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Biomedical subjects

T Su

Publications and source records attributed to T Su.

At least 55 records · Page 3Linked to original sources
PubMed1998

Antifeedancy of neem products containing Azadirachtin against Culex tarsalis and Culex quinquefasciatus (Diptera: Culicidae).

In order to develop and utilize new botanical insecticides originating from neem (Azadirachta indica A. Juss) in mosquito control programs as a potential larvicide, the antifeedant activity of three formulations of neem against the larvae of Culex tarsalis Coquillett and Culex quinquefasciatus Say was investigated under laboratory conditions. A significant antifeedancy was indicated at 5 ppm and 10 ppm azadirachtin (AZ) for all formulations and both species. Within the test concentration range of AZ (1-10 ppm), 5 ppm was the minimum effective concentration for antifeedancy in most cases. Some differences in larval susceptibility in terms of antifeedancy to the test formulations were noted between the two species. The Cx. tarsalis larvae were more susceptible than Cx. quinquefasciatus larvae to Azad EC 4.5 at 1 ppm during the first 15-min exposure period and at 5 and 10 ppm during the whole test period. The Cx. quinquefasciatus larvae were more susceptible than Cx. tarsalis larvae to Azatin WP 4.5 at 1, 5, and 10 ppm during the first 15-min exposure period or to Neemix EC 4.5 at 1 ppm during the first 45-min exposure period. The formulation-related differences in antifeedant activity appeared when the concentration increased from 1 to 10 ppm. In Cx. tarsalis, the Azad EC 4.5 and Neemix EC 4.5 were more effective than Azatin WP 4.5 at 5 ppm during the first 15-min exposure period and at 10 ppm during the whole test period. In Cx. quinquefasciatus, the Azatin WP 4.5 and Neemix EC 4.5 were more effective than Azad EC 4.5 at 1 ppm during the first 30-min exposure period, and at 5 ppm during the first 60-min exposure period, and at 10 ppm during the whole test period.

Animals↗
PubMed1997

Fibrinogen receptor (GPIIb-IIIa) antagonists derived from 5,6-bicyclic templates. Amidinoindoles, amidinoindazoles, and amidinobenzofurans containing the N-alpha-sulfonamide carboxylic acid function as potent platelet aggregation inhibitors.

A series of highly potent and specific fibrinogen receptor antagonists have been discovered and optimized through structural modification of the novel amidinoindole and benzofuran compounds, I and II. Systematic linker optimization afforded the amidinobenzofuran-containing inhibitor 29, which displayed an IC50 value of 250 nM in platelet aggregation assays. Attempts to enhance activity by modification of the beta-position of the beta-alanyl carboxylate group of 29 had only a modest effect on inhibitory activity in aggregation assays. Analogues prepared to enhance the activity by conformational restriction were also found to be equally or less potent. In contrast, modification at the alpha-position of the beta-alanyl carboxylate group resulted in the identification of extremely potent and novel amidinobenzofuran-containing derivatives 46-49. Reexamination of 5,6-bicyclic aromatic nucleus led to the further identification of amidinoindole- and amidinoindazole-containing derivatives 53-55. These analogues, 46-49 and 53-55, exhibited potent in vitro activity with IC50 values of 25-65 nM in platelet aggregation assays and an IC50 value of 2 nM in fibrinogen binding assays and demonstrated a selectivity of > 50,000-fold for GPIIb-IIIa versus the most closely related integrin, the vitronectin receptor, alpha v beta 3.

Administration, Oral↗
PubMed1997

cDNA cloning, heterologous expression, and characterization of mouse CYP2G1, an olfactory-specific steroid hydroxylase.

CYP2G1 is expressed specifically in the olfactory mucosa in rabbits and rats. In the present study, a full-length cDNA for mouse CYP2G1 was obtained using a PCR approach with RNA preparations from the olfactory mucosa of C57BL/6 mice. Sequence comparisons indicated that mouse CYP2G1 is highly homologous in deduced amino acid sequence to rabbit (82.4% identity) and rat CYP2G1 (94.9% identity). RNA blot and immunoblot analyses indicated that mouse CYP2G1 is expressed only in the olfactory mucosa. The coding region of the mouse CYP2G1 cDNA was cloned into a baculoviral expression vector for heterologous production of the enzyme in cultured insect cells. Heterologously expressed mouse CYP2G1 was active in a reconstituted system toward testosterone and progesterone, producing all the major metabolites detected in olfactory microsomal reactions, including 15 alpha-, 15 beta-, and 2 beta-hydroxytestosterone from testosterone and two unidentified metabolites from progesterone. Kinetic analysis indicated that mouse CYP2G1 has relatively high affinities toward the steroid substrates, with K(m) values in the micromolar range for both testosterone and progesterone. At a substrate concentration of 10 microM, microsomes of olfactory mucosa had much higher turnover numbers toward testosterone and progesterone than hepatic microsomes, consistent with the olfactory-specific expression of a high-affinity sex steroid hydroxylase. These findings will facilitate further molecular genetics studies on the biological function of CYP2G1 in a mouse model.

Amino Acid Sequence↗
PubMed1997

Posttraumatic empyema. Risk factor analysis.

BACKGROUND: Empyema remains a distressing complication after thoracic injury. OBJECTIVE: To identify high-risk factors associated with the development of empyema. DESIGN: Retrospective cohort review. SETTING: University hospital, level I trauma center. PATIENTS: Trauma patients who required tube thoracostomy (TT) between January 1, 1991, and November 31, 1993 (n = 584). METHODS: Data (demographic characteristics, injuries, chest x-ray film reports, and setting of TT) were assessed using a stepwise logistic regression analysis to identify risk factors associated with the development of post-traumatic empyema. RESULTS: Empyema that required decortication developed in 25 patients (4%). Factors predictive of development of empyema were retained hemothorax (odds ratio, 12.5; 95% confidence interval, 0.96-163), pulmonary contusion (odds ratio, 6.3; 95% confidence interval, 1.53-25.8), and multiple chest tube placement (odds ratio, 2.5; 95% confidence interval, 1.91-3.28); factors not predictive of empyema were severity of injury, mechanism of injury, setting in which TT was performed, number of days chest tubes were in place, and antibiotic drugs at the time of TT. CONCLUSIONS: The extent of pulmonary injury (pulmonary contusion) is an important predictor of empyema development. Previously implicated factors such as setting in which a TT was performed and mechanism of injury did not correlate with the development of posttraumatic empyema. Based on the results of our study, we recommend early drainage of the pleural space with video-assisted thoracoscopic techniques in patients at risk of empyema, which may spare them the morbidity of a thoracotomy.

Empyema, Pleural↗
PubMed1997

Nutritional reserves, body weight, and starvation tolerance of autogenous and anautogenous strains of Culex tarsalis (Diptera:Culicidae).

The nutritional reserves and body weight of autogenous and anautogenous strains of Culex tarsalis Coquillett were determined for 4th instars, pupae, females, and males. Starvation tolerance and survivorship of adult females and males also were studied. The autogenous individuals contained significantly greater amounts of total lipids (except the total lipids in 4th instars), total carbohydrates, glycogen, and total proteins, which resulted in a heavier mean body weight of autogenous than anautogenous mosquitoes (except the fresh weight in pupae). Results of the body fluid coefficient determination were inconclusive. Nutritional reserves in the immature stages, especially the pupal stage, were significantly greater (except the total proteins in 4th instars and female adults) than those in the adult stage. There were no significant differences in median longevity between autogenous and anautogenous females, and between autogenous and anautogenous males, provided with distilled water alone after emergence. The median longevity of females and males was significantly different in both autogenous and anautogenous strains. Our findings strongly indicate a relationship between autogenous reproduction and differences in nutritional reserves of autogenous and anautogenous strains.

Animals↗
PubMed1997

Quantitative determination of free amino acids in the hemolymph of autogenous and anautogenous strains of Culex tarsalis (Diptera: Culicidae).

Autogenous and anautogenous strains were selected from the egg rafts of Culex tarsalis Coquillett collected from Coachella Valley, California. In autogenous (21-25 generations) and anautogenous (0-4 generations) strains used for hemolymph free amino acid analysis, the autogenous oviposition rates were 73.6-83.6% and 2.7-3.9%, the proportions of females undergoing autogenous ovarian development 120 h postemergence were 75.6 and 8.9%, respectively. To study the presence and quantities of free amino acids and explore their relationship to autogenous ovarian development, the 6 legs of females from both autogenous and anautogenous strains were removed at the coxo-femoral joints, and hemolymph was collected by centrifuging the bodies of 50-100 females. Proteins in the hemolymph were precipitated with 10% sulphosalicylic acid. On days 1, 4, 7, and 10 postemergence, a total of 17 free amino acids was found in females from the autogenous strain, and a total of 16 was found in females from the anautogenous strain in which asparagine (Asn) was absent. Comparisons of free amino acid concentrations between these 2 strains indicated that there were significant differences in total free amino acids and 13 individual free amino acids except Glu, Gln, Pro, and Met on day 1, total free amino acids and 14 individual free amino acids except Gln, Pro, and on day 4, and total free amino acids and 12 individual free amino acids except Asp, Glu, Gln, Pro, and Met on day 7 postemergence. There were no significant differences in the concentrations of individual and total free amino acids on day 10 postemergence. Female age affected free amino acid content in the autogenous strain, where total free amino acids and 14 individual free amino acid content in the autogenous strain, where total free amino acids and 14 individual free amino acids increased from day 1, peaked on day 4, declined on day 7, and declined further on day 10 postemergence. In the anautogenous strain, only total free amino acids and Ser, Gly, Ala, and Leu exhibited age-dependent changes in concentration, and the magnitude of changes in concentration was less than that in autogenous strain. Conclusively, autogenous ovarian development was the major reason for the changes in hemolymph free amino acid concentration postemergence. The current and previous findings indicate that the free amino acids, Arg, Gly, Ile, Leu, Lys, Phe, Ser, Thr, and Val putatively may be essential for vitellogenesis in mosquitoes.

Amino Acids↗
PubMed1997

Kinetic modeling of [11C]raclopride: combined PET-microdialysis studies.

The in vivo binding of D2 receptor ligands can be affected by agents that alter the concentration of endogenous dopamine. To define a more explicit relation between dopamine and D2 receptor binding, the conventional compartment model for reversible ligands has been extended to account for a time-varying dopamine pulse. This model was tested with [11C]raclopride positron emission tomography and dopamine microdialysis data that were acquired simultaneously in rhesus monkeys. The microdialysis data were incorporated into the model assuming a proportional relation to synaptic dopamine. Positron emission tomography studies used a bolus-plus-infusion tracer delivery with amphetamine given at 40 minutes to induce dopamine release. The extended model described the entire striatal time-activity curve, including the decrease in radioactivity concentration after an amphetamine-induced dopamine pulse. Based on these results, simulation studies were performed using the extended model. The simulation studies showed that the percent decrease in specific binding after amphetamine measured with the bolus-plus-infusion protocol correlates well with the integral of the postamphetamine dopamine pulse. This suggests that changes in specific binding observed in studies in humans can be interpreted as being linearly proportional to the integral of the amphetamine-induced dopamine pulse.

Animals↗
PubMed1997

Two novel mutations in phenylalanine hydroxylase gene and in vitro expression analysis on mutation Arg252Gln.

We report novel mutations in exon 7 of human phenylalanine hydroxylase (PAH) gene of phenylketonuria (PKU) in southern Chinese, analysed by using PCR-DGGE (denaturing gradient gel electrophoresis), solid phase DNA sequencing and in vitro expression. One of the 2 novel mutations, IVS6nt-1, is an intron-exon junctional mutation which results a splicing defect in mRNA. Arg252Gln is another novel mutation with residual PAH activity only 24% compared to wild type in in vitro mutagenesis and expression in Cos-1 cell. Other 3 known mutations and polymorphism including Arg241Cys, Arg243Gln and Val245Val (GTG to GTA) together with these novel mutations composed the mutational profile of exon 7 in the PAH gene of PKUs in this populations.

Exons↗
PubMed1997

Effect of high glucose on permeability of retinal capillary endothelium in vitro.

PURPOSE: To study the effect of high glucose on the permeability of bovine retinal capillary endothelial cell (BRCEC) monolayers. METHODS: The paracellular permeability of second-passage BRCEC cultured on millipore filters in two chamber transwell inserts was assayed by measuring the peak trans-monolayer electrical resistance and percent equilibration of 14C-inulin 48 hours after it had been added to the luminal chamber. RESULTS: High glucose increased the paracellular permeability of BRCEC monolayers independently of its hypertonic action (5 mM glucose: 154.2 +/- 21.2 and 19.5 +/- 2.4; 30 mM glucose: 134.2 +/- 5.1 [P = 0.01] and 23.5 +/- 2.1 [P = 0.01]; 5 mM glucose + 25 mM mannitol: 168.7 +/- 13.7 ohm.cm2 [P = 0.04] and 19.3% +/- 1.2% 48-hour equilibration of inulin [P = 0.008]). In a separate series of experiments, the authors were unable to show that either aminoguanidine or ponalrestat prevented the effect of high glucose on permeability (30 mM glucose 95.1 +/- 16.7 and 45.4 +/- 5.6; 5 mM glucose: 122.9 +/- 14.2 [P = 0.02] and 36.6 +/- 5.6 [P = 0.001]; 30 mM glucose + aminoguanidine 87.9 +/- 17.5 [P = 0.04] and 75.3 +/- 14.9 [P = 0.6]; 30 mM glucose + ponalrestat 79.9 +/- 12.7 ohm.cm2 [P = 0.1] and 48.2 +/- 2.5% 48-hour equilibration of inulin [P = 0.15]). Ponalrestat did not abrogate the effect of high glucose despite its ability to reduce a high glucose-induced increase in BRCEC intracellular sorbitol levels. CONCLUSIONS: The data are consistent with a role for increased paracellular permeability in breakdown of the blood-retinal barrier in diabetic retinopathy, which appears to be independent of both nonenzymatic glycosylation and the polyol pathway.

Animals↗
PubMed1997

Selection-dependent trends of autogeny and blood feeding in an autogenous strain of Culex tarsalis (Diptera:Culicidae).

During successive en masse selection of autogeny in Culex tarsalis from parental to 20th generation, the autogenous oviposition capacity changed as follows: mean number of egg rafts/female and mean number of eggs/female increased significantly, from 0.11 to 0.56 and from 6.2 to 20.2, respectively; the mean size of the egg rafts decreased significantly, from 56.2 to 36 eggs/raft; autogeny rates increased significantly, from 18.6 to 65.2%; mean number of autogenous follicles/female decreased significantly, from 57.4 to 34; the hatching rate of autogenous egg rafts reduced significantly, from 88.3 to 75.4%; and the feeding rates of the females on a blood meal source during the 7th day postemergence increased significantly, from 62.8 to 71.1%. The autogeny rate determined by ovarian dissection was higher than that indicated by actual oviposition. As the age of females increased during the observed 10-day oviposition period, the mean number of egg rafts/female, the mean number of eggs/female, and the mean number of eggs/raft decreased successively, and scattered "light color" egg rafts became more common. Successive en masse selection enhanced autogeny and strengthened the bloodfeeding tendency in this facultative autogenous species.

Animals↗
PubMed1997

Physiological aspects of autogeny in Culex tarsalis (Diptera: Culicidae): influences of sugar-feeding, mating, body weight, and wing length.

Sugar feeding and mating promoted the expression of autogeny in Culex tarsalis. In sugar-fed cohorts fed 5, 10, and 20% sucrose solution, the mean number of egg rafts/female, mean number of eggs/raft, mean number of eggs/female, mean number of autogenous follicles/female, and the autogeny rate were all significantly greater than those in sugar-deprived cohorts. There were no significant differences in these parameters among the sugar-fed groups of 5, 10, and 20%. Similarly, magnitudes of the parameters mentioned above in female-male cohorts were significantly higher than those in female-alone cohorts. There was no difference in the hatching rate of the autogenous egg rafts in the cohorts fed on different sucrose solutions and the female-male cohorts, while it was 0 in male-deprived cohorts. There were positive correlations between mean emergence weight and mean number of autogenous eggs/female (r2 = 0.69), mean emergence weight and mean number of autogenous follicles/female (r2 = 0.75), mean wing length and mean number of autogenous eggs/female (r2 = 0.64), and mean wing length and mean number of autogenous follicles/female (r2 = 0.63). The regression analysis of the data indicated that females with emergence weights < 1.92 mg could not oviposit autogenously, and those with emergence weights < 1.89 mg could not develop the ovaries autogenously. Females with wing lengths < 2.89 mm could not oviposit autogenously and those with the wing length of < 2.83 mm could not develop the ovaries autogenously. The coefficient of correlation between emergence weight and autogenous follicles/female was greater than that between emerging weight and autogenous eggs/female. The coefficients of correlation between emergence weight and autogeny were greater than that between wing length and autogeny. Therefore, autogenous follicles/female is a more accurate parameter to describe autogeny expression level than autogenous eggs/female because oviposition is affected by other factors, and emergence weight is a more important factor determining autogeny expression than wing length.

Animals↗
PubMed1996

DNA binding properties of two Arabidopsis MADS domain proteins: binding consensus and dimer formation.

MADS domain proteins are members of a highly conserved family found in all eukaryotes. Genetic studies clearly indicate that many plant MADS domain proteins have different regulatory functions in flower development, yet they share a highly conserved DNA binding domain and can bind to very similar sequences. How, then, can these MADS box genes confer their specific functions? Here, we describe results from DNA binding studies of AGL1 and AGL2 (for AGAMOUS-like), two Arabidopsis MADS domain proteins that are preferentially expressed in flowers. We demonstrate that both proteins are sequence-specific DNA binding proteins and show that each binding consensus has distinct features, suggestion a mechanism for specificity. In addition, we show that the proteins with more similar amino acid sequences have more similar binding sequences. We also found that AGL2 binds to DNA in vitro as a dimer and determined the region of AGL2 that is sufficient for DNA binding and dimerization. Finally, we show that several plant MADS domain proteins can bind to DNA either as homodimers or as heterodimers, suggesting that the number of different regulators could be much greater than the number of MADS box genes.

Amino Acid Sequence↗
PubMed1996

Expression of CYP2A genes in rodent and human nasal mucosa.

CYP2A10 and CYP2A11, which are abundant in olfactory microsomes from rabbits, are active in the metabolic activation of a number of nasal toxicants, such as hexamethylphosphoramide and N-nitrosodiethylamine. Previous immunohistochemical studies indicated that CYP2A-related cytochromes P450 may also be present in rodent and human olfactory tissue. In the present study, the expression of cytochromes P450 highly homologous to rabbit CYP2A10/11 in rat, mouse, and human nasal mucosa was studied. In Sprague-Dawley rats, CYP2A3 mRNA was detected in olfactory mucosa at levels much higher than those found in total RNA from lung. Similar observations were made for the level of microsomal CYP2A3 protein with the use of antibodies to rabbit CYP2A10/11. However, mRNAs for two other rat cytochrome P450 genes in the CYP2A subfamily, CYP2A1 and CYP2A2, were not detected in nasal tissue by RNA-polymerase chain reaction analysis. In C57BL/6 mice, both CYP2A4 and CYP2A5 mRNAs were detected in the olfactory mucosa by RNA-polymerase chain reaction, but the CYP2A5 transcript was present at a level much higher than that of CYP2A4. The expression of another mouse gene in CYP2A subfamily, CYP2A12, was not detected in nasal tissue. CYP2A5 protein was also detected in mouse olfactory microsomes at higher levels than in liver, lung, or kidney microsomes. However, no significant sex differences in the levels of CYP2A4/5 mRNA or microsomal coumarin 7-hydroxylase activity were found with the nasal tissue. In addition, consistent with previous immunohistochemical studies, the expression of CYP2A6 in human nasal mucosa was detected by RNA-polymerase chain reaction as well as RNA blot analysis. The identification of CYP2A6 in human nasal tissues may have important implications for risk assessment of potential nasal toxicants, and the abundant expression of the CYP2A genes in rat and mouse olfactory tissue suggests a molecular basis for the known tissue-specific toxicity of numerous inhaled compounds in rodents.

Animals↗
PubMed1995

Interferon-alpha 2b enhances barrier function of bovine retinal microvascular endothelium in vitro.

Increased permeability of the vascular endothelium is a critical part of pathological processes such as inflammation and wound healing. While several cytokines have been shown to increase endothelial permeability, none has been shown to reduce it. We studied the effect of interferon-alpha 2b on the barrier function of bovine retinal capillary endothelial cells in vitro and found that it increased the electrical resistance of the monolayers (treated cells 211 +/- 6 ohm.cm2, untreated 109 +/- 14 ohm.cm2), decreased their permeability to inulin (Pc inulin of untreated cells 0.73 +/- 0.21 x 10(-6) cm/sec, treated 0.31 +/- 0.23 x 10(-6) cm/sec, P = 0.015), and enhanced their morphological differentiation. Interferon-gamma had no effect. No effect of interferon-alpha treatment on the permeability of bovine aortic endothelial cells was found. We conclude that interferon-alpha 2b can enhance the barrier function of retinal microvascular endothelium in vitro. This is consistent with the hypothesis that interferon-alpha is an effector of a mechanism which actively promotes tissue homeostasis and suggests that it might have therapeutic potential in diseases characterized by leakage of the vascular endothelium.

Animals↗
PubMed1995

Enhanced susceptibility to human immunodeficiency virus infection in CD4+ T lymphocytes genetically deficient in CD43.

CD43 is a cell surface sialoglycoprotein expressed by most cells of hematopoietic origin, including all T lymphocytes. Elimination of CD43 expression by gene targeting in the CEM T cell line results in its increased homotypic adhesion and binding to HIV-1 gp120. Here we report that the CD43-negative CEM cells show increased susceptibility to HIV-1 infection and increased viral replication compared with the parental CD43+ CEM cell line. Increased HIV-1 replication also was observed in CEM cells with diminished CD43 expression secondary to functional inactivation of a single CD43 allele. The CD43- CEM cells were more susceptible to HIV-1-induced cytopathicity than their CD43+ counterparts. HIV-1 replication also was increased in the CD43- CEM cells after transfection with the infectious HIV molecular clone pNL4-3. These data suggest that factors that diminish CD43 expression on T lymphocytes may enhance their susceptibility to HIV-1 infection.

Antigens, CD↗
PubMed1995

Electrical resistance and macromolecular permeability of retinal capillary endothelial cells in vitro.

This study was undertaken to examine the ability of retinal capillary endothelial cells to retain blood-retinal barrier properties in vitro. Second passage bovine retinal capillary endothelial cells were grown to confluence on polycarbonate filters in two chamber systems coated with laminin, fibronectin and type IV collagen. The electrical resistances, permeability of 3H-insulin and expression of blood-brain barrier related enzymes by retinal cells was observed and compared with bovine aortic endothelial cells and bovine fibroblasts. The electrical resistance of retinal cells rose over the first week of culture, peaking after 5-9 days in culture. In eleven separate experiments (n = 5 for each experiment) the average peak resistance of retinal endothelial cells ranged from 89.3-186.6 with a mean average of 129.0 ohm.cm2. In one of these experiments, the peak electrical resistance of retinal cells was 149.0 +/- 10.3 compared with 34.8 +/- 6.8 for aortic cells and 37.8 +/- 3.8 ohm.cm2 for fibroblasts. The permeability coefficients of inulin were: retinal cells 0.17 +/- 0.09, aortic cells 3.47 +/- 1.58 (p = 0.015), fibroblasts 3.93 +/- 0.78 (p = 0.002) x 10(-6) cm/sec. Retinal cells expressed significantly higher activities of gamma-glutamyl transpeptidase and alkaline phosphatase than the other cell types. Treatment of the monolayers with the calcium ionophore, A23187, resulted in a reversible increase in permeability as has been described for peripheral vascular endothelium. We conclude that BRCEC retain at least some of their specialised barrier properties in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗