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R Adler

Publications and source records attributed to R Adler.

At least 19 recordsLinked to original sources
PubMed1992

Developmental regulation of adenosine A1 receptors, uptake sites and endogenous adenosine in the chick retina.

Although adenosine A1 receptors mediate the inhibition of dopamine-dependent stimulation of adenylate cyclase activity in the developing chick retina, their localization and function are unknown. We have examined the localization of these receptors, and of endogenous adenosine and adenosine uptake sites at several stages of chick retinal development. A1 receptors were already localized predominantly to plexiform regions by embryonic day 12 (E12) with no gross changes at subsequent stages. Adenosine immunoreactivity was absent from retina at E8 but was detected at E12 in the ganglion cell layer, as well as cells in the inner nuclear cell layer and photoreceptors. At more advanced developmental stages the immunoreactivity was greater, but displayed similar localizations. Uptake sites labeled with [3H]nitrobenzylthioinosine (NBI) were detected even earlier using binding and autoradiographic methods. [3H]NBI binding was saturable, and Scatchard analysis demonstrated a single class of sites with a Kd of 0.91 nM and Bmax of 298 fmol/mg protein in E15 retinal membranes. The binding was displaced by unlabeled NBI and dipyridamole. NBI binding sites differentiated earlier than adenosine A1 receptors or endogenous adenosine immunoreactivity, showing a diffuse distribution at E8, but predominating in the plexiform layers of more developed retinas. The results indicate that elements of a putative purinergic system differentiate at specific localizations early in retinal development.

Adenosine↗
PubMed1992

Estrogen suppresses hepatitis B virus expression in male athymic mice transplanted with HBV transfected Hep G-2 cells.

Hormones are known to regulate both viral and cellular genes. It has been shown previously that estrogen has an effect on liver gene transcription and mRNA stability. Sex hormones might have a role in the chronic persistence of hepatitis B virus (HBV) infection. In fact, there is a male preponderance in the incidence of chronic HBV infection, and HBsAg expression was reported to be much higher in male transgenic mice than in the females. We investigated the effect of estrogen on HBV gene expression and regulation in athymic mice bearing 2.2.15 cells, a human hepatoblastoma cell line derived from Hep G-2 transfected with HBV sequences. Both male and female mice were treated with estradiol after tumors could be observed. Episomal DNA was extracted from the tumors and hybridized with 32P-labelled HBV DNA. Southern blot and slot blot analyses demonstrated that male mice had higher expression of HBV DNA. Estrogen treatment suppressed HBV DNA expression in males, but had only a minor effect on females. HBeAg production in male mice was also inhibited by estrogen treatment. HBV RNA extracted from 2.2.15 cells showed 2-3-fold reduction following beta-estradiol treatment. Moreover, inhibition of HBV transcription by estrogen was demonstrated by an RNA pulse-labelling experiment. These data indicate that estrogen inhibits HBV expression in the in vivo model presented in this study. These results might contribute to a better understanding of the effect of sex hormones on the pathogenesis of HBV-induced liver disease.

Animals↗
PubMed1992

A visual pigment from chicken that resembles rhodopsin: amino acid sequence, gene structure, and functional expression.

The amino acid sequence of a rhodopsin-like visual pigment from chickens has been determined by isolating and sequencing its gene. The predicted sequence is between 70% and 80% identical to bovine, human, and chicken rhodopsins and between 40% and 50% identical to human blue, green, and red cone pigments, the chicken red cone pigment, and cavefish long-wave cone pigments. The encoded pigment, produced by transfection of cDNA into cultured cells, absorbs maximally at 495 nm as determined from photobleaching difference spectra and reacts at 20 degrees C with 50 mM hydroxylamine with a half-time of 16 min. These properties, together with a high pI predicted from the amino acid sequence, suggest that this cloned gene encodes the chicken green pigment previously identified by biochemical and spectroscopic studies. This sequence defines a new branch of the visual pigment gene family.

Amino Acid Sequence↗
PubMed1992

Immunotargeting of daunomycin to localized and metastatic human colon adenocarcinoma in athymic mice.

A monoclonal antibody (designated SF25), which recognizes a protein antigen expressed on a large number of human colon carcinomas, was used for drug targeting. Daunomycin-antibody conjugates were prepared by two previously described procedures. In one, the drug was bound to the antibody through a spacer of small molecular mass (cis-aconitic acid), while in the other a dextran bridge served as the link between drug and antibody. High substitution rates of drug to antibody were obtained using the latter binding procedure. Both conjugates were tested in vitro against two human colon carcinoma cell lines, LS180 and KM-12. The efficacy of a daunomycin-dextran-SF25 antibody conjugate was tested against colon carcinoma LS180 tumors transplanted at different sites into athymic mice. The specific conjugate was significantly more inhibitory to a subcutaneous tumor growth than its components or their mixture. SF25 antibody alone showed antitumoral effects against all three forms of transplanted tumor tested, namely, local, metastatic or intrahepatic, whereas daunomycin, on its own, was effective only against the subcutaneous tumor. Binding of daunomycin to dextran partially improved its inhibitory activity against the metastatic tumor. The conjugate, daunomycin-dextran-SF25 antibody reduced the number of metastatic foci, increased the survival rate and delayed death. Yet against lymph node metastases it was not significantly better than a mixture of both constituents. However, results obtained with an intrahepatic tumor, a model that mimics the natural progression of the disease, resembled those described with the subcutaneous tumor. Daunomycin-dextran-SF25 antibody was significantly more effective than all components separately and than a mixture of drug and antibody, provided a highly drug-substituted conjugate was used.

Adenocarcinoma↗
PubMed1992

Differentiation of retinal precursor cells born in vitro.

It is not known whether the differentiated fate of retinal precursor cells is determined before, during, or after terminal mitosis. Previous studies from this laboratory led to the hypothesis that retinal precursor cells remain plastic after final mitosis and will follow a photoreceptor "default pathway" unless induced to develop as neurons by intraretinal factors. This hypothesis predicts that isolated precursors undergoing terminal mitosis and differentiation in cell culture, in the absence of the retinal microenvironment, should become photoreceptors, regardless of embryonic age. To test this prediction precursor cells were dissociated from 5- to 8-day chick embryo retinas and grown as single cells in vitro. Bromodeoxyuridine (BRDU)- and [3H]thymidine-labeling techniques, coupled with serial photography of precursor development in culture, showed that at all donor ages some of the isolated cells divided one or more times and became postmitotic in vitro. Analysis of cell phenotype by phase-contrast microscopy, sequential photography, autoradiography, and immunocytochemistry showed that the majority of precursors from all donor ages differentiated as photoreceptors. These observations support a prediction derived from the "photoreceptor default" hypothesis.

Animals↗
PubMed1992

Manifestations of pediatric AIDS: proposed mechanisms of transmission.

Pediatric Acquired Immunodeficiency Syndrome (AIDS) is expected to increase by greater than 75% by 1993. Most of these infants will become infected with the Human Immunodeficiency Virus (HIV) through the mother. It is unclear exactly how the virus is passed from mother to child. The nature of HIV infection is described in this paper, and several mechanisms relevant to its transfer are proposed.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Toxicosis in sheep following ingestion of natural gas condensate.

Thirty of 200 ewes died or were euthanatized during a 21-day period following a 1-day accidental exposure to natural gas condensate, a complex mixture of hydrocarbons obtained during collection of natural gas from wells. Despite access to potable well water, the poisoned ewes willingly consumed toxic doses of condensate that contaminated surface water. Eight animals died without premonitory signs; the remainder became ill over the course of a few days to 3 weeks. The principal cause of mortality was aspiration pneumonia, but myocardial degeneration and necrosis, renal tubular damage, gastritis, enteritis, and meningeal edema and hyperemia were also observed. Gas chromatographic analysis identified chemical traces of the hydrocarbons in the tissues, and "fingerprinting," the process of matching chromatographic tracings, provided forensic proof of the contamination source. Atomic absorption spectroscopy and cholinesterase analyses were performed to eliminate the possibility of toxicosis by heavy metal contaminants or other constituents. This appears to be the first reported incidence of natural gas condensate toxicity involving sheep or other ruminants. Although the available literature presents a suggestive pattern of clinical signs and pathologic lesions of petroleum product poisoning, diagnostic investigations should employ detailed analytic examination because each source of petroleum hydrocarbons contains unique sets of components that may produce different toxic effects.

Adipose Tissue↗
PubMed1992

Accurate determination of the time of cell birth using a sequential labeling technique with [3H]-thymidine and bromodeoxyuridine ("window labeling").

During tissue embryogenesis, precursor cells divide actively and eventually withdraw from the mitotic cycle before differentiation. Accurate information about the time of terminal mitosis ("birthdate") of precursors is of vital importance for studying relationships between cell proliferation and differentiation. Methods presently available for birthdate determination, based on "pulse" or "cumulative" labeling with either tritiated thymidine (3HT) or bromodeoxyuridine (BrDU) incorporated into DNA during the mitotic cycle, allow only the approximate timing of terminal mitosis. To overcome this limitation, we have developed a "window labeling" technique based on the sequential administration of 3HT and BrDU. Chick retinal precursor cell cultures were first exposed to 3HT and, after a specified time interval, also to BrDU. After 6 days the cultures were fixed and processed for BrDU immunocytochemistry and 3HT autoradiography. Three populations of cells could be easily identified: (a) unlabeled cells, representing post-mitotic cells before label exposure; (b) BrDU-labeled cells [either 3HT (+)/BrDU (+) or 3HT (-)/BrDU (+)], representing those that continue dividing after the addition of BrDU; and (c) "window-labeled" cells, 3HT (+)/BrDU (-), which are those undergoing their last round of DNA synthesis during the interval between 3HT and BrDU administration. Control experiments demonstrated that this method allows birthdate determinations with a resolution of hours or minutes and is essentially free of deleterious effects on precursor cell survival and differentiation.

Animals↗
PubMed1992

Childhood through the eyes of child psychiatrists and paediatricians.

Attitudes to childhood in general and towards one's own childhood in particular are compared in a survey of 152 Australian and New Zealand child psychiatric and paediatric trainees. Results confirm the findings of Enzer et al that paediatricians view childhood more positively than do child psychiatrists. Although there is a significant difference between the two groups on measures of their perceptions of the parenting they received with child psychiatrists rating their own parents as less caring than do paediatricians, there is no relationship between attitudes to childhood and perceptions of the parenting they received. Implications of these findings are examined, both in terms of motivation for choosing one or other specialty and for the working relationship between the two professions.

Adult↗
PubMed1992

New RPO.

Explore the source record for details and available documents.

Audiology↗
PubMed1991

Support services for pediatric trainees. A survey of training program directors.

We conducted a survey of pediatric training program directors (75% response rate) regarding program support services for house staff, directors' attitudes about stress in training, and program plans to ameliorate such stress. Support services included explicit measures to alleviate stress, policies that may minimize stress, evaluation of house staff performance, feedback regarding career concerns, and benefits (eg, medical insurance and child care). Most programs offered services to reduce stress from training, but few offered preventive services. Support policies were reported to be inadequate, especially in the areas of coverage for leaves of absence. Maternity leave represented most leaves of absences, as 10% of the female house staff and 11% of the male house staff members became parents. Program directors' terms were short, and only 30% perceived these roles to be their primary roles. Male directors believed that female house officers had a harder time adjusting to their programs. We suggest changes and present a simple way for program directors to evaluate their support services.

Attitude of Health Personnel↗
PubMed1991

Prevalence of HBsAg carriers in native and immigrant pregnant female populations in Israel and passive/active vaccination against HBV of newborns at risk.

Israel has no official prevention policy at present against perinatal and horizontal transmission of hepatitis B virus (HBV) infection in newborns and children at risk. The present study was designed to assess the prevalence of HBV carrier state in a population of 11,123 pregnant women at term. Among this population (mean age 29.7 +/- 5.9), 98 women (0.88%) were found to be asymptomatic HBsAg+ carriers, and 97% of these carriers were anti-HBe+. Evidence for HBV replication, as determined by serum HBV-DNA, was established in 6.6% of the HBsAg+/anti-HBe+ population. The HBsAg carrier rate was strongly influenced by religion, continent, and country of birth of the carrier mothers. The highest relative carrier rate was found among women of Moslem origin (4.3%), as compared to Jewish women (0.67%). Most carrier women were born in Israel (56.1%) to mothers who had emigrated from regions with intermediate or high endemicity of HBV, such as North Africa or the Middle East. In these groups, the HBsAg carrier rate ranged between 1.2 and 3.0%. Ninety-three percent of newborns receiving passive/active vaccination against HBV developed protective levels of anti-HBs. Finally, evidence for horizontal transmission of HBV was found in 19.3% of 83 non-vaccinated children in families of HBsAg carriers. The present study therefore establishes HBsAg prevalence rates in specific risk groups of women at term and confirms the need for an official policy on immunization against HBV in Israel. Since over 50% of women at term belong to the defined risk groups, universal active vaccination of the entire newborn population each year is suggested as the most rational and needed policy in Israel.

Adolescent↗
PubMed1991

Proteoglycan synthesis in cultures of murine retinal neurons and photoreceptors.

1. In recent years, a number of histochemical and immunocytochemical studies have suggested that proteoglycans, particularly those in the interphotoreceptor matrix, exhibit altered distributions in several murine models for retinal degenerations. We are using a cell culture system to characterize the proteoglycans synthesized by neurons and photoreceptors derived from mouse retina, with the long-term goal of analyzing their role in retinal degenerations. 2. In this study we describe initial studies using cells derived from the retinas of normal mice. Cultures of retinal neurons and photoreceptors, which were free of glial, epithelia, or endothelial cells, were labeled with 3H-glucosamine and 35SO4. Proteoglycans isolated from the medium and cell layer were analyzed on the basis of charge, relative hydrodynamic size, and glycosaminoglycan content. 3. The studies indicate that the cultures actively synthesize proteoglycans. The medium contained predominantly chondroitin sulfate/dermatan sulfate, while the cell layer had a higher proportion of heparan sulfate, indicating a differential distribution between the two compartments.

Animals↗
PubMed1991

Antenatal prediction of mother-infant difficulties.

A prospective study of 143 "low risk" pregnant women expecting their first baby was conducted in Newcastle, Australia. The study was designed to examine the contribution of a woman's perception of her own childhood experiences, her trait anxiety level, socioeconomic status, and social support network to difficulties in her relationship with her baby during the baby's first year. The women were initially interviewed during pregnancy and followed up 3 and 12 months postpartum. Follow-up measures included the Dimensions of Perinatal Adjustment, the Neonatal Perception Inventory, the Ainsworth Strange Situation, and information from hospital records, family doctors, and baby health centre sisters. Women who perceived their social network as less supportive during pregnancy were likely to see their one-year-old babies (p less than .05) as more difficult. The other antenatal measures were not significantly predictive of outcome.

Adolescent↗
PubMed1991

Dose-related immunogenicity of Haemophilus influenzae type b capsular polysaccharide-Neisseria meningitidis outer membrane protein conjugate vaccine.

We studied the immunologic responsiveness to Haemophilus influenzae type b capsular polysaccharide-Neisseria meningitidis group b outer membrane protein conjugate vaccine (PRP-NOMP) in children 2 to 42 months of age with vaccine dosages containing 7.5, 15, or 30 micrograms of PRP. Overall, PRP-NOMP was highly immunogenic. Geometric mean titers of anti-PRP antibody increased from 0.09 to 3.3 mg/L and 6.6 mg/L following each dose of vaccine, respectively, in the 2- to 18-month age group. Similarly, anti-PRP antibody geometric mean titers increased from 0.12 to 5.9 mg/L in the older than 18-month age group. However, we noted an apparent inverse relationship between vaccine dosages and immune responses following two doses of PRP-NOMP in 2- to 18-month-old children. Anti-PRP antibody geometric mean titers were 12.0, 6.9, and 3.5 mg/L, respectively, after the second dose of vaccine containing 7.5, 15, or 30 micrograms of PRP. Additional studies are needed to understand the mechanisms responsible for this inverse relationship and also to determine the optimal dosage of PRP-NOMP for young children.

Antibodies, Bacterial↗
PubMed1990

The effect of anti-alpha-fetoprotein-adriamycin conjugate on a human hepatoma.

Conjugates between chemotherapeutic agents and antibodies, linked by a dextran bridge, were previously shown to be effective in suppression of hepatoma growth in vitro and in vivo. However, scaling up of production of such conjugates may lead to a high degree of variation in molar ratios of drug to antibody in different batches. In this study, an alternative link between drug and antibody was evaluated. A conjugate between adriamycin and murine IgGI monoclonal antibodies to human alpha-fetoprotein was prepared using a polyglutamic-acid bridge. The simple and reproducible method of linking adriamycin to a specific site on the antibody enabled the binding of the drug to alpha-fetoprotein with a high yield (63% to 68%); the molar ratio of drug/antibody was in the range of 110:1 to 120:1. The conjugate retained its capacity to bind to purified alpha-fetoprotein. Incorporation of [3H]-thymidine or [3H]-leucine into hepatoma cells, which express alpha-fetoprotein, was inhibited by the conjugate, compared with unconjugated antibody. Furthermore, 90% of this pharmacological activity was preserved, compared with free adriamycin. In vitro, the inhibitory activity of the polyglutamic acid conjugate was higher than that of a conjugate in which dextran was used as the linker between drug and antibody. In vivo, both conjugates were equally effective in suppression of hepatoma growth transplanted subcutaneously in athymic mice. However, this effect lasted only during the treatment period of 2 to 3 wk. Six days after discontinuation of therapy, reacceleration of tumor growth was observed regardless of the conjugate used.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗