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Biomedical subjects

S M Singh

Publications and source records attributed to S M Singh.

At least 19 recordsLinked to original sources
PubMed1992

Chaos game representation of coding regions of human globin genes and alcohol dehydrogenase genes of phylogenetically divergent species.

Chaos game representation (CGR) is a novel holistic approach that provides a visual image of a DNA sequence quite different from the traditional linear arrangement of nucleotides. Although it is known that CGR patterns depict base composition and sequentiality, the biological significance of the specific features of each pattern is not understood. To systematically examine these features, we have examined the coding sequences of 7 human globin genes and 29 relatively conserved alcohol dehydrogenase (Adh) genes from phylogenetically divergent species. The CGRs of human globin cDNAs were similar to one another and to the entire human globin gene complex. Interestingly, human globin CGRs were also strikingly similar to human Adh CGRs. Adh CGRs were similar for genes of the same or closely related species but were different for relatively conserved Adh genes from distantly related species. Dinucleotide frequencies may account for the self-similar pattern that is characteristic of vertebrate CGRs and the genome-specific features of CGR patterns. Mutational frequencies of dinucleotides may vary among genome types. The special features of CG dinucleotides of vertebrates represent such an example. The CGR patterns examined thus far suggest that the evolution of a gene and its coding sequence should not be examined in isolation. Consideration should be given to genome-specific differential mutation rates for different dinucleotides or specific oligonucleotides.

Alcohol Dehydrogenase↗
PubMed1992

Pathogenicity of Sporotrichum pruninosum and Cladosporium oxysporum, isolated from the bronchial secretions of a patient, for laboratory mice.

In this study we have demonstrated the occurrence of Sporotrichum pruinosum and Cladosporium oxysporum in the bronchial secretions of a patient with a presumptive diagnosis of tuberculosis. This observation coupled with the ability of both fungi to cause infection and elicit tissue responses in experimentally infected mice supported a probable etiologic relationship with the patient which could not be confirmed in the absence of histologic evidence. In vitro some antimycotics were tested against S. pruinosum and C. oxysporum by the agar dilution method. Oxiconazole with a minimum inhibitory concentration of 0.1 micrograms/ml-1 after 72 h and amorolfine at a concentration of 0.001 micrograms/ml-1 after 72 h were the most active ones against S. pruinosum and C. oxysporum respectively. It is suggested that the isolation of S. pruinosum and C. oxysporum from patients with bronchopulmonary disorders should be viewed with caution. Clinical and laboratory evaluation of such patients should be done critically before arriving at a firm diagnosis.

Animals↗
PubMed1992

Hyalohyphomycosis caused by Paecilomyces variotii: a case report, animal pathogenicity and 'in vitro' sensitivity.

A case of cutaneous infection in a 25-year-old male caused by Paecilomyces variotii is described. Animal pathogenicity studies with normal and cortisone-treated mice revealed the predeliction of P. variotii for skin and liver in both normal and cortisone-treated mice and for lungs and heart only in immunosuppressed mice. 5-fluorocytosine gave the best MIC value for P. variotii in vitro. This report documents for the first time that P. variotii causes cutaneous infection.

Adult↗
PubMed1992

Pancreatic ductal and interstitial pressures in cats with chronic pancreatitis.

We investigated the etiology of interstitial hypertension in chronic pancreatitis by examining the relationship between pancreatic ductal and interstitial pressures in cats. The main pancreatic duct was cannulated in the tail of the gland and perfused at 1, 2, or 5 ml/hr, to simulate pancreatic secretion. Intraductal and interstitial pressures were measured in four groups of animals: (1) normal cats; (2) normal cats after acutely narrowing the main duct to 25% of its original diameter; (3) normal cats after encasing the body and tail in a rigid latex capsule; and (4) cats with chronic pancreatitis created by narrowing the main duct five weeks earlier. Duct perfusion increased intraductal pressure in all of the cats, but significantly more in groups 2, 3, and 4 compared to group 1. Pancreatic interstitial pressure was unchanged by duct perfusion in groups 1 and 2, but increased in groups 3 and 4. We concluded that the compliant tissue of the normal pancreas expanded to effectively dissipate the increase in duct pressure associated with duct perfusion. In chronic pancreatitis, the inelastic parenchyma and capsule limited the distensibility of the gland, which resulted in elevated interstitial pressures during duct perfusion.

Animals↗
PubMed1992

Effect of interferon-gamma priming on the activation of murine peritoneal macrophages to tumouricidal state by cisplatin, IL-1, and tumour necrosis factor (TNF): production of IL-1 and TNF.

The effect of interferon-gamma (IFN-gamma) priming of murine peritoneal macrophages on the activation to tumouricidal state by cisplatin, lipopolysaccharide (LPS)-IL-1 and TNF was investigated. Cisplatin-, LPS-, IL-1- or TNF-treated IFN-gamma-primed macrophages showed significantly enhanced tumouricidal activity and binding to tumour cells, compared with unprimed treated or untreated macrophages. Macrophages treated with cisplatin, LPS, IL-1 and TNF produced released and membrane-associated IL-1 and TNF activity which was significantly enhanced after priming with IFN-gamma. These observations suggest the use of IFN-gamma along with these biological response modifiers in designing immunotherapeutic protocols for treatment of malignancy.

Animals↗
PubMed1992

Clinical studies regarding the plaque removal efficacy of manual toothbrushes.

Two independent cross-over design studies were performed to compare two toothbrushes for their ability to remove plaque. In Study I, the Colgate Precision toothbrush was compared to the Oral-B 40 toothbrush; in Study II, the Colgate Precision toothbrush was compared to the Reach Full-Head soft toothbrush. A total of 54 and 72 adult male and female subjects who met the inclusion/exclusion criteria completed Study I and Study II, respectively. In each study, subjects refrained from brushing for 24 hours, and were screened for dental plaque on the facial and lingual surfaces of all natural teeth, using the Rustogi, et al. index. Based on mean scores and number of teeth, qualifying subjects were randomly assigned to one of two groups. Subjects were then scheduled to return one week later, having again abstained from all oral hygiene procedures for a 24-hour period. At this visit, each subject was evaluated for plaque, then brushed with his/her assigned toothbrush for sixty seconds, and was again scored for plaque after brushing. Subjects were instructed to resume their normal routine and return to the clinical site one week later. At this visit, a different test toothbrush was assigned to each group in a cross-over design. Plaque evaluations and toothbrushing procedures were again performed. In both studies, the Colgate Precision toothbrush was significantly more effective (p < 0.01) than either the Oral-B 40 toothbrush or the Reach Full-Head soft toothbrush in reducing whole mouth plaque scores, plaque scores at the gumline, and plaque scores at interproximal areas.

Adult↗
PubMed1992

HLA-D-region genomic DNA restriction fragments in DRw15 (DR2) familial narcolepsy.

Restriction fragment length polymorphism (RFLP) associated with the three human lenkocyte antigen (HLA)-D-region gene-specific cDNA probes (gene-specific DQ alpha, DQ beta and DP beta) was evaluated in two Caucasian families from southwestern Ontario, each with two confirmed narcoleptic siblings. The special feature of the two families is that the affected members are not necessarily DRw15 (previously DR2) positive. In family 1, of the two affected sibs one is DRw15 positive, whereas in family 2 all members including the two affected sibs are DRw15 negative. There is no association between narcolepsy and HLA haplotype in the two families. Further, the polymorphic DNA band patterns generated by a number of restriction enzymes do not show a relationship with the presence or absence of narcolepsy. The probe-specific DNA and patterns however do follow the HLA haplotypes associated with the DQ and DR loci. These results suggest that in DRw15-negative narcolepsy, the DNA patterns are not informative with respect to diagnosing or predicting the presence of narcolepsy. Further, such results argue for genetic heterogeneity in narcolepsy, and the role of DRw15 in the development of the disease could at best be viewed as contributory and not essential.

DNA↗
PubMed1992

Clinical efficacy of a triclosan/copolymer pre-brush rinse.

A five-day, double-blind parallel clinical study was conducted to determine the effect on plaque removal of a pre-brush rinse containing 0.03 triclosan (Irgacare MP, Ciba-Geigy Corp.) and 0.125% of a copolymer of methoxyethylene and maleic acid (Gantrez, GAF Corp.), as compared to a matching placebo pre-brush rinse. One hundred eleven subjects were stratified into two balanced groups according to baseline Quigley-Hein Plaque Index scores. Each group was randomly assigned to use either the triclosan/copolymer pre-brush rinse or the matching placebo pre-brush rinse. In order to determine plaque removal efficacy of the pre-brush rinses, subjects rinsed their mouths twice daily (mornings and evenings) for one minute with 15 ml of their assigned pre-brush rinse. Immediately after rinsing, subjects brushed their teeth for 30 seconds with a commercially available dentifrice containing 0.76% sodium monofluorophosphate and a soft-bristled toothbrush. The morning rinsing/brushing procedure was done under supervision at the clinical facility. The evening rinsing/brushing procedure was done at home. After five days' use of their assigned pre-brush rinse and toothbrushing, subjects were evaluated by the dental examiner for residual plaque using the modified Quigley-Hein Plaque Index scoring procedure. When mean five-day Quigley-Hein Plaque Index scores were compared for both groups, the triclosan/copolymer pre-brush rinse removed 22.54% more plaque from all surfaces of the teeth than the matching placebo pre-brush rinse. When mean Quigley-Hein Plaque Index decrements (the difference between baseline and five-day Quigley-Hein Plaque Index scores) were compared for both groups, the triclosan/copolymer pre-brush rinse removed more than twice as much plaque from all surfaces of the teeth than the matching placebo pre-brush rinse (33.99% efficacy versus 15.19% efficacy). When mean five-day Plaque Severity Index scores were compared for both groups, the triclosan/copolymer pre-brush rinse removed 46.15% more plaque from the "more difficult to brush" surfaces of the teeth than the matching placebo pre-brush rinse. rinse.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of cisplatin treatment of human monocyte cell line U937 on the induction of tumoricidal activity.

U937, a human monocyte-like, cell line was checked for cytotoxic activity against tumor target cells. Untreated U937 cells showed little cytotoxicity against tumor cells. Granulocyte-macrophage colony stimulating factor (GM-CSF) and LPS significantly activated the U937 cells to tumoricidal state. Treatment of U937 cells with cisplatin did not enhance the tumoricidal activity. Similarly, interferon gamma (IFN-Y) and macrophage colony stimulating factor (M-CSF) could also not activate either the tumoricidal activity of U937 cells. Pretreatment of U937 cells with GM-CSF for 24 h and then the treatment with cisplatin significantly augmented the tumoricidal activity as compared to that of GM-CSF alone.

Cisplatin↗
PubMed1992

Effect of allogenic Dalton's lymphoma cells on the activation of murine peritoneal macrophages to tumoricidal state by cisplatin and lipopolysaccharide (LPS).

Murine peritoneal macrophages on treatment with cisplatin or LPS for 24 h showed enhanced tumoricidal activity. Co-incubation of macrophages with fresh allogeneic Dalton's lymphoma (DL) cells significantly inhibited the activation of macrophages to tumoricidal state by cisplatin or LPS. Incubation of macrophages with DL cell culture supernatants or paraformaldehyde (PFA) fixed DL cells also significantly down-regulated the activation of macrophages with cisplatin or LPS. On the other hand, preexposure of macrophages to DL cells for 24 h before activation with cisplatin and LPS enhanced the tumoricidal activity of murine peritoneal macrophages. These results may contribute to understanding the effect of tumor cells on macrophages.

Animals↗
PubMed1991

A method for transforming lymphocytes from very small blood volumes suitable for paediatric samples.

Permanent lymphoblastoid cell lines are important in the molecular analysis and characterization of human genetic disorders, when immortalized cells must be banked for future diagnostic or research purposes. However, routine methods for transformation using Epstein-Barr virus (EBV) require blood volumes that may be difficult to collect from clinically compromised neonates and small children. Here we report a modified transformation procedure utilizing blood samples of small volume (less than 1.0 ml), which we have found to be particularly useful for the immortalization of lymphocytes destined for future molecular genetic studies.

Adolescent↗
PubMed1991

Onychomycosis caused by Scopulariopsis brumptii. A case report and sensitivity studies.

Scopulariopsis brumptii was isolated from nail lesions in left hand of a 42 year-old-farmer. The direct microscopic examination of the nail samples revealed light brown, septate, branched fungal hyphae along with thick-walled spherical cells. The histopathological examination showed involvement of internal phase of the nail plate. Amongst the antimycotics tested against S. brumptii 'In vitro' oxiconazole was found to be the most active with MIC value of 10 micrograms/ml-1. This report documents the first instance of onychomycosis caused by S. brumptii.

Adult↗
PubMed1991

Onychomycosis caused by Chaetomium globosum Kunze.

In this paper we report a case of onychomycosis caused by Chaetomium globosum. The patient had lesions of the fingernails of the left hand. The direct microscopical examination of the nails showed light-brown hyphae with thick-walled cells. The histopathological examination revealed thick aggregated hyphal element in the nail plate. Amongst the antimycotics tested oxiconazole with MIC values of 0.3 microgram/ml-1 was found to be most effective in vitro against Chaetomium globosum.

Adult↗
PubMed1991

A quantitative genetic analysis of tissue-specific catalase activity in Mus musculus.

Tissue-specific catalase activity in 3-week-old animals from inbred mouse strains 129/ReJ, BALB/c, C3H/HeAnl/Cas-1b, C3H/HeSnJ, C3H/S, C57BL/6J, and Swiss-Webster was found to be highly variable by analysis of variance (P = 0.01). Appropriate crosses were made among strains which were classified as normal (BALB/c, C3H/HeSnJ, C3H/S), hypocatalasemic (129/ReJ, C57BL/6J), and acatalasemic (C3H/HeAnl/Cas-1b) with respect to blood catalase activity to study the inheritance of the blood, kidney, liver, and lung catalase activity levels in a number of generations (reciprocal F1's, F2, two backcrosses--BC1 and BC2--and some RI lines). Segregation analysis and statistical methods which tested different models of inheritance as well as calculations of heritability were used in an effort to assess and evaluate genetic parameters that affect catalase activity. Results indicate that the inheritance of blood catalase activity in the cross involving acatalasemic and normal (BALB/c, C3H/HeSnJ) strains is compatible with the single-locus difference between the parental strains; however, the difference between the acatalasemic and the hypocatalasemic strain (C57BL/6J) would require additional genetic interaction for a satisfactory explanation. A similar pattern of generalization also applies to the inheritance of kidney catalase activity. The segregation pattern for the liver and lung catalase activity in most crosses is significantly different from the expectations of the single locus model. These results are compatible with the concept that a number of genes must affect tissue-specific catalase activity in mice. These may include previously described (e.g., Ce-1 and Ce-2) or novel genetic regulators/modifiers which interact with a single structural gene (Cas-1) or its product to produce the catalase phenotype characteristic of specific tissues in each strain.

Acatalasia↗
PubMed1991

A study of the time course of conversion of edematous to hemorrhagic pancreatitis.

We studied the conversion of acute edematous pancreatitis (AEP) to acute hemorrhagic pancreatitis (AHP) in an experimental model in cats. In the model, 16,16 dimethyl PgE2 effects this conversion by increasing microvascular permeability. First, we induced AEP in cats and then gave PgE2 at increasing intervals after the induction of AEP to see how long an interval would still allow conversion. In 6 groups of cats, PgE2 was administered for 2 h, starting at 2, 4, 6, 8, 10, or 12 h after the creation of AEP. Twelve h later, the cats were sacrificed and the pancreases were graded for inflammation and hemorrhage. Significant pancreatic hemorrhage did not occur when the PgE2 was administered at 12 h compared to 2 h. Next, we determined that PgE2 still retained its ability to increase pancreatic vascular permeability when administered 12 h after the creation of AEP. This was done by perfusing a marker molecule through the MPD (fluorescein isothiocyanate labeled dextran: FITC-D, mol wt 20,000) and then finding it in portal venous blood (PVB). The presence of FITC-D in PVB signified increased vascular permeability, since normally none was present. We concluded that conversion of AEP to AHP was possible during the first 12 h after induction of AEP. Lack of conversion at 12 h was not caused by a lack of vascular reactivity at that time.

16,16-Dimethylprostaglandin E2↗
PubMed1991

Up-regulation of induction of lymphokine (IL-2)-activated killer (LAK) cell activity by FK-565 and cisplatin.

The role of cisplatin and FK-565 in up-regulation of lymphokine-activated killer (LAK) cell induction by IL-2 was examined. Treatment of blood mononuclear cells (MNC) of healthy donors with cisplatin or FK-565 in the presence of IL-2 resulted in a significant increase in LAK activity against natural killer (NK)-resistant Daudi cells as assessed by the 4 h 51Cr release assay. Blood MNC treated with cisplatin alone was not cytotoxic to Daudi cells. However, MNC treated with FK-565 showed some cytotoxicity against Daudi cells. Addition of cisplatin to IL-2-stimulated MNC did not increase proliferation but did enhance cytotoxicity. FK-565 together with IL-2 increased both proliferation and cytotoxicity of blood MNC. These data suggest the potential of cisplatin and FK-565 in LAK adoptive immunotherapy for cancer treatment.

Antibiotics, Antineoplastic↗