Developmental regulation of telomerase activity in human fetal tissues during gestation

Telomerase is a ribonucleoprotein that adds hexanucleotide repeats (telomeres) to the ends of linear chromosomes, compensating for the loss of telomeric DNA which occurs with DNA replication. In humans, telomerase has been previously detected in germ-line tissues, blastocysts, 16-20 week old fetal tissue, and most cancers, but not in mature sperm or ova, or in most normal somatic tissues. It has been hypothesized that telomerase is suppressed during somatic development and reactivated in malignancy. To test the hypothesis that telomerase is suppressed during somatic development, human fetal tissues of 8-21 weeks gestational age were assayed for telomerase activity. All tissues expressed telomerase at the earliest ages examined. Lung, liver, spleen, and testis maintained telomerase activity through the latest age assayed, namely 21 weeks. Brain and kidney telomerase activity was present up to the 16th week and was undetectable thereafter. Heart tissue did not display activity beyond the 12th week. Lysates of heart, brain, and kidney without telomerase activity did not inhibit the activity of known telomerase-positive cells, suggesting that suppression of telomerase activity during gestational development is due to a lack of active telomerase rather than to the presence of an inhibitor. These findings demonstrate tissue-specific and developmental regulation of telomerase in the human fetus, suggesting an important role for this ribonucleoprotein in human fetal tissue differentiation and development.      

Prevention and primary care treatment of stings from imported fire ants.

Stings from imported fire ants constitute a problem encountered more and more frequently in practice settings across the Southern United States. Envenomation (impregnation of venom) in children is especially common. Current medical regimens for the treatment of other stinging insects are of little value in preventing local cutaneous reactions to fire-ant stings. The pathogenesis of reactions from imported-fire-ant stings is discussed, and suggestions for prevention, treatment and patient education are provided.     

Fungal sinusitis: diagnosis with CT and MR imaging

Of 293 patients who underwent computed tomography (CT), surgery, and pathologic examination for chronic sinusitis, 25 had a diagnosis of fungal sinusitis at pathologic examination. Of these, 22 had foci of increased attenuation at CT (in four patients the mean representative CT number [Hounsfied unit] was 122.2 HU [SD, 8.2 HU]), and three did not. Of the 22, 19 patients (76%) met the CT criterion of this study (there was a 12% false-positive and a 12% false-negative diagnostic rate). Six of the 19 patients and one additional patient underwent magnetic resonance (MR) imaging, and all demonstrated remarkably hypointense signal characteristics on T2-weighted images. The findings at MR imaging therefore appear more characteristic of fungal sinusitis than the findings at CT. Furnace atomic absorption spectrometry showed increased concentrations of iron and manganese in mycetoma compared with their concentrations in bacterially infected mucus. This finding and the presence of calcium in the fungal concretion may explain the hypointense T2-weighted signal on MR images.     

Anti-idiotypic antibodies specific for a pathologic anti-Pr2 cold agglutinin

The heterogeneity of human red cell (RBC) autoantibodies may be assessed by using anti-idiotypic antibodies. In this study, mouse monoclonal anti-idiotypic antibodies were produced against a pathologic RBC autoantibody with anti-Pr2 specificity. Epstein-Barr virus-transformed B-cell clones were established from a patient who had splenic lymphoma and associated immune hemolysis due to an anti-Pr2 cold autoantibody. Two of the eight clones producing this autoantibody were used to immunize mice for the establishment of hybridomas, and four monoclonal anti-idiotypic antibodies were isolated (2 IgG1 kappa and 2 IgM kappa). By the use of these anti-idiotypic antibodies, strong crossreactivity was seen on enzyme-linked immunosorbent assay with other anti-Pr2-producing clones from the same patient, but no cross-reactivity was seen with RBC autoantibodies from other individuals having anti-Pr or different specificities. Each of the anti-idiotypic antibodies inhibited hemagglutination (HA) by the patient's anti-Pr2 but failed to inhibit HA by antisera of a different RBC specificity. Cross-competition experiments indicated that all of the anti-idiotypic antibodies may recognize the same or a closely related idiotope on the anti-Pr2 autoantibody. These studies suggested that the four anti-idiotypic antibodies are directed against the same (or closely related) idiotypic determinant(s), unique to this patient's anti-Pr2 and located at or near the antigen-binding site. These anti-idiotypic antibodies may be useful tools for the study of this autoimmune response or for the development of immune therapeutic agents.(ABSTRACT TRUNCATED AT 250 WORDS)     

Peripheral blood stem cell collection and use in Hodgkin''s disease. Comparison with marrow in autologous transplantation

Hematopoietic progenitor cells can be collected from blood by cytapheresis; the clinical use of these cells may offer such advantages over marrow as the avoidance of general anesthesia, collection on an outpatient basis, and use when marrow is involved with malignancy. Since Hodgkin's disease rarely spreads hematogenously, postchemotherapy marrow transplantation with autologous peripheral blood stem cells (PBSCs) was compared to that with marrow transplantation in patients with this disorder. Seven patients were treated with PBSCs and 19 with marrow. Five to nine collections of PBSC were performed per patient. There was a rebound increase in circulating committed progenitors when PBSC were collected during the marrow rebound after cyclic chemotherapy. After intensification and cellular rescue, quicker recovery of circulating white cells (p less than 0.05) and a shorter hospital stay (not significant) were seen in the PBSC patients than in those treated with autologous marrow. There was no difference in the duration of red cell or platelet transfusion required after transplant. Of six patients whose marrows were previously involved by Hodgkin's, recurrent or progressive disease has occurred in five. PBSC may be a viable alternative to marrow in selected patients.     

Identification and characterization of human genes encoding Hprp3p and Hprp4p, interacting components of the spliceosome

Nuclear RNA splicing occurs in an RNA-protein complex, termed the spliceosome. U4/U6 snRNP is one of four essential small nuclear ribonucleoprotein (snRNP) particles (U1, U2, U5 and U4/U6) present in the spliceosome. U4/U6 snRNP contains two snRNAs (U4 and U6) and a number of proteins. We report here the identification and characterization of two human genes encoding U4/U6-associated splicing factors, Hprp3p and Hprp4p, respectively. Hprp3p is a 77 kDa protein, which is homologous to the Saccharomyces cerevisiae splicing factor Prp3p. Amino acid sequence analysis revealed two putative homologues in Caenorhabditis elegans and Schizosaccharomyces pombe. Polyclonal antibodies against Hprp3p were generated with His-tagged Hprp3p over- produced in Escherichia coli . This splicing factor can co- immunoprecipitate with U4, U6 and U5 snRNAs, suggesting that it is present in the U4/U6.U5 tri-snRNP. Hprp4p is a 58 kDa protein homologous to yeast splicing factor Prp4p. Like yeast Prp4p, the human homologue contains repeats homologous to the beta-subunit of G- proteins. These repeats are called WD repeats because there is a highly conserved dipeptide of tryptophan and aspartic acid present at the end of each repeat. The primary amino acid sequence homology between human Hprp4p and yeast Prp4p led to the discovery of two additional WD repeats in yeast Prp4p. Structural homology between these human and yeast splicing factors and the beta-subunit of G-proteins has been identified by sequence-similarity comparison and analysis of the protein folding by threading. Structural models of Hprp4p and Prp4p with a seven-blade beta-propeller topology have been generated based on the structure of beta-transducin. Hprp3p and Hprp4p have been shown to interact with each other and the first 100 amino acids of Hprp3p are not essential for this interaction. These experiments suggest that both Hprp3p and Hprp4p are components of human spliceosomes.      

Cloning, mapping and RNA analysis of the human methionine synthase gene

Elevated levels of plasma homocysteine is a risk factor in both birth defects and vascular disease. Methionine synthase (MS) is a cobalamin dependent enzyme which catalyzes methylation of homocysteine to methionine. Impaired MS activity is expected to lead to increased levels of plasma homocysteine. In addition, defects in this gene may underlie the methionine-dependence observed in a number of human tumor cell lines. We describe here the isolation and characterization of the human MS cDNA. It contains an open reading frame of 3798 nucleotides encoding a protein of 1265 amino acids with a predicted molecular mass of 140 kDa. The amino acid sequence of the human MS is 55% identical with that of the Escherichia coli enzyme (METH) and 64% identical with the predicted Caenorhabditis elegans enzyme. Seven peptide sequences derived from purified porcine MS have substantial similarity to the human protein. Northern analysis indicates that the MS RNA is present in a wide variety of tissues. We have mapped the human gene to chromosomal location 1q43, a region found monosomic in individuals with deletion 1q syndrome. The isolation of the MS cDNA will now allow the direct determination of whether mutations in this gene contribute to folate-related neural tube defects, cardiovascular diseases, and birth defects.      

Medical management of interstitial ectopic pregnancy: a case report and literature review

Recent reports describe successful treatment of interstitial ectopic pregnancies using methotrexate. While the number of reported cases is increasing, no consensus exists regarding the management of this complication of pregnancy. We present the successful use of combined systemic and direct intrasac injection of methotrexate for an interstitial pregnancy with the highest yet reported initial beta-human chorionic gonadotrophin concentration (102,000 mIU/ml). We also describe the use of Doppler ultrasound for monitoring treatment progression. Through a review of the current literature, we propose to facilitate management decisions and increase outcome success by summarizing previously reported treatment regimens and by describing enhanced parameters for patient selection and monitoring.      

Is oxidative stress involved in the aetiology of pre-eclampsia?

Pre-eclampsia is one of the major indications for elective premature delivery. Several lines of evidence suggest that pre-eclampsia is associated with a state of oxidative stress, offering hope of prevention by antioxidant supplementation. It was recently shown by the present authors that supplementation with vitamin C and E from early in pregnancy leads to a reduction in the incidence of the disease in "high-risk" women.     

Critical care resources in the Solomon Islands: a cross-sectional survey

Background  

There are minimal data available on critical care case-mix, care processes and outcomes in lower and middle income countries (LMICs). The objectives of this paper were to gather data in the Solomon Islands in order to gain a better understanding of common presentations of critical illness, available hospital resources, and what resources would be helpful in improving the care of these patients in the future.