Sweat chloride

Question 1

Principle fo Iontophoresis

Answer 1

sweat glands on a localized are fo skin are activated by TEH iontophoretic introduction fo pilocarpine. In the process fo iontophoresis, an electric potential is established so that pharmacologically active ions carry a current and are thereby introduced into the skin

Question 2

The reagent used in iontophoresis

Answer 2

a positive electrode moistened with pilocarpine NITRATE is used to induce the positively charged pilocarpine radicals to move away from the electrode and into the skin.

Question 3

How is sweat collected?

Answer 3

The pilocarpine stimulated sweat glands respond by producing sweat, which is collected on a piece fo filter paper. and analyzed by using the chloride titrator.

Question 4

Two electrochemical methods involved in chloridometry

Answer 4

coulometric and amperometric

Question 5

The purposes of nitric acid

Answer 5

the sample is diluted in a nitric acetic acid solution to which a small amount of gelatin indicator has been added. provides good electrolytic conductivity

Question 6

The purpose of acetic acid

Answer 6

Essentially renders the silver chloride formed during the titration insoluble by making the solution less polar; thereby yielding a very sharp endpoint. also helps prevent the reduction of silver chloride at the indicator electrode

Question 7

The purpose of gelatin

Answer 7

Produces a smoother, more uniform current flow by equalizing any high spots on the electrode.

Question 8

Coulometric

Answer 8

A constant direct current potential is passed between two silver electrodes in the generator circuit. The amount of electricity produced after all of the substance is reached is quantitated.

Question 9

Amperometric

Answer 9

Current is measured as it flows through the working electrode in an electrochemical cells. a rapid increase in the conductivity of the solution which si detected by a pair of silver electrodes in the indicator circuit.

Question 10

The purpose of sweat chloride testing.

Answer 10

The gold standard test for diagnosis of Cystic Fibrosis.

Question 11

Discuss how the genetic defect present in CF disrupts the functions of the Airways

Answer 11

Clogging and infection fo bronchial passages impede breathing. The infection progressively destroy the lungs. Lung disease accounts for most deaths from CF

Question 12

Discuss how the genetic defect present in CF disrupts the functions of the Liver

Answer 12

Plugging of small bile ducts impedes digestion and disrupts liver function in perhaps 5% of patients.

Question 13

Discuss how the genetic defect present in CF disrupts the functions of the pancreas

Answer 13

Occlusion of ducts prevents the pancreas from delivering critical digestive enzymes to the bowel in 85% of patients. Diabetes can result as well

Question 14

Discuss how the genetic defect present in CF disrupts the functions of the Small intestine

Answer 14

Obstruction fo the gut by thick stool necessitates surgery in about 10% of newborns

Question 15

Discuss how the genetic defect present in CF disrupts the functions of the reproductive tract

Answer 15

Absence fo fine ducts, such as the vas deferens, renders 95% of males infertile. occasionally, women are made infertile by a dense plug of mucus that blocks sperm from entering the uterus.

Question 16

The genetic inheritance of CF

Answer 16

Transmitted as an autosomal recessive trait.

Question 17

Expected range for patients older than 6 months

Answer 17

0-39 mmol/L

Question 18

Expected range for patients up to and including 6 months fo age

Answer 18

0-29 mmol/L

Question 19

Abnormal critical value for any age

Answer 19

> or equal to 60 mmol/L

Question 20

indeterminate range for patients older than 6 months

Answer 20

40-59 mmol/L

Question 21

indeterminate range for patients up to and including 6 months of age

Answer 21

30-59 mmol/L

Question 22

List at least five symptoms that a patient would exhibit that might cause a physician to order sweat chloride analysis

Answer 22

Pulmonary sx- (difficulty breathing-wheezing, rasping, asthma-like sx, decreased pulmonary function, lesions, recurrent respiratory infections, chronic congestion, cough)
Digestive sx- (failure to thrive (poor weight gain), pancreatic insufficiency, frequent bowel movements0 greasy stools-foul odor)
Other sx; meconium ileus, prolapsed rectum, liver disease, nasal polyps

Question 23

List two organisms that are commonly the causative agent for infections present in cystic fibrosis patients.

Answer 23

Staphylococcus aureus and Pseudomonas aeruginosa.

Question 24

List the investigators names associated with this test methodology

Answer 24

Gibson and Crook

Question 25

Explain CFTR

Answer 25

The gene defect for CF affects CFTR, which prevents chloride from being transported across the cell membranes. This will cause the cells to draw water in from the surrounding tissue. In the lungs and digestive tract this will cause the secretions in the area to become thicker than normal as water is drawn from them. This secretion will build up and cause the symptoms of CF