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Biomedical subjects

S Smith

Publications and source records attributed to S Smith.

At least 721 records · Page 40Linked to original sources
PubMed1989

The premenstrual syndrome--diagnosis and management.

Premenstrual syndrome is an extremely common disorder. Prospective documentation of symptoms and their temporal relationship to menstruation establishes the diagnosis of PMS. Because the pathophysiologic mechanisms causing PMS are still undetermined, therapy for PMS is largely empiric. A number of pharmacologic agents may be used to reduce PMS symptomatology, and therapeutic decisions should be tailored to the individual's symptom complex. Many women will be able to lead more productive lives if PMS is properly diagnosed and intelligently treated.

Clinical Trials as Topic↗
PubMed1989

Dura versus Gore-Tex as an abdominal wall prosthesis in an open and closed infected model.

Occasionally, it is necessary to use prosthetic material to close large abdominal wall defects in infected, potentially infected, or open wounds. We compared the effectiveness of Gore-Tex (PTFE, W.L. Gore & Associates, Flagstaff, AZ) and dura for closing large, full thickness abdominal wall defects in terms of resistance to infection, patch separation, and intraperitoneal adhesion formation. Ninety guinea pigs had full thickness, 2 cm2, abdominal defects patched with either PTFE or dura. The skin was (A) left open (B) closed over the patch under aseptic conditions, or (C) closed after wound contamination with 10(5) CFU of staphylococcus aureus. Wounds were examined daily and the wound and peritoneal cavity examined at necropsy (day 45). Patch separation, patch retention, and adhesions were similar in both open (A), and clean closed (B) wounds patched with PTFE or dura. In the infected closed wounds (C) of the PTFE animals, the incision remained intact significantly longer, the time of patch separation and overall patch retention were significantly increased, and bowel adhesions were significantly reduced compared to dura animals.

Abdominal Muscles↗
PubMed1989

Expression of the chicken vimentin gene in transgenic mice: efficient assembly of the avian protein into the cytoskeleton.

To study expression and function of the vimentin gene, transgenic mice were generated by microinjecting the entire chicken gene plus 2.4 kilobases of 5' and 2.6 kilobases of 3' flanking sequences. All the transgenic mice obtained had incorporated multiple copies of the gene. RNA analyses demonstrated that the chicken vimentin gene was efficiently expressed in an appropriate tissue-specific pattern and that the transcripts were properly processed, as in chicken, giving rise to two RNAs. The vimentin transgene was predominantly expressed in lens at levels of up to 10-fold the endogenous level in every transgenic line studied. The chicken vimentin transcripts were efficiently translated into polypeptides that were modified posttranslationally and could assemble into the mouse cytoskeleton. Overexpression of the chicken vimentin gene did not obviously affect the expression of the endogenous gene at the RNA or the protein level. Immunofluorescence microscopy further demonstrated that the chicken protein was properly expressed spatially in lens. However, the levels were much higher in the transgenic animals.

Animals↗
PubMed1989

Molecular cloning and sequencing of cDNAs encoding the entire rat fatty acid synthase.

Overlapping cloned cDNAs representing the entire sequence of the rat fatty acid synthase mRNA have been isolated from a cDNA library and sequenced. Authenticity of the cDNA clones was supported by hybridization to fatty acid synthase mRNA and by amino-terminal sequencing of 39 fatty acid synthase CNBr fragments. The full-length fatty acid synthase mRNA is 9156 nucleotides long and includes an 84-nucleotide 5' noncoding region, a 7515-nucleotide coding sequence, and a 1537-nucleotide 3' noncoding region; a second mRNA species containing a shortened 3' noncoding sequence is also transcribed in the rat. The encoded fatty acid synthase subunit contains 2505 amino acids and has a molecular weight of 272,340. Active sites and substrate binding sites were located within the sequence, thus establishing the order of domains on the multifunctional animal fatty acid synthase as condensing enzyme-transferase-dehydrase-enoyl reductase-ketoreductase-acyl carrier protein-thioesterase.

Amino Acid Sequence↗
PubMed1989

Overexpression of the vimentin gene in transgenic mice inhibits normal lens cell differentiation.

To investigate the role of the intermediate filament protein vimentin in the normal differentiation and morphogenesis of the eye lens fiber cells, we generated transgenic mice bearing multiple copies of the chicken vimentin gene. In most cases, the vimentin transgene was overexpressed in the lenses of these animals, reaching up to 10 times the endogenous levels. This high expression of vimentin interfered very strongly with the normal differentiation of the lens fibers. The normal fiber cell denucleation and elongation processes were impaired and the animals developed pronounced cataracts, followed by extensive lens degeneration. The age of appearance and extent of these abnormalities in the different transgenic lines were directly related to the vimentin level. Electron microscopic analysis revealed that the accumulated transgenic protein forms normal intermediate filaments.

Animals↗
PubMed1989

Measurement of x-ray tube potential in the mammographic region.

In mammography it is important to be able to measure x-ray tube potential with an accuracy of +/- 1 kV or better. Mammography x-ray sets generally use molybdenum for both target and filter. Consequently, a high proportion of the x-ray spectrum consists of characteristic radiation from the target. Devices for estimating tube potential such as penetrameters and digital kV meters, which depend on the relation between tube potential and the filtered x-ray spectrum, could be affected in their performance unless calibrated on similar x-ray sets. This paper reports tube potential measurements on a Mo/Mo x-ray set from 25 to 37 kV using the fluorescence technique, a manufacturer's potential divider, two penetrameters of different design and two digital meters of a single design. Agreement between all four techniques was good, being within the various combined experimental errors associated with each, from 37 down to 28 kV, below which the results diverged only slightly.

Calibration↗
PubMed1989

Serum oncogene proteins in hazardous-waste workers.

Oncogene protein detection may be a valuable molecular epidemiological marker of commitment to the carcinogenic pathway in worker populations exposed to carcinogens. This paper reports the use of serum immunoblotting with monoclonal antibodies to oncogene proteins to screen hazardous waste workers with potential carcinogen exposure who employ state-of-the-art work practices and personal protective equipment to minimize real exposures. Two individuals in this cohort were found to be trace positive for the ras oncogene protein in their serum, but this may have been due to their cigarette smoking. These results are contrasted to previous results in hazardous waste workers with real workplace carcinogen exposures.

Adult↗
PubMed1989

Does the bacteremia observed in hemorrhagic shock have clinical significance? A study in germ-free animals.

We have recently reported the rapid appearance of bacteria and endotoxin in the blood of rats and of trauma patients in the course of 30 minutes to 2 hours of hemorrhagic shock. The current study was designed to determine the effect of this bacteremia and endotoxemia on survival. Thirty-three conventional (C:group 1) and 36 germ-free (GF:group 2) Sprague Dawley rats were subjected to our previously described model of treated hemorrhagic shock. Survival in the GF group was significantly better than the C group at 24, 48, and 72 hours after shock. Endotoxin levels were elevated in 88% of C group during shock and in 28% of GF group. The gut of the GF animal contains endotoxin (26 ng/gm of stool) as does the sterile food supply (393 ng/gm of rat chow).

Animals↗
PubMed1989

Comparison of CT scan muscle measurements and isokinetic trunk strength in postoperative patients.

The present study compared the computed tomography (CT) scan muscle area/muscle density and isokinetic trunk strength of a group of spinal surgery patients (35 males and 11 females) 3 months postoperatively. Analyses showed trunk strength means to be below 50% of gender-specific "normal" values obtained by evaluating a normative sample. Extensor strength was more significantly affected than flexors. Single-cut CT scans performed at the time of isokinetic trunk strength assessment demonstrated psoas and erector spinae atrophy through a significant decrease in muscle density, with only a trend towards decreased cross-sectional area. Findings also indicated that there was a significant correlation between increased mechanical trunk strength performance and greater muscle density on CT scan. Strength was significantly lower for the male patients undergoing spinal fusion compared with those undergoing disc excision. However, no significant difference was found in strength measures between: males with high versus low pain level and working versus nonworking males at the time of evaluation.

Adult↗
PubMed1989

Suicidal ideation in a young adult population.

Depending on the manner in which the data were interpreted, as many as 17.5% of women and 20.2% of men, or as few as 3.0% of women and 3.3% of men in a young Australian adult population reported some degree of suicidal ideation in the few weeks prior to testing. Using a suicidal ideation score derived from the General Health Questionnaire (GHQ), 11.7% of men and 9.7% women could be considered to have suicidal ideation. These findings and the diversity of results from other studies emphasize the need for standardized methods of assessment of suicidal ideation. The GHQ could be usefully employed for this purpose, particularly as it is widely used and further analysis of existing data could provide valuable comparisons.

Adolescent↗
PubMed1989

A double-blind controlled trial of long chain n-3 polyunsaturated fatty acids in the treatment of multiple sclerosis.

A trial of n-3 polyunsaturated fatty acids in the treatment of multiple sclerosis has been conducted over a 5 year period. Ambulant patients (312) with acute remitting disease were randomly allocated to treatment or placebo. Both groups were given dietary advice to increase the intake of n-6 polyunsaturated fatty acids and the treatment group in addition received capsules containing n-3 polyunsaturated fatty acids. Analysis of clinical outcome at the end of 2 years of treatment was made in terms of the duration, frequency and severity of relapses and the number of patients who had improved or remained unchanged. The results showed no significant difference at the usual 95% confidence limits but there was a trend in favour of the group treated with n-3 polyunsaturated fatty acids in all parameters examined.

Adipose Tissue↗
PubMed1989

People with Down's syndrome can be distinguished on the basis of cholinergic dysfunction.

The mydriatic response to eyedrops of the anticholinergic agent tropicamide at very low concentration (0.01%) has been studied in people with Down's syndrome. By comparison with healthy subjects people with Down's syndrome had responses approximately three times greater, suggesting a peripheral imbalance between cholinergic and adrenergic autonomic influences.

Adolescent↗
PubMed1989

Acetylcholine's effect on vascular resistance and compliance in the pulmonary circulation.

Acetylcholine's effect on the distribution of vascular resistance and compliance in the canine pulmonary circulation was determined under control and elevated vascular tone by the arterial, venous, and double occlusion techniques in isolated blood-perfused dog lungs at both constant flow and constant pressure. Large and small blood vessel resistances and compliances were studied in lungs given concentrations of acetylcholine ranging from 2.0 ng/ml to 200 micrograms/ml. The results of this study indicate that acetylcholine dilates large arteries at low concentrations (less than or equal to 20 ng/ml) and constricts small and large veins at concentrations of at least 2 micrograms/ml. Characterization of acetylcholine's effects at constant pulmonary blood flow indicates that 1) large artery vasodilation may be endothelial-derived relaxing factor-mediated because the dilation is blocked with methylene blue; 2) a vasodilator of the arachidonic acid cascade (blocked by ibuprofen), probably prostacyclin, lessens acetylcholine's pressor effects; 3) when vascular tone was increased, acetylcholine's hemodynamic effects were attenuated; and 4) acetylcholine decreased middle compartment and large vessle compliance under control but not elevated vascular tone. Under constant pressure at control vascular tone acetylcholine increases resistance in all segments except the large artery, and at elevated vascular tone the pressor effects were enhanced, and large artery resistance was increased.

Acetylcholine↗
PubMed1989

Efficacy of exercise for end-stage renal disease patients immediately following high-efficiency hemodialysis: a pilot study.

Nine patients receiving maintenance high-efficiency hemodialysis were studied before and after a 12-week conditioning program to determine the efficacy of exercise immediately following hemodialysis. Each patient performed a combination of bicycle ergometry on the Schwinn Air-Dyne ergometer (SAE) and treadmill walking three times a week for a total exercise time of 15-35 min per session. A low-level Bruce treadmill test and an exercise test on the SAE were administered before and after training. Hematological, serum electrolyte, and serum lipid profiles were also determined before and after training. Following training, there were improvements in exercise capacities for both treadmill walking and ergometry on the SAE. Although a significant increase in serum apolipoprotein A1 was seen following exercise, no significant changes were observed for total cholesterol, low-density-lipoprotein cholesterol, high-density-lipoprotein cholesterol or apolipoprotein B. Additionally, no significant changes were seen in hematological parameters and serum electrolyte profiles following the exercise program. The 9 patients demonstrated an average compliance record of 74%. This study demonstrated that patients on high-efficiency hemodialysis can safely engage in an exercise program immediately following dialysis at intensities and frequencies that can improve their physical work capacities.

Aged↗
PubMed1989

Androgens affect the processing of secretory protein precursors in the guinea pig seminal vesicle. I. Evidence for androgen-regulated proteolytic processing.

The guinea pig seminal vesicle epithelium synthesizes and secretes four major secretory proteins (SVP-1-4). Previous work has established that these four proteins are cleaved from two primary translation products in a complex series of protein processing reactions. The present studies suggest that these protein processing reactions are regulated by androgens. In vitro labeling of seminal vesicle proteins revealed significant differences in the patterns of secretory protein intermediates produced by tissue from intact and castrated animals. Seminal vesicle tissue explants from castrated animals secreted a subset of the processing intermediates secreted by tissue from intact animals. The changes in the patterns of secretory protein intermediates became more pronounced with increasing time after castration, and were fully reversible by treatment of castrated animals with testosterone, suggesting that androgens were affecting the processing or secretion of secretory protein precursors. Amino-terminal protein sequencing of secretory protein processing intermediates that accumulate in the seminal vesicle lumen after castration suggests that the guinea pig seminal vesicle contains an androgen-regulated proteolytic processing activity.

Animals↗
PubMed1989

The small midline occipital encephalomeningocele: definition of a syndrome.

An unusual group of encephalomeningoceles is described. Two children were noted at birth to have a raised area of abnormal skin at the occipital midline. Both of these lesions were found to perforate the superior sagittal sinus and to end between the leaves of the falx cerebri, and to contain a small amount of abnormal cerebral tissue with no connection to either occipital lobe. Previous case reports are reviewed; these lesions are true encephalomeningoceles, rather than glial heterotopias. The embryology of such lesions is considered, and likely differs from the much more common occipital encephalocele arising from one or both occipital lobes.

Brain Diseases↗