Stellate Cells in the Medial Entorhinal Cortex Are Required for Spatial Learning

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Cellular survival in rat vein-to-artery grafts

Microsurgical models of vein-to-artery graft surgery have been developed in rats as a means of assessing vein graft adaptation and neo-intimal hyperplasia. Neo-intimal hyperplasia in these grafts is often attributed, at least in part, to an adaptive response by venous smooth muscle cells to the increased intraluminal pressure of the arterial pressure. However, considerable evidence suggests complete or near-complete cellular replacement in these grafts. A series of experiments were undertaken in which male vein or artery grafts were placed into either allogeneic female nude rat hosts or into syngeneic WKy female hosts as a means of determining donor cell survival. Grafts were removed at postsurgery week 2 or week 6 and the fate of the donor male cells assessed by PCR amplification of the testis-determining gene Sry. The Sry gene was undetectable in 2-week male to female vein grafts. When left for 6 weeks, donor cells were detectable in vein grafts only after multiple 50-cycle PCR analyses. Minimal donor cell survival was not due to an allograft response, as donor male cells were readily detectable in WKy male to female nude rat artery-to-artery grafts. These data were not nude rat specific, as poor donor cell survival was also evidenced in syngeneic male to female vein-to-artery grafts. In conclusion, we demonstrate only marginal survival of donor cells in rat vein-to-artery grafts. Neo-intimal hyperplasia in these grafts was not a consequence of donor venous smooth muscle cell proliferation.     

The first definitive Middle Jurassic atoposaurid (Crocodylomorpha,Neosuchia), and a discussion on the genus Theriosuchus

Atoposaurids were a clade of semiaquatic crocodyliforms known from the Late Jurassic to the latest Cretaceous. Tentative remains from Europe, Morocco, and Madagascar may extend their range into the Middle Jurassic. Here we report the first unambiguous Middle Jurassic (late Bajocian–Bathonian) atoposaurid: an anterior dentary from the Isle of Skye, Scotland, UK. A comprehensive review of atoposaurid specimens demonstrates that this dentary can be referred to Theriosuchus based on several derived characters, and differs from the five previously recognized species within this genus. Despite several diagnostic features, we conservatively refer it to Theriosuchus sp., pending the discovery of more complete material. As the oldest known definitively diagnostic atoposaurid, this discovery indicates that the oldest members of this group were small‐bodied, had heterodont dentition, and were most likely widespread components of European faunas. Our review of mandibular and dental features in atoposaurids not only allows us to present a revised diagnosis of Theriosuchus, but also reveals a great amount of variability within this genus, and indicates that there are currently five valid species that can be differentiated by unique combinations of dental characteristics. This variability can be included in future broad‐scale cladistics analyses of atoposaurids and closely related crocodyliforms, which promise to help untangle the complicated taxonomy and evolutionary history of Atoposauridae. © 2015 The Authors. Zoological Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of The Linnean Society of London     

Spawning and rearing behavior of bull trout in a headwater lake ecosystem

Environmental Biology of Fishes - Numerous life histories have been documented for bull trout Salvelinus confluentus. Lacustrine-adfluvial bull trout populations that occupy small, headwater lake...     

Effect of myrrh and thyme on Trichinella spiralis enteral and parenteral phases with inducible nitric oxide expression in mice

Trichinellosis is a serious disease with no satisfactory treatment. We aimed to assess the effect of myrrh (Commiphora molmol) and, for the first time, thyme (Thymus vulgaris L.) against enteral and encysted (parenteral) phases of Trichinella spiralis in mice compared with albendazole, and detect their effect on inducible nitric oxide synthase (iNOS) expression. Oral administration of 500 mg/kg of myrrh and thyme led to adult reduction (90.9%, 79.4%), while 1,000 mg/kg led to larvae reduction (79.6%, 71.3%), respectively. Administration of 50 mg/kg of albendazole resulted in adult and larvae reduction (94.2%, 90.9%). Positive immunostaining of inflammatory cells infiltrating intestinal mucosa and submucosa of all treated groups was detected. Myrrh-treated mice showed the highest iNOS expression followed by albendazole, then thyme. On the other hand, both myrrh and thyme-treated groups showed stronger iNOS expression of inflammatory cells infiltrating and surrounding encapsulated T. spiralis larvae than albendazole treated group. In conclusion, myrrh and thyme extracts are highly effective against both phases of T. spiralis and showed strong iNOS expressions, especially myrrh which could be a promising alternative drug. This experiment provides a basis for further exploration of this plant by isolation and retesting the active principles of both extracts against different stages of T. spiralis.     

To strike or not to strike? House-staff attitudes and behaviors during a hospital work action.

Work actions by house staff are an infrequent response to sometimes difficult working conditions, but they can have a notable effect on institutional cohesiveness and represent a challenge to traditional notions of medical ethics. To determine the extent of participation in a hospital-wide doctors'' strike and factors associated with participation, we surveyed 432 house officers at a university-affiliated public hospital where a contract dispute had recently led to a 4-day work action. Of 257 respondents, 69% approved of the strike and 50% participated in it. Both strikers and nonstrikers agreed that quality of care and specific contract issues were important precipitants of the event. By logistic regression, factors independently associated with strike participation (P less than .05) included being unmarried, training in internal medicine or psychiatry, being in earlier stages of training, being assigned to an outpatient service at the time of the strike, holding a favorable view of physician activism, and perceiving nurses, faculty, peers, and the public to have favored the strike. These associations may provide a basis for understanding the individual and social determinants of house-staff strike activity.     

A protocol for efficient transformation and regeneration of Carica papaya L.

Summary A reproducible and effective biolistic method for transforming papaya (Carica papaya L.) was developed with a transformation-regeneration system that targeted a thin layer of embryogenic tissue. The key factors in this protocol included: 1) spreading of young somatic embryo tissue that arose directly from excised immature zygotic embryos, followed by another spreading of the actively growing embryogenic tissue 3 d before biolistic transformation; 2) removal of kanamycin selection from all subsequent steps after kanamycin-resistant clusters were first isolated from induction media containing kanamycin; 3) transfer of embryos with finger-like extensions to maturation medium; and 4) transferring explants from germination to the root development medium only after the explants had elongating root initials, had at least two green true leaves, and were about 0.5 to 1.0 cm tall. A total of 83 transgenic papaya lines expressing the nontranslatable coat protein gene of papaya ringspot virus (PRSV) were obtained from somatic embryo clusters that originated from 63 immature zygotic embryos. The transformation efficiency was very high: 100% of the bombarded plates produced transgenic plants. This also represents an average of 55 transgenic lines per gram fresh weight, or 1.3 transgenic lines per embryo cluster that was spread. We validated this procedure in our laboratory by visiting researchers who did four independent projects to transform seven papaya cultivars with coat protein gene constructs of PRSV strains from four different countries. The method is described in detail and should be useful for the routine transformation and regeneration of papaya. Based in part on a presentation at the 1997 SIVB Congress on In Vitro Biology held in Washington, DC, June 14–18, 1997.     

The effects of non-steroidal inhibitors of phospholipase A2 on leukotriene and histamine release from human and guinea-pig lung

The effects of chloroquine and mepacrine were determined on the release of slow reacting substances (leukotrienes) from lung fragments in vitro. These drugs have been shown in a variety of tissues to inhibit phospholipase A2, and thus to reduce the availability of arachidonate, which is a substrate for leukotriene biosynthesis. Leukotriene and histamine release from unsensitized human lung was stimulated by calcium ionophore A23187, and from actively sensitized guinea-pig lung, by ovalbumin. Chloroquine (10 microM and 100 microM) significantly inhibited leukotriene release in lung from both species, and at 100 microM also inhibited histamine release. Mepacrine (10 microM) inhibited leukotriene release in human lung and at 100 microM in guinea-pig lung. The effects of chloroquine (100 microM) on leukotriene release were counteracted by the presence of arachidonic acid (10 microM), which suggests that chloroquine had impaired the availability of arachidonate. It seems probable that chloroquine and mepacrine inhibit leukotriene release by inhibition of phospholipase A2 in lung.     

DNA evolutionary rates in nine-primaried passerine birds

Differences in single-copy nuclear-DNA sequences among 13 species of passerine birds were measured using DNA-DNA hybridization. A matrix of pairwise dissimilarity values (delta mode distances) was constructed from analysis of fitted thermal dissociation curves. A least-squares method of phylogenetic estimation was used to construct two topologies from the distance matrix, one constraining branch lengths of sister taxa to be equal and the other permitting such lengths to vary. These topologies were identical in the pattern of branching of taxa, and the difference in their sums of squares was not statistically significant, suggesting that rates of DNA evolution in sister groups of nine- primaried oscines are equal. A nonparametric test for nonrandom variation in distances of sister groups to outgroup taxa revealed no statistically significant deviation from random variation that would be expected as a result of measurement error. However, the level of measurement error was such that rates of DNA evolution in sister taxa could vary by as much as 10% without being detected with the statistical methods used here.      

Woodchuck hepatitis virus is a more efficient oncogenic agent than ground squirrel hepatitis virus in a common host.

Chronic infection with hepatitis B viruses (hepadnaviruses) is a major cause of hepatocellular carcinoma (HCC), but the incubation time varies from 1 to 2 years to several decades in different host species infected with indigenous viruses. To discern the influence of viral and host factors on the kinetics of induction of HCC, we exploited the recent observation that ground squirrel hepatitis virus (GSHV) is infectious in woodchucks (C. Seeger, P. L. Marion, D. Ganem, and H. E. Varmus, J. Virol. 61:3241-3247, 1987) to compare the pathogenic potential of GSHV and woodchuck hepatitis virus (WHV) in chronically infected woodchucks. Chronic GSHV infection in woodchucks produces mild to moderate portal hepatitis, similar to that observed in woodchucks chronically infected with WHV. However, HCC developed in GSHV carriers about 18 months later than in WHV carriers. Thus, although both viruses are oncogenic in woodchucks, GSHV and WHV differ in oncogenic determinants that can affect the kinetics of appearance of HCC in chronically infected animals.