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Biomedical subjects

A A Qureshi

Publications and source records attributed to A A Qureshi.

At least 19 recordsLinked to original sources
PubMed1997

Isoprenoids suppress the growth of murine B16 melanomas in vitro and in vivo.

Sundry mevalonate-derived constituents (isoprenoids) of fruits, vegetables and cereal grains suppress the growth of tumors. This study estimated the concentrations of structurally diverse isoprenoids required to inhibit the increase in a population of murine B16(F10) melanoma cells during a 48-h incubation by 50% (IC50 value). The IC50 values for d-limonene and perillyl alcohol, the monoterpenes in Phase I trials, were 450 and 250 micromol/L, respectively; related cyclic monoterpenes (perillaldehyde, carvacrol and thymol), an acyclic monoterpene (geraniol) and the end ring analog of beta-carotene (beta-ionone) had IC50 values in the range of 120-150 micromol/L. The IC50 value estimated for farnesol, the side-chain analog of the tocotrienols (50 micromol/L) fell midway between that of alpha-tocotrienol (110 micromol/L) and those estimated for gamma- (20 micromol/L) and delta- (10 micromol/L) tocotrienol. A novel tocotrienol lacking methyl groups on the tocol ring proved to be extremely potent (IC50, 0.9 micromol/L). In the first of two diet studies, experimental diets were fed to weanling C57BL female mice for 10 d prior to and 28 d following the implantation of the aggressively growing and highly metastatic B16(F10) melanoma. The isomolar (116 micromol/kg diet) and the Vitamin E-equivalent (928 micromol/kg diet) substitution of d-gamma-tocotrienol for dl-alpha-tocopherol in the AIN-76A diet produced 36 and 50% retardations, respectively, in tumor growth (P < 0.05). In the second study, melanomas were established before mice were fed experimental diets formulated with 2 mmol/kg d-gamma-tocotrienol, beta-ionone individually and in combination. Each treatment increased (P < 0.03) the duration of host survival. Our finding that the effects of individual isoprenoids were additive suggests the possibility that one component of the anticarcinogenic action of plant-based diets is the tumor growth-suppressive action of the diverse isoprenoid constituents of fruits, vegetables and cereal grains.

Animals↗
PubMed1997

Relative performance of different types of passive dosimeters employing solid state nuclear track detectors.

Radon and its progeny, known to be carcinogenic, are a matter of great concern in underground mines and energy conserved air-tight houses. Different shapes of dosimeters using solid state nuclear track detectors (SSNTDs) have been devised to measure radon concentrations in mines and dwellings. Sometimes intercomparison of results is required by various laboratories working with solid state nuclear track detector-based passive dosimeters. The present work includes the determination of various parameters for a set of dosimeters consisting of (1) box-type, (2) pen-type, (3) tube-type, (4) Karlsruhe Diffusion Chamber, and (5) bare-type dosimeters. In this research two types of plastics, allyl-diglycol-carbonate (C12H18O7) and cellulose nitrate (C6H8O8N2) known as CR-39 and CN-85, respectively, have been employed. The detection efficiency for alpha particles from radon and its progeny for CR-39 and CN-85 have been compared. All experiments have been carried out in a custom-designed exposure chamber connected to a radon source. The calibration factors, in terms of Bq m(-3) per unit track density (1.0 cm(-2)) with respect to box-type dosimeter, have been determined for intercomparison and standardization of measured radon concentrations by a set of passive radon dosimeters used in various laboratories of the world.

Collodion↗
PubMed1996

Dynamic and steady state response of heart rate to orthostatic stress in normotensive and hypertensive pregnant women.

We determined the dynamic and steady state responses of heart rate (HR) to orthostatic stress (standing up) in normotensive and hypertensive pregnant women. Using a continuous recording with servo-photosphygmography, HR response to change in posture from left lateral recumbent position to standing was analysed. The subjects were divided into five groups comprising: Groups I, II and III: normotensive pregnant women in each of the three trimesters of pregnancy (total n = 77); Group IV: women with gestational proteinuric hypertension (GPH) in the third trimester (n = 16); Group V: age-matched non-pregnant normotensive controls (n = 15). The HR reacted with a typical overshoot response to this orthostatic change with HR rising to a peak and then settling to a new but higher steady state. Change in steady state HR from lying to standing (delta HR), rate of rise of HR in response to standing (i.e. the acceleration slope (HRon)), and rate of fall of HR after reaching the peak (i.e. deceleration slope (HRoff)) were evaluated from standing heart rate time curves. HRon in response to standing showed a downward trend with gestation (ANOVA, P < 0.05) in normotensive gravida. The deceleration slope (HRoff) showed a distinct gestational age-related decrease from first to third trimester in normotensive women (ANOVA, P < 0.01). The most striking observation was that the slope of HRoff for the GPH group was significantly steeper than that of normotensive women of comparable gestational age (unpaired t-test P < 0.01) and approximated to that of the non-pregnant group. The difference in HR response between normotensive women and those with GPH in the third trimester suggests it may have potential as a new marker for pre-eclampsia.

Adult↗
PubMed1996

Dietary alpha-tocopherol attenuates the impact of gamma-tocotrienol on hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in chickens.

The concentration-dependent impact of gamma-tocotrienol on serum cholesterol can be traced to the posttranscriptional down-regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. gamma-Tocotrienol also suppresses tumor growth. Palmvitee, the tocopherol and tocotrienol-rich fraction of palm oil, is the sole commercial source of gamma-tocotrienol. Contrary to the universal findings of the efficacy of gamma-tocotrienol there are conflicting reports of the impact of Palmvitee on 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, serum cholesterol concentrations and tumor development. These conflicting reports led us to examine the impact of alpha-tocopherol on the cholesterol-suppressive action of gamma-tocotrienol. Control and experimental diets were fed to groups of White Leghorn chickens (n = 10) for 26 d. The control diet was supplemented with 21 nmol alpha-tocopherol/g. All experimental diets provided 141 nmol of blended tocols/g diet. The alpha-tocopherol and gamma-tocotrienol concentrations of the experimental diets ranged from 21 to 141 and 0 to 120 nmol/g, respectively. We now report that including alpha-tocopherol in tocol blends containing adequate gamma-tocotrienol to suppress 3-hydroxy-3-methylglutaryl coenzyme A reductase activity results in an attenuation of the tocotrienol action (P < 0.001). A summary of results from studies utilizing different Palmvitee preparations shows that effective preparations consist of 15-20% alpha-tocopherol and approximately 60% gamma- (and delta-) tocotrienol, whereas less effective preparations consist of > or = 30% alpha-tocopherol and 45% gamma- (and delta-) tocotrienol.

Animals↗
PubMed1996

Amaranth and its oil inhibit cholesterol biosynthesis in 6-week-old female chickens.

All amaranth varieties contain tocotrienols and squalene compounds which are known to affect cholesterol biosynthesis. Therefore, in the present study, the influence of dietary supplementation of whole seed, popped, and milled amaranth and amaranth oil on cholesterogenesis was studied in 6-wk-old female chickens. Serum total cholesterol and LDL-cholesterol were lowered 10-30% and 7-70% (P < 0.01), respectively, in birds fed amaranth-containing diets. HDL-cholesterol was not affected by amaranth supplementation. Activities of liver cholesterol 7alpha-hydroxylase (the enzyme responsible for cholesterol breakdown into bile acids) were 10-18% higher (P < 0.01) than those of controls for birds fed most forms of amaranth and its oil, whereas activities of liver 3-hydroxy-3-methylglutaryl coenzyme A reductase (the rate-limiting enzyme for cholesterol biosynthesis) were lowered by about only 9% (P < 0.01) by popped, milled amaranth and its oil. This lack of marked inhibition of this enzyme suggests the presence of some other potent cholesterol inhibitor(s) apart from tocotrienols and squalene in amaranth.

Amaranthus↗
PubMed1996

Langerhans cells express inducible nitric oxide synthase and produce nitric oxide.

The importance of nitric oxide (NO) in mediating macrophage functions has been demonstrated, but production of this potent gas has not been examined in Langerhans cells (LC). Using murine LC purified from epidermal cell suspensions and the recently established LC-like cell line derived from newborn BALB/c epidermis (XS-52), it was shown with reverse transcriptase (RT)-PCR that inducible nitric oxide synthase (iNOS) message is present in these cells. Murine keratinocytes did not contain iNOS message. iNOS mRNA was increased in a concentration-dependent manner by lipopolysaccharide (LPS) in purified murine LC and XS-52 cells, and immunofluorescence using an antibody to iNOS revealed bright cytoplasmic staining in LPS-treated XS-52 cells. Anti-iNOS antibody brightly stained LC on human neonatal foreskin cryosections. An increase in NO production by LPS-treated XS-52 cells over 16 h, as measured by the determination of nitrite levels in culture supernatants using the Griess Reaction, was observed. Interferon-gamma (IFNgamma) did not affect NO production on its own. In the presence of LPS and IFNgamma, NO production was 3 times more than observed with LPS alone. NO production was inhibited by the NOS inhibitor L-NAME. Western blots with anti-iNOS antibody demonstrated an increase in iNOS expression in LPS-treated XS-52 cells that was suppressed by IL-10. NO produced in LC may affect LC functions such as microbicidal activity, antigen presentation, and cytotoxicity and may affect adjacent keratinocytes and melanocytes.

Animals↗
PubMed1996

Immunomodulatory properties of maxadilan, the vasodilator peptide from sand fly salivary gland extracts.

Sand flies are the arthropod vector of leishmaniasis and salivary gland extracts from these flies exacerbate leishmaniasis in vivo. The mechanism of exacerbation appears to be due to immunomodulatory effects of the saliva on host immune function but the active component is unknown. The following studies reveal that maxadilan, the vasodilatory peptide present in sand fly salivary gland extracts, has immunomodulatory properties. To examine the effect of maxadilan on T cell proliferation, the peptide was added to murine spleen cells stimulated with either concanavalin A or plate-bound anti-T cell receptor antibody. Inhibition of proliferation was noted in a dose-dependent manner for both sets of experiments (P < 0.05). To examine the effect of maxadilan on alloantigen presentation, the peptide was added to mixed lymphocyte and mixed epidermal cell lymphocyte reactions. Inhibition of proliferation was found in these culture systems. Maxadilan also inhibited the delayed-type hypersensitivity reaction in mice (P < 0.05). These observations suggest a role for maxadilan in the pathogenesis of leishmaniasis since the peptide may inhibit the immune response at the site of parasite inoculation, allowing the infection to proceed.

Adjuvants, Immunologic↗
PubMed1996

From bedside to the bench and back. Nitric oxide and the cutis.

When the discoverer of dynamite (trinitrotoluene [TNT]), Alfred Nobel, was prescribed nitroglycerin for angina in 1895, he was certainly taken aback. Almost a century later, organic nitrates and their gaseous metabolic end product, nitric oxide (NO), were implicated in a vast array of biologically diverse activities. About 10 years ago, a series of discoveries from different avenues of research converged on NO, thrusting it into the limelight as a neurotransmitter, vasodilator, toxin, and modulator of immune function and inflammation. Nitric oxide has thus managed to capture the interest of scientists from a number of fields and holds center stage attention. Interest in NO among dermatologists has been slow to appear, however, and the literature on NO with respect to the skin is sparse when compared with the steep escalation in the number of articles published generally on NO since 1987 (Figure 1).

Blood Vessels↗
PubMed1995

Response of hypercholesterolemic subjects to administration of tocotrienols.

The cholesterol-suppressive actions of Palmvitee and gamma-tocotrienol were assessed in hypercholesterolemic subjects after acclimation to the American Heart Association Step 1 dietary regimen for four and eight weeks, respectively. The four-week dietary regimen alone elicited a 5% decrease (P < 0.05) in the cholesterol level of the 36 subjects. Subjects continuing on the dietary regimen for a second four-week period experienced an additional 2% decrease in their cholesterol levels. Dietary assessments based on unanticipated recalls of 24-h food intake records suggest that significant reductions in energy and fat, predominantly in saturated fat, intakes are responsible. The subjects experienced significant Palmvitee- and gamma-tocotrienol-mediated decreases in cholesterol. The group of subjects acclimated to the dietary regimen for four weeks responded to Palmvitee (a blend of tocols providing 40 mg alpha-tocopherol, 48 mg alpha-tocotrienol, 112 mg gamma-tocotrienol, and 60 mg delta-to-cotrienol/day for four weeks) with a 10% decrease in cholesterol (P < 0.05). Dietary assessments showed no further change in energy and fat intakes. alpha-Tocopherol attenuated the cholesterol-suppressive action of the tocotrienols. The second group of subjects, acclimated to the dietary regimen for eight weeks, received 200 mg gamma-tocotrienol/d for four weeks. The cholesterol-suppressive potency of this alpha-tocopherol-free preparation was calculated to be equivalent to that of the mixture of tocotrienols (220 mg) used in the prior study. Cholesterol levels of the 16 subjects in the second group decreased 13% (P < 0.05) during the four-week trial. Plasma apolipoprotein B and ex vivo generation of thromboxane B2 were similarly responsive to the tocotrienol preparations, whereas neither preparation had an impact on high density lipoprotein cholesterol and apolipoprotein A-1 levels.

Adult↗
PubMed1994

Inhibitors of cholesterol biosynthesis. 2. Hypocholesterolemic and antioxidant activities of benzopyran and tetrahydronaphthalene analogues of the tocotrienols.

Tocotrienols exhibit antioxidant and cholesterol-biosynthesis-inhibitory activities and may be of value as antiatherosclerotic agents. The mechanism of their hypolipidemic action involves posttranscriptional suppression of HMG-CoA reductase (HMGR) in a manner mimicking the action of putative non-sterol feedback inhibitors. The in vitro cholesterol-biosynthesis-inhibitory and HMGR-suppressive activities in HepG2 cells of an expanded series of benzopyran and tetrahydronaphthalene isosteres and the hypocholesterolemic activity of selected compounds assessed in orally dosed chickens are presented. Preliminary antioxidant data of these compounds have been obtained using cyclic voltammetry and Cu-induced LDL oxidation assays. The farnesyl side chain and the methyl/hydroxy substitution pattern of gamma-tocotrienol deliver a high level of HMGR suppression, unsurpassed by synthetic analogues of the present study. In orally dosed chickens, 8-bromotocotrienol (4o), 2-desmethyltocotrienol (4t), and the tetrahydronaphthalene derivative 35 exhibit a greater degree of LDL cholesterol lowering than the natural tocotrienols.

Animals↗
PubMed1994

Cloning and expression of mutations demonstrating intragenic complementation in mut0 methylmalonic aciduria.

The mut0 mutation resulting in methylmalonyl CoA mutase (MCM) apoenzyme deficiency and methylmalonic aciduria is characterized by undetectable enzyme activity in cell extracts and low incorporation of propionate into cultured cells which is not stimulated by hydroxycobalamin. A mut0 fibroblast cell line (WG1681) from an African-American male infant complemented another mut0 cell line (WG 1130). Cloning and sequencing of cDNA from WG 1681 demonstrated compound heterozygosity for two novel changes at highly conserved sites: G623R and G703R. In addition, two previously described homozygous polymorphisms, H532R and V671I, were found. Hybridization of allele-specific oligonucleotides to PCR amplified MCM exons from the proband and family members identified a clinically normal mother, half-sister, and half-brother as carriers of the G703R change in cis with both polymorphisms. Transfection of each change into a mut0 cell line with very low MCM mRNA (GM1673) demonstrated a lack of stimulation of propionate uptake in the absence and presence of hydroxycobalamin. Cotransfection of each mutation with the previously identified R93H mutation of WG 1130 stimulated propionate uptake, indicating that G623R and G703R are independently capable of complementing the R93H mutation.

Base Sequence↗
PubMed1994

Peculiar histopathological features of giardiasis in distal duodenal biopsies.

Histological changes in 20 Giardia positive duodenal biopsies (Group A) were compared with 50, Giardia negative duodenal biopsies (Group B), taken during the same period. Stool examinations in Group B were negative for Giardia. Surface epithelium, villous and crypt architecture and cellular infiltrates were examined and compared between the groups. Atrophic changes in the villi were more common in Group A as compared to B(P < 0.0001). Intraepithelial neutrophil infiltration (P < 0.001), infiltration of the lamina propria with plasma cells (P < 0.5), and presence of eosinophils in the lamina propria (P < 0.001) were significant findings in group A. Some of the changes were related to the density of Giardia colonization e.g., the goblet cell depletion (P < 0.05) and the density of plasma cell infiltration in lamina propria (P < 0.01). Erosions and ulcerations were less commonly seen in group A. Thus we conclude that giardiasis manifests its peculiar features in the distal duodenal mucosa and a biopsy of this region is an important diagnostic tool for detection of this disease.

Adult↗
PubMed1994

"Benign" metastasizing pleomorphic adenoma. A case report and review of literature.

A case of a 34-year-old man with a pathologic fracture through a lytic lesion in the left glenoid is presented. The results of a needle biopsy of the lesion showed a benign pleomorphic adenoma. Sixteen years previously, the patient had a pleomorphic adenoma of the parotid gland. Histology of the initial tissue and the needle biopsy specimen were identical. The patient developed metastasis without any local recurrence of the initial tumor. When evaluating a patient with a lytic lesion of bone with a history of a benign pleomorphic adenoma of the salivary gland, a metastasis should be considered.

Adenoma, Pleomorphic↗
PubMed1993

The lesson.

Explore the source record for details and available documents.

Adolescent↗
PubMed1992

Hypocholesterolemic activity of synthetic and natural tocotrienols.

Tocotrienols are farnesylated benzopyran natural products that exhibit hypocholesterolemic activity in vitro and in vivo. The mechanism of their hypolipidemic action involves posttranscriptional suppression of HMG-CoA reductase by a process distinct from other known inhibitors of cholesterol biosynthesis. An efficient synthetic route to tocotrienols and their isolation from palm oil distillate using an improved procedure is presented. gamma-Tocotrienol exhibits a 30-fold greater activity toward cholesterol biosynthesis inhibition compared to alpha-tocotrienol in HepG2 cells in vitro. The synthetic (racemic) and natural (chiral) tocotrienols exhibit nearly identical cholesterol biosynthesis inhibition and HMG-CoA reductase suppression properties as demonstrated in vitro and in vivo.

Animals↗