Search PubMed⌕ Search

Biomedical subjects

D S Smith

Publications and source records attributed to D S Smith.

At least 19 recordsLinked to original sources
PubMed1992

Presence of paralytic shellfish poisoning toxins and soluble proteins in toxic butter clams (Saxidomus giganteus).

Butter clams obtained from a variety of locations along the northern British Columbia coast were assayed for the presence of individual paralytic shellfish poisoning toxins (PSPT) by HPLC and total PSPT toxicity using the mouse bioassay. Specific organs, namely the siphon, adductor muscle, foot and mantle were examined for soluble antigens that crossreacted with crab Saxitoxin-Induced Protein (SIP) using immunochemical (Western blotting) techniques. Butter clams containing high concentrations of PSPT also had several proteins that crossreacted with crab anti-SIP serum. In particular, soluble proteins with distinctly different molecular weights were found in the siphon and foot, respectively, in toxic shellfish. These proteins were absent in nontoxic butter clams. The concept of using PSPT-induced proteins in the butter clam as a screen for identifying toxic shellfish is introduced.

Animals↗
PubMed1992

Agraphia in dementia of the Alzheimer type.

This study describes graphic errors made in writing a simple sentence in 368 healthy older adults and individuals in different stages of dementia of the Alzheimer type. Errors of agraphia were present in both healthy and demented people and, in general, increased with the severity of dementia. The errors of agraphia were not correlated with measures of aphasia or psychometric measures of language and motor performance. Writing skill may represent procedural memory, and agraphia errors indicate alterations in long-term memory in dementia of the Alzheimer type.

Aged↗
PubMed1992

Cross-reacting antigens in the butter clam (Saxidoma giganteus) and their relationship to total paralytic shellfish poison toxicity.

A specific protein with an apparent mol. wt of 23,000 was identified in foot homogenate derived from paralytic shellfish poisoning (PSP) contaminated butter clams and was found to cross-react with crab-saxitoxin-induced protein (SIP) antiserum. Antiserum, once cross-absorbed against non-toxic shellfish material, was incubated with tissue homogenate derived from 52 butter clams with varying total PSP toxicities in a prototype ELISA. A significant (r = 0.83; P less than 0.001) correlation existed between soluble clam antigen content in foot homogenate and total PSP toxicity; the latter measured by the mouse lethality bioassay. From the ELISA results, a soluble antigen threshold of 0.1% total protein was successfully used to distinguish between PSP toxic and non-toxic butter clams. It is proposed that this type of screening assay could be used in conjunction with the standard mouse bioassay to increase PSP monitoring and potentially reduce unnecessary animal testing.

Animals↗
PubMed1992

Effects of rectal examination, prostatic massage, ultrasonography and needle biopsy on serum prostate specific antigen levels.

Measurement of serum prostate specific antigen (PSA) is commonly used to evaluate the prostate gland in a variety of clinical settings. We examined the effects of prostatic manipulations, including digital rectal examination, prostate massage, transrectal ultrasonography and transrectal needle biopsy, on serum PSA levels in 199 men. We detected no clinically significant difference between serum PSA levels obtained immediately before and at 5 or 90 minutes after rectal examination in 43 men. We observed falsely increased PSA levels (to greater than 4 ng./ml., Tandem-R) in 1 of 17 men (6%) following prostatic massage and in 3 of 27 men (11%) following ultrasonography. Transrectal needle biopsy caused an immediate increase in serum PSA in 92 of 100 men. In 29 of these 92 men (32%) when followed weekly serum PSA levels did not return to baseline as expected according to the published serum PSA half-life of 2 to 3 days. Biopsies taking 3 or fewer cores (7 patients) resulted in a smaller increase in serum PSA (mean 1.63 +/- 1.12 times the baseline level versus 6.24 +/- 1.10 times baseline, p less than 0.03) and a proportionally shorter duration of PSA elevation (mean 1.43 +/- 0.48 weeks versus 2.13 +/- 0.14 weeks, p = 0.20) than those taking 4 or more cores (93 patients). Prostate size and the presence of cancer had no influence on the duration of PSA elevation following biopsy. We conclude that digital rectal examination, prostatic massage and ultrasonography have minimal effects on serum PSA levels in most patients. However, prostatic needle biopsy usually causes marked elevations of serum PSA levels with a persistent PSA leak into the blood stream lasting longer than expected from the serum half-life of PSA in approximately 25% of the patients.

Antigens, Neoplasm↗
PubMed1992

Clinical predictors of bacterial versus aseptic meningitis in childhood.

STUDY OBJECTIVE: To assess the reliability of meningeal signs and other physical findings in predicting bacterial and aseptic meningitis at various ages. DESIGN: Children requiring lumbar puncture were evaluated prospectively for meningeal signs and other physical parameters before lumbar puncture. SETTING: Emergency department of Children's Hospital of Wisconsin. PARTICIPANTS: One hundred seventy-two children, aged 1 week to 17 years, with meningitis (53 bacterial and 119 aseptic). MEASUREMENTS AND MAIN RESULTS: Nuchal rigidity was present in 27% of infants aged 0 to 6 months with bacterial meningitis versus 95% of patients 19 months or older (P = .0001). Three percent of infants 0 to 6 months old with aseptic meningitis had nuchal rigidity versus 79% of patients 19 months or older (P = .0005). Seventy-two percent of infants 12 months of age or younger with bacterial meningitis has at least one positive meningeal sign versus 17% of infants with aseptic meningitis (P = .0001). Eighty-five percent of children older than 12 months with meningitis had at least one positive meningeal sign, 93% with bacterial meningitis, and 82% with aseptic meningitis. CONCLUSION: Despite a lack of meningeal signs, a high index of suspicion for meningitis is essential when evaluating the febrile infant 12 months of age or younger.

Adolescent↗
PubMed1992

Urinary cotinine fluoroimmunoassay for smoking status screening adapted to an automated analyser.

A polarization fluoroimmunoassay for cotinine, a major metabolite of nicotine, has been adapted for fully automated screening of urine samples on the Abbott TDx analyser. The method has sensitivity and specificity suitable for the discrimination of active smokers from non-smokers (including passive smokers) by application of a cut-off at 0.5 mg l-1 of total urinary cotinine. Most active smokers' urine gave results over 1 mg l-1, whereas apparent levels in non-smokers were 0.08 mg l-1 or lower. A result for one sample can be obtained in about 5 min and a throughput of 80 samples h-1 can be maintained for large-scale screening applications.

Adult↗
PubMed1992

The role of abdominal x-rays in the diagnosis and management of intussusception.

The management of intussusception requires early diagnosis and reduction with either barium enema or surgical intervention. Supine and erect abdominal radiographs are often obtained prior to ordering a barium enema. In many pediatric centers, the critical, initial interpretation of these radiographs is made by nonradiologists and, in most instances, by pediatric emergency physicians. We determined the sensitivity and specificity of abdominal radiographs in diagnosing intussusception when interpreted by these physicians. Six full-time pediatric emergency physicians evaluated 126 radiographs from 42 patients with intussusception, 42 in whom the disease was clinically suspected but ruled out, and 42 in whom the final radiology report was "normal." These were presented to pediatric emergency physicians in a blinded, randomized sequence without any additional clinical information. These physicians then identified patients for whom they would proceed to barium enema. The mean sensitivity was 80.5% (range, 71-93%), and the mean specificity was 58% (range, 48-69%). This compares favorably to the sensitivity of signs and symptoms, and we conclude that plain and upright abdominal films are a useful adjunct for the clinician evaluating patients for suspected intussusception.

Barium Sulfate↗
PubMed1992

Keeping community college faculty current in physiology through utilization of health science center expertise.

The maintenance of current knowledge in physiology in community colleges is very difficult to accomplish. The absence of a research environment, limited library facilities, and heavy teaching loads often result in the instructor utilizing the teaching textbook as the primary source of information. A cooperative program between The University of Texas Health Science Center at San Antonio and San Antonio Community College has been developed in which the Health Science Center faculty present updated seminars in physiology topics for the community college faculty. This program has been in existence for three years and has proved to be very effective in improving the quality of the physiology curriculum at the community college.

Curriculum↗
PubMed1992

Zinc gluconate and the common cold: a controlled clinical study.

A report in 1984 on the success of zinc gluconate against common cold symptoms could not be confirmed in three subsequent studies, which are now known to have used formulations that inactivated zinc. A non-chelating formulation including glycine, which releases 93% of contained zinc into saliva, was tested in a randomized, placebo-controlled, double-blind trial in 73 young adults. Efficacy was recorded in symptom diaries using a symptom severity rating. Patients' symptoms first appeared 1.34 days prior to entry to the study in both groups. Disappearance of symptoms occurred after an additional 4.9 days for zinc-treated patients versus 6.1 days for placebo-treated patients. A difference was noted in the efficacy of treatment if it was started 1 day after symptom onset: cold duration was an additional 4.3 days in zinc-treated patients compared with 9.2 days for placebo-treated patients. Cough, nasal drainage and congestion were the symptoms most affected, and only mild side-effects were noted.

Adult↗
PubMed1991

Measurement of prostate-specific antigen in serum as a screening test for prostate cancer.

BACKGROUND: Prostate-specific antigen (PSA) is secreted exclusively by prostatic epithelial cells, and its serum concentration is increased in men with prostatic disease, including cancer. We evaluated its usefulness in the detection and staging of prostate cancer. METHODS: We measured serum PSA concentrations in 1653 healthy men 50 or more years old. Those with PSA values greater than or equal to 4.0 micrograms per liter then underwent rectal examination and prostatic ultrasonography. Ultrasound-directed prostatic needle biopsies were performed in the men with abnormal findings on rectal examination, ultrasonography, or both. The results were compared with those in 300 consecutively studied men 50 or more years old who underwent ultrasound-directed biopsy because of symptoms or abnormal findings on rectal examination. RESULTS: Serum PSA levels ranged from 4.0 to 9.9 micrograms per liter in 6.5 percent of the 1653 men (107). Nineteen of the 85 men in this group (22 percent) who had prostatic biopsies had prostate cancer. Serum PSA levels were 10.0 micrograms per liter or higher in 1.8 percent of the 1653 men (30). Eighteen of the 27 men in this group (67 percent) who had prostatic biopsies had cancer. If rectal examination alone had been used to screen the men who had biopsies, 12 of the 37 cancers (32 percent) would have been missed. If ultrasonography alone had been used to screen these men, 16 of the 37 cancers (43 percent) would have been missed. Serum PSA measurement had the lowest error rate of the tests, and PSA measurement plus rectal examination had the lowest error rate of the two-test combinations. CONCLUSIONS: The combination of measurement of the serum PSA concentration and rectal examination, with ultrasonography performed in patients with abnormal findings, provides a better method of detecting prostate cancer than rectal examination alone.

Age Factors↗
PubMed1991

Escherichia coli bacteremia in children. A review of 91 cases in 10 years.

We reviewed 91 cases of pediatric Escherichia coli bacteremia during a 10-year period. Thirty one patients were afebrile; a significantly greater proportion of these patients were aged less than 1 month, had ampicillin-resistant E coli isolates, or had persistent bacteremia 24 hours after initiating antibiotic therapy. Infection was community acquired in 65 cases; associated urinary tract infection was six times more common in this setting than in nosocomially acquired infections. In 85 cases at least 1 underlying medical condition/focus of infection was identified at the time the positive blood culture was obtained, the most common were immune deficiency states (38 cases), urinary tract infection (29 cases), and lesions of the gastrointestinal tract (27 cases). Polymicrobial bacteremia occurred in five cases. Twelve patients died; significantly associated with death were hypotension requiring pressor therapy, presence of a central venous catheter, and neutropenia.

Adolescent↗
PubMed1991

The detection of cytochrome oxidase heme iron and copper absorption in the blood-perfused and blood-free brain in normoxia and hypoxia.

The resolution of cytochrome and hemoglobin changes in in vivo rat and cat brains has required studies over wide wavelength ranges (580-1100 nm) with a novel spectroscopic technique using blood-free and blood-perfused brains. Tissue oxygen was varied from physiological levels to 0 and hematocrits were varied from normal to less than 1%. The experimental results were subjected to a multicomponent analysis using the Beer-Lambert law. At normal hematocrits, the oxygen saturation of hemoglobin in the brain was found to be 30-50% in rats and cats, indicating that the optical method responded primarily to the saturation of the venous ends of the capillary beds. With low hematocrits, both brains showed the absorption band of reduced cytochrome c, the iron component of cytochrome aa3, plus the absorption band of the oxidized copper component. In cat brains, the background absorption changed at all wavelengths. Thus, no isosbestic points were observed in the spectra. In rat brains, however, they were readily observed. The "overtones" of water absorption in the NIR region were found to be significant in the difference spectra of the cat brain, but not in the rat brain. Parallel absorbance changes in the heme and copper components of cytochrome aa3 were obtained in rat and cat brains during the normoxic-hypoxic transition. The ratio of the iron absorbance at 605 nm to the copper absorbance at 830 nm is much smaller in both brains than the in vitro value due to the shorter path length of photon migration at the shorter wavelengths.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Age dependence of steady state mitochondrial oxidative metabolism in the in vivo hypoxic dog brain.

Mitochondrial bioenergetics were investigated in newborn, neonatal and adult dog brains during normoxia and hypoxia. The ratio of the rate of ATP synthesis to the maximum synthesis rate (V/Vmax), phosphorylation potential, [ADP] and PCr/Pi, were used to evaluate age related mitochondrial hypoxic tolerance. These indicators were calculated from the phosphorus compounds measured by in vivo 31P MRS quantitatively using ATP as an internal reference. Indicators and substrates of mitochondrial function, V/Vmax, ADP, and Pi reached a peak value during the neonatal (3-21 days) period of development, suggesting that the oxidative metabolism of the neonate is more vulnerable to stress when compared to newborns and adults. Distinction among newborns and neonates became apparent during hypoxia. Newborns (0-2 days old) showed substantial tolerance by maintaining V/Vmax until exposure to severe hypoxia. Older neonates (3-21 days old) showed increases in V/Vmax, [Pi] and [ADP] under less than severe conditions of hypoxia. Adults exhibited low V/Vmax values even during exposure to severe hypoxia, further indicating that mitochondrial oxidative processes are more stable in adults than in newborns and neonates. This study provides evidence that newborns and adults are more capable of maintaining mitochondrial function under conditions of minimal to moderate hypoxia than 3-21 day old neonates.

Adenosine Triphosphate↗
PubMed1991

Autoimmune Addison's disease and thyrotoxic thyroiditis presenting as encephalopathy in twins.

An 11 year old boy who presented with neuropsychiatric symptoms including delirium and pronounced agitation was found to have simultaneous onset of autoimmune adrenocortical insufficiency and hyperthyroidism. His identical twin also had hyperthyroidism and six months later developed symptoms of adrenocortical insufficiency. In children presenting with neuropsychiatric symptoms, adrenal (or pituitary) and other endocrine disorders should be considered.

Addison Disease↗
PubMed1991

ECT-induced delirium in depressed patients with Parkinson's disease.

In this pilot study, a prolonged (interictal) delirium was induced by electroconvulsive therapy (ECT) in seven out of seven depressed patients with Parkinson's disease. This occurrence of delirium appears much higher than what has been reported in other patient populations. These findings are consistent with several lines of data that have implicated the basal ganglia in the development of delirium from other causes, and they suggest that structural changes in these areas may predispose individuals to develop an interictal delirium during a course of ECT.

Aged↗