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Biomedical subjects

J L Williams

Publications and source records attributed to J L Williams.

At least 55 records · Page 3Linked to original sources
PubMed2003

Comparison of a long spinal board and vacuum mattress for spinal immobilisation.

OBJECTIVES: This study was designed to compare the stability and comfort afforded by the long spinal board (backboard) and the vacuum mattress. METHODS: Nine volunteers wearing standardised clothing and rigid neck collars were secured on to a backboard and vacuum mattress using a standard strapping arrangement. An operating department table was used to tilt the volunteers from 45 degrees head up to 45 degrees head down, and additionally 45 degrees laterally. Movements of the head, sternum, and pubic symphysis (pelvis) from a fixed position were then recorded. The comfort level during the procedure was assessed using a 10 point numerical rating scale (NRS) where 1=no pain and 10=worst pain imaginable. RESULTS: The mean body movements in the head up position (23.3 v 6.66 mm), head down (40.89 v 8.33mm), and lateral tilt (18.33 v 4.26mm) were significantly greater on the backboard than on the vacuum mattress (p<0.01 for all planes of movement). Using the NRS the vacuum mattress (mean score=1.88) was significantly more comfortable than the backboard (mean score=5.22) (p<0.01). CONCLUSIONS: In the measured planes the vacuum mattress provides significantly superior stability and comfort than a backboard.

Beds↗
PubMed2003

A comparative map of bovine chromosome 19 based on a combination of mapping on a bacterial artificial chromosome scaffold map, a whole genome radiation hybrid panel and the human draft sequence.

We have constructed a medium density physical map of bovine chromosome 19 using a combination of mapping loci on both a bovine bacterial artificial chromosome (BAC) scaffold map and a whole genome radiation hybrid (WGRH) panel. The resulting map contains 70 loci spanning the length of bovine chromosome 19. Three contiguous groups of BACs were identified on the basis of multiple loci mapping to individual BAC clones. Bovine chromosome 19 was found in this study to be comprised almost entirely from regions of human chromosome 17, with a small region putatively assigned to human chromosome 10. Fourteen breakpoints between the bovine and human chromosomes were detected, with a possibility of five more based on ordering of the WGRH map.

Animals↗
PubMed2003

Estimation of linkage disequilibrium in a sample of the United Kingdom dairy cattle population using unphased genotypes.

The association between genetic marker alleles was estimated for two regions of the bovine genome from a random sample of 50 young dairy bulls born in the United Kingdom between 1988 and 1995. Microsatellite marker genotypes were obtained for six markers on chromosome 2 and seven markers on chromosome 6, spanning 38 and 20 cM, respectively. Two different methods, which do not require family information, were used to estimate population haplotype frequencies. Haplotype frequencies were estimated for pairs of loci using the expectation-maximization algorithm and for all linked loci using a Bayesian approach via a Markov chain-Monte Carlo algorithm. Significant (P = 0.0007) linkage disequilibrium was detected between pairs of loci in syntenic groups (that is, loci in the same linkage group), extending to about 10 cM. No significant linkage disequilibrium was detected between markers in nonsyntenic regions. Given the observed level of linkage disequilibrium, mapping methods based on population-wide association might provide a better resolution than traditional quantitative trait loci mapping methods in the U.K. dairy cattle population and may reduce the required sample sizes of the experiments.

Algorithms↗
PubMed2003

Effects of imprint training procedure at birth on the reactions of foals at age six months.

REASONS FOR PERFORMING STUDY: While imprint training procedures have been promoted in popular magazines, they have received limited scientific investigation. OBJECTIVES: To determine the effects of a neonatal imprint training procedure on 6-month-old foals and to determine if any one session had a greater effect than others. METHODS: Foals (n = 131) were divided into the following treatments: no imprint training, imprint training at birth, 12, 24 and 48 h after birth or imprint training only at birth, 12, 24, 48, or 72 h after birth. Foals then received minimal human handling until they were tested at 6 months. RESULTS: During training, time to complete exposure to the stimulus was significant for only 2 of 6 stimuli. Percentage change in baseline heart rate was significant for only 2 of 10 stimuli. These 4 effects were randomly spread across treatments. CONCLUSIONS: Neither the number of imprint training sessions (0, 1, or 4) nor the timing of imprint training sessions (none, birth, 12, 24, 48, or 72 h after birth) influenced the foal's behaviour at 6 months of age. POTENTIAL CLINICAL RELEVANCE: In this study, imprint training did not result in better behaved, less reactive foals.

Age Factors↗
PubMed2002

Creation of two tomographic voxel models of paediatric patients in the first year of life.

Tomographic computational models, based on regional segmentation of CT or MRI medical images, have increasingly been proposed as replacements for current stylized mathematical models of human anatomy used in radiation dosimetry studies. While much effort has been devoted towards the creation of adult models, few research studies have been initiated to address the need for models supporting paediatric radiology dosimetry. In this study, two tomographic models were created using a combination of automatic and manual segmentation via a program created in-house using IDL version 5.5. The first model is of a normal 6 day female newborn, and consists of a 512 x 512 x 485 data array. The CT slices of this model were obtained every 1 mm, and 66 different anatomic regions were defined. The second model is of a patient developmentally equivalent to a 2 month male, and was saved as a 512 x 512 x 438 data array. This subject had severe tissue oedema within the gut, kidneys, liver and spleen. The model is thus considered representative of a critically ill child, from a patient subpopulation expected to receive a larger than normal number of diagnostic x-ray exams. The voxel volumes for the two models are 0.35 mm3 and 0.30 mm3, respectively, thus making these models the most detailed in existence for paediatric dosimetry applications. Ratios of organ masses for the UF newborn model to those within the reference ORNL/MIRD model range from highs of 1.2 to 1.7 for the oesophagus and small intestine/colon, respectively, to lows of 0.18 to 0.27 for the mandible and humeri, respectively. For the UF 2 month model, ratios of organ masses in the UF model to those in the 8 week GSF BABY model ranged from highs of 3.7 to 5.2 for the clavicles and spleen, respectively, to lows of 0.2 to 0.3 for the adrenals and scapulae, respectively.

Anatomy, Cross-Sectional↗
PubMed2002

Comparisons of point and average organ dose within an anthropomorphic physical phantom and a computational model of the newborn patient.

Pediatric radiographic examinations yield medical benefits and/or diagnostic information that must be balanced against potential risk from patient radiation exposure. Consequently, clinical tools for measuring internal organ dose are needed for medical risk assessment. In this study, a physical phantom and Monte Carlo simulation model of the newborn patient were developed based upon their stylized mathematical expressions (ORNL and MIRD model series). The physical phantom was constructed using tissue equivalent substitutes for soft tissue, lung, and skeleton. Twenty metal-oxide-semiconductor field effect transistor (MOSFET) dosimeters were then inserted at three-dimensional positions representing the centroids of organs assigned in the ICRP's definition of the effective dose. MOSFET-derived point estimates of organ dose were shown to be in reasonable agreement with Monte Carlo estimates for representative newborn head, chest, and abdomen radiographic exams. Ratios of average organ dose assessed via MCNP simulations to the MOSFET-derived point doses (point-to-organ dose scaling factors, SF(POD)) are tabulated for subsequent use in clinical irradiations of the newborn phantom/MOSFET system. Values of SF(POD) indicate that MOSFET measurements of point dose for in-field exposures need to be adjusted only to within 10% to report volume-averaged organ dose. Larger adjustments to point doses are noted for organs out-of-field. For walled organs, point estimates of organ dose at the content centroid are shown to underestimate the average wall dose when the organ is within the primary field: SF(POD) of 1.19 for the stomach (AP chest exam), and SF(POD) of 1.15 for the urinary bladder (AP abdomen exam).

Abdomen↗
PubMed2002

Taking STOX: developing a cross disciplinary methodology for systematic reviews of research on the built environment and the health of the public.

STUDY OBJECTIVE: To develop a cross disciplinary literature search methodology for conducting systematic reviews of all types of research investigating aspects of the built environment and the health of the public. DESIGN: The method was developed following a comprehensive search of literature in the area of housing and injuries, using 30 databases covering many disciplines including medicine, social science, architecture, science, engineering, environment, planning and psychology. The results of the database searches, including the type (or evidence) of research papers identified, were analysed to identify the most productive databases and improve the efficiency of the strategy. The revised strategy for literature searching was then applied to the area of neighbourhoods and mental health, and an analysis of the evidence type of references was carried out. In recognition of the large number and variety of observational studies, an expanded evidence type classification was developed for this purpose. MAIN RESULTS: From an analysis of 722 citations obtained by a housing and injuries search, an overlap of only 9% was found between medical and social science databases and only 1% between medical and built environment databases. A preliminary evidence type classification of those citations that could be assessed (from information in the abstracts and titles) suggested that the majority of intervention studies on housing and injuries are likely to be found in the medical and social science databases. A number of relevant observational studies (10% of all research studies) would have been missed, however, by excluding built environment and grey literature databases. In an area lacking in interventional research (housing/neighbourhoods and mental health) as many as 25% of all research studies would have been missed by ignoring the built environment and grey literature. CONCLUSIONS: When planning a systematic review of all types of evidence in a topic relating to the built environment and the health of the public, a range of bibliographical databases from various disciplines should be considered.

Databases, Bibliographic↗
PubMed2002

Pressor responsiveness to angiotensin in soy-fed spontaneously hypertensive rats.

Dietary soy may attenuate the development of arterial hypertension. In addition, some soy-containing foods exhibit angiotensin-converting enzyme (ACE) inhibitory properties. Accordingly, we tested the hypothesis that ACE inhibition contributes to the antihypertensive effect of dietary soy. Mean arterial blood pressure (MAP) was recorded from conscious spontaneously hypertensive rats (SHR) at least 24 h after the implantation of catheters. Cumulative dose-response curves to intravenous angiotensin I (AI) (5-100 ng x kg(-1) x min(-1)) and angiotensin II (AII) (1-20 ng x kg(-1) x min(-1)) were constructed for male, sham-operated female, and ovariectomized female (OVX) SHR that were maintained on either casein or soy diets. The soy diet was associated with a significant reduction in baseline MAP in the OVX SHR (approximately 20 mmHg, 1 mmHg = 133.322 Pa). AI and AII infusions caused graded increases in MAP in all groups. However, there was no significant attenuation of the pressor responses to AI in the soy-fed SHR. Conversely, we observed a significant rightward displacement of the AII dose-response curves in the soy-fed sham-operated and OVX SHR. We conclude that ACE inhibition does not account for the antihypertensive effect of dietary soy in mature SHR.

Angiotensin I↗
PubMed2002

Estimation of pedigree errors in the UK dairy population using microsatellite markers and the impact on selection.

The proportion of cows in the UK dairy herd whose sires were misidentified was estimated using DNA markers. Genetic marker genotypes were determined on 568 cows (from 168 milk samples and 400 hair samples) and 96 putative sires (from semen samples). The estimated pedigree error rate from the hair samples was 8.8%, and from the milk samples, 13.1%, giving an overall estimate of the error rate of 10%. This level of pedigree errors will have a relatively large impact on the efficiency of progeny testing and the accuracy of cow predicted breeding values. We predict a loss of response to selection of approximately 2 to 3% given this error rate.

Animals↗
PubMed2001

Short stay after cleft palate surgery.

Although algorithms for the repair of soft and hard palatal clefts continue to be debated, the appropriate length of postoperative stay has not yet been defined. Recent reports of cleft palate repair advocate a 2- to 5-day hospitalization. The plastic surgery service at St. Joseph Hospital frequently uses same-day admission with 23-hour observation postoperatively, with no increase in complications from the reported 2- to 5-day stay. The authors inspected the records for all the cleft palate patients undergoing cleft repair at St. Joseph Hospital Cleft Clinic from August of 1988 through June of 1998. After excluding syndromic patients and secondary or revision surgical cases, 79 patients remained in the study. These 79 patients underwent 104 procedures; all procedures were performed by a single surgeon (E.D.C.) with resident assistance. Short-term morbidity, length of stay, and operation performed were studied. All patients were admitted the day of surgery. Mean age at the time of operation was 13.2 months, with a range of 6 months to 20 years. The length of operation averaged 1 hour and 37 minutes; 94 percent of patients stayed 24 hours or less postoperatively, and 97 percent stayed 36 hours or less. The longest stay was 72 hours, which was related to delay in resuming adequate oral intake. The overall complication rate was 3.8 percent for this cohort, which included two partial palatal dehiscences and two small fistulas. No blood transfusions were needed, and no infections were noted postoperatively. No patients required readmission postoperatively for bleeding, respiratory compromise, or inadequate oral intake. The authors do not advocate a 1-night stay for all cleft palate cases. However, they do think it is safe for a healthy group of patients undergoing routine cleft palate surgery. The decision to discharge a patient early must always be left to the treating physician.

Adolescent↗
PubMed2001

Evaluation of the response to a booster dose of hepatitis B vaccine in previously immunized healthcare workers.

INTRODUCTION: Hepatitis B vaccination is recommended for all healthcare workers (HCW) at risk of exposure to infectious body fluids. However, the absolute duration of protection from immunization is unknown. The purpose of this randomized comparison trial was to determine how previously immunized HCW respond to different booster doses of hepatitis B vaccine. METHOD: Adult HCW (n=59) were classified by level of hepatitis B surface antigen (anti-HBs), either <10 milli-International Units per milliliter (mIU/ml) or 10-50 mIU/ml. Participants were then randomized to receive a 2.5 or 10 microg dose of hepatitis B vaccine. Evaluation of anti-HBs levels were conducted 10 to 14 days, one month and one year postbooster. RESULTS AND DISCUSSION: All participants responded to the booster dose with increased anti-HBs levels. At 14 days, mean anti-HBs levels were significantly higher for those with higher levels at baseline (P=0.004) and those receiving the 10 microg dose (P=0.016). At one month, those with higher anti-HBs levels at baseline and those receiving the 10 microg dose were significantly higher (P<0.01 for both). At one year, the increase for the higher dose was no longer statistically significant when examined by itself (P=0.081); statistical significance (P=0.021) was achieved after adjusting for anti-HBs level at baseline. For all participants, the geometric mean anti-HBs level was 2618 mIU/ml at 14 days, 2175 mIU/ml at one month and 88.9 mIU/ml at one year. At all time points the increase in anti-HBs levels represented an increase over the geometric mean baseline level of anti-HBs (7.4 mIU/ml). Hepatitis B immunized adults responded to a booster dose of hepatitis B vaccine from 3 to 13 yr postvaccination series. Data support current recommendations that immunized HCW do not require periodic antibody testing or vaccine boosters.

Adult↗
PubMed2001

Brief report on the effect of providing single versus assorted brand name condoms to hospital patients: a descriptive study.

OBJECTIVES: This study examined condom acquisition by persons in a hospital setting when single versus assorted brand name condoms were provided. METHODS: Condom receptacles were placed in exam rooms of two clinics. During Phase 1, a single brand name was provided; for Phase 2, assorted brand names were added. Number of condoms taken was recorded for each phase. RESULTS: For one clinic there was nearly a two-fold increase in number of condoms taken (Phase 1 to Phase 2); for the second clinic there was negligible difference in number of condoms taken. CONCLUSIONS: The provision of assorted brand name condoms, over a single brand name, can serve to increase condom acquisition. Locations of condoms and target population characteristics are related factors.

Adolescent↗
PubMed2001

Epithelial permeability is not increased in rats following small bowel resection.

BACKGROUND: Increased intestinal permeability and translocation of bacteria and/or bacterial products may cause infection and liver dysfunction in patients with the short bowel syndrome. In previous studies, serum from mice undergoing small bowel resection (SBR) enhanced growth of cultured rat intestinal epithelial cells (RIEC-6), implicating a role for a serum factor(s) in the enterocyte response to SBR. These experiments tested the hypothesis that epithelial cell permeability is increased following SBR. MATERIALS AND METHODS: Male Sprague-Dawley rats underwent a 75% SBR or sham operation. Intestinal permeability in the remnant ileum was determined by Ussing chambers on Postoperative Day (POD) 3. Additionally, serum was collected on POD 1, 3, and 7 and mesenteric lymph was harvested on POD 3. Once confluent, RIEC-6 cells were incubated for 3 days in media supplemented with 10% fetal bovine serum (FBS; control), 1% FBS, 1% FBS plus 9% Sham serum, or 1% FBS plus 9% SBR serum or exposed to media with varied concentrations of SBR or Sham lymph. Monolayer permeability was determined by measuring the passage of dextran-rhodamine. RESULTS: Intestinal permeability was reduced in rats undergoing SBR. Sham serum-treated monolayers demonstrated the greatest permeability. Incubation with SBR serum reduced permeability to near control media. There were no permeability differences between SBR and Sham lymph-treated monolayers. CONCLUSION: The early adaptive response of the remnant intestine after SBR is associated with reduced permeability. These results suggest an alternative mechanism for the increased bacterial translocation that has been described following SBR.

Adaptation, Biological↗
PubMed2001

Nitric oxide-releasing nonsteroidal anti-inflammatory drugs (NSAIDs) alter the kinetics of human colon cancer cell lines more effectively than traditional NSAIDs: implications for colon cancer chemoprevention.

Nitric oxide-releasing nonsteroidal anti-inflammatory drugs (NO-NSAIDs), consisting of a known nonsteroidal anti-inflammatory drug (NSAID) and a nitric oxide (NO)-releasing group, are reported safer than NSAIDS: To assess their potential in colon cancer chemoprevention, we studied in vitro the effect of NO-aspirin, NO-sulindac, and NO-ibuprofen on colonocyte kinetics. These three NO-NSAIDs reduced the growth of cultured HT-29 colon adenocarcinoma cells much more effectively than the corresponding NSAIDs; e.g., at 24 h, their IC(50) values were as follows: (a) aspirin, >5000 microM; (b) NO-aspirin, 1 microM; (c) sulindac, 750 microM; (d) NO-sulindac, 150 microM; (e) ibuprofen, >1000 microM; and (f) NO-ibuprofen, 42 microM. This effect was due to inhibition of proliferation and induction of apoptosis and perhaps to the induction of novel cell changes, characterized by extensive DNA degradation. NO-NSAIDs also blocked the G(0)-G(1) to S cell cycle transition. Their superior effectiveness compared with traditional NSAIDs, combined with their reported safety, makes them promising candidates for chemopreventive agents against colon cancer.

Adenocarcinoma↗