[Atrial septal defect in the adult: clinical course with medical treatment, pre-operative risk, and long-term postoperative survival].
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Adult↗
Biomedical subjects
A Levi
Publications and source records attributed to A Levi.
Molecular cloning and characterization of the human VGF promoter region.
The VGF gene encodes a secretory protein that is expressed in a cell type-restricted pattern in neuroendocrine cells and is up-regulated by nerve growth factor (NGF) in the rat pheochromocytoma PC12 cell line. Here we report the isolation and characterization of the 5'-terminal region of the human VGF gene. In addition to a TATA box and a CCAAT box located at canonical distances from the transcription start site, the human VGF promoter contains several consensus sequences for different transcription factors, including a cyclic AMP response element and an AP-1 element, several GC boxes, and sequences homologous to other neuronal promoters. Transient transfection analysis demonstrates that 2.3 kb of the 5'-flanking sequence acts as a tissue-specific promoter, efficiently used only by neuronal cells that express endogenous VGF. Deletion analysis reveals that a positive regulatory region is located between nucleotides -458 to -204. Negative cis-acting elements that repress promoter activity in cell lines that do not normally express VGF are located between nucleotides -2,305 and -573 and between -458 and -204. The 5'-flanking region of the human VGF gene confers responsiveness to NGF, cyclic AMP, and phorbol ester treatment.
Animals↗
Spatial distribution of dihydropyridine receptors in the plasma membrane of guinea pig cardiac myocytes investigated by correlative confocal microscopy and label-fracture electron microscopy.
Excitation-contraction coupling in cardiac muscle is thought to depend fundamentally on the spatial organization of sarcolemmal dihydropyridine receptors (L-type calcium channels) in relation to ryanodine receptors (calcium-release channels of the sarcoplasmic reticulum). In the present study, we have investigated the distribution of dihydropyridine receptors in the guinea pig myocyte plasma membrane by correlative immunoconfocal microscopy and label-fracture electron microscopy. Label-fracture, a method in freeze-fracture cytochemistry, permits immunogold localization of cell surface proteins in en face membrane views. Taken together, results from confocal microscopy and label-fracture replicas suggest that, in the peripheral plasma membrane, calcium channels are organized predominantly in the form of clusters. Confocal microscopy also suggests a similar organization in the transverse tubules. It is hypothesized that these clusters may lie adjacent to junctional sarcoplasmic reticulum, permitting the close coupling of influx of calcium through plasma membrane calcium channels to trigger release of calcium from the intracellular stores, as part of the mechanism of calcium-induced calcium release.
Animals↗
Interplay of the E box, the cyclic AMP response element, and HTF4/HEB in transcriptional regulation of the neurospecific, neurotrophin-inducible vgf gene.
vgf is a neurotrophin response-specific, developmentally regulated gene that codes for a neurosecretory polypeptide. Its transcription in neuronal cells is selectively activated by the neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor, and neurotrophin 3, which induce survival and differentiation, and not by epidermal growth factor. We studied a short region of the rat vgf promoter which is essential for its regulated expression. A cyclic AMP response element (CRE) within this region is necessary for NGF induction of vgf transcription. Two sites upstream of CRE, an E box and a CCAAT sequence, bind nuclear protein complexes and are involved in transcriptional control. The E box has a dual role. It acts as an inhibitor in NIH 3T3 fibroblasts, together with a second E box located downstream, and as a stimulator in the NGF-responsive cell line PC12. By expression screening, we have isolated the cDNA for a basic helix-loop-helix transcription factor, a homolog of the HTF4/HEB E protein, that specifically binds the vgf promoter E box. The E protein was present in various cell lines, including PC12 cells, and was a component of a multiprotein nuclear complex that binds the promoter in vitro. The E box and CRE cooperate in binding to this complex, which may be an important determinant for neural cell-specific expression.
3T3 Cells↗
Repair of fascia with polyglycolic acid mesh cultured with fibroblasts--experimental study.
In the present study polyglycolic acid (PGA) mesh was used for repair of fascial defects experimentally made in rats. In the experimental group fibroblasts were cultured on the mesh before implantation and in the control group the mesh alone was used. Rats were sacrificed 7, 14, 28 and 60 days after the implantation of the mesh. Tissues were examined microscopically and for hydroxyproline content. Microscopically good incorporation of the mesh was noted in both the control and experimental groups. However, it seems that in the experimental group earlier dissolution of the mesh occurred. The hydroxyproline content was higher in the experimental group after 7 (statistically not significant) and 14 days (p < 0.05) and in the control group after 28 (p < 0.025) and 60 days (p < 0.05). These results suggest that the use of PGA mesh with cultured fibroblasts might have a beneficial effect on wound healing.
Animals↗
Effects of gelatin and BSA on the amplification reaction for generating RAPD.
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Animals↗
Planter foot pressures in pregnant women.
UNLABELLED: The physiological changes occurring during pregnancy may be responsible for the faulty foot position leading to backache and lower limb pain. We evaluated the changes in the plantar foot pressures during pregnancy. Twenty-eight, full-term, healthy, pregnant women, average age 28 years, were examined and evaluated clinically, and the plantar foot pressure distribution was measured statically and dynamically using the EMED system. Twenty-eight, non-pregnant women, average age 25 years, served as the control group. In the static measurements, the pregnant women had significantly lower maximal forefoot pressures and higher hindfoot pressures than the non-pregnant women. The area of the foot in contact with the measuring pressure plate was greater in the pregnant women than in the non-pregnant women. In the dynamic measurements, the maximal force in almost every area of interest was significantly higher. The total force exerted on the pressure plate at the instant of maximal force of every area of interest during the whole step was higher in the pregnant group. On the medial side of the forefoot there was a slight decrease in the contact time of the maximal force. The peak pressures were higher in the midfoot of both feet and on the lateral side of the right forefoot in the pregnant women. In the medial side of the forefoot, the peak pressures were lower in pregnant women. CONCLUSIONS: The pregnant woman has a different pattern of gait. There is an increase of load on the lateral side of the foot and the hindfoot. These changes may be responsible for the musculoskeletal complaints of lower limb pain in pregnant women.
Adult↗
Congenital long-QT syndrome: deleterious effect of long-term high-rate ventricular pacing and definitive treatment by cardiac transplantation.
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Cardiac Pacing, Artificial↗
Healing of the esophageal suture line: does it differ from the rest of the alimentary tract?
We investigated the healing pattern of the esophageal suture line in rats. Fifty male wistar rats were divided into experimental (n = 40) and control (n = 10) groups. The rats in the experimental group underwent esophogostomy at the abdominal esophagus, which was immediately sutured, and sacrificed 2, 4, 7 and 14 days later. Esophageal bursting pressure and hydroxyproline content were determined in both groups. The measured bursting pressures in the experimental group on days 2, 4, 7 and 14 were (mean +/- SD) 78 +/- 35, 95 +/- 12, 1,163 +/- 98 and 1,224 +/- 22 cm H2O, respectively, and 1,308 +/- 87 cm H2O in the control group (P <0.05 vs. all the experimental group values). The hydroxyproline content in the experimental group on days 2, 4, 7 and 14 were 13.9 +/- 2.1, 12.53 +/- 2.68, 15.6 +/- 0.85 and 17.75 +/- 5.65 microg/mg, respectively, and 27.88 +/- 2.5 microg/mg in the control group (P <0.05 vs. all the experimental group values). We conclude that the esophagus demonstrates the same healing pattern as the rest of the alimentary tract, but its healing seems to occur at a slower pace.
Animals↗
Neuronal differentiation of P19 embryonal cells exhibits cell-specific regulation of neurotrophin receptors.
During development, the regulation of expression of the Trk family of tyrosine kinase receptors plays an important role in defining the cellular responses to neurotrophin action. We report here that neurotrophin receptors are differentially expressed in distinct populations of retinoic acid-differentiated P19 cells. TrkB, the tyrosine kinase receptor for brain-derived neurotrophic factor, and LNGFR, the low-affinity receptor for all neutrophins, are preferentially expressed in P19-derived neurones. In contrast, retinoic acid induces the expression of TrkA, the high-affinity receptor for nerve growth factor, and of a non-catalytic form of TrkB, in non-neural subsets of differentiated cells. We propose P19 cells as a model system to study the mechanisms controlling the expression of neurotrophin receptors and the responsiveness of developing neurones to a specific neurotrophin.
Animals↗
Fetal pelvic kidney: a challenge in prenatal diagnosis?
The objective of this study was to establish ultrasonographic guidelines for the prenatal diagnosis of fetal pelvic kidneys and assess the relationship to clinical outcome. The records of all ultrasonographic diagnoses of a fetal pelvic kidney between 1 January 1991 and 31 December 1993 were reviewed. After review of the sonographic evaluation, the prenatal records were obtained, to assess demographic data as well as the obstetric course and neonatal outcome. If a fetal pelvic kidney was suspected on prenatal ultrasound examination, its precise location and size were recorded and compared with neonatal sonograms. Twenty-six cases of fetal ectopic kidney were diagnosed of which 13 were on the right side and 13 on the left (24/26 cases were diagnosed in the late second trimester). The size of the ectopic kidney did not differ from that of the normal kidney. Except for one case of hydronephrosis, there were no associated structural anomalies. All prenatal diagnoses were confirmed by postnatal sonograms and all neonates had normal renal function. Our conclusions are that prenatal sonographic detection of fetal pelvic kidney is feasible, although in most cases the diagnosis is made beyond 24 weeks' gestation. The importance of prenatal diagnosis is that the parents can be reassured that normal renal function is highly probable and that early neonatal intervention is usually unnecessary.
Adult↗
Tissue-specific processing of the neuroendocrine protein VGF.
VGF is a neuroendocrine-specific gene product that is up-regulated by nerve growth factor in the PC12 cell line. In rat neuroendocrine tissues two polypeptides of 90 and 80 kDa were detected by an antiserum to an N-terminal domain of VGF (from residues 4 to 240). In parallel, an antiserum directed against the C-terminal nonapeptide of VGF (from residues 609 to 617) revealed several additional posttranslational products. Peptides of apparent molecular sizes of 20, 18, and 10 kDa were prominent in nerve tissues and the hypophysis but absent in the adrenal medulla, and their relative abundance varied in distinct regions of the CNS. In PC12 cells VGF was proteolytically processed only after nerve growth factor treatment, and primary cultures of rat cerebellar granule cells accumulated the low-molecular-weight forms of VGF during in vitro maturation. In these cells the specific cleavages of VGF occurred in a postendoplasmic reticulum compartment; the processed forms were enriched in the secretory vesicles and were preferentially secreted upon cell membrane depolarization. Distinct differential distribution in the CNS and in vitro release of such posttranslational products indicate that these species may represent biologically relevant forms of VGF that play a role in neuronal communication.
Adrenal Medulla↗
The hyperpolarisation-activated current, I(f), is not required for pacemaking in single cells from the rabbit atrioventricular node.
The atrioventricular node (AVN) is vital for cardiac function. One of its properties is that it can act as a pacemaker for the ventricles if the sinoatrial node fails. This study investigates the role of the hyperpolarisation-activated inward current (I(f)) in generating pacemaker activity in morphologically normal single cells isolated from the rabbit AVN. Whole-cell patch-clamp recordings show that 80%-90% of AVN myocytes do not possess I(f), but nevertheless generate spontaneous action potentials with normal pacemaker depolarisations before each action potential upstroke. We have termed this type of cell "type 1". A small proportion (10%-20%) of spontaneously active AVN cells (type 2) do exhibit I(f). A 100 nM solution of isoprenaline increased the action potential rate of type 1 cells by 31%. In these cells isoprenaline did not activate any I(f) whereas in type 2 cells it clearly increased the amplitude of I(f). Manganese at 2 mM also increased the amplitude of I(f) in type 2 cells, but did not reveal I(f) in type 1 cells. We conclude that, whilst I(f) may play a role in modulating pacemaker activity in type 2 cells, in the majority of AVN cells (type 1) pacemaker depolarisation normally occurs in the complete absence of I(f). Furthermore, the inability of both isoprenaline and Mn to reveal I(f) in type 1 cells suggests that I(f) channels may be absent in these cells.
Animals↗
Differential expression of nerve growth factor receptors leads to altered binding affinity and neurotrophin responsiveness.
The low-affinity p75 neurotrophin receptor is believed to participate with the Trk receptor tyrosine kinase in the formation of high-affinity binding sites for nerve growth factor (NGF). To investigate the functional significance of the two NGF receptors, a truncated p75 receptor was stably expressed in PC12 rat pheochromocytoma cells, yielding cells with greatly reduced levels of wild-type p75 and normal Trk levels. Although these cells were capable of normal differentiation by NGF, very few high-affinity NGF binding sites were detected. These findings indicate that high-affinity binding may be functionally dissociated from biological responses. Furthermore, an increased responsiveness to neurotrophin 3 was observed, as manifested by increased neurite outgrowth. These results suggest that a correct ratio of p75 and p140trk is required to create high-affinity sites and that p75 expression may assist in the discrimination between related but different neurotrophin factors.
Animals↗
Eupergit C-coated membranes as solid support for a sensitive immunoassay of human albumin.
A number of commercially available membranes preactivated by coating with oxirane-containing Eupergit C beads were used for diagnostic immunoassay applications. These membranes possess a higher capacity for protein binding than the respective unmodified membranes as measured with fluorescently labelled antibodies. Immobilization of antigens or antibodies as the first step of the assay was achieved by covalent binding of amino groups of proteins to the oxirane moieties introduced onto the membranes. The high performance of the newly developed membranes bearing covalently bound antibodies, was demonstrated by a dot enzyme-linked microalbuminuria immunoassay as compared to unmodified membranes.
Albumins↗
Pronus angina (angina pectoris induced by stooping or crouching). A proposed mechanism.
Patients with severe coronary artery disease (CAD) sometimes complain of chest pressure upon crouching or bending-forward (pronus angina). The factors that trigger pronus angina are not clear. We therefore investigated 28 patients with CAD and 26 normal subjects in the sitting, knee-chest, stooping, and squatting positions. Systolic and diastolic blood pressures were found to increase by 13.5 and 19.5 percent (p < 0.005) in the stooping position. In addition, left ventricular (LV) ejection time index (LVETI) also increased (p < 0.005). Despite the acute rise in aortic pressure, which is expected to lengthen the pre-ejection period index (PEPI), the latter shortened slightly in 10 of 14 (71 percent) patients tested, suggesting augmentation in contractile force during the isovolumic phase. Finally, left atrial size increased (p < 0.005) during the knee-chest maneuver, suggesting that the LV size also increases upon bending forward. The effect of stooping on blood pressure was similar in magnitude to that of squatting. It is concluded that the triggering factor for "pronus angina" in severe CAD may be explained as a combination of hemodynamic events which acutely increase myocardial oxygen requirements.
Aged↗
Regulatory elements in the promoter region of vgf, a nerve growth factor-inducible gene.
vgf, a gene coding for a protein secreted through the regulated pathway, is rapidly up-modulated by nerve growth factor in PC12 cells and is expressed in vivo only in cell subpopulations of neuronal and endocrine origin. Here we demonstrate the following: (i) the nerve growth factor-dependent induction of vgf mRNA occurs at the transcriptional level and requires ongoing protein synthesis, (ii) lack of vgf expression in the nonneuronal cell line HTC is in part mediated by the presence of a repressor, (iii) a 110-base-pair sequence in the vgf promoter region contains positive and negative regulatory elements that partially account for its regulated expression, and (iv) a 47-base-pair oligonucleotide within this sequence specifically binds nuclear proteins that differ between vgf-expressing and non-expressing cells.
Adrenal Gland Neoplasms↗
Effects of the dipyridamole test on left ventricular function in coronary artery disease.
The dipyridamole stress test is used with thallium-201 to detect areas of inhomogeneity of blood flow that point to coronary artery disease (CAD). It is unclear whether dipyridamole produces inhomogeneous perfusion only or whether it actually decreases net flow in the obstructed vessels and produces true ischemia. It is also unclear what effect dipyridamole has on global and segmental left ventricular function. Therefore, ejection fraction, segmental wall motion and ventricular volume equivalents were measured before and after dipyridamole in 113 patients and 32 normal subjects. Ejection fraction responded in an abnormal fashion in 98 patients (87%), decreasing from 49 +/- 11% to 43 +/- 13% (p less than 0.0001), whereas it increased in 29 normal subjects (90%) from 57 +/- 6% to 64 +/- 10% (p less than 0.0001). Wall motion worsened distinctly in 75 patients (66%), and pressure/volume ratio deteriorated in 72%. The effect of dipyridamole lasted between 10 and 25 minutes, but was promptly reversed by aminophylline. These findings indicate that dipyridamole generally induces true ischemia in CAD. Furthermore, the degree of dysfunction is related to the angiographically assessed severity of CAD. The shortness of breath (seen in 10% of patients) may be partially explained by the findings, and it seems advisable to give aminophylline to every patient in order to promptly correct left ventricular dysfunction.
Adult↗