Biomedical subjects

R W Collins

Publications and source records attributed to R W Collins.

13 recordsLinked to original sources

PubMed2003

Multichannel mueller matrix ellipsometry for simultaneous real-time measurement of bulk isotropic and surface anisotropic complex dielectric functions of semiconductors.

We have applied a dual rotating-compensator multichannel ellipsometer to acquire spectra ( approximately 2.0-4.6 eV) in all 16 elements of the Mueller matrix associated with a specularly reflecting surface, in a minimum time of 0.25 s. In this initial study, such results have been collected for the (110) silicon surface at an incidence angle of approximately 70 degrees and have been used to derive spectra in the bulk isotropic dielectric function epsilon (b)= epsilon (1b)-i epsilon (2b) and the surface-induced dielectric function anisotropy Delta epsilon =Delta epsilon (1)-iDelta epsilon (2). Thus, this instrument shows promise for simultaneous real-time measurement of epsilon (b) and Delta epsilon spectra in oblique reflection during the fabrication of semiconductor structures having bulk isotropic components.

Journal Article↗

PubMed2002

Comparison of long-chain alcohols and other volatile compounds emitted from food-borne and related Gram positive and Gram negative bacteria.

Numerous reports have been published on the antimicrobial activity of synthetic volatile long chain alcohols, such as 1-decanol and 1-dodecanol, against bacteria and fungi. The objective of the present study was to survey microorganisms for emission patterns of naturally occurring long chain alcohols and other volatile components to determine if these compounds are associated with certain groups of bacteria. Cultures were grown in trypticase soy broth overnight and volatile compounds were trapped on a porous polymer and identified by mass spectrometry. Subsequently, volatile compounds were collected from 26 strains of food associated bacteria using solid-phase microextraction and analyzed by gas chromatography. Alcohols comprising 1-octanol, 1-decanol, and 1-dodecanol occurred as products from enteric Gram negative bacteria, which included Citrobacter, Enterobacter, Klebsiella, Salmonella, and Shigella. However, the long chain alcohols were not detected as products from the nonenteric Gram negative species studied which included Acinetobacter, Pseudomonas, and Shewanella. Among Gram positive bacteria, including Bacillus, Enterococcus, Lactococcus, Leuconostoc, Listeria, Staphylococcus, and Streptococcus, the only long chain alcohol detected was 1-decanol and, if present, it occurred in relatively small amounts. Other classes of compounds emitted by bacteria included methylketones and sulfides. The methylketones were found as products from Gram positive and Gram negative bacteria, whereas the sulfides were closely associated with Gram positive bacteria. In summary, the emission patterns of volatile compounds from bacteria showed many trends including the association of long chain alcohols with enteric Gram negative bacteria. The results provide a basis for future in vivo studies to determine if volatile compounds such as natural long chain alcohols function in the ecology of food-borne Gram negative bacterial pathogens.

Alcohols↗

PubMed2001

The clinical importance of variation within the HLA-Bw4 complex.

BACKGROUND: Antibody screening of a patient with a failed renal transplant showed positive reactions with most, but not all HLA-Bw4-associated B-locus antigens. However, the patient's serological HLA class I type suggested the presence of HLA-Bw4. METHODS: Standard molecular techniques were used to re-type the patient and donor. ELISA antibody screening helped determine the patient's antibody specificity. RESULTS: The patient's type was HLA-B*1402,4703;Bw6 and the donor HLA-B*4703,51011;Bw4,6. Analysis of ELISA results identified three amino acids (positions 77,80,81) as the most likely epitope recognised by the patient's serum. These corresponded to HLA-B*51011 amino acid mismatches, explaining the lymphocytotoxic reactivity pattern. This epitope is located on a subgroup of the HLA-Bw4 antigen suggesting anti-Bw4 was not a sufficient description of this antibody. CONCLUSIONS: This report identifies an antibody to a sub-group of the Bw4 public specificity and also confirms the need for sequence-level analysis in the tissue-typing laboratory to determine future unacceptable mismatches.

Antilymphocyte Serum↗

PubMed2001

Intravenous administration of prochlorperazine by 15-minute infusion versus 2-minute bolus does not affect the incidence of akathisia: a prospective, randomized, controlled trial.

STUDY OBJECTIVE: We sought to compare the rate of akathisia after administration of intravenous prochlorperazine as a 2-minute bolus or 15-minute infusion. METHODS: We conducted a prospective, randomized, double-blind study in the emergency department of a central-city teaching hospital. Patients aged 18 years or older treated with prochlorperazine for headache, nausea, or vomiting were eligible for inclusion. Study participants were randomized to receive 10 mg of prochlorperazine administered intravenously by means of 2-minute push (bolus group) or 10 mg diluted in 50 mL of normal saline solution administered by means of intravenous infusion during a 15-minute period (infusion group). The main outcome was the number of study participants experiencing akathisia within 60 minutes of administration. Akathisia was defined as either a spontaneous report of restlessness or agitation or a change of 2 or more in the patient-reported akathisia rating scale and a change of at least 1 in the investigator-observed akathisia rating scale. The intensity of headache and nausea was measured with a 100-mm visual analog scale. RESULTS: One hundred patients were enrolled. One study participant was excluded after protocol violation. Seventy-three percent (73/99) of the study participants were treated for headache and 70% (70/99) for nausea. In the bolus group, 26.0% (13/50) had akathisia compared with 32.7% (16/49) in the infusion group (Delta=-6.7%; 95% confidence interval [CI] -24.6% to 11.2%). The difference between the bolus and infusion groups in the percentage of participants who saw a 50% reduction in their headache intensity within 30 minutes was 11.8% (95% CI -9.6% to 33.3%). The difference in the percentage of patients with a 50% reduction in their nausea was 12.6% (95% CI -4.6% to 29.8%). CONCLUSION: A 50% reduction in the incidence of akathisia when prochlorperazine was administered by means of 15-minute intravenous infusion versus a 2-minute intravenous push was not detected. The efficacy of prochlorperazine in the treatment of headache and nausea likewise did not appear to be affected by the rate of administration, although no formal statistical comparisons were made.

Adolescent↗

PubMed2001

Alignment and calibration of the MgF2 biplate compensator for applications in rotating-compensator multichannel ellipsometry.

Biplate compensators made from MgF2 are being used increasingly in rotating-element single-channel and multichannel ellipsometers. For the measurement of accurate ellipsometric spectra, the compensator must be carefully (i) aligned internally to ensure that the fast axes of the two plates are perpendicular and (ii) calibrated to determine the phase retardance delta versus photon energy E. We present alignment and calibration procedures for multichannel ellipsometer configurations with special attention directed to the precision, accuracy, and reproducibility in the determination of delta (E). Run-to-run variations in external compensator alignment, i.e., alignment with respect to the incident beam, can lead to irreproducibilities in delta of approximately 0.2 degrees . Errors in the ellipsometric measurement of a sample can be minimized by calibrating with an external compensator alignment that matches as closely as possible that used in the measurement.

Journal Article↗

PubMed2000

Volatile compounds from Escherichia coli O157:H7 and their absorption by strawberry fruit.

Volatile compounds emitted by cultures of two strains of the pathogenic bacterium Escherichia coliO157:H7 and a nonpathogenic strain of E. coli were trapped on Super-Q porous polymer and identified by GC-MS. The predominant compound produced by all three strains was indole with lesser amounts of other components including methyl ketones, 2-heptanone, 2-nonanone, 2-undecanone, and 2-tridecanone. The vapor-phase profiles of these strains were similar for most chemicals identified but differed with regard to ketones. Strawberry fruit was shown to be a suitable host for E. coli O157:H7 with the population of the bacterium either increasing or remaining stable after 3 days depending on inoculation level. Headspace analysis of the volatile compounds from inoculated fruit yielded no detectable quantity of indole. Strawberry fruit readily absorbed indole and other volatile compounds produced by the bacteria and in some cases metabolized the compounds to new volatile products. Thus, headspace "marker" compounds indicating possible bacterial contamination of fruit were largely removed from the vapor phase by the strawberries.

Absorption↗

PubMed1995

Medication cost savings associated with weight loss for obese non-insulin-dependent diabetic men and women.

BACKGROUND: The cost of diabetes mellitus can be defined in both medical and economic terms. Although there is an abundance of literature concerning the medical management of diabetes, few studies have assessed the financial impact of its treatment. This study examined the savings in prescription costs associated with a weight reduction program for obese men and women with non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: Forty subjects ages 40-70 years who had body mass indexes of 30-40 kg/m2 and NIDDM of more than 1 year duration were assigned to one of two 800-kcal weight-loss programs for 12 weeks. A cost analysis was done on the 32 subjects who were taking anti-hypertensive and/or anti-diabetes medications. A list of medications and monthly amounts was obtained at the start, upon completion, and 1 year following completion of the diet. The average out-of-pocket cost for a month's supply of each prescription was calculated by polling 16 retail pharmacies in Lexington, Kentucky. RESULTS: Subjects lost an average of 15.3 kg (33.7 lb) over the 12 weeks. At 1-year follow-up, subjects maintained a mean 9.0-kg (19.8 lb) weight loss. The average monthly prediet out-of-pocket cost for anti-hypertensive and anti-diabetes medications and supplies was $63.30 per subject. Following completion of the diet, this cost per month decreased to $20.40 and at 1-year follow-up the average monthly cost per subject was $32.40. The estimated average savings in prescription costs per subject over the year was $442.80. CONCLUSIONS: Significant short- and long-term savings in prescription costs were obtained following a 12-week hypocaloric weight reduction program for obese individuals with NIDDM.

Adult↗

PubMed1994

Food-containing hypocaloric diets are as effective as liquid-supplement diets for obese individuals with NIDDM.

OBJECTIVE: This study was designed to determine if food-containing hypocaloric diets are as effective as liquid-supplement diets in promoting weight loss for obese individuals with non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: Forty NIDDM subjects with body mass indexes (BMIs) of 30-40 kg/m2 were randomized to one of two 800-kcal diets for 12 weeks. Group A received liquid supplement only, and group B received supplement plus an evening meal. Both groups received an intensive behavioral education program. RESULTS: Weight loss and improvements in glycemic, blood lipid, and blood pressure parameters were similar for the two groups. Weight loss averaged 15.7 kg for the entire group. The need for insulin, anti-diabetes, and anti-hypertensive medication decreased significantly. No serious side effects were observed. CONCLUSIONS: Both food-containing and supplement diets providing 800 kcal a day effectively promote weight loss for obese individuals with NIDDM.

Body Mass Index↗

PubMed1980