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Biomedical subjects

S Hasnain

Publications and source records attributed to S Hasnain.

At least 19 recordsLinked to original sources
PubMed2006

Growth stimulatory effect of Ochrobactrum intermedium and Bacillus cereus on Vigna radiata plants.

AIMS: This study assessed the plant growth-promoting ability of the bacterial strains Ochrobactrum intermedium (isolate CrT-1) and Bacillus cereus (isolate S-6). METHODS AND RESULTS: Two chromium resistant bacterial strains isolated from chromium-contaminated wastewater and soils were identified as O. intermedium CrT-1 and B. cereus S-6. These strains were inoculated on seeds of mungbean Vigna radiata var NM-92, which were germinated and grown under chromate salts (300 microg ml(-1) of CrCl(3)or K(2)CrO(4)). The data show that Cr(VI) was more toxic because of its better availability to plants roots when compared with Cr(III). The major part of Cr(VI) supplied to the seedlings was reduced to Cr(III) in the rhizosphere by the bacterial strains, thus lowering the toxicity of chromium to seedlings. CONCLUSIONS: Strains have significant Cr(VI) resistance and reduction potential and have ability to enhance mungbean plant growth under chromium stress. SIGNIFICANCE AND IMPACT OF THE STUDY: These strains could be utilized for the growth of economically important cash crops as well as for the bioremediation of chromium-polluted soils.

Bacillus cereus↗
PubMed1998

Elimination of cardiopulmonary bypass: a prime goal in reoperative coronary artery bypass surgery.

OBJECTIVE: The purpose of this study was to evaluate morbidity and mortality in reoperative coronary artery bypass surgery using the New York State database. METHODS: Patients undergoing reoperative coronary artery bypass between January-1995 and December 1996 were included. Patients were operated using cardiopulmonary bypass (CPB group, n = 184) or without cardiopulmonary bypass (non-CPB group, n = 105) by surgeon preference. Groups were compared for preoperative risk factors, postoperative mortality and major complications. RESULTS: Crude mortality was lower in the non-CPB group, despite a higher expected mortality, resulting in a risk-adjusted mortality of 1.3% versus 2.7% for the CPB group (NS). Of non-CPB patients, 91.4% were without complications, while only 72.1% of CPB patients (P < 0.0001) were complication-free. Major complications were significantly reduced in non-CPB patients compared to CPB patients: stroke 0% versus 3.8% (P < 0.04), cardiovascular complications 4.8% versus 15.8% (P < 0.005), other major complications 1.9% versus 10.4% (P < 0.007). Postoperative IABP support was needed in 1.9% of the non-CPB group patients and in 14.2% of the CPB group (P < 0.0007). CONCLUSIONS: The main object of reoperative CABG is to relieve symptoms, since the survival benefit of the procedure has not been demonstrated. Performance of reoperative coronary artery bypass surgery without cardiopulmonary bypass significantly reduces morbidity. We conclude that cardiopulmonary bypass should be avoided whenever possible in reoperative coronary bypass surgery.

Aged↗
PubMed1998

Cardiovascular risk in hypertension: implications of the Sheffield Table for lipid-lowering strategy.

OBJECTIVE: To determine the actual use of 'statin' therapy for primary and secondary prevention and the potential effect of using the Sheffield Table for primary prevention of coronary heart disease upon 'statin' use in a consultant-run Hypertension and Cardiovascular Risk Clinic. DESIGN: Prospective audit of the current use of cholesterol-lowering therapy and the effect of implementing the criteria used in the Sheffield Table and the Scandinavian Simvastatin Study for cholesterol lowering in 'at risk' patients upon statin use in a consultant-led cardiovascular risk clinic. SETTING: The Aberdeen Hypertension Clinic. RESULTS: A total of 1500 patients were reviewed of which 416 (27.7%) had experienced at least one clinical manifestation of atherosclerotic cardiovascular disease (CVD) and 392 (94%) of these had a total cholesterol measured of whom 298 (76%) had a total cholesterol >5.5 mmol/l. Only 11.2% of eligible patients were actually receiving lipid-lowering treatment for secondary prevention. A total of 1084 patients with no prior cardiovascular disease were identified, 97 (8.9%) were excluded because of age. Using the Sheffield Table, 92 (9.4%) of these patients were eligible for statin therapy and only six of the 92 patients were actually receiving treatment. CONCLUSIONS: The results of this study reveal that even in a consultant-led cardiovascular prevention clinic there is a significant discrepancy between optimal evidence-based management and the actual delivery of clinical care. Seventy-two per cent and 9.3% of patients attending the clinic were eligible for statin treatment for secondary and primary prevention, respectively. However, only 11.2% of patients suitable for secondary prevention and 6.5% of patients suitable for primary prevention were actually receiving appropriate lipid-lowering therapy. Considering the proven benefit of this form of medical intervention the results of this study are of real importance to practising clinicians and patients alike.

Aged↗
PubMed1998

Evaluation of the performance of hysterosalpingo contrast sonography in 500 consecutive, unselected, infertile women.

The performance of hysterosalpingo contrast sonography (Hy Co Sy) as a first-line, outpatient investigation of tubal patency was examined in 500 consecutive, infertile women, at one centre. Hy Co Sy was completed in 463 (92.6%) cases, using a galactose microbubble contrast agent (Echovist-200) and transvaginal sonography. Initial plain scanning identified adnexal pathology in 198 women (39.6%). Examination with Echovist was attempted for 905 tubes and only 67 (7.4%) were not assessable; after the first 100 women this decreased to 35 tubes (4.8%). A sonographic appearance compatible with blocked tubes was found on 118 (14.1%) occasions but it was also possible to identify variations in the appearance/filling/spilling patterns of individual tubes which increased the number assessed as abnormal to 193 (23.0%). Comparison with laparoscopy and dye chromopertubation findings from the past three years was possible for 185 (37%) women, representing 282 tubes, which gave Hy Co Sy an overall concordance rate of 85.8%, sensitivity of 90.4%, specificity of 70.3%, positive predictive value of 91.2% and negative predictive value of 68.2%. Some 51.0% of women described only mild discomfort and there were no significant postprocedure complications. Hy Co Sy appears to be an acceptable first-line screen and may select out women in whom more invasive investigations are likely to reveal pathology.

Adult↗
PubMed1998

Routine use of saline hysterosonography in 500 consecutive, unselected, infertile women.

Saline hysterosonography was attempted as a routine, first-line screening test of uterine structure in 500 consecutive, unselected, infertile women. The procedure was completed in 96.8% (484/500) women and the observations were interpretable in 483 of these women. Intrauterine pathology was suspected in 67/499 (13.4%) women on plain ultrasound scan and 58/484 (12%) women with saline hysterosonography. Ultrasound alone had a superior specificity (96.3%) to sensitivity (81.8%) and better negative (97.6%) than positive (73.8%) predictive value for the detection of any intrauterine abnormality, using saline hysterosonography as the reference procedure. Suspected pathology at saline hysterosonography led to hysteroscopy in 20 women, after a median of 5.7 months (range, 1-14). The overall concordance rate between the two procedures was 65% with lesions suspicious of intrauterine polyps not present at subsequent hysteroscopy on six occasions. Criteria were established to help identify women with potentially self-limiting lesions, in whom a re-scan should be considered before resorting to hysteroscopy. The procedure was well tolerated with no significant complications. Saline hysterosonography appeared to be an acceptable first-line screening procedure for uterine structure which enhanced the predictive power of ultrasound alone for uterine anomalies and provided additional information which was potentially of value when planning operative hysteroscopy.

Adult↗
PubMed1998

Coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB): a strategy for improving results in surgical revascularization.

BACKGROUND: Coronary artery bypass grafting (CABG) was performed on patients with cardiopulmonary bypass (CPB group) or without CPB (non-CPB group). A series of CABG patients, performed between January 1, 1995 and September 30, 1997 is included. METHODS: Data were collected and analyzed as determined by the New York State Department of Health. Preoperative comorbidity, postoperative morbidity and mortality were compared. There were 2869 patients in the CPB group and 505 patients in the non-CPB group. RESULTS: Demographics of the two groups were similar but preoperative risk factors were more common in patients undergoing CABG without CPB. Of the non-CPB patients, 31.9% had reoperations as compared to 8.5% in CPB patients (p = 0.00005). The presence of an extensively calcified aorta was more common in the non-CPB patients (5.9% vs. 2.8%, p = 0.0002). Immune deficiency was also more common in the non-CPB group (p = 0.001). Risk-adjusted mortality was similar in the two groups while major complications were much less common when CPB was not utilized. In CPB patients only 84.3% avoided major complications, while among non-CPB patients 90.1% were complication-free (p = 0.0008). CONCLUSIONS: CABG without CPB is an attractive method of surgical revascularization. Increasing age and preoperative comorbidity in patients referred for CABG dictate changes in surgical strategy, of which avoidance of CPB appears most beneficial.

Adult↗
PubMed1997

Growth stimulation of Triticum aestivum seedlings under Cr-stresses by non-rhizospheric pseudomonad strains.

Four chromium-resistant non-rhizospheric strains SPCr-1, SPCr-2, SPCr-3 and SPCr-4 (Pseudomonads), which were isolated from the effluents of an ICI paint factory and could tolerate 2-3 mg ml(-1) chromium in a minimal medium and 40 mg ml(-1) in a rich medium, were used to inoculate seeds of Triticum aestivum. Both inoculated and non-inoculated seeds were germinated and grown under different concentrations of chromium salts (K2CrO4, 0, 100, 250, 500; CrCl3, 0, 250, 500, 1000 microg ml(-1)). Germination and growth parameters were severely affected by chromium-salts. K2CrO4 had more drastic effects than CrCl3 treatments. Seedlings had a hard and brittle texture and showed symptoms of hypertrophy. Brown spots on leaves and stems were visible and the tips of leaves were bifurcated and curled. The root system was also impaired, ranging from a browning of the tip to complete destruction of cortical tissues. Under chromium-stress conditions, inoculated plants had significantly better germination and growth as compared to non-inoculated treatments. Bacterial growth enhancement of seedlings was associated with reduced chromium-uptake, increased auxin content and the formation of stress specific proteins. With bacterial inoculations, symptoms of chromium toxicity were reversed, especially at lower concentrations of chromium salts.

Journal Article↗
PubMed1996

Two related rolling circle replication plasmids from salt-tolerant bacteria.

In a range of salt-tolerant bacteria isolated from soil, rhizosphere, and phyloplane, cross-hybridization tests revealed a group of seven plasmids which were chosen for further study. Two plasmids (pSH1418 and pSH1451) were picked as representative examples of the two related subgroups. Restriction mapping and Southern blotting identified a region common to the two plasmids which later was identified as encoding the replication functions. We were unable to join these plasmids to high-copy-number vectors but this was possible with low-copy-number IncP vectors. In Escherichia coli, cloned plasmids pSH1418 and pSH1451 conferred salt tolerance but the phenotype was unstable, with the loss of salt tolerance apparently being correlated with structural instability of the plasmid DNA. Plasmid pSH1451 was sequenced and shown to be closely related to RCR plasmids of Gram-positive bacteria. The host of this plasmid was classified as Bacillus pumilus by rDNA typing and lipid profiling by gas chromatography. A number of open reading frames (orfs) which could code for salt tolerance or other functions were identified in the plasmid sequence. Sequence similarity to previously sequenced genes suggested that the products of orf4 and orf5 may work together to transport a molecule such as aspartate ion that may promote osmotolerance.

Amino Acid Sequence↗
PubMed1996

Comparison of long-term patency of "horseshoe" saphenous vein grafts with and without valves.

OBJECTIVE: The paper analyzes the long-term patency of valveless and valvular limbs of reversed saphenous veins. METHODS: Between 1983 and 1988, 335 patients underwent isolated coronary artery bypass grafting (CABG) with 1,329 grafts. Eighty-three patients had follow-up angiography over 8-12 years. The side-to-side saphenous vein to aortic "horseshoe" anastomosis was created just before the first valve from the ankle (naturally a valveless portion). The valveless (ankle end) was depicted in every case. These patients with angiography were similar to 252 patients without angiography in terms of age, gender, number of grafts, diseases vessels, single (A) and sequential (B) grafts and actuarial survival. In the 83 patients, graft patency was 75%. Overall patency was the same in B versus A grafts (76% versus 74.6%); valveless patency (78.7%) was slightly better than valvular patency (73.3%). RESULTS: In patients with B grafts (88.6%) valveless patency was significantly better than valvular patency (71.9%) (P < 0.02). The patency of B-valveless to the left coronary bed was also better, (86.8% versus B-valvular 70.5%, P < 0.04). Attrition of the B-valveless and B-valvular grafts was similar up to 8 years, but by the 12th year it had become significantly different (P < 0.05). The 12-year actuarial survival rate of the patients was 87.7%. CONCLUSIONS: We recommended the use of valveless vein segments when possible.

Actuarial Analysis↗
PubMed1995

Characterization of the S3 subsite specificity of cathepsin B.

Five synthetic substrates containing different amino acid residues at the P3 position (acetyl-X-Arg-Arg-AMC, where X is Gly, Glu, Arg, Val, and Tyr and where AMC represents 7-amindo-4-methylcoumarin) were used to investigate the S3 subsite specificity of cathepsin B. At pH 6.0, the specificity constant, kcat/Km, for tripeptide substrate hydrolysis was observed to increase in the order Glu < Gly < Arg < Val < Tyr. Molecular modeling studies of substrates containing a P3 Glu, Arg, or Tyr covalently bound as the tetrahedral intermediate to the enzyme suggest that the specificity for a P3 Tyr is because of a favorable aromatic-aromatic interaction with Tyr75 on the enzyme as well as a possible H bond between the P3 Tyr hydroxyl and the side chain carboxyl of Asp69.

Amino Acid Sequence↗
PubMed1995

Crystal structures of recombinant rat cathepsin B and a cathepsin B-inhibitor complex. Implications for structure-based inhibitor design.

The lysosomal cysteine proteinase cathepsin B (EC 3.4.22.1) plays an important role in protein catabolism and has also been implicated in various disease states. The crystal structures of two forms of native recombinant rat cathepsin B have been determined. The overall folding of rat cathepsin B was shown to be very similar to that of the human liver enzyme. The structure of the native enzyme containing an underivatized active site cysteine (Cys29) showed the active enzyme conformation to be similar to that determined previously for the oxidized form. In a second structure Cys29 was derivatized with the reversible blocking reagent pyridyl disulfide. In this structure large side chain conformational changes were observed for the two key catalytic residues Cys29 and His199, demonstrating the potential flexibility of these side chains. In addition the structure of the complex between rat cathepsin B and the inhibitor benzyloxycarbonyl-Arg-Ser(O-Bzl) chloromethylketone was determined. The complex structure showed that very little conformational change occurs in the enzyme upon inhibitor binding. It also allowed visualization of the interaction between the enzyme and inhibitor. In particular the interaction between Glu245 and the P2 Arg residue was clearly demonstrated, and it was found that the benzyl group of the P1 substrate residue occupies a large hydrophobic pocket thought to represent the S'1 subsite. This may have important implications for structure-based design of cathepsin B inhibitors.

Amino Acid Chloromethyl Ketones↗
PubMed1994

Sero-diagnosis for viral hepatitis in 93 patients admitted with acute hepatitis in three different teaching hospitals in Lahore.

Serodiagnosis was done in 93 patients admitted with acute viral hepatitis (AVH) to three teaching hospitals in Lahore. Five (5.4%) had hepatitis A, 39 (41.9%) hepatitis B (2 of these were anti delta positive) [see erratum notice], 44 (47.3%) probable hepatitis E and 3(3.2%) had HAV/HBV co-infection. Antibody to hepatitis C (anti HCV) was detected in 6 patients (6.4%); 2 with HBV and 4 with probable HEV infection. Excluding 39 patients with hepatitis B and 3 with HBV as part of co-infection, there was evidence of previous HBV infection in 39 out of the remaining 51 patients. In the subset of 6 children, 3 had hepatitis A and 3 hepatitis E. Of these, 5 had evidence of previous exposure to HBV and one was also positive for anti HCV. Our results are suggestive of a strong background of HBV infection raising concern about its chronic sequelae in the community.

Acute Disease↗
PubMed1993

Characterization of cathepsin B specificity by site-directed mutagenesis. Importance of Glu245 in the S2-P2 specificity for arginine and its role in transition state stabilization.

The pH dependence of cathepsin B-catalyzed hydrolyzes is very complex. At least seven dissociable groups are involved in the binding and hydrolysis of 7-amido-4-methyl coumarin and p-nitroaniline (pNA)-based substrates containing a P1 Arg and either a Phe or Arg at the P2 position. By site-directed mutagenesis we show that a previous suggestion, that Arg202 is one of the groups which influences the pH dependence of cathepsin B-catalyzed hydrolysis of the Z-Arg-Arg-pNA substrate, is not valid. However, it was found that Glu245, which has a pKa of 5.1 in rat cathepsin B, is responsible for the S2-P2 specificity for Arg-containing substrates and controls the pH dependence of their hydrolysis. Furthermore, the data indicate that Glu245, which forms a hydrogen bond with the guanidinium group of the substrate's P2 Arg, contributes about 1.8 kcal/mol to transition state stabilization in the protonated state and about 0.6 kcal/mol in the deprotonated state. Mutation of Glu245 to Gln results in a 16-fold decrease in kcat but does not affect Km. While cathepsin B has a 7-fold preference for Phe over Arg at the P2 position of a substrate, binding of the aromatic side chain does not appear to be influenced by Glu245.

Amino Acid Sequence↗
PubMed1993

The effects of lead-resistant pseudomonads on the growth of Triticum Aestivum seedlings under lead stress.

Five Pseudomonad strains, SPb-1, SPb-2, SPb-3, (from a water sample), SPb-4, and SPb-5 (from rhizosphere), which could tolerate lead acetate up to 1000 microm ml(-1), were isolated from an industrially polluted area around Kasoor, Pakistan. Only SPb-5 harbours a lead-resistant plasmid. Triticum aestivum seeds inoculated with strains SPb-4 and SPb-5 were germinated and grown under different concentrations (0, 1, 5, 10, 15 and 20 mM) of lead acetate for ten days. Germination and seedling growth were adversely affected. Poor growth was associated with increased lead content of seedlings. With bacterial inoculation, germination and seedling growth were improved, as compared with non-inoculated treatments. Stimulation in the growth of seedlings was accompanied by a decrease in lead content, as compared with non-inoculated treatments.

Journal Article↗
PubMed1992

Human tumour cathepsin B. Comparison with normal liver cathepsin B.

Cathepsin B was purified from normal human liver and several human tumour tissues and partially characterized. Three forms of cathepsin B, with molecular masses of 25 kDa, 26 kDa (the two appearing as a doublet) and 30 kDa, were detected in SDS/polyacrylamide gels. The 25-26 kDa doublet was associated with the fractions from tumours and normal liver containing the highest cathepsin B activity. Cathepsin B from both sources showed similar pH optima. Both normal liver and tumour cathepsin B exhibited similar kinetics against selected synthetic substrates. At neutral pH and 24 degrees C, cathepsin B from both normal liver and tumour exhibited a lower Km and a higher kcat./Km than at pH 6.0. Their inhibitory profiles against synthetic inhibitors were also similar. Immunological studies with a monospecific antibody against the mature double-chain form of human liver cathepsin B and an antibody against a cathepsin B-derived synthetic peptide established the immunological similarity of liver and tumour enzymes. The N-terminal sequences of the 25 kDa and 26 kDa forms were identical with that of the heavy chain of the mature double-chain form of human cathepsin B, whereas the N-terminal sequence of the 30 kDa species was identical with that of the single-chain form of human cathepsin B. Treatment of the double-chain form of cathepsin B from normal liver and tumours with the endoglycosidase peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase converted the 26 kDa form into 25 kDa in SDS/polyacrylamide gels, suggesting that cathepsin B may exist as both glycosylated and unglycosylated forms. Our results, in contrast with those reported earlier for mouse cathepsin B, indicate that human liver and tumour cathepsin B are similar.

Amino Acid Sequence↗