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Biomedical subjects

J Ren

Publications and source records attributed to J Ren.

At least 307 records · Page 17Linked to original sources
PubMed1994

Effect of aging, position, and temperature on the threshold volume triggering pharyngeal swallows.

BACKGROUND/AIMS: Swallows triggered by direct stimulation of pharyngeal structures may help to prevent aspiration by emptying the pharynx. The aims of this study were to compare the biomechanical events of the pharyngeal and primary swallow, determine the threshold volume of liquid required to trigger the pharyngeal swallows, and determine the effect of aging, position, and temperature on this threshold volume. METHODS: Concurrent manometry, video fluoroscopy, and video endoscopy were used to study young and elderly healthy volunteers. RESULTS: During pharyngeal swallows, in contrast to primary swallows, the free portion of the tongue did not make contact with the hard palate. In addition, pharyngeal swallows did not result in oral bolus clearance. All other biomechanical events, including deglutitive glottal function, were similar in both types of swallows. The threshold volume for pharyngeal swallows in young volunteers was significantly smaller than in the elderly (P < 0.01). Temperature and position did not have significant effects on threshold volume. CONCLUSIONS: Swallowing is readily induced by water stimulation of the pharynx. Pharyngeal swallows do not induce lingual peristalsis or clearance of oral content. The threshold volume of the pharyngeal swallow is significantly higher in the elderly than in the young, but it is not affected by body position or bolus temperature.

Adult↗
PubMed1994

Evidence that prostaglandin E2 can block calcium-activated 86Rb efflux from rat brain synaptosomes via a protein kinase C-dependent mechanism.

The effects of prostaglandin E2 (PGE2) on 86Rb efflux from rat brain synaptosomes were studied to explore its role in nerve ending potassium (K+) channel modulation. A selective dose-dependent inhibition of the calcium-activated charybdotoxin-sensitive component of efflux was found upon application of PGE2. No significant effect was seen on basal and voltage-dependent components over the concentration range of 10(-8) to 10(-5) M. The protein kinase C (PKC) inhibitors H-7 (10 microM) and staurosporine (100 nM), as well as prolonged preincubation (90 min) with 4 beta-phorbol 12,13-dibutyrate, which has been reported to down-regulate PKC, abolished the PGE2-induced inhibition, whereas HA1004 (10 microM) and Rp-3',5'-cyclic phosphorothioate (100 nM), which are relatively more selective for protein kinase A than PKC, did not. 4 beta-Phorbol 12,13-dibutyrate (100 nM), an activator of PKC, produced a similar inhibition of the Ca(2+)-dependent component of 86Rb efflux but also had no effect on the basal and voltage-dependent components. These data suggest that PGE2 can inhibit rat brain nerve ending calcium-activated 86Rb efflux, and this inhibition may involve PKC activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Identification and characterization of the esophagoglottal closure reflex in a feline model.

To identify a suitable animal model and to delineate the neural pathway and target organs of the esophagoglottal closure reflex we studied three species. Study showed the existence of an esophagoglottal closure reflex in cats. The presence of this reflex could not be documented in the opossum. In monkeys, because of the inadequacy of the available recording devices, its presence could not be ascertained. In the feline model, the closure response of the vocal folds to the abrupt generalized and segmental distension of the esophagus was similar to that of the humans. Study findings indicate that among glottal adductor muscles at least interarytenoid and lateral cricoarytenoid muscles are involved as target organs of the esophagoglottal closure reflex. Decerebration did not change the frequency of glottal closure response to esophageal distension, supporting the notion that this reflex is completely under brain stem control. Bilateral cervical vagotomy abolished the glottal closure induced by esophageal distension indicating that this reflex is mediated by the vagus nerve. Upper esophageal sphincter (UES) pressure response to esophageal distension by air was variable, suggesting that glottal and UES response to esophageal distension, although closely coordinated, are not dependent on one another. In summary, an esophagoglottal closure reflex exists in feline species, and many similarities in the elicitation and mediation of this reflex have been found with that of humans. This model could be used for further physiological studies.

Air↗
PubMed1994

Additive effect of contractions and insulin on GLUT-4 translocation into the sarcolemma.

The maximal effects of insulin and muscle contractions on glucose transport are additive. GLUT-4 is the major glucose transporter isoform expressed in skeletal muscle. Muscle contraction and insulin each induce translocation of GLUT-4 from intracellular sites into the plasma membrane. The purpose of this study was to test the hypothesis that the incremental effect of contractions and insulin on glucose transport is mediated by additivity of the maximal effects of these stimuli on GLUT-4 translocation into the sarcolemma. Anesthetized rats were given insulin by intravenous infusion to raise plasma insulin to 2,635 +/- 638 microU/ml. The gastrocnemius-plantaris-soleus group was stimulated to contract via the sciatic nerve by using a protocol that maximally activates glucose transport. After treatment with insulin, contractions, or insulin plus contractions or no treatment, the gastrocnemius-plantaris-soleus muscle group was dissected out and was subjected to subcellular fractionation to separate the plasma membrane and intracellular membrane fractions. Insulin induced a 70% increase and contractions induced a 113% increase in the GLUT-4 content of the plasma membrane fraction. The effects of insulin and contractions were additive, as evidenced by a 185% increase in the GLUT-4 content of the sarcolemmal fraction. This finding provides evidence that the incremental effect of maximally effective insulin and contractile stimuli on glucose transport is mediated by additivity of their effects on GLUT-4 translocation into the sarcolemma.

Animals↗
PubMed1994

Chemical studies of Chinese licorice-roots. I. Elucidation of five new flavonoid constituents from the roots of Glycyrrhiza glabra L. collected in Xinjiang.

From the air-dried roots of Glycyrrhiza glabra L. (Leguminosae) collected in Xinjiang province, China ("Shinkyo-Kanzo" in Japanese), five new flavonoid compounds named glucoliquiritin apioside (1) (a flavonone bisdesmoside), prenyllicoflavone A (5) (a bisprenylflavone), shinflavone (7) (a prenylated pyranoflavanone), shinpterocarpin (9) and 1-methoxyphaseollin (12) (both pyranopterocarpans), were isolated together with eight known saponins, seven known flavonoid glycosides, and eleven flavonoids. The structures of the new compounds have been elucidated on the basis of their chemical and physicochemical properties.

Chromatography, High Pressure Liquid↗
PubMed1994

[Submucous implantation with pedicel auto-flap of cheek muscle for atrophic rhinitis].

This paper described a method of submucous implantation for 32 patients with atrophic rhinitis by using pedicel auto-flap of cheek muscle and maxillary periosteum of piriform aperture. The results indicated that the total effective rate was 100% and the evident effective rate was 90.6% after 1 to 3 year postoperatively. The cilia beat of nasal mucosa, blood flow, osmotaxis of blood vessel. P substance and the resistance of nasal airflow were all improved. The flap survived and grew well due to autogenuous graft tissues and its original blood supply. No complications have been found. The clinical efficiency was obvious for a short term and was stable for a long term.

Adolescent↗
PubMed1994

[Establishment of immuno-PCR technique for the detection of tumor associated antigen MG7-Ag on the gastric cancer cell line].

The gastric cancer associated antigen McAb MG7-Ag was detected by means of a newly established method, termed immuno-PCR. A McAb-recombinant DNA chimeric molecule was made which possesses bispecific binding affinity for antigen that had been immobilized on microtiter wells and the segment of the attached DNA was amplified by PCR. The antigen of gastric cancer cell line KATO III was monitored by this method. Analysis of PCR products by agarose gel electrophoresis after staining with ethidium bromide allowed as few as 20 cells to be detected readily and reproducibly. Immuno-PCR showed a 10(4) enhancement in detection sensitivity compared with ELISA assay. When the same numbers of cells (2 x 10(6)/ml) were immobilized and then the serial diluted chimeric molecule was added, 3.8 x 10(-14) moles and 3.0 x 10(-11) moles were needed to give positive results with the immuno-PCR and ELISA assay, respectively. Therefore, immuno-PCR could give an enormous amplification capability with good specificity, and has a sensitivity much higher than any existing techniques for antigen detection.

Antibodies, Monoclonal↗
PubMed1994

Inhibition of a K+ current by beta-dendrotoxin in primary and subcultured vascular smooth muscle cells.

beta-Dendrotoxin (beta-DTX), a polypeptide component of Eastern Green Mamba snake venom, inhibits a slow voltage-activated 86Rb efflux from synaptosomes, suggesting that beta-DTX inhibits K+ channels. The effects of beta-DTX on the K+ currents in primary cultured and subcultured (passages 8-12) rat tail artery vascular smooth muscle cells (VSMCs) were studied using the whole-cell patch-clamp technique. A delayed rectifier K+ current was observed in both types of cells. The current, which was relatively insensitive to tetraethylammonium, was activated at -40 to -30 mV and showed almost no inactivation. beta-DTX (1-1000 nM) decreased the outward K+ current. The effect was concentration dependent and reversible by washout but did not depend on the frequency of stimulation (use dependence) or the membrane potential. beta-DTX was more effective in primary cultured cells than in subcultured cells. K+ channels in primary cultured cells were maximally (45%) inhibited by 1 microM beta-DTX compared with 35% inhibition in subcultured cells. The concentration producing half-maximal inhibition was 5.1 x 10(-8) M for primary cells and 7.1 x 10(-8) M for subcultured cells. The delayed rectifier current was not affected by alpha-DTX, a blocker of the fast-inactivating outward K+ current (IA). These results clearly demonstrate that beta-DTX is a novel antagonist of the delayed rectifier K+ current in primary and subcultured rat tail artery VSMCs.

Animals↗
PubMed1993

Alpha-lactalbumin possesses a distinct zinc binding site.

It has been proposed that the binding of Zn2+ to alpha-lactalbumin switches the conformation to one akin to a state intermediate in the folding of the protein. However, the high resolution x-ray crystal structure of human alpha-lactalbumin-Zn2+ complex at 1.7-A resolution (pH 7.6) does not reveal any significant change in conformation from the native state. The Zn2+ ion binds specifically in the "cleft" of alpha-lactalbumin (the region which forms the active site of the homologous protein lysozyme). This may suggest a possible role for Zn2+ binding in lactose synthase complex. The coordination of the Zn2+ ion involves a symmetry-related molecule in the crystal, the crystal contacts being stabilized by a SO4(2-) ion bound at the interface between three molecules.

Amino Acid Sequence↗
PubMed1993

Retinal detachment and degeneration in response to subretinal perfluorodecalin in rabbit eyes.

Perfluorocarbon liquids, including perfluorodecalin (PFD), are useful intraoperative tools in complicated vitreoretinal surgery, such as for giant retinal tears, PVR and intraocular foreign bodies. Due to its high specific gravity (1.91 g/cm3) subretinal complications of PFD may occur. The consequences of subretinal PFD were studied in 23 albino rabbits (28 eyes). Using glass micropipettes (outer diameter of tip 100-120 microns), we injected 50-100 microliters PFD subretinally via the vitreous space. The same volume of BSS was injected into 18 control eyes. Eyes were monitored by indirect ophthalmoscopy and examined by light and electron microscopy at 1, 2 and 3 days, and 1, 2, 4 and 12 weeks. Progressive retinal detachments with newly formed retinal breaks in the inferior quadrants developed in 26 of 28 eyes. As early as 1 day postoperatively, subretinal PFD induced loss of outer and inner segments. Local retinal necrosis occurred in 4 eyes 5-7 days after surgery. A marked vacuole formation in retinal layers and PFD emulsification were regularly seen. The control eyes healed spontaneously. Toxic, mechanical and barrier effects may have caused the retinal damage. We advocate that all PFD be removed from the eye at surgery.

Animals↗
PubMed1993

Calcitonin gene-related peptide mediates capsaicin-induced neuroendocrine responses in rat antrum.

BACKGROUND: Calcitonin gene-related peptide (CGRP) is a 37-amino acid peptide localized to primary sensory afferent nerves in the rat stomach. The actions of CGRP in regulating antral neuroendocrine function were examined in vitro through the use of capsaicin, an agent capable of evoking neuropeptide release from peripheral sensory nerve endings. These results were compared with the effects of exogenous CGRP and CGRP antagonist, CGRP8-37. METHODS: Rat antral mucosal/submucosal fragments were incubated in either static or dynamic perifusion experiments. Media were assayed for gastrin, somatostatin, CGRP, and acetylcholine. RESULTS: Capsaicin, like exogenous CGRP, stimulated antral somatostatin release and inhibited both gastrin release and acetylcholine discharge. Low dose capsaicin (1 x 10(-5) mol/L) caused significant stimulation of CGRP release: 33 +/- 0.2 vs. 14 +/- 1 pg/mL protein; P < 0.001. Tetrodotoxin blocked capsaicin-induced inhibition of acetylcholine release and prevented partially capsaicin-mediated stimulation of CGRP release. The CGRP receptor antagonist CGRP8-37 prevented capsaicin-induced D-cell stimulation and inhibition of G-cell secretion and cholinergic discharge. CONCLUSIONS: The effects of capsaicin-induced changes in antral D- and G-cell secretion and acetylcholine discharge are due primarily to release of CGRP. Antral CGRP release from primary sensory afferent nerve terminals may act as a local effector substance to regulate antral neuroendocrine function.

Acetylcholine↗
PubMed1993

Determinants of intrabolus pressure during esophageal peristaltic bolus transport.

Previous manometric studies of esophageal fluid bolus transport in humans have generally ignored the hydrodynamic distinction between intrabolus pressure and pressure within the lumen-occluded, contracting esophageal segment. In this study we obtained concurrent esophageal videofluoroscopic and intraluminal manometric recordings in supine normal volunteers using different bolus volumes and viscosities and abdominal compression. Intrabolus pressure increased with bolus volume, viscosity, and abdominal compression. Esophageal diameter increased with larger bolus volumes, and this increase was correlated with increases in intrabolus pressure. Intrabolus pressure was highest in the bolus tail. Peak intraluminal pressures > 20 mmHg above basal intrabolus pressure almost invariably were associated with effective peristalsis, whereas values of this pressure differential < 20 mmHg frequently were associated with ineffective peristalsis and retrograde bolus escape. Intrabolus pressure can serve as an important indicator of the forces resisting peristaltic transport and the occurrence of ineffective bolus transport.

Abdomen↗
PubMed1993

Effect of aging and bolus variables on pharyngeal and upper esophageal sphincter motor function.

Effect of aging, bolus volume, temperature, and consistency on the pharyngeal peristalsis, as well as the effect of aging on the upper esophageal sphincter (UES) resting pressure and its response to esophageal distension by air and balloon, were studied in 14 young and 12 healthy elderly volunteers. In both age groups there was no significant volume or temperature effect on amplitude, duration, or velocity of the pharyngeal peristalsis. Compared with water swallows, mashed potato swallows resulted in a significant increase in the amplitude and duration of the hypopharyngeal peristaltic pressure wave (P < 0.05). For water swallows, the amplitude and duration of the peristaltic pressure wave in the hypopharynx were significantly increased in the elderly compared with the young group (P < 0.01). UES resting pressure in the elderly measured 43 +/- 5 (SE) mmHg and was significantly less than that of the young (71 +/- 8 mmHg; P < 0.01). Magnitude of the UES pressure decrease because of esophageal distension by air, as well as magnitude of its pressure increase because of esophageal balloon distension, was similar among young and elderly. 1) Contrary to common expectations, the parameters of the pharyngeal peristaltic pressure wave do not deteriorate in the elderly in their seventh and eighth decade. 2) Compared with the young, hypopharyngeal pressure wave amplitude and duration are significantly increased in the elderly. This increase could be caused by an adaptation response to a pharyngeal outflow compromise. 3) Pharyngeal peristaltic pressure wave amplitude and duration, but not its velocity, are modulated by the bolus consistency. This modulatory mechanism is preserved in the elderly. 4) Although UES resting pressure is significantly decreased in the elderly, its pressure response to esophageal distension by air and balloon is preserved.

Adult↗
PubMed1993

Saponin and sapogenol. XLIX. On the constituents of the roots of Glycyrrhiza inflata Batalin from Xinjiang, China. Characterization of two sweet oleanane-type triterpene oligoglycosides, apioglycyrrhizin and araboglycyrrhizin.

Two sweet oleanane-type triterpene oligoglycosides named apioglycyrrhizin and araboglycyrrhizin were isolated from the air-dried roots of Glycyrrhiza inflata Batalin, collected in Xinjiang province (Shinkyo-Kanzo in Japanese), together with glycyrrhizin (3), licorice-saponins A3 (8), G2 (10), and H2 (11) and known flavonoid glycosides. On the basis of chemical and physicochemical evidence, the structures of apioglycyrrhizin and araboglycyrrhizin have been determined to be expressed as 3-O-[beta-D-apiofuranosyl(1-->2)-beta-D- glucuronopyranosyl]glycyrrhetic acid (1) and 3-O-[alpha-L- arabinopyranosyl(1-->2)-beta-D-glucuronopyranosyl]glycyrrhet ic acid (2), respectively. During the course of these studies, it has been found that the hydroxyl groups in the oligosaccharide moiety of the glucuronide saponins may be partially methylated by prolonged treatment with diazomethane in methanol. The sweetness of the saponins hitherto isolated from various Glycyrrhizae Radix has been examined and a structure-sweetness relationship, as compared with glycyrrhizin, has been found.

China↗
PubMed1993

Saponin and sapogenol. L. On the constituents of the roots of Glycyrrhiza uralensis Fischer from Xinjiang, China. Chemical structures of licorice-saponin L3 and isoliquiritin apioside.

From the air-dried roots of Glycyrrhiza uralensis Fischer collected in Xinjiang province, China ("Shinkyo-Kanzo" in Japanese), a new oleanene-type triterpene oligoglycoside named licorice-saponin L3 and a new chalcone oligoglycoside named isoliquiritin apioside were isolated together with glycyrrhizin, 18 alpha-glycyrrhizin, apioglycyrrhizin, araboglycyrrhizin, licorice-saponins A3, E2, G2, and H2, and six known flavonoid glycosides. On the basis of chemical and physicochemical evidence, the structures of licorice-saponin L3 and isoliquiritin apioside were elucidated as 3 beta-[alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranosyl(1--> 2)-beta-D-glucuronopyranosyloxy]-22 beta-acetoxy-24-hydroxyolean-12-en-30-oic acid (1) and 4-O-[beta-D-apiofuranosyl(1-->2)-beta-D- glucopyranosyl]isoliquiritigenin (6), respectively.

Chalcone↗
PubMed1993

[Enhanced malignancy of tumor cells by the interaction with host cells reactive to foreign body].

We examined factors promoting malignant progression using a weakly malignant variant cell line, ER-1, derived from c-SST-2, a rat mammary carcinoma. ER-1 cells were converted to a highly malignant phenotype (highly tumorigenic, metastatic, invasive in vitro) by the in vitro/in vivo interaction with host cells reactive to foreign body. Epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta) produced by host reactive cells, transiently enhanced the tumorigenicity and in vitro invasiveness of ER-1 cells into an endothelial cell monolayer. The host reactive cells also produced oxygen radicals and induced mutations in ER-1 cells. It is speculated that mutations induced by host reactive cells cause cellular diversification, including the emergence of highly malignant variant cells whose growth is selectively promoted by growth factors such as EGF and TGF-beta.

Animals↗
PubMed1993

Effect of age and bolus variables on the coordination of the glottis and upper esophageal sphincter during swallowing.

We studied 1) the effect of age and bolus variables on a) the coordination of deglutitive vocal cord adduction and upper esophageal sphincter (UES) relaxation and b) the duration of deglutitive vocal cord adduction; 2) the effect of the presence of a manometric catheter across the UES on the deglutitive glottal function; and 3) the temporal relationship between deglutitive vocal cord closure and swallow-induced apnea. We studied 10 young (23 +/- 2 yr) and 10 healthy elderly (73 +/- 2 yr) volunteers by concurrent videoendoscopy, UES manometry, respirography, and submental surface electromyography. In both groups the onset of vocal cord adduction preceded the onset of UES relaxation, deglutitive apnea, and submental electromyogram swallowing signal. In both groups, bolus volume and temperature did not have any significant effect on the duration of deglutitive vocal cord adduction. In both young and elderly volunteers, water swallows, compared with dry swallows, significantly shortened the interval between the onset of deglutitive vocal cord adduction and the onset of UES relaxation. In conclusion, coordination between deglutitive glottal and UES function, as well as the duration of deglutitive vocal cord adduction, is preserved in the elderly. Bolus volume and temperature do not have a modulatory effect on the duration of vocal cord closure, but water swallow shortens the interval between the onset of glottal closure and UES relaxation. This shortened interval may contribute to the safety of the airway during swallowing of liquid volumes.

Adult↗