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Biomedical subjects

C B Pert

Publications and source records attributed to C B Pert.

At least 19 recordsLinked to original sources
PubMed1992

Potent gp120-like neurotoxic activity in the cerebrospinal fluid of HIV-infected individuals is blocked by peptide T.

The envelope protein of the human immunodeficiency virus (gp120) causes neuronal death in developing murine hippocampal cultures or rat retinal ganglion cells. In HIV-infected individuals, gp120 released from HIV-infected macrophages or other cells in the brain has been proposed as the etiology for the pathophysiology of AIDS central nervous system (CNS) disease by diffusing to act at a distance to cause damage and/or death to neighboring neurons. In this study, 28 cerebrospinal fluid (CSF) samples from HIV-infected individuals (79% were WR stage 1 and 2) and neurological disease controls were tested, blind to the investigator, for the presence of in vitro neuronal killing activity. Neurotoxic activity was detected with peak effects at a 1:10(5) dilution in CSF from 9/18 HIV-infected individuals and 1/10 neurological disease controls. Thus half of CSF from early stages of HIV disease are characterized by the presence of neurotoxic activity which is not present in control CSF (Fischers exact test, P < 0.05). The neuronal toxicity by patient CSF could be prevented by peptide T (1 nM). A monoclonal antibody to mouse CD4, RL.172, also attenuated or prevented CSF-induced neuronal killing in all four CSF samples tested. In addition, an antiserum to peptide T previously shown to bind gp120 and neutralize both infectively and direct gp120 neurotoxicity, neutralized the CSF factor. gp120, or a modified small fragment, is suggested to be the responsible toxic molecular entity. These results may be relevant to the pathophysiology of HIV-related CNS disease and the mechanism by which peptide T causes improvements.

Animals↗
PubMed1991

Pharmacokinetics of peptide T in patients with acquired immunodeficiency syndrome (AIDS).

1. The pharmacokinetics of Dala1-peptide T-NH2 (peptide T) was determined during phase I clinical trials in patients with acquired immunodeficiency disease (AIDS) and AIDS related complex (ARC). Drug levels were determined by specific RIA, and in some cases with HPLC analysis, after intravenous (i.v.) or intranasal (i.n.), via metered sprayer, administration. 2. The plasma kinetics appeared to be bi-phasic with a first compartment half-life of 30 to 60 minutes and a second plasma clearance rate of 4 to 6 hours, observed for both routes of administration. Peptide T, in one individual was confirmed to be present at 6 hrs in plasma, determined after HPLC isolation followed by specific RIA. 3. Bioavailability, determined for a 2 mg test dose in six individuals was 9.3 +/- 6.9 nmol/L. Peak plasma levels of 41 +/- 30 nmol/L after 10 mg i.n., 2.8 +/- 5.9 nmol/L after 2 mg i.n., and 0.13 +/- 0.07 nmol/L after 0.4 mg i.n. were observed. In two individuals tested, peptide T was detected in CSF at levels 20% of the corresponding plasma level 90 and 145 minutes post i.v. administration. Peptide T was not detected in urine. I.N. administration was well tolerated for times up to 21 months.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Identification of a domain in cytochrome C that displaces [3H]TCP binding from rat brain membrane receptors: synthesis of beta-neuroprotectin.

1. A stereospecific radioreceptor binding assay for the phencyclidine analogue, [3H]TCP, was utilized to screen for inhibition of binding in extracts of rat brain. 2. Extracts were prepared from rat cerebral cortex and hippocampus by methods employing aqueous acid. The extracts were fractionated by reversed phase-HPLC (RP-HPLC) and tested for activity in the radioreceptor assay. Three zones of activity were detected. The middle zone was further purified by high performance-size exclusion chromatography (HP-SEC). 3. Size exclusion chromatography revealed a single zone of activity corresponding to mol. wts of ca 12,000-31,000 daltons. A fraction from this zone was digested with trypsin, and the resulting enzyme fragments, isolated by a combination of HP-SEC and RR-HPLC, were identified as fragments of rat cytochrome C. 4. Horse cytochrome C was digested with trypsin and the fragments were similarly purified on the basis of the [3H]TCP binding displacement assay. The fragments were sequenced and found to be trypsin cleavage products of a single largely invariant domain of the cytochrome C molecule: Lys-Lys-Lys-Asp-Glu-Arg-Ala-Asp-Leu-Ile-Ala-Tyr-Leu-Lys-Lys. 5. beta-neuroprotectin (D)-Ala-Asp-Leu-Ile-Ala-Tyr-Leu-NH2, inhibits [3H]TCP binding and provides protection against NMDA mediated neuronal cell death at low concentrations.

Amino Acid Sequence↗
PubMed1990

Isolation and identification of a peptide from rat brain which inhibits [3H]TCP binding.

1. A stereospecific radioreceptor binding assay for the phencyclidine analogue [3H]TCP was utilized to screen for inhibitors of binding in extracts of rat brain. 2. Extracts were prepared from rat cortex and hippocampus by methods employing aqueous acid or acidified methanol. Samples were fractionated by reversed phase-HPLC (RP-HPLC) and tested for activity in the radioreceptor assay. Three zones of activity were detected. The most active fraction was further purified by high performance-size exclusion chromatography. 3. Size exclusion chromatography revealed two zones of activity, corresponding to mol. wts of 4000-8000 Da and 1000-2000 Da. Final purification of the lower molecular weight material was achieved by RP-HPLC. 4. Two well-separated peaks were shown to be homogeneous. Their amino acid sequences were determined by automated Edman degradation and data base searching identified these two peaks as the undecapeptide Substance P and its oxidized counterpart (Substance P sulfoxide). 5. Comparative HPLC of synthetic Substance P, or its sulfoxide, as well as spectral analysis confirmed the identity of the isolated peptides. 6. Synthetic Substance P inhibits specific [3H]TCP binding in the radioreceptor assay.

Amino Acid Sequence↗
PubMed1989

Influenza viruses induce autoantibodies to a brain-specific 37-kDa protein in rabbit.

Immunization of rabbits with certain H1N1 influenza viruses, including the neurotropic strains NWS/33 and WSN/33 and the New Jersey/76 strain, resulted in the production of autoantibodies to a brain-specific protein of 37 kDa that is present in various species, including humans. Autoantibodies were produced to brain only; various other tissues tested were negative. These antibodies were not elicited by other influenza A or B viruses, including closely related recombinant strains, but were elicited by the isolated hemagglutinin of A/Bellamy/42 strain and by formaldehyde-fixed WSN virus--demonstrating that infection was not essential for the induction of autoantibodies. In histological studies, reaction with anti-viral antisera was specific to gray matter and was confined to sera that recognized the 37-kDa protein. Antibody binding was prominent in regions comprised of neuronal cell bodies in cellular layers of the dentate gyrus, hippocampus, cerebral cortex, and cerebellum and was undetectable in myelin-rich regions, such as the corpus callosum. The 37-kDa protein, therefore, appears to be a neuronal antigen. Antibodies directed against this protein may be involved in the pathogenesis of one or more of the neuropsychiatric disorders that occur after infection with influenza.

Animals↗
PubMed1988

Neuromodulation by polypeptide growth factors: preliminary results on the distribution of epidermal growth factor receptors in adult brain.

Polypeptide growth factors and their receptors are expressed within the brain and neuromodulatory functions are described. Using autoradiography of 125I-epidermal growth factor (EGF) and radioimmunohistochemistry with an antibody to the EGF receptor, we have determined the distribution pattern of the EGF receptor in adult rat brain. The patterns achieved by both methods were similar at every level of the neuroaxis examined. Highest densities of autoradiographic grains were present in the cingulate cortex, cerebral cortex, hippocampus, amygdala and caudate putamen. This pattern of distribution suggests that EGF may have neuromodulatory functions. Common expression of polypeptide receptors by cells of different organ systems constitutes a biochemical basis for homeostatic network regulation.

Animals↗
PubMed1988

The opiate receptor: a single 110 kDa recognition molecule appears to be conserved in Tetrahymena, leech, and rat.

We compared the molecular nature of the rat brain opiate receptor with that of the invertebrate leech, Haemopis marmorata, and the protozoan, Tetrahymena, in order to examine the issue of apparent receptor heterogeneity with respect to biochemical structure. A binding study with rat brain membrane verified that [125I]beta-endorphin [( 125I]beta E), a broad specificity ligand, is displaced by the antagonist (-)-naloxone, but not the inactive stereoisomer (+)-naloxone; agonists considered prototypes for mu, delta, and kappa opiate receptors all displayed stereospecific binding displacement. For SDS-PAGE analysis of the opiate receptor [125I]beta-endorphin was covalently affixed to its recognition molecule with the cross-linking reagent DSS. Primary reaction products occur at 110, 58/55, and 29 kDa. Cross-linking products of all 3 molecular weights are effectively reversed by opiate ligands, regardless of their mu, delta, or kappa specificities. Peptide mapping studies in SDS gels, using limited proteolysis, showed that the 110 kDa band can be digested into 58 and 29 kDa fragments and the 58 kDa band into a 29 kDa fragment. Additional smaller molecular weight fragments were generated from the 110, 58/55, and 29 kDa bands which shared their molecular weights. Two possible explanations for the extensive sequence homology between the three major cross-linking products are: (1) the 110 kDa species is the opiate receptor, and the 58 and 29 kDa species are proteolytic fragments; and (2) one of the lower molecular weight species is the opiate receptor, and adjacent receptors are aggregated into the 110 kDa complex through cross-linking.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Neuronal cell killing by the envelope protein of HIV and its prevention by vasoactive intestinal peptide.

The clinical manifestations of AIDS (acquired immune deficiency syndrome) often include neuropsychiatric and neurological deficits, including early memory loss and progressive dementia. HIV (human immunodeficiency virus), the aetiological agent of AIDS, is probably carried by infected macrophages in the central nervous system. The virus enters cells by binding its envelope glycoprotein gp120 to the CD4 antigen present on brain and immune cells. From the data reported in this paper, we now suggest that the neuronal deficits associated with HIV may not be entirely a result of infectivity, but that gp120 shed from HIV could directly produce the neuropathology as a result of its interference with endogenous neurotrophic substances. It is known that an analogue of a sequence contained in vasoactive intestinal peptide (VIP) occurs in all known sequenced gp120 isolates and that VIP is important for neuronal survival in cell culture. Here we show that purified gp120 from two diverse HIV isolates and a recombinant gp120 from a third isolate were all potent in specifically producing significant neuronal cell death in dissociated hippocampal cultures derived from fetal mice, and that this could be reduced by monoclonal antibodies against the murine CD4 antigen and completely antagonized by VIP.

Animals↗
PubMed1988

Identification and characterization of the opiate receptor in the ciliated protozoan, Tetrahymena.

Tetrahymena, a ciliated protozoan, is a highly specialized, differentiated eukaryotic organism. It is known to possess many informational substances, including beta-endorphin (beta E). We wished to investigate the possibility that this organism possesses a functional opiate receptor which might be similar to the well-characterized opiate receptor in the rat brain. Binding assays using both living cells and membrane preparations, verified stereospecific, saturable, reversible 125I-beta E binding. This binding was displaceable by various opiates chosen to represent each of the putative opiate subtypes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of a disuccinimidyl suberate cross-linked 125I-beta E-receptor complex revealed a pattern of bands which consistently included bands at 110, 58-55, and 29 kDa. These bands, which were all displaceable by the classical antagonist, naloxone, as well as by other opiates, are thought to be prototypic for various opiate receptor subtypes. Limited proteolysis in SDS-PAGE showed that the 110 kDa band could be fragmented into 58-55 and 29 kDa bands and that the 58 kDa band could generate a 29 kDa fragment. The limited digest fragments of the 110, 58-55 doublet and 29 kDa bands were remarkably similar to those generated from the rat brain receptor. Analytical isoelectric focusing of digitonin solubilized 125I-beta E-receptor complexes showed the isoelectric points (pI) from both the rat and Tetrahymena were identical (pI 4.6). Chemotactic experiments with the intact Tetrahymena, demonstrated that these unicellular animals migrated toward a 10(-9) M beta E gradient. Chemotaxis was blocked by (-)-naloxone but not (+)-naloxone, suggesting a stereospecific opiate receptor-mediated response. We conclude that Tetrahymena possesses a functional opiate receptor (recognition molecule) very similar to the opiate receptor of the rat brain.

Animals↗
PubMed1988

AIDS and its dementia as a neuropeptide disorder: role of VIP receptor blockade by human immunodeficiency virus envelope.

The CD4 molecule was originally described as a marker for a subset of lymphocytes; however, recent work has shown that a similar, if not identical, molecule is present on human brain. We have realized that this cell-surface recognition molecule is normally modulated by vasoactive intestinal peptide (VIP), one of the 50 or more neuropeptides that compose a shared intercellular network joining the brain, glands, and immune system. Human immunodeficiency virus (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), has been found to mimic VIP binding via peptide T (4-8), a pentapeptide sequence present in approximately the same region of all 20 HIV isolates whose sequences are currently known. AIDS dementia results from interference of gp120, present on the HIV envelope protein, with normal VIP-ergic neurotrophic effects, and effects on cerebral blood flow.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Enhanced secretion of immunoreactive bombesin by alveolar macrophages exposed to silica.

Bombesin has recently been identified in alveolar macrophages (AM). Since this peptide has been shown to stimulate fibroblast growth in culture, we wished to determine whether AM exposed to the fibrogenic particle silica in vivo were capable of secreting more bombesin than AM recovered after instilling inert carbon particles to the lung. Rats received 10 mg of either carbon or silica by intratracheal injection and were killed at 3 days or 6 weeks. Both particles induced a rapid inflammatory response, and normal levels of immunoreactive bombesin were measured in lung lavage fluid and in freshly recovered macrophages from all rats. However, incubation of normal AM for 4 h in serum free medium produced a significant increase in bombesin levels measured in supernatants. Bombesin in supernatants of AM cultured after recovery from rats exposed to carbon was at the control value, while AM recovered after silica exposure in vivo secreted increased amounts of bombesin when cultured. Cells recovered 6 wk after instilling silica to the lung and cultured for 4 h secreted 50% more bombesin than control AM. At this time, hydroxyproline measured in the silica-injected lungs was also significantly higher than in controls or carbon-injected rats. These results indicate that AM recovered from lungs after exposure to silica secrete increased amounts of bombesin during the development of pulmonary fibrosis.

Animals↗
PubMed1988

Regional distribution and density of Thy 1.1 in rat brain and its relation to subpopulations of neurons.

We have used a radioimmunohistochemical technique employing OX-7, a monoclonal antibody to rat Thy 1.1, to determine the regional distribution and density of Thy 1 in rat brain. Thy 1.1 was found to be unevenly distributed in rat brain with distinct regional differences related to the density of neuronal perikarya. This is consistent with the previously reported findings that Thy 1.1 is found primarily on neurons. However, the relative absence of Thy 1 in some cell body-dense areas of the brain suggests that Thy 1 is expressed differentially on specific subsets of neurons which are abundant and widespread throughout the brain.

Animals↗
PubMed1988

Vasoactive intestinal peptide receptors in rat spleen and brain: a shared communication network.

The binding sites for [125I]-vasoactive intestinal polypeptide (125I-VIP) in rat spleen and brain were localized using autoradiography. High affinity VIP receptors are present in rat spleen, and competition studies reflect structure-activity relationship typical of VIP receptors elsewhere. In spleen, specific binding of 125I-VIP occurs on red pulp and, most abundantly, on the periarteriolar lymphoid sheath (PALS) of white pulp. Unlabeled VIP competes for binding to both red pulp and white pulp, whereas secretin displaces binding to PALS more potently than to red pulp. This indicates that expression of VIP and/or secretin type receptors is limited to T lymphocytes of white pulp. In red pulp, VIP receptor bearing cells probably are monocytes/macrophages since this is the most abundant red pulp cell type. In the brain, VIP receptors are widely distributed with the highest densities occurring in "sensory" areas. Receptors are abundant in the olfactory bulb, thalamic nuclei, several cranial nuclei and the area postrema. High levels of 125I-VIP binding occurred on inner walls of blood vessels of the brain and spleen. The distribution patterns of receptors for "VIP-ergic signals" in brain and lymphoid tissue indicate interrelatedness of the two organ systems. This may serve as one biochemical rationale for a bio-psycho-social view of health and disease.

Animals↗
PubMed1988

Cholecystokinin and the immune system: receptor-mediated chemotaxis of human and rat monocytes.

The ability of the peptide cholecystokinin (CCK) to induce monocyte chemotaxis was tested both in vivo and in vitro. In the in vitro assay, the activity of different forms of CCK on human monocytes was studied demonstrating the importance of sulfation on tyrosine for the chemotactic activity. CCK receptor antagonists benzotript and CR-1369 are able to block CCK 8 sulfated chemotaxis, thus suggesting the presence of CCK receptors on human monocytes. In both acute and chronic experiments, the peptide specifically increases the number of peritoneal macrophages, when injected into rat peritoneal cavity. These data suggest that immune system cell migration from one body compartment to another can be produced by a neuropeptide receptor-mediated process.

Amino Acid Sequence↗
PubMed1988

Co-localization of IGF-II receptors, IL-1 receptors and Thy 1.1 in rat brain.

The distribution of 125I-IGF-II and 125I-IL-1 binding to rat brain sections was determined with autoradiography, Thy 1.1 with radioimmunocytochemistry. The pattern of distribution of all three was found to be identical and almost the same as the pattern achieved by a Nissl stain. In preliminary studies excess IGF-II was shown to inhibit the binding of radiolabeled IGF-II and IL-1 but not anti-Thy 1.1. Similarly, IL-1 inhibited the binding of radiolabeled IL-1 and IGF-II but not anti-Thy 1.1. Anti-Thy 1.1 inhibited the binding of IGF-II and IL-1, but was not inhibited by either IGF-II or IL-1. The distribution data from this study indicates the IGF-II receptors, IL-1 receptors and Thy 1.1 are present on almost all neurons in the brain. The preliminary competition studies suggest that these factors may, under some conditions, function in a common biochemical cellular process to regulate each other's functions. Both IGF-II and IL-1 are growth factors and Thy 1.1 may play a role in synapse formation and cell adhesion. Perhaps, among other things, these growth factors and Thy 1.1 function in the development and maintenance of intercellular contacts within the brain.

Animals↗