Dinitrophenol causes uncoupling of oxidative phosphorylation

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Biochemistry For Medics 12/13/2012 1

A laboratory technician accidently consumed
Dinitrophenol. Soon after that his body was
observed to be extreme hot. He was sweating
profusely and was extremely thirsty.
What could be the possible reason for these
symptoms ?


 Dinitrophenol is an uncoupler of oxidative
phosphorylation.
 Oxidative phosphorylation is a coupled process,
 The uncouplers allow the oxidation to proceed
but there is no ATP formation.
 The surplus energy that would have been used
up for ATP formation is released in the form of
heat.
 The symptoms in the given patient, high body
temperature, sweating and thirst are due to heat
released by the said uncoupling of oxidative
phosphorylation.


A patient of long standing Diabetes Mellitus
on treatment presents with recurrent
fractures and generalized swelling.
Physical Examination reveals-
 Pallor++
 Puffiness around eyes+
 B.P.- 160/100 mm Hg


Laboratory Investigations-
Blood Biochemistry
Glucose 110 mg/dl
Urea 100 mg/dl
Creatinine 6 mg/dl
Uric acid 8.8 mg/dl
Calcium 6 mg/dl
Hb 6 G /dl


Urine Examination
Color- Normal
Appearance- Clear
Specific Gravity- 1.010
Protein ++
Reducing sugar Nil
What is your probable diagnosis ?


 It is a case of Renal failure, as is evident from
high blood urea and serum creatinine levels.
 Urinary specific gravity (1.010) and proteinuria
are also additional findings in support of
diagnosis.
 It might be a complication of long standing
diabetes mellitus (Diabetic nephropathy ) which
has progressed to renal failure.
 Anemia is due to reduced erythropoietin
secretion from the kidney.
 Fractures and hypocalcemia are due to vitamin D
deficiency. As the last step of activation of
vitamin D takes place in kidney.
 Puffiness is due to water retention.


 A fair chubby boy was brought
to the hospital with the
complaint that he has mental
retardation.
 Blood Biochemistry revealed
that phenyl alanine was
abnormally high.
 Phenyl pyruvate was present in
appreciable amount in urine.
 What is the probable diagnosis
?
 Which other metabolite can be
found in urine ?


 The child is suffering from Phenyl ketonuria
 It is a congenital disorder of phenyl alanine
metabolism.
 Caused due to deficiency of phenyl alanine
hydroxylase enzyme, that converts phenyl
alanine to tyrosine
 In the deficiency of phenyl alanine
hydroxylase, phenyl alanine accumulates in
blood and is also alternatively transaminated
to form phenyl pyruvate, that gets excreted
excessively in urine

 The other metabolites excreted in urine are
phenyl acetyl glutamine and phenyl lactate
 Phenyl pyruvate produced from
transamination reaction can be
decarboxylated to phenyl acetate that is
conjugated with glutamine to form phenyl
acetyl glutamine, which is responsible for
imparting characteristic mousy odor to the
urine
 Phenyl lactate is produced from phenyl
acetate by reduction.


 Sodium Fluoride is used in combination with
potassium oxalate (in the ratio of 1:3) while
sample collection for Blood glucose estimation.
 Glycolysis is said to be inhibited as a result of
inhibition of one of the enzymes of this pathway.
 The results are plotted to depict the mode of
inhibition.


State the type of inhibition and name the
enzyme inhibited by the action of sodium
fluoride

 There is no change in Km, but Vmax has
decreased in the presence of inhibitor.
 It is a non competitive inhibition
 Enolase enzyme that catalyzes the conversion of
2-Phosphoglycerate to Phospho enol pyruvate is
inhibited by sodium fluoride

 Glycolysis is required to be inhibited as
otherwise, glucose of the sample would get
oxidized and falsely low blood glucose values
would be obtained and that happens if sodium
fluoride is not used


(A) (B)

 Out of the two instruments (A and B),Which one is
use for the determination of pH of the solutions ?
 By what other methods, pH of solutions can be
measured ? Biochemistry For Medics 12/13/2012 14

 The instrument (A) is pH meter that can be
used for pH measurement.
 The other instrument (B) is Flame photometer
that is use for the determination of the ions
 pH can also be determined by using
indicators, pH papers, indicator papers and
universal indicator solutions


 Which out of the two glass wares (A and B) is
used for the centrifugation of the biological
fluids ?
 What is the use of the other glass ware ?

(A) (B)


 (A) is cuvette, that is used in the colorimetric
procedures for determination of the
absorbance value of the colored solutions.
 (B) is centrifuge tube, that is used for the
centrifugation of biological fluids.


 The urine test of a patient gave the following
result-
 A purple ring at the junction of two liquids-
 Identify the substance present in the urine .
 Name the test carried out.


 This is Rothera’s test carried out for the
detection of urinary ketone bodies
 A positive reaction is given by acetone and
acetoacetate.
 Beta- hydroxy butyrate does not give a
positive reaction in this test.
 The patient is having ketonuria, that might be
due to uncontrolled diabetes mellitus,
starvation , high fat diet or heavy exercise.


 A 45-year-old obese lady attended the
outpatient department with-
 a history of severe right sided abdominal pain
 vomiting
 fever and yellow tinge of sclera.
 Ultrasound of the abdomen shows the
presence of gall stones.


 State the type of jaundice in this patient ?
 What would be the urinary findings in this patient
?

 Gall stones cause obstruction in the common
bile duct, hence it is obstructive jaundice
 Urine will show the presence of Bilirubin since
it is conjugated hyperbilirubinemia
 Due to obstruction to the outflow of bile
urobilinogen will not synthesized and hence it
would be absent in urine
Note-Only conjugated Bilirubin can appear in
urine. Unconjugated Bilirubin is water
insoluble and is also bound to albumin, hence
can not be filtered to appear in urine.


 The bone marrow smear of a strict vegetarian
female patient presenting with weakness,
fissured tongue and paralysis is displayed.
 Make a diagnosis and suggest the line of
treatment.


 Fissured tongue and megaloblastic anemia are
signs of vitamin B12 deficiency
 The patient is a strict vegetarian that is another
proof of vitamin B12 deficiency
 Neurological manifestations are also
characteristic of B12 deficiency.
 The patient should be treated by a
supplementation of a combination of folic acid
and vitamin B12
 Folic acid and B12 deficiencies always coexist
due to trapping of folate in methylated form in
B12 deficiency (Folate trap )


 A new born baby experienced abdominal
distension, severe bowel cramps and diarrhea
after being fed with milk.
 A hydrogen breath analysis of the exhaled
breath discovered an eighty fold increase in
the production of hydrogen 90 minutes after
milk feeding.


 The urine analysis revealed the presence of a
reducing sugar which formed the characteristic
osazone crystals as shown under the microscope.
 Identify and draw the crystals and mention the
defect.

 The given slide shows lactosazone crystals
(Powder puff).
 The history and clinical features are also
suggestive of Lactose intolerance
 Lactose intolerance is caused due to
deficiency of lactase enzyme
 The undigested lactose is absorbed in the
intestinal cells by pinocytosis that enters
systemic circulation to appear in urine
causing lactosuria.


 An 8-year-old child has been brought to OPD
with pain abdomen and vomiting.
 These episodes often occur upon
consumption of table sugar and sugar
candies.
 A provisional diagnosis of “Hereditary
Fructose Intolerance "is framed for this child.
 There is inability to metabolized fructose in
this disorder


 Which of the two tests would be best suitable
to confirm the presence of fructose in urine ?
 What is the significance of the other test?

Barfoed
Seliwanoff

(A) (B)

 Seliwanoff test is the most confirmatory test
for fructose
 Barfoed test is given positive by all reducing
monosaccharides, it is not a confirmatory test
for fructose
 Keto hexose (Fructose) in the free or bound
form gives this test positive.
 This test is also given positive by Sucrose.


 Which of the two reagents is used for the
detection of urinary chlorides ?
 What is the significance of the other reagent?

Silver Nitrate Mercuric sulphate

(A) (B)

 Silver nitrate (A) is used for the detection of
urinary chlorides
 Mercuric sulphate is used for the detection of
Tyrosine by Millon’s test.
 Chlorides present in urine react with silver
nitrate to form a white precipitate of silver
chloride


Urine Examination report
Name- Mrs. Parvati
Age - 68 years
Sex - Female
Occupation- Housewife
Physical Examination
 Color- Dark yellow

 Appearance- Slightly turbid

 Odor-Aromatic

 Volume – 75 ml

 pH- 7.0
 Specific Gravity- 1.035

Chemical examination
 Reducing sugars- nil
 Proteins- nil
 Ketone bodies- nil
 Blood- nil
 Bilirubin- absent
 Urobilinogen- +++++

Make a probable diagnosis
By which method Urinary Bilirubin can be
detected ?


 Specific gravity is on the higher side probably
due to the presence of urobilinogen
 Dark color of urine is also due to high
urobilinogen content
 There is no Bilirubin.
 Since urine shows the presence of urobilinogen
 There is no other abnormal component
 It is a case of prehepatic jaundice (Acholuric
Jaundice)
 In prehepatic jaundice bilirubin is Unconjugated,
hence can not appear in urine.
 Urinary bilirubin can be detected by Fouchet’s
test


 A child stops making developmental progress
at the age of 2 years and develops coarse
facial features with thick mucus drainage.
Skeletal deformities develop over the next
year, and the child regresses to a vegetarian
state by the age of 10 years.
 The child’s urine is positive for
glycosaminoglycans, that include which of the
followings ?


A. Heparan Sulfate
B. Collagen
C. Glycogen
D. Gamma amino butyric acid


 The right answer is (A).
 The child is most probably suffering from Hurler
syndrome
 Heparan sulfate is the mucopolysaccharide
(Glycosaminoglycan- out of all the options) that
is excreted out in urine in such affected patients
 Collagen is a protein
 Glycogen is a storage form of glucose
 Gamma amino butyric acid is an inhibitory
neurotransmitter
 The last three can not be excreted in urine.


 A 14 –year-old boy was admitted to the
hospital because of sudden pain on the left
flank. Urine analysis reveals hexagonal
crystals.
 24 hours urine sample shows excessive
excretion of Cystine.
 What is the probable diagnosis ?


 It is a case of Cystinuria, an absorption defect
 Cystine, Ornithine , Arginine and Lysine are
excessively lost in urine due to deficiency of
transporter (COAL)
 Cystine is precipitated in acidic urine
 As urine becomes more concentrated in the
kidneys, the excess cystine forms crystals in
acidic pH. As these crystals become larger,
they form stones that may lodge in the
kidneys or in the bladder.


 A chronic alcoholic has been brought to
casualty in a semi-conscious state
Physical examination reveals mild icterus and
moderately enlarged liver
Blood biochemistry reveals-
 High serum Bilirubin
 High blood ammonia level
 Low serum protein level
 A provisional diagnosis of Liver Cirrhosis is
made


1) What is the normal range
of blood ammonia level ?
2) What is the cause of
ammonia intoxication in
brain ?


 Normal blood ammonia level ranges
between-10-80 μg/dl
 Excess of ammonia is detoxified by
conversion of glutamate to glutamine- first
line of defense
 Still excess if present- by conversion of Alpha
keto glutarate to Glutamate
 As a result there is excess of glutamine, but
less of glutamate and Alpha keto glutarate


 Glutamine is exchanged with tryptophan, a
precursor of serotonin, that causes over
excitation
 Low glutamate- Low GABA (Inhibitory
neurotransmitter )- State of hyper excitation
 Low Alpha keto glutarate- TCA cycle
suppressed- Energy depletion
 Patients of ammonia intoxication present with
slurring of speech, blurring of vision,
convulsions, coma and death in untreated
cases.


 Mention the normal reference range of
serum total cholesterol
 Give the names of two cholesterol lowering
drugs to be prescribed to a patient with
hypercholesterolemia
 State two most important causes of
hypercholesterolemia


 Serum total cholesterol ranges between 150-220
mg/dl
 Statins are the most commonly used drugs to
lower cholesterol levels
 The other lipid lowering drugs are- Ezetimibe,
Niacin, Bile acid sequestrants, Fibrates etc
 Hypercholesterolemia is observed in Diabetes
mellitus, Nephrotic syndrome, Hypothyroidism,
Biliary cirrhosis, Obstructive jaundice and in
familial cases (Familial hypercholesterolemia)


 A young man with
hypercholesterolemia was
rushed to the hospital with
crushing chest pain radiating
to the left arm and a probable
heart attack.
The attending physician after
confirmation of the diagnosis
administered streptokinase
injection.
 What is the role of this drug
in heart attack ?

 Streptokinase is given as a fibrinolytic agent in
coronary thrombosis
 It acts by promoting conversion of plasminogen
to plasmin ( that can degrade circulating
fibrinogen) as well as plasminogen that is bound
to a fibrin clot.
 It is given in the first 6 hours of myocardial
infarction to dissolve the clot
 Being non specific in nature, can cause bleeding,
it is largely replaced by t PA (tissue plasminogen
activator) prepared by recombinant DNA
technology.


Interpret from
graph
1) FBS ?
2) Peak value of
blood glucose ?


Urine Analysis Report

Time zero 1/2 1 1hour 2 2hour 3
in 30 s 30
hours mins mins

Urinary + ++ ++++ ++++ ++++ ++++ ++++
sugar

Ketone +++ +++ +++ +++ +++ +++ ++++
bodies

Make a complete diagnosis from the blood and
urinary findings

 Fasting blood glucose is high (135 mg/dl)
 There is delayed peak and the peak value is
also high (200 mg/dl)
 The blood glucose values after half an hour of
glucose load have crossed renal threshold
(160-180 mg/dl)
 Glucose and ketone bodies are there in
almost all the urine samples
 It is a case of diabetic ketoacidosis.


 A 70 year-old female patient was seen in an
emergency service with a chief complaint of
crushing substernal chest pain.
 Her past medical history revealed a diagnosis
of hypertension for five years, for which she
received Captopril 25 mg three times a day.
 Her family history was positive for
hypertension and coronary artery disease.
 What is the basis of using Captopril in this
patient ?


 Captopril is an ACE
inhibitor (Angiotensin
converting enzyme inhibitor)
 Angiotensin II is a potent
vasoconstrictor, by inhibiting
ACE, the formation of
Angiotensins from
Angiotensinogen is inhibited.
 Captopril acts by
competitive inhibition.


Dinitrophenol causes uncoupling of oxidative phosphorylation

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Dinitrophenol causes uncoupling of oxidative phosphorylation