PubMed Health⌕ Search

Biomedical subjects

D Jain

Publications and source records attributed to D Jain.

At least 19 recordsLinked to original sources
PubMed2001

Use of paclitaxel in patients with pre-existing cardiomyopathy: a review of our experience.

Cardiac toxicity is frequently the indication for discontinuation of an anthracycline in patients with tumors which remain anthracycline-sensitive. During the 1990s, the most frequently used second-line agents at the Yale Cancer Center (YCC) were the taxanes. The goal of this retrospective analysis was to determine the effect of paclitaxel on cardiac function in patients with cardiomyopathy. YCC outpatient clinic pharmacy order forms were used to identify all patients who had received paclitaxel between December 1995 and November 1997. The clinic records of those patients with a left ventricular ejection fraction (LVEF) of < or = 50% were reviewed to determine the temporal relation between the decreased LVEF and paclitaxel therapy. In addition, clinic records were examined for evidence of prior doxorubicin therapy and history of prior cardiac disease. Between December 1995 and November 1997, 225 patients were treated with paclitaxel in the YCC outpatient clinic. Nine patients had LVEF < or = 50% (mean 37%) prior to initiation of paclitaxel therapy. Six of these patients had equilibrium radionuclide angiocardiographic (ERNA) scans following completion of paclitaxel. In these 6 patients, the mean change in LVEF was +6% (range -3% to +29%). Four patients had improved LVEF following paclitaxel (mean 11%, range 2% to 29%), while 2 patients experienced a decrease in LVEF following paclitaxel treatment (mean 2.5%). The 3 patients who did not have ERNA scans following paclitaxel therapy had no clinical evidence of congestive heart failure. Our experience confirms the results of prior studies that paclitaxel can be safely administered in patients with underlying cardiac dysfunction.

Aged↗
PubMed2001

Immunological implications of structural mimicry between a dodecapeptide and a carbohydrate moiety.

The immunogenicity and antibody cross-reactivity of two chemically different but structurally equivalent molecular mimics were analyzed by presenting them to the immune system in different modes. The observed differences in IgM and IgG responses in terms of cross-reactivity with the mimicking antigen could reflect the differential proliferative abilities of the corresponding B-cells. Modification of the T-cell help, either by using a promiscuous T-cell epitope or by prepriming, led to the shift in the antibody response towards the mimicking epitope. Also, the anti-sugar antibodies could be boosted using a carbohydrate mimicking peptide on cross-immunization. Thus, the carbohydrate-peptide mimicry appears to be a topological quasi-equivalence reflected differently in terms of antibody response during maturation.

Amino Acid Sequence↗
PubMed2001

A unique pitfall in percutaneous coronary angioplasty of in-stent restenosis: guidewire passage out of the stent.

Three cases of in-stent restenosis are narrated, wherein, during balloon angioplasty of the lesion, the guidewire inadvertently exited out of the stent. The forward balloon progress was halted in this region. In the first case, the situation could only be realized when dilatation of a forcefully pushed small balloon avulsed the well-embedded stent. The mishap was averted in the subsequent two cases by reintroduction of a new guidewire. Some suggestions to avoid this eventuality are offered. Though the cases pertain to in-stent restenosis, the observations may be applicable to the procedures in general that entail passage of a guidewire through a stented area.

Aged↗
PubMed2001

Plasticity in protein-peptide recognition: crystal structures of two different peptides bound to concanavalin A.

The structures of concanavalin A (ConA) in complex with two carbohydrate-mimicking peptides, 10-mer (MYWYPYASGS) and 15-mer (RVWYPYGSYLTASGS) have been determined at 2.75 A resolution. In both crystal structures four independent peptide molecules bind to each of the crystallographically independent subunits of ConA tetramer. The peptides exhibit small but significant variability in conformations and interactions while binding to ConA. The crystal structure of another similar peptide, 12-mer (DVFYPYPYASGS), in complex with ConA has been determined (Jain, D., K. J. Kaur, B. Sundaravadivel, and D. M. Salunke. 2000. Structural and functional consequences of peptide-carbohydrate mimicry. J. Biol. Chem. 275:16098-16102). Comparison of the three complexes shows that the peptides bind to ConA at a common binding site, using different contacting residues and interactions depending on their sequence and the local environment at the binding site. The binding is also optimized by corresponding plasticity of the peptide binding site on ConA. The diversity in conformation and interactions observed here are in agreement with the structural leeway concerning plasticity of specific molecular recognition in biological processes. The adaptability of peptide-ConA interactions may also be correlated with the carbohydrate-mimicking property of these peptides.

Concanavalin A↗
PubMed2001

Adenosine inhibits norepinephrine release in the postischemic rat heart: the mechanism of neuronal stunning.

OBJECTIVE: Numerous studies support the concept of impaired postischemic sympathetic neurotransmission in the heart. We hypothesized that postischemic neuronal dysfunction (neuronal stunning) is caused by a transient suppression of exocytotic norepinephrine (NE) release from sympathetic nerve terminals. Furthermore, we assessed the role of presynaptic adenosine-receptors and alpha2-adrenoceptors in neuronal stunning. METHODS AND RESULTS: Exocytotic NE release was induced by two electrical field stimulations (S(1) and S(2)) in isolated perfused rat hearts. S(1) was performed under baseline conditions and S(2) either during or following intervention. Results are expressed as mean S(2)/S(1) ratios+/-S.E.M. Stepwise increase of global ischemic periods (10, 20, and 30 min) induced a progressive suppression of NE release in the postischemic hearts, which was reversible during reperfusion. Both the degree and duration of NE suppression was dependent on the extent of the preceding ischemic period. Following 10-min ischemia complete recovery of NE release was achieved after 5-min reperfusion (1.07+/-0.12), whereas 5-min reperfusion did not restore NE release after 30 min (0.36+/-0.07) of ischemia. The adenosine-receptor antagonists 8-phenyltheophylline (8-PT; non-selective) and 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; adenosine A1-receptor subtype selective) significantly increased NE release after 30-min ischemia and 5-min reperfusion (0.78+/-0.06 and 0.64+/-0.07), while in the same experimental protocol blockade of alpha2-adrenoceptors by yohimbine failed to restore the postischemic release (0.24+/-0.06). In non-ischemic hearts the adenosine analogue R(-)N(6)-(2-phenylisopropyl)adenosine (R-PIA) resulted in a marked suppression of NE release (0.61+/-0.07). The inhibitory effect of R-PIA and 2-chloro-N(6)-cyclopentyladenosine (CCPA; adenosine A1-receptor subtype selective agonist) persisted 5 min after cessation of R-PIA (0.62+/-0.05) and CCPA (0.58+/-0.04). Activation of alpha2-adrenoceptors by 5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK 14,304) also caused a reduction of NE release (0.50+/-0.02), but the release increased to control levels 5 min after cessation of UK 14,304 (0.90+/-0.06). CONCLUSIONS: The results establish the phenomenon of neuronal stunning in terms of a postischemic suppression of exocytotic NE release and provide evidence that neuronal stunning is mediated by endogenous adenosine through activation of presynaptic adenosine A1-receptors.

Adenosine↗
PubMed2001

Morphology of isolated colonic crypts.

The traditional paradigm of colonic fluid and electrolyte transport includes a spatial separation of absorptive and secretory processes to surface and crypt cells, respectively. Recent studies of isolated microperfused colonic crypts revealed constitutive Na-dependent fluid absorption while secretion is regulated by one or more neurohumoral agonists. One obvious reason for the difference found in microdissected crypts is their separation from the lamina propria milieu. While it has been shown that isolated crypts are devoid of obvious lamina propria elements, including pericryptal fibroblasts, detailed morphologic information of the content of isolated crypts has been lacking. To characterize the morphology of the isolated crypt, we performed transmission electron microscopy (TEM) and immunofluorescence on microdissected and Ca2+ chelated crypts. Crypt cell type analysis was carried out separately on intact rat colon using light microscopy. TEM revealed a complete lack of either lamina propria cells or extracellular material in crypts isolated by either technique. TEM also revealed a subtle difference between the two isolation methods, with intact basal membranes in microdissected crypts but focal disruption of basal membranes in Ca2+- chelated crypts. Immunofluorescent stains for two basement membrane components (laminin and collagen type IV) revealed the presence of adherent basement membrane only on microdissected crypts; evidence that the plane of separation differs in these two preparations. Crypt cell type analysis on intact rat colon revealed an equal proportion of goblet cells in the right and left colon (approximately 50%) when measuring the middle 70% of the crypts - the area studied during crypt microperfusion. This morphologic analysis will increase our understanding of the observed physiology of isolated colonic crypts.

Animals↗
PubMed2001

An unusual complication of metallic balloon shaft fracture during coronary angioplasty.

We describe two cases of metallic balloon catheter shaft fracture, at a site just proximal to the hemostatic Y-adapter, while attempting to push the stent-balloon assembly through a tortuous left circumflex artery. In both instances, the stent carrying the balloon catheter had a stainless-steel hypotube constituting the proximal stiff portion of the shaft. While no inferences pertaining to this design can be made, our cases call for a closer observation. It would probably be prudent to change the catheter or the dilatation strategy once the shaft started buckling.

Angioplasty, Balloon, Coronary↗
PubMed2000

Liver disease in patients with hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia, or Rendu-Osler-Weber disease, is an autosomal dominant disorder characterized by angiodysplastic lesions (telangiectases and arteriovenous malformations) that affect many organs. Liver involvement in patients with this disease has not been fully characterized. METHODS: We studied the clinical findings and results of hemodynamic, angiographic, and imaging studies in 19 patients with hereditary hemorrhagic telangiectasia and symptomatic liver involvement. RESULTS: We evaluated 14 women and 5 men who ranged in age from 34 to 74 years. All but one of the patients had a hyperdynamic circulation (cardiac index, 4.2 to 7.3 liters per minute per square meter of body-surface area). In eight patients, the clinical findings were consistent with the presence of high-output heart failure. The cardiac index and pulmonary-capillary wedge pressure were elevated in the six patients in whom these measurements were performed. After a median period of 24 months, the condition of three of the eight patients had improved, four were in stable condition with medical therapy, and one had died. Six patients had manifestations of portal hypertension such as ascites or variceal bleeding. The hepatic sinusoidal pressure was elevated in the four patients in whom it was measured. After a median period of 19 months, the condition of two of the six patients had improved, and the other four had died. Five patients had manifestations of biliary disease, such as an elevated alkaline phosphatase level and abnormalities on bile duct imaging. After a median period of 30 months, the condition of two of the five had improved, the condition of one was unchanged, heart failure had developed in one, and one had died after an unsuccessful attempt at liver transplantation. CONCLUSIONS: In patients with hereditary hemorrhagic telangiectasia and symptomatic liver-involvement, the typical clinical presentations include high-output heart failure, portal hypertension, and biliary disease.

Adult↗
PubMed2000

Structural basis of functional mimicry between carbohydrate and peptide ligands of con A.

Crystallographic studies have shown independent binding sites for sugar and peptide ligands of concanavalin A, although they were considered functional mimics based on biochemical experiments. The topological correlation of 12-residue peptide with different carbohydrate ligands of concanavalin A showed similarity between trimannose and the YPY region of the peptide establishing structural mimicry. Molecular docking of trimannose and the YPY motif on the reciprocal binding sites revealed equivalent interactions and energetics implying that the peptide-binding sites may constitute additional sugar-binding subsites of concanavalin A. The binding of a mannose-rich neoglycoprotein with significantly higher affinity compared with that of the methyl alpha-d-mannopyranoside is consistent with this interpretation.

Amino Acid Motifs↗
PubMed2000

Structural and functional consequences of peptide-carbohydrate mimicry. Crystal structure of a carbohydrate-mimicking peptide bound to concanavalin A.

The functional consequences of peptide-carbohydrate mimicry were analyzed on the basis of the crystal structure of concanavalin A (ConA) in complex with a carbohydrate-mimicking peptide, DVFYPYPYASGS. The peptide binds to the non-crystallographically related monomers of two independent dimers of ConA in two different modes, in slightly different conformations, demonstrating structural adaptability in ConA-peptide recognition. In one mode, the peptide has maximum interactions with ConA, and in the other, it shows relatively fewer contacts within this site but significant contacts with the symmetry-related subunit. Neither of the peptide binding sites overlaps with the structurally characterized mannose and trimannose binding sites on ConA. Despite this, the functional mimicry between the peptide and carbohydrate ligands was evident. The peptide-inhibited ConA induced T cell proliferation in a dose-dependent manner. The effect of the designed analogs of the peptide on ConA-induced T cell proliferation and their recognition by the antibody response against alpha-d-mannopyranoside indicate a role for aromatic residues in functional mimicry. Although the functional mimicry was observed between the peptide and carbohydrate moieties, the crystal structure of the ConA-peptide complex revealed that the two peptide binding sites are independent of the methyl alpha-d-mannopyranoside binding site.

Binding Sites↗
PubMed2000

Destabilizing effects of mental stress on ventricular arrhythmias in patients with implantable cardioverter-defibrillators.

BACKGROUND: The incidence of sudden cardiac death increases in populations who experience disasters such as earthquakes. The physiological link between psychological stress and sudden death is unknown; one mechanism may be the direct effects of sympathetic arousal on arrhythmias. To determine whether mental stress alters the induction, rate, or termination of ventricular arrhythmias, we performed noninvasive programmed stimulation (NIPS) in patients with defibrillators and ventricular tachycardia (VT), which is known to be inducible and terminated by antitachycardia pacing, at rest and during varying states of mental arousal. METHODS AND RESULTS: Eighteen patients underwent NIPS in the resting-awake state (nonsedated). Ten underwent repeat testing during mental stress (mental arithmetic and anger recall). Induced VT was faster in 5 patients (P=0.03). VT became more difficult to terminate in 5 patients during mental stress; 4 required a shock (P=0.03). There was no change in ease of induction with mental stress. There was no evidence of ischemia on ECG or continuous ejection fraction monitoring. Eight patients received a shock in the resting-awake state and did not perform mental stress. Four underwent repeat NIPS after sedation; 3 then had induced VT terminated with antitachycardia pacing. All patients with an increase in norepinephrine of >50% had alterations in VT that required shock for termination (P<0.01). CONCLUSIONS: Mental stress alters VT cycle length and termination without evidence of ischemia. This suggests that mental stress may lead to sudden death through the facilitation of lethal ventricular arrhythmias.

Aged↗
PubMed2000

Nuclear cardiology in the evaluation of acute chest pain in the emergency department.

Only a minority of patients presenting to the emergency department (ED) with acute chest pain will eventually be diagnosed with an acute coronary syndrome. The majority will have an electrocardiogram that is normal or nondiagnostic for acute myocardial ischemia or infarction. Typically, these patients are admitted to exclude myocardial infarction despite a very low incidence of coronary artery disease. However, missed myocardial infarctions in patients who are inadvertently sent home from the ED have significant adverse outcomes and associated legal consequences. This leads to a liberal policy to admit patients with chest pain, presenting a substantial burden in terms of cost and resources. Many centers have developed chest pain centers, using a wide range of diagnostic modalities to deal with this dilemma. We discuss the methods currently available to exclude myocardial ischemia and infarction in the ED, focusing on the use of myocardial perfusion imaging as both an adjunct and an alternative to routine testing. We review the available literature centering on the ED evaluation of acute chest pain and then propose an algorithm for the practical use of nuclear cardiology in this setting.

Acute Disease↗
PubMed2000

Non-traumatic rhabdomyolysis with acute renal failure.

A clinical profile of non-traumatic rhabdomyolysis with acute renal failure is presented. Myoglobinuric renal failure is treatable and hence a high index of suspicion is warranted in the etiologies discussed.

Acute Kidney Injury↗
PubMed2000

Risk factors for severe child discipline practices in rural India.

OBJECTIVES: To determine the type and severity of discipline practices in rural India and to identify risk and protective factors related to these practices. METHODS: Five hundred mothers, ages 18-50, participated in face-to-face interviews as part of a cross-sectional, population-based survey. One of the mother's children was randomly selected as the referent child. The interview focused primarily on discipline practices and spousal violence. Sociodemographic characteristics, neighbor support, residential stability, and husband's drinking behavior were also assessed. RESULTS: Nearly half of the mothers reported using severe verbal discipline and 42% reported using severe physical discipline. While common, severe discipline practices occurred less frequently than moderate practices and had different risk factors, notably low maternal education and spousal violence. CONCLUSIONS: Results suggest that increased formal education for rural women in India may have the added benefit of reducing family violence, including spouse and child abuse.

Adolescent↗
PubMed2000

Evidence for the neoplastic transformation of Von-Meyenburg complexes.

Von-Meyenburg complexes (VMC) are seen frequently in the liver and are largely considered to be innocuous, with only 11 cases reported in the literature of neoplastic transformation of VMCs. The authors report three cases of cholangiocarcinoma, each occurring in a background of fibrosis and nodularity that was reported initially as micronodular cirrhosis. Although the livers showed cirrhosis, the central veins were often preserved, and regenerative activity was patchy and focal. Histologic examination revealed many VMCs, and a gradual transition from VMCs to hyperplastic or adenomatous lesions and cholangiocarcinoma. The adenomatous lesions consisted of extensive replacement of the parenchyma by tumor-like nodules of ductular proliferations without obvious features of malignancy. All three patients were older than 60 years of age and had portal hypertension. Computed tomographic scans showed multiple, small renal cysts in one patient. Immunohistochemical staining showed positivity for epithelial membrane antigen, carcinoembryonic antigen, and keratins (AE1/AE3 and CAM5.2) in tumor cells, consistent with cholangiocarcinoma. The pattern of fibrosis and nodularity in these cases is not typical of either congenital hepatic fibrosis or usual cirrhosis. The authors propose that these patients represent another aspect in the spectrum of ductal plate malformations that may be modified by other factors such as alcohol, drugs, or infection. To their knowledge, neoplastic transformation of VMCs in the background of such changes has never been reported before.

Aged↗
PubMed2000

Granular cells as a marker of early amiodarone hepatotoxicity.

Hepatotoxicity due to chronic amiodarone (AD) use is well described. However, hepatitis occurring after acute administration of AD has only occasionally been reported and the pathologic findings in the liver in this condition have not been well characterized. We describe an idiosyncratic reaction, in a 40-year-old man after 6 weeks of oral AD therapy, consisting of acute hepatitis, which resolved after withdrawal of the drug. The liver biopsy showed clusters of cells with granular cytoplasm. These cells were characterized as macrophages, and phospholipid membranous inclusions were demonstrated ultrastructurally in the granular cells and in the hepatocytes. Pathologists and clinicians should be aware of this subtle histologic finding when looking for evidence to support AD hepatotoxicity.

Adult↗
PubMed2000

Epstein-Barr virus RNA detection and glandular differentiation in nasopharyngeal carcinoma: report of 2 cases.

Most tumors arising in the nasopharynx are either squamous cell carcinoma or so-called undifferentiated carcinoma of the nasopharyngeal type. Primary adenocarcinomas of the nasopharynx are rare, and glandular differentiation in undifferentiated carcinoma of the nasopharyngeal type has not been reported to date. We report 2 cases of undifferentiated carcinoma of the nasopharyngeal type that show distinct glandular differentiation by light microscopy, histochemistry, immunohistochemistry, and ultrastructure. Both tumors showed equal positivity for Epstein-Barr virus latent membrane protein and in situ hybridization for Epstein-Barr virus genome in the undifferentiated areas of the tumor and those featuring glandular differentiation.

Adenocarcinoma↗