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Biomedical subjects

M Holt

Publications and source records attributed to M Holt.

At least 19 recordsLinked to original sources
PubMed2006

Compartment syndrome following total knee arthroplasty: a report of seven cases.

Compartment syndrome is a rare complication of total knee arthroplasty that requires early recognition and prompt decompression in order to prevent long-term disability. We have found only one previous case report in the literature. We present a series of seven cases from four hospitals and five surgeons. Six of the cases resulted in the loss of at least one compartment, and one resulted in amputation. Four of the cases resulted in legal action. We suggest that important risk factors contributing to the development of this condition include complex surgery, soft-tissue compromise, previous surgery, and possibly vascular disease. Delay in the diagnosis and hence delay in decompression was common in our series, and in five cases appeared to be related to the use of a postoperative epidural infusion for pain relief. The presence of associated neurological compromise may have also been a significant factor in the delay to diagnosis in two cases.

Adult↗
PubMed2006

Lactational performance of Quackenbush Swiss line 5 mice.

We evaluated 2 strains of mice for their utility in the investigation of nutritional and molecular regulatory mechanisms of lactation. The lactational performance and milk composition were characterized for an inbred mouse strain, inbred Quackenbush Swiss line 5 (QSi5) selected persistently for fecundity, and a nonselected strain, CBA. The milk yield assessed by changes in BW in response to suckling of sustainable litter sizes for each strain was 3-fold greater (P < 0.001) in QSi5 mice than the CBA strain. The QSi5 mice also produced milk more efficiently (P < 0.001) than CBA mice, despite having the same quantity of mammary tissue per unit of BW. Milk composition did not vary between strains or by stage of lactation, with the exception of lactose concentration, which was greater (P = 0.003) in QSi5 mice. Expression of epsilon-casein was > or = 10-fold greater, and alpha(S1)-casein was > or = 3-fold greater, during mid and late lactation compared with early lactation in both strains, whereas kappa-casein underwent an apparent alteration in posttranslational modifications in both strains from early to mid lactation. Changes in casein composition coincided with an increased susceptibility to proteolytic degradation; hence milk from early lactation may be more readily degraded to facilitate digestion in the neonate. The greater milk synthetic capacity of QSi5 mice over the lactation cycle provides a useful model for studies of nutritional and molecular regulation of lactation.

Animals↗
PubMed2005

Microstructure of ferroelectric domains in BaTiO3 observed via x-ray microdiffraction.

X-ray microdiffraction utilizing Fresnel zone plate focusing optics has been used to study microstructural properties of individual 90 degree ferroelectric domains in BaTiO3. Diffraction measurements at a microfocused spot resolution of 0.3 microm over domain widths of approximately 10 microm unambiguously reveal features of lattice buckling, rotation, and strain near domain boundaries. Our results may be understood within the context of bound residual strain due to lattice mismatch and elastic interactions between neighboring domains.

Journal Article↗
PubMed2005

Long-term responses, changes in genetic variances and inbreeding depression from 122 generations of selection on increased litter size in mice.

Data on mice selected for litter size over 122 generations have been analysed in order to reveal the effect of long-term selection on responses and changes in variances over a long selection period. Originally, three lines were established from the same base population, namely an H line selected for large litter size, an L line selected for small litter size and a K line without selection. In generation 122, the mean number of pups born alive (NBA) was 22 for the H line and 11 for the K line. Phenotypic response to selection is reduced over generations, but crossing of plateaued lines increased responses and realized heritabilities. Both realized heritabilities and heritabilities from residual maximal likelihood (REML) analyses were, in general, calculated from generation (-1)-44 (period 1), 45-70 (period 2) and 71-122 (period 3) separately. Realized heritabilities were in general smaller than heritabilities estimated from mixed model analysis. An overall estimate of heritability for NBA was found to be 0.19 (+/- 0.01) by REML analysis. Additive variance is constant over all periods in the high line and the control line, but is reduced over periods in the low line. The reduction of additive variance in the low line could probably be explained by changes in gene frequencies. In all lines, environmental variances increased over periods. Inbreeding reduced the mean litter size by 0.72 (+/- 0.10) pups per 10% increase in inbreeding, with substantial variance between periods and lines.

Animals↗
PubMed2004

Components of litter size in mice after 110 generations of selection.

The aim of the present study was to evaluate how ovulation rate and survival rate through pregnancy had been affected by more than 110 generations of upwards selection on litter size in mice. The mean number of pups born alive was 22 in the high line (selected line) and 11 in the control line (an increase in 2.6 standard deviations). Selection on litter size increased ovulation rate by 4.6 standard deviations, and it is suggested that selection also increased embryonic mortality in late pregnancy. Embryo survival from ovulation until birth was 66% in the selected line and 69% in the control line, and the observed loss in litter size from day 16 of pregnancy until birth was possibly higher in the high line compared with the control line. Selection for higher litter size has significantly increased body weight in both males and females, as the mean weight at mating for the females was 46 g in the high line and 33 g in the control line respectively.

Animals↗
PubMed2003

Oesophageal cancer and cachexia: the effect of short-term treatment with thalidomide on weight loss and lean body mass.

BACKGROUND: Cachexia is common in patients with advanced cancer and has a direct impact on well-being and mortality. AIM: To test the hypothesis that thalidomide can promote weight gain and lean body mass in patients with advanced oesophageal cancer. METHODS: In an open-label study, 11 patients with non-obstructing and inoperable oesophageal cancer were established on an isocaloric diet for 2 weeks, followed by 2 weeks on thalidomide, 200 mg daily. The primary end-points were weight change and lean body mass. Secondary end-points were quality of life and changes in resting energy expenditure. RESULTS: Ten patients completed the study protocol. The average caloric intake remained the same throughout the study period in all patients. Nine of 10 patients (95% confidence interval, 0.60, 0.98) lost weight on diet alone. The mean weight gain on thalidomide in the following 2 weeks was 1.29 kg (median, 1.25 kg). A similar trend was shown in the lean body mass. Eight of nine patients (95% confidence interval, 0.57, 0.98) initially lost lean body mass on diet alone (missing data in one patient). The mean gain in lean body mass on thalidomide in the following 2 weeks was 1.75 kg (median, 1.33 kg). CONCLUSIONS: Thalidomide treatment appeared to reverse the loss of weight and lean body mass over the 2-week trial period.

Aged↗
PubMed2003

Alternating layer and island growth of Pb on Si by spontaneous quantum phase separation.

Real-time in situ x-ray studies of continuous Pb deposition on Si(111)-(7x7) at 180 K reveal an unusual growth behavior. A wetting layer forms first to cover the entire surface. Then islands of a fairly uniform height of about five monolayers form on top of the wetting layer and grow to fill the surface. The growth then switches to a layer-by-layer mode upon further deposition. This behavior of alternating layer and island growth can be attributed to spontaneous quantum phase separation based on a first-principles calculation of the system energy.

Journal Article↗
PubMed2002

Percutaneous endoscopic gastrostomy (PEG): change in practice since 1988.

BACKGROUND AND AIMS: We previously reported a 30-day mortality following percutaneous endoscopic gastrostomy (PEG) of 8% (1988-92). Concerns over increasing mortality rates prompted us to survey current practice compared with 1988-92: assess case mix, outcome, risk factors for early death, and review practice guidelines. METHODS: 78 consecutive adults were referred for PEG over 7 months. Baseline characteristics, including age and functional status (Barthel Index), and outcome at 30 and 180 days were prospectively evaluated. RESULTS: 74 patients. Median age 69 years; male 55%. Major underlying diagnoses: cerebrovascular disease 42%, head and neck tumours 19%, motor neurone disease 4% (33%, 16% and 27% in 1988-92). Mortality rates at 30, 90 and 180 days were 19%, 35% and 42% respectively (8%, 20% and 37% in 1988-92). Univariate analysis showed that age >75 years, Barthel Index <1 and Glasgow Coma Scale < or =10 were significant risk factors for death at 30 days: odds ratios (95% confidence intervals) 3.9 (1.1-13), 5.9 (1.4-25) and 4.4 (1.2-15) respectively. CONCLUSIONS: 30-day mortality was increased from 8% to 19% between 1988-92 and 1998-99 reflecting a change in referral patterns: more elderly with cerebrovascular disease and fewer with motor neurone disease. Age and functional status should be considered when advising on PEG feeding.

Adult↗
PubMed2002

Improvements in total mortality and lipid levels after acute myocardial infarction in an English health district (1995-1999).

OBJECTIVES: To quantify changes in 30 day and one year mortality among patients with acute myocardial infarction in southern Derbyshire (population 560 000) in each of five consecutive years (1995-1999) before the publication of the National Service Framework for coronary heart disease, and to assess the proportion of one year survivors in whom serum lipids were measured and were below target values. DESIGN: All hospital admissions coded on the patient administration system (PAS) as "AMI" (ICD codes I-21, I-22, and I-23) and with a creatine kinase measurement in the pathology database were identified over a five year period (n = 4912). All deaths in the district are automatically notified to the PAS. Total mortality after acute myocardial infarction (30 days and one year) and lipid levels were analysed by year of admission, age group (35-74 years v > or = 75 years), and sex using unconditional logistic regression analysis. SETTING: An acute hospitals trust and pathology laboratory, as sole service providers for a catchment population of 560 000. RESULTS: The number of admissions for acute myocardial infarction was similar in each of the five years (n = 4912, 62% male, 63% < 75 years old). Overall, among patients aged 35-74 years there were 396 deaths (13%) at 30 days and 585 (19%) at one year; mortality was higher in women (1.28-fold at 30 days, p = 0.02) and in subjects aged 75 years or more (3.26-fold at 30 days, p < 0.0001). There was a progressive reduction in 30 day mortality of 9%/year over the five year period (95% confidence interval, 4% to 13%, p = 0.012). The proportion of one year survivors (35-74 years) in whom serum lipids were measured at least once increased from 74% in 1995 to 88% in 1999; of these, 27% of men and 23% of women had a total serum cholesterol of < 5 mmol/l in 1995, increasing to 65% and 74%, respectively, in 1998 and 1999 (p < 0.0001). CONCLUSIONS: In the five year period 1995-1999, there was a significant year on year decline in 30 day and one year mortality after admission for acute myocardial infarction, and progressively more patients achieved cholesterol levels below 5 mmol/l. Men were more likely than women to have their lipids measured after myocardial infarction. Mortality at one year was 1.32-fold higher among women than among men.

Adult↗
PubMed2002

Influence of yeast culture on ruminal microbial metabolism in continuous culture.

A continuous culture study was conducted to evaluate the effect of two different yeast cultures on ruminal microbial metabolism. The treatments were a) control lactation ration, b) yeast culture 1 (YC1, Diamond-V XP) and c) yeast culture 2 (YC2, A-Max), both fed at an equivalent of 57 g/head per day. The results showed that both yeast culture products increased dry matter (DM) digestion, propionic acid production, and protein digestion compared with the control. Yeast culture 1 demonstrated an increase in molar percentage of propionic acid, a reduction in acetic acid, and a lower mean nadir (daily low) pH compared with YC2. Ruminal cultures treated with YC digested more protein and contributed less bypass N than control. Supplementing YC2 resulted in a tendency for higher microbial N/kg DM digestion than YC1. Yeast culture 1 resulted in production of rumen microbes containing less protein and more ash than YC2. These results support previous research findings that yeast culture does influence microbial metabolism, and specific yeast cultures may have different modes of action.

Acetic Acid↗
PubMed2001

Modifications to the hand-held Gene Gun: improvements for in vitro biolistic transfection of organotypic neuronal tissue.

Transfection and subsequent expression of DNA in living neuronal tissue is problematic and no technique has emerged that is completely non-damaging, efficient and reproducible. The Bio-Rad hand-held Gene Gun has overcome some of these problems by exploiting a biolistic method in which small gold particles carrying plasmid DNA are propelled into neurons whilst causing minimal detectable cell damage. In its current configuration, however, the Bio-Rad Gene Gun is optimised for transfecting cells in dispersed cultures, and therefore delivers particles superficially over a relatively wide area. Here we report modifications to the Bio-Rad Gene Gun that both enhance its accuracy by restricting its target area, and increase the depth penetration achieved by gold particles, thereby allowing smaller and deeper tissues to be transfected. These alterations make the modified Gene Gun more applicable for in vitro transfection of organotypic cultures and enhance its potential utility for in vivo gene delivery. Moreover, the modified configuration operates successfully at lower gas pressures, thereby reducing even further the degree of cell damage incurred during transfection.

Air Pressure↗
PubMed2001

X-ray studies of phonon softening in tise2.

The charge-density-wave transition in TiSe (2), which results in a commensurate (2x2x2) superlattice at temperatures below approximately 200 K, presumably involves softening of a zone-boundary phonon mode. For the first time, this phonon-softening behavior has been examined over a wide temperature range by synchrotron x-ray thermal diffuse scattering.

Journal Article↗
PubMed2001

Can saltwater toxicity be predicted from freshwater data?

The regulation of substances discharged to estuarine and coastal environments relies upon data derived from ecotoxicity tests. Most such data are generated for freshwater rather than saltwater species. If freshwater toxicity data are related to saltwater toxic effects in a systematic and predictable way, the former can be used to predict the latter. This would have economic advantages due to a reduction in toxicity testing of saltwater species. If toxicity data are plotted as species sensitivity distributions, four theoretical relationships between freshwater and saltwater can be envisaged. Examples show that each one of these relationships is supported by empirical data. These examples show that although there is considerable potential for freshwater to saltwater prediction, species parity and representativeness need to be examined for each chemical substance to avoid bias.

Animals↗
PubMed2001

GREAT-ER: a new tool for management and risk assessment of chemicals in river basins. Contribution to GREAT-ER #10.

The GREAT-ER (Geo-referenced Regional Exposure Assessment Tool for European Rivers) project team has developed and validated an accurate aquatic chemical exposure prediction tool for use within environmental risk assessment schemes. The software system GREAT-ER 1.0 calculates the distribution of predicted environmental concentrations (PECs) of consumer chemicals in surface waters, for individual river stretches as well as for entire catchments. The system uses an ARC/INFO-ArcView (ESRI) based Geographical Information System (GIS) for data storage and visualization, combined with simple mathematical models for prediction of chemical fate. At present, the system contains information for four catchments in Yorkshire, one catchment in Italy, and two in Germany, while other river basins are being added. Great-ER 1.0 has been validated by comparing simulations with the results of an extensive monitoring campaign for two 'down-the-drain' chemicals, i.e. the detergent ingredients boron and Linear Alkylbenzene Sulphonate (LAS). GREAT-ER 1.0 is currently being expanded with models for the terrestrial (diffuse input), air and estaurine compartments.

Environmental Monitoring↗
PubMed2000

Removal of linear alkylbenzene sulfonate from a small Yorkshire stream: contribution to GREAT-ER project #7.

An in-stream removal experiment has been carried out in Red Beck, a small stream which receives effluent from Shibden Head Sewage Treatment Works. This trickling filter works serves a purely domestic population of 9408 but is scheduled to be closed, and the flows diverted to another works, as part of Yorkshire Water's continuing capital investment programme. An anionic detergent, linear alkylbenzene sulfonate (LAS), boron, and standard water quality parameters have been measured at seven sites downstream of the effluent discharge point. Time of travel has been measured by detection of a fluorescent dye added to the effluent sampling chamber, and the increase in flow as the river proceeds through the catchment has been determined from current flow measurements, and from boron dilution data. Assuming a first order removal mechanism, the overall half-life for LAS removal is just over 2 h (2 h 14 min). Faster removal takes place in the upper portion of the stream, and removal over the last five sampling points is somewhat slower, with a half-life of 2 h 40 min. This removal may comprise both primary biodegradation and the deposition of suspended matter to which the surfactant has been adsorbed. There was no significant difference in the removal half-lives of the individual alkyl chain length homologues.

Alkanesulfonic Acids↗