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Biomedical subjects

C C Chou

Publications and source records attributed to C C Chou.

At least 109 records · Page 6Linked to original sources
PubMed1995

Microdeletion of chromosomal region 22q11 in DiGeorge syndrome: report of a case.

This is a case of chromosome 22q11 deletion in a female Chinese infant with DiGeorge syndrome. Cardiac anomalies included a type B interrupted aortic arch from the descending aorta with an aberrant right subclavian artery, a large ventricular septal defect, a small atrial septal defect and a large patent ductus arteriosus. This patient was small for her age and showed symptoms of feeding difficulties, chronic diarrhea and facial dysmorphisms (frontal bossing, hypertelorism, posteriorly rotated ears, fish-like mouth and micrognathia). Chest film did not reveal a thymic shadow. Immunological studies showed a low T-cell ratio (20%). Laboratory tests revealed a borderline low serum calcium level. The karyotype, 46, XX, del(22) (q11.21-->q11.23), was observed by high-resolution banding techniques. Cardiac surgery was successfully performed at 1 month of age. Operative findings confirmed aplasia of the thymus and the above complex cardiac anomalies. To our knowledge, this is the first Taiwanese case of DiGeorge syndrome proven immunologically and cytogenetically.

Chromosome Deletion↗
PubMed1995

Evaluation of screening kits for the detection of anti-human immunodeficiency virus type 1 and 2 (HIV-1/2) antibodies.

HIV-1/HIV-2 3rd generation (Abbott), Wellcozyme HIV 1 + 2 (Murex), Enzygnost Anti-HIV 1/-HIV 2 (Behring), and Genelavia Mixt (Sanofi Diagnostics Pasteur) are currently registered by authorities as enzyme immunoassays (EIAs) for detecting HIV-1/2 infection. The present study dissects these reagents by means of the major antigenic components, assay principles and their actual performance. The performances have been evaluated by their test results in international panels of seroconversion, mixed titer performance and HIV-1/2 combination, respectively. Those EIA tests were further used to examine 26 potentially false-reacting samples, serial diluted sera prepared from two confirmed positive specimens and 720 specimens obtained from random blood donors in the Taipei Blood Center, Chinese Blood Services Foundation (CBSF). The results showed that, although standard sera of the mixed titer, performance and HIV-1/2 combination rows could not distinguish significantly among various EIAs, the seroconverting samples clearly showed their differences. The differences, as calculated by using 3 of 4 seroconverting sera, was a backward window period ranging from 19 to 23 days as compared to the detection of HIV-1 antigens. Together, these studies strongly suggest that assays which are capable of detecting HIV-specific IgM and IgG antibodies have a shorter seroconversion window. Furthermore, the HIV-2 antigen seems to be crucial for successful detection of anti-HIV-2. Finally, testing anti-HIV-1/2 in the routine screenings is expected not to increase the exclusion rate of blood units currently acquired from the examination of anti-HIV-1. Consequently, with both HIV-1/2 specificities and the ability of early detection, IgM/IgG-captured EIAs may represent a better screening method than assays based solely on the detection of HIV-specific IgG.

Blood Donors↗
PubMed1994

CD8+ lymphocyte activation at human immunodeficiency virus type 1 seroconversion: development of HLA-DR+ CD38- CD8+ cells is associated with subsequent stable CD4+ cell levels. The Multicenter AIDS Cohort Study Group.

Subsets of activated CD8+ lymphocytes defined by membrane expression of the activation antigens HLA-DR and CD38 were counted by three-color flow cytometry in homosexual men who subsequently became seropositive for human immunodeficiency virus type 1 (HIV). Profound CD8+ cell activation was seen in all subjects at seroconversion and 6 and 12 months later. The HLA-DR+ CD38+ CD8+ cell population, which has potent direct HIV cytotoxic T cell activity, was markedly elevated at seroconversion in all subjects. In some men, these levels remained elevated throughout the first year of infection. During the next 5 years, these men had stable CD4+ cell levels, whereas the others did not. Long-term survivors (seropositive for 9 years, > 800 CD4+ cells/mm3) also had elevated levels of this subset, despite few other activated CD8+ cells. Thus, selective elevation of HLA-DR+ CD38- CD8+ cells was a marker of subsequent stable HIV disease.

ADP-ribosyl Cyclase↗
PubMed1994

L-NAME, nitric oxide and jejunal motility, blood flow and oxygen uptake in dogs.

1. The effects of the inhibitor of nitric oxide (NO) synthesis, NG-nitro-L-arginine methyl ester (L-NAME), on systemic arterial blood pressure and jejunal motility, blood flow, and oxygen uptake have been investigated in anaesthetized dogs. 2. L-NAME (cumulative doses of 0.1-20 mg kg-1, i.v.) dose-dependently increased blood pressure and jejunal motility and decreased heart rate. The maximal response of these three variables occurred at doses, 3, 10 and 10 mg kg-1, respectively. L-NAME (cumulative doses of 0.5-5 mg kg-1) also dose-dependently induced jejunal vasoconstriction. The jejunal vascular resistance returned to control values as the cumulative doses reached 10 and 20 mg kg-1, which corresponded to the maximal increase in jejunal motility. 3. A single intravenous injection of L-NAME (10 mg kg-1) produced a prompt increase in blood pressure, which lasted for at least 50 min. 4. L-NAME (10 mg kg-1) produced a progressive rise in jejunal motility reaching its maximum (47 +/- 6 mmHg) 15 min after the administration, and lasting for 40-50 min. Both the basal lumen pressure and the amplitude of rhythmic contractions increased during this period. 5. L-NAME (10 mg kg-1) produced a triphasic change in jejunal vascular resistance and blood flow measured by timed collection of venous outflow. The blood flow decreased initially (-43% at 5 min), increased (+35%) and returned to control value between 15 and 35 min, then decreased (-35%) 40-50 min post-infusion. Jejunal vascular resistance reflected the blood flow response (+88% at both 5 and 50 min). The time during which the reversal of the vasoconstriction occurred (15-35 min) corresponded to the time of marked increase in motility, and was accompanied by a significant increase in jejunal oxygen uptake (+ 18%).6. The L-NAME-induced increase in motility was prevented by L-arginine (1 g kg-1, i.v.) but not by D-arginine pretreatment. The interim (15-35 min) changes in jejunal blood flow, vascular resistance and oxygen uptake were also prevented by L-arginine pretreatment.7. L-Arginine pretreatment attenuated L-NAME-induced hypertension for 5 min.8. The L-NAME-induced increases in jejunal vascular resistance and motility were inhibited by either local intra-arterial infusion of L-arginine (32 mM local arterial blood concentration) or topical application of 2 MicroM nitroglycerin. Infusion of D-arginine (32 mM local arterial blood concentration) had no such effect.9. The L-NAME-induced increase in blood pressure was not the mechanism by which jejunal motility was increased, because similar increases in blood pressure by mefenamate (10 mg kg-1, i.v.) had no such effect.10. Thus, inhibition of nitric oxide synthesis by L-NAME increased jejunal motility and vascular resistance and the marked increase in motility can abolish or reverse the vasoconstriction. Endogenous nitric oxide may play a role in regulating motility and blood flow in the resting canine jejunum.

Animals↗
PubMed1994

Phenotypically defined memory CD4+ cells are not selectively decreased in chronic HIV disease.

Simultaneous measurements of phenotypically defined memory CD4+ cells and in vitro proliferation to three recall antigens (Ags; tetanus toxoid, influenza, and Candida albicans) were performed in 53 HIV-seropositive subjects and 39 HIV-seronegative controls. The results indicate that the low proliferative responses to recall Ags of those who were HIV infected could be partly, but not fully, explained by a decrease of phenotypically defined memory CD4+ cells. This is, to our knowledge, the first report of experiments that simultaneously measured memory CD4+ cell numbers and function and then examined whether the low responses observed in seropositive subjects could be explained by low numbers of phenotypically defined memory CD4+ cells. A central finding of the study, which argues against prevailing dogma, was that within the CD4+ lymphocyte population, the proportion of cells displaying the memory phenotype was not selectively decreased in HIV-seropositive subjects as compared with the proportion of these cells in seronegative homosexual controls. An entirely new finding of the study was that AIDS patients, many of whom were unresponsive to all three recall Ags tested, actually had a significant increase in the proportion of CD4+ cells with the memory phenotype, and this fraction approached 100% in subjects with CD4+ cell numbers that were near zero. A final observation of the study, possible because some patients were on zidovudine (ZDV), was that there was no evidence that ZDV treatment led to an increased proliferative response to recall Ags in vivo. An in vitro study also found no effect of ZDV, dideoxycytidine (ddC), or azido-dideoxyuridine (AZU) on proliferative responses to recall Ags.

CD4-Positive T-Lymphocytes↗
PubMed1994

Improvement of penicillin G acylase production by using pac gene clone.

The penicillin G acylase gene (pac gene) from Escherichia coli ATCC 9637 has been isolated. It conferred the production of penicillin G acylase upon E. coli HB101 and other enteric bacilli. Restriction enzyme analysis and subcloning studies reveal that the gene is contained within a 2.3 kb HindIII-SmaI DNA fragment. In vitro protein synthesis study suggests a gene product of approximately 90 kDa. By using the genetically engineered bacteria which harbor a novel recombinant plasmid (pGL5) bearing a constitutively expressible pac gene, a 20-fold increased production yield of penicillin G acylase activity was obtained as compared with that produced by the original strain, E. coli ATCC 9637.

Bacterial Proteins↗
PubMed1993

Characterization of interleukin-10 receptors on human and mouse cells.

Human interleukin (IL)-10 is a pleiotropic cytokine acting on a variety of immune cells. Here we show that the protein can be enzymatically iodinated to high specific radioactivity with retention of biological activity. The radiolabeled ligand binds specifically to its receptor in several mouse and human cell lines, notably human B-lymphoma line JY and mouse mast cell line MC/9. Human IL-10 apparently binds as a dimer to a single class of receptor in both the JY and MC/9 cell lines with a Kd in the 50-200 pM range. Interestingly, mouse IL-10 was capable of blocking binding of human IL-10 to mouse but not human cells. There appears to be at most only a few hundred IL-10 receptors/cell for both mouse and human cell lines examined. Chemical cross-linking of the radioiodinated hIL-10 to JY and MC/9 cells revealed a common protein complex with an apparent molecular mass of about 97 kDa. Additional high molecular weight complexes were detected with JY but not MC/9 cells.

Animals↗
PubMed1993

Molecular cloning and sequence analysis of the monkey and human tissue kallikrein genes.

Cynomolgus monkey renal kallikrein cDNA and genomic human tissue kallikrein gene were cloned. The monkey gene encodes a 257 amino acid (aa) preprokallikrein and exhibits 95% and 92% homology to the human at nucleotide (nt) and aa level, respectively. The monkey gene encodes a 233-aa mature kallikrein versus a 238-aa in human. The human kallikrein gene and urinary kallikrein both contain a Lys-162 instead of the reported Glu-162. Human, monkey and rat renal/pancreatic kallikrein genes evolve with a N-glycosylation containing domain (aa 81-87) which is absent in porcine and is non-glycosylable in mice. Only human kallikrein evolves with an additional Thr-108 and with a N-glycosylation site at aa-141.

Amino Acid Sequence↗
PubMed1993

Circulating HIV-specific CD8+ cytotoxic T cells express CD38 and HLA-DR antigens.

CD38, a molecule with multilineage distribution but unknown function, and the MHC class II molecule HLA-DR (DR) have markedly elevated levels of expression on CD8+ cells of HIV-infected people. This study investigated the expression of CD38 and DR Ag on circulating HIV-specific CD8+ CTL in HIV-seropositive subjects. Purified CD8+ lymphocytes from 22 participants in the University of California at Los Angeles Multicenter AIDS Cohort Study were screened for CTL activity against autologous EBV-immortalized lymphoblast targets infected with vaccinia vectors that carried HIVIIIB gag, pol, and env genes. Sixty-seven percent (14 of 21), 64% (14 of 22), and 9% (2 of 22), respectively, of the subjects had HIV-specific CD8+ CTL activity against gag, pol, and env proteins. CD8+ cells from 11 of the subjects who had high CTL activity were then FACS-separated using three-color immunofluorescence sorting. Circulating DR-CD38- CD8+ cells had little activity. Highly purified DR+CD38+ CD8+ cells had higher HIV-specific CTL activity than other CD8+ cells. DR+CD38- or DR-CD38+ CD8+ cells also mediated significant activity, but only about half as much on a per cell basis as DR+CD38+ CD8+ cells. This is the first report that the CD38 molecule is expressed in vivo on Ag-specific CD8+ CTL, and confirms previous reports that DR is expressed on these cells. Both asymptomatic HIV-seropositive subjects (144 +/- 132/mm3) and AIDS patients (253 +/- 178/mm3) had markedly elevated levels of DR+CD38+ CD8+ cells compared with the levels in HIV-seronegative controls (7 +/- 3/mm3). However, the level of anti-HIV CTL activity was not correlated with the level of DR+CD38+ CD8+ cells, indicating that enumeration of this lymphocyte population by flow cytometry most likely will not be a useful surrogate for measuring functional CTL activity. Low levels of HIV-specific CTL activity, especially against gag, were correlated with lower CD4+ cells numbers, suggesting that the loss of CD8+ T cell cytotoxic activity against HIV that has been reported to occur with advancing HIV disease progression may reflect in part the extent of CD4+ cell immunodeficiency in HIV-infected subjects.

ADP-ribosyl Cyclase↗
PubMed1993

High-level expression of antibody-plasminogen activator fusion proteins in hybridoma cells.

We show that the mouse gamma 2b heavy chain or human beta-globin 3' untranslated region can greatly enhance protein expression in myeloma cells transfected by genes coding for antibody-plasminogen activator fusion proteins. Expression plasmids were constructed containing a cloned genomic heavy chain variable region from fibrin-specific monoclonal antibody 59D8, a cloned genomic constant region of the mouse gamma 2b heavy chain, and DNA sequence coding for either tissue-type plasminogen activator (tPA) or a segment of urokinase (UK) and their respective 3' untranslated sequences. Cell lines transfected with these constructs, pSVtPA (tPA) and pSVUKG(UK), produced extremely low levels of mRNA and protein (0.008-0.06 micrograms/ml) in comparison with the parental 59D8 myeloma cell line (7.6-10 micrograms/ml). In vitro nuclear run-off analysis indicated that the low steady-state levels of mRNA encoded by pSVUKG(UK) did not result from a lower rate of transcription of the transfected gene (relative to the rate of transcription of the endogenous heavy chain gene in the 59D8 parent cells). In an attempt to increase protein secretion, we assembled the expression plasmids pSVtPA(Ig), pSVUKG(Ig), and pSVUKG(beta), in which the 3' untranslated region of the mouse gamma 2b heavy chain or human beta-globin gene was substituted for the 3' untranslated region of the plasminogen activator gene. Analysis of supernatant media from cell lines transfected with these constructs showed an increase in recombinant protein secretion of 68 to 100 fold in comparison with that from cell lines transfected with pSVtPA(tPA) or pSVUKG(UK).

Amino Acid Sequence↗
PubMed1993

Protection from ultraviolet irradiation by melanin of mosquitocidal activity of Bacillus thuringiensis var. israelensis.

A process for production, isolation, and purification of melanin produced by the fermentation of Streptomyces lividans 66 harboring a recombinant plasmid pIJ702-bearing tyrosinase gene has been developed. The efficacy of melanin in the protection of mosquito larvacidal activity of Bacillus thuringiensis var. israelensis against uv light has been studied. Results obtained by the live cell counts and the bioassay of residual mosquitocidal activity of B. thuringiensis var. israelensis after exposure to uv radiation showed that melanin is an excellent photoprotective agent.

Aedes↗
PubMed1993

Differences in vascular response to thromboxane between intestinal mucosa and muscularis.

The effects of a thromboxane A2 (TxA2)-endoperoxide analogue, U-44069 (0.16 micrograms/min. i.a.) on blood flows to the total wall, the mucosal (= mucosa+submucosa), and muscularis (= muscularis+serosa) layers of the canine jejunum, were determined utilizing radiolabelled microspheres (diam = 13.75 microns). U-44069 significantly decreased total (-64 +/- 5%), mucosal (-67 +/- 5%), and muscularis (-53 +/- 6%) blood flows in the natural flow preparation. In the constant flow preparation, U-44069 increased jejunal vascular resistance from 2.02 +/- 0.27 to 4.6 +/- 0.65 mmHg/ml/min/100g and increased mucosal and muscularis vascular resistance by 3.5-fold and 1.5-fold, respectively. As a result, it decreased mucosal blood flow (-19 +/- 5%), but increased muscularis blood flow (+52 +/- 10%). The magnitude of U-44069-induced percent change in mucosal blood flow was significantly different from that of the muscularis. Furthermore, U-44069 significantly redistributed the total jejunal blood flow in favor of the muscularis in both natural and constant flow preparations. Intra-arterial administration of a TxA2 receptor antagonist, SQ-29548 (2.0 micrograms i.a.) reversed all of the above U-44069-induced blood flow changes to control values. Our study indicates that TxA2 produces a significantly greater vasoconstriction in the mucosa than in the muscularis of the canine jejunum. This differential action of TxA2 may have some physiological and pathophysiological significance.

Animals↗
PubMed1993

Lupus patients with peripheral vascular thrombosis: the significance of measuring anticardiolipin antibody.

The purpose of this study was to determine the significance of measuring anticardiolipin (ACL) antibodies in Chinese lupus patients with peripheral vascular thrombosis. A total of 252 lupus patients were evaluated prospectively for the presence of peripheral vascular thrombosis in a 3-year period. Tests of ACL antibodies with three isotypes were done serially during follow-up. There were 10 lupus patients with five episodes of arterial thrombosis and seven episodes of venous thrombosis by the evidence of angiographical and/or pathological findings. The ACL antibody status was negative (< 2 standard deviation [SD]), low (2 to 5 SD) and high (> 5 SD) for 43.3%, 22.6%, and 34.1% patients, respectively. Patients with high levels (> 5 SD) of ACL antibodies had a high frequency of peripheral vascular thrombosis than patients with negative levels (> 2 SD) of ACL antibodies (P < .05). It is concluded that serial measurement of ACL antibodies in lupus patients is useful in predicting the occurrence of peripheral vascular thrombosis. Clinicians should be alert to the possibility of such complication in lupus patients with high ACL antibodies levels when visiting the emergency service.

Adolescent↗
PubMed1992

Microtox EC50 values for drinking water by-products produced by ozonolysis.

The aim was to determine the Microtox EC50 values of some aliphatic aldehydes and carboxylic acids of normal chain length with 1-14 carbon atoms since these compounds have been detected as ozonolysis by-products in drinking water. The aqueous EC50 values decreased with increasing chain length except for formaldehyde and for the C1-C7 acids. At chain lengths above C7, where methanolic saline solutions were utilized to promote solubility, the aldehydes were more toxic than their corresponding carboxylic acids. Below a chain length of C7, the reverse situation applied. More precise and sensitive EC50 values were observed at 15 and 25 min than at 5 min. Both C14 aldehyde and acid as well as palmitoleic acid showed luminescence in methanolic saline solutions. The C14 compounds are known natural substrates for bacterial luciferase, and the present findings confirm this for Photobacterium phosphoreum. The concentrations of the aldehyde and/or carboxylic acid ozonolysis by-products reported in drinking water could not be detected by the Microtox test. This is the first report of Microtox EC50 values for these carboxylic acids and for aldehydes of chain lengths greater than C4.

Aldehydes↗
PubMed1992

Cell-mediated immune response to human immunodeficiency virus (HIV) type 1 in seronegative homosexual men with recent sexual exposure to HIV-1.

Although human immunodeficiency virus (HIV) type 1 infection is efficiently transmitted by sexual intercourse, some individuals whose sexual behavior places them at extremely high risk for infection have nevertheless remained HIV-1-seronegative. An investigation was undertaken to determine whether such individuals have circulating T helper cells that are sensitized to HIV-1. Five very high risk men who had recent sexual exposure to HIV-1 were studied. Peripheral blood mononuclear cells from all 5 produced interleukin (IL)-2 in culture in response to synthetic amphipathic HIV-1 envelope peptides. One of the 5 high-risk men has subsequently seroconverted, while 4 have remained seronegative. All were initially culture-negative, and those who have remained seronegative were also virus-negative by polymerase chain reaction (PCR) testing 10 months after they were first studied. These results demonstrate that a cell-mediated immune response to HIV-1 can be detected in the absence of a humoral immune response in individuals recently exposed to HIV-1. Furthermore, IL-2 production by T cells in response to synthetic peptides may be a more sensitive test for exposure to HIV-1 than antibody, lymphoproliferation, or PCR tests.

Amino Acid Sequence↗
PubMed1992

Role of adenosine in postprandial and reactive hyperemia in canine jejunum.

The role of adenosine in postprandial jejunal hyperemia was investigated by determining the effect of placement of predigested food into the jejunal lumen on blood flow and oxygen consumption before and during intra-arterial infusion of dipyridamole (1.5 microM arterial concn) or adenosine deaminase (9 U/ml arterial concn) in anesthetized dogs. Neither drug significantly altered resting jejunal blood flow and oxygen consumption. Before dipyridamole or deaminase, food placement increased blood flow by 30-36%, 26-42%, and 21-46%, and oxygen consumption by 13-22%, 21-22%, and 26-29%, during 0- to 3-, 4- to 7-, and 8- to 11-min placement periods, respectively. Adenosine deaminase abolished the entire 11-min hyperemia, whereas dipyridamole significantly enhanced the initial 7-min hyperemia (45-49%). Both drugs abolished the initial 7-min food-induced increase in oxygen consumption. Dipyridamole attenuated (14%), whereas deaminase did not alter (28%), the increased oxygen consumption that occurred at 8-11 min. Adenosine deaminase also prevented the food-induced increase in venoarterial adenosine concentration difference. In separate series of experiments, luminal placement of food significantly increased jejunal lymphatic adenosine concentration and release. Also, reactive hyperemia was accompanied by an increase in venous adenosine concentration and release. This study provides further evidence to support the thesis that adenosine plays a role in postprandial and reactive hyperemia in the canine jejunum.

Adenosine↗