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Biomedical subjects

P Yu

Publications and source records attributed to P Yu.

At least 163 records · Page 9Linked to original sources
PubMed1996

[Projections from pontine pneumotaxic center to medullary Bötzinger complex in cats].

Experiments were done on 33 adults cats. After injection of WGA-HRP (5%, 30-60 nl) into the Bötzinger complex, labelled cells were observed in the lateral parabrachial nucleus and the Kölliker-Fuse nucleus. Injection into control sites failed to label the cells in the above two nuclei. Ninety-one respiratory related neurons recorded from the pneumotaxic center were tested by electrical stimulation of the Bötzinger complex. Thirteen neurons (14.3%, inspiratory 11, phase-spanning 2) could be antidromically activated. Results of the present study showed that neurons in the pneumotaxic center sent axons to the Bötzinger complex concerning respiratory control.

Animals↗
PubMed1996

Exercise hemodynamic benefits of rate adaptive ventricular pacing.

OBJECTIVE: To investigate the exercise hemodynamic benefits of activity-sensing rate adaptive ventricular pacing (VVIR) over fixed rate pacing (VVI) mode. METHODS: Activity sensing rate adaptive pacemaker was implanted in 19 patients (13 males and 6 females, mean age 54.8 years) with bradycardia. All patients underwent symptom-limited upright bicycle exercise in VVIR and VVI pacing modes in random order after implantation. With electrocardiogram monitor and M-mode echocardiography, heart rate, stroke volume and cardiac output were measured at rest and at each stage of exercise. RESULTS: All patients were pacemaker dependent, without any spontaneous heart rhythm throughout this study. In the activity sensing ventricular pacing mode, all patients achieved a significant increase in exercise duration compared to fixed rate ventricular pacing mode (mean +/- s, 437 +/- 45 vs 323 +/- 23sec; P < 0.01), with a mean maximum pacing rate of 113 +/- 23ppm. Although the cardiac output was significantly improved in both pacing modes (10.2 +/- 1.4L/min with VVIR and 7.5 +/- 1.1L/min with VVI), the maximum exercise cardiac output in VVIR was increased over VVI by 46% (P < 0.05). Additionally, the stroke volume was significantly increased by 50% or more at rest in VVI mode, but was relatively maintained in VVIR mode (P > 0.05). CONCLUSION: Rate adaptive ventricular pacing can significantly improve the exercise capacity and cardiac output in patients with bradycardia. The increment of exercise cardiac output in VVIR mode is mainly dependent upon the pacing rate during exercise.

Cardiac Output↗
PubMed1996

[Changes of circulating Lps and cytokines in burned patients after anti-endotoxin therapy].

OBJECTIVE: Endotoxin as the inciting agent of cytokines and other mediators, whose high level expression correlates with the septic shock and MOF, has been the one of leading causes of death in ICU. METHODS: For treating sepsis and MOF caused by endotoxin, the anti-lipid A of LPS antibody was used, 19 burned patients whose TBSA varied from 50% to 100% were divided into anti-LPS treatment group and nontreated group. RESULTS: The levels of serum endotoxin, IL-6, IL-8, TNF and soluble IL-2R were lower obviously in patients of anti-LPS group than those of nontreated group (P < 0.05). CONCLUSION: Clinical study surggests that anti-lipid A of LPS antibody can act as an therapeutic agent against gram-negative bacterin infection in burned patients.

Adult↗
PubMed1996

[A study on changes and its mechanisms of intestinal mucosal permeability after severe burn].

The changes in the intestinal mucosal permeability were observed by quantitatively assessing plasma to luminal clearance of 99mTc-labeled DTPA, and the influence of platelet activating factor (PAF) on it was investigated. The results showed that intestinal permeability was significantly elevated after severe burn and was positively correlated with increase in PAF in the intestinal tissue (r = 0.94, P < 0.01). PAF antagonist therapy could significantly attenuate postburn intestinal mucosal permeability. It is concluded that PAF is one of the important factors causing increased intestinal permeability after severe burn.

Animals↗
PubMed1996

[Computed tomography of the ethmoid labyrinth and adjacent structures].

In order to study the relation of ethmoid labyrinth to the adjacent structures, continuous axial CT scan of the ethmoid labyrinth was performed on 9 normal subjects. Meanwhile, coronal and axial CT scans of ethmoid labyrinth were obtained in 20 normal subjects. On an average, 22 scan sections were done on each subject. The relation of ethmoid labyrinth to adjacent structures was observed and the remarkable intersubject variations in this anatomic area were noted. The relation of posterior ethmoid cells or sphenoid sinus to the optic canal, and the relation of internal carotid artery to the sphenoid sinus were clearly demonstrated on axial scans. The detailed anatomic structure of the ostiomeatal complex and the anatomic relation of ethmoid labyrinth to orbit and anterior skull base were revealed by coronal CT scans. CT scan of the paranasal sinuses was of great importance in clinical practice for the purpose of etiological analysis of sinusitis, design of endoscopic sinus surgery and prevention of complication.

Adolescent↗
PubMed1995

Role of antral intramural neural pathways in control of gastric emptying in the pig.

1. The role of antral intramural pathways in the control of antropyloric motility and gastric emptying was evaluated in five conscious pigs equipped with chronic gastric and duodenal cannulae. Neural pathways were divided by transection and re-anastomosis of the antrum 2 cm proximal to the pylorus. Concurrent measurements of gastric emptying, transpyloric flow and antropyloric motility were performed before and 6 weeks after surgery. 2. Antral transection retarded gastric emptying, only 36% of 1000 ml saline being emptied in 30 min compared with 62% before transection. Transection did not alter the number of transpyloric flow pulses (22.0 +/- 4.0 cf. 24.4 +/- 3.2 pre-transection), but reduced (P < 0.01) the volume of flow pulses substantially (8.6 +/- 0.4 cf. 18.7 +/- 1.5 ml pre-transection). 3. Antral transection was associated with a reduction in the rate of distal antral pressure waves (P < 0.05), but no alteration in the rate of phasic low level pressurization of the entire gastric content by gastric contractions (gastric common cavity pressure waves). However, transection was associated with a significant (P < 0.05) shortening of the interval between the onset of gastric common cavity pressure waves, and the onset of lumen-occlusive pyloric pressure waves generated by the same contraction sequence (3.2 +/- 0.3 cf. 7.9 +/- 0.6 s). 4. Transection did not alter the inhibition of antral pressure waves, stimulation of localized pyloric pressure waves, and retardation of gastric emptying produced by infusion of 25% dextrose into the duodenum. 5. These studies suggest that antral intramural nerves regulate the emptying of liquids from the stomach by modulating the timing of pyloric closure in relation to phasic gastric antral and corpus contractions. 6. Distal antral intramural neural pathways do not appear to play a major role in the suppression of antral motor activity produced by duodenal glucoreceptors.

Animals↗
PubMed1995

A retrospective study of the use of cisplatinum-5-fluorouracil neoadjuvant chemotherapy in cervical-node-positive nasopharyngeal carcinoma (NPC).

A retrospective study on 422 nasopharyngeal carcinoma (NPC) patients with cervical nodal metastases treated between 1984 and 1987 was performed. 169 received neoadjuvant chemotherapy (CHEMO) with cisplatinum and 5-fluorouracil for two or three courses prior to definitive radiotherapy and 253 were treated by radical radiotherapy alone (NCHEMO). While the primary tumour (T-stage) prognosticators had been comparable between the two groups, CHEMO had significantly more advanced cervical nodal metastases with bulkier nodes and more low-cervical and supraclavicular nodes (P < 0.05) which could account for its overall worse survival, poorer regional tumour control and a trend towards worse systemic tumour control. The worse regional control in CHEMO for Ho's N1 could be the result of more bulky nodes and more tumours infiltrating the skull base and/or causing cranial nerve(s) palsy. There was no statistical or apparent difference between CHEMO and NCHEMO for the same Ho's overall stages of NPC with comparable nodal and primary tumour characteristics for the clinical endpoints of actuarial survival rate (ASR), disease-free survival rate (DFS), free of local failure survival rate (FLF), and free from distant metastases survival rate (FDM), despite the presence of significantly more fixed nodes and bulky nodes. This suggests a possible beneficial effect of the neoadjuvant chemotherapy. However, multivariate analysis has not shown the administration of the neoadjuvant chemotherapy to be of prognostic significance. Even though the chemotherapy was well tolerated with little toxicity, we recommend against the routine use of neoadjuvant chemotherapy in cervical-node-positive NPC outside the context of a prospective randomised clinical trial.

Adolescent↗
PubMed1995

Tests for possible effects of selection by domestic pyrethroids for resistance in culicine and anopheline mosquitoes in Sichuan and Hubei, China.

Resistance tests, by conventional methods and by observing the time for knockdown, showed no evidence for any build up of resistance to deltamethrin in malaria vectors from areas where millions of bednets have been treated with this compound annually for up to 7 years. However, a strain of Culex quinquefasciatus which had been bred in a factory in which volatile pyrethroids are handled had developed unequivocal resistance to deltamethrin. Observation of the time for knockdown gave clearer discrimination between resistant and susceptible strains than did observation of percentage mortality after a standard exposure time.

Animals↗
PubMed1995

Direct G protein activation reverses impaired CCK signaling in human gallbladders with cholesterol stones.

Human gallbladders were used to investigate the mechanisms of the impaired contraction induced by cholecystokinin (CCK) associated with cholesterol stones. Single muscle cells were isolated enzymatically with collagenase. Inositol 1,4,5-trisphosphate was measured by high-performance liquid chromatography. Diacylglycerol was assayed by thin-layer chromatography. CCK stimulation showed decreased muscle contraction and production of inositol 1,4,5-trisphosphate and diacylglycerol in gallbladders with cholesterol stones compared with those with pigment stones. Exogenous calmodulin induced maximal contraction of 22.4 +/- 0.5 and 21.0 +/- 0.6% in gallbladders with cholesterol and pigment stones, respectively. Similar findings were observed with a synthetic diacylglycerol analogue. Two G protein activators, aluminum fluoride and guanosine 5'-O-(3-thiotriphosphate), evoked similar responses in these two types of gallbladders, with maximal contractions of 21.3 +/- 0.4 and 23.3 +/- 0.5%, respectively, in those with cholesterol stones and 20.9 +/- 0.8 and 22.6 +/- 0.4%, respectively, in those with pigment stones. These results suggest that receptor-dependent ligands like CCK cannot fully activate the intracellular pathways, which, however, can be fully stimulated by circumventing receptors with G protein activators or second messengers. After G protein activation, the pathways appear to be functionally intact. The defect might then reside in the receptor or in the interaction between receptors and G proteins.

Aluminum Compounds↗
PubMed1995

Effect of enzyme treatment or steam-flaking of sorghum grain on lactation and digestion in dairy cows.

Effects of addition of a fungal enzyme (reported to have amylolytic and proteolytic activities) to dry-rolled or steam-flaked sorghum grain (40% of dietary DM) were tested for 70 d with 36 lactating Holstein cows in a 2 x 2 factorial arrangement of treatments. Compared with dry-rolling, steam-flaking resulted in increased yield of milk, milk protein, and 3.5% FCM; percentage of milk protein; and efficiency of feed utilization (FCM/DMI). Milk casein (as a percentage of milk N) was not altered, but milk urea N was lower, for cows fed steam-flaked sorghum. With steam-flaking, milk fat percentage decreased, short-chain fatty acids (C8 to C14) increased, but long-chain fatty acids (C16 to C18) were not affected. No yield parameters were altered by enzyme addition, except that the percentage of lactose in milk increased (5.02 vs. 4.96%). Steam-flaking of sorghum grain increased digestibilities of DM, OM, and starch (63 vs. 57%; 66 vs. 59%; and 98 vs 83%, respectively) compared with dry rolling. Enzyme addition did not affect starch digestibility, but digestibilities of DM, OM, CP, and NDF were greater than flaked grain was treated with enzyme, resulting in significant interaction effects. This study demonstrated higher milk and milk protein yields for cows fed steam-flaked sorghum than for cows fed dry-rolled sorghum, but addition of a sorghum-specific enzyme had no significant effect.

Animal Feed↗
PubMed1995

[The effect of platelet-activating factor antagonists on early bacteria translocation of rat after burn injury].

30% third degree burn model of Wistar rat was used in this experiment. The animals were divided randomly into three groups (normal control, burn, and platelet-activating factor antagonist treatment). After poured E. coli which labelled with acridine orange into intestine, the rats were killed at 6, 12, 24, and 48 hrs postburn, the bacteria in mesentery lymph node (MLN), liver and pulmonary organisms were cultured and counted, also observed by fluorescent microscopy directly. The results showed that, in PAF antagonist (WEB2170) treatment group, the quantity of bacteria in MLN, liver and lung were decreased significantly (P < 0.001). The labelled bacteria in MLN, liver and lung of burn group were 100%, 80.0%, and 50.0% respectively compared with 40.0%, 30.0%, and 20.0% in treatment group. It is suggested that WEB 2170 could protect the intestine from bacteria translocation after burn injury.

Animals↗
PubMed1995

Distinct muscarinic receptors and signal transduction pathways in gallbladder muscle.

Acetylcholine (ACh) caused a dose-dependent contraction of gallbladder muscle cells in either a normal (1.9 mM) Ca2+, zero-Ca2+ or 4 mM Sr2+ medium, with a maximal contraction about 21 +/- 1% at 10(-6) M. Pirenzepine, methoctramine and p-fluoro-hexahydro-sila-difenidol (the M1, M2 and M3 antagonist, respectively) alone had no inhibitory effect on ACh-induced contraction in normal Ca2+ medium, which was blocked by the combination of methoctramine and p-F-HHSiD. In the 4 mM Sr2+ medium, methoctramine dose dependently inhibited ACh-induced contraction and shifted the ACh dose-response curve to the right. The contraction induced by ACh was further blocked by 10(-4) M propranolol (phosphatidic acid phosphohydrolase inhibitor that prevents the production of diacylglycerol from phospholipase D activation), 10(-5) M H-7 and chelerythrine (the protein kinase C inhibitors) by 64%, 75% and 77%, respectively. In contrast, in the zero-Ca2+ medium, p-fluoro-hexahydro-sila-difenidol dose-dependently inhibited ACh-induced contraction and shifted the ACh dose-response curve to the right. The action of ACh was further blocked by 10(-6) M U-73122 (phospholipase C inhibitor) and 10(-5) M CGS 9343B (calmodulin antagonist) by 95% and 77%, respectively. In conclusion, ACh contracts the gallbladder muscle by stimulating the M2 and M3 muscarinic receptors. The M2 receptors are linked to Ca2+ influx, activation of phospholipase D and protein kinase C-dependent pathway, whereas the M3 receptors are preferentially associated with the activation of phospholipase C, intracellular Ca2+ release and calmodulin-dependent pathway.

Acetylcholine↗
PubMed1995

[Establishment of hybridoma lines and protective study of monoclonal antibodies against lipid A of endotoxins].

For developing monoclonal antibodies (MAb) that bound to lipid A of the LPS molecule, we established several hybridomas cell lines by fusion of SP2/0 and spleen cells from BALB/c mice immunized by J5 mutant strain of E. coli 0111:B4. Each MAb exhibited a high titer by ELISA assay. Six of MAb were of immunoglobulin G isotype and another one immunoglobulin M. All of these MAb demonstrated different capacity to cross-react with several gram-negative bacteria and their endotoxins. Among them, 9G6 MAb improved the survival rate of mice significantly when administered 2 hours before the challenge by pseudomonas A and E. coli. These findings suggest that MAb will probably be useful in the treatment of sepsis caused by a wide variety of gram-negative bacteria.

Animals↗
PubMed1995

[The roles of platelet activating factor in intestinal mucosal barrier injury after burn].

In order to investigate the roles of platelet activating factor (PAF) in postburn intestinal barrier injury, the changes in intestinal mucosal potential difference (PD), intestinal PAF, Phospholipase A2 (PLA2), myeloperoxidase (MPO) and malondialdehyde (MDA) were measured in a model of rats with 30% TBSA III degrees burns. The results showed that the intestinal PAF level was significantly elevated after severe burn and was negatively correlated with the decrease of intestinal mucosal PD (r = -0.94, P < 0.01). PAF antagonist WEB 2170 treatment could significantly inhibite the increase of PAF in intestinal tissue, enhance intestinal mucosal PD, attenuate the levels of PLA2, MPO and MDA in intestinal tissue, and alleviate the pathological changes in ileal mucosa, compared with the burn group. The results suggest that PAF is an important factor causing postburn intestinal mucosal barrier injury, and activation of leukocyte and PLA2 as well as the release of superoxide are important intermediate mechanisms for PAF leading to intestinal mucosal injury.

Animals↗
PubMed1995

[The anatomy of the maxillary ostium and the middle meatus antrostomy].

Serial cadaver dissections were performed and the anatomy of the natural ostium of the maxillary sinus and its adjacent structures observed. The results showed obvious anatomic variations. In most cases, the maxillary ostium was located in the infundibulum, directly under the orbit. The average distance was 1.1 cm from the maxillary ostium to the anterior maxillary wall, showing the anatomic relationship of the maxillary ostium with the nasolacrimal duct. The close anatomic relationship between the antronasal channel and orbit was demonstrated by radiography. A retrospective review of 70 middle meatal antrostomies was conducted and discussed. The anatomy of the antronasal channel should be well understood by an endoscope sinus surgeon in order to perform the middle meatal antrostomy without injuring the orbit and nasolacrimal duct.

Endoscopy↗
PubMed1994

Sciatic nerve regeneration navigated by laminin-fibronectin double coated biodegradable collagen grafts in rats.

Biodegradable type I collagen tube grafts filled longitudinally with laminin and fibronectin double coated collagen fiber bundles (L-F grafts) were implanted to promote sciatic nerve regeneration in rats. Grafts filled with uncoated collagen fibers were used as control. A 1 cm defect on the right sciatic nerve was filled with a graft in the manner of bridging. Thirty days after implantation, several newly developed nerve fasciculi were found at the middle portion of the L-F grafts in contrast to no developed nerves in the controls. After 60 days, the middle and distal portions of both grafts included well-developed nerve tissues with prominent myelinated and unmyelinated nerve fibers surrounded by perineural cells, but the control distal portion showed fewer nerve fibers. All artificial collagen elements were completely degraded and absorbed at 30 days, and new nerve tissues surrounded by an epineurium successfully connected the proximal stump to the distal stump of the initially separated nerve. Descending and ascending action potentials were evoked in all grafts at 60 days. These results indicated that laminin and fibronectin may promote the growth of axons in biodegradable collagen grafts, which guided nerve regeneration well and allowed the formation of epineurium.

Animals↗