Dexamethasone alters TNF-alpha expression in retinopathy

TNF-alpha has been found in the retina. Hyperoxia and hypoxia regulate TNF-alpha expression. TNF-alpha is an important factor in inflammation and angiogenesis. Dexamethasone inhibits TNF-alpha production. Changes in TNF-alpha expression in the retina may play an important role in the development of oxygen-induced retinopathy. Oxygen-induced retinopathy was produced in C57BL6 mice by exposure to 75% oxygen at Postnatal Day 7 (P7) for 5 days and the mice recovered in room air until Day 17 (P17). Dexamethasone was administered at 0.5 mg/kg/day once daily subcutaneously during the 5 days of oxygen exposure. TNF-alpha expression was evaluated at Day 7 prior to oxygen exposure, at Day 12 (P12) immediately upon removal from oxygen, and at Day 17, the time of maximal vasoproliferation by RT-PCR. TNF-alpha is developmentally regulated in the retinae of C57BL6 mice. From P7 to P12, there is a 3-fold increase in TNF-alpha expression and from P7 to P17 there is a 2.7-fold increase. There was 2.7-fold suppression in expression immediately following oxygen exposure at P12. The expression was dramatically increased at P17, the time of maximal vasoproliferation. Dexamethasone inhibited the expression of TNF-alpha at P17 by 6.4-fold. At this dose, it also suppressed the baseline TNF-alpha expression in the mouse model. In summary, TNF-alpha is altered in the development of oxygen-induced retinopathy in the mouse. It increased markedly during the vasoproliferative phase and was suppressed by dexamethasone. Modulation of TNF-alpha expression may provide a potential site of action for future therapeutic targets.     

Engineered human dicentric chromosomes show centromere plasticity

The centromere is essential for the faithful distribution of a cell's genetic material to subsequent generations. Despite intense scrutiny, the precise genetic and epigenetic basis for centromere function is still unknown. Here, we have used engineered dicentric human chromosomes to investigate mammalian centromere structure and function. We describe three classes of dicentric chromosomes isolated in different cell lines: functionally monocentric chromosomes, in which one of the two genetically identical centromeres is consistently inactivated; functionally dicentric chromosomes, in which both centromeres are consistently active; and dicentric chromosomes heterogeneous with respect to centromere activity. A study of serial single cell clones from heterogeneous cell lines revealed that while centromere activity is usually clonal, the centromere state (i.e. functionally monocentric or dicentric) in some lines can switch within a growing population of cells. Because pulsed field gel analysis indicated that the DNA at the centromeres of these chromosomes did not change detectably, this switching of the centromere state is most likely due to epigenetic changes. Inactivation of one of the two active centromeres in a functionally dicentric chromosome was observed in a percentage of cells after treatment with Trichostatin A, an inhibitor of histone deacetylation. This study provides evidence that the activity of human centromeres, while largely stable, can be subject to dynamic change, most likely due to epigenetic modification.     

The kinase haspin is required for mitotic histone H3 Thr 3 phosphorylation and normal metaphase chromosome alignment

Post-translational modifications of conserved N-terminal tail residues in histones regulate many aspects of chromosome activity. Thr 3 of histone H3 is highly conserved, but the significance of its phosphorylation is unclear, and the identity of the corresponding kinase unknown. Immunostaining with phospho-specific antibodies in mammalian cells reveals mitotic phosphorylation of H3 Thr 3 in prophase and its dephosphorylation during anaphase. Furthermore we find that haspin, a member of a distinctive group of protein kinases present in diverse eukaryotes, phosphorylates H3 at Thr 3 in vitro. Importantly, depletion of haspin by RNA interference reveals that this kinase is required for H3 Thr 3 phosphorylation in mitotic cells. In addition to its chromosomal association, haspin is found at the centrosomes and spindle during mitosis. Haspin RNA interference causes misalignment of metaphase chromosomes, and overexpression delays progression through early mitosis. This work reveals a new kinase involved in composing the histone code and adds haspin to the select group of kinases that integrate regulation of chromosome and spindle function during mitosis and meiosis.     

Determination of antigenic specificity and relationship among Haemophilus pleuropneumoniae serotypes by an indirect hemagglutination test.

Serological properties of antigens extracted from strains of Haemophilus pleuropneumoniae belonging to seven different serotypes were investigated. Antisera were prepared in rabbits against Formalin-treated whole cell suspensions as well as autoclaved cell suspensions. Saline and heat extracts and their alcohol precipitate antigens of H. pleuropneumoniae were used in the indirect hemagglutination test. All the antigens used were easily adsorbed directly onto sheep erythrocytes. Saline extract antigen showed maximum type specificity. Heating of the whole cell suspension revealed the cross-reactive minor antigenic determinants. Thus, the heat extract preparations had both type-specific and species-specific antigens. It is suggested that the indirect hemagglutination test may be useful for both serotyping and serodiagnosis of H. pleuropneumoniae infections in pigs.     

Haplotype analysis in multiple crosses to identify a QTL gene

Identifying quantitative trait locus (QTL) genes is a challenging task. Herein, we report using a two-step process to identify Apoa2 as the gene underlying Hdlq5, a QTL for plasma high-density lipoprotein cholesterol (HDL) levels on mouse chromosome 1. First, we performed a sequence analysis of the Apoa2 coding region in 46 genetically diverse mouse strains and found five different APOA2 protein variants, which we named APOA2a to APOA2e. Second, we conducted a haplotype analysis of the strains in 21 crosses that have so far detected HDL QTLs; we found that Hdlq5 was detected only in the nine crosses where one parent had the APOA2b protein variant characterized by an Ala61-to-Val61 substitution. We then found that strains with the APOA2b variant had significantly higher (P < or = 0.002) plasma HDL levels than those with either the APOA2a or the APOA2c variant. These findings support Apoa2 as the underlying Hdlq5 gene and suggest the Apoa2 polymorphisms responsible for the Hdlq5 phenotype. Therefore, haplotype analysis in multiple crosses can be used to support a candidate QTL gene.     

Occurrence of neural tube defects among first-, second-, and third-degree relatives of probands: Results of a United States study

Data on the occurrence of neural tube defects in first-, second-, and third-degree relatives of probands were collected in a United States study. The proportions of affected individuals were 3.2%, 0.5%, and 0.17% respectively. These findings are compared to those from other recent North American studies, and differences are discussed. It is pointed out that accurate recurrence risk figures may not be available, and that caution should be used when counseling families with relatives who are affected with NTD.     

RNAs 4A and 5 are present in tomato aspermy virusand both subgroups of cucumber mosaic virus

Summary.  Primer extension analysis was used to determine the presence of RNAs 4A and 5 in tomato aspermy virus (TAV) and both subgroups of cucumber mosaic virus (CMV). RNAs 4A and 5 were detected in TAV and all CMV strains (representative of both subgroups) that were analysed, except for one subgroup I CMV strain which lacked detectable RNA 5. In subgroup II CMV strains the RNA 5 population was found to consist of two sequence variants. Comparison of the RNA 5 sequences from TAV and CMV indicated that TAV and subgroup II CMV RNA 5 share a much greater degree of sequence similarity than either has with subgroup I RNA 5. RNA 4A and the encoded 2b protein appear to be unique to the cucumovirus genus of the tripartite viruses, which share an otherwise common genome structure, and may have played a role in the evolutionary origin of this genus. Accepted November 15, 1996 Received May 27, 1996     

Large B-cell lymphoma of thyroid. Two cases with a marginal zone distribution of the neoplastic cells

We report 2 cases of B-cell lymphoma of the thyroid in which although a marginal zone distribution of the neoplastic cells was present, the cytologic features of the cells indicated large cell lymphoma. One of the cases showed an accumulation of crystalline inclusions within the cytoplasm of the neoplastic cells. Many of these inclusion-bearing cells showed plasmacytoid features. By immunohistochemical studies performed on formalin-fixed paraffin-embedded tissue, both of the cases showed a B-cell phenotype as indicated by CD20 expression, and 1 showed kappa light chain restriction. In both cases, Ki-67 staining corroborated the impression of an aggressive neoplasm with staining of 50% and 90% of the tumor cells. Both patients received cyclophosphamide, doxorubicin, vincristine, and prednisone with radiation therapy, and both are without evidence of disease after 17 and 18 months of follow-up. It is important to recognize this pattern of large B-cell lymphoma of the thyroid gland. While the indolent course typical of most low-grade extranodal marginal zone lymphomas is not likely in these cases, the outcome may be favorable if patients are treated aggressively with therapy for large cell lymphoma.     

Immunoblot analysis of anti-Ureaplasma urealyticum antibody in pregnant women and newborn infants.

The purpose of the present study was to determine the frequency in which antibody reactive to Ureaplasma urealyticum could be detected in a population of pregnant women and newborn infants. Serum samples from a prospective cohort of 80 healthy, U. urealyticum culture-positive and culture-negative pregnant women and a retrospective cohort of 522 infants born at between 25 and 42 weeks of gestation were studied by immunoblot analysis. Cultures of specimens from the lower genital tract were positive for U. urealyticum for 83% of the pregnant women, and serum immunoglobulin G (IgG) antibody which reacted to U. urealyticum was detectable in 93% of the pregnant women. Samples from five women (8%) had increases in the number of anti-U. urealyticum IgG bands over the course of the pregnancy. Samples from four of these five women had corresponding increases in the number of antibody bands present in IgA immunoblots. Six of the 522 samples from newborns or cord blood (1.1%) were positive for anti-U. urealyticum IgA; 5 of these 6 samples were also positive for IgM. The six anti-U. urealyticum IgA-positive infants were distributed as follows; 3 of 67 (4.5%) infants were delivered at 25 to 30 weeks of gestation, 3 of 176 (1.7%) infants were delivered at 31 to 34 weeks of gestation, and 0 of 279 infants were delivered at > or = 35 weeks of gestation. An antibody response to U. urealyticum can be detected in pregnant women and preterm infants and may serve as a marker of infection.