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Biomedical subjects

J Simon

Publications and source records attributed to J Simon.

At least 289 records · Page 16Linked to original sources
PubMed1994

Impact of cardiovascular risk factors on morbidity and mortality in Czech middle-aged men: Pilsen Longitudinal Study.

The impact of biological and life-style characteristics measured during baseline examination on 12-year morbidity and mortality of coronary heart disease (CHD), stroke (STR), and malignancies was investigated in an urban population of 3,540 middle-aged men initially free of clinical disease. The following factors enhanced significantly (at the 5% level) the adjusted relative risk ratios: for total mortality age, smoking, and elevated systolic blood pressure; for CHD age, smoking, elevated systolic blood pressure, serum cholesterol levels, and body mass index, and family history (father or mother). Myocardial infarction was positively associated with age, smoking and elevated serum cholesterol levels. For STR age and elevation of both systolic and diastolic blood pressure were risk factors. The relative risk for all malignancies was enhanced by age and smoking. Regular alcohol consumption was associated with a significantly lower risk for all CHD; however, with only marginal significance for myocardial infarction. Higher education was associated with a significantly lower risk of total mortality, all CHD, and myocardial infarction and a marginally lower risk of STR. A high leisure physical activity was negatively (but not significantly) associated with the risk of all end points.

Adult↗
PubMed1994

Increased insulin receptor number and insulin responsiveness in a chicken hepatoma cell line.

Insulin receptor number and insulin responsiveness were compared in a chicken hepatoma cell line (LMH) and in normal chicken hepatocyte (cHep) cells cultured in the same conditions. LMH cells expressed two- to threefold more insulin receptors than cHep cells, without significant changes in affinity. The tyrosine kinase activity of solubilized and lectin (lentil+wheat germ agglutinin; WGA)-purified LMH receptors was higher than that of cHep receptors. The ATP hydrolytic activity previously observed in WGA-purified receptors from chicken liver membranes was also present in WGA-purified receptors from cultured cHep cells. This unidentified membrane-associated ATPase was absent from LMH membrane-solubilized material and therefore from WGA-purified LMH insulin receptors. Finally, LMH cells incorporated at least tenfold more amino isobutyric acid than cHep cells in the absence of insulin and were more responsive to insulin. The enhanced basal amino acid transport of LMH cells was most probably the consequence of their proliferative activity. The enhanced insulin responsiveness of LMH cells can be accounted for, at least in part, by one or several of the modifications presently demonstrated in LMH cells when compared with normal cultured hepatocytes: increased insulin receptor number and tyrosine kinase activity and possibly the loss of the membrane-associated ATPase.

Amino Acids↗
PubMed1994

Preferential binding of insulin-like growth factors to a binding protein rather than to receptors on chicken hepatoma cell (LMH) membranes.

[125I]IGF-I binding to chicken hepatoma cell (LMH) membranes was displaced by unlabelled IGF-I or IGF-II, but not by insulin. Cross-linking revealed specific binding sites of 128 and 28-31 kDa, which following solubilization could be separated by wheat germ agglutinin (WGA) chromatography. [125I]IGF-I binding to the WGA eluate (128 kDa) could be displaced by insulin although with a 30-fold lower potency than IGF-I. Binding to the WGA flow-through (28-31 kDa) was not inhibited by insulin. This suggested that IGF binding to LMH was due mainly to membrane bound IGFBP rather than to type 1 IGF receptors. A reverse proportion was observed in normal chicken liver. A predominant 28 kDa IGFBP was synthesized and secreted by LMH cells, together with an unusual 60 kDa IGF binding entity which only bound [125I]IGF-II (with weak affinity). This process was not affected by the presence or absence of glucose, dexamethasone, glucagon, insulin or IGF-I.

Animals↗
PubMed1994

Effects of glucocorticoid treatment of the carbonic anhydrase activity of brain tissue in the early postnatal age in the rat.

The carbonic anhydrase activity in the brain tissue shows a considerable increase with proceeding gliogenesis during the first three postnatal weeks in the rat. The administration of 10 to 30 micrograms corticosterone or 5 to 10 micrograms dexamethasone per g body weight to 3-day old rats produced a marked acceleration in maturation of enzyme activity in the neocortex and hippocampus. The noradrenaline-induced stimulation of enzyme activity under in vitro conditions was also enhanced in corticosterone pretreated rats. There was no difference between the influence of noradrenaline and cAMP on stimulation of enzyme activity in either control or glucocorticoid-pretreated rats. In contrast to the corticosterone, the pretreatment with dexamethasone failed to stimulate the noradrenaline or cAMP effects on enzyme activity which may be due to differences in receptor-mediated responses for glucocorticoids. The glucocorticoid-induced acceleration of enzyme activity in the early postnatal period may be attributed to an enhanced development of glial elements.

Animals↗
PubMed1994

[Comparative evaluation of clinical and ultrasonographic screening of hip dislocation in Breton and Languedoc populations].

BACKGROUND: Congenital dislocation of the hip varies greatly in incidence among different regions. This work is aimed at comparing results of clinical investigation and ultrasonography of the hip in Languedoc-Roussillon and Brittany. POPULATION AND METHODS: Two thousand eight hundred and twelve and 2,809 neonates admitted to Nîmes and Vannes hospitals respectively, were enrolled in a prospective study. Clinical examinations were made according to the protocol established by the "Groupe d' études en orthopédie pédiatrique". Ultrasound investigations were performed in every risk case. RESULTS: No dislocation occurred in the 4946 neonates without risk factors. In the 675 neonates with risk factors, 213 ultrasonographic examinations were abnormal, more frequently in the Brittany group (P < 0.001); nine dislocations were observed. A familial history of hip dysplasia (P < 0.001) and the addition of two risk factors (P < 0.001) were more frequent in Brittany. One hundred and six cases required treatment, more frequently in Brittany (P < 0.001). CONCLUSIONS: Some clinical risk factors and delayed ossification or hip dysplasia at ultrasound examination are significantly more frequent in Brittany. Clinical examination with selective ultrasonography is a reliable method, allowing early diagnosis and treatment of delayed dislocations.

Adult↗
PubMed1994

Effects of ACTH 1-24 on hydrolysis of beta-casomorphin-4-nitroanilide in brain homogenates in vivo and in vitro.

Administration of ACTH 1-24 to 3-10 days old rats produced a significant decrease in hydrolysis of beta-casomorphin-4-nitroanilide (beta-CM-4NA) in the cytosolic fraction of brain homogenate in the first three hours after injection. Corticosterone treatment did not modify the hydrolysis of the substrate. ACTH 1-24 but not ACTH 4-10, Met-enkephalin or Leuenkephalin given to the brain homogenate resulted in a dose-dependent decrease in liberation of 4NA from beta-CM-4NA. Kinetic data suggest competitive inhibition of ACTH molecule on hydrolysis of beta-CMA-4NA. The ACTH treatment, however, did not influence the hydrolysis of Pro-Gly-4NA or Pro-Pro-4NA in the brain homogenate in vitro.

Animals↗
PubMed1994

Transient expression of the recombinant chick brain P2y1 purinoceptor and localization of the corresponding mRNA.

Extracellular ATP acts at specific cell surface purinoceptors to elicit a wide range of physiological responses. We have recently isolated a cDNA for a G-protein-coupled P2 purinoceptor (P2y1) from chick brain. It has been defined as a P2Y-like purinoceptor by the rank order of potency of P2 purinoceptor ligands, determined electrophysiologically in the Xenopus oocyte expression system. Here, we examine the ligand selectivity of this recombinant receptor, expressed transiently in COS-7 cells. The regional distribution of the P2y1 purinoceptor transcript within the one-day-post-hatch chick brain was also determined. It is widely expressed in the cerebellum and telencephalon and in specific nuclei of the mesencephalon and diencephalon, suggesting a neuronal localization of the P21 purinoceptor.

Adenosine Triphosphate↗
PubMed1994

[Immunoscintigraphy results in the comparison of ocular with cutaneous melanoma].

For several years, immunoscintigraphy (IS) using a 99mTc-labeled monoclonal antibody for tumor localization has been used as an additional tool in the diagnosis of malignant melanoma. The aim of our study was to verify previously published data with respect to our own patients and to correlate immunoscintigraphic results with histological findings. In particular, we wanted to compare the outcome of IS in ocular melanoma with that in cutaneous melanoma. We examined 28 patients (15 females, 13 males, average age 64 years) with clinically suspected ocular melanoma. IS was performed using the monoclonal antibody 225.28S (Tecnemab-K-1, Fa. Sorin/Solco), and images were obtained in a standard fashion (planar) as well as with the SPECT technique. In 16 patients, the tumor was examined afterwards histologically. The control group consisted of 102 patients with histologically proven metastasizing cutaneous melanoma who were investigated by IS in an identical fashion. In contrast to the literature published so far, we demonstrated a positive IS reaction in only 42% (and 56% in histologically proven cases, respectively) in our patients with ocular melanoma, while in patients with cutaneous melanoma, we found a sensitivity of more than 80%. In the 3 patients who turned out not to have ocular melanoma, we found one false-positive reaction (subretinal hemorrhage). No correlation was found between the various histological features of ocular melanoma and the immunoscintigraphic results. We conclude that IS using the antibody 25.28S is of limited value in patients with ocular melanoma and should only be recommended in selected cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Choroid Neoplasms↗
PubMed1994

Evolution of cellular and humoral response against Tuberculin and antigen 85 complex during intravesical treatment with BCG of superficial bladder cancer.

Prophylactic treatment with Bacillus Calmette-Guerin (BCG) is an established and effective therapy of bladder cancer. The antitumor effect of BCG seems to be largely related to cellular immunological mechanisms, although its precise mode of action is unknown. Antitumor response of BCG seems to be initiated by the attachment of BCG to bladder wall via Fibronectin (FN). The cellular immune response against Tuberculin PPD and the major secreted BCG antigen (Fibronectin-binding AG 85 complex) has been tested in a control group of 20 untreated bladder tumor patients and before and after 6 weekly intravesical BCG instillations in a group of 20 superficial bladder tumor patients. A major increase in the lymphoproliferative response against PPD and AG 85 was observed in respectively 66% and 57% of the treated patients. In contrast, no detectable antibody response (IgA, IgM, IgG) was observed against AG 85 complex after BCG treatment. On the other hand, antibodies against Tuberculin increased in 13 of 20 patients. This study seems to demonstrate a specific cellular immune activation against AG 85 Fibronectin-binding complex during BCG treatment of superficial bladder tumors. Humoral response against the AG 85 is not activated after BCG treatment. Further studies are needed to elucidate the role of AG 85 in the cellular intravesical penetration of BCG. Presence or absence of cellular response against this antigen could be of clinical value.

Administration, Intravesical↗
PubMed1994

Intraventricular cerebral neuroblastoma. Analysis of subtypes and comparison with hemispheric neuroblastoma.

Two cases of intraventricular neuroblastomas were compared with cases of intraventricular and hemispheric neuroblastomas that have been reported in the published literature. The following order of tumor subtypes was found in patients with increasing age: hemispheric neuroblastoma, intraventricular undifferentiated neuroblastoma, intraventricular differentiated neuroblastoma, and intraventricular neurocytoma; for patients with intraventricular neuroblastomas, this was also the order of increasing cellular maturation and survival. Neuronal morphologic or epitope differentiation was associated with a longer survival time than lack of differentiation by Kaplan-Meier product-limit estimates and with a better survival rate (chi 2) for intraventricular tumors but not for hemispheric tumors. Pathologic distinction of a neurocytoma was confirmed with immunostaining or ultrastructural studies that suggested that a neurocytoma is a matured neuroblastoma of a granule-cell (interneuron) phenotype. Differences among neuroblastoma groups bolster previous suggestions that intraventricular tumors arise differently than do cases of hemispheric tumors and follow a more benign course when neuronal differentiation is present.

Adult↗
PubMed1993

Interactions of liposomes and hydrophobically-modified poly-(N-isopropylacrylamides): an attempt to model the cytoskeleton.

The interactions of small unilamellar vesicles (SUV) and water-soluble copolymers were studied by fluorescence spectroscopy, differential scanning calorimetry (DSC) and quasi-elastic light scattering (QELS). The anchoring onto liposomal bilayer membranes of copolymers of N-isopropylacrylamide, N-(2-(1-naphthyl)ethyl)-N-n-octadecylacrylamide and or N-[4-(1-pyrenyl)butyl]-N-n-octadecylacrylamide (0.5 mol% of the octadecylacrylamide comonomer) was monitored by non-radiative energy transfer between excited naphthalene and pyrene. The anchoring process occurred on zwitterionic lecithin liposomes and on negatively charged phosphatidic acid liposomes, whether the bilayer was in the crystalline or the liquid-crystalline phase. Insertion of the copolymer octadecyl groups within crystalline bilayers was attributed to the presence of packing defects. Aqueous solutions of poly-(N-isopropylacrylamide) and of its hydrophobically-modified copolymers exhibit a lower critical solution temperature (LCST). The coil to globule collapse of the polymer chains which is known to occur as the aqueous solution is heated through the LCST, also took place when the copolymers were anchored onto vesicular bilayers. The copolymers remained anchored during this collapse and the liposomes were not destroyed. The process was thermo-reversible. Detailed aspects of the reversibility of the phenomenon depended on the relative values of the phase transition temperatures of the liposomes and of the polymer LCST.

Acrylic Resins↗
PubMed1993

[Can the cardiologist implant pacemakers without a surgeon?].

The authors evaluate the results of activities of the cardiostimulation centre during a two-year period: 1991-1992 with special attention to the incidence of surgical complications. As in the authors' department are implanted by cardiologists without the assistance of a surgeon, the authors compared the frequency of surgical complications with data from departments where implantations are made by a cardiologists and a surgeon. During the investigation period a total of 315 operations were performed, incl. 229 primary implantations. Early surgical complications developed in two subjects (0.63%). Late surgical complications occurred in 22 patients (6.98%). The total was thus 24 complications, i.e. 7.58% of all operations. These results are comparable with the percentage of complications reported in our literature and literature published in other countries. Permanent cardiac pacing is a routine operation which can be implemented by a well trained cardiologist without a surgeon, without a negative impact on the patient. The authors conclude that under new economic conditions this approach makes the implantation cheaper and simpler from the technical aspect.

Adult↗
PubMed1993

Cloning and functional expression of a brain G-protein-coupled ATP receptor.

A cDNA encoding a novel member of the G-protein-coupled receptor (GCR) superfamily, an ATP receptor, has been isolated from an embryonic chick whole brain cDNA library by hybridization screening. The encoded protein has a sequence of 362 amino acids (41 kDa) and shares no more than 27% amino acid identity with any known GCR. When expressed as a complementary RNA (cRNA) in Xenopus oocytes a slowly-developing inward current was observed in response to application of ATP. The pharmacology of this expressed protein defines it as a P2Y purinoceptor.

Adenosine Triphosphate↗
PubMed1993

Regulation of amino acid transport and protein metabolism in myotubes derived from chicken muscle satellite cells by insulin-like growth factor-I.

The effects of insulin and insulin-like growth factor-I (IGF-I) on amino acid transport and protein metabolism were compared in myotubes derived from chicken breast muscle satellite cells. Protein synthesis was assessed by continuous labelling with [3H]-tyrosine. Protein degradation was estimated by the release of trichloroacetic acid (TCA) soluble radioactivity by cells which had been previously labelled with [3H]-tyrosine for 3 days. Amino acid transport was measured in myotubes incubated in Dulbecco's modified Eagle's medium (DMEM) 0.5% bovine serum albumin (BSA) with or without insulin or IGF-I. Subsequent [3H]-aminoisobutyric acid (AIB) uptake was then measured in amino acid-free medium. IGF-I was more efficient than insulin at equimolar concentration (3.2 nmol/l) in stimulating protein synthesis (127 and 113% of basal, respectively) and inhibiting protein degradation (32% and 13% inhibition of protein degradation following 4 h incubation). Half maximal effective concentrations for stimulation of AIB uptake were 0.27 +/- 0.03 nmol/l and 34.8 +/- 3.1 nmol/l for IGF-I and insulin respectively, with maximal stimulation of about 340% of basal. Cycloheximide (3.6 mumol/l) diminished IGF-I-stimulated AIB uptake by 55%. Chicken growth hormone had no effect on basal AIB uptake in these cells and neither glucagon nor dexamethasone had an effect on basal or IGF-I-stimulated AIB uptake. This study demonstrates an anabolic effect for IGF-I in myotubes derived from primary chicken satellite cells which is mediated by the type I IGF receptor, since the cation-independent mannose 6-phosphate receptor does not bind IGF-II in chicken cells.

Amino Acids↗
PubMed1993

Elements of the Drosophila bithorax complex that mediate repression by Polycomb group products.

The Polycomb (Pc) group genes encode repressors that restrict expression of homeotic genes to precise domains along the anterior-posterior (A-P) axis. We describe germ-line transformation constructs, containing portions of the bxd, iab-2, or iab-3 regulatory regions of the bithorax complex (BX-C), that are controlled by Pc group products in embryos. There are multiple BX-C elements that mediate Pc group control, which we call Pc group response elements (PREs), and they can work when removed from the normal BX-C context. These constructs are each regulated by the genes Polycomb (Pc), extra sex combs (esc), Enhancer of zeste (E[z]), polyhomeotic (ph), Polycomb-like (Pcl), Sex comb on midleg (Scm), Posterior sex combs (Psc), and Additional sex combs (Asx), consistent with multiple Pc group products acting together. Depending upon context, a PRE from the iab-3 region can restrict expression in different A-P positions. Thus, PREs are not specialized for particular parasegments, suggesting that Pc group products do not directly specify A-P boundaries of homeotic expression. Instead, the results support the idea that Pc group products provide stable memory or imprinting of boundaries which are initially specified by gap and pair-rule regulators.

Animals↗