Biomedical subjects

J Ren

Publications and source records attributed to J Ren.

At least 217 records · Page 12Linked to original sources

PubMed1998

Effects of calcitonin gene-related peptide on somatostatin and gastrin gene expression in rat antrum.

The ability of exogenous calcitonin gene-related peptide (CGRP) to regulate gastric somatostatin and gastrin messenger RNA was studied in vitro in rat antral mucosal/submucosal tissues. Somatostatin and gastrin mRNA were quantified by Northern and dot blot hybridization and regulatory peptides were measured by radioimmunoassay. Incubation of antral tissues in the presence of CGRP [1 x 10(-7) M] for 60 min resulted in a reciprocal increase in somatostatin and a decrease in gastrin release: 214.7+/-28.5 vs. control of 81.7+/-5.9 pg somatostatin per gram of tissue and 2.2+/-0.3 vs. control of 5.5+/-0.7 ng gastrin per gram of tissue (P < 0.001). CGRP caused parallel changes in somatostatin and gastrin mRNA levels: somatostatin mRNA increased by 212% from 0.40+/-0.02 to 1.25+/-0.09 absorbance units (AU) (P < 0.001) and gastrin mRNA decreased by 73% from 0.55+/-0.08 to 0.15+/-0.02 AU (P < 0.001). Somatostatin monoclonal antibody prevented CGRP-mediated inhibition of both gastrin release and gastrin mRNA levels. In conclusion, CGRP is capable of modulating both the secretion and gene expression of regulatory peptides from antral G and D cells. Somatostatin immunoneutralization studies suggest that the actions of CGRP on gastrin release and gene expression are indirect and mediated through the paracrine influences of somatostatin.

Animals↗

PubMed1998

Conservation of the major cold shock protein in lactic acid bacteria.

Primers designed from consensus regions of the major cold shock gene of different bacterial species were used in PCR amplification of Lactic Acid Bacteria (LAB). An appropriately-sized PCR product was obtained from Lactococcus lactis subsp. lactis LL43-1 and MG1363; Lactococcus lactis subsp. cremoris LC10-1, LC11-1, and LC12-1; Streptococcus thermophilus ST1-1; Enterococcus faecalis EF1-1; Lactobacillus acidophilus LA1-1; Lactobacillus helveticus LH1-1; Pediococcus pentosaceus PP1-1; and Bifidobacterium animalis BA1-1. The PCR products were cloned and sequenced. The deduced amino acid sequences displayed high sequence similarity with the major cold shock proteins of Escherichia coli and Bacillus subtilis and the human Y-box factor. The amino acid residues of the cold shock domain implicated in nucleic acid binding in several unrelated species were also highly conserved in the LAB strains. It is possible, therefore, that this protein in LAB may also act as a transcriptional enhancer to other cold shock genes and/or act as an RNA chaperone unwinding tightly folded RNA molecules.

Amino Acid Sequence↗

PubMed1998

Long-term outcome of primary glaucoma triple procedure with adjunctive 5-fluorouracil.

PURPOSE: To evaluate the long-term effect of adjunctive subconjunctival 5-fluorouracil (5-FU) on the filtration outcome of primary glaucoma triple procedure (PGTP) in primary open-angle glaucoma (POAG) patients. METHODS: Seventy-four POAG patients were randomly assigned to PGTP alone (36 patients) or PGTP with adjunctive subconjunctival 5-FU (5.0 +/- 1.3 injections of 5 mg each, total of 24.8 mg) (38 patients). After surgery, the patients were examined at regular intervals for intraocular pressure (IOP), visual acuity, medical therapy requirements, and complications. Surgical success was defined as IOP < or = 20 mmHg on postoperative medication < or = 1 without additional glaucoma surgery. RESULTS: Over an average follow-up (+/- SD) of 45.3 +/- 25.0 months, both 5-FU and control groups maintained significant improvement of IOP control and visual acuity. However, there were no statistically significant differences between the 5-FU and control groups with respect to postoperative IOP, number of glaucoma medications, visual acuity outcome, and success rate overall or in selected patients with one or more of the risk factors for filtration failure. CONCLUSIONS: The use of low-dose subconjunctival 5-FU (mean dosage of 24.8 mg in 5.0 +/- 1.3 injections) as an adjunct did not significantly improve the long-term filtration outcome of PGTP in POAG patients.

Aged↗

PubMed1998

Outcomes of primary phakic trabeculectomies without versus with 0.5- to 1-minute versus 3- to 5-minute mitomycin C.

PURPOSE: To compare the intraocular pressure and hypotony outcomes of primary phakic trabeculectomies with no mitomycin C (MMC), shorter MMC, and longer MMC exposure. METHODS: We evaluated primary phakic trabeculectomies with no MMC (36 eyes of 36 patients), 0.5- to 1-minute MMC (50 eyes of 50 patients), and 3- to 5-minute MMC (38 eyes of 38 patients) at the concentration of 0.5 mg/ml. Successful trabeculectomy was defined as an intraocular pressure of 21 mm Hg or less without development of a marked visual acuity loss associated with prolonged hypotony (intraocular pressure < 6 mm Hg over 3 months) and without the need for additional surgery to control intraocular pressure or treat postoperative complications. RESULTS: The three groups were similar in demographics, preoperative intraocular pressure, and medical dependency. However, the incidence of hypotony during the postoperative periods of 3 to 12 months was significantly higher in the 3- to 5-minute MMC group (P < .05, chi-square test). Severe visual acuity loss associated with hypotony was also more frequently found in the 3- to 5-minute MMC group than in the 0.5- to 1-minute (P = .009, chi-square test) group or the control group (P = .014, chi-square test). In addition, the success probabilities were significantly different among the three groups (P = .001, Kaplan-Meier survival analysis with log-rank test) and were the highest in the 0.5- to 1-minute MMC group and the lowest in the 3- to 5-minute MMC group. CONCLUSION: Shorter application (0.5 to 1 minute) of MMC appears to be optimal for the successful outcome of primary phakic trabeculectomy compared with no MMC or longer application of MMC at a concentration of 0.5 mg/ml.

Aged↗

PubMed1998

Primary glaucoma triple procedure in patients with primary open-angle glaucoma: the effect of mitomycin C in patients with and without prognostic factors for filtration failure.

PURPOSE: To investigate the effect of adjunctive mitomycin C on primary glaucoma triple procedure in patients with primary open-angle glaucoma with and without one or more of the prognostic factors for filtration failure of primary glaucoma triple procedure. Those factors include being of African-American race, having a preoperative intraocular pressure of 20 mm Hg or more on maximum tolerated medications, and being on two or more medications preoperatively. METHODS: Study patients consisted of 197 consecutive patients with primary open-angle glaucoma who were randomly assigned to receive either no adjunctive mitomycin C (101 eyes of 101 patients) or to receive adjunctive subconjunctival mitomycin C (96 eyes of 96 patients) during the primary glaucoma triple procedure. Kaplan-Meier survival analysis comparisons were made between respective subgroups with and without prognostic indicators for filtration failures using a relatively stringent set of criteria for filtration success of primary glaucoma triple procedure. RESULTS: There was no statistically significant (P = .117) difference in filtration success of primary glaucoma triple procedure between the control and mitomycin C groups. Adjunctive mitomycin C significantly (P < .05) improved the filtration outcome of the primary glaucoma triple procedure in the subgroups with each of the three prognostic factors for filtration failure of primary glaucoma triple procedure. On the other hand, in the subgroups without the prognostic factors, adjunctive mitomycin C did not significantly (P > .05) change the filtration outcome of the primary glaucoma triple procedure. CONCLUSION: These findings establish the basis for selective use of mitomycin C in patients with primary open-angle glaucoma undergoing primary glaucoma triple procedure.

Aged↗

PubMed1998

The role of adjunctive mitomycin C in secondary glaucoma triple procedure as compared to primary glaucoma triple procedure.

OBJECTIVE: This study aimed to investigate whether previously failed glaucoma filtration surgery is a risk factor for filtration failure of subsequent trabeculectomy combined with cataract surgery and to determine the role of adjunctive mitomycin C (MMC) in the secondary glaucoma triple procedure (SGTP) as compared to primary glaucoma triple procedure (PGTP). DESIGN: A prospective, controlled study that was randomized with respect to assignment to adjunctive MMC and a case-control design with respect to comparisons between SGTP and PGTP was studied. PARTICIPANTS: The SGTP group consisted of 49 eyes of 49 consecutive patients with primary open-angle glaucoma with a history of glaucoma filtration surgery requiring glaucoma medical therapy and in need of cataract surgery, randomized to adjunctive MMC (SGTP MMC subgroup of 21 eyes) and no adjunctive MMC (SGTP control subgroup of 28 eyes). The PGTP group consisted of 49 PGTP cases closely matched to the SGTP cases with respect to age, race, gender, MMC use, C:D ratio, and systemic diseases. INTERVENTION: Trabeculectomy combined with phacoemulsification and a small incision (5 x 6 mm), all polymethylmethacrylate posterior chamber intraocular lens implantation with or without adjunctive MMC (0.5 mg/ml for 1 minute), was performed. MAIN OUTCOME MEASURES: Surgery failure was defined as the need of an additional intraocular procedure or the need of more than one medication to achieve intraocular pressure control to the target level. Intragroup and intergroup comparisons were made with respect to filtration outcome among the SGTP and PGTP patients. RESULTS: Without adjunctive MMC, filtration success was significantly less in SGTP than in PGTP (P = 0.03). Adjunctive MMC significantly increased the success rate of SGTP (P = 0.02) but not that of PGTP (P = 0.89) over the average follow-up period of 2 years. CONCLUSIONS: Previously failed glaucoma filtration surgery is a significant risk factor for the filtration failure of combined surgery. Intraoperative use of adjunctive MMC significantly improves the filtration success rate of SGTP.

Adult↗

PubMed1998

Decrease of capsular opacification with adjunctive mitomycin C in combined glaucoma and cataract surgery.

OBJECTIVE: The authors investigated the incidence of capsular opacification requiring YAG capsulotomy after primary trabeculectomy combined with phacoemulsification and implantation of all polymethylmethacrylate intraocular lenses. DESIGN: A prospective randomized study. PARTICIPANTS: One hundred seventy-four eyes of 174 nonselected patients with primary open-angle glaucoma (POAG) were randomized to either no adjunctive mitomycin C (MMC) control group of 93 eyes of 93 patients) or adjunctive subconjunctival MMC (MMC group of 81 eyes of 81 patients) during the primary glaucoma triple procedure (PGTP). INTERVENTION: Primary glaucoma triple procedure with and without MMC and YAG laser capsulotomy for posterior capsular opacification (PCO) was performed. MAIN OUTCOME MEASURES: The incidences of YAG capsulotomy for PCO were compared between the control and MMC groups and also between the control group and the MMC subgroups (1 minute, 3 minutes, and 5 minutes of MMC application) using Kaplan-Meier analysis with Mantel-Cox log-rank test. Cox proportional hazard regression analysis also was performed to identify significant factors affecting capsular opacification. RESULTS: The control and MMC groups were similar in preoperative characteristics. However, the probability of PCO requiring YAG capsulotomy was significantly lower in the MMC group than in the control group (P = 0.004). Among the MMC subgroups, MMC application for 3 minutes was most effective and significant when compared with that of the control group (P = 0.002). Although not as significant as the intraoperative use of MMC (P = 0.002), old age (P = 0.026) and presence of diabetes mellitus (P = 0.035) were also identified as significant beneficial factors for decreasing the incidence of YAG capsulotomy for PCO in Cox proportional hazard regression analysis. CONCLUSION: Intraoperative subconjunctival MMC application during combined glaucoma and cataract surgery has a beneficial effect of inhibiting PCO after combined surgery in patients with POAG. Thus, after intraoperative subconjunctival application of MMC at the concentration of 0.5 mg/ml for 3 minutes, the aqueous MMC level must have been great enough to inhibit the lens epithelial cell proliferation to result in a long-term decrease in PCO.

Aged↗

PubMed1998

Effect of chronic and acute cigarette smoking on the pharyngo-upper oesophageal sphincter contractile reflex and reflexive pharyngeal swallow.

BACKGROUND: Cigarette smoking is known to affect adversely the defence mechanisms against gastro-oesophageal reflux. The effect of smoking on the supraoesophageal reflexes that prevent aspiration of gastric contents has not been previously studied. AIMS: To elucidate the effect of cigarette smoking on two of the supraoesophageal reflexes: the pharyngo-upper oesophageal sphincter (UOS) contractile reflex; and the reflexive pharyngeal swallow. METHODS: Ten chronic smokers and 10 non-smokers were studied, before and 10 minutes after real or simulated smoking, respectively. UOS pressure and threshold volume for the reflexes were determined using a UOS sleeve assembly. Two modes of fluid delivery into the pharynx were tested: rapid injection and slow injection. RESULTS: For both rapid and slow injections, the threshold volume for triggering the pharyngo-UOS contractile reflex was significantly higher in smokers than in non-smokers (rapid: smokers 0.42 (SE 0.07) ml, non-smokers 0.16 (0. 04) ml; slow: smokers 0.86 (0.06) ml, non-smokers 0.38 (0.1) ml; p<0. 05). During rapid injection, the threshold volume for reflexive pharyngeal swallow was higher in smokers (smokers 0.94 (0.09) ml, non-smokers 0.46 (0.05) ml; p<0.05). Acute smoking further increased the threshold volume for the pharyngo-UOS contractile reflex and reflexive pharyngeal swallow during rapid injection. CONCLUSIONS: Smoking adversely affects stimulation of the pharyngo-UOS contractile reflex and pharyngeal reflexive swallow. These findings may have implications in the development of reflux related respiratory complications among smokers.

Adult↗

PubMed1998

Pharyngoglottal closure reflex: identification and characterization in a feline model.

Earlier studies in humans have shown that pharyngeal stimulation by water at a threshold volume induces a brief vocal cord adduction, i. e., pharyngoglottal closure reflex. The present study was undertaken to 1) develop a suitable animal model for physiological studies of this reflex and 2) delineate its neural pathway and effector organs. Studies were done in cats by concurrent videoendoscopy and manometry followed by electromyographic studies. At a threshold volume (0.3 +/- 0.06 ml), injection of water into the pharynx resulted in a brief closure of the vocal folds, closing the introitus to the trachea. Duration of this closure averaged 1.1 +/- 0.1 s. Bilateral transection of the glossopharyngeal nerve completely abolished this reflex but not swallows induced by pharyngeal water stimulation. The pharyngoglottal closure reflex is present in the cats. The glossopharyngeal nerve is the afferent pathway of this reflex, and the interarytenoid and lateral cricoarytenoid muscles are among its target organs.

Animals↗

PubMed1998

Characterization and mechanisms of the pharyngoesophageal inhibitory reflex.

The objectives of this study were to identify and to characterize the pharyngoesophageal inhibitory reflex (PEIR) in an animal model. Thirty-one cats (2.4-5.0 kg) were anesthetized using alpha-chloralose (45 mg/kg ip), and esophageal peristalsis was recorded manometrically. Secondary peristalsis was activated by rapid air injection (8-20 ml) at midesophagus or slow infusion of water through the manometric catheters. Neither stimulus activated primary peristalsis. The PEIR was activated by rapid water injection or focal mechanical stimulation of the pharynx. Rapid air injection activated secondary peristalsis in 92% of the trials, and slow water infusion activated 1 secondary peristalsis every 3.2 min. Pharyngeal stimulation by 0.3, 0.5, 0.8, or 1.0 ml of water inhibited or blocked ongoing secondary peristalsis in 67, 82, 97, or 93% of trials, respectively. Mechanical stimulation of the posterior wall of the pharynx with 11-20 g pressure attenuated secondary peristalsis in 96% of the trials or blocked secondary peristalsis in 41% of the trials. Centripetal electrical stimulation at 30 Hz, 0.2 ms, 2 V for 4 s of the superior laryngeal (SLN) or glossopharyngeal (GPN) nerves blocked or inhibited secondary peristalsis in 100% of the trials. Bilateral transection of the GPN (n = 8), but not the SLN (n = 6), blocked the PEIR. Anesthetization of the pharyngeal mucosa using lidocaine (2%) blocked the PEIR (n = 3). We concluded that 1) the PEIR exists in the cat, 2) mechanical stimulation of the pharynx more strongly activates the PEIR than water, 3) activation of either SLN or GPN afferents attenuates ongoing secondary peristalsis, 4) the receptors mediating the PEIR are located in the pharyngeal mucosa, and 5) both SLN and GPN contribute to the PEIR, but the GPN is the major afferent limb of this reflex.

Animals↗

PubMed1998

Altered inotropic response to IGF-I in diabetic rat heart: influence of intracellular Ca2+ and NO.

Normally, insulin-like growth factor I (IGF-I) exerts positive effects on cardiac growth and myocardial contractility, but resistance to its action has been reported in diabetes. This study was designed to determine whether IGF-I-induced myocardial contractile action is altered in diabetes as a result of an intrinsic alteration of contractile properties at the cellular level. Contractile responses to IGF-I were examined in left ventricular papillary muscles and ventricular myocytes from normal and short-term (5-7 days) streptozotocin-induced diabetic rats. Mechanical properties of muscles and myocytes were evaluated using a force transducer and an edge detector, respectively. Preparations were electrically stimulated at 0.5 Hz, and contractile properties analyzed include peak tension development (PTD) or peak twitch amplitude (PTA), time to peak contraction/shortening, and time to 90% relaxation/relengthening. Intracellular Ca2+ transients were measured as fura 2 fluorescence intensity changes. IGF-I (1-500 ng/ml) caused a dose-dependent increase in PTD and PTA in preparations from normal but not diabetic animals. IGF-I did not alter time to peak contraction/shortening or time to 90% relaxation/relengthening. Pretreatment with the NO synthase inhibitor Nomega-nitro-L-arginine methyl ester (100 microM) attenuated IGF-I-induced increases in PTD in normal myocardium but unmasked a positive inotropic action in diabetic animals. Pretreatment with Nomega-nitro-L-arginine methyl ester blocked IGF-I-induced increases in PTA in single myocytes. Consistent with its inotropic actions on muscles and myocytes, IGF-I induced a dose-dependent increase in Ca2+ transients in normal but not diabetic myocytes. These results suggest that the IGF-I-induced inotropic response is depressed in diabetes because of an intrinsic alteration at the myocyte level. Mechanisms underlying this alteration in IGF-I-induced myocardial response may be related to changes in intracellular Ca2+ and/or NO production in diabetes.

Animals↗

PubMed1998

[Quantitative determination of constituents in various licorice roots by means of high performance liquid chromatography].

During the course of our studies on the chemical constituents of botanically identified Chinese licorice roots of various origins, we have identified 15 kinds of saponins and 49 kinds of flavonoids (including flavonoid glycosides). With these chemical constituents at hand, we have carried out the chemical evaluation studies of licorice roots available in Japan by means of high performance liquid chromatography (HPLC). In the HPLC analysis using an ODS reversed-phase column, a combination of 1% aqueous acetic acid and acetonitrile was used as the mobile phase in a gradient solvent system, and the eluate was monitored with UV absorption at 254 nm (for saponins with a diene or a conjugated carbonyl moiety, liquiritin, and liquiritin apioside) or at 350 nm (for other flavonoid constituents). By our analytical method described here, quantitative analyses of saponin and flavonoid constituents were effected simultaneously. We have found an interesting piece of information concerning the origin of parent plants and their characteristic constituents such as saponins and flavonoids.

Chromatography, High Pressure Liquid↗

PubMed1998

[Study on the effects of hyaluronic acid-streptomycin perfusion through the round window on the function and morphology in guinea pig inner ears].

To investigate the effects of the hyaluronic acid-streptomycin (HA-SM) perfusion through round window on the function and morphology of the inner ear in guinea pig, membrous labyrinth mapping, temporal bone section after celloidin embedding, transmission electron microscopy, electrocochlegraphy (ECochG) and electronystagmography (ENG) were examined. The nystagmus duration induced by caloric test was obviously reduced in comparison with that of the preoperation (P< 0.01), while the action potential(AP) by ECochG was not obviously changed. The sensory cells of estibular organs were severely damaged, while the morphology of corti's organs were significantly damaged after HA-SM perfusion. The results suggest that the HA-SM perfusion through the round window may selectively destroy the vestibular function, whereas the auditory function is not obviously damaged.

Animals↗

PubMed1998

[Sudden deafness in the elderly].

To study the clinical features of the sudden sensorineural hearing loss (SSHL) in the elderly, forty-five cases with SSHL, in the age more than 60 years, and fifty-seven young cases with SSHL as controls were investigated. The results showed that: 1. there was a higher incidence of the cardiovascular disease in the elderly group than in the young group (P < 0.05), 2. prognosis of hearing in elderly patients was worse than that in the controls (P < 0.05).

Aged↗

PubMed1998

[The determinations of tumor necrosis factor and interleukin 6 in serum of patients with sudden sensorineural hearing loss].

Serum level of tumor necrosis factor(TNF alpha) and interleukin 6(IL-6) were determined in 32 patients with sudden sensorineural hearing loss (SSHL), 15 patients with progressive sensorineural hearing loss(PSHL) and 20 normal controls by using enzyme-linked immunosorbent assay. The results showed that plasma TNF alpha and IL-6 levels in patients with SSHL were higher than those in PSHL group and in normal control group (P < 0.05). The study suggested that the TNF alpha and IL-6 played an important role in the pathogenesis of SSHL.

Adolescent↗

PubMed1998

[Sudden sensorineural hearing loss and jugular bulb diverticulum].

The relationship between high placed jugular bulb (diverticulum) and inner ear disorder is not well known. Three of 19 patients with sudden sensorineural hearing loss (SSHL) treated in 1995 had right side jugular bulb diverticulum revealed by CT scan and MRA. One of the 3 SSHL cases complicated with delayed endolymphatic hydrops. The exact mechanism of causation of inner ear symptom is not clear, but may partly be due to pressure effects with the jugular fossa encroaching on inner ear structure such as the cochlear aqueduct and vestibular aqueduct, and due to turbular flow in the diverticulum striking the inner ear. It is needed to further study the influence of the diverticulum on the inner ear.

Adult↗

PubMed1998

Characteristics of nystagmus and illusion evoked by optokinetic stimuli.

To study the characteristics of human psychophysiological responses to optokinetic stimulus, 30 male medical students were given a series of optokinetic step stimulus (5, 10, 15, 20, 30, 40, 60, 80, 100, 120 deg/sec ) (clockwise). Each stimulus lasted for 20 seconds. Optokinetic nystagmus was recorded on tape. At the same time, the latency and estimated fuzzy magnitude of the illusion were noted down. The nystagmus was analysed with a computer system of ENG and the magnitude of illusion was measured with a fuzzy set model. The results were: 1. Both the slow velocity (SV) and fast velocity (FV) of optokinetic nystagmus increased as stimulus speeded up and reached their peaks at 60 deg/sec, which remained constant from 60 to 120 deg/sec; 2. From 5 to 120 deg/sec, the magnitude of optokinetic illusion increased linearly as stimulus speeded up. Optokinetic illusion and optokinetic nystagmus are human psychophysiological responses to the same optokinetic stimulus, they are different in trend of change, and when optokinetic stimulus is at 60-l20 deg/sec, illusion response is more stable than nystagmus response.

Adolescent↗

PubMed1998

[Infrared spectra of Caulis Mahoniae and 6 species of medicinal plants of the same genus].

Based on the IR spectra of the petroleum ether extract, ethyl ether extract and water extract of Caulis Mahoniae and six species of medicinal plants of the same genus, it has been found out that the differences of chemical constituents among the samples can be reflected by the changes of IR spectra. This method can be used as a rapid and exact means to search unknown species with same chemical constituents in the same genus and family.

Drug Contamination↗