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Biomedical subjects

M Singh

Publications and source records attributed to M Singh.

At least 415 records · Page 23Linked to original sources
PubMed1998

Anti-tumor immunity induced by murine melanoma cells transduced with the Mycobacterium tuberculosis gene encoding the 38-kDa antigen.

The Mycobacterium tuberculosis Ag38 gene, which encodes a highly immunogenic protein, was cloned into a retroviral vector in-frame with the leader and the transmembrane portion of the nerve growth factor receptor, and transduced into murine melanoma cell line B16-B78. Significant protection was observed in mice immunized with the transduced melanoma cells and subcutaneously challenged with parental melanoma cells since only 20% of mice developed tumors. Necroscopy of mice immunized with the transduced melanoma cells revealed dramatic inhibition of experimental metastases induced by intravenous (i.v.) inoculation of parental melanoma cells. Moreover, vaccination with transduced cells significantly prolonged survival of mice challenged i.v. with parental melanoma cells. These data indicate that the presence of the mycobacterial 38-kDa protein greatly enhances immunological recognition of structures expressed by the parental melanoma cells. Comparison of Th1 and Th2 responses in mice immunized with parental melanoma cells versus mice receiving the transduced cells revealed a clear predominance of Th1 responses when the Ag38 protein was endogenously expressed. This transduction approach may represent a promising immunotherapeutic strategy for the treatment of cancer patients.

Animals↗
PubMed1998

Differences in stratum corneum pH gradient when comparing white Caucasian and black African-American skin.

This study assessed pH gradient changes in relation to stratum corneum (SC) depth and possible differences between white caucasian and black African-American skin. Ten white and eight black people entered the study. SC was progressively removed by cellophane tape stripping on the volar forearm and weighed with a microbalance. Transepidermal water loss (TEWL) and SC pH were measured every three tape strippings. Significantly increased TEWL and decreased pH values were found with increasing SC depth in both races. Significantly increased TEWL in black people was found after three and six tape strippings (P < 0.05 and 0.03, respectively); pH was significantly decreased in black people after three tape strippings (P < 0.005). No differences were found between the races after nine, 12 and 15 strippings, i.e. in the deeper SC layers. The data confirm that pH in the superficial SC layers decreases with SC depth; only total SC removal results in increased pH values. In the superficial layers, there are significant differences in both water evaporation and skin pH, possibly explaining the contradictory literature.

Adult↗
PubMed1998

IgG subclass distribution of antibody responses to protein and polysaccharide mycobacterial antigens in leprosy and tuberculosis patients.

Immunoenzymatic assays were developed for the measurement of antibodies against mycobacterial lipoarabinomannan (LAM), a cell-free proteic extract (CFX) of Mycobacterium leprae, and the 38-kD protein antigen of M. tuberculosis. Sera from 108 leprosy patients, belonging to all clinical-immunological forms of the spectrum, and 81 patients with localized or disseminated tuberculosis (TB) were tested for antibodies of the four IgG subclasses. Standard calibration curves were used to allow comparisons between results of different isotypes and specificities. Mean concentrations of total IgG antibodies were higher in the overall leprosy population than in TB patients. In leprosy, levels of anti-CFX increased from tuberculoid toward lepromatous forms, with a clear switch from IgG1 to IgG2 subclass predominance. A similar IgG1 to IgG2 conversion was observed in anti-LAM antibodies, although total levels of anti-LAM were similar in patients with tuberculoid and lepromatous forms. In TB, antibodies against polysaccharide and protein antigens were both predominantly of IgG1 subclass, whatever the patient's clinical status, although lower in disseminated forms, probably due to concomitant HIV infection. A hypergammaglobulinaemia was also found in most leprosy and TB patients. In TB this was due to increased IgG1 and IgG3, especially in HIV co-infected patients. Based on the current knowledge of the influence of T cell-secreted cytokines on human immunoglobulin isotype expression, these results do not fit with a putative role of Th1 (such as found in TB and tuberculoid leprosy (TT)) and Th2 (such as found in leprosy lepromatous (LL) leprosy) environment in the isotypy of antibody responses in mycobacterial infections. Nor do variations of isotypy according to pathological conditions seem to be related to the biochemical nature of antigens, since antibodies to LAM and protein antigens had comparable evolutions of their subclass distribution. Other factors are to be investigated in order to understand better the significance and possible roles of antibodies in mycobacterial diseases.

Adolescent↗
PubMed1998

Novel delivery systems for coagulation proteins.

Long-term haemophilia prophylaxis with clotting factors administered by alternative delivery modes requires stable liquid formulations of these factors. We developed an aqueous-formulated human coagulation factor IX (hCFIX) with in vitro half-life (T 1/2) of 6 weeks at 37 degrees C and 18 months at 4 degrees C. Upon bolus subcutaneous (s.c.) injection in animals, hCFIX had a bioavailability of up to 16% compared to intravenous (i.v.) dose. When delivered by s.c. implanted pumps, hCFIX attained > 2% of normal human levels in the animal plasma. Hydrogels of hCFIX in a chitosan derivative, N,O-carboxymethyl chitosan (NOCC), released hCFIX slowly in vitro, and when injected s.c., gave prolonged plasma levels over those obtained by bolus i.v. or s.c. injection. Freeze-dried human coagulation factor VIII (hCFVIII) formulated in non-aqueous solvents had in vitro T 1/2 up to 80 days at 37 degrees C.

Administration, Cutaneous↗
PubMed1998

Human T- and B-cell reactivity to the 16kDa alpha-crystallin protein of Mycobacterium tuberculosis.

The attributes of immunodominance, predominant expression during mycobacterial dormancy and restriction to the Mycobacterium tuberculosis complex make the 16 kDa protein an important candidate for the study of the immune response in humans. We therefore investigated the relationship between T- and B-cell reactivity to the recombinant antigen and disease in a total of 127 subjects. The percentage of T-cell responders towards both the intact antigen and its permissively recognised peptide 16p91-110 was highest in healthy bacillus Calmette-Guérin (BCG)-sensitized controls (96% and 68%, respectively) and lowest in those with extensive untreated tuberculosis (26% and 18%) (P < 0.001). By contrast, antibody levels (ABT50 > 100) were highest in patients with extensive disease (46-50%) (P < 0.005). There was significantly higher production of IFN-gamma in the BCG-sensitized controls by comparison with untreated patients (P < 0.05), but complete antituberculous chemotherapy abolished this deficit in patients. The significance of these findings to immunodiagnosis and protective immunity is discussed.

Antigen Presentation↗
PubMed1998

Transurethral electrovaporization of the prostate--a possible alternative to transurethral resection: a one-year follow-up of a prospective randomized trial.

OBJECTIVE: To compare the efficacy, safety and durability of transurethral electrovaporization of the prostate (TUVP) with standard transurethral resection (TURP) in a prospective randomized trial. PATIENTS AND METHODS: The study included 104 consecutive men with symptomatic benign prostatic hyperplasia (BPH) admitted for surgery who were randomized to TUVP or TURP. The variables evaluated included the duration of surgery, catheterization and hospital stay, the International Prostate Symptom Score (IPSS), a quality-of-life assessment (QOL), the maximum urinary flow rate (Qmax) and the postvoid residual urine volume (PVR). RESULTS: Both groups showed a comparable significant and maintained decline in the mean IPSS, from 26.5 to 4.4 (TUVP) and from 26.6 to 5.9 (TURP), and increase in mean Qmax, from 8.6 to 20.8 mL/s [corrected] (TUVP) and 8.6 to 22.8 mL/s (TURP) after 1 year. However, there were significant differences in the mean duration of catheterization (TUVP 20.9 h, TURP 46.6 h, P<0.001), hospital stay (TUVP 2.2 day, TURP 3.1 days, P<0.001), and the duration and volume of post-operative irrigation (TUVP none, TURP 18.1 h with 17.5 L of saline). Two patients in each group developed urethral strictures (4%) and two patients in each group required re-operation for residual adenoma (4%); two patients undergoing TURP had a bladder neck stricture (4%). CONCLUSION: The results suggest that TUVP is as effective as standard TURP in the treatment of moderate-sized BPH. TUVP offers the advantage of using established instruments, has excellent peri-operative haemostasis and requires a shorter hospital stay.

Aged↗
PubMed1998

Hospital outcomes management: the Care Continuum and Health Outcomes Project.

The Care Continuum and Health Outcomes Project is part of a national initiative to build an outcomes management approach in health care. This paper examines the baseline performance of the study. In 1995-96, 7154 Australian Capital Territory hospital inpatients were selected to take part in a five-wave survey over six months. In addition to the survey, the project involved the unit record linkage of routine data collections. A total of 5668 people (79%) agreed to participate in the survey, with 85% of these people agreeing to release their Medicare data. There were significant variations in participation rates between hospitals and wards. Factors contributing to these variations included patient socioeconomic status, disease type and illness severity. In conclusion, the success in establishing the project indicates that it is possible to conduct a broad scientific study within the health system, and that there are strong implications that ongoing scientific evaluations can be embedded within routine clinical practice.

Adult↗
PubMed1998

Is zero dose oral polio vaccine effective in preterm babies?

A randomized controlled trial was done to compare seroconversion following a single dose of trivalent oral polio vaccine (TOPV) in preterm babies, vaccinated at two different post-conception ages, with that of term newborns. Sixty-two consecutive preterm babies < or = 35 weeks were randomly allocated to two groups. Group A was vaccinated 'early' at 34-35 weeks and group B 'late' at 38-40 weeks post conception. The two groups were comparable in birthweight [mean (SD) 1594 g (118) and 1599 g (126), respectively] and gestational age [mean (SD) 33.2 (1.2) and 33 (1.3) weeks, respectively]. A control group of 36 term babies (group C) were vaccinated in the 1st week of life. Polio virus antibodies were measured immediately before and 6-8 weeks after vaccination. Group A had seroconversion rates of 54.2, 12.5 and 12.5% against polio virus types 1, 2 and 3, respectively, group B had rates of 60.0, 8.0 and 16.0%, and group C rates of 53.6, 10.7 and 14.3%. Differences in the seroconversion rates in the three groups were not statistically significant. The conversion rates against types 2 and 3 are much lower than in previous studies. We conclude that preterm babies vaccinated at 34-35 weeks post conception show seroconversion rates similar to those in term newborns.

Humans↗
PubMed1998

Temporal sequence of mammary intraductal proliferations, ductal carcinomas in situ and adenocarcinomas induced by 1-methyl-1-nitrosourea in rats.

An experimental model for mammary carcinogenesis has been described in which intraductal proliferations, ductal carcinomas in situ and adenocarcinomas can be readily detected and the frequency of their occurrence quantified. The objective of the experiment reported in this study was to determine the latency period between carcinogen administration and the occurrence of each of these types of lesion. A total of 150 female Sprague-Dawley rats were injected i.p. with 50 mg 1-methyl-1-nitrosourea (MNU)/kg body wt at 21 days of age. Groups of 30 rats each were killed at 7, 14, 21, 28 and 35 days post-carcinogen. Mammary intraductal proliferations were the first detected lesions and were observed in 20% of the animals at 14 days following carcinogen administration. At 21 days post-carcinogen ductal carcinomas in situ and adenocarcinomas were observed. The number of each type of lesion increased with time post-carcinogen, but the temporal pattern of occurrence was different among lesion types. The pattern of lesion occurrence was consistent with intraductal proliferations being a precursor lesion for ductal carcinomas in situ and adenocarcinomas. Furthermore, the data imply that ductal carcinomas in situ represent one pathway of morphological progression by which intraductal proliferations evolve into invasive carcinomas, but that this lesion type, as currently defined histologically, may not be an obligatory intermediate in morphologic progression. These findings are consistent with emerging evidence of multiple but distinct pathogenetic pathways leading to mammary carcinomas that display different morphological patterns and biological activities.

Adenocarcinoma↗
PubMed1998

Ovarian hormone dependence of pre-malignant and malignant mammary gland lesions induced in pre-pubertal rats by 1-methyl-1-nitrosourea.

The experiments reported in this study were designed to examine the question of whether a mammary epithelial cell's independence from hormonal requirements is established at the time of carcinogenic initiation, or whether the emergence of hormone independence is associated with the process of tumor progression. A newly developed rat model of mammary carcinogenesis was used in which the latency period to lesion detection is very short and in which the frequencies of both pre-malignant and malignant mammary lesions can be quantified. Two experiments were conducted in Sprague-Dawley rats injected with 50 mg MNU/kg body wt at 21 days of age. In the first experiment 47 animals were ovariectomized after the detection of a mammary tumor of palpable size. Forty-six of the 47 tumors assessed, all of which were subsequently classified as mammary gland adenocarcinomas, regressed to <50% of their initial volume within 14 days of bilateral ovariectomy. However, both pre-malignant and malignant mammary gland lesions were observed when animals were killed. In Experiment 2 a total of 60 rats were ovariectomized 7 days after MNU was injected. At 35 days post carcinogen ovariectomized animals had a higher incidence of intraductal proliferations than sham-operated controls (P = 0.03); there was no effect of ovariectomy on the incidence of ductal carcinoma in situ or carcinoma. The multiplicity of intraductal proliferations was increased by 58% in ovariectomized rats (P = 0.12), but the number of mammary carcinoma per rat was reduced (3.8 vs. 1.57, P = 0.02). These data are consistent with the hypotheses that the progression of pre-malignant to malignant lesions is inhibited in the mammary gland by ovariectomy and that the hormone independent phenotype can be conferred at the time of carcinogenic initiation.

Adenocarcinoma↗
PubMed1998

Mechanism of inhibition of benzo[a]pyrene-induced forestomach cancer in mice by dietary curcumin.

Curcumin (diferuloylmethane), the major yellow pigment in turmeric, has been shown to inhibit benzo[a]pyrene (BaP)-induced forestomach cancer in mice through mechanism(s) not fully understood. It is well known that while cytochrome P4501A1 (CYP1A1) and epoxide hydrolase (EH) are important in the conversion of BaP to its activated form, (+)-anti-7,8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BaPDE], the detoxification of (+)-anti-BaPDE is accomplished by glutathione (GSH) S-transferases (GST). Therefore, it seems reasonable to postulate that curcumin may exert anti-carcinogenic activity either by inhibiting activation of BaP or (and) by enhancing the detoxification of (+)-anti-BaPDE. Administration p.o. of 2% curcumin in the diet to female A/J mice for 14 days, which has been shown to cause a significant inhibition in BaP-induced forestomach tumorigenesis, resulted in a modest but statistically significant reduction in hepatic ethoxyresorufin O-deethylase (EROD) activity, a reaction preferentially catalyzed by CYP1A1. While EROD activity could not be detected in the forestomach of either control or treated mice, curcumin feeding caused a statistically significant increase (approximately 2.3-fold) in hepatic EH and GST activities. Hepatic and forestomach GSH levels, and forestomach EH and GST activities were not affected by curcumin treatment. Even though the levels of various hepatic GST isoenzymes were significantly increased upon curcumin feeding, maximum induction was noticed for the pi class isoenzyme (mGSTP1-1), which among murine hepatic GSTs is highly efficient in the detoxification of (+)-anti-BaPDE. In conclusion, the results of the present study suggest that curcumin may inhibit BaP-induced forestomach cancer in mice by affecting both activation as well as inactivation pathways of BaP metabolism in the liver.

Animals↗
PubMed1998

The regulatory role of heat shock protein 70-reactive CD4+ T cells during rat listeriosis.

Protection against infection with Listeria monocytogenes depends primarily on Listeria-specific T cells. We show here that CD4+ TCR alphabeta+ T cells are capable of recognizing the mycobacterial heat shock protein (HSP) 70, that appears in the peritoneal cavity of F344 rats infected i.p. with L. monocytogenes. The HSP70-reactive CD4+ T cells recognized a peptide comprising 234-252 residues as present in the 70 kDa HSP of Mycobacterium tuberculosis in the context of RT1.B MHC class II molecules. Analysis of TCR Vbeta gene expression with RT-PCR revealed that the HSP70-reactive CD4+ T cells predominantly used the Vbeta16 gene segment, whereas the heat-killed Listeria (HKL)-specific T cells expressed a diverse set of Vbeta gene segments. In contrast to the HKL-specific T cells producing IFN-gamma, the HSP70-reactive CD4+ T cells produced TGF-beta1 and IL-10 but neither Th1- or Th2-type cytokines. Adoptive transfer with HSP70-reactive T cells rendered rats susceptible to listerial infection. Collectively, these results proposed that the HSP70-reactive CD4+ T cells appearing during rat listeriosis may be involved in termination of Th1 cell-mediated excessive inflammation after the battle against L. monocytogenes has been won.

Adoptive Transfer↗
PubMed1998

Cardiac mast cell stabilization and cardioprotective effect of ischemic preconditioning in isolated rat heart.

This study was designed to investigate the effect of disodium cromoglycate (DSCG), a mast cell stabilizer, on cardioprotective effect of ischemic preconditioning. Isolated rat heart was subjected to 30 min of global ischemia followed by 30 min of reperfusion. Ischemic preconditioning was provided by four episodes of 5-min global ischemia followed by 5 min of reperfusion before sustained ischemia. Ischemic preconditioning and DSCG (10 and 100 microM) treatment markedly decreased the release of lactate dehydrogenase (LDH) and creatine kinase (CK) in coronary effluent and percentage incidence of ventricular premature beats (VPBs) and ventricular tachycardia/fibrillation (VT/VF) during reperfusion. Ischemic preconditioning and DSCG treatment also significantly reduced ischemia/reperfusion-induced mast cell peroxidase (MPO) release, a marker of mast cell degranulation. A significant increase in MPO release was observed immediately after ischemic preconditioning, and the release was found to be inhibited in hearts perfused with DSCG (10 and 100 microM) during ischemic preconditioning. DSCG administered during ischemic preconditioning (DSCG in ischemic preconditioning) attenuated the cardioprotective and antiarrhythmic effects of ischemic preconditioning. DSCG in ischemic preconditioning produced no marked effect on ischemia/reperfusion-induced MPO release. These findings tentatively suggest that DSCG administration during ischemic preconditioning abolishes its cardioprotective effect, perhaps by stabilizing resident cardiac mast cells.

Animals↗
PubMed1998

Immunotherapy with Mycobacterium vaccae in the treatment of psoriasis.

A placebo-controlled study of immunotherapy with Mycobacterium vaccae for chronic plaque psoriasis showed improvement in the psoriasis area severity index in 19 of 21 immunotherapy recipients (P<0.005). Minor improvement, not reaching statistical significance for the group, occurred in nine of 14 placebo recipients. There were losses to follow-up and the placebo used, tetanus toxoid, was not ideal. Clinical improvement after immunotherapy persisted for 6 months and another injection of the immunotherapeutic given to a few volunteers from either group resulted in benefits lasting a year. Lymphoproliferative tests were carried out at each clinic visit, and on 50 matched controls. Starting with reduced responses to mycobacterial antigens and concanavalin A, both treatment groups showed a fall after 3 months, and diverged at 6 months with M. vaccae recipients rising to values similar to those of healthy controls, whereas placebo recipients continued to fall. Conclusions reached were that immunotherapy with M. vaccae gave long-lasting clinical benefit to most patients, with minimal side effects. This accompanied a return towards normal cellular immune responsiveness to mycobacterial antigens, which did not follow the use of the placebo.

Adult↗
PubMed1998

Regain of fertility and normality of progeny born during below protective threshold antibody titers in women immunized with the HSD-hCG vaccine.

PROBLEM: Phase II clinical trials with the heterospecies dimer of beta hCG and alpha-subunit of ovine luteinizing hormone (HSD)-human chorionic gonadotrophin (hCG) vaccine showed that pregnancy was prevented at and above 50 ng/ml titers, whereas conceptions occurred below 35 ng/ml of hCG bioneutralization capacity. The effect of below-protective threshold anti-hCG antibodies on the progression of pregnancy and the normality of progeny was studied. METHOD OF STUDY: Four women enrolled by informed consent in the Phase II trials. The women studied were immunized with the HCG vaccine and did not receive booster injections in consideration of their desire to have another child. They were examined clinically at least once every month until delivery. The babies were followed up from 2 to 3.5 years, and their anthropometric indices were compared with elder siblings. RESULTS: The pregnancies progressed to 35 to 38 weeks with the usual obstetric problems, and the children developed normally. CONCLUSIONS: The anti-fertility effect of the HSD-hCG vaccine is reversible and low titers of antibodies below the protective threshold have no apparent side effects on the progression of pregnancy and on the early development of the progeny.

Adult↗
PubMed1998

Structural and kinetic properties of nonglycosylated recombinant Penicillium amagasakiense glucose oxidase expressed in Escherichia coli.

The gene coding for Penicillium amagasakiense glucose oxidase (GOX; beta-D-glucose; oxygen 1-oxidoreductase [EC 1.1.3.4]) has been cloned by PCR amplification with genomic DNA as template with oligonucleotide probes derived from amino acid sequences of N- and C-terminal peptide fragments of the enzyme. Recombinant Escherichia coli expression plasmids have been constructed from the heat-induced pCYTEXP1 expression vector containing the mature GOX coding sequence. When transformed into E. coli TG2, the plasmid directed the synthesis of 0.25 mg of protein in insoluble inclusion bodies per ml of E. coli culture containing more than 60% inactive GOX. Enzyme activity was reconstituted by treatment with 8 M urea and 30 mM dithiothreitol and subsequent 100-fold dilution to a final protein concentration of 0.05 to 0.1 mg ml-1 in a buffer containing reduced glutathione-oxidized glutathione, flavin adenine dinucleotide, and glycerol. Reactivation followed first-order kinetics and was optimal at 10 degrees C. The reactivated recombinant GOX was purified to homogeneity by mild acidification and anion-exchange chromatography. Up to 12 mg of active GOX could be purified from a 1-liter E. coli culture. Circular dichroism demonstrated similar conformations for recombinant and native P. amagasakiense GOXs. The purified enzyme has a specific activity of 968 U mg-1 and exhibits kinetics of glucose oxidation similar to those of, but lower pH and thermal stabilities than, native GOX from P. amagasakiense. In contrast to the native enzyme, recombinant GOX is nonglycosylated and contains a single isoform of pI 4.5. This is the first reported expression of a fully active, nonglycosylated form of a eukaryotic, glycosylated GOX in E. coli.

Base Sequence↗
PubMed1998

Identification of new cytotoxic T-cell epitopes on the 38-kilodalton lipoglycoprotein of Mycobacterium tuberculosis by using lipopeptides.

Induction of cytotoxic T lymphocytes (CTLs) by vaccination has been shown to protect against bacterial, viral, and tumoral challenge. The aim of this study was to identify CTL epitopes on the 38-kDa lipoglycoprotein from Mycobacterium tuberculosis. The identification of these CTL epitopes was based on synthesizing peptides designed from the 38-kDa lipoglycoprotein, with known major histocompatibility complex class I (MHC-I) binding motifs (H-2Db), and studying their ability to up-regulate and stabilize MHC-I molecules on the mouse lymphoma cell line RMA-S. To improve the capacity of the identified peptides to induce CTL responses in mice, palmitic acid with a cysteine-serine-serine spacer amino acid sequence was attached to the amino terminus of the peptide. Two of five peptides with H-2Db binding motifs and their corresponding lipopeptides up-regulated and stabilized the H-2Db molecules on RMA-S cells. Both lipopeptides, in combination with incomplete Freund's adjuvant, induced CTL responses in C57BL/6 (H-2(b)) mice. Moreover, the lipopeptide induced stronger CTL responses than the peptide. The capacity of the various lipopeptides to induce CTL displayed a good relationship with the ability of the (lipo)peptide to up-regulate and to stabilize H-2Db molecules. The capacity of the peptides and lipopeptides to up-regulate and stabilize MHC-I expression can therefore be used to predict their potential to function as a CTL epitope. The newly identified CTL epitopes and their lipid derivatives provide us with important information for future M. tuberculosis vaccine design.

Animals↗