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Biomedical subjects

S Ho

Publications and source records attributed to S Ho.

At least 145 records · Page 8Linked to original sources
PubMed1985

Increase of plasma renin activity after subcutaneous application of compound 48/80 in the rat.

Subcutaneous (s.c.) administration of compound 48/80 (3.0 mg/kg) to conscious rats produced a time-dependent long-lasting increase of plasma renin activity (PRA). A dose-related increase of the hematocrit was also observed after injection of compound 48/80. The onset of the hematocrit increase preceded that of PRA increase. Pretreatment with a dose of more than 20 mg/kg of histamine H1-receptor antagonists such as tripelennamine or diphenhydramine prior to the injection of compound 48/80 (3.0 mg/kg s.c.) attenuated or abolished the effects of compound 48/80 on PRA, hematocrit and plasma extravasation. Pretreatment with cimetidine (histamine H2-receptor antagonist, 40 mg/kg i.p.) had no effect on these plasma variables. The increase of PRA caused by s.c. administration of compound 48/80 was not affected by the pretreatment with propranolol (beta-adrenoceptor antagonist, 10 mg/kg i.p.), which completely inhibited the isoproterenol (0.5 mg/kg s.c.)-induced PRA increase. Administration of compound 48/80 did not induce a significant PRA increase in the nephrectomized rats although the increase of hematocrit following s.c. administration of compound 48/80 persisted despite the absence of kidneys. S.c. administration of compound 48/80 (3.0 mg/kg) led to a significant decrease of histamine content at the site of injection and to a significant increase in plasma histamine concentration without affecting arterial blood pressure. The present data suggest that s.c. administration of compound 48/80 stimulates the release of histamine from cutaneous mast cells, which cause an increase in vascular permeability to plasma protein via the stimulation of histamine H1-receptors, then leads to hypovolemia. The resulting hypovolemia may directly stimulate the juxtraglomerular cells of the kidney to release renin.

Animals↗
PubMed1983

Intraspecies variation in methacholine-stimulated esterase release from mouse submandibular gland.

Esterase release was investigated in male and female submandibular glands of 5 strains of mice (ICR/BR, ND/4BR, SW/BR, DDS/Cox and C57BL/6BR) using dispersed cells prepared by treatment with collagenase and hyaluronidase. The muscarinic-cholinergic agonist methacholine stimulated esterase release in C57BL/6BR, DDS/Cox and SW/BR females and DDS/Cox males in a dose-dependent manner, but did not stimulate esterase release in ICR/BR and ND/4BR strains of both sexes. The percentage release of esterase over control in response to methacholine in females was of the descending order: C57BL/6BR, DDS/Cox, SW/BR, ND/4BR, ICR/BR. There was a close relationship between the percentage release of esterase by methacholine and the esterase activity in homogenate of submandibular gland. The lower the esterase content in the homogenate of mouse submandibular gland, the higher the percentage release of esterase by methacholine stimulation in the dispersed cells.

Animals↗
PubMed1983

Ca2+ regulation of tight-junction permeability and structure in Necturus gallbladder.

To explore the role of Ca2+ in tight-junction permeability, the Necturus gallbladder was exposed to varying Ca2+ concentrations and to the Ca2+ ionophore A23187 added to the mucosal side (1.9 X 10(-6) to 6.8 X 10(-5) M). Electrophysiological parameters measured in an Ussing-type chamber were correlated with tight-junction morphology revealed by freeze-fracture electron microscopy. In Ca2+-free bathing media, transepithelial resistance decreases and tight-junctional ultrastructure is fragmented. In 1.8 mM Ca2+ media, A23187 induces an initial drop in transepithelial resistance, followed by an increase in transepithelial resistance to a value 20% above base line. At peak response to A23187, NaCl diffusion potentials decrease. Freeze-fracture replicas reveal that the number of junctional strands increase pari passu with junctional depth. Both physiological and morphological changes were partially reversible. The initial decrease in transepithelial resistance coincided with a persistent hyperpolarization of the mucosal cell membrane potential difference and a decrease in the mucosal-to-serosal cell membrane resistance ratio. Thus A23187 alters both the transcellular and paracellular pathway, resulting in opposing effects on transepithelial resistance.

Animals↗
PubMed1983

Fracture studies on a mammalian semicircular canal.

In the present work the pressures necessary to fracture the semicircular canal of the mammalian inner ear, specifically the squirrel monkey, have been investigated experimentally. The results indicate that individual canals can fracture when subjected to internal pressures of approximately 1.6 +/- 0.4 MPa. Simulation testing using Plexiglas and polycarbonate specimens, to represent the location of a possible osteoclast site within the bone forming a semicircular canal, demonstrates further that fracture of the canal can be initiated at this or even lower pressures when the pressure is generated within a simulated osteoclast site. These results provide useful information for a better understanding of the mechanisms by which bubble nucleation and growth could cause pressures of this magnitude within an osteoclast cavity during the decompression phase of a diving schedule.

Animals↗
PubMed1983

Whole bowel irrigation--an alternative to traditional bowel washout.

The objective of this study was to determine whether or not whole bowel irrigation through oral route was a safe and acceptable alternative to traditional bowel washout per rectum in preparation for large bowel surgery. Out of a total of 114 patients, 32 had whole bowel irrigation, 71 had traditional washout and 11 had no bowel preparation. The irrigation involved approximately 12 litres of normal saline over an average period of 3 1/4 hours. The preparation of the colon by whole bowel irrigation was better as indicated by total absence of faeces and the cleanliness of the colon at operation. However, there was no significant difference in wound infection rate between the two groups although the severity of wound infection was lesser in the first group. There were no major complications like anastomotic breakdown, burst abdomen, abscess or fistula formation and septicaemia in this group. Based on this experience we believe that whole bowel irrigation is a good alternative method of bowel preparation. The advantages of this method are that it is short and rapid, avoiding prolonged pre-operative hospitalisation and is acceptable to most patients.

Aged↗
PubMed1980

Cytoplasmic regulation of tight-junction permeability: effect of plant cytokinins.

The significance of the "leaky" tight junction might be understood better if cells of the epithelial monolayer possessed mechanisms to regulate molecular flow through the junction. To test this possibility, Necturus gallbladder, a representative leaky epithelium, was studied before, during, and after mucosal exposure to plant cytokinins and two other microfilament-active drugs, cytochalasin B and phalloidin. Concomitant with morphological changes in microfilaments, cytokinins induced rapid reversible increases in transepithelial resistance and potential difference (PD) and decreases in NaCl dilution potentials, with no change in the ratio of relative cell membrane resistances. Cytochalasin B (0.2-1.2 microM) and phalloidin (0.6-12.7 microM) caused similar changes in transepithelial resistance and PD. When the intramembranous structure of tight junctions was studied by freeze fracture, peak cytokinin-induced increments in transepithelial resistance were associated with more disorder in the strand meshwork resulting in a small increase in tight junction depth, but there was no evidence of de novo strand assembly. These studies suggest that permeability of the tight junction of Necturus gallbladder is subject to rapid reversible modulation, possibly under cytoskeletal control.

Animals↗
PubMed1978

The effects of pentobarbitone and urethane on pulmonary airway resistance in guinea-pigs and their interactions with drugs.

1 Propranolol increased pulmonary airway resistance (PAR) in the conscious guinea-pig, whereas atropine had no effect, suggesting the existence of a continual sympathetic bronchodilator tone. 2 The direct bronchoconstrictor effects of histamine, acetylcholine and 5-hydroxytryptamine were modified by autonomic reflexes: a bronchodilator one, abolished by propranolol, and a cholinergic bronchoconstrictor one, seen with histamine. 3 Pentobarbitone increased PAR, an effect which was reduced by propranolol but which was unaffected by atropine. The bronchoconstrictor effects of histamine, acetylcholine and 5-hydroxytryptamine were potentiated by pentobarbitone. 4 Pentobarbitone therefore appears to inhibit the adrenergic bronchodilator tone and to depress adrenergic reflexes, these being the preponderant autonomic influences in these experiments. 5 Like pentobarbitone, urethane increased PAR in the conscious guinea-pig and potentiated the bronchoconstrictor effects of the three amines. These actions are similarly attributed to a reduction in adrenergic influences.

Airway Resistance↗
PubMedDate not supplied

Impact of a diagnostic cerebrospinal fluid enterovirus polymerase chain reaction test on patient management.

CONTEXT: Enterovirus (EV) infection, the most common cause of aseptic meningitis, can be rapidly diagnosed with an EV-specific reverse transcriptase polymerase chain reaction (EV-PCR) test. However, no studies have examined EV-PCR in a clinical context in which it is routinely used. OBJECTIVE: To determine the impact of EV-PCR testing on diagnosis and clinical management of suspected aseptic meningitis cases. DESIGN AND SETTING: Retrospective review of electronic medical records from a 220-bed tertiary care pediatric medical center in San Diego, Calif. PATIENTS: A total of 276 pediatric patients for whom a diagnostic EV-PCR test was performed during the calendar year 1998. MAIN OUTCOME MEASURES: Clinical parameters such as length of stay, medication use, and ancillary test use. RESULTS: One hundred thirty-seven patients (49.6%) had a positive cerebrospinal fluid EV-PCR result. Enterovirus-positive patients with results available before hospital discharge (n=95) had significantly fewer ancillary tests performed (26% vs 72% with at least 1 test performed; P<.001), received intravenous antibiotics for less time (median, 2.0 vs 3.5 days; P<.001), and had shorter hospital stays (median, 42 vs 71.5 hours; P<.001) than EV-negative patients (n=92). A positive EV-PCR result was associated with more rapid hospital discharge (median EV-PCR-to-discharge time, 5.2 hours) compared with a negative result (median EV-PCR-to-discharge time, 27.4 hours; P<.001). CONCLUSIONS: Our results suggest that a positive EV-PCR result may affect clinical decision making and can promote rapid discharge of patients, and that unnecessary diagnostic and therapeutic interventions can be reduced by use of EV-PCR testing. JAMA. 2000;283:2680-2685.

Cerebrospinal Fluid↗
PubMedDate not supplied

Disposition of epirubicin in an oily contrast medium after intravenous and intrahepato-arterial administration in liver cancer: a preliminary report.

The present study reports findings on the disposition of epirubicin after an intrahepato-arterial administration of the Lipiodol-drug complex, prepared by mixing the drug-aqueous phase with the iodized oil by ultra-sonification, in 14 patients with histologically proven hepatoma or hepatomegaly with serum alpha-fetoprotein level above 500 micrograms.l-1. The volume of Lipiodol used was 5 ml and the epirubicin dose was 50 mg.m-2. Blood samples were obtained at various time intervals up to 72 h post-dose. Serum concentrations of epirubicin were measured by liquid chromatography with fluorometric detection. The area under serum concentration-time curve (AUCinfinity0) was higher in the Lipiodol-epirubicin group (n = 8) while the clearance was faster and elimination t1/2 and mean residence time shorter in the plain epirubicin group (n = 3). However, interindividual variation in metabolism of epirubicin would affect serum level of the drug. In three patients who were given intravenous and intrahepato-arterial injections (90 mg.m-2) of plain epirubicin and Lipiodol-drug complex, the relative bioavailability of Lipiodol-epirubicin complex (F = 0.76 and 0.45) was lower than that of plain epirubicin (F = 0.80 and 0.73) in two patients while it was approximately 100% (F = 1.06 and 1.20) in one patient. It is likely that liver function of the patients might be modified by the disease state over a period of 3 months in the cross-over study. Further studies with larger patient samples are required to confirm if there is a targeting effect of the Lipiodol-drug complex toward hepatoma using a better formulation of the drug in Lipiodol.

Adult↗
PubMedDate not supplied

Neonatal screening for glutaric aciduria type I: strategies to proceed.

Acute encephalopathic crisis in glutaric aciduria type I results in an unfavourable disease course and poor outcome, dominated by dystonia, feeding problems, seizures and reduced life expectancy. A conditio sine qua non for the prevention of irreversible brain damage is timely diagnosis and start of therapy, i.e. before the onset of neurological disease. As there are no specific clinical signs or symptoms that allow a reliable detection of these patients before the manifestation of encephalopathic crises, neonatal screening programmes for glutaric aciduria type I have been established in some countries using analysis of glutarylcarnitine in dried blood spots by tandem mass spectrometry. This article summarizes recent strategies, pitfalls and shortcomings of mass screening for glutaric aciduria type I, focusing on the relevant risk of missing patients with a mild biochemical phenotype (i.e. low excretors). Furthermore, it evaluates a binary strategy--using glutarylcarnitine as primary variable and glutarylcarnitine/acylcarnitine ratios as secondary variable--to improve the diagnostic sensitivity and specificity of neonatal screening for glutaric aciduria type I. An optimization of diagnostic as well as therapeutic procedures must be achieved before screening for glutaric aciduria type I can be regarded as reliable and beneficial for all patients.

Amino Acid Metabolism, Inborn Errors↗
PubMedDate not supplied

Generation and characterization of a human monoclonal autoantibody that acts as a high affinity interleukin-1 alpha specific inhibitor.

Interleukin-1 (IL-1) defines two polypeptides, IL-1 alpha and IL-1 beta, that possess a wide spectrum of biological effects. Two natural antagonists of IL-1 action have been characterized: the IL-1 receptor antagonist (IL-1Ra) and a soluble form of the type II IL-1 receptor. Neutralizing autoantibodies to IL-1 alpha have also been detected in sera of healthy individuals and patients with autoimmune or inflammatory diseases. To characterize such antibodies molecularly, we attempted to generate B cell clones producing anti-IL-1 alpha human monoclonal antibody (HuMAb) by combining Epstein-Barr virus-immortalization and CD40-activation of B lymphocytes from individuals with circulating anti-IL-1 alpha. We describe herein the generation and properties of a natural IgG4/kappa anti-IL-1 alpha monoclonal autoantibody, HuMAb X3, that bound specifically to human IL-1 alpha, but not to IL-1 beta and IL-1Ra, with a high affinity (Kd = 1.2 x 10(-10)M). HuMAb X3 inhibited IL-1 alpha binding to IL-1 receptors and neutralized biological activities of both recombinant and natural forms of IL-1 alpha. A recombinant form of HuMAb X3 was found to display identical specific IL-1 alpha antagonism. The presence of somatic mutations within X3 variable regions suggests an antigen-driven affinity maturation. This study extends the demonstration of the presence of high affinity neutralizing anti-IL-1 alpha autoantibodies that can function as a third type of IL-1 antagonist.

Amino Acid Sequence↗
PubMedDate not supplied

The DNA sequence and comparative analysis of human chromosome 20.

The finished sequence of human chromosome 20 comprises 59,187,298 base pairs (bp) and represents 99.4% of the euchromatic DNA. A single contig of 26 megabases (Mb) spans the entire short arm, and five contigs separated by gaps totalling 320 kb span the long arm of this metacentric chromosome. An additional 234,339 bp of sequence has been determined within the pericentromeric region of the long arm. We annotated 727 genes and 168 pseudogenes in the sequence. About 64% of these genes have a 5' and a 3' untranslated region and a complete open reading frame. Comparative analysis of the sequence of chromosome 20 to whole-genome shotgun-sequence data of two other vertebrates, the mouse Mus musculus and the puffer fish Tetraodon nigroviridis, provides an independent measure of the efficiency of gene annotation, and indicates that this analysis may account for more than 95% of all coding exons and almost all genes.

Animals↗
PubMedDate not supplied

The role of Bcl-2 expression in EGF inhibition of TNF-alpha/IFN-gamma-induced villous trophoblast apoptosis.

The inflammatory cytokines tumour necrosis factor alpha (TNF-alpha) and immune interferon gamma (IFN-gamma) stimulate villous cytotrophoblast apoptosis while epidermal growth factor (EGF) protects. We hypothesize that TNF-alpha, IFN-gamma and EGF regulate apoptosis in part by modulating cellular expression levels of the anti-death gene bcl-2. While Bcl-2 is reported to be strongly expressed in villous syncytiotrophoblasts, it is not known whether the protein is expressed in cultured villous cytotrophoblasts (CT) and, if so, whether it is functional. We show by Northern blot analysis that bcl-2 mRNA is expressed in cultured CT and by immunoblot analysis that the protein is strongly expressed in highly purified first trimester and term villous cytotrophoblasts. The expression levels of Bcl-2 protein were the same in first trimester and term cytotrophoblasts. Culture with TNF-alpha/IFN-gamma and EGF did not alter expression of either Bcl-2 protein or of the pro-apoptotic Bcl-2 family member Bak. Double label flow cytometric analysis that measured apoptosis and Bcl-2 content simultaneously showed that cells expressing low levels of Bcl-2 underwent TNF-alpha/IFN-gamma-induced apoptosis at a higher frequency than cells expressing lower levels. We conclude that Bcl-2 is expressed in cytotrophoblasts, that its expression is constitutive and that modulation of its expression levels does not mediate cytokine and growth factor regulation of apoptosis in these cells.

Apoptosis↗