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Biomedical subjects

Y P Fan

Publications and source records attributed to Y P Fan.

16 recordsLinked to original sources
PubMed2001

Inducible and neuronal nitric oxide synthase involvement in lipopolysaccharide-induced sphincteric dysfunction.

We examined the effect of endotoxin lipopolysaccharide (LPS) on the basal tone and on the effects of different stimuli and agonists and transcriptional and translational expression of nitric oxide (NO) synthase (NOS) isozymes in the lower esophageal sphincter (LES), pyloric sphincter (PS), and internal anal sphincter (IAS). NO release was also examined before and after LPS. LPS caused a dose-dependent fall in the basal tone and augmentation of the relaxation caused by nonadrenergic, noncholinergic (NANC) nerve stimulation in the LES and IAS. In the PS, LPS had no significant effect on the basal tone and caused an attenuation of the NANC relaxation and an augmentation of the contractile response of muscarinic agonist. Interestingly, the smooth muscle relaxation by atrial natriuretic factor was suppressed in the LES and IAS but not in the PS. These changes in the sphincteric function following LPS may be associated with increase in the inducible NOS (iNOS) expression since they were blocked by iNOS inhibitor L-canavanine. Augmentation of NANC relaxation in the LES and IAS smooth muscle by LPS may be due to the increased activity of neuronal NOS and NO production.

Anal Canal↗
PubMed2001

[Antifebrile effect of naoreqing oral liquid on post-operational fever of glioma or meningioma patients].

OBJECTIVE: To observe the antifebrile effect of Naoreqing (NRQ) oral liquid on fever in patients after glioma or meningioma operation. METHODS: Patients were divided into 3 groups, the TCM group treated with NRQ, the TCM-WM group treated with NRQ plus western medicine and the WM group treated with western medicine alone. The treatment was applied for 7 successive days. The mean time of fever and fever subsidence, body temperature before and after treatment were recorded and compared. RESULTS: The antifebrile effect in the TCM and the TCM-WM group was superior to that in the WM group significantly (P < 0.01), and the difference between the TCM group and the TCM-WM group was insignificant. CONCLUSION: NRQ can evidently reduce the body temperature of patients after brain tumor operation, its antifebrile effect is irrelevant to the kind of tumor being glioma or meningioma.

Adolescent↗
PubMed2000

Biophysical characterization of rat caudal hypothalamic neurons: calcium channel contribution to excitability.

Neurons in the caudal hypothalamus (CH) are responsible for the modulation of various processes including respiratory and cardiovascular output. Previous results from this and other laboratories have demonstrated in vivo that these neurons have firing rhythms matched to the respiratory and cardiovascular cycles. The goal of the present study was to characterize the biophysical properties of neurons in the CH with particular emphasis in those properties responsible for rhythmic firing behavior. Whole cell, patch-clamped CH neurons displayed a resting membrane potential of -58.0 +/- 1.1 mV and an input resistance of 319.3 +/- 16.6 MOmega when recorded in current-clamp mode in an in vitro brain slice preparation. A large proportion of these neurons displayed postinhibitory rebound (PIR) that was dependent on the duration and magnitude of hyperpolarizing current as well as the resting membrane potential of the cell. Furthermore these neurons discharged tonically in response to a depolarizing current pulse at a depolarized resting membrane potential (more positive than -65 mV) but switched to a rapid burst of firing to the same stimulus when the resting membrane potential was lowered. The PIR observed in these neurons was calcium dependent as demonstrated by the ability to block its amplitude by perfusion of Ca(2+)-free bath solution or by application of Ni(2+) (0.3-0.5 mM) or nifedipine (10 microM). These properties suggest that low-voltage-activated (LVA) calcium current is involved in the PIR and bursting firing of these CH neurons. In addition, high-voltage-activated calcium responses were detected after blockade of outward potassium current or in Ba(2+)-replacement solution. In addition, almost all of the CH neurons studied showed spike frequency adaptation that was decreased following Ca(2+) removal, indicating the involvement of Ca(2+)-dependent K(+) current (I(K,Ca)) in these cells. In conclusion, CH neurons have at least two different types of calcium currents that contribute to their excitability; the dominant current is the LVA or T-type. This LVA current appears to play a significant role in the bursting characteristics that may underlie the rhythmic firing of CH neurons.

Action Potentials↗
PubMed1999

Mechanism of inhibition of VIP-induced LES relaxation by heme oxygenase inhibitor zinc protoporphyrin IX.

The putative heme oxygenase inhibitor zinc protoporphyrin IX (ZnPP IX) is known to exert diverse actions, including inhibitory action on smooth muscle relaxation by vasoactive intestinal polypeptide (VIP). The studies were performed in the opossum lower esophageal sphincter (LES) smooth muscle to determine the site of the inhibitory action of ZnPP IX in the smooth muscle relaxation by VIP. We also examined the effect of a direct Gs protein activator, cholera toxin (CTX), known to stimulate adenylate cyclase (AC). CTX caused relaxation of the LES smooth muscle by its action directly at the smooth muscle cells. The convergence of the common mechanisms of actions of VIP and CTX on AC was determined by the suppression of their effects by the AC inhibitor and CTX desensitization. ZnPP IX caused attenuation of the LES smooth muscle relaxation by VIP but not by CTX. ZnPP IX but not zinc deuteroporphyrin IX caused significant inhibition of VIP binding to the membrane receptor. We conclude that ZnPP IX attenuates VIP-induced LES smooth muscle relaxation by inhibition of VIP binding to G protein-coupled receptors linked to AC at a point proximal to G protein activation.

Adenylyl Cyclase Inhibitors↗
PubMed1999

Mechanism of action of cholera toxin on the opossum internal anal sphincter smooth muscle.

Cholera toxin (CTX), an activator of G(s) protein, is an important pharmacological tool in G protein research. The effect and the mechanism of action of CTX in the gastrointestinal smooth muscle, including the internal anal sphincter (IAS), are not known. The present investigation was carried out to examine the effects of CTX on the signal transduction associated with the adenylate cyclase (AC) pathway on the basal tone of the IAS smooth muscle. CTX caused a prompt and dose-dependent fall in the basal tone of the IAS that was not affected by the neurotoxins TTX and omega-conotoxin or the nitric oxide synthase inhibitor N(G)-nitro-L-arginine. The cyclooxygenase inhibitor indomethacin, cAMP-dependent protein kinase inhibitor Rp-8-bromoadenosine 3',5' cyclic monophosphorothioate inhibited CTX-induced IAS smooth muscle relaxation. Furthermore, CTX caused a concentration-dependent relaxation of the isolated smooth muscle cells (SMC) of the IAS, which was blocked by G(s)alpha antibody (G(s)alpha-Ab). The IAS smooth muscle relaxation was accompanied with an increase in the GTPase activity that was also specifically blocked by G(s)alpha-Ab. We conclude that a major part of the inhibitory action of CTX in the IAS is via the direct response of the SMC that is linked with G(s) protein to the AC pathway. A part of the inhibitory action of CTX on the smooth muscle occurs via the activation of cyclooxygenase pathway. The relative contribution of such actions of CTX in the smooth muscle in the gastrointestinal motility disturbances following cholera infection remains to be determined.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

Developmental aspects and mechanisms of rat caudal hypothalamic neuronal responses to hypoxia.

Previous reports from this laboratory have shown that a high percentage of neurons in the caudal hypothalamus are stimulated by hypoxia both in vivo and in vitro. This stimulation is in the form of an increase in firing frequency and significant membrane depolarization. The goal of the present study was to determine if this hypoxia-induced excitation is influenced by development. In addition, we sought to determine the mechanism by which hypoxia stimulates caudal hypothalamic neurons. Caudal hypothalamic neurons from neonatal (4-16 days) or juvenile (20-40 days) rats were patch-clamped, and the whole cell voltage and current responses to moderate (10% O2) or severe (0% O2) hypoxia were recorded in the brain slice preparation. Analysis of tissue oxygen levels demonstrated no significant difference in the levels of tissue oxygen in brain slices between the different age groups. A significantly larger input resistance, time constant and half-time to spike height was observed for neonatal neurons compared with juvenile neurons. Both moderate and severe hypoxia elicited a net inward current in a significantly larger percentage of caudal hypothalamic neurons from rats aged 20-40 days (juvenile) as compared with rats aged 4-16 days (neonatal). In contrast, there was no difference in the magnitude of the inward current response to moderate or severe hypoxia between the two age groups. Those cells that were stimulated by hypoxia demonstrated a significant decrease in input resistance during hypoxic stimulation that was not observed in those cells unaffected by hypoxia. A subset of neurons were tested independent of age for the ability to maintain the inward current response to hypoxia during synaptic blockade (11.4 mM Mg2+/0. 2 mM Ca2+). Most of the neurons tested (88.9%) maintained a hypoxic excitation during synaptic blockade, and this inward current response was unaffected by addition of 2 mM cobalt chloride to the bathing medium. In contrast, perfusion with the Na+ channel blocker, tetrodotoxin (1-2 microM) or Na+ replacement with N-methyl-D-glucamine (NMDG) significantly reduced the inward current response to hypoxia. Furthermore, the input resistance decrease observed during hypoxia was attenuated significantly during perfusion with NMDG. These results indicate the excitation elicited by hypoxia in hypothalamic neurons is age dependent. In addition, the inward current response of caudal hypothalamic neurons is not dependent on synaptic input but results from a sodium-dependent conductance.

Age Factors↗
PubMed1998

Inhibitory effect of zinc protoporphyrin IX on lower esophageal sphincter smooth muscle relaxation by vasoactive intestinal polypeptide and other receptor agonists.

This study was performed in the opossum lower esophageal sphincter (LES) smooth muscle strips to determine the action of the heme oxygenase inhibitor zinc protoporphyrin IX (ZnPP IX) on the relaxant effect of vasoactive intestinal polypeptide and isoproterenol, which are known to stimulate adenylate cyclase (AC) via G protein coupling, and of the direct activator of AC catalytic subunit forskolin. To investigate the cGMP pathway, we examined the effect of atrial natriuretic factor known to activate the receptor linked to the particulate guanylate cyclase via G protein coupling and that of sodium nitroprusside [nitric oxide (NO) donor], authentic NO and carbon monoxide, which stimulate the intracellular soluble fraction of GC. The smooth muscle relaxation caused by nonadrenergic noncholinergic (NANC) nerve stimulation also was investigated. ZnPP IX caused concentration-dependent attenuation of the relaxant effect of vasoactive intestinal polypeptide, isoproterenol and atrial natriuretic factor without any effect on that of forskolin, sodium nitroprusside, NO and CO. Interestingly, ZnPP IX had no significant effect on the LES relaxation caused by NANC nerve stimulation and the smooth muscle contraction by bethanechol. From these results, we conclude that ZnPP IX attenuates the LES smooth muscle relaxation caused by the stimulation of G protein-coupled receptors to particulate AC and guanylate cyclase. The lack of effect of ZnPP IX on the NANC nerve-mediated LES relaxation suggests either lack of a role of heme oxygenase pathway in the response or an upregulation of NOS leading to normal LES relaxation.

Animals↗
PubMed1997

Comparing patient satisfaction, outcomes and costs between cataract day surgery and inpatient surgery for elderly people.

The study reported in this paper examined the characteristics of elderly people undergoing cataract surgery and compared patient perspectives and satisfaction, outcome, costs, reported health problems and social circumstances of day surgery patients and hospital inpatients. The study sample was drawn from the client database of a health insurance fund and covered 291 people aged 60 years or more who had recently undergone cataract surgery. Overall, both day surgery patients and inpatients indicated a high level of satisfaction with their eye surgery (about 80 per cent for both groups). The majority of patients from both groups reported an improved level of vision, with vision outcome in the day surgery group being as good as in the inpatient group. Overall, inpatient treatment was more costly and involved higher out of pocket expenses. The study results indicate a potential to increase the number of patients undergoing cataract surgery as a day patient procedure. Pre-operative preparation contributed to patient satisfaction and the availability of family and/or social support was an important factor influencing day surgery admission. Whilst patients reporting health problems were less inclined to have cataract surgery than were day patients, this only accounted for one-fifth of the total inpatient group. Developing systematic and appropriate case selection criteria and effective case management will contribute to more efficient use of hospital resources, an increased use of day surgery facilities, and hence a more cost-effective overall cataract surgery service for elderly people.

Aged↗
PubMed1995

[The role of accumbens nucleus in the inhibitory effect of somatic afferent inputs on the defence cardiovascular response and its mechanism].

After Accumbens Nucleus (AC) lesion, the inhibitory effect of deep peroneal nerve (DPN) on the pressor response and ECG-ST changes induced by excitation of dorsomedial nucleus of hypothalamus (DMH) was decreased as compared with that of before lesion (P < 0.05, P < 0.01). Electrical stimulation of AC could elicit prominent depressor response, which could be effectively lessened by microinjection of naloxone into ventral periaqueductal gray (vPAG). Lesion of vPAG could reverse the depressor response to AC stimulation to a slight pressor response (P < 0.01). After lesion of arcuate nucleus of hypothalamus (ARC), the depressor response to AC stimulation almost disappeared, which, again, could be largely mimicked by microinjection of naloxone into ARC.

Animals↗
PubMed1994

[Significance of brainstem auditory evoked potential determination in chronic renal failure and maintenance hemodialysis patients].

Brainstem auditory evoked potentials (BAEP) were measured in 20 chronic renal failure patients and 8 maintenance hemodialysis patients. The BAEP in chronic renal failure patients was showed that wave I, III, V peak latencies (PL) and I-III, I-V interpeak latencies (IPL) were markedly increased. The significant reductions, although not to normal, of wave III, IV PL and I-III, I-V IPL were recorded in postdialysis (average 4.2 months) compared with that in predialysis. A correlation analysis revealed no consistent relationships between plasma proteins, hemoglobin, urea, creatinine serum electrolytes and BAEP PL or IPL. The authors realize that BAEP could be used as a subjective index in deciding the inner ear and nervous system damage in chronic renal failure, and it also provided an electrophysiologic evidence for the relationship of Kidney and ear in traditional Chinese medicine.

Adult↗
PubMed1993

[Enhancing effect of jian pi jin dan on immune functions of normal and cyclophosphamide induced immunosuppressed mice].

UNLABELLED: By means of normal and cyclophosphamide (CY) injected NIH mice, the effect of Jian Pi Jin Dan on immuno-modulation was studied which could treat the "Gan" disease effectively in TCM. RESULTS: Markedly improved the level of serum lysozyme, enhance the phagocytosis of abdominal macrophage. The proliferation of spleen T, B cells, the production of interleukin-1 (IL-1) by macrophage and of interleukin-2 (IL-2) by T cells in normal and CY injected mice were also enhanced. Furthermore, it was able to restore the weight, spleen and thymus index of CY injected mice. This prescription can not only reinforce Spleen, but also regulate Liver, complying to the children's physiological and pathological characteristics.

Animals↗
PubMed1989

[Dose-response of intrathecal morphine for post-cesarean analgesia].

Intrathecal morphine for post-operative analgesia is famous for its quality and safety, but its role in post-Cesarean analgesia is not well established. In this study, we investigate its analgesic effect, complication rate and neonatal outcome under various dosages of morphine. The parturients divided into five groups according to morphine dosage: 0, 0.1, 0.25, 0.5, 1.0 mg respectively. The duration of analgesic effect was 19.1 h in 0.1 mg group, 23.6 h in 0.25 mg group, 28.1 h in 0.5 mg group, 30.5 h in 1.0 mg group. Complication rate increased markedly as more than 0.5 mg morphine was injected. Respiratory inhibition (respiratory rate less than 10/min) that required naloxone treatment had occurred twice in 0.5 and 1.0 mg group respectively. Neonatal outcome did not bear any difference among the five groups. In conclusion, adding 0.1 to 0.25 mg morphine to intrathecal anesthetics can be effectively and safely extended into post-Cesarean analgesia.

Adult↗
PubMedDate not supplied

Development of the Chinese nutrition screen (CNS) for use in institutional settings.

OBJECTIVES: To develop and validate a nutritional screening tool (CNS) for elderly Chinese subjects in the institutional setting. DESIGN: Using the MNA as a guide, a questionnaire was developed appropriate for the Chinese health care system, diet, food customs and culture, using physician assessment for comparison. PARTICIPANTS: 200 men and 200 women aged 65 years or older, approximately equally distributed by age between two cities in China (Hong Kong and Shanghai), were recruited from hospitals and old age homes for the reliability study. 340 men and 527 women were recruited for the validity study. RESULTS: The CNS compared with physician assessments based on two groups, normal or at risk with less than normal nutritional status, had kappa coefficients of 0.5 overall and were as high as 0.8 in Shanghai. CNS was able to identify about 90% of all persons with normal nutritional status and had about a 60% chance of correctly identifying a person at risk with a less than normal nutritional status. CONCLUSION: The CNS can be used in a 2-group classification to identify those who have a normal nutritional status (CNS > or = 21). Those who do not fall into this group should have their nutritional status evaluated in greater detail (CNS score < or = 20). The applicability of screening tools may vary depending on the site and the population characteristics.

Aged↗