Development and validation of a multivariate predictor of mortality in very low birth weight

Accurate prognosis is critical to the design of all prospective research aimed at improving survival. Predictions based on birth weight, gestational age, or any other single variable, fail to take into account the potentially important contribution of other factors. In order to develop a practical and accurate multivariate model, we studied all singleton pregnancies resulting in viable liveborn infants who weighed less than or equal to 1500 g at birth during 1984 and 1985 at the New York Hospital-Cornell Medical Center. When gestational age, birth weight, and/or crown-heel length were considered, no maternal characteristics were significant predictors of mortality. The model with the maximal predictive accuracy (84.5%) used birth weight and 5-minute Apgar score to calculate a probability of mortality. This prognostic model was then validated in a separate cohort of singletons born in 1986. We conclude that clinical trials should require stratification before randomization, using the calculated probability of mortality, rather than birth weight or gestational age alone. Given the ability of models, such as the one presented here, to generate reasonable estimates of mortality, this information might also be used in the clinical setting to assist parents and physicians in individualized decision-making processes for a given infant.     

Chromosome triplication found across the tribe Brassiceae

We have used an approximately 8.7-Mb BAC contig of Arabidopsis thaliana Chromosome 4 to trace homeologous chromosome regions in 21 species of the family Brassicaceae. Homeologs of this segment could be identified in all tested species. Painting of pachytene chromosomes of Calepina, Conringia, and Sisymbrium species (2n = 14, 16), traditionally placed in tribe Brassiceae, showed one homeologous copy of the Arabidopsis contig, while the remaining taxa of the tribe (2n = 14-30) revealed three, and three Brassica species (2n = 34, 36, and 38) and Erucastrum gallicum (2n = 30) had six copies corresponding to the 8.7-Mb segment. The multiple homeologous copies corresponded structurally to the Arabidopsis segment or were rearranged by inversions and translocations within the diploidized genomes. These chromosome rearrangements accompanied by chromosome fusions/fissions led to the present-day chromosome number variation within the Brassiceae. Phylogenetic relationships based on the chloroplast 5'-trnL (UAA)-trnF(GAA) region and estimated divergence times based on sequence data of the chalcone synthase gene are congruent with comparative painting data and place Calepina, Conringia, and Sisymbrium outside the clade of Brassiceae species with triplicated genomes. Most likely, species containing three or six copy pairs descended from a common hexaploid ancestor with basic genomes similar to that of Arabidopsis. The presumed hexaploidization event occurred after the Arabidopsis-Brassiceae split, between 7.9 and 14.6 Mya.     

Susceptibility of corneal allografts and xenografts to antibody-mediated rejection

The effects of passive transfer of antisera containing cytotoxic antibodies to allo- and xenoantigens on survival of corneal allografts and xenografts were evaluated in experimental models. Corneas from allogeneic B10 or xenogeneic rat Lewis donors were grafted orthotopically into BALB/c mice. Recipient mice were treated with donor-specific antisera administered at the period of grafting or at 2 weeks after transplantation. Rejection was determined by the severity of corneal opacity using a standard scoring system. Treatment of graft recipients with donor-specific antisera accelerated the onset of graft rejection and significantly shortened survival times of both corneal allografts and xenografts. Corneal xenografts, which had been accepted after treatment with anti-CD4 monoclonal antibody, were acutely rejected by the passive transfer of antiserum against xenoantigens. The results suggest that corneal grafts are vulnerable to antibody-dependent immunity and that cytotoxic antibodies against graft donor antigens can mediate rejection of both corneal allografts and xenografts.     

Lesion of posterior parietal cortex in rats does not disrupt place avoidance based on either distal or proximal orienting cues

A current topic in neurobiology is the study of the role of various brain structures in processing of spatial information. The present study was aimed at elucidating the role of the rat posterior parietal cortex in performing a place avoidance task. Two variants of the task were used: an arena frame task, in which animals were trained to avoid a sector defined by local cues bound to the surface of a rotating arena, and the room frame task, in which the shock sector was defined with respect to distal room landmarks. The results showed that both control and lesioned rats were able to efficiently solve both tasks, while locomotion was not altered. These results suggest that the posterior parietal cortex is not crucial for the processing of either proximal or distal cues in place avoidance.     

Aryl hydrocarbon receptor-activating polychlorinated biphenyls and their hydroxylated metabolites induce cell proliferation in contact-inhibited rat liver epithelial cells.

Polychlorinated biphenyls (PCBs) exhibit tumor-promoting effects in experimental animals. We investigated effects of six model PCB congeners and hydroxylated PCB metabolites on proliferation of contact-inhibited rat liver epithelial WB-F344 cells. The 'dioxin-like' PCB congeners, PCB 126, PCB 105, and 4'-OH-PCB 79, a metabolite of the planar PCB 77 congener, induced cell proliferation in a concentration-dependent manner. In contrast, the 'non-dioxin-like' compounds that are not aryl hydrocarbon receptor (AhR) agonists, PCB 47, PCB 153, and 4-OH-PCB 187, an abundant noncoplanar PCB metabolite, had no effect on cell proliferation at concentrations up to 10 muM. The concentrations of dioxin-like PCBs leading to cell proliferation corresponded with the levels inducing the expression of cytochrome P450 1A1 mRNA, suggesting that the release from contact inhibition was associated with AhR activation. The effects of PCB 126 and PCB 153 on expression of proteins controlling G0/G1-S-phase transition and S-phase progression were compared. Only PCB 126 was found to upregulate cyclin A and D2 protein levels, and to increase both total cyclin-dependent kinase 2 (cdk2) and cyclin A/cdk2 complex activities. Despite the observed upregulation of cyclin D2, no increase in cdk4 activity was observed. The expression of cdk inhibitor p27Kip1 was not affected by either PCB 126 or PCB 153. These results suggest that dioxin-like PCBs can induce cell proliferation of contact-inhibited rat liver epithelial cells by increasing cyclin A protein levels, a process that then leads to upregulation of cyclin A/cdk2 activity and initiation of DNA replication. This mechanism could be involved in tumor-promoting effects of dioxin-like PCBs.     

Study of Internal Stress in Conductive and Dielectric Thick Films

This paper is focused on the study of internal stress in thick films used in hybrid microelectronics. Internal stress in thick films arises after firing and during cooling due to the differing coefficients of thermal expansion in fired film and ceramic substrates. Different thermal expansions cause deflection of the substrate and in extreme cases, the deflection can lead to damage of the substrate. Two silver pastes and two dielectric pastes, as well as their combinations, were used for the experiments, and the internal stress in the thick films was investigated using the cantilever method. Further experiments were also focused on internal stress changes during the experiment and on the influence of heat treatment (annealing) on internal stress. The results were correlated with the morphology of the fired thick films. The internal stress in the thick films was in the range of 8 to 21 MPa for metallic films and in the range from 12 to 16 MPa for dielectric films. It was verified that the cantilever method can be successfully used for the evaluation of internal stress in thick films. It was also found that the values of deflection and internal stress are not stable after firing, and they can change over time, mainly for metallic thick films.     

Neuroendocrine Tumor Arising within Mature Cystic Teratoma of the Pancreas: Literature Review and Case Report

Cystic teratomas are germ cell tumors most commonly found in the ovaries and testes. The pancreas, however, is very rare as a site of occurrence. Moreover, only two cases of cystic teratoma with concomitant neuroendocrine tumor have been reported to date. We report the case of a 33-year-old female who presented with abdominal pain. Computed tomography and magnetic resonance imaging of the upper abdomen revealed an 85 mm cystic tumor in the head of the pancreas. Cystic teratoma and mucinous cystadenoma were suggested as differential diagnoses. Cytopathologic analysis of endoscopic ultrasound-guided fine needle aspiration was consistent with mucinous cystadenoma. Therefore, the patient underwent surgical resection. Histologic analysis revealed a mature cystic teratoma of the pancreas with a concomitant neuroendocrine tumor. The patient is in great condition at 8 months follow-up. Cystic teratoma of the pancreas with a concomitant neuroendocrine tumor is an extremely rare condition. Surgical resection remains the mainstay of treatment as it provides a definitive diagnosis and no recurrences have been reported to date.