Biomedical subjects
Publications and source records attributed to C J Huang.
We have used PCR to amplify and align the sequence of two genes encoding cGTH alpha. Both genes comprise four exons and three introns. The organization of cGTH alpha genes is very similar to that of mammalian GTH alpha genes. However, the cGTH alpha genes only span a region of 1.2 kb which is much smaller than those mammalian GTH alpha genes.
When Escherichia coli HB101 harbors pWR127, a plasmid comprising the viaB gene from Citrobacter freundii WR7004 and the ColE1-derived pACKC1, the strain produces the virulence (Vi) antigen. Vi antigen expression is abolished (Vi- phenotype), however, when an IS1 or IS1-like DNA element inserts into the viaB region. To determine the sites of IS1 insertion, pWR127 DNAs extracted from 95 independently isolated Vi- strains were analyzed by digestion with the restriction endonuclease PstI and agarose gel electrophoresis. Ten insertion sites were found distributed non-randomly in an area of about 1.3 kb. Nine Vi+ strains (two Citrobacter, two E. coli, and five Salmonella strains), four of which contain pWR127, were then tested for the presence of IS1 by DNA-DNA hybridization. Of the nine strains, five were stable Vi+ and did not contain IS1. The other four which generated Vi- strains, contained IS1. When pRR134, a plasmid that contains IS1 was transferred into a stable Vi+ Salmonella typhimurium strain carrying pWR127 (OU5140), Vi- strains were produced from which pWR127 derivatives carrying IS1 inserts could be isolated. It appears, therefore, that the presence of an IS1 or IS1-like element in a strain is required for conversion of the Vi+ expression state to the Vi- expression state.
The experiments were performed on 55 rabbits vagotomied, anesthetized with urethane and immobilized with flaxedil. Injection of L-glutamate (L-glu) into the locus coeruleus complex (Lc-Sc) area led to a marked increase in respiratory frequency (RF) and phrenic nerve discharge rate (phr.d) (16 +/- 3.5% and 6.5 +/- 2.5%; P < 0.01 and P < 0.05, respectively), a decrease in inspiratory and expiratory duration, and no obvious change in blood pressure (Bp) was observed. While prazosin (0.5 micrograms/microliters), yohimbin (4 micrograms/microliters) and propranolol (2 micrograms/microliters) were preinjected into the nuclei tractus solitraii (NTS) respectively, the above-mentioned effects of L-glu on respiration was blocked. These results indicate that the excitation of neurons in the Lc-Sc can induce an increase in RF and phr. d and the excitative effect of L-glu on RF was mediated by alpha 1, alpha 2 and beta-receptors in the NTS, while the effect on phr.d was mediated differently.
Agonist challenged aortic prostacyclin production was examined in copper-adequate, -marginal and -deficient rats fed AIN-based diets providing 6.7, 1.7 and 0.8 micrograms Cu/g, respectively. Aortic rings were incubated in Krebs-Henseleit salts, 10 mmol/L HEPES buffer, pH 7.4, 95%:5% O2:CO2, 37 degrees C, and equilibrated for 1 h. Equilibrated rings were challenged with buffer (basal), 273.0 nmol/L thrombin and angiotensin II at 84.6 pmol/L and 846.0 pmol/L. Prostacyclin production, determined at 10 minutes by RIA as 6-keto prostaglandin F1 alpha, in basal and 84.6 pmol/L angiotensin II ring incubations was significantly reduced by 28 to 48% in copper-deficient rats. With thrombin or 846.0 pmol/L angiotensin II prostacyclin production was significantly reduced by 18 to 55% in copper-marginal and copper-deficient rats. Copper-dependent superoxide dismutase activity was significantly depressed by 30 and 57% in aortae of copper-marginal and copper-deficient rats. Lipid peroxidation, estimated by the thiobarbituric acid test, was significantly increased by 85% in copper-deficient rats, with a nonsignificant 40% increase in aortae from copper-marginal rats. The results suggest that the decreases in aortic prostacyclin production in aortae from both copper-deficient and copper-marginal rats are associated, in a dose-dependent manner, with copper-dependent superoxide dismutase depression and increases in aortic lipid peroxidation.
To investigate the effects of dietary protein and polyunsaturated fat levels on tissue lipid peroxidation and antioxidative enzymes, Long-Evans male weanling rats were fed either an 8% lactalbumin diet containing 2% (L2), 5% (L5), 10% (L10), 15% (L15) or 20% (L20) soybean oil or a 20% lactalbumin diet containing 5% (N5) or 20% (N20) soybean oil for 8 weeks. The tissue thiobarbituric acid-reactive substances (TBARS) concentrations of the L2 group were similar to those of the N5 group except in plasma in which they were higher. The L5 group generally showed tissue TBARS concentrations comparable to the N20 group. Gradually increasing the dietary soybean oil level in the low protein diet further increased the tissue TBARS concentrations. The L20 group had significantly higher TBARS in RBC, liver, heart, kidney and muscle than the N20 group. The low protein-fed groups had lower activities of glutathione peroxidase (EC 1.11.1.9), superoxide dismutase (EC 1.15.1.1) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) in liver and catalase (EC 1.11.1.6) in RBC than the N5 group. Compared with the N5 group, the N20 group also showed higher TBARS concentrations and lower activities of certain antioxidative enzymes in some tissues. The antioxidative enzyme activities decreased more drastically with the increasing dietary soybean oil level in the low protein-fed groups than in those fed a normal level of protein. Supplementation of 150 mg/kg of all-rac-alpha-tocopheryl acetate to the L15 diet slightly decreased the TBARS in plasma, heart and liver and restored the depressed activities of RBC superoxide dismutase and catalase. The results indicated that insufficiency of dietary protein aggravates the enhanced production of TBARS and the reduced activities of antioxidant enzyme in rats fed a high soybean oil diet.
Insulin-like growth factor I (IGF-I) is involved in paracrine/autocrine regulation of gonadal steroidogenesis and peptide hormone biosynthesis. This study was designed to determine whether IGF-I alone, or an interaction of IGF-I, is involved in augmenting the actions of luteinizing hormone (LH) and prolactin in controlling relaxin and progesterone secretion from ageing corpora lutea of hysterectomized gilts at days 110, 113 and 116 after oestrus. Luteal tissue slices were incubated for 8 h with IGF-I (0, 50, 300 ng ml-1), LH (0, 100, 1000 ng ml-1), and prolactin (0, 100, 1000 ng ml-1) alone or in combination. Progesterone and relaxin concentrations were determined by radioimmunoassay of spent medium and of homogenates from luteal tissue slices before and after incubation. Porcine luteal tissue from day 110 had a net output of 25 ng progesterone and 26 ng relaxin in the control and of 65 ng progesterone and 2125 ng relaxin in the combined IGF-I, LH and prolactin treatment mg-1 of luteal tissue, respectively. IGF-I, LH and prolactin alone or in combination significantly increased (P < 0.01) progesterone production by luteal tissue from day 110, but they were partially effective at day 113 and ineffective at day 116. By contrast, the same hormone treatments increased relaxin production by luteal tissue from days 110 and 113. Even at day 116, prolactin alone or with LH or IGF-I continued to stimulate relaxin production. In conclusion, IGF-I augments the ability of prolactin and LH to increase relaxin production by ageing corpora lutea; however, a decrease in progesterone secretion and an increase in relaxin secretion at day 113 indicate that different mechanisms control progesterone and relaxin secretion in pigs.
Tuberculosis of the middle ear is rare; associated meningitis is even more unusual. This report contains our experience with a one and a half year old psychomotor retarded boy. He had a poor healing left postauricular abscess four months prior to admission. Also noted was postprandial vomiting and left sided involuntary movement. On admission spinal tapping was done. Results showed leukocytosis, with lymphocytes being predominant, as well as high protein and low glucose levels. A cranial CT revealed left mastoiditis, hydrocephalus, basal cistern abnormal enhancement and a prominent posterior fossa postcerebellar CSF space. Left radical mastoidectomy was performed. A biopsy showed caseous necrosis surrounded by epitheloid and Langhan's giant cells. He also received a ventriculoperitoneal shunt. The gastric and CSF were both positive for tuberculous culture.
An implantable drug delivery system will play an important role for patients who need chemotherapy or prolonged total parenteral nutrition in the future. We implanted 72 injection capsules in 74 patients who were undergoing aggressive chemotherapy or total parenteral nutrition programs. These capsules were implanted in different positions, including central access in 67 cases, peritoneal cavity in 1, hepatic artery in 2, portal vein in 1 and intrathecal space in 1. The actual median functional survival of the injection capsules was 12.3 months (range, 2 months to 4 years). The total cumulative puncture numbers were 1651 (range, 5 to 153; median 23). There was no unsuccessful instance in infusion or injection. To date, 27 patients still survive. The complication rate was about 7% including 1 sepsis, 1 skin infection, 1 catheter thrombosis, 1 dislodgement of reservoir and 1 catheter-reservoir disengagement, which were all corrected by a secondary operation without mortality. Patency of the Port-A-Cath system was maintained using a regular flushing schedule once every 30 days. The results of this study suggest that the implantable drug delivery system can provide a safe and reliable method for venous access or even arterious access in patients requiring intermittent or prolonged intravenous therapy.
Experiments were performed on 55 urethane anesthetized and flaxedil immobilized rabbits under artificial respiration. Injection of L-Glutamate into the locus coeruleus area led to a marked augmentation of respiration. This effect of L-Glutamate could be significantly attenuated or reversed by a previous injection of prazosin, yohimbine and propranolol into the NTS area. These results indicate that the neurons in the locus coeruleus are involved in the regulation of the respiration as a result of mediation by alpha and beta receptors in the NTS area.
There are two types of cDNA clones (designated alpha 1 and alpha 2) encoding the alpha subunit of carp gonadotropin. These two cDNAs are derived from different genes and encode proteins that differ by seven amino acid residues (three in the signal peptide and four in the mature polypeptide). Expression of these two cDNAs in insect cells by recombinant baculovirus revealed that the alpha 1 subunit, after noncovalent association with the beta subunit, has the same potency as the native alpha subunit purified from the pituitary. In contrast, the alpha 2 subunit can associate with the beta subunit, but only to form an inactive gonadotropin. Competition of the alpha 2 subunit with the alpha 1 subunit for association with the beta subunit decreases the gonadotropin activity of the alpha/beta complex. In addition, both alpha 1 and alpha 2 subunits are secreted into the culture medium by insect cells and have an apparent molecular mass approximately 5 kDa higher than that of the native alpha subunit. These results indicate that the insect cell-derived alpha 1 subunit is biologically active and that those four amino acid changes in the mature of alpha 2 protein affect the biological activity and thus provide valuable clues for the study of the structure-function relationship of the alpha subunit of glycoprotein hormones.
A chromosomal locus of Salmonella typhimurium which complements S. typhimurium asr (anaerobic sulfite reduction) mutants and confers on Escherichia coli the ability to produce hydrogen sulfide from sulfite was recently cloned (C. J. Huang and E. L. Barrett, J. Bacteriol. 172:4100-4102, 1990). The DNA sequence and the transcription start site have been determined. Analysis of the sequence and gene products revealed a functional operon containing three genes which have been designated asrA, asrB, and asrC, encoding peptides of 40, 31, and 37 kDa, respectively. The predicted amino acid sequences of both asrA and asrC contained arrangements of cysteines characteristic of [4Fe-4S] ferredoxins. The sequence of asrB contained a typical nucleotide-binding region. The sequence of asrC contained, in addition to the ferredoxinlike cysteine clusters, two other cysteine clusters closely resembling the proposed siroheme-binding site in biosynthetic sulfite reductase. Expression of lacZ fused to the asr promoter was repressed by oxygen and induced by sulfite. Analysis of promoter deletions revealed a region specific for sulfite regulation and a second region required for anaerobic expression. Computer-assisted DNA sequence analysis revealed a site just upstream of the first open reading frame which had significant homology to the FNR protein-binding site of E. coli NADH-linked nitrite reductase. However, asr expression by the fusion plasmid was not affected by site-specific mutations within the apparent FNR-binding site.
Although a prominent role of conceptuses in the hormonal control of normal parturition in the pig is well founded, mechanisms are entrained that cause a timed relaxin release and an abrupt decrease in progesterone secretion in the complete absence of the uterus. This study focused on the steroidogenic and peptide hormone secretory capacities of aging porcine luteal cells in culture on specific days during a narrow window (days 110-116) when abrupt shifts occur in their function. Dispersed luteal cells (3 x 10(5) cells/well) from hysterectomized and pregnant gilts on days 110, 113, and 116 after estrus were cultured for 24 h with porcine (p) LH, pPRL, prostaglandin E1 (PGE1), PGE2, and (Bu)2cAMP. Progesterone and relaxin concentrations in cells preceding culture and in the spent medium were quantified by RIA. Progesterone in cells before culture was less (P less than 0.05) than that released into the medium, while relaxin levels were greater (P less than 0.05) than those in the medium. Relaxin stored in luteal cells of hysterectomized gilts was consistently greater (P less than 0.01) than that during the same days of late pregnancy; however, progesterone was greater (P less than 0.01) in hysterectomized compared with pregnant gilts only on day 116. Relaxin release was greater (P less than 0.01) in hysterectomized compared with pregnant gilts on days 113 and 116, whereas progesterone was greater (P less than 0.05) on days 110 and 116 in hysterectomized compared with pregnant animals. pLH, pPRL, and (Bu)2cAMP increased (P less than 0.05) relaxin secretion in hysterectomized gilts on days 110, 113, and 116, but only on day 110 in pregnant animals. These hormones consistently increased (P less than 0.05) progesterone release only on day 110 in both groups of gilts. PGE1 increased (P less than 0.01) relaxin release in hysterectomized, but not pregnant, gilts; it was not effective in altering progesterone in either group. PGE2 increased the release of both hormones on day 113 in both groups. The percentage of large cells (i.e. greater than 20 microns in diameter) was consistently greater (P less than 0.01) on days 110-116 in hysterectomized compared with pregnant gilts. Both luteal cell relaxin concentrations and the population of electron-dense granules decreased from days 110-116 in pregnant, but not in hysterectomized, gilts; luteal cells from postpartum animals were nearly depleted of granules, and empty vesicles were prominent. The secretory response of the cells to tropic hormone stimulation is preprogrammed from the previous estrus that occurred more than 110 days previously.(ABSTRACT TRUNCATED AT 400 WORDS)
Porcine corpora lutea produce progesterone and relaxin during pregnancy and after hysterectomy. Peak amounts of relaxin are released into peripheral blood in both pregnant and hysterectomized animals on about day 113 (estrus = day 0 and term = 114), and this release coincides with an abrupt decrease in the progesterone concentration. RU 486, a progesterone receptor antagonist, was used to investigate the effects of interruption of progesterone binding to its receptor on luteal function and gonadotropin secretion of pigs with aging corpora lutea. RU 486 was administered orally to hysterectomized gilts (surgery on day 8) once a day (0800 h) on days 111-115 at two dosages (group 1, 2 mg/kg BW; group 2, 4 mg/kg BW). During 5 days of RU 486 treatment, plasma progesterone concentrations in both treated groups were markedly elevated (32 and 37 ng/ml for groups 1 and 2) compared with 22 ng/ml in the controls (group 3; P less than 0.01). PRL concentrations increased in both groups (9 and 13 ng/ml) and differed significantly from those of the controls (3 ng/ml) (P less than 0.04). RU 486 treatment delayed the time of relaxin peak to days 116.1 and 117.0 in groups 1 and 2 compared with day 114.1 in the controls (P less than 0.01). Pregnant gilts received RU 486 orally once a day (0800 h) at 4 mg/kg BW beginning on day 111 until parturition occurred. Parturition was induced on day 112.7 after only two RU 486 treatments compared with day 114.7 in the control group (P less than 0.01). Progesterone decreased abruptly from a pretreatment mean of 11 to less than 0.6 ng/ml during the 2 days that RU 486 was given compared with a shift from 12 to 6 ng/ml during the same period in the controls (P less than 0.01). The time of the relaxin peak was advanced to day 112.1 in RU 486-treated gilts compared with day 113.9 in the controls (P less than 0.01). Results from this study provide strong evidence that the antagonistic effect of RU 486 on progesterone receptor results in an abrupt increase in PRL and progesterone secretion in hysterectomized gilts with aging corpora lutea. In marked contrast with hysterectomized animals, the acute luteolytic effects of RU 486 depend on the presence of the uterus and/or conceptuses in the pig. Disruption of the regulatory loop of progesterone secretion by RU 486 alters the ability of corpora lutea to produce and release peak quantities of relaxin.
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A procedure to quantitate picomole amounts of hydroperoxides based on GSSG formation is described. Hydroperoxides are incubated with GSH and glutathione peroxidase, and the GSSG formed is measured by a GSSG-specific glutathione reductase recycling assay. Prior to analysis the remaining GSH is removed with N-ethylmaleimide. N-Ethylmaleimide inhibition of the recycling assay is prevented by alkaline hydrolysis of the N-ethylmaleimide, without GSSG hydrolysis, at pH 11. The method is rapid, 30 min, with a limit of detection of 142 pmol calculated by linear regression analysis. Stoichiometric amounts of GSSG are produced in response to hydroperoxides. An application of the method is shown with air oxidation of arachidonic acid solutions over 4 h at room temperature. The method is sufficiently sensitive to quantitate the low amounts of hydroperoxides present in fresh arachidonic acid samples.
The alpha and beta subunit of silver carp gonadotropin (scGTH-alpha and scGTH-beta) were isolated by high-performance liquid chromatography. Heterogeneity of N-terminal amino acid sequence was observed in scGTH-alpha but not in scGTH-beta. For determining the complete primary structures of scGTH-alpha and scGTH-beta, their cDNAs were cloned. Combining the data of N- and C-terminal sequences determined from proteins and the amino acid sequences deduced from cDNAs, we infer that scGTH-alpha consists of 95 and/or 93 residues and scGTH-beta consists of 115 residues. Both scGTH-alpha and scGTH-beta are glycoprotein. Their carbohydrate content is about 20 g per 100 g protein. The molecular weights of scGTH-alpha and scGTH-beta were calculated to be 12,700 and 15,700 Da, respectively. The amino acid sequences of scGTH-alpha and scGTH-beta are very similar to those of the corresponding subunit of carp GTH, different in only 2 and 4 residues, respectively. In addition, a high extent of homology (70%) was also observed between the alpha subunits of fish and mammalian GTHs. In the case of beta subunit, homology among various species of fish (75 to 98%) is much higher than that between fish and mammal (40%). These data suggest that the alpha subunit is conserved while the beta subunit is diversified during the molecular evolution of vertebrate GTH.
Transposon Tn5 insertions causing anaerobic cysteine auxotrophy were isolated from a Salmonella typhimurium cysI parent (auxotrophic under aerobic but not anaerobic conditions). Insertions in one mutant group appeared to be in cysG. A second group of insertions, designated asr (anaerobic sulfite reduction), were located near map unit 53 on the S. typhimurium chromosome. They did not cause aerobic or anaerobic auxotrophy in a cys1+ background but did prevent dissimilatory sulfite reduction. Plasmids containing asr DNA cloned from wild-type S. typhimurium conferred anaerobic prototrophy and the ability to produce hydrogen sulfide from sulfite on an Escherichia coli cys1 mutant.
Nine boys whose age ranged from 5 days to 3 months with urinary ascites were managed in Beijing Children's Hospital. All of them presented with gradual abdominal distension from birth, 5 had dripping of urine, the 5-day old new born had anuria since birth. In 2 other infants one had cystostomy and the other, ureterostomy before admission. Urinary ascites was confirmed by abdominal paracentesis. Intravenous pyelography (IVP) and Voiding cystourethrography (VCUG) in 7 cases showed bilateral hydroureteronephrosis and dilatation of the posterior urethra consistent with congenital posterior urethral valves. The 40-day old infant who had cystostomy followed subsequently by vesicostomy is still waiting for ablation of the valves. The remaining 6 were managed by 2 stage operation, 5 had vesicostomy first, one; ureterostomy. They had valves ablation either through urethra or bladder at the age of 3 months to 2 years old. Urinary ascites disappeared spontaneously after urinary drainage. Two patients died; one due to dehydration after drainage of the obstructed renal pelvis, the other (in 1977) had no urinary drainage for obstructed urinary tract.