Behavioral differences between two inbred strains of Fawn-Hooded rat: a model of serotonin dysfunction

The Fawn-Hooded rat (FH) strain has attracted the attention of some psychopharmacologists because of reports of its exaggerated immobility in the swim test, hypercortisolemia, excessive voluntary intake of alcohol, platelet and central serotonin abnormalities and subsensitivity to serotonergic agonists. However, there appears to be some controversy over several behavioral and physiological characteristics of these rats. The present paper proposes that the lack of reproducible findings can be traced to there being several distinct inbred strains of FH rats. Of the two compared in this communication, the FH/Wjd strain is more immobile in the forced swim test, spends more time in the open arms of the elevated plus maze, and drinks more saccharin and alcohol voluntarily than the FH/Har (Iowa Reactive) strain. Future workers are cautioned to report the source of their FH rats.     

Relation between the thermal expansion coefficient and the heat capacity in halide melts

The thermal expansion coefficients of molten halides have been analyzed. This parameter has been found to be a constant for all halides except for lithium halides. Since the thermal expansion coefficient and the molar heat capacity of halides change symbatically, the ratio of the molar heat capacity to the thermal expansion coefficient is also a constant.     

Poly(anhydride-co-imides): in vivo biocompatibility in a rat model

The degradation and tissue compatibility characteristics of a novel class of biodegradable poly(anhydride-co-imide) polymers: poly[trimellitylimidoglycine-co-1,6-bis(carboxyphenoxy)hexan e] (TMA-gly: CPH) (in 10:90; 30:70 and 50: 50 molar ratios) and poly[pyromellitylimidoalanine-co-1,6-bis(carboxyphenoxy)hexa ne] (PMA-ala:CPH) (in 10:90 and 30:70 molar ratios) were investigated and compared with control poly(lactic acid/glycolic acid) (PLAGA in 50:50 molar ratio) matrices, a well-characterized biocompatible polymer, in rat subcutaneous tissues for 60 days. Polymers were compression-molded into circular discs of 14 mm x 1 mm in diameter. On post-operative days 7, 14, 28 and 60, histological tissue samples were removed, prepared by fixation and staining, and analyzed by light microscopy. PLAGA matrices produced mild inflammatory reactions and were completely degraded at the end of 60 days, leaving implant tissues that were similar to surgical wounds without implants. TMA-gly:CPH (10:90 and 30:70) matrices produced mild inflammatory reactions by the end of 60 days, similar to those seen with PLAGA. TMA-gly: CPH (50: 50) produced moderate inflammatory reactions characterized by macrophages and edema. PMA-ala:CPH matrices elicited minimal inflammatory reactions that were characterized by fibrous encapsulation by the end of 60 days. In vivo degradation rates of poly(anhydride-co-imides) were similar to PLAGA. Both PMA-ala:CPH and TMA-gly: CPH matrices maintained their shapes and degraded at a constant rate over the period of two months. These polymers, possessing good mechanical properties and tissue compatibility, may be useful in weight-bearing applications in bone.     

Effect of feeding clinoptilolite (zeolite) on the performance of three strains of laying hens

1. One hundred and twenty 16-week-old single combed pullets of three strains were fed on a diet containing 135 g protein/kg with or without 50 g clinoptilolite/kg in a trial with 20 hens per treatment. Sterile river sand replaced clinoptilotile in the control diet in order to keep the diets isoenergetic. The hens were individually caged in a naturally ventilated laying house and fed one of the two diets for ten 28-d periods. 2. Significant dietary effects of feeding clinoptilolite were observed with number of eggs laid per hen, shell thickness, efficiency of food utilisation and droppings moisture content. No significant dietary effects between treatments were observed with body weight, age at first egg, egg weight. Haugh units, food intake/hen and rate of amino acid absorption of radioactive lysine and methionine into the bloodstream. Significant differences between strains were observed with regard to all parameters except food intake/hen. There were no significant strain X clinoptilolite interactions.     

Variation in the hepatotoxic effects of carbon disulphide between different strains of rat

The hepatotoxic effects of carbon disulphide have been investigated in an outbred (Porton) strain of rat and in 8 inbred strains. Carbon disulphide (1.38 mmoles/kg body weight) was administered intraperitoneally to rats which had been pretreated with phenobarbitone and starved. Livers were taken for analysis 24 h later. A considerable genetic variation in the response of rats to carbon disulphide was observed. The extent of centrilobular hydropic degeneration varied greatly between strains and was accompanied by a high incidence of focal coagulative necrosis in the most susceptible rats. Analysis of variance of the accompanying changes in liver weight and water content and in total liver cytochrome P450 content gave statistical confirmation of a strain effect in the response to carbon disulphide. Highly significant strain x treatment interactions for these parameters were attributable to changes after carbon disulphide treatment rather than variation between phenobarbitone pretreated starved controls. The experiments were repeated in two blocks, 3 months apart. Block effects and interactions were significant in some cases but were quantitatively small and did not obscure a ranking based on histological assessment. AGUS rats were least affected by carbon disulphide whereas PVG and LEW rats showed extensive liver damage. Other strains (WA, Porton, F344, BDIX, WAG) showed a gradation of response between these extremes.     

Molecular and functional adaptation of the GABA(A) receptor complex during pregnancy and after delivery in the rat brain

The abundance of gamma-aminobutyric acid receptor type A (GABAA receptor) subunit mRNAs and polypeptides as well as muscimol-stimulated 36Cl- uptake were measured in rat cerebral cortex or hippocampus at various times during pregnancy and after delivery. RNase protection assays revealed that the amount of the gamma2L subunit mRNA decreased progressively during pregnancy, in the cerebral cortex and hippocampus, and then returned to control values around the time of delivery. A similar pattern was observed for the alpha5 subunit mRNA in the cerebral cortex, whereas no significant changes were apparent for alpha1, alpha2, alpha3, alpha4, beta1, beta2, beta3 and gamma2S subunit mRNAs. The amounts of gamma2 and alpha1 proteins in the cerebral cortex were measured by immunoblot analysis; whereas the abundance of gamma2 protein decreased during pregnancy, no change was detected in the amount of alpha1 protein. Evaluation for functional significance of the down-regulated gamma2 and alpha5 subunit was made by determining the GABAA receptor function assessed by measurement of muscimol-stimulated 36Cl- uptake in cerebral cortical membrane vesicles. Muscimol-induced 36Cl- uptake was markedly reduced during of pregnancy compared with rats in oestrus. At this same time, the potentiating effects of diazepam and allopregnanolone on muscimol stimulation of 36Cl- uptake also were reduced. In contrast, the effects of muscimol, allopregnanolone and diazepam were significantly increased, relative to animals in oestrus, after delivery.     

鱼雷罐耐材蓄热及散热模型的铁水温降

基于某炼铁厂鱼雷罐热周转过程,建立鱼雷罐热周转耐材蓄热及散热模型,通过数值模拟计算得到鱼雷罐运输铁水的散热量,进一步获得铁水温降.利用该方法对影响铁水温降的主要因素即空罐时间、重罐时间、周转次数、铁水质量和铁水初始温度进行全因子组合试验分析,对试验结果进行多元线性拟合,获得鱼雷罐运输铁水温降的预测模型,并用该模型与现场生产数据进行比较,结果表明该模型的预测误差控制在8.1％以内.     

Comparative virulence between different strains of Listeria in zebrafish (Brachydanio rerio) and mice

Listeriosis is a disease found in most animal species but is relatively uncommon in fish. We studied the relationship between Listeria and zebrafish by injecting Brachydanio rerio intraperitoneally with different Listeria strains having pathological or food-stuff origins. We then compared these results with those obtained in Swiss mice. Experimental Listeriosis in Zebrafish differs greatly from that observed in mice. The 50% lethal dose (LD50) previously determined was much higher than that observed in mice. In fish, a good correlation exists between infection found in renal tissue, an important lympho?d organ and that present in whole fish (p < 0.001). Infection kinetics showed that, in contrast with mice, L. monocytogenes was unable to multiply in fish. Differential blood counts showed the development of an immune response in fish. The difference in the expression of Listeria virulence between Zebrafish and mice was also seen in their reactions to different wild strains inoculate i.p. Strains belonging the innocua, ivanovii, seeligeri and welshimeri were weakly or not virulent in mice but virulent in fish. Nevertheless, as in mice, differences in virulence existed between strains of L. monocytogenes belonging to serovars 4b, 1/2a, 1/2b and 1/2c.     

Do taste factors contribute to the mediation of ethanol intake? Ethanol and saccharin-quinine intake in three rat strains

Several recent studies have suggested that ethanol-preferring rodents may also have an affinity for sweet solutions (saccharin, sucrose) and, conversely, that saccharin preference may predict ethanol preference. The purpose of the present investigation was to determine whether intake of ethanol and saccharin-quinine (SQ) solutions would be related in three nonselected strains of rats who differ in their ethanol preference: Lewis, Wistar Kyoto, and Wistar. In the first phase of the experiment, all animals were presented with an ascending series of ethanol solutions (2 to 10%) in free choice with water, followed by a 10-day maintenance period of 10% ethanol with water. In the second phase, the same animals were presented with an ascending series of SQ solutions (saccharin: 0.4%, quinine: 0.001 to 0.04%) in free choice with water, followed by a 10-day maintenance period of 0.4% saccharin with 0.04% quinine and water. The results revealed an absence of a direct relationship between ethanol and SQ consumption. The ethanol-nonpreferring Lewis rats showed a greater preference for the SQ solutions than Wistar Kyoto rats, whereas the ethanol-preferring Wistar Kyoto strain consistently consumed significantly less SQ. Wistar rats showed relatively stable consumption levels for both solutions that fell between those of the other two strains. These results suggested that the relationship between ethanol and SQ preference in rats was not a direct one and did not support the findings in the literature of a simple overall positive relationship between sweet and ethanol preference. These data do, however, provide further evidence for taste factors in the mediation of self-selection of ethanol in rats.     

A molecular model for the interaction between vorozole and other non-steroidal inhibitors and human cytochrome P450 19 (P450 aromatase)

In a previous study (Vanden Bossche et al., Breast Cancer Res. Treat. 30 (1994) 43) the interaction between (+)-S-vorozole and the I-helix of cytochrome P450 19 (P450 aromatase) has been reported. In the present study we extended the "I-helix model" by incorporating the C-terminus of P450 aromatase. The crystal structures of P450 101 (P450 cam), 102 (P450 BM-3) and 108 (P450 terp) reveal that the C-terminus is structurally conserved and forms part of their respective substrate binding pocket. Furthermore, the present study is extended to the interaction between P450 aromatase and its natural substrate androstenedione and the non-steroidal inhibitors (-)-R-vorozole, (-)-S-fadrozole, R-liarozole and (-)-R-aminoglutethimide. It is found that (+)-S-vorozole, (-)-S-fadrozole and R-liarozole bind in a comparable way to P450 aromatase and interact with both the I-helix (Glu302 and Asp309) and C-terminus (Ser478 and His480). The weak activity of (-)-R-aminoglutethimide might be attributed to a lack of interaction with the C-terminus.     

Potential role of the peroxynitrate-poly(ADP-ribose) synthetase pathway in a rat model of severe hemorrhagic shock

PURPOSE: The purpose of this study was to assess the performance of sealants placed by senior dental students as part of a comprehensive dental care program that included periodic patient recall. METHODS: The dental records of 100 patients ranging in age from 6 to 13 years were selected for review to determine the treatments provided for first permanent molars over time. Criteria for inclusion were: 1) at least five documented recall examinations and 2) all four first permanent molars had to have been treated with an occlusal pit and fissure sealant. The data collected included: 1) the age of the patient at the time of initial sealant placement; 2) the subsequent treatment provided to the first permanent molars, including retreatment with sealant or restoration and the date the services were provided; 3) the last date of follow-up examination in the pediatric dental program. RESULTS: A total of 400 molars were followed for an average of 54 months. Fifty-two percent of all molars received no further treatment after initial placement of sealant. Approximately 35% received retreatment with sealant only. The total number of molars receiving sealant material only was 343 (86%). The total number of teeth that were judged to require restoration was 57 (14%). No relationship was noted between the patient's age at placement of the occlusal sealant and sealant performance. CONCLUSION: In a dental school clinic, occlusal sealants were effective at preventing caries in a comprehensive care program that included periodic recall.     

Phenotypic and DNA relatedness between nematode symbionts and clinical strains of the genus Photorhabdus (Enterobacteriaceae)

Bacterial strains isolated from wide ranges of nematode hosts and geographic sources and strains isolated from human clinical specimens were used to assess the taxonomic structure of the genus Photorhabdus. The following two methods were used: DNA relatedness and phenotypic characterization. Analysis of the DNA relatedness data revealed that all of the strains studied were congeneric and that the genus Photorhabdus is, on the basis of DNA relatedness data, more homogeneous than the other genus of nematode-symbiotic bacteria, the genus Xenorhabdus. In contrast to previous reports, only two DNA relatedness groups were identified in the genus Photorhabdus. These groups corresponded to the symbiotic strains and the clinical strains. There appeared to be some subgroups within the symbiotic strain group on the basis of the interactions of the strains with nematodes, which corresponded to some extent with the DNA relatedness data. However, there were significant ambiguities in the DNA relatedness data, and this group could not be subdivided on the basis of DNA relatedness data or phenotypic data. The distinct functional differences within and between the DNA relatedness groups of symbiotic Photorhabdus strains indicated that there are biologically significant sub-groups within the genus Photorhabdus that cannot be defined at this time. Further investigation of the taxonomy of Photorhabdus by using different approaches and a suitably wide range of strains is recommended. However, it is clear that the clinical strains form a recognizable subgroup within the genus even though no formal subtaxon can be defined at this time.     

Differences in serum interleukin-6 (IL-6) between healthy dextral and non-dextral subjects

Serum interleukin-6 (IL-6) was measured in picograms/ml pg/ml using an immunoassay (ELISA) in healthy individuals (n = 148), of whom 128 were classified as dextral and 20 as non-dextral, as per a laterality questionnaire. Only 3 (15%) non-dextral individuals had serum IL-6 levels above the lower limit of the assay sensitivity as compared to 59 (46%) of dextral individuals (P < 0.013). There were no significant correlations between previously determined mitogen stimulated interleukin-2 production and autoantibodies in a subset of the same individuals. While this data does not provide casual information, it adds to the evidence of the asymmetric regulation of immune functions by the cerebral hemispheres.     

Constitutive expression of heat shock protein 90 (HSP90) in neurons of the rat brain

Immunoblot analysis, immunocytochemistry and immuno-electron microscopy were employed to study the expression of HSP90 protein in the adult rat brain, using a specific polyclonal antiserum. Immunoblot analysis demonstrated equal levels of HSP90 in microdissected extracts from hippocampus, cortex, striatum and cerebellum. Immunocytochemistry and immuno-electron microscopy provided evidence that HSP90 is markedly expressed throughout all neuronal subpopulations of the CNS but not in non-neuronal cells except ependyma and choroid plexus. At the ultrastructural level, HSP90 immunoreactivity was predominantly found in perikarya but to a lesser extent also in dendrites and nuclei. The constitutive expression of HSP90 in widespread neuronal cell populations suggests a functional role in the physiological molecular program of CNS neurons.     

Differences in the structural characteristics of adult guinea pig and rat cardiomyocytes during their adaptation and maintenance in long-term cultures: confocal microscopy study

In this study, we used laser confocal scanning microscopy and immunofluorescent markers to describe the establishment of long-term (1-5 week) cultures of adult guinea pig cardiomyocytes and adult rat cardiomyocytes. Providing that the preparation of freshly isolated guinea pig cardiomyocytes consists mostly (> 80%) of rod-shaped, Ca(2+)-tolerant, and quiescent cells and these are plated under optimal conditions and density (10(5) cells/cm2), these myocytes have the following characteristics: (1) they remain elongated with regular ultrastructural characteristics and quiescent for 1 week; (2) within 10-14 days, they reestablish intercellular contacts and resume contractile activity, which becomes synchronous all through the confluent layer; (3) their myofibrillar striations remain regular all through the adaptation to culture conditions without any sign of dedifferentiation or redifferentiation; (4) they form adherence junctions (as indicated by their immunoreactivity to an antibody against N-cadherin) over the entire cellular surface; (5) they appear to retain their ability to express atrial natriuretic peptide (ANP), as indicated by immunoreactivity to anti-ANP antibody; (6) this activity seems to be directly related to the surface area of the myocytes in contact with the substrate. In contrast, rat cardiomyocytes cultured under very similar and optimal conditions exhibit very different characteristics during their adaptation in long-term cultures: (1) although 85-90% of freshly isolated cells are also rod-shaped and Ca2+ tolerant they exhibit slow spontaneous contractions; (2) they round up during the first few days, and during the first week they dedifferentiate, losing their regular striated appearance; (3) they spread, becoming irregularly shaped, and, unlike the guinea pig cardiomyocytes, they do not form confluent layers, no matter what the plating density is; (4) they atrophy at a very early stage in the cultures, so that by the fourth week, they have lost most of their myofibrils; (5) the initial rounding up is largely eliminated by exposure for 24 h to 1 microM ryanodine or 20 mM butanedione monoxime, compounds that suppress the spontaneous contractions. In conclusion, our studies demonstrate that adult guinea pig cardiomyocytes adapt and survive in long-term (1-5 week) cultures much better than do adult rat cardiomyocytes, indicating that the long-term cultures of adult guinea pig ventricular myocytes provide a valuable experimental model which opens new possibilities for studying the cellular and molecular regulation of myocardial function under the acute or chronic influence of various intrinsic and/or extrinsic factors.