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Biomedical subjects

F L Williams

Publications and source records attributed to F L Williams.

At least 19 recordsLinked to original sources
PubMed1999

Screening practices for gestational diabetes mellitus in UK obstetric units.

AIM: To identify current screening practices for gestational diabetes mellitus (GDM) in all maternity units. METHODS: A questionnaire was sent to the senior obstetrician of all obstetric units known to the UK Royal College of Obstetricians and Gynaecologists. RESULTS: A response rate of 84% was achieved. 89% of units reported that they screened for GDM with a wide variation in the screening methods used, both between and within units. The most commonly employed procedure (81% of units) was screening based on the presence of maternal risk factors. The 75 g oral glucose tolerance test (OGTT) was the commonest diagnostic test (79% of units). Sixty-six per cent of units operate a combined diabetic antenatal clinic and 58% of units have written guidelines for screening. Seventy-six per cent of units would welcome national guidelines. CONCLUSION: The majority of obstetric units in the UK screen for GDM but with little consensus on the appropriate screening methods. National guidelines would probably be welcomed.

Diabetes, Gestational↗
PubMed1998

Assessment of uterine arterial notching as a screening test for adverse pregnancy outcome.

OBJECTIVE: The objective of the study was to evaluate the screening potential of routine uterine arterial Doppler ultrasonography as a predictor of adverse pregnancy outcome. STUDY DESIGN: All women (n = 6579) with singleton pregnancies undergoing a fetal anomaly scan at 18 to 20 weeks' gestation between January 1, 1994, and December 31, 1995, at Ninewells Hospital and Medical School were screened for the presence of uterine arterial notching. Women who had evidence of bilateral notching were rescanned at 22 to 24 weeks' gestation. Outcome measures included proteinuric hypertension, premature separation of the placenta, and birth weight z score. RESULTS: The sensitivity and positive predictive value of uterine arterial notching as a predictor of adverse pregnancy outcomes was low. For all types of notching and disease, outcome sensitivity was never higher than 44% and positive predictive value was never higher than 27%. In contrast, the relative risk of adverse pregnancy outcome in the presence of uterine arterial notching was uniformly high for all disease outcomes (range of relative risk 3.5-30.7). Significant obstetric morbidity was seen in 57% of women with bilateral notches at 18 to 20 weeks' gestation and 72% of women with persistent bilateral notches. CONCLUSIONS: As a screening test for adverse pregnancy outcomes, detection of uterine arterial notching is poor. Nevertheless, the presence of bilateral uterine arterial notching is associated with a significantly increased risk of adverse pregnancy outcome. In units performing routine anomaly screening, the addition of maternal uterine arterial Doppler ultrasonography may help to discriminate this small group of women at high risk.

Adolescent↗
PubMed1998

Episiotomy and perineal tears in low-risk UK primigravidae.

BACKGROUND: The aim of the study was to determine the rates and to describe the risk factors for episiotomy and perineal tears in low-risk primigravidae. METHOD: A cross-sectional survey of 101 randomly selected NHS hospitals in the UK was carried out between February 1993 and January 1994. Subjects were 40 consecutive low-risk primigravidae in each hospital. The main outcome measures were number and reasons for episiotomy, and number and degree of perineal tears. RESULTS: A large proportion of women (83 per cent) experienced some form of perineal trauma. Forty per cent of the women had an episiotomy only, 6 per cent an episiotomy and perineal tear, and 37 per cent perineal or other tears without episiotomy. The main reasons for performing an episiotomy were foetal distress (27 per cent), impending tear (25 per cent) and delay of the second stage of labour (21 per cent). Fifty-nine per cent of women with a delayed second stage had a spontaneous vaginal delivery and 41 per cent required instrumental assistance. The likelihood of having an episiotomy increased with the duration of the second stage of labour, irrespective of type of delivery. Episiotomy rates varied appreciably throughout regions and hospitals in the United Kingdom, ranging from 26 to 67 per cent. There was also a large regional variation in the rates of perineal trauma; generally, high rates of one outcome were associated with low rates of the other. Compared with white women, women from the Indian sub-continent were almost twice as likely and those from the Orient almost five times as likely to have an episiotomy. CONCLUSIONS: The magnitude of the geographical variation suggests a lack of uniformity in indications for performing episiotomies and that guidelines for performing episiotomies may need to be reviewed. The rates of episiotomy in women from the Indian sub-continent and Orient were very high compared with those for white women, and this requires clarification and explanation, as they are contrary to rates experienced in these ethnic groups in other countries.

Adult↗
PubMed1998

UK study of intrapartum care for low risk primigravidas: a survey of interventions.

STUDY OBJECTIVE: To determine the extent of intrapartum intervention received by primigravidas. DESIGN: Cross sectional survey of NHS hospitals in the UK. SETTING: One hundred and one randomly selected hospital maternity units. PARTICIPANTS: Forty consecutive primigravid women, judged to be at low risk at the start of labour, in each hospital. MAIN OUTCOME MEASURES: Seven groups of interventions or monitoring procedures were identified from the first, second, and third stages of labour: fetal monitoring, vaginal examinations, artificial rupture of membranes, augmentation of labour, pain relief, type of delivery, and episiotomy. Data were collected during 1993. MAIN RESULTS: Ninety eight hospitals took part in the study and data were collected on 3160 low risk primigravidas. Seventy four per cent of these women had continuous cardiotocography. The proportion of women having restrictive or invasive fetal monitoring showed appreciable geographical variation for both the first and second stages of labour. Using the criterion of a vaginal examination every four hours and allowing for the length of each woman's labour, 72% had more vaginal examinations than expected; there was a significant geographical variation in the number of women receiving more than five examinations. Fifty three per cent had artificial rupture of membranes; the procedure was performed over a wide range of cervical dilatations (0 cm-10 cm). Thirty eight per cent of labours were augmented, most commonly by intravenous syntocinon; the procedure showed significant geographical variation. Twenty eight per cent had a spinal block or epidural analgesia for the relief of pain; this intervention varied by geographical region only for the second stage of labour. Over one quarter of the women required instrumental delivery. Forty six per cent had an episiotomy; the frequency of this intervention varied substantially by region. There were no infant deaths. Twelve babies were recorded at birth as having a congenital anomaly. CONCLUSIONS: The rates of several interventions seem high for this low risk group and there was substantial geographical variation in the use of six interventions. Clinical trials are needed to evaluate the optimum criteria for using these interventions from which guidelines should be drawn up by local groups and the Royal College.

Adolescent↗
PubMed1998

Relationship of feeder lamb frame size to feedlot gain and carcass yield and quality grades.

Small-(S), medium-(M), and large-(L) framed feeder lambs (n = 243 S, 247 M, and 245 L) were finished on five diets differing in amount of concentrate (C) and crude protein (CP): 1) 30% C, 12.5% CP; 2) 55% C, 12.5% CP; 3) 55% C, 14.5% CP; 4) 80% C, 12.5% CP; and 5) 80% C, 14.5% CP. Lambs were sampled over a wide weight range to establish relationships of frame size to daily gain and live weight at specific carcass grade end points. Increased frame size (F) was associated with more rapid gains during finishing, although differences in daily gain among L, M, and S lambs were not expressed consistently across all dietary treatments (D), as reflected by a significant F x D interaction for ADG. The rate at which external fat thickness increased as the lambs became heavier was not affected by frame size, sex, or diet. However, increased frame size was associated with lower (P < .05) values for fat thickness (FT), body wall thickness (BWT), yield grade (YG), and quality grade (QG) when comparisons were made at a constant slaughter weight. Similarly, later-maturing wether lambs were leaner and had lower YG and QG than ewes of the same weight. Dietary treatment had no effect on FT, BWT, and YG when treatment groups were compared at a constant live weight. Subclass regressions of YG on live weight were used to project the weights at which lambs of various frame sizes would be expected to produce YG-2 carcasses. Projected final weights for wethers were less than 50 kg for S, 50 to 55 kg for M, and greater than 55 kg for L. Projected final weights for ewe lambs were approximately 2.5 kg lower. Dietary treatment did not affect relationships among frame size, live weight, and YG. A grading/classification system for feeder lambs based on frame size could be developed to predict carcass grade end point.

Animal Feed↗
PubMed1998

Relationship of visual assessments of feeder lamb muscularity to differences in carcass yield traits.

We examined the relationship between visual differences in muscle thickness among feeder lambs and subsequent differences in carcass composition. Medium-framed, crossbred feeder lambs (n = 120) were selected at two commercial feedlots to exhibit distinct phenotypic differences in muscularity. The lambs were assigned scores (ranging from 1 to 9; 1 = extremely thin, 5 = average, 9 = extremely thick) for muscle thickness and were sampled serially on d 0, 14, 28, and 42 of the trial. After recording yield grades, one side of each carcass was deboned, and the soft tissues from the entire side were ground, sampled, and analyzed for lipid and moisture content. The opposite side was fabricated into boneless, closely trimmed (.25 cm maximum fat depth) subprimal cuts. When lambs of the same frame size were compared at the same live weight, greater muscle thickness was associated with greater (P < .05) fat-free muscle mass. Correspondingly, thickly muscled lambs produced carcasses of a given weight that had a higher (P < .05) composite yield of lean meat and a lower (P < .05) proportion of trimmable fat compared with carcasses of thinly muscled lambs. When comparisons were made at the same percentage of extractable fat in the carcass, greater muscle thickness was associated with heavier (P < .05) live and carcass weights, increased (P < .05) fat-free muscle mass, and increased (P < .05) weights of trimmed, boneless subprimal cuts. Results suggest that visual assessments of muscle thickness in feeder lambs, as applied in this study, are indicative of commercially important differences in carcass yields of lean meat.

Adipose Tissue↗
PubMed1998

Prediction of slaughter cow composition using live animal and carcass traits.

Slaughter cows (n = 120), representing four genotypes (British, continental, Bos indicus, and dairy) and three body condition classes (thin, moderate, and fat), n = 10 per subclass, were used to identify practical and accurate prediction equations for the yield of boneless manufacturing beef of specific fat percentages. Cows and their carcasses were weighed and evaluated for USDA yield and quality grade factors and for physical muscle and fat indicators. Carcass sides were fabricated; total fat percentage (TFP) was calculated as total fat (trimmed and chemical) divided by side weight, and tissue lean percentage (TLP) was calculated as boneless fat-free lean divided by soft tissue weight. Data were analyzed using maximum R2 multiple regression. The best live trait prediction model for TFP included live preliminary yield grade (LPYG), body condition score (LCOND), visual live muscle score (LMUSC), and live weight (LWT), R2 = .83. The best carcass trait TFP prediction model included adjusted preliminary yield grade (CPYGA); kidney, pelvic, and heart fat adjustment (CKPHADJ); marbling score (CMARB); and hot carcass weight (HCW), R2 = .92. The best live trait TLP prediction model included LPYG, LCOND, LMUSC, and LWT, R2 = .82. The best carcass trait TLP prediction model included CPYGA, CKPHADJ, CMARB, and lean maturity, R2 = .91. These data indicate that TFP and TLP of slaughter cows can be accurately and practically predicted using live animal and carcass traits.

Animals↗
PubMed1998

An evaluation of current and alternative systems for quality grading carcasses of mature slaughter cows.

Strip loins from 354 female bovine carcasses, selected to represent 30 skeletal maturity (A, B, C, D, and E) x marbling score (SA/MA/AB, MD, MT, SM, SL, and TR/PD) subclasses, were used to evaluate current and alternative systems for classifying cow carcasses into expected-palatability groups. Strip loins were vacuum-packaged, stored for 14 d postmortem at 2 degrees C, and frozen (-27 degrees C). Five steaks from each strip loin, each cooked to a different internal temperature (60, 66, 71, 77, or 82 degrees C), were used for shear force determinations. Two steaks from each strip loin, one cooked to 66 degrees C and the other to 77 degrees C, were used for sensory evaluation. Increased carcass maturity was associated with decreased tenderness and juiciness, increased flavor intensity, and a higher incidence of flavors described as "painty," "fishy," and "grassy." Position of a carcass within a maturity group had a negligible effect on palatability. Increased marbling was associated with greater tenderness and juiciness, a lower incidence of steaks with a "grassy" flavor, and a higher incidence of steaks with a flavor described as "fatty." Relationships between marbling and beef palatability traits were consistent across all maturity groups. Carcasses of maturities A through E were most effectively stratified according to differences in palatability when marbling scores were grouped as follows: 1) MD and higher; 2) SL, SM, MT; and 3) TR/PD. Among mature (C, D, and E maturity) carcasses, yellow-colored fat was associated with greater beef toughness and higher detection rates for "grassy" and "fishy" flavors. Higher end-point temperatures were associated with higher shear force values and lower ratings for muscle fiber tenderness, connective tissue amount, overall tenderness, and juiciness. Two alternative grading approaches (one involving current quality grading factors and the other involving the use of fat color as an additional grade factor) were developed for possible use in classification of cow carcasses into expected-palatability groups. Both alternative systems provided a more effective stratification of cow carcasses according to palatability differences than did the current USDA quality grading system.

Age Factors↗
PubMed1995

Limb joint surface areas and their ratios in Malagasy lemurs and other mammals.

Surface areas of humeral and femoral heads scale largely as a function of body size. However, differences in the relative sizes of these articular surfaces are correlated with differential joint mobility and force transmission through fore- and hindlimbs. They can therefore assist interpretation of the positional behavior of extinct species. In this paper, we document variation in ratios of humeral head surface area to femoral head surface area among extant primates and other mammals. We then examine a group of extinct primates: the subfossil lemurs of Madagascar. Many Malagasy lemurs, including some giant extinct species with very long forelimbs and short hindlimbs, have relatively small humeral heads and large femoral heads. We explore the adaptive implications of this pattern.

Animals↗
PubMed1995

Sex ratios of births, mortality, and air pollution: can measuring the sex ratios of births help to identify health hazards from air pollution in industrial environments?

OBJECTIVES: To compare the sex ratios of births and mortality in 12 Scottish localities with residential exposure to pollution from a variety of industrial sources with those in 12 nearby and comparable localities without such exposure. METHODS: 24 localities were defined by postcode sectors. SMRs for lung cancer and for all causes of death and sex ratios of births were calculated for each locality for the years 1979-83. Log linear regression was used to assess the relation between exposure, sex ratios, and mortality. RESULTS: Mortalities from all causes were consistently and significantly higher in the residential areas exposed to air pollution than in the non-exposed areas. A similar, but less consistently significant, excess of mortality from lung cancer in the exposed areas was also found. The associations between exposure to the general air pollution and abnormal sex ratios, and between abnormal sex ratios and mortality, were negligible. CONCLUSIONS: Sex ratios were not consistently affected when the concentrations or components of the air pollution were insufficiently toxic to cause substantially increased death rates. Monitoring of the sex ratio does not provide a reliable screening measure for detecting cryptic health hazards from industrial air pollution in the general residential environment.

Air Pollutants↗
PubMed1993

Applications of extraction mapping in environmental epidemiology.

This paper discusses a new method which allows the extraction of a background disease rate from a data set consisting of spatial co-ordinates of morbidity or mortality events. We demonstrate its application with two data sets, one based on cancer registry data and the other on death certificates.

Air Pollutants↗
PubMed1993

Effects of feeder cattle frame size, muscle thickness, and age class on days fed, weight, and carcass composition.

Feeder steers (n = 189) representing nine frame size x muscle thickness subclasses were started on a high-concentrate diet as calves, yearlings, or long yearlings and slaughtered at a constant s.c. fat thickness (13.5 mm) to determine the effects of feeder cattle frame size (large, medium, small), muscle thickness (No. 1, No. 2, No. 3), and age class on carcass traits and composition. After slaughter, one side of each carcass was physically separated into muscle, fat, and bone. Subcutaneous, intermuscular, and internal fat depot percentages were calculated as proportions of total fat weight. Effects of age class, frame size, and muscle thickness were significant for time-on-feed, slaughter weight, and carcass weight. Among age classes, long yearling steers required the fewest (P < .05) days on feed and heaviest (P < .05) live weights to reach the fat thickness end point. Increased frame size and decreased muscle thickness were associated with greater time-on-feed and heavier weights at slaughter. However, the effects of muscle thickness on slaughter traits were not consistent among frame and age subclasses; effects were greatest among large-framed steers and smallest among long yearling steers. Compositional differences (P < .05) were noted among age and muscle subclasses. Long yearling steers had the lowest (P < .05) percentage of bone among all age classes and a higher (P < .05) percentage of fat than steers fed as calves. No. 2 steers had the highest (P < .05) percentage of bone and the lowest (P < .05) muscle:bone ratio among muscle thickness groups; no (P > .05) compositional differences were observed between No. 1 and No. 3 steers. Differences in muscle:bone ratio, though statistically significant, were relatively small in magnitude and were not directionally consistent with differences in muscle thickness. Differences in fat partitioning were noted among frame and muscle subclasses. Large-framed steers had the lowest (P < .05) percentage of s.c. fat and the highest (P < .05) percentage of internal fat among frame sizes. No. 3 steers deposited the lowest (P < .05) percentage of intermuscular fat and the highest (P < .05) percentage of internal fat.

Adipose Tissue↗
PubMed1992

Low sex ratios of births in areas at risk from air pollution from incinerators, as shown by geographical analysis and 3-dimensional mapping.

Previous research in environmental and occupational health has suggested that fluctuations in the sex ratios of births might provide a useful early warning to the possible health effects of toxins or other stresses in the environment. To examine further this hypothesis, we investigated the sex ratios of births in an area in central Scotland which contained two incineration plants. Analyses of the sex ratios, at various levels of geographical detail and using 3-dimensional mapping techniques, in the residential areas at risk from airborne pollution from these incinerators showed locations with statistically significant excesses of female births.

Air Pollution↗
PubMed1992

Effect of frame size, muscle score, and external fatness on live and carcass value of beef cattle.

Commercial slaughter steers (n = 329) and heifers (n = 335) were selected to vary in slaughter frame size and muscle thickness score, as well as adjusted 12th rib fat thickness. After USDA carcass grade data collection, one side of each carcass was fabricated into boneless primals/subprimals and minor tissue components. Cuts were trimmed to 2.54, 1.27, and .64 cm of external fat, except for the bottom sirloin butt, tritip, and tenderloin, which were trimmed of all fat. Four-variable regression equations were used to predict the percentage (chilled carcass weight basis) yield of boneless subprimals at different fat trim levels (.64, 1.27, and 2.54 cm) as influenced by sex class, frame size, muscle score, and adjusted 12th rib fat thickness. Carcass component values, total carcass value, carcass value per 45.36 kg of carcass weight, and live value per 45.36 kg of live weight were calculated for each phenotypic group and external fat trim level. Carcass fatness and muscle score had the most influence on live and carcass value (per 45.36 kg weight basis). Carcasses with .75 and 1.50 cm of fat at the 12th rib were more valuable as the trim level changed from 2.54 cm to .64 cm; however, for carcasses with 2.25 cm of fat at the 12th rib, value was highest at the 2.54 cm trim level. Value was maximized when leaner cattle were closely trimmed. There was no economic incentive for trimming light-muscled or excessively fat carcasses to .64 cm of external fat.

Adipose Tissue↗
PubMed1992

Development of a quantitative quality grading system for mature cow carcasses.

Data from 400 cow carcasses were used to develop a new quality grading system. First principal component (FPC) values were determined for shear force (SHR) and palatability attributes of tenderness, connective tissue amount, flavor, and juiciness (JUC). Associated eigenvector load values for those traits were -.48, .54, .51, .46, and .05, respectively, and FPC values ranged from -3.20 to 2.18. Linear regression, using FPC as the independent variate, and SHR and palatability attributes (8-point scale, where 8 was highest) as dependent variates explained a significant amount of variation (P less than .001) in all traits, except JUC, and resulted in R2 values of .71, .89, .80, .66, and .01, respectively. A predictive quality-grade equation was developed using FPC as the dependent variate, and overall maturity (OM), lean color, marbling score (MS), lean firmness, lean texture, fat color (FC), and marbling fineness ([marbling texture + marbling distribution]/2; 8-point scale, where 8 was highest) as independent variates. The resulting best-fit prediction equation (FPC = -.052-[.0031 x OM] + [.0013 x MS] + [.31 x FC]) explained a significant amount (P less than .001) of variation in FPC with R2 = .53, Cp = 15.0, and residual standard deviation = .69. A short-cut equation was developed from this prediction equation. Simple correlations for OM, MS, and FC with FPC were -.56, .39, and .64, respectively. Cow carcasses were assigned to one of three quality grades based on FPC values that corresponded with predetermined acceptability levels for each palatability trait. Newly developed grades were quantitative and less variable than existing grades. Future grades for cow carcasses should include fat color to predict palatability.

Adipose Tissue↗
PubMed1992

Development of a multivariate yield grade equation to predict compositional traits in mature cow carcasses.

Data from 68 cow carcasses were used to develop a new yield grading system. First principal component (FPC) values for compositional attributes (LNFT = separable lean weight/[lean+fat weight] x 100, LNBN = separable lean weight/[lean+bone+connective tissue weights] x 100, and BTPR = [defatted lean from the round, loin, rib, and chuck]/side weight x 100) were determined. The first component explained 83.5% of the standardized variance and load values were .63, -.52, and .58, respectively. The resulting FPC values ranged from -1.93 to 1.89. The linear regression of LNFT, LNBN, and BTPR (dependent variables) on FPC (independent variable) explained a significant amount of variation (P less than .001) in each case and resulted in R2-values of .98, .67, and .85, respectively. A best-fit yield grade equation, developed to predict FPC, included adjusted fat thickness (ADF), percentage of kidney, pelvic, and heart fat (KPH), and overall muscling grade (OM). The equation, FPC = 2.04 - (.67 x ADF) - (.21 x KPH) - (.0016 x OM), explained a significant amount (P less than .001) of variation in FPC with R2 = .94 and residual standard deviation = .25. Simple correlations for ADF, KPH, and OM with FPC were -.87, -.71, and -.80, respectively. Cow carcasses were assigned to one of three grades based on FPC values that corresponded with predetermined levels of LNFT, LNBN, and BTPR. These grades generally had smaller CV than existing grades. When used in conjunction with quality grades, proposed grades could be more useful to the cow meat industry.

Abattoirs↗