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Biomedical subjects

H Cheng

Publications and source records attributed to H Cheng.

At least 199 records · Page 11Linked to original sources
PubMed1998

The National Diabetic Retinopathy Laser Treatment Audit. II. Proliferative retinopathy.

The National Diabetic Retinopathy Laser Treatment Audit is a prospective survey of laser treatment for diabetic retinopathy throughout the United Kingdom. This paper presents data on 284 patients who were undergoing their first panretinal photocoagulation for proliferative retinopathy during a 2 month period in 1995, describing the demographic features, the level of systematic screening, the sources of referral, and the waiting times. For those cases where proliferative retinopathy was present at the first ophthalmology outpatient visit, the retinopathy was detected as a result of systematic screening in 46.8%, whilst 28.7% presented symptomatically. Of these patients 28.4% waited for more than 12 weeks from referral to the time of laser treatment, but once the patient had been listed for laser treatment this was performed within 8 weeks in 95.3%. The retinopathy features and the type of treatment given are also described. Compared with the DRS and ETDRS recommendations, at least 32.5-40.2% of eyes may be undertreated initially, and for those with high-risk characteristics these figures were at least 30.8-38.5%.

Adolescent↗
PubMed1998

Genotype-phenotype correlations in attenuated adenomatous polyposis coli.

Germ-line mutations of the tumor suppressor APC are implicated in attenuated adenomatous polyposis coli (AAPC), a variant of familial adenomatous polyposis (FAP). AAPC is recognized by the occurrence of <100 colonic adenomas and a later onset of colorectal cancer (age >40 years). The aim of this study was to assess genotype-phenotype correlations in AAPC families. By protein-truncation test (PTT) assay, the entire coding region of the APC gene was screened in affected individuals from 11 AAPC kindreds, and their phenotypic differences were examined. Five novel germ-line APC mutations were identified in seven kindreds. Mutations were located in three different regions of the APC gene: (1) at the 5' end spanning exons 4 and 5, (2) within exon 9, and (3) at the 3' distal end of the gene. Variability in the number of colorectal adenomas was most apparent in individuals with mutations in region 1, and upper-gastrointestinal manifestations were more severe in them. In individuals with mutations in either region 2 or region 3, the average number of adenomas tended to be lower than those in individuals with mutations in region 1, although age at diagnosis was similar. In all AAPC kindreds, a predominance of right-sided colorectal adenomas and rectal polyp sparing was observed. No desmoid tumors were found in these kindreds. Our data suggest that, in AAPC families, the location of the APC mutation may partially predict specific phenotypic expression. This should help in the design of tailored clinical-management protocols in this subset of FAP patients.

Adenomatous Polyposis Coli↗
PubMed1998

Absence of macrophage inflammatory protein-1alpha prevents the development of blinding herpes stromal keratitis.

Prior studies in our laboratory have suggested that the CC chemokine macrophage inflammatory protein-1alpha (MIP-1alpha) may be an important mediator in the blinding ocular inflammation which develops following herpes simplex virus type 1 (HSV-1) infection of the murine cornea. To directly test this hypothesis, MIP-1alpha-deficient (-/-) mice and their wild-type (+/+) counterparts were infected topically on the scarified cornea with 2.5 x 10(5) PFU of HSV-1 strain RE and subsequently graded for corneal opacity. Four weeks postinfection (p.i.), the mean corneal opacity score of -/- mice was 1.1 +/- 0.3 while that of the +/+ mice was 3.7 +/- 0.5. No detectable infiltrating CD4+ T cells were seen histologically at 14 or 21 days p.i. in -/- animals, whereas the mean CD4+ T-cell count per field (36 fields counted) in +/+ hosts was 26 +/- 2 (P < 0.001). In addition, neutrophil counts in the -/- mouse corneas were reduced by >80% in comparison to the wild-type controls. At 2 weeks p.i., no interleukin-2 or gamma interferon could be detected in six of seven -/- mice, whereas both T-cell cytokines were readily demonstrable in +/+ mouse corneas. Also, MIP-2 and monocyte chemoattractant protein-1 protein levels were significantly lower in MIP-1alpha -/- mouse corneas than in +/+ host corneas, suggesting that MIP-1alpha directly, or more likely indirectly, influences the expression of other chemokines. Interestingly, despite the paucity of infiltrating cells, HSV-1 clearance from the eyes of -/- mice was not significantly different from that observed in +/+ hosts. We conclude that MIP-1alpha is not needed to control virus growth in the cornea but is essential for the development of severe stromal keratitis.

Animals↗
PubMed1998

Human immunodeficiency virus type 1 genome activation induced by human T-cell leukemia virus type 1 Tax protein is through cooperation of NF-kappaB and Tat.

For productive replication of human immunodeficiency virus type 1 (HIV-1) in host cells, the viral genome-encoded transactivator Tat and several cellular transcription factors are required for efficient viral gene transcription. However, it remains unclear how the viral genome initiates transcription before Tat is transcribed or when Tat is at suboptimal levels. Here, we utilized the human T-cell leukemia type 1 Tax protein as a molecular tool to investigate the mechanism of viral gene transcription that initiates the early phase of infection of HIV-1. Tax alone does not significantly increase the activity of HIV-1 long terminal repeat (LTR) in T lymphocytes, but it markedly enhanced the replication of an infectious HIV-1 provirus with a truncated nef gene. This enhancement is preferentially mediated by the cooperation of Tax and Tat which is dependent on TAR and duplicated kappaB cis elements of the HIV-1 LTR as well as the NF-kappaB activation domain of Tax. Furthermore, phorbol myristate acetate and membrane-targeted HIV-1 Nef also enhanced the LTR activity in the presence of Tat in the TAR- and kappaB cis element-dependent manner. These data suggest that activated NF-kappaB can functionally interact with a suboptimal amount of Tat and the HIV-1 LTR for efficient initiation of viral gene transcription.

Binding Sites↗
PubMed1998

Constitutive expression of cyclooxygenase-2 in rat vas deferens.

Prostaglandins, lipoid substances discovered in human semen as modulators of uterine muscle contractility, are known to play significant roles in virtually all mammalian organ systems, but their male reproductive functions are unclear. Cyclooxygenase, the rate-limiting enzyme in prostaglandin synthesis, occurs in two isoforms distinguished on the basis of constitutive (COX-1) or inducible (COX-2) expression patterns in mammalian tissues. However, in the adult rat male reproductive system, immunohistochemistry and Western and Northern analysis showed that COX-2 is the predominant isoform and is heavily localized to the epithelium of the distal vas deferens, where constitutive expression is manyfold greater than in any other organs of the body. COX-2 is not detected in the proximal one-half of the vas nor in the testis, epididymis, seminal vesicles, or prostate. Elimination of luminal sperm by vasectomy does not affect COX-2 levels, whereas castration severely depletes COX-2 and androgen replacement after castration restores COX-2, indicating that COX-2 expression in the vas is androgen dependent. Because the distal vas also comprises an extensive submucosal venous plexus connected to the penile corpora cavernosa, prostaglandins from the vas may play a role in erection.

Animals↗
PubMed1998

Truncated dipeptidyl peptidase IV is a potent anti-adhesion and anti-metastasis peptide for rat breast cancer cells.

A novel adhesion receptor/ligand pair was shown recently to mediate lung vascular arrest and metastasis of rat breast cancer cells. The interacting adhesion molecules are endothelial dipeptidyl peptidase IV (DPP IV) and tumor cell surface-associated, polymeric fibronectin (FN). A truncated DPP IV (DPP IV(31-767): amino acids 31-767) in which the FN-binding site is preserved is shown here to mask the breast cancer cell surface-associated FN complexes, causing a dose-dependent inhibition of adhesion to endothelial DPP IV and impeding lung colony formation by approximately 80%. Since surface accumulation of FN is chiefly occurring during dissemination in the blood and since many cancer cell types have surface receptors by which they may initiate FN accumulation on their surfaces, the present anti-metastatic treatment modality may extend its efficacy farther than appreciated by this study.

Adenocarcinoma↗
PubMed1998

The c-Fes family of protein-tyrosine kinases.

The human c-fes protooncogene encodes a protein-tyrosine kinase (c-Fes) distinct from c-Src, c-Abl and other nonreceptor tyrosine kinases. Although originally identified as the cellular homolog of several transforming retroviral oncoproteins, Fes was later found to exhibit strong expression in myeloid hematopoietic cells and to play a direct role in their differentiation. Recent work has shown that Fes exhibits a more widespread expression pattern in both developing and adult tissues, suggesting a general physiological function for this kinase and its closely related homolog, Fer. This review highlights the unique aspects of Fes structure, regulation, and function that set it apart from other tyrosine kinase families.

Animals↗
PubMed1998

[Monitoring and management on the mandatory reporting system of infectious diseases in Jiangxi provincial].

From 1994 to 1997, we had continuously and actively conducted surveillance on reports of legal infectious diseases and administrative performance of hospitals in this aspect. The proportion from outpatient clinic in the whole province under supervision had sucessively increased yearly. It suggested that the implementation of "report on the first visit" regulation had been improved; the number of hospitals with "no information on epidemic desease" had decreased, and the number of months with no information on epidemic disease had also decreased. All the results showed that the surveillance and monitoring on the infectious desease reporting system and administrative performance of hospitals was an effective practice.

China↗
PubMed1998

Protective effect of the angiotensin-converting enzyme inhibitor perindopril on diabetic glomerulopathy in streptozotocin-induced diabetic rats.

OBJECTIVES: To evaluate the protective effect of the angiotensin-converting enzyme inhibitor perindopril on diabetic glomerulopathy in rats with experimentally induced diabetes and explore its possible mechanisms. METHODS: Ninety-two adult male Wistar rats were randomly allocated into diabetes mellitus (DM), diabetes mellitus + perindopril (DMP) and control (C) groups. According to the duration of diabetes or observation (1, 3, 6 months), each group was randomly subdivided into DM1, DM3, DM6; DMP1, DMP3, DMP6; and C1, C3, C6 groups. Diabetes was induced by intraperitoneal injection of streptozotocin. The rats in the DMP groups received perindopril 1 mg.kg-1.d-1, through gastric intubation. Urinary protein excretion rate was determined by the method of Coomassie brilliant blue. Plasma renin activity, renal tissue renin activity, and plasma and renal tissue angiotensin II concentration were assayed by radioimmunoassay (RIA). Renal tissue total RNA was extracted by the Chomezymskis AGPC method. Renal angiotensinogen mRNA expression level was assessed by slot blot hybridization using a full length rat angiotensinogen cDNA probe labelled with 32P-dCTP and a random primer. RESULTS: There was increased activity of the renin angiotensin system in diabetic rats. Perindopril decreased proteinuria and delayed the progression of glomerular basement membrane thickening. However, it did not reduce the expansion of the mesangial matrix (P < 0.05). Renin activity increased and angiotensin II concentration decreased significantly in both plasma and renal tissue in diabetes + perindopril groups (P < 0.05). CONCLUSIONS: Perindopril may help prevent the progression of diabetic glomerulopathy, and the inhibition of renin angiotensin system activity may be a mechanism for this action.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

[Long-term result of free forearm skin flap for repair of soft tissue defects of the oral and maxillofacial regions].

To evaluate the long-term result of free forearm skin flap in the repair of soft tissue defects of the oral and maxillofacial regions, 26 cases which had received radical resection of maxillofacial tumors were follow-up for 4.5 years. Twenty cases, having complete data were analyzed. In this series, There were 8 males and 12 females, with ages ranged from 40 to 69 years old. The size of the flaps ranged from 4 cm x 5 cm-6 cm x 13 cm. The radial artery and the cephalic vein were used as the donor vessels, and the maxillary artery, superior thyroid artery, external jugular vein and the anterior jugular vein were prepared as the recipient vessels. According to the shape, colour, temperature, sensation, mucosoid degree of the flap, the blood supply and function of hand and the configuration of the forearm, the overall results of the recepient regions in 20 cases were all satisfactory and the overall results of 16 cases donor regions were satifactory in 16 cases. The results were poor in 4 cases. The conclusion were: 1. Free forearm skin flap was worth trying in the repair of soft tissue defects of oral region; 2. The radial artery need not to be reconstructed because of the abandant vascular net-work in the upper limb and 3. The residual scar on the forearm was the main shortcoming, but most of the patients could tolerate it because of the obvious advantages received from the operation.

Adult↗
PubMed1998

[Effects of nitrogen form on American ginseng leaf blight].

The effects of two nitrogen forms(NO3-N and NH4-N) on American ginseng leaf blight were studied using sand culture method. The results indicated that American ginseng leaf blight caused by Alternaria panax was reduced with NO3-N, while increased with NH4-N.

Alternaria↗
PubMed1998

Contribution of the absence of aspartic acid at position 57 of the HLA-DQ beta chain to predisposition to insulin-dependent diabetes mellitus in a southern Chinese population.

OBJECTIVE: To investigate the association of the absence or presence of aspartic acid at position 57 of the HLA-DQ beta chain (NA or A) with susceptibility or resistance to insulin-dependent diabetes mellitus (IDDM) in a Southern Chinese population. METHODS: Sixty-nine IDDM patients and 47 healthy controls in a Southern Chinese population were HLA-DQB1 genotyped by one-step sequence specific polymerase chain reaction (ssPCR). RESULTS: The frequencies of NA and A were 64.5% and 35.5% in the IDDM patients, and 40.4% and 59.6% in the control subjects respectively (RR for NA was 2.68, P < 0.01). The frequencies of NA/NA, NA/A and A/A phenotypes were 47.8%, 33.3% and 18.8% in the IDDM patients, and 31.9%, 17.0% and 51.1% in the controls respectively (P < 0.01). The frequency of A/A phenotype was significantly lower in the IDDM patients than in the control subjects (RR = 0.22, P < 0.01). DQB1* 0302 and DQB1* 0201 were more frequent in IDDM patients than in control subjects. The younger the age of IDDM onset, the higher the allele frequencies of DQB1* 0201 and DQB1* 0302. CONCLUSION: The present study suggests that the NA confers the susceptibility to IDDM, while the A confers the protection against IDDM in patients of Southern Chinese origin. These associations are more clearcut in childhood-onset IDDM patients.

Adolescent↗
PubMed1998

[Production of allochtonic formations in callus cells of Salvia miltiorrhiza Bge].

OBJECTIVE: To study the effect of hormones content in the medium on of allochtonic formations in the callus from Salvia miltiorrhiza. METHOD: Study the development of allochtonic formations in the callus from explants of Salvia miltiorrhiza cultured on hormones of different content ratios in the medium. RESULT AND CONCLUSION: 2,4-D inhibits the production of water-soluble active principles and KT promotes the production of total tanshinone.

Abietanes↗
PubMed1998

[Application of time-frequency filter of wavelet to single-trail ERP extracting].

A new approach to extracting single-trail event-related potential(ERP) in combination with the correlation analysis has been proposed. This approach, called time-frequency filter, is based on the concept that multiresolution wavelet transforms. At first, an investigation of the properties in time and frequency domain was carried out on the ERP. On the basis of the findings, the time-frequency filter of wavelet was designed and used for single-trail ERP extracting. The results and related discussion are presented in this paper.

Adult↗
PubMed1998

[The construction of Alcaligenes faecalis ntrC-lacZ fusion gene and its expression during association with rice roots].

A broad host range vector pLA2917 containing ntrC gene or ntrC-lacZ fusion were constructed, namely pLAC1 and pLAC2. The plasmids pLAC1 and pLAC2 were introduced into A. faecalis wild type strain A1501 by conjugation, subsequently to abtain A15C1 and A15C2. The expression and regulation of ntrC gene of A. faecalis associated with rice roots was investigated under the condition of the associative nitrogen fixation using X-Gal decoration method, micrograph and ntrC partially deletion mutant. The blue precipitation was strongly existed in parenchyma cells as well as in the lateral root primordial. It showed that ntrC gene could express at much higher level in these sites. In the presence of ammonia, the number of multi-copy ntrC conjugatants colonized on surface of rice roots is higher than that of wild type A1501, and the colonization of ntrC mutant is weakest among these three strains. This provided an evidence that ntrC gene might be involved in procedure of colonization of A. faecalis to rice roots.

Alcaligenes↗
PubMed1998

[The effect of pressure on the morphology of superior mesenteric vein in rabbits].

The effect of pressure on the morphology of the superior mesenteric vein of rabbits (SMV) was researched with the method of constant pressure fixation. The results indicate the morphology of SMV is similar to human umbilical cord vein. It looks like the structure of femoral artery of vein in many ways. Under constant pressure fixation (4 kPa), the internal elastic membrane of SMV is straightened, and the wall of SMV becomes thin, with its media thinning from 51.680 microns to 32.3260 microns. The long diameter of nucleus of the smooth muscles decreases from 1.9146 microns to 3.4980 microns, the short diameter of nucleus of the smooth muscles becomes from 0.7884 micron to 0.5228 micron. The direction of the tension on the smooth muscles is mainly longitudinal.

Animals↗
PubMed1998

[The effect of activity of smooth muscles on the relationship of circumferential stress-strain of superior mesenteric veins in rabbits].

The superior mesenteric veins (SMV) of 14 rabbits were divided into two groups for experiment of inflation pressure, namely the normal group and the inactivated smooth muscles group. The results showed that the relationship of circumferential stress-strain of SMV could be expressed with the exponential equation. Constant X2 is effected by the active condition of smooth muscles. The difference of the material constant X2 between the two groups was statistically significant (P < 0.05), but the difference of the material constant X1 between the two groups was not statistically significant (P > 0.05). These suggest that X2 is the parameter concerning the activity of smooth muscles.

Animals↗