addison’s disease
Albright’s syndrome
Nelson’s syndrome
pregnancy

Post-inflammatory

Others:
Gaucher’s disease
generalized neurofibromatosis
haemochromatosis
HIV disease
incontinentia pigmenti
thalassaemia
Whipple’s disease

 
List the Causes of Pigmentation 

Melanin
Melanin, a nonhemoglobin derived brown pigment, is the most common of the endogenous pigments and is produced by melanocytes present in the basal layer of the epithelium. Melancocytes have a round nucleus with a double nucleus membrane and clear cytoplasm lacking desmosomes or attachment plates. Melanin accumulates in the cytoplasm, and the melanosome is transformed into a structureless particle no longer capable of melanogenesis. The number of melanocytes in the mucosa corresponds numerically to that of skin; however,in the mucosa their activity is reduced. Various stimuli can result in an increased production of melanin at the level of mucosa including trauma, hormones, radiation, and medications.Thyrosinase activity is present in premelanosome and melanosomes but absent in melanin granules.

Melanoid
Granules of melanoid pigment are scattered in the stratum lucidum and stratum corneum of the skin. Initially it was assumed melanoid was a degradation product of melanin, but more recently it has been shown that such a relationship is highly improbable. Melanoid imparts a clear yellow shade to the skin.3

Oxyhemoglobin and Reduced Hemoglobin
Oxyhemoglobin and reduced hemoglobin are pigments resulting from hemosiderin deposits.
The skin color is affected by the capillary and venom plexuses shining through the skin.

Carotene
Carotene is distributed in the lipids of the stratum corneum and stratum lucidum and gives a deep yellow color to the skin. It is found in higher concentrations in more women than in men. Pigmented lesions of the oral cavity are of multiple origin. Different classifications are used at this time. Some researchers divide the lesions into two main groups as either endogenous or exogenous lesions. Brocheriou et al.
subdivides pigmented lesions as follows:

• Non tumoral pigmentations
• Non melanin pigmented tumors or tumor like lesions
• Benign melanin pigmented tumors
• Malignant melanomas
In several articles on oral pigmentation, Dummett and others implicate many systemic and local factors as causes of changes in oral pigmentation.

Epidemiology
Oral pigmentation occurs in all races of man.There were no significant differences in oral pigmentation between males and females. The intensity and distribution of racial pigmentation of the oral mucosa is variable, not only between races, but also between different individuals of the same race and within different areas of the same mouth. Physiologic pigmentation is probably genetically determined, but as Dummett suggested , the degree of pigmentation is partially related to mechanical, chemical, and physical stimulation. In darker skinned people oral pigmentation increases, but there is no difference in the number of melanocytes between fair-skinned and dark-skinned individuals. The variation is related to differences in the activity of melanocytes.There is some controversy about the relationship between age and oral pigmentation. Steigmann and Amir et al. stated all kinds of oral pigmentation appear in young children. Prinz, on the other hand, claimed physiologic pigmentation did not appear in children and was clinically visible only after puberty.

Clinical Characteristics
The gingivae are the most frequently pigmented intraoral tissues. Microscopically, melanoblasts are normally present in the basal layers of the lamina propria.The most common location was the attached gingiva (27.5%) followed in decreasing order by the papillary gingiva, the marginal gingiva, and the alveolar mucosa.The total number of melanophores in the attached gingival was approximately 16 times greater than in the free gingival. The prevalence of gingival pigmentation was higher on the labial part of the gingiva than on the buccal and palatal/lingual parts of the arches.The shade of pigment was
classified as very dark brown to black, brown, light brown-yellow.3 Melanin pigmentation of the
oral tissues usually does not present a medical problem, but patients complain of black gums.
Classification and Differential Diagnosis
Oral pigmentation has been associated with a variety of lesions and conditions. Differential diagnosis of oral mucous membrane pigmentations are made according to the following situations:

A. Localized Pigmentations: Amalgam tatoo, graphite or other tattoos, nevus, melanotic macules, melanoacanthoma, malignant melanoma, Kaposi’s sarcoma, epithelioid oligomatosis, verruciform xanthoma

B. Multiple or Generalized Pigmentations

1. Genetics: Idiopathic melanin pigmentation (racial or physiologic pigmentation), Peutz-Jegher’s syndrome, Laugier-Hunziker syndrome, complex of myxozomas, spotty pigmentation, endocrine overactivity, Carney syndrome, Leopard syndrome, and lentiginosis profuse

2. Drugs: Smoking, betel, anti-malarials, antimicrobials, minocycline, amiodarone, clorpromazine, ACTH, zidovudine, ketoconazole, methyldopa, busulphan, menthol, contraceptive pills, and heavy metals exposure (gold, bismuth, mercury, silver, lead, copper)

3. Endocrine: Addison’s disease, Albright’s syndrome, Acanthosis nigricans, pregnancy, hyperthyroidism

4. Postinflammatory: Periodontal disease, postsurgical gingival repigmentation

5. Others: Haemochromatosis, generalized neurofibromatosis, incontinenti pigmenti, Whipple’s disease, Wilson’s disease, Gaucher’s disease, HIV disease, thalassemia, pigmented gingival cyst, and nutritional deficiencies

Systemic and Local Causes of Pigmentation
Many systemic and local factors are caused by changes in oral pigmentation. Some of the important factors are discussed below.

Amalgam Tattoo
The pigmentation of the oral mucous membrane by tooth restoration material (amalgam) is a
common finding in dental practice. Amalgam pigmentation is generally called amalgam tattoo.The lesion represents embedded amalgam particles and usually manifests itself as an isolated bluish or black macule in various areas of the mucosa. The color is usually described as black, blue, grey, or a combination of these. Almost half were located on the gingiva and alveolar mucosa, the mandibular region being affected more than the maxillary region. Almost half of the lesions were asymtomatic and were discovered during routine dental examination. The amalgam granules and fragments were found mainly in the lamina propria but were sometimes seen in the submucosa.

Pigmented Nevi
Pigmented nevi of the oral cavity are uncommon. The pigmented nevi are classified as intramucosal, junctional, compound, or blue according to their histological features. Nevi are seen particularly on the vermillion border of the lips and the gingivae. They are usually grey, brown, or bluish macules and are typically asymptomatic. Melanocytes are pigment producing cells characterized by the ability to syntesize via the enzyme dihydroxyphenylalanine (DOPA). A group of melanocytes (generally four or more) are in contact with the basal layer of the epithelium.

Oral Melanotic Macules
Oral melanotic macules are relatively rare oral mucosal lesions, analogous to skin freckles, due to the focal increase of melanin production.These melanotic macules have been variously termed ephelis, melonosis, lentigo, solitary labial lentigo, labial melanotic macule, and oral melanotic macule.The vermillion border of the lower lip is most commonly involved.The buccal mucosa, palate, and gingiva are less commonly affected. The color is usually described as grey, brown, blue, black, or a combination of these.Histologically, ephelis shows increased melanin pigmentation in the basal cell layer without an increase in the number of melanocytes; otherwise, the epidermis is normal.
Melanoma
Melanoma is a cancerous condition of the melanocyte. Special corpusles in this cell, known as melanosomes, contain the necessary enzyme (tyrosine) to transform amino acids into melanin. Melanocytes are found among the basal cells of the epidermis. Histopathogically, the mucosal epithelium is abnormal with large atypical melanocytes and excessive melanin. Malignant melanoma of the oral mucosa affects both sexes equally usually after 40 years of age. The great majority of the lesions (about 70-80%) occur on the palate, upper gingival, and alveolar mucosa.Initially there usually is a solitary small asymtomatic brown or black macule.

Physiologic Pigmentation
Physiologic pigmentation of the oral mucosa is clinically manifested as multifocal or diffuse melanin pigmentation with variable prevalence in different ethnic groups.2 Melanin is normally found in the skin of all people. In dark skinned persons the gingiva may contain melanin pigment to a greater extent than the adjacent alveolar mucosa. The melanin pigment is synthesized in specialized cells, the melanocytes, located in the basal layer of the epithelium. The melanin is produced as granules. The melanosomes are stored within the cytoplasm of the melanocytes, as well as in the cytoplasm of adjacent keratinocytes. Melanocytes are embryologically derived from neural crest cells that eventually migrate into the epithelium. If pigmented gingiva is surgically resected, it will often heal with little or no pigmentation; therefore, surgical procedures should be designed so as to preserve the pigmented tissues.

Peutz-Jeghers Syndrome
Peutz-Jeghers syndrome (intestinal polyposis) is a genetic disorder characterized by mucocutaneous pigmentation and hamartomas of the intestine.It manifests itself as frecklelike macules about the hands, perioral skin, and intraorally to include the gingiva, buccal, and labial mucosa. Pigmented spots are 1 to l0 mm in diameter. Pigmented spots are particularly found on the lower lip and buccal mucosa but rarely on the upper lip, tongue, palate, and gingiva.

Smoker’s Melanosis
Smoker’s melanosis is a benign focal pigmentation of the oral mucosa. It tends to increase significantly with tobacco consumption. Tobacco smokers have significantly more oral surfaces pigmented than non-tobacco users.Clinically, the lesion usually presents as multiple brown pigmented macules less than 1 cm in diameter, localized mainly at the attached labial anterior gingival and the interdental papillae of the mandible. Smoker’s melonosis is more common in females usually after the third decade of life.

Antimalaria Drug Use
Several antimalarial drugs are known to be capable of inducing intraoral melanin pigmentation. These drugs include: quinacrine, chloroquine, and hydroxychloroquine Longterm use may cause pigmentation of the oral mucosa. The pigmentation of the oral mucosa is described as slate-grey in color, bearing some resemblance to pigmentation caused by silver arsplenamine.

Minocycline Use
Minocycline is a synthetic tetracycline that is commonly used in the treatment of acne vulgaris.Although tetracycline causes pigmentation of bones and teeth, minocycline alone is also responsible for soft tissue pigmentation.It is usually seen as brown melanin deposits on the hard palate, gingiva, mucous membranes, and the tongue.

Heavy Metals
Heavy metals absorbed systemically from therapeutic use or occupational environments may discolor the gingiva and other areas of the oral mucosa. Bismuth, arsenic, and mercury produce a black line in the gingiva which follows the contour of the margin. Lead results in a bluish red or deep blue linear pigmentation of the gingival margin (Burtonian line). Exposure to silver causes a violet marginal line, often accompanied by a diffuse bluish-grey discoloration throughout the oral mucosa.

Addison’s Disease
Addison’s disease or primary adrenocortical hypofunction is due to adrenocortical damage
and hypofunction.Bronzing of the skin and increased pigmentation of the lips, gingivae, buccal mucosa, and tongue may be seen. Oral pigmentation may be the first sign of the disease.A biopsy of the oral lesions shows acanthosis with silver-positive granules in the cells of the stratum germinativum. Melanin is seen in the basal layer.

Periodontal Diseases
Periodontal diseases often produce discolorations of the oral mucosa. The pigmentation is worsened by gingivitis, which increases vascular permeability and allows the heavy metals access to the soft tissues.51 Melanin re-pigmentation is related to after surgical inury.

Hemachromatosis
Hemachromatosis (bronze diabetes) is a chronic disease characterized by the deposition of excess iron (ferritin and hemosiderin) in the body tissues, resulting in fibrosis and functional insufficiency of the involved organs. Hyperpig mentation may appear both in skin and mucous membranes (oral and conjunctiva). Gingival or mucosal pigmentation is reported to occur in 15 to 25% of patients with hemachromatosis. The oral mucosa shows diffuse homogeneous pigmentation of gray-brown or deep brown in about 20% of the cases. The buccal mucosa and the attached gingiva are the most frequently involved sites.

HIV Infection
In patients infected with human immunodeficiency virus (HIV), progessive hyperpigmentation of the skin, oral mucosa, fingernails, and toenails have been reported being related to primary adrenocortical deficiency and to zidovudine (azidothymidine) therapy in some cases.Clinically, oral pigmentation appears as irregular macules with brown or dark brown color. The tongue, buccal mucosa, and palate are the most commonly affected sites.

Monday, December 22, 2014

Classification of oral diseases of HIV- associated immune suppression (ODHIS)


         Present classification systems for HIV – associated oral lesions developed in the early 1990’s which was named as HAART. Patterns of oral conditions keep on changing very frequently. This highlights the need of new system.

Classification of oral diseases of HIV – associated immune suppression (ODHIS)

System should consider:
·         Changes in epidemiology of oral lesions
·         Therapeutics
·         Development of lesions and immune systems
·         Oral lesions to oral disease

Definition of Oral disease:  abnormality characterized by a defined set of signs and symptoms in the oral cavity, extending from the vermilion border of the lip to the oropharynx, with the exception of salivary gland disease

New Classification- Classification of oral diseases of HIV – associated immune suppression (ODHIS)
Group 1 – ODHIS associated with severe immune suppression (CD4<200 cells/mm3)
Group 2 – ODHIS associated with immune suppression (CD4<500 cells/mm3)
Group 3 – ODHIS assumed associated with immune suppression
A) More commonly observed
B) Rarely reported
Group 4 – Therapeutically-induced oral diseases
Group 5 – Emerging oral diseases
Oral diseases do not belong exclusively to one classification Group
Overlap may exist

Use of the New Classification
·         Identifying undiagnosed individuals
·         Provides additional rationale for HIV testing
·         Affects access and type of HIV-related healthcare
·         Provides clinical markers for therapeutic interventions and efficacy

Group 1. ODHIS associated with severe immune suppression (CD4<200 cells/mm3)
1.      Major recurrent aphthous ulcer
2.      Neutropenia-induced ulcers
3.      Necrotizing ulcerative periodontitis
4.      Necrotizing stomatitis
5.      Cytomegalovirus (CMV)
6.      Chronic HSV
7.      Histoplasmosis
8.      Esophageal, pseudomembranous, and hypertrophic candidiasis
9.      Oral hairy leukoplakia
10.   Kaposi’s sarcoma
11.   Idiopathic Necrotizing Stomatitis    

Hyperplastic candidosis

Oesophageal candidosis

Pseudomembranous Candidosis

Kaposi's Sarcoma

Histoplasmosis
Periodontitis
Neccotizing Sialometaplasia
Chronic HSV

Group 2. ODHIS associated with immune suppression (CD4,500 cells/mm3)
1.       Major recurrent aphthous ulcer
2.       Increased frequency, harder to treat, atypical location
3.       Erythematous candidiasis
4.       Salivary gland disease
5.       Drug induced low salivation
6.       Facial palsy
7.       Neuropathies
8.       Hyposalivation
9.       Human papilloma virus (HPV)
10.   Linear gingival erythema
11.   Non-Hodgkin’s lymphoma
12.   Linear Gingival Erythema

Aptheous Ulcer
HPV

Group 3. ODHIS assumed associated with immune suppression
More commonly observed
1.       Angular candidiasis
2.       Herpes labialis
3.       Intra-oral herpes
4.       Minor aphthous ulcers
Rarely reported
1.       Bacillary epithelioid angiomatosis
2.       Tuberculosis
3.       Deep-seated mycosis (except histoplasmosis)
4.       Molluscum contagiosum
5.       Varicella Zoster Virus (VZV)
6.       HSV Labialis
7.       Intra-oral Herpes
8.       Minor Aphthous Ulcers
Angular Chelitis with candidosis

Group 4. Therapeutically-induced oral diseases

Side-effect
·         Melanotic hyperpigmentation
·         Ulcers
·         Hyposalivation
·         Lichenoid drug reaction
·         Neutropenia-induced ulcers
·         Thrombocytopenia
·         Lypodystrophy-associated oral changes
·         Perioral paresthesia
·         Steven Johnson’s?
·         Exfoliative cheilitis?

Resistance-induced disease
·         Different Candida spp and strains
·         HSV

Antiretrovirals and Adverse Reactions

Antiretroviral Drugs
Indinavir
Saquinavir
Amprenavir
Nevirapine
Delavirdine
Efavirenz
Stavudine
Didanosine

Recurrent HSV
Adverse reactions of antiretroviral drugs
Oral ulcers
Stevens Johnson’s
Taste changes
Dryness
Perioral paresthesia
Thrombocytopenia
Ulcers – Medication Induced
Recurrent HSV

Group 5. Emerging oral diseases
1.       Human papilloma virus, several HPV types (may be associated with immune reconstitution)
2.       Erythema migrans
3.       Variants of Non-Hodgkin’s Lymphoma (NHL B-cell types)
4.       Epithelial neoplasms
5.       Aggressive interproximal dental caries
6.       Condyloma Accuminatum
7.       Squamous Cell Carcinoma

Saturday, December 6, 2014

Upper Limb Anatomy-MCQ


01.Regarding pronator teres which of the following statements is correct?
a)      It forms the lateral border of the cubital fossa
b)      It arises from the coronoid process and lateral epicondyle.
c)      The Median nerve passes deep to both heads
d)     It’s medial border forms the medial boundary of the cubital fossa
e)      It is the most lateral of the superficial flexors of the forearm

02.Regarding the radial nerve which statement is incorrect?
a)      It passes anterior to the lateral epicondyle of the humerus
b)      Injury to the radial nerve from fracture of the shaft of the humerus will result in wrist drop
c)      Injury to the deep radial nerve in the mid forearm will prevent extension only at the MCPJs
d)     Sensory loss from injury to the superficial radial nerve will usually result in loss of sensation over the entire thumb
e)      It is the larger terminal branch of the posterior cord of the brachial plexus


03.Regarding the blood supply of the forearm
a)      The radial artery is the larger of the terminal branches of the brachial artery
b)      The radial artery runs under brachialis as it leaves the cubital fossa
c)      The radial artery has just one named branch proximal to the carpal braches
d)     Ligation of the radial artery at its origin will significantly reduce blood flow through the posterior interosseous artery.
e)      The radial artery has no involvement in the elbow anastomotic network



04The median nerve
a)      Supplies flexor carpi ulnaris and half of flexor digitorum profundis
b)      Gives rise to most of its braches in the upper arm
c)      Gives rise to the common interosseous nerve which divides anterior to the radial head
d)     May be compressed between the two heads of pronator teres
e)      Enters cubital fossa lateral to the brachial artery


Answers

1) E
2) D
3) C
4) D

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