Biomedical subjects

B Xu

Publications and source records attributed to B Xu.

405 records · Page 23Linked to original sources

PubMedDate not supplied

Ultrastructural changes of nucleoli in common wheat induced by actinomycin D.

Common wheat root tip meristematic cells were treated with low concentrations of actinomycin D (ActD), then stained whole by silver nitrate. We showed by transmission electron microscopy that the typical nucleolar structure did not form, but a granular and fibrillar network was exhibited in the nucleolar region. Our results support a correlation between nucleolar organization/assembly and the activation of RNA Polymerase I transcription. Furthermore, we speculate that the fibrillar network present in the nucleolar region of ActD treated cells may represent the basic skeletal structure required to support the nucleolus.

Cell Nucleolus↗

PubMedDate not supplied

Maternal determinants of birth weight: a population-based sample from Qingdao, China.

This analysis examines the relationship between maternal determinants and birth weight in a population-based birth cohort of 5,284 mothers with singleton births of 28 completed gestational weeks in Qingdao, China, in 1992. Multiple linear regression models suggest that the length of the menstrual cycle, age at menarche, maternal weight, maternal height, parity, and number of antenatal visits had independent effects on birth weight after controlling for gestational age and sex of infant. The estimated difference in mean birth weight for each year after menarche was 11.7 g (95 per cent CI 4.6-18.8), and for each day of the menstrual cycle was 4.0 g (95 per cent CI, 2.1-6.0), after controlling for gestational age, sex of infant, maternal height, maternal weight, parity and the number of antenatal visits. No substantial differences in determinants of birth weight were found between the sexes. Maternal age, education, and occupation failed to reveal any significant association with birth weight. In sum, those women who reached menarche younger and had a relatively short menstrual cycle had a heavier baby on average, and the determinants of birth weight did not differ between male and female in the cohort.

Adolescent↗

PubMedDate not supplied

Sex differentials in perinatal mortality in China and Finland.

This study describes patterns of sex differentials in perinatal mortality in China and Finland. The analysis is based on three population-based one-year birth cohorts, one from Qingdao, China, in 1992 and two from Northern Finland in 1966 and 1985-86, comprised of 9,219, 11,422 and 9,207 singletons with at least 28 gestational weeks and 1000 g in birthweight, respectively. Both Finnish cohorts had an excess of male over female perinatal deaths, but in the Chinese cohort girls were more likely to die than boys. The adjusted odds ratio (OR) of perinatal mortality for boys was 1.31 (95 per cent confidence interval [CI] 0.98, 1.78) and 1.57 (95 per cent CI 0.89, 2.78) in the Finnish 1966 and 1985-86 cohorts, respectively, and 0.82 (95 per cent CI 0.55, 1.20) in the Chinese cohort. The corresponding figure for stillbirths in the Chinese was 0.57 (95 per cent CI 0.33, 0.98), which could explain the total excess of female deaths during the perinatal period. Our results suggest that the role of different social and cultural environments on the existing sex differentials in perinatal mortality between the countries needs further evaluation.

Adolescent↗

PubMedDate not supplied

Maternal smoking in pregnancy and sex differences in perinatal death between boys and girls.

The sex difference in perinatal mortality in developed countries is largely unexplained. The current study evaluated the differences in the impact of maternal smoking during pregnancy on the risk of perinatal death between males and females. The analysis involved 11,469 and 9,404 newborns derived from two population-based birth cohorts in Northern Finland, for 1966 and 1985-86, respectively. The perinatal mortality rate was 23 per thousand in the 1966 cohort and 9 per thousand in the 1985-86 cohort. The rate ratio (RR) for mortality for males over females is 1.15 and 1.60 in the two cohorts, respectively. Among children whose mothers smoked during pregnancy, the RR was 2.2 (95% CI 1.0, 4.7) for the former cohort and 4.8 (95% CI 1.5, 15.2) for the later cohort; and among the children whose mothers did not smoke the corresponding RR was 1.2 (95% CI 0.9, 1.6) and 1.1 (95% CI 0.6, 1.9). Maternal smoking during pregnancy could be an important determinant accounting for the excess perinatal death for males over females. Our results encourage evaluation of the findings among other populations.

Female↗

PubMedDate not supplied

Establishment of fluorescein diacetate and ethidium bromide (FDAEB) assay for quality assessment of isolated islets.

One of the most important factors in clinical islet transplantation is isolation of a great number of islets with good viability. According to viability assessments of isolated islets, the static incubation test and the perifusion test of islets, which are used retrospectively, take much time and need various apparatus. But viability assessments of isolated islets for clinical islet transplantation require a simple, rapid, sensitive, and prospective method. We have developed a microfluorometric viability assay for isolated human, porcine, and dog islets of pancreata using fluorescein diacetate and ethidium bromide (FDAEB). Fluorescein diacetate (FDA) causes live cells to fluoresce green under blue light excitation (490 nm) and ethidium bromide (EB) causes dead cells to fluoresce red. In this study, we investigated the applicability of FDAEB staining to quality assessment of isolated islets for clinical use by correlation with the counting method with insulin secretion of islets. Discrimination of living from dead islets by insulin secretion correlated well with viability as determined by FDAEB staining. The proportion of living islets within isolated canine islets, as measured by microfluorometric counting, was found to correlate highly significantly on low-temperature (24 degrees C) culture (R = 0.831, p < 0.001) and on 37 degrees C culture (R = 0.553, p < 0.05) with the insulin contents of the same islets. Therefore, it is possible to differentiate degrees of viability, and a scoring system is described for this purpose. The FDAEB assay prospectively and easily provides a rapid, accurate, and objective measurement of the proportion of living cells and dead cells in isolated islets for clinical islet transplantation.

Animals↗

PubMedDate not supplied

Novel method for isolation of adult porcine pancreatic islets with two-stage digestion procedure.

It is particularly difficult to isolate porcine islets (PI). Experience suggests that the success rate of porcine islet isolation (PII) is probably considerably influenced by the distension and digestion of the pancreas. In this study, we divided the digestion procedure into two stages and developed a new enzyme solution to improve both the distension and digestion procedures. As a result, we established a novel and stable method of large-scale adult porcine islet isolation (APII). The harvested pancreata of 2-year-old pigs weighing over 200 kg (n = 18) were distended by introducing our new enzyme solution gently and slowly through the pancreatic ducts. Two-stage digestion (cold, then warm) was then performed by first placing the distended pancreata on ice for 2 h to cause diffusion of the enzyme solution around the islets, and then by incubating the pancreata in a water bath at 37 degrees C for 45 min without shaking. The islets were purified by a COBE 2991 cell processor on dextran T70 discontinuous density gradients. Histological study was performed on porcine pancreata sampled after 0, 15, 30, and 45 min of the second stage, and stained with H&E stain. Next, islet equivalent was calculated. Static incubation study was performed by stimulating the islets with 3.3 and 16.7 mM glucose in Krebs' Ringer bicarbonate buffer (KRBB) solution at 37 degrees C for 1 h, and finally the insulin released was measured. The dilated acinar cells septa around the islets were observed at time 0. Destruction of the acinar cells around the islets by warm digestion was recognized at 15 and 30 min, and destroyed and separated acinar cells present around the islets at 45 min. During the entire course of the warm digestion, the islets remained intact. The number of isolated islets was 291,667 +/- 240,452 IEQ/pancreas (n = 14) and 3,294 +/- 2199 IEQ/g of pancreatic tissue. The purity of recovered porcine islets was over 90%. The concentration of the insulin secreted by 10,000 IEQ islets selected at random was 83.9 +/- 13.4 microU/dish/h in response to 3.3 mM glucose and 104.1 +/- 12.9 microU/dish/h in response to 16.7 mM glucose (n = 20). A success rate of approximately 80% was attained with APII. We demonstrated that this increase in the success rate was due to the improved distension and digestion provided by this method. This two-stage APII method with its new enzyme solution may facilitate the future use of porcine islets in clinical xenotransplantation trials.

Animals↗

PubMedDate not supplied

Effects of cancer chemotherapy on the blood fibrinogen concentrations of cancer patients.

Blood fibrinogen concentrations and glutamic-pyruvic transaminase activities of 66 adult cancer inpatients (aged 22 - 70 years) were determined both before and after one or two chemotherapy regimens. The percentage of hepatoma patients with abnormal blood fibrinogen levels (< 1.5 or > 6.0 g/l) was higher (64.3% of 14 patients) than that in other cancer categories (19.2% of 52 patients). The mean blood fibrinogen concentrations of male (3.5 g/l) and female (4.5 g/l) cancer patients were higher than those previously reported for healthy humans (2.8 and 2.9 g/l, respectively). After chemotherapy, blood fibrinogen concentrations decreased in patients whose primary tumours were surgically removed (from 4.8 to 3.2 g/l) but increased (from 3.0 to 4.8 g/l) in those who did not undergo surgery. Glutamic-pyruvic transaminase activities did not appear to be related to blood fibrinogen levels. We conclude that the increase in mean blood fibrinogen levels of cancer patients is probably related to tumour growth. Different mechanisms may operate in patients with hepatoma.

Adolescent↗

PubMedDate not supplied

Effect of anti-cancer drugs on the binding of 125I-Fibrinogen to two leukaemia cell lines in vitro.

Anti-cancer drugs may be able to inhibit tumour growth and metastasis by blocking fibrinogen- and/or fibrin-related pathways. To test this hypothesis, the effect of various anti-neoplastic drugs on the binding of 125I-Fibrinogen to two leukaemia cell lines, HL60 and P388, was investigated. All the drugs tested inhibited the binding of fibrinogen to leukaemia cells. This effect was particularly marked for drugs that act as inhibitors of protein synthesis. Since these anti-neoplastic drugs do not have anti-coagulant actions, these results provide evidence for the potential of targeting tumour fibrinogen as a new form of cancer chemotherapy.

Antineoplastic Agents↗

PubMedDate not supplied

Effect of cadmium and cigarette smoking on human semen quality.

OBJECTIVE: In recent years, there have been many nonconclusive studies on cigarette smoking and sperm quality. Few studies, if any, have attempted to implicate any decrease of sperm quality. The aim of this study was to examine the relationship between cigarette smoking, blood and seminal plasma concentrations of cadmium and lead, and sperm quality. METHODS: A total of 184 males who were undergoing initial screening for infertility were included in the study. Tests conducted included semen characteristics (volume, total sperm count, sperm viability, motility and morphology of spermatozoa), and blood and seminal plasma concentrations of lead and cadmium. RESULTS: More than 50% and 70% of the subjects had normal sperm density and motility, respectively. The mean concentrations of lead in blood (PbB) and seminal plasma (PbS) were 7.09 micrograms/dL and 12.98 micrograms/L, respectively, while the mean concentrations of cadmium in blood (CdB) and seminal plasma (CdS) were 0.95 micrograms/L, and 0.58 micrograms/L, respectively. Significant correlations were observed between CdB and cigarette-years and sperm density (negative). CdS was significantly correlated with cigarette-years and sperm volume (negative). Significant trends were observed for different categories of cigarette-years with CdB, CdS and sperm density. CONCLUSION: Cigarette smoking appears to affect sperm density, especially in heavy smokers. Cadmium (present) in cigarettes could be a possible causative agent for the low sperm density among smokers.

Adult↗