Light microscopy of GTP-binding protein (Go) immunoreactivity within the retina of different vertebrates

To examine species differences in the distribution pattern of guanosine triphosphate (GTP)-binding protein (Go) within the vertebrate retina, paraffin-embedded retinae from a number of vertebrate species, including the goldfish, frog, turtle, chicken, monkey, and human, were immunohistochemically stained with affinity-purified antibody against the alpha-subunit of Go. Go-immunoreactive products were found to be located in the neuropil, but not in the cell bodies of neurons, in the retina of all these species. However, some species differences were observed. In the frog, monkey and human, the inner plexiform layer (IPL) was homogeneously stained with this antibody, but in the goldfish, turtle and chicken, the IPL was heterogeneously stained. In the frog, chicken, turtle and human, the outer plexiform layer (OPL) was densely stained with this antibody, but in the goldfish and monkey, the OPL was rather faintly immunoreactive to the antibody. In the goldfish, monkey and human, the outer nuclear layer (ONL) was not immunoreactive to the Go-antibody, whereas in the frog, turtle and chicken, the ONL was immunoreactive to it. The implications of these species differences in Go localization in the vertebrate retina are discussed.     

Link protein shows species variation in its susceptibility to proteolysis.

Human cartilage link protein exists as three native components, while equine, bovine, and porcine cartilage link protein exist as two and Swarm rat chondrosarcoma link protein exists as only one component. These nonhuman link protein components represent intact protein structures, and there is little evidence for proteolytically modified forms in nonhuman tissues. In human cartilage, the proteolytic production of modified link proteins increases with age, whereas high amounts of such products were not seen in the nonhuman tissues. However, the small amounts of link protein fragments that were observed in the nonhuman cartilages were of a similar size to their human counterparts. On digestion of human proteoglycan aggregate with stromelysin, rapid modification of the link protein components occurred, whereas the aggregates from nonhuman cartilages showed incomplete cleavage of their link protein components. The relative resistance of nonhuman link protein to stromelysin may in part be due to a unique amino acid substitution present near the enzymic cleave site.     

Methylglyoxal induces apoptosis mediated by reactive oxygen species in bovine retinal pericytes

One of the histopathologic hallmarks of early diabetic retinopathy is the loss of pericytes. Evidences suggest that the pericyte loss in vivo is mediated by apoptosis. However, the underlying cause of pericyte apoptosis is not fully understood. This study investigated the influence of methylglyoxal (MGO), a reactive alpha-dicarbonyl compound of glucose metabolism, on apoptotic cell death in bovine retinal pericytes. Analysis of internucleosomal DNA fragmentation by ELISA showed that MGO (200 to 800 microM) induced apoptosis in a concentration-dependent manner. Intracellular reactive oxygen species were generated earlier and the antioxidant, N-acetyl cysteine, inhibited the MGO-induced apoptosis. NF-kappaB activation and increased caspase-3 activity were detected. Apoptosis was also inhibited by the caspase-3 inhibitor, Z-DEVD-fmk, or the NF-kappaB inhibitor, pyrrolidine dithiocarbamate. These data suggest that elevated MGO levels observed in diabetes may cause apoptosis in bovine retinal pericytes through an oxidative stress mechanism and suggests that the nuclear activation of NF-kappaB are involved in the apoptotic process.     

Species differences in the relative analgesic potencies of some classical opiates and opioid peptides

The analgesic ED₅₀ values of some classical morphine congeners (morphine, methadone, fentanyl, azidomorphine) in the rat and mouse tail-flick tests were found to be similar. However, several synthetic derivatives of the natural enkephalins were more potent in mice than in rats. (These analogs contain d-amino acid in position 2 and d- or l-sulfonic (or phosphonic) acid residue in position 5). -Endorpin, d-Met², Pro⁵-enkephalinamide and two partial agonists showed intermediate interspecies relative potencies. According to the data obtained, similar opiate receptors might mediate the analgesic action of classical opiates in rats and in mice. However, the opiate receptors responsible for the antinociceptive effects of the above mentioned enkephalin analogues must be dissimilar in the two species examined. The results are discussed in terms of the role of - and -receptors in mediation of the analgesic effect induced by different types of opioids.     

BDBPH—Zn Mn Cd双核配合物的稳定常数及其形态研究

目的测定BDBPH-Zn、Mn、Cd双核配合物的稳定常数,分析不同pH条件下各物种的存在形式及变化规律.方法温度25.0±0.10℃、离子强度0.100mol/L、N2保护下用NaOH标准溶液滴定大环配体BDBPH-金属离子(12)酸性溶液,滴定pH范围2～12,高精度酸度计记录pH值,BEST程序计算稳定常数,SPE和SPEPLOT程序绘制样品分布曲线.结果BDBPH-金属配合物的稳定常数分别为17.72(LogKLZn2),11.58(LogKLMn2),14.28(LogKLCd2).结论配体BDBPH能够与金属离子(Zn、Mn、Cd)形成稳定的双核配合物.     

Metabolism of taxol by human and rat liver in vitro: A screen for drug interactions and interspecies differences

Human liver slices, human liver microsomes, and rat liver microsomes were used to investigate the metabolism of³H-taxol. The effects of drugs frequently coadministered with taxol and the effects of several cytochrome P450 system probes were studied. In all, 16 compounds were screened. After incubation with liver slices or with microsomal protein,³H-taxol was converted into several radioactive species resolved by HPLC. There were qualitative and quantitative species differences in the metabolism of taxol. The pattern of metabolism was similar for both human-derived preparations, with 6-hydroxytaxol being the major metabolite peak. In drug interaction studies performed with human liver microsomes, cimetidine 80 M, and diphenhydramine 200 M, had little or no effect on 6-hydroxytaxol formation. Quinidine, ketoconazole, dexamethasone and Cremophor EL inhibited 6-hydroxytaxol formation with IC₅₀ values of 36 M, 37 M, 16 M and 1 l/ml, respectively, but these concentrations exceed the usual clinical range. Cremophor EL also inhibited microsomal metabolism of taxol, but at 2 l/ml it had little or no effect on 6-hydroxytaxol production by human liver slices. These results suggest that: (1) taxol is metabolized by the cytochrome P450 system; (2) taxol metabolism is different in humans than in rats; (3) taxol metabolism in humans is unlikely to be altered by cimetidine, dexamethasone, or diphenhydramine, drugs regularly coadministered with taxol; (4) taxol metabolism can be indirectly affected by Cremophor EL, the formulation vehicle; (5) taxol metabolism may be altered by concentrations of ketoconazole achievable in humans only at very high doses; and (6) taxol metabolism and drug interaction studies of clinical relevance can be performed in vitro with human liver microsomes and human liver slices, but not with rat liver preparations.Part of this work was presented in poster form at the 84th Annual Meeting of the American Association for Cancer Research, Orlando, Fl., USA, 1993     

Species differences in presynaptic serotonin autoreceptors: mainly 5-HT1B but possibly in addition 5-HT1D in the rat, 5-HT1D in the rabbit and guinea-pig brain cortex

Summary The pharmacological properties of presynaptic serotonin autoreceptors were compared in slices of rat, rabbit, and guinea-pig brain cortex. The slices were preincubated with ³H-serotonin and then superfused with medium containing fluvoxamine 3 mol/l and stimulated four times by trains of four pulses delivered at 100 Hz. Cumulative concentration-response curves were determined and used for the calculation of agonist EC₅₀ values and maximal effects and antagonist K _B values.Unlabelled serotonin itself and the serotonin receptor agonists 5-carboxamidotryptamine (5-CT), 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole (RU 24969) and (±)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) reduced the stimulation-evoked overflow of tritium with a rank order of potency 5-CT = RU 24969 > serotonin > 8-OH-DPAT in the rat and 5-CT > serotonin > RU 24969 > 8-OH-DPAT in the rabbit and guinea-pig. Ipsapirone caused no change. Metitepine and metergoline antagonized the effect of 5-CT; the K _B values were lower in the rabbit and guinea-pig than in the rat. Yohimbine at up to 1 mol/1 did not reduce the evoked overflow of tritium and did not antagonize the inhibitory effect of 5-CT in the rat but reduced the evoked overflow in the rabbit and counteracted the effect of 5-CT in the guinea-pig. (–)-Propranolol, conversely, reduced the evoked overflow of tritium in the rat but neither reduced the evoked overflow nor antagonized the effect of 5-CT in the rabbit and guinea-pig. Isamoltane did not significantly change the effect of 5-CT in any species. In the rat, it also failed to antagonize the inhibitory effect of 8-OH-DPAT but did antagonize the effect of RU 24969. The inhibition caused by 8-OH-DPAT persisted in the presence of idazoxan but was attenuated by metitepine in all species.The experimental conditions used permit the determination of the constants of agonist and antagonist action undistorted by autoinhibition. The results confirm the view that the serotonin axons of rat brain possess 5-HT_1B autoreceptors. They show by direct comparison under identical conditions that the autoreceptors in rabbit and guinea-pig are very similar to each other but differ markedly from those in the rat. The results give additional credence to previous suggestions that, in the rabbit and guinea-pig, the autoreceptors are 5-HT_1D. The serotonin axons of rat brain cortex may possess 5-_1D in addition to 5-HT_1B autoreceptors. In many previous studies agonist potencies at, and antagonist affinities for, presynaptic serotonin autoreceptors have been underestimated due to the use of too intense stimuli to elicit serotonin release. Send offprint requests to N. Limberger at the above address     

山东省恙螨区系研究

目的　调查山东省恙螨的种类分布。方法　现场捕获鼠类及其他野生动物 ,采集体外恙螨 ,结合历次山东省恙螨调查研究文献收集种类资料。结果　已知山东省恙螨 3亚科 9属 2 4种 ,占中国已知恙螨 (4 5 3种 )的 5 .3 0 %。结论　基本摸清了山东省主要地区恙螨的种类区系分布 ,为深入开展恙虫病防治研究提供了依据。     

肖厝口岸恙螨本底调查报告

〔目的〕掌握肖厝口岸鼠形动物所携带的恙螨的种类、分布和季节消长的本底情况。〔方法〕从2004年8月￣2005年7月分别采用捕鼠夹和捕鼠笼对肖厝口岸的鼠形动物所携带的恙螨的种群构成、季节消长进行了调查。〔结果〕本次调查共捕获鼠形动物60只,其中22只携带恙螨,共检集恙螨2938只,经鉴定隶属2科2属4种,其中地理纤恙螨为优势种,占总恙螨数的74.13%。恙螨全年平均密度(恙螨指数)为48.97,鼠体染恙螨率为36.67%。优势鼠种黄胸鼠的恙螨密度最高,为102.48,鼠体染恙螨率为59.26%。全年的季节消长有3个高峰期,最高峰月份为5月。〔结论〕肖厝口岸优势鼠种携带的恙螨率较高,存在着恙虫病发生的可能性。改善港区办公大楼及食堂室内外和与港区连接部的海龙餐馆室内外的环境卫生,消灭恙螨孽生地,加强防治知识的宣传以及开展群众性灭鼠是我们今后工作的重点。每年的5月和12月是开展灭鼠、灭螨的最好时机。     

吉林省中朝边境地区吸血虻的调查研究

目的调查吉林省中朝边境地区4市(县)的吸血虻种分布及种群组成。方法牛诱法采虻。结果在吉林省中朝边境地区的珲春、图门、安图、敦化4市(县)采获吸血虻5属39种,依次分布为31、27、24和28种。采获的虻中短小瘤虻占20.5%,骚扰黄虻占15.6%,痣翅瘤虻占14.1%。痣翅瘤虻(6月中旬)、短小瘤虻(6月中旬)、僻氏虻(7月中旬)、骚扰黄虻(8月上旬)和黑胫瘤虻(8月上旬)在整个活动季节均出现1次高峰。结论优势种为短小瘤虻、骚扰黄虻和痣翅瘤虻。不同月份的虻种群组成有所不同。