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Biomedical subjects

F Khan

Publications and source records attributed to F Khan.

At least 19 recordsLinked to original sources
PubMed1999

Comparison of the entropy technique with two other techniques for detecting disease clustering using data from children with high blood lead levels.

The entropy technique was compared with two other case-control techniques for detecting disease clustering using data on blood lead levels of children who were patients at the King/Drew Medical Center in South-Central Los Angeles in 1991 to 1994. The other two methods are the nearest neighbor technique (NNT) and Moran's IPOP technique, a variation of Moran's I test, in which rates are adjusted for population size. Four different blood lead levels (15 microg/dl, 20 microg/dl, 30 microg/dl, 35 microg/dl) were used as cutoff levels to designate cases. Persons with blood lead levels greater than or equal to the cutoff level were designated as cases. The authors found significant clustering for all four cutoff levels using the entropy method, and for the first three cutoff levels using the NNT. They found significant clustering with Moran's IPOP for some scales for two of the cutoff levels. While performance of the entropy technique and the NNT were independent of scale, that of Moran's IPOP was highly scale-dependent.

Adolescent↗
PubMed1999

Peptide mapping and disulfide bond analysis of myeloid progenitor inhibitory chemokine and keratinocyte growth factor by matrix-assisted laser desorption ionization mass spectrometry.

Peptide mapping and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) were conducted to characterize the human genome-based recombinant proteins. Accurate mass values for the deleted forms of the myeloid progenitor inhibitory factor chemokine (MPIF-1d23), and the keratinocyte growth factor (KGF-2d33) were measured as 8848.55 +/- 0.25 and 16,175.87 +/- 0.89 Da, respectively. The mass accuracy of delayed ion extraction MALDI-MS measurements was within 20 ppm of the cDNA predicted value. Reduction and alkylation of the chemokine showed the presence of six cysteine residues and three disulfide bonds. Additional confirmation of disulfide bonding among the cysteine residues of the chemokine was demonstrated by identifying the RP-HPLC separated tryptic and endoprotease Glu-C peptides. Three methionine residues of the chemokine were identified by MALDI-MS of its cyanogen bromide (CNBr) cleavage products. The KGF-2d33 growth factor, however, lacked the disulfide bonding between the two-cysteine residues and contained two free sulfhydryl groups. Direct analysis of the growth factor CNBr digest showed 7542.99, 4993.4, and 3107.7 Da peptides, which identified the methionine residues. Peptide mapping mass spectrometry indicated that host-specific posttranslational modifications had not influenced the gene expression work.

Amino Acid Sequence↗
PubMed1999

Cadaveric small bowel/split liver transplantation in a child.

Scarcity of size-matched grafts continues to be a major limiting factor for liver and combined liver/intestinal transplants in the pediatric population. It is reported that 29% of pediatric patients listed for hepatic transplantation die while waiting for a donor. The reported mortality of pediatric patients awaiting intestinal transplantation is about 40%. We report on a technique of segmental liver and intestinal transplantation in a child. To our knowledge, this is the first report of a combined split liver-intestinal transplantation. We used a cadaveric donor, but the technique can also be performed with a live donor. The adult recipient of one segment of the liver was discharged home without complications. The child who received the combined liver intestinal graft developed intestinal perforation and severe rejection and died. If this technique is applied successfully, the adverse effects and mortality of a long pretransplant waiting period in pediatric patients may be avoided.

Adult↗
PubMed1999

Determining soil contamination profiles from intensities of capture-gamma rays using above-surface neutron sources.

Four methods are presented to estimate contaminant concentration profiles in soil from the intensities of neutron-induced capture-gamma photon intensities measured at the soil surface. In particular, the method of linear regularization with and without an iterative positivity constraint, the Backus-Gilbert method, and the maximum entropy method are applied to the soil contamination problem. Example results obtained with the four methods are given for photon intensities calculated for idealized test contaminant profiles in soil irradiated by neutron sources above the surface.

Gamma Rays↗
PubMed1999

Specialist nurse counsellor interventions at the time of diagnosis of breast cancer: comparing 'advocacy' with a conventional approach.

Over recent years, specialist breast care nurses have become increasingly recognized as core members of any breast care team within the UK. Part of the role is to support patients at the highly stressful stage of receiving a diagnosis. This paper describes an 'advocacy' style of nurse counsellor intervention which aims to improve patients' preparation for, and involvement in, the diagnostic consultation and provides a framework for future counselling support. One hundred and three women undergoing surgery following diagnosis of breast cancer or a benign breast lump were supported using either this advocacy intervention or a more conventional model of care. The aim was to identify the most effective and appropriate method of intervening at this important stage. Assessment took place before surgery, with 2-week and 6-month follow-ups, and included the Hospital Anxiety and Depression Scale, Rotterdam Symptom Check List and semi-structured interviews addressing perceived quality of care, involvement in decision-making and psycho-social functioning. Whilst the results of many measures were similar for women in the two intervention groups, qualitative data support the implementation of the advocacy method by the breast care nurse.

Adaptation, Psychological↗
PubMed1999

Five case studies of soldiers with painful clavicular fracture non-union.

We report a short case series of 5 servicemen who had sustained closed clavicular fractures, 4 of whom presented to our clinic with a painful non-union, and 1 required primary fixation for tenting of the skin. Our treatment consisted of open reduction and internal fixation of these non-unions. This resulted in all these men returning to duties with painfree shoulder girdles within 6 months. A complication in these cases was one of a prominent plate which rubbed on straps and required removal of the plate after union had occurred resulting once again in a painfree shoulder girdle and a return to full duties. We advocate early orthopaedic referral in cases of painful clavicular non-union and where appropriate, open reduction and internal fixation with the expectation of an early return to full duties with a pain free shoulder girdle.

Adult↗
PubMed1999

Impaired skin vasomotor reflexes in patients with erythromelalgia.

Erythromelalgia (EM) is a chronic disorder characterized by intermittent burning pain, warmth and erythema of the extremities. Increasing the local temperature and dependency of the affected limb(s) precipitates the symptoms, whereas direct cooling and elevation of the limb(s) can provide partial relief. Our previous findings showed that patients with EM have enhanced cutaneous vascular tone at rest and during stimulation, which may be due to an increase in sympathetic neural activity. To test this, we measured skin vasoconstrictor responses to contralateral arm cold challenge (CC) and inspiratory gasp (IG) using laser Doppler flowmetry at the toe pulp and fingertip. These areas were chosen because of their dense sympathetic innervation. An index of the vasoconstrictor response (between 0 and 1) was calculated from the change in skin perfusion from baseline following CC and IG. In control subjects, vasoconstrictor responses to CC at the toe and fingertip were both 0. 70+/-0.02 (mean+/-S.E.M.), which were significantly greater (P<0. 001) than corresponding values in patients with EM (0.37+/-0.04 and 0.45+/-0.04 respectively). Similarly, vasoconstrictor responses to IG were significantly greater (P<0.001) at the toe and fingertip in control subjects (0.70+/-0.03 and 0.70+/-0.02 respectively) compared with values in EM patients (0.27+/-0.03 and 0.45+/-0.15 respectively). These data show that, in contrast with control subjects, patients with EM have diminished sympathetic vasoconstrictor responses to both CC and IG. Denervation supersensitivity may play a part by increasing vasoconstrictor responses to circulating catecholamines, leading to a reduction in skin blood flow. Therefore an interplay between neural and vasoactive agents may be involved in the pathophysiology of EM.

Adult↗
PubMed1998

Liver transplantation with cavoportal hemitransposition in the presence of diffuse portal vein thrombosis.

BACKGROUND: Orthotopic liver transplantation is possible even in the presence of recipient portal vein thrombosis, provided that hepatopetal portal flow to the graft can be restored. On rare occasions this is not possible due to diffuse thrombosis of the portal venous system. In these cases, successful liver transplantation has been considered impossible. Portocaval transposition was introduced in the pretransplantation era to study the effect of systemic venous flow on the liver and has been used in three patients for the treatment of glycogen storage disease. We used portocaval hemitransposition (portal perfusion with inflow from the inferior vena cava) in liver transplantation when portal inflow to the graft was not feasible. We are reporting the collective experience of nine patients from four liver transplant centers. METHODS: Cavoportal hemitransposition was used in nine patients. In seven of these cases, the technique was used during the original transplant (primary group). In two cases, it was used after the portal inflow to the first transplant had clotted (secondary group). RESULTS: Five of seven patients in the primary group are alive after intervals of 6-11 months. The two patients in the rescue group died. In the successful cases, liver function and histology were indistinguishable from those of conventional liver transplantation. Ascites disappeared within 3-4 months and the patients were able to return to their normal activities. Postoperative variceal bleeding necessitated splenectomy and gastric devascularization in one case and splenic artery embolization in another case. Bleeding was controlled in both these cases. Splenectomy and gastric devascularization were performed prophylactically in one patient with a history of variceal bleeding in order to prevent this complication after transplantation. CONCLUSION: Portocaval hemitransposition maybe useful in liver transplantation when hepatopetal flow to the liver graft cannot be established by other techniques. Rescue after failure of conventional technique was not possible in two patients.

Adult↗
PubMed1998

Intraoperative donor cholangiography.

Biliary drainage has long been called the Achilles' heel of liver transplantation, and biliary complications compromise the success of liver transplantation by increasing graft loss and the rates of a required second operation, morbidity, and mortality. One cause of complications is unrecognized anomalous biliary anatomy. We examined 73 intraoperative donor duct cholangiograms (IODDCs) to assess our ability to identify biliary anomalies intraoperatively. Normal anatomy was seen in 42% (31/73); some part of the right-sided biliary system drained into the left bile duct in 22% (16/73); trifurcated systems with a single branch point for the right posterior, right anterior, and left ducts appeared in 16% (12/73); low insertion of a right segmental duct to the hepatic duct was seen in 11% (8/73); and drainage of a right segmental duct into the cystic duct or into the hepatic duct at the cystic duct origin was noted in 8% (6/73). It was believed that the last group represented a condition that dictated extra caution in biliary reconstruction. The incidence of radiographic recognition of these anomalies was more than twice the clinical recognition in our patient population, implying that many such "problem" ducts usually go unrecognized. IODDCs facilitate training of transplant fellows. Costs are low, and morbidity is nil.

Cholangiography↗
PubMed1998

Dental erosion and bruxism. A tooth wear analysis from south east Queensland.

Tooth-tissue loss from erosion and attrition from bruxism were associated findings in 104 patients with excessive toothwear from South East Queensland. Approximately one-third of these subjects had been given a diagnosis of bruxism prior to referral. After a structured interview and clinical examination, the prevailing diagnosis was tooth erosion associated with occupational or sports-related dehydration, and one-third of the subjects were provisionally classified as bruxers. Eight items of clinical history and examination, designed to differentiate bruxers from non-bruxers, were analysed retrospectively from their records. These clinical items, by which the diagnosis of bruxism might be made, segregated the subjects into three groups of equal size, 'bruxers, possible bruxers and non-bruxers,' by a notional score for bruxism. The presence of occlusal attrition or erosion on the sextants of the dentitions was determined by scanning electron microscopic criteria on epoxy resin dental casts. The incidence of attrition versus erosion was compared between the three groups. The hypothesis was that attrition would be found on more sextants of bruxers than non-bruxers. Erosion predominated in virtually all sextants in all three groups, to the virtual exclusion of attrition in the molar sextants. The exception was the mandibular anterior sextant, where more sextants in bruxers were affected by attrition. Thus extrinsic or intrinsic acid erosion was strongly associated with occlusal tooth wear found in bruxers. Conversely, tooth-wear patterns were unreliable indicators of a bruxing habit, for attrition alone was often found on acid-exposed teeth. Thus, even if a patient is suspected of having bruxism, dental erosion is more likely the cause of tooth-tissue loss than attrition, especially in the dehydrating environment of South East Queensland.

Adult↗
PubMed1998

Influence of puberty on endothelial dysfunction and oxidative stress in young patients with type 1 diabetes.

OBJECTIVE: To examine the influence of puberty on endothelial dysfunction and oxidative stress in children and young people with type 1 diabetes. RESEARCH DESIGN AND METHODS: There were 51 young patients with type 1 diabetes, including 12 prepubertal children, 16 adolescents, and 23 young adults who had no clinical diabetic angiopathy, studied; none had microalbuminuria. The three groups were matched for glycemic control, and systolic and diastolic blood pressures and cholesterol levels were not significantly different between the groups. Endothelium-dependent vasodilatation was assessed by laser Doppler flowmetry after iontophoresis of acetylcholine (ACh) to the skin of the dorsum of the right foot. Soluble E-selectin, intercellular cell adhesion molecule-1 (ICAM-1), von Willebrand factor (vWF), plasma thiol (PSH), red cell glutathione (GSH), and red cell superoxide dismutase (SOD) were measured in blood samples obtained in the early morning. RESULTS: Skin vascular responses to ACh were significantly reduced in the young adult group compared with the prepubertal group (P < 0.05, analysis of variance). The levels of soluble ICAM-1 and E-selectin were significantly higher in the adolescent group compared with the young adult group: 338 (267-415) and 89 (64-106) ng/ml (median [interquartile range]), respectively, versus 255 (222-284) and 58 (54-71) ng/ml (P < 0.01 and P < 0.005, Mann-Whitney U test). SOD levels were significantly higher in the prepubertal group at 250 (238-282) micro/ml, when compared with the adolescent, 217 (171-249) micro/ml (P < 0.04), and young adult, 217 (157-244) micro/ml (P < 0.02), groups. GSH tended to be lower in the adolescent group, 1,192 (1,047-1,367) micromol/l, when compared with the young adults, 1,286 (1,145-1,525) pmol/l, and levels of vWF tended to be higher in the adolescent group, but these failed to reach statistical significance (both P = 0.09). PSH was not different between the three groups. CONCLUSIONS: These results suggest that puberty modulates endothelial function and antioxidant mechanisms in childhood diabetes, which may have implications for therapy and intervention.

Acetylcholine↗
PubMed1998

AIDS-associated secondary lymphoma of bone: a case report with review of the literature.

Although musculoskeletal lesions are not reported as commonly as pulmonary or central nervous system abnormalities in human immunodeficiency virus (HIV)-positive individuals, a wide variety of osseous and soft-tissue changes are seen in these patients. We describe the case of a 35-year-old injection drug user with acquired immune deficiency syndrome (AIDS) who presented with diffuse adenopathy, lower extremity pain and swelling, subcutaneous nodules, and constitutional symptoms. Radiographic images showed bilateral lytic lesions of the tibia and accompanying soft-tissue masses. Biopsy of the bone and soft-tissue abnormalities established a diagnosis of Burkitt's-like non-Hodgkin's lymphoma (NHL). By recognizing the heterogeneity of AIDS-associated NHL presentations, and the potential clinical overlap between malignancy, infection, and other rheumatologic abnormalities, physicians may obtain appropriate diagnostic studies and offer treatment recommendations.

Adult↗
PubMed1997

Oral L-arginine supplementation and cutaneous vascular responses in patients with primary Raynaud's phenomenon.

OBJECTIVE: To assess the effects of oral L-arginine supplementation on cutaneous vascular responses in patients with primary Raynaud's phenomenon (RP). METHODS: Double-blind, crossover comparison of placebo versus L-arginine (8 gm/day for 28 days). Cutaneous vascular responses in the fingers were assessed during iontophoresis of acetylcholine and sodium nitroprusside, which are endothelium-dependent and endothelium-independent vasodilators. RESULTS: In comparison with control subjects, patients with primary RP had diminished endothelium-dependent and -independent vasodilatation (P < 0.05, and P < 0.005, respectively, by analysis of variance). At the 3 doses used, vascular responses to acetylcholine were reduced by 71%, 64%, and 63%, respectively, and responses to sodium nitroprusside were reduced by 67%, 73%, and 66%, respectively. L-arginine had no significant effect on cutaneous vascular responses to acetylcholine or sodium nitroprusside in control subjects or patients with primary RP. CONCLUSION: Reduced vasodilator ability in primary RP is unlikely to be due to an impairment in the L-arginine/nitric oxide pathway.

Acetylcholine↗
PubMed1997

An examination of some derivatives of S-nitroso-1-thiosugars as vasodilators.

A number of S-nitrosated compounds derived from 1-thiosugars (glucose, galactose, xylose, maltose, and lactose) have been prepared and characterized. Most of the compounds obtained were unstable either as solids or in solution. However, S-nitroso-1-thio-2,3,4,6-tetra-O-acetylglucopyranose was stable enough to examine as a vasodilator using an isolated rat tail artery model. It also proved effective in human cutaneous vascular smooth muscle relaxation when delivered transdermally.

Animals↗