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Biomedical subjects

B Yang

Publications and source records attributed to B Yang.

At least 127 records · Page 7Linked to original sources
PubMed2000

Skeletal muscle function and water permeability in aquaporin-4 deficient mice.

It has been proposed that aquaporin-4 (AQP4), a water channel expressed at the plasmalemma of skeletal muscle cells, is important in normal muscle physiology and in the pathophysiology of Duchenne's muscular dystrophy. To test this hypothesis, muscle water permeability and function were compared in wild-type and AQP4 knockout mice. Immunofluorescence and freeze-fracture electron microscopy showed AQP4 protein expression in plasmalemma of fast-twitch skeletal muscle fibers of wild-type mice. Osmotic water permeability was measured in microdissected muscle fibers from the extensor digitorum longus (EDL) and fractionated membrane vesicles from EDL homogenates. With the use of spatial-filtering microscopy to measure osmotically induced volume changes in EDL fibers, half times (t(1/2)) for osmotic equilibration (7.5-8.5 s) were not affected by AQP4 deletion. Stopped-flow light-scattering measurements of osmotically induced volume changes in plasmalemma vesicles also showed no significant differences in water permeability. Similar water permeability, yet approximately 90% decreased AQP4 protein expression was found in EDL from mdx mice that lack dystrophin. Skeletal muscle function was measured by force generation in isolated EDL, treadmill performance time, and in vivo muscle swelling in response to water intoxication. No differences were found in EDL force generation after electrical stimulation [42 +/- 2 (wild-type) vs. 41 +/- 2 (knockout) g/s], treadmill performance time (22 vs. 26 min; 29 m/min, 13 degrees incline), or muscle swelling (2.8 vs. 2.9% increased water content at 90 min after intraperitoneal water infusion). Together these results provide evidence against a significant role of AQP4 in skeletal muscle physiology in mice.

Animals↗
PubMed2000

Role of aquaporin water channels in pleural fluid dynamics.

Continuous movement of fluid into and out of the pleural compartment occurs in normal chest physiology and in pathophysiological conditions associated with pleural effusions. RT-PCR screening and immunostaining revealed expression of water channel aquaporin-1 (AQP1) in microvascular endothelia near the visceral and parietal pleura and in mesothelial cells in visceral pleura. Comparative physiological measurements were done on wild-type vs. AQP1 null mice. Osmotically driven water transport was measured in anesthetized, mechanically ventilated mice from the kinetics of pleural fluid osmolality after instillation of 0.25 ml of hypertonic or hypotonic fluid into the pleural space. Osmotic equilibration of pleural fluid was rapid in wild-type mice (50% equilibration in <2 min) and remarkably slowed by greater than fourfold in AQP1 null mice. Small amounts of AQP3 transcript were also detected in pleura by RT-PCR, but osmotic water transport was not decreased in AQP3 null mice. In spontaneously breathing mice, the clearance of isosmolar saline instilled in the pleural space ( approximately 4 ml. kg(-1). h(-1)) was not affected by AQP1 deletion. In a fluid overload model produced by intraperitoneal saline administration and renal artery ligation, the accumulation of pleural fluid (approximately 0.035 ml/h) and was not affected by AQP1 deletion. Finally, in a thiourea toxicity model of acute endothelial injury causing pleural effusions and lung interstitial edema, pleural fluid accumulation in the first 3 h ( approximately 4 ml. kg(-1). h(-1)) was not affected by AQP1 deletion. These results indicate rapid osmotic equilibration across the pleural surface that is facilitated by AQP1 water channels. However, AQP1 does not appear to play a role in clinically relevant mechanisms of pleural fluid accumulation or clearance.

Animals↗
PubMed2000

Existence of a transient outward K(+) current in guinea pig cardiac myocytes.

A novel transient outward K(+) current that exhibits inward-going rectification (I(to.ir)) was identified in guinea pig atrial and ventricular myocytes. I(to.ir) was insensitive to 4-aminopyridine (4-AP) but was blocked by 200 micromol/l Ba(2+) or removal of external K(+). The zero current potential shifted 51-53 mV/decade change in external K(+). I(to.ir) density was twofold greater in ventricular than in atrial myocytes, and biexponential inactivation occurs in both types of myocytes. At -20 mV, the fast inactivation time constants were 7.7 +/- 1.8 and 6.1 +/- 1.2 ms and the slow inactivation time constants were 85.1 +/- 14.8 and 77.3 +/- 10.4 ms in ventricular and atrial cells, respectively. The midpoints for steady-state inactivation were -36.4 +/- 0.3 and -51.6 +/- 0.4 mV, and recovery from inactivation was rapid near the resting potential (time constants = 7.9 +/- 1.9 and 8.8 +/- 2.1 ms, respectively). I(to.ir) was detected in Na(+)-containing and Na(+)-free solutions and was not blocked by 20 nmol/l saxitoxin. Action potential clamp revealed that I(to.ir) contributed an outward current that activated rapidly on depolarization and inactivated by early phase 2 in both tissues. Although it is well known that 4-AP-sensitive transient outward current is absent in guinea pig, this Ba(2+)-sensitive and 4-AP-insensitive K(+) current has been overlooked.

4-Aminopyridine↗
PubMed2000

Aquaporin-4 is expressed in basolateral membranes of proximal tubule S3 segments in mouse kidney.

Because of the availability of knockout mouse models to examine renal transport mechanisms, it has become increasingly important to describe the cellular distribution of major renal transporters in mice. We have used immunocytochemistry and freeze-fracture electron microscopy to compare the renal distribution of aquaporin-4 (AQP4) with that previously described in rat. In rat kidney AQP4 is present exclusively in basolateral membranes of collecting duct principal cells. In mice, however, AQP4 was also detected by immunocytochemistry in basolateral membranes of proximal tubule S3 segments, and not detected in S1 and S2 segments of proximal tubule. Freeze-fracture electron microscopy revealed orthogonal arrays of intramembrane particles (OAPs) on the basolateral membranes of the S3 segment. In AQP4-knockout mice, immunostaining was absent and OAPs were found neither in collecting ducts nor in the S3 segment of the proximal tubule. The urinary concentrating capacity after deletion of both AQP1 and AQP4 was further reduced compared with that of AQP1 or AQP4 null mice, suggesting an additive effect of AQP1 and AQP4 in the concentrating mechanism. The functional significance of the apparent species-dependent expression of AQP4 in proximal tubules is unknown, but may relate to physiological differences between rats and mice.

Animals↗
PubMed2000

Effects of traditional classroom and distance continuing education: a theory-driven evaluation of a vaccine-preventable diseases course.

OBJECTIVES: This study evaluated the effects of a major federal immunization continuing education course, delivered in both traditional classroom and satellite broadcast versions, on public health professionals' knowledge, agreement, self-efficacy, and adherence in practice to recommendations. METHODS: The study used a comparative time series design to determine whether the course influenced participants' knowledge, agreement, self-efficacy, and adherence in practice to general and polio-specific recommendations as measured immediately and 3 months after the course. It also compared the effects of the classroom and satellite broadcast versions and used path analysis to show how the outcomes were related to one another. RESULTS: Both versions significantly improved knowledge, agreement, self-efficacy, and adherence. Knowledge and agreement were significant predictors of self-efficacy, which directly predicted adherence. Vaccine availability and supportive clinic policies were also important adherence predictors. CONCLUSIONS: A well-designed training update can change provider knowledge, agreement, self-efficacy, and adherence. Traditional classroom and distance training can have comparable effects. The findings support incorporation of distance learning in national public health training, if the distance learning is used wisely in relation to training needs, goals, and practice contexts.

Analysis of Variance↗
PubMed2000

Culture and the economy.

In a sample of 18 industrialized nations, measures of national character did not improve the power of socioeconomic variables in predicting unemployment rates.

Cross-Cultural Comparison↗
PubMed2000

Who buys their textbooks online?

A pilot study of 82 undergraduates indicated that skills with computers and Internet use predicted purchasing textbooks online.

Adult↗
PubMed2000

[Exogenous lactate sustains synaptic activity and neuronal viability, but fails to induce long-term potentiation (LTP)].

In Alzheimer's disease, brain glucose metabolic ratio decreases, whereas the brain lactate metabolic ratio increases. To investigate possible synaptic dysfunction in Alzheimer's disease, we examined the effects of exogenous glucose deprivation and replacement of glucose with lactate on the synaptic transmission, synaptic plasticity, and the morphological integrity of hippocampal neurons. Synaptic activity was estimated by the amplitude of the population spike (PS) recorded in the granular cell layer in the hippocampal slices from guinea pig and rat. Exogenous glucose deprivation caused the immediate depression of PS. Replacement of glucose with lactate induced transient decrease of PS, followed by spontaneous recovery of synaptic transmission. Neural activity recovered from transient glucose deprivation became resistant to the replacement of glucose with exogenous lactate. Glucose-supported synaptic transmission exhibited approximately 140% enhancement of PS (LTP). However, lactate-supported synaptic activity yielded approximately 110% potentiation of PS. Effects of exogenous glucose and lactate on the cell viability were examined by the propidum iodide uptake and LDH release in the organotypic hippocampal slice cultures. Hippocampal slice cultures incubated in medium containing 10 mM lactate suppressed the cell death during 48 h observation as well as those in the 10-30 mM glucose containing medium. These results indicate that lactate can sustain the neural transmission and support the morphological integrity of hippocampal neurons, but failed to induce LTP, which could at least in part, cause the memory impairment in Alzheimer's disease.

Animals↗
PubMed2000

[Loss of imprinting of insulin-like growth factor II gene in acute myeloid leukemia].

OBJECTIVE: To investigate the status of insulin- like growth factor-2(IGF-2) gene imprinting in acute myeloid leukemia(AML). METHODS: Selection of heterozygous cases for Apa I polymorphism within exon 9 of IGF-2 gene and further analysis of loss of imprinting(LOI) were done in 26 AML patients by polymerase chain reaction(PCR), reverse transcription PCR (RT-PCR) and restriction fragment length polymorphism(RFLP) technique. RESULTS: Eleven cases of AML patients were identified as heterozygous for IGF-2(11/26); 8 heterozygous patients showed biallelic expression of IGF-2, indicating loss of IGF-2 imprinting. CONCLUSION: The frequent LOI of IGF-2 may play a role in the development of acute myeloid leukemia.

Adolescent↗
PubMed2000

Childhood stress leads to later suicidality via its effect on cognitive functioning.

The present study examined the etiology of suicidal behavior from cognitive and developmental perspectives in a sample of 181 suicidal and nonsuicidal college students. We hypothesized that cognitive functioning would serve as a mediator between early life events and suicidal behavior. The present study examined child maltreatment, family instability, and poor general family environment as early negative life events, and examined self-esteem, locus of control, hopelessness, and problem-solving deficits as cognitive factors. In addition, individuals' perceived social support before age 18 and current social support and life stress were also examined in relation to the preceding variables. A series of structural equation analyses indicated that early negative life events have a mild impact on suicidal behavior, but a stronger impact on cognitive deficits, which in turn have a strong impact on suicidal behavior.

Adult↗
PubMed2000

Senescent ventricular dysfunction: issues related to cardiopulmonary bypass.

The mean age of the open-heart surgical patient is increasing every year. Therefore, it is logical to define the aging-related changes in cardiovascular function. This study set forth to define the major molecular and performance alterations that occur in the left ventricle related to advanced aging or senescence. In the human, vascular pathologies usually accompany left ventricular dysfunction. The aim of this study was to associate the altered left ventricular mechanics with molecular pathways in mice who lacked these associated vascular pathologies. This study compared the left ventricular function of two groups of mice (N = 20 each), 6 months old and 16 months old (senescent). The mice were anesthetized with urethane and alpha-chloralose, and a Millar 1.4 Fr. conductance micromanometer catheter was placed into the left ventricle for acquisition of pressure-volume loops. Heart tissues were collected immediately for analysis of cGMP concentrations. The cardiac index, preload recruitable stroke work, and the slope (Ees) of the end-systolic pressure volume relationship were significantly less in the senescent group compared to the young mice. It was concluded that the aged heart has significantly reduced systolic and diastolic dysfunction compared to the young heart function and that this dysfunction may be related to pathways leading to increased myocardial cGMP concentrations.

Age Factors↗
PubMed2000

[Long-term monitoring of artificial vagina reconstructed with sigmoid colon].

OBJECTIVE: To observe the influence of the artificial plastic vagina on overall patient health. METHODS: Length and width of the artificial vagina were measured. Histological studies were performed under light and electron microscope. Vaginal bacterial flora were analyzed using the drop-implant method. Vaginal HPV and ER were detected with ABC histochemical staining. RESULTS: According to the results of anatomic measurements, artificial vagina was similar to normal vagina. The reductions of glands in the mucosa and collagen fibers as well as interstitial tissue hyperplasia in the lower segment of artificial vagina were documented. Four kinds of bacteria indigenous to the sigmoid colon were found in artificial vagina and were studied microbiologically with only differences in the amount and detection rates of bacteria flora. The positive presentation of HPV was not significantly different from that in the control group. The positive presentation of estrogen receptor (ER) in the epithelium of artificial vagina was not found. CONCLUSION: The reconstruction of artificial vagina with sigmoid colon is a safe, effective and satisfactory procedure for the patient.

Adolescent↗
PubMed2000

[Effects of serum and decidual tissue fluid in early pregnant women on natural killer cells activity and lymphocyte proliferation].

OBJECTIVE: To study the effects of serum and decidual tissue fluid in early pregnant women on natural killer cells (NK cells) activity and lymphocyte proliferation. METHOD: The effects of the serum and decidual tissue fluid obtained from 32 normal early pregnant women on NK cells activity and lymphocyte proliferation were tested by isotope incorporation methods. Sera of 25 nonpregnant women were chosen as controls. RESULTS: The NK cells activity and lymphocyte proliferation of sera and decidual tissue fluids from early pregnant women were lower than those of sera from nonpregnant women (P < 0.01). So were those of decidual tissue fluid as compared with sera during early pregnancy (P < 0.005). CONCLUSIONS: Serum and decidual tissue fluid from early pregnant women expressed immunosuppressive effects. It is possible that these effects of decidual tissue fluid play an important role in regulating local immune status of pregnant uterus.

Adult↗
PubMed2000

Pancreatic insulinomas: experience in 220 patients.

OBJECTIVE: To summarize the experience in the diagnosis and treatment of insulinoma. METHODS: We retrospectively reviewed 220 patients with insulinoma confirmed surgically in the PUMC Hospital from 1953 to 1999. They were 131 men and 89 women, aged on average 39 years. RESULTS: In the 220 patients, the average interval from the onset of symptoms to diagnosis was 35 months. 54% of the patients were misdiagnosed before admission to the hospital. In 214 patients underwent operation, 201 (93.9%) had benign tumor and 12 (5.6%) malignant one. The diameter of 78% tumors was less than 2cm. 90.7% tumors were single and 9.3% were multiple. 37.1% tumors were located in the head and uncinate process of the pancreas, 26.1% in the body, 36.1% in the tail, and 0.7% ectopic. 95.5% patients had Whipple's triad and the ratio of insulin to glucose was greater than 0.3 in 89% patients. The positive rates of B-ultrasound, CT and MRI for localization before operation were low, but those of angiography and PTPC were 62.8% and 88% respectively. Most patients could be cured by simple enucleation of tumor. The main complications were pancreatic fistulae and pancreatitis. CONCLUSION: It is important for surgeons to familiarize with insulinoma, the most common islet cell tumor, for a better treatment.

Adult↗
PubMed2000

[Photodynamic therapy of hematoporphyrin derivative on human pancreatic carcinoma cell lines].

OBJECTIVE: To observe the effect of photodynamic therapy (PDT) on human pancreatic carcinoma cell lines in vitro. METHODS: Two lines of human pancreatic carcinoma cell P3 and SW1990 were studied to investigate the killing role of PDT with hematoporphyrin derivative (HPD) as photosensitizer and sodium lamp as light source. The cultured cells were treated with serial concentrations of HPD followed by irradiation of different dosages of visible light, then MTT colorimetric assay was applied to measure the relative inhibitory rate of PDT for the cells. RESULTS: The relative inhibitory rate of PDT for the cells elevated along with the increase in the concentration of sensitizer and dose of light. Under the low photodynamic dose, it increased rapidly, and gradually slowed down to reach the plateau. Under the same photodynamic dose, significant difference in the inhibitory rate between the two lines was observed (P < 0.01), and the LD90 was also different. CONCLUSIONS: PDT has a significant killing effect on human pancreatic carcinoma cell lines in vitro, and its relative inhibitory rate appears to be correlated with the dose of sensitizer and light irradiation. The sensitivity of the two cell lines to PDT is different.

Cell Line, Tumor↗
PubMed2000

[In vitro antiviral activity of antisense oligonucleotides against influenza virus].

For developing of antisense oligonucleotides as potential antiviral therapeutic agents against influenza A virus, phosphorothioate oligodeoxynucleotides(PS-ODN) targeted to part to the 3' and 5' end sequences which are common to the eight RNAs of type A influenza virus were synthesized. The in vitro cytotoxicity of these PS-ODNs was assayed and then antiviral activity of these PS-ODNs was evaluated by using cultured MDCK cells infected by A/JingFang/86-1(H1N1). It was found that(1) No in vitro cytotoxicity was seen when concentration of PS-ODN was up to 50 mumol/L. (2) Oligonucleotides(IV4 #) complementary to 5' terminal conserved sequences and ODN(IV6 #, IV7 #)composed by 3'/5' terminal conserved sense sequences or antisense sequences all exhibited the most potent antiviral activity. IV4 # ODN exhibited significant antiviral activity with reduced hemegglutination titer about 50% at concentration of 1 mumol/L, and over 70% at 10 mumol/L. The antiviral activity of IV4 # was in a dose- and sequence-dependent manner. (3) IV4 # ODN showed significant antiviral activity not only against H1N1 subtype strains of influenza virus, but also against H3N2 subtype strains. (4) The multiplicity of infection(MOI) of influenza virus had effects on antiviral activity of IV4 # ODN. IV4 # ODN showed better dose-dependent antiviral activity when there was lower MOI. These results suggested the the 3'/5' terminal sequences of influenza A virus could be used as a target for designing antiviral oligonucleotides against influenza A virus.

Animals↗
PubMed2000

[The research progress of using electromagnetic technology in treatment of bone diseases].

In these years, the study of the bioeffects of electromagnetic fields (EMFs) has been listed as the national important task in the field of biological physics. Using EMFs to treat bone diseases is associated with electric technology, biology and medicine. Previous medical studies have shown that EMFs can stimulate healing in bone fractures. But the effects are still controversial and the mechanism is not yet clear. Therefore, it is necessary to carry out experiments in vitro at cellular and molecular levels. Research workers have been exploring the effects of EMFs on bone formation and metabolism. The suggestion of using EMFs in the treatment of osteoporosis and other osseous diseases has been put forward.

Animals↗