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Biomedical subjects

T J Peters

Publications and source records attributed to T J Peters.

At least 217 records · Page 12Linked to original sources
PubMed1995

Factors associated with preterm birth in Cardiff, Wales. I. Univariable and multivariable analysis.

OBJECTIVE: Our purpose was to examine the associations of demographic, social, and medical factors with risk of preterm birth. STUDY DESIGN: By use of the Cardiff Births Survey, a large database of largely homogeneous (white) births in Wales, multivariable analysis by logistic regression examined the relative importance of risk variables associated with preterm birth. RESULTS: Significant independent associations with preterm birth were found (in decreasing order of magnitude) for late pregnancy bleeding, preeclampsia-proteinuria, low maternal weight, low maternal age, early pregnancy bleeding, history of previous stillbirth, smoking, high parity, low or high hemoglobin concentration, history of previous abortion, low social class, bacteriuria, and nulliparity. CONCLUSION: In this population demographic, social, and medical characteristics of the pregnancies showed significant associations with preterm birth.

Abortion, Induced↗
PubMed1995

Factors associated with preterm birth in Cardiff, Wales. II. Indicated and spontaneous preterm birth.

OBJECTIVE: Our purpose was to examine and contrast associations of risk factors with spontaneous preterm birth and indicated preterm birth. STUDY DESIGN: Separate multiple logistic regression analyses were performed of indicated and spontaneous preterm births in a large database of births in Cardiff, Wales. RESULTS: Spontaneous preterm births were associated with young maternal age, low maternal weight, low or high parity, previous abortion, smoking, and early pregnancy bleeding. Indicated preterm births were associated with older age, low weight, previous stillbirth, bacteriuria, and early pregnancy bleeding. CONCLUSION: Spontaneous and indicated preterm births have different overall profiles of association with pregnancy risk factors.

Abortion, Induced↗
PubMed1995

In vitro duodenal iron uptake and serum and mucosal iron protein levels, with special reference to rheumatoid arthritis.

Duodenal biopsies from control subjects, patients with iron-deficiency anaemia and rheumatoid arthritic patients with anaemia of chronic disorders (ACD) were investigated for their ability to take up 59Fe from iron ascorbate. Additionally, duodenal tissues were analysed for iron and immunoreactive ferritin and transferrin. Biopsies from iron-deficient subjects showed a 2- to 3-fold increase in the apparent Vmax for 59Fe uptake, compared to control values. Uptake was inversely related to body iron stores. ACD patients showed similar rates of 59Fe uptake to controls; the rates were independent of the degree of anaemia or serum ferritin levels. Tissue analysis showed reductions in mucosal iron and ferritin levels in iron-deficient patients, whilst transferrin levels were within the normal range. ACD patients also exhibited lower mucosal iron levels, but had iron protein levels within the normal range. It is suggested that factors distant from the intestinal mucosa influence iron absorption in ACD.

Adult↗
PubMed1995

Duodenal expression of NF-E2 in mouse models of altered iron metabolism.

This study investigated the relationship between duodenal mucosal mRNA levels of the transcription factor, NF-E2, H-ferritin (a putative NF-E2 regulated gene) and iron absorption in mice. CD1-strain mice with normal and altered iron metabolism (hypoxic, iron-deficient, iron-loaded) and animals with genetic defects of iron metabolism (hypotransferrinaemia, beta-thalassaemia) were studied. Tissue RNA from these mouse models was subjected to reverse transcription and PCR amplification for NF-E2 and a stable ribosomal protein (S14) and the products analysed with an automated laser fluorescent sequencer. Duodenal NF-E2 mRNA levels were generally low and decreased in the hypoxic and iron-deficient groups, both of which exhibited elevated iron absorption as compared to controls. A modest increase in the NF-E2 mRNA level was seen in the iron-loaded mice, whose iron absorption was decreased. In contrast, both the genetic strains showed elevated NF-E2 mRNA levels in conjunction with raised iron absorption values. Only the iron-deficient group exhibited an alteration in the duodenal mucosal H/L ferritin ratio. Hence, no relationship was evident between the NF-E2 mRNA levels and the H/L ferritin ratio. These data indicate that NF-E2 is not the primary regulator of intestinal iron absorption.

Animals↗
PubMed1995

Assessment of intestinal blood-flux by laser Doppler fluxmetry in mice with altered intestinal iron absorption.

Laser Doppler fluxmetry (LDF) has been used to assess mucosal blood-flux in the intestine of normal CD1 mice and groups of animals with altered iron metabolism (i.e. iron-deficient, hypoxic and hypotransferrinaemic [hpx/hpx]). All experimental animals showed a 2-3-fold increase in duodenal iron absorption, mainly due to changes in the 'mucosal transfer' phase. However, only the hypoxic mice exhibited any increases in duodenal blood-flux. In the hpx/hpx group, blood flux was maintained at control levels despite the anaemia and without any significant alterations in red blood cell velocity. Moreover, these two groups demonstrated a further capacity to increase blood-flux above basal levels during onset of acute hypoxia (inhalation of 10% O2). Changes in duodenal blood-flux were apparent on both the mucosal and serosal surfaces, suggesting that the LDF signal reflects flux throughout the thickness of the mouse intestine. Iron absorption is likely to be more related to plasma flux changes than to blood-flux changes. Deduction of plasma flux changes from blood-flux changes is complicated by vasodilation effects on capillary haematocrits. It is clear from the data, however, that plasma flux changes do not parallel changes in iron absorption in the experimental models. The lack of correlation between the duodenal blood-flux and iron absorption values in the experimental models argues against the possible involvement of blood-flux in the control of duodenal iron absorption.

Anemia, Iron-Deficiency↗
PubMed1995

Plasma clearance of transferrin in control and hypotransferrinaemic mice: implications for regulation of transferrin turnover.

Kinetic studies were performed to determine the clearance of iodinated transferrin in hypotransferrinaemic mice, as compared to normal animals. Clearance of i.v. (and i.p.) administered radiolabelled protein in homozygous (hpx/hpx) mice was significantly faster than in heterozygous (hpx/+) and wild-type control (+/+) groups. A comparable t1/2 value for transferrin clearance in hpx/hpx mice was derived from a study in which immunoassay was performed on serum samples obtained at various times post-injection with normal mouse serum, indicating that the clearance of 125I reflected true clearance of transferrin protein. The clearance rate in the hpx/+ group was significantly slower than in +/+ mice. Calculation of transferrin synthesis rates in these two groups suggested that transferrin levels do not regulate transferrin synthesis rates, but may affect degradation; this observation is consistent with the fact that transferrin levels in hpx/+ mice are > 50% of the values in +/+ mice, and indicates a partial compensation for reduced synthesis. The rapid clearance in hpx/hpx mice is an additional factor in determining the low levels of circulating transferrin in these synthesis-impaired mutants.

Anemia, Hypochromic↗
PubMed1995

Achieving equal probability of selection under various random sampling strategies.

The underlying objective of epidemiological investigations is to extrapolate results from a sample to the relevant population. The simplest way of achieving this is to adopt a sampling strategy in which each individual in the population has the same chance of being selected--that is, to employ an 'equal probability of selection method' (epsem). The easiest ways of achieving this are to use simple random sampling or stratified random sampling with a constant sampling fraction. These strategies are often impracticable, however, particularly in large investigations covering a wide geographical area where resource implications dictate a more complex approach such as multi-stage or cluster sampling. Following detailed definitions and appropriate illustrations of these terms, the main purpose of this paper is to provide a working guide of how to achieve epsem using these various random sampling techniques. In brief, for multi-stage sampling with the rare feature of equal-sized first stage units, epsem is achieved by applying the above simple or stratified approaches to the first stage units. Even in the more realistic scenario of unequal first stage units, the same options apply provided that a fixed proportion of second stage units are to be selected (cluster sampling is in fact just one example of this, with 100% sampling of second stage units). If on the other hand a fixed number of second stage units are to be selected then for epsem the first stage units should be selected with each one having a probability proportionate to its size.

Data Collection↗
PubMed1995

Prostate-specific antigen and prognosis in patients with metastatic prostate cancer--a multivariable analysis of prostate cancer mortality.

OBJECTIVE: To analyse the prognostic significance of pre- and post-treatment serum prostate-specific antigen (PSA) levels, together with a variety of other factors, in a multivariable analysis of survival in men with stage D2 prostate cancer. PATIENTS AND METHODS: Cox's proportional hazards model was used to compare survival in 134 men with stage D2 metastatic prostate cancer followed prospectively over a 4 year period, using both univariable and multivariable models. The influence of the following factors on survival was analysed: pre- and post-treatment PSA (both absolute and percentage values), age, treatment, testosterone, pre- and post-treatment alkaline phosphatase (absolute and percentage values), acid phosphatase, haemoglobin, symptom score and performance status and extent of disease on bone scan. RESULTS: Pre-treatment PSA levels did not significantly influence survival. Similarly, a low absolute post-treatment PSA level at 3 months after the start of treatment conferred no survival advantage relative to patients with a high PSA level at this time. A post-treatment percentage PSA of < 10% at 2, 3 and 6 months after commencement of treatment was associated with prolonged survival. Low pre-treatment alkaline phosphatase (less than the upper limit of normal) and high pre-treatment testosterone levels (> or = 10 nmol/L) were similarly associated with prolonged survival. CONCLUSIONS: The strong influence of post-treatment percentage PSA on survival in patients with stage D2 prostate cancer suggests that the percentage change in bulk of metastatic deposits is more important in determining survival than the absolute volume of tumour. Pre-treatment alkaline phosphatase seems to be a better indicator of tumour activity than pre-treatment PSA. These findings have important implications for the design and analysis of clinical trials of new therapies in men with stage D2 prostate cancer and for the future selection of alternative treatments for patients with this stage of the disease.

Aged↗
PubMed1995

The significance of abdominal straining in men with lower urinary tract symptoms.

OBJECTIVE: To determine the relationship between the symptom of straining to void, the presence of objectively demonstrated abdominal straining and bladder outflow obstruction in men with lower urinary tract symptoms (LUTS), and to assess the effect of straining on flow rate in these men. PATIENTS AND METHODS: The presence of straining to void as a symptom was determined from a symptom questionnaire in 61 men presenting with LUTS. Objective evidence of straining to void was assessed by rectal pressure measurement and the presence of bladder outflow obstruction was determined by pressure-flow studies. The effect of straining on flow rate was assessed in a separate group of 58 men with LUTS, by comparing the maximum flow rate on non-strain and strain voids of similar volume. RESULTS: There was poor agreement between the complaint of straining and the presence of straining as measured by rectal pressure recording. Twelve of the 53 patients who claimed they never or occasionally strained to void in fact showed straining on each of four voids. There was no significant difference in the proportion of men who complained of straining in the obstructed and non-obstructed groups (P = 0.86). The probability of obstruction in those men with objective evidence of straining on all voids was 80% and in those who did not strain on all voids was 51%, but this difference was not statistically significant (P = 0.53). There was no clinically significant effect of straining on maximum flow rate in men with LUTS. CONCLUSION: As a symptom, straining is an uncommon complaint in men with benign prostatic hyperplasia (BPH), and the relationship between the symptom and objective evidence of its presence is poor. Both as a symptom and as an objectively measured voiding disorder, straining lacks sufficient sensitivity and specificity for it to be of value in the diagnosis of bladder outlet obstruction (BOO). Abdominal straining does not have a marked effect on flow rate in men with BPH. This study suggests that straining is an unreliable symptom of BOO, that it does not influence voiding function in elderly men and that its inclusion in symptom scores for BPH should be reconsidered.

Aged↗
PubMed1995

Social class and preventive health behaviour: a British example.

STUDY OBJECTIVE: To test the relationship between social class and preventive health behaviour in a British national sample and identify which set of more specific socioeconomic factors best "explained" any observed relationship(s). DESIGN: Secondary analysis from a national cross sectional survey of the health attitudes and health behaviour of men and women aged 18 years and over living in private households in England, Scotland, and Wales. A selection of addresses was made randomly from the electoral register using a three stage design, and then one individual in each household was sampled. A total of 12,254 addresses yielded interviews with 9003 individuals, a response rate of 73.5%. Compared with the census population, the single and divorced/separated are slightly under-represented but otherwise sources of bias are small. PARTICIPANTS: The subset selected was 1671 women and 1026 men aged between 20-45 years with at least one child under 17 living at home. MAIN RESULTS: Social class was strongly associated with the health practices index (HPI, used as a measure of health behaviour) both for women and men (p < 0.001). The set of factors identified for both sexes as having an impact on this relationship were education, tenure, residential overcrowding index, and salience of lifestyle. In addition, their partner's employment status and household income were relevant for women only. These groups of factors did not totally explain the observed relationship but the proportion of variance in HPI attributable to social class was considerably reduced. CONCLUSIONS: Descriptions of the association between social class and health behaviour(s) are of little use to those wishing to mount more effective interventions in health promotion. Multivariable analysis can indicate which specific factors account for much of the social class effect on health behaviour and thereby assist better understanding and targeting of resources.

Adult↗
PubMed1995

An improved method for the quantitation of apolipoprotein B and apolipoprotein A-1 in dried blood spots.

An extraction protocol has been developed to elute apolipoprotein B (apo B) and apolipoprotein A-1 (apo A-1) from dried blood spots with assay of the extracted apolipoproteins by automated immunoturbidimetry. Various extraction media were investigated to assess their elution efficiency and the optimum medium was found to be deionized water. Studies on the rate of elution suggested both apolipoproteins were eluted readily in less than an hour with a recovery of 71% for apo B and 65% for apo A-1. Extracted apo B but not aop A-1 was found to be stable for 24 h when kept at 4 degrees C. The within-batch coefficients of variation (CV) for the combined extraction and assay of apo B were found to be 5.9% and 8.5% at 0.6 g/L and 1.2 g/L respectively. The CVs for apo A-1 were found to be 7.4% at 0.7 g/L and 8.9% at 1.5 g/L. Antiserum from three sources (Immuno, Incstar and Bayer) was investigated for immunoreactivity with apo B and apo A-1 and cross-reactivity with red blood cells was also assessed. Although the antisera from the three companies showed similar immunoreactivity towards apo B and apo A-1, antiserum from Bayer was found to cross-react with red cells.

Adult↗
PubMed1995

Perioperative low-molecular-weight heparin. Is it effective and safe.

In previous randomised clinical trials of thromboprophylaxis after total hip replacement, low-molecular-weight heparin has been given for an arbitrary 7 to 14 days. The risk factors are mainly perioperative and it is possible that a shorter course may be adequate. We assessed the safety and effectiveness of a three-day course. We assessed 156 primary THR patients after randomisation to either a control group or to receive enoxaparin at 12 hours preoperatively and 12 and 36 hours postoperatively. Thrombosis was diagnosed by routine venography. Haemorrhagic side-effects were assessed by measurement of blood loss, and soft-tissue side-effects by descriptive scores for wound discharge and bruising of the leg. The prevalence of calf thrombosis was 15.4% in the enoxaparin group and 32.1% in the control group (p = 0.01); the prevalence of proximal thrombosis was 15.4% and 17.9% respectively (not significant). There was no difference in haemorrhagic side-effects or wound discharge, but there was more bruising in the enoxaparin group.

Anticoagulants↗
PubMed1995

Appropriateness of hospital utilization. The validity and reliability of the Intensity-Severity-Discharge Review System in a United Kingdom acute hospital setting.

Assessing the appropriateness of hospital utilization in the United Kingdom may yield practical solutions to problems faced by both purchasers and providers of health care in the National Health Service. It is, however, essential that such assessment is based on a method that is both valid and reliable--in particular, valid in the context in which it is applied. Whereas American methods for the assessment of appropriateness have been shown to be valid in the United States, it is pertinent to question whether the application of such methods to the National Health Service also is valid given the different circumstances, both cultural and financial, under which health care is provided. A study of the appropriateness of admission and hospital stay for a sample of admissions to a large acute hospital in the United Kingdom was carried out, and the assessment of appropriateness was made using the Intensity-Severity-Discharge Review System with Adult criteria (ISD-A). The validity and reliability of using the ISD-A for assessing hospital utilization in the United Kingdom was evaluated. The ISD-A was found to have high reliability and to be valid for assessing appropriateness in the United Kingdom when a full range of alternative forms of care are presumed to be available. It was not found to be valid currently, therefore, for routine assessment of hospital utilization within the National Health Service, when alternatives often are not available.

Emergencies↗