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R Adler

Publications and source records attributed to R Adler.

At least 19 recordsLinked to original sources
PubMed1996

The bZIP transcription factor Nrl stimulates rhodopsin promoter activity in primary retinal cell cultures.

In vitro DNA binding assays and transient transfection analysis with monkey kidney cells have implicated Nrl, a member of the Maf-Nrl subfamily of bZIP transcription factors, and the Nrl response element (NRE) in the regulation of rhodopsin expression. We have now further explored the role of the NRE and surrounding promoter elements. Using the yeast one-hybrid screen with integrated NRE and flanking DNA as bait, the predominant clone obtained was bovine Nrl. Recovery of truncated clones in the screen demonstrated that the carboxyl-terminal half of Nrl, which contains the basic and leucine zipper domains, is sufficient for DNA binding. To functionally dissect the rhodopsin promoter, transient expression studies with primary chick retinal cell cultures were performed. Deletion and mutation analyses identified two positive regulatory sequences: one between -40 and -84 base pairs (bp) and another between -84 and -130 bp. Activity of the -40 to -84 region was shown to be largely due to the NRE. On co-transfection with an NRL expression vector, there were 3-5-fold increases in the activity of rhodopsin promoter constructs containing an intact NRE but little or no effect with rhodopsin promoters containing a mutated or deleted NRE. Nrl was more effective than the related bZIP proteins, c-Fos and c-Jun, in stimulating rhodopsin promoter activity. The -84- to -130-bp region acted synergistically with the NRE to enhance both the level of basal expression and the degree of Nrl-mediated trans-activation. These studies support Nrl as a regulator of rhodopsin expression in vivo, identify an additional regulatory region just upstream of the NRE, and demonstrate the utility of primary retinal cell cultures for characterizing both the cis-acting response elements and trans-acting factors that regulate photoreceptor gene expression.

Amino Acid Sequence↗
PubMed1996

Correlations between terminal mitosis and differentiated fate of retinal precursor cells in vivo and in vitro: analysis with the "window-labeling" technique.

We have investigated with high resolution the timing of retinal precursor cell commitment to specific differentiated fates, using an in ovo modification of the in vitro "window-labeling" technique (A. M. Repka and R. Adler, J. Histochem. Cytochem. 40, 947-953, 1992a). The method involves an initial injection of tritiated thymidine into chick embryos, followed a specific number of hours later by an injection of bromodeoxyuridine (BrDU); cells born during this period are identified by being labeled with thymidine but not with BrDU. We used this method to determine, in a narrow region adjacent to the choroid fissure, the fate of cells born during defined 5-hr intervals between Embryonic Days (ED) 4-8. All the cohorts gave rise to heterogenous differentiated populations, indicating that time of cell birth is not a major cell fate determinant. A progressive restriction in the developmental potential of precursor cells, however, was suggested by the observed decrease in the number of different populations generated during each 5-hr period from ED 4 to 8, and supported also by dissociated cell culture experiments investigating the fate of cells born at different developmental stages. Microenvironmental influences were tested in vitro using cells windowed-labeled in ovo for 5 hr on ED 5. After spending at least 72 hr within the retina before their isolation for culture, these cells mimicked their in vivo fate, giving rise predominantly to nonphotoreceptor neurons; a completely different behavior was observed when the cells were isolated after shorter exposures to the retinal microenvironment, when they gave rise predominantly to photoreceptors. Together with data demonstrating that differential cell death cannot account for these results, our results are consistent with the hypothesis that cell fate determination occurs after the time of terminal mitosis.

Animals↗
PubMed1996

Mechanisms of photoreceptor death in retinal degenerations. From the cell biology of the 1990s to the ophthalmology of the 21st century?

There is still no effective treatment for retinal degenerative diseases such as retinitis pigmentosa (RP), in which the loss of photoreceptor cells causes visual loss and eventually blindness. In addition to its intrinsic scientific interest, basic research aimed at elucidating the biological mechanisms regulating the survival and function of cones and rods is also important from a clinical perspective, since it could provide a foundation for the development of therapeutic strategies for these diseases. The recent observation that photoreceptor degeneration in several RP animal models occurs through programmed cell death (apoptosis) illustrates this possibility well. This article will present a brief overview of recent research contributions toward the search for treatments for retinal degenerations of genetic origin.

Animals↗
PubMed1996

Psychosocial and family functioning in children with insulin-dependent diabetes at diagnosis and one year later.

Examined the initial impact and subsequent adjustment to the diagnosis of insulin-dependent diabetes mellitus (IDDM). Children between 1 and 14 years of age and their families were assessed several weeks after diagnosis and again a year later using standardized measures of child behavior, parental mental health, and family functioning. Immediately after diagnosis, the children and both parents exhibited mild symptoms of psychological distress but these had largely resolved at 12-month follow-up. The impact of IDDM diagnosis on family functioning varied with informant, SES, and the age of the child, with an overall tendency for families to become less flexible over the year. Findings suggest that most children and their parents exhibit satisfactory individual adjustment after a period of initial stress but family functioning is affected in complex ways. Serial follow-up of the cohort is planned to establish whether the current findings are predictive of longer term outcome.

Adaptation, Psychological↗
PubMed1996

Child Behaviour Checklist classification of behaviour disorder.

OBJECTIVE: The aim of this study was to determine the applicability of the published clinical cut-off scores of the Child Behaviour Checklist (CBCL) for the classification of behaviour disorders. METHODOLOGY: Child Behaviour Checklists were obtained for 1342 subjects newly referred to the six major mental health centres in Melbourne. The normative community sample of 1002 7-, 12- and 15-year-olds was drawn from a school-based asthma prevalence study. RESULTS: The mean total problem T-score for the children referred to mental health centres was 67 and was above the clinical range for all age groups. Using referral to psychiatric services as the gold standard, the sensitivity and specificity of the CBCL using a cut-off of > or = 60, was 77.4 and 83.2%, respectively. This compares favourably with the sensitivity of 68% and specificity of 82% for the American sample. Using a cut-off score of > or = 63, the sensitivity was 70.5% and the specificity was 88.6%. The referred and community samples differed with respect to socio-economic status, family structure and mothers' level of education. Fifty-two per cent of the clinically referred children lived with both parents, compared with 89% of the community sample. CONCLUSIONS: While there are some limitations to this study in terms of both the clinic and community sample, support is provided for the usefulness and applicability of the recommended CBCL cut-off scores in an Australian population.

Adolescent↗
PubMed1996

Development and maintenance of outer segments by isolated chick embryo photoreceptor cells in culture.

PURPOSE: To investigate the capacity of isolated chick embryo photoreceptors to develop and maintain outer-segment processes in dissociated cell cultures, in the absence of pigment epithelial and glial cells. METHODS: Cells were obtained from the retinas of embryonic day (ED) 17 chick embryos, after the onset of outer-segment formation in vivo. After 5 to 12-minute incubation in Ca++ and Mg++-free Hank's balanced salt solution, neural retinas were freed from other optical tissues, including the pigment epithelium. Retinal cell suspensions were prepared by repeated pipetting after mild trypsinization and were grown in serum-containing medium on a polyornithine-coated substratum. Cell differentiation was evaluated using phase-contrast and transmission electron microscopes and by autoradiographic analysis of the uptake of putative amino acid neurotransmitters, lectin cytochemical analysis, and immunocytochemical analysis with rod and cone-specific antibodies. Cells isolated from ED 8 retinas, before the onset of outer-segment formation in vivo, were also studied. RESULTS: At culture onset, ED 17 cells appeared morphologically undifferentiated and devoid of processes; differentiated features could be detected after 24 to 48 hours in vitro. Photoreceptor cells were the most abundant cell type after 6 days in vitro, followed by nonphotoreceptor multipolar neurons and morphologically undifferentiated cells. Autoradiographic analysis showed extensive Na+ -dependent uptake of (2,3,4-(3)H)gamma- aminobutyric acid in nonphotoreceptor neurons, whereas photoreceptors were labeled predominantly with 3H-glutamate. Most of the photoreceptors were labeled with fluorescent peanut lectin and with a sheep polyclonal antibody against bovine rhodopsin. Subsets of photoreceptors, on the other hand, were immunoreactive with cone- or rod-specific monoclonal antibodies COS-1, OS-2, 50-1B11, or Rho-4D2. Approximately 50% to 65% of the photoreceptors positive with these monoclonal antibodies showed a remarkable polarization of immunoreactive materials, which accumulated predominantly, or even exclusively, in an outer-segment-like apical process. When viewed on the transmission electron microscope, these outer-segment-like processes appeared as distal expansions of the photoreceptor cilium and contained disc-like membranous profiles. Outer-segment-like processes also could be detected using the electron microscope and by immunocytochemical analysis of cultures of ED 8 retinal cells. CONCLUSIONS: After undergoing morphologic dedifferentiation as a result of tissue dissociation, isolated retinal photoreceptors, grown in the absence of contact-mediated cell interactions and of pigment epithelial and glial cells, can regenerate and maintain a highly polarized pattern of structural and molecular organization, including the formation of outer-segment-like processes. The cultures provide an experimental system for the investigation of cellular and molecular mechanisms regulating further development and maturation of these photoreceptor structures.

Animals↗
PubMed1995

Hodgkin's disease as an indicator of AIDS.

Hodgkin's disease (HD) is not currently included within the Centers for Disease Control (CDC) classification system for AIDS. Upon HD diagnosis, HIV(human immunosuppressive virus)-positive patients are generally found within Stages III or IV of the Ann Arbor HD classification system, already exacerbating the problem of treatment. In contrast, HIV-negative patients diagnosed with HD are generally found within Stages I or II. Epidemiology and the presence of secondary lymphomas, opportunistic infections, or aggressive pathologies, accompanied by low survival rate and timing of HD diagnosis suggest that HD should be included among conditions indicating AIDS manifestation.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Chromokinesin: a DNA-binding, kinesin-like nuclear protein.

Microtubule-associated mechanoenzymes have been proposed to play a fundamental role in chromosome movement. We have cloned and characterized the cDNA for a novel protein, named Chromokinesin, that fulfills several of the criteria expected of a mitotic motor. Chromokinesin contains both a kinesin motor-like domain and an unusual basic-leucine zipper DNA-binding domain. Its mRNA is readily detectable in proliferating cells, but not in postmitotic cells. Immunocytochemical analysis with antibodies directed against the nonconserved COOH-terminal region of Chromokinesin indicates that the protein is localized in the nucleus, and primarily associated with chromosome arms in mitotic cells. These data suggest that Chromokinesin is likely to function as a microtubule-based mitotic motor with DNA as its cargo.

Amino Acid Sequence↗
PubMed1995

Biliary cystadenoma of cats.

Published surveys of feline neoplasia have not specifically included biliary cystadenoma, and there is only one case report in the literature. This report is a compilation of 13 feline cases and provides a description of clinical, pathologic, immunohistochemical, and ultrastructural aspects of biliary cystadenoma as well as a discussion of comparative pathology of biliary cystadenoma in human beings and speculative histogenesis.

Adenoma, Bile Duct↗
PubMed1995

Specific targeting of adriamycin conjugates with monoclonal antibodies to hepatoma associated antigens to intrahepatic tumors in athymic mice.

Doxorubicin (adriamycin), once considered the treatment of choice for hepatocellular carcinoma (HCC), is known to cause cardiotoxicity and myelotoxicity. To reduce the systemic toxicity of adriamycin by direct delivery of the drug to the tumor site, we established a panel of monoclonal antibodies (MAbs) to hepatoma associated antigens that were conjugated to adriamycin by a dextran bridge. Initially, the efficacy of these conjugates in suppressing tumor growth was assessed using a model of subcutaneous HCC tumors injected in athymic mice. In the second stage of the study, we tested these conjugates in an experimental model in which human HCC was transplanted intrahepatically by intrasplenic injection, thus providing the tumor cells with growth factors and an adequate cellular matrix, similar to the natural microenvironment of HCC. Anti-tumoral therapy resulted in lower serum alpha-fetoprotein (AFP) levels in two of three experimental groups treated with different specific conjugates as compared with control mice treated with the individual components. Efficacy of targeting was enhanced using the intrahepatic model system for propagation of HCC and was demonstrated by fluorescence of adriamycin and MAb in tumor tissue and absence of this fluorescence in healthy liver tissue surrounding the tumor. Reduction of systemic toxicity was shown by the absence of adriamycin fluorescence in myocardial tissue in conjugate-treated mice, whereas in all other treatment groups, including mice treated with a mixture of adriamycin and specific MAb, there was strong myocardial fluorescence of adriamycin.

Animals↗
PubMed1995

Successful immunization of autologous bone marrow transplantation recipients against hepatitis B virus by active vaccination.

Patients undergoing autologous bone marrow transplantation (BMT) are severely immunosuppressed. These patients are exposed to various infections agents due to delayed and efficient reconstitution of their immune system. Forty-eight patients with hemato-oncological malignancies were immunized against hepatitis B virus (HBV) following autologous BMT. Twenty one were vaccinated more than 10 days before BMT, 17 on days 1-9 before and 10 day after BMT. Thirty three patients (68.7%) seroconverted within 40 days after autologous BMT after receiving one dose of the vaccine before autologous BMT with a relatively low level of anti-HBs, whereas in 11 no anti-HBV antibodies could be detected. Nineteen patients remained seropositive but in 11 the seroconversion was only transient no correlation was found between permanent or transient seroconversion and basic disease, conditioning regimens, post-transplant therapy, immunotherapy and day of vaccination in relation to autologous and day of vaccination in relation to autologous BMT. Active HBV immunization of patients with malignancy undergoing autologous BMT is feasible and levels of antibodies, although low, are above the conventional protective titers. Therefore active immunization of some patients may reduce hepatitis-related complications in the setting of autologous BMT.

Adolescent↗
PubMed1995

Apoptotic photoreceptor degeneration in experimental retinal detachment.

PURPOSE: To investigate the possibility that cell death in retinal detachment may occur by reactivation of apoptotic programmed cell death mechanisms. METHODS: Unilateral retinal detachments were created in adult cats using 0.25% sodium hyaluronate; detached and control retinas were studied at different intervals. Internucleosomal DNA fragmentation (one of the landmarks of apoptosis) was investigated in tissue sections with the TUNEL technique, which uses terminal transferase to label with biotinylated nucleotides the 3' ends of DNA fragments. Sections also were labeled with propidium iodide, which intensely stains pyknotic nuclei. In addition, one time point was selected for analysis with electron microscopy. RESULTS: TUNEL-positive (T+) and propidium iodide-positive (PI+) cells almost never were observed in retinas from control eyes, but they were abundant at defined time points after retinal detachment, appearing almost exclusively in the photoreceptor layer. Their frequency was particularly high 1 to 3 days after detachment but declined rapidly over the next several weeks. T+ cells were still present 28 days after retinal detachment. Electron microscopy also revealed evidence of apoptotic cells after retinal detachment. CONCLUSIONS: Results are consistent with the hypothesis that photoreceptor degeneration after retinal detachment occurs through apoptosis, usually associated with intrinsic, programmed cell death mechanisms. The detection of a rapid wave of photoreceptor degeneration seems to suggest that early therapeutic interventions might be recommended; agents capable of interfering with the apoptotic mechanism could have a role in the prevention of cell losses that represent a critical complication of retinal detachment.

Animals↗
PubMed1994

A developmentally regulated basic-leucine zipper-like gene and its expression in embryonic retina and lens.

Transcriptional regulators play important roles in the control of key developmental events. We have identified sw3-3, a likely candidate for such a function, in tissues of the eye and other neural organs. It encodes a basic-leucine zipper-like protein, in which two leucine zipper motifs flank a basic domain. The latter contains helix-disturbing amino acids such as glycine and proline, at positions occupied by conserved asparagine and alanine residues (respectively) in "conventional" basic-leucine zipper proteins. sw3-3 is widely expressed at early embryonic stages in the lens, retina, and other neural tissues and is down-regulated thereafter with a spatial and temporal pattern that correlates with the cessation of mitotic activity and the onset of cell migration and differentiation.

Amino Acid Sequence↗
PubMed1994

Apoptotic photoreceptor cell death in mouse models of retinitis pigmentosa.

Retinitis pigmentosa (RP) is a group of inherited human diseases in which photoreceptor degeneration leads to visual loss and eventually to blindness. Although mutations in the rhodopsin, peripherin, and cGMP phosphodiesterase genes have been identified in some forms of RP, it remains to be determined whether these mutations lead to photoreceptor cell death through necrotic or apoptotic mechanisms. In this paper, we report a test of the hypothesis that photoreceptor cell death occurs by an apoptotic mechanism in three mouse models of RP: retinal degeneration slow (rds) caused by a peripherin mutation, retinal degeneration (rd) caused by a defect in cGMP phosphodiesterase, and transgenic mice carrying a rhodopsin Q344ter mutation responsible for autosomal dominant RP. Two complementary techniques were used to detect apoptosis-specific internucleosomal DNA fragmentation: agarose gel electrophoresis and in situ labeling of apoptotic cells by terminal dUTP nick end labeling. Both methods showed extensive apoptosis of photoreceptors in all three mouse models of retinal degeneration. We also show that apoptotic death occurs in the retina during normal development, suggesting that different mechanisms can cause photoreceptor death by activating an intrinsic death program in these cells. These findings raise the possibility that retinal degenerations may be slowed by interfering with the apoptotic mechanism itself.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1994

Cell-type- and developmental-stage-specific metabolism and storage of retinoids by embryonic chick retinal cells in culture.

Biological functions of retinoids in the vertebrate retina include the role of 11-cis retinaldehyde as visual pigment chromophore, and possible effects of retinoic acid in histogenesis and cell survival. Qualitative and quantitative regulation of retinoid availability for these complex processes could involve several cell types, including retinal pigment epithelium, Müller glia and retinal photoreceptors and non-photoreceptor neurons; their relative contributions, however, have not been fully elucidated. Using purified cultures, we have carried out a study of cell-type-specific metabolism and storage of retinoids in chick embryo retinal photoreceptors and other neuronal cells, as compared to those of retinal glia. Retinal glia were found to synthesize both retinoic acid and retinyl esters, and to hydrolyse the latter; they also displayed retinol dehydrogenase activities. Cultured neurons and photoreceptors also synthesized and hydrolysed retinyl esters; their capacity for retinaldehyde synthesis from a retinol or retinyl ester substrate suggested the presence of retinol dehydrogenase activity. Retinoic acid was not synthesized in differentiated neuronal cultures, although some synthesis was detectable at early culture stages when the cells were still morphologically undifferentiated. These findings indicate that cell-type-specific metabolic activities are expressed during retinal cell differentiation in vitro, and that embryonic retinal photoreceptors and nonphotoreceptor neurons are active participants in the metabolism and storage of retinoids.

Animals↗
PubMed1994

Improved immunogenicity in mice of a mammalian cell-derived recombinant hepatitis B vaccine containing pre-S1 and pre-S2 antigens as compared with conventional yeast-derived vaccines.

The widely used hepatitis B virus (HBV) vaccines consist of the small hepatitis B surface (SHBs) protein produced in transfected yeast cells. The frequency of non-responders, especially among immunocompromised patients, has increased the demand for a more immunogenic vaccine. We evaluated the immunogenicity of recombinant HBs 20 nm particles secreted by transfected Chinese hamster ovary (CHO) cells, Bio-Hep-B (BioTechnology General Ltd, Israel), and compared it with yeast-derived vaccines. The CHO-derived vaccine contains the small hepatitis B surface antigen (SHBs protein) as the major component, as well as the middle HBs (MHBs, pre-S2) and the large HBs (LHBs, pre-S1) antigens. Nine groups of ten female Balb/c mice, 4-6 weeks old, were injected once intraperitoneally (i.p.) with 0.09, 0.27 or 0.81 micrograms of each of three vaccines: Bio-Hep-B or two conventional yeast-derived recombinant vaccines, Engerix-B (SmithKline Beecham, Belgium) and H-B-Vax II (Merck, Sharp & Dohme, USA) containing only non-glycosylated SHBs antigen. After 30 days, 40% of the mice injected with 0.09 microgram Bio-Hep-B had seroconverted, but none of the mice receiving the same dose of the other vaccines. The immunogenic dose in 50% of the mice at day 14 after injection was 0.13 microgram for Bio-Hep-B, but over 0.81 microgram for the other two vaccines. Mice of the strain B10/M (which are unresponsive to SHBs and MHBs antigens at the T-cell level) developed 100-fold higher anti-HBs titres after immunization with 1 microgram of Bio-Hep-B i.p., as compared with mice receiving the same amount of yeast-derived HBsAg vaccines.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗