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Biomedical subjects

A Lucas

Publications and source records attributed to A Lucas.

At least 235 records · Page 13Linked to original sources
PubMed1990

The prediction of total body fatness in early infancy.

We have investigated the relationship between percentage fat mass and skinfold thicknesses in a group of male and female infants at 5, 11 and 26 weeks of age. Fat-free mass and hence fat mass was determined using an H2(18)O dilution technique. Multiple regression analysis was used in order to evaluate whether the triceps and subscapular skinfold measurements, in a number of models, could predict percentage body fat. In all cases skinfold thickness was poorly predictive of percentage body fat. We suggest that variation in the distribution of internal and external stores of body fat may be a major factor accounting for the poor predictive value of skinfold thickness in this study.

Adipose Tissue↗
PubMed1990

Atherosclerotic Yucatan microswine: an animal model with high-grade, fibrocalcific, nonfatty lesions suitable for testing catheter-based interventions.

A new breed of swine, the Yucatan microswine, that was derived from repetitive inbreeding of selected, small Yucatan swine, was investigated as an animal model of advanced vascular atherosclerosis. Nineteen animals were fed an atherogenic diet for 9.9 +/- 1.5 (mean +/- SEM) weeks before and 19.9 +/- 1.8 weeks after balloon endothelial denudation of all four iliac arteries. In 18 (94.7%) of the 19 microswine, angiography performed at 33 to 87 weeks of age disclosed some degree of luminal diameter narrowing: six animals (33.3%) had one-vessel, six (33.3%) had two-vessel, four (22.2%) had three-vessel, and two (11.1%) had four-vessel disease. In 38 (50%) of 76 denuded arteries, angiographically apparent luminal diameter narrowing was observed as follows: three arteries (7.9%) were narrowed less than 50%; 10 arteries (26.3%) were narrowed 50% to 75%; seven arteries (18.4%) were narrowed 76% to 99%; and 18 arteries (47.3%) were occluded. Sixty-four arteries were harvested from 16 of the 18 microswine with angiographically apparent luminal narrowing, which yielded 748 histologic sections. Maximum cross-sectional area narrowing from atherosclerotic plaque exceeded 90% in 135 (18%) of the sections examined, while 65 sections (9%) were narrowed 76% to 90%, and 127 sections (17%) were narrowed 51% to 75%. Atherosclerotic plaque in these animals appeared histologically similar to the so-called "complex" lesion that is typical of human atherosclerosis, which consists predominantly of collagen with focal calcific deposits and a minor lipid component. The smaller size and lower weight of these animals, in comparison with full-size farm pigs and "minipigs," facilitated transportation, handling, and instrumentation. These findings establish the Yucatan microswine as a useful, representative, and economical atherosclerotic animal model for the evaluation of novel interventional techniques.

Angiography↗
PubMed1990

The interleukin-2 receptor on cord blood and nulliparous mononuclear cells is downregulated by maternal and cord blood serum.

The concentration of interleukin-2 receptor (IL-2R) on maternal, cord blood and unrelated nulliparous mononuclear cells has been studied after a previous phytohaemagglutinin (PHA) stimulation. Furthermore, the inhibitive action of maternal and cord blood serum on the IL-2R expression of stimulated nulliparous and cord blood lymphocytes has been shown. A downregulation of the [3H]-thymidine uptake by these PHA treated cells previously incubated in maternal and cord blood serum has been observed. Retroplacental serum was the most inhibitive experimental medium. The IL-2R modulation property of maternal serum has been studied during the pregnancy. Appearing quite early (in the sixth week), the maternal serum dependent inhibitive factor vanished, 2 to 3 weeks after delivery. After a study of the different serum components, it is suggested that the IL-2R downregulating molecule is included in the maternal immunoglobulin (IgG) fraction. Further experiments suggest that the addition of recombinant IL-2 during the action of low doses of maternal IgG allows a partial re-expression of the IL-2R. However, at physiological concentrations of IgG, the IL-2R downregulation becomes irreversible.

Antibodies, Monoclonal↗
PubMed1990

Localized scleroderma--response to 1,25-dihydroxyvitamin D3.

1,25-Dihydroxyvitamin D3 [1,25(OH)2 D3] may be an immunomodulatory drug which could have a role in controlling collagen deposition, and inducing reversal of fibrosis in some tissues. These observations prompted a study of the possible use of this hormone for the treatment of scleroderma. A 35-year-old woman, who had been suffering from localized scleroderma for 2 years, was given oral 1,25(OH)2 D3 for 6 months. The effects of the treatment were evaluated using clinical and physical measurements (skin thickness, extensibility properties of the skin). The evolution of the patient's condition during the 6-month therapy suggests that 1,25(OH)2 D3 is beneficial in localized scleroderma. The mechanisms of action are discussed in relation to the literature, which suggests both immunoregulatory and inhibitory effects on fibroblast growth.

Adult↗
PubMed1990

Does early diet program future outcome?

Despite intensive research in infant nutrition throughout this century, uncertainty persists over nearly every major aspect of practice. Reasons for this uncertainty are analysed and the need for prospective studies on the later effects of early diet is justified. Evidence is presented that nutrition at a critical or sensitive period in early life predetermines future metabolism, performance and morbidity in animal models. Similar data in Man have been collected mainly in retrospective and flawed studies and are correspondingly less convincing. A prospective multicentre randomized study on preterm infant feeding is discussed to illustrate the feasibility of conducting long-term outcome studies in Man and to emphasize the critical importance of outcome data as a basis for clinical practice. Preliminary evidence from this study suggests that the way a preterm infant is fed, in just the early weeks post partum, may have a major impact on later growth and development.

Animals↗
PubMed1990

Assay-dependent results of immunoassayable spontaneous 24-hour growth hormone secretion in short children.

Forty-eight children, referred for evaluation of short stature, underwent 24-hour spontaneous growth hormone (GH) secretion studies. The GH level in pooled sera was assessed for each child, using up to 11 commercial immunoassays. In a group of 15 children, the mean GH values obtained by nine of the assays were compared with the mean value given by a polyclonal radioimmunoassay (RIA) from Sorin: four gave higher results (p less than 0.0001), three gave comparable results and two gave lower results (p less than 0.001). The assay yielding the highest results (Nichols: 5.9 +/- 2.3 ng/ml, mean +/- SD) gave values that were approximately triple those obtained by the assay yielding the lowest results (Hybritech: 1.8 +/- 0.8 ng/ml; p less than 0.0001); both of these are monoclonal immunoradiometric assays (IRMAs). The GH concentrations measured in 24-hour pools from 32 children using a monoclonal IRMA from Biomérieux were similar to those obtained using a polyclonal RIA from Farmos (2.8 +/- 1.1 ng/ml and 2.9 +/- 1.4 ng/ml, respectively) but significantly lower than those measured by another polyclonal RIA from Sorin (3.5 +/- 1.5 ng/ml). Two polyclonal assays (Biomérieux and Sorin) were then used to measure the GH levels in all of the 30-minute samples and in the day, night and 24-hour pools from the secretion studies of 22 children. The ratio of the results of the two assays remained fairly constant for a given child (although the GH levels in different 30-minute samples differed considerably). However, the ratios between different children showed quite wide variation (from 2.03 to 1.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Birthweight ratio and outcome in preterm infants.

The association between birthweight ratio and outcome was investigated in 429 infants born before 31 weeks' gestation. Birthweight ratio was calculated in each case as birth weight divided by mean birth weight for gestation (from reference data). It was shown that a given ratio corresponded to the same birth centile across the gestational age range studied; a ratio of 0.8 corresponding to the 10th centile. There was a linear relationship between birthweight ratio and requirement for mechanical ventilation and postneonatal mortality. Birthweight ratio was also strongly and linearly related to body weight, length, and head circumference at 18 months' corrected age. Overall, there was no association between this ratio and neurodevelopmental outcome to 18 months. However, the subgroup with the largest weights for gestation (birthweight ratio greater than or equal to 1.1), had significantly higher language subscores than all the other children. Our data show that conventional dichotomous categorisation of preterm infants into small or appropriate for gestation is inadequate when exploring the association between size for gestation and outcome.

Birth Weight↗
PubMed1990

Food and drug reactions, wheezing, and eczema in preterm infants.

Allergic reactions were investigated in 777 preterm infants who were randomly assigned to early diet and followed up to 18 months post term. Wheezing or asthma was common (incidence 23%); it was associated with neonatal ventilation, maternal smoking, and a family history of atopy and was unexpectedly reduced in babies born by caesarean section. Even in non-ventilated infants, the incidence of subsequent wheezing was 18%, rising to an estimated 44% (using logistic regression) when the foregoing risk factors (excluding ventilation) were present. Eczema occurred in 151 infants (19%) and was strongly associated with multiple pregnancy (30% incidence in twins or triplets). Reactions to cows' milk (incidence: 4.4% from detailed history; 0.8% confirmed by challenge), other foods (10%), and drugs (5%) were within the range reported in full term infants. Milk and food reactions were associated with multiple pregnancy (19%) and a family history of atopy. Reactions to drugs were least likely to occur in infants who had been ventilated and were on multiple medications in the neonatal period, suggesting that drug tolerance may have developed. We speculate that preterm infants may be a high risk group for asthma and eczema, which could imply an association between atopy and prematurity.

Drug Hypersensitivity↗
PubMed1990

Linear growth in the early neonatal period.

To test the hypothesis that early linear growth is independent of changes in weight we undertook took simple anthropometry in 45 term infants daily to day 7 after birth. Linear growth proceeded rapidly and independently of changes in weight variations from the first day after birth; we suggest that this implies 'programmed' continuity of skeletal growth, possibly fuelled at the expense of other body tissues.

Age Factors↗
PubMed1990

Plasma prolactin and clinical outcome in preterm infants.

Plasma prolactin was measured weekly in 280 preterm infants. The complex gestational age dependent pattern of postnatal prolactin release has been defined and reference standards provided. Plasma prolactin was higher in girls, with increasing divergence between the sexes from the third week onwards, and higher after two weeks, in infants of mothers with pregnancy related hypertension. Diet, assigned randomly, exerted a major effect on plasma prolactin, with significantly higher values in infants fed donor breast milk or standard formula than in those fed a protein, energy, and mineral enriched preterm formula. After adjusting for confounding factors, infants with the lowest plasma prolactin concentrations (less than 1000 mU/l, 32.9 micrograms/l) occurring usually at a nadir between days 5 and 12, showed a 120% increase in the duration of ventilatory assistance required, a 20% increase in the number of days to attain full enteral feeds, and a 30% decrease in length gain. We suggest preterm birth disrupts the normal perinatal pattern of prolactin release and that those infants who develop relatively low plasma concentration have an adverse outcome. Our data add to the broader debate on whether preterm infants require multiple endocrine replacement treatment.

Age Factors↗
PubMed1990

Effect of chronic clonidine treatment on urinary growth hormone excretion and linear growth in children with short stature.

Eleven prepubertal children with short stature were treated with clonidine (0.15 mg/m2 daily) for a period of 1 year. The effect of this drug was evaluated on both clinical (growth velocity, height standard deviation scores for chronological age and bone age) and hormonal (urinary growth hormone excretion and insulin-like growth factor I) parameters. Our study shows that long-term clonidine administration in children with short stature did not result in significant differences in growth velocity, height standard deviation scores for chronological age and bone age, insulin-like growth factor I or in urinary growth hormone excretion.

Body Height↗
PubMed1990

Modulation of the interleukin 2 receptor by maternal and cord blood serum.

In this report, the potential inhibitive action, of maternal serum (retroplacental and peripheral), and cord blood serum on the expression of the Il2r has been studied. Calf and male serum were used as a control. In order to have an optimal Il2r expression, a previous PHA cellular stimulation was performed. The maternal serum's Il2r inhibitive property was measured during and after the pregnant period. The presence of Il2r on maternal lymphocytes, cord blood cells, and unrelated donor mononuclear cells has been investigated (after a PHA stimulation assay). The downregulated Il2r expression of neoplastic cell line (Hut78 cell line) under the influence of maternal serum has been observed. The examination of the inhibitive action due to maternal serum has suggested that a factor included in the IgG fraction is mainly responsible for the downregulating property concerning the Il2r expression. A possible mechanism for the action of this factor has been studied. Further experiments suggest that the addition of recombinant Il2 during the action of low doses of maternal IgG allows a partial reexpression of the Il2 receptor. However, at physiological concentrations of IgG, the Interleukin 2 receptor downregulation becomes irreversible.

Blood Cells↗
PubMed1990

Modulation of the HLA class II antigen at a molecular level by maternal serum.

The recent immunological literature has described the existence of a retroplacental serum factor being responsible for the downregulation of the MHC Class II antigen expression. In this report, the same property has been found in peripheral maternal serum. The HLA Class II modulating activity is however diminished in the presence of peripheral maternal serum as compared to retroplacental serum suggesting that the IA like inhibiting factor is released at the fetomaternal interface. After a three-day incubation period of unrelated lymphocytes in a maternal serum pool, it was shown that the HLA Dr., the HLA Dp., and more significantly, the HLA Dq. molecules were modulated. When third party lymphocytes were stimulated by Candidine or unrelated mononuclear cells in the presence of retroplacental serum, only the cellular subpopulation belonging to the CD4+ subset showed an HLA Dq. downregulation. The molecular constituents of the MHC Class II antigen expression characterizing cells belonging to other subsets remained unchanged. When the same stimulation assay was performed in the presence of a control medium (nulliparous serum), no changes concerning the MHC Class II molecular constituents were observed. When unrelated mononuclear cells were PHA stimulated in the presence of maternal and nulliparous serums, the HLA Dq. expression of the CD8+ subset showed a significant downregulation in the maternal serum mediated stimulation assay as compared to the control stimulation test. The molecular expression of the HLA Class II antigen related to the other subpopulations (CD4+, CD3+) stimulated by a mitogenic lectin remained unchanged. It is suggested that these molecular MHC Class II modulations are due to a factor included in the maternal IgG reaction. Retroplacental IgG contains the highest concentration of this factor.

Down-Regulation↗
PubMed1990

Long term follow-up of the effect of captopril on severe proteinuria in hypertensive diabetic patients.

We have studied the long term effects of captopril therapy on proteinuria in ten patients with non-insulin-dependent diabetes mellitus with hypertension and nephropathy. There were 7 males and 3 females, with a mean age of 53.3 +/- 10.6 years. After a run-in period of two weeks, therapy with captopril was started. The following parameters were studied: serum glucose, sodium, potassium, cholesterol and triglycerides, glycosylated haemoglobin, renal function and 24 hour urine protein excretion before and at six month intervals for up to 24 months. Average BP fell significantly from 182.5 +/- 28/95 +/- 7.1 to 146 +/- 16.7/76 +/- 18.1 mmHg although no significant changes were seen in the biochemical parameters studied, except a reduction in 24 hour urine protein excretion from 3.86 +/- 2.85 to 0.88 +/- 1.08 g/24 h after 24 months of treatment (P less than 0.01). No correlation was observed between the reduction in proteinuria and any other parameters studied. Our results confirm the reduction of proteinuria in patients with type II diabetes mellitus and stable diabetic nephropathy treated with captopril. This effect was maintained for a period of 24 months.

Adult↗
PubMed1990

[The recurrence of a gynecological neoplasm as a solitary thyroid nodule].

We present a case of a patient who sought medical assistance because of a single thyroid nodule and had a history of cervix carcinoma and hysterectomy three years earlier not having had any signs of progression of that disease since. The aspiration puncture of the thyroid nodule revealed atypical squamous cells suggestive of metastasis of the gynecological neoplasia. The rareness of the clinical presentation of the thyroid metastasis as well as of the involvement of this gland in the dissemination of cervix neoplasia are discussed, noting on the possible role of radiotherapy on the variation of the progression patterns of the disease. Similarly, the usefulness of cytology obtained by aspirative puncture with a thin needle, in the diagnosis of thyroid nodule is highlighted.

Biopsy, Needle↗
PubMed1990

Clinical efficacy of emergency bypass surgery for failed coronary angioplasty.

The clinical and angiographic variables of 26 coronary artery disease patients at the University of Alberta Hospitals requiring emergency coronary artery bypass grafting (CABG) for failed percutaneous transluminal coronary angioplasty (PTCA) were reviewed. Emergency CABG was judged necessary in 2% of 1300 consecutive patients undergoing PTCA. The most frequent indication for an emergency operation was dissection and acute closure of eccentric bend point target lesions associated with clinically severe, unremitting chest pain and ST-T abnormalities suggestive of impending myocardial infarction. The mortality rate for the combined procedures of failed PTCA and CABG was low (3.8%). The incidence of periprocedural infarction was high (61%); it was, however, associated with a benign clinical course and electrocardiographic evidence of significant reversibility of acute phase damage. Thus, overall, emergency CABG appears to be a clinically efficacious treatment for patients with threatened or impending infarction as a consequence of failed PTCA.

Aged↗