Category: Module

Benzodiazepine

BENZODIAZEPINE


CLASSIFICATION:

  • Long Acting
    • Flurazepam 50-100 t1/2(hrs)
    • Diazepam 30-60 t1/2(hrs)
    • Nitrazepam 30 t1/2(hrs)
    • Flunitrazepam 15-25 t1/2(hrs)
  •  Short-Acting 
    • Temazepam with t1/2 8-12 hrs
      • Benzodiazepine without anticonvulsant property.
    •  Triazolam with t1/2 2-3 hrs
    •  Midazolam 2 t1/2(hrs)
    • Alprazolam 

MOA:

PHARMACOKINETICS:

  • Short-acting BZDs:
  • Eg: Midazolam – IV or IM as an induction agent.
    • Rapid onset of action.
    • Quick drug clearance.
    • Causes anterograde amnesia, tachyphylaxis during high dose infusions.
    • Decreased cardiovascular effects as compared to propofol 
  • Temazepam or oxazepam – Revives insomnia. 
    • At lower doses, relieves acute symptoms of anxiety, such as panic attacks & phobias.
  • Long-acting BZDs: 
    • Slower onset of action following oral administration → Hence prolonged pharmacological action.
    • Sedation.
    • Prevents increased muscle tone of tetanus infection. 
  • Metabolized in liver by dealkylation and hydroxylation.
  • Excreted in urine as glucuronide conjugates.

ACTIONS:

  • Antianxiety
  • Sedation: 
    • Increasing dosage produce sleep & hence considerable as hypnotic
    • I.V administration used extensively to produce conscious sedation during unpleasant procedures. 
    • Eg: Diazepam & midazolam.
    • Cardiovascular stability – IV diazepam 
    • Midazolam potentiates propofol in co-induction technique.
  • Anticonvulsants: 
    • Clonazepam & diazepam – Effective in status epilepticus.
  • Muscle relaxation: 
    • Reduce muscle tone.
  •  Amnesia: 
    • IV benzodiazepines produces antegrade amnesia. 
    • Midazolam – Very intense for 20-30 minutes
    • Lorazepam – Longer amnesia – 6 hr.

DRUGS:

  • Inverse agonist of benzodiazepine receptor – Beta carboline.
  • Benzodiazepine antagonist – Flumazenil

USES:

  • As hypnotic –
    • Daytime sedation (Alprazolam)
  • As anxiolytic.
  • Antidepressant  (Alprazolam)
  • As anticonvulsants, especially emergency control of status epilepticus  
    • To avoid future recurrence of seizure attacks Oral Diazepam 6 hourly is given.
  • As centrally acting muscle relaxant.
  • For anesthetic medication and IV anesthesia 
  • Alcohol withdrawal in dependent subjects 
  • Mostly given along with analgesics (NSAIDs|). 
  • DOC in elderly & with liver disease.
    • Lorazepam, OxazepamTemazepam
  • Spasmolytics.
  • Anti-ulcer.

ADVERSE EFFECT:

  • Dizziness, lassitude, vertigo, disorientation, amnesia, increased reaction time with motor incoordination, impairment of mental coordination occur. 
  • Weakness, blurring of vision, dry mouth and urinary incontinence.
  • BZD poisoning:
    • Benzodiazepine antagonist -Flumazenil
    • Eg: Diazepam poisoning.
  • Paradoxical stimulation, irritability, and sweating may occur with flurazepam.
  • Increase in nightmares and behavioral alterations 
  • Increased psychological effects with usage of short-acting benzodiazepines in insomnia. 
  • Disturbed REM sleep patterns.

Exam Important

  • Diazepam poisoning is treated by Flumazenil
  • Benzodiazepine antagonist  Flumazenil
  • Benzodiazepines of choice in elderly and those with liver disease Lorazepam, Orazepam & Temazepam
  • Shortest acting benzodiazepine is Triazolam
  • Benzodiazepine without anticonvulsant property is Temazepam
  • To avoid future recurrence of seizure attacks Oral Diazepam 6 hourly is given
  • Alprazolam is an anxiolytic benzodiazepine with  antidepressant  action
  • IV diazepam  shows Coronary dilatation
  • Inverse agonist of benzodiazepine receptor is Beta carboline
  • Midazolam causes  Anterograde amnesia, tachyphylaxis during high dose infusions & Decreased cardiovascular effects as compared to propofol
Don’t Forget to Solve all the previous Year Question asked on BENZODIAZEPINE

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Pelvis Musculature

PELVIS MUSCULATURE


 PELVIC MUSCULATURE:

The pelvic muscles of importance in gynaecology are those of the pelvic floor grouped into three layers:

LAYER MUSCLE
Pelvic Diaphragm 2 levator ani muscles

  • Pubococcygeus
  • Iliococcygeus
  • Ischiococcygeus
Obturator internus
Puborectalis
Urogenital Diaphragm Sphincter urethra

Deep transverse Perineal

Compressor urethra

Superficial Layer Superficial transverse Perineal

Ischiocavernous

bulbospongiosus

The external
sphincter muscle of the anus

Muscle Origin Insertion
Pubococcygeus Post. Pubic bone Anococcygeal raphe and coccyx
Iliococcygeus white line of the pelvic fascia coccyx.
Ischiococcygeus ischial spine coccyx
Obturator internus Pelvic aspect of ischium & ilium

Obturator membrane

 Greater trochantor of femur
Puborectalis  Posterior surface of pubis   Midline sling posterior to rectum
Sphincter urethra   Circular anatomical sphincter  Fuses with deep transverse perinei
Compressor urethra  ischiopubic ramus Blends with its partner on the other side

anterior to urethra

below external urethral sphincter

Superficial transverse Perineal  Ischial tuberosity   Perineal body
Ischiocavernous   Ischial tuberosity  Clitoris
bulbospongiosus  Central point of  perineum  symphysis pubis
Deep transverse Perineal  Ramus of ischium  Perineal body
The external
sphincter muscle of the anus
Central point of the perineum Surrounds the anus

ACTION OF MUSCLES:

The roles of the pelvic floor muscles are:

  • Support of abdominopelvic viscera (bladder, intestines, uterus etc.) through their tonic contraction.
  • Resistance to increases in intra-pelvic/abdominal pressure during activities such as coughing or lifting heavy objects.
  • Urinary and fecal continence.The muscle fibers have a sphincter action on the rectum and urethra. They relax to allow urination and defecation.Puborectalis is essential to maintain continence

Exam Important

  • Muscles that can cause external rotation of the hip include Obturator internus
  • Pubovaginalis, External urethral sphincter & Bulbospongiosus are sphincters of lower genito urinary tract of female 
  • Pelvic diaphragm is formed by Pubococcygeus,Iliococcygeus & Pubovaginalis
  • Urogenital Diaphragm is made up of Sphincter urethrae , Perineal membrane & Deep transverse Perineal muscle
  • Superficial perineal muscles include Bulbospongiosus
  • Lateral border of ischeorectal fossa is formed by Obturator internus
  • Puborectalis is essential to maintain continence
  • Sphincter urethrae is Voluntary, Arises from ischiopubic ramus and are Supplied by pudendal nerve
  • Pubococcygeus supports prostate
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TUBERCULOSIS OF SPINE (Pott’s disease)

TUBERCULOSIS OF SPINE (Pott’s disease)


TUBERCULOSIS OF THE SPINE  (Pott’s disease)

  • The spine is the commonest site of bone and joint tuberculosis.
  • Dorso-lumbar region affected most frequently.

Types of vertebral tuberculosis:

1. Paradiscal: commonest type

2. Central:

  • Single vertebra is affected.
  • This leads to early collapse of the weakened vertebra.
  • The nearby disc may be normal.
  • The collapse may be a ‘wedging’ or ‘concertina’ collapse 

 3. Anterior:

  • infection is localised to the anterior part of the vertebral body.

 4. Posterior:

  • the posterior complex of the vertebra i.e., the pedicle, lamina, spinous process and transverse process are affected.

CLINICAL FEATURES

  • Pain (back pain)
  • Stiffness
  • Cold abscess
  • Paraplegia
  • Deformity: increasing prominence of the spine – gibbus.
  • Constitutional symptoms: Symptoms like fever, weight loss etc.

RADIOLOGICAL INVESTIGATIONS

X-ray examination:

  • Reduction of disc space: earliest sign  
  • Destruction of the vertebral body 

Evidence of cold abscess:

1). Para-vertebral abscess-

  1. fusiform para-vertebral abscess (bird nest abscess – an abscess whose length is greater than its width (Fig-23.7a);
  2. globular or tense abscess – an abscess whose width is greater than the length

2). Widened mediastinum-

3). Retro-pharyngeal abscess

4). Psoas abscess

  • Rarefaction: diffuse rarefaction of the vertebrae above and below the lesion.
  • Unusual signs: erosion of the posterior elements of pedicle, lamina etc.
  • Signs of healing

CT scan:

  • very useful investigation in cases presenting as ‘spinal tumour syndrome’.

MRI:

  • Investigation of choice to evaluate the type and extent of compression of the cord.

Other investigations:

  • ESR, Mantoux test, ELISA test for detecting anti- tubercular antibodies, chest X-ray, etc.,

COMPLICATIONS

  1. Cold abscess:  commonest complication of TB of the spine.
  2. Neurological compression: At times the patient presents as a case of spinal tumour syndrome.
  • First clinical symptom being a neurological deficit.

Exam Important

  • Tuberculosis in Pott’s disease involves Spine.
  • Pott’s spine is commonest at Thoracolumbar spine.
  • Tuberculosis of spine is common at Thoracolumbar.
  • Most common cause of cold abscess of chest wall is Pott’s spine.
  • Commonest presenting symptom of Pott’s spine is Back pain.
  • The paradiscal type is M/C type of vertebral tuberculosis.
  • Wedging or Concertina collapse: in central type.
  • Pott’s disease: M/C cause for kyphosis & cold abscess.
  • Earliest radiological sign of spine tuberculosis is reduction of intervertebral disc space.
  • M/C complication of spine tuberculosis cold abscess.
  • Investigation of choice- MRI.
  • M/c performed surgery- Antero lateral decompression.
  • TB of spine à bony ankylosis, other bones & joints a fibrous ankylosis.
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Cesarean Section

Cesarean Section


DEFINITION:

  • It is an operative procedure whereby the fetuses after the end of 28th weeks are delivered through an incision on the abdominal and uterine walls.

FACTORS FOR RISING CESARIAN SECTION RATE:

  • Rising incidence of primary cesarean delivery
  • Identfication of at risk fetuses before term (FGR)
  • Identfication  of high-risk pregnancy
  • Wider use of repeat CS
  • Rising rates of induction of labor and failure of induction
  • Decline in operative vaginal delivery & vaginal breech delivery
  • Increased number of women with age >30 years
  • Wider use of electronic fetal monitoring and increased  diagnosis of fetal distress
  • Fear of litigation

INDICATIONS:

Absolute Indications:

  • Vaginal delivery is not possible
  • Central placenta previa
  • Contracted pelvis or cephalopelvic disproportion
  • Pelvic mass
  • Advanced carcinoma cervix
  • Vaginal obstruction

Relative Indications:

  • Previous cesarean delivery
  • Fetal distress
  • Dystocia
  • Antepartum hemorrhage
    • Placenta previa
    • Abruptio placenta
  • Malpresentation
  • Failed surgical induction
  • Recurrent fetal loss
  • Hypertensive disorders
  • Medical-gynecological disorders
    • Diabetes
    • Coarctation of aorta
    • MS, AR, AS
    • Marfan’s syndrome
    • Mechanical obstruction

TYPES OF OPERATIONS:

  • Lower segment CS.
  • Upper segment (classical) CS.
  • Modified classical (de-lee) CS.

Lower segment cesarean section (LSCS):

PATIENT PREPARATION

  • Counseling.
  • Written informed consent.
  • Pre-operative evaluation.
  • Preparation of incision area
  • Bladder catheterization
  • Blood arrangements
  • Antibiotics
  • Heparin therapy.

PATIENT PREPARATION IN OPERATION THEATRE

  • Left lateral tilt at least 15 degree
  • Oxygen inhalation
  • Pediatrician should be available
  • Auscultation of fetal hearts before starting.

ANESTHESIA

  • General anesthesia
  • Spinal anesthesia
  • Epidural anesthesia
  • Local infiltration.

SKIN INCISIONS :

  • Pfannenstiel incision
  • Joel-Cohen incision.
  • Midline incision
  • Para-median incision

Uterine incision:

  1. Peritoneal incision: Transverse cut  across lower segment with convexity downwards
  2. Muscle incision:  Low transverse(90%):Slightly below peritoneal incision
  • Ease of operation
  • Less bladder dissection
  • Less blood loss
  • Easy to repair
  • Complete reperitonization
  • Less adhesion
  • Less risk of scar rupture

Other:

  • Lower vertical
  • Classical incision (upper segment).
  • “J” incision
  • Inverted “T” incision

PROCEDURE:

  • Two index fingers are then inserted through the incision down to the membranes and the muscles of the lower segment are split transversely.

Delivery of the head:

  • Membranes are ruptured
  • Suction of blood mixed amniotic fluid
  • Hooking the head with fingers by elevation and flexion using the palm
  • If the head is jammed push up the head by fingers introduced into the vagina
  • Wrigley’s or Barton’s forceps  also be used
  • Mucus from the mouth, pharynx and nostrils is sucked

Delivery of the trunk

  • After delivery of shoulders IV oxytocin 20 units or methergine 0.2 mg is to be administered
  • Head tilted down for gravitational drainage
  • Cord is cut between two clamps
  • The Doyen’s retractor is reintroduced.
  • The optimum interval between uterine incision and delivery should be less than 90 seconds.

Removal of the placenta and membranes:

  • Traction on the cord with simultaneous pushing of the uterus towards the umbilicus per abdomen using left hand

Suture of the uterine wound:

  • Allis tissue forceps or Green Armytage hemostatic clamps are used to pick margins of the wound

The uterine incision is sutured in three layers:

First layer:

  • Suture material is No “0” chromic catgut or vicryl
  • Continuous running suture taking deeper muscles excluding or including the decidua

Second layer:

  • Continuous suture placed taking superficial muscles and adjacent fascia overlapping first layer of suture.
  • Uterine muscles may be closed  taking full thickness muscle and decidua
  • The peritoneal flaps may be apposed by continuous inverting suture
  • Concluding part: The mops placed inside are removed and the number verified.
  • Peritoneal toileting is done and the blood clots are removed meticulously
  • After being satisfied that the uterus is well contracted, the abdomen is closed in layers.

CLASSICAL CESAREAN SECTION:

  • Abdominal incision is always longitudinal (paramedian)12.5 cm (5″) starting from below the fundus
  • Delivery commonly as breech extraction.
  • The uterus is eventrated.
  • The placenta is extracted by traction on the cord or removed manually
Lower Segment Classical
Techniques Difficult Easy
Blood loss is less More
Wall is thin and as such apposition is perfect Wall is thick and apposition of the margins is imperfect
Perfect peritonization  possible Not possible
Technical Difficulty in placenta previa or transverse Comparatively safer
Post-operative Less Hemorrhage and shock More
Peritonitis is less More
Convalescence is better Relatively delayed
Morbidity and mortality are much lower Morbidity and mortality are high
Less Peritoneal adhesions and intestinal obstructions More
Wound healing Perfect muscle apposition Imperfect
Minimal wound hematoma More
Wound  Quiescent during healing process Wound in state of tension
Chance of gutter formation is unlikely More
During future
pregnancy
Scar rupture(0.5–1.5%) More risk of scar rupture(4–9%)

COMPLICATIONS:

Maternal:

INTRAOPERATIVE::

  • Extension of uterine incision
  • Uterine lacerations
  • Bladder injury
  • Ureteral injury
  • Gastrointestinal tract injury
  • Hemorrhage
  • Morbid adherent placenta (placenta accreta)

POSTOPERATIVE COMPLICATIONS:

IMMEDIATE:

  • Postpartum hemorrhage
  • Shock
  • Anesthetic hazards:Mendelson’s syndrome
  • Infections
  • Intestinal obstruction
  • Deep vein thrombosis and thromboembolic disorders

Wound complications:

  • Sanguineous or frank pus
  • Hematoma
  • Dehiscence
  • Burst abdomen
  • Necrotizing fasciitis
  • Secondary postpartum hemorrhage

REMOTE:

  • Gynecological: Menstrual excess or irregularities, chronic pelvic pain or backache.
  • General surgical: Incisional hernia, intestinal obstruction due to adhesions and bands.
  • Future pregnancy: There is risk of scar rupture

FETAL:

  • Iatrogenic prematurity
  • RDS
  • MATERNAL AND PERINATAL MORTALITY

Exam Important

  • Indications for caesarean section in pregnancy are Aortic stenosis, M.R. & Aortic regurgitaion
  • Lower Segment Caesarean section (LSCS) can be carried out under  
    • General anaesthesia 
    • Spinal anaesthesia 
    • Combined Spinal Epidural anaesthesia
  • Absolute indication for caesarean section in pregnancy are
    •  Advanced Carcinoma Cervix 
    • Central Placenta Praevia 
    • Contracted Pelvis
  • History of previous classical CS  is the contraindication for trial of normal labour after caesarean section
  • Cephalopelvic disproportion is an absolute indication for Caesarean section.
  • In classical caesarean section more chances of rupture of uterus is in Upper uterine segment
  • Best management in Mento-posterior presentation Caesarean section
  • Absolute indication for caesarean section is Type IV placenta previa
  • Ideal management of a 37 weeks pregnant elderly primigravida with placenta praevia and active bleeding is Caesarean section
  • Placenat accrete complicates third stage of labour and is associated with a past history of caesarean section
  • Incidence of scar rupture in previous lower segment caesarean section 1%
  • Risk of rupture of uterus with previous classical caesarean section is 4-8%
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Enzyme Inhibition

ENZYME INHIBITION


ENZYME INHIBITION

  • Enzyme inhibitor binds with enzyme and decreases a catalytic activity.

Types of Enzyme Inhibition-

  1. Reversible
  2. Irreversible
  3. Allosteric
  4. Reversible Inhibition– binds through non-covalent bonds and activity of enzyme is restored. Divided into-

a) Competitive inhibitorKm increased, Vmax unchanged.

  • E.g.- Succinate dehydrogenase by melanate.

b) Non competitive inhibitor- Km unchanged, Vmax decrease, mostly irreversible.

  • E.g.- Cyanide by Cytochrome C Oxidase.
  • Carbonic anhydrase by Acetazolamide

2. Irreversible Inhibition– binds covalently with an enzyme.

a) Suicidal Inhibitor– irreversible binding to enzyme and inhibit enzyme.

  • E.g. Allopurinol inhibit Xanthine oxidase, cyclooxygenase.

3. Feedback Inhibition- called as end product inhibition.

  • E.g. AMP inhibits first step in purine synthesis.

Exam Important

  1. Reversible Inhibition- binds through non-covalent bonds and activity of enzyme is restored.
  2. Competitive inhibitor- Km increased, Vmax unchanged.
  3. Competitive inhibitor- Succinate dehydrogenase by melanate.
  4. Non competitive inhibitor- Km unchanged, Vmax decrease, mostly irreversible.
  5. Non competitive inhibitor- E.g.- Cyanide by Cytochrome C Oxidase.
  6. Suicidal Inhibitor- Allopurinol inhibit Xanthine oxidase.
Type of inhibitor Km Vmax
Reversible inhibbitor Increased No effect
Competitive No effect Decreased
Non-competitive Decreased Decreased
Uncompititive No effect Decreased
Irrversible inhibitor (same as reversible Increased No effect
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Codons & Genetic code

Codons & Genetic code


CODON &GENETIC CODE

  • Codon- is a sequence of three adjacent bases that corresponds to one of the amino acid.
  • There are 64 possible codon of sequence.
  • Four nucleotide bases A, G, C and U.
  • If 4 bases 44 = 256 amino acids.
  • Methionine has only 1 codon.
  • Genetic code is the system of nucleotide sequences of mRNA that determines the sequence of amino acids in protein.
  • Characteristics of genetic codes-

1.  Triplet codon– each amino acid has triplet sequence.

2. Degenerate (Redundant)

  • A given amino acid may have more than one codon.
  • Degeneracy of the codon lies in the 3rd base.

3. Universal– a specific codon represent a specific amino acid in all the  species.

  • Genetic coder are found in human mitochondria, code is-
  1. AUA codes for methionine instead of isoleucine.
  2. AGA and AGG serve as as stop codon.
  3. UGA also codes for Selenocysteine, a mechanism called translational recording.

4.Unambiguous/ Specific– a particular codon always codes for the same amino acid

5. Non overlapping and nonpuntate (comma less)– reading of genetic code does not involve overlapping sequence.

  • E.g.- AUGCUA GACUUU reads as AUG/CUA/GAC/UUU without punctuation (comma) between codons.

6. Stop or termination or nonsense codons

  • The three nucleotide triplets do not code for any amino acid are- UAA (amber), UAG (ochre), UGA (opal) called as nonsense codons that normally signal termination of polypeptide chains.
  • Wobble Hypothesis- states that a single tRNA can recognise more than one codon.
  • Base pairing of 3rd base of codon (at 31 end) often fails to recognize the specific complementary base codon (at 51 end at tRNA)
  • Wobble explains the degeneracy of genetic code.
  • A minimum of 31 tRNAs are required to translate all 61 different codons for the amino acids.
  • Gene- is the smallest functional unit of genome. 2 types
  1. Inducible gene
  2. Constitutive gene (housekeeping genes)- genes whose expression is not regulated
  • Cistron- is the smallest unit of genetic expression.
  • The codons that designate the same amino acid are called synonyms.

 Exam Important

  • Information for synthesis of protein is contained in the mRNA.
  • Thymine is not involved in codons.
  • 64 (43) possible codon sequences.
  • tRNA acts as the adapter molecule between the codon and specific amino acid.
  • UUU is the codon for phenylalanine.
  • Degeneracy of the codon lies in the 3rd base.
  • Amino acid with maximum number codons are Serine, Arginine, Leucine.
  • Monocistronic- e.g. eukaryotic mRNA
  • Polycistronic- e.g. Prokaryotic mRNA
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Phospholipids

PHOSPHOLIPIDS


PHOSPHOLIPIDS

  • Phospholipid= Fatty acid+ Glycerol+Phosphoric acid+ nitrogenous base
  • Function is transduction of signals in cell membrane.

2 types-

  1. Glycerophospholipids
  2. Sphingophospholipids

1. Glycerophospholipids (phosphoglycerides)- that contains glycerol as alcohol. They are-

a) Phosphatidylcholine (lecithin)

  • Most abundant phospholipids in cell membrane.
  • Dipalmitoyl lecithin in lungs
  • Insufficient production of Dipalmitoyl lecithin- acute pulmonary distress syndrome in premature infants.

b) Phosphatidylethanolamine (Cephalin)- contains ethanolamine.

c) Plasmogens- platelet activating factor

d) Cardiolipin (Diphosphatidylglycerol) – is a major lipid of inner mitochondrial membrane.

  • It has antigenic properties (only humans).
  • Deficiency causes- Barth syndrome.

Exam Important

1.Glycerophospholipids (phosphoglycerides)- that contains glycerol as alcohol. They are-

a) Phosphatidylcholine (lecithin)

  • Most abundant phospholipids in cell membrane.
  • Dipalmitoyl lecithin in lungs
  • Insufficient production of Dipalmitoyl lecithin- acute pulmonary distress syndrome in premature infants.

 b) Phosphatidylethanolamine (Cephalin)- contains ethanolamine.

c) Plasmogens- platelet activating factor

d) Cardiolipin (Diphosphatidylglycerol) – is a major lipid of inner mitochondrial membrane.

  • It has antigenic properties (only humans).
  • Deficiency causes- Barth syndrome.
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Severe Combined Immunodeficiency (Scid)

SEVERE COMBINED IMMUNODEFICIENCY (SCID)


SEVERE COMBINED IMMUNODEFICIENCY (SCID)

It is caused due to –

  • Deficiency of Adenosine Deaminase (ADA)
  • Adenosine accumulates and converted to ribonucleotides and deoxyribonucleotides (dATP).
  • dATP inhibits ribonucleotidereductase which decreases production of deoxyribose nucleotides.
  • There is decrease in T and B cells leading to immunodeficiency.
  • X Linked Type is the Most Common Pattern of Inheritance

Clinical features-

  •  Chronic diarrhea
  •   failure to thrive.

Treatment-

  • Gene therapy is the first order to be treated.
  • Enzyme Replacement Therapy with Polyethyleneglycol modified bovine adenosine deaminase (PEGADA).

Exam Important

  • There is a decrease in T and B cells.
  • Adenosine accumulation is seen in SCID.
  • DNA synthesis decreases.
  • X Linked Pattren of Inheritance is most common
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Metabolism of Triacylglycerol

Metabolism of Triacylglycerol


METABOLISM OF TRIACYLGLYCEROL

  • Triacylglycerol contains one molecule of glycerol and 3 molecules of fatty acid.
  • Occurs in liver, adipose tissue, intestinal mucosal cells.
  • Organelle- endoplasmic reticulum.

3 steps-

  1. Fatty acid to acyl CoA by Acyl CoA synthase (thiokinase)
  2. Glycerol to glycerol-3-phosphate (formed from glucose-3- phosphate dehydrogenase in adipose tissue) by glucose kinase.
  3. Phosphatidate undergoes hydrolytic dephosphorylation which is esterified to form triacylglycerol.
  • In adipose tissues- insulin enhances triacylglycerol synthesis.
  • In Diabetes, glycerol-3-phosphate is hampered leading to decrease triglyceride synthesis.
  • Triglyceride is the major lipid for adipose tissues.

Triacylglycerol hydrolysis (lipolysis)-

  • Triacylglycerol (stored fat) is degraded.
  • Enzyme- hormone sensitive lipase.
  • Lipolysis refers to hydrolysis of triacylglycerol in adipose tissues.

Regulation of lipolysis-

  1. Hormone sensitive lipase activated by-
  2. Epinephrine
  3. Catecholamines
  4. Thyroid hormones
  5. Growth hormone
  6. ACTH
  7. Glucocorticoids

Hormone sensitive lipase inactivated by-

  1. Insulin
  2. Prostaglandin

Exam Important

  • Triacylglycerol contains one molecule of glycerol and 3 molecules of fatty acid.
  • Occurs in liver, adipose tissue, intestinal mucosal cells.
  • Organelle- endoplasmic reticulum.

3 steps-

  1. Fatty acid to acyl CoA by Acyl CoA synthase (thiokinase)
  2. Glycerol to glycerol-3-phosphate (formed from glucose-3- phosphate dehydrogenase in adipose tissue) by glucose kinase.
  3. Phosphatidate undergoes hydrolytic dephosphorylation which is esterified to form triacylglycerol.
  • In adipose tissues- insulin enhances triacylglycerol synthesis.
  • In Diabetes, glycerol-3-phosphate is hampered leading to decrease triglyceride synthesis.
  • Triglyceride is the major lipid for adipose tissues.
  • Triacylglycerol hydrolysis (lipolysis)-
  • Triacylglycerol (stored fat) is degraded.
  • Enzyme- hormone sensitive lipase.
  • Lipolysis refers to hydrolysis of triacylglycerol in adipose tissues.

Regulation of lipolysis-

Hormone sensitive lipase activated by-

  1. Epinephrine
  2. Catecholamines
  3. Thyroid hormones
  4. Growth hormone
  5. ACTH
  6. Glucocorticoids

Hormone sensitive lipase inactivated by-

  1. Insulin
  2. Prostaglandin
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Lesch- Nyhan Syndrome

LESCH- NYHAN SYNDROME


LESCH- NYHAN SYNDROME

Main Features

  • It is X-linked Recessive disorder.
  • It is caused due to complete deficiency of Hypoxanthine guanine phosphoribosyl transferase (HGPRT deficiency).
  • It affects only males.
  • Increased production of purine nucleotide from PRPP via De Novo pathway.
  • Purine degraded into uric acid and its level increases.

Clinical features

  • Hyperuricemia
  • Gouty arithritis
  • Urinary stones
  • Intellectual disability
  • Dystonic movement
  • Dysarthric speech
  • Self mutilation (irresistible urge to bite the fingers and lips)
  • Megaloblastic anaemia

Diagnosis

  • Hyperuricemia
  • HGPRTase enzyme acitivity in RBCs is deficient

Treatment

  • Allopurinol
  • Alkalanization of urine
  • High fluid intake

Exam Important

  • It is a sex linked disorder. (X Linked Recessive Disorder)
  • The structural gene of HGPRT is located on X-chromosome.
  • There is a complete deficiancy of HGPRT 
  • Self mutilation is one of the characteristic feature of the syndrome.
  • Allopurinol is used in the treatment.
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