Roles of sulfonylurea receptor 1 and multidrug resistance protein 1 in modulating insulin secretion in human insulinoma

BACKGROUND:Sulfonylurea receptor 1(SUR1)and multidrug resistance protein 1(MRP1)are two prominent members of multidrug resistance proteins associated with insulin secretion. The aims of this study were to investigate their expression in insulinomas and their sole and synergistic effects in modulating abnormal insulin secretion. METHODS:Fasting glucose,insulin and C-peptide were measured in 11 insulinoma patients and 11 healthy controls. Prolonged oral glucose tolerance tests were performed in 6 insulinoma p...     

Manganese inhalation by rhesus monkeys is associated with brain regional changes in biomarkers of neurotoxicity.

The purpose of this study was to evaluate biochemical markers of neurotoxicity following subchronic manganese sulfate (MnSO(4)) inhalation. Juvenile rhesus monkeys were exposed to MnSO(4) at 0, 0.06, 0.3, or 1.5 mg Mn/m(3) for 65 days. Glutamine synthetase (GS), glutamate transporters (glutamate transporter-1 [GLT-1] and glutamate/aspartate transporter [GLAST]) and tyrosine hydroxylase (TH) protein levels, metallothionein (MT), GLT-1, GLAST, TH and GS mRNA levels, and total glutathione (GSH) levels were assessed in known targets (caudate, globus pallidus, putamen) as well as the cerebellum, frontal cortex, and olfactory cortex. All MnSO(4)-exposed monkeys had decreased pallidal GS protein, decreased caudate GLT-1 mRNA, decreased pallidal GLAST protein, and increased olfactory cortical TH mRNA levels. Monkeys exposed to MnSO(4) at 0.06 or 0.3 mg Mn/m(3) had significantly increased pallidal mRNA levels for GLT-1, GLAST, and TH. Monkeys exposed to MnSO(4) at > or = 0.3 mg Mn/m(3) had several alterations including decreased frontal cortical MT mRNA, decreased caudate, globus pallidus, olfactory cortex, and cerebellum GLT-1 protein, decreased olfactory cortex and cerebellum GLAST protein, increased cerebellar GLAST mRNA, and decreased pallidal TH protein levels. Lastly, GSH levels were significantly increased in the frontal cortex and decreased in the caudate of monkeys exposed to the 1.5-mg Mn/m(3) compared to the controls. Overall, as in our previous studies, we observed that increased Mn concentrations due to airborne Mn exposure differentially affects biomarkers in each brain region (e.g., GSH was increased in the frontal cortex and decreased in the caudate despite two- to threefold increases in Mn concentrations in these regions).     

不同证候H22荷瘤小鼠肿瘤ABC转运蛋白家族基因转录特征

目的:观察不同证候H22荷瘤小鼠肿瘤组织ABC转运蛋白家族基因表达的特征。方法:对来源于早期邪毒壅盛和单纯气虚、中期阳气虚和中晚期气阴阳虚四种证候小鼠H22肿瘤组织4张Affymetrix GeneChip Mouse Exon 1.0 STArray数据标准化处理后,筛选其中的ABC转运蛋白基因进行差异分析。结果:从芯片中共筛选出与ABC转运蛋白有关的基因47个,以邪毒壅盛小鼠肿瘤基因转录最活跃,气虚次之,阳气虚最低;四种常见证候间共有25个基因转录具有明显差异;Abce1和Abcf1等7个基因中在四种常见证候肿瘤中转录水平最高。结论:Tap1(Abcb2)和Abcd2等6个高表达基因可能是邪毒壅盛型小鼠肿瘤增长快的重要因素;不同证候荷瘤小鼠肿瘤组织中的ABC转运蛋白基因转录既存在一定共性又存在很大差异,进一步证明了H22荷瘤小鼠证候客观存在的物质基础,为中医辨证论治提供分子依据。     

高尿酸血症大鼠肾小管上皮细胞OAT3表达的变化

目的 研究高尿酸血症状态下Wistar大鼠肾小管上皮细胞有机阴离子转运体3(OAT3)表达水平的变化.方法 20只雄性Wistar大鼠随机分为对照组和高尿酸血症组,高尿酸血症组饲以高酵母饲料并给予腺嘌呤100 mg/(kg·d)灌胃,定期监测大鼠血尿酸、肌酐、尿素氮水平,应用免疫组织化学技术检测大鼠肾脏近端小管上皮细胞OAT3的表达水平.结果 实验第14天,高尿酸血症组大鼠血尿酸水平显著高于对照组(t′=-15.00,P<0.01);高尿酸血症组OAT3的吸光度值较对照组明显降低(t=3.299,P<0.01),灰度值较对照组明显升高(t=-3.337,P<0.01).结论 高尿酸血症大鼠肾小管上皮细胞中OAT3 蛋白表达水平显著降低,OAT3可作为研发治疗高尿酸血症药物作用靶点.     

新肿瘤相关抗原MG－AgS在肺癌中的免疫组化研究

肿瘤相关抗原的发现对于肿瘤的诊断和治疗都具有重要的意义。本文作者运用ＡＢＣ免疫组织化学技术，采用ＭＧ系列单克隆抗体，对一组新的胃癌相关抗原ＭＧ─ＡｇＳ在肺部病变中的表达进行了免疫组织化学研究，在检测的８８例肺癌标本中，ＭＧ─ＡｇＳ的阳性率为７３．９％。其中肺的腺癌阳性率为８７．５％（２８／３２），肺的鳞癌阳性率为７５％（１８／２４），肺的小细胞癌阳性率为６０．８％（１４／２３），肺的大细胞癌阳性率为５５．６％（５／９）；在检测的２５例肺结核标本中，ＭＧ─ＡｇＳ的阳性率为４％（１／２５）；１０例肺部炎症和１０例正常粘膜ＭＧ─ＡｇＳ则均为阴性。由此提示：①ＭＧ─ＡｇＳ肿瘤相关抗原在肺癌组织中占有明显优势，对于ＭＧ─ＡｇＳ肿瘤相关抗原的检测，将有助于肺癌的病理组织学诊断，而且ＭＧ─ＡｇＳ分布特征有助于肺癌组织学分型；②ＭＧ系列单克隆抗体对肺部肿瘤也同样具有较高的特异性和敏感性，并可用于肺部肿瘤的免疫示踪和导向方面的研究。     

Overexpression of Multidrug Resistance Protein Gene in Human Cancer Cell Lines Selected for Drug Resistance to Epipodophyllotoxins

Overexpression of either the multidrug resistance 1 (MDR1) gene or multidrug resistance protein (MRP) gene is involved in acquisition of multidrug-resistant phenotypes in human cancer cells. In this study we examined whether selection for resistance to the epipodophyllotoxins, etoposide/teniposide (VP16/VM26), could induce overexpression of MDR1 or MRP. We have previously isolated two VP16/VM26-resistant KB cell lines. Two VP16/VM26-resistant KB cell lines, KB/VM-1 and KB/VM-4, which were selected by stepwise exposure to VM26 had decreased accumulation of [³H]VP16 and increased levels of MRP, but no apparent expression of MDR1 gene was observed. Another VP16/VM26-resistant KB cell line, KB/VP-4, which was further isolated from a VP16-resistant KB cell line, KB/VP-2, had decreased accumulation of [³H]VP16 and showed overexpression of MRP gene, but not that of MDR1 gene. We also isolated a VP16-resistant cell line, IN157/VP-1, from a human glioma cell line IN157. IN157/VP-1 cells showed decreased accumulation of [³H]VP16 and overexpression of MRP gene, but not of MDR1. These findings suggest that selection for resistance to VP16/VM26, preferentially induces overexpression of MRP gene.     

Langerhans cells in human papillomavirus (HPV) lesions of the uterine cervix identified by the monoclonal antibody OKT-6

The local inflammatory cell infiltrates in 263 cervical punch biopsies of the women followed-up since 1981 (16 +/- 14 months, mean +/- S.D.) for an established human papillomavirus (HPV) lesion with or without concomitant cervical intraepithelial neoplasia (CIN) were analysed for occurrence of Langerhans cells, defined by the monoclonal antibody OKT-6 using the avidin-biotin peroxidase complex (ABC) technique. OKT-6+ cells remained at the constant low level (1.5-1.9% of the inflammatory cells) in the different types of HPV lesions (flat, inverted or papillomatous condylomas), their percentages (range 0.8-2.1% of the cells) being slightly affected by the grade of HPV-associated CIN, however, (P less than 0.05 between HPV-CIN I and HPV-CIS). Although cervical HPV lesions characteristically are a disease of young females, the relative levels of in situ Langerhans cells did not show any age-dependence. Furthermore, the intensity of the inflammatory cell infiltrate did not correlate with the relative levels of OKT-6+ cells in the biopsies. Practically identical (1.6%) levels of OKT-6+ cells were found in the first biopsies of the HPV lesions shown to regress during the follow-up period (28.8% of cases), when compared with those (1.7%) in the lesions persisted (52.1% of cases) or progressed (19.1% of lesions). The results are discussed in terms of the proposed immune surveillance function against viral infections, attributed to Langerhans cells in the SALT/MALT concept.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transport Activity of Human MRP3 Expressed in Sf9 Cells: Comparative Studies with Rat MRP3

Purpose. Multidrug resistance-associated protein 3 (MRP3) was initially cloned as a hepatic transporter induced under cholestatic/hyperbilirubinemic conditions. In the present study, transport property of human MRP3 (hMRP3) was compared with that of rat MRP3 (rMRP3). Methods. Adenosine 5 triphosphate (ATP)-dependent uptake of several organic anions into the membrane vesicles isolated from the Sf9 cells expressing hMRP3 and rMRP3 was measured by rapid filtration technique. Results. ATP-dependent uptake of glucuronide conjugates, glutathione conjugates, and [³H]methotrexate (MTX) was stimulated by infection of cDNAs for hMRP3 and rMRP3. The mean (± SE) K_m values for the uptake of 17 estradiol 17-D-glucuronide ([³H]E₂17 G) by hMRP3 and rMRP3 were 42.9 ± 4.3 M and 33.4 ± 2.2 M, respectively. Although the K_i values of glucuronides on the uptake of E₂17G were similar in humans and rats, hMRP3 exhibited higher K_i values toward MTX. In addition, although glycocholate and taurolithocholate 3-sulfate (TLC-S) were transported by both hMRP3 and rMRP3, taurocholate was only transported to a significant degree by rMRP3. Moreover, the inhibitory effect of taurocholate and glycocholate on the transport of E₂17G was much more potent in rMRP3 compared to hMRP3. Conclusion. Collectively, the substrate specificity of hMRP3 resembles that of rMRP3 although differences were observed, particularly in bile acid transport.     

A group of glutamatergic interneurons expressing high levels of both neurokinin-1 receptors and somatostatin identifies the region of the pre-Bötzinger complex

The pre-B?tzinger complex (pre-B?tC) is a physiologically defined group of ventrolateral medullary neurons that plays a central role in respiratory rhythm generation. These cells are located in a portion of the rostral ventrolateral medulla (RVLM) that is difficult to identify precisely for lack of a specific marker. We sought to determine whether somatostatin (SST) might be a marker for this region. The rat pre-B?tC area was defined as a 500-microm-long segment of ventrolateral medulla coextensive with the ventral respiratory group. This region was identified by juxtacellular labeling of neurons with respiratory-related activity and by its location rostral to the phrenic premotor neurons. It contained most of the SST-ir neuronal somata of the RVLM. These cells were small (107 microm(2)) and expressed high levels of preprosomatostatin mRNA. They were strongly neurokinin 1 receptor (NK1R)-ir and were selectively destroyed by saporin conjugated with an NK1R agonist (SSP-SAP). Most SST-ir neurons (>90%) contained vesicular glutamate transporter 2 (VGLUT2) mRNA, and terminals immunoreactive for SST and VGLUT2 protein were found in their midst. Few SST-ir neurons contained GAD-67 mRNA (<1%) or preproenkephalin mRNA (6%). Retrograde labeling experiments demonstrated that over 75% of the SST-ir neurons project to the contralateral pre-B?tC area, but none projects to the spinal cord. In conclusion, the RVLM contains many neurons that express preprosomatostatin mRNA. A subgroup of these cells contains high levels of SST and NK1R immunoreactivity in their somata. These glutamatergic interneurons identify a narrow region of the RVLM that appears to be coextensive with the pre-B?tC of adult rats.     

Identification of a cone bipolar cell in cat retina which has input from both rod and cone photoreceptors

It has been generally accepted that rod photoreceptor cells in the mammalian retina make synaptic contact with only a single population of rod bipolar cells, whereas cone photoreceptors contact a variety of cone bipolar cells. This assumption has been challenged in rodents by reports of a type of cone bipolar cell which receives input from both rods and cones. Questions remained as to whether similar pathways are present in other mammals. We have used an antiserum against the glutamate transporter GLT1-B to visualize a population of cone bipolar cells in the cat retina which make flat contacts with axon terminals of both rod and cone photoreceptor cells. These cells are identified as OFF-cone bipolar cells and correspond morphologically to type cb1 (CBa2) cone bipolar cells which are a major source of input to OFF-beta ganglion cells in the cat retina. The GLT1-B transporter was also localized to processes making flat contacts with photoreceptor terminals in rat and rabbit retinas. Examination of tissue processed for the GluR1 glutamate receptor subunit showed that cb1 cone bipolar cells, like their rodent counterparts, express this alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-selective receptor at their contacts with rod spherules. Thus, a direct excitatory pathway from rod photoreceptors to OFF-cone bipolar cells appears to be a common feature of mammalian retinas.