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Biomedical subjects

E Johnson

Publications and source records attributed to E Johnson.

At least 19 recordsLinked to original sources
PubMed1992

Ultrastructure of spared dopamine terminals in caudate-putamen nuclei of adult rats neonatally treated with intranigral 6-hydroxydopamine.

Residual dopamine terminals in the dorsal striatum, caudate-putamen nuclei (CPN), of adult rats neonatally lesioned with 6-hydroxydopamine (6-OHDA) sustain a relatively high level of dopamine release. We examined whether there were morphological differences in the spared dopamine terminals that might correlate with this increased efficacy. Postnatal male rat pups from 50 litters were pretreated with desmethylimipramine (DMI) to protect from non-specific monoamine damage, then given unilateral intranigral injections of 6-OHDA or vehicle. Coronal sections through the CPN and substantia nigra of the surviving adult animals from each litter were co-processed for immunoautoradiographic or immunoperoxidase localization of the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH). Quantitative ultrastructural analysis established that in animals showing maximal (greater than 90%) depletions in immunoautoradiographic labeling for TH, the number of TH-labeled axons in the CPN ipsilateral to the 6-OHDA injections was reduced to one third of the number seen in the contralateral, unlesioned hemisphere, or the CPN from vehicle-injected animals. The ultrastructural features of residual terminals ipsilateral to 6-OHDA lesions were morphologically similar to those of the contralateral side or in vehicle-injected animals. However, in comparison with controls, these TH-labeled terminals had significantly larger mean cross-sectional diameters. When subdivided into groups according to size, there were significantly fewer small (0.0-0.1 micron 2) and more large (0.41-0.50 micron 2) TH-immunoreactive profiles in lesioned versus unlesioned CPN. The remaining TH-labeled terminals ipsilateral to the 6-OHDA lesions also appeared to be more often in direct contact with unlabeled soma and proximal dendrites as opposed to dendritic spines in the unlesioned CPN. These results suggest that the enhanced activity of dopamine neurons innervating the CPN after nigral 6-OHDA lesions may contribute to changes in size and target of their terminals. Alternatively, the observed large size of remaining dopamine terminals may reflect selective vulnerability of smaller axons to 6-OHDA toxicity.

Aging↗
PubMed1992

An isoform of protein disulfide isomerase isolated from chronic myelogenous leukemia cells alters complex formation between nuclear proteins and regulatory regions of interferon-inducible genes.

We have previously shown that the electrophoretic mobility of complexes formed in vitro between nuclear proteins and the regulatory domains of interferon-inducible genes is altered by an extranuclear protein present in elevated levels in the myeloid cells of chronic myelogenous leukemia patients. Interferon-alpha reduces the level of this activity only in the cells of patients who are clinically sensitive to the antiproliferative effects of interferon-alpha. We have purified this protein to homogeneity and found it to be a 57-kDa protein which corresponds to an isoform of protein disulfide isomerase. Protein disulfide isomerase is an oxidoreductase which catalyzes the interconversion between the reduced and oxidized states of proteins which contain multiple sulfhydryl groups and disulfide bonds. These studies suggest that this protein may play an important role in the transcriptional activation of interferon-inducible genes, perhaps through redox mechanisms.

Base Sequence↗
PubMed1992

[Pathogenetic aspects of sarcoidosis. Importance of local complement synthesis in alveolar macrophages].

Sarcoidosis is a multisystem granulomatous disorder of unknown etiology. Markers of activity include elevated serum ACE levels, interleukin 2-receptors, hypercalcemia, hypercalciuria, intrathoracic uptake of radioactive gallium, retinal vascular leakage, and an increased T4/T8 ratio in bronchoalveolar lavage fluid. The three main pathological features of sarcoidosis are alveolitis, granuloma formation and fibrosis. The cells harvested by bronchoalveolar lavage in sarcoidosis are representative of the local inflammatory reaction seen in the lung. Alveolar macrophages have the potential to synthesize the components of the functional alternative and terminal pathways of complement. The alveolar macrophages from sarcoidosis patients produce more complement than their healthy counterparts. Complement participates in the normal metabolism of immune complexes and has the ability to modulate immune responses via complement receptors present on virtually all cell types. On the other hand, through enhanced levels of complement factors, an increased number of activated macrophages in the lung may contribute to a changed immune response, which may be of significance for the granulomatous inflammation seen in sarcoidosis and may also contribute to the tissue damage seen in sarcoid fibrosis.

Biomarkers↗
PubMed1992

Human umbilical vein endothelial cells synthesize S-protein (vitronectin) in vitro.

S-protein, also named vitronectin, is a multifunctional glycoprotein with molecular weight (MW) of about 75 kDa and a serum concentration of 0.14-0.60 mg/ml. It is synthesized mainly in the liver, but synthesis has also been found in monocytes/macrophages. We used human umbilical vein endothelial cells (EC) which were incubated with agarose beads, an activator of the alternative complement pathway. By radioimmunoassay (RIA) based on monoclonal and polyclonal S-protein antibodies, we detected S-protein on harvested agarose beads. The time-dependent increase in the amount of S-protein was significantly reduced by the presence of cycloheximide (10 micrograms/ml) in the cell cultures. We also found a strong binding of S-protein antibodies to agarose beads preincubated in native serum, which was strongly reduced (70-80%) by inactivation of the alternative complement pathway (50 degrees C, 20 min). Our results show that EC synthesize S-protein in vitro.

Cells, Cultured↗
PubMed1992

Enzyme immunosorbent assay for Ebola virus antigens in tissues of infected primates.

A sandwich enzyme immunosorbent assay (EIA) using a mixture of mouse monoclonal antibodies for antigen capture and polyclonal hyperimmune rabbit anti-Ebola virus serum for antigen detection was developed and evaluated on the tissues of monkeys naturally or experimentally infected with strains of Ebola viruses. When compared with virus isolation, the antigen detection EIA was both sensitive and specific: 44 of 45 (97.7%) liver homogenates and 38 of 41 (92.7%) spleen homogenates that were culture positive and tested by both techniques were positive for viral antigen, while 85 of 87 (97.7%) culture-negative liver homogenates and 66 of 66 culture-negative spleen homogenates were found to be antigen negative. The assay, initially developed to detect antigens of prototype African strains of Ebola virus, reliably detected related strains of Ebola virus found during two recent outbreaks of Ebola virus infection among imported, quarantined Macaca fascicularis monkeys in the United States. The assay allows economical and rapid testing of large numbers of tissue specimens. Antigen was found in homogenates of spleen and liver and in serum.

Animals↗
PubMed1992

The putative E5 open reading frame of cottontail rabbit papillomavirus is dispensable for papilloma formation in domestic rabbits.

In the cottontail rabbit papillomavirus (CRPV)-rabbit system, recombinant CRPV DNA can induce papillomas. This investigation was undertaken to evaluate whether the E5 open reading frame (ORF) of CRPV is required for papilloma formation. The CRPV genome we utilized, CRPV-WA, was sequenced in the E5 region and was found to contain one deletion, two insertions, and one transition mutation compared with CRPV-KS, the CRPV genome that has been fully sequenced. Despite these differences, an intact E5 ORF is preserved, supporting the notion that this gene may serve a biological function. One frameshift and two in-frame mutations were constructed in the small region of the 5' end of the E5 ORF that follows the E2 stop codon and precedes the L2 ORF. Several hundred rabbit skin sites were inoculated with each DNA preparation with a jet injector to test the ability of three CRPV E5 mutant DNAs to induce papillomas. In vivo results showed that each of the mutants induced papillomas, and biochemical analysis demonstrated that the E5 mutations present in DNA inocula were retained in the papillomas. The frequency of papilloma formation, however, was generally lower with each of the CRPV E5 mutants than with wild-type CRPV DNA, particularly so for the E5 frameshift mutant, suggesting that although the recognized E5 ORF is not required in domestic rabbits for the induction of papillomas by CRPV DNA, it may facilitate their formation.

Amino Acid Sequence↗
PubMed1992

Heparin, fatty acids and sodium, potassium-ATPase inhibition by plasma factors during hemodialysis.

To assess the relationship between heparin and the associated increase in nonesterified fatty acids (NEFA) and their possible influence on Na,K-ATPase during hemodialysis, we studied two groups of patients: (1) 12 patients on chronic hemodialysis dialysed with heparin and (2) 6 patients dialysed without heparin. All 12 patients who received heparin anticoagulation had a 7-fold rise in NEFA on average and also had an increase in circulating inhibitors of Na,K-ATPase assayed by 3H-ouabain displacement from Na,K-ATPase and/or by effect of plasma on the uptake of 86Rb by rat aortic rings. Serial assays in 3 of the patients receiving heparin showed NEFA and inhibitory changes to be at or near maximum within 30-60 min. Of the individual NEFA, the greatest relative increases were in oleic (18:1) and linoleic (18:2) acids, and the strongest correlations were between linoleic acid and both 3H-ouabain displacement (r = 0.94) and 86Rb uptake (r = 0.86). However, a small and slower increase in NEFA also occurred in 3 of the patients dialysed without heparin. We conclude that heparin anticoagulation during dialysis leads to a rapid and marked increase in circulating NEFA, particularly the unsaturated fatty acids, with a corresponding interference with Na,K-ATPase activity. The clinical significance of these findings is unknown. The rise in NEFA during dialysis without heparin in some patients suggests that factors other than heparin may also contribute to the rise in NEFA.

Adult↗
PubMed1992

Mechanisms of amplification, deactivation, and noise reduction in invertebrate photoreceptors.

In this review we have discussed the problem of deactivation at both the rhodopsin and G protein levels. Of particular interest is the novel observation that rhodopsin deactivation can be modulated by light. This modulation is likely to play an important role in light adaptation by reducing the gain of transduction. One interesting possibility is that this modulation involves the phosphorylation of an arrestin-like molecule, but this remains to be tested. One of the experimental advantages of Limulus photoreceptors is the large size of the single photon responses and the fact that even single G proteins produce a detectable response. This made possible the observation that nonhydrolyzable GTP analogues produce discrete transient events rather than the step-like events that would be predicted by previous models. This observation led us to a new view of how enzyme deactivation is coupled to GTP hydrolysis on G protein. According to this view, enzymes are activated by G protein, but can be deactivated by processes that are not dependent on G protein or the hydrolysis of GTP. We have conducted several types of experiments, including some on the vertebrate rod system, that strongly support this hypothesis. A second major theme of this review is transduction noise. The available biochemical evidence suggests that both G protein and G protein-activated enzymes are likely to become spontaneously active and generate undesirable noise. Our measurements indicate, however, that this noise is orders of magnitude smaller than would be predicted by simple models, suggesting that special mechanisms must exist for suppressing this noise. We have proposed a specific mechanism by which enzymes regulated allosterically by multiple subunits could act as coincidence detectors to reduce transduction noise. Finally, there is the fundamental question of which second messengers have a direct role in invertebrate phototransduction. After Fesenko et al. (1985) showed that the light-dependent conductance in vertebrate rods was modulated by cGMP and not by Ca2+, there was rapid progress in understanding the vertebrate photoreceptor transduction mechanism. Now that it has been established that invertebrate light-dependent channels are regulated by cGMP and not by Ca2+, we can expect rapid progress in understanding invertebrate phototransduction. A key question that needs to be answered is whether the InsP3-Ca2+ pathway somehow triggers changes in cGMP or whether there is an altogether different pathway by which cGMP metabolizing enzymes are affected by light.

Adaptation, Physiological↗
PubMed1992

Knowledge of colorectal cancer among older persons.

Cancer screening is a national health priority, especially for colorectal cancer, the second leading cause of death due to cancer in the United States. The researchers measured colorectal cancer knowledge among 211 older Americans. A quasiexperimental pretest-posttest two-by-two factorial design was used to test the effect of knowledge on participation in fecal occult blood screening. The American Cancer Society's colorectal cancer educational slide-tape presentation served as the basis for all of the educational programs. Hemoccult II kits were distributed at no cost to the participants. Descriptive statistics, chi 2, and logistic regressions were used to analyze data. One-half of the participants had incomes below the poverty level. Almost one-half the subjects in the study sample stated that they had not received any information about colorectal cancer within the past year. Caucasians had more knowledge of colorectal cancer than African Americans [F(1, 78) = 7.92, p < 0.01] and persons with higher income had more knowledge than persons with less income [F(2, 76) = 3.01, p = 0.05]. Subjects showed significant increases in colorectal cancer knowledge 6 days after the colorectal cancer education program [t(79) = 2.59, p = 0.01] and this increased knowledge was a predictor of participation in free fecal occult blood screening [chi 2(1, n = 164) = 5.34, p = 0.02].

Aged↗
PubMed1992

The killifish Rivulus marmoratus: a potential biocontrol agent for Aedes taeniorhynchus and brackish water Culex.

In the laboratory, newly hatched fry of Rivulus marmoratus were effective predators on 1st-instar Aedes taeniorhynchus. Adult fish consumed 4th-instar Ae. taeniorhynchus and egg rafts of Culex quinquefasciatus at a rate increasing with standard length of the fish. Predation of Rivulus marmoratus on Ae. taeniorhynchus larvae in the field was documented by observing the passage of larval/pupal remains through the gut. Laboratory reared fish released at known Ae. taeniorhynchus breeding sites survived over 1.5 years, but did not reproduce.

Aedes↗
PubMed1992

A complication of the Greenfield filter: fracture and distal migration of two struts--a case report.

This is a case report of a 41-year-old woman who required surgical removal of a Greenfield filter 7 months after placement. The filter developed several complications. Two struts were noted to be completely separated from the filter and lodged in the infrarenal vena cava. The filter had migrated to a resting position in the right renal, vein with two struts perforating the renal vein and inferior vena caval junction. The perforating struts were intraperitoneal and were found to impinge on the right ureter with seromuscular involvement of the second portion of the duodenum. No free perforation was noted at the time of exploration.

Adult↗
PubMed1991

SPECT imaging of the benzodiazepine receptor in non-human primate brain with [123I]Ro 16-0154.

We have used SPECT (single photon emission computed tomography) imaging in non-human primates to examine the time course and pharmacological specificity of 123I-labeled Ro 16-0154 as an in vivo probe of the benzodiazepine receptor. Maximal brain uptake was reached approximately 70 min post i.v. administration of the radioligand and represented approximately 10% of the injected dose. The regional distribution of radioactive densities was consistent with the known distribution of benzodiazepine receptors in primate brain, with highest uptake localized over the occipital area. Washout of radioactivity was relatively slow with a rate of 3% per hour after the time of peak radioactivity. Injection of the benzodiazepine antagonist Ro 15-1788 (0.2-0.3 mg/kg i.v.) caused a rapid decrease of more than 90% of radioactivity from brain. In summary, [123I]Ro 16-0154 is a promising in vivo SPECT radioligand for the benzodiazepine receptor, with high brain uptake, a stable period of peak radioactivity, appropriate regional distribution, and ability to be displaced by other benzodiazepine receptor agents.

Animals↗
PubMed1991

Distribution and density of substance P receptors in the feline gastrointestinal tract using autoradiography.

Autoradiography was used to localize and quantify substance P receptors in the feline gastrointestinal tract. The specific binding of 125I-Bolton Hunter substance P was determined in the esophagus, lower esophageal sphincter, antrum, pylorus, duodenum, jejunum, ileum, ileocecal sphincter, and colon. Competitive binding studies indicated that substance P binding sites or NK-1 receptor sites were demonstrated. The concentration of NK-1 receptors was greatest in the distal half of the gastrointestinal tract, with the highest concentrations in the proximal colon. The circular muscle layer contained the greatest amount of substance P binding. The location and density of binding sites for substance P may be important in understanding the relative importance of both the pharmacological responses to this neuropeptide and the immunohistochemical evidence of the peptide at different sites in the intestine.

Animals↗
PubMed1990

S protein binds to serum-treated agarose beads independently of complement activation and the formation of the terminal complement complex on the beads.

Comparison of initial (early-phase) and terminal (late-phase) sequence activation of complement by agarose beads and endotoxin was evaluated in an enzyme immunoassay (EIA) of serum levels of C3c and C9 neoepitopes, respectively. EIA and Western blotting with anti-S protein monoclonal antibody revealed lower S protein values and weaker S protein bands in serum activated by agarose beads than by endotoxin, implying that S protein was removed from serum by binding to agarose. The binding of S protein to the beads was confirmed by radioimmunoassay and was found to be equal in normal and heat-inactivated serum. In contrast, the terminal complement complex was formed only on agarose beads incubated with normal serum and not with inactivated serum.

Blood Proteins↗
PubMed1990

Synthesis of complement by alveolar macrophages from patients with sarcoidosis.

Sarcoidosis is a granulomatous disorder of unknown aetiology. Alveolar macrophages (AM) in sarcoidosis release a variety of mediators important to the pathogenesis of the disease. Complement is essential for the inflammatory response and we investigated whether there were any major defects in the potential for sarcoidosis AM to synthesize complement in vitro. AM from 11 patients with active sarcoidosis and three healthy controls were cultured under serum-free conditions. There was a significant binding of polyclonal (anti-C5, -C6, -C7, -C8) and monoclonal anti-complement antibodies (anti-C3c and anti-C9 neoepitope (aE11] to agarose beads incubated with unstimulated AM for 24, 48, or 72 h. A significant and inhibitable production of soluble C3c, C5, C9, and S-protein was found in the harvested medium as detected by enzyme immunoassays. Activated C3 and C9 were also detected based on neoepitope expression. Presence of co-cultured agarose beads reduced the amount of soluble S-protein due to deposition on the agarose. We argue that the C9 neoepitope is an integral part of the terminal complement complex (TCC), both in the fluid and solid phase when bound to the agarose. In the fluid phase, SC5b-9 was generated, whereas the agarose-bound S-protein is assumed not to be associated with TCC on the beads. The results demonstrate for the first time that AM from sarcoidosis patients synthesize the functional alternative and terminal pathway of complement.

Adult↗