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H Bernstein

Publications and source records attributed to H Bernstein.

At least 19 recordsLinked to original sources
PubMed1997

Sexual communication.

Sexual communication refers to the use of signals to promote or modulate sexual interaction. We suggest that these signals operate at three levels: (a) a primary level at which signals are used to increase the likelihood of sexual interaction between two individuals; (b) a secondary level at which signals inhibit inbreeding or facilitate outbreeding; and (c) a tertiary level at which signals allow selection among potential mates. Evidence is cited that the selective advantage of the primary, secondary and tertiary levels are, respectively, repair of DNA damage, masking of mutation, and selection for fitness in the mating partner. We illustrate how these advantageous processes are facilitated by sexual communication in bacteria, fungi, protozoa, insects, plants and vertebrates.

Adaptation, Physiological↗
PubMed1997

Effects of metal salts on poly(DL-lactide-co-glycolide) polymer hydrolysis.

The effects of encapsulated metal salts on poly(DL-lactide-co-glycolide) (PLGA) water uptake and degradation properties were investigated in this work. Salts of varying aqueous solubility characteristics were incorporated into PLGA films either as particles or by codissolution in polymer solutions. Polymer films were characterized with respect to the kinetics of water uptake, morphology changes, degradation, and weight loss after hydration. It was found that these properties are strongly influenced by the presence and nature of encapsulated salts. Effects range from minor changes in water uptake profile with no significant difference in degradation kinetics to major alterations in water uptake kinetics together with a several-fold decrease in the polymer degradation rate. Possible mechanistic explanations for the observed effects are discussed.

Biocompatible Materials↗
PubMed1996

Primordial emergence of the recombination activating gene 1 (RAG1): sequence of the complete shark gene indicates homology to microbial integrases.

The rearrangement of antibody and T-cell receptor gene segments is indispensable to the vertebrate immune response. All extant jawed vertebrates can rearrange these gene segments. This ability is conferred by the recombination activating genes I and II (RAG I and RAG II). To elucidate their origin and function, the cDNA encoding RAG I from a member of the most ancient class of extant gnathostomes, the Carcharhine sharks, was characterized. Homology domains identified within shark RAG I prompted sequence comparison analyses that suggested similarity of the RAG I and II genes, respectively, to the integrase family genes and integration host factor genes of the bacterial site-specific recombination system. Thus, the apparent explosive evolution (or "big bang") of the ancestral immune system may have been initiated by a transfer of microbial site-specific recombinases.

Amino Acid Sequence↗
PubMed1996

Reduced bile acid-induced apoptosis in "normal" colorectal mucosa: a potential biological marker for cancer risk.

Dietary factors, including bile acids, are important in the causation of colorectal cancer (CRC). We have previously shown that in vitro exposure of colorectal mucosal biopsies to low concentrations of bile acids produces apoptosis selectively in goblet cells. Apoptosis is an important mechanism for clearing DNA-damaged cells. Inhibition of apoptosis would result in increasing accumulation of DNA-damaged cells, resulting in increased cancer risk. We compared the percentage of apoptosis induced by bile acids in mucosal biopsies from CRC patients with that of noncancer subjects. Mucosal biopsies from 15 to 20 cm from the anal verge were incubated in 1 mM sodium deoxycholate, and the percentage of goblet cells undergoing apoptosis was quantitated. Seven patients with a history of CRC within the previous 5 years were compared with 18 noncancer subjects [4 neoplasia free and 14 with small (< or = 9 mm) polyps only]. The CRC patients had a significantly lower percentage of apoptosis than noncancer subjects; the mean for CRC was 10.7% (range, 0.9-26%) and for noncancer subjects was 55.9% (range, 20.3-71%; P < or = 0.001). Two other noncancer patients had very high-risk lesions, i.e., large villous adenomas and multiple large polyps during several colonoscopies over the previous 6 years. Their percentage of apoptosis was in the cancer range, i.e., 6.2 and 10.7%. Reduced apoptotic ability may imply increased cancer risk. By applying a quantitative bile acid-induced apoptosis assay to colorectal mucosal biopsies, the percentage of apoptosis was found to be significantly reduced in CRC patients. This assay may prove to be a useful intermediate biological marker for identifying subjects at increased risk of cancer.

Aged↗
PubMed1995

Safety and cellular and humoral immune responses of a booster dose of varicella vaccine 6 years after primary immunization.

Four hundred nineteen children and adolescents immunized with live varicella vaccine 4-6 years earlier were enrolled in a study to evaluate the safety and immune response to a booster dose containing approximately 3300 pfu of virus. Of the subjects, 99% (414/419) maintained antibody to varicella zoster virus (VZV) with a geometric mean titer of 25.7 and mean stimulation index (SI) for VZV-specific lymphoproliferation response of 40.3 +/- 5.3 (SE). Some 7-10 days after the booster immunization, seropositivity rates increased to 100% (302/302), and GMT was 143.6 (anamnestic response). At 6 weeks after the booster inoculation, a subset of subjects had 100% seropositivity (74/74) with a GMT of 218.8 and an SI of 58.6. After 3 months, seropositivity was 100% (358/358), GMT was 119.0, and SI was 61.4.

Adolescent↗
PubMed1995

Apoptosis overview emphasizing the role of oxidative stress, DNA damage and signal-transduction pathways.

Apoptosis (programmed cell death) is a central protective response to excess oxidative damage (especially DNA damage), and is also essential to embryogenesis, morphogenesis and normal immune function. An understanding of the cellular events leading to apoptosis is important for the design of new chemotherapeutic agents directed against the types of leukemias and lymphomas that are resistant to currently used chemotherapeutic protocols. We present here a review of the characteristic features of apoptosis, the cell types and situations in which it occurs, the types of oxidative stress that induce apoptosis, the signal-transduction pathways that either induce or prevent apoptosis, the biologic significance of apoptosis, the role of apoptosis in cancer, and an evaluation of the methodologies used to identify apoptotic cells. Two accompanying articles, demonstrating classic apoptosis and non-classic apoptosis in the same Epstein-Barr virus-transformed lymphoid cell line, are used to illustrate the value of employing multiple criteria to determine the type of cell death occurring in a given experimental system. Aspects of apoptosis and programmed cell death that are not covered in this review include histochemistry, details of cell deletion processes in the sculpting of tissues and organs in embryogenesis and morphogenesis, and the specific pathways leading to apoptosis in specific cell types. The readers should refer to the excellent books and reviews on the morphology, biochemistry and molecular biology of apoptosis already published on these topics. Emphasis is placed, in this review, on a proposed common pathway of apoptosis that may be relevant to all cell types.

Animals↗
PubMed1995

Evaluation of cell death in EBV-transformed lymphocytes using agarose gel electrophoresis, light microscopy and electron microscopy. I. Induction of classic apoptosis by the bile salt, sodium deoxycholate.

In this study, we examined the effect of different concentrations of sodium deoxycholate (NaDOC), a secondary bile salt, on an Epstein-Barr virus transformed human lymphoid cell line (NC-37). We found that NaDOC induces classic apoptosis in a dose-dependent manner at 0.1-0.4 mM doses, and necrosis at much higher concentrations (0.8-3.1 mM). This is the first demonstration that a bile salt can induce apoptosis in any cell type. The mode of cell death was determined using morphologic methods (light and electron microscopy) as the gold standard. Standard agarose gel electrophoretic techniques were applied to identify the "ladder" of DNA fragments that have been associated with apoptosis in certain cell types. Although DNA fragmentation was observed during the apoptotic death of NC-37 cells, we were not able to identify a "ladder" pattern of fragmentation. Two other types of cells, however, that previously have been reported to display a characteristic "ladder" pattern of DNA fragmentation, glucocorticoid-treated WEHI7.2 cells and isolated human neutrophils, did display the "ladder" pattern. This study emphasizes the need to examine morphology when identifying the mode of cell death induced by a new agent.

Apoptosis↗
PubMed1994

Calmodulin antagonists inhibit human immunodeficiency virus-induced cell fusion but not virus replication.

We have reported that amphipathic helical segments in the cytoplasmic domain of the HIV-1 envelope glycoproteins bind to calmodulin (CaM) with high affinity, and inhibit calmodulin-regulated proteins. To investigate the possible role of calmodulin activity in HIV-1 replication, we investigated the anti-HIV activity of various CaM antagonists--trifluoperazine and naphthalenesulfonamide W13 or W7--in HeLa T4 cells, PBMCs, and various T lymphocytic cell lines. The different CaM antagonists were found to inhibit the proliferation of the different cell types to varying extent. Also, the CaM antagonists were found to exert a greater antiproliferative effect on H9/HIV-1IIIB, as compared to uninfected H9 cells, suggesting a deficit of CaM function in HIV-infected cells. The CaM antagonists inhibited virus-induced cell fusion in HeLa T4 cells infected with a recombinant vaccinia virus expressing HIV-1 envelope proteins at threshold concentrations that do not inhibit cell proliferation. The fusion-inhibitory effects of the CaM antagonists were also observed in cocultures of HIV-infected (H9/HIV-1IIIB) and uninfected H9 cells. Under these conditions, the synthesis and surface expression of the viral glycoproteins were not affected, although the kinetics of processing of HIV envelope precursor was delayed. Virus production from both HIV-infected peripheral blood mononuclear cell (PBMC) and MT-2 cell cultures was inhibited by CaM antagonists at concentrations that were inhibitory to cell proliferation. Surprisingly, threshold concentrations of CaM antagonists that do not inhibit cell proliferation were found to enhance virus production from HIV-infected MT-2 cells, but not PBMCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Calmodulin↗
PubMed1994

Dental implants.

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Dental Implants↗
PubMed1993

Kinetics of immobilized heparinase in human blood.

Immobilized enzyme reactors can form the basis of useful blood detoxification systems. One such reactor was developed for heparin neutralization by immobilized heparinase. In this article, reactor kinetics were studied under clinically relevant conditions. Heparin neutralization was assessed in vitro in whole human blood using (a) a well-mixed batch reactor, and (b) an oscillating, continuous-flow reactor. The kinetics of heparin neutralization in human blood were first order over the entire range of heparin and enzyme concentrations and particle fractions tested. The kinetic rate was not sensitive to physiological variations in the concentration of antithrombin, a heparin binding protein in blood. Enzyme activity did not decrease significantly over the 2 hour test period. Kinetic control of the system with minimal intraparticle diffusional limitations was suggested by the Thiele moduli (0.11-0.67) and effectiveness factors (0.98 +/- 0.01). The ratio kcat/Km obtained in batch studies was 0.0028 +/- 0.0008 cm3/microgram-min. A continuous-flow oscillating reactor within a closed recirculation loop performed as a single well mixed batch reactor; there was a short mixing time of recirculating blood when compared to reaction time. A model based on this mixing pattern and the kinetics obtained in independent batch studies accurately predicted heparin neutralization profiles observed in the continuous-flow system.

Antithrombins↗
PubMed1993

Successful epidural anaesthesia for a patient with Takayasu's arteritis presenting for caesarean section.

The management of a 24-yr-old parturient with Takayasu's arteritis (TA) presenting at term for Caesarean section is discussed. The best anaesthetic management for the patient with TA is controversial, but avoiding regional anaesthesia has been suggested by some authors because of the risk of hypotension and the subsequent need for vasopressors. We report the use of regional anaesthesia in a term parturient with severe TA undergoing Caesarean section. Anaesthesia was provided with chloroprocaine 3%, via a lumbar epidural catheter. The initial doses of 60 mg and 150 mg were followed by a decrease in BP (from 110/70 to 70/40) which was corrected with iv fluids and ephedrine 25 mg. Additional doses of chloroprocaine, 150 and 90 mg, were uneventful. It is concluded that an epidural can be made in safety to provide anaesthesia for Caesarean section in patients with TA.

Adult↗
PubMed1992

Oxidative and other DNA damages as the basis of aging: a review.

DNA damages occur continuously in cells of living organisms. While most of these damages are repaired, some accumulate. In particular, there is evidence for DNA damage accumulation in non-dividing cells of mammals. These accumulated DNA damages probably interfere with RNA transcription. We consider that the decline in the ability of DNA to serve as a template for gene expression is the primary cause of aging. Oxidative DNA damages are among the best documented and prevalent DNA damages and are likely to be a prominent cause of aging.

Aging↗
PubMed1991

The pharmacokinetics of, and humoral responses to, antigen delivered by microencapsulated liposomes.

The feasibility of creating a s.c. depot for sustained protein delivery with the goal of enhancing antigen immunogenicity was investigated. The depot was designed as antigen-laden liposomes of hydrogenated egg phosphatidylcholine and cholesterol (1:1 molar ratio) encapsulated in alginate-poly(L-lysine) microcapsules and evaluated using iodinated bovine serum albumin (BSA) as a model antigen. The in vivo release behavior of the liposomes and microencapsulated liposomes (MELs) was evaluated from the BSA serum concentration profiles after s.c. injection into rats and the pharmacokinetic parameters of 125I-labeled BSA appearance after s.c. or i.v. injections of BSA in saline. Maximal BSA concentrations were detected 11 h after s.c. injection in all rats. The BSA serum concentrations decreased rapidly in rats injected with BSA in saline or Freund's adjuvant and less rapidly in rats injected with BSA in liposomes or MELs. Four to 5 weeks after injection, BSA-associated radioactivity was detected only in sera of rats injected with BSA in liposomes or MELs. Fifty days after injection, 50% of the originally injected BSA was recovered form the s.c. sites of rats injected with BSA in MELs; no radioactivity was recovered from the other three groups of rats. The antigen-reactive antibody levels induced in rats immunized with BSA in MELs were 2- to 3-fold higher than those obtained in rats immunized with BSA in liposomes, saline, or Freund's adjuvant. More significantly, high antibody levels were maintained for more than 150 days after a single injection of BSA in MELs, suggesting that MELs can serve as a long-term single-dose immunization vehicle.

Animals↗
PubMed1990

Modification of DNA by bile acids: a possible factor in the etiology of colon cancer.

Bile acids have been implicated as promoters and cocarcinogens in the etiology of colon cancer and as comutagens and mutagens in bacteria. These observations suggest the hypothesis that bile acids may interact directly with DNA. We treated the single stranded circular DNA of phage M13 with bile acids and found that the transfection efficiency of this DNA declined up to a 1000-fold. This result suggests that bile acids can damage DNA and thus may play an important role in the etiology of colon cancer.

Bile Acids and Salts↗
PubMed1990

Colon cancer and dietary fiber: cellulose inhibits the DNA-damaging ability of bile acids.

Colon cancer is the second most common type of cancer in the United States. Bile acids have been implicated in the etiology of this disease. In a previous study, we showed that bile acids can damage DNA in vitro. In this study, we report that this damage is largely prevented when the bile acids are pretreated with cellulose fiber. Preliminary data show that cellulose may act as a catalyst to promote polyesterification of bile acid to a biologically inactive form.

Cellulose↗
PubMed1989

Chronic pruritic eruption in patients with acquired immunodeficiency syndrome associated with increased antibody titers to mosquito salivary gland antigens.

Five of seven patients with acquired immunodeficiency syndrome (AIDS) who had pruritus and a chronic, nonspecific-appearing skin eruption had increased antibody titers to antigens in the salivary glands of Aedes taeniorhynchus, a salt marsh mosquito common to South Florida. We hypothesize that the pruritus and skin lesions in patients with AIDS represent a form of chronic "recall" reaction. Increased antibody titers to mosquito salivary gland antigens may be a consequence of nonspecific B cell activation, a feature of AIDS.

Acquired Immunodeficiency Syndrome↗