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Biomedical subjects

C Williams

Publications and source records attributed to C Williams.

At least 145 records · Page 8Linked to original sources
PubMed2000

Prevention validation and accounting platform: a framework for establishing accountability and performance measures of substance abuse prevention programs.

The field of substance abuse prevention has neither an overarching conceptual framework nor a set of shared terminologies for establishing the accountability and performance outcome measures of substance abuse prevention services rendered. Hence, there is a wide gap between what we currently have as data on one hand and information that are required to meet the performance goals and accountability measures set by the Government Performance and Results Act of 1993 on the other. The task before us is: How can we establish the accountability and performance measures of substance abuse prevention programs and transform the field of prevention into prevention science? The intent of this volume is to serve that purpose and accelerate the processes of this transformation by identifying the requisite components of the transformation (i.e., theory, methodology, convention on terms, and data) and by introducing an open forum called, Prevention Validation and Accounting (PREVA) Platform. The entire PREVA Platform (for short, the Platform) is designed as an analytic framework, which is formulated by a collectivity of common concepts, terminologies, accounting units, protocols for counting the units, data elements, and operationalizations of various constructs, and other summary measures intended to bring about an efficient and effective measurement of process input, program capacity, process output, performance outcome, and societal impact of substance abuse prevention programs. The measurement units and summary data elements are designed to be measured across time and across jurisdictions, i.e., from local to regional to state to national levels. In the Platform, the process input is captured by two dimensions of time and capital. Time is conceptualized in terms of service delivery time and time spent for research and development. Capital is measured by the monies expended for the delivery of program activities during a fiscal or reporting period. Program capacity is captured by fourteen measurement units, tapping into the dimensions of staff resources and community assets. Staff resources are, in turn, operationalized in terms of staff size, staff certification status, staff turnover rate, and the accreditation status of a provider agency. Community assets are operationalized by the number of community centers accessible to the funded agency, number of formalized teams or antidrug coalitions active in the catchment area, and other social/human services providers with whom the prevention agency has formalized networks. The totality of process output from all sources of program activities is reduced to eighteen classes of measures. These are operationalized by thirty-three summary measures. Some of these include: total count of events facilitated; total number of clients served; average number of clients served per event; clients served by single and multiple program sessions; classification of target population in terms of the severity of risk as defined by the Institute of Medicine; age groups and race/ethnicity of clients served; number of program participants retained by recurring programs; number of clients who have completed the program; penetration rates to the target population; client attrition rates; average referral rates per provider per time interval; referral success rates; and so on. All process output measures specified in the Platform are derived from two broad classes of events classified as either products or services. The collectivity of these measures is expected to present a cost-effective, parsimonious, yet comprehensive picture of the entire spectrum of the process output, i.e., "what came out of the program as program activities". For the measurement of performance outcomes, two types of data are incorporated into the Platform: outcome data from individuals and the behavior (or performance) of social indicators from aggregated data bases. Individual data are used to evaluate the outcome of substance abuse programs

Accounting↗
PubMed2000

College students' performance on associated, corresponding tasks for horizontality.

500 college biology students were asked to predict the axisymmetry (horizontal-vertical position) of the water surface and a swimming goldfish in a masked, sealed container. Subjects were shown the fish submerged in the semifilled container before it was slipped into a terry cloth stocking. The researcher then asked subjects to predict the position of the fish and the water surface as the sealed container was rotated to different angles. Many college students did not understand that liquids and submerged organisms remain invariantly horizontal regardless of the rotation of the container.

Curriculum↗
PubMed2000

Paranormal belief, experience, and the Keirsey Temperament Sorter.

121 college students completed the Anomalous Experience Inventory and the Keirsey Temperament Sorter. Multiple regression analyses provided significant models predicting both Paranormal Experience and Belief; the main predictors were the other subscales of the Anomalous Experience Inventory with the Keirsey variables playing only a minor role.

Adult↗
PubMed2000

Screening for refractive errors with the Topcon PR2000 Pediatric Refractometer.

PURPOSE: The PR2000 (Topcon, Tokyo, Japan) is a photorefractor that has been used in a population study comparing different methods of screening preschool children. The present study was conducted to determine the accuracy of the device in a largely clinical population. METHODS: Two hundred twenty-two children less than 8 years of age were included. All children were examined by an orthoptist using the PR2000 without inducing cycloplegia. All children then underwent retinoscopy with cycloplegia by an examiner who was unaware of the results from the PR2000 examination. RESULTS: The PR2000 gave a numerical reading for 90% of the children's right eyes and the message "Out of range" for a further 5%. The readings underestimated the amount of hypermetropic or astigmatic refractive error found on retinoscopy by an amount proportional to the magnitude of the refractive error. Agreement with retinoscopy for the axis of astigmatism more than 0.75 D was moderately good (intraclass correlation coefficient [ICC] = 0.63). The PR2000 was more useful as a screener, especially for anisometropia for which it was 91% sensitive and 92% specific. The repeatability was good for sphere (ICC = 0.74), less so for astigmatism (ICC = 0.59), and better than the optometrist for anisometropia (ICC = 0.38). The presence of nonrefractive diagnoses and the age of the children examined made little difference in the screening results. CONCLUSIONS: The PR2000 underestimated hypermetropic refractive errors when used without cycloplegia. However, it was at least as good a screening device as other similar instruments, especially when judged by its ability to detect anisometropia and the repeatability of the results.

Child↗
PubMed2000

Carbohydrate ingestion prior to exercise augments the exercise-induced activation of the pyruvate dehydrogenase complex in human skeletal muscle.

This study examined the effect of pre-exercise carbohydrate (CHO) ingestion on pyruvate dehydrogenase complex (PDC) activation, acetyl group availability and substrate level phosphorylation (glycogenolysis and phosphocreatine (PCr) hydrolysis) in human skeletal muscle during the transition from rest to steady-state exercise. Seven male subjects performed two 10 min treadmill runs at 70 % maximum oxygen uptake (VO2,max), 1 week apart. Each subject ingested 8 ml (kg body mass (BM))-1 of either a placebo solution (CON trial) or a 5.5 % CHO solution (CHO trial) 10 min before each run. Muscle biopsy samples were obtained from the vastus lateralis at rest and immediately after each trial. Muscle PDC activity was higher at the end of exercise in the CHO trial compared with the CON trial (1.78+/-0.18 and 1.27+/-0.16 mmol min(-1) (kg wet matter (WM))(-1), respectively; P 0.05) and this was accompanied by lower acetylcarnitine (7.1+/-1.2 and 9.1+/-1.1 mmol kg(-1) (dry matter (DM))(-1) in CHO and CON, respectively; P<0.05) and citrate concentrations (0.73+/-0.05 and 0.91+/-0.10 mmol (kg DM)(-1) in CHO and CON, respectively; P<0.05). No difference was observed between trials in the rates of muscle glycogen and PCr breakdown and lactate accumulation. This is the first study to demonstrate that CHO ingestion prior to exercise augments the exercise-induced activation of muscle PDC and reduces acetylcarnitine accumulation during the transition from rest to steady-state exercise. However, those changes did not affect the contribution of substrate level phosphorylation to ATP resynthesis.

Acetylcarnitine↗
PubMed2000

Reducing the risk of user error with infusion pumps.

Many of the adverse reports received by the Medical Devices Agency concern infusion pumps. Clinical governance aims to ensure that both employers and employees reduce the hazards related to device use. Full training is required to help staff avoid user errors.

Humans↗
PubMed2000

[Antibiotic prophylaxis for high risk patients undergoing cholecystectomy].

An open, randomised clinical trial was performed on 435 high risk patients who underwent open cholecystectomy between 1 = January 1993. and 31. December 1995. The patients were divided into three groups. Group 1 (AMOX/CLAV, N = 179) was treated with 1.2 g i.v. amoxicillin/clavulanic acid, the patients in Group 2 (COMPARATOR, N = 164) were given other antibiotics commonly used for prophylaxis in biliary surgery (cefamandole, cefuroxime, cefotaxim). Group 3 (CONTROL, N = 92) contained patients without any risk factors for infectious complication. In this group we did not use antibiotic prophylaxis. The results were analysed with Student t, and x2 methods. The wound infection rate in Group 1 was 2.76% versus 5.48% in Group 2. The difference was significant if the patients were older than 65 years or the preoperative hospitalisation was longer than 5 days. The concentration of amoxycillin/calavulanic acid was measured in the serum, in the wall of the gall bladder, in the bile obtained both from the gall bladder and the major bile duct. The observed levels were higher than the therapeutic concentration in the serum and in the bile gained from the major bile duct, whereas lower in the gall bladder wall, and in the bile gained from the gall bladder. Systemic antibiotic prophylaxis is required for open cholecystectomy in high risk patients.

Age Factors↗
PubMed1999

Dose escalation of chart in non-small cell lung cancer: is three-dimensional conformal radiation therapy really necessary?

PURPOSE: To evaluate, preclinically, the potential for dose escalation of continuous, hyperfractionated, accelerated radiation therapy (CHART) for non small-cell lung cancer (NSCLC), we examined the strategy of omission of elective nodal irradiation with and without the application of three-dimensional conformal radiation technology (3DCRT). METHODS AND MATERIALS: 2D, conventional therapy plans were designed according to the specifications of CHART for 18 patients with NSCLC (Stages Ib, IIb, IIIa, and IIIb). Further plans were generated with the omission of elective nodal irradiation (ENI) from the treatment portals (2D minus ENI plans [2D-ENI plans]). Both sets were inserted in the patient's planning computed tomographies (CTs). These reconstructed plans were then compared to alternative, three-dimensional treatment plans which had been generated de novo, with the omission of ENI: 3D minus elective nodal irradiation (3D-ENI plans). Dose delivery to the planning target volumes (PTVs) and to the organs at risk were compared between the 3 sets of corresponding plans. The potential for dose escalation of each patient's 2D-ENI and 3D-ENI plan beyond 54 Gy, standard to CHART, was also determined. RESULTS: PTV coverage was suboptimal in the 2D CHART and the 2D-ENI plans. Only in the 3D-ENI plans did 100% of the PTV get > or = 95% of the dose prescribed (i.e., 51.5 Gy [51.3-52.2]). Using 3D-ENI plans significantly reduced the dose received by the spinal cord, the mean and median doses to the esophagus and the heart. It did not significantly reduce the lung dose when compared to 2D-ENI plans. Escalation of the dose (minimum > or = 1 Gy) with optimal PTV coverage was possible in 55.5% of patients using 3D-ENI, but was possible only in 16.6% when using the 2D-ENI planning strategy. CONCLUSIONS: 3DCRT is fundamental to achieving optimal PTV coverage in NSCLC. A policy of omission of elective nodal irradiation alone (and using 2D technology) will not achieve optimal PTV coverage or dose escalation. 3DCRT with omission of ENI can achieve true escalation of CHART in 55.5% of tumors, depending on their site and N-stage.

Aged↗
PubMed1999

Context-dependent Taq-polymerase-mediated nucleotide alterations, as revealed by direct sequencing of the ZNF189 gene: implications for mutation detection.

We have recently reported on the genetic organisation of a novel Krüppel-like zinc finger, ZNF189, located to 9q22-q31. In that study we found no mutations in the coding sequence when using ZNF189 as a candidate gene for sporadic basal cell cancer and squamous cell cancer. Here, by direct sequencing of the proximal promotor of ZNF189, mutations were found to appear in a small hot-spot region in over 50% of analysed tumour samples, the majority being G to A substitutions. The hot-spot region spans a 24bp G-rich region. Repeated analyses of the original sample lysates fail to confirm each of these mutations; and frequently new mutations appear at neighbouring positions. Subsequent analysis with serial dilutions of genomic DNA and a cosmid harbouring the wild-type ZNF189 gene demonstrate that these sequence-specific alterations arise in the outer PCR-amplification when 50 copies or less of template are used. Although the mechanism of how these context-specific alterations arise is not proven, the results demonstrate a previously unreported type of PCR-mediated sequence-specific alteration that easily could have been interpreted as being of clinical relevance. The phenomena observed show that mutations detected by direct sequencing can be caused by PCR-introduced alterations. Consequently, this should be of general caution in mutation analysis of disease gene candidates when using small amounts of template, such as microdissected biopsies.

Artifacts↗
PubMed1999

Marijuana use among minority youths living in public housing developments.

Youths residing in public housing developments appear to be at markedly heightened risk for drug use because of their constant exposure to violence, poverty, and drug-related activity. The purpose of this study was to develop and test a model of marijuana etiology with adolescents (N = 624) residing in public housing. African-American and Hispanic seventh graders completed questionnaires about their marijuana use, social influences to smoke marijuana, and sociodemographic and psychosocial characteristics. Results indicated that social influences, such as friends' marijuana use and perceived ease of availability of marijuana, significantly predicted both occasional and future use of marijuana. Individual characteristics such as antimarijuana attitudes and drug refusal skills also predicted marijuana use. The findings imply that effective prevention approaches that target urban youths residing in public housing developments should provide them with an awareness of social influences to use marijuana, correct misperceptions about the prevalence of marijuana smoking, and train adolescents in relevant psychosocial skills.

Adolescent↗
PubMed1999

A high frequency of sequence alterations is due to formalin fixation of archival specimens.

Genomic analysis of archival tissues fixed in formalin is of fundamental importance in biomedical research, and numerous studies have used such material. Although the possibility of polymerase chain reaction (PCR)-introduced artifacts is known, the use of direct sequencing has been thought to overcome such problems. Here we report the results from a controlled study, performed in parallel on frozen and formalin-fixed material, where a high frequency of nonreproducible sequence alterations was detected with the use of formalin-fixed tissues. Defined numbers of well-characterized tumor cells were amplified and analyzed by direct DNA sequencing. No nonreproducible sequence alterations were found in frozen tissues. In formalin-fixed material up to one mutation artifact per 500 bases was recorded. The chance of such artificial mutations in formalin-fixed material was inversely correlated with the number of cells used in the PCR-the fewer cells, the more artifacts. A total of 28 artificial mutations were recorded, of which 27 were C-T or G-A transitions. Through confirmational sequencing of independent amplification products artifacts can be distinguished from true mutations. However, because this problem was not acknowledged earlier, the presence of artifacts may have profoundly influenced previously reported mutations in formalin-fixed material, including those inserted into mutation databases.

Base Sequence↗
PubMed1999

Variance in transneuronal retrograde ganglion cell degeneration in monkeys after removal of striate cortex: effects of size of the cortical lesion.

The extent of transneuronal retrograde degeneration of ganglion cells in the primate retina depends on the age at which striate cortex was damaged, the survival time, the species, and retinal eccentricity. We here report on the effect of lesion size beyond striate cortex, which we assessed along with retinal ganglion cell degeneration in three groups of macaque monkeys who, in each group, had undergone striate cortical ablation at similar ages and survived for similar periods, which ranged from 302 days to 8 years. Where possible, the number of surviving projection neurones in the degenerated dLGN and its volume were also estimated. Results confirm that both geniculate and retinal degeneration correlate significantly with survival time but that the differences within a group can exceed differences between groups and are best accounted for by the extent of the damage to extra-striate visual cortex and underlying white matter.

Animals↗