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Biomedical subjects

D Chowdhury

Publications and source records attributed to D Chowdhury.

At least 19 recordsLinked to original sources
PubMed2006

Cytokine response in children undergoing surgery for congenital heart disease.

Pediatric cardiac surgery with cardiopulmonary bypass (CPB) induces a complex inflammatory response that may cause multiorgan dysfunction. The objective of this study was to measure postoperative cytokine production and correlate the magnitude of this response with intraoperative variables and postoperative outcomes. Serum samples from 20 children (median age, 15 months) undergoing cardiac surgery with CPB were obtained preoperatively and on postoperative days (POD) 1-3. Serum levels of interleukin (IL)-6, IL-8, and IL-10 increased significantly on POD 1 (p < 0.01) vs pre-op values to 271 +/- 68, 44 +/- 9, 7.5 +/- 0.8 pg/ml, respectively, whereas serum IL-1beta, IL-12, and tumor neurosis factor -alpha were not significantly changed. The serum IL-6 and IL-8 levels correlated positively (p < 0.01) with the degree of postoperative medical intervention as measured by the Therapeutic Interventional Scoring System and indicated a greater need for inotropic support (p = 0.057). A negative correlation (p < 0.01) between IL-6, IL-8, and mixed venous oxygen saturation suggested compromised cardiopulmonary function. Patients with single ventricle anatomy had the highest levels of IL-6 and IL-8 (629 +/- 131 and 70 +/- 17 pg/ml, respectively), with a mean CPB time of 106 +/- 23 minutes. Thus, the proinflammatory response after surgery with CPB was associated with postoperative morbidity with increased need for medical intervention.

Adolescent↗
PubMed2006

Approach to a case of autonomic peripheral neuropathy.

Autonomic neuropathy is the term used to describe autonomic disturbances resulting from diseases of the peripheral autonomic nervous system. This is a group of disorders in which the small, lightly myelinated and unmyelinated autonomic nerve fibers are selectively targeted. Most often, autonomic neuropathies occur in conjunction with a somatic neuropathy (i.e. with motor weakness and/or sensory loss), but they can occur in isolation. Causes of autonomic neuropathies are immune-mediated, paraneoplastic, infectious, toxic and drug-induced, hereditary, nutritional and idiopathic. Amongst all, diabetes mellitus is the most common cause. Autonomic features, which involve the cardiovascular, gastrointestinal, urogenital, sudomotor, and pupillomotor systems, occur in varying combination in these disorders. Orthostatic hypotension is often the first recognized and most disabling symptom. Noninvasive, well-validated clinical tests of autonomic functions along with a host of laboratory tests are of immense value to diagnose the presence and to demonstrate the distribution of autonomic failure. Treatment aims to treat specific cause of the autonomic neuropathy (if possible) and to control symptoms of autonomic dysfunction. Present review attempts to outline clinical approach to a case of autonomic peripheral neuropathy.

Arrhythmias, Cardiac↗
PubMed2005

Solid-state storage of Ag nanoparticles in anion exchange resin beads and their recovery.

This paper reports the idea and describes a method of reversible storage and recovery of silver nanoparticles (NPs) in anion exchange resin beads based on the principle of ion exchange. We also report that similar exchange of NPs was not possible with cation exchange resins. The Ag NPs were stored by simple exchange of anions of the resins, which were activated with OH- and NO3- ions. FTIR spectroscopic measurements support that the Ag NPs were exchanged with NO3- ions in the resins. The so-stored NPs could be regenerated by addition of NaBH4 solution to the resins. These NPs were recovered and subsequently utilized for catalytic reduction of an organic dye (eosin). Powder X-ray diffraction (XRD) pattern indicated storage of the NPs in the form of various oxides of silver in the resin, with the peak value of intensity corresponding to XRD of the NPs not changing with time. Scanning electron microscopic measurements show that the NPs in the beads were stable for over a month without the formation of any apparent agglomeration.

Journal Article↗
PubMed2004

Are multiple acute small subcortical infarctions caused by embolic mechanisms?

OBJECTIVE: To seek evidence of potential embolic sources or other stroke mechanisms in patients who, on chance observation, had several apparently recent small subcortical infarcts on diffusion weighted magnetic resonance imaging (DWI). METHODS: Patients presenting with stroke and multiple hyperintense subcortical infarcts visible on DWI were identified prospectively. Detailed clinical and radiological assessments were done independently and blinded to each other. RESULTS: Of 10 patients with multiple hyperintense subcortical infarcts on DWI, a definite embolic source was identified in only one. Most patients were hypertensive and smoked. The DWI appearance suggested that the subcortical lesions had occurred within several weeks rather than at exactly the same time. Most patients also had significant white matter hyperintensities and four had microhaemorrhages. CONCLUSIONS: Embolic sources were not identified in most patients but they did have systemic vascular risk factors and brain imaging features of "small vessel disease." A more generalised intrinsic process affecting many small cerebral vessels contemporaneously could explain multiple acute small subcortical infarcts. White matter hyperintensities, microhaemorrhages, and multiple small subcortical infarcts may share a common pathophysiological mechanism such as a diffuse cerebral microvascular abnormality which requires further exploration.

Acute Disease↗
PubMed2004

Brachial plexopathy: a clinical and electrophysiological study.

BACKGROUND: A retrospective study to evaluate the clinical and electrophysiological profile of brachial plexus lesions in a tertiary care center of India. METHODS: Thirty eight patients with brachial plexopathy (idiopathic or traumatic) with detailed electrophysiological studies were sampled. This included detailed motor and sensory nerve conduction studies of the conventional median, ulnar and radial nerves of the upper limbs, CMAP from deltoid, biceps and triceps on stimulating the ERB's point, needle EMG in the appropriate muscles and paraspinal muscles. The electrophysiological studies were performed on both sides irrespective of the clinical involvement and were recorded within 1.61 +/- 2.89 months in idiopathic group and 2.11 +/- 2.65 months in traumatic plexopathy group. The severity of involvement was assessed on MRC scale. ADL scale was used to assess the disability at presentation and subsequent follow up. RESULTS: 12 patients (11 male and 01 female) had idiopathic brachial plexopathy and 26 patients (all male) had traumatic brachial plexopathy. In the idiopathic group the lesion was localized to upper trunk in 58.3% of patients and middle trunk (posterior cord) in 41.66% and none had lower trunk or diffuse involvement. 25% had bilateral involvement. Two patients (16.6%) with idiopathic plexitis had recurrence involving the opposite side during the follow up. In the traumatic group the lesion was localized to the upper trunk in 11.53%, middle trunk (posterior cord) in 57.69% and 30.76% of patients had diffuse involvement. All the patients in traumatic plexopathy group had severe disability while in idiopathic group 91.66% had severe disability and 8.33% had moderate disability. Low amplitude CMAP and F wave abnormality were seen in 16.6% of patients in idiopathic group. On needle EMG 83.3% had fasciculation or fibrillations while none had paraspinal EMG abnormality. In traumatic group low to absent CMAP was seen in 69.2% and 76.92% had F wave abnormality. SNAPs were not recordable in 53.8%. On Needle EMG all the patients showed fasciculation or fibrillations and only 6 (23.0%) had paraspinal muscle fibrillations. Root avulsion could be documented in only four of these cases on MR imaging. CONCLUSIONS: Recovery in the traumatic group correlated well with the electrophysiological abnormalities while no such correlation was evident in the idiopathic group.

Adolescent↗
PubMed2002

Solid phase microextraction: measurement of volatile organic compounds (VOCs) in Dhaka City air pollution.

A solid phase microextraction (SPME) technique was applied for the sampling of volatile organic compounds (VOCs) in ambient air polluted by two stroke autorickshaw engines and automobile exhausts in Dhaka city, Bangladesh. Analysis was carried out by capillary gas chromatography (GC) and GC-mass spectrometry (MS). The methodology was tested by insitu sampling of an aromatic hydrocarbon mixture gas standard with a precision of +/-5% and an average accuracy of 1-20%. The accuracy for total VOCs concentration measurement was about 7%. VOC's in ambient air were collected by exposing the SPME fiber at four locations in Dhaka city. The chromatograms showed signature similar to that of unburned gasoline (petrol) and weathered diesel containing more than 200 organic compounds; some of these compounds were positively identified. These are normal hydrocarbons pentane (n-C5H2) through nonacosane (n-C29H60), aromatic hydrocarbons: benzene, toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, 1,3,5-trimethylbenzene, xylenes, and 1-isocyanato-3-methoxybenzene. Two samples collected near an autorickshaw station contained 783000 and 1479000 microg/m3 of VOCs. In particular, the concentration of toluene was 50-100 times higher than the threshold limiting value of 2000 microg/m3. Two other samples collected on street median showed 135000 microg/m3 and 180000 microg/m3 of total VOCs. The method detection limit of the technique for most semi-volatile organic compounds was 1 microg/m3.

Air Pollutants↗
PubMed2002

Randomized prospective study of outcome of short term antiepileptic treatment in small single enhancing CT lesion in brain.

The study was conducted in 81 patients of epilepsy with small single enhancing CT (SSECT) lesion in brain to determine the clinical profile and duration of antiepileptic drugs (AEDs) treatment. The patients were randomly divided into group A (41 cases) and group B (40 cases). Group A patients were treated for 6 months and group B for 1 year with AEDS without cysticidal drugs. The most common mode of presentation was simple partial motor seizures with secondary generalization in both the groups. Repeat imaging of brain (CT/MRI) at 6 months showed disappearance of lesion in 82.94% in group A and 87% in group B, while persistence of lesion was present only in 4.87% in group A and 5% in group B. 87.81% patients in group A and 87.17% in group B were seizure free. The recurrence of seizure occurred in 12.19% cases in group A, and 12.82% in group B. 80% of these patients had calcified lesion in both the groups. This study reveals that SSECT lesion with epilpesy is a benign self-limiting disease. It also reveals that 6 months AED treatment is as effective as one year treatment. Patients having calcified lesion or persistence of lesion might require long term AED treatment.

Adolescent↗
PubMed2001

Stepwise activation of the immunoglobulin mu heavy chain gene locus.

The immunoglobulin heavy chain (IgH) gene locus spans several megabases. We show that IgH activation during B-cell differentiation, as measured by histone acetylation, occurs in discrete, independently regulated domains. Initially, a 120 kb domain of germline DNA is hyperacetylated, that extends from D(FL16.1), the 5'-most D(H) gene segment, to the intergenic region between Cmu and Cdelta. Germline V(H) genes were not hyperacetylated at this stage, which accounts for D(H) to J(H) recombination occurring first during B-cell development. Subsequent activation of the V(H) locus happens in at least three differentially regulated domains: an interleukin-7-regulated domain consisting of the 5' J558 family, an intermediate domain and the 3' V(H) genes, which are hyperacetylated in response to DJ(H) recombination. These observations lead to mechanisms for two well-documented phenomena in B-cell ontogeny: the sequential rearrangement of D(H) followed by V(H) gene segments, and the preferential recombination of D(H)-proximal V(H) genes in pro-B cells. We suggest that stepwise activation may be a general mechanism by which large segments of the genome are prepared for expression.

Acetylation↗
PubMed2001

Axonal Guillain-Barré syndrome: a critical review.

Axonal Guillain-Barré Syndrome (GBS) was first described by Feasby et al. in 1986, challenging the existent notion of GBS being a primarily demyelinating disease. The severe course and slow recovery commonly seen in these patients was ascribed to axonal degeneration. Other authors challenged this claim on several grounds. Amidst these controversies, epidemics of a similar illness were reported from China, which were given the acronym AMAN, having exclusive motor involvement in contrast to the cases already described in which both motor and sensory involvement were present (AMSAN). Pathologically, Wallerian degeneration, minimal lymphocytic response, absent demyelination or inflammation and periaxonal macrophages are prominent features. Ultrastructural studies have revealed node of Ranvier to be the prime target of immune attack. A frequent occurrence of antecedent Campylobacter jejuni infection and a strong association between elevated titres of IgG GM1 and axonal GBS on a background of preceding C. jejunii infection has been observed and molecular mimicry between lipopolysaccharides of C. jejuni and neural epitopes has been proposed as a mechanism of injury. Clinically axonal variant is similar to AIDP, but a more severe course, with frequent respiratory involvement, ventilator dependence and significant residue may be seen. Diagnosis is essentially electrophysiological. Treatment is similar to AIDP, preferential benefit of either IVIG or plasmapheresis needs to be further evaluated. A critical review of existing literature in axonal GBS is presented.

Axons↗
PubMed2001

Estimation of mortality and morbidity due to strokes in India.

In order to control the stroke problem, its magnitude should be assessed. India is ranked among the countries where the information on stroke is minimal. We decided to review the information available in order to estimate the mortality and morbidity due to stroke in India. Information was collected through electronic search, hand search and contact with experts. Each article was reviewed for relevance and epidemiological rigor. The demographic data were as derived from published government figures. The prevalence from individual studies was pooled and weighted based on sample size. Analysis was done separately for males and females at 10-year intervals (20 years onwards). A total of 7 studies was located, but 2 were discarded. All were done in rural areas except 2 which also included urban areas. The prevalence was estimated as 203 per 100,000 population above 20 years amounting to a total of about 1 million cases. The male to female ratio was 1.7. Around 12% of all strokes occurred in population below 40 years. The estimation of stroke mortality was seriously limited by the method of classification of cause of death in the country. The best estimate derived was 102,000 deaths; which represented 1.2% of total deaths in the country. There is need to initiate steps to collect data on morbidity and mortality due to stroke in the country as a first step towards control measures.

Adolescent↗
PubMed2001

Reversible posterior leukoencephalopathy syndrome: a report of 2 cases.

Reversible posterior leukoencephalopathy syndrome (RPLE) is an increasingly recognised disorder, most commonly associated with malignant hypertension, toxaemia of pregnancy or the use of immunosuppressive agents. Two cases of RPLE syndrome occurring in the setting of accelerated hypertension and eclampsia are described. Both patients had seizures, altered sensorium and typical findings on neuroimaging. They had complete clinical and radiological recovery. The clinical course, pathophysiology and neuroimaging features of RPLE syndrome are discussed.

Adolescent↗
PubMed2000

Congenital myasthenic syndrome: report of four cases and brief review of literature.

The term 'congenital myasthenic syndrome' (CMS) encompasses a number of heterogeneous disorders characterised by myasthenic symptoms since birth, usually with positive family history and absence of acetyl choline receptor antibodies. Recent advances in electrophysiology and ultrastructural analysis of neuromuscular junction have made it possible to identify the various defects underlying these disorders. We report four cases of CMS, with a review of literature.

Adult↗
PubMed1999

Usefulness of triiodothyronine (T3) treatment after surgery for complex congenital heart disease in infants and children.

This is a study of the use of T3 infusion in the postoperative period in 6 pediatric patients who underwent complex cardiac surgical procedures under cardiopulmonary bypass. Normalization of serum T3 levels was reflected in a marked decrease in requirement of inotropic support, conversion to normal sinus rhythm, and progressively improving clinical course.

Child, Preschool↗
PubMed1999

Distinct functions of eukaryotic translation initiation factors eIF1A and eIF3 in the formation of the 40 S ribosomal preinitiation complex.

We have used an in vitro translation initiation assay to investigate the requirements for the efficient transfer of Met-tRNAf (as Met-tRNAf.eIF2.GTP ternary complex) to 40 S ribosomal subunits in the absence of mRNA (or an AUG codon) to form the 40 S preinitiation complex. We observed that the 17-kDa initiation factor eIF1A is necessary and sufficient to mediate nearly quantitative transfer of Met-tRNAf to isolated 40 S ribosomal subunits. However, the addition of 60 S ribosomal subunits to the 40 S preinitiation complex formed under these conditions disrupted the 40 S complex resulting in dissociation of Met-tRNAf from the 40 S subunit. When the eIF1A-dependent preinitiation reaction was carried out with 40 S ribosomal subunits that had been preincubated with eIF3, the 40 S preinitiation complex formed included bound eIF3 (40 S.eIF3. Met-tRNAf.eIF2.GTP). In contrast to the complex lacking eIF3, this complex was not disrupted by the addition of 60 S ribosomal subunits. These results suggest that in vivo, both eIF1A and eIF3 are required to form a stable 40 S preinitiation complex, eIF1A catalyzing the transfer of Met-tRNAf.eIF2.GTP to 40 S subunits, and eIF3 stabilizing the resulting complex and preventing its disruption by 60 S ribosomal subunits.

Animals↗
PubMed1999

Periodicity-dependent stiffness of periodic hydrophilic-hydrophobic heteropolymers.

From extensive Monte Carlo simulations of a Larson model of perfectly periodic heteropolymers (PHP) in water, a striking stiffening is observed as the period of the alternating hydrophobic and hydrophilic blocks is shortened. At short period and low temperature needlelike conformations are the stable conformations. As temperature is increased thermal fluctuations induce kinks and bends. At large periods compact oligomeric globules are observed. From the generalized Larson prescription, originally developed for modeling surfactant molecules in aqueous solutions, we find that the shorter the period is the more stretched the PHP is. This novel effect is expected to stimulate polymer synthesis and trigger research on the rheology of aqueous periodic heteropolymer solutions.

Journal Article↗