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Biomedical subjects

A Lucas

Publications and source records attributed to A Lucas.

At least 217 records · Page 12Linked to original sources
PubMed1992

Clinical usefulness of urinary growth hormone measurements in normal and short children according to different expressions of urinary growth hormone data.

To assess the clinical usefulness of urinary growth hormone (UGH) measurements, a UGH determination technique, including dialysis, ultrafiltration, and measurement by polyclonal-coated tube RIA, was established. Sixty-three short children were studied: 56 idiopathic growth retarded (37 prepubertal and 19 pubertal) and seven prepubertal with classic GH (growth hormone) deficiency. Forty-two healthy children (32 prepubertal and 10 pubertal) served as controls. Two groups of adults were studied: eight with active acromegaly and 11 healthy controls. UGH was measured in 24-h urine samples from all patients and controls. Mean +/- SD UGH excretion expressed as ng/24 h was significantly lower in the GH-deficient group compared with prepubertal growth-retarded and control children (p less than 0.01). No differences were found between UGH excreted by controls and by the growth-retarded groups. Pubertal children excreted significantly higher amounts of GH when UGH was expressed as ng/24 h (p less than 0.02 and p less than 0.03, respectively), but this difference disappeared when UGH was expressed as ng/g creatinine. UGH was significantly higher in acromegalic patients compared with adult controls (p less than 0.001). Differences between day, night, and 24-h UGH were studied in 23 children. UGH in night urine was significantly lower whether expressed as the total amount or as ng/g creatinine. The effect of recombinant hGH administration on UGH was studied in 13 children after 6 and 12 mo of treatment. UGH increased significantly under recombinant hGH treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1992

Reevaluation of autoantibodies to islet cell membrane in IDDM. Failure to detect islet cell surface antibodies using human islet cells as substrate.

Since their demonstration in 1975, ICSAs have been proposed as serological markers and pathogenic elements in IDDM. ICSAs are detected in the sera of most newly diagnosed IDDM patients by indirect IFL that uses viable preparations of rat islet or insulinoma cells as substrate, but they also can be detected by using human insulinoma or fetal islet cells. We have tried to demonstrate ICSAs in the sera of 31 newly diagnosed diabetic patients, including 6 positive samples on human fetal islet cells, which used their natural target for the first time: normal human islet cells. In spite of using different types of preparations of these cells (i.e., freshly dispersed cell suspensions, monolayer cultures, or dispersed islets after culture), ICSAs could not be detected by IFL under the UV microscope, nor by flow cytometry. In contrast, 9 of 29 of the sera gave a positive staining on the RIN rat insulinoma cells. In an attempt to establish whether the putative ICSA autoantigen is present in the surface of human islet cells in the diabetic pancreas, the insulitis microenvironment was emulated by exposing the islets to three types of stress: 1) cytokines (IFN-gamma and TNF-alpha); 2) heat shock; and 3) hyperglycemia. However, diabetic sera failed again to recognize membrane antigens on the islet cells after either of these treatments. Neither were islet cells from a newly diagnosed diabetic patient stained by its autologous serum (ICA titer > 80 JDF U). These results suggest that ICSA autoantigen is not expressed in the membrane of human islet cells and therefore raises doubts about their proposed pathogenic role.

Adolescent↗
PubMed1992

Mechanism of action of maternal serum on the interleukin2 receptor expression.

Neoplastic Jurkat cells were submitted to a PHA stimulation test after a preincubation in maternal or nulliparous serum (10% dilution). The Il2R expression was significantly downregulated among maternal serum treated cells. Retroplacental serum was significantly more inhibitive than peripheral maternal serum (P less than 0.01). The maternal IgG fractions and mostly the retroplacental IgG fraction proved to contain a factor mainly responsible for the Il2R expression inhibitive property. The molecular mechanism of this phenomenon was further studied. It was shown that H7 (acting as a protein kinase inhibitor) could not influence the Il2R modulation. E.G.T.A., a calcium chelator, was not able to interfere with the inhibitive influence of maternal serum. It was suggested that the maternal serum mediated inhibition of the IL2R expression is not influenced by the hydrolysis of membrane bound phosphatidyl inositol. In contrast, pertussis toxin markedly enhanced, in a dose dependent way, the suppressive influence of maternal serum as compared to nulliparous serum. At low concentrations, pertussis toxin lost its stimulating property and retained its ability to ADP ribosylate the alpha subunit of G proteins inducing a release of adenylcyclase mediating cAMP synthesis. This mechanism has been further studied by the addition of dbc AMP or dbc GMP to Jurkat cells preparations stimulated by PHA. dbc AMP, in a dose-related way, induced a downregulation of the IL2R expression of stimulated neoplastic cells preincubated in nulliparous or maternal serum. dbc GMP did not influence the IL2R expression in the same experimental conditions. The maternal serum mediated cells showed the most pronounced IL2R inhibition. Finally, it was shown that the cAMP synthesis by PHA stimulated Jurkat cells was upregulated in a dose dependent way, after a previous cellular incubation in progressive concentrations of maternal serum. In contrast, among nulliparous serum pretreated cells, cAMP synthesis remained significantly lower, after a lectin stimulation, as compared to the cAMP production derived from retroplacental serum treated and stimulated cells. Taken together, these experiments suggest that the maternal serum dependent suppression of the IL2R expression is related to a protein G stimulation followed by an enhanced cAMP synthesis.

Calcium↗
PubMed1992

[Restoration of colonic continuity after Hartmann's operation].

A retrospective analysis of data from 69 patients treated by Hartmann's operation between 1981 and 1991 determined prognostic factors for colon continuity re-establishment and the mortality of this second intervention. The 15 patients who died during the first month after the Hartmann's operation were excluded from the study, the 54 survivors including 32 men and 22 women, mean age 68 +/- 12 years (range 19 to 87 years). The initial indication for surgery was: complicated sigmoid diverticulis (n = 26), cancer of colon (n = 14) or other site (n = 14). Colon continuity was re-established in 23 patients (42.6%), including 15 men and 8 women, mean age 60 +/- 10 years (range 38 to 78 years). In this latter group, 82.6% of the patients were under 70 years of age, indicative of a significant effect of age (p < 0.001) on re-establishment of continuity. Secondary anastomosis was obtained in 65.4% of cases of complicated sigmoid diverticulitis, whereas re-establishment of continuity was possible in only 7.1% of colon cancer patients (p < 0.001). The mean duration prior to re-establishment was 4.8 +/- 1.6 months (range 2.5 to 9 months). Morbidity was high (47.8%) and mortality 4.3% (1 patient). Hartmann's operation remains indicated for stages III and IV of complicated sigmoid diverticulosis, as well as for other benign affections (volvulus of sigmoid, perforation of sigmoid following injury), although it must be recognized that the possibilities of re-establishment are limited more in elderly patients and that fewer patients with colon cancer can benefit from the procedure. A period of 3 to 4 months appears sufficient to allow healing of the inflammatory phenomena of the initial operation, without the development of excessive retraction of the rectal stump.

Adult↗
PubMed1991

Long-term vascular access via the inferior vena cava.

A prospective evaluation of long-term venous access catheters placed via the inferior vena cava was performed to determine their efficacy as well as short- and long-term morbidity. From June 1987 to May 1989, 31 catheters were placed in 26 patients, for a total of 3,503 catheter use days. All catheters were placed via an infraumbilical approach when the more conventional supraumbilical route was technically difficult, dangerous, or impossible to be used. There were a total of 14 complications in 12 episodes (one in every 701 catheter use days), six episodes of catheter occlusion or vessel thrombosis (one in every 583 catheter use days), one catheter malfunction, one episode of cuff erosion through the skin, and one catheter that migrated through the inferior vena cava into the retroperitoneum. These results compared favorably with our experience with long-term catheters of a similar type placed via a supraumbilical approach into the superior vena cava. We conclude that the infraumbilical route for long-term central venous access is safe and technically easy and should be strongly considered in patients in whom venous access via the supraumbilical approach will be technically difficult or have a high likelihood of failure.

Adolescent↗
PubMed1991

Laser-induced fluorescence emission: I. The spectroscopic identification of fibrotic endocardium and myocardium.

UNLABELLED: Laser-induced fluorescence has been developed as a guidance system for laser angioplasty. Laser ablation has been used for resection of arrhythmogenic ventricular scar. We have investigated the use of laser-induced fluorescence for the detection of fibrotic and ischemic changes in endocardium and myocardium. Fluorescence emission spectra from human necropsy specimens were correlated with histologic examination. Normalized fluorescence intensity detected from both the endocardial and the myocardial surfaces of the fibrotic ventricular specimens was significantly higher than that of corresponding normal specimens at 440 to 475 nm. Fibrotic endocardium could be identified by a fluorescence emission intensity ratio less than 1.5 for wavelength ratio 375/450nm. Acutely infarcted endocardium was recognizable by a ratio of 1.5 to 2.0. The specificity and sensitivity of detection of scarred endocardium was 70 and 100%, respectively. Fibrotic myocardium was also consistently identified by fluorescence spectroscopy. CONCLUSION: Fluorescence emission spectroscopy can differentiate normal and fibrotic endocardium and myocardium, in vitro. This technique may be useful for guidance during laser ablation of arrhythmogenic ventricular scar.

Capillaries↗
PubMed1991

Modulation of the HLA class II antigen at a molecular level by maternal serum among cord blood cells and unrelated lymphocytes.

A retroplacental serum factor responsible for the downregulation of the MHC class II antigen expression has been described [1]. We found that maternal serum had the same property. The HLA class II modulating activity is however diminished in the presence of maternal serum as compared to retroplacental serum suggesting that the IA like inhibiting factor is released at the fetomaternal interface. After a 3-day incubation period of unrelated lymphocytes and mononuclear cord blood cells in a maternal serum pool, it was shown that the HLA Dr, the HLADp, and more significantly, the HLADq molecules were modulated. This phenomenon was more pronounced among cord blood cells. When third party lymphocytes and mononuclear cord blood cells 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 HLADq 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), we found no changes in the MHC class II molecular constituents. When unrelated mononuclear cells and mononuclear cord blood cells were PHA stimulated in the presence of maternal and nulliparous serum, the HLADq 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 subpopulation (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.

Anti-Bacterial Agents↗
PubMed1991

Palmaris brevis turnover flap as an adjunct to internal neurolysis of the chronically scarred median nerve in recurrent carpal tunnel syndrome.

Thirteen hands in 11 patients with previous carpal tunnel releases were treated by microscopic internal neurolysis and palmaris brevis "turnover" flaps. All patients in the series had positive electrodiagnostic testing, dysesthetic wrist pain, and numbness in the median nerve distribution before operation. Average age was 41.9 years (range, 27 to 62 years). Ten were male and 3 were female. Range of follow-up after the procedure was from 1 to 1 1/2 years. All hands with abnormal preoperative two-point discriminations or Semmes-Weinstein measurements showed numerical improvement in their sensory parameters. Thenar strength and bulk improved at least one grade in all six cases of thenar atrophy. Mean grip strength was 15.2% greater than before operation. Key pinch increased 5.5% and pulp pinch 31.9%. Subjective assessment of improvement ranged from 25% to 100%. All patients returned to their former jobs or to vocational retaining except the oldest patient who is semiretired.

Adult↗
PubMed1991

Birthweight ratio.

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Birth Weight↗
PubMed1991

Neonatal gastrointestinal growth and function: are they regulated by composition of feeds?

The effects of natural suckling versus a cow's milk formula on gastrointestinal growth and mucosal function were measured in newborn guinea pigs during the first 8 days of postnatal life. Comparable growth was achieved between the two groups. Both feeds appeared to be a stimulus for the growth of the gastrointestinal tract and expression of disaccharidases, but not for mucosal growth. Formula feeding was associated with a diminished rate of lactase expression and an enhanced rate of maltase and sucrase expression suggesting that the effect of natural suckling is regulatory, acting to delay expression of an inherent ontogenic programme uncovered by formula feeding. These finding in the precocial guinea pig contrast with those in the altricial rat, and have implications for our understanding of the regulation of gastrointestinal development and effects of formula feeds, in other species, including man.

Animal Nutritional Physiological Phenomena↗
PubMed1991

Modulation of B cell stimulation by maternal serum.

Anti-IgM stimulation of B cells is decreased in the presence of maternal serum as compared to control media. This inhibiting influence of maternal serum is observed during the priming of the B cells. The progression of B cells into cellular proliferation was not influenced by maternal serum. At the level of the immunoglobulin secretion, the influence of maternal serum was also shown. A significant down regulation of the IgM, no change of the IgG production, and an enhanced secretion of IgA and IgE was demonstrated in the presence of maternal serum as compared to control media. It has been suggested that the maternal IgG fraction contains a molecule partly responsible for these changes. Furthermore, the CD23 antigen is increased when B cells are stimulated in the presence of a pool of maternal IgG. All the findings concerning maternal IgG were more pronounced when retroplacental IgG was used instead of peripheral maternal IgG. This observation suggests that the factor responsible for the B cell changes is released at the fetomaternal interface.

Antibodies, Anti-Idiotypic↗
PubMed1991

[Cholelithiasis in patients over 75 years of age. Apropos of 147 cases].

The authors perform a retrospective study of a series of 147 patients aged 75 and more, who were treated for gallstone. AMong them, 104 had conventional surgery and 43 a nonsurgical treatment. The noticeable elements produced by this analysis are: the frequency of common bile duct lithiasis and of severe septic complication in elderly patients, the frequency of previous gallstone, sometimes remote in time, a significantly higher mortality when the treatment is non-surgical (p less than 0.001), mainly due to the septic complications of the lithiasis. the influence of the diathesis on mortality, and finally, the greater inocuity of the right infracostal approach in view of respiratory complications.

Age Factors↗
PubMed1991

Energy expenditure in early infancy and later body fatness.

Total energy expenditure was measured in a cohort of 33 normal, full term infants at 12 weeks of age using the doubly labelled water technique. These data were related to Quetelet's index and the sum of the triceps and subscapular skinfold measurements at 9 months and 2 years of age. Correlation coefficients were used to determine the relationship between total energy expenditure and later indices of body composition. Total energy expenditure was expressed as kcal/kg per day; kcal/kg0.5 per day (in order to negate the effect of body weight) and kcal/kg fat free mass per day (in order to take into account body composition). Using this approach there was no relationship between the level of total energy expenditure at 12 weeks of age and later indices of body fatness. The highest correlation coefficient being 0.09 (n = 33, P greater than 0.10). These findings are contrary to recent reports that a reduced total energy expenditure is related to the development of obesity in certain selected groups of individuals.

Adipose Tissue↗
PubMed1991

Programming by early nutrition in man.

Whether early diet influences long-term health or achievement is a key question in nutrition. Such long-term consequences would invoke the concept of 'programming'--a more general process whereby a stimulus or insult at a critical period of development has lasting or lifelong significance. Data from small mammals and primates show that early nutrition may have potentially important long-term effects, for example on blood lipids, plasma insulin, obesity, atherosclerosis, behaviour and learning. Corresponding studies in man have been largely retrospective and difficult to interpret. The preterm infant is however an important model for human research because formal random assignment to early diet is practical. A large prospective randomized multicentre study has been undertaken on 926 preterm infants to test the hypothesis that early diet influences long-term outcome. Diets included human milk, standard formula and nutrient-enriched preterm formula. The diet consumed for on average the first month post partum had a major impact on subsequent developmental attainment, growth and allergic status in early childhood. That such a brief period of dietary manipulation has lasting significance implies that the neonatal period is critical for nutrition after preterm birth. These data may have broader implications for human nutrition.

Animals↗
PubMed1990

Early diet in preterm babies and developmental status at 18 months.

424 preterm infants were randomly assigned a standard "term" formula or a nutrient-enriched "preterm" formula as sole diets (trial A) or as supplements to mother's own expressed milk (trial B) for a median of 4 weeks postnatally. 18 months post term, blind evaluation of 377 survivors showed that those previously fed preterm rather than term formula had major developmental advantages, more so in motor than mental function; the advantages, in both mental and motor scores, were especially striking in small-for-gestational-age infants and in males. For motor development index in trial A, this advantage was 15 points; in infants born small for gestation, it was 23 points (nearly 1.5 SD). Moderate developmental impairment (developmental index less than 85), notably motor impairment, was considerably more common in the group fed term formula. Infants fed preterm formula also had a small benefit in social maturity quotient. Thus, a short period of early dietary manipulation in preterm infants had major consequences for later development, which suggests that the first weeks may be critical for nutrition.

Age Factors↗
PubMed1990

[Thyrotropic hormone in an adult population seeking care at a primary health care center].

In a study of the need for detecting subclinical hypothyroidism in a population aged 60-80 years, the measurement of thyrotropin with the immunofluorometric technique in 446 individuals seeking attention identified 58 with high TSH (greater than 4 microU/ml); only 33 of these were evaluated in a specialized endocrinological unit. The abnormality was confirmed by radioimmunometric technique in 19 patients (4%), and in the remaining 14 individuals disease was ruled out. The prevalence in this group of individuals is comparable to that found in other studies which recommend screening for subclinical hypothyroidism, but the requirement for the implementation of such a screening program in our area should be carefully evaluated before it could be recommended.

Aged↗
PubMed1990

Early diet of preterm infants and development of allergic or atopic disease: randomised prospective study.

OBJECTIVE: To study the effect of early diet on the development of allergic reactions in infants born preterm. DESIGN: Two randomised prospective trails. In trail A infants were randomly allocated banked donor milk or preterm formula as their sole diet or (separately randomised) as a supplement to their mother's expressed breast milk. In trial B infants were allocated term or preterm formula. A blind follow up examination was done 18 months after the expected date of birth. SETTING: Neonatal units of hospitals in Cambridge, Ipswich, King's Lynn, Norwich, and Sheffield. Outpatient follow up. PARTICIPANTS: 777 Infants with a birth weight less than 1850 g born during 1982 to 1984. MAIN OUTCOME MEASURES: Development of eczema, allergic reactions to food or drugs, and asthma or wheezing by nine and 18 months after term. Whenever possible the observations were confirmed by rechallenge or clinical examination. RESULTS: At 18 months after term there was no difference in the incidence of allergic reactions between dietary groups in either trial. In the subgroup of infants with a family history of atopy, however, those in trial A who received preterm formula rather than human milk had a significantly greater risk of developing one or more allergic reactions (notably eczema) by 18 months (odds ratio 3.6; 95% confidence interval 1.4 to 9.1). CONCLUSIONS: Feeding neonates on formulas based on cows' milk, including those with a high protein content, did not increase the overall risk of allergy. Nevertheless, in the subgroup with a family history of atopy early exposure to cows' milk increased the risk of a wide range of allergic reactions, especially eczema.

Animals↗