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Biomedical subjects

X Jin

Publications and source records attributed to X Jin.

At least 127 records · Page 7Linked to original sources
PubMed1998

[An experimental research of recombinant human epidermal growth factor on corneal wound healing].

OBJECTIVE: To investigate the effects of recombinant human epidermal growth factor (rhEGF) eye drops on corneal wound healing. METHODS: Twenty-four white rabbits were randomly divided into 4 groups, 6 rabbits 12 eyes each. Anterior keratectomy of 8 mm in diameter and 1/3 cornea in thickness was performed on each eye. Each of the following concentrations of rhEGF: 1, 10, 100 microg/ml eye drops or normal saline (control) was applied four times daily for a week respectively for one group. The wound area was determined by computer imaging analysis. RESULTS: The mean epithelial healing rate of rhEGF 1, 10, 100 microg/ml groups was 9.31, 9.96, 9.31 mm(2)/day respectively, significantly greater than 8.11 mm(2)/day of the control group. The action of rhEGF of 10 microg/ml was somewhat better than that of 1 or 100 microg/ml, and no significant difference was noticed among the three rhEGF groups. Moderate inflammation and corneal neovascularization were induced in the rhEGF 100 microg/ml treated group. CONCLUSION: rhEGF 1 - 10 microg/ml can accelerate corneal wound healing in the rabbit with no adverse side-effects. It may be used to treat serious corneal trauma and ulcer clinically.

Animals↗
PubMed1998

[Retinal light damage: I. The influences of light intensity and exposure duration at moderate and low intensities of cyclic light].

PURPOSE: To study the influences of moderate- and low intensity of cyclic light exposure on the light damage of rat retina and its relationship with light intensity and exposure duration. METHODS: Twenty five 8-10 weeks old of female Sprague-Dawley rats were divided into 5 groups randomly. One group were as controls reared in dark-room, others were exposured to 12 hour light: 12 hour dark cyclic white xenon light from 3 to 28 days. The light intensities were 90-115 Lux(100 Lux), 400-650 Lux(500 Lux), 800-1,150 Lux(1,000 Lux), 1,400-1,650 Lux(1,500 Lux) separately. After various duration of exposure, the retina were evaluated with light microscopy, electron microscopy and morphometric study. RESULTS: Except for the intensity of 100Lux group, all of the other exposure intensities can induce the light damage of rat retina. The photoreceptor cells were affected most early. The higher of light intensity and the longer of exposure duration, the severer of the photoreceptor cell loss. In the severely damaged eye, RPE were also damaged. CONCLUSIONS: For the light damage of rat retina which is induced by moderate- or low intensity of cyclic light, the damage degree was both affected by light intensity and exposure duration.

Animals↗
PubMed1998

Studies in a modified auxiliary abdominal rat heart transplantation model: preservation with colloid-free University of Wisconsin solution.

BACKGROUND: Current clinical heart preservation is still limited to 6 hours. A suitable heart transplantation model to rapidly screen the effectiveness of new solutions is essential. This study examines a new screening test-a modification of the conventional abdominal rat heart transplantation model that overcomes its serious limitation of lack of quantitative evaluation of function. METHODS: Rat hearts, with an externalized intraventricular balloon-tipped catheter, were transplanted immediately (controls) or flushed and stored in colloid-free University of Wisconsin solution in ice for 6, 9, or 12 hours before transplantation. One and 7 days later this catheter was connected to a pressure transducer and a calibrated syringe. Heart rate, maximum developed pressure, and maximum rate of left ventricular pressure rise were determined. Grafts were prepared for histologic study on day 7. RESULTS: All preserved hearts commenced beating within 2 minutes (controls beat within 20 seconds). On day 1 the heart rate and chamber stiffness (deltaP/deltat) were similar in all groups. The 9- and 12-hour-preserved hearts had significantly (p < 0.05) diminished developed pressure and contractility. On day 7 contractility and developed pressure improved in 9- and 12-hour-preserved grafts. There was extensive muscular atrophy and necrosis, with extensive cellular infiltrate in the 9- and 12-hour-preserved grafts; other grafts showed no damage. CONCLUSION: This quantitative model provides an ischemia-related gradation of function and greater discrimination than conventional methods. It has refuted previous studies suggesting effective preservation for 20 hours and demonstrated that functional testing is essential in evaluating preservation regimens.

Adenosine↗
PubMed1997

Inosine binds to A3 adenosine receptors and stimulates mast cell degranulation.

We investigated the mechanism by which inosine, a metabolite of adenosine that accumulates to > 1 mM levels in ischemic tissues, triggers mast cell degranulation. Inosine was found to do the following: (a) compete for [125I]N6-aminobenzyladenosine binding to recombinant rat A3 adenosine receptors (A3AR) with an IC50 of 25+/-6 microM; (b) not bind to A1 or A2A ARs; (c) bind to newly identified A3ARs in guinea pig lung (IC50 = 15+/-4 microM); (d) lower cyclic AMP in HEK-293 cells expressing rat A3ARs (ED50 = 12+/-5 microM); (e) stimulate RBL-2H3 rat mast-like cell degranulation (ED50 = 2.3+/-0.9 microM); and (f) cause mast cell-dependent constriction of hamster cheek pouch arterioles that is attenuated by A3AR blockade. Inosine differs from adenosine in not activating A2AARs that dilate vascular smooth muscle and inhibit mast cell degranulation. The A3 selectivity of inosine may explain why it elicits a monophasic arteriolar constrictor response distinct from the multiphasic dilator/constrictor response to adenosine. Nucleoside accumulation and an increase in the ratio of inosine to adenosine may provide a physiologic stimulus for mast cell degranulation in ischemic or inflamed tissues.

Adenine↗
PubMed1997

High-energy defibrillation increases the severity of postresuscitation myocardial dysfunction.

BACKGROUND: The fatal outcome of victims after initially successful resuscitation from cardiac arrest has been attributed both to global myocardial ischemia during the interval of cardiac arrest and to the adverse effects of reperfusion. The present study was prompted by earlier experimental observation that the magnitude of myocardial dysfunction was in part related to the energy delivered during electrical defibrillation. METHODS AND RESULTS: Ventricular fibrillation (VF) was induced in 15 Sprague-Dawley rats. Precordial compression was begun together with mechanical ventilation after 4 minutes of untreated VF and continued for 6 minutes. Spontaneous circulation was restored in each animal after external defibrillation with a single stored 2-, 10-, or 20-J countershock. Cardiac index and the rate of left ventricular pressure rise at left ventricular pressure of 40 mm Hg (dP/dt40) and fall (negative dP/dt) during the 240-minute interval after successful resuscitation were decreased, and left ventricular diastolic pressure was increased. These decreases in myocardial function were closely related to the energy of electrical defibrillation. After a 20-J shock, animals survived for only 5+/-3 hours; after a 10-J shock, animals survived for 15+/-4 hours; and after a 2-J shock, all animals survived for >24 hours. CONCLUSIONS: The severity of postresuscitation myocardial dysfunction is related, at least in part, to the magnitude of the electrical energy of the delivered shock.

Animals↗
PubMed1997

Molecular dissection of two distinct actions of melatonin on the suprachiasmatic circadian clock.

The pineal hormone melatonin elicits two effects on the suprachiasmatic nuclei (SCN): acute neuronal inhibition and phase-shifting. Melatonin evokes its biological effects through G protein-coupled receptors. Since the Mel1a melatonin receptor may transduce the major neurobiological actions of melatonin in mammals, we examined whether it mediates both melatonin effects on SCN function by using mice with targeted disruption of the Mel1a receptor. The Mel1a receptor accounts for all detectable, high affinity melatonin binding in mouse brain. Functionally, this receptor is necessary for the acute inhibitory action of melatonin on the SCN. Melatonin-induced phase shifts, however, are only modestly altered in the receptor-deficient mice; pertussis toxin still blocks melatonin-induced phase shifts in Mel1a receptor-deficient mice. The other melatonin receptor subtype, the Mel1b receptor, is expressed in mouse SCN, implicating it in the phase-shifting response. The results provide a molecular basis for two distinct, mechanistically separable effects of melatonin on SCN physiology.

Animals↗
PubMed1997

Canine mast cell adenosine receptors: cloning and expression of the A3 receptor and evidence that degranulation is mediated by the A2B receptor.

We cloned and characterized the canine A3 adenosine receptor (AR) and examined AR-induced degranulation of the BR line of canine mastocytoma cells. Canine A3AR transcript is found predominantly in spleen, lung, liver, and testes and encodes a 314-amino acid heptahelical receptor. 125I-N6-Aminobenzyladenosine binds to two affinity states of canine A3AR with KD values of 0.7 +/- 0.1 and 16 +/- 0.8 nM, reflecting G protein-coupled and -uncoupled receptors, respectively. Xanthine antagonists bind with similar affinities to human, canine, and rabbit receptors but with 80-400-fold lower affinities to rat A3AR. Although canine BR mastocytoma cells contain A1AR, A2BAR, and A3AR, degranulation seems to be mediated primarily by A2BARs stimulated by the nonselective agonist 5'-N-ethylcarboxamidoadenosine (NECA) but not by the A3-selective agonist N6-(3-iodobenzyl)adenosine-5'-N-methylcarboxamide. NECA-stimulated degranulation is not prevented by pertussis toxin and is blocked by enprofylline (Ki = 7 microM), an antiasthmatic xanthine with low affinity (Ki > 100 microM) for A1AR, A2AAR, and A3AR. NECA increases canine mastocytoma cell cAMP, Ca2+, and inositol trisphosphate levels; these responses are antagonized half-maximally by 7-15 microM enprofylline. The results suggest that (i) the cloned canine A3AR is structurally and pharmacologically more similar to human than to rat A3AR; (ii) the A2BAR, and not the A1AR or A3AR, is principally responsible for adenosine-mediated degranulation of canine BR mastocytoma cells; and (iii) the BR cell A2BAR couples to both Ca2+ mobilization and cAMP accumulation. Although A2B receptors play a major role in the regulation of BR mast cell degranulation, multiple AR subtypes and G proteins may influence mast cell functions.

Adenine↗
PubMed1997

Tetrandrine inhibited chronic "inflammatory" pulmonary hypertension in rats.

AIM: To study the effects of tetrandrine (Tet), on pulmonary hypertension. METHODS: An "inflammatory" chronic pulmonary hypertension induced by monocrotaline (Mon) in rats was used. RESULTS: Tet 50, 100, and 150 mg.kg-1.d-1 i.g. 3 wk inhibited Mon-induced increase of pulmonary artery pressure (PAP) by 23.8%, 34.9% (P < 0.05), and 42.0%, (P < 0.05); the right heart index by 2.0%, 25.0%, and 30.0% (P < 0.05) respectively compared with those from Mon group, without significant influence on the systemic artery pressure (SAP). Using histological exam by Verhoeff elastic stain and computer scanning analysis, it was found that Tet (100 mg.kg-1.d-1) for 3 wk, inhibited the increase of medial thickness and cross sectional area by 57.8% (P < 0.01) and 54.6% (P < 0.01), respectively vs Mon group. CONCLUSION: Tet ameliorated the development of pulmonary vascular and lung tissue injury induced by Mon in rats.

Alkaloids↗
PubMed1997

[Operative treatment of vesical diverticula].

We reviewed the results of operative management of 31 patients with vesical deverticula, and introduce a simple technique for treating large bladder diverticula. In the 31 patients with vesical diverticula analysed, 23 were followed up for at least six months. Of the 31 patients, 25 were male and 6 female. The average age was 54.2 years. Diverticula was secondary to bladderoutlet obstruction. Seven cases had intradiverticular tumors, and 9 stones in the sac. The diagnosis of vesical diverticula was usually made by cystogram or ultrasonography. The operative indications for vesical diverticula included stone formation, intradiverticular tumor, ureteral obstruction, incomplete empting diverticulum and urine retention due to large diverticula. The combined extravesical and intravesical method was often used. 26 patients underwent both operations for outlet obstruction and vesical diverticula at the same time. Of the 23 followed-up cases, 21 had no symptoms of the urinary tract. Five of the 7 patients with intradiverticular tumor died within 2.5 years; one of the rest survived for 2 years, and the others for 6 years. Two patients with large vesical diverticula received intravesical separation of diverticula. No complications encountered in this simple, time-saving and safe procedure. Cystograms revealed normal condition. The choice of operative techniques to treat vesical diverticula varies with each individual patient. The technique of intravesical separation of vesical diverticula is suitable for large, adhesive and posterior diverticula.

Adult↗
PubMed1997

[Interleukin-6 and tumor necrosis factor-alpha in middle ear effusions].

Using enzyme-linked immunosorbant assay (ELISA), we measured levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) in middle ear effusions (MEE) from patients with secretory otitis media (SOM) undergoing auripuncture to study the role of cytokines in the pathogenesis of the disease. Significant levels of IL-6 (> 62.5 ng/L) were found in 19 (86.36%) of 22 MEEs and those of TNF-alpha (> 37.5 ng/L) in 19 (70.37%) of 27 MEEs. The mean (+/- s) levels of IL-6 and TNF-alpha were 507.68 +/- 813.11 ng/L and 186.86 +/- 166.93 ng/L, respectively. It revealed that the shorter the course, the higher the concentration of IL-6 in MEE: the longer the course, the higher the concentration of TNF-alpha in MEE. These findings suggested that during the early stages of SOM, IL-6 might participate in the defensive reaction of organism, while TNF-alpha might be closely related to the persistence of SOM, resulting in an excessive inflammatory reaction with a potential for pathological changes. It is concluded that the immunological mechanisms probably play a significant role in the pathogenesis of SOM.

Adolescent↗
PubMed1997

[Accumulation sites of kanamycin in the organ of Corti by microautoradiography].

The accumulation sites of the 3H-labelled kanamycin in the organ of Corti were observed with electron microscope. The results showed that the accumulation of kanamycin was mainly in the mitochondria, cell membrane and stereocilia of the hair cells. The possible mechanism of the kanamycin accumulation in the mitochondria is their similarity with bacteria in the protein synthesis, i.e. the way that kanamycin might inhibit the protein synthesis in the mitochondria is similar to that of bacteria. The kanamycin accumulation in the cell membrane may indicate the entrance of kanamycin into the hair cells. The kanamycin deposition in the stereocilia was most likely related to its high chemical affinity with glycocalyx.

Animals↗
PubMed1997

The long-term effect of captopril treatment on endothelial function in spontaneously hypertensive rats.

The aim of this study is to elucidate the long term effect of captopril treatment on the endothelial function to release nitric oxide (NO) in spontaneously hypertensive rats (SHR). The properties of endothelium were determined with a model of hindquarter perfusion in response to alpha 1 adrenergic agonist, phenylephrine, at the age of 40 weeks of SHR which was administrated with captopril (100 mg/kg/day) from intrauterine and withdrawn at 16 weeks of age. Furthermore, in the presence of N omega-nitro-L-arginine methyl ester (LNAME), or L-arginine, the responses to phenylephrine were studied. From the curve of perfusion pressure, the minimal, maximal perfusion pressure (PPmin, PPmax) and the maximal slope (slope), as well as the 50% of effective concentration (EC50) were obtained. The data show that in captopril treated SHR, PPmin, PPmax and slope were markedly lower, but EC50 higher than those of untreated SHR. The curve induced by phenylephrine was significantly right shift compared with that of untreated SHR. Like WKY, the intensive reactivity to phenylephrine in the presence of LNAME was much lower than that of untreated SHR. In the presence of L-arginine, however, the right shift of curves was seen only in captopril treated SHR and WKY rats, but not in control SHR. In conclusion, endothelium does involve in the response of resistant vessel to phenylephrine. The mechanism of enhanced reactivity in untreated SHR may be, at least in part, due to the diminished capacity of producing NO from endothelium, and the effect of sustained hypotension of early captopril treatment might be relevant to the improved ability of endothelium.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

[Preliminary study on the arsenic trioxide-induced NB4 cell apoptosis and its molecular mechanisms].

OBJECTIVE: To illustrate the possible cellular and molecular mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL). METHODS: APL cell line NB4 was used for in vitro studies. The effect of As2O3 on APL was studied by using flow cytometry, DNA electrophoresis, Narthern blotting and Western blotting. RESULTS: As2O3 induced NB4 cell apoptosis, while not inhibiting the growth and survival of two other leukemic cell lines (HL-60 and U937). Furthermore, As2O3 effectively down-regulated the expression of bcl-2 gene without changing the mRNA levels of other apoptosis-associated genes (including p53, c-myc, bax and bcl-XL). CONCLUSION: These might be one of the molecular mechanisms of As2O3 induced NB4 cell apoptosis.

Animals↗
PubMed1997

Seven outbreaks of trichinosis in China (1992-1996).

Seven outbreaks of trichinosis occurred in Zhengzhou (central China) from 1992 to 1996, 250 patients were diagnosed. Trichinella larvae were found in 3 of 4 portions of the pork examined and in 5 of 7 cases by muscle biopsy. There was a higher occurrence of outbreaks in winter. Young and middle-aged workers, cadres and merchants were the majority of patients, (higher in males than in females). The most important clinical manifestations were fever, eyelid edema, tiredness and eosinophilia without any gastrointestinal symptoms, rash and with less myalgia. Anti-Trichinella antibodies were detected by IF in 62.6% individuals with the history of infection. The specific antibodies were only observed in 78% patients one week after onset of disease, while the antibody positive rate was increased to 92.5%, 97.6% and 100% two, three, four and five weeks after the onset and evidently increased from 89.6% before therapy to 100% one week after therapy, and decreased to 74.6% and 23.7% one and four months after therapy respectively, which suggested that IF was a useful tool for immunodiagnosis and checking up therapeutic effect of trichinosis.

Adolescent↗
PubMed1997

Action of autonomic drugs on the in vivo bladder base and proximal urethra in dog.

OBJECTIVE: To investigate the effects of autonomic drugs on the in vivo bladder base and proximal urethra in order to provide some reference materials for clinical usage of these drugs in the treatment of bladder outlet dysfunction. METHODS: In 35 dogs, the bladder base was separated from the bladder body and closed to constitute a small chamber. The changes of the pressure in the bladder base chamber and proximal urethra were recorded synchronously before and after administration of autonomic drugs. All data were analyzed with Student's t test. RESULTS: The bladder base had little response to acetylcholine (Ach) which however promoted a contraction of the proximal urethra. The effect of Ach on the proximal urethra was antagonized by phentolamine, but not by atropine. Isoprenaline resulted in relaxation of the bladder base, though it had little effect on the urethra. Norepinephrine (NE) produced contraction of the bladder base and urethra, while phentolamine caused a reduction in the bladder base and urethral pressure, and blocked the response of the bladder outlet region to NE. Angiotensin amide (AII) caused contraction of the bladder base and urethra, which was not obliterated by phentolamine. CONCLUSIONS: The cholinergic drug has no influence on the in vivo canine bladder base, but causes a contraction of the proximal urethra through indirect activation of alpha-receptors. The alpha-adrenergic agents have great effects on the bladder base and urethra by acting on alpha-receptors within the musculature in the outlet region. The beta-adrenoceptor agonist results in relaxation of the bladder base, but it has no effect on the urethra.

Acetylcholine↗
PubMed1997

[The mechanisms of progesterone treatment on endometrial carcinoma].

OBJECTIVE: To study the mechanisms of the exogenic progestrerone treatment on endometrial carcinoma. METHODS: We observed the morphologic changes of the endometrial cancer cells treated by exogenic progesterone with light and electronic microscopy. RESULTS: The main changes of the tumor cell treated were well differentiation, increase in secretory activity and apoptosis of tumor cells. CONCLUSIONS: Progesterone may directly affect tumor cells, inhibit the growth of tumor cells and lead to well differentiation. Clinically with preoperative and postoperative progesterone therapy, it can decrease the peritoneum implantation and metastasis, and also decrease the recurrence after operation.

Adenocarcinoma↗
PubMed1997

[Analysis of risk factors for infant deaths in urban and rural areas of Shandong Province].

Data of infant deaths in 1984 and 1994 were collected from the disease surveillance system in Shandong Province and 13 risk factors contributing infant death were analyzed with unconditional logistic regression to reveal their change in urban and rural areas in recent ten years. Results showed that risk factors for infant death in urban areas were birth weight, mother's age of childbirth, length of gestation and maternal health status, with comprehensive population attributable risk proportions (PARP) of 92.24 and 93.81 percent in 1984 and 1994, respectively. In addition to the risk factors mentioned above in urban areas, infant death in rural areas was also affected by ways of delivery and unhealthy events during pregnancy, with a comprehensive PARP of 98.07 percent in 1994. Risks for infant death delivered by family midwives reduced greatly in recent ten years, with an odd ratio (OR) of 4.145 in 1984, but it could not be entered a multivariate regression model in 1994.

Cause of Death↗