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M Singh

Publications and source records attributed to M Singh.

At least 235 records · Page 13Linked to original sources
PubMed2000

Role of nitric oxide in diabetes-induced attenuation of antinociceptive effect of morphine in mice.

The study was designed to investigate the role of nitric oxide (NO) in the diabetes-induced decrease of the antinociceptive effect of morphine. The nociceptive threshold in diabetic and non-diabetic mice was measured in the tail-flick test. Streptozotocin (200 mg/kg i.p.) was administered to induce experimental diabetes in the mice. Four weeks after the administration of streptozotocin, the tail-flick test was performed and urinary nitrite concentration was estimated using Greiss reagent. Experimental diabetes markedly decreased the antinociceptive effect of morphine (10 microg in 5 microl/mice i.c.v.) and significantly increased the urinary nitrite concentration. Administration of aminoguanidine (12 mg/mice) markedly improved the antinociceptive effect of morphine and attenuated the increase in urinary nitrite concentration in diabetic mice. It may be tentatively concluded that an increase in NO formation may be responsible for the observed decrease in antinociceptive effect of morphine in diabetic mice.

Analgesics, Opioid↗
PubMed2000

Novel anionic microparticles are a potent adjuvant for the induction of cytotoxic T lymphocytes against recombinant p55 gag from HIV-1.

Microparticles with entrapped antigens have recently been shown to possess significant potential as vaccine delivery systems and adjuvants. However, the potential of microparticles as adjuvants has been seriously limited by the common problem of degradation and denaturation of antigens following encapsulation and release. To overcome these problems, we have developed a novel way to use microparticles as adjuvants, by the adsorption of proteins onto their surface. Anionic microparticles were prepared through the inclusion of an anionic detergent, sodium dodecyl sulphate (SDS), in the microparticle preparation process. The anionic microparticles were capable of the efficient and reproducible adsorption of recombinant p55 gag protein from HIV-1. Microparticles with adsorbed p55 were capable of inducing potent cytotoxic T lymphocyte responses in mice following intramuscular immunization. In addition, the microparticles also exhibited a potent adjuvant effect for antibody induction against p55.

Adjuvants, Immunologic↗
PubMed2000

BSAP (Pax5)-importin alpha 1 (Rch1) interaction identifies a nuclear localization sequence.

BSAP (Pax5) is an essential transcription factor for early B cell and central nervous system development. In later B cell development, BSAP has been implicated in the regulation of 3' Ig enhancers and a number of B cell-specific genes. Previous studies have suggested a role for BSAP-interacting proteins in the regulation of the function of BSAP. Using the yeast two-hybrid system, we identified importin alpha1 (Rch1) as a BSAP-interacting protein. Importin alpha proteins have been shown to escort proteins into the nucleus through interaction with a nuclear localization signal (NLS), composed of short stretches of basic amino acids. A predicted NLS in BSAP (NKRKRDE, located at amino acids 195-201 in the central domain) was confirmed to be essential for interaction with importin alpha1 by the yeast two-hybrid assay. Physical interaction between BSAP and importin alpha1 was detected in vitro by a glutathione S-transferase (GST) pulldown assay. The NLS sequence in BSAP conferred nuclear localization to green fluorescent protein (GFP)-BSAP fusion proteins. Although the N-terminal paired (DNA-binding) domain of BSAP also conferred nuclear localization when coupled to green fluorescent protein, this domain did not bind to importin alpha1 in the yeast two-hybrid assay. The NLS sequence in the central domain of BSAP binds to the C-terminal 98-amino acid fragment of importin alpha1.

Animals↗
PubMed2000

Formulation and evaluation of ophthalmic preparations of acetazolamide.

The orally administered acetazolamide has a limited use in glaucoma due to the systemic side effects associated with its use. It has been reported to show little effect on the intraocular pressure (IOP) of human and rabbit eyes upon topical application, probably owing to its poor bioavailability and instability at pH >5.0. In order to enhance the bioavailability of the drug, contact time between the drug molecules and the ocular surface was increased using high viscosity, water soluble polymers (PVA, HPMC), and by incorporating acetazolamide into an in situ-forming ophthalmic drug delivery system. Moreover, a penetration enhancer (EDTA) was also used in these formulations to increase the extent of absorption of the drug. Acetazolamide at a concentration of 10% was used and the formulations (eyedrop suspensions) were evaluated for their in vitro release pattern. The effect of these formulations on the IOP in normotensive conscious rabbits was also investigated. These formulations were found to be therapeutically effective with a peak effect at 2 h. A fall in IOP of up to 46.4% was observed with repeated administration of one of the formulation containing PVA, EDTA and Tween 80 (MK-5). Results indicated that a topical effect of acetazolamide can be observed if the formulation, (a) contains a suitable polymer-to increase the residence time; (b) a penetration enhancer-as acetazolamide has a low permeability coefficient i.e. 4. 1x10(-6) cm/s [Duffel, M.W., Ing. I.S., Segarra, T.M., Dixson, J.A., Barfknecht, C.F., Schoenwald, R.D., 1986. J. Med. Chem. 29, 1488-1494]; and (c) pH of the formulation is maintained at the point of maximum stability (pH< or =5.0).

Acetazolamide↗
PubMed2000

Cloning and characterization of a new theta-class glutathione-S-transferase (GST) gene, gst-3, from Drosophila melanogaster.

We report here on the cloning and characterization of a new theta-class glutathione-S-transferase (GST) gene, gst-3, from Drosophila melanogaster. Its sequence is distinct from previously characterized Drosophila GST genes, and Southern blotting shows no other closely related genes in the genome. In-situ hybridization localizes the gene to chromosome 2 (55D), near gst-2 (53F), and clearly separate from the gst-D cluster at 87B. The gene is intronless and appears to possess conventional 5' TATA, Cap and 3' polyadenylation signals. A single transcript, approximately 1kb in size, appears to be expressed at high levels in all developmental stages examined. When this gene is overexpressed using various upstream GAL4 driver systems, no striking phenotypes are observed; however, we detect bristle morphology defects in some progeny. The gst-3 gene does not appear to be essential, based upon our observation that mutant flies homozygous for an EP element insertion 5' to the TATA box produce little or no detectable gst-3 mRNA; these flies are viable and fertile at 25 and 29 degrees C. Nevertheless, the gst-3 gene appears to be evolutionarily conserved in other Drosophila species, suggesting that it may be functionally important.

Amino Acid Sequence↗
PubMed2000

Physics and instrumentation for imaging in-vivo drug distribution.

Several imaging methods are currently available to measure drugs noninvasively. Of these, two techniques are today central to such measurements: nuclear imaging and magnetic resonance imaging/spectroscopy (MRI and MRS). While other methods, such as optical techniques, are rapidly gaining in interest, they have not yet attained the degree of development that makes them effective in measuring drugs in living systems, except in a small number of examples. The following introduction provides some basic elements of the potential and the limitations of both nuclear imaging and MRI/MRS techniques, methods that will be used in the studies described in the articles in this issue. However, and for those desiring to gain a better understanding of both methods, the reader is advised to consult much more extensive reviews and books describing such methods. A suggested list of books and articles on Nuclear Imaging and MRI/MRS is given.

Diagnostic Imaging↗
PubMed2000

Microparticles in MF59, a potent adjuvant combination for a recombinant protein vaccine against HIV-1.

Novel adjuvant formulations involving PLG microparticles with entrapped recombinant protein antigens (env gp120 and p24 gag) from human immunodeficiency virus type-1 (HIV-1), dispersed in the emulsion adjuvant MF59 were evaluated as potential HIV-1 vaccine candidates in mice and baboons. In mice, the adjuvant combination induced significantly enhanced antibody responses in comparison to either adjuvant used alone. In addition, the polylactide co-glycolide polymer (PLG) microparticles and MF59 combination induced CTL activity against HIV-1 p24 gag. In baboons, the adjuvant combination induced significantly enhanced antibody titers after a single dose of gp120, but the responses were comparable to gp120 in MF59 alone after boosting. Both MF59+gp120 alone and PLG/gp120 in MF59 induced neutralizing antibodies against a T cell line-adapted (TCLA) strain and a primary isolate of HIV-1. In contrast to the observations with gp120, immunization in baboons with PLG/p24 in MF59 induced significantly enhanced antibody responses after boosting, in comparison to immunization with MF59 alone + p24.

AIDS Vaccines↗
PubMed2000

Evidence for a trypanothione-dependent peroxidase system in Trypanosoma cruzi.

Hydroperoxide metabolism in Crithidia fasciculata has recently been shown to be catalyzed by a cascade of three oxidoreductases comprising trypanothione reductase (TR), tryparedoxin (TXN1), and tryparedoxin peroxidase (TXNPx) (Nogoceke et al., Biol. Chem. 378, 827-836, 1997). The existence of this metabolic system in the human pathogen Trypanosoma cruzi is supported here by immunohistochemistry. Epimastigotes of T. cruzi display strong immunoreactivity with antibodies raised against TXN1 and TXNPx of C. fasciculata. In addition, a full-length open reading frame presumed to encode a peroxiredoxin-type protein in T. cruzi (Acc. Nr. AJ 012101) was heterologously expressed in Escherichia coli and shown to exhibit tryparedoxin peroxidase activity. With TXN, TXNPx, trypanothione and TR, T. cruzi possesses all components constituting the crithidial peroxidase system. It is concluded that the antioxidant defense of T. cruzi also depends on the NADPH-fuelled, trypanothione-mediated enzymatic hydroperoxide metabolism.

Amino Acid Sequence↗
PubMed2000

A conserved mycobacterial heat shock protein (hsp) 70 sequence prevents adjuvant arthritis upon nasal administration and induces IL-10-producing T cells that cross-react with the mammalian self-hsp70 homologue.

Immunization with Mycobacterium tuberculosis heat shock protein (hsp) 60 has been shown to protect rats from experimental arthritis. Previously, the protection-inducing capacity was shown to reside in the evolutionary conserved parts of the molecule. Now we have studied the nature of the arthritis suppressive capacity of a distinct, antigenically unrelated protein, M. tuberculosis hsp70. Again, a conserved mycobacterial hsp70 sequence was found to be immunogenic and to induce T cells that cross-reacted with the rat homologue sequence. However, in this case parenteral immunization with the peptide containing the critical cross-reactive T cell epitope did not suppress disease. Upon analysis of cytokines produced by these peptide-specific T cells, high IL-10 production was found, as was the case with T cells responsive to whole hsp70 protein. Nasal administration of this peptide was found to lead to inhibition of subsequent adjuvant arthritis induction. The data presented here shows the intrinsic capacity of conserved bacterial hsp to trigger self-hsp cross-reactive T cells with the potential to down-regulate arthritis via IL-10.

Administration, Inhalation↗
PubMed2000

Estrogen-induced activation of the mitogen-activated protein kinase cascade in the cerebral cortex of estrogen receptor-alpha knock-out mice.

We have shown previously in the developing cerebral cortex that estrogen elicits the rapid and sustained activation of multiple signaling proteins within the mitogen-activated protein (MAP) kinase cascade, including B-Raf and extracellular signal-regulated kinase (ERK). Using estrogen receptor (ER)-alpha gene-disrupted (ERKO) mice, we addressed the role of ER-alpha in mediating this action of estrogen in the brain. 17beta-Estradiol increased B-Raf activity and MEK (MAP kinase/ERK kinase)-dependent ERK phosphorylation in cerebral cortical explants derived from both ERKO and their wild-type littermates. The ERK response was stronger in ERKO-derived cultures but, unlike that of wild-type cultures, was not blocked by the estrogen receptor antagonist ICI 182,780. Surprisingly, both the ER-alpha selective ligand 16alpha-iodo-17beta-estradiol and the ER-beta selective ligand genistein failed to elicit ERK phosphorylation, suggesting that a different mechanism or receptor may mediate estrogen-induced ERK phosphorylation in the cerebral cortex. Interestingly, the transcriptionally inactive stereoisomer 17alpha-estradiol did elicit a strong induction of ERK phosphorylation, which, together with the inability of the ER-alpha- and ER-beta-selective ligands to elicit ERK phosphorylation, and of ICI 182,780 to block the actions of estradiol in ERKO cultures, supports the hypothesis that a novel, estradiol-sensitive and ICI-insensitive estrogen receptor may mediate 17beta-estradiol-induced activation of ERK in the brain.

Animals↗
PubMed2000

Effect of age on the outcome of angioplasty for acute myocardial infarction among patients treated at the Mayo Clinic.

PURPOSE: Elderly patients, especially those 80 years of age and older, have been excluded from most studies of thrombolysis or primary coronary angioplasty in patients with acute myocardial infarction. We compared the outcomes of elderly patients who underwent coronary angioplasty with the outcomes of younger patients and determined whether there were any temporal trends in survival. PATIENTS AND METHODS: We reviewed the outcomes of 1,597 consecutive patients who underwent primary coronary angioplasty between 1979 and 1997, including 127 patients who were 80 years of age or older (mean [+/-SD] age, 83 +/- 3 years, 47% male). Their in-hospital and long-term outcomes were compared with those of 524 patients who were 70 to 79 years old, 527 patients who were 60 to 69 years old, and 419 patients who were 50 to 59 years old. The oldest group of patients was divided into two groups, based on whether they had intervention through the end of 1993 (n = 56) or between 1994 and 1997 (n = 71). The survival rate of the patients who had no complications and left the hospital was compared with expected survival based on age- and sex-adjusted data. RESULTS: Patients 80 years of age or older had more adverse baseline characteristics, including risk factors and comorbid conditions, than the younger patients. The clinical success rate of primary angioplasty in this group was lower than those in the other three groups (61% versus 74% in those aged 70 to 79 years, 73% in those aged 60 to 69 years, and 81% in those aged 50 to 59 years, P < 0.001). The in-hospital mortality rate among patients 80 years of age or older was significantly greater than among patients in the other three groups (21% in those aged 80 years or older, 13% in those aged 70 to 79 years, 9% in those aged 60 to 69 years, and 4% in those aged 50 to 59 years, P < 0.001 ). The clinical success rate of the angioplasty improved significantly in the more recent period (75% versus 45%, P = 0.0006) and in-hospital mortality declined (16% versus 29%, P = 0.07). During follow-up, mortality in the oldest age group in whom angioplasty was successful was significantly greater than in the three younger groups, but was similar to the expected survival in the general US population. CONCLUSIONS: The mortality associated with primary angioplasty for acute myocardial infarction in octogenarians remains high, although there has been significant improvement in the clinical success rate. The long-term prognosis following a successful angioplasty is not different from that in an age- and sex-adjusted U.S. white population.

Age Factors↗
PubMed2000

Cationic microparticles: A potent delivery system for DNA vaccines.

An approach involving the preparation of biodegradable microparticles with a cationic surface was developed to improve the delivery of adsorbed DNA into antigen-presenting cells after i.m. injection. The microparticles released intact and functional DNA over 2 weeks in vitro. In addition, the microparticles induced higher levels of marker gene expression in vivo. After i.m. immunization, the microparticles induced significantly enhanced serum antibody responses in comparison to naked DNA. Moreover, the level of antibodies induced by the microparticles was significantly enhanced by the addition of a vaccine adjuvant, aluminum phosphate. In addition, in contrast to naked DNA, the cationic microparticles induced potent cytotoxic T lymphocyte responses at a low dose.

Animals↗
PubMed2000

Nebulised anti-pseudomonal antibiotics for cystic fibrosis.

BACKGROUND: Lung damage associated with persistent infection by Pseudomonas aeruginosa is the major cause of morbidity and mortality in people with cystic fibrosis. Nebulised antibiotics are commonly used for treatment of this infection. OBJECTIVES: To examine the evidence that nebulised anti-pseudomonal antibiotic treatment in patients with cystic fibrosis reduces frequency of exacerbations of infection, improves lung function, quality of life and survival. To assess adverse effects of nebulised anti-pseudomonal antibiotic treatment. SEARCH STRATEGY: Trials were identified from the Cochrane Cystic Fibrosis and Genetic Disorders Group clinical trials register. Companies which marketed nebulised anti-pseudomonal antibiotics were contacted for information on unpublished trials. Date of the most recent search of the Group's specialised register: November 1999. SELECTION CRITERIA: Trials were selected if, nebulised anti-pseudomonal antibiotics treatment was used in patients with cystic fibrosis, treatment was used for four weeks or more, allocation to treatment was randomised or pseudo-randomised, and there was a placebo or a no placebo control group. DATA COLLECTION AND ANALYSIS: References to nebulised antibiotics were retrieved from the register. Two reviewers independently selected trials from this sample according to the criteria. Each judged the quality of selected trials. One reviewer extracted data from these trials. MAIN RESULTS: Ten trials with 758 participants were included in the review. Sixty eight % of participants were in one trial. Duration of trials ranged from one to 32 months. There was large variation in study design and outcome measures which limited meta-analysis. Lung function measured as forced expired volume in one second (FEV1) was generally better in the treated groups than in control groups but a pooled estimate of effect was not possible. In the largest trial of 520 participants the FEV1 was 11.9% predicted (95% confidence interval 8.1to 15.6) higher in the treated group than in the placebo control group after 5 months. In three trials with 581 participants the number of participants having at least one hospital admission during a trial was reduced in the groups treated with nebulised antibiotics, odds ratio 0.69 (95% confidence Interval 0.50 to 0.96). In two trials with 591 participants the number of participants having and at least one course of antibiotic therapy was reduced in the treated group, odds ratio 0.62 (95% confidence interval 0.45 to 0.87). There was no evidence of renal or auditory toxicity. Resistance to antibiotic increased more in the antibiotic treated group than in placebo group. The most evidence for a single drug is for tobramycin, which was used in total daily doses from 40mg to 1800mg. REVIEWER'S CONCLUSIONS: Nebulised anti-pseudomonal antibiotic treatment improves lung function and reduces frequency of exacerbations of infection in people with cystic fibrosis. There is a need for more evidence for effect on quality of life and survival, for longer duration trials to determine if this benefit is maintained and to determine the significance of development of antibiotic resistant organisms.

Administration, Inhalation↗
PubMed2000

Heated, humidified air for the common cold.

OBJECTIVES: To assess the effects of inhaling heated water vapour with the help of a rhinotherm (an equipment designed to deliver heated water vapour to a person's nasal cavity), in the treatment of the common cold by comparing a. symptoms b. viral shedding c. nasal resistance after a natural or experimentally induced common cold. SEARCH STRATEGY: We searched MEDLINE with MeSH headings: common cold, rhinopharyngitis, inhalation, steam, heated vapour, rhinothermy, till July 1999. EMBASE, Current Contents, review articles, cross references were also searched. Attempts were also made to contact the manufacturers for any unpublished data. SELECTION CRITERIA: Randomized trials using heated water vapour in a standardized way in patients with the common cold or volunteers with experimental induction of rhinovirus infection were included in the review. DATA COLLECTION AND ANALYSIS: All the articles retrieved were initially subjected to a review for inclusion / exclusion criteria. Review articles, editorials, abstracts with inadequate outcome description were excluded. Studies selected for inclusion were subjected to a methodological assessment. MAIN RESULTS: The results of a systematic review of six trials with 319 participants, support the use of warm vapour inhalations in the common cold in terms of relief of symptoms (Odds Ratio with 95 % CI 0.31, 0.16-0.60, Relative risk 0.56, 0.4-0. 79). Results on symptom score indices were equivocal. None of the studies demonstrated a worsening of clinical symptom scores. One study demonstrated increased nasal resistance one week after steam inhalation in contrast to an earlier study which showed improvement in the nasal resistance. There was no evidence of decreased viral shedding measured by virus isolation in the nasal secretions (Tyrrell 1989) or measurement of viral titres in nasal washings among treatment group. The rhinovirus titres in the nasal washings from the treatment group were the same as those of the placebo group on day one prior to the treatment and on all four days after the treatment. The area under curve (Hendley 1994) was also similar in the placebo and treatment groups for titres of virus in the nasal washings as were the average viral titres across five days of follow up, the maximum values after treatment, and viral shedding velocity i.e. amount of virus shed per day (Hendley 1994). Minor side effects due to thermal stress were reported in all the studies. REVIEWER'S CONCLUSIONS: Three trials demonstrated beneficial effects on the symptoms of the common cold. One study from Israel showed a decrease in nasal resistance measured by peak nasal expiratory and inspiratory flow rate. Studies done in North America failed to show any objective improvement in outcome measures with the study intervention. A multi-centre double blind randomised controlled trial testing this therapy with uniform outcome measures is recommended.

Air↗
PubMed2000

The role of gammadelta T cells in generating antiviral factors and beta-chemokines in protection against mucosal simian immunodeficiency virus infection.

In view of the role of gammadelta(+) T cells in mucosal protection against infection, the proportion of gamma delta T cells was examined in cells eluted from lymphoid and mucosal tissues of macaques immunized with simian immunodeficiency virus (SIV) gp120 and p27 in alum and challenged with live SIV by the rectal mucosal route. This revealed a significant increase in gammadelta T cells eluted from the rectal mucosa (p < 0.01) and the related iliac lymph nodes (p < 0.0001) in protected as compared with infected macaques. Preferential homing of PKH-26-labeled gammadelta(+) T cells from the primed iliac lymph nodes to the rectal and cervico-vaginal mucosa was demonstrated after targeted iliac lymph node as compared with i. m. immunization. Investigations of the mechanism of protection revealed that gammadelta(+) T cells can generate antiviral factors, RANTES, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta which can prevent SIV infection by binding to the CCR5 coreceptors. Up-regulation of gammadelta(+) T cells was demonstrated by immunization of macaques with heat shock protein (HSP)70 linked to peptides and with granulocyte-macrophage colony-stimulating factor (GM-CSF). This was confirmed by in vitro studies showing that GM-CSF can up-regulate gammadelta(+) T cells from macaques immunized with HSP-linked peptides but not those from naive animals. We suggest that a novel strategy of immunization with HSP70 linked to antigen may generate both cognate immunity to the antigen and innate immunity by virtue of up-regulation of gammadelta(+) T cells. These cells generate antiviral factors and the three beta-chemokines that prevent binding and transmission of SIV or M-tropic HIV by the CCR5 coreceptor.

Animals↗