Biomedical subjects

L Mao

Publications and source records attributed to L Mao.

At least 73 records · Page 4Linked to original sources

PubMed2000

Predicting cancer development in oral leukoplakia: ten years of translational research.

Our 10-year translational study of the oral premalignant lesion (OPL) model has advanced the basic understanding of carcinogenesis. Although retinoids have established activity in this model, a substantial percentage of our OPL patients progress to cancer, especially after treatment is stopped. On the basis of our 10-year OPL study, we have developed the first comprehensive tool for assessing cancer risk of OPL patients. This cancer risk assessment tool incorporates medical/demographic variables, epidemiological factors, and cellular and molecular biomarkers. Between 1988 and 1991, 70 advanced OPL patients were enrolled in a chemoprevention trial of induction with high dose isotretinoin (1.5 mg/kg/day for 3 months) followed by 9 months of maintenance treatment with either low dose isotretinoin (0.5 mg/kg/day) or beta-carotene (30 mg/d; total treatment duration, 1 year). We assessed the relationship between cancer risk factors and time to cancer development by means of exploratory data analysis, logrank test, Cox proportional hazard model, and recursive partitioning. With a median follow-up of 7 years, 22 of our 70 patients (31.4%) developed cancers in the upper aerodigestive tract following treatment. The overall cancer incidence was 5.7% per year. The most predictive factors of cancer risk are OPL histology, cancer history, and three of the five biomarkers we assessed (chromosomal polysomy, p53 protein expression, and loss of heterozygosity at chromosome 3p or 9p). In the multivariable Cox model, histology (P = 0.0003) and the combined biomarker score of chromosomal polysomy, p53, and loss of heterozygosity (P = 0.0008) are the strongest predictors for cancer development. Retinoic acid receptor beta and micronuclei were not associated with increased cancer risk. We have demonstrated a successful strategy of comprehensive cancer risk assessment in OPL patients. Combining conventional medical/demographic variables and a panel of three biomarkers can identify high risk patients in our sample. This result will need to be validated by future studies. With the identification of high risk individuals, more efficient chemoprevention trials and molecular targeting studies can be designed.

Alcohol Drinking↗

PubMed2000

Microinjection of nociceptin (Orphanin FQ) into nucleus tractus solitarii elevates blood pressure and heart rate in both anesthetized and conscious rats.

The role of nociceptinergic transmission in the nucleus tractus solitarii (NTS) in the central modulation of cardiovascular activity was investigated in pentobarbital-anesthetized and conscious rats. Pharmacological activation of nociceptin receptors with a unilateral injection of synthetic nociceptin into the NTS, wherein injection of L-glutamate (1 nmol) caused typical depressor responses, elevated blood pressure and heart rate (HR) in most of the anesthetized rats. The elevation of blood pressure and HR by nociceptin was dose-dependent (0.04, 0.2, and 1 nmol) with a threshold dose of 0.2 nmol. At 1 nmol, changes in blood pressure and HR were evident at 5 min, and remained for 45 min after injection. Pretreatment with the selective nociceptin receptor antagonist nocistatin (1 nmol) into the NTS abolished the nociceptin-induced hypertension and tachycardia. In contrast, the nonselective opioid receptor antagonist naloxone (5 nmol) did not modify the cardiovascular responses to nociceptin. Intra-NTS injection of nocistatin (0.04 and 1 nmol) and naloxone alone had no significant effect on baseline blood pressure and HR. In chronically cannulated and conscious rats, similar pressor and tachycardic responses were induced by intra-NTS injection of 1 nmol of nociceptin. However, changes in blood pressure and HR were rapid, and quickly returned to normal levels within 10 min. These data suggest that the newly discovered nociceptinergic transmission in the NTS has a powerful influence on peripheral hemodynamic activity. This influence is inhibitory and may not be tonically active under normal physiological conditions. Moreover, the cardiovascular responses to exogenous nociceptin were mediated through activation of specific nociceptin receptors rather than typical naloxone-sensitive opioid receptors.

Anesthesia↗

PubMed2000

N-(4-hydroxyphenyl)retinamide in the chemoprevention of squamous metaplasia and dysplasia of the bronchial epithelium.

Lung cancer remains the number one cause of cancer-related deaths in the United States. To reduce the mortality associated with this disease, individuals at risk must be identified prior to the development of lung cancer, and effective prevention strategies must be developed. One such strategy is to use retinoids like N-(4-hydroxyphenyl)retinamide (4-HPR), which has been found to possess chemopreventive activities in preclinical studies. In this study, 139 smokers were registered and 82 were randomized onto a double-blinded, placebo-controlled chemoprevention trial of 4-HPR administered p.o. (200 mg once daily). Of these, 70 participants were eligible for response evaluation. Biopsies were obtained at six predetermined sites in the bronchial tree from participants before and at the completion of 6 months of treatment. 4-HPR treatment had no measurable effect on histopathology (squamous metaplasia and dysplasia) in the bronchial epithelium of current smokers. 4-HPR was detected (104.5+/-64.0 ng/ml, mean +/- SD) in the serum of participants, supporting its potential bioavailability. Serum retinol levels decreased markedly (44% of placebo-treated patients) as a consequence of 4-HPR treatment. Notably, the mRNA level of retinoic acid receptor beta, which is typically increased by retinoid treatment, did not change in the bronchial epithelium of 4-HPR-treated participants. Clonal populations of bronchial epithelial cells were detected by analysis of loss of heterozygosity at putative tumor suppressor loci on chromosomes 3p, 9p, and 17p, and these changes were not altered by 4-HPR treatment. In conclusion, at this dose and schedule, 4-HPR was not effective in reversing squamous metaplasia, dysplasia, or genetic and phenotypic abnormalities in the bronchial epithelium of smokers.

Adult↗

PubMed2000

C-CAM1, a candidate tumor suppressor gene, is abnormally expressed in primary lung cancers.

Previous studies have shown that the expression of the cell-cell adhesion molecule (C-CAM1), located at chromosome 19, is down-regulated in several types of human cancers, including prostate and breast cancers. Two major isoforms of C-CAM1, the long or L-form C-CAM1 and the short or S-form C-CAM1, are derived from the C-CAM1 gene through alternative splicing. Tumor cells transfected with L-form C-CAM1, which contains a cytoplasmic domain, display significantly lower growth rates and less tumorigenicity in both in vitro and in vivo models compared with untransfected tumor cells, suggesting that L-form C-CAM1 may be a tumor suppressor. The transfection of the cytoplasmic domain of L-form C-CAM1 could also cause suppression of tumor growth, further supporting the role of L-form C-CAM1 in tumorigenesis. In contrast to reports of most of the tumor types tested, Ohwada et al. (Am. J. Respir. Cell Mol. Biol., 11: 214-220, 1994) reported that C-CAM1 was not down-regulated or even up-regulated in lung cancer. Because the cytoplasmic domain of L-form C-CAM1 is critical for the tumor suppressor function of C-CAM1, we hypothesized that switching of the isoform rather than down- regulation of C-CAM1 gene expression occurs during lung tumorigenesis. To test this hypothesis, we analyzed pairs of tumor tissue and corresponding normal-appearing lung tissue from 51 patients with non-small cell lung cancer (NSCLC) and 43 cell lines to determine expression profiles of L-form C-CAM1 and S-form C-CAM1 using reverse transcription-PCR. We found that L-form C-CAM1 was the predominant form (75%; 38 of 51) in normal-appearing lung tissue, whereas most (84%; 43 of 51) of the primary NSCLC tissue samples expressed predominantly S-form C-CAM1 (P < 0.0001). Similarly, 19 (79%) of the 24 NSCLC cell lines and 17 (85%) of the 20 small cell lung cancer cell lines expressed predominantly S-form C-CAM1. The frequent alteration of the C-CAM1 expression pattern suggests that C-CAM1 has an important role in lung tumorigenesis.

Adenosine Triphosphatases↗

PubMed2000

[Liver cell culture in bioreactors for in vitro drug studies as an alternative to animal testing].

An important consideration for the utilisation of in vitro culture models for studies on drug metabolism as an alternative to animal testing is the maintenance of a defined degree of cell differentiation. Thus, in vitro conditions reflecting as near as possible the in vivo situation of the cells within the whole organ are required. A bioreactor was developed for the cultivation of liver cells which allows the reorganisation of hepatocytes and non-parenchymal cells of the liver in coculture to form three-dimensional, tissue-like structures including extracellular matrix components produced by the cells. In this study, the vitality and metabolic activity of isolated rat hepatocytes was investigated over a two week culture period in bioreactors. The results show that after a reorganisation phase, the cells preserve specific functions, such as protein and urea synthesis capacity and specific cytochrome P450 activities during the culture period, with maximal values during the first week. Possible applications of the model in pharmaceutical industry are studies on metabolite patterns, enzyme induction, drug-drug-interactions, first pass effects and long-term toxicity of drugs.

Animal Testing Alternatives↗

PubMed2000

Response and determinants of sensitivity to paclitaxel in human non-small cell lung cancer tumors heterotransplanted in nude mice.

The lack of tumor models that can reliably predict for response to anticancer agents remains a major deficiency in the field of experimental cancer therapy. Although heterotransplants of certain human solid tumors can be successfully grown in nude mice, they have never been appropriately explored for prediction of in vivo chemosensitivity to anticancer agents. We determined the tumor response rate and studied the influence of several biological and molecular tumor parameters on the in vivo sensitivity to paclitaxel in a series of heterotransplanted human non-small cell lung cancer (NSCLC) tumors. One hundred consecutive resected NSCLC tumors were heterotransplanted s.c. in nude mice. The in vivo sensitivity to i.v. paclitaxel (60 mg/kg every 3 weeks) was studied in 34 successfully grown heterotransplants. Treatment started when the tumors reached a size of 5 mm in diameter, and strict standard clinical criteria (>50% shrinkage in tumor weight or cross-sectional surface) were used to define tumor response. Baseline multidrug resistance protein (MRP), Her-2/neu, and epidermal growth factor receptor (EGFR) expression, and pre- and posttherapy bax and bcl-2 expression were determined by Western blot analysis. p53 status was determined by sequencing. The overall take rate was 46% (95% confidence interval, 36-56%) and was significantly higher (P < 0.05) for squamous carcinoma tumors (75%) than for adenocarcinoma tumors (30%) and bronchoalveolar tumors (23%). The heterotransplants were morphologically very similar to the original tumors. The response rate to paclitaxel was 21% (95% confidence interval, 9-38%). Baseline tumor parameters associated with response were no Her-2/neu expression (none of the responding tumors expressed Her-2/neu versus 48% of the nonresponding tumors, P = 0.05) and baseline bcl-2 expression (all responding tumors expressed bcl-2 versus only 43% of the nonresponding tumors, P = 0.02). There was a trend toward a higher response rate in bax-positive tumors, and MRP- and EGFR-negative tumors, but it was not statistically significant. The response was independent of baseline p53 status and baseline mitotic index. Responding tumors had a higher bax/bcl-2 ratio 24 h after therapy, but the difference was only marginally significant (2.8 for responding tumors versus 1.1 for nonresponding tumors, P = 0.07). The extent of mitotic arrest at 24 h after therapy was not associated with response. Human NSCLC heterotransplants are morphologically identical to the original tumors and have a response rate to paclitaxel that is equivalent to that reported in Phase II studies in patients with advanced NSCLC treated with single-agent paclitaxel. NSCLC heterotransplants deserve to be explored to evaluate new agents for lung cancer and to predict clinical response on an individual basis in selected groups of patients.

ATP-Binding Cassette Transporters↗

PubMed2000

[Changes of T lymphocyte and CD4+ T helper subsets in peripheral blood from women with unexplained recurrent spontaneous abortion].

OBJECTIVE: To investigate the relationship between occurrence of unexplained recurrent spontaneous abortion(URSA) and immune function of T lymphocytes. METHODS: T lymphocyte subsets and CD4+ T helper subsets (including T helper 1 and T helper 2 cells) in peripheral blood from 30 cases with URSA and 24 healthy women (controls) were detected by enzyme-linked immunospot assay (ELISPOT). RESULTS: The percentage of CD4+ positive T lymphocytes in URSA group was higher than that in the controls (60% vs 45%, P < 0.05). Compared with the normal group, the percentage of Th1 cells increased (26% vs 14%, P < 0.01) but the percentage of Th2 cells decreased (7% vs 20%, P < 0.05), the ratio of Th1 to Th2 increased (3.80 vs 0.73, P < 0.01) in the URSA group. CONCLUSIONS: The occurrence of URSA might be associated with proliferation of the CD4+ positive T cells and enhancement of cellular immune function mediated by Th1 cells.

Abortion, Habitual↗

PubMed1999

Gender differences in p53 mutational status in small cell lung cancer.

Mutations in the p53 tumor suppressor gene have been demonstrated to be one of the most frequent genetic abnormalities in human cancers. Previous studies have shown that the frequency of p53 mutations is significantly higher in small cell lung cancer than in non-small cell lung cancer. However, this conclusion was based in large part on data derived from tumor cell lines and from studies with relatively small sample sizes and biased gender populations. To determine the mutational frequency in the p53 tumor suppressor gene and a potential difference in gender, we analyzed primary small cell lung cancer tumors from 65 patients (37 males and 28 females) for p53 mutations between exons 5 and 9. Mutations were found in 37 of 65 tumors (57%) within the region of p53 analyzed. Interestingly, none of the tumors from females contained more than one mutation, whereas four of the tumors from males contained more than one mutation. The most common mutation in this population was an adenosine-to-guanine transition (27%), followed by guanine-to-thymidine transversion (17%) and guanine-to-adenosine transition (12%). The gender difference in p53 mutational rate identified in this study suggests that a higher proportion of female tumors may develop through pathways not involving p53 mutations.

Adult↗

PubMed1999

Progressive cardiac dysfunction and fibrosis in the cardiomyopathic hamster and effects of growth hormone and angiotensin-converting enzyme inhibition.

BACKGROUND: Growth hormone (GH) improves cardiac function in the rat with myocardial infarction, but its effects in a model of primary dilated cardiomyopathy have not been reported. GH effects were examined at early (4 months) and late (10 months) phases of disease in the cardiomyopathic (CM) hamster, and the combination of GH with chronic ACE inhibition was assessed in late-phase heart failure. METHODS AND RESULTS: CM hamsters (CHF 147 line) at 4 months showed severe systolic left ventricular (LV) dysfunction with normal LV filling pressure, and at 10 months there was more severe systolic as well as diastolic dysfunction with increasing myocardial fibrosis. Recombinant human GH alone for 3 weeks at age 4 months increased LV wall thickness and reduced systolic wall stress without altering diastolic wall stress, whereas at 10 months, wall stress and fractional shortening did not improve. The LV dP/dt(max) was enhanced at both ages by GH, which at 4 months reflected increased contractility, but at 10 months was most likely caused by elevation of the LV filling pressure. The increasing degree of fibrosis correlated inversely with LV function but was unaffected by GH. In other CM hamsters, high-dose ACE inhibition alone (quinapril), started at 8 months and continued for 11 weeks, improved LV function and inhibited unfavorable remodeling, but the addition of GH for 3 weeks at age 10 months produced increased wall thickness with little additional functional benefit and increased the LV filling pressure and diastolic wall stress. CONCLUSIONS: GH treatment alone improved LV dysfunction at 4 months of age in CM hamsters by increasing contractility and reducing wall stress but had few beneficial effects at 10 months in severe LV failure. After chronic ACE inhibition, addition of GH at 10 months had no additional beneficial effects and further increased LV diastolic pressure. These differing effects of GH may relate to the progressive increase of LV fibrosis in the CM hamster.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1999

Loss of Fhit is frequent in stage I non-small cell lung cancer and in the lungs of chronic smokers.

Abnormalities of FHIT, a candidate tumor suppressor gene at 3p14.2, have been found frequently in multiple tumor types including non-small cell lung cancer (NSCLC). To investigate whether FHIT inactivation plays a role in early lung tumorigenesis, Fhit levels were determined by immunohistochemistry in tumors from 87 patients with stage I NSCLC and in 372 bronchial biopsy specimens from 86 chronic smokers without evidence of malignancy. We found that 49% of NSCLC specimens demonstrated significantly decreased staining or lack of staining for Fhit. However, Fhit expression status was not significantly associated with disease-free survival or overall survival. Analysis of a subset of 76 specimens on which microsatellite analysis at the FHIT locus was performed did not show a strong association between loss of heterozygosity at FHIT and Fhit expression, suggesting the presence of complex mechanisms of Fhit inactivation. Of 372 bronchial biopsies from chronic smokers, 86 biopsies (23%) exhibited decreased Fhit expression or lack of Fhit expression. In 37 of 86 (43%) subjects, decreased Fhit expression or lack of expression was observed in at least one biopsy site. Loss of Fhit expression was significantly higher in bronchial metaplastic lesions (23 of 49 lesions, 47%) than in histologically normal bronchial epithelium (63 of 323 specimens, 20%; P < 0.001). Smokers with a metaplasia index of > 15% had a higher frequency of loss of Fhit expression than those with a metaplasia index of < or = 15% (P = 0.015). Interestingly, current smokers had a higher rate of loss of Fhit expression than former smokers (P = 0.02). Our data indicate that Fhit expression is significantly reduced in a substantial number of early-stage NSCLC and preneoplastic lesions in chronic smokers. The association between cigarette smoking and Fhit expression suggests a role for FHIT in the initiation of smoking-related lung tumorigenesis.

Acid Anhydride Hydrolases↗

PubMed1999

Protection against acute amphetamine-induced behavior by microinjection of a group II metabotropic glutamate receptor agonist into the dorsal striatum of rats.

Group II metabotropic glutamate receptors (mGluRs) are distributed both pre- and postsynaptically in the striatum. By bilaterally administering a subgroup-selective agonist or antagonist into the dorsal striatum of chronically cannulated rats, this study examined the role of striatal group II mGluRs in the regulation of basal and dopamine-stimulated motor behavior. Intrastriatal injection of a group II agonist, (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV, 0.01, 0.1 and 1 nmol), dose-dependently reduced basal levels of motor activity. Pretreatment of rats with intrastriatal DCG-IV at a higher dose (1 nmol), but not a lower dose (0.01 nmol), produced complete or partial blockade of hyperlocomotion induced by acute injection of amphetamine (2.5 mg/kg, i.p.) or apomorphine (1 mg/kg, s.c.), respectively. Blockade of group II mGluRs by intrastriatal injection of a group II antagonist, (RS)-alpha-methylserine-O-phosphate monophenyl ester (10 nmol), was found to: (i) induce a moderate locomotion by itself; (ii) augment amphetamine-stimulated behaviors and (iii) attenuate DCG-IV-induced reduction of basal and amphetamine-stimulated motor activity. These data demonstrate that the group II mGluRs in the striatum play a significant role in the inhibitory modulation of tonic and phasic motor activity, which is most likely processed through both pre- and postsynaptic mechanisms.

Amphetamine↗

PubMed1999

Inhibition of cardiovascular activity following microinjection of novel opioid-like neuropeptide nociceptin (orphanin FQ) into the rat rostral ventrolateral medulla.

Nociceptin (orphanin FQ), the newly discovered endogenous ligand for the novel opioid receptor-like 1 receptor, has been initially found to participate in pain modulation. In this study, centrally mediated cardiovascular actions of this peptide were investigated in the alpha-chloralose/urethane-anesthetized rats. We found that bilateral injection of nociceptin (10 nmol) into the rostral ventrolateral medulla (RVLM), wherein injection of excitatory amino acid dl-homocysteic acid (3 nmol) induced typical pressor responses, significantly reduced arterial blood pressure and heart rate by -32% and -15%, respectively. Reduction of blood pressure and heart rate in response to intra-RVLM injection of nociceptin was dose-dependent with a threshold dose being 3 nmol. Pretreatment with the selective nociceptin receptor antagonist, [Phe1psi(CH2-NH)Gly2]NC(1-13)NH2 (10 nmol), into the RVLM abolished the nociceptin-induced cardiovascular inhibition. In contrast, non-selective opioid receptor antagonist, naloxone (10 nmol), did not modify the hypotension and bradycardia induced by nociceptin, even though naloxone at the same dose prevented reduction of blood pressure and heart rate induced by intra-RVLM injection of methionine-enkephalin (3 nmol). Both [Phe1psi(CH2-NH)Gly2]NC(1-13)NH2 and naloxone injection alone had no significant effect on baseline blood pressure and heart rate. These data suggest that the newly discovered opioid-like neuropeptide nociceptin in the CNS exert powerful influence on hemodynamic activity by affecting the RVLM neurons. This influence is inhibitory in nature, which may not be active in normal physiological conditions. Moreover, the cardiovascular effects of nociceptin were mediated by activation of specific nociceptin receptors rather than typical naloxone-sensitive opioid receptors.

Animals↗

PubMed1999

Expression of DMBT1, a candidate tumor suppressor gene, is frequently lost in lung cancer.

DMBT1 is a candidate tumor suppressor gene located at 10q25.3-26.1. Homozygous deletion of the gene was found in a subset of medulloblastoma and glioblastoma multiforme; lack of expression was noted in the majority of these tumors. In adult tissues, DMBT1 is highly expressed only in lung and small intestine tissues, indicating its important role in these organs. By analyzing lung cancer cell lines and primary lung tumors using reverse transcription-PCR, we found that 100% (20 of 20) of small cell lung cancer (SCLC) cell lines and 43% (6 of 14) of non-small cell lung cancer (NSCLC) cell lines lacked DMBT1 expression. Furthermore, 45% (9 of 20) of the primary NSCLCs exhibited a markedly low level of gene expression compared with corresponding normal lung tissues, indicating that lack of gene expression also occurs in primary lung cancers. To determine the potential mechanisms for lack of DMBT1 expression in lung cancer, we analyzed tumor cell lines for potential intragenic homozygous deletions of the gene and found such homozygous deletions in 10% (4 of 40) of SCLC cell lines but in none of 14 NSCLC cell lines. Moreover, the loss of expression could not be rescued by treatment with a demethylation agent (5-azacytidine) in two NSCLC cell lines lacking DMBT1 expression, suggesting that de novo methylation of the promoter region of the gene is unlikely to play a role in inactivation of the gene. We then sequenced the whole coding region of DMBT1 in 8 NSCLC cell lines that expressed DMBT1 and 20 primary NSCLCs. A potential point mutation at codon 52 was detected in a NSCLC cell line and resulted in an amino acid change from serine to tryptophan. Three common polymorphisms were also detected in tissues analyzed. Our data demonstrate that DMBT1 expression is frequently lost in lung cancer due to gene deletion and to other not yet identified mechanisms, suggesting that inactivation of DMBT1 may play an important role in lung tumorigenesis.

Agglutinins↗

PubMed1999

Long-term fate of heterotopic liver transplants in rats with portal vein inflow only.

Previous studies have suggested that hepatic arterial flow in heterotopic partial liver transplants is necessary to ensure graft survival and regenerative capacity. This report presents findings in a syngeneic rat strain (Lewis) that partial liver transplants can be successfully heterotopically transplanted in the long term with the only inflow coming from the portal vein. When the host liver undergoes a nearly complete resection at 3-4 weeks, the transplanted liver regenerates to maintain the health of the host. Moderate to massive hepatocellular necrosis occurs in the first 3 months postoperatively, with recovery by 4-5 months. Liver transplants 8-10 months postoperatively appear architecturally normal. No host liver tissues were found to be regenerating after subtotal host liver resection. We conclude that portal vein reconstruction without hepatic arterial inflow can sustain a partial liver transplant in the long term, replacing the function of the host liver.

Anastomosis, Surgical↗

PubMed1999

Update on sequential isologous rat organ transplantation: pancreaticoduodenal and kidney transplantations.

This periodic report includes intermittent results of consecutive pancreaticoduodenal (Pd) and kidney (Kt) transplants in inbred rats and results on double kidney transplants that did not follow sequential transplant protocol. Eight 24-month-old Lewis pancreas, kidney, and aorta served histological controls showing normal histological architecture with no atherosclerosis developed in the aorta. Thirty-four month old pancreas and thirty-two month old kidneys, which resided in young hosts for at least three occasions, appeared as youthful Pd and Kt grafts. They show normal histological appearance for more than the expected life span of a Lewis rat. The fact that not only pancreases but also kidneys outlived their host leads to the study of other different organs' viability as aged valuable grafts. Nevertheless, the threats by the development of atherosclerosis in graft-associated aortas resulted in slow progression of the follow-ups.

Animals↗

PubMed1999

Simultaneous determination of oxalic, fumaric, maleic and succinic acids in tartaric and malic acids for pharmaceutical use by ion-suppression reversed-phase high performance liquid chromatography.

A reliable method for the simultaneous determination of oxalic, fumaric, maleic, and succinic acids in tartaric and malic acids for pharmaceutical use by reversed-phase ion-suppression high performance liquid chromatography is presented. HPLC was achieved on a Nova-Pak C18 column by isocratic elution using water adjusted to pH 2.10-2.15 with perchloric acid, and detection was by UV adsorption at a wavelength of 210 nm. This method was found to be superior to previous liquid chromatography as well as other classical assay, and to be an attractive choice for the analysis of these compounds.

Chromatography, High Pressure Liquid↗

PubMed1999

The Mla (powdery mildew) resistance cluster is associated with three NBS-LRR gene families and suppressed recombination within a 240-kb DNA interval on chromosome 5S (1HS) of barley.

Powdery mildew of barley, caused by Erysiphe graminis f. sp. hordei, is a model system for investigating the mechanism of gene-for-gene interaction between large-genome cereals and obligate-fungal pathogens. A large number of loci that confer resistance to this disease are located on the short arm of chromosome 5(1H). The Mla resistance-gene cluster is positioned near the telomeric end of this chromosome arm. AFLP-, RAPD-, and RFLP-derived markers were used to saturate the Mla region in a high-resolution recombinant population segregating for the (Mla6 + Mla14) and (Mla13 + Ml-Ru3) resistance specificities. These tightly linked genetic markers were used to identify and develop a physical contig of YAC and BAC clones spanning the Mla cluster. Three distinct NBS-LRR resistance-gene homologue (RGH) families were revealed via computational analysis of low-pass and BAC-end sequence data derived from Mla-spanning clones. Genetic and physical mapping delimited the Mla-associated, NBS-LRR gene families to a 240-kb interval. Recombination within the RGH families was at least 10-fold less frequent than between markers directly adjacent to the Mla cluster.

Alleles↗

PubMed1999

[Long-term outcome and relevant factors of thymectomy for myasthenia gravis].

OBJECTIVE: To evaluate the long-term outcome and relevant factors of thymectomy for myasthenia gravis (MG) by analyzing patients data. METHODS: 114 patients with MG operated between May 1990 and 1997 were reviewed. The results of operation were classified in to 4 grades: remission, improvement (efficiency includes remission and improvement), no change, and deterioration. The relativity between the long-term outcome and the factors of age, sex, the serum titer of AchR antibodies, duration of disease, pathological classification of thymus, modified osserman classification, and follow-up period was analyzed by logistic and chi(2) test. RESULTS: There were 47 man and 67 women aged from 4 to 72 years. Follow-up ranged from 10 to 82 months (mean 42, 8 months). The remission rate was 27.2% and the effective rate 67.5%. No patient died in the hospital, and the late-death rate was 7.0% (8 cases). CONCLUSION: Long follow-up (over 5 years) is necessary for evaluating the results of the treatment. There is no correlation between the outcome sex, and the serum titer of AchR antibodies. Associated diseases show no influence on the outcome of thymectomy.

Adolescent↗