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Biomedical subjects

T Hutchinson

Publications and source records attributed to T Hutchinson.

At least 19 recordsLinked to original sources
PubMed2002

Morphological sex reversal upon short-term exposure to endocrine modulators in juvenile fathead minnow (Pimephales promelas).

Indications of effects on fish endocrine system have been noted when exposed to effluents of sewage treatment plants and subsequently in the receiving surface waters. For screening purposes, the concentration of vitellogenin (VTG) in plasma is employed to detect potential exposure of fish, to (anti-)estrogenic substances. However, little is known about the variability of VTG determinations and morphological endpoints (secondary sexual characteristics) in fish under exposure conditions employing compounds with hormonal activity other than estrogens. An in vivo test system was established to study the effects of methyltestosterone (MT, a potential model androgen) and fadrozole (F, an aromatase inhibitor) as well as the combination of MT and F on juvenile, sexually undifferentiated fathead minnows (Pimephales promelas). Fish were exposed to those compounds continuously in the (nominal) microg/l range (MT, 10, 50 and 100 microg/l; F, 25, 50, 100 microg/l; MT+F, 10 microg MT per l +50 microg F per l), for 14 days (MT+F) or 21 days (MT and F) using a flow-through system. The concentration of VTG and the expression of VTG mRNA was determined using whole body homogenates in an enzyme linked immunosorbant assay (ELISA) or reverse transcription-polymerase chain reaction (RT-PCR), respectively. Exposure to MT alone led to de novo mRNA expression as well as up to a four-fold increase of VTG. F had no effect on the VTG mRNA expression and VTG protein synthesis. The combination of MT and F had no effect on VTG concentrations, however, this produced a strong masculinisation of the juvenile fish, e.g. after 13 days of exposure 100% of the fish showed typical male sex characteristics, e.g. formation of nose tubercles and pigmentation of the dorsal fin. The above findings suggest that in fish MT may be aromatised to an estrogen. F, on the other hand, inhibits testosterone aromatisation. Consequently, the combination of MT and F strongly morphologically masculinised the juvenile fathead minnows. VTG detection at the mRNA and protein level is a sensitive parameter, however, it does not provide for any information regarding the baseline "estrogenicity" of a given parent compound.

Animals↗
PubMed2002

N-acetyl beta-D-glucosaminidase is not attached to human sperm membranes through the glycosylphosphatidyl inositol (GPI)-anchor.

AIM: The mode of anchorage of N-acetyl beta-D-glucosaminidase (NAGA) on human ejaculated sperm was investigated. METHODS: Sperm plasma membrane was prepared by discontinuous sucrose gradient centrifugation from human sperm. NAGA was solubilized from these membranes by two detergents: octyl-glycoside and triton X-100. In separate studies, the release of the enzyme from the sperm membrane preparation by phosphatidylinositol specific phospholipase C (PI-PLC) was also examined. RESULTS: NAGA activity was detected on sperm membranes isolated from human ejaculates. The pattern of the enzyme solubilization by detergents indicated that the enzyme was an integral protein of sperm membrane. NAGA was not released from the sperm membranes by PI-PLC treatment. CONCLUSION: The evidence presented strongly suggests that human sperm membrane bound NAGA is not attached via the GPI anchor.

Acetylglucosaminidase↗
PubMed2001

Postmortem biochemical markers of experimentally induced hypomagnesaemic tetany in cattle.

Severe hypomagnesaemia and tetany were induced in 10 lactating cows by feeding them semi-synthetic low magnesium diets and the animals were used to study the stability of postmortem markers of hypomagnesaemic tetany. There were significant relationships between the concentrations of magnesium in either cerebrospinal fluid (CSF) or plasma and either aqueous or vitreous humour. The onset of hypomagnesamic tetany was also associated with low magnesium concentrations in plasma, CSF and aqueous and vitreous humour. Magnesium concentrations less than 0.25 mmol/litre in fresh aqueous humour may be indicative of severe hypomagnesaemia and possible tetany in lactating cows, but the concentration of magnesium in aqueous humour was unstable postmortem. The concentration of magnesium in vitreous humour was relatively stable and a concentration of less than 0.55 mmol/litre could be used as a diagnostic marker of tetany in cattle for up to at least 48 hours postmortem, at ambient temperatures typical of Northern Ireland.

Animals↗
PubMed2001

Postmortem biochemical markers of experimentally induced hypomagnesaemic tetany in sheep.

Hypomagnesaemic tetany was induced in non-lactating and lactating ewes by feeding them semi-synthetic low magnesium diets containing additional potassium chloride and citric acid. Aqueous and vitreous humour were sampled from one eye at the time of death (fresh) and from the second eye after the head had been stored at ambient temperature for 24 hours (24-hour). There were significant relationships between the concentrations of magnesium in cerebrospinal fluid and plasma and its concentrations in fresh aqueous humour and fresh vitreous humour. Magnesium concentrations of < 0.33 mmol/litre in fresh aqueous humour and < 0.50 mmol/litre in 24-hour aqueous humour were associated with severe hypomagnesaemia and tetany. However, the concentration of magnesium in aqueous humour is relatively unstable and, unless the time of death was known accurately, its interpretation would be difficult. Magnesium concentrations of < 0.60 mmol/litre in fresh vitreous humour and < 0.65 mmol/litre in 24-hour vitreous humour were associated with severe hypomagnesaemia and tetany in adult sheep. The concentration of magnesium in vitreous humour was relatively stable for up to 48 hours postmortem.

Animals↗
PubMed2001

A randomized, double-blind comparison of the efficacy and tolerability of once-daily modified-release diltiazem capsules with once-daily amlodipine tablets in patients with stable angina.

A randomized, double-blind, parallel-group study comparing the efficacy and tolerability of once-daily diltiazem capsules with amlodipine tablets in patients with stable angina. After a run-in period of 1 to 3 weeks, 34 patients received once-daily diltiazem and 33 patients received amlodipine. Patients received either diltiazem, 240 mg/day, or amlodipine, 5 mg/day, for 2 weeks followed by diltiazem, 360 mg/day, or amlodipine, 10 mg/day, for 2 weeks. Standard treadmill exercise testing was the primary efficacy assessment. Patients also recorded incidence of angina attacks and use of glyceryl trinitrate spray. Both treatments gave significant improvement in time to onset of angina and time to maximal exercise. With the exception of amlodipine, 5 mg/day, both treatments gave significant increases in time to 1-mm ST segment depression. Diltiazem, 360 mg/day, gave a significant decrease in rate pressure product. There were no significant treatment differences in any of the exercise test parameters. Both treatments reduced incidence of angina attacks and use of glyceryl trinitrate spray. The incidence of edema was significantly less in patients receiving diltiazem. In conclusion, both treatments were effective in controlling patients' angina, but diltiazem was better tolerated, with a lower incidence of edema.

Adult↗
PubMed2000

Effects of 17 days bedrest on the maximal voluntary isometric torque and neuromuscular activation of the plantar and dorsal flexors of the ankle.

Maximal voluntary isometric torque values of the ankle plantar (Tim,PF) and dorsal flexors (Tim,DF) were assessed in eight healthy adult males at 5 degrees and 15 degrees of dorsal flexion (DF) and at 5 degrees, 15 degrees and 25 degrees of plantar flexion (PF) with the knee at right angles, before (two times), during (three times) and after (three times) 17 days of 6 degrees head-down tilt bedrest (BR). Integrated electromyograms (iEMG) were also recorded from the gastrocnemius medialis and tibialis anterior. Tim,PF and the iEMG of the gastrocnemius medialis were significantly larger (by 14% and by 27%, respectively) at the end of recovery than before BR. This was probably the consequence of training and/or habituation leading to: (1) increased activation of the plantar flexors; and (2) decreased co-activation of the antagonist muscles. Neither Tim,DF nor the tibialis anterior iEMG changed significantly. The effects of BR on muscle performance were evaluated as follows. The net torque generated by a given muscle group was assumed to be the algebraic sum of the torque generated by the agonists and by the antagonists. Thus, for the plantar flexors Tim,PF = alpha iEMGGm - beta iEMGTa, where: (1) iEMGGm and iEMGTa are the iEMGs of gastrocnemius medialis and of tibialis anterior during maximal PF; and (2) the constants alpha and beta represent the electromechanical coupling of the plantar (alpha) and dorsal (beta) flexors. Similarly for the dorsal flexors: Tim,DF = beta iEMGTa - alpha iEMGGm, where iEMGTa and iEMGGm are the iEMGs of tibialis anterior and gastrocnemius medialis during maximal DF. Torque and iEMG values were assessed for all subjects under all experimental conditions. Thus, since the biomechanical leverage of the system was constant, alpha and beta could be calculated. During BR, alpha decreased by 25% and it dropped by a further 30% during recovery. In contrast, beta remained almost unchanged. This suggests that, in spite of training and/or habituation, BR significantly impaired the maximal isometric performance of the plantar flexors, an effect that continued during the initial 10 days of recovery.

Adult↗
PubMed1998

What is the role of radiation-chemotherapy in the radical non-surgical management of carcinoma of the oesophagus? Upper GI Cancer Working Party of the UK Medical Research Council.

The optimal radical non-surgical management of carcinoma of the oesophagus has yet to be determined. The combination of high-dose radiotherapy with chemotherapy is being explored, particularly in North America. The MRC Upper GI Working Party has debated the areas where there is scientific uncertainty and which clinical trials may be appropriate to undertake in the UK.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

A phase II trial of epirubicin plus paclitaxel in metastatic breast cancer. United Kingdom Coordinating Committee for Cancer Research Breast Cancer Sub-Committee.

Epirubicin and paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) is an active combination for the treatment of metastatic breast cancer. A multicenter pilot phase II trial evaluated this combination in 35 patients treated with epirubicin 75 mg/m2 given as a 1-hour infusion, immediately followed by paclitaxel 200 mg/m2 given as a 3-hour infusion every 3 weeks. All patients had metastatic disease and had received a maximum of one chemotherapy regimen for advanced disease. A 43% response rate was observed in 30 evaluable patients, with two complete responses (7%) and 11 partial responses (37%). All patients were evaluable for toxicity. Hematologic toxicity was common and dose limiting. All patients underwent blood counts three times weekly. Grade 4 neutropenia was extremely common (91%), occurring at approximately days 10 to 12 and resolving rapidly in most cases. Thrombocytopenia was rare. Dose reductions were necessary in 10 patients, primarily for myelosuppression, but due to neuropathy in two patients. Alopecia was universal. Cardiac function was measured in all patients every two cycles. Among the first 24 evaluable patients, left ventricular ejection fraction decreased to below 40% in three patients, all of whom had received prior anthracyclines. Treatment was discontinued in one patient, who experienced no further deterioration. Under the auspices of the United Kingdom Coordinating Committee for Cancer Research, a randomized phase III study has been initiated in the United Kingdom to compare this combination of epirubicin/paclitaxel with combination epirubicin/cyclophosphamide. The primary end point of this study is progression-free survival, and the intention is to recruit 350 to 700 patients over the next 2 years.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Exercise thermoregulation after 6 h of chair rest, 6 degrees head-down bed-rest, and water immersion deconditioning in men.

The purpose was to investigate the mechanism for the excessive exercise hyperthermia following deconditioning (reduction of physical fitness). Rectal (Tre) and mean skin (Tsk) temperatures and thermoregulatory responses were measured in six men [mean (SD) age, 32 (6) years; mass, 78.26 (5.80) kg; surface area, 1.95 (0.11) m2; maximum oxygen uptake (VO2max), 48 (6) ml.min-1.kg-1; whilst supine in air at dry bulb temperature 23.2 (0.6) degree C, relative humidity 31.1 (11.1)% and air speed 5.6 (0.1) m.min-1] during 70 min of leg cycle exercise [51 (4)% VO2max] in ambulatory control (AC), or following 6 h of chair rest (CR), 6 degree head-down bed rest (BR), and 20 degree (WI20) and 80 degree (WI80) foot-down water immersion [water temperature, 35.0 (0.1) degree C]. Compared with the AC exercise delta Tre [mean (SD) 0.77 (0.13) degree C (*P < 0.05), after WI80 0.96 (0.13) degree C*, and after WI20 1.03 (0.09) degree C*. All Tsk responded similarly to exercise: they decreased (NS) by 0.5-0.7 degree C in minutes 4-8 and equilibrated at +0.1 to +0.5 degree C at 60-70. Skin heat conductance was not different among the five conditions (range = 147-159 kJ.m-2.h-1.degree C-1). Results from an intercorrelation matrix suggested that total body sweat rate was more closely related to Tre at 70 min (Tre70) than limb sweat rate or blood flow. Only 36% of the variability in Tre70 could be accounted for by total sweating, and less than 10% from total body dehydration. It would appear that multiple factors are involved which may include change in sensitivity of thermo- and osmoreceptors.

Adult↗
PubMed1990

The use of biomarkers in the prediction of survival in patients with pulmonary carcinoma.

Data on ten variables and 16 biomarkers were obtained on 119 patients with newly diagnosed pulmonary cancer. The prognostic value of 16 biomarkers (alpha-1-antitrypsin [AAT], adrenocorticotropic hormone [ACTH], alpha-fetoprotein [AFP], carcinoembryonic antigen [CEA], human chorionic gonadotropin [HCG], immune complexes, immunoglobulins, N-terminal peptide of proopiomelanocortin [NTERM], and tumor-associated antibody [TAA]) was tested by adding these to the model of age, gender, stage, morphology, Feinstein's classification of symptoms, Karnofsky scale, leukocyte count, recent weight loss, and liver enzymes. Using Cox's regression method and a forward stepwise procedure, seven biomarkers (ACTH, AAT, AFP, calcitonin, HCG, TAA, and prolactin) entered the model. Elevated levels of cortisol and TAA were associated with longer survival. The selection of biomarkers by stepwise regression needs to be interpreted with caution, especially since the Z scores were found to be dependent on the particular variables included in the model. Furthermore, when dichotomized on maximum of the normal laboratory values, HCG and AFP were infrequently (2%) elevated. The lack of correlation among the biomarkers supports the hypothesis of random derepression of the genome of cancer cells. Further studies in improved modeling and the formulation of a biomarker index could enhance our understanding of the biology of cancer.

Adenocarcinoma↗
PubMed1989

Management of childhood haematogenous osteomyelitis in a rural Papua New Guinean hospital.

Haematogenous osteomyelitis, especially in its more common chronic stage, is an important cause of morbidity in children in the Southern Highlands Province. Hospital stays are lengthy and the incidence of fractures is high. While awaiting, or in the absence of, culture and sensitivity results, cloxacillin 200 mg/kg/day plus probenecid 40 mg/kg/day is an appropriate first choice antibiotic when it is available. Antibiotic therapy in chronic disease should be limited to the specific settings of associated soft tissue infection; pre- and post-sequestrectomy; and radiological signs of ongoing bone necrosis and systemic signs of active infection. Surgical drainage of subperiosteal pus and possibly the medullary canal is required in all but the very early (less than 48 hours) cases of acute osteomyelitis that sometimes respond to antibiotics alone. Sequestrectomy should be reserved for cases where a sequestrum and adequate involucrum can be seen on X-ray. Effective management of this disease is possible only if ongoing communication exists between hospital-based medical staff and the staff of health centres or subcentres, including the network of aid post orderlies and their supervisors. Since the majority of patients present to facilities other than hospitals, any campaign directed at improving management must involve co-workers in rural areas, namely the health extension officer, nurse and aid post orderly. Only in this way can we hope to achieve earlier appropriate treatment and more systematic long-term follow-up.

Adolescent↗
PubMed1988

Sporadic aluminum osteomalacia: identification of patients at risk.

Chronic dialysis patients at risk for aluminum osteomalacia in areas of low water-aluminum content are not well identified. We, therefore, studied retrospectively a cohort of 59 patients who underwent bone biopsy at two hospital-based dialysis centers in Montreal (water aluminum content less than 10 micrograms/L). Overall, 25% of patients biopsied had aluminum-related osteomalacia defined by aluminum staining of more than 30% of the trabecular surface and low levels of bone formation as measured by tetracycline labeling. Multiple linear regression analysis showed high predialysis serum creatinine (P less than .05) and the amount of aluminum prescribed per month (P less than .05) as the most important determinants of aluminum staining. We conclude that aluminum-related osteomalacia can be a frequent disease entity in areas of low water-aluminum content. Our findings also suggest predialysis serum creatinine and the amount of aluminum prescribed per month are risk factors for the development of aluminum-related osteomalacia. Though the relationship between serum creatinine and aluminum staining of trabecular bone is unclear, serum creatinine is probably a marker for adequacy of dialysis in these patients.

Aluminum↗