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Biomedical subjects

R Ahmad

Publications and source records attributed to R Ahmad.

At least 37 records · Page 2Linked to original sources
PubMed2002

Microfloral contamination and hydrolytic enzyme differences between monsooned and non-monsooned coffees.

AIMS: To analyse and compare, for the first time, fungal and bacterial populations and hydrolytic enzyme production in four monsooned and non-monsooned Arabica and Robusta coffee types. METHODS AND RESULTS: Overall, using serial dilution, the populations of bacteria (approximately 10(8) cfu g(-1)) were highest in monsooned coffees of both varieties. Fungal populations were lower (10(5) cfu g(-1)) and found predominantly on monsooned coffee beans. The major fungal species were Aspergillus terreus, A. restrictus and A. ochraceus. Of 19 semi-quantitative enzymes analysed, significantly higher concentrations of 2-naphthyl-butyrate, caprylate and 2-naphthyl-D-galactopyranosidase were present in Arabica monsooned coffee. CONCLUSIONS: The results suggest that speciality monsooned coffee has markedly different microbial and physiological characteristics from normally produced green coffees. SIGNIFICANCE AND IMPACT OF THE STUDY: Monsooned coffee may have a higher contamination with spoilage moulds, especially mycotoxigenic species.

Bacteria↗
PubMed2002

Audit of primary care angina management in Sandwell, England.

This audit aimed to assess the identification and treatment of coronary risk factors, lifestyle advice given and use of drug therapy, among patients with angina in Sandwell. It was designed to help general practices evaluate their angina management, and highlight areas where practice could be improved. Criteria were based on Sandwell's published angina audit and local clinical guidelines. Each participating practice was asked to identify all patients with angina, from which a 10% sample was randomly selected. The notes of each selected patient were examined for evidence showing whether agreed standards of care had been achieved. Fifteen practices took part, and contributed data on a total of 358 patients. Of patients without contraindications, 66.5% were taking aspirin, 62.1% were prescribed short-acting nitrates and 58.4% were prescribed beta-blockers. Non-white patients were significantly less likely to receive short-acting nitrates (p < 0.001) and women were significantly less likely to receive beta-blockers (p < 0.01). A total of 83.5% of patients had received smoking cessation advice, 75.1% had weight advice, 75.1% were advised about alcohol use and 64.5% about exercise. Overall, 77.4% had a blood pressure check within the previous twelve months, 40.5% had their cholesterol measured and 33.5% had their blood glucose measured. Non-white patients were significantly less likely to receive smoking cessation, weight, exercise and alcohol advice and were less likely to have their blood pressure checked (all p < 0.0001). Patients aged 65 and over were significantly less likely to receive a cholesterol check (p < 0.0001). None of the auditable standards were actually met. This study shows that there is considerable scope to improve the management of angina patients, with particular regard to aspirin. We recommend that practices develop systems to ensure that the appropriate treatment, advice and checks are given to all patients with angina, paying particular attention to those from ethnic minority backgrounds.

Angina Pectoris↗
PubMed2002

Identification of novel alpha-glucosidase inhibitors by screening libraries based on N- [4-(benzyloxy) benzoyl] alanine derivatives.

A library of 72 compounds related to N- [4-(benzyloxy) benzoyl]alanine (I) was synthesized, prepared and screened for alpha-glucosidase inhibitory activity. Four compounds showed potent inhibition, six compounds moderate inhibition, and 16 were weak inhibitors. One compound, N- [4-(benzyloxy) benzoyl] serine, was found to be a potent inhibitor of alpha-glucosidase with 100% inhibition at 1 micro M. This inhibitor was at least five times more potent than the lead compound I.

Alanine↗
PubMed2001

Removal and recovery of heavy metals from electroplating wastewater by using Kyanite as an adsorbent.

Kyanite, a commercial mineral has been utilized as an adsorbent for the removal of heavy metals, such as Ni(II), Zn(II), Cr(VI) and Cu(II) from electroplating wastewater. The effect of contact time, pH, concentration, adsorbent doses, particle size of the adsorbent, salinity and hardness, both in natural and wastewater on the adsorption of Cu(II) have been studied in detail. The adsorption of metal ions seems to be an ion exchange process. The adsorbed metals ions from electroplating wastewater were recovered by batch as well as column operation using dilute HCl solution. The column operation was found to be more effective compared to batch process.

Adsorption↗
PubMed2001

The nature of soil organic matter affects sorption of pesticides. 1. Relationships with carbon chemistry as determined by 13C CPMAS NMR spectroscopy.

The structural composition of soil organic matter (SOM) was determined in twenty-seven soils with different vegetation from several ecological zones of Australia and Pakistan using solid-state CPMAS 13C NMR. The SOM was characterized using carbon types derived from the NMR spectra. Relationships were determined between Koc (sorption per unit organic C) of carbaryl(1-naphthylmethylcarbamate) and phosalone (S-6-chloro-2,3-dihydro-2-oxobenzoxazol-3-ylmethyl O,O-diethyl phosphorodithioate) and the nature of organic matter in the soils. Substantial variations were revealed in the structural composition of organic matter in the soils studied. The variations in Koc values of the pesticides observed for the soils could be explained only when variations in the aromatic components of SOM were taken into consideration. The highly significant positive correlations of aromaticity of SOM and Koc values of carbaryl and phosalone revealed that the aromatic component of SOM is a good predictor of a soil's ability to bind such nonionic pesticides.

Adsorption↗
PubMed2001

Adsorption behaviour of some aromatic amines on pyrolusite and activated carbon and recovery of beta napthylamine from water sample.

The adsorption behaviour of Diphenylamine (DPAM), beta napthylamine (beta NAM), alpha napthylamine (alpha NAM) and aniline on pyrolusite and activated carbon has been studied. Pyrolusite shows remarkable sorption capacity for DPAM and beta NAM as compared to aniline; (the adsorption followed the order: Activated Carbon:--> DPAM = beta NAM > alpha Aniline; Pyrolusite: DPAM: --> beta NAM > alpha NAM > Aniline) The maximum adsorption of beta NAM occurred in the concentration range 4-20 microg mL(-1) on pyrolusite (95%) and 4-50 microg mL(-1) on activated carbon (100%). The effect of various doses of activated carbon on the adsorption of beta NAM confirm Langmuir and Freundlich isotherms where as Freundlich isotherm is obeyed by pyrolusite. The adsorption of beta NAM on both the absorbents is not affected in presence of DPAM over a wide range of their initial concentrations (20-60 microg mL(-1)). The desorption studies of beta NAM on pyrolusite was carried out by batch as well as column processes. Excellent results were obtained when a mixture of n-hexane and isopropanol (91:1) was used as eluent.

2-Naphthylamine↗
PubMed2001

Evidence for a correlation between antibody-dependent cellular cytotoxicity-mediating anti-HIV-1 antibodies and prognostic predictors of HIV infection.

Using our gp120/41-expressing, NK cell activity-resistant CEM.NKR cell clones as targets in HIV-1-specific antibody-dependent cellular cytotoxicity (ADCC) assays, we demonstrate here that the serum titers of anti-HIV-1 ADCC antibodies bear a significant (P < 0.05) positive correlation with the peripheral blood CD4+ T cell counts and a negative one with the number of copies of HIV-1 RNA in the plasma of HIV-infected individuals. These findings underscore the importance of these antibodies as a protective immune parameter in these infections.

Antibody-Dependent Cell Cytotoxicity↗
PubMed2001

Peritoneal dialysis: new developments and new problems.

AIMS: To ascertain the incidence of hyponatraemia, and the impact of an icodextrin-based dialysis solution regime on hyponatraemia, in diabetic and non-diabetic patients using peritoneal dialysis (PD). METHODS: Following severe hyponatraemia, resulting in neurological sequelae, in two diabetic patients who were on icodextrin-based PD for established renal failure, we reviewed the results of all our PD patients. Data was gathered retrospectively, from our database and case notes, on plasma sodium, haematocrit, dry weight estimation, plasma albumin and residual renal function. Patients using icodextrin-based solutions were compared with a random selection of patients using dextrose-based peritoneal solutions. We also compared diabetic patients on and off icodextrin with their non-diabetic counterparts using the same dialysis regime. The data were analysed using the paired Student's t-test. RESULTS: Plasma sodium was significantly lower in all patients using icodextrin-based solutions compared with those patients on dextrose-based PD. Plasma sodium was also found to fall in all patients following the initiation of an icodextrin-based PD regime. The fall in plasma sodium was statistically significant in diabetic and non-diabetic patients, but only fell below the laboratory reference range in the diabetic patients. CONCLUSIONS: Icodextrin-based PD is a risk factor for hyponatraemia and may produce clinically relevant symptoms if, as in our two cases, the hyponatraemia is compounded by other factors.

Diabetic Nephropathies↗
PubMed2001

Synthesis and structure determination of some oxadiazole-2-thione and triazole-3-thione galactosides.

The syntheses of 5-pyridyl-3(beta-D-galactopyranosyl)-1,3,4-oxadiazole-2-thiones 3a-3c and 5-pyridyl-2(beta-D-galactopyranosyl)-4-benzyl-1,2, 4-triazole-3-thiones 6a-6c are reported. The existence of N-galactosides--not S-galactosides--was proven by IR and 15N NMR spectroscopy. The structures of the final products and the intermediates were elucidated by IR, 1H, 13C and 15N NMR spectroscopy and mass spectrometry.

Chromatography, Thin Layer↗
PubMed2001

Sorption of ametryn and imazethapyr in twenty-five soils from Pakistan and Australia.

Sorption of ametryn and imazethapyr in 25 soils from Pakistan and Australia was investigated using the batch method. The soils varied widely in their intrinsic capacities to sorb these herbicides as shown by the sorption coefficients, Kd, which ranged from 0.59 to 47.6 for ametryn and 0.02 to 6.94 for imazethapyr. Generally the alkaline soils of Pakistan had much lower Kd values of both herbicides than the soils of Australia. Both soil pH and soil organic carbon (SOC) were correlated significantly with the sorption of ametryn, whereas only soil pH was strongly correlated with imazethapyr sorption. No correlation was found between Kd values of the herbicides and the clay contents of the soils. Multiple regression analysis showed that Kd values were better correlated (r2=0.94 and 0.89 for ametryn and imazethapyr, respectively) if SOC and pH were simultaneously taken into account. The study indicated that sorption of these herbicides in the alkaline soils of Pakistan was low and consequently there is considerable risk of groundwater contamination.

Adsorption↗
PubMed2001

Activated human platelets express Fas-L and induce apoptosis in Fas-positive tumor cells.

In addition to their role in hemostasis and thrombosis, platelets are important modulators of immune and inflammatory responses. We provide evidence here that human platelets contain abundant quantities of Fas-L, and upon activation, they express it on their surface as well as release it into medium. This surface-expressed Fas-L is biologically active and can induce apoptosis in Fas-positive human tumor cells. Therefore, activated platelets may represent an important player in Fas/Fas-L-mediated apoptosis.

Apoptosis↗
PubMed2001

Modulation of expression of the MHC class I-binding natural killer cell receptors, and NK activity in relation to viral load in HIV-infected/AIDS patients.

The natural killer (NK) cells play an important role in viral infections via their spontaneous cytolytic activity against virus-infected cells as well as via secreting a variety of soluble mediators. The MHC class I-binding NK receptors of these cells have emerged as the most important regulators of the effector activities of cytolytic cells (both NK and CTL). We have studied the modulation of NK activity and the expression of NK receptors in HIV-infected/AIDS patients and report here that the NK activities of the patients with the lowest plasma HIV load were minimal and vice versa, suggesting a decrease in this activity following suppression of HIV replication. Interestingly, the NK activity correlated negatively with the peripheral blood CD4+ T-cell counts of these patients. Furthermore, these patients showed decreased percentages of CD56+ cells expressing NK receptors of the immunoglobulin superfamily, whereas the percentages of CD8+ cells expressing these receptors were increased. Moreover, the expression of C-type lectin-like NK receptor-associated invariant molecule CD94 was increased on CD8+ cells in these patients as compared with HIV-seronegative controls. These changes in the expression of NK receptors were also evident within groups of these patients having different viral loads. These results show, for the first time, decreased innate immunity and changes in the expression of NK receptors on cytolytic cells in relation to viral burden in HIV-infected/AIDS patient.

Adult↗
PubMed2000

Adsorption studies on Citrus reticulata (fruit peel of orange): removal and recovery of Ni(II) from electroplating wastewater.

The ability of fruit peel of orange to remove Zn, Ni, Cu, Pb and Cr from aqueous solution by adsorption was studied. The adsorption was in the order of Ni(II)>Cu(II)>Pb(II)>Zn(II)>Cr(II). The extent of removal of Ni(II) was found to be dependent on sorbent dose, initial concentration, pH and temperature. The adsorption follows first-order kinetics. The process is endothermic showing monolayer adsorption of Ni(II), with a maximum adsorption of 96% at 50 degrees C for an initial concentration of 50 mg l(-1) at pH 6. Thermodynamic parameters were also evaluated. Desorption was possible with 0.05 M HCl and was found to be 95.83% in column and 76% in batch process, respectively. The spent adsorbent was regenerated and recycled thrice. The removal and recovery was also done in wastewater and was found to be 89% and 93.33%, respectively.

Absorption↗