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Biomedical subjects

R Chadha

Publications and source records attributed to R Chadha.

At least 19 recordsLinked to original sources
PubMed2005

The histopathology of congenital pouch colon associated with anorectal agenesis.

The colonic pouch excised during surgery in 17 patients with congenital pouch colon associated with anorectal agenesis (CPC) was subjected to detailed histological examination after staining with hematoxylin and eosin. The patients included 11 newborns, 3 infants, and 3 older children. The most frequently observed abnormalities were acute and chronic inflammation of the mucosa and submucosa, focal or generalized thinning of muscle layers, especially of the outer muscle coat, disorganized muscle layers, a decreased number of mature ganglion cells, and neuronal hyperplasia and hypertrophy in nerve plexuses. Ectopic heteroplastic tissues were identified in 2 patients. These findings suggest that the colonic pouch in CPC represents abnormally developed colonic tissue and points to the similarity with segmental dilatation of the colon. The neuromuscular abnormalities explain the physiological characteristics of the colonic pouch, namely weak peristalsis as well as the propensity to undergo marked dilatation even after tubularization.

Child, Preschool↗
PubMed2004

Microcalorimetric evaluation of the in vitro compatibility of amoxicillin/clavulanic acid and ampicillin/sulbactam with ciprofloxacin.

Solution calorimetric technique has been used to determine the compatibility of binary and ternary systems of ampicillin trihydrate (AMP), sulbactam sodium (SS), amoxicillin trihydrate (AM), potassium clavulanate (PC) and ciprofloxacin hydrochloride (CP). The enthalpy of solution (DeltasolH) were obtained over a wide range of composition in the pH range 2-9. For all the pure drugs the DeltasolH is endothermic in nature. The molar enthalpies of interaction of binary (DeltaHbi.E) and ternary (DeltaHter.E) mixtures of the drugs in aqueous buffers have been determined. The DeltaHbi.E for all binary systems is negative and pH dependent (maximum pH 6-8) indicating the interaction among charged species of the drugs. In case of binary systems with CP the magnitude of DeltaHbi.E indicate strong interactions. The variation and magnitude of DeltaHbi.E for the systems is discussed in terms of hydrogen bonding and van der Waal's interaction in the solution. The interaction parameter for ternary systems (A) is positive indicating repulsive interaction among the drugs. The coefficients hi's calculated from Redlich-Kister equation for binary systems (DeltaHbi.E) and ternary interaction parameter (A) were used to predict the compatibility of the marketed formulations in pH range studied.

Algorithms↗
PubMed2003

Microcalorimetric studies to determine the enthalpy of solution of diclofenac sodium, paracetamol and their binary mixtures at 310.15 K.

A sensitive and selective microcalorimetric technique has been used to determine the enthalpy of solution of diclofenac sodium (DS), paracetamol (PC) and their binary mixtures over a wide range of composition in the pH range 4-12. The systems showed endothermic behavior. The molar enthalpies of solutions of DS vary between 42.26+/-0.16 and 50.48+/-0.03 kJ mol(-1) at pH 4-9 and for PC from 24.28+/-0.05 to 36.03+/-0.01 kJ mol(-1) at pH 5-12. The excess molar enthalpy of their mixtures has also been determined. The values of excess molar enthalpy of solutions are negative and very low in magnitude indicating no specific interaction between DS and PC in solution.

Acetaminophen↗
PubMed2003

Kinetic studies of the degradation of an aminopenicillin antibiotic (amoxicillin trihydrate) in aqueous solution using heat conduction microcalorimetry.

Recent developments in isothermal microcalorimetry allow the direct determination of kinetic and thermodynamic parameters for slow reactions from studies conducted at appropriate temperatures and under designated environmental control. The degradation kinetics of amoxicillin trihydrate has been investigated as a function of pH (1-10) and temperature (303.15-318.15 K) at 0.5 M ionic strength using heat conduction microcalorimetry. Equations were developed incorporating calorimetric accessible data, rate constants and change in enthalpy, which showed that the degradation of amoxicillin trihydrate in aqueous solution followed pseudo-first-order kinetics under our experimental conditions. The enthalpy of degradation reaction was found to be exothermic in nature. The values of the rate constant k for individual steps were determined from the values of the overall rate constants at different pH. Energy of activation of overall reaction as a function of pH and for individual rate constants was determined. The log k-pH profiles indicated specific-acid and specific-base catalysis and there were inflection points near pH 3 and pH 7 corresponding to the pKa1 and pKa2 values. Quantitatively, there was good correlation between calorimetric determined half-life (t1/2) and the literature value in the acidic region determined by other methods at 310.15 K. The presence of a beta-lactam ring and of an alpha-amino group in the C-6 side chain played a critical role in the degradation of amoxicillin trihydrate and the zwitterionic form of the drug was found to be more stable.

Amoxicillin↗
PubMed2003

Kinetics of degradation of diclofenac sodium in aqueous solution determined by a calorimetric method.

An isothermal heat conduction microcalorimeter has been used to study the stability of diclofenac sodium both alone and its inclusion complex with beta-cyclodextrin in aqueous solution. The rates of heat evolved during degradation of diclofenac sodium have been measured by a highly sensitive microcalorimetric technique as function of concentration, pH and temperature. The calorimetric accessible data have been incorporated in the equations for determination of rate constants, change in enthalpy and order of reaction. The decomposition of diclofenac sodium both alone and its inclusion complex with beta-cyclodextrin in solution corresponds to a pseudo-first order reaction. The values of rate constants, k's at 338.15 K, (calculated from the variation of heat evolution with the time) for the degradation of diclofenac sodium at pH 5, 6, 7, 8 and its inclusion complex with beta-cyclodextrin at pH 7 are found to be 4.71 x 10(-4), 5.69 x 10(-4), 6.12 x 10(-)4, 6.57 x 10(-4) and 4.26 x 10(-4) h(-1) respectively. There is good agreement between calorimetric determined t(0.5) and literature values. It has been found that beta-cyclodextrin retards the degradation of diclofenac sodium. The kinetic parameters have been calculated for the reaction. The negative entropy of activation suggests the formation of an ordered transition state.

Algorithms↗
PubMed2002

Calorimetric studies of diclofenac sodium in aqueous solution of cyclodextrin and water-ethanol mixtures.

The technique of solution calorimetry has been employed to study the interaction between diclofenac sodium and beta-cyclodextrin by determining the enthalpies of solution of the drug in water and in aqueous beta-cyclodextrin solution. Thermodynamic parameters characterizing the binding process such as enthalpy deltaH0, equilibrium constant K, free energy deltaG0 and entropy deltaS0 have been calculated to be 12.00 kJ mol(-1), 1670 dm3 mol(-1), -19.03kJ mol(-1) and 22.98 J K(-1) mol(-1), respectively. Enthalpies of solution of diclofenac sodium have also been determined in water-ethanol mixtures.

Algorithms↗
PubMed2001

Two cases of pseudoduplication of the external genitalia.

In two newborn boys an accessory rudimentary phallus and scrotal sacs were present on the surface of a midline perineal swelling. Both boys had an associated high anorectal anomaly (ARA), a small phallus, and a bifid scrotum with absence of the scrotal raphé. One also had penile torsion with hypospadias and an accessory anal dimple. During definitive surgery for the ARA in one patient, excision of the perineal soft-tissue mass and overlying duplicated penoscrotal tissue was performed. The embryogenesis of this condition is discussed.

Abnormalities, Multiple↗
PubMed2001

Female pseudohermaphroditism associated with cloacal anomalies: faulty differentiation in the caudal developmental field.

A 1(1/2)-year-old girl with a urogenital sinus defect associated with an enlarged phalluslike clitoris is described. The child had an anteriorly located anus, a single kidney with grade III vesicoureteric reflux, a 3.5-cm-long common urethrovaginal channel, a large vesical calculus, and a hamartoma in the pubic region. After a preliminary colostomy, definitive surgery consisted of urethral reconstruction, vaginal reconstruction using a colonic graft, and posterior relocation of the anus. The discussion centers on a review of the previously reported cases of female pseudohermaphroditism associated with cloacal or urogenital sinus defects (FPHCD). The likely embryogenesis of this condition is discussed, and the similarity of the features with those seen in some patients with complete penoscrotal transposition (CPST) is highlighted.

Anal Canal↗
PubMed2001

Complete diphallia associated with features of covered exstrophy.

This report describes a 1-day-old boy with complete true diphallia associated with features of covered or pseudo-exstrophy and an anorectal malformation. The urinary bladder and rectum were single. A divided sigmoid colostomy was constructed at birth for the anorectal anomaly. Complete diphallia and its likely embryogenesis are discussed.

Anal Canal↗
PubMed2001

Congenital pouch colon associated with segmental dilatation of the colon.

A 1-day-old boy who presented with an anorectal malformation (ARM) was found to have a segmental dilatation of the colon (SDC) associated with a typical congenital pouch colon (CPC) malformation. The distal colonic pouch terminated in a high colovesical fistula. The posterior portion of the perineal raphé was duplicated and ended in 2 anal dimples. Both dilated segments of the colon were excised. The similarity between CPC and SDC is highlighted, and the possible embryogenesis of both conditions is discussed.

Colon↗
PubMed2000

Enthalpies of solution of ampicillin, amoxycillin and their binary mixtures at 310.15 K.

Enthalpies of solutions of ampicillin, amoxycillin and their binary mixtures have been determined at pH 2, 5, and 7 using C-80 calorimeter. The systems showed endothermic behaviour; molar enthalpies of solutions of ampicillin were determined to be 13.32, 15.89 and 23.21 kJ mol(-1) and amoxycillin were 16.32, 18.45 and 26. 25 kJ mol(-1) at pH 2, 5, and 7, respectively. The excess molar enthalpies of solution have also been calculated to find any interaction between these two drugs.

Amoxicillin↗
PubMed1999

Congenital pouch colon in females.

From January 1995 to March 1998, congenital pouch colon (CPC) with anorectal agenesis was diagnosed in ten girls who were classified into four groups based on the length of normal colon proximal to the colonic pouch. Of six girls with little or no normal colon, one had a cloacal anomaly while five had a colovesical or colovestibular fistula along with a completely bifid uterus and cervix and a septate vagina. Initial surgery consisted of ligation of the fistula and subtotal pouch excision with tubularization of the remaining colon in four girls, ileostomy after excision of a gangrenous pouch in one, and window colostomy in another. None of the patients had a sacral abnormality or associated major malformation. Definitive surgery using the posterior sagittal approach consisted of a pull-through of the tubularized colon in three girls (including one in whom one-stage cloacal reconstruction was performed), the ileum in one, and the proximal colon in another. The four girls with a longer length of normal colon had an associated vestibular fistula. In these, a colostomy was constructed just proximal to the pouch with definitive surgery in two patients consisting of excision of the pouch and pull-through of the proximal colon. Definitive surgery was well tolerated in all seven patients. The embryogenesis of this condition and the related genitourinary tract abnormalities are discussed.

Abnormalities, Multiple↗
PubMed1999

Covered exstrophy with incomplete duplication of the bladder.

A rare exstrophy variant in a 1(1/2)-year-old girl is reported. The child had a wide, scar-like lesion over the lower central abdomen with divarication of the recti and a spread symphysis pubis. The underlying bladder was divided into two unequal chambers by a complete sagittal septum with only the right chamber communicating with the single urethra and the left draining by a vesicocutaneous fistula. Both kidneys were normal. The clitoris was bifid and the anus anteriorly placed. Preliminary surgical management consisted of dissection of the bladder from its prevesical covering, excision of the sagittal septum, and cystocystostomy. Postoperatively, the child had normal urinary continence. The literature is reviewed with special reference to the various forms of duplicate exstrophy.

Abnormalities, Multiple↗
PubMed1999

Complete penoscrotal transposition and associated malformations.

Complete transposition of the penis and scrotum, or prepenile scrotum, is an uncommon congenital malformation. Concomitant genitourinary abnormalities, often life-threatening in nature, are frequently seen, and major malformations involving other organ systems may also be present. We report a newborn in whom complete penoscrotal transposition was accompanied by urethral atresia and radial dysgenesis.

Abnormalities, Multiple↗
PubMed1999

Inferior vesical fistula.

Exstrophy variants are uncommon developmental anomalies of the bladder; the variants involving only the bladder neck are extremely rare. There are only two case reports of inferior vesical fissure to date, and inferior vesical fistula (IVF) as an exstrophy variant has not been described previously. We report a case of IVF in a 20-month-old female. The urethra was normal in calibre and position and the bladder capacity was adequate. Simple closure of the fistula was followed by a normal micturition pattern.

Bladder Exstrophy↗
PubMed1998

An outbreak of post-surgical wound infections due to Mycobacterium abscessus.

An outbreak of post-operative wound infections due to Mycobacterium abscessus is described. During a 5-month period 45 post-surgical patients developed wound infection, manifested by wound breakdown, cellulitis, and discharge and progressing slowly to suppuration and sinus formation. The majority (43/45) had undergone out-patient operations, and 40 had had surgery in the inguinal region. The source of infection was identified as contaminated tap water. A study revealed serious deficiencies in the disinfection and sterilisation techniques employed in the operating theatre (OT), including major defects in the autoclaving machine. The outbreak was controlled after several specific measures were instituted. The patients responded well to treatment with conventional first-line anti-tuberculous drugs administered for 3-8 months. The report highlights the necessity of strict monitoring of disinfection and sterilisation techniques in surgical units and OTs.

Antitubercular Agents↗
PubMed1998

Pseudoexstrophy associated with congenital pouch colon.

Pseudoexstrophy or covered exstrophy is a rare exstrophy variant. The authors report a case of covered exstrophy that presented as a newborn with widely separated pubic bones and rectus muscles, a low-set umbilicus, and a subcutaneous bladder. The anal opening was absent, and there was a complex malformation of the external genitalia consisting of a small, laterally displaced penis and a right-sided ectopic hemiscrotum. Micturition and urinary continence were normal. The child also had a high anorectal malformation with a coexistent type IV congenital pouch colon (CPC) malformation. Both kidneys were normal. Preliminary surgery consisted of a divided sigmoid colostomy proximal to the colonic pouch. The literature is reviewed and the embryogenesis of pseudoexstrophy and its associated malformations are discussed.

Abnormalities, Multiple↗