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Biomedical subjects

Q Cheng

Publications and source records attributed to Q Cheng.

At least 91 records · Page 5Linked to original sources
PubMed1999

Tissue tropism, transmission and expression of foreign genes in vivo in midgut symbionts of tsetse flies.

Tsetse flies (Diptera: Glossinidae) harbour three different symbiotic organisms in addition to the pathogenic African trypanosomes they transmit. The two gut-associated symbionts (primary, P; secondary, S) are enteric and are nutritionally required, whereas the third microorganism Wolbachia (family Rickettsiaceae) affects the reproductive biology of the insects it infects. The bacteriome-associated P-symbiont (Wigglesworthia glossinidia) displays a concordant phylogeny with its host tsetse species, whereas midgut S-symbionts characterized from distant tsetse have identical 16S rDNA sequences and therefore may either represent recent independent acquisitions or horizontal transfer between species. The S-symbionts have been cultured in vitro and a genetic transformation system has been developed. Here we report on their density and tissue tropism in different species (G. m. morsitans, G. p. palpalis, G. austeni and G. brevipalpis) and on their maternal route of transmission to tsetse progeny. Using a bacterium-specific PCR-assay, the S-symbionts were found primarily in the midgut, haemolymph, milk gland and in G. palpalis also in salivary glands of teneral flies. In older flies these infections were found to spread to other tissues including muscle, testes and fat body. The S-symbionts were transformed to express the marker gene product, Green Fluorescent Protein (GFP) in vitro. When the recombinant symbionts were introduced into the haemoceal of fertile female flies via intrathoracic microinjection, they were detected in the intrauterine progeny, indicating that haemolymph may provide a possible route for their transmission. The implications of these results for symbiont-host interactions and for transgenic strategies in tsetse are discussed.

Animals↗
PubMed1999

Integrin alphavbeta3-RGDS interaction mediates fibrin-induced morphological changes of glomerular endothelial cells.

BACKGROUND: In our previous studies, we found that intraglomerular deposition of fibrin and its metabolites was related to glomerular sclerosis and reduced renal function. It has been reported that both overlying and underlying fibrin may induce specific morphological changes of cultured endothelial cells from large blood vessels. The dependency of these morphological changes on the integrin alphavbeta3-arginyl-glycyl-aspartyl-serine (RGDS) interaction is still controversial. We hypothesized that glomerular endothelial cells (GECs) stimulated by fibrin might undergo morphological changes through an integrin alphavbeta3-RGDS interaction. Methods. In vitro studies were performed to examine the growing status of GECs stimulated by overlying and underlying fibrin gels in the presence or absence of the following: 50 microg/ml anti-alphavbeta3 integrin monoclonal antibody 23C6 or nonimmune mouse IgG, 1 mg/ml synthetic RGDS or arginyl-glycyl-glycyl-serine (RGGS) peptide, 10 mg/ml sodium heparin, 100 microg/ml cycloheximide, and 10 microM actinomycin D. Fast protein liquid chromatography (FPLC)-purified fibrinogen and the third to fifth passages of human GECs were also used in this study. RESULTS: GECs developed capillary tube structure after 60 hours of culturing on fibrin gels, and GECs cultured on gelatin-coated plates displayed a monolayer of cobblestone-like cells in the presence or absence of 23C6 and synthetic RGDS peptide. Fibrin-induced capillary tube formation was promoted by 23C6 and inhibited by RGDS peptide, cycloheximide, and actinomycin D. Disorganization of the GEC monolayer was induced by overlying fibrin, but was not induced by overlying agarose gels and glass cover slips or culturing in fibrinogen, 0.05 NIH U/ml thrombin, fibrin supernatants, as well as in fibrin degradation products. Disorganization of GEC monolayer can be induced by both des-AA-fibrin and des-AABB-fibrin and was unaffected by heparin. Furthermore, both 23C6 and synthetic RGDS peptide prevented disorganization of GECs induced by overlying fibrin, whereas nonimmune mouse IgG, synthetic RGGS peptide, cycloheximide, and actinomycin D had no similar effect. CONCLUSIONS: GECs cultured on fibrin gels may develop capillary structure spontaneously, and GECs covered by fibrin gels may undergo disorganization. Our data suggest that these GEC morphological changes are mediated by an integrin alphavbeta3-RGDS interaction.

Antibodies, Monoclonal↗
PubMed1999

The effectiveness and safety of dorzolamide 2% in addition to multiple topical antiglaucoma medications.

Dorzolamide is the first commercial topical carbonic anhydrase inhibitor approved by the Food and Drug Administration (FDA) for the treatment of glaucoma. In a prospective, open label, uncontrolled study on 245 glaucoma patients, dorzolamide significantly lowered the intraocular pressure at least 14% when used alone or in combination with one, two, or three other antiglaucoma medications over ten weeks. There were very few adverse reactions to dorzolamide. Dorzolamide is effective and safe when used alone or in combination with other topical antiglaucoma medications for the treatment of glaucoma.

Administration, Topical↗
PubMed1999

First hospital-admission rate as an epidemiological indicator for patients with multiple sclerosis in Stockholm, 1984-1993.

OBJECTIVES: To evaluate the first hospital-admission patients with multiple sclerosis (MS) in the population. MATERIAL AND METHODS: By using the data from hospital discharge registry of MS diagnosis in Stockholm during 1984-1993, we calculated rates of first hospital-admission patients with MS in the population and evaluated the temporal trend of the rates during the study period. RESULTS: There were 719 first hospital-admission patients with MS corresponding to 1556 admissions. The mean age at the first admission was nearly the same for male patients (44.3 years, SD: 12.9) and for female patients (44.6 years, SD: 13.7). The mean annual rate of first hospital-admission patients with MS was 4.46 per 100,000 person-years. The sex rate ratio of first hospital-admission patients with MS between females and males was 2.19:1. CONCLUSION: The first hospital-admission rate of MS could be used as an epidemiological indicator which is useful in planning of hospital service for MS patients.

Adolescent↗
PubMed1999

[Antisense oligonucleotide attenuates renal tubulointerstitial injury in mice with unilateral ureteral obstruction].

OBJECTIVE: To inhibit the expression of ICAM-1 mRNA with the mouse ICAM-1 phosphorothioate antisense oligodeoxynucleotide (ASON) and to investigate the role of ICAM-1 in the pathophysialogical process of renal injury in unilateral ureteral obstruction (UUO) animal model. METHODS: After unilateral ureteral ligation, the mice were treated with ICAM-1 ASON, which was injected intravenously at the dosage of 1 mg/kg/day every other day for one week. Other mice treated with control oligonucleotide or normal saline solution only were taken as controls. The expression of ICAM-1 protein and the number of Mac-1 positive cells were measured by immunohistochemical staining. The pathological changes of the obstructed kidney in the mice were analyzed by PAS-staining. Total RNA renal tissue was extracted for the analysis of the ICAM-1 mRNA by methods of Northern blotting. RESULTS: The expression of ICAM-1 protein and the number of Mac-1 positive cells were reduced markedly in the obstructed kidneys of the mice treated with the ICAM-1 ASON(110 +/- 14 [symbol: see text]/mm2 vs 270 +/- 13 [symbol: see text]/mm2). The results of Northern blotting also showed marked decrease of the expression of ICAM-1 mRNA in the kidney of the mice after treatment with ICAM-1 ASON. There were marked inflammatory cells infiltration in the tubulointerstitium, markedly dilated tubules, and extraceliular matrix accumulation in the obstructed kidneys on the 7th day after UUO operation. The treatment of ICAM-1 ASON can alleviate the lesions of the obstructed kidney except for the dilation of the tubules. There was no difference in the body weight, liver weight, spleen weight, the level of BUN and SCr, the level of GPT as well as the urine protein of the mice treated with ICAM-1 ASON, compared with those in control Oligodeoxynucleotide-treated and saline-treated mice. CONCLUSIONS: ICAM-1 is a very important factor in the pathogenesis of the UUO animal model. The mouse ICAM-1 ASON has therapeutic effects on the injury of the obstructed kidney without apparent side effects.

Animals↗
PubMed1999

[The experience of treatment of 7 cases of olfactory neuroblastoma].

OBJECTIVE: To improve the treatment result of olfactory neuroblastoma. METHOD: Introduce the experience of treatment of 7 patients with this disease. Among these 7 cases, 2 of them were stage B while the others were stage C according to the system proposed by Kadish. 3 cases received radiotherapy alone, and 4 others received radiotherapy pre-operation. The radiation dose was 5000-7000 cGy. All the patients were followed-up until December 1997. RESULT: 5 cases are still alive, survival time are 20, 22, 23, 29 and 76 months respectively. The other 2 patients died with the survival time of 6 and 48 months respectively. CONCLUSION: Radiotherapy seems effective in the treatment of olfactory neuroblastoma; the combination of chemo-radio-therapy is preferable for advanced or metastasis olfactory neuroblastoma. We extrapolate there are different subtypes on pathology in this tumor.

Adolescent↗
PubMed1998

stevor and rif are Plasmodium falciparum multicopy gene families which potentially encode variant antigens.

Several multicopy gene families have been described in Plasmodium falciparum, including the var genes that code for the variant surface antigen PfEMP1, the stevor family of subtelomeric open reading frames and the rif interspersed repetitive elements. This report documents the chromosomal location of stevor genes, their transcription and characteristics of the deduced protein. On 14 chromosomes, 34 stevor copies were identified from the Dd2 parasite line. Most are in subtelomeric regions within 50 kb of the telomere. stevor genes are located close to var genes and rij. All stevor genes sequenced had two exons: a short exon 1 encoding a start codon and a transmembrane domain; exon 2 encoding for the remainder of the approximately 30 kDa protein and including two more transmembrane segments. A similar structure was found for copies of rif and its predicted protein. In both STEVOR and RIF proteins, a highly polymorphic region is predicted to be a loop on the outer side of the membrane. We propose that stevor and rif are members of a larger superfamily. The number of copies of stevor and rif, their location close to the var genes, their extreme polymorphism and the predicted structure of the proteins suggest that stevor and rif code for variant surface antigens.

Amino Acid Sequence↗
PubMed1998

ras1 and pat1 alleles interact to quantitatively and qualitatively alter conjugation in fission yeast.

To identify novel components of ras1+ signalling in Schizosaccharomyces pombe, extragenic suppressors of the mating defect of ras1 effector mutants were isolated. A novel allele of pat1, pat1-e1, was isolated that increases the mating of ras1-D43E mutants to near wild-type levels but does not suppress the mating defect of ras1-I41M, ras1-Y37F, or ras1-Y45I mutants. This allele-specific suppression is not a characteristic of all pat1 alleles since pat1-3 and pat1-114 partially and equally suppress ras1-D43E and ras1-I41M mutants. Analysis of mating cultures showed that ras1-D43E and pat1-e1 interact to qualitatively alter the mating response. While pat1-e1 ras1-D43E cells were delayed in agglutination, cell-cycle delay, and mat1-Pm transcription, they induce mat1-Mc at the same time and mate more rapidly than other mating cultures. These results suggest that pheromone signalling, but not nutritional signalling, is delayed in pat1-e1 ras1-D43E cells. We hypothesize that this delay causes an elevated pheromone response and thus suppression of the mating defect of the ras1-D43E mutant by pat1-e1.

Alleles↗
PubMed1998

The effect of antiglaucoma drugs on rabbit aqueous humor proteins determined by gel electrophoresis.

Previous studies indicate that there may be differences in the protein composition of the aqueous humor in normal and glaucomatous human eyes. These differences in protein composition and concentration may be due to the topical antiglaucoma medications used to treat glaucoma. These differences should be distinguished from any possible protein composition changes due to glaucoma. In order to study the effects of topical antiglaucoma medications on aqueous humor protein composition, we analyzed the aqueous humor of rabbit eyes topically treated with various antiglaucoma medications (timolol, pilocarpine, and dipivefrin). One eye of each rabbit was treated with the experimental drug, and the fellow eye was treated with saline solution (control). Thirty-six aqueous humor samples from 18 rabbits were obtained after 24 hours and 36 samples were obtained from 18 additional rabbits after 7 days of topical drug treatment. The protein composition of the aqueous humor samples was analyzed by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Significant protein differences in aqueous humor samples were found between the eyes treated with timolol and the control eyes, whereas no significant differences were found between the eyes treated with pilocarpine or dipivefrin and the controls. These protein differences ranged from 14,000 to 18,000 daltons in molecular weight.

Administration, Topical↗
PubMed1998

Reproducibility of intraocular pressure and outflow facility measured by pneumatic tonography and Schiotz tonography.

The purpose of this study was to compare means, variability, and reproducibility in intraocular pressure and in outflow facility measured repeatedly over several days by Bio-Rad pneumatonography and Schiotz tonography in normal human volunteers. For each instrument a measurement of intraocular pressure and one of outflow facility were obtained at each of three repeated examinations of eight healthy subjects in the supine position. For pressure, the Bio-Rad mean was significantly higher by 5.31 mmHg than the Schiotz mean (p < 0.00005). Reproducibility was 71.1% and 59.0% for the Bio-Rad and Schiotz, respectively. For outflow, the Bio-Rad and Schiotz means were not significantly different. Reproducibility was 17.3% and 58.7% for the Bio-Rad and Schiotz, respectively. For measuring pressure, both the Bio-Rad and Schiotz instruments had good reproducibility; for measuring outflow, the Bio-Rad and Schiotz instruments had low and good reproducibility, respectively.

Adult↗
PubMed1998

Basic science and clinical aspects of wound healing in glaucoma filtering surgery.

Success of glaucoma filtration surgery is influenced by the wound healing response. Attention has been focused on pharmacological agents to control a process that leads to excessive scarring and eventual failure of glaucoma filtration surgery. Several agents, including 5-fluorouracil and mitomycin C, as well as other antiproliferative drugs will be discussed. Newer antifibrotic agents and novel drug delivery systems are under development in tissue culture and animal models in an effort to improve efficacy and safety. This article summarizes current treatment modalities and future prospects to prevent excessive wound healing and improve the success of glaucoma filtration surgery.

Culture Techniques↗
PubMed1998

[Intracardiac operations performed in beating heart through mini-thoracotomy in 34 patients].

OBJECTIVE: To introduce the technique of intracardiac operations performed in beating heart through mini-thoracotomy. METHOD: >From March 1995 to June 1997, intracardiac operations were performed in beating heart through right subaxillary anterolateral mini-thoracotomy with normothermic extracorporeal circulation in 34 patients. 16 patients had atrial septal defect, 14 ventricular septal defect, 2 mitral insufficiency, 1 right coronary artery-right ventricular fistula, and 1 Ebstein's anomaly. RESULT: The mean cardiopulmonary bypass time was 22.54 minutes. There were no embolism, arrhythmia and cerebral complications. Postoperative hospital stay was 8.0 +/- 2.2 days. All the patients had no heart murmur and residual shunt, and enjoyed a full range of physical activities in a follow-up of 2 to 26 months. CONCLUSION: Intracardiac operations performed in beating heart through right subaxillary anterolateral mini-thoracotomy appears to be less invasive, simple, safe and cosmetic.

Adolescent↗
PubMed1998

Increased incidence of Guillain-Barré syndrome postpartum.

We studied the relation between pregnancy and Guillain-Barré syndrome in the Swedish female population ages 15-49 years during the period 1978-1993. Person-based information from the national Hospital In-patient Registry on patients discharged with a diagnosis of Guillain-Barré syndrome was linked to data on pregnancy and delivery from the Swedish Medical Birth Registry. We validated coded Guillain-Barré syndrome diagnoses and the time periods of clinical onset for patients hospitalized with Guillain-Barré syndrome during pregnancy or during the first 90-day postpartum period. We compared the incidence of Guillain-Barré syndrome in women in different exposure categories related to pregnancy with that in women neither pregnant nor in the 90-day postpartum period. Poisson regression analysis yielded age-adjusted rate ratios of 0.89 [95% confidence interval (CI) = 0.52-1.53] for pregnant women, 1.37 (95% CI = 0.64-2.91) for women during the first 90 days, and 2.93 (95% CI = 1.20-7.11) during the first 30 days after delivery. Our results indicate that the risk of Guillain-Barré syndrome increases after delivery, particularly during the first 2 weeks postpartum.

Adolescent↗
PubMed1997

Guillain-Barré syndrome in Stockholm County, 1973-1991.

In order to describe the incidence of Guillain-Barré syndrome (GBS) in Stockholm County (SC) and hospital use by GBS patients, we conducted a retrospective epidemiological study on GBS covering 1973-1991, using the Hospital Inpatient Register in SC. There were 556 patients, bona fide residents in the county during the study period, discharged from hospitals with GBS diagnosis. The mean annual incidence, age-adjusted to the European population, was 1.84 (2.15 for males and 1.57 for females) per 100,000 population. The incidence increased with age and showed a bimodal distribution with peaks in the 10-29 and 70-79 age-groups. Annual incidence rates were highest in 1978 and 1983. Neither heterogeneity of annual or monthly rates nor linear trends during the period were found to be significant, except in 1978 for patients below 40 years of age, RR 1.72 (95% CI 1.08-2.71) and in 1983 for patients at ages 40 years and over, RR 1.48 (95% CI 1.02-2.16), when compared with GBS incidences in the same age-groups during the remaining study period. The mean +/- SD duration of hospital stay, including long-term care or rehabilitation institutions, for GBS patients, was 86 +/- 210 days, with considerably longer duration for the elderly. The rate of hospital use by GBS patients was 162 days per 100,000 inhabitants per year. In accordance with results of prior studies in South-West Stockholm and described GBS epidemics in Sweden, this study supports that an etiologically different subgroup of GBS exists at ages below 40 years, and that relevant but small time-space variations, such as the reported zimeldine epidemic in 1983, resist detection by hospital data analysis of pooled GBS cases. Efficient epidemiological surveillance of GBS may require targeted development of clinico-epidemiological tools.

Adult↗
PubMed1997

The com locus controls genetic transformation in Streptococcus pneumoniae.

Genetic exchange by natural transformation in Streptococcus pneumoniae occurs in a cell-density dependent process and is initiated by a small extracellular signalling molecule, the competence-stimulating peptide (CSP). comC, the gene for this peptide, has previously been identified and encodes a 44 amino acid pre-peptide that is apparently processed to an active molecule that consists of the C-terminal 17 amino acids. We have sequenced the region adjacent to comC and shown that it is the first gene of an operon, com, consisting of two downstream elements, comD and comE, which encode members of the two-component family of sensor regulators. Null mutants with defects in either comC or comD were transformation deficient and failed to respond to exogenous CSP. A comC mutant did not exhibit any detectable CSP activity, while a comD mutant that contained an intact comC produced minimal CSP activity. In mixed-culture experiments consisting of isogenic pairs of pneumococci (Csp+ and Csp-), we showed that induction of competence by quorum sensing was independent of CSP. Northern analysis showed that com was transcribed as a single polycistronic message, while analysis of strains with transcriptional fusions showed that com was constitutively expressed under conditions that both promoted or repressed the development of competence. Finally, we showed genetically and biochemically a CSP-dependent transcription of rec, a competence-induced locus, and that ComD and ComE are required for this CSP-dependent expression.

Bacterial Proteins↗
PubMed1997

Influence of n-3 fatty acid supplementation on the endogenous activities of plasma lipases.

The aim of these studies was to explore the possibility that enhanced triacylglycerol clearance may contribute to the hypotriacylglycerolemic effect of n-3 fatty acids in humans. Healthy subjects (n = 20) and hypertriacylglycerolemic patients (n = 6) were given a placebo (olive oil, OO) or a fish-oil concentrate (FOC; 41% eicosapentaenoic acid and 23% docosahexaenoic acid) in two, independent, randomized, blind trials. For the healthy subjects, the FOC treatment period was 3 wk long and FOC intakes were 5 g/d. For the patients, treatment periods were 4 wk long and dosages were 5 g.70 kg body wt-1.d-1. Washout periods were 2-4 wk for both groups. Blood samples were drawn at the end of each phase and analyzed for plasma lipids, lipoproteins, and endogenous (nonheparin-stimulated) activities of lipoprotein lipase (LPL) and hepatic lipase (HL). In the healthy subjects the FOC decreased plasma triacylglycerol concentrations by 18% (P < 0.01), whereas in the patients concentrations were reduced by 35% (P < 0.05). Low-density-lipoprotein-cholesterol concentrations increased by 25% in the latter group (P = 0.06). FOC increased the endogenous activities of LPL and HL by 62% and 68%, respectively (P < 0.0001), in the healthy subjects, but only LPL in the patients (65%, P < 0.005). These data suggest that endogenous lipase activities may be altered by nutritional interventions, and further, that accelerated lipolysis could contribute, at least in part, to the observed effects of n-3 fatty acids on human lipoprotein metabolism.

Fatty Acids, Omega-3↗