Biomedical subjects

G Tang

Publications and source records attributed to G Tang.

At least 109 records · Page 6Linked to original sources

PubMed1997

[Studies on purging leukemic cells by photosensitizer PSD-007 laser photoradiation in vitro].

The sensitivity to photosensitization mediated by the hematoporphyrin photosensitizer PSD-007 of acute promyelocytic leukemic cell line (HL-60) was compared with normal human hemopoietic progenitor cells. The results showed that the leukemic cells were more sensitive. After being treated with 10 micrograms.ml-1 PSD-007 followed by 2J.cm-2 copper vapor laser light irradiation, the clonogenic leukemic (HL-60) cells were reduced 98%, but the survival rate of human granulocyte-macrophage colony-forming units (CFU-GM) was 40 +/- 8%. Mixing of normal human marrow cells with leukemic (HL-60) cells (ratio 100:1) did not interfere with elimination of tumor cells. The ultrastructure changes of HL-60 cells treated by laser photoradiation was observed under the trans-electronic microscope. The mitochondria, endoplasmic reticulum and cell membrane were involved. This means that the cell biomembrane is the main target to be attacked. It is considered that PSD-007-laser photoradiation therapy is efficient for killing leukemic cells.

Adult↗

PubMed1996

Human plasma carotenoid response to the ingestion of controlled diets high in fruits and vegetables.

Plasma carotenoid responses were determined in 36 healthy men and women before and after being fed controlled diets with a moderate amount of fat (26% of total energy) and a high carotenoid content (approximately 16 mg/d) for two 15-d periods. In addition, broccoli (205 g/d) was provided either during the first or the second 15-d residency period in a crossover design. Plasma was digested with lipase and cholesterol esterase, and carotenoids were extracted and measured by using HPLC. Three oxygenated carotenoids (lutein, zeaxanthin, and cryptoxanthin), three hydro-carbon carotenoids (alpha-carotene, all-trans-beta-carotene, and 13-cis-beta-carotene), and four geometric isomers of lycopene (15-cis-, 13-cis-, 9-cis-, and all-trans-lycopene) were separated by using a C30 carotenoid column. A small unidentified peak coeluted with standard 9-cis-beta-carotene and was identified as zeta-carotene (lambda(max) = 400 nm). The concentrations of plasma lutein, cryptoxanthin, alpha-carotene, 13-cis-beta-carotene, all-trans-beta-carotene, and cis- and trans-lycopenes were all significantly increased (P < 0.05) on days 6-16 by the high-fruit and -vegetable diets. The provision of additional broccoli for 5 d to the basic high-carotenoid diet resulted in a further significant increase in the serum concentration of lutein compared with the feeding of the basic high-carotenoid diet alone. Most of the measurable carotenoids of human plasma can be increased by moderate alterations in diet within a short time, although the magnitude of the plasma response may be related to the baseline carotenoid concentrations.

Adult↗

PubMed1996

Gastric acidity influences the blood response to a beta-carotene dose in humans.

The effect of gastric acidity on the blood response to a single dose of 120 mg beta-carotene in humans was investigated in 12 normal subjects (5 women, 7 men) aged 23-68 y. Omeprazole was used for 7 d to obliterate gastric acid secretion and to raise gastric pH to > 4.5. In a crossover design, six subjects were randomly assigned to take beta-carotene with omeprazole either at the beginning (day 9) or at the end (day 26) of the study. The beta-carotene response in blood was not altered by the experimental order. Results from the high-gastric-pH phase (ie, with omeprazole) were analyzed together and compared with the results from the low-gastric-pH phase (ie, without omeprazole). The increases of serum concentrations of both trans beta-carotene and cis beta-carotene 6 and 24 h after the beta-carotene dose were significantly greater at a low gastric pH (pH = 1.3 +/- 0.1, ie, without omeprazole) than those at a high gastric pH (pH = 6.4 +/- 0.3, ie, with omeprazole), P < 0.02. Similarly, 24 h after beta-carotene administration, the area under the blood beta-carotene response curve (trans plus cis beta-carotene) was significantly greater at a low gastric pH (6825 +/- 760 nmol.h/L) than at a high gastric pH (3390 +/- 550 nmol.h/L), P < 0.002. In investigations of bacterial overgrowth, gelatin capsule disintegration and isomeric profiles associated with high and low pH, we could not identify factors to explain the differences observed in the blood response curves between low-gastric-pH and high-gastric-pH conditions. A suppressed blood response of beta-carotene at a high intraluminal pH may have been due to the slower movement of negatively charged micelles through the unstirred water layer and cell membrane.

Absorption↗

PubMed1996

In vivo biosynthesis of retinoic acid from beta-carotene involves and excentric cleavage pathway in ferret intestine.

This study was done to determine whether retinoic acid can be produced by excentric cleavage of beta-carotene in vivo. By using an inhibitor of retinaldehyde oxidation, citral, either retinaldehyde or beta-carotene was incorporated in a micellar solution and perfused through the upper portion of small intestine of ferrets. After 2 h perfusion of 1 microM retinaldehyde, retinoic acid rose in portal blood (+3.5 +/- 1.3 nmol/L) and was detected in the intestinal mucosa (30 +/- 2 pmol/g). When citral was added at 2 mM along with retinaldehyde, retinoic acid decreased in the portal blood and retinoic acid was not detected in the intestinal mucosa. With or without the presence of citral (2 mM), the perfusion of beta-carotene (10 microM) during 2 h caused a significant rise of retinoic acid in portal blood (+2.6 +/- 0.6 nmol/L and + 4.1 +/- 0.6 nmol/L, respectively) and in liver; moreover, significant amounts of retinoic acid were detected in the intestinal mucosa (19 +/- 3 pmol/g and 36 +/- pmol/g, respectively. This study demonstrates that after intestinal perfusion of beta-carotene in the ferret in vivo, a substantial amount of retinoic acid is formed via an excentric cleavage pathway.

Acyclic Monoterpenes↗

PubMed1996

Cloning and function determination of promoter region of glucoamylase gene from Aspergillus niger T21.

A 850 bp fragment of the 5' flanking region of the glucoamylase gene (glaA) was synthesized from A. niger T21 genome using PCR. The function detection vector was constructed by fusing this fragment to E. coli hygromycin B phosphotransferase gene (hph) and was used to transform A. niger. The high hygromycin resistance transformants thus obtained verified that the synthesized fragment functioned as a promoter in filamentous fungi. Southern blot analysis showed the hph gene has been integrated into genomic DNA of A. niger transformant.

Anti-Bacterial Agents↗

PubMed1996

Construction of a brewing yeast having glucoamylase activity and its fermentation characteristics.

The brewing yeast having glucoamylase activity was constructed by integrating glucoamylase cDNA from Asapergillus niger into the genome of brewing yeast B48. The integration was achieved by cotransformation of YEP type plasmid pKG1 carrying glucoamylase expression-secretion element and was verified by Southern blot analysis. The engineered yeast was stable, and the fermentation test demonstrated that the lower residual dextrin level was obtained compared with control strain B48. Thus the fermentation rate was raised to 80.5%. No alteration of growth and brewing properties was observed. Beer quality was judged to be good.

Aspergillus niger↗

PubMed1996

[Study on the death of Escherichia coli induced by hydrostatic pressures].

The effect of hydrostatic pressure on the death of E. coli was studied in this paper. The results indicated that E. coli could be killed by hydrostatic pressure above 800 bar. At 2300 bar E. coli was totally killed in 30 minutes. The time course of E. coli death induced by pressure indicated that the most E. coli was killed in the first 10 minutes after the pressure was applied. It was also found that the lower temperature favored killing E. coli under pressure.

Escherichia coli↗

PubMed1996

[On the conservation and regeneration of Taxus resources].

In recent years, the taxol isolated from the stem bark of some plants of Taxus has been widely as an antitumor agent. But the development of taxol is limited by the scarcity of wild Taxus resources. This paper seeks to discuss the ways to conserve and promote the regeneration of these resources.

China↗

PubMed1995

Similar metabolites formed from beta-carotene by human gastric mucosal homogenates, lipoxygenase, or linoleic acid hydroperoxide.

To determine the basis for the formation of excentric cleavage products of beta-carotene (beta-C) after incubation with human gastric mucosal homogenates, we have studied the effect of lipoxygenase in beta-C metabolism. beta-C was incubated with human gastric mucosal homogenates, soybean lipoxygenase with linoleic acid, or the lipoxygenase primary product, 13(S)-hydroperoxycis,trans-9,11-octadecadienoic acid (13-LOOH). The beta-C metabolites, beta-apo-14', -12', -10', and -8'-carotenals, beta-apo-13-carotenone, retinoic acid, and retinal were detected and quantified by HPLC after a 30-min incubation with 1.8 microM beta-C. The products from the lipoxygenase plus linoleic acid incubation and from the lipoxygenase primary product, 13-LOOH, with beta-C were exactly the same as the products from a human gastric mucosal homogenate incubation. Significantly larger amounts of the same beta-C metabolites were formed when beta-C was incubated with gastric mucosal homogenates and lipoxygenase together. Furthermore, nordihydroguaiaretic acid (NDGA), a specific lipoxygenase inhibitor, was found to significantly inhibit the formation of beta-apo-carotenoids and retinoids produced by gastric mucosal homogenates incubated with beta-C. The similarity of the beta-C metabolites when beta-C was incubated with human gastric mucosal homogenate, lipoxygenase plus linoleic acid, or 13-LOOH and the inhibition of beta-C metabolite production by NDGA in gastric tissue incubation with beta-C suggest that lipoxygenase is involved in beta-C metabolism in gastric mucosa. The activity of 13-LOOH in our hands would indicate that an enzyme-linked process is occurring in gastric tissue producing fatty acid hydroperoxides, and that the hydroperoxide, or a radical species derived from it, is able to carry out the oxidation of beta-C independently of the enzyme.

Biotransformation↗

PubMed1995

Timing of laparoscopic surgery in gallstone pancreatitis.

OBJECTIVE: To study the effect of the timing of laparoscopic cholecystectomy following acute gallstone pancreatitis. SETTING: University-based county teaching hospital. DESIGN: Retrospective case series. PATIENTS: One hundred forty-two patients with gallstone pancreatitis treated by laparoscopic cholecystectomy between April 1991 and September 1993. There were 16 men and 126 women, with a mean age of 39.5 years. The mean serum amylase level at admission was 1616 U/L. All patients were operated on more than 48 hours after admission, after clinical and biochemical resolution of pancreatitis. Preoperative endoscopic retrograde cholangiopancreatography was performed in 25 patients (more than 48 hours after admission), with common bile duct stones being identified and removed in 10. RESULTS: Twenty patients had three or more Ranson's criteria. Of these, nine had laparoscopic cholecystectomy attempted within the first week of admission. Six (67%) of these patients required conversion to open procedures (two for common bile duct exploration, one for repair of a common hepatic duct injury, and three for anatomic distortion due to inflammation). The mean postoperative stay of the nine patients was 5.4 days. The other 11 patients with three or more Ranson's criteria were operated on after 1 week, and only two required conversion to open cholecystectomy (18%). The mean postoperative stay in these 11 patients was 2.3 days. The difference in conversion rate approached but did not reach statistical significance (P = .08). The postoperative stay, however, was significantly shorter in the group of patients who underwent late operations (P = .03). There were 122 patients with fewer than three Ranson's criteria. In this group, there was no difference in length of postoperative stay between patients operated on earlier and those operated on later (2.4 vs 3.9 days; P = .49; n = 74 and n = 48, respectively). Of these 122 procedures, eight were converted to open procedures (6.6%). There was no significant difference in conversion rates in these patients regardless of whether they were operated on earlier or later. CONCLUSIONS: Based on these data, we believe, first, that laparoscopic cholecystectomy is safe in patients recovering from gallstone pancreatitis (mortality rate, 0%; bile duct injury, 0.7%). Furthermore, early operation can safely be recommended in patients with mild pancreatitis. However, in patients with three or more Ranson's criteria, operation during the first week following admission is associated with an increase in operative complications, an increased rate of conversion, and longer postoperative stays.

Acute Disease↗

PubMed1995

Serum retinoic acid levels in patients with resected benign and malignant colonic neoplasias on beta-carotene supplementation.

To determine whether patients with colon cancer metabolize beta-carotene differently from benign colon polyp patients, a normal control group (n = 13) and groups of resected colon polyp patients (n = 29) or resected colon cancer patients (Dukes A and B1, n = 21) were supplemented with placebo or beta-carotene (30 mg/day) taken with their morning meals for three months. Serum samples at zero and three months of the study were analyzed blindly for retinoic acid and beta-carotene. The results showed that beta-carotene levels in the serum of colon polyp and colon cancer groups were 8- to 12-fold higher than in the untreated control or the placebo-treated groups. The benign polyp subjects (n = 17) receiving beta-carotene showed a significant rise in serum trans-retinoic acid at three months compared with Time 0. The trans-retinoic acid values from the colon cancer group receiving beta-carotene (n = 11) or placebo (n = 10) were significantly lower than the values from the beta-carotene-supplemented colon polyp group. It appears that trans-retinoic acid levels in response to beta-carotene supplementation are different between treated cancer and benign patients because of different body demands for retinoic acid.

Adult↗

PubMed1995

Supplementing ferrets with canthaxanthin affects the tissue distributions of canthaxanthin, other carotenoids, vitamin A and vitamin E.

To study the effects of canthaxanthin supplementation on the tissue distribution of canthaxanthin, other carotenoids, vitamin A and vitamin E, 26 spayed female ferrets (2 mo of age) were used. Ferrets were assigned to receive a commercial ferret diet and a gavage of canthaxanthin [50 mg/(kg body wt.d)] or a gavage of placebo beadlets (0 mg canthaxanthin) 5 d/wk. Serum canthaxanthin concentrations in the canthaxanthin-fed group increased from 0 at baseline to 37.76 +/- 5.34 nmol/L trans and 77.10 +/- 12.60 nmol/L cis canthaxanthin at 12 mo. Further accumulation of canthaxanthin did not occur with continuous dosing. After 2 y of receiving canthaxanthin beadlets by gavage, the ferrets did not show a detectable concentration of canthaxanthin in the eyes, nor did they have clinical signs of toxicity. Canthaxanthin concentrations were highest in liver, with high concentrations also seen in fat, lung and small intestine. The sum of alpha and beta-carotene concentrations detected in livers was significantly higher in the canthaxanthin-fed group than in the placebo-fed group, but not significantly higher when individual carotenes were compared. However, alpha-tocopherol concentrations in the livers and lungs and lutein/zeaxanthin in the fats of the ferrets fed canthaxanthin were significantly lower than in those fed the placebo. Retinoid concentrations in tissues of the ferrets fed canthaxanthin were not different from those of the placebo-fed group. The effects of canthaxanthin supplementation on other antioxidants and vitamin A nutrients demonstrate either a synergistic or antagonistic relationship, depending on the specific tissue assayed.

Adipose Tissue↗

PubMed1995

Investigation on breastfeeding and lactational amenorrhoeic women in mountainous areas of Pengxian County, Southwest China.

OBJECTIVE: To determine the distributions of the duration of postpartum breastfeeding, amenorrhoea, and contraceptive use, a community-based epidemiological investigation was carried out in Pengxian County, Southwest China in March 1992. METHODS: 1,040 women who had given live births during the reference period were interviewed. A current-status life table analysis was used. RESULTS: At 1 month postpartum, 100% infants were breastfed, at 6 months 95%, and at 12 months 82%. The level of amenorrhoea at 1 month postpartum was 90%, at 3 months 74%, at 6 months 62%, and at 12 months 36%. Contraceptive use was initiated at the second month postpartum with 19% of users, at 6 months 48%, and at 12 months 91%. CONCLUSION: The results indicate that at population level advising women to begin using contraceptives in 3 months postpartum is fairly reasonable, and the non-medicated IUD is recommended to be the first choice for the lactating women.

Adult↗

PubMed1995

Role of endogenous cytokines in endotoxin- and interleukin-1-induced pulmonary inflammatory response and oxygen tolerance.

Endotoxin lipopolysaccharide and the cytokines, tumor necrosis factor (TNF) and interleukin-1 (IL-1), are known to protect adult rats against O2 toxicity. However, whether the effect of endotoxin is mediated by these cytokines is not clear. We have previously demonstrated that depletion of 84% rat alveolar macrophages (AM), which reduced lipopolysaccharide (LPS)-induced release of TNF by 86%, had no effect on LPS-induced O2 tolerance. In this study, we demonstrated that coinsufflation of LPS with anti-TNF antibody and IL-1 receptor antagonist (IL-1ra), which completely inhibited LPS-induced TNF and IL-1 activities, had no effect on LPS-induced alveolar inflammatory response and O2 tolerance. Likewise, coinsufflation of IL-1 and anti-TNF antibody, which completely neutralized IL-1-induced TNF activity, had no effect on IL-1-induced alveolar inflammatory response and O2 tolerance. In contrast, IL-1ra completely abolished IL-1-induced inflammatory response and markedly inhibited IL-1-induced O2 tolerance. These results suggest that LPS-induced alveolar inflammatory response and O2 tolerance are not mediated by endogenous TNF and IL-1. Similarly, endogenous TNF does not mediate IL-1-induced alveolar inflammatory response and O2 tolerance.

Animals↗

PubMed1995

Measurement of carotenoids, retinoids, and tocopherols in human lenses.

PURPOSE: To determine the levels of carotenoids, retinoids, and tocopherols in normal and cataractous human lenses. METHODS: Concentrations of carotenoids, retinoids, and tocopherols were measured by high-performance liquid chromatography (HPLC) in 12 American normal lenses, 9 American cataractous lenses, and 10 Indian cataractous lenses. RESULTS: On a per gram wet weight of tissue basis, human lenses contained 11 to 25 ng xanthophylls (lutein and zeaxanthin), 31 to 50 ng retinol, 21 to 25 ng retinyl palmitate, 1573 to 2550 ng alpha-tocopherol, and 257 to 501 ng gamma-tocopherol. Concentrations of lutein, zeaxanthin, and retinol were significantly higher in Indian cataractous lenses than in American normal or cataractous lenses. There were no differences in the lutein-zeaxanthin, retinoid, or alpha-tocopherol contents between American normal lenses and American cataractous lenses. The range of ratios of lutein to zeaxanthin in human lenses was 1.6 to 2.2. The mean age of the Indian lens donors was 20 years younger than the American lens donors. Comparisons using contralateral lenses indicated that there was significant interindividual variance in human lens concentrations of xanthophylls, retinoids, and tocopherols. beta-carotene and lycopene, major carotenoids in human serum and other tissues, were not detected in human lenses. CONCLUSIONS: Xanthophylls (lutein and zeaxanthin) are the only carotenoids detected in human lens. Retinol, retinyl palmitate, and alpha- and gamma-tocopherols also are present in human lens. Determinants of lens concentration of nutrients are not defined, but dietary factors are likely to be important.

Carotenoids↗

PubMed1995

Children's development effecting blood oxygen desaturation following apnea.

One hundred and fifty-six children aged from 4 months to 12 years undergoing elective plastic surgery were included in this study. All children were ASA physical status I, under normal development, ranging from 64 to 140 cm in body height and from 6.0 to 41.0 kg in body weight. Following 2-minute preoxygenation, the time when SpO2 dropped to 95% and 90% in apneic period had a close correlation with age, weight and height of children by means of linear and non-linear regression analysis. The smaller the children's weight, the higher the incidence of severe arterial desaturation after reinstitution of manual ventilation with 100% oxygen at SpO2 of 90%. It is suggested that younger children are more susceptible to hypoxemia than older ones during apnea and provided no problem existing other than oxygen delivery, an SpO2 of 95% might be the safe limitation of apnea in pediatric anesthesia induction.

Age Factors↗

PubMed1995

Integration of glucoamylase gene from Aspergillus niger into Saccharomyces cerevisiae genome and its stable expression.

Starch digestible delta-integrants were constructed by integrative transformation of a linear YIP plasmid carrying Aspergillus niger glucoamylase cDNA under the control of the MF alpha 1 promoter and its prepro signal and the delta sequence of the Ty element from yeast. The integration of glucoamylase cDNA into Saccharomyces cerevisiae was identified by Southern analysis. The secreted glucoamylase activity of integrants in the medium with soluble starch as a carbon source reached 2.5 u/ml. After ten times of successive transfers in a nonselective medium, the activity of secreted glucoamylase of integrant was approximately at its original level.

Aspergillus niger↗

PubMed1994

A statistical analysis of factors related to symptomatic cerebral vasospasm.

A retrospective review of patients presenting to our institution with aneurysmal subarachnoid hemorrhage between 1980-1990 was accomplished. Eleven variables were examined as to their relationship to clinical vasospasm: age, sex, clinical grade, amount of subarachnoid blood on CT, aneurysm location, incidence of vasospasm, incidence of complications, use of calcium channel blockers, time to surgery, length of stay, and outcome. Data were analyzed with univariate and multivariate logistical regression methodology. By univariate analysis, age under 20, amount of subarachnoid hemorrhage, and clinical grade were associated with a higher risk of vasospasm. Using multivariate logistic regression, these factors, along with age under 35, were correlated as being predictive of clinical vasospasm. When all patients are grouped into either good or bad outcome, and a similar analysis is performed, only in the poor outcome group is the amount of subarachnoid hemorrhage and clinical grade correlated with vasospasm. This suggests that there is a group of patients with a predisposition to vasospasm that is independent of subarachnoid hemorrhage and clinical grade, and that these patients may have a more favorable outcome.

Adolescent↗