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Biomedical subjects

L Yang

Publications and source records attributed to L Yang.

At least 631 records · Page 35Linked to original sources
PubMed1995

Regional concentrations of cyclic nucleotides after experimental brain injury.

Regional concentrations of lactate, glucose, cAMP, and cGMP were measured after lateral fluid percussion brain injury in rats. At 5 min after injury, while tissue concentrations of lactate were elevated in the cortices and hippocampi of both the ipsilateral and contralateral hemispheres, those of glucose were decreased in these brain regions. By 20 min after injury, increases of lactate concentrations and decreases of glucose concentrations were observed only in the cortices and in the hippocampus of the ipsilateral hemisphere. Whereas the cAMP concentrations were unchanged in the cortices and hippocampi of the ipsilateral and contralateral hemispheres at 5 min after injury, decreases were found in the injured cortex and ipsilateral hippocampus at 20 min after injury. The tissue concentrations of cGMP were found to be elevated only in the ipsilateral hippocampus at 5 min after injury. The present observation that tissue glucose decreases in the injured cortex and the ipsilateral hippocampus are consistent with the published findings of increased hyperglycolysis and oxidative metabolism in brain immediately after injury. The present findings that the concentrations of cAMP and cGMP change in the cortex and hippocampus provide biochemical evidence for the neurotransmitter's surge after brain injury.

Animals↗
PubMed1995

Topical stratum corneum lipids accelerate barrier repair after tape stripping, solvent treatment and some but not all types of detergent treatment.

Topical acetone treatment extracts lipids from the stratum corneum, and disrupts the permeability barrier, resulting in a homeostatic response in the viable epidermis that ultimately repairs the barrier. Recently, we have developed an optimal lipid mixture (cholesterol, ceramide, palmitate and linoleate 4.3:2.3:1:1.08) that, when applied topically, accelerates barrier repair following extensive disruption of the barrier by acetone. The present study determined if topical treatment with this optimal lipid mixture would have beneficial effects following disruption of the barrier by petroleum ether, tape stripping, or by detergent treatment. Also, we determined if barrier repair was accelerated after moderate disturbances of barrier function. Following moderate or extensive disruption of the barrier by acetone or petroleum ether (solvents), or tape stripping (mechanical), application of the optimal lipid mixture accelerated barrier repair. Additionally, following barrier disruption with N-laurosarcosine free acid or dodecylbenzensulphuric acid (detergents), the optimal lipid mixture similarly accelerated barrier repair. However, following disruption of the barrier with different detergents, sodium dodecyl sulphate and ammonium lauryl sulphosuccinate, the optimal lipid mixture did not improve barrier recovery. Thus, the optimal lipid mixture is capable of accelerating barrier repair following disruption of the barrier by solvent treatment or tape stripping (mechanical), and by certain detergents such as Sarkosyl and dodecylbenzensulphuric acid. The ability of the optimal lipid mixture to accelerate barrier repair after both moderate and extensive degrees of barrier disruption suggests a potential clinical use for this approach.

Acetone↗
PubMed1995

Variable oxygenation response to inhaled nitric oxide in severe persistent pulmonary hypertension of the newborn.

The causes of variable responsiveness to inhaled nitric oxide (NO) in Persistent Pulmonary Hypertension of the Newborn (PPHN) are unknown. The changes in the severity of respiratory failure after the onset of inhaled NO (maximal dose 20 ppm) were studied in 13 consecutive neonates with severe PPHN. Response was defined as a sustained decrease of alveolar-arterial oxygen gradient (AaDO2) by > 20%, or a decrease in oxygenation index (OI) by > 40%. Six neonates had a rapid response within 30 min, three had an intermediate response within 8 h, and three had a delayed response within 12 h after the onset of NO. Three infants with birth asphyxia responded rapidly to inhaled NO. One infant with sepsis did not respond, and two with suspected sepsis had a delayed response. The infants with Meconium Aspiration Syndrome and idiopathic PPHN had a variable response time. Twelve neonates required 4 to 14 days of mechanical ventilation and survived. Infants with PPHN may benefit from a trial of inhaled NO therapy that exceeds 30 min. The variability of the response time to inhaled NO is likely to be multifactorial and dependent on the disease process associated with PPHN.

Administration, Inhalation↗
PubMed1995

Fetal outcome in murine Lyme disease.

Lyme disease is an inflammatory syndrome caused by infection with Borrelia burgdorferi. Although this syndrome has important implications for human pregnancy, little is known about gestational infection with B. burgdorferi. Fetal death occurred in 33 of 280 gestational sacs (12%) in 39 C3H/HeN female mice infected by intradermal injection of B. burgdorferi 4 days after mating (acute infection), compared with 0 of 191 sacs in 25 control mice (P = 0.0001). Forty-six percent of acutely infected mice suffered at least one fetal death, compared with none of the control animals (P = 0.0002). There were no fetal deaths in 18 C3H/HeN mice infected 3 weeks prior to mating (chronic infection). A sensitive PCR technique detected B. burgdorferi DNA in the uteri of acutely infected mice but did not detect DNA in the uteri of controls or chronically infected mice. Spirochete DNA was only rarely detected in fetal tissues, and its presence was not required for fetal death. The inclusion of an internal competitive PCR target indicated that the lack of B. burgdorferi sequences in fetal DNA was not due to the presence of a PCR inhibitor. Histologic analysis of gestational tissues from infected animals demonstrated nonspecific pathology consistent with fetal death. These findings indicate an association between murine fetal death and acute infection with B. burgdorferi early in gestation but not with chronic infection. Our data suggest that fetal death is due to a maternal response to infection rather than fetal infection. These findings could provide an explanation for observations in humans in which sporadic cases of fetal death in women infected with B. burgdorferi during pregnancy have been reported, while previous infection has not been associated with fetal death.

Animals↗
PubMed1995

Efficiency and functional consequences of adenovirus-mediated in vivo gene transfer to normal and dystrophic (mdx) mouse diaphragm.

The protein dystrophin is absent in muscles of patients with Duchenne muscular dystrophy (DMD) as well as in mdx mice. The mdx mouse diaphragm closely resembles the human DMD phenotype and should serve as an appropriate model for future studies of dystrophin gene replacement. In this regard, recombinant adenovirus (AV) holds great promise as a vector for delivering a functional dystrophin gene to muscle. However, the use of AV is hampered by the development of an immune response against transduced cells, resulting in short-lived transgene expression as well as possible adverse effects on organ function. In the present study, sensitive reporter genes were employed to determine the efficiency and functional consequences of AV-mediated gene transfer to the diaphragm in both normal and mdx adult mice. One week after direct intramuscular injection of AV into the diaphragm, the level of transgene expression was significantly increased in mdx compared with normal diaphragms. In addition, small-caliber fibers (< 500 microns2) demonstrated preferential transduction in both groups of mice. Normal diaphragms receiving AV exhibited a substantial reduction in maximal twitch and tetanic force generation, whereas no significant effect on diaphragm contractility was found in the mdx group at 1 wk after injection. At 1 mo after AV administration, however, there was a significant decrease in force production by both normal and mdx diaphragms. Immunosuppression with cyclosporine A over 1 mo did not augment the level of transgene expression, but a beneficial effect on diaphragm force-generating capacity was observed in both groups of animals. We conclude the following: (1) short-term transduction of the diaphragm is more efficient in mdx than in normal mice; (2) AV leads to reduced force production by the diaphragm, with this effect being more pronounced in normal than in mdx in the early (but not the late) postinjection period; and (3) immunosuppressive therapy with cyclosporine has a partially protective effect on muscle function after AV administration, which is apparently unrelated to sparing of transduced fibers from elimination by the host immune system. These findings have important implications for the application of AV-mediated dystrophin gene transfer to the treatment of DMD.

Adenoviruses, Human↗
PubMed1995

Purification and characterization of a geniposide-hydrolyzing beta-glucosidase from Eubacterium sp. A-44, a strict anaerobe from human feces.

A geniposide-hydrolyzing beta-glucosidase was discovered in Eubacterium sp. A-44, a human intestinal anaerobe. The enzyme was intracellularly distributed in the bacterium, and purified to homogeneity from the extract using Butyl-Toyopearl 650M, Sephacryl S-300, hydroxyapatite and chromatofocusing column chromatography. The enzyme was a single polypeptide chain with the molecular weight of 90 kDa and the N-terminal amino acid sequence initiated from methionine up to the 29th residue did not show more than 50% homology against known protein sequences. A broad substrate specificity was shown for the beta-glucosidase to hydrolyze aryl beta-D-glucosides (p-nitrophenyl beta-D-glucopyranoside-pNPG, esculin and salicin), alkyl beta-D-glucosides (geniposide and amygdalin) and cellobiose. The Km values (mM) for various beta-D-glucosides were 0.068 for geniposide, 0.10 for pNPG, 0.21 for esculin, 0.22 for salicin, 2.9 for amygdalin, and 0.91 for cellobiose. The pH optimum with pNPG and geniposide as the substrates was 6.0. The enzyme was inhibited by sulfhydryl reagents, Cu2+, and nojirimycin bisulfite.

Amino Acid Sequence↗
PubMed1995

Airway protection during experimental CPR.

BACKGROUND: Experimental studies recently demonstrated that positive pressure ventilation may not be essential for initial cardiopulmonary resuscitation. Nevertheless, oxygen enrichment of inspired gas mixtures and spontaneous gasping were associated with increased resuscitability and survival after cardiac arrest. However, as yet unresolved is the benefit of early airway control under conditions simulating "sudden death" due to ventricular fibrillation. METHODS: Twenty adult, male Sprague-Dawley rats were randomly assigned to one of two groups in which the airway was unprotected or protected by an oropharyngeal airway of our design. Cardiac arrest was induced by an alternating current delivered to the right ventricular endocardium. Oxygen was delivered to a hood that was loosely applied over the head of the each animal at a flow rate of 1 L/min. Precordial compression was initiated after 4 min of untreated ventricular fibrillation and defibrillation was attempted 6 min later. After spontaneous circulation had been restored, a tracheostomy was performed and the animals were mechanically ventilated with 100% oxygen for an additional interval of 1 h. Animals were then returned to their cages and observed for an additional 24 h. RESULTS: Spontaneous circulation was restored in each of the animals who had an oropharyngeal airway and nine of ten animals in the absence of an artificial airway. In each group, seven animals survived for more than 24 h. Animals in which the airway had been protected had significantly greater frequency of spontaneous gasping (28 +/- 13/min vs 13 +/- 9/min; p < 0.05) and significantly higher arterial oxygen saturation (77 +/- 19% vs vs 55 +/- 25%; p < 0.05). CONCLUSION: In the setting of experimental cardiac resuscitation, the insertion of an artificial airway increased the frequency of spontaneous gasping and arterial oxygenation. Nevertheless, no significant differences in resuscitability or postresuscitation survival were associated with insertion of the artificial airway.

Airway Obstruction↗
PubMed1995

Enhanced radiation-induced cell killing by carboplatin in cells of repair-proficient and repair-deficient cell lines.

The objective of this study was to determine whether a deficiency for either one of two repair processes influences the phenomenon of enhancement of radiation-induced cell killing by carboplatin which has been reported previously in one cell line (V79) and which is presumably a result of an interaction between these two therapeutic modalities. Cell killing was enhanced in cells of four cell lines when the cells were exposed to carboplatin before and during irradiation in either air or hypoxia. In cell lines proficient in both excision repair and DNA double-strand break repair (K1 and AA8), and in a cell line deficient in nucleotide excision repair (UV41), the enhancement was characterized as both a reduction in the shoulder region of the survival curves indicated by a reduced Dq and a reduction in D0 in the terminal region of the survival curves determined for cells exposed in air and under hypoxic conditions. Only the latter effect was observed in a cell line deficient in DNA double-strand break repair (xrs-5). The survival curves were fitted to the data using the repair saturation model and a computer program developed by N. Albright (Radiat. Res. 118, 112-130, 1989). In hypoxia, the reductions in Dq were as great as from 7.0 Gy to 2.1 Gy, 3.3 Gy to 0 Gy and 1.7 Gy to 0 Gy for K1, AA8 and UV41 cells, respectively. Sensitizer enhancement ratios ranged from 1.3 to 1.7 and were similar for irradiation in air and under hypoxic conditions. This enhanced cell killing by carboplatin combined with radiation required levels of the drug sufficient to produce cytotoxicity by the drug alone as exemplified by the UV41 cell line, which is intrinsically sensitive to carboplatin and in which 1/30 of the drug concentration required for the other cell lines produced an enhanced cell killing at an equitoxic dose of only 5 microM.

Animals↗
PubMed1995

[The clinical study of local treatment of ocular malignant tumors with IL-2 LAK cells].

The authors reported the method of treatment of ocular malignant tumors at early and middle stages with local injections of self lymphokine-activated killing (LAK) cells which were induced by gamma IL-2 in vitro. Satisfactory therapeutic results were obtained. Among the 25 cases of ocular malignant tumors, 10 cases were treated only with IL-2 LAK cells, nine of them got complete regression (CR) and one got partial regression (PR); the other 15 cases were treated with operation and IL-2 LAK cells and they all obtained complete remission. In the follow-up, except the contact of 1 case with PR was lost, all the other 24 cases did not relapse after 1-5 years of observation. The above results show that the treatment of malignant tumors with local injection of self IL-2 LAK cells is a very effective immunotherapy.

Adolescent↗
PubMed1995

[A preliminary study on bioactivity of orange and tangerine peel extracts against aphis and mites].

An assay was made on the bioactivity of the extracts of tangerine peel from Cinocitrus tangerina, orange peel from Citrus sinensis and mixed tangerine peel from Cinocitrus sp. against aphis Semia phis heraclei, Aphis craccivora, Uroleucon gobonis and Myzus persicae using residual film or topical method, and against mites Tetranychus viennensis and T. trancatus using slide-dip or immersion method. Test results show that these extracts have strong bioactivity against aphids and mites. The corrected mortality regression equations and LC50 (or LD50) of these extracts to pests are presented.

Animals↗
PubMed1995

[Effect of ligands on rotational mobility of Na,K-ATPase].

Phosphorescence anisotropy of eosin-5'-isothiocyanate labelled Na,K-ATPase purified from duck salt glands has been studied. The initial anisotropy value is 0.235 +/- 0.015 (room temperature) and does not depend on the enzyme conformation (sodium or potassium). The experimental curve is fitted into a two-exponential curve with residual term, the fast component corresponds to the rotational mobility of the functional unit of Na,K-ATPase (promoter), while the slow one--to that of larger associates. In the presence of ligands modifying the conformational state of Na,K-ATPase (sodium, potassium, ATP) the rotational mobility of the fast component does not change in contrast with the slow one. A comparison of the enzyme rotational mobility in the presence of ligands simulating different steps of hydrolytic cycle suggests that interprotomer interactions are changed in the course of hydrolytic cycle: the fraction of larger associates increases at the step of the enzyme interactions with potassium ions, whereas their mobility in the bilayer enhances sharply after interaction with ATP. In the presence of the 2% non-ionic detergent, C12E9, the initial anisotropy value decreases down to 0.1; the residual term disappears thereby, while the curve is still two-exponential. However, the difference in the rotational mobility of sodium and potassium conformers diminishes. At the same time, the ratios between protomers and oligomers in the presence of sodium and potassium become approximated. This indicates that in the presence of the detergent high molecular weight associates are solubilized, the mobility of the both protomers and oligomers of Na,K-ATPase increases, while the difference between the mobilities of sodium and potassium conformers is disappeared.

Animals↗
PubMed1995

Sublocalization of an ataxia-telangiectasia gene distal to D11S384 by ancestral haplotyping in Costa Rican families.

In an effort to localize a gene for ataxia-telangiectasia (A-T), we have genotyped 27 affected Costa Rican families, with 13 markers, in the chromosome 11q22-23 region. Significant linkage disequilibrium was detected for 9/13 markers between D11S1816 and D11S1391. Recombination events observed in these pedigrees places A-T between D11S1819 and D11S1960. One ancestral haplotype is common to 24/54 affected chromosomes and roughly two-thirds of the families. Inferred (ancestral) recombination events involving this common haplotype in earlier generations suggest that A-T is distal to D11S384 and proximal to D11S1960. Several other common haplotypes were identified, consistent with multiple mutations in a single gene. When considered together with all other evidence, this study further sublocalizes the major A-T locus to approximately 200 kb, between markers S384 and S535.

Ataxia Telangiectasia↗
PubMed1995

[Myocardial damage after high tension electricity injury in rabbits].

The experiment was designed to study the condition of rabbit myocardium after 10,000-Volt high tension electricity injury by using light and electron microscopes. Early change in myocardium was detected and it took a dynamic development. Also, the enzymogram of myocardium was found to be altered parallel with the pathological alteration, apart from significant changes showed in electrocardiograms. The result of the study demonstrated that organic injury occurred in myocardium after high tension electricity injury.

Animals↗
PubMed1995

[Organ regeneration and somatic embryogenesis from young stems of Fritillaria sinica].

Regenerated bulbs and embryogenetic calli were inducted from young stems of Fritillaria sinica cultured on Murashige and Skoog (MS) medium supplemented with alpha-naphthale-neacetic acid (NAA), 2, 4-dichlophenexy-acetin acid (2, 4-D), 6-benzylaminopurine (6BA) and kenetin (Kt) respectively. The callus cultures used for the organ regeneration and somatic embryogenesis were subcultured at intervals of 30-40 days on MS medium+NAA 1mg/L + 6BA 0.5mg/L. In general, the bulbs can be obtained from cultured Fritillaria sinica through three ways: (1) induction from explants; (2) production of adventitious buds or (3) somatic embryogenesis.

Culture Media↗
PubMed1995

Effects of osthole on isolated guinea pig heart atria.

AIM: To study the effects of osthole (Ost) on the isolated guinea pig atria and the relationship between Ost effect and Ca2+. METHODS: Contractions of left atria were induced by electric stimulations. The contractile amplitude of left atria pre- and post-treated with Ost was measured according to the cumulative concentration method, the drug being added at 15 min intervals, the pA2 or pD2' were calculated. It were measured that the effects of Ost to the positive staircase and to the post-rest potential enhancement. The contractile responses were recorded via an auto-equiolibration recording instrument. RESULTS: Ost 10-300 mumol.L-1 and Ver 0.1-30 mumol.L-1 decreased the contractile force and inhibited the isoprenaline-induced restoration of contractile response in the left atria rendered inexcitable by KCl 25 mmol.L-1. Ost and Ver antagonized the CaCl2- and isoprenaline-induced positive inotropic response noncompetively, the pD2' values to Ost were 4.41 +/- 0.13 and 4.90 +/- 0.15, to Ver were 6.53 +/- 0.22 and 6.91 +/- 0.17, respectively. Both of them inhibited the contraction of the left atrium and reversed the frequency-contraction response from positive to negative staircase in the higher dosage (500 and 1 mumol.L-1), but they showed only slight inhibitory effect on post-rest potentiation. CONCLUSION: Ost was similar to, but much less potent than Ver in inhibiting the isolated guinea pig atria.

Animals↗