Characterization of CD34+ thymic stromal cells located in the subcapsular cortex of the human thymus

In this paper we report that suspensions of human fetal thymocytes contain cells that express high levels of CD34 and Thy-1. These cells were characterized with regard to location within the thymus, phenotype, and function. Confocal laser scan analysis of frozen sections of fetal thymus with anti-CD34 and Thy-1 antibodies revealed that the double-labeled cells were located in the pericortical area. In addition, it was found that the CD34+Thy-1+ cells lacked CD45 and CD50, indicating that these cells are not of hematopoietic origin; this was confirmed by the finding that these cells could be cultured as adherent cells in a medium with cholera toxin and dexamethasone, but failed to grow in mixtures of hematopoietic growth factors. Further analysis indicated that most cultured CD34+Thy-1+ cells expressed cytokeratin (CK) 14 but lacked CK 13, suggesting that these cells are immature epithelial cells. Cultured CD34+Thy-1+ cells were able to induce differentiation of CD1-CD34+CD3-CD4-CD8- thymic precursors into CD4+CD8+ cells in a reaggregate culture in the absence of exogenous cytokines. The CD4+CD8+ cells that developed in these cultures did not express CD3, indicating that CD34+Thy-1+ thymic stromal cells are not capable of completing full T cell differentiation of thymic hematopoietic progenitor cells.     

Hydrogen peroxide induces protection against lethal effects of cumene hydroperoxide in Escherichia coli cells: an Ahp dependent and OxyR independent system?

Despite a large body of evidence showing the beneficial effects of successful treatment of anemia with recombinant human erythropoietin (EPO) in patients with end-stage renal disease, controversy remains as to whether EPO treatment of anemia can improve the nutritional status in patients on maintenance hemodialysis. This prompted us to conduct a prospective study in 41 hemodialysis patients with basal hemoglobin less than 9 g/dl. The dose of EPO was increased for 12 weeks to achieve the target hemoglobin concentration of 10 g/dl and then titrated in the following 12 weeks to maintain the target value. Nutritional status was assessed at baseline and after 6 months of follow-up, using the global protein-calorie malnutrition (PCM) index proposed by Bilbrey and Cohen. A low global PCM score indicates better nutrition. The results showed that hemoglobin values significantly increased from 8.7 +/- 0.8 g/dl at baseline to 10.7 +/- 0.5 g/dl in the 6th month (p < 0.001). No significant changes were observed in the normalized protein catabolic rate and Kt/V during the study period. Global PCM scores improved from 30.0 +/- 7.5 to 23.6 +/- 3.1 (p < 0.001) and paralleled the correction of anemia by EPO treatment. The data were consistent with a major improvement in the nutritional markers of relative body weight, triceps skinfold, midarm circumference, midarm muscle circumference, serum albumin, serum transferrin and total lymphocyte count in the 6th month as compared to baseline. The percentages of mild and moderate-severe PCM at baseline were 32 and 58%, respectively. These percentages were significantly reduced during the 6th month to 20 and 30%, respectively (p = 0.0004). In summary, correction of renal anemia with EPO improves the nutritional status in hemodialysis patients. A postulated mechanism is that EPO may exhibit anabolic effects, with a better utilization of ingested protein.     

Phenotypic expression of a mannose-sensitive hemagglutinin by a Vibrio cholerae O1 E1Tor strain and evaluation of its role in intestinal adherence and colonization

A Vibrio cholerae O1 strain (1150) of the EIT or biotype and Ogawa serotype with haemagglutination (HA) activity was subjected to TnphoA mutagenesis. Out of several mutants isolated, one HA- and another HA+ mutant were further characterised. The HA- mutant showed about 50% reduction in its intestinal adherence capacity in vitro and about 9-fold decrease of its colonisation ability in vivo, as compared to the wild-type strain. Subsequent studies showed that the HA activity of strain 1150 was mediated by a mannose-sensitive haemagglutinin (MSHA). Thus, the phenotypic expression of MSHA appears to be partly responsible for the intestinal adherence and colonisation properties of strain 1150.     

Parathyroid hormone-related protein in patients with primary breast cancer and eucalcemia

Parathyroid hormone-related protein (PTHrP) is a causative factor of humoral hypercalcemia in breast cancer and other malignancies. We studied circulating PTHrP levels with three different immunoassays directed against different parts of the PTHrP molecule in 48 patients with breast cancer and eucalcemia. The methods used were: (a) a RIA with antibodies directed toward the midregion (63-78); (b) an immunofluorometric assay with two antibodies against 1-34 and 38-67; and (c) an immunoradiometric assay with antibodies against 1-40 and 1-72. Although most patients had PTHrP levels indistinguishable from normal when measured by all three methods, four patients had increased serum levels in the IFMA. PTHrP was detected by immunohistochemistry in tumors from nearly all patients. One patient with elevated PTHrP in plasma measured by IFMA showed intense staining of tumor by immunohistochemistry; the tumor was histologically graded as III (severe) and was the largest of all tumors in this patient group. The IFMA can identify increased serum PTHrP in some patients with breast cancer who are not hypercalcemic. This assay may be especially useful in screening patients for this tumor during a relative early phase of the disease.     

Effects of high calcium intake on fat digestion and bile acid excretion in feces of veal calves

To diagnose visceral leishmaniasis (kala-azar), we have developed a nested PCR method based on amplification of the mini-exon gene, which is unique and tandomly repeated in the Leishmania genome. Nested PCR was sufficiently sensitive for the detection of DNA in an amount equivalent to a single Leishmania parasite or less. We examined the usefulness of this PCR method using bone marrow aspirates and buffy coat cells collected from kala-azar patients who had or had not received chemotherapy in northwest China. We obtained PCR positivity for all of the parasitologically positive bone marrow samples from the patients. Some ambiguities with the primary PCR results were eliminated by the subsequent nested PCR. The buffy coat samples from 7 of 12 patients with splenomegaly were positive by the nested PCR, although only 2 of them were positive for parasites by culture. However, buffy coat samples from nine children, whose splenomegaly has been reduced and clinically cured by antimony treatment, were all negative. Thus, this nested PCR method represents a new tool for the diagnosis of kala-azar with patient blood samples instead of bone marrow or spleen aspirates obtained by more invasive procedures.