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Biomedical subjects

B Khan

Publications and source records attributed to B Khan.

At least 19 recordsLinked to original sources
PubMed2006

Medical management of male infertility.

Management of male infertility is always a difficult task. In recent years booming of artificial reproductive technologies (ART) has put infertologists and andrologists in front of a million dollar question whether to treat the person or the gametes. A basic andrology laboratory at present has become part and parcel of an infertility clinic. Hence treatment of male infertility has become institutional and collective for clinicians and basic scientists. The basic approach towards management of male infertility includes confirmation of diagnosis and to find out the cause for which pathological, endocrinological and biochemical tests are essential. In this series specific defects causing seminopathy has been found in 18% cases where treatment is straightforward and towards the cause. The main bulk of idiopathic seminal defects (82%) really poses challenge to the infertologists so far management is concerned. In this study commonest seminal defect has been found to be oligoasthenozoospermia which amounts to 63% cases. For medical management purpose drugs commonly used are clomiphene, gonadotrophins, bromocriptine, L-thyroxine, vitamin E, B12, etc. When they fail the main approach remains to be intra-uterine insemination (IUI) and ART eg, in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI).

Androgens↗
PubMed2004

Analysis of genetic variability of Indian isolates of Hepatitis C virus.

The degree of genetic variability among Hepatitis C virus strains circulating in India is currently unknown. In order to get insight into this matter, sequence data obtained from the 5' non coding region from 8 patients from New Delhi were compared with sequences from 16 HCV isolates from different geographic locations of India. The phylogenetic analysis of most prevalent genotypes revealed the presence of novel HCV variants in type 1 strains.

5' Untranslated Regions↗
PubMed2004

Allogeneic bone marrow transplantation in beta-thalassaemia--single centre study.

OBJECTIVE: To evaluate outcome of allogeneic BMT in beta-Thalassaemia at the Armed Forces Bone Marrow Transplant Centre, Rawalpindi, Pakistan from August 2001 to November 2003. METHODS: Nineteen patients with beta-Thalassaemia underwent allogeneic BMT/PBSC transplantation from HLA identical sibling donors. Patients were classified in three groups according to Pesaro (Italy) risk classification. Class-I (n = 9) and Class-II (n = 7) patients received conditioning with busulphan/cyclophosphamide, whereas Class-III (n = 3) patient received conditioning with hydroxyurea, azathioprine, fludarabine, along with Bu14 / Cy 200. Cyclosporine, prednisolone and methotrexate were given for GvHD prophylaxis. Stem cells dose infused was >4.0 x 10(8)/kg body weight of the patient. RESULTS: Engraftment was achieved in all Class-I patients, whereas in Class-II and Class-III , graft rejection was observed in one patient from each class. Median time to achieve absolute neutrophil recovery (> 0.5 x 10(9)/l) was 13 days, platelet count (> 20 x 10(9)/1) was 15 days and reticulocyte count (>0.5%) was 15 days. Acute GvHD was observed in 15 patients. One patient developed grade IV GvHD (liver and skin) and died within 30 days post BMT. Post transplant infectious complications were pseudomonas septicemia, disseminated fungal infection, CMV pneumonia and tuberculosis. Three patients died of these complications during post transplant period (31-90 days). Median stay in hospital was 25 days. CONCLUSION: Allogeneic BMT is the only curative therapy for beta-Thalassaemia patients, however the success rate can be increased if the patients are selected carefully and transplanted at an early age.

Adolescent↗
PubMed2002

Analysis of genetic heterogeneity of hepatitis C viruses in Central America reveals a novel genetic lineage. Brief report.

Hepatitis C virus (HCV) has high genomic variability and at least six different types have been reported. The genotypes distribution is currently unknown among HCV strains circulating in Central America. In order to study the degree of genetic variability of strains isolated in Costa Rica, sequence data obtained from the 5' non coding region from 7 patients from Costa Rica were compared with published sequences from 57 strains of all types. The phylogenetic analysis revealed the existence of type 1 strains of a novel genetic lineage, recently described for some South American countries, and indicates an increasing diversification of HCV.

5' Untranslated Regions↗
PubMed2002

Thalidomide prevents donor corneal graft neovascularization in an alkali burn model of corneal angiogenesis.

OBJECTIVE: Thalidomide is a potent inhibitor of angiogenesis. We evaluated the effects of Thalidomide on corneal angiogenesis and on tissue survival of grafts in rabbit eyes with pre-existing neovascularization secondary to alkali burn. METHODS: Sixteen rabbits received alkali burns to one cornea. One month post-injury, assessments of corneal neovascularization were performed followed by corneal transplantation. Four rabbits received oral Thalidomide and ten got placebo (powdered sugar) for thirty days. Total corneal neovascularization (NV), clock hours (CH) involved in (NV), longest (NV) pedicle length (NVP) and the duration of time required for NV to develop were assessed. RESULTS: Thalidomide significantly decreased the total neovascularization (p<0.0072), the number of (CH) involved (p<0.0002) and the longest (NVP) length (p<0.0001). There was also a significant delay in the earliest development of NV in the test group (p<0.0064). The test group retained corneal clarity significantly longer than the control group (p<0.0008). CONCLUSION: Thalidomide is an effective inhibitor of corneal angiogenesis and prolongs graft survival as measured by graft clarity in donor corneas in eyes with previous neovascularization secondary to alkali injury. CLINICAL RELEVANCE: Thalidomide may be used as a modulator of corneal angiogenesis to prolong graft survival in eyes with pre-existing corneal neovascularization.

Angiogenesis Inhibitors↗
PubMed2002

Hepatitis C virus phylogeny: a useful clinical tool.

In order to type 45 recent isolates of Hepatitis C virus (HCV) originating from four different geographic regions of the world, we performed phylogenetic analysis of a 192 nucleotides (nts) long sequence from the 5'non-coding region (5'-NCR) of the virus genome and compared them with 55 HCV isolates/strains of known type. The results of this study showed that phylogenetic studies can assign an HCV isolate to the correct type in 100% and to the correct subtype in 98%. A comparison ofthis method with other methods using commercial kits revealed that it is appropriate for clinical use and is cost effective.

Hepacivirus↗
PubMed2001

A multi-center study in order to further define the molecular basis of beta-thalassemia in Thailand, Pakistan, Sri Lanka, Mauritius, Syria, and India, and to develop a simple molecular diagnostic strategy by amplification refractory mutation system-polymerase chain reaction.

The spectrum of the beta-thalassemia mutations of Thailand, Pakistan, India, Sri Lanka, Mauritius and Syria has been further characterized by a multi-center study of 1,235 transfusion-dependent patients, and the mutations discovered used to assess the fidelity of a simple diagnostic strategy. A total of 44 beta-thalassemia mutations were identified either by allele-specific oligonucleotide hybridization, amplification with allele-specific primers, or DNA sequencing of amplified product. The results confirm and extend earlier findings for Thailand, Pakistan, India, Mauritius and Syria. This is the first detailed report of the spectrum of mutations for Sri Lanka. Two novel mutations were identified, codon 55 (-A) and IVS-I-129 (A-->C), both found in Sri Lankan patients. Two beta-thalassemia mutations were found to coexist in one beta-globin gene: Sri Lankan patients homozygous for the beta0 codon 16 (-C) frameshift were also homozygous for the beta+ codon 10 (C-->A) mutation. Studies of Sri Lankan, Pakistani, and Indian carriers suggest the codon 10 (C-->A) mutation is just a rare polymorphism on an ancestral allele, on which the beta0 codon 16 (-C) mutation has arisen. Each country was found to have only a few common mutations accounting for 70% or more of the beta-thalassemia alleles. A panel of primers to diagnose the majority of the mutations by the amplification refractory mutation system was developed, enabling a simple molecular diagnostic strategy to be introduced for each country participating in the multi-center study.

Asia↗
PubMed2001

Keratoprosthesis: an update.

Porous polytetrafluoroethylene and polyurethane skirt materials, as well as copolymers of poly (2-hydroxyethyl methacrylate), have shown promise in approaching the goal of a "biointegratable" keratoprosthesis. A novel fixation method that uses scleral haptics also has been introduced to increase stability. An all silicone device that can be sewn into position has been used successfully, temporarily, during vitreoretinal procedures. The prognosis of keratoprosthesis (KPro) procedures depends on the preoperative diagnosis: graft failure-noncicatrizing disease>ocular cicatricial pemphigoid>chemical burns>Stevens-Johnson syndrome. The likelihood of endophthalmitis after KPro surgery follows this scheme. Causative organisms tend to be gram-positive. Modified vitreoretinal techniques also have been developed, allowing successful treatment of posterior segment complications. The science of keratoprosthesis is advancing more rapidly than in previous years. However, use of KPro to address complicated corneal blindness worldwide remains limited. The authors conducted an English language literature review from January 1, 2000 to April 1, 2001 and describe advances of note in the field of keratoprosthesis design, materials, and medical and surgical management.

Biocompatible Materials↗
PubMed2001

Rearrangement of substituted propionanilides.

The rearrangements of substituted anilides of propionic acid to amino ketones in a solvent medium were studied, employing bismuth chloride as a catalyst. Rearranged compounds were then characterized by qualitative tests and spectral data.

Journal Article↗
PubMed2000

Mercury bioconcentration factors in American alligators (Alligator mississippiensis) in the Florida everglades.

Alligators inhabiting the Florida Everglades contain elevated levels of mercury within their tissues due to accumulation of mercury in the sediments. The objective of this study was to determine the mercury bioconcentration factors (BCFs) in the alligators based on mercury concentrations in the alligator tissues and mercury levels in the water column. Data from studies on mercury concentrations in the Everglades alligator tissues and water quality were used to determine the mercury bioconcentration factors. The BCFs for juvenile and adult alligators were found to be very high, with liver and kidney BCFs of 39.9x10(7) and 32.9x10(7), respectively, for adult alligators and 10.5x10(7) and 9.34x10(7) for juveniles. Adults within 7-14 years of age, living under the same conditions as juveniles who are less than 4 years of age, contain approximately 70% more mercury in their livers and kidneys and 50% more mercury in their muscle tissues.

Age Factors↗
PubMed2000

Distinct phosphoisoforms of the Xenopus Mcm4 protein regulate the function of the Mcm complex.

Initiation of DNA replication in eukaryotes requires the assembly of prereplication complexes (pre-Rcs) at the origins of replication. The assembly and function of the pre-Rcs appear to be controlled by phosphorylation events. In this study we report the detailed characterization of the cell cycle phosphorylation of one component of the Xenopus pre-Rcs, the Mcm protein complex. We show that individual Mcm subunits are differentially phosphorylated during the cell cycle. During mitosis, the Mcm4 subunit is hyperphosphorylated, while the other subunits are not actively phosphorylated. The mitotic phosphorylation of Mcm4 requires Cdc2-cyclin B and other unknown kinases. Following exit from mitosis, the Mcm4 subunit of the cytosolic interphase complex undergoes dephosphorylation, and the Mcm2, Mcm3, or Mcm6 subunits are then actively phosphorylated by kinase(s) other than cyclin-dependent kinases (Cdks) or Cdc7. The association of the Mcm complex with the pre-Rcs correlates with the formation of a transient interphase complex. This complex contains an intermediately phosphorylated Mcm4 subunit and is produced by partial dephosphorylation of the mitotic hyperphosphorylated Mcm4 protein. Complete dephosphorylation of the Mcm4 subunit inactivates the Mcm complex and prevents its binding to the chromatin. Once the Mcm complex is assembled on the chromatin the Mcm4 and the Mcm2 proteins are the only subunits phosphorylated during the activation of the pre-Rcs. These chromatin-associated phosphorylations require nuclear transport and are independent of Cdk2-cyclin E. These results suggest that the changes in Mcm4 phosphorylation regulate pre-Rc assembly and the function of the pre-Rcs on the chromatin.

Animals↗
PubMed1999

Hematopoietic colony-stimulating factors for neutropenic patients in the ICU.

OBJECTIVE: To assess whether adjunct hematopoietic colony-stimulating factor (H-CSF) accelerates neutrophil recovery and improves survival. DESIGN: A retrospective study. SETTING: Medical/surgical intensive care unit (ICU). PATIENTS: 30 neutropenic patients admitted to the ICU and treated with H-CSF. Controls were the preceding 30 neutropenic patients not treated with H-CSF. MEASUREMENTS AND RESULTS: Patient admission characteristics were reviewed. Endpoints were neutrophil recovery ( > 1.0 x 10(9)/l), length of ICU stay and survival. Depth and duration of neutropenia (0.267 +/- 0.04 x 10(9)/l for 12 +/- 1.7 days vs 0.293 +/- 0.05 x 10(9)/l for 15 +/- 1.9 days; p = 0.67 and 0.21), and the Acute Physiology and Chronic Health Evaluation II and organ system failure scores were similar. Systemic candidiasis was lower in the H-CSF group (20 vs 3 %; p > 0.05). In 11 (36.6 %) and 10 (33.3 %) patients neutrophil count recovered ( > 1.0 x 10(9)/l); H-CSF did not reduce the duration of neutropenia (7.8 +/- 1.4 vs 5.7 +/- 1.3 days; p = 0. 28), the length of ICU stay (7.8 +/- 1.1 vs 8.9 +/- 1.5 days; p = 0. 55) or improve survival (23 vs 10 %; p = 0.168). CONCLUSION: H-CSF for treatment of neutropenia in patients admitted to the ICU did not accelerate neutrophil recovery or improve survival.

APACHE↗
PubMed1999

Gallbladder ascariasis: presentation and management.

BACKGROUND: As many as 1.5 billion people around the world harbour Ascaris lumbricoides in the digestive tract. Gallbladder ascariasis, although less common than bile duct ascariasis, is quite often seen in endemic areas. METHODS: Some 1300 patients with hepatobiliary ascariasis, admitted between October 1992 and June 1998, were analysed prospectively. The clinical features and outcome of 56 cases of gallbladder ascariasis are presented. RESULTS: Forty-seven patients were diagnosed by ultrasonography and nine were diagnosed at laparotomy. Only ten patients diagnosed by ultrasonography expelled the worms spontaneously, with resolution of symptoms and signs. The remaining 37 patients underwent cholecystectomy. CONCLUSION: Gallbladder ascariasis is a significant entity in endemic areas which usually requires cholecystectomy.

Ascariasis↗
PubMed1999

Long-term effects of balloon angioplasty on systemic hypertension in adolescent and adult patients with coarctation of the aorta.

AIMS: To define the long-term effect of balloon angioplasty of aortic coarctation on hypertension, in adolescent and adult patients. METHODS: Balloon angioplasty of discrete, native aortic coarctation was performed on 50 patients (34 male) aged 23+/-8 (mean+/-standard deviation) years. In 42 of these patients cardiac catheterization and angiography were repeated 1 year later, and on the basis of sphygmomanometric blood pressure determination at that time, they were divided into 31 patients (group A) with normalized blood pressure and 11 patients (group B) who still needed antihypertensive medication. Both groups were followed annually thereafter for 12-123 (66+/-37) months. RESULTS: Coarctation gradient values before, immediately after and 1 year after angioplasty were 69+/-24 mmHg, 12+/-8 mmHg (P<0.001) and 7+/-6 mmHg. The corresponding systolic blood pressure values were 165+/-17 mmHg, 128+/-12 mmHg (P<0.001) and 115+/-10 mmHg (P<0.001) in group A; 182+/-21 mmHg, 141+/-24 mmHg (P<0.001) and 134+/-18 mmHg (P<0.001) in group B. Echocardiographic left ventricular mass index before angioplasty and at follow-up was 130+/-31 g x m-2 and 105+/-23 g x m-2 in group A; 157+/-38 g x m-2 and 132+/-35 g x m-2 in group B (P<0.001 for both comparisons). CONCLUSION: Normalization of blood pressure without medication occurred in 74% of patients after angioplasty for aortic coarctation, with subsequent long-term regression of left ventricular hypertrophy. In comparison to reported surgical results, balloon angioplasty should be considered as first line treatment for native, discrete aortic coarctation in adolescent and adult patients.

Adolescent↗
PubMed1999

Radiographic grading for knee osteoarthritis. A revised scheme that relates to alignment and deformity.

OBJECTIVE: To develop a radiographic grading scheme for osteoarthritis of the knee that would relate to arthritic progression and deformity. METHODS: The scheme of Scott, et al was revised to include new fields of Tibial Erosion and Subluxation; the fields of Tibial Osteophytes and Sclerosis were removed. The worst affected compartment only was scored on frontal Standardized Knee Images, which were used to define knee alignment variables. RESULTS: The interreader reliability (kappa = 0.92) and correlation for total scores (r = 0.94) were both excellent (p < 0.001). Individual field scores and total knee scores both correlated well with most limb alignment variables, especially the hip-knee-ankle angle (r = 0.77, p < 0.001). CONCLUSION: These findings encourage further evaluations for outcome measurement, diagnostic sensitivity, and sensitivity to define arthritic change over time.

Arthroscopy↗
PubMed1997

One- to ten-year follow-up results of balloon angioplasty of native coarctation of the aorta in adolescents and adults.

OBJECTIVES: We attempted to evaluate the role of balloon angioplasty in the treatment of discrete coarctation of the aorta in adolescents and adults, with special emphasis on long-term results. BACKGROUND: Controversy persists over the use of balloon dilation for the treatment of native coarctation of the aorta. METHODS: Between July 1986 and January 1997, 43 consecutive adolescent and adult patients with discrete coarctation of the aorta underwent balloon angioplasty. One- to 10-year follow-up data of 37 patients, including results of cardiac catheterization and magnetic resonance imaging (MRI), form the basis of this study. RESULTS: No early or late deaths occurred. Balloon angioplasty produced a reduction in the peak to peak coarctation gradient from a mean +/- SD of 69 +/- 24 mm Hg (95% confidence interval [CI] 61 to 76) to 12 +/- 8 mm Hg (95% CI 10 to 14.8) (p < 0.001). Follow-up catheterization 12 months later (37 patients) revealed a residual gradient of 6.7 +/- 6 mm Hg (95% CI 4.6 to 8.9); 3 (7%) of 43 patients had suboptimal results with development of recoarctation, defined as peak gradient >20 mm Hg, with successful repeat angioplasty. A small aneurysm developed at the site of dilation in 3 (7%) of the 43 patients. MRI follow-up data 1 to 10.8 years (mean 5.2 +/- 2.7) after angioplasty (37 patients) revealed no new aneurysm or appreciable change in the size of the preexisting aneurysm in the three patients. The blood pressure had normalized without medication in 27 (73%) of 37 patients at follow-up examination. CONCLUSIONS: Balloon angioplasty is safe and effective and should be considered a viable alternative to operation for treatment of discrete coarctation of the aorta in adolescents and adults.

Adolescent↗
PubMed1997

Antiplasmodial activity of four Kenyan medicinal plants.

A preliminary antiplasmodial and phytochemical screening of four Kenyan medicinal plants was carried out. The medicinal plants were extracted and tested for in vitro antiplasmodial activity against chloroquine-sensitive (K67) and chloroquine-resistant (ENT36) strains of Plasmodium falciparum. Out of 16 extracts, 12 were active against ENT36 strain while seven were active against K67 strain, that is, IC50 < or = 50 micrograms/ml. The most active extracts on both strains were those of leaves of Phyllanthus reticulatus Poir, and Suregada zanzibariensis Baill. (Euphorbiaceae) with IC50 < or = 10 micrograms/ml. The stembark of Terminalia spinosa Engl. (Combretaceae) and the stems of Dissotis brazzae Cogn. (Melastomataceae) had IC50 < or = 10 micrograms/ml for strains K67 and ENT36, respectively. A preliminary phytochemical analysis of these plants revealed the presence of different classes of primary and secondary metabolites.

Animals↗