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Biomedical subjects

F Siddiqui

Publications and source records attributed to F Siddiqui.

25 records · Page 2Linked to original sources
PubMed1993

N-methyl-D-aspartate receptor excitotoxicity involves activation of polyamine synthesis: protection by alpha-difluoromethylornithine.

We investigated the role of polyamines and their regulatory enzyme ornithine decarboxylase in N-methyl-D-aspartate-induced excitotoxicity in embryonic chick retina. N-Methyl-D-aspartate (200 microM) produced an early increase in ornithine decarboxylase activity, putrescine concentration, and Ca2+ entry, leading to selective neuronal death by 30 min. This response was attenuated by the ornithine decarboxylase inhibitor alpha-difluoromethylornithine and the N-methyl-D-aspartate receptor antagonist 5-aminophosphonovaleric acid. Exogenous putrescine increased intracellular putrescine and spermine levels and reversed neuroprotection by alpha-difluoromethylornithine, but not by 5-aminophosphonovaleric acid. N-Methyl-D-aspartate-receptor stimulation of putrescine/polyamine synthesis mediates abnormal Ca2+ entry and acute excitotoxic neuronal death. Postreceptor inhibition of the ornithine decarboxylase/polyamine cascade by alpha-difluoromethylornithine may provide neuroprotection against N-methyl-D-aspartate-induced excitotoxicity.

Animals↗
PubMed1992

Localization of inhaled trimellitic anhydride to lung with a respiratory lymph node antibody secreting cell response.

Male Sprague-Dawley rats were exposed to trimellitic anhydride (TMA) by inhalation (500 micrograms/m3), 4 hours a day, for 1 to 10 days. TMA was localized to lung cells by immunoelectron microscopy. Enzyme-linked immunosorbent assay (ELISA) and Western blot analysis were used in an attempt to localize TMA to lung lavage proteins. The lung-associated lymph node (LALN) B-lymphocyte response was measured by quantitation of immunoglobulin (Ig)G, IgA, and IgM antibody secreting cells specific for TMA rat serum albumin (TM-RSA) by use of the enzyme-linked immunospot assay (ELISPOT) method. The IgG, IgM, and IgA antibody response to TM-RSA in serum and lavage fluid was quantitated by ELISA. Lung injury was assessed by the number of external lung hemorrhagic foci and lung weight. Immunoelectron microscopy localized TMA to alveolar and bronchial cells on all exposure days. ELISA detected trace amounts of TMA haptenized lavage proteins that could not be detected by Western blot analysis. A marked increase occurred in lung injury from day 7 to 10. The LALN IgG, IgA, and IgM antibody secreting cell response to TM-RSA paralleled measures of lung injury. IgG, IgM, and IgA serum and lavage antibody to TM-RSA were correlated with lung injury measures. Lavage and serum IgG antibody levels had the highest correlation with lung injury.

Administration, Inhalation↗
PubMed1991

On-site screening for urinary Hg concentrations and correlation with glomerular and renal tubular function.

At the American Dental Association 1985 and 1986 Annual Sessions, an on-site screening for mercury was conducted as part of the Health Screening Program (HSP) to identify dentists having elevated urinary mercury concentrations. The data generated from this study were used to examine the relationship between elevated urinary mercury exposure and kidney dysfunction. Kidney dysfunction was assessed by measurement of serum and urine beta 2 microglobulin concentrations, serum creatinine, and creatinine clearance. The mean values found for urinary mercury were 5.8 micrograms Hg/L and 7.6 micrograms Hg/L for 1985 and 1986, respectively. Urinary mercury concentrations for this population were found to fall within the range of not detected to 115 micrograms Hg/L. Of the total number of participants assayed in 1985 and 1986, roughly 10 percent of the sample exhibited elevated mercury concentrations above 20 micrograms Hg/L. An analysis of the clinical markers indicated no clear relationship between elevated urinary mercury concentrations and kidney dysfunction. In addition to mercury testing, all dentists who participated in the 1985 and 1986 HSP were issued a questionnaire soliciting information as to their professional exposure. Those participants who were identified as having elevated urinary mercury concentrations in the 1985 HSP were issued a followup questionnaire that addressed psychological and neuropsychological symptoms. From these questionnaires three significant relationships were found. These relationships were associated with mercury/amalgam handling and skin contact, the number of amalgams placed by the dentist, and the number of hours of practice per week. The reported absence of a clear relationship between urinary mercury concentrations and potential kidney dysfunction is in agreement with other findings at the mercury concentrations tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1981

Rationale and application of beta-2-microglobulin measurements to detect acute transplant rejection.

Serum and urinary concentrations of beta 2-microglobulin were measured for the first 21 days after renal transplantation to aid in diagnosis of acute rejection. Criteria developed after study of 15 patients were applied to the entire group of 31 consecutive cases. 29 instances meeting our criteria were identified in 651 days at risk and were associated with a mean maximal increase of serum creatinine of 74.8%. beta 2-Microglobulin methods may make possible detection of what is now subclinical rejection. beta 2-Microglobulin methods, however, are an adjunct to, not a replacement for classical methods for detecting acute rejection.

Beta-Globulins↗
PubMedDate not supplied

Studies on the inhibitory effects of zinc heptanoate on microorganisms.

Inhibitory effect of zinc heptanoate was observed on different cultures of bacteria and fungi. Growth of all the bacteria was inhibited by the compound. Greatest inhibition was seen in the case of Staphylococcus albus, Streptococcus pyogenes, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, Salmonella typhi, S. paratyphi A, S. paratyphi B, Vibrio cholerae, Corynebacterium diphtheriae, and E. coli whereas least inhibition was found in the case of Staphylococcus aureus. In triethanolamine: water (1:1) solution minimum inhibitory concentration (MIC) was least for Klebsiella pneumoniae (800 p.p.m.) while in the case of Staph. aureus and Bacillus subtilis it was 200 p.p.m. Among yeasts and fungi greatest inhibition was found with Trichophyton schoenleini, T. rubrum, T. gourvili, Microsporum adouini, M. vanbreuseghemi and least in the case of Candida albicans. In triethanolamine: water (1:1) solution the MIC for T. schoenleini and T. gourvili and T. violaceum was as low as 900 p.p.m. whereas in the case of Aspergillus oryzae it was highest--3500 p.p.m. The effect of the compound on glucose consumption of Aspergillus niger and Bacillus subtilis was also seen.

Bacteria↗