On the partial suppression of IL-2 receptor expression and the prevention of lectin-induced lymphoblast formation by cyclosporine A.

The effect of cyclosporine A (CyA) on the expression of the Tac-antigen (IL-2 receptor) on PHA-activated PBMNC was analysed by immunofluorescence. In the initial experiments we determined the number of Tac(+) cells, disregarding cell size; we found that CyA did not affect the number of cells expressing the Tac antigen after lectin stimulation (Fig. 1, Table 1). When we found that comparable numbers of Tac(+)-lymphocytes absorbed less IL-2 when grown in CyA as compared to solvent controls, we analysed in more detail the correlation between Tac-antigen expression and cell size of cell populations grown in CyA. It was found that CyA prevented a majority of PHA-activated PBMNC to undergo blastogenesis despite having expressed the IL-2 receptor. A minority of the cells, however, were refractory to the CyA-mediated suppression of blast formation. Studies analysing the Tac antigen expression semiquantitatively showed that CyA reduced the intensity of Tac antigen expression on cells of all sizes.     

Chromosome 8p deletions are associated with invasive tumor growth in urinary bladder cancer.

Alterations of chromosome 8, including deletions of 8p, occur frequently in many tumors. In this study, fluorescence in situ hybridization was used to study the relationship between 8p deletions, 8q gains, and phenotype in bladder cancer. Cells from 87 tumors were examined by dual-labeling fluorescence in situ hybridization with a centromere 8 probe (pJM12) and P1 probes for 8p22, 8p12, 8q12, and 8q24. Both 8p22 deletions and 8q24 gains were strongly associated with tumor phenotype. There was a marked difference in 8p22 deletions between noninvasive (pTa) tumors (3/33) and minimally invasive (pT1) tumors (8/19; P = 0.005) whereas there was no significant difference between pT1 and muscle-invasive (pT2-4) tumors (19/35; P = 0.3926). Six tumors with 8p22 deletion were examined at 8p12. Three of these tumors showed no 8p12 deletion, narrowing down the site of a putative tumor suppressor gene distal to 8p12. In one other case, there was a marked increase in 8p12 copy number (> 40 per cell; amplification), suggesting the presence of an oncogene involved in bladder cancer at 8p12. The marked difference in 8p22 deletions between noninvasive (pTa) and minimally invasive (pT1) tumors is consistent with a role of a putative tumor suppressor gene on 8p for development of invasive tumor phenotype.     

Cell-mediated immune responses in vitro. V. A comparative study of in vitro immunogenicity of splenic lymphocytes, neoplastic lymphoid cells and fibroblats

This study compares the effectiveness of mouse lymphocytes, neoplastic lymphoid cells or fibroblasts in stimulating allogeneic cells to embark on an in vitro cytotoxic response, as measured by a ⁵¹Cr release assay. In addition, during ontogeny of mouse spleen cells, their capacity to stimulate in the mixed lymphocyte culture (MLR) was compared to their capacity to stimulate cytotoxic allograft responses. During ontogeny, there was amarked increase in the capacity of mouse spleen cells to stimulate mitotic responses in the MLR. In contrast, the magnitude of cytotoxic allograft responses induced by neonatal mouse spleen cells in the cytotoxic allograft system was comparable in magnitude to that induced by spleen cells of adult mice. The immunogenicity of subpopulations of mouse spleen cells was investigated. Mouse lymphoid cell populations, enriched for B or T lymphocytes or hemopoietic stem cells were equally immunogenic in vitro, as were myeloma or thymoma lymphoid cells. In contrast, mouse fibroblasts were found to elicit poor cytotoxic allograft responses. In fact, lymphoid cells were about 20–40-fold more immunogenic than fibroblasts.     

Factors affecting production of catalase by Bacteroides.

Several variables affected the production of catalase by members of the "Bacteroides fragilis group" of anaerobic bacteria. Both media yielded higher catalase levels than the respective agar media. Addition of hemin to media after autoclave sterilization, rather than before, significantly increased production of catalase. Both of these variables could be related to the available hemin concentration present in the medium being tested. Significantly higher amounts of hemin were required for catalase production than were required for growth. For catalase production by B. fragilis ATCC 25285, 1 microgram of hemin per ml was required. Of the various media tested, the use of chopped meat broth resulted in the highest levels of catalase production (up to 50 to 60 U of catalase per mg of protein). Of the various species and DNA homology groups tested, strains of B. fragilis and Bacteroides distasonis were catalase positive. Strains of Bacteroides thetaiotaomicron, Bacteroides ovatus, and Bacteroides eggerthi possessed variable catalase activity. Bacteroides vulgatus, Bacteroides uniformis, and DNA homology groups "3452A" and "subsp. a" were catalase negative. A catalase well test, in which equal volumes of 3% H2O2 and chopped meat culture are mixed, is described and recommended for routine catalase tests.     

Multiple forms of glycoproteins in the secretory product of the bovine subcommissural organ--an ancient glial structure

The glial subcommissural organ (SCO) is a conserved structure of the vertebrate brain that secretes a glycoprotein-rich product into both the extracellular matrix and the cerebrospinal fluid of the third ventricle that forms Reissner's fibre (RF). In order to identify specific secretory proteins of the subcommissural organ, a panel of antigen- and epitope-specific monoclonal antibodies was raised against bovine RF to study the distribution of epitopes in Western blots of bovine RF. Six groups of epitopes that were specific for SCO secretion were distinguished on the basis of their phylogenetic conservation and their different grades of resistance against chemical denaturation. The monoclonal antibody aRFME 4 recognised a carbohydrate-containing epitope that was strongly conserved in vertebrates and unique for SCO secretion. All epitopes showed essentially the same distribution pattern over 15 bovine RF glycoprotein fractions of different molecular masses in immunoblots indicating that the different RF fractions are closely related. They may represent multiple forms of SCO spondin.     

Retinal projection to the nucleus of the optic tract in the cat as revealed by retrograde transport of horseradish peroxidase

Retrograde transport of horseradish peroxidase injected iontophoretically into the nucleus of the optic tract of cats revealed that the direction-selective cells in this pretectal nucleus receive direct retinal projections from small retinal ganglion cells, the so-called gamma-cells. These cells from a horizontal band on the contralateral retina. Few labeled cells are found in the ipsilateral temporal retina. The input from the contralateral retina is 10 times more numerous than from the ipsilateral one. In both retinae the highest concentration of labeled cells is near the area centralis.     

Density profile of group B streptococci, type III, and its possible relation to enhanced virulence.

The buoyant densities of virulent and colonizing group B streptococci, type III, were determined by centrifugation of bacteria on a linear, hypotonic density gradient. A total of 28 strains were investigated. Eleven strains were obtained from blood cultures of babies with early-onset disease, and eight strains were isolated from the cerebrospinal fluid of babies with late-onset septicemia and meningitis. Nine colonizing strains were genital isolates from pregnant women subsequently giving birth to healthy children. In each strain the buoyant density was determined before and after neuraminidase treatment. All strains showed an increase in the buoyant density after enzymatic removal of sialic acid, and the density differences before and after desialylation were calculated. The mean values of these differences for blood, cerebrospinal fluid, and colonizing isolates were 23.4, 25.3, and 10.6 mg/ml, respectively. The mean value for the colonizing strains differed significantly from the mean value for each group of virulent strains. All colonizing strains banded singly in the gradient, whereas five of the virulent strains divided into two density populations. Extracts of the low-density cells produced markedly more dense immunoprecipitates with type antiserum than did extracts of the high-density bacteria. One double-banding strain was positive for R protein. After separation of the two density populations, this antigen was detected only in the low-density population. The results indicate that bacterial buoyant density is inversely related to the amount of capsular polysaccharide enveloping the cell and that a determination of the density profile of the bacteria may be used for discriminating strains with an increased pathogenic potential.     

Primary myocardial disease in the cat. A model for human cardiomyopathy.

Thirty-four cats with primary myocardial disease were studied. The cats were divided into two groups, depending on the clinical, hemodynamic, angiocardiographic, and pathologic findings. Group A consisted of those cats with hypertrophic cardiomyopathy and Group B consisted of those cats with congestive cardiomyopathy. Similarity in the characteristics of cardiomyopathy in the human cat was found. Both Group A and Group B consisted predominantly of mature adult male cats. The most common presenting signs were dyspnea and/or thromboembolism, systolic murmurs with gallop rhythms on auscultation, cardiomegaly with (Group A) or without (Group B) pulmonary edema, abnormal electrocardiograms, elevated left ventricular end diastolic pressures, and angiocardiographic evidence of mitral regurgitation with left ventricular concentric hypertrophy (Group A) or left ventricular dilatation (Group B). Some cats in Group A also had evidence of left ventricular outflow obstruction. The principal pathologic findings in these cats were left atrial dilatation, symmetric hypertrophy or asymmetric septal hypertrophy of the left ventricle (Group A), and dilatation of the four cardiac chambers (Group B). Aortic thromboembolism was commonly observed in both groups. These clinical and pathologic findings indicate that cardiomyopathy in the cat is similar to the two most common forms of cardiomyopathy in the human (hypertrophic cardiomyopathy, with and without obstruction, and congestive cardiomyopathy).     

Postnatal expression of transport proteins involved in acid–base transport in mouse kidney

The kidney plays a major role in maintaining and controlling systemic acid–base homeostasis by reabsorbing bicarbonate and secreting protons and acid-equivalents, respectively. During postnatal kidney development and adaptation to changing diets, plasma bicarbonate levels are increasing, the capacity for urinary acidification maturates, and the final morphology and distribution of intercalated cells is achieved. In adult kidney, at least two types of intercalated cells (IC) are found along the collecting duct characterised either by the expression of AE1 (type A IC) or pendrin (non-type A IC) where non-type A IC are found only in the convoluted distal tubule, connecting tubule and cortical collecting duct. Here we investigated in mouse kidney the relative mRNA abundance, protein expression levels and distribution of several proteins involved in renal acid–base transport, namely, the Na⁺/HCO₃ ^– cotransporter NBC1 (SLC4A4), the Na⁺/H⁺-exchanger NHE3 (SLC9A3), two subunits of the vacuolar H⁺-ATPase [ATP6V0A4 (a4), ATP6V1B1 (B1)], the Cl^–/HCO₃ ^– exchangers AE1 (SLC4A1) and pendrin (SLC26A4). Relative mRNA abundance of all transport proteins was lowest at day 3 after birth and increased thereafter in parallel with protein levels. The numbers of type A and non-type A IC in the cortical collecting duct (CCD) increased from day 3 to days 18 and 24, whereas the number of IC in the CCD with apical staining for the vacuolar H⁺-ATPase subunits a4 and B1 decreased from day 3 to days 18 and 24, respectively. In addition, cells with characteristics of non-type A IC (pendrin expression, basolateral expression of vacuolar H⁺-ATPase subunits) were found in the inner and outer medulla 3 days after birth but were absent from the medulla of 24-day-old mice. Taken together, these results demonstrate massive changes in mRNA and protein expression levels of several acid–base transporters during postnatal kidney maturation and also show changes in intercalated cell phenotype in the medulla during these processes.