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Biomedical subjects

H Rosen

Publications and source records attributed to H Rosen.

At least 145 records · Page 8Linked to original sources
PubMed1990

Differential inactivation of Escherichia coli membrane dehydrogenases by a myeloperoxidase-mediated antimicrobial system.

Neutrophil myeloperoxidase, hydrogen peroxide, and chloride constitute a potent antimicrobial system with multiple effects on microbial cytoplasmic membranes. Among these is inhibition of succinate-dependent respiration mediated, principally, through inactivation of succinate dehydrogenase. Succinate-dependent respiration is inhibited at rates that correlate with loss of microbial viability, suggesting that loss of respiration might contribute to the microbicidal event. Because respiration in Escherichia coli can be mediated by dehydrogenases other than succinate dehydrogenase, the effects of the myeloperoxidase system on other membrane dehydrogenases were evaluated by histochemical activity stains of electrophoretically separated membrane proteins. Two bands of succinate dehydrogenase activity proved the most susceptible to inactivation with complete loss of staining activity within 20 min, under the conditions employed. A group with intermediate susceptibility, consisting of lactate, malate, glycerol-3-phosphate, and dihydroorotate dehydrogenases as well as three bands of glucose-6-phosphate dehydrogenase, was almost completely inactivated within 30 min. The relatively resistant group, including the dehydrogenases for glutamate, NADH, and NADPH and the remaining bands of glucose-6-phosphate dehydrogenase, retained substantial amounts of diaphorase activity for up to 60 min of incubation with the myeloperoxidase system. The differential effects of myeloperoxidase on dehydrogenase inactivation could not be correlated with published enzyme contents of flavin or iron-sulfur centers, potential targets of myeloperoxidase-derived oxidants. Despite the relative resistance of NADH dehydrogenase/diaphorase activity to myeloperoxidase-mediated inactivation, electron transport particles prepared from E. coli incubated for 20 min with the myeloperoxidase system lost 55% of their NADH oxidase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Membrane↗
PubMed1990

Adoptive transfer of fluorescence-labeled cells shows that resident peritoneal macrophages are able to migrate into specialized lymphoid organs and inflammatory sites in the mouse.

We have examined the migration of murine macrophages from the vascular compartment to normal and inflammatory tissues by the adoptive transfer of resident peritoneal macrophages (RPM phi) fluorescently labeled with the hydrophobic dye 1,1'-dioctadecyl 3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI). After initial labeling of the plasma membrane of RPM phi, the dye accumulated stably in intracellular vesicles of low density (rho = 1.042-1.045 kg/l) and cells remained viable in culture for 4 weeks. Like the normal monocyte, DiI-RPM phi, but not exudate-derived or fixed cells, migrated to peritoneal exudates, following i.v. adoptive transfer, by a mechanism inhibitable by an antibody to the type 3 complement receptor. In the absence of an inflammatory stimulus there was no migration to the peritoneal cavity, and DiI-RPM phi accumulated within 4 h in the red pulp and marginal zone of the spleen. By day 6 these cells still formed a tight ring of fluorescence in the marginal zone alone, outside the marginal metallophil cells. DiI-RPM phi injected into the peritoneal cavity migrated to the parathymic lymph nodes where they were found in the subcapsular sinus and in the medullary cords, whereas very few fluorescent cells could be found in the T cell areas. The migration of RPM phi to lymphoid organs required viable cells but, unlike the recruitment of cells to peritoneal exudates, was not inhibitable by antibodies to CR3. We conclude that the RPM phi is a useful surrogate for the analysis of constitutive and induced monocyte migration to secondary lymphoid and inflammatory sites, respectively.

Animals↗
PubMed1990

The leukocyte cell surface receptor(s) for the iC3b product of complement.

CR3 is probably the major adhesion molecule on monocytes and neutrophils. Its function as a phagocytic receptor for iC3b-coated particles has been well characterized. CR3 also has binding affinity for other ligands, including those that compete with iC3b such as fibrinogen, factor X, and beta-glucan, and those that do not such as bacterial LPS. CR3 binding to endothelial cells probably plays an important role in the extravascular migration of monocytes and neutrophils, but the ligand that it recognizes on endothelial cells has not been identified. Structurally CR3 belongs to the integrin family, and it shares a common subunit with p150,95 and LFA-1. The expression of these three membrane antigens appear to be limited to leukocytes, and they are sometimes referred to collectively as the leukocyte integrins. All three antigens have a common binding affinity for bacterial LPS. p150,95 also has affinity for iC3b, but p150,95/iC3b-dependent cellular responses has not been demonstrated. Its status as a complement receptor therefore awaits further experimental support.

Amino Acid Sequence↗
PubMed1990

Importance of the HpaI-P sequence for herpes simplex virus-1 replication in the adrenal glands.

The ability of several strains and recombinants of herpes simplex virus 1 (HSV-1) to proliferate in the adrenal glands and to invade the spinal cord was studied. After intraperitoneal infection, pathogenic HSV-1 strains replicated in the adrenal glands, penetrated the spinal cord and migrated to the brain. The nonpathogenic strain HFEM could not replicate in the adrenal glands, but the recombinant virus MLC1 was able to do so after rescue by reinsertion of the HpaI-P sequence into the BamHI fragment of HFEM DNA. However the recombinant MLC1 virus could not penetrate the spinal cord. The effect of HSV-1 infection on the expression of the cellular genes for multidrug resistance (in the adrenal glands) and proenkephalin A (in the spinal cord) was also studied.

Adrenal Glands↗
PubMed1990

Loss of DNA-membrane interactions and cessation of DNA synthesis in myeloperoxidase-treated Escherichia coli.

Neutrophils and monocytes employ a diverse array of antimicrobial effector systems to support their host defense functions. The mechanisms of action of most of these systems are incompletely understood. The present report indicates that microbicidal activity by a neutrophil-derived antimicrobial system, consisting of myeloperoxidase, enzymatically generated hydrogen peroxide, and chloride ion, is accompanied by prompt cessation of DNA synthesis in Escherichia coli, as determined by markedly reduced incorporation of [3H]thymidine into trichloracetic acid-precipitable material. Simultaneously, the myeloperoxidase system mediates a decline in the ability of E. coli membranes to bind hemimethylated DNA sequences containing the E. coli chromosomal origin of replication (oriC). Binding of oriC to the E. coli membrane is an essential element of orderly chromosomal DNA replication. Comparable early changes in DNA synthesis and DNA-membrane interactions were not observed with alternative oxidant or antibiotic-mediated microbicidal systems. It is proposed that oxidants generated by the myeloperoxidase system modify the E. coli membrane in such a fashion that oriC binding is markedly impaired. As a consequence chromosomal DNA replication is impaired and organisms can no longer replicate.

Cell Membrane↗
PubMed1990

Regulated expression of proenkephalin A during ontogenic development of mesenchymal derivative tissues.

Proenkephalin A (PEA), a neuropeptide-encoding gene, is widely expressed in the nervous and endocrine systems. Recently, we demonstrated that in addition to its abundance in fetal brain tissue; PEA is markedly expressed in nondifferentiated mesodermal cells of developing fetuses. To evaluate the implication of these findings for the normal development of tissues of mesodermal origin, we examined the expression of PEA in rat mesenchymal tissues during pre- and postnatal development. Using in situ hybridization analysis combined with RNA blots and a Met-enkephalin-specific radioimmunoassay, we showed that (i) PEA mRNA levels in embryonic and newborn mesenchymal derivative tissues were as high as in the developing brain, (ii) PEA mRNA concentrations in these tissues dropped to undetectable levels shortly after birth, and (iii) this mRNA was translated and processed differentially among different mesenchymal tissues, yielding a tissue-specific pattern of PEA-derived peptides. Our results demonstrate multilevel regulation of PEA gene expression during ontogenic development of mesenchymal derivative tissues. The transient expression and the correlation between PEA mRNA and tissue maturation support the notion that peptides encoded by PEA play a significant role in normal development of these tissues. These findings provide a framework for examination of the mechanisms and roles of PEA gene expression during mesenchymal ontogeny.

Aging↗
PubMed1990

The role of the type 3 complement receptor in the induced recruitment of myelomonocytic cells to inflammatory sites in the mouse.

The type 3 complement receptor (CR3), initially identified as the leukocyte cell surface receptor for iC3b, is now known to form part of the extended integrin family of cell adhesion molecules that mediate both cell-cell and cell-extracellular matrix interactions. The identification of a heritable deficiency of human leukocyte adhesion together with the advent of monoclonal antibodies has shed some light on the central role of CR3 in the transendothelial migration of macrophages and neutrophils to sites of inflammation. We review the general structural features of CR3 and then examine our understanding of its role in both nonspecific and T cell-dependent inflammatory processes based on our murine in vivo experiments. CR3-dependent inflammation seems to contribute to the pulmonary response to some stimuli (lipopolysaccharide) but not to others (bacillus Calmette-Guerin). These studies highlight the potential therapeutic benefits, as well as the significant risks of potentiating acute bacterial infections, of CR3 blockade in vivo.

Animals↗
PubMed1990

Local regulation within the female reproductive system and upon embryonic implantation: identification of cells expressing proenkephalin A.

The detection of proenkephalin A (PEA) mRNA and encoded peptides in various regions of the female reproductive system raised the possibility that opioid peptides might act as local regulators within this system. Assignment of a specific role for locally synthesized enkephalins has been hampered, however, by the unknown identity of the cells that produce PEA. Using in situ hybridization analysis we have now identified the cell types that express PEA mRNA in the reproductive system of female mice. In the ovary, PEA mRNA was localized primarily in theca cells of preovulatory follicles, and to a lesser extent, in follicular granulosa cells. In the oviducts, where PEA mRNA is most abundant, expression was confined to the secretory and ciliated epithelium of the mucosa. In the uterus, the site of PEA mRNA expression was the deep glandular layer of the endometrium. When pregnancy ensues, and upon decidual transformation, PEA expression by the same uterine cells was dramatically elevated. Elevated levels of PEA mRNA were detected predominantly in the vicinity of the implantation site, suggesting that signaling by the implanted embryo play a role in stimulating PEA expression. Based on these results, possible physiological roles for PEA-encoded peptides as autocrine/paracrine regulators within the female reproductive system are suggested.

Animals↗
PubMed1990

The treatment of nonunions and pseudarthroses of the humeral shaft.

In summary, if one follows the AO/ASIF principles of open reduction and stable internal fixation of nonunions and pseudarthroses of the humerus, mostly with plate fixation supplemented by shingling or petaling, cement for loose screws when necessary, and bone grafting of defects or atrophic nonunions, then successful healing with one operative procedure can be achieved in over 95%, with almost full correction of preoperative deformity. Return of useful function and range of motion can also be achieved in 75% to 90% by early active exercises, physiotherapy, and occasional continuous passive motion, supported by hinged braces or cast braces in the postoperative period until union occurs. Union was achieved in an average of 6.6 months after the operative procedure.

Adult↗
PubMed1990

Chairside repair of ceramo-metallic restorations.

The ceramo-metallic crown has enjoyed increasing universal popularity as the full-coverage restoration of choice where long-term esthetics is desirable. The porcelain veneer is colour stable and relatively wear resistant. It has excellent compressive strength but poor tensile and shear strength, which unfortunately can result in fracture. Consequently, there is a need for chairside repair, since remake is often contraindicated. Commercially available repair systems are inconsistent and unpredictable and provide, at best, only temporary results despite recent improvements in materials and technique. Two new adhesive composite resins appear promising, although long-term clinical studies are not available. This article deals first with prevention and a review of the literature. Secondly, clinically proven methods of providing mechanical retention for resin and composite resin repairs of fractured porcelain are presented. The combination of mechanical retention and recently developed adhesive composite resins should provide the dentist with a reliable chairside repair system that could last for many years.

Composite Resins↗
PubMed1989

Regulated expression of proenkephalin A in normal lymphocytes.

The expression of proenkephalin A (PEA), a neuropeptide-encoding gene, was examined in normal rat lymphocytes. With the use of Northern blot hybridization analysis of total RNA, PEA mRNA was found in normal cells derived from spleen, lymph nodes, and bone marrow. Cell sorting of the two main fractions of B and T cells derived from the spleen revealed that PEA is expressed in normal B cells (sIg+). The expression of PEA mRNA was markedly enhanced after a short incubation (3 h) of cells with LPS or Salmonella typhimurium. This was not the case when these cells were incubated with Con A during the same period of time; whereas, in thymocytes the presence of PEA mRNA was exclusively dependent upon mitogenic stimulus (Con A) and could be detected after 24 h of in vitro incubation. Extracts of cells were also found to contain immune reactive enkephalins, indicating that the PEA mRNA is translated. These results support the concept that neuropeptides, such as enkephalins, have a role in the modulation of the immune response and may participate in the bidirectional communication between the nervous and immune systems.

Animals↗
PubMed1989

Oxygen-based free radical generation by ferrous ions and deferoxamine.

Deferoxamine accelerates the autooxidation of iron as measured by the rapid disappearance of Fe2+, the associated appearance of Fe3+, and the uptake of oxygen. Protons are released in the reaction. The formation of H2O2 was detected by the horseradish peroxidase-catalyzed oxidation of scopoletin, and the formation of hydroxyl radicals (OH.) was suggested by the formation of the OH. spin trap adduct (DMPO/OH). with the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and the generation of the methyl radical adduct on the further addition of dimethyl sulfoxide. (DMPO/OH). adduct formation was inhibited by catalase but not by superoxide dismutase. The oxidant formed converted iodide to a trichloroacetic acid-precipitable form (iodination) and was bactericidal to logarithmic phase Escherichia coli. Both iodination and bactericidal activity was inhibited by catalase and by OH. scavengers, but not by superoxide dismutase. Iodination was optimal in 5 x 10(-4) M acetate buffer, pH 5.0, and when the Fe2+ and deferoxamine concentrations were equimolar at 10(-4) M. Fe2+ could not be replaced by Fe3+, Co2+, Zn2+, Ca2+, Mg2+, or Mn2+, or deferoxamine by EDTA, diethylenetriaminepentaacetic acid, or bathophenanthroline. These findings indicate that Fe2+ and deferoxamine can act as an oxygen radical generating system, which may contribute to its biological effects in vitro and in vivo.

Catalase↗
PubMed1989

Increase in hypothalamic pro-opiomelanocortin gene expression in response to prolonged low level lead exposure.

Lead, an environmental pollutant, has been long recognized as a neurotoxic agent. Several reports have recently described behavioral disturbances caused by low level lead exposure. Lead-induced changes in neurotransmitter metabolism in the brain may help to elucidate the molecular basis for the observed behavioral alterations. In this study, the influence of low level lead exposure on the hypothalamic expression of rat opioid genes was examined. Determination of relative opioid mRNA levels revealed a dramatic increase of pro-opiomelanocortin (POMC) mRNA concentrations in response to lead. This increase was found to be specific, developmentally regulated, reversible and dependent on prolonged lead exposure. These findings may provide substantial evidence for the possible connections between early environmental inputs and the expression of neuropeptide genes in the brain.

Animals↗
PubMed1989

Exacerbation of murine listeriosis by a monoclonal antibody specific for the type 3 complement receptor of myelomonocytic cells. Absence of monocytes at infective foci allows Listeria to multiply in nonphagocytic cells.

Treatment of mice with a rat mAb (5C6) specific for an epitope of the type 3 complement receptor of myelomonocytic cells severely interfered with the ability of the mice to resist infection with Listeria monocytogenes. Consequently, a sublethal infection was rapidly converted to a lethal one that resulted in death in 5 d. However, infection was only exacerbated if 5C6 was given earlier in infection, before mononuclear phagocytes populated sites of Listeria implantation in the liver and spleen. If given after day 3 of infection, 5C6 caused only a temporary increase in bacterial multiplication. The infection-enhancing effect of 5C6 was associated with failure of mice to focus mononuclear phagocytes at sites of bacterial multiplication of Listeria in liver hepatocytes and extracellulary in the spleen. This resulted in unrestricted multiplication of Listeria in hepatocytes and extracellularly in the spleen. The results are in keeping with the ability of 5C6 to inhibit the accumulation of myelomonocytic cells in peritoneal inflammatory exudates, as revealed by a previous study.

Animals↗
PubMed1989

Myeloperoxidase-mediated inhibition of microbial respiration: damage to Escherichia coli ubiquinol oxidase.

A microbicidal system, mediated by neutrophil myeloperoxidase, inhibits succinate-dependent respiration in Escherichia coli at rates that correlate with loss of microbial viability. Succinate dehydrogenase, the initial enzyme of the succinate oxidase respiratory pathway, catalyzes the reduction of ubiquinone to ubiquinol, which is reoxidized by terminal oxidase complexes. The steady-state ratio of ubiquinol to total quinone (ubiquinol + ubiquinone) reflects the balance between dehydrogenase-dependent ubiquinone reduction and terminal oxidase-dependent ubiquinol oxidation. Myeloperoxidase had no effect on total quinone content of E. coli but altered the steady-state ratio of ubiquinol to total quinone. The ratio doubled for organisms incubated with the myeloperoxidase system for 10 min, suggesting decreased ubiquinol oxidase activity, which was confirmed by observation of a 50% decrease in oxidation of the ubiquinol analogue 2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinol. Despite inhibition of ubiquinol oxidase, overall succinate oxidase activity remained unchanged, suggesting that succinate dehydrogenase activity was preserved and that the dehydrogenase was rate limiting. Microbial viability was unaffected by early changes in ubiquinol oxidase activity. Longer (60 min) exposure of E. coli to the myeloperoxidase system resulted in only modest further inhibition of the ubiquinol oxidase, but the ubiquinol to total quinone ratio fell to 0%, reflecting complete loss of succinate dehydrogenase activity. Succinate oxidase activity was abolished, and there was extensive loss of microbial viability. Early myeloperoxidase-mediated injury to ubiquinol oxidase appeared to be compensated for by higher steady-state levels of ubiquinol which sustained electron turnover by mass effect. Later myeloperoxidase-mediated injuries eliminated succinate-dependent ubiquinone reduction, through inhibition of succinate dehydrogenase, with loss of succinate oxidase activity, effects which were associated with, although not clearly causal for, microbicidal activity.

Animals↗
PubMed1989

Postnatal expression of opioid genes in rat brain.

Developmentally regulated expression of opioid genes in rat brain was studied by Northern blot hybridization, using cloned rat genes as probes. Total RNA was isolated from the rat medulla oblongata, hypothalamus and striatum at 11 stages of development from birth to postnatal day 28. The steady-state levels of opioid precursor mRNAs in the above tissues were determined by hybridization to 32P-labeled opioid DNA probes and densitometric scanning of the appropriate bands. Analysis of the relative steady-state concentrations of opioid mRNAs has shown that the tissue distribution and size of these mRNAs during postnatal development of the CNS are similar to the pattern described in the adult. However, up to 50-fold changes in the relative mRNA concentrations were observed. These changes are tissue-specific, characterized by a peak within the postnatal stage of development, and are followed by a build-up of mRNA levels characteristic of the adult. Moreover, comparison of the changes in mRNA levels of proenkephalin to those of prodynorphin at their main site of synthesis in the brain, namely the striatum, revealed striking similarities in pattern. The association of this phenomenon with a possible role of opioid genes in development is suggested.

Aging↗
PubMed1989

Antibody to the murine type 3 complement receptor inhibits T lymphocyte-dependent recruitment of myelomonocytic cells in vivo.

We have used the delayed-type hypersensitivity (DTH) response to SRBC or tuberculin to examine the role of the murine type 3 complement receptor in T lymphocyte-dependent inflammatory recruitment. Intravenous injection of 5C6, a CR3-specific rat mAb known to impair myelomonocytic adhesion, divided the DTH to SRBC in actively immunized mice into two phases. The early phase, which lasted 24 h, was characterized by maximal oedema and maximal inflammatory recruitment and was 5C6 inhibitable. The later phase was 5C6 resistant and reached a peak 48 h after antigenic challenge and was superimposable on the declining peak seen in control mice. Passive transfer of reactive T cells mixed with antigen was used to examine the myelomonocytic effector arm of the DTH alone. Both passive transfer of cutaneous DTH to SRBC and passive transfer of the largely monocytic T cell-dependent recruitment to tuberculin in the peritoneal cavity were completely abolished by systemic 5C6 treatment. Injection of 5C6-treated donor leukocytes at the site of passive transfer had no effect. Treatment of donor mice with 5C6 at the time of active immunization did not alter their ability to provide reactive T cells for passive transfer. The myelomonocyte-restricted rat mAb 7/4 and the rapidly cleared F(ab')2 fragment of 5C6 showed no inhibition of the DTH. In all cases, inhibition of footpad swelling correlated with histological evidence of inhibition of myelomonocytic cell recruitment. Peritoneal cell counts after local DTH to tuberculin showed complete inhibition of monocyte recruitment. We conclude that CR3 plays a quantitatively important role in T cell-dependent inflammatory recruitment. This is absolute in passive transfer experiments, but only partial after active immunization. Leukocyte CR3 plays a common role in both immunologically specific and nonspecific inflammatory recruitment and provides a target that could possibly be manipulated to therapeutic advantage.

Animals↗