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Biomedical subjects

C H Hsu

Publications and source records attributed to C H Hsu.

At least 163 records · Page 9Linked to original sources
PubMed1986

DNA and amino acid sequence analysis of structural and immunity genes of colicins Ia and Ib.

The nucleotide sequences for colicin Ia and colicin Ib structural and immunity genes were determined. The two colicins each consist of 626 amino acid residues. Comparison of the two sequences along their lengths revealed that the two colicins are nearly identical in the N-terminal 426 amino acid residues. The C-terminal 220 amino acid residues of the colicins are only 60% identical, suggesting that this is the region most likely recognized by their cognate immunity proteins. The predicted proteins for the colicin immunity proteins would contain 111 amino acids for the colicin Ia immunity protein and 115 amino acids for the colicin Ib immunity protein. The colicin immunity proteins have no detectable DNA or amino acid homology but do exhibit a conservation of overall hydrophobicity. The colicin immunity genes lie distal to and in opposite orientation to the colicin structural genes. The colicin Ia immunity protein was purified to apparent homogeneity by a combination of isoelectric focusing and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal amino acid sequence of the purified Ia immunity protein was determined and was found to be in perfect agreement with that predicted from the DNA sequence of its structural gene. The Ia immunity protein is not a processed membrane protein.

Amino Acid Sequence↗
PubMed1986

Sonographic finding of the bright thalamus.

Six of 83 asphyxiated neonates showed a diffuse increase of echodensity in bilateral thalami with or without other lesions in the basal ganglia on sonographic examination. The thalamic image still had a fairly high echogenecity compared with the surrounding brain parenchyma on follow up examination and was hence termed the bright thalamus. These six patients had a poor neurological outcome, including psychomotor retardation, spastic diplegia or quadriplegia, microcephaly, failure to thrive, seizures, and one death. The bright thalamus is not an occasional or an isolated sonographic finding of hypoxic-ischaemic encephalopathy, but it may serve as a landmark of severe hypoxic brain damage with adverse outcome.

Asphyxia Neonatorum↗
PubMed1986

Effects of furosemide diuresis on mercuric chloride-induced acute renal failure in the rat.

In previous studies in rats given mercuric chloride (HgCl2), administration of furosemide has been found to either attenuate, exacerbate, or not affect the severity of the acute renal failure (ARF) otherwise expected to obtain. In the current study in rats given large doses of furosemide and in which urinary fluid losses were replaced by intravenous infusions of saline, administration of HgCl2 induced less severe ARF than that induced in rats not given furosemide and saline infusions. In rats not given furosemide, a diuresis induced by continuous reinfusion of urine also conferred protection against the nephrotoxic effect of HgCl2. These findings suggest that in rats given HgCl2: diuresis per se is the critical determinant of any salutary effect of furosemide and the protective effect of diuresis does not depend on renal elimination of mercury.

Acute Kidney Injury↗
PubMed1986

Plasma 1,25(OH)2D3 response to parathyroid hormone, cyclic adenosine monophosphate, and phosphorus depletion in the spontaneously hypertensive rat.

Spontaneously hypertensive rats (SHR) have several abnormalities of calcium metabolism compared with normotensive control Wistar-Kyoto (WKY) rats. Previously the vitamin D metabolite 1,25-dihydroxycholecalciferol (1,25[OH]2D3) was found to be inappropriately low in SHR in view of their ionized hypocalcemia and hyperparathyroidism. We examined the responses of plasma 1,25(OH)2D3 to several known stimuli. Baseline plasma 1,25(OH)2D3 levels tended to be lower in SHR than WKY rats (51.5 +/- 4.3 vs. 82.3 +/- 14.1 pg/ml, P = 0.06). Infusion of a pharmacologic dose of parathyroid hormone (8 U/hr over a period of 17 hours) resulted in a plasma 1,25(OH)2D3 level of 504 +/- 77 pg/ml in SHR vs. 1016 +/- 211 pg/ml in WKY rats (P less than 0.03). Cyclic adenosine monophosphate infusion (1 mumol/hr/100 gm over a period of 17 hours) in thyroparathyroidectomized animals resulted in a 1,25(OH)2D3 level of 121 +/- 24 pg/ml in SHR vs. 557 +/- 26 pg/ml in WKY rats (P less than 0.01). After dietary phosphorus depletion for 3 weeks, SHR also had lower 1,25(OH)2D3 levels than WKY rats (83 +/- 13 vs. 300 +/- 42 pg/ml, P less than 0.001) even though a comparable degree of hypophosphatemia was achieved. Thus, the response of plasma 1,25(OH)2D3 levels to several known stimuli is submaximal in SHR as compared with WKY rats, suggesting defective synthesis or enhanced metabolic clearance of this hormone.

Animals↗
PubMed1986

Pathogenesis of hypercalciuria in spontaneously hypertensive rats.

The etiology of hypercalciuria remains unknown in spontaneously hypertensive rats (SHR). In order to differentiate absorptive versus renal hypercalciuria, serial measurements of urinary calcium (UCaV) excretion were made weekly under fasting (3-hour urine collection) and after oral administration of CaCl2 (50 mg/100 g; 4-hour urine collection) from age 8 to 14 weeks in SHR (n = 14) and normotensive Wistar Kyoto rats (WKY; n = 14). Fasting UCaV was significantly greater in WKY than in SHR throughout the periods of observation. In contrast, after oral Ca loading UCaV was greater in SHR after 13 weeks of age (13 weeks: SHR UCaV = 954 micrograms/mg creatinine, WKY UCaV = 541 p less than 0.01; 14 weeks: SHR UCaV = 988 micrograms/mg creatinine, WKY UCaV = 534, p less than 0.01). Fasting urinary cyclic adenosine monophosphate (AMP) excretion was not different between WKY and SHR. However, cyclic AMP excretion of SHR, but not WKY, was decreased after calcium loading when compared to the fasting values. The cyclic AMP was also significantly lower in SHR than in WKY rats after calcium loading. Calcium handling by the kidney was not different between SHR and WKY with or without parathyroidectomy. Calcium disposition kinetic studies were performed on these animals at age 15 and 16 weeks. No significant difference of intravenous 45Ca was observed between WKY (n = 6) and SHR (n = 6) in total plasma clearance, nonrenal clearance, biologic half-life, and elimination rate constant from the central compartment. However, the WKY had a significantly greater renal clearance of 45Ca than the SHR (0.48 +/- 0.04 vs. 0.24 +/- 0.02 ml/n, p less than 0.001). Since tissue disposition of intravenous 45Ca was not different between WKY and SHR, the increased renal excretion of calcium after oral administration in SHR, therefore, reflects increased intestinal absorption of calcium. Correction of established hypertension did not abolish the hypercalciuria. We believe that increased gastrointestinal absorption of calcium is responsible for the hypercalciuria in SHR.

Administration, Oral↗
PubMed1985

Expression of Sendai virus defective-interfering genomes with internal deletions.

Sendai virus strain 7 has been shown to contain four defective interfering (DI) RNA species in which both genome termini and various adjacent fragments of the 3'-terminal NP gene and 5'-terminal L gene are represented, but most or all internal genes and gene boundaries are deleted. Previous sequence analyses of these mutant RNAs suggested that all four possessed the transcription initiation signal of the NP gene and the transcription termination signal of the L gene. The supposition that these signals should specify transcripts has now been supported by oligo(dT) selection of four DI 7 specific RNA species that had apparent molecular weights slightly lower than each DI genome. DI RNA 7a, which contains the entire NP gene, except for two U residues at the end of the poly(A) initiation signal, appeared to be transcribed solely as a readthrough product. Since DI RNA 7a contains the entire NP protein-coding sequence and DI RNAs 7c and 7d contain fragments of it, whereas DI RNA 7b is devoid of it, only transcripts of RNAs 7c and 7d were expected to specify fusion proteins containing NP gene-specific sequences. A strain 7-induced protein that reacted with monoclonal antibodies against the NP protein had the 33,000 Mr size appropriate for the translation product predicted by the sequence of RNA 7d. Other proteins of lower molecular weight were seen only in cells infected by strain 7, but they did not react with NP-specific antibody and their translation in vitro was not blocked by hybridization to an NP gene-specific oligonucleotide. Therefore, at least some of these proteins may be cellular products induced by DI virus infection. These DI transcripts and translation products may influence interference with replication of the parental helper virus.

Antibodies, Monoclonal↗
PubMed1985

Constitutively phosphorylated residues in the NS protein of vesicular stomatitis virus.

The NS protein of vesicular stomatitis virus is an auxiliary protein in the virus core (nucleocapsid) that plays a role in virus-specific RNA synthesis. NS exhibits a variety of phosphorylated forms, and the degree of phosphorylation correlates with the rate of RNA synthesis. However, chymotryptic peptide mapping has indicated that all forms of NS share a common cluster of phosphorylated residues. To locate these residues in the primary structure of the molecule, we performed a series of residue-specific chemical and enzymatic cleavages and separated radiophosphate-labeled peptides by gel electrophoresis. The data indicate that the constitutively phosphorylated sites in NS molecules reside in the amino-terminal region of the molecule, between residues 35 and 78. The previously reported resistance of the phosphoamino acids in this region to dephosphorylation by exogenous phosphatase suggests that this domain is embedded within the tertiary structure of the molecule or involved in quaternary interactions. In contrast, the amino acid residues that are phosphorylated secondarily, making NS more active in RNA synthesis, reside in more exposed regions of the molecule.

Aspartic Acid↗
PubMed1984

Renal phosphate excretion in spontaneously hypertensive and normotensive Wistar Kyoto rats.

Renal tubular reabsorption of phosphate was studied in unanesthetized spontaneously hypertensive (SHR) and normotensive Wistar Kyoto rats (WKY). Three-hour-urinary phosphate excretions of 12-week-old-male SHR (53.0 +/- 13.1 micrograms/mg creatinine, N = 7) and 14-week-old female SHR (81.8 +/- 12.8, N = 8) were significantly lower than those of age sex-matched WKY (12 week, 435.8 +/- 73.2, N = 8, P less than 0.01; 14 week, 423.3 +/- 75.9, N = 8, P less than 0.01). Renal clearances were performed in 14-week-old female rats after an overnight fast. The serum phosphate concentration of SHR (4.61 +/- 0.25 mg/dl) was lower than that of WKY (5.44 +/- 0.14, P less than 0.02). Urinary phosphate excretion (U Pi V = 6.85 +/- 1.83 micrograms/min) and fractional phosphate excretion (FE Pi = 13.7 +/- 2.3%) of SHR were lower than those of WKY (U Pi V = 15.9 +/- 1.87 micrograms/min, P less than 0.01, FE Pi 22.8 +/- 2.6%, P less than 0.02). Acute hyperventilation could not account for the lower excretion of phosphate in SHR, since arterial pH and PCO2 were not different between WKY and SHR. The low renal phosphate clearance of SHR was noted at a very early age; the U Pi V of 5-week-old SHR was already lower than that of WKY. Maximum tubular phosphate reabsorption (TmPi) was studied in the 12-week-old SHR and WKY after acute thyroparathyroidectomy. TmPi of SHR (241 +/- 3.0 micrograms/ml GFR/100 g, N = 7) was greater than that of WKY (204 +/- 7.0, N = 8, P less than 0.01). However, the differences in 3-hr urinary phosphate excretion and clearances of phosphate were abolished between SHR and WKY after their blood pressures were lowered by chronic hydralazine treatment. The results indicate that hypertension is responsible for the lower renal phosphate clearances in SHR.

Animals↗
PubMed1984

Bicarbonate hemodialysis: influence on plasma refilling and hemodynamic stability.

The present study compares the effect of sodium bicarbonate (LoNaHCO3, Na = 134, HCO3 = 33 mEq/l) and sodium acetate (LoNaAc, Na = 134, acetate 33 mEq/1)dialysate on the extravascular fluid mobilization (VFM) and hemodynamic changes in 6 patients during 3 h of hemodialysis with equivalent fluid ultrafiltration of about 600 ml/h. The cumulative decrease in plasma volume after 1, 2 and 3 h of dialysis was significantly less during LoNaHCO3 dialysis than during LoNaAc dialysis, with plasma volume almost completely refilled by VFM during the first 2 h of LoNaHCO3 dialysis. High sodium acetate dialysate (HiNaAc, Na = 144, acetate = 33 mEq/1) with equivalent fluid ultrafiltration also resulted in less net decrease in plasma volume and greater VFM than LoNaAc, although the temporal pattern of refilling was somewhat different from that during LoNaHCO3: rapid and complete refilling during the early portion of LoNaHCO3, slower and more progressive refilling during HiNaAc, with similar cumulative refilling for LoNaHCO3 and HiNaAc by 3 h. Mean arterial pressure (MAP) tended to decrease during LoNaAc dialysis, whereas MAP remained stable during LoNaHCO3 and increased slightly during HiNaAc. This study, therefore, suggests that improved hemodynamic stability utilizing bicarbonate dialysate may be due, in part, to greater plasma refilling and better preservation of plasma volume.

Acetates↗
PubMed1982

Contribution of oligosaccharide sulfation to the charge heterogeneity of a viral glycoprotein.

The single glycoprotein species of vesicular stomatitis virus exhibits heterogeneity in isoelectric focusing. Short term radioisotopic labeling of infected cells revealed that this heterogeneity is acquired after synthesis and glycosylation of the protein, during the period of oligosaccharide processing from the high mannose to the complex form. In this process, radioactive sulfate is incorporated randomly into different glycoprotein molecules, conferring unequal amounts of negative charge upon them. Since the virus glycoprotein is processed by cellular pathways, it is likely that differential sulfation is responsible for much of the charge heterogeneity displayed by cellular glycoproteins.

Animals↗
PubMed1982

The effect of renal perfusion pressure on renal vascular resistance in the spontaneously hypertensive rat.

Renal hemodynamics and renal vascular resistance (RVR) were measured in the spontaneously hypertensive rat (SHR) and in the normotensive Wistar-Kyoto rat (WKY). In addition, the autoregulatory response and segmental RVR in the SHR were studied after aortic constriction. Mean arterial pressure (MAP) and RVR were higher in the SHR than in the WKY, but renal blood flow (RBF) and glomerular filtration rate were similar in both groups. Measurement of mean afferent arteriolar diameter (AAD) by a microsphere method showed a significantly smaller AAD in SHR (17.7 +/- 0.35 micrometers) than in the WKY (19.5 +/- 0.20 micrometers). This decrease in AAD could account for a 47% increase in preglomerular resistance. Aortic constriction in the SHR, sufficient to reduce renal perfusion pressure from 152 to 115 mmHg, did not alter the AAD. Since RBF and glomerular filtration were also well maintained following aortic constriction, these autoregulatory responses suggest that vessels proximal to the afferent arteriole rather than postglomerular vasculature are primarily involved in the changes on intrarenal vascular resistance in SHR.

Animals↗
PubMed1982

NS phosphoprotein of vesicular stomatitis virus: subspecies separated by electrophoresis and isoelectric focusing.

The NS protein of vesicular stomatitis virus is the only phosphorylated nucleocapsid protein. The amount of NS phosphorylation appears to regulate the activity of the protein in the transcription of the virus genome. Several methods have been used to separate NS subspecies containing different amounts of phosphate, but the relationships among the subspecies separated by different workers have been unclear. We report that the isoelectric points of NS molecules were abnormally acidic in some commercial ampholytes, but favorable ampholytes resolved multiple phosphorylated NS subspecies with isoelectric points ranging from pH 6.8 to 7.2. The most highly phosphorylated NS molecules had more acidic isoelectric points, and they exhibited greater electrophoretic mobilities in two previously employed electrophoretic systems.

Capsid↗