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Biomedical subjects

R C Smith

Publications and source records attributed to R C Smith.

At least 217 records · Page 12Linked to original sources
PubMed1987

Effects of light chain phosphorylation and skeletal myosin on the stability of non-muscle myosin filaments.

The effect of light chain phosphorylation and the presence of skeletal muscle myosin on the stability of non-phosphorylated non-muscle myosin filaments was investigated. Purified skeletal, brush border and thymus myosins were assembled in vitro into hybrid filaments consisting of varying proportions of (1) non-muscle and skeletal myosins, or (2) phosphorylated and non-phosphorylated non-muscle myosins. The stability of these hetero- and homopolymers in the presence of MgATP was determined using sedimentation, gel electrophoresis and immunochemical techniques. In addition, the effect of a monoclonal antibody, binding to the tip of brush border myosin tail, on the assembly of the homo- and heteropolymers, was tested. Filamentous non-phosphorylated non-muscle myosin was disassembled by MgATP to the same extent whether in homo- or heteropolymers, indicating that skeletal myosin has no stabilising effect on the hybrid filaments. The presence of small amounts of phosphorylated non-muscle myosin was, however, found to prevent the complete disassembly by MgATP of non-phosphorylated non-muscle myosin filaments, indicating that light chain phosphorylation stabilizes co-operatively non-muscle myosin filaments. The monoclonal antibody prevented the assembly of brush border myosin into both homo- and heteropolymers, and its effect on the filaments was compared with that of MgATP.

Adenosine Triphosphate↗
PubMed1987

Antioxidant properties of 2-imidazolones and 2-imidazolthiones.

Uric acid has been postulated to be an important antioxidant and free radical scavenger in humans. Other purines, such as xanthine, that lack an 8-oxo group on the imidazole ring do not show antioxidant properties. For this reason, the antioxidative activities of 2-imidazolones and 2-imidazolthiones were compared to that of uric acid. 2-Imidazolthiones reacted with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) at rates comparable to those of uric acid and other antioxidants. 2-Imidazolones also reacted with DPPH, although at a much slower rate than the 2-imidazolthiones. The 2-imidazolthiones protected oxyhemoglobin from oxidation to methemoglobin by sodium nitrite; the 2-imidazolones had little effect on the oxidation of oxyhemoglobin by nitrate. Most of the 2-imidazolthiones and 2-imidazolones protected both porcine and bovine erythrocytes from hemolysis by t-butyl hydroperoxide. Although 2-imidazolthiones were more reactive than 2-imidazolones in the assays using DPPH and the oxidation of oxyhemoglobin, both types of compounds may be useful as antioxidants in vivo.

Animals↗
PubMed1987

Magnetic resonance imaging studies of the brains of schizophrenic patients.

Magnetic resonance imaging studies of the brains of schizophrenic and control subjects were performed using a 0.3 Tesla superconducting magnet. Quantitative measurements of ventricular size, sulcal width, and standardized image intensity were performed. There were no significant differences between schizophrenic and comparison subjects for linear or area measures related to ventricular size, corpus collusum size, or cortical atrophy. However, schizophrenics had a significantly higher image intensity in the inversion recovery mode (IR-30). Since the IR-30 images are T1 weighted, this suggests that there may be differences in T1 relaxation times in tissues in some areas of the brains of schizophrenics as compared to controls. However, more precise measurements of T1 relaxation time are needed to confirm this finding.

Adult↗
PubMed1987

Uric acid protects erythrocytes from ozone-induced changes.

Uric acid effectively reduced hemolysis and methemoglobin formation in bovine and swine erythrocytes bubbled with ozone in vitro. In bovine erythrocytes, formation of thiobarbituric acid-reactive material was inhibited by uric acid, but there was little immediate protection for the swine cells. Antioxidant protection was due to preferential degradation of the uric acid by ozone. These results provide evidence to support the hypothesis that in plasma, uric acid can provide antioxidant protection for erythrocytes.

Animals↗
PubMed1987

Reaction of methylated urates with 1,1-diphenyl-2-picrylhydrazyl.

The kinetics of the reaction between the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and methylated urates was studied. Urates that had methyl groups on the 1,3,9, or on the 1 and 3 or 1 and 9 nitrogens reacted with DPPH 15 to 77% faster than uric acid. Urates substituted with methyl groups on the 7 nitrogen or on both the 3 and 9 nitrogens reacted with DPPH at rates that were less than 0.1 that of uric acid. 3,7,9-Trimethyluric acid and 1,3,7,9-tetramethyluric acid reacted with DPPH at barely detectable rates. DPPH reacted with uric acid, the monomethylated urates, and some of the dimethylated urates in a ratio of 2:1. DPPH reacted with other dimethylated and trimethylated urates in a ratio of 1:1. Semiempirical MNDO calculations indicate that the most stable radical of uric acid is formed by hydrogen abstraction from the 3, 7 or 9 position. The most stable species resulting from loss of a second hydrogen lack hydrogens at the 3 and 7 positions or the 7 and 9 positions. For maximum reactivity with DPPH, methylated uric acid derivatives must have a hydrogen at nitrogen 7 and one of the hydrogens at either the 3 or 9 position.

Biphenyl Compounds↗
PubMed1987

Radiographic differentiation between different etiologies of pulmonary edema.

We compared the plain chest radiographs of critically ill patients who had different types of pulmonary edema and evaluated the radiographs according to a standardized score sheet of findings. We included 94 total cases of pulmonary edema: 49 with cardiogenic, 33 with permeability, and 12 with renal/overhydration pulmonary edema. Patients with cardiogenic edema had enlarged hearts, vascular engorgement, septal lines, and absence of air bronchograms significantly more often than patients with permeability pulmonary edema. Renal/overhydration patients had enlarged hearts significantly more often than patients with permeability edema. There were no other statistically significant differences. Heart size and presence or absence of septal lines could have been used to distinguish cardiogenic and permeability edema in 83% of cases.

Capillary Permeability↗
PubMed1987

Do dreams reflect a biological state?

The purpose of this study was to prospectively evaluate the hypothesis that dreams reflect biological states. Inpatients on a nonacute cardiology service were studied. Dream material was gathered by an independent interviewer using the Staged Interview Technique, a newly developed interview technique that limited bias. The outcome measures used were obtained at the time of cardiac catheterization. Different levels of severity of cardiac disease with these measures were interpreted as representing different biological states. The patients' dreams were evaluated for the predicted correlations of the number of dream references to death (men) and separation (women) with different levels of severity of heart disease. The severity of heart disease was evaluated with anatomical (coronary angiography) and physiological (ejection fraction) measures obtained at cardiac catheterization, each represented by a 6-point scale of increasing severity. There was no correlation of the number of dream references with the severity of abnormalities on coronary angiography. However, the number of dream references to death and separation correlated with the severity of cardiac dysfunction, as measured by the ejection fraction, which is a more sensitive parameter of disease severity. The data provided prospective support for the hypothesis by showing that dreams reflected a biological state, the ejection fraction. This suggested a possible biological "meaning" of dreams.

Adult↗
PubMed1987

A randomised comparison of three drainage systems following cholecystectomy.

The efficacy of low pressure, high pressure and passive drainage systems have been compared after cholecystectomy. Symptoms of pain, discomfort and nausea were compared using linear analogue scales and spirometry was used to examine pre-operative and postoperative respiratory function. The low pressure suction drain removed an intraperitoneal marker, gentamicin, more effectively than the high pressure suction drain, but not more effectively than the passive drain. There were no differences in postoperative respiratory function nor in the amount of pain or discomfort between the groups. The passive drain group reported less nausea than the suction drain groups. If a negative pressure drainage system is to be used, a low pressure suction drain should be used in preference to a high pressure system.

Cholecystectomy↗
PubMed1987

Cortical atrophy and white matter density in the brains of schizophrenics and clinical response to neuroleptics.

The relationship between clinical response to neuroleptics and brain morphology as revealed by CT scans was evaluated in a sample of 39 patients with schizophrenia and schizoaffective psychosis. Four measures of brain morphology previously shown to differ between schizophrenics and patients with headaches - white matter density, asymmetry in brain white matter density, sulcal width and global cortical atrophy - did not correlate with clinical improvement after 3 weeks treatment with constant doses of neuroleptics. These brain morphology measures also did not correlate with baseline psychopathology scores. The same results were found with scales or subscales reflecting primarily positive symptoms of schizophrenia as well as those reflecting primarily social withdrawal.

Adult↗
PubMed1987

Plasma levels and effects of nortriptyline in geriatric depressed patients.

Pharmacokinetic, therapeutic effects, and side effects of nortriptyline were studied in geriatric depressed patients treated with a standard dose of 150 mg/day. Plasma levels and elimination half-life of nortriptyline were no different in geriatric patients than younger patients. The antidepressant therapeutic effects of nortriptyline appeared to be similar in geriatric patients as in younger depressed patients. Geriatric patients experienced few subjective side effects of nortriptyline. Overall, the drug produced no clinically significant changes in several parameters of the EKG, and no geriatric patient experienced tachycardia on nortriptyline. Nortriptyline did induce significant orthostatic hypotension in the systolic component, but not in the diastolic component. However, the orthostatic hypotension produced by nortriptyline was not greater in geriatric patients than in younger patients treated with the same dose.

Age Factors↗
PubMed1987

Successful replantation of amputated nose and auricle.

Amputations of the nose and of the auricle present difficult management problems. Application of simple reattachment techniques, followed by aggressive medical therapy which consists of cooling, anticoagulation, antibiotic coverage, and multiple stab incisions in the amputated tissues, have resulted in the successful replantation of major portions of an amputated nose and an amputated auricle with satisfactory cosmetic results.

Adult↗
PubMed1986

Role of general practitioners in the care of disabled young adults.

Services for handicapped children end when these patients become young adults. In the Exeter Health Authority district 383 disabled young adults were interviewed about their unmet needs. Many wished for advice and counselling. A quarter had not visited their general practitioner in the previous year, and two thirds of these had not had a general assessment or seen a specialist.

Adult↗
PubMed1986

Uric acid protects membranes and linolenic acid from ozone-induced oxidation.

Aqueous preparations of linolenic acid, bovine serum albumin, and bovine erythrocyte membrane fragments were bubbled with ozone in the presence or absence of uric acid. Ozonation of the membrane fragments or the bovine serum albumin did not result in protein degradation. After 15 min of ozonation, the absorbance of the thiobarbituric acid-reactive material increased by 0.34 in the linolenic acid preparation and by 0.08 in the suspension of membrane fragments. In the presence of uric acid, these changes in absorbance were reduced to 0.14 for the fatty acid and to 0.01 for the membrane fragments. This result indicates that uric acid protects lipids from ozone-induced oxidation.

Animals↗
PubMed1986

Uric acid protection of nucleobases from ozone-induced degradation.

Uric acid has been proposed to be an important antioxidant and free radical scavenger in humans. Of the purine and pyrimidine compounds examined in this study, uric acid showed the greatest susceptibility to ozone-induced degradation. The parent compounds, purine and pyrimidine, were more resistant to ozonation than were the nucleobases. When the degradation of OH-substituted purines was examined, it was found that the more OH groups on the purine ring, the more readily the purine was degraded. Urea and allantoin were identified as degradation products of uric acid. The relative rates of nucleobase degradation in the presence and absence of uric acid were compared. Uric acid protected thymine, guanine, and uracil from degradation by ozone. In this system uric acid was found to protect the nucleobases as effectively as reduced glutathione.

Antioxidants↗
PubMed1986

Rhinoplastic revisions with injectable silicone.

We report 20 years of experience with conservative and cautious injection of small amounts of medical-grade liquid silicone in 347 postrhinoplasty patients for a total of 1,937 treatments. Medical-grade silicone was found to be a safe, effective, and valuable adjunct to cosmetic rhinoplastic procedures. Microdroplet technique with very small doses is recommended for the correction of nasal defects that may not be amenable to revisional surgery. Controlled release of this material to the medical profession after appropriate evaluation is recommended, along with proper training prior to its use.

Combined Modality Therapy↗