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Biomedical subjects

F Khan

Publications and source records attributed to F Khan.

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

Angioleiomyoma: a clinical, pathological and radiological review.

Angioleiomyoma is a benign tumour arising from the vascular smooth muscle (tunica media) and presents commonly between third and fifth decades of life. Although there are sporadic reports about this tumour in the literature, none describes all the information in detail. This review is an attempt to collate all the facts in one concise article. Angioleiomyoma presents as a painful mass in approximately 60% of the cases. One of the distinct clinical feature noted is the increase in size of the swelling with physical activity of the involved part, especially in the hand. It should be considered in the differential diagnosis of painful nodular lesions of the extremity. Pre-operative diagnosis is difficult, but with a high index of suspicion and awareness, it is possible. The use of ultrasound and magnetic resonance imaging should be considered. It causes minimal morbidity and excision is usually curative. Histological examination using smooth muscle Actin stain portraits the smooth muscle bundles clearly.

Adult↗
PubMed2003

Low-risk persistent gestational trophoblastic disease treated with low-dose methotrexate: efficacy, acute and long-term effects.

The aim of this study was to evaluate the efficacy and toxicity of low-dose methotrexate with folinic acid rescue in a large series of consecutively treated patients with low-risk persistent gestational trophoblastic disease. Between January 1987 and December 2000, 250 patients were treated with intramuscular methotrexate (50 mg on alternate days 1, 3, 5, 7) with folinic acid (7.5 mg orally on alternate days 2, 4, 6, 8) rescue. The overall complete response rate without recurrence was 72% for first-line treatment and 95% for those who required second-line chemotherapy. Eight women (3.2%) had recurrence following remission and two (0.8%) had new moles. Two women (0.8%) died of their disease giving an overall cure of 99%. Only 10 women (4%) experienced grade III/IV toxicity during the first course of treatment and 13 women (5.2%) subsequently. Toxicity included mucositis and stomatitis, pleuritic chest pain, thrombocytopenia, uterine bleeding, abdominal pain, liver function changes, rash and pericardial effusion. A total of 59 women (23.6%) required second-line chemotherapy; 48 women had methotrexate resistance, eight had methotrexate toxicity and an empirical decision to change therapy was made in three. In all, 11 women (4.4%) had a hysterectomy before, during or after treatment; 141 women (56.4%) became pregnant following treatment: in 128 (90.7%), the outcome was successful. Methotrexate with folinic acid rescue is an effective treatment for low-risk persistent trophoblastic disease. It has minimal severe toxicity, excellent cure rates and does not appear to affect fertility.

Adolescent↗
PubMed2003

Mechanisms contributing to the vaso-active effects of prilocaine in human skin.

We investigated the roles of the endothelial nitric oxide and cyclo-oxygenase pathways in mediating the vasoactivity of prilocaine in the skin. We injected prilocaine 1% intradermally into forearm skin of 10 healthy, male subjects. Nitric oxide synthesis was inhibited at a second site by co-injecting prilocaine with l-NAME 1%. We then repeated the injections while blocking the cyclo-oxygenase pathway with aspirin (4 x 600 mg). We measured blood flow responses to the injections using laser Doppler imaging. We found that, after the traumatic effects of injection had subsided, l-NAME reduced the vascular response to prilocaine by a third (p = 0.012), indicating an influence specifically on the drug response. Aspirin had no effect on the response (p = 0.588). We conclude that the vasoactive effects of prilocaine in human skin are mediated partly through the release of endothelial nitric oxide and, although other mechanisms might also be involved, the cyclo-oxygenase pathway does not appear to play a role.

Adolescent↗
PubMed2003

Expression of Cpgp40/15 in Toxoplasma gondii: a surrogate system for the study of Cryptosporidium glycoprotein antigens.

Cryptosporidium parvum is a waterborne enteric coccidian that causes diarrheal disease in a wide range of hosts. Development of successful therapies is hampered by the inability to culture the parasite and the lack of a transfection system for genetic manipulation. The glycoprotein products of the Cpgp40/15 gene, gp40 and gp15, are involved in C. parvum sporozoite attachment to and invasion of host cells and, as such, may be good targets for anticryptosporidial therapies. However, the function of these antigens appears to be dependent on the presence of multiple O-linked alpha-N-acetylgalactosamine (alpha-GalNAc) determinants. A eukaryotic expression system that would produce proteins bearing glycosylation patterns similar to those found on the native C. parvum glycoproteins would greatly facilitate the molecular and functional characterization of these antigens. As a unique approach to this problem, the Cpgp40/15 gene was transiently expressed in Toxoplasma gondii, and the expressed recombinant glycoproteins were characterized. Antisera to gp40 and gp15 reacted with the surface membranes of tachyzoites expressing the Cpgp40/15 construct, and this reactivity colocalized with that of antiserum to the T. gondii surface protein SAG1. Surface membrane localization was dependent on the presence of the glycophosphatidylinositol anchor attachment site present in the gp15 coding sequence. The presence of terminal O-linked alpha-GalNAc determinants on the T. gondii recombinant gp40 was confirmed by reactivity with Helix pomatia lectin and the monoclonal antibody 4E9, which recognizes alpha-GalNAc residues, and digestion with alpha-N-acetylgalactosaminidase. In addition to appropriate localization and glycosylation, T. gondii apparently processes the gp40/15 precursor into the gp40 and gp15 component glycopolypeptides, albeit inefficiently. These results suggest that a surrogate system using T. gondii for the study of Cryptosporidium biology may be useful.

Animals↗
PubMed2003

Mechanics of patterned helical Si springs on Si substrate.

The elastic response, including the spring constant, of individual Si helical-shape submicron springs, was measured using a tip-cantilever assembly attached to a conventional atomic force microscope. The isolated, four-turn Si springs were fabricated using oblique angle deposition with substrate rotation, also known as the glancing angle deposition, on a templated Si substrate. The response of the structures was modeled using finite elements, and it was shown that the conventional formulae for the spring constant required modifications before they could be used for the loading scheme used in the present experiment.

Elasticity↗
PubMed2003

Differences in endothelial function and vascular reactivity between Scottish and Arabic populations.

BACKGROUND: The endothelium is a major organ that plays a central role in the regulation of blood flow, resists thrombus formation and maintains blood fluidity. Environmental, dietary, but also genetic factors might affect endothelial cell function and vascular activity. METHODS AND RESULTS: Endothelium-dependent and -independent vascular responses were evaluated in 42 male subjects from two different populations: 30 Scottish and 12 Arabic (transient visitors to UK) (20-41 years old). Endothelium-dependent and -independent vascular responses were measured in the forearm skin using laser Doppler imaging after iontophoresis of increasing doses of acetylcholine and sodium nitroprusside, respectively. Endothelium-dependent responses were significantly greater in Arabic subjects compared with responses in Scottish subjects (mean ACh ratio 4.9 +/- 1.2 v 3.8 +/- 1.5, respectively, P = 0.013, ANOVA). Although there was no significant difference between the groups in endothelium-independent vascular responses (mean SNP ratio 3.4 +/- 1.2 v 2.8 +/- 1.2, respectively, P = 0.26, ANOVA), there was a trend however towards a higher peak SNP response in the Arabic group (5.3 +/- 1.5 v 4.1 +/- 1.9, respectively, P = 0.019). CONCLUSIONS: These results suggest that a significant difference exists in the endothelial function and vascular reactivity between these populations. Although the reasons for these differences are not clear, they may be related to differences in life styles, tradition, food intake, environmental and genetic factors.

Acetylcholine↗
PubMed2003

Absence of factor V Leiden (G1691A) mutation, FII G20210A allele in coronary artery disease in North India.

BACKGROUND: Interaction between various genetic and environmental factors is associated with coronary artery diseases (CADs). Factor V Leiden mutation (FVL) and FII G20210A polymorphism are two recently described genetic factors with a propensity towards venous thrombosis, however, with a doubtful role in coronary artery disease and myocardial infarction. AIM: Present study was conducted to assess the relationship of both these factors in coronary artery disease in population from North India. SETTING AND DESIGN: Case control study. MATERIAL AND METHODS: Two hundred angiographically proven coronary artery disease patients were studied to examine the association of Factor V Leiden mutation and FII G20210A mutation with coronary artery disease and myocardial infarction. Out of 200 patients, 51 had myocardial infarction. Two hundred controls were selected who were from north India and were also age and sex matched. RESULTS AND CONCLUSIONS: Our results indicate that both these polymorphisms were totally absent in our population, therefore, these variants cannot be considered as independent risk factors or as a predictor for CAD. However, there is a need to confirm the above findings on patients from different populations from different parts of the country as there are reports which show that the incidence of Factor V Leiden varies from 1.3 % to 10%.

Adult↗
PubMed2002

Models for protein folding and nature's choice of protein as catalyst.

The study of protein folding and unfolding pathways lends a fascinating dimension to protein biochemistry. Several models for protein folding have been postulated. Two powerful probes used in protein folding study are far UV-CD monitored stopped flow kinetics and pulse hydrogen exchange in conjunction with NMR. The formation of molten globule, which is an intermediate possessing secondary structure but not a well packed tertiary structure, is now emerging as a common feature on the folding pathway of many proteins. The molten globule is recognized by a class of molecules called chaperones which act as accelerators of protein folding. This article ends by elucidating why proteins are Nature's choice as catalysts.

Catalysis↗
PubMed2002

Sites of dental erosion are saliva-dependent.

Acid demineralization of teeth causes occlusal erosion and attrition and associated non-carious cervical lesions at sites relatively unprotected by saliva. Associations of occlusal pathology and cervical lesions were looked for in 450 patients with toothwear, and 174 subjects with cervical lesions were identified. Associations of occlusal attrition, or erosion, or no wear, with cervical lesions at 72 buccal and lingual sites were recorded from epoxy resin replicas of the subjects' dentitions (3241 teeth). Criteria used to discriminate occlusal erosion from attrition; and shallow from grooved and wedge-shaped cervical lesions were delineated by scanning electron microscopy (SEM). In the absence of occlusal pathology, cervical lesions were very rare (<1%). In the presence of occlusal pathology, cervical lesions were present in 27.71% of buccal sites as opposed to 2.61% of lingual sites. The commonest site of cervical lesions was the facial of maxillary incisors (36% of sites). The least common site was the lingual aspect of mandibular molars (1.7% of sites). These differences may reflect the normal protective role of serous saliva and salivary pellicle in a site-specific manner, on the lingual surfaces of mandibular teeth particularly, and do not support abfraction as the prime aetiology of cervical lesions.

Adult↗
PubMed2002

Testing a model of the relationship between gender, ethnicity, clinical status and impact in older adults from minority ethnic groups.

OBJECTIVE: To identify the relationship between indicators of self-assessed symptom status, the reported impact of oral conditions and clinical indices, and the extent to which this relationship was moderated by gender and ethnicity. DESIGN: Secondary analysis of data from an oral health survey of minority ethnic groups. PARTICIPANTS: Purposive sample of 376 individuals from minority ethnic groups in the United Kingdom recruited through community groups. MEASURES: Numbers of decayed, missing and filled teeth. Measures of self assessed symptoms, and impact upon quality of life. RESULTS: Impact of oral conditions upon lifestyle was predicted by the number of missing teeth, the presence of pain on eating certain foods and the presence of toothache in the previous four weeks. Social variables (gender and ethnicity) did not predict impact either singly or through interaction with symptoms. CONCLUSIONS: The findings support a linear model of the relationship between the experience of oro-facial symptoms and impact on everyday life amongst older adults.

Black or African American↗
PubMed2002

Dental erosion in asthma: a case-control study from south east Queensland.

BACKGROUND: Asthma medication places patients at risk of dental erosion by reducing salivary protection against extrinsic or intrinsic acids. But patterns of lesions in asthmatics may differ from patterns in non-asthmatics, because gastro-oesophageal reflux (GOR) is found in 60 per cent of asthmatics. METHODS: The lesions in 44 asthma cases were compared to those of age and sex match controls with no history of asthma or medications drawn from the dental records of 423 patients referred concerning excessive tooth wear. The subjects were 70 males age range 15 to 55 years and 18 females age range 18 to 45. Anamnestic clinical data were compared between the two groups. Models of all 88 subjects were examined by light microscopy, and wear patterns were recorded on permanent central incisor, canine, premolar and first molar teeth. RESULTS: Clinical differences were a higher incidence of tooth hypersensitivity, xerostomia, salivary gland abnormalities, gastric complaints, and self induced vomiting in the cases. No differences were found between the cases and controls on citrus fruit and acid soft drink consumption. More occlusal erosion sites were found in cases, whereas more attrition sites were found in the controls. There were no significant differences in palatal erosion on maxillary anterior teeth found between cases and controls. Lingual erosion of the mandibular incisors, found only in GOR patients, was not observed. CONCLUSIONS: A higher incidence of erosion was found in asthmatics. Gastro-oesophageal reflux symptoms were not associated with the sign of lingual mandibular incisor erosion. The clinical significance is that asthmatics are at risk of dental erosion from extrinsic acid, but GOR does not appear to contribute in a site-specific manner.

Adolescent↗
PubMed2002

Evaluation of a combined laser Doppler flowmetry and iontophoresis technique for the assessment of equine cutaneous microvascular function.

A combined laser Doppler flowmetry and iontophoresis (LDFI) technique, used routinely to assess human microvascular function, was evaluated as a noninvasive technique for assessment of equine microvascular function, to facilitate the study of diseases such as laminitis. Baseline and vasoactive agonist-induced (acetylcholine and nitroprusside) microvascular flux was quantified at 2 sites (on the dorsal pastern adjacent to the coronary band and over the gluteals) in 6 clinically normal horses on 5 or 6 separate occasions under standardised conditions. Both agonists significantly increased microvascular flux. Skin pigmentation significantly attenuated the baseline flux, but not the magnitude of the agonist-mediated vasodilatory response. While LDFI was simple to perform, its value as a clinical and research tool for assessing the equine cutaneous microcirculation is limited by its poor reliability, as indicated by the marked intra- and intersubject variability in baseline and agonist-mediated microvascular flux.

Acetylcholine↗
PubMed2002

Vascular endothelial growth factor in patients with critical limb ischemia before and after amputation.

BACKGROUND: It is known that levels of vascular endothelial growth factor (VEGF) in biological fluids increase with inflammation and vascular proliferation. Theraputic angiogenesis by injection of VEGF or genes encoding for it may be a promising strategy for treatment of critical limb ischemia. However growth factors are also implicated in the development of vascular disease by smooth muscle cell proliferation. METHODS: We have previously shown VEGF levels to be increased in juvenile diabetic subjects with no clinical evidence of vascular disease. We have measured serum VEGF using an enzyme linked immunosorbent assay and cellular VEGF expression using flow cytometry in patients with critical limb ischemia prior to and 6 months postamputation to determine whether removal of the ischemic limb leads to changes in systemic endothelial cell function. RESULTS: Baseline VEGF levels were significantly increased in the patient group compared to controls with levels returning to control levels at 6 months postsurgery. Monocyte and neutrophil VEGF expression was significantly reduced in the patient group. Platelet expression of VEGF was also reduced but this failed to reach statistical significance. CONCLUSIONS: The results suggest that it may be useful to determine the balance between VEGF production and cellular receptor expression prior to treatment.

Aged↗
PubMed2001

Identification of potential diagnostic markers of prostate cancer and prostatic intraepithelial neoplasia using cDNA microarray.

The identification of novel genes or groups of genes expressed in prostate cancer may allow earlier diagnosis or more accurate staging of the disease. We describe the assembly and use of a 1877-member microarray representing cDNA clones from a range of prostate cancer stages and grades, precursor lesions and normal tissue. Using labelled cDNA from tumour samples obtained from TURP or radical prostatectomy, analysis of expression patterns identified many up-regulated transcripts. Cell lines were found to over-express fewer genes than diseased tissue samples. 17 known genes were found to over-express more than 4-fold in 4 or more cancers out of 15 cancers. Only 2 genes were over-expressed in 6 out of 15 cancers or more, whilst no genes were consistently found to be over-expressed in all cancer samples. Novel prostate cancer associations for several well characterized genes or full length cDNAs were identified, including PLRP1, JM27, human UbcM2, dynein light intermediate chain 2 and human homologue of rat sec61. Novel associations with high-grade PIN include: breast carcinoma fatty acid synthase and cDNA DKFZp434B0335. We shortlist and discuss the most significant over-expressed genes in prostate cancer and PIN, and highlight expression differences between malignant and benign samples.

Aged↗