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Biomedical subjects

A Sharma

Publications and source records attributed to A Sharma.

At least 37 records · Page 2Linked to original sources
PubMed1995

Identification of linear antigenic sites on the Porphyromonas gingivalis 43-kDa fimbrillin subunit.

The fimbrillin of Porphyromonas gingivalis is thought to be an important virulence factor that mediates adherence to host surfaces. The linear immunogenic and antigenic structure of P. gingivalis fimbrillin was investigated with synthetic peptides corresponding to the amino acid sequence predicted from the cloned fimbrillin gene for P. gingivalis 2561. A series of continuous and overlapping peptides corresponding to the entire sequence of P. gingivalis fimbrillin was used to immunize Wistar rats. The resulting polyclonal antibodies were used to test the antigenicity of the 43-kDa fimbrillin protein by enzyme-linked immunosorbent assay and Western blot analysis. All the peptides elicited specific antibodies directed to the corresponding peptides but differed in their ability to elicit antisera that cross-reacted with either native or denatured fimbrillin. Antisera to various C-terminal one-third peptides were more reactive to the denatured monomeric form of fimbrillin by Western blot analysis. Antisera to peptide 99-110 was by far the most reactive against the native form of the oligomeric fimbrillin as well as the partially denatured oligomeric form of fimbrillin. The results indicate that amino acid residues 99-110 on the native fimbrillin protein are accessible to antibody binding and that the immunogen 99-110, when conjugated to thyroglobulin, is able to mimic an epitope on the 43-kDa fimbrillin.

Amino Acid Sequence↗
PubMed1995

Cutaneous metastases of lung cancer.

The reported incidence of skin metastases from lung cancer varies from 2.8-7.5%. In the present study 8.7% of patients had skin metastases, with head and neck being the most common sites, nodular lesions the most common, and adenocarcinoma the most frequent histology. Although most patients develop these lesions during the course of a known progressive disease, they may be the presenting manifestation of a primary tumour in the lung. The occurrence of skin lesions in lung cancer announces an ominous prognosis. The response to chemotherapy is poor, possibly due to poor blood supply to the skin; monitoring response to chemotherapy, however, is easier when such lesions are present.

Adenocarcinoma↗
PubMed1995

The reduction of insulin gene transcription in HIT-T15 beta cells chronically exposed to high glucose concentration is associated with the loss of RIPE3b1 and STF-1 transcription factor expression.

The most important regulator of insulin gene expression in pancreatic beta- cells is glucose, which affects gene transcription, mRNA translation, and secretion. Insulin gene transcription is both positively and negatively regulated by glucose. Recently, we have shown that the inhibition of insulin gene transcription caused by passaging HIT T-15 beta-cells, in the presence of high glucose, was due, in part, to reduced expression of a key regulator of insulin enhancer-mediated expression, somatostatin transcription factor-1 (STF-1). In this study, we have examined whether the activity of the other essential transcription regulators of insulin gene expression, the RIPE3b1 and insulin control element (ICE) activators, were also influenced in these HIT T-15 cells. The results show that the binding and trans-activation functions of the RIPE3b1 activator are reduced in parallel with the loss in STF-1 and insulin gene expression. In contrast, the regulatory properties of the ICE activator are unaffected. Our studies indicate that insulin gene transcription is inhibited by glucose through a mechanism involving reduced expression of both the RIPE3b1 and STF-1 activators in HIT T-15 cells but is independent of the ICE activator.

Animals↗
PubMed1995

Hypocholesterolemic activity of nut shell extract of Semecarpus anacardium (Bhilawa) in cholesterol fed rabbits.

Administration of S. anacardium nut shell extract to cholesterol fed rabbits resulted in a significant reduction in serum cholesterol (-73.3%) and serum LDL-Chol. (-80%). The extract feeding also prevented the accumulation of cholesterol/triglycerides in liver, heart muscle and aorta and caused a regression of plaques (75.3-83.5%). These results indicate that S. anacardium is hypocholesterolemic in action and prevents cholesterol induced atheroma. Possible mechanism of action is discussed.

Animals↗
PubMed1995

Synthesis of interleukin-1 beta in primary biliary cirrhosis: relationship to treatment with methotrexate or colchicine and disease progression.

Primary biliary cirrhosis (PBC) is a chronic, progressive, cholestatic liver disease. Interleukin-1 beta (IL-1 beta) may play a role in the pathogenesis of PBC by contributing to altered immune function and fibrosis. Colchicine or methotrexate has some beneficial effects in the treatment of PBC, and also affects interleukin-1 (IL-1). Therefore, we prospectively studied the synthesis of IL-1 beta by peripheral blood mononuclear cells (PBMC) from 42 patients with PBC entered into a randomized, double-blind, double-dummy controlled trial of colchicine and methotrexate. PBMC obtained at entry, 6, 12, 18, and 24 months were stimulated to produce IL-1 beta with phytohemagglutinin (PHA), lipopolysaccharide (LPS), Staphylococcus epidermidis, recombinant IL-2, or mitochondrial antigen. Patients in the two treatment groups did not differ at entry in biochemical measures or liver histological stage. Over 24 months in both groups, serum bilirubin and histologic stage remained stable and alkaline phosphatase decreased significantly. For all patients, synthesis of IL-1 beta increased constitutively and in response to immune-mediated stimulants (PHA, IL-2, and mitochondrial antigen) but not the bacterial stimulants LPS or S epidermidis. Compared with levels of IL-1 beta at entry, PHA induced increases for patients treated with methotrexate (12, 18, and 24 months) or colchicine (18 and 24 months). At 24 months, IL-2-induced IL-1 beta synthesis was increased in patients treated with methotrexate, whereas S epidermidis-induced IL-1 beta was enhanced in colchicine-treated patients. Before treatment, IL-1 beta production did not relate to severity of disease except in response to S epidermidis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Congenital cytomegalovirus infection in Shimla Hills, Himachal Pradesh, India.

We came across some cases clinically suggestive of intrauterine infection which were confirmed to be congenital cytomegalovirus infection. A clinical profile of these patients is presented. Intracranial calcification was not seen in any of these patients. Mental retardation was profound in all the patients and all had hepatomegaly. Uncommon findings encountered included hydrocephalus, patent ductus arteriosus and corneal opacities. Other clinical findings and investigation are also discussed.

Altitude↗
PubMed1995

Induction of acrosome reaction in fresh and frozen-thawed bovine spermatozoa by platelet activating factor.

In vitro capacitation has been induced in fresh and frozen spermatozoa of Karan Swiss (KS) and Karan Fries (KF) crossbred cattle by using a phospholipid-platelet activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine). The capacitation was monitored by examining acrosome reaction (AR) and motility at various levels of platelet activating factor (PAF) and at the end of each incubation time. On an average, with the increase in incubation time, there was a gradual decrease in motility and increase in acrosome reaction in both fresh as well as frozen spermatozoa. As PAF level increased, the motility of fresh sperms decreased and their acrosome reaction increased dramatically. However, in frozen-thawed semen, the motility remained almost the same and increase in AR of frozen spermatozoa was not pronounced. PAF level of about 100 microM was observed to be most optimum as at this level AR improved significantly without much loss of motility.

Acrosome↗
PubMed1995

Exacerbation of groin hernias after laparoscopy.

The incidence of pneumoperitoneum-related complications of laparoscopy is quite low. The more common complications are due to improper placement of the needle during insufflation and those related to the cardiorespiratory system. We describe two cases who underwent prolonged laparoscopic surgery and presented postoperatively with hernia.

Aged↗
PubMed1994

High-efficiency synthesis of human alpha-endorphin and magainin in the erythrocytes of transgenic mice: a production system for therapeutic peptides.

Chemical synthesis of peptides, though feasible, is hindered by considerations of cost, purity, and efficiency of synthesizing longer chains. Here we describe a transgenic system for producing peptides of therapeutic interest as fusion proteins at low cost and high purity. Transgenic hemoglobin expression technology using the locus control region was employed to produce fusion hemoglobins in the erythrocytes of mice. The fusion hemoglobin contains the desired peptides as an extension at the C end of human alpha-globin. A protein cleavage site is inserted between the C end of the alpha-globin chain and the N-terminal residue of the desired peptide. The peptide is recovered after cleavage of the fusion protein with enzymes that recognize this cleavage signal as their substrate. Due to the selective compartmentalization of hemoglobin in the erythrocytes, purification of the fusion hemoglobin is easy and efficient. Because of its compact and highly ordered structure, the internal sites of hemoglobin are resistant to protease digestion and the desired peptide is efficiently released and recovered. The applicability of this approach was established by producing a 16-mer alpha-endorphin peptide and a 26-mer magainin peptide in transgenic mice. Transgenic animals and their progeny expressing these fusion proteins remain health, even when the fusion protein is expressed at > 25% of the total hemoglobin in the erythrocytes. Additional applications and potential improvements of this methodology are discussed.

Amino Acid Sequence↗
PubMed1994

Crystal structure of the amino-terminal fragment of vaccinia virus DNA topoisomerase I at 1.6 A resolution.

BACKGROUND: Vaccinia virus, a cytoplasmically-replicating poxvirus, encodes a type I DNA topoisomerase that is biochemically similar to eukaryotic-like DNA topoisomerases I, and which has been widely studied as a model topoisomerase. It is the smallest topoisomerase known and is unusual in that it is resistant to the potent chemotherapeutic agent camptothecin. RESULTS: The crystal structure of a 9 kDa amino-terminal fragment of vaccinia virus DNA topoisomerase I has been determined at 1.6 A resolution. The fragment forms a five-stranded, antiparallel beta-sheet with two short alpha-helices and connecting loops. Residues that are conserved between all eukaryotic-like type I topoisomerases are not clustered in particular regions of the structure. CONCLUSIONS: This is the first atomic structure of any region of a eukaryotic-like DNA topoisomerase I. It has provided insights into the structural bases of the phenotypes of some single-site mutants of the intact topoisomerase. The structure has enabled us to study the interactions within a well-folded protein fragment and the camptothecin resistance of the viral topoisomerase.

Amino Acid Sequence↗
PubMed1994

Reversed-phase high-performance liquid chromatographic determination of taxol in mouse plasma.

A simple and selective high-performance liquid chromatographic technique was developed for the determination of taxol in mouse plasma. This technique employs a single extraction step followed by isocratic chromatography on a C18 analytical column and ultraviolet detection at 227 nm, and is suitable for the analysis of microsamples (50 microliters plasma). A series of aromatic and aliphatic benzamides were synthesized as internal standards; N-octylbenzamide was evaluated most extensively. The calibration curve is linear within the range 0.15-10 nmol/ml. The intra-day and inter-day coefficients of variation were below 7%. The specificity of the assay was confirmed by comparing the chromatographic properties of samples with authentic taxol, using a diode-array detector. The assay was used to conduct pharmacokinetic studies of taxol in mice after administration in different formulations.

Animals↗
PubMed1994

Characterization of pPT23B, the plasmid involved in syringolide production by Pseudomonas syringae pv. tomato PT23.

Avirulence gene D (avrD) in strain PT23 of Pseudomonas syringae pv. tomato (Pst) specifies the production of syringolides, which are elicitors of plant defense reactions. An 83-kb indigenous plasmid (pPT23B) that carries avrD has been mapped and characterized and a putative par region was identified. pPT23B contains a large amount of DNA that is repeated in other native plasmids in PT23. A putative mobile insertion element that occurs on plasmid pPT23A as well as on the chromosome was also identified in strain PT23. New broad-host-range expression vectors that functioned in Pst were constructed for overexpression of the cloned avrD gene and high-level production of the syringolides. Introduction of an avrD overexpression plasmid into PT23 or plasmid-cured strains led to identical syringolide peaks on HPLC with no new peaks observed. These results suggested that neither pPT23B nor other indigenous plasmids in Pst carry additional genes required for syringolide production or metabolism. Pst strains lacking pPT23B were not impaired in virulence on tomato plants.

Bacterial Toxins↗
PubMed1994

Encircling endocardial cryoablation for ventricular tachycardia after myocardial infarction: experience with 33 patients.

Encircling endocardial cryoablation, consisting of circumferential cryoablation of the infarct scar, can be curative in selected patients with ventricular tachycardia (VT). We describe our experience with and long-term outcome in 33 patients undergoing this procedure. The interval between myocardial infarction and the onset of tachycardia varied from 2 weeks to 22 years (mean 38 +/- 63 months and median 3 months). All patients had a left ventricular aneurysm (anterior in 20, posterior in 12, and lateral in 1) and significant coronary artery disease. Fourteen patients had clinical evidence of heart failure preoperatively. Twenty-eight patients had sustained monomorphic VT (incessant in 3); 3 had polymorphic or nonsustained tachycardia; 2 had primary ventricular fibrillation; and 1 had associated Wolff-Parkinson-White syndrome. Surgery was undertaken after failed drug therapy and consideration of left ventricular anatomy and function. At surgery, 32 patients had encircling endocardial cryoablation, and 1 patient had partial right ventricular free-wall disconnection (right ventricular infarct). Thirteen patients underwent concomitant coronary artery bypass grafting. An implantable cardioverter defibrillator (ICD) was implanted in 2 patients and prophylactic ICD patches in 1. One patient died postoperatively; 3 had recurrent VT perioperatively; 1 was treated with amiodarone; and 2 had ICD implantation. During long-term follow-up (mean 5 years), all patients who were free of tachycardia at discharge remained alive and free of arrhythmias or syncope. The patient receiving amiodarone sustained a cardiac arrest subsequently and received an ICD implant. One patient with an ICD continued to receive appropriate shocks frequently and died 2 years after surgery. Nine patients had congestive heart failure postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1994

Interstitial pneumonitis after low-dose methotrexate therapy in primary biliary cirrhosis.

Interstitial pneumonitis is an uncommon complication of low-dose methotrexate therapy in patients with psoriasis but occurs in 3%-5% of patients with rheumatoid arthritis. We found a higher incidence of interstitial pneumonitis in patients with primary biliary cirrhosis (14%) and describe its clinical manifestations, treatment, and possible etiology. Blood tests, arterial blood gas determinations, chest radiographs, bronchoscopy, tear production, autoantibody tests, and serum immunoglobulin levels were obtained in six women who developed interstitial pneumonitis while receiving methotrexate in a double-blind prospective trial of methotrexate vs. colchicine in 87 patients with primary biliary cirrhosis. Six of 43 patients (14%) who received methotrexate compared with no patients receiving colchicine developed interstitial pneumonitis 19-61 weeks after starting treatment. The pneumonitis was characterized by dyspnea, hypoxemia, and bilateral lung infiltrates, all of which responded within 24 hours to the administration of intravenous glucocorticoids. There was no correlation between the pneumonitis and pre-existing lung disease, the severity of the primary biliary cirrhosis, the titer of antimitochondrial antibody, or other diseases associated with primary biliary cirrhosis. Patients with primary biliary cirrhosis receiving low-dose methotrexate (15 mg/wk) are more susceptible to interstitial pneumonitis than patients with psoriasis or rheumatoid arthritis. The pneumonitis appears to be a hypersensitivity reaction and responds rapidly to intravenous glucocorticoid therapy.

Aged↗
PubMed1994

Chlorophyll and chlorophyllin as modifiers of genotoxic effects.

Reports on an inverse relationship between the consumption of fresh vegetables and human gastrointestinal cancer have been followed by screening for the protective activity of a large number of plant extracts, including leafy vegetables. Chlorophyll is ubiquitous in all green plant parts. Chlorophyllins are derivatives of chlorophyll in which the central magnesium atom is replaced by other metals, such as cobalt, copper or iron. An attempt has been made in this article to review the relative efficacy of chlorophyll and chlorophyllin in modifying the genotoxic effects of various known toxicants.

Animals↗