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Biomedical subjects

S Davis

Publications and source records attributed to S Davis.

At least 253 records · Page 14Linked to original sources
PubMed1994

Alcoholism and cancer of the larynx: a case-control study in western Washington (United States).

Alcohol consumption is a well-known risk factor for laryngeal cancer. To determine whether alcoholism, as measured by responses to the Michigan alcoholism screening test (MAST), is a risk factor for laryngeal cancer independent of alcohol consumption, we analyzed data from a population-based case-control study. Personal interviews were conducted with 235 patients (81 percent response rate) with laryngeal cancer diagnosed from September 1983 through February 1987, who were residents of the Seattle metropolitan area. A total of 547 controls frequency-matched by age and gender, selected by random-digit dialing, were interviewed (75 percent response rate). When considered in a multivariate model, independent risk factors for laryngeal cancer included: alcohol consumption (42 or more drinks/wk compared with seven or less drinks/wk: odds ratio [OR] = 3.1, 95 percent confidence interval [CI] = 1.2-7.9); cigarette use (40 or more cigarettes/day compared with never-smoked: OR = 23.1, CI = 9.4-52.6); and weighted positive responses to the MAST (score of five or more compared with score of zero: OR = 1.9, CI = 1.1-3.4). Possible explanations for the association between alcoholism and laryngeal cancer are that a measure of alcoholism improves the accuracy of assessment of alcohol consumption, that alcoholism is associated with a pattern of alcohol consumption that increases the risk of laryngeal cancer, or that alcoholism may be a marker for host susceptibility to the carcinogenic effects of alcohol.

Adult↗
PubMed1994

Unilateral asterixis due to a lesion of the ventrolateral thalamus.

A case of unilateral asterixis in a man with a focal ischaemic lesion of the contralateral ventral thalamus is presented. Atypically, the movements were present at rest and had a pattern of activation that resulted in an initial misdiagnosis of epilepsia partialis continua. This case emphasises the importance of electromyographic analysis in establishing the correct diagnosis of involuntary movements before starting specific treatment.

Aged↗
PubMed1994

Unilateral asterixis due to a lesion of the ventrolateral thalamus.

A case of unilateral asterixis in a man with a focal ischaemic lesion of the contralateral ventral thalamus is presented. Atypically, the movements were present at rest and had a pattern of activation that resulted in an initial misdiagnosis of epilepsia partialis continua. This case emphasises the importance of electromyographic analysis in establishing the correct diagnosis of involuntary movements before starting specific treatment.

Aged↗
PubMed1994

A re-analysis of caries rates in a preventive trial using Poisson regression models.

The analysis of caries incidence in clinical trials has several challenging features: (1) The distribution of the number of caries onsets per patient is skewed, with the majority of patients having few or no cavities; (2) the number of surfaces at risk varies (i) over time and (ii) between patients, due to eruption and exfoliation patterns, dental diseases, and treatments; (3) surfaces within a patient differ in their caries susceptibility, and (4) caries onsets within a patient are correlated due to shared host factors. Recent statistical developments in the area of correlated data analyses permit incorporation of some of these characteristics into the analyses. With Poisson regression models, the expected number of caries onsets can be related to the number of surfaces at risk, the time they have been at risk, and surface- and subject-specific explanatory variables. The parameter estimated in these models is an epidemiological measure of disease occurrence: the disease incidence rate (caries rate) or the rate of change from healthy (sound) to diseased (carious). Differences and ratios of these rates provide standard epidemiological measures of excess risk. To illustrate, Poisson regression models were used for exploratory analyses of the Ylivieska xylitol study.

Age Factors↗
PubMed1994

Within-subject coronal caries distribution patterns: an evaluation of randomness with respect to the midline.

The distribution of caries among homologous surfaces can exhibit three possible patterns: random, aggregated, or regular. In a random caries pattern, caries lesions are randomly distributed among homologous surfaces. An aggregated caries pattern is distinguished by the aggregation of lesions on one side of the mouth or the other to a greater extent than would be expected by chance alone. For a regular caries pattern, the left-right distribution of lesions is more homogenous than would be expected by chance alone. A test statistic based on the left-right distribution of caries lesions among discordant homologous pairs was developed to investigate which of these three caries patterns is present in a representative sample of the adult United States population. The data originated from the National Survey of Oral Health in the US (Employed Adults), 1985-1986. Of the 15,132 subjects studied, 12,776 subjects had 2 or more decayed or filled teeth. (At least 2 carious or filled teeth are required for detection of patterns.) Approximately 50% of these subjects (n = 6,439) had two or more discordant homologous tooth pairs. With these tooth pairs, the hypothesis of a random caries pattern was rejected in favor of an aggregated caries pattern (p < 0.0001). Similar findings were obtained with discordant homologous surface pairs. This aggregation of caries on one side of the mouth or the other may be due to genetic, infectious, and/or environmental factors.

Adolescent↗
PubMed1994

Automatic weaning from mechanical ventilation using an adaptive lung ventilation controller.

STUDY OBJECTIVE: To evaluate a new method of closed-loop mechanical ventilation using an adaptive lung ventilation (ALV) controller in patients with different pathologic causes of respiratory failure at a time when they first met standard weaning criteria. STUDY DESIGN: Prospective, open, selected case study. SETTING: The 10-bed, multidisciplinary respiratory intensive care unit at Groote Schuur hospital, which is a teaching unit of the University of Cape Town. PATIENTS: Twenty-seven patients (9 patients in each of 3 groups: normal lungs, parenchymal lung disease, and COPD) who required prolonged mechanical ventilation and who met standard weaning criteria were included. Our institutional committee for ethical research approved the study and informed consent was obtained. INTERVENTIONS: The patients were mechanically ventilated and had daily measurements of vital capacity, respiratory rate, and arterial blood gas analysis until they met standard weaning criteria. On the day that each patient met the weaning criteria, a closed loop control algorithm providing ALV was implemented on a modified ventilator (Hamilton AMADEUS) with a PC-based lung function analyzer. After measuring gross alveolar ventilation, patients were placed in ALV and ventilatory and hemodynamic parameters were measured at baseline, 5 min, 30 min, and 2 h. Pertinent parameters measured included airway pressures, pressure support levels, respiratory rates, rapid shallow breathing indices, airway resistance indices, and patient respiratory drive and work indices. MEASUREMENTS AND RESULTS: In 22 patients, ALV reduced pressure support to 5 cm H2O and an intermittent mandatory ventilation rate of 4 breaths/min within 30 min, and all but 1 of these patients were successfully extubated within 24 h. In four patients, pressure support was maintained by ALV at a mean level of 14.6 cm H2O +/- for 2 h and these patients were recorded as having failed to wean. There was a measurable difference in an index of airway resistance relative to muscular activity between the successfully weaned and failed wean patients with COPD during the attempted wean by the ALV controller. CONCLUSIONS: ALV will provide a safe, efficient wean and will respond immediately to inadequate ventilation in patients when standard weaning criteria are met.

Adult↗
PubMed1994

Drug treatment decisions of chemically-dependent women.

The Cognitive Appraisal Model was developed as a means of examining the cognitive appraisal processes and the intervening variables that affect the decision of chemically-dependent women (CDW) to remain in or drop out of a drug treatment program. Methodological triangulation, in which eight questionnaires were selected as construct measures, was used to compare a group of CDW who remained in treatment 4 consecutive months (N = 39) and a group who dropped out prior to completing 4 consecutive months (N = 41). Anger was the strongest predictor of treatment dropout, and feeling inconvenienced by treatment demands ironically predicted treatment compliance. Overall, findings revealed that CDW appraise drug treatment decisions differently than would be expected.

Adolescent↗
PubMed1994

Factors associated with the diversion of mentally disordered offenders.

This study is an examination of the process of pre-trial diversion, in which prosecutors use their discretion to drop criminal proceedings against mentally disordered persons on the condition that such persons be certified and detained for treatment in a hospital setting. An attempt was made to uncover the factors relevant to understanding why mentally disordered offenders are diverted in some instances but not in others. Using data from the forensic psychiatric system of a Canadian province, it was found that accused persons were diverted into the mental health system in 13.4 percent of cases over a three-year period. Three factors were found to be significantly associated with the diversion decision: 1) offense seriousness, with persons facing less serious charges being diverted in a greater proportion of cases; 2) court jurisdiction, with courts in smaller centres and outlying areas being more likely to divert; and 3) psychiatrist, with considerable variability between psychiatrists in their use of the diversion mechanism. The significance of these results and implications for forensic psychiatric policy-making are discussed.

Canada↗
PubMed1994

Pooling of long term clinical wear data for posterior composites.

Clinical studies to evaluate the wear of posterior composite restorations are complicated by the large number of factors which influence the findings. A multi-factorial equation has been developed which successfully normalizes the effects of these factors within studies. This equation is not capable of normalizing these effects for other investigations reported in the literature because study characteristics essential to the analysis are rarely reported. Quantitative estimates of wear rate often differ dramatically between studies and between groups of investigators. The objective of this study was to investigate a potential solution to this problem by ranking materials within studies, using common materials to relate rankings across studies, and achieving an overall pooled ranking for products. An intensive literature search disclosed 78 articles and 46 abstracts on clinical posterior composite wear. All studies were analyzed which involved: (1) more than five restorations per material, (2) Class I or II restorations in posterior adult teeth, (3) characterized commercial products, (4) 2 or 3-year wear data, and (5) information on more than one composite material per study. There were 10 2-year studies involving 25 materials, and 10 3-year studies with 26 materials. Within each study the materials were ranked by wear, and the rankings were converted to centered modified ridits. A meta-analysis combining the data across studies was conducted using ANOVA. Although caution is needed for interpreting significance levels because of the small numbers of products evaluated per study, a high level of agreement in rank correlation of 28 products across qualifying studies was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Computer-aided diagnosis and treatment planning.

As computers slowly permeate our dental practices, it becomes obvious that we have a choice: either accept and embrace this technology in order to survive, if not prosper, or we can reject it and sit on the sidelines and get left behind. Using a new patient examination scenario, five different types of computer-aided technology are explored. The clinical application of each piece of equipment is the focus. Extraoral video imaging, intraoral imaging, voice-activated periodontal charting, digital radiographs, and complete office management systems are discussed.

Dental Care↗
PubMed1994

Intact splenic function in cystic fibrosis.

Patients with cystic fibrosis (CF) suffer from severe chronic pulmonary infections but rarely develop bacteremia/septicemia suggestive of an intact splenic mononuclear phagocyte function. The splenic function of 25 patients diagnosed with CF, aged 2 to 37 years, was evaluated using erythrocyte pit count by direct interference contrast microscopy. Results were compared with patients with sickle cell disease and normal individuals. All CF patients displayed normal splenic function by pit count. The mean percentage of pitted erythrocytes was 0.20 +/- 0.28 (range: 0.0% to 1.0%) versus 0.19 +/- 0.33 (range: 0.0% to 1.4%) in normal eusplenic controls. There were no episodes of bacteremia or septicemia despite recurrent acute exacerbations of chronic bacterial bronchitis and the use of central lines. We conclude that splenic function in CF is unabridged and may account for the rarity of bacteremia/septicemia in patients with CF despite the high prevalence of chronic bronchial infection in this population.

Adolescent↗
PubMed1994

Radiation and carboplatin combined-modality therapy in non-small cell lung cancer.

Previously untreated patients with stages I to IV, N0-3, M0 unresectable non-small cell lung cancer were randomized to arm I (conventional radiotherapy [RT], 60 Gy in 30 fractions over 6 weeks), arm II (accelerated RT, 60 Gy in 30 fractions over 3 weeks), arm III (conventional RT, as in arm I, plus carboplatin 70 mg/m2/d on days 1 to 5 during treatment weeks 1 and 5), or arm IV (accelerated RT, as in arm II, plus carboplatin 70 mg/m2/d on days 1 to 5 of week 1 only). An intensive analysis of toxicity in the first 92 patients entered revealed significantly more neutropenia (P < .0001) and thrombocytopenia (P = .004) in the combined-modality arms. Esophagitis was worse on arms II, III, and IV, but was more prolonged in the accelerated RT arms. Overall, however, the treatment on all study arms was well tolerated.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

The influence of subsequent neoplasms on incidence trends in childhood cancer.

The purpose of this analysis was to evaluate to what extent subsequent malignant neoplasms account for the increasing rates of cancer occurrence among children. Data from the population-based Surveillance, Epidemiology, and End Results program were used to calculate age-standardized annual incidence rates from 1974-1989 for 10 common cancers among children 14 years of age or younger. Mean rates and linear trends were evaluated using least squares regression, first for all neoplasms and then excluding subsequent neoplasms, to determine if the removal of subsequent neoplasms would attenuate increasing trends. Increasing annual incidence rates were found for all childhood cancers combined, acute lymphoid leukemia, and brain tumors, but not for other cancer types. Excluding subsequent neoplasms from the analysis had a negligible effect on the trends we observed. Although it remains largely undetermined why childhood cancer incidence rates are increasing in the United States, this study presents evidence that subsequent primary neoplasms do not substantively contribute to these observed trends.

Adolescent↗
PubMed1994

The tails of two proteins: the scrapie prion protein and the ciliary neurotrophic factor receptor.

Many proteins with a variety of functions have proven to have glycosylphosphatidylinositol (GPI)-linkages; two members of this family are the scrapie prion protein and the receptor for ciliary neurotrophic factor (CNTF). The scrapie prion protein has two isoforms: PrPC is found in brain cells from normal animals, while PrPSc is an abnormal isoform that is only found in scrapie-infected animals. PrPSc is the only identified component of the prion, an infectious agent that apparently does not contain nucleic acid. Models for how prions replicate require that PrPSc must somehow recruit PrPC and catalyze or stabilize a post-translational event that converts PrPC into PrPSc. Extensive characterization has suggested that this critical post-translational event is probably conformational and not a chemical change. The presence of a GPI anchor on CNTFR alpha is an unusual feature for a molecule that must transmit a signal to the inside of the cell. Recent data have indicated that CNTFR alpha must bind CNTF, then interact with two other "beta" receptor components to initiate signal transduction. Furthermore, we have shown that, unlike the vast majority of receptors, CNTFR alpha can function as a soluble molecule to promote CNTF action on cells that contain the two beta components, but do not themselves express CNTFR alpha. Intriguingly, we have also demonstrated that CNTFR alpha is present in cerebrospinal fluid and blood in vivo, and the release of CNTFR alpha from skeletal muscle is increased by denervation of the muscle. Whether the soluble form is released through GPI-anchor cleavage remains to be determined.

Animals↗