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Biomedical subjects

A Webb

Publications and source records attributed to A Webb.

At least 109 records · Page 6Linked to original sources
PubMed1993

Dopexamine hydrochloride maintains portal blood flow and attenuates hepatic ultrastructural changes in a porcine peritonitis model of multiple system organ failure.

Fifteen anesthetised pigs (25-30 kg) were divided into three equal groups, sham, dopexamine (D) (10 micrograms/kg/min), and placebo (P). Sepsis was induced by fecal peritonitis in the D and P groups and colloid was infused to try to maintain mean arterial blood pressure (MABP) at a constant value and the hemodynamics measured at baseline and hourly for 8 hr. There was an initial increase in MABP and systemic vascular resistance (SVR) in the P group but not the dopexamine (D) group. Cardiac output (CO) in the P group showed a small decline but increased in the D group. The portal blood flow (PVF) in the P group fell with MABP but increased in the D group as MABP fell. The sham group showed normal ultrastructure and cellular integrity. Occlusion of the hepatic sinusoids was similar in the D and P groups. There was a greater area of Kupffer cells and endothelial cells in the P group, suggesting a greater inflammatory reaction than was found in the D group. Ultrastructure and mitochondrial integrity was better maintained in the D group. Dopexamine hydrochloride infusion maintained CO, increased PVF, and attenuated hepatic ultrastructural changes compared to placebo in a porcine fecal peritonitis model of multisystem organ failure.

Animals↗
PubMed1992

Level of cancer pain knowledge among baccalaureate student nurses.

Inadequate nursing education is a major impediment to effective pain relief for cancer patients throughout the world. This study was conducted to identify the level of cancer pain knowledge among baccalaureate student nurses and to determine whether specific activities affect this level of knowledge. Two questionnaires were administered to 82 baccalaureate student nurses in the final course of their program. Although the students displayed a realistic perspective about the severity and prevalence of cancer pain and psychological dependence, specific knowledge deficits and negative attitudes suggest the possibility of inadequate pain management. Specifically, the students believed that (a) maximal analgesic therapy should be delayed until the patient's prognosis was less than 12 months; (b) the proportion of patients whose pain can be controlled by appropriate therapy is less than is possible; (c) increasing pain is related to tolerance rather than to progression of the disease; (d) the preferred route of administration is intravenous rather than oral; and (e) the degree of respiratory depression, rather than constipation, does not decrease with repeated administration. Significant positive correlations (P < or = 0.05) were found between age and cancer pain knowledge and between attendance at seminars/workshops and time spent reading professional journal articles. Of the 30% of the participants who perceived a particular person to be a source for obtaining information about cancer pain management, 52% specified a practicing registered nurse. Seminars and workshops were chosen by 59% of the students as the most effective way for nurses to increase their knowledge.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Goal directed therapy with dobutamine in a porcine model of septic shock: effects on systemic and renal oxygen transport.

Systemic and renal haemodynamic and functional indices were measured in 15 anaesthetised pigs during systemic sepsis induced by faecal peritonitis. Five animals were assigned to maintenance of cardiac output (CO) at baseline, pre-infection values throughout the study (controls n = 5). In the remaining 10 animals, CO was increased by 25% prior to induction of sepsis and maintained at this level for the duration of the study using volume expansion with intravenous colloid and an infusion of either 20 micrograms/kg/min dobutamine (n = 5) or placebo (n = 5). Hourly measurements were made of CO, left renal blood flow, arterial and renal venous oxygen saturation, urine output, creatinine clearance and arterial partial pressure of oxygen until the animal died or until termination 8 h. Systemic indices of oxygen transport did not reflect the behaviour of the renal vascular bed during the management of sepsis. In the dobutamine group systemic oxygen uptake (VO2) increased from 173 +/- 30 to 277 +/- 73 ml/min (P less than 0.05), however this resulted in a decrease in renal DO2 (20 +/- 9 to 10 +/- 2 ml/min P less than 0.05) and there was no equivalent rise in renal VO2 (3.3 +/- 1.6 to 3.2 +/- 1.5 ml/min). There was however no significant difference in the effect on renal function of the three management protocols. Agents used to increase cardiac output during systemic sepsis may result in significantly different effects on the renal vascular bed which are not revealed by the measurement of systemic indices alone.

Animals↗
PubMed1988

Quantitative autofluorescence in the ovine and canine ocular fundus in ceroid-lipofuscinosis (Batten's disease).

Yellow-green autofluorescence was quantified in the fundi of sheep and dogs with ceroid-lipofuscinosis, using a modified photographic slit-lamp microscope with motorized scanning probe, a photomultiplier system and a digital radiometer. In age-matched controls, no fluorescence was detected. The technique should prove useful as a clinical aid in the early differential diagnosis of this disease and in the basic study of aging.

Aging↗
PubMed1988

Comparison of free alpha-tocopherol and alpha-tocopheryl acetate as sources of vitamin E in rats and humans.

The uptake of alpha-tocopherol from 2R,4'R,8'R-alpha-tocopherol and 2R, 4'R, 8'R-alpha-tocopheryl acetate has been compared in rats and humans. The two forms of vitamin E were compared simultaneously in each subject (rat and human) by using a combination of deuterium-substitution and gas chromatography-mass spectrometry (GC-MS) to distinguish and measure the competitive uptake of alpha-tocopherol from an orally ingested mixture of the acetate and the free phenol forms. When rats were dosed in a manner analogous to that used in traditional bioassays, i.e., providing the two forms of vitamin E once daily in tocopherol-stripped corn oil for four successive days immediately prior to sacrifice, the net uptake of alpha-tocopherol from the free phenol form was only half that from the acetate. This result is consistent with the greater activity of the acetate that had been observed previously in bioassays. However, when the two forms of tocopherol were intubated into rats as a single dose mixed in with an aqueous bolus of standard laboratory diet, the amount of alpha-tocopherol taken up from the free form after 24 hr was very similar to that derived from the acetate. In five adult humans, competitive uptake studies of the two forms after a single dose taken with a meal showed that the amount of alpha-tocopherol from the free phenol form was equal to that from the acetate in plasma and red blood cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Radioimmunoassay of detirelix ([ N-Ac-D-Nal(2)1,D-p-Cl-Phe2,D-Trp3, D-hArg(Et)6(2),D-Ala10]-luteinizing hormone-releasing hormone) in plasma or serum.

A procedure for the radioimmunoassay (RIA) of detirelix in plasma or serum at concentrations as low as 0.15 ng/ml is described. Antiserum was produced by deacetylation of the N-terminus amino groups of detirelix and coupling this analog to bovine serum albumin with a carbodiimide and immunizing rabbits with the resultant conjugate. For RIA, 125I-labeled detirelix was used as the tracer and a double antibody procedure was used to separate the free and bound fractions. No purification of samples was required prior to RIA. Accuracy of the method was assessed by adding known quantities of detirelix to detirelix-free plasma and determining the ratio of measured to added analyte. Linear regression analysis for the concentration range 0.15-150.0 ng/ml yielded a regression equation of y = 0.88 X +1.46 and a correlation coefficient of 0.996. Additional validation was obtained from an in vivo study in which [14C]detirelix was administered to monkeys and plasma clearance profiles were determined by RIA and an HPLC-radiochemical method. The RIA results were in good agreement with those obtained by the HPLC method.

Animals↗
PubMed1988

Bone histomorphometry and structure in corticosteroid treated chronic active hepatitis.

Transiliac biopsies from 34 female patients with corticosteroid treated chronic active hepatitis have been examined to determine the contributions made by decreased bone formation and increased bone resorption to bone loss associated with this condition and to determine the structural basis of the bone loss. Mean wall thickness was significantly reduced when compared with control values (p less than 0.001) as was the bone formation rate at tissue (p less than 0.005) and basic multicellular unit (p less than 0.005) level. The osteoid maturation period and the bone formation period were significantly prolonged (p less than 0.02 and 0.05). The total resorption surfaces were significantly increased (p less than 0.02) but the mean interstitial bone thickness was normal. The mean trabecular plate thickness was significantly reduced (p less than 0.005). These findings indicate that decreased bone formation plays a major role in bone loss associated with corticosteroid treated chronic active hepatitis and that the structural basis of bone loss is trabecular thinning.

Adult↗
PubMed1988

Pulmonary infection with Nocardia caviae in a patient with diabetes mellitus and liver cirrhosis.

The first reported case of pulmonary infection with Nocardia caviae in Britain occurred in a 67 year old woman, in whom diabetes mellitus and liver cirrhosis probably contributed to impaired cell mediated immunity. She was successfully treated with gentamicin 60 mg eight hourly and sulphadimidine 500 mg six hourly for six months and then with sulphadimidine 2 g/day for a further three months. When Nocardia caviae is isolated from the sputum of a patient with chronic respiratory infection and fever, effective treatment should be started promptly.

Aged↗
PubMed1988

Globin genes are useful markers to identify genetic similarities between Fijians and Pacific Islanders from Polynesia and Melanesia.

DNA mapping studies in Fijians have enabled the identification of rearrangements and RFLPs involving the alpha-, zeta-, and gamma-globin genes. Comparisons of these data with corresponding gene markers in Polynesians and Melanesians of Papua New Guinea show considerable overlap between the three population groups. The utility of globin genes as population markers is further confirmed.

Adult↗
PubMed1987

Biokinetics of and discrimination between dietary RRR- and SRR-alpha-tocopherols in the male rat.

The net rates of uptake of the natural (2R,4'R,8'R) diastereoisomer of alpha-tocopherol (alpha-T) and the biodiscrimination relative to its 2S-epimer (2S,4'R,8'R) have been measured, in two experiments, for the blood and 21 tissues of male Sprague-Dawley rats fed over a period of several months diets containing deuterium-substituted forms of the alpha-T acetates. Gas chromatography-mass spectrometry was used to measure the amount of deuterated tocopherols taken up relative to the amount of nondeuterated tocopherol remaining. The measurements were performed at different times after the rats, placed for one month on a basal diet containing nondeuterated, natural alpha-T acetate, were switched to a diet containing the same total quantity of deuterated forms of either natural alpha-T acetate or a mixture of the acetates of the 2R- and 2S-epimers (i.e., ambo-alpha-T acetate). In experiment 1 the source of vitamin E in the replacement diet was trideuterio-2R,4'R,8'R-alpha-T acetate. The data obtained provide the first direct measure of the rate at which natural vitamin E is replaced and augmented in the tissues of growing animals under normal laboratory dietary conditions. There are dramatic differences in the tissue kinetics; for example, the apparent half-life of vitamin E, i.e., the time at which the total amount of ingested trideuterio-alpha-T taken up is the same as the amount of nondeuterated alpha-T remaining, varies from ca. 1 wk for the lung to ca. 11 wk for the spinal cord. In experiment 2 the vitamin E in the replacement diet was an equimolar mixture of trideuterio-2S,4'R,8'R- and hexadeuterio-2R,4'R,8'R-alpha-T acetates. The results show that there is a preferential uptake of the natural diastereoisomer of alpha-T by all tissues (except the liver during the first month). Examination of fecal material reveals that the biodiscrimination begins in the gut; the incomplete hydrolysis of the acetates shows clearly that this reaction proceeds to a greater extent with the natural diastereoisomer. The greatest discrimination of all the tissues examined was found to occur in the brain. After five months, the level of the deuterated natural diastereoisomer was more than five times that of the deuterated 2S-epimer. These results have potential implications for human nutrition.

Animals↗
PubMed1986

Lipid peroxidation in regenerating rat liver.

Rats entrained to a strictly regulated lighting and feeding schedule have been subjected to partial hepatectomy or a sham operation. In the partially hepatectomised animals the period of liver regeneration is characterised by regular bursts of thymidine kinase activity. Liver microsomes from rats, at times corresponding to maximum thymidine kinase activity, have much reduced rates of lipid peroxidation compared to control preparations: this is due in part to increased levels of lipid-soluble antioxidant at times of maximal DNA synthesis. This temporal relationship between thymidine kinase and lipid peroxidation is consistent with the view that lipid peroxidation is decreased prior to cell division.

Animals↗
PubMed1986

Vitamin E in young and old human red blood cells .

Young and old human red blood cells contain about the same amount of alpha-tocopherol, a compound which has previously been shown to be the major lipid-soluble, chain-breaking antioxidant present in such cells. Since red blood cells lose up to ca. 20% of lipid material from their membrane as they age, the alpha-tocopherol/membrane-lipid ratio actually rises with age rather than declining as might have been expected on the basis of the free radical theory of aging. The alpha-tocopherol/arachidonic acid moiety ratios increase in the order: young red blood cells less than old red blood cells less than plasma, which argues against the suggested membrane stabilizing effect of alpha-tocopherol/arachidonic acid moiety complexes.

Adult↗
PubMed1986

Physical and hormonal evaluation of transsexual patients: a longitudinal study.

The physical and hormonal characteristics of 60 male-to-female transsexuals and 30 female-to-male transsexuals were measured before or during treatment with commonly used forms and dosages of hormones. Only two patients (both female-to-male) had either a congenital defect in hormonal production or abnormal genital development. Patients were seen at 3- to 6-month intervals for an average of 18 months. The response to therapy was examined over time; physical parameters, hormonal concentrations, liver function tests, lipids, and glucose were measured. Three patients were changed from ethinyl estradiol to conjugated estrogen because of liver enzyme elevations. Ethinyl estradiol (0.1-0.5 mg/day) was equal to conjugated estrogen (7.5-10 mg/day) in its ability to suppress testosterone and gonadotropins and to promote breast growth. Maximum breast growth required 2 years of therapy. During treatment with testosterone, female-to-male transsexuals had a significant mild elevation of cholesterol and triglyceride. The female-to-male transsexuals receiving testosterone cypionate, 200 mg every 2 weeks, ceased to have menstrual periods and became progressively masculinized. A mean maximal clitoral length of 4.6 cm which achieved by 1 year of therapy. Based on the data generated by this study, we recommend as hormonal therapy 0.1-0.5 mg/day of ethinyl estradiol or 7.5-10 mg/day of conjugated estrogen for male-to-female transsexuals, and intramuscular testosterone cypionate, 200 mg every 2 weeks, for female-to-male transsexuals.

Adolescent↗
PubMed1986

Lack of osteomalacia in chronic cholestatic liver disease.

Assessment of osteomalacia using rigorous histologic definition was carried out in 36 unselected patients with chronic cholestatic liver disease, 33 with primary biliary cirrhosis, and 3 with primary sclerosing cholangitis. Disease duration varied from 1 to 11 years. The mean values for total trabecular bone volume, osteoid volume, osteoid surface, and mineralization appositional rate were all decreased when compared to age-matched and sex-matched controls. There was a highly significant decrease in the mean osteoid seam width in both females (P = 0.001) and males (P = 0.02), and a significant prolongation of the mineralization lag time was found in females (P = 0.05), but failed to reach significance in males. These results excluded osteomalacia but were more indicative of osteoporosis. Biochemical evidence of osteomalacia was also absent, with serum calcium, serum phosphorus, and mean 25-hydroxyvitamin D levels not significantly different from control values, although there was a nonsignificant decrease in the mean value of 25-hydroxyvitamin D in patients with elevated serum bilirubin levels, and all patients with levels below 20 nmol/L had avoided sunlight exposure. The present results suggest that osteoporosis is the major type of metabolic bone disease in patients with chronic cholestatic liver disease.

Adult↗
PubMed1985

A mild, rapid, and efficient method of lipid extraction for use in determining vitamin E/lipid ratios.

A new, general method for lipid extraction and measurement of vitamin E/total lipid ratios in tissue and cell samples has been developed. The new extraction procedure uses a combination of sodium dodecylsulfate, ethanol and n-heptane, and is mild, clean, convenient, efficient and rapid (less than or equal to 5 min). The efficiency of the new method has been confirmed for human plasma, red blood cells and rat liver homogenate by the comparison of the yields of vitamin E, O-acyl lipid and cholesterol with the yields obtained following conventional extraction procedures. Extraction efficiency also has been confirmed for multilamellar vesicles composed of known quantities of vitamin E, egg lecithin and cholesterol.

Animals↗
PubMed1985

Relationship between toluidine blue-stained calcification fronts and tetracycline-labeled surfaces in normal human iliac crest biopsies.

The relationship between toluidine blue-stained calcification fronts and tetracycline labeling was examined in iliac crest biopsies from 56 normal subjects aged 19-80 years, all of whom had received double tetracycline labeling. Sections were quantitated using an eye-piece graticule and all values were expressed as a percentage of osteoid surface. Values for double plus single tetracycline-labeled surfaces were lower than those obtained for toluidine blue-stained calcification fronts in 66% of subjects, although the difference between the two measurements was not statistically significant. Values obtained for calcification fronts demonstrated by toluidine blue staining were significantly greater than those obtained for single, double, and double plus half single tetracycline-labeled surfaces. No significant correlation could be demonstrated between toluidine blue-stained calcification and tetracycline-labeled surfaces. In conclusion, the fraction of osteoid bearing a tetracycline label differed from that showing a toluidine blue-stained calcification front and no correlation could be demonstrated between the two measurements. These differences may arise from methodological problems associated with their demonstration and identification; alternatively their lack of similarity might reflect uptake of stain and tetracycline at different sites within the calcification front. Which of the two parameters most accurately represents the active mineralizing surface is unknown.

Adult↗