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Biomedical subjects

J Chou

Publications and source records attributed to J Chou.

At least 55 records · Page 3Linked to original sources
PubMed1992

The gamma 1(34.5) gene of herpes simplex virus 1 precludes neuroblastoma cells from triggering total shutoff of protein synthesis characteristic of programed cell death in neuronal cells.

The gamma 1(34.5) gene of herpes simplex virus 1 was previously shown to play a role in viral virulence since deletion of the gene reduced by a factor of approximately 100,000 the capacity of the virus to replicate in the central nervous system and cause mortality in the mouse. Here we show that in the human neuroblastoma cell line SK-N-SH of neuronal origin gamma 1(34.5) null mutants expressed early proteins, viral DNA, and mRNA of late genes. However, the onset of viral DNA synthesis triggered complete cessation of incorporation of radioactive precursors into proteins. The mutant and wild-type viruses replicated and could not be differentiated in cell lines or cell strains of nonneuronal origin. The results indicate that in the absence of the gamma 1(34.5) gene the SK-N-SH neuroblastoma cells triggered a response similar to the programed cell death of neuronal cells induced by metabolic stress. The gamma 1(34.5) protein precludes this cell response possibly in order to enable the protein synthesis necessary for viral replication.

Animals↗
PubMed1992

Correlates of blood pressure differ in high and in low plasma renin groups.

It has been proposed that the aetiology, pathophysiological status, and effective treatment of hypertensives depends on concomitant plasma renin levels. Epidemiological data are scarce on the interrelations of plasma renin activity (PRA), BP and correlates of BP in the general population. Therefore, profiles of BP correlates were compared between low PRA groups and high PRA groups in a relatively healthy population of 321 Chinese government employees working in the Taipei area, in the summer of 1987. The characteristics of the two PRA groups were similar in body mass index, urinary sodium, chloride, calcium excretion and fasting parathyroid hormone. However, the high PRA group was younger, smoked more, and had a higher mean urinary potassium excretion. Fasting plasma glucose, uric acid, and creatinine levels were lower in the low PRA group. Positive relationships between BP and urinary sodium, chloride, potassium, calcium, plasma cholesterol, triglyceride, and glucose, independent of age and body mass index, were demonstrated in the low PRA group, where a volume expansion state may exist. However, in the high PRA state, uric acid, haemoglobin concentration, insulin and parathyroid hormone level were correlated more closely with BP than in the low PRA state. Further studies are needed to examine whether the differing associations between BP and risk factors in the high and low PRA groups reflect different compensatory mechanisms or aetiological factors.

Blood Pressure↗
PubMed1991

Big endothelin in plasma and amniotic fluid.

UNLABELLED: We previously demonstrated that endothelin-1 (ET-1) exists both in the peripheral circulation and the amniotic fluid (AF). The objects of the present study were (a) to measure the concentrations of ET-1 and big endothelin (big ET) in plasma and AF by radioimmunoassay (RIA) and (b) to characterize the molecular forms of endothelin in human AF by high-performance liquid chromatography (HPLC) coupled with RIAs. Plasma samples from healthy male and female volunteers, and AF samples from full-term and mid-trimester pregnant women were extracted by C18 cartridges. Big ET, like ET-1, exists both in plasma and in AF. Significant increases (p less than 0.01) of big ET and ET-1 in AF from mid-trimester to full-term pregnancy were observed. The reverse-phase HPLC elution profile of immunoreactive (ir-) ET-1 presented a single major peak at a position corresponding to that of the standard ET-1 in the extracted AF. Two major components of ir-big ET were revealed: one corresponded to the elution position of standard big ET; the other one to that of the standard endothelin fragment [22-38] (EF). IN CONCLUSION: (a) Three molecular forms of ET exist in AF: ET-1 as a major form, big ET, and EF. (b) ET-1 and big ET are both present in higher concentrations in AF at full-term pregnancy than during mid-trimester.

Adult↗
PubMed1991

Effect of oral glucose ingestion on hepatic non-esterified fatty acids and ketone body metabolism in normal dogs.

The time course of changes in hepatic lipid metabolism (non-esterified fatty acids (NEFA), ketone body) after ingestion of glucose was assessed in normal dogs. Glucose ingestion suppressed significantly (p less than 0.01) the amount of NEFA reaching the liver (12.4 +/- 1.0 to a nadir of 2.9 +/- 0.6 mumol/kg/min at 80 min) and increased significantly (p less than 0.05) net hepatic balance (-1.8 +/- 0.6 to 0.5 +/- 0.4 mumol/kg/min at 120 min). After glucose ingestion, the amount of total ketone body presented to the liver decreased significantly (p less than 0.05) to a nadir of 1.1 +/- 0.4 mumol/kg/min at 60 min and gradually increased after 120 min. These changes reflect the increased insulin secretion induced by glucose ingestion. The hyperinsulinemia would inhibit peripheral lipolysis and stimulate esterification of fatty acids. It would reduce ketone body concentration both by a direct effect on hepatic production as well as the consequence of diminished NEFA levels. In summary, the present study clearly demonstrated the time course changes in NEFA and ketone body level after oral glucose ingestion.

Animals↗
PubMed1990

Mapping of herpes simplex virus-1 neurovirulence to gamma 134.5, a gene nonessential for growth in culture.

The gene designated gamma 134.5 maps in the inverted repeats flanking the long unique sequence of herpes simplex virus-1 (HSV-1) DNA, and therefore it is present in two copies per genome. This gene is not essential for viral growth in cell culture. Four recombinant viruses were genetically engineered to test the function of this gene. These were (i) a virus from which both copies of the gene were deleted, (ii) a virus containing a stop codon in both copies of the gene, (iii) a virus containing after the first codon an insert encoding a 16-amino acid epitope known to react with a specific monoclonal antibody, and (iv) a virus in which the deleted sequences were restored. The viruses from which the gene was deleted or which carried stop codons were avirulent on intracerebral inoculation of mice. The virus with the gene tagged by the sequence encoding the epitope was moderately virulent, whereas the restored virus reacquired the phenotype of the parent virus. Significant amounts of virus were recovered only from brains of animals inoculated with virulent viruses. Inasmuch as the product of the gamma 134.5 gene extended the host range of the virus by enabling it to replicate and destroy brain cells, it is a viral neurovirulence factor.

Amino Acid Sequence↗
PubMed1990

Positive relationship between urinary sodium chloride and blood pressure in Chinese health examinees and its association with calcium excretion.

The relationships between salt, urinary calcium and blood pressure were studied in 401 middle-aged Chinese men. Seven overnight urine samples were collected. Three consecutive blood pressure measurements were made on two occasions. The 24-h urinary sodium estimate was positively associated with both mean systolic and diastolic blood pressure (P less than 0.001), controlled for age and body mass index. Urinary chloride was also positively associated with blood pressure (P less than 0.001) at a magnitude similar to that of sodium. Potassium was not related to blood pressure. Urinary calcium was significantly correlated to sodium (r = 0.46) and was positively associated with systolic (P less than 0.001) and diastolic (P less than 0.01) blood pressure. The relationship between calcium and blood pressure was partly explained by salt intake. Similar findings were obtained using electrolyte to creatinine ratios. These results confirm the positive relationship between salt and blood pressure within a Chinese population living in Taipei and indicate a possible, positive relationship between blood pressure and urinary calcium excretion, either dependent or independent of salt intake.

Age Factors↗
PubMed1990

The herpes simplex virus 1 gene for ICP34.5, which maps in inverted repeats, is conserved in several limited-passage isolates but not in strain 17syn+.

In a previous study, it was reported that herpes simplex virus 1 (HSV-1) strain F contains a transcribed open reading frame situated in the inverted repeats of the L component between the terminal a sequence and the open reading frame that encodes the alpha 0 gene (J. Chou and B. Roizman, J. Virol. 57: 629-637, 1986). By means of an antibody to repeats of the trimer Ala-Thr-Pro predicted to be specified by the open reading frame, it was shown that the open reading frame specifies a protein (M. Ackermann, J. Chou, M. Sarmiento, R. A. Lerner, and B. Roizman, J. Virol. 58: 843-850, 1986). This open reading frame is absent from the reported sequence of HSV-1(17)syn+ (D. J. McGeoch, M. A. Dalrymple, A. J. Davison, A. Dolan, M. C. Frame, D. McNab, L. J. Perry, J. E. Scott, and P. Taylor, J. Gen. Virol. 69: 1531-1574, 1988; L. J. Perry and D. J. McGeoch, J. Gen. Virol. 69: 2831-2846, 1988). To define the extent of variability in this open reading frame, we compared the sequences of the ICP34.5-encoding open reading frames of the genomes of three strains characterized by limited passage in cell culture with that of the HSV-1(17)syn+ strain. Furthermore, to establish unambiguously that the antibody to the Ala-Thr-Pro repeats reacts with the product of this open reading frame, we inserted a short sequence that encodes a known epitope in frame at the 5' terminus of the coding domain. Our results indicate that with minor variations, the open reading frame is conserved in the three HSV-1 genomes analyzed but not in HSV-1(17)syn+. Thus, two strains contain an inserted amino acid and one strain, isolated from a case of human encephalitis, lacks a seven-amino-acid sequence. The recombinant virus carrying the foreign epitope expressed a slightly slower-migrating protein which reacted with both the rabbit polyclonal antibody to the Ala-Thr-Pro trimer repeats and the monoclonal antibody to the inserted epitope. The implications of the results are discussed.

Amino Acid Sequence↗
PubMed1990

Effects of meal ingestion on plasma amylin concentration in NIDDM and nondiabetic humans.

Recent interest has focused on the potential role of amylin in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM). This 37-amino acid peptide is found in extracellular amyloid deposits in approximately 50% of pancreatic islets of patients with NIDDM and has been shown to inhibit skeletal muscle glycogen synthesis in vitro. Immunocytochemical studies have colocalized amylin and insulin within beta-cell secretory granules in nondiabetic humans, provoking the following questions. Is amylin cosecreted with insulin? Are circulating amylin concentrations higher in patients with NIDDM either before or after food ingestion? To answer these questions, we developed a sensitive and specific immunoassay to measure plasma concentrations of amylin in humans. Use of this assay indicated that, in lean nondiabetic subjects, glucose ingestion resulted in an increase (P less than 0.001) in the plasma concentration of amylin (from 2.03 +/- 0.22 to 3.78 +/- 0.39 pM) and insulin (from 48.3 +/- 3.1 to 265 +/- 44 pM). There was a significant correlation between the concentrations of insulin and amylin (r = 0.74, P less than 0.001) and the increase in insulin and amylin concentration (r = 0.65, P less than 0.005). Fasting concentrations of amylin did not differ in diabetic and weight-matched nondiabetic subjects and showed a similar pattern of change after ingestion of a mixed meal. We conclude that amylin is secreted in response to ingestion of either glucose or a mixed meal and circulates at concentrations that do not differ in patients with NIDDM and nondiabetic subjects. It remains to be determined whether amylin at physiological concentrations influences carbohydrate metabolism and if so whether its effects differ in diabetic and nondiabetic humans.

Adult↗
PubMed1989

Type II collagen screening in the human chondrodysplasias.

Abnormalities of type II collagen have been considered strong candidates for causing human condrodysplasias. We have employed peptide mapping to screen for several types of type II colagen abnormalities in cartilage samples from 66 patients with 20 separate disorders. Except for achondrogenesis type II (Langer-Saldino) and spondyloepiphyseal dysplasia (SED) congenita in which abnormalities have been described and diastrophic dysplasia in which the changes were probably secondary, no abnormalities were detected. Within the limitations of the screening technique, the results combined with other data from the literature suggest that abnormalities of this molecule are not common causes of chondrodysplasias outside of the achondrogenesis type II-SED congenita family of disorders.

Adolescent↗
PubMed1989

Characterization of DNA sequence-common and sequence-specific proteins binding to cis-acting sites for cleavage of the terminal a sequence of the herpes simplex virus 1 genome.

The terminal 500-base-pair alpha sequence of the herpes simplex virus 1 genome contains signals for cleavage (Pac1 and Pac2) of unit-length DNA molecules from concatemers in unique stretches of sequences designated Ub and Uc, respectively, and a cis site for cleavage designated DR1. We report that nuclear extracts from infected cells contain factors which form two DNA-virus-specific protein complexes with components of the a sequence. Purification of the factors forming the V2 complex yielded a protein with an apparent molecular weight of 82,000 binding to DNA in a non-sequence-specific manner. Addition of Mg2+ to the purified protein-DNA probe mixture resulted in exonucleolytic degradation of the DNA. The protein was identified as the virus-specific DNase with monoclonal antibody specific for the viral enzyme. The purification of the proteins forming the V4 complex yielded two proteins with molecular weights of greater than 250,000 and 140,000 corresponding to infected cell protein 1 and to an as yet unidentified protein, respectively. These proteins formed two DNA sequence-common bands with a number of DNA probes and one sequence-specific band with probes containing both Pac2 and DR1 but not with probes containing either site alone or Pac1 and DR1. Since the DNA probe containing Pac2 and DR1 inserted into viral genome or into amplicons induced specific cleavage of the DR1 sequence whereas the nonreactive probes failed to induce the cleavage, the formation of this sequence-specific DNA-protein complex is significant and may reflect a DNA-protein interaction essential for cleavage. The possible role of the proteins identified in this study for the cleavage-packaging of viral DNA into capsids is presented.

DNA Probes↗
PubMed1989

Fasting and postabsorptive hepatic glucose and insulin metabolism in hyperthyroidism.

The effect of thyroid hormone excess on hepatic glucose balances and fractional hepatic extraction of insulin and glucagon was examined in six conscious dogs with catheters in the portal vein, hepatic vein, and femoral artery and Doppler flow probes on the portal vein and hepatic artery. An oral glucose tolerance test was performed before and after the animals were made hyperthyroid by intramuscular thyroxine administration (100 micrograms.kg-1.day-1) for 10 days. In the basal state and after oral glucose, insulin and glucagon levels in the three vessels and the basal fractional hepatic extraction of insulin and glucagon were not significantly modified by thyroid hormone. These results suggest that in short-term thyrotoxicosis insulin secretion is not impaired, and the rise in fasting plasma glucose and increased hepatic glucose production could reflect hepatic insulin resistance, increased availability of precursors for gluconeogenesis, or increased glycogenolysis. Hyperthyroidism significantly increased basal flows in the portal vein (14.7 +/- 0.6 vs. 12.9 +/- 0.5 ml.kg-1.min-1), the hepatic artery (4.8 +/- 0.3 vs. 3.9 +/- 0.2 ml.kg-1.min-1) and vein (19.6 +/- 0.7 vs. 16.9 +/- 0.4 ml.kg-1.min-1), the fasting plasma glucose concentration (104 +/- 3 vs. 92 +/- 2 mg/dl), and basal hepatic glucose output (2.1 +/- 0.2 vs. 1.5 +/- 0.2 mg.kg-1.min-1). It did not alter the nonhepatic splanchnic uptake of glucose, the percent of orally administered glucose that appeared in the portal vein (47 +/- 2 vs. 45 +/- 11%), the percent of hepatic uptake of glucose (59 +/- 11 vs. 74 +/- 22%), or the shape of the glucose tolerance test.

Animals↗
PubMed1989

Synergistic cytotoxic effect of azidothymidine and recombinant interferon alpha on normal human bone marrow progenitor cells.

Azidothymidine (AZT) and interferon alpha (IFN-alpha) are among the drugs showing strong in vitro activity against the human immunodeficiency virus type-1 (HIV-1). Each drug, however, has significant toxicity against normal marrow progenitor cells that frequently proves dose-limiting in patients. In this study, AZT and recombinant IFN-alpha 2a (rIFN-alpha 2a) were tested as single agents and in combination against normal myeloid (CFU-GM) and erythroid (BFU-E) colony forming cells in a standard methylcellulose culture assay. The data were analyzed using a quantitative computerized analysis based on the median-effect principle and the isobologram equation as described by Chou and Talalay (Adv Enz Regul 22:27, 1984). The ED90 for BFU-E and CFU-GM inhibition was then compared with previously measured in vivo plasma levels of each drug and the ED90 for the anti-HIV-1 effect in vitro. We demonstrate that (a) the drugs are strongly synergistic in inhibiting marrow progenitor cell growth and that this synergism occurs at drug levels that are within the range of measured plasma levels in phase I clinical trials, (b) BFU-E are more sensitive than CFU-GM to the inhibiting effects of AZT, rIFN-alpha 2a or both drugs in combination, (c) the drug concentrations in combination that synergistically inhibit bone marrow progenitors are much higher than those required to inhibit HIV-1 replication in vitro, and (d) the anti-HIV-1 effect for the combination of AZT and rIFN-alpha 2a was clearly superior to the effect of AZT or rIFN-alpha 2a alone as indicated by the combination index and the dose-reduction index. These data suggest that substantially lower doses of AZT and rIFN-alpha than those currently being tested in clinical trials might not only maintain a strong synergistic anti-HIV-1 effect but might also avoid significant hematologic toxicity.

Bone Marrow↗
PubMed1988

Vitamin A deficiency and pulmonary oxygen toxicity: morphometric studies in the murine lung.

Vitamin A and its precursor beta-carotene are naturally occurring antioxidants. The effects of diets deficient in beta-carotene and vitamin A on the alveolar-capillary membrane were studied in young adult BALB/C mice before and after exposure to 65% oxygen. One of three diets (standard complete, beta-carotene deficient, or beta-carotene and vitamin A deficient) was fed for a 6-wk period. Mice were then exposed to 65% oxygen for 0, 3, or 6 days, sacrificed, and their lungs examined by electron microscopy using the morphometric techniques of Weibel. The arithmetic and the harmonic mean thicknesses of the alveolar-capillary membrane and its components (epithelium, interstitium, and endothelium) were measured to assess the influences of diet and of duration of exposure to 65% oxygen. Analysis of variance and multiple comparisons of means (Student-Neuman-Keuls statistics) were applied. Diet alone did not significantly affect membrane thickness. However, duration of oxygen exposure increased the thicknesses of both the epithelium and interstitium in the group fed a diet deficient in both beta-carotene and vitamin A as compared to the other two groups although this was only significant for the epithelium. beta-Carotene deficiency alone did not affect the respiratory membrane either before or after oxygen exposure. These results suggest that vitamin A may be an important nutrient in the protection against pulmonary oxygen toxicity.

Animals↗
PubMed1987

High affinity peptide histidine isoleucine-preferring receptors in rat liver.

Peptide Histidine Isoleucine (PHI) is generally considered a low affinity agonist for Vasoactive Intestinal Peptide (VIP) receptors. In this study, we investigated the presence and characteristics of [125I]PHI binding sites on rat liver membranes. Detergents at nonsolubilizing concentrations (1 mM CHAPS or 0.01% Tween-20) were included in the assay buffer to reduce adsorptive loss of PHI to acceptable levels and permit measurement of PHI-binding to receptors. Under these conditions, binding of PHI to liver membranes was time- and temperature-dependent, reversible and saturable. Unlabeled PHI was 9.7-fold more potent than VIP, and 357-fold more potent than secretin in displacing [125I]-PHI binding. Scatchard analysis suggested the presence of two classes of PHI receptors, with Kd 27 pM and 512 pM. The data from [125I]-PHI and [125I]-VIP binding studies suggested that one class of receptors was PHI-preferring, and the other, equally reactive with PHI and VIP. The concentration of immunoreactive PHI, measured by radioimmunoassay, in blood from the hepatic portal vein of anesthetized rats was 2-fold higher than that from the hepatic vein, suggesting uptake of circulating PHI by the liver.

Animals↗
PubMed1987

First-pass hepatic extraction and metabolic effects of insulin and insulin analogues.

First-pass hepatic extraction of insulin and hepatic and peripheral contributions to hypoglycemia were compared in conscious dogs during portal infusion of insulin A1, B29 diacetyl insulin, or A1-B29 dodecoyl insulin at 7 and 14 pmol X kg-1 X min-1. The liver removed 43 +/- 2% of insulin, 12 +/- 1% of dodecoyl, and 8 +/- 1% of diacetyl insulin, in a single transhepatic circulation. The hypoglycemia induced by insulin and diacetyl insulin and the ensuing glucagon response were greater than that produced by the dodecoyl analogue. Diacetyl insulin primarily increased glucose utilization, dodecoyl insulin solely inhibited hepatic production, and insulin affected both. The lack of hepatic effect of diacetyl insulin during hypoglycemia can be ascribed to greater counterregulation, because under euglycemic clamp conditions, this analogue caused suppression of glucose production. The different patterns of hypoglycemia exhibited can be explained by the combined effects of altered distribution between the liver and peripheral tissues caused by differences in hepatic extraction, the effect of this phenomenon on the counterregulatory response, and the intrinsic biological potency of the analogues.

Animals↗
PubMed1986

The terminal a sequence of the herpes simplex virus genome contains the promoter of a gene located in the repeat sequences of the L component.

The herpes simplex virus DNA genome consists of two covalently linked components, L and S. The unique sequences of the L component are flanked by 9-kilobase-pair inverted repeat sequences ab and b'a', whereas those of the S component are flanked by 6.5-kilobase-pair inverted repeat sequences c'a' and ca. We report that the 500-base-pair a sequence contains the promoter-regulatory domain and the transcription initiation site of a diploid gene, the coding sequences of which are located in the b sequences of the inverted repeats of the L component. The chimeric gene constructed by fusion of the a sequence to the coding sequences of the thymidine kinase gene and recombined into the viral genome was regulated as a gamma 1 gene. The size of the protein predicted from its sequence is 358 amino acids; it was designated as infected cell protein (ICP) 34.5. Thus, the inverted repeats flanking the unique sequences of the L component contain two genes specifying ICP0 and ICP34.5, respectively. Moreover, in addition to the cis-acting sites for the inversion of L and S components relative to each other, for cleavage of unit length DNA molecules from head-to-tail concatemers, and for packaging of the DNA into capsids, the a sequence also contains the promoter-regulatory domain and transcription initiation sites of a gene.

Amino Acid Sequence↗
PubMed1986

Identification by antibody to a synthetic peptide of a protein specified by a diploid gene located in the terminal repeats of the L component of herpes simplex virus genome.

In the course of studies on the a sequences located at the termini of and at the junction between the L and S components of herpes simplex virus 1 DNA, J. Chou and B. Roizman (J. Virol. 57:629-637, 1986) noted that the a sequence acted as a gamma 1 promoter when fused to the structural sequence of the thymidine kinase gene, the b inverted repeat sequences located in the L component next to the a sequences contained an open reading frame predicted to encode the protein of 358 amino acids with a molecular weight of 37,054, and the transcription of an RNA homologous to the open reading frame initiated within the a sequence. The nucleotide sequence of the open reading frame predicted the presence of the triplet Ala-Thr-Pro repeated 10 times. To verify the existence of the predicted gene, designated gamma 134.5, a synthetic peptide consisting of the triplet Ala-Thr-Pro repeated 10 times was synthesized and used to raise antibodies in rabbits. The results were as follows. The antiserum to the peptide reacted with a 43,500-apparent-molecular-weight protein present in lysates of cells infected with herpes simplex virus 1 but not present in mock-infected or herpes simplex virus 2-infected cells. We genetically engineered a recombinant virus containing a single copy of a truncated gene. Concordant with predictions, the antibody reacted with a faster-migrating protein in cells infected with this recombinant. The gamma 134.5 gene product was soluble, and it accumulated primarily in the cytoplasm late in infection. The overlap of the domain of the gamma 134.5 gene with the a sequence raises the possibility that it acts in trans on the a sequence and is associated with one of the functions currently ascribed to the a sequences.

Amino Acid Sequence↗