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Biomedical subjects

R Smith

Publications and source records attributed to R Smith.

At least 1,225 records · Page 68Linked to original sources
PubMed1985

The encephalitogenic protein of myelin forms hexamers in which the polypeptides have a pleated-sheet structure.

Sedimentation equilibrium data are shown to be consistent with the existence in solution of an equilibrium between monomers and hexamers of bovine myelin basic protein, without significant accumulation of intermediates. At low concentrations circular dichroism spectra were indicative of an aperiodic coiled secondary structure. At higher concentrations, where the protein self-associates, they showed formation of a beta-pleated sheet conformation. At low molar ratios myristoyllysophosphatidylcholine promotes protein self-association and the concomitant conformational transition. The data are consistent with the existence of an equilibrium mixture of relatively unstructured monomers and hexamers in which the polypeptides have a well-defined three-dimensional structure.

Animals↗
PubMed1985

Effect of histamine infusion on circulating methionine-enkephalin and catecholamine concentrations.

In 5 normal adult men, histamine was infused i.v. for 5 min at 20 micrograms/kg/h and at 80 micrograms/kg/h on two occasions one week apart. Diastolic blood pressure fell and heart rate, plasma adrenaline and noradrenaline all rose in a dose-dependent manner, but plasma methionine-enkephalin (Met-Enk) concentrations were unchanged. These results indicate that while Met-Enk may be co-stored with catecholamines (CAs) in the adrenal medulla in at least this paradigm, circulating concentrations of CAs may be altered without similar changes in plasma Met-Enk immunoreactivity.

Adrenal Medulla↗
PubMed1985

The effect of surgery on plasma beta-endorphin and methionine-enkephalin.

Seven women undergoing abdominal hysterectomy under halothane and nitrous oxide analgesia had plasma samples taken before, during and after surgery for assay of adrenocorticotrophin (ACTH), beta-endorphin, beta-lipotrophin and methionine (Met)-enkephalin immunoreactivity. Plasma ACTH, beta-endorphin and beta-lipotrophin all rose in parallel from the start of surgery and were unaffected by postoperative opiate analgesia. Plasma Met-enkephalin concentrations did not change significantly during the course of the surgery and immediate post-operative period, although the variance of the samples increased at the time of the first skin incision. These data indicate that the stress of surgery and post-operative pain, while producing marked elevations of proopiomelanocortin-derived peptides, are not associated with changes in plasma Met-enkephalin. These data exclude a role for circulating Met-enkephalin in the modulation of surgical pain but do not exclude such a role for beta-endorphin.

Analgesics, Opioid↗
PubMed1985

Booze on the telly.

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Alcohol Drinking↗
PubMed1985

Breaking the ice.

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Burnout, Professional↗
PubMed1985

Needle localization of nonpalpable breast masses.

A series of 146 women underwent 150 preoperative localizations of mammographically suspicious but nonpalpable breast lesions. The lesions were localized using the hook-wire method of Frank in 133 of these patients. Carcinoma was discovered in 24 (16%) of the women; 18 (75%) of these women had invasive and six women (25%) had noninvasive carcinomas. Sixty-seven patients demonstrated calcification, and of these, 16 patients (24%) turned out to have malignancies. Eighty percent of the cancers were less than 1 cm in diameter, and 38% met the criteria of minimal carcinoma as described by Gallagher and Martin in 1969. Fourteen percent of the patients with carcinoma had lymph node metastases. We conclude that this is a safe, rapid, and accurate method for localizing small, potentially highly curable breast cancers with minimal sacrifice of breast tissue.

Adult↗
PubMed1985

Protein absorption and desorption phenomena on clean metal surfaces.

The noncompetitive adsorption of the proteins albumin and fibrinogen onto 17 different metal surfaces has been studied in vitro using 125I-labeled proteins. Although many of the metals showed very similar adsorption characteristics to polymers, several of them adsorbed considerably greater amounts. Copper, gold, and silver were the most significant in this respect, all three being face-centered cubic, group 1B metals known to bind to many types of protein in vitro and in vivo. The desorption of the proteins was studied in an in vivo model in which preproteinized metals were implanted in rats. There was considerable variations in the amounts of the proteins removed from the various metal surfaces. Generally those metals onto which protein is most readily adsorbed tend to lose the protein quickly, whereas others, such as iron, with only moderate adsorbed amounts, may retain a large part of the adsorbed layer for a long time.

Adsorption↗
PubMed1985

Excessive excretion of beta-alanine and of 3-hydroxypropionic, R- and S-3-aminoisobutyric, R- and S-3-hydroxyisobutyric and S-2-(hydroxymethyl)butyric acids probably due to a defect in the metabolism of the corresponding malonic semialdehydes.

A new metabolic disorder characterised by the excessive excretion of beta-alanine, 3-hydroxypropionic acid, R- and S-3-amino- and 3-hydroxyisobutyric acids and S-2-(hydroxymethyl)butyric acid is probably due to deficient activities of malonic, methylmalonic and ethylmalonic semialdehyde dehydrogenases. These dehydrogenation reactions could be mediated by one enzyme, or by enzymes with a common subunit, and both R- and S-methylmalonic semialdehydes seem to be equally affected. The patient is now aged 4 years and has developed normally. He has a persistent gross hypermethioninaemia which is probably unrelated to the other biochemical abnormalities.

Alanine↗
PubMed1985

Correlative studies in Alzheimer's disease.

An approach is described for establishing and maintaining a correlative study of Alzheimer's Disease. A sample of the findings by the University of Western Ontario (U.W.O.) Dementia Study Group is provided.

Aged↗
PubMed1985

Tolerance of peripheral nerve to intraoperative radiotherapy (IORT): clinical and experimental studies.

In our clinical experience combining wide excision and intraoperative radiotherapy (IORT), five patients have developed clinical signs of lumbosacral or sciatic neuropathy within 9 months of receiving IORT to a dose of 20-25 Gy. Three patients showed recovery of nerve function over several months while two patients have shown no recovery and have near complete loss of extremity function. In an attempt to investigate this clinical observation further, the lumbosacral plexus and sciatic nerve of American foxhounds were surgically exposed and received a single dose of IORT ranging from 20-75 Gy. An approximate linear relationship between radiation dose and time to onset of hind limb paresis is found with 19 of 21 irradiated dogs showing clinical signs of nerve injury within an interval of 1-19 months. No recovery of nerve function is seen in these dogs. Histological study of the irradiated nerves demonstrates a loss of nerve fibers, particularly those of the large myelinated type without evidence of vascular occlusion or thrombosis. These studies suggest that peripheral nerve may be a dose-limiting normal tissue in clinical studies of IORT.

Adult↗
PubMed1985

Synthesis and biological evaluation of 9-[5'-(2-oxo-1,3,2-oxazaphosphorinan-2-yl)-beta-D-arabinosyl]ade nine and 9-[5'-(2-oxo-1,3,2-dioxaphosphorinan-2-yl)-beta-D-arabinosyl]ade nine: potential neutral precursors of 9-[beta-D-arabinofuranosyl]adenine 5'-monophosphate.

9-[5'-(2-Oxo-1,3,2-oxazaphosphorinan-2-yl)-beta-D-arabinosyl]adeni ne (1c) and 9-[5'-(2-oxo-1,3,2-dioxaphosphorinan-2-yl)-beta-D-arabinosyl]adeni ne (1d) were synthesized by reaction of 9-[beta-D-arabinofuranosyl]adenine with phosphoryl chloride with 1-amino-3-propanol and 1,3-propanediol, respectively. 1c consisted of a mixture of diastereomers, while 1d was enantiomerically homogeneous. The structures of these compounds were established by spectral (1H NMR, MS, UV) and elemental analyses. Both 1c and 1d were resistant to degradation by 5'-nucleotidase, alkaline phosphatase, venom phosphodiesterase, crude snake venom, adenosine deaminase, and adenylate deaminase. Neither compound was significantly biotransformed by mouse hepatic microsomal preparations in the presence of an NADPH-generating system. Compound 1c was marginally effective at prolonging the life span of mice bearing P-388 leukemia; compound 1d, however, was inactive.

5'-Nucleotidase↗
PubMed1985

Cannulation of the cisterna magna in sheep: a method for chronic studies of cerebrospinal fluid.

A method of cannulating the cisterna magna of sheep is described. Successful cannulations were achieved in 15 of 17 attempts (88%). Mean cannula patency was 13.9 days (range 7-20). Using these cannulas, it was possible to obtain samples of cerebrospinal fluid (CSF) in large volumes (4-8 ml) and remove 20-30 ml of CSF over a 5 h period. This technique allows access to the CSF of an animal large enough for the removal of samples of CSF of sufficient size to detect materials present at very low concentrations.

Animals↗
PubMed1985

Mitochondrial modulation of maternally transmitted antigen: analysis of cell hybrids.

Maternally transmitted antigen (Mta) is a murine cell surface class I-like antigen that is defined by specific cytotoxic lymphocyte reactivity. Mta is unique in that its expression requires cooperation between genetic elements both in the Qa/Tla region of chromosome 17 and in the cytoplasm. In view of the known cytoplasmic, and thus maternal, inheritance of mitochondria, we have directly assessed their potential involvement in Mta expression. The mitochondria-specific lethal dye rhodamine 6G (R6G) was used to control the input of mitochondria into cell hybrids. The parental lines, one of BALB/c and one of NZB origin, were known to differ in Mta and mtDNA phenotype. Our data show that most control BALB/c-NZB hybrids expressed the BALB/c Mta phenotype and likewise contained only BALB/c-type mtDNA. The NZB Mta phenotype was not coexpressed in the control hybrids. However, when the mitochondrial contribution from BALB/c was prevented by R6G treatment, the majority of the resultant hybrids expressed only the NZB Mta type and likewise contained only NZB mtDNA. The exceptional R6G-treated hybrids that continued to express the BALB/c Mta phenotype likewise contained only BALB/c mtDNA. Thus, in every case the mtDNA phenotype correlated with the Mta phenotype of the cells. Together, the data support the remarkable conclusion that mitochondria modulate the phenotypic expression of a cell surface molecule.

Animals↗
PubMed1985

Pelvic tilt. Intratester reliability of measuring the standing position and range of motion.

The purpose of this study was to examine intratester reliability of a test designed to measure the standing pelvic-tilt angle, active posterior and anterior pelvic-tilt angles and ranges of motion, and the total pelvic-tilt range of motion (ROM). After an instruction session, the pelvic-tilt angles of the right side of 20 men were calculated using trigonometric functions. Ranges of motion were determined from the pelvic-tilt angles. Intratester reliability coefficients (Pearson r) for test and retest measurements were .88 for the standing pelvic-tilt angle, .88 for the posterior pelvic-tilt angle, .92 for the anterior pelvic-tilt angle, .62 for the posterior pelvic-tilt ROM, .92 for the anterior pelvic-tilt ROM, and .87 for the total ROM. We discuss the factors that may have influenced the reliability of the measurements and the clinical implications and limitations of the test. We suggest additional research to examine intratester reliability of measuring the posterior pelvic-tilt ROM, intertester reliability of measuring all angles and ROM, and the pelvic tilt of many types of subjects.

Adult↗
PubMed1985

Radioactive iodine treatment of metastatic thyroid carcinoma with clinical thyrotoxicosis.

We present a case of well-differentiated follicular carcinoma of the thyroid with hyperfunctioning metastases and clinical thyrotoxicosis. The recommended I-131 treatment dose for patients with widespread bone metastases from thyroid carcinoma is 200 mCi. However, in a patient with hyperfunctioning metastatic tumor and increased radioiodine uptake, the treatment dose should be modified. Radiation dosimetry measurements performed on the patient in this study demonstrated that 132 mCi would be a safe therapeutic I-131 dose which would avoid injury to normal radiosensitive tissues. Consequently, she was given a 130-mCi therapeutic dose.

Adenocarcinoma↗