Search PubMed⌕ Search

Biomedical subjects

S M Smith

Publications and source records attributed to S M Smith.

At least 343 records · Page 19Linked to original sources
PubMed1986

Synthesis of the small subunit of ribulose-bisphosphate carboxylase from genes cloned into plasmids containing the SP6 promoter.

DNA sequences encoding ribulose 1,5-bisphosphate carboxylase small subunit precursor from Pisum sativum L. have been transcribed from plasmids containing the SP6 promoter, and translated in a wheat germ cell-free system. The small subunit precursor polypeptide, its N-terminal leader sequence (transit peptide) and the mature small subunit have each been synthesized independently from three different plasmid constructs. The precursor polypeptide is imported into isolated pea chloroplasts and processed to the mature small subunit by a stromal proteinase. The mature polypeptide is neither imported, nor subject to proteolysis by stromal extracts. The transit peptide alone is very rapidly degraded by a stromal proteinase activity which can be inhibited by EDTA or 1,10-phenanthroline. The use of these gene constructs helps to establish the crucial role of the transit peptide in protein import into the chloroplast.

Base Sequence↗
PubMed1986

Injuries associated with three-wheeled, all-terrain vehicles, Alaska, 1983 and 1984.

From January 1983 through December 1984, twenty deaths and at least 534 injuries in Alaska were associated with three-wheeled, all-terrain vehicles. Age at death ranged from 12 to 53 years; 15 deaths (75%) were in the 15- to 34-year age group. Of the 20 fatalities, 12 (60%) might have been prevented had the riders been wearing a helmet. Alcohol use was detected or highly suspected as the major contributing cause of the fatal crash for 12 of 15 drivers and three of five female passengers. Potential risk factors for injuries associated with all-terrain vehicles include alcohol use, failure to use helmets, rider inexperience and inattention, and excessive speed.

Adolescent↗
PubMed1986

Polyamine distribution in the rat intestinal mucosa.

As the first step in a study of mucosal polyamine metabolism during intestinal adaptation, we have measured mucosal polyamine concentrations at different sites along the normal rat intestine. Putrescine, spermidine, spermine and cadaverine were measured by spectrofluorometric analysis after thin-layer chromatography of their dansylated derivatives. Spermidine was present in the largest amounts at each of the sampling sites. The ratio of the concentration of spermidine to that of spermine paralleled the established pattern of cellular proliferation in the normal intestine as did the putrescine concentration (nmol per 10 cm) which decreased from duodenum to colon. These results provide the essential background to an assessment of the role of polyamines in the intestinal adaptive response.

Animals↗
PubMed1986

Cephalosporin therapy for salmonellosis. Questions of efficacy and cross resistance with ampicillin.

The new cephalosporins should be explored for Salmonella septicemia efficacy, because of multiple-drug resistance, the high incidence of patient allergies to ampicillin and sulfamethoxazole-trimethoprim, and the limited number of antibiotics with proven efficacy. This study reports on six widely used cephalosporins: cephalothin, cefamandole, cefoperazone, cefoxitin, cefotaxime, and ceftriaxone with respect to in vitro killing of Salmonella. This in vitro activity was related to the stability of the agents to beta-lactamases. Cefoperazone was the least stable, followed by cefamandole and cephalothin. Cefoxitin, cefotaxime, and ceftriaxone were the most stable. The beta-lactamase-unstable agents permitted regrowth of beta-lactamase-producing salmonella within 36 hours. Standard susceptibility tests showed good inhibitory levels by these unstable agents at 18 hours, but the minimum inhibitory concentrations increased dramatically with longer incubation periods. Based on these results, past cephalothin failures for ampicillin-resistant Salmonella can be explained. Additionally, there should be a dichotomy of effectiveness in the new cephalosporins depending on their beta-lactamase stability. The stable cephalosporins deserve further clinical trials in the treatment of beta-lactamase-producing Salmonella infections.

Ampicillin↗
PubMed1986

Cryptococcal infections in patients with acquired immune deficiency syndrome.

Cryptococcus neoformans is a major pathogen in patients with acquired immune deficiency syndrome and was found to infect 13.3 percent of such patients seen at two medical centers. Serum cryptococcal antigen levels were as high as 1:2,000,000 and, despite therapy, often remained elevated. Antigen titers in the cerebrospinal fluid generally declined at an expected rate in the survivors. The significance of high antigen titers in the blood after a prolonged course of therapy with amphotericin B and 5-flucytosine is unknown.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Bacteremia and fungemia in patients with acquired immune deficiency syndrome.

Patients with acquired immune deficiency syndrome (AIDS) are known to have identifiable host defense deficiencies, especially deficiencies in cell-mediated immunity. They are at increased risk for developing infections of the bloodstream caused by Cryptococcus neoformans and Salmonella species. However, bacteremias caused by other enteric gram-negative rods and Pseudomonas aeruginosa are found less frequently in patients with AIDS than in patients without AIDS (P less than 0.001 and P less than 0.01, respectively). The findings of specific organisms in blood is consistent with the known types of host defense deficiencies in these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Use of D-lactic acid measurements in the diagnosis of bacterial infections.

This study explored the use of D-lactic acid as a marker for bacterial infections. D-Lactic was produced by frequently encountered human bacterial pathogens under anaerobic growth conditions; Bacteroides fragilis produced the largest amount. Orally administered D-lactic acid was absorbed from the intestines of rats and later found in measurable quantities in the blood and urine. Eunephric and anephric rats that received D-lactic acid intravenously showed similar quantities of this metabolite in the blood. These quantities are consistent with the distribution of D-lactic acid to total body water. Isolated liver and lung tissues from rats did not metabolize or produce D-lactic acid. Rats with experimentally induced, sublethal klebsiella peritonitis had D-lactic acidemia of 0.2 mM and 25.6 mM at 0 and 6 hr of infection, respectively. In a normal human, D-lactic acid was detected in the urine and blood after a subcutaneous injection of D-lactic acid, and pharmacokinetics of elimination similar to those of rats were found.

Anaerobiosis↗
PubMed1986

The effect of ciprofloxacin on methicillin-resistant Staphylococcus aureus.

Ciprofloxacin exhibited good in-vitro activity for methicillin-resistant Staphylococcus aureus with a MIC90 of 0.5 mg/l. The postantibiotic effect was 2.16 h. When ciprofloxacin was evaluated in combination studies with an aminoglycoside, none of the strains met the criterion of synergy as defined by FIC or FBC interaction indices of less than or equal to 0.25. However, killing kinetic experiments indicated that the combination of ciprofloxacin was synergistic for two of 12 strains with gentamicin and three of 12 strains with amikacin. Although the inoculum size had no effect on the rate of killing by ciprofloxacin, an increase in turbidity was noted when a high inoculum was tested. This increase in turbidity was due to the swelling of the staphylococci to several times their normal size and the formation of clusters of multicellular, incompletely divided staphylococci. If a high inoculum is used for susceptibility testing, this increase in turbidity could be misinterpreted as bacterial growth and could result in a false report of an elevated MIC.

Anti-Bacterial Agents↗
PubMed1986

In-vitro emergence of beta-lactam-resistant variants of Pseudomonas aeruginosa.

The frequency with which resistant variants could be found in Pseudomonas aeruginosa ATCC 27853 during growth in media with and without antibiotics was determined for ticarcillin, piperacillin, cefotaxime, latamoxef, cefoperazone, ceftriaxone, ceftazidime, aztreonam and imipenem. The resistance frequency was highest for ceftriaxone, cefotaxime, cefoperazone and piperacillin (up to 2 X 10(-4)) and lowest for ticarcillin, latamoxef, ceftazidime, aztreonam and imipenem (less than 10(-8)). The resistant variants showed cross-resistance to all of the beta-lactam antibiotics tested with the exception of imipenem. The MIC profiles of all variants were similar regardless of which antibiotic the cultures had been exposed to previously. Although all resistant variants produced and excreted cephalosporinases, increased resistance was demonstrated to both cephalosporinase-susceptible and cephalosporinase-stable beta-lactam antibiotics.

Anti-Bacterial Agents↗
PubMed1986

A Community-wide epidemic of hepatitis A in Ohio.

Between June 1, 1983 and August 30, 1984, an epidemic involving 313 cases of hepatitis A occurred in Muskingum County, Ohio. One hundred ninety-seven cases occurred in the city of Zanesville, with 34.7% of cases concentrated in two neighborhoods in the eastern part of the city. Case characteristics were similar to those reported in previous community-wide outbreaks, including a maximum attack rate among 5-9-year-olds and a very low attack rate in adults over 30 years. Case households were larger, and their members were less educated than the mean for households in the city. Forty-eight per cent of the cases reported exposures to other cases which temporally could have been the source of infection. A case-control study failed to show differences in several behavioral factors between case and control households, but did confirm that lower socioeconomic status was a risk factor for the disease. Broad use of immunoglobulin was effective in preventing clinical disease among family contacts, but did not stop the outbreak. This outbreak typifies a genre of hepatitis A epidemic transmitted from person to person in which exact routes of spread are poorly understood and control is difficult. Lower socioeconomic status may be a marker for some unidentified behaviors that promote hepatitis A transmission.

Adolescent↗
PubMed1986

Glyoxysomal Malate Synthase of Cucumber: Molecular Cloning of a cDNA and Regulation of Enzyme Synthesis during Germination.

A cDNA clone for the glyoxysomal enzyme malate synthase was isolated from a cDNA library made with polyadenylated RNA from the cotyledons of germinating Cucumis sativus L. This cloned DNA sequence was used as a probe to characterize changes in the amounts of malate synthase gene transcripts in cotyledons of cucumber seeds grown both in the light and in the dark. Malate synthase gene transcripts increase in amount to a peak at day 3 or day 4, and thereafter decline. In the light, this rate of decline is significantly greater than in the dark. Measurement of the changes in the amounts of malate synthase by assaying enzyme activity directly, and by immunological reaction with a specific antiserum indicate that the developmentally regulated synthesis of malate synthase in germinating cucumber is brought about primarily by changes in the amount of malate synthase gene transcripts, rather than through a control of translation. Similarly, the effect of light on the amount of malate synthase correlates precisely with its effect on the abundance of malate synthase gene transcripts.

Journal Article↗
PubMed1986

Ameloblastoma with myofibroblasts: first report.

A recurrent infiltrative ameloblastoma of the mandible with a predominantly "follicular pattern" of the epithelial component is studied. The stroma contains abundant myofibroblasts; these cells have been described in benign and malignant infiltrative processes. This raises the question of the relationship between the presence of myofibroblasts and the aggressive behavior of a neoplasm.

Ameloblastoma↗
PubMed1986

In vitro comparison of A-56619, A-56620, amifloxacin, ciprofloxacin, enoxacin, norfloxacin, and ofloxacin against methicillin-resistant Staphylococcus aureus.

Seven quinolone antibiotics were tested against 115 isolates of methicillin-resistant Staphylococcus aureus. The MICs for 90% of the strains tested were 0.5 microgram/ml for A-56619, A-56620, ciprofloxacin, and ofloxacin; 2.0 micrograms/ml for amifloxacin and enoxacin; and 4.0 micrograms/ml for norfloxacin. Killing kinetic studies showed a similar killing rate for all seven antibiotics.

Anti-Bacterial Agents↗
PubMed1986

Failure of vancomycin prophylaxis and treatment for Actinobacillus actinomycetemcomitans endocarditis.

Reported is a case of Actinobacillus actinomycetemcomitans endocarditis which developed after dental prophylaxis with vancomycin and erythromycin. In vitro results indicated that this isolate and 20 additional isolates were resistant to vancomycin and that potentially useful bactericidal antibiotics for the prophylaxis and treatment of A. actinomycetemcomitans infections included gentamicin, sulfamethoxazole-trimethoprim, cefotaxime, and ciprofloxacin.

Actinobacillus↗
PubMed1986

Comparative evaluation of identification systems for testing methicillin-resistant strains of Staphylococcus aureus.

Several commercial systems are available to distinguish between Staphylococcus aureus and the coagulase-negative species of the Micrococcaceae family. Four latex agglutination systems (Accu-Staph, SeroSTAT, Staphaurex, and Staphylatex) and two hemagglutination systems (Hemastaph and Staphyloslide) were compared for their performance in the rapid identification of 232 isolates of staphylococci, including 114 of methicillin-resistant S. aureus. Accu-Staph, Staphaurex, and Staphyloslide correctly identified 100% of the methicillin-resistant S. aureus isolates; Hemastaph and Staphylatex, 99.1%; and SeroSTAT, 94.7%. Most reactions were easy to interpret, although 15% of the SeroSTAT reactions were weak. Autoagglutination occurred only with isolates of coagulase-negative staphylococci. False-positive reactions were rare and occurred only with systems which did not detect autoagglutination. Five of these six systems appear to be adequate for the rapid identification of S. aureus, including methicillin-resistant isolates.

Coagulase↗
PubMed1986

Yield of bone marrow culture in the diagnosis of infectious diseases in patients with acquired immunodeficiency syndrome.

The yield in cultures of bone marrow aspirations or biopsies was determined in 50 patients with acquired immunodeficiency syndrome. Most patients were febrile and had no identifiable source of infection. Concurrent stool, urine, and blood samples were also cultured. The bone marrow aspiration and biopsy procedures produced no complications and enabled a microbiological diagnosis to be made in 42% of the cases. Granuloma formation was not seen in any of the infected bone marrow specimens despite the fact that mycobacteria were seen in abundance in some. Bone marrow culture is a valuable low-morbidity invasive procedure in the evaluation of febrile patients with acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1986

The detection of atrial and ventricular septal defects with electrocardiographically synchronized magnetic resonance imaging.

To evaluate the detectability of cardiac septal defects by electrocardiographically synchronized (ECG-gated) magnetic resonance imaging (MRI), 48 subjects were imaged, including 18 normal and 30 abnormal subjects in whom 22 ventricular septal defects (VSDs) and nine atrial septal defects (ASDs) had been diagnosed angiographically. Two radiologists with ECG-gated cardiac MRI experience read the scans in a blinded fashion, and the results were evaluated by receiver operator characteristic curve analysis. The detectability of VSDs appeared greater than that of ASDs, although statistical significance at the .05 level was not achieved. The reported sensitivity and specificity of echocardiography in the detection of VSDs is comparable to MRI, whereas echocardiography probably is superior to MRI for detection of ASDs. Although MRI is potentially valuable in the diagnosis of various complex congenital cardiac defects, echocardiography is probably superior in the detection of VSDs and ASDs.

Adolescent↗