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Biomedical subjects

Z Hussain

Publications and source records attributed to Z Hussain.

At least 37 records · Page 2Linked to original sources
PubMed2004

What is the relationship between male sexual function and lower urinary tract symptoms (LUTS)?

INTRODUCTION: There is considerable current interest in the relationship between LUTS and sexual function in men, and in particular whether there is a causative relationship between them. This observational study, performed in a single centre, seeks to explore this area further. METHODS: 1,420 patients attending a prostate assessment clinic were assessed by International Prostate Symptoms Score (IPSS), BPH impact index (BPH-II), Urinary flow rate (Q(max)), post-void residual volume (PVR) and the O'Leary sexual questionnaire (which assesses erectile, ejaculatory and sexual drive). The results were analyzed using univariate and multivariate techniques. RESULTS: Following exclusion of those with incomplete data, those who were not sexually active, those with PSA >20 ng/ml and those who refused to fill in the questionnaire, there were 696 evaluable patients. Using univariate techniques, age, IPSS, Quality of life (QOL), BPH-II, Q(max) and PVR all correlated with differing domains of sexual function including erectile and ejaculatory function. Multiple regression analysis demonstrated that age was overwhelmingly the most important predictor of sexual function, but that BPH-II and QOL were also predictive for some domains, while the IPSS score was not. CONCLUSION: This study confirms that a significant proportion of men with LUTS have sexual dysfunction. The relationship is complex and differs according to the type of sexual dysfunction.

Age Factors↗
PubMed2003

Metallic behavior of lightly doped La2-xSrxCuO4 with a Fermi surface forming an arc.

Lightly doped La2-xSrxCuO4 in the so-called "insulating" spin-glass phase has been studied by angle-resolved photoemission spectroscopy. We have observed that a "quasiparticle" (QP) peak crosses the Fermi level in the node direction of the d-wave superconducting gap, forming an "arc" of Fermi surface, which explains the metallic behavior at high temperatures of the lightly doped materials. The QP spectral weight of the arc smoothly increases with hole doping, which we attribute to the n approximately x behavior of the carrier number in the underdoped and lightly doped regions.

Journal Article↗
PubMed2003

Metal-insulator transitions in an expanding metallic fluid: particle formation kinetics.

Core-level photoemission spectroscopy provides a local probe of expansion dynamics and associated transient chemical properties as a highly pressurized, metallic fluid expands into vacuum following impulsive heating of a semiconductor by an intense, ultrashort laser pulse. Transient photoemission peak shifts reveal that metal-insulator transitions occur rapidly following laser heating. These experiments probe constituents species and solidification kinetics occurring in the early moments of material ejection and provide insight into how particles arise in the current laser ablation regime.

Journal Article↗
PubMed2003

Band structure and Fermi surface of electron-doped C60 monolayers.

C60 fullerides are challenging systems because both the electron-phonon and electron-electron interactions are large on the energy scale of the expected narrow band width. We report angle-resolved photoemission data on the band dispersion for an alkali-doped C60 monolayer and a detailed comparison with theory. Compared to the maximum bare theoretical band width of 170 meV, the observed 100-meV dispersion is within the range of renormalization by electron-phonon coupling. This dispersion is only a fraction of the integrated peak width, revealing the importance of many-body effects. Additionally, measurements on the Fermi surface indicate the robustness of the Luttinger theorem even for materials with strong interactions.

Journal Article↗
PubMed2003

Management of pediatric urolithiasis in Pakistan: experience with 1,440 children.

PURPOSE: We evaluated the efficacy and safety of different modalities for pediatric urolithiasis in a developing country in 2 eras, namely before and after the advent of minimally invasive surgery. MATERIALS AND METHODS: We retrospectively reviewed the records of 1,440 children younger than 14 years treated with various modalities during a 14-year period. From 1987 to 1995, 486 and 50 patients were treated with open surgery, and extracorporeal shock wave lithotripsy (ESWL, Dornier Medical Systems, Inc., Marietta, Georgia) and minimally invasive methods, respectively. Between 1996 and 2000, 518 and 386 children were treated with surgery and minimally invasive methods, respectively. RESULTS: Of the 1,440 children 795 (55.2%) had renal, 198 (13.8%) had ureteral and 447 (31%) had bladder calculi. Of the renal stones 556 (70%), 177 (22%) and 62 (7.8%) were treated with open surgery, ESWL and percutaneous nephrolithotomy, respectively. Of the ureteral calculi 85 (43%), 37 (18.6%) and 76 (38%) were managed by ESWL, ureterorenoscopy and open surgery, respectively. Of the bladder calculi 307 (68%), 77 (17.2%) and 63 (14%) were treated with open vesicolithotomy, transurethral pneumatic cystolithotripsy and ESWL, respectively. The renal stone clearance rate was 98% after open surgery, 84% after ESWL and 68% after percutaneous nephrolithotomy monotherapy at 3 months of followup. Similarly the ureteral stone-free rate was 54% after ESWL and 86.9% after ureterorenoscopy. Of the patients with bladder calculi 48% and 93% become stone-free after ESWL and transurethral pneumatic cystolithotripsy, respectively. CONCLUSIONS: The use of ESWL, percutaneous nephrolithotomy and ureterorenoscopy has resulted in treating a large number of children with a short hospital stay and early return to school. Open surgery is reserved only for complex stones.

Adolescent↗
PubMed2003

Antituberculosis drug-induced hepatitis: risk factors, prevention and management.

Apart from infectious or viral hepatitis, other most common non-infectious causes of hepatitis are alcohol, cholestatic, drugs and toxic materials. The most common mode that leads to liver injuries is antituberculosis drug-induced hepatitis. The severity of drug-induced liver injury varies from minor nonspecific changes in hepatic structure to fulminant hepatic failure, cirrhosis and liver cancer. Patients receiving antitubercular drug frequently develop acute or chronic hepatitis. The time required for the metabolites to reach hepatotoxic levels is much earlier with isoniazid plus rifampicin treatment than isoniazid alone and this has been shown to be synergistic rather than additive. Antituberculosis drug (ATT)-inducible cytochrome P-4502E1 (CYP2E1) is constitutively expressed in the liver. Recent studies show that polymorphism of the N-acetyltransferase 2 (NAT2) genes and glutathione-S-transferase (GST) are the major susceptibility risk factors for ATT-induced hepatitis. The hepatic NAT and GST are involved in the metabolism of several carcinogenic arylamines and drugs. The NAT2 enzyme has a genetic polymorphism in human. N-acetyltransferase 2 genes (NAT2) have been identified to be responsible for genetic polymorphism of slow and rapid acetylation in humans. Slow acetylators of NAT2 prove to develop more severe hepatotoxicity than rapid acetylators making it a significant risk factor. Deficiency of GST activity, because of homozygous null mutations at GSTM1 and GSTT1 loci, may modulate susceptibility to drug and xenobiotic-induced hepatotoxicity. Polymorphisms at GSTM1, GSTT1 and NAT2 loci had been linked to various forms of liver injury, including hepatocellular carcinoma.

Antitubercular Agents↗
PubMed2002

Anomalous momentum dependence of the quasiparticle scattering rate in overdoped Bi2Sr2CaCu2O8.

The question of the anisotropy of the electron scattering in high temperature superconductors is investigated using high resolution angle-resolved photoemission data from Pb-doped Bi2Sr2CaCu2O8 (Bi2212) with suppressed superstructure. The scattering rate of low energy electrons along two bilayer-split pieces of the Fermi surface is measured (via the quasiparticle peak width), and no increase of scattering towards the antinode (pi,0) region is observed, contradicting the expectation from Q=(pi,pi) scattering. The results put a limit on the effects of Q=(pi,pi) scattering on the electronic structure of this overdoped superconductor with still very high T(c).

Journal Article↗
PubMed2002

Pediatric urolithiasis: developing nation perspectives.

PURPOSE: We evaluated epidemiology, etiology, dietary and urinary risk factors, and the composition of calculi in pediatric stone formers in Pakistan. MATERIALS AND METHODS: This retrospective study includes 1,440 children treated between 1987 and 2000. Case records were reviewed for demographics, etiology and clinical symptoms. Dietary and urinary risk factors were analyzed prospectively in idiopathic stone formers. Stone composition was analyzed by infrared spectroscopy. RESULTS: There were 1,075 males and 365 females for a male-to-female ratio of 3:1. The peak age for renal and bladder stones was 6 to 10 and 1 to 5 years, respectively. Overall 795 stones (55%) were renal, 198 (14%) were ureteral and 447 (31%) were vesical. Bladder stones were present in 60% of cases in the mid 1980s but decreased to 15% in the mid 1990s. The clinical symptoms were abdominal pain in 511 patients (51%) and fever in 193 (19.5%). There were anatomical abnormalities in 96 patients (12%), metabolic abnormalities in 206 (25%), infection stones in 60 (7%) and idiopathic stones in 444 (55%). Urinary analysis in idiopathic stone formers revealed hypercalciuria in 17 (11%), hyperoxaluria in 62 (40%), hyperuricosuria in 41 (27%) and hypocitruria in 97 (63%). Diet involved a low intake of protein in 60 cases (44%), calcium in 45 (33%), potassium in 105 (77%) and high oxalate in 75 (55%). The composition was calcium oxalate in 362 stones (47%), ammonium hydrogen urate in 210 (27%) and struvite in 49 (6.4%). Stones recurred in 30 patients (2%). CONCLUSIONS: The pattern of calculous disease changed from a predominantly lower tract site in the mid 1980s to the upper tract in the mid 1990s. Stone composition, urinary risk factors and dietary analysis suggest that diet, dehydration and poor nutrition are the main causative factors of stone disease.

Adolescent↗
PubMed2002

Living-related pediatric renal transplants: a single-center experience from a developing country.

We retrospectively analyzed the results of 75 living-related pediatric renal transplants performed at our center between January 1986 and December 1999. The major causes of end-stage renal disease (ESRD) were glomerulonephritis (26%) and nephrolithiasis (16%), while the etiology was unknown in 50%. The mean age of the recipients was 12 yr (range 6-17 yr) and that of the donors was 39 yr (range 20-65 yr). The majority (73%) of donors were parents. Eighty five per cent of donors were one-haplotype matched and the rest identical. Immunosuppression was based on a triple drug regimen. Thirty per cent of recipients were rapid metabolizers of cyclosporin A (CsA) (area under the curve [AUC]: < 6,000 ng/mL/h), while 16% were slow metabolizers (AUC: > 8,000 ng/mL/h). Forty three (57%) children encountered 59 rejection episodes, the majority of which (59%) were recorded in the first month post-transplant. Seventy-four per cent of the rejection episodes were steroid sensitive and the rest, except two, were resolved by therapy with antithymocyte globulin (ATG) or orthoclone thymocyte 3 (OKT3). After a mean follow-up of 37 months, 17 (22%) grafts had chronic rejection and 76% of these recipients had previously experienced acute rejection episodes. The overall infection rate was high, necessitating two hospital admissions/patient/year. The majority (53%) of the infections were bacterial. Urinary tract infections (UTIs) were seen in 17 (23%) recipients. Twelve of these had ESRD as a result of stone disease and eight grafts were lost because of UTIs. Eight per cent of recipients developed tuberculosis (TB), and extra-pulmonary lesions were seen in 50%. Surgical complications were encountered in eight patients. Free medication to all recipients and parental support ensured a compliance rate of 93%. Baseline growth deficit was seen in children of the two groups studied (the 6-12 yr and 13-17 yr age-groups), with Z-scores of - 2.39 and - 2.12, respectively. No growth catch-up was observed at 12 and 24 months in either group. Post-donation complications were seen most commonly in donors > 50 yr of age and included: proteinuria (> 300 mg/24 h, four patients), hypertension (three patients), and diabetes (one patient). Twenty-four grafts were lost, 54% as a result of immunological and the rest as a result of non-immunological causes, and 17 recipients died during the follow-up period. Infections were the main cause of patient and graft loss. Overall 1- and 5-yr graft and patient survival rates were 88% and 65%, and 90% and 75%, respectively.

Child↗
PubMed2002

In vitro activity of quinupristin/dalfopristin, linezolid, telithromycin and comparator antimicrobial agents against 13 species of coagulase-negative staphylococci.

OBJECTIVES: To determine in vitro susceptibilities of a large series of speciated coagulase-negative staphylococci (CNS) against three new antibiotics, linezolid, quinupristin/dalfopristin and telithromycin. METHODS: Susceptibilities to three new antibiotics and oxacillin, vancomycin, clindamycin and erythromycin were determined by the agar dilution method, as described by the NCCLS. RESULTS: Resistance to linezolid was not observed in any isolates, although MIC90 values varied between species. Fifteen of 658 (2.3%) isolates were resistant to quinupristin/dalfopristin, but < 1% of the clinically most important isolates of Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus hominis demonstrated resistance to this agent. Susceptibility to clindamycin correlated with susceptibility to quinupristin/dalfopristin; however, resistance to clindamycin did not predict quinupristin/dalfopristin resistance. Telithromycin was the least active of the new agents tested, showing activity similar to that of clindamycin. Susceptibility and resistance to clindamycin were predictive of susceptibility and resistance to telithromycin. CONCLUSION: Clindamycin susceptibility can be used as a surrogate marker for susceptibility to quinupristin/dalfopristin and telithromycin. Quinupristin/dalfopristin and linezolid show good activity against both mecA-positive and -negative CNS.

Acetamides↗
PubMed2001

Evidence for ubiquitous strong electron-phonon coupling in high-temperature superconductors.

Coupling between electrons and phonons (lattice vibrations) drives the formation of the electron pairs responsible for conventional superconductivity. The lack of direct evidence for electron-phonon coupling in the electron dynamics of the high-transition-temperature superconductors has driven an intensive search for an alternative mechanism. A coupling of an electron with a phonon would result in an abrupt change of its velocity and scattering rate near the phonon energy. Here we use angle-resolved photoemission spectroscopy to probe electron dynamics-velocity and scattering rate-for three different families of copper oxide superconductors. We see in all of these materials an abrupt change of electron velocity at 50-80 meV, which we cannot explain by any known process other than to invoke coupling with the phonons associated with the movement of the oxygen atoms. This suggests that electron-phonon coupling strongly influences the electron dynamics in the high-temperature superconductors, and must therefore be included in any microscopic theory of superconductivity.

Journal Article↗
PubMed2001

Dual nature of the electronic structure of (La(2--x--y)Nd(y)Sr(x))CuO(4) and La(1.85)Sr(0.15)CuO(4).

High resolution angle-resolved photoemission measurements have been carried out on (La(1.4--x)-Nd(0.6)Sr(x))CuO(4), a model system with static one-dimensional (1D) charge ordering (stripe), and (La(1.85)-Sr(0.15))CuO(4), a high temperature superconductor (T(c) = 40 K) with possible dynamic stripes. In addition to the straight segments near ( pi,0) and ( 0,pi) antinodal regions, we have identified the existence of spectral weight along the [1,1] nodal direction in the electronic structure of both systems. This observation of nodal state, together with the straight segments near antinodal regions, reveals the dual nature of the electronic structure of stripes due to the competition of order and disorder.

Journal Article↗