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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

Syndromes with salivary dysfunction predispose to tooth wear: Case reports of congenital dysfunction of major salivary glands, Prader-Willi, congenital rubella, and Sjögren's syndromes.

Four cases-of congenital dysfunction of the major salivary glands as well as of Prader-Willi, congenital rubella, and Sjögren's syndromes-were identified in a series of 500 patients referred for excessive tooth wear. Although there was evidence of consumption of highly acidic drinks, some occlusal parafunction, and unacceptable toothbrushing habits, salivary dysfunction was the salient factor predisposing a patient to tooth wear in these syndromal cases. The 500 subjects have been characterized either as having medical conditions and medications that predispose them to xerostomia or lifestyles in which workplace- and sports-related dehydration lead to reduced salivary flow. Normal salivation, by buffering capacity, clearance by swallowing, pellicle formation, and capacity for remineralization of demineralized enamel, protects the teeth from extrinsic and intrinsic acids that initiate dental erosion. Thus, the syndromes, unrelated in many respects, underline the importance of normal salivation in the protection of teeth against tooth wear by erosion, attrition, and abrasion.

Adult↗

Investigation of cutaneous microvascular activity and flare response in patients with fibromyalgia syndrome.

OBJECTIVES: To assess microvascular activity in the skin of patients with fibromyalgia syndrome (FMS) as compared with normal controls. METHODS: Fifteen patients, who fulfilled the American College of Rheumatology criteria for FMS, and 15 age- and sex-matched healthy controls, were studied. The microvascular activity of the skin overlying the trapezius muscle was quantified using iontophoresis of acetylcholine as an endothelial-dependent vasodilator and sodium nitroprusside as an endothelial-independent vasodilator. We also studied the flare response by iontophoresing acetylcholine continuously for 10 min to stimulate a ring of nociceptor c-fibre endings in the skin. RESULTS: There was no significant difference in cutaneous vascular responses to short-duration iontophoresis of acetylcholine and sodium nitroprusside at the three different doses used. The area under the curve (AUC) (mean+/-s.e.m.) for acetylcholine baseline, 20, 40, and 80 s were 6+/-0.7, 23+/-6, 45+/-7 and 66+/-10 AU for patients and 11+/-4, 24+/-3, 49+/-7 and 62+/-12 AU for controls, respectively (P=0.2, 0.9, 0.7, 0.8, respectively). The corresponding figures for sodium nitroprusside were 5+/-1, 18+/-7, 51+/-14 and 68+/-14 AU for patients and 8+/-3, 13+/-2, 39+/-5 and 61+/-9 AU for controls, respectively (P=0.2, 0.5, 0.4, 0.7, respectively). There was also no significant difference in the flare response in patients with FMS as compared with control subjects (119+/-15 and 131+/-13 AU, respectively; P=0.57). CONCLUSION: There are no significant differences in cutaneous microvascular reactivity between patients with FMS and control subjects.

Acetylcholine↗

Cupped lesions of early onset dental erosion in young southeast Queensland adults.

BACKGROUND: Dental erosion manifests as cupped lesions on cusp apices and in fissures of teeth in patients from southeast Queensland referred with excessive tooth wear. When found in young adults, these lesions may indicate early onset of active dental erosion. If the numbers and extent of cupped lesions increase with age, erosion may be a slow cumulative process. METHODS: This cross-sectional study recorded the presence or absence and the relative sizes of cupped lesions from all cusps and occlusal fissures on premolar and permanent molar teeth from study models by image analysis. Type-specimens of cupped lesions were examined. RESULTS: The incidence by tooth reflected time in the mouth, post-tooth emergence. A linear increase in lesion number and size, with age, was found. However, cupped lesions occurred on mandibular first molar cusp apices as often, and attained greater extent, in adults under 27 years compared with older subjects. CONCLUSION: Marked differences were found between lesion number and size, between maxillary and mandibular molar sites that reflect differences in salivary protection against dental erosion. The significance of this study is that the mandibular first permanent molar indicates the age of onset and severity of dental erosion.

Adolescent↗

High prevalence of type 2 diabetes in all ethnic groups, including Europeans, in a British inner city: relative poverty, history, inactivity, or 21st century Europe?

OBJECTIVE: To compare the prevalence of type 2 diabetes in white Europeans and individuals of African-Caribbean and Pakistani descent. RESEARCH DESIGN AND METHODS: Random sampling of population-based registers in inner-city Manchester, Britain's third most impoverished area. A total of 1,318 people (25-79 years of age) were screened (minimum response 67%); 533 individuals without known diabetes underwent 2-h glucose tolerance testing, classified by 1999 World Health Organization criteria. RESULTS: More than 60% of individuals reported household annual income < pound10,000 ($15,000) per year. Energetic physical activity was rare and obesity was common. Age-standardized (35-79 years) prevalence (mean 95% CI) of known and newly detected diabetes was 20% (17-24%) in Europeans, 22% (18-26%) in African-Caribbeans, and 33% (25-41%) in Pakistanis. Minimum prevalence (assuming all individuals not tested were normoglycemic) was 11% (8-14%), 19% (15-23%), and 32% (24-40%), respectively. Marked changes in prevalence represent only small shifts in glucose distributions. Regression models showed that greater waist girth, lower height, and older age were independently related to plasma glucose levels, as was physical activity. Substituting BMI and waist-to-hip ratio revealed their powerful contribution. CONCLUSIONS: A surprisingly high prevalence of diabetes, despite expected increases with new lower criteria, was found in Europeans, as previously established in Caribbeans and Pakistanis. Lower height eliminated ethnic differences in regression models. History and relative poverty, which cosegregate with obesity and physical inactivity, are likely contributors. Whatever the causes, the implications for health services are alarming, although substantial preventive opportunities through small reversals of glucose distributions are the challenge.

Adult↗

DNA short tandem repeat profiling of three North Indian populations.

POPULATION: Fifty healthy unrelated individuals were randomly chosen from each of the three populations viz., Bhargavas, Chaturvedies, and Brahmins. Three generation pedigree charts were prepared to ensure sirname endogamy in Bhargavas Chaturvedies and group endogamy in Brahmins subjects were chosen from several parts of Uttar Pradesh, a northern state of the Indian republic.

Alleles↗

Assessment of microvascular endothelial function in human skin.

Endothelial dysfunction is an important factor in many cardiovascular diseases, and is commonly associated with impaired endothelium-mediated vasodilatation. Information about the mechanisms behind this dysfunction has come largely from animal studies or, in humans, through invasive techniques that are not specific to one vascular bed. We have developed protocols to assess endothelial function non-invasively in the cutaneous microcirculation by measuring blood flow responses to four receptor-specific vasoactive compounds. Cumulative doses of acetylcholine, methacholine, bradykinin and substance P were administered iontophoretically to the forearm skin of healthy volunteers on two to three occasions. Dose-dependent increases in skin microvascular blood flow in response to these drugs were measured with laser Doppler imaging. Vascular responses to acetylcholine and methacholine were reasonably consistent, with coefficients of variation of approx. 17%. The coefficients of variation for bradykinin and substance P were much poorer, as high as 70% for some doses. This might partly be a consequence of the more unpredictable effects of histamine release in the vasoactive behaviour of these two agonists. Although it might be advantageous to find other agonists with which to test the function of different receptor pathways, we have shown that just acetylcholine and methacholine can currently be used with iontophoresis to allow sensitive and reproducible assessment of endothelial function.

Acetylcholine↗

Alcohol-induced versus anion-induced states of alpha-chymotrypsinogen A at low pH.

Characterization of conformational transition and folding intermediates is central to the study of protein folding. We studied the effect of various alcohols (trifluoroethanol (TFE), butanol, propanol, ethanol and methanol) and salts (K(3)FeCN(6), Na(2)SO(4), KClO(4) and KCl) on the acid-induced state of alpha-chymotrypsinogen A, a predominantly beta-sheet protein, at pH 2.0 by near-UV circular dichroism (CD), far-UV CD and 1-anilinonaphthalene-8-sulfonic acid (ANS) fluorescence measurements. Addition of alcohols led to an increase in ellipticity value at 222 nm indicating the formation of alpha-helical structure. The order of effectiveness of alcohols was shown to be TFE>butanol>propanol>ethanol>methanol. ANS fluorescence data showed a decrease in fluorescence intensity on alcohol addition, suggesting burial of hydrophobic patches. The near-UV CD spectra showed disruption of tertiary structure on alcohol addition. No change in ellipticity was observed on addition of salts at pH 2.0, whereas in the presence of 2 M urea, salts were found to induce a molten globule-like state as evident from the increases in ellipticity at 222 nm and ANS fluorescence indicating exposure of hydrophobic regions of the protein. The effectiveness in inducing the molten globule-like state, i.e. both increase in ellipticity at 222 nm and increase in ANS fluorescence, followed the order K(3)FeCN(6)>Na(2)SO(4)>KClO(4)>KCl. The loss of signal in the near-UV CD spectrum on addition of alcohols indicating disordering of tertiary structure results suggested that the decrease in ANS fluorescence intensity may be attributed to the unfolding of the ANS binding sites. The results imply that the alcohol-induced state had characteristics of an unfolded structure and lies between the molten globule and the unfolded state. Characterization of such partially folded states has important implications for protein folding.

1-Propanol↗

Maternal bone lead contribution to blood lead during and after pregnancy.

We examined bone lead contribution to blood lead in a group of 311 immigrant women, 99% from Latin America, during the third trimester of pregnancy and 1 to 2 months after delivery. We measured in vivo tibia and calcaneus (heel) bone lead concentration in the postdelivery period with K shell X-ray fluorescence. Prenatal and postnatal geometric mean (range) blood lead level was 2.2 microg/dL (0.4 to 38.7) and 2.8 microg/dL (0.4 to 25.4), reflecting low current exposure. Postnatal blood lead level was significantly higher than prenatal (P<0.0001). Mean (range) tibia and calcaneus lead concentration was 6.7 microg/g (-33.7 to 62.2) and 8.4 microg/g (- 30.1 to 66.4), reflecting varying but elevated past lead exposure. Mean calcaneus lead concentration was significantly higher than mean tibia lead concentration (P = 0.055). Variance-weighted multiple regression and structural equation models showed that both calcaneus and tibia lead were directly associated with prenatal blood lead but only calcaneus lead was associated with postnatal blood lead. Increasing natural log years in the United States independently predicted decreasing calcaneus and third-trimester blood lead. The data suggest that while some exogenous lead sources and modulators of blood lead level, such as use of lead-glazed pottery and calcium in the diet, control lead exposure during and after pregnancy, endogenous lead sources from past exposure before immigration continue to influence blood lead levels in this sample.

Adolescent↗

Thrombus formation at the site of radiofrequency catheter ablation.

A 55-year-old woman with a history of resected atrial myxoma with residual patched atrial septal defect (ASD) underwent a successful radiofrequency (RF) ablation of reentry atrial tachycardia. She presented with progressive dyspnea 5 days later. Transesophageal echocardiography revealed a 1-cm right atrial mass attached to the intraatrial septum at the ablation site. Repeat study after anticoagulation for 5 weeks showed complete resolution of the thrombus. Thrombus formation at the site of RF ablation is a potential complication that may require aggressive anticoagulation. Patients with patched ASD might be at higher risk.

Catheter Ablation↗

Intestinal transplantation for short gut syndrome attributable to necrotizing enterocolitis.

BACKGROUND: Necrotizing enterocolitis (NEC) is a life-threatening condition of the neonatal age, which frequently requires surgical intervention. After extensive bowel resection, a small proportion of these patients may develop chronic short gut syndrome (SGS) and require chronic total parenteral nutrition (TPN) use. Intestinal transplantation has been performed in these patients as a life-saving option. This study reviews our experience with intestinal transplantation for SGS attributable to NEC emphasizing the mode of presentation, natural history, timing, and outcome. METHODS: A retrospective chart review was performed for all pediatric patients who underwent small bowel transplantation for NEC at the University of Miami between August 1994 and March 1999. RESULTS: Eleven transplants were performed for 10 patients with NEC (8 male and 2 female; median age: 1.75 years [range: 10 months to 10. 1 years]). Procedures performed were isolated intestinal transplants (n = 2), combined liver-intestinal transplants (n = 6), and multivisceral transplants (n = 3). All patients were born prematurely with median birth weight of 1.640 kg (range: 810 g to 2. 730 kg). They developed NEC in the first few days of life and subsequently underwent an average of 5 surgeries per patient before transplant. Transplant was indicated for liver failure in 8 patients and recurrent central line sepsis in 2 others. At present, 6 patients are alive with an overall 1-year and 3-year actuarial survival of 60% and a median follow-up of 29 months (range: 9-46 months). Six children have been weaned off TPN after a median time of 71 days (range: 19-131) from transplantation. All survivors are at home with functional grafts. CONCLUSION: Intestinal transplantation provided a reasonable outcome in patients with NEC-associated SGS who had already developed life-threatening complications related to TPN. Intestinal transplantation replaced the diseased intestine and liver, enfranchised patients from TPN, and conferred improved quality of life. These patients should be actively considered for intestinal transplantation and referred to a transplant center as soon as possible.

Child↗

Impaired skin microvascular function in children, adolescents, and young adults with type 1 diabetes.

OBJECTIVE: Vascular disease in type 1 diabetes is a complex and multifactorial process, which probably begins in childhood in association with the onset of diabetes. To determine the possible factors involved, we measured microvascular responses to endothelium-dependent (acetylcholine) and endothelium-independent (sodium nitroprusside) vasodilators in 56 patients with type 1 diabetes (aged 9-22 years) and 22 control subjects. RESEARCH DESIGN AND METHODS: Skin perfusion was measured at the dorsum of the foot using laser Doppler flowmetry during low-current iontophoresis of acetylcholine and sodium nitroprusside. Maximum vasodilator function was measured during local 44 degrees C skin heating. RESULTS: Vascular responses were significantly reduced in patients with type 1 diabetes compared with responses in control subjects: acetylcholine (P<0.01, analysis of variance [ANOVA]), sodium nitroprusside (P<0.01, ANOVA), and local heating (P<0.02. Mann-Whitney U test). Endothelium-dependent responses were related to duration of diabetes (r = -0.38, P<0.01) and to glycemic control (r = 0.37, P<0.01). Significant correlations were found in the patient group between responses to acetylcholine and sodium nitroprusside (r = 0.28, P<0.05) but not to heating, suggesting that a common factor (e.g., nitric oxide activity) may be responsible for the abnormal vascular responses to these chemicals. CONCLUSIONS: Early changes in microvascular function are present in young patients with type 1 diabetes, long before the initial clinical presentation. These abnormalities may be related to complex interactions between structural abnormalities and functional changes in the endothelium, smooth muscle, and nitric oxide activity.

Acetylcholine↗

Recommendations for water supply in arsenic mitigation: a case study from Bangladesh.

Arsenic problems have been observed in several countries around the world. The challenges of arsenic mitigation are more difficult for developing and poor countries due to resource and other limitations. Bangladesh is experiencing the worst arsenic problem in the world, as about 30 million people are possibly drinking arsenic contaminated water. Lack of knowledge has hampered the mitigation initiatives. This paper presents experience gained during an action research on water supply in arsenic mitigation in rural Singair, Bangladesh. The mitigation has been implemented there through integrated research and development of appropriate water supply options and its use through community participation. Political leaders and women played key roles in the success of the mitigation. More than one option for safe water has been developed and/or identified. The main recommendations include: integration of screening of tubewells and supply of safe water, research on technological and social aspects, community, women and local government participation, education and training of all stakeholders, immediate and appropriate use of the available knowledge, links between intermediate/immediate and long term investment, effective coordination and immediate attention by health, nutrition, agriculture, education, and other programs to this arsenic issue.

Arsenic↗

Primary Vibrio vulnificus bacteremia in a liver transplant recipient after ingestion of raw oysters: caveat emptor.

Vibrio vulnificus is responsible for severe infections in chronically ill patients. Organ transplant recipients are also at risk for severe infections due to V vulnificus. We report here the first case of V. vulnificus primary bacteremia due to raw shellfish consumption in a liver transplant recipient. All transplant patients should be cautioned against consuming uncooked seafood and warned about the risk of severe Vibrio infections from seemingly innocuous wounds acquired in a salt water environment.

Animals↗