Preclinical Assessment of Adjunctive tPA and DNase for Peritoneal Dialysis Associated Peritonitis

A major complication of peritoneal dialysis is the development of peritonitis, which is associated with reduced technique and patient survival. The inflammatory response elicited by infection results in a fibrin and debris-rich environment within the peritoneal cavity, which may reduce the effectiveness of antimicrobial agents and predispose to recurrence or relapse of infection. Strategies to enhance responses to antimicrobial agents therefore have the potential to improve patient outcomes. This study presents pre-clinical data describing the compatibility of tPA and DNase in combination with antimicrobial agents used for the treatment of PD peritonitis. tPA and DNase were stable in standard dialysate solution and in the presence of antimicrobial agents, and were safe when given intraperitoneally in a mouse model with no evidence of local or systemic toxicity. Adjunctive tPA and DNase may have a role in the management of patients presenting with PD peritonitis.     

Maternal protectiveness and response to the unfamiliar in vervet monkeys

Vervet monkeys (Cercopithecus aethiops sabaeus) show individual differences in approach-avoidance behavior when faced with an unfamiliar and potentially threatening situation. Prior research from our colony demonstrated that juveniles who had experienced high levels of early maternal protectiveness were more cautious in response to novelty, compared to juveniles who had had less protective mothers. The research reported here was designed to verify this result in a paradigm that experimentally varied maternal protectiveness through the introduction of new breeding adult males. Mothers responded to the presence of new males by increased maternal protectiveness toward infants born in the year following the introductions. Individual differences in response to the unfamiliar were later evaluated by measuring the latency to approach within 1 m of novel food containers placed into the home enclosure of four naturally composed social groups. Infants approached with the same latency and in the same order as their mothers. Juveniles approached sooner than, and independent of, their mother's current behavior, but their latency to approach could be predicted by the experimentally induced variation in maternal protectiveness they had experienced as infants. Immatures who had been born in New Male years, when maternal protectiveness was high, were more cautious and had significantly longer latencies to approach the novel stimulus compared to immatures who had been born in Resident Male years. © 1993 Wiley-Liss, Inc.     

Transforming growth factor-beta alters differentiation in cultures of avian neural crest-derived cells: effects on cell morphology, proliferation, fibronectin expression, and melanogenesis.

Neural crest cell differentiation is responsive to a variety of extrinsic signals that include extracellular matrix (ECM) molecules and growth factors. Transforming growth factor-beta (TGF-beta) has diverse, cell type-specific effects, many of which involve regulation of synthesis of ECM molecules and their cell surface receptors. We are studying both separate and potentially interrelated influences of ECM and growth factors on crest differentiation and report here that TGF-beta alters several aspects of crest cell behavior in vitro. Clusters of quail neural crest cells were cultured in the presence and absence of 400 pM TGF-beta 1 and examined at 1, 3, and 5 days. When examined at 5 days, there was a dramatic decrease in the number of melanocytes in treated cultures, regardless of the onset or duration of TGF-beta treatment. With continuous TGF-beta treatment, or with treatment only during crest cluster formation on explanted neural tubes, many cells increased in area, becoming extremely flat. These changes were evident beginning on Day 3. While quantitative analyses of video images documented the size increase, several aspects of motility were relatively unchanged. Synthesis of fibronectin (FN) by approximately 11% of cells on Day 3 and 31% of cells on Day 5 was demonstrated by immunocytochemistry and was associated with a sixfold increase in FN mRNA by Day 5. Experiments which correlated FN immunoreactivity with incorporation of bromodeoxyuridine suggested that the population of large, flat, FN-positive cells did not proliferate selectively and that there was a slower rate of proliferation in TGF-beta-treated cultures than in untreated cultures. The large FN-immunoreactive cells resemble cells derived from cephalic neural crest and raise interesting questions concerning potential roles for TGF-beta in regulating crest differentiation in vivo.     

Light enough to travel: migratory bats have smaller brains,but not larger hippocampi,than sedentary species

Migratory bird species have smaller brains than non-migratory species. The behavioural flexibility/migratory precursor hypothesis suggests that sedentary birds have larger brains to allow the behavioural flexibility required in a seasonally variable habitat. The energy trade-off hypothesis proposes that brains are heavy, energetically expensive and therefore, incompatible with migration. Here, we compared relative brain, neocortex and hippocampus volume between migratory and sedentary bats at the species-level and using phylogenetically independent contrasts. We found that migratory bats had relatively smaller brains and neocortices than sedentary species. Our results support the energy trade-off hypothesis because bats do not exhibit the same degree of flexibility in diet selection as sedentary birds. Our results also suggest that bat brain size differences are subtler than those found in birds, perhaps owing to bats'' shorter migration distances. Conversely, we found no difference in relative hippocampus volume between migratory and sedentary species, underscoring our limited understanding of the role of the hippocampus in bats.     

Functional neuroimaging in psychiatry.

Functional neuroimaging is one of the most powerful means available for investigating the pathophysiology of psychiatric disorders. In this review, we shall focus on the different ways that it can be employed to this end, describing the major findings in the field in the context of different methodological approaches. We will also discuss practical issues that are particular to studying psychiatric disorders and the potential contribution of functional neuroimaging to future psychiatric research.     

Molecular phylogeny of five species of Dremomys (Rodentia: Sciuridae), inferred from cytochrome b gene sequences

Analyses of the mitochondrial cytochrome b gene (1140 bp) showed that Dremomys lokriah , D. pernyi , D. pyrrhomerus , D. rufigenis and D. gularis all are separate species. Dremomys pyrrhomerus showed 8.5% sequence variation from D. rufigenis, and the level of estimated sequence divergence observed among D. gularis , D. lokriah and D. pernyi was > 11%. With Tamiops and Callosciurus as the outgroup taxa, in both maximum likelihood and Bayesian analyses, the five Dremomys species formed one strongly supported monophyletic group and D. pyrrhomerus is closely related to D. rufigenis . The derived divergence times and fossil record suggested that the present geographical distributions of Dremomys owe much to the uplifting of the Himalayas and the successive glacial and interglacial in the Pliocene–Pleistocene.