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Biomedical subjects

J Brown

Publications and source records attributed to J Brown.

At least 811 records · Page 45Linked to original sources
PubMed1987

Successful pregnancies from cryopreserved human embryos produced by in vitro fertilization.

Sixty-three embryos produced after in vitro fertilization in 30 infertile couples were frozen and stored. Dimethylsulfoxide was used as a cryoprotectant and embryos were frozen from the two-cell stage to early blastocyst development. Replacement occurred during spontaneous ovulatory cycles 2 to 15 months after embryo freezing. Embryo replacement was performed 3 to 6 days following identification of the luteinizing hormone surge in the spontaneous cycle. Thirty-five embryos were replaced into 25 women and two viable pregnancies resulted.

Adult↗
PubMed1987

Altered glucagon release in biotin deficiency.

Classical biotin deficiency in young chickens is characterized by a reduction in the activity of liver biotin-dependent enzymes which thus impairs gluconeogenesis during periods of food withdrawal. Because the normal bird maintains an elevated fasting blood glucose level, the ability of the classically biotin-deficient animal to resist changes induced by fasting has not been established. Whether the release of insulin and/or glucagon is affected by biotin deficiency has not been investigated and so determining the importance of these hormones in maintaining fasting glucose levels as well as their ability to respond to a challenge is the objective of the present study. Experimental animals (15-week-old cockerels) were fed a biotin-deficient diet for 9 weeks while control animals (n = 8) were pair-fed biotin-supplemented diets. Before fasting, concentrations of plasma glucose, insulin, and glucagon were not different between the two groups. After 72 h of fasting basal glucose levels remained the same in both groups and concentrations of plasma insulin were equally suppressed but concentrations of glucagon were significantly elevated in biotin-deficient animals (P less than 0.025). Ten minutes after an iv glucose challenge the magnitude of the increase in plasma insulin concentrations was equivalent for both groups of animals whereas the magnitude of the decline in plasma glucagon concentrations was greater for biotin-deficient birds. Twenty minutes after a protein challenge (purified casein diet) the levels of plasma glucagon in both groups were maximally increased although the concentrations remained elevated only in control animals. In conclusion the release of insulin and glucagon is not impaired in biotin-deficient animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Soft tissue augmentation as a method of reducing the liability to pressure sores in spinal injured patients.

The development of a procedure designed to reduce the liability to pressure sores over bony prominences is described. This employs the properties of a particular type of carbon fibre pad implanted surgically over the bony prominence. The mechanical response of the pad to loading has been examined. The host tissue response to the pad involves penetration of the interstices between the carbon fibres with organised fibrous tissue. The host-tissue--carbon fibre pad complex has been found to be highly vascular. An 'ischiobarograph' has been developed and used in order to evaluate the alteration in pressure profile produced by the presence of the implanted prosthesis (the patient being in a sitting position).

Animals↗
PubMed1987

The effect of intravenous frusemide on urine dopamine in normal volunteers: studies with indomethacin and carbidopa.

1. The urine dopamine response to intravenous frusemide (30 mg) was investigated in 15 salt replete male volunteers. The effects of oral indomethacin (100 mg) and oral carbidopa (100 mg) given before intravenous frusemide were studied in the same group of subjects. 2. Frusemide produced a significant increase in urine dopamine output within 15 min. 3. Indomethacin attenuated the natriuretic and renin responses to frusemide, but did not alter urine dopamine output. 4. Carbidopa lowered urine dopamine to undetectable levels, but did not significantly affect the natriuretic and renin responses to frusemide. 5. We conclude that urine dopamine excretion after frusemide is not directly related to increased sodium excretion or renin response and it is not mediated by the prostaglandins. In addition, dopamine does not contribute to the renal actions of frusemide under normal conditions.

Administration, Oral↗
PubMed1987

Magnetic resonance microscopy of changes in water content in stems of transpiring plants.

Differences in water content and degree of binding in the various stem tissues of Pelargonium hortorum were observed by magnetic resonance imaging. 1H images were obtained with a resolution of 100 microns in the transverse plane and a slice thickness of 1250 microns. It was possible to distinguish the principal tissues of the stem by differences in their proton density or apparent water content and spin lattice relaxation time (T1) or degree of water binding. Measurements were made while the plant was slowly and actively transpiring. In the slowly transpiring plant, T1 of various tissues ranged from an average of 659 to 865 ms with a proton density variation of from 72 to 100%. In the actively transpiring plant, T1 ranged from an average of 511 to 736 ms, and the proton density was reduced, ranging between 62 and 88% of the peak value found in the slowly transpiring plant. The fibrous sheath surrounding the vascular tissue and the epidermal region was found to have the highest spin density and T1. Both tissues are comprised of relatively small thick-walled cells. Cortical and pith parenchyma are composed of larger, thinner-walled cells with numerous intercellular spaces and lower spin density and T1. The differences are attributed to the higher water content by volume in the tissue composed of smaller, more compactly arranged cells. The resolution obtained in this work enables clear definition of tissues in the living plant and quantitative information concerning differences in the distribution and extent of binding of water.

Magnetic Resonance Spectroscopy↗
PubMed1987

Lumenal location of the microsomal beta-glucuronidase-egasyn complex.

Mouse liver beta-glucuronidase is stabilized within microsomal vesicles by complexation with the accessory protein egasyn. The location of the beta-glucuronidase-egasyn complex and free egasyn within microsomal vesicles was investigated. Surprisingly, it was found that neither the complex nor free egasyn are intrinsic membrane components. Rather, both are either free within the vesicle lumen or only weakly bound to the inside of the vesicle membrane. This conclusion was derived from release studies using low concentrations of Triton X-100 or controlled sonication. Both the intact complex and free egasyn were released in parallel with lumenal proteins, not with intrinsic membrane components. Also, beta-glucuronidase was protected from digestion by proteinase K by the membrane of microsomal vesicles. The hydrophilic nature of both the complex and free egasyn was confirmed by phase separation experiments with the detergent Triton X-114. Egasyn is one of an unusual group of esterases that, despite being located within the lumen or only weakly bound to the lumenal surface of the endoplasmic reticulum, do not enter the secretory pathway.

Animals↗
PubMed1987

Non-invasive measurement of renal blood flow with 99mTc DTPA: comparison with radiolabelled microspheres.

This technique for non-invasive measurement of renal blood flow is based on the principle of fractionation of cardiac output, and applicable with any recirculating gamma activity tracer. It effectively determines the count rate that would be recorded over the kidney if the tracer behaved like radiolabelled microspheres and was completely trapped in the kidney on first pass. After correction for kidney depth, the estimated first pass activity plateau, expressed as a fraction of the injected dose, is equal to the kidney's fraction of cardiac output. The principle of the technique was validated by comparison with renal blood flow based on radiolabelled microspheres. Nine separate comparisons were made in two anaesthetised dogs. A known dose of 99mTc radiolabelled microspheres (particle size 23-45 microns) was injected into the left ventricle and the count rate over each kidney recorded. A known dose of 99mTc diethylenetriaminepenta acetic acid (DTPA) was then given as an intravenous bolus and the data recorded dynamically with a gamma camera online to a computer. After subtraction of the stable signal arising from the preceding radiolabelled microspheres, the theoretical first pass activity plateau from the DTPA that would have been recorded if the DTPA, after reaching the systemic circulation, had behaved like radiolabelled microspheres and become completely trapped in the renal vascular bed, was estimated. Using doses based on syringe counts before and after injection the ratio of renal blood flow values given by the two techniques (DTPA:RLMS) was 1.14 (SD 0.22) for the left kidney and 1.1(0.17) for the right. Using doses based on whole body counts, corresponding ratios were 1.05(0.11) and 1.02(0.13).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Reversible inhibition of rabbit sperm-fertilizing ability by cholesterol sulfate.

Experiments were carried out to examine the influences of lipid treatments on the fertilizing ability of rabbit spermatozoa. In vitro insemination of tubal oocytes with in vivo-capacitated sperm resulted in fertilization (IVF) of 81% of the oocytes (38/47) and in vitro development to the morula or blastocyst stage of 92% (35/38) of the embryos within 72 to 96 h. Treatment of capacitated sperm with cholesterol (Ch, up to 100 micrograms/ml) did not reduce the proportion of oocytes fertilized (fertilization rate, 100%, 8/8). Cholesterol-3-sulfate (Chs) at concentrations of 100 and 1,000 micrograms/ml significantly (p less than 0.001) decreased fertilization rates to 13.6% (8/59), and 3.5% (1/29), respectively. Hypercholesterolemic serum (HChS, 1295 mg cholesterol/dl vs. 45 +/- 18 mg/dl in normal serum), incubated for 2 h with in vivo-capacitated sperm, did not inhibit fertilization. However, a decreasing trend in fertilization was associated with increasing levels of HChS cholesterol. ChS effectively inhibited the fertilizing ability of capacitated sperm (p less than 0.05) compared to control, Ch, and HChS. In another experiment the use of ChS at 100 micrograms/ml significantly (p less than 0.05) reduced the fertilization rate from 56.6% (30/53) to 14.3% (7/49). When a phospholipid-enriched serum medium was added to sperm treated with 100 micrograms ChS/ml, the fertilization rate was 57.7% (23/40), which was not significantly (p less than 0.05) different from the fertilization rate of sperm not treated with ChS (56.6%, 30/53). These data suggest that rabbit sperm fertilizing ability can be reversibly inhibited by cholesterol sulfate.

Animals↗
PubMed1987

Noninvasive measurement of blood flow and extraction fraction.

We describe the theory of a technique for the noninvasive measurement of organ blood flow which is based on the principle of fractionation of cardiac output and is applicable with any recirculating gamma emitting tracer. The technique effectively determines the count rate that would be recorded over the organ if the tracer behaved like radiolabelled microspheres and was completely trapped in the organ's vascular bed on first pass. After correction for organ depth, the estimated first pass activity plateau, expressed as a fraction of the injected dose, is equal to the organ's fraction of the cardiac output (CO). By extending the theory, organ extraction fraction of extractable tracers or mean transit time of nonextractable tracers can be measured. Renal blood flow (RBF) to the normal left kidney in 18 subjects without evidence of renal disease was estimated by the technique to be 10.4% CO (S.D. 1.2), for the right kidney 9.0% CO(S.D. 1.1), and for both, 19.4% CO (S.D. 1.5). In a separate series of eight patients, RBF values were highly reproducible when obtained on successive days (standard deviation of change: 0.67% CO for the left kidney, 0.63% CO for the right and 0.78% CO for both). The extraction fraction of DTPA (filtration fraction) was 8.5% (1.7) in the left kidney and 9.7% (2.1) in the right kidney. This parameter was less reproducible than RBF, with standard deviations of the changes equal to 1.17% for the left kidney and 1.31% for the right. Stable, well-functioning, renal allografts in children had a mean blood flow of 20.6% CO (S.D. 3.7). Transplant blood flow in eight patients with rejection was less than 5.2% CO. In patients without splenomegaly, splenic blood flow, splenic extraction fraction of sulphur colloid and splenic red cell mean transit time were 4.3% CO (S.D. 0.9), 41% (S.D. 13.8), and 36.9 s (S.D. 4.6), respectively.

Blood Circulation↗
PubMed1987

Comparison of a positive expiratory pressure (PEP) mask with postural drainage in patients with cystic fibrosis.

The use of a positive expiratory pressure (PEP) mask was compared with postural drainage in the treatment of 10 patients with cystic fibrosis. The patients were allocated randomly in a crossover fashion to the two regimens and evaluated initially by a physiotherapist and over a 4 week treatment period by use of a diary card. There was no significant difference in sputum production or change in lung function between each technique as assessed by the physiotherapist. Diary card evaluation also failed to demonstrate a difference in sputum production, symptom score or peak expiratory flow rate between the 4 week treatment periods. It was concluded that PEP mask therapy is an acceptable and effective alternative to postural drainage in interval therapy of patients with cystic fibrosis, although the patients have tended to revert to postural drainage during acute exacerbations.

Adolescent↗
PubMed1987

Renal mechanisms of human alpha-atrial natriuretic peptide in man.

1. Eight normal volunteers were studied on two separate days after being dehydrated overnight. Each volunteer received a background intravenous infusion of arginine vasopressin (5.5 X 10(-7) i.u. kg-1 min-1) on both days and also received an intravenous infusion of human alpha-atrial natriuretic peptide (15 pmol kg-1 min-1) plus carrier on one day and carrier alone on the other. The ensuing changes in blood pressure, in the excretion of urinary solutes, and in the excretion of solute-free water were recorded. 2. The infusion of atrial peptide had a small hypotensive effect, and increased the rate of excretion of sodium but not of potassium. There were no significant changes of urinary osmolality or of creatinine clearance. 3. The infusion of atrial peptide increased the rate of solute-free water reabsorption and did so in direct proportion to its effect of increasing sodium excretion. 4. A further six normal, dehydrated volunteers were studied on each of two days after taking 500 mg of lithium carbonate on the previous evening. On one day, they received an intravenous infusion of human alpha-atrial natriuretic peptide (15 pmol kg-1 min-1) plus carrier and on the other day they received carrier alone. The excretion of urinary electrolytes and the creatinine clearance were recorded. 5. The infusion of atrial peptide produced significant increases in the rates of excretion of both sodium and lithium, but there were no such changes of creatinine clearance. 6. Another six normal volunteers were studied on each of two days. On each day they drank 2 l of water over 30 min and then water to replace their urinary losses. They also received loading doses and maintenance infusions of inulin and sodium para-aminohippurate. Once a full water diuresis had become established, each subject received an infusion of human alpha-atrial natriuretic peptide (15 pmol kg-1 min-1) plus carrier on one day and carrier alone on the other, exactly as before. The excretion of sodium and solute-free water, and the clearances of inulin and para-amino-hippurate were recorded. 7. The infusion of atrial peptide increased the rates of excretion of both sodium and solute-free water. It also increased the clearance of inulin, but not that of para-aminohippurate. 8. These results suggest that, in our volunteers, infusion of human alpha-atrial natriuretic peptide increases sodium excretion mainly by increasing the delivery of sodium along the renal tubule from sites upstream of the loop of Henle.(ABSTRACT TRUNCATED AT 400 WORDS)

Arginine Vasopressin↗
PubMed1987

Human and primate malarial sera inhibit Fc receptor-mediated phagocytosis.

Sera obtained from humans in P. falciparum-endemic regions and from P. vivax-infected Saimiri sciureus were assayed for their ability to inhibit Fc receptor-mediated phagocytosis. Some sera of humans exposed to P. falciparum from The Gambia, Sudan, and Thailand inhibited ingestion via the Fc receptor by normal human monocytes. In addition, sera from infected monkeys and a high molecular weight fraction of infected monkey serum inhibited ingestion of EIgG by normal monkey spleen macrophages. Generally, inhibition was correlated with higher parasitemia and higher IFA titers.

Adolescent↗
PubMed1987

The China diary. AMRA delegation's visit to China. Part I.

In May, 22 AMRA representatives toured the People's Republic of China at the invitation of the Chinese government. Designated delegates kept a diary of the informational exchange between the AMRA delegates and their hosts, as well as a commentary on places seen during their travels. Their diary entries have been compiled into a two-part article. The first part appears in this issue, and the second part will appear in the September issue.

Abstracting and Indexing↗
PubMed1987

Efficacy of carvedilol in exercise-induced myocardial ischemia.

The exercise response to a single oral dose (25 mg) of a new beta-blocking agent that also has potent vasodilating properties, carvedilol, was assessed in 15 patients with stable exertional angina, positive exercise tests (greater than or equal to 1 mm ST depression) and coronary artery disease. A placebo-controlled, randomized, crossover study was carried out. Compared with placebo, carvedilol significantly reduced both resting heart rate (HR) and blood pressure (BP) at rest. After the administration of carvedilol, 10 of the 15 patients did not have angina at peak exercise and 5 had ST shifts less than 1 mm. Total exercise time and time to 1 mm ST depression were prolonged, and ST segment depression at peak exercise was significantly reduced. Systolic BP was reduced both at peak exercise and at 1 mm ST depression whereas mean HR at peak exercise did not change significantly compared with placebo. Overall, mean HR-BP product at peak exercise was significantly reduced by carvedilol compared with placebo. However, four patients achieved similar or higher HR-BP product and yet did not experience angina and had less ST depression (or no ST segment shifts) during exercise. This indicates an increase in their coronary flow reserve. These results suggest that carvedilol is effective therapy for effort-induced angina, and this may be related to its combined beta-blocking and vasodilatory properties.

Adrenergic beta-Antagonists↗
PubMed1987

Presumptive screening of suspected semen stain in situ using cotton swabs and bromochloroindolyl phosphate to detect prostatic acid phosphatase activity.

A novel approach to the presumptive screening of questioned semen stains has been developed which enables the rapid identification of stains which are devoid of semen. Questioned semen stains can be swabbed with a moist cotton swab, and the prostatic acid phosphatase (SAP) activity transferred to the swab identified through assay with 5-bromo-4-chloro-3-indolyl phosphate (BCIP). Controlled laboratory studies revealed that the BCIP swab procedure was as sensitive as the semiquantitative SAP test currently employed in the FBI Laboratory for the presumptive screening of semen stains. A validation study of the BCIP swab procedure in parallel with the current procedure using 4305 case evidence stains indicated that the BCIP swab procedure was as effective as the current procedure in identifying those questioned stains which lack semen. The advantage of the BCIP swab procedure is that it can be performed on questioned stains in situ and thereby avoids the requirement of removing and extracting the stain before assay of SAP activity.

Acid Phosphatase↗