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Biomedical subjects

K K Sharma

Publications and source records attributed to K K Sharma.

At least 55 records · Page 3Linked to original sources
PubMed2000

Chaperone-like activity of a synthetic peptide toward oxidized gamma-crystallin.

alphaA-Crystallin can function like a molecular chaperone. We recently reported that the alphaA-crystallin sequence, KFVIFLDVKHFSPEDLTVK (peptide-1, residues 70-88) by itself possesses chaperone-like (anti-aggregating) activity during a thermal denaturation assay. Based on the above data we proposed that the peptide-1 sequence was the functional site in alphaA-crystallin. In this study we investigated the specificity of peptide-1 against gamma-crystallin aggregation in the presence of H2O2 and CuSO4. Peptide-1 was able to completely protect against the oxidation-induced aggregation of gamma-crystallin. Removal of N-terminal Lys or the replacement of Lys with Asp (DFVIFLDVKHFSPEDLTVK, peptide-2) did not alter the anti-aggregation property of peptide-1. However, deletion of KF residues from the N-terminus of peptide-1 resulted in a significant loss of its anti-aggregation property. Bio-gel P-30 size-exclusion chromatography of gamma-crystallin incubated with peptide-2 under oxidative conditions revealed that a major portion of the peptide elutes in the void volume region along with gamma-crystallin, suggesting the binding of the peptide to the protein. Peptide-1 and -2 were also able to prevent the UV-induced aggregation of gamma-crystallin. These data indicate that the same amino acid sequence in alphaA-crystallin is likely to be responsible for suppressing the heat-denatured, oxidatively modified and UV-induced aggregation of proteins.

Amino Acid Sequence↗
PubMed2000

Possible role of histamine receptors in the central regulation of immune responses.

The present study was designed to delineate the role of H1- and H2-histamine receptors in the neuro-immune regulation in rats. The effects of H1- and H2-receptor antagonists on humoral and cell-mediated immune (HI and CMI) responses were investigated after intraperitoneal (i.p.) and intra-cerebroventricular (i.c.v.) administration. HI response was assayed by anti-sheep red blood cell (SRBC) antibody titre in presence and absence of 2-mercaptoethanol (2-ME). The CMI responses were evaluated by delayed type hypersensitivity (DTH) reaction (in vivo), i.e., measurement of footpad thickness, and lymphokine activity such as leucocyte migration inhibition (LMI) test (in vitro). On i.p. administration, both H1- (pheniramine and astemizole) and H2-receptor antagonists (ranitidine and cimetidine) were observed to produce significant enhancement of anti-SRBC antibody response. However, only H2- and not H1-receptor blockers were observed to stimulate CMI response significantly. When administered by icv route, only H2-receptor antagonists caused a statistically significant increase in both HI and CMI responses, while the H1-receptor blockers failed to modify the same. Thus, H2-receptors appear to play a major role in the histaminergic mechanisms involved in immunomodulation both at the level of immunocompetent cells active in the peripheral tissues as well as through the central nervous system structures involved in the central regulation of neuro-immune interaction.

Animals↗
PubMed2000

Interaction of pentazocine with calcium channel blocking drugs during chemical and thermal pain in mice.

The present study was designed to investigate the antinociceptive interaction of a clinically used opioid, pentazocine which produces its analgesic effect mainly through kappa receptors, with some calcium channel blockers (CCBs, viz. Diltiazem, flunarizine, nimodipine and verapamil--each representing one chemical class) in formalin and tail flick tests in mice. All the CCBs, except verapamil, significantly inhibited the formalin-induced pain response in a dose-dependent manner. However, none of these drugs affected tail flick latency at any of the studied doses. Pentazocine showed a significant antinociceptive response in both pain models, although a high dose was required to increase the tail flick latency. Pretreatment with all CCBs, individually enhanced the analgesic effect of pentazocine in both formalin and tail flick tests. In the latter test of nociception, a per se ineffective dose of pentazocine, showed a significant analgesic response in presence of CCB dose which itself was not effective in the test. Chronic concomitant administration of diltiazem with pentazocine did not prevent the development of tolerance to the opioid compound. However, diltiazem when given in combination with pentazocine to pentazocine-tolerant animals, it effectively reversed the tolerance. Results of the study thus suggest that concomitant treatment with CCBs, irrespective of their chemical nature, not only potentiate the antinociceptive effect of pentazocine in opioid naive animals in both tonic and acute nociceptive tests but also reverse the pentazocine tolerance.

Analgesics, Opioid↗
PubMed2000

A review on recent development of common cold therapeutic agents.

(1) The common cold is a frequently occurring illness caused by rhinoviruses. Inspite of its ubiquitous occurrence the disease has defied all efforts of finding a cure. The current approaches to the treatment of common cold can be divided into two important categories: the antiviral and antiinflammatory; both of these leave a lot to be desired. Most of the rhinovirus serotypes use a single cellular receptor, i.e. the intercellular Adhesion Molecule-1 (ICAM-1) for attachment to the cells. This has lead to the development of blockers of this receptor in an effort to find a cure for the common cold. (2) Recently tremacarmra, a synthetic ICAM-1 glycoprotein has been investigated in human volunteers as an antiadhesion molecule towards an approach to common cold therapy. Two dosage forms of the compound-phosphate buffered saline spray and carboxymethyl cellulose-mannitol powder spray were administered intra-nasally in two modes--pre-inoculation (7 h prior) and post-inoculation (24 h after) time periods of rhinovirus type 39 challenge to different groups of human volunteers. Both the treatment modes produced a significant decrease in the symptoms score of clinical illness and concentration of interleukin-8 in the nasal lavage. Saline spray was found to be devoid of any side effects, whereas powder spray produced some nasal irritation initially. The encouraging results of clinical trial with tremacamra show that a cure for common cold is not far off. However, it remains to be seen what would be the impact of such synthetic protein administration on the immune response of the body, should such compounds be used repeatedly. Further, since all colds are not due to rhinovirus it would be wise to restrict the use of tremacamra during autumn and spring when rhinoviruses are known to be the causative organisms of common cold.

Antiviral Agents↗
PubMed1999

Microglial activation by the small heat shock protein, alpha-crystallin.

Activated microglia regulate immune and inflammatory responses in the CNS under a variety of stresses due to infection, injury and disease. In this study, we show that a stress-inducible small heat shock protein, alpha-crystallin, induces in vitro activation of microglia cultured from newborn rat brain. Exposure of microglia to alpha-crystallin resulted in an increased production of nitric oxide (NO) and the expression of the inducible NO synthase (iNOS) as determined by Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses. Alpha-crystallin also stimulated the synthesis of the pro-inflammatory cytokine, TNF alpha. The results presented showing microglial induction of the two key immune regulatory and inflammatory molecules, i.e., NO and TNF alpha, in response to a stress-inducible protein, suggest a link between environmental stress and the CNS immune response.

Animals↗
PubMed1999

Minimally invasive mitral valve surgery through right anterolateral minithoracotomy.

BACKGROUND: This study evaluates the feasibility of minimally invasive mitral valve surgery. The aim of the study was to minimize surgical access to achieve better cosmetic results, less postoperative discomfort, and faster recovery. METHODS: From September 1997 to October 1998, 76 patients underwent mitral valve surgery through a right anterolateral minithoracotomy at the fourth intercostal space. The mitral valve was either repaired (n = 21) or replaced (n = 55). In all cases, open femoral artery-femoral vein cannulation was used for cardiopulmonary bypass. In 27 cases, an endoluminal aortic clamp was used, but in 49 cases, the aorta was cross-clamped with a transthoracic, sliding-rod-design clamp. RESULTS: There were no approach-related limitations to surgical intervention. Intraoperative transesophageal echocardiography revealed excellent results after valve repair and no paravalvular leak in any patient after mitral valve replacement. Mean duration of intensive care and postoperative hospital stay was 32+/-5.2 hours and 7+/-1.1 days, respectively. There were no major complications related to femoral vessel cannulation. In 1 patient, transient neurological problems developed, with subsequent complete recovery. There was one hospital mortality (85-year-old male patient died of upper GI bleeding). CONCLUSIONS: Minimally invasive port access mitral valve surgery can accelerate recovery and decrease pain, while maintaining overall surgical efficacy. It also provides better cosmetic results to our patients, and now it has become our standard approach for isolated mitral valve surgery.

Adult↗
PubMed1998

Identification of 1,1'-bi(4-anilino)naphthalene-5,5'-disulfonic acid binding sequences in alpha-crystallin.

The hydrophobic binding sites in alpha-crystallin were evaluated using fluorescent probes 1,1'-bi(4-anilino)naphthalenesulfonic acid (bis-ANS), 8-anilino-1-naphthalene sulfonate (ANS), and 1-azidonaphthalene 5-sulfonate (1,5-AZNS). The photolysis of bis-ANS-alpha-crystallin complex resulted in incorporation of the probe to both alphaA- and alphaB-subunits. Prior binding of denatured alcohol dehydrogenase to alpha-crystallin significantly decreased the photoincorporation of bis-ANS to alpha-crystallin. Localization of bis-ANS incorporated into alphaA-crystallin resulted in the identification of residues QSLFR and HFSPEDLTVK as the fluorophore binding regions. In alphaB-crystallin, sequences DRFSVNLNVK and VLGDVIEVHGK were found to be the bis-ANS binding regions. Of the bis-ANS binding sequences, HFSPEDLTVK of alphaA-crystallin and DRFSVNLNVK and VLGDVIEVHGK of alphaB-crystallin were earlier identified as part of the sequences involved in their interaction with target proteins during the molecular chaperone-like action. The hydrophobic probe, 1,5-AZNS, also interacted with both subunits of alpha-crystallin. Localization of 1,5-AZNS binding site in alphaB-crystallin lead to the identification of HFSPEEK sequence as the interacting site in this subunit of alpha-crystallin. Glycated alpha-crystallin displayed decreased ANS fluorescence and loss of chaperone-like function, suggesting the involvement of glycation site as well as ANS binding site in chaperone-like activity display.

Amino Acid Sequence↗
PubMed1998

Characterization of trypsin-modified bovine lens acylpeptide hydrolase.

Acylpeptide hydrolase, which removes the N-acetylated amino acids from peptide substrates was purified from bovine lens, truncated in vitro to a 55 kDa enzyme by trypsin digestion and characterized. The activity of the trypsin-modified enzyme was investigated using alpha A-crystallin and oxidized insulin A chain. The trypsin-modified enzyme was able to unblock alpha A-crystallin and displayed endoprotease activity unlike the native enzyme. SDS-PAGE analysis and amino acid sequencing of (3H)iPr2P-F labeled bovine lens acylpeptide hydrolase showed that the lens has a 55 kDa truncated form of the enzyme. The in vivo truncated form of the enzyme was generated by the cleavage of the Gly203-Asp204 peptide bond in the native enzyme.

Amino Acid Sequence↗
PubMed1998

Interaction of 1,1'-bi(4-anilino)naphthalene-5,5'-disulfonic acid with alpha-crystallin.

The hydrophobic sites in alpha-crystallin were evaluated using a fluorescent probe 1,1'-bi(4-anilino)naphthalenesulfonic acid (bis-ANS). Approximately one binding site/subunit of alpha-crystallin at 25 degrees C was estimated by equilibrium binding and Scatchard analysis (Kd = 1.1 microM). Based on fluorescence titration, the dissociation constant was 0.95 microM. The number of bis-ANS binding sites nearly doubled upon heat treatment of the protein at 60 degrees C. Likewise, the exposure of alpha-crystallin to 2-3 M urea resulted in increased binding of bis-ANS. Above 3 M urea there was a rapid loss in the fluorescence indicating the loss of interaction between bis-ANS and protein. The alpha-crystallin refolded from 6 M urea showed tryptophan fluorescence emission similar to the native alpha-crystallin. However, the refolded alpha-crystallin showed a 60% increase in bis-ANS binding, suggesting distinct changes on the protein surface resulting from exposure to urea similar to the changes occurring due to heat treatment. The fluorescence of tryptophan in native alpha-crystallin was quenched by the addition of bis-ANS. The quenching was inversely related to the amount of bis-ANS bound to alpha-crystallin. Additionally, the binding of bis-ANS reduced the chaperone-like activity of the protein. Photolysis of bis-ANS-alpha-crystallin complex resulted in incorporation of the probe to both A- and B-subunits, indicating that both subunits in native alpha-crystallin contribute to the surface hydrophobicity of the protein.

Anilino Naphthalenesulfonates↗
PubMed1998

Real-time intraoperative transesophageal echocardiography--how useful? Experience of 5,016 cases.

OBJECTIVE: To evaluate transesophageal echocardiography (TEE) as an intraoperative monitoring modality and to assess its safety, reliability, and overall utility in real-time use during cardiac surgery. DESIGN: Prospective, observational cohort study performed from January 1993 to June 1997. SETTING: Operating room of a tertiary care hospital for cardiology and cardiovascular surgery. PARTICIPANTS: Five thousand and sixteen adult patients with acquired heart disease, who underwent 1,356 valve procedures and 3,660 coronary artery bypass graftings (CABGs). INTERVENTIONS: All patients were monitored with radial artery and pulmonary artery catheters, along with continuous TEE monitoring with a multiplane transducer. MEASUREMENTS AND MAIN RESULTS: Prebypass imaging yielded unsuspected findings that either helped or modified the surgical plan in 158 of 1,356 valve procedures (11.65%) and in 993 of 3,660 CABGs (27.13%). There were 3,217 TEE-guided hemodynamic interventions in 944 patients (25.79%) in the CABG group and 629 in 142 patients (10.47%) in the valve group. TEE was the sole guiding factor in initiating therapy in 23.53% of events, whereas it was supportive to other monitoring modalities in 76.46% of events. Postbypass TEE identified the need for graft revision in 29 patients (0.8%), intra-aortic balloon pump (IABP) requirement in 29 patients (0.8%), and inadequate valve repair in 28 patients (2.08%). For the entire series, 38.78% of patients benefited from prebypass and 39.16% from postbypass use of TEE. There were no complications attributable to the use of TEE in the entire series. There was 87% concordance between online interpretation by a trained anesthesiologist and offline analysis by a cardiologist. CONCLUSION: Intraoperative TEE is useful in formulating the surgical plan, guiding various hemodynamic interventions, and assessing the immediate results of surgery. It is safe and the results are reliable in the hands of trained anesthesiologists.

Cardiac Surgical Procedures↗
PubMed1998

Malingering uncommon psychiatric symptoms among defendants charged under California's "three strikes and you're out" law.

This paper describes an epidemic of uncommon psychiatric symptoms among nine criminal defendants charged under California's new "Three Strikes and You're Out" law. The defendants were facing a minimum sentence of 25 years to life in prison. The defendants exhibited the following uncommon psychiatric symptoms: coprophagia (eating feces), eating cockroaches and many reported seeing little green men. The defendants, all of whom we believe were malingering, were evaluated by the authors for competency to stand trial. Thus far, eight of the nine defendants were found competent to stand trial; only one defendant was found incompetent to stand trial. The authors created a database which included information on the defendants from court documents and from our interview with the defendants. We summarized the data and outcomes of the case. Also included is a brief review of the "Three Strikes Law" and a paradigm for how we ruled out relevant psychiatric diagnoses before we arrived at our opinion of malingering.

Adult↗
PubMed1998

Forensic implications and medical-legal dilemmas of maternal versus fetal rights.

The purpose of this paper is to review the issue of fetal rights from primarily a legal perspective, with consideration of morals and professional ethics. The practice of medicine is fraught with numerous bioethical dilemmas. These dilemmas often leave the physician wondering if he has made the correct decision. A physician's morals and professional ethics may influence his or her decision in resolving bioethical dilemmas. The case example is a 34-year-old female with a 41-week intra-uterine pregnancy. The mother was refusing induction of labor. Without the labor induction, the fetus may die. Despite this risk, the mother desired to pursue a vaginal delivery. The AMA's ethics state that a competent, pregnant mother's wishes should prevail and the court should not be involved unless there are unusual circumstances. The mother in the case example was competent and informed consent was provided. Case law does not specifically address the dilemma of the case example. However, there is case law regarding court-ordered cesarean sections which reveals different opinions. The difference in court opinion encompasses the relative degree of weight given to the fetus's right to be born healthy and alive versus the mother's privacy rights. Some courts describe this "balancing test," whereas others state that the mother's privacy rights prevail unless there are exceptional circumstances, which will be extremely rare. The fetus has acquired rights in other areas of the law; for example, abolishment of the intra-family immunity doctrine and the definition of murder in most states. In considering the legal arena of fetal versus maternal rights, a decision tree is presented to assist physicians in assessing cases of a pregnant mother refusing medical treatment. There is no precise demarcation in assessing fetal and maternal rights. The greater the degree of fetal viability, the greater degree of fetal rights. Consideration must also be given to the relative degree of invasiveness to the mother for the proposed procedure; the more invasive, the greater degree of maternal rights. Each case must be evaluated on an individual basis and the decision tree can assist a clinician with this process.

Adult↗
PubMed1998

Tramadol, a centrally acting opioid: anticonvulsant effect against maximal electroshock seizure in mice.

The present study was designed to investigate the pro- or anticonvulsant effect of tramadol using maximal electroshock (MES) test. An attempt was also made to determine the possible opioid receptor mechanism involved. MES seizures were induced through transauricular electrodes (60 mA, 0.2s) and the seizure severity was assessed by the duration of tonic hindlimb extensor phase. Intraperitoneal (i.p.) administration of tramadol resulted in a dose-dependent anticonvulsant action; the ED50 for the effect was 33 mg/kg. The anti-MES effect of tramadol was antagonized by the low doses (0.05 and 0.1 mg/kg, s.c.) of MR 2266, a selective kappa receptor antagonist and also by the high doses (1.0 and 5.0 mg/kg, i.p.) but not the low doses (0.1 and 0.25 mg/kg) of naloxone. The results suggest that the anti-MES effect of tramadol is mediated by kappa receptors, since MR 2266 and naloxone (in high doses) are known to block these receptors.

Animals↗
PubMed1997

Functional elements in molecular chaperone alpha-crystallin: identification of binding sites in alpha B-crystallin.

alpha-Crystallin, the predominant eye lens protein with sequence homology to small heat shock proteins, acts like a molecular chaperone by suppressing the aggregation of damaged crystallins and proteins. To gain an insight into the amino acid sequences in alpha-crystallin involved in chaperone-like function, we used a cleavable, fluorescent, photoactive, crosslinking agent, sulfosuccinimidyl-2 (7-azido-4-methylcoumarin-3-acetamido)-ethyl-1,3' dithiopropionate (SAED), to derivatize yeast alcohol dehydrogenase (ADH) and allowed it to complex with bovine alpha-crystallin at 48 degrees C. The complex was photolyzed and reduced with DTT and the subunits of alpha-crystallin, alpha A- and alpha B-, were separated. Fluorescence analysis showed that both alpha A- and alpha B-crystallins interacted with ADH during chaperone-like function. Tryptic digestion, amino acid sequencing, and mass spectral analysis of alpha B-crystallin revealed that APSWIDTGLSEMR (57-69) and VLGDVIEVHGKHEER (93-107) sequences were involved in binding with ADH.

Amino Acid Sequence↗
PubMed1997

Acquired gastric outlet obstruction during infancy and childhood: a report of five unusual cases.

Infantile hypertrophic pyloric stenosis is a common, specific, and well-understood entity in the pediatric age group. Prepyloric webs and diaphragms are the other rare causes of gastric outlet obstruction followed by still rarer causes, eg, pyloric stenosis secondary to acid peptic disease. The present report describes a newer, nonspecific, clinical condition of pyloric obstruction in five patients of varying age who responded very well to Henieke-Mikulicz' pyloroplasty. The authors have suggested some modifications in the classification of gastric outlet obstruction in children to include these patients.

Child↗