Search PubMed⌕ Search

Biomedical subjects

C M Smith

Publications and source records attributed to C M Smith.

At least 145 records · Page 8Linked to original sources
PubMed1992

Mutations in topA interfere with the inducible expression of DNA damage response loci in Salmonella typhimurium.

Strains of Salmonella typhimurium deficient in topoisomerase I activity (topA mutants) are UV sensitive and non-mutable (Overbye and Margolin: J Bacteriol 146:170-178, 1981). Using lac-operon fusions to DNA damage inducible (din) loci we investigated whether these observations could be explained by an inability of topA strains to efficiently induce DNA damage responses. Mitomycin C (MMC)-induced expression of lac-operon fusions to uvrB and to a second SOS locus, din-9, was largely eliminated in topA bacteria. The inducible expression of several other din-fusions was also diminished. This inducibility defect was mimicked by growth of din-9 topA+ bacteria in media of high osmolarity, a condition that leads to increased DNA supercoiling. Inhibitors of DNA gyrase efficiently induced din-9 in topA bacteria. Together, these results suggest that the topA effect on din expression may be mediated at the level of DNA supercoiling. The sensitivities of a number of din-fusions to topA paralleled the degree to which they were repressed by excess LexA, suggesting that mutations in topA might influence LexA-operator interactions and/or increase lexA expression.

Bacterial Proteins↗
PubMed1992

Acquisition of coccidioidomycosis at necropsy by inhalation of coccidioidal endospores.

Coccidioidomycosis is accepted as being noncontagious because the infectious arthroconidial form of Coccidioides immitis is not produced in humans and other mammalian hosts. However, disseminated coccidioidomycosis developed in a veterinarian who autopsied a horse with disseminated disease but without draining lesions or productive cough. We postulate transmission occurred by inhalation of tissue-phase endospores aerosolized in the course of dissection.

Adult↗
PubMed1992

Preparation and stability of a radioiodinated pentamidine isethionate analog.

Iodopentamidine isethionate was heated for 70 min with [I-123]- or [I-125]-sodium iodide and ammonium sulphate in the absence of solvent at 140 degrees C. The product, [I-123]- or [I-125]-iodopentamidine isethionate, was purified by ion exchange chromatography. It was stable at room temperature in aqueous solution over several days, in human blood in vitro for at least 24 h (showing no binding to either cells or proteins), in urine over at least 15 h, and during nebulization in both ultrasonic and jet nebulizers.

Aerosols↗
PubMed1992

Influence of calcium antagonists on thrombin-induced calcium mobilization and platelet-vessel wall interactions.

Elevation of cytosolic ionized calcium plays a critical role in human platelet activation. We have evaluated three well-characterized calcium antagonists for their ability to prevent thrombin-induced calcium mobilization in Fura 2 AM-loaded platelets and also their ability to inhibit platelet-vessel wall interactions. Thrombin (0.2 U/ml) caused significant elevation of cytosolic calcium (basal 84 +/- 18, activated 546 +/- 76 nM; n = 3). Verapamil, diltiazem, and nifedipine (100 microM) did not exert any inhibitory effect on thrombin-mediated calcium elevation. Untreated platelets perfused through a Baumgartner chamber containing a rabbit aorta preparation reacted with exposed and denuded subendothelium. The percentage of the total area covered by control platelet thrombi was 39.6 +/- 3.4. Diltiazem and Nifedipine significantly reduced the percentage of area covered by platelet thrombi, but the drugs were not as effective as aspirin (8.2 +/- 1.4). Calcium antagonists studied did not inhibit thrombin-stimulated elevation of cytosolic calcium in blood platelets. Although these drugs have been shown to prevent in vitro platelet aggregation and offer some protection against risks for atherosclerosis and thrombosis, they failed to significantly inhibit platelet-vessel wall interactions leading to formation of spread platelets and aggregates.

Aspirin↗
PubMed1992

Anaerobic and aerobic power in arms and legs of elite senior wrestlers.

UNLABELLED: The purpose of this study was to characterize anaerobic power and aerobic power (power at peak oxygen uptake, or peak VO2) of elite senior (post-collegiate) wrestlers. Subjects (n = 14) from the U.S. national senior freestyle and Greco Roman wrestling teams were evaluated at separate tests using cycle ergometry for peak VO2 of the arms, peak VO2 of the legs, arm anaerobic peak power, and leg anaerobic peak power. Power output at peak VO2 was recorded for each test and compared to the anaerobic power of the appropriate body segment. The results (mean +/- SD) showed that wrestlers produced 2.3 +/- 0.4 W.kg body weight-1 at arm peak VO2 (43.7 +/- 4.6 ml.kg body weight-1. min-1), 4.2 +/- 0.5 W.kg body weight-1 at leg peak VO2 (50.9 +/- 5.1 ml.kg body weight-1.min-1), arm PP of 7.7 +/- 1.0 W.kg body weight-1, and leg PP of 10.5 +/- 1.7 W.kg body weight-1. Comparing power output during anaerobic and aerobic tests, the subjects performed at 3.4 +/- 0.6 times their peak oxygen uptake during arm anaerobic ergometry, whereas leg anaerobic peak power was 2.7 +/- 0.4 times the power at peak oxygen uptake for the legs (p < 0.05 for difference between ratios). CONCLUSION: relative to aerobic power, elite senior wrestlers may produce power anaerobically in the upper body at significantly higher levels than in the lower body.

Adult↗
PubMed1992

Enumeration of subgingival species on primary isolation plates using colony lifts.

This study evaluated the feasibility of using a colony lift method and DNA probes to enumerate bacterial species cultured on primary isolation plates. Fourteen digoxigenin-labeled whole chromosomal DNA probes representing 12 subgingival species were validated by hybridization with colony lifts prepared from 249 reference strains of 51 species grown on Trypticase soy agar plates supplemented with 5% sheep blood. Colonies of reference strains were lifted onto Nytran filters from plates and treated to lyse cells, remove cellular proteins, denature and fix microbial DNA to the filters. Positive reactions were detected with an anti-digoxigenin antibody conjugated to alkaline phosphatase and revealed by bromo-chloro-indolyl phosphate and nitroblue tetrazolium. Cross-reactions were not observed for 13/14 probes, but 2 strains of Streptococcus mitis reacted with the probe to Streptococcus sanguis II. Subgingival plaque samples were taken by means of a sterile curette from mesiobuccal surfaces of teeth present in each of 26 subjects with differing periodontal disease states. Samples were dispersed, diluted, plated and incubated anaerobically for 7 d at 35 degrees C. Colonies were lifted as described above. Filters were cut into sections and hybridized with the 14 digoxigenin-labeled DNA probes. The probes were used to enumerate the test species and the total number of isolates was determined in 711 plaque samples. The colony lift method and DNA probes provided a sensitive, economical and quantitative method for enumerating cultivable microbial species in subgingival plaque samples. In addition, the amplification provided by growing the organisms on agar plates facilitated determination of numbers of organisms in small plaque samples, such as those from healthy sites.

Actinomyces↗
PubMed1992

Tissue kallikrein is associated with prolactin-secreting cells within human growth hormone-secreting adenomas.

Tissue kallikrein is a serine protease which may be involved in the intracellular processing of prolactin in the anterior pituitary gland. The expression of tissue kallikrein, in the rat, is promoted by oestrogen and inhibited by dopamine. Human and rat prolactinomas contain markedly increased amounts of tissue kallikrein; this is comparatively reduced if patients are pretreated with the dopamine agonist, bromocriptine, before surgery. Some GH-secreting adenomas are mixed and also contain prolactin-secreting cells. We therefore investigated 27 GH-immunostaining human pituitary adenomas for the presence of immunoreactive tissue kallikrein. Sixteen of the adenomas had positive immunostaining for prolactin; eight of these patients had associated clinical hyperprolactinaemia before the tumour was removed. Tissue kallikrein immunoreactivity was found in ten adenomas, all of which also had prolactin immunopositivity. There was a close relationship between the percentage of cells staining for prolactin and tissue kallikrein but not for GH. A further eight adenomas had patchy positivity, i.e. less than 1% of cells immunostained for tissue kallikrein and six of these also had some prolactin-staining cells. Nine out of eleven purely GH-staining adenomas had no tissue kallikrein immunopositivity, the remaining two showing patchy staining. A review of bromocriptine responsiveness, as assessed by mean GH hormone levels during oral glucose tolerance tests before and after therapy was commenced, indicated that patients with adenomas which stained for prolactin and tissue kallikrein were more likely to respond to bromocriptine than those which failed to do so.

Adenoma↗
PubMed1992

Urinary leukotriene E4 in bronchial asthma.

Leukotriene E4 (LTE4) is excreted into the urine in a relatively constant proportion of 4-7% when either leukotriene C4 (LTC4) or LTE4 is intravenously infused, regardless of the magnitude of the infused dose. Measurement of LTE4 in urine is, therefore, a convenient and non-invasive method for assessing changes in the rate of total body sulphidopeptide leukotriene production. We assayed urinary LTE4 in 17 normal subjects, 31 subjects with asthma without aspirin sensitivity, and 10 aspirin-sensitive subjects. The relationship between urinary LTE4 and nonspecific bronchial hyperresponsiveness, as assessed by the provocative dose producing a 20% fall in forced expiratory volume in one second (PD20) to inhaled histamine, was examined in 19 non-aspirin-sensitive asthmatic subjects. The urinary LTE4 values were log-normally distributed. Urinary LTE4 was detected in 28 of the 31 non-aspirin-sensitive asthmatic subjects, and the geometric mean (95% confidence interval (CI) of 43 (32-57) pg.mg-1 creatinine was no different to that of 34 (25-48) pg.mg-1 creatinine measured in the normal subjects. The geometric mean of 101 (55-186) pg.mg-1 creatinine measured in the aspirin-sensitive asthmatics was significantly higher than that measured in the normal subjects (p less than 0.005) and in the asthmatic subjects who were non-aspirin-sensitive (p less than 0.002), but there was considerable overlap between the three groups. There was no relationship between urinary LTE4 and PD20, or between urinary LTE4 and baseline forced expiratory volume in one second (FEV1) (% predicted). Thus, measurement of LTE4 in a single sample of urine will not predict the extent of bronchial hyperresponsiveness or degree of airflow obstruction.

Adult↗
PubMed1992

Effects of pentoxifylline on equine neutrophil function and flow properties.

Pentoxifylline has been reported to improve peripheral vascular circulation by altering the flow properties of blood. To determine if the hemorrheological effects of pentoxifylline were mediated by alterations in neutrophil function and/or flow properties, we evaluated the drug's effects on equine neutrophils in vitro. Pentoxifylline, at a concentration of 1 x 10(-1) M, but not at concentrations of 1 x 10(-6) M to 1 x 10(-2) M, markedly suppressed neutrophil superoxide production, zymosan phagocytosis and adherence to nylon wool. Pentoxifylline failed to improve neutrophil filterability through 3 mu polycarbonate filters at any concentration tested. We conclude that equine neutrophil function and flow properties are unlikely to be affected by pentoxifylline concentrations achievable in vivo.

Animals↗
PubMed1992

Alcohol consumption in the guinea pig is associated with reduced megakaryocyte deformability and platelet size.

Mild thrombocytopenia is common in alcoholic individuals. Ethanol appears to impair platelet production primarily by affecting the maturing megakaryocyte compartment. We recently showed that guinea pigs have an unusually large number of elongated platelet forms even under conditions of steady-state thrombopoiesis, and a portion of their mature (stage IV) megakaryocytes yield extremely long extensions on micropipette aspiration. This study evaluates the effect of a moderately low level of ethanol consumption by guinea pigs on platelet size and form and megakaryocyte deformability. Adult Duncan Hartley guinea pigs took ethanol 2.5% (vol/vol) ad libitum for 4 weeks under environmentally controlled conditions, never reaching detectable blood ethanol levels (< 0.01%); the platelet count fell 16%. Elongated platelet forms constituted 29% of the cardiac puncture platelets of control animals, but only 3% of the cardiac puncture platelets of animals given ethanol; discocytic platelets of ethanol-treated animals were also significantly smaller. Individual stage III and IV megakaryocytes were aspirated into 5 microns diameter micropipettes by stepwise increment in pressure from 10 to 200 cm water. The extensions drawn from megakaryocytes of ethanol-exposed animals were significantly shorter than the extensions from control megakaryocytes. Extremely long extensions over 50 microns in length were drawn from 21% of the control megakaryocytes but less than 1% of ethanol-exposed megakaryocytes. Moderately low level ethanol consumption was associated with reduced platelet count and size, along with rigidity of mature megakaryocytes in guinea pigs. Few ethanol-exposed megakaryocytes yielded extremely long cell extensions, nor were elongated platelet forms prevalent in the circulation of animals given ethanol.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗
PubMed1992

Furosemide-induced electrolyte depletion associated with echinocytosis in horses.

Echinocytes have been incriminated in the pathogenesis of exertional diseases in horses. To evaluate the hypothesis that echinocytes are dehydrated erythrocytes, we decreased blood sodium and potassium concentrations in 4 horses by administering furosemide (1.0 mg/kg of body weight, q 12 h) for 2 days and we monitored CBC, serum and erythrocyte sodium and potassium concentrations, and echinocyte numbers. Serum sodium concentration decreased progressively over the 48 hours of furosemide administration, then returned to near baseline concentration at 168 hours. A statistically significant decrease (P < 0.05) in serum potassium concentration was observed at 24, 48, and 72 hours after initial furosemide administration, and remained less than the baseline value at the end of the study. Mean erythrocyte potassium concentration decreased rapidly and remained low at the end of the study. Minimal changes were observed in erythrocyte sodium concentration during the first 72 hours after furosemide administration, but the value was significantly (P < 0.05) increased at 168 hours. Type-I and type-II echinocyte numbers increased by 4 hours after furosemide administration and persisted throughout the study. Type-III echinocytes were not seen in baseline samples, but numbers increased only modestly after furosemide administration. Administration of epinephrine to well-hydrated horses increased echinocyte numbers only minimally, indicating that splenic contraction was not the likely cause for the furosemide-associated increase. To determine whether the decrease in erythrocyte potassium concentration and increase in sodium concentration was caused by furosemide acting directly on the erythrocyte membrane, we quantified erythrocyte potassium and sodium concentrations before and after incubation with furosemide in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Tissue kallikrein and the effect of bromocriptine in human prolactin and growth hormone-secreting pituitary adenomas.

Tissue kallikrein (TK) is present and co-localises with prolactin producing cells in human prolactinoma and mixed growth hormone (GH) and prolactin-secreting pituitary adenomas. TK immunoreactivity was reduced or absent in these types of adenomas from patients who had received the dopamine agonist, bromocriptine before surgery. Pure GH secreting adenomas had no TK immunoreactivity.

Adenoma↗
PubMed1992

Effects of furosemide and pentoxifylline on blood flow properties in horses.

The effects of furosemide and pentoxifylline on blood flow properties in horses were investigated. Hematologic and rheologic changes were examined in 4 horses before and 3 minutes after administration of epinephrine (1 mg, IV). The next day, hemorheologic changes were determined before and 3 hours after administration of furosemide (1 mg/kg of body weight, IM), and after administration of epinephrine at the sampling at 3 hours. Hematologic and rheologic changes were evaluated weekly in 3 horses given pentoxifylline (8.5 mg/kg, q 12 h, PO) for 28 days. In addition, hemorheologic responses to epinephrine were determined on days 0, 14, and 28 of pentoxifylline treatment. Neutrophil filtration studies were also performed 2 hours after IV administration of pentoxifylline (8.5 mg/kg). Postepinephrine values for PCV, RBC and WBC counts, and blood viscosity were greater than preepinephrine values. Erythrocyte sedimentation rates decreased after epinephrine, whereas RBC filterability did not change. Treatment with furosemide was associated with increases in mean RBC hemoglobin concentration and blood viscosity. Filterability of RBC did not change. Treatment with pentoxifyllie resulted in an increase in RBC filterability and erythrocyte sedimentation rate and a decrease in PCV; however, mean values for hematocrit and RBC count did not change. Treatment with pentoxifylline did not result in a change in resting blood viscosity, but markedly reduced the postepinephrine increase in blood viscosity. Neither IV nor orally administered pentoxifylline had an effect on neutrophil filtration. It was concluded that pentoxifylline has beneficial effects on RBC filterability and postepinephrine changes in blood viscosity, which may contribute to improvements of microcirculatory blood flow. In addition, furosemide may exacerbate exercise-associated hyperviscosity in horses.

Animals↗
PubMed1992

Evaluation of hemorheologic variables as implications for exercise-induced pulmonary hemorrhage in racing thoroughbreds.

Hematologic and rheologic changes were examined in 49 Thoroughbreds before and after competitive racing. Mean postrace values for RBC count, hemoglobin concentration, and PCV increased by 58 to 61%, whereas blood viscosity increased 2 to 3 times. Postrace echinocyte numbers were 162% greater than prerace values. Smaller, but statistically significant, changes were found for mean corpuscular hemoglobin concentration, red cell distribution width, plasma total protein concentration, total WBC count, neutrophil count, and lymphocyte count. Variables measured did not predict whether a horse was a bleeder not treated with furosemide, a bleeder treated with furosemide, or a nonbleeder.

Animals↗
PubMed1992

Microbial contamination of hydrophilic contact lenses. Part I: Quantitation of microbes on patient worn-and-handled lenses.

We cultured Soflens (polymacon) contact lenses to determine the number of microorganisms present following normal patient wear and handling just prior to disinfection. Total protein deposited was determined for the companion lens from each patient. A random population of 109 adapted soft contact lens patients participated in the study. Some patients participated more than once, resulting in a total of 196 lenses being cultured and 195 lenses analyzed for total protein. The left lens was cultured immediately. The right lens was extracted at 70 degrees C in sodium hydroxide, and the total protein in the extract determined using a modified Lowry protein assay. The mean protein deposition per lens was 3.4 micrograms (median 2 micrograms per lens; range less than 1 to 78 micrograms/lens). Microorganisms were cultured from 95% of the lenses. The mean bacterial count (in colony forming units per lens) was 2,482 (median: 123; range less than 3 to 150,000). Fungal contamination was found on 11% of the lenses at very low levels (3-9 yeast/lens and 3-18 mold/lens). Statistical analysis found no significant relationship between bacterial bioburden and any of the study parameters, including total protein, lens age, or subjective evaluation of lens cleanliness.

Bacteria↗
PubMed1991

Immunohistochemical localization of a calcium pump and calbindin-D28k in the oviduct of the laying hen.

The localization of a plasma membrane calcium pump in the oviduct of the laying hen was investigated by immunohistochemical techniques, utilizing a monoclonal antibody (5F10) produced against the human erythrocyte calcium pump. This antibody was shown to react with an epitope of the pump in oviductal tissue, and prominent staining was observed on the microvilli of the tubular gland cells of the hen shell gland (uterus) and the isthmus. The Ca2+ pump was not detectable in the infundibulum or the magnum. Calbindin-D28k, also localized by immunohistochemical means, was observed to be present in the tubular gland cells of the shell gland and the distal isthmus (adjacent to shell gland) but not in either the proximal isthmus (adjacent to the magnum), the magnum or the infundibulum. The localization of the Ca2+ pump in the oviduct corresponds to known sites of mineral deposition during egg shell formation. The distribution of calbindin-D28k differed, co-localizing with the Ca2+ pump in the shell gland and distal isthmus but not in the proximal isthmus. This might reflect a greater rate of active Ca2+ secretion in the distal isthmus and shell gland as compared to the proximal isthmus.

Animals↗