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Biomedical subjects

C Snyder

Publications and source records attributed to C Snyder.

At least 37 records · Page 2Linked to original sources
PubMed1998

Prostate cancer screening in the workplace. Employer costs.

Recognition of the mortality and morbidity associated with prostate cancer has resulted in employer based screening programs. This retrospective cohort study identified the employer costs of prostate cancer screening and referrals due to abnormal test results. The subjects were 385 men enrolled in a workplace screening program at a single employer between 1993 and 1995. Screening consisted of digital rectal examination (DRE) annually for enrolled employees aged 40 years and older, plus annual prostate specific antigen (PSA) testing for those 50 and older, and those 40 and older and considered at high risk. Data related to the health care and lost productivity costs of screening and referrals for abnormal test results were collected and analyzed. The total cost of screening was $44,355, or approximately $56 per screening encounter (788 DREs; 437 PSAs). Abnormal screening tests resulted in 52 referrals. Upon further evaluation, 42% were found to have an enlargement, 29% a node, and 12% benign prostatic hyperplasia. Only one malignancy was found. The total cost of additional referrals was $31,815, or 42% of the cost of screening plus referrals. As the cost per screening encounter was low, prostate cancer screening in the workplace is an efficient alternative.

Adult↗
PubMed1997

Patient assessments of adequacy of dialysis and protein nutrition.

Nephrologists closely monitor biochemical measurements of adequacy of dialysis and protein nutrition, but little is known about how patients assess adequacy. We sought (1) to determine how hemodialysis patients assess adequacy and (2) to compare patient assessments with objective measures of adequacy. We performed a cross-sectional interview study of 145 patients from two chronic hemodialysis units. Using a structured questionnaire, we asked subjects to assess the amount of dialysis and protein nutrition they were getting. Objective measures of amount of dialysis (Kt/V) and protein nutrition (albumin) were obtained from chart abstraction. We found that only 5% of all subjects thought they were getting less dialysis than they needed, yet 41% were actually receiving inadequate dialysis (Kt/V <1.2). Even among the 60 subjects with Kt/V less than 1.2, only 5% thought they were getting less dialysis than they needed. Similarly, 21% of all subjects thought they were getting less protein nutrition than they needed, yet 28% had inadequate protein nutrition levels (albumin <3.5 g/L). Even among the 41 subjects with albumin less than 3.5 g/L, only 20% thought they were getting less protein nutrition than they needed. In conclusion, patient assessments of adequacy differ greatly from the objective measures that nephrologists use to assess adequacy. Most patients with Kt/V less than 1.2 or albumin less than 3.5 g/L think they are getting adequate dialysis and protein nutrition. Understanding how patients assess adequacy may be an important step in developing interventions to improve the adequacy of dialysis and protein nutrition.

Attitude to Health↗
PubMed1997

Using data mining to characterize DNA mutations by patient clinical features.

In most hereditary cancer syndromes, finding a correspondence between various genetic mutations within a gene (genotype) and a patient's clinical cancer history (phenotype) is challenging; to date there are few clinically meaningful correlations between specific DNA intragenic mutations and corresponding cancer types. To define possible genotype and phenotype correlations, we evaluated the application of data mining methodology whereby the clinical cancer histories of gene-mutation-positive patients were used to define valid or "true" patterns for a specific DNA intragenic mutation. The clinical histories of patients with their corresponding detailed attributes without the same oncologic intragenic mutation were labeled incorrect or "false" patterns. The results of data mining technology yielded characterizing rules for the true cases that constituted clinical features which predicted the intragenic mutation. Some of the initial results derived correlations already independently known in the literature, adding to the confidence of using this methodological approach.

Age of Onset↗
PubMed1996

BRCA1 testing in families with hereditary breast-ovarian cancer. A prospective study of patient decision making and outcomes.

OBJECTIVES: To identify predictors of utilization of breast-ovarian cancer susceptibility (BRCA1 gene) testing and to evaluate outcomes of participation in a testing program. DESIGN: Prospective cohort study with baseline interview assessment of predictor variables (eg, sociodemographic factors, knowledge about hereditary cancer and genetic testing, perceptions of testing benefits, limitations, and risks). BRCA1 test results were offered after an education and counseling session in a research setting. Outcome variables (including depression, functional health status, and prophylactic surgery plans [follow-up only]) were assessed at baseline and 1-month follow-up interviews. PARTICIPANTS: Adult male and female members (n=279) of families with BRCA1-linked hereditary breast-ovarian cancer (HBOC). RESULTS: Of subjects who completed a baseline interview (n=192), 60% requested BRCA1 test results (43% of all study subjects requested results). Requests for results were more frequent for persons with health insurance (odds ration [OR], 3.74; 95% confidence interval [CI], 2.06-6.80); more first-degree relatives affected with breast cancer (OR, 1.59; 95% CI, 1.16-2.16); more knowledge about BRCA1 testing (OR, 1.85; 95% CI, 1.36-2.50); and indicating that test benefits are important (OR, 1.45; 95% CI, 1.13-1.86). At follow-up, noncarriers of BRCA1 mutations showed statistically significant reductions in depressive symptoms and functional impairment compared with carriers and nontested individuals. Individuals identified as mutation carriers did not exhibit increases in depression and functional impairment. Among unaffected women with no prior prophylactic surgery, 17% of carriers (2/12) intended to have mastectomies and 33% (4/12) to have oophorectomies. CONCLUSIONS: Only a subset of HBOC family members are likely to request BRCA1 testing when available. Rates of test use may be higher in persons of a higher socioeconomic status and those with more relatives affected with breast cancer. For some high-risk individuals who receive test results in a research setting that includes counseling, there may be psychological benefits. More research is needed to assess the generalizability of these results and evaluate the long-term consequences of BRCA1 testing.

Adult↗
PubMed1996

Effects of myosin light chain kinase and peptides on Ca2+ exchange with the N- and C-terminal Ca2+ binding sites of calmodulin.

Myosin light chain kinase and peptides from the calmodulin (CaM) binding domains of myosin light chain kinase (RS-20, M-13), CaM kinase II, and the myristoylated alanine-rich protein kinase C substrate protein slowed Ca2+ dissociation from CaM's N-terminal sites from 405 +/- 75/s to 1.8-2.9/s and from CaM's C-terminal sites from 2.4 +/- 0.2/s to 0.1-0.4/s at 10 degrees C. Since Ca2+ dissociates 5-29 times faster from the N-terminal in these CaM.peptide complexes and both lobes are required for activation, Ca2+ dissociation from the N-terminal would control target protein inactivation. Ca2+ binds 70 times faster to the N-terminal (1.6 x 10(8) M-1 s-1) than the C-terminal sites (2.3 x 10(6) M-1 s-1). In a 0.6-ms half-width Ca2+ transient, Ca2+ occupied > 70% of the N-terminal but only 20% of the C-terminal sites. RS-20 produced a 9-fold and CaM kinase II a 6.3-fold increase in C-terminal Ca2+ affinity, suggesting that some target proteins may be bound to the C-terminal at resting [Ca2+]. When this is the case, Ca2+ exchange with the faster N-terminal sites may regulate CaM's activation and inactivation of these target proteins during a Ca2+ transient.

Amino Acid Sequence↗
PubMed1996

The tar fraction of cigarette smoke does not promote arteriosclerotic plaque development.

In addition to being the single greatest known environmental cause of cancer, cigarette smoke (CS) is also a major contributor to heart disease. We reported previously that 1) inhalation of either mainstream or sidestream CS promotes aortic arteriosclerotic plaque development; 2) 1,3 butadiene, a vapor-phase component of CS, promotes plaque development at 20 ppm, which at the time was only 2 times higher than the threshold limit value; and 3) individual tar fraction carcinogens in CS, including polynuclear aromatic hydrocarbons (PAHs) and nitrosamines, either do not promote plaque development or do so only at high concentrations. These results suggested that the tar fraction is not the primary source of plaque-promoting agents in CS. We asked whether repeated exposure to the tar fraction of CS, collected in a cold trap (TAR), promotes plaque development in an avian model of arteriosclerosis. Acetone extracts of mainstream CS tar from burning, unfiltered reference cigarettes were solubilized in dimethyl sulfoxide (DMSO) and injected weekly into cockerels for 16 weeks (25 mg/kg/week). Positive controls were injected weekly with the synthetic PAH carcinogen, 7,12 dimethylbenz(a)anthracene (DMBA) dissolved in DMSO and negative controls were injected with DMSO. Plaque location and prevalence did not differ from group to group. Morphometric analysis of plaque cross-sectional areas showed that plaque sizes, which are log-normally distributed, were significantly larger in the DMBA cockerels compared to both the TAR and DMSO groups. There were no significant differences in plaque size between DMSO and TAR cockerels. The results reported here, combined with other recent findings, support the conclusion that the primary arteriosclerotic plaque-promoting components of CS are in the vapor phase.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

Infiltrative keratitis with contact lens wear--a review.

BACKGROUND: "Infiltrates" of white blood cells aggregating in the superficial cornea are common with corneal inflammation. The etiologies of such inflammation vary widely and include an association with contact lens wear. METHODS: This paper reviews the literature regarding corneal infiltrative keratitis with contact lens wear. Basic mechanisms in the development of corneal infiltrates as well as etiologies are presented. Associations and causes, clinical presentation, differential diagnosis, course, and treatment for corneal infiltrates in contact lens wearers are reviewed. CONCLUSIONS: Corneal infiltrates associated with contact lens wear may stem from a variety of causes including factors related to the lens material, design, condition; the lens wearing schedule; environmental factors such as external environment; and lens care patterns, procedures, and products. Individuals who wear contact lenses are also subject to the many non-contact lens-related stimuli to corneal infiltration. Accurate diagnosis and appropriate management of corneal infiltrates with contact lens wear is important, especially due to the possibility of infectious etiology.

Contact Lenses↗
PubMed1994

Peer coaching in clinical teaching: a case report.

Peer coaching is a method for improving teaching skills that was developed for use in general educational classroom settings. Key elements of peer coaching include the identification of specific goals for improving teaching skills, focused observation of teaching by colleagues, and the provision of feedback, analysis, and support. As part of a faculty development project, we adapted peer-coaching methodology to the clinical teaching setting. This report describes the experiences of two family physicians who have served as peer coaches for each other over the past 2 years. The participating physicians report enthusiastically about their experiences with peer coaching as a method for personalized faculty development. They report more self-awareness of their clinical teaching behaviors, the ability to improve specific teaching skills, and the rewards of a collaborative relationship between colleagues.

Ambulatory Care↗
PubMed1994

Daily disposed hydrogel lenses--a comparison with biweekly replacement.

BACKGROUND: Hydrogel lenses worn daily and disposed of daily represent an extreme of the spectrum of prescribing that has not been extensively investigated. This study was undertaken to ascertain whether hydrogel lenses worn on a daily replacement schedule displayed differences in patient comfort, vision, and physiological response and as compared to lenses replaced biweekly. METHODS: Hydrogel lens wearing schedules were devised to allow the patient to, in a masked fashion, directly compare the characteristics of a 1-day-old hydrogel lens to that of one 2 weeks old. Eighteen qualifying subjects wore Bausch & Lomb Seequence 2 lenses in this investigation. RESULTS: There was neither a significant difference in visual acuity, lens condition, and corneal or bulbar conjunctival fluorescein staining, nor a significant difference in subjective ratings of wearing comfort and clarity of vision between the 1-day and biweekly worn lenses. CONCLUSIONS: No apparent advantage was found in replacing the evaluated hydrogel lenses on a daily vs. biweekly schedule when considering vision, comfort, and physiological response of the eye.

Adult↗
PubMed1992

Inhalation of carbon monoxide does not accelerate arteriosclerosis in cockerels.

The effects of chronic exposure to moderate levels of carbon monoxide (CO) upon the augmentation of arteriosclerotic plaque development were investigated in a series of in vivo studies. Cockerels were exposed to carefully regulated CO levels in dynamic exposure chambers. The plaque volume percentage in the aortic walls of experimental and control animals was determined by point-counting. Chronic CO inhalation, at levels up to 200 ppm, did not stimulate arteriosclerotic plaque development (at 200 ppm CO, carboxyhemoglobin (COHb) levels 10 min after exposures ended were 11-12%). When administered concomitantly with cholesterol feeding, CO did not augment plaque development. When administered after either carcinogen-associated or diet-promoted plaque size increases had occurred, CO elicited no further plaque size increases. Thus, in this animal model, daily exposures to moderately high CO levels were without discernable effect upon arteriosclerotic plaque development, although high COHb levels were attained.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Effect of calcium in model plaque on the anticaries activity of fluoride in vitro.

The uptake of calcium by a polysaccharide (agarose) gel used as a model for plaque from a two-step treatment (consisting of a calcium rinse followed by a fluoride treatment) and the effect of the deposited calcium in model plaque on caries lesion formation in enamel were determined. Calcium uptake was measured by treatment of the model plaques with [45Ca]-CaCl2 solutions with or without NaF. A two-step treatment consisting of calcium followed by fluoride produced a 100% increase in calcium content of model plaque, presumably due to the formation of CaF2, compared with a treatment with artificial saliva followed by calcium alone. The effects of these increased plaque minerals on caries lesion formation were studied by subjecting model-plaque-covered enamel blocks to a cyclic demineralization-remineralization treatment. Artificial-plaque-covered enamel blocks were treated daily with 180 ppm calcium for ten min, then 100 ppm fluoride for ten min, followed by demineralization for 16 h, and finally, remineralization for seven h and 40 min. After five days, the blocks were sectioned, and lesion formation was determined by microradiography-microdensitometry. Artificial plaque treated with a calcium rinse followed by a fluoride rinse reduced lesion size by 90%, compared with a 68% reduction by a fluoride rinse alone. When the experiment was repeated with a simulated pre-brush calcium rinse (180 ppm calcium) followed by a fluoride dentifrice suspension (110 ppm fluoride), lesion size was reduced by 46%, compared with a 32% reduction by the fluoride dentifrice suspension alone.

Absorptiometry, Photon↗
PubMed1991

Clinical profiles of non dry eye patients and correlations with tear protein levels.

An accurate clinical description of the normal patient must be established before the dry eye patient can be accurately profiled. The current study was designed to (a) determine normal values for, and to seek correlations between, clinical tests used for the evaluation of non dry eye patients' tear film and ocular surface, and (b) compare clinical findings with previously reported levels of non-stimulated and stimulated tear proteins for the same group. Thirty non-contact lens wearing patients (age range 20-64 years) were determined to be free of dry eye based on the results of a series of clinical tests. McMonnie's dry eye questionnaire was used as an initial screening step. Clinical tests included lacrimation kinetics (using sealed, calibrated filter paper strips), non-invasive tear break-up time (NIBUT) measurement by Xeroscope, biomicroscopic evaluation of the anterior segment, assessment of tear prism height and regularity, and fluorescein and Rose Bengal staining. No significant correlations were found between age, questionnaire score, lacrimation kinetics final tear secretion rate or NIBUT. However, NIBUT results did vary by gender. Mean NIBUT for females was 46.3 +/- 16.6 (standard deviation) seconds and for males 59.3 +/- 2.1 seconds. some significant correlations were found between clinical test results and levels of non-stimulated and stimulated tear proteins. Overall, the results indicate that this battery of clinical tests will be appropriate for distinguishing between normal and dry eye patients. Combined with tear protein assay, this clinical approach may improve our current understanding of the different types of dry eye.

Adult↗
PubMed1991

Dying pattern in volume-controlled hemorrhagic shock in awake rats.

We previously determined that in awake, unmonitored Sprague-Dawley rats, bleeding of 2.5 ml/100 g over 20 min resulted in hemorrhagic shock (HS) with about a 75% survival rate over 24 h, and bleeding of 3.0 ml/100 g in about 25% survival to 24 h. In the present study, we monitored systolic and mean arterial pressure (MAP), central venous pressure (CVP), breathing movements, electroencephalogram (EEG), and arterial blood gases to 3 h in order to study dying patterns. After cannulation under light anesthesia and awakening for 2 h, the rats were bled over 20 min. Ten rats in each of four groups were studied. Shed blood volume (SBV) in group I was 2.0 ml/100 g; in group II, 2.5 ml; in group III, 3.0 ml; and in group IV, 3.5 ml. Three hour survival rates were 100% for group I, 80% for group II (survival time 149 +/- 65 [106-180] min), 40% for group III (survival time 116 +/- 72 [93-180] min), and 0% for group IV (survival time 32 +/- 38 [5-69] min). MAP decreased at end of bleeding, increased transiently to moderately hypotensive levels (attempted self-resuscitation), and then either recovered to normotension or declined to cardiac arrest (death), which was defined as simultaneous apnea, systolic arterial pressure less than or equal to 30 mmHg without pulsations, and isoelectric EEG. EEG depression began with hypotension to MAP less than or equal to 50 mmHg. During HS, PaO2 increased, and PaCO2, pHa, and Hct all decreased. The results suggest that this model with SBV of 3.25 ml/100 g would give a low, but not zero 3 h survival, and therefore would be suitable for the study of responses to field resuscitation potentials.

Animals↗