Protection against experimental encephalomyelitis. Idiotypic autoregulation induced by a nonencephalitogenic T cell clone expressing a cross-reactive T cell receptor V gene

The recovery process in experimental autoimmune encephalomyelitis (EAE) in Lewis rats is characterized by an increasing diversity of T cell clones directed at secondary epitopes of myelin basic protein. Of particular interest, residues 55 to 69 of guinea pig basic protein could induce protection against EAE. A nonencephalitogenic T cell clone, C455-69, that was specific for this epitope transferred protection against both active and passive EAE. Clone C4 was found to express V beta 8.6 in its Ag receptor, and residues 39 to 59 of the TCR V beta 8.6 sequence were found to be highly crossreactive with the corresponding residues 39 to 59 of TCR V beta 8.2, which is known to induce protective anti-idiotypic T cells and antibodies. Like the TCR V beta 8.2 peptide, the V beta 8.6 sequence induced autoregulation and provided effective treatment of established EAE. Thus, the EAE-protective effect of the guinea pig basic protein 55-69 sequence was most likely mediated by T cell clones such as C4 that could efficiently induce anti-TCR immunity directed at a cross-reactive regulatory idiotope.

Protection against experimental encephalomyelitis. Idiotypic autoregulation induced by a nonencephalitogenic T cell clone expressing a cross-reactive T cell receptor V gene

The recovery process in experimental autoimmune encephalomyelitis (EAE) in Lewis rats is characterized by an increasing diversity of T cell clones directed at secondary epitopes of myelin basic protein. Of particular interest, residues 55 to 69 of guinea pig basic protein could induce protection against EAE. A nonencephalitogenic T cell clone, C455-69, that was specific for this epitope transferred protection against both active and passive EAE. Clone C4 was found to express V beta 8.6 in its Ag receptor, and residues 39 to 59 of the TCR V beta 8.6 sequence were found to be highly crossreactive with the corresponding residues 39 to 59 of TCR V beta 8.2, which is known to induce protective anti-idiotypic T cells and antibodies. Like the TCR V beta 8.2 peptide, the V beta 8.6 sequence induced autoregulation and provided effective treatment of established EAE. Thus, the EAE-protective effect of the guinea pig basic protein 55-69 sequence was most likely mediated by T cell clones such as C4 that could efficiently induce anti-TCR immunity directed at a cross-reactive regulatory idiotope.

5-HT3-like receptors in the rat medial prefrontal cortex: an electrophysiological study

In this study, we have identified and characterized 5-HT3-like receptors in the rat medial prefrontal cortex (mPFc), an area with a moderate density of 5-HT3 binding sites, using the techniques of single unit recording and microiontophoresis. The microiontophoresis of the 5-HT3 receptor agonist 2-methylserotonin (2-Me-5HT), similar to the action of 5-HT, produced a current-dependent (10-80 nA) suppression of the firing rate of both spontaneously active and glutamate (GLU)-activated (quiescent) mPFc cells. Phenylbiguanide (PBG), another 5-HT3 receptor agonist, suppressed the firing rate of mPFc cells but was less effective compared to 2-Me-5HT. The continuous iontophoresis (10-20 min) of 1 M magnesium chloride markedly attenuated the suppressant effect produced by electrical stimulation of the ascending 5-HT pathway, but did not alter 2-Me-5HT's action, suggesting that the action of 2-Me-5HT is a direct one. The suppressant action of 2-Me-5HT on mPFc cells was blocked by a number of structurally diverse and selective 5-HT3 antagonists, with a rank order of effectiveness as follows: ICS 205930 = (+/-)-zacopride greater than granisetron = ondansetron = LY 278584 greater than MDL 72222. Furthermore, the intravenous administration of (+/-)-zacopride antagonized the action of 2-Me-5HT and PBG on mPFc cells. In contrast to the effects of the 5-HT3 receptors antagonists, other receptor antagonists such as metergoline (5-HT1A,1B,1C.2), (+/-)-pindolol (5-HT1A,1B, beta), SCH 23390 (5-HT1C.2, D1), l-sulpiride (D2) or SR 95103 (GABAA) failed to block 2-Me-5HT's action. These results combined suggest that 2-Me-5HT's suppressive action on mPFc cells is mediated directly by 5-HT3-like receptors.

The CCK-A receptor antagonist devazepide but not the CCK-B receptor antagonist L-365,260 reverses the effects of chronic clozapine and haloperidol on midbrain dopamine neurons

In this study, we examined the effects of the cholecystokinin-A (CCK-A) antagonist devazepide (MK 329) and the CCK-B antagonist L-365,260 to reverse the decrease in the number of spontaneously active dopamine (DA) cells in the ventral tegmental area and substantia nigra pars compacta after chronic haloperidol (HAL) or clozapine (CLOZ) treatment. The intravenous administration of devazepide (2 micrograms/kg) but not L-365,260 (2 micrograms/kg) reversed the reduction in the number of spontaneously active A9 and A10 DA cells produced by chronic HAL. Furthermore, devazepide also reversed the decrease in the number of spontaneously active A10 DA cells produced by chronic CLOZ administration. Overall, these results suggest that CCK-A but not CCK-B receptors play an important role in mediating or maintaining the chronic antipsychotic drug-induced effect on midbrain DA cells.

The effect of typical and atypical antipsychotic drugs on the stimulation of phosphoinositide hydrolysis produced by the 5-HT3 receptor agonist 2-methyl-serotonin

The atypical antipsychotic drug clozapine (CLOZ) and a structurally related compound RMI 81,582 (RMI) dose-dependently inhibited the stimulation of phosphoinositide hydrolysis induced by the 5-HT3 receptor agonist 2-methyl-serotonin in the rat fronto-cingulate and entorhinal cortices. The antagonism of 2-methyl-serotonin's stimulation of phosphoinositide hydrolysis by CLOZ and RMI was comparable to that observed with 5-HT3 antagonists such as granisetron, ondansetron, ICS 205-930 and zacopride. By contrast, the typical antipsychotic drugs haloperidol (HAL) and chlorpromazine (CPZ) did not antagonize the stimulation of phosphoinositide hydrolysis induced by 2-methyl-serotonin. The 5-HT3 receptor antagonizing effect of CLOZ and RMI may contribute to the 'atypical' pharmacological profile of these antipsychotic drugs.

The action of (+/-)-MDMA on medial prefrontal cortical neurons is mediated through the serotonergic system

The mechanism of action of systemically administered (+/-)-MDMA (3,4-methylenedioxymethamphetamine) on spontaneously active neurons in the medial prefrontal cortex (mPFc) of chloral hydrate anesthetized rats was examined using standard single unit extracellular recording techniques. Intravenously administered MDMA dose-dependently decreased the firing rates of the majority of mPFc neurons in control rats. In contrast, in rats that were pretreated with p-chlorophenylalanine (PCPA), which depletes the brain serotonin (5-hydroxytryptamine, 5-HT) content by inhibiting tryptophan hydroxylase, the rate-limiting enzyme in the synthesis of 5-HT, MDMA was largely ineffective in inhibiting the firing of mPFc cells. In PCPA-treated animals, the administration of 5-hydroxytryptophan (5-HTP), which presumably restored the brain 5-HT content, but not L-DOPA, reinstated MDMA's inhibitory action in PCPA-treated rats. In rats that were pretreated with alpha-methyl-p-tyrosine (AMPT), which depletes the brain dopamine (DA) content by inhibiting tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of DA, MDMA inhibited the firing of all of the mPFc cells. MDMA's effect on mPFc neurons was reversed by 5-HT receptor antagonists such as granisetron and metergoline. These results strongly suggest that MDMA exerts its action on mPFc cells indirectly by releasing endogenous 5-HT.

Effect of 5-hydroxytryptamine3 receptor agonists on phosphoinositides hydrolysis in the rat fronto-cingulate and entorhinal cortices

In the present experiments we have investigated the possible coupling of 5-hydroxytryptamine (HT)3 receptors to the metabolism of phosphatidylinositol (PI) in the rat fronto-cingulate and entorhinal cortices, two brain regions with relatively high density of this receptor subtype. 5-HT dose-dependently increases PI turnover (20-80% increase above basal stimulation), with an EC50 of 0.5 and 0.3 microM for fronto-cingulate and entorhinal cortices, respectively. This effect was blocked by the selective 5-HT3 antagonists, BRL 43694 (granisetron), GR 38032F (ondansetron) and ICS 205-930. The selective 5-HT3 receptor agonists, 2-methyl-serotonin (2-Me-5-HT) and phenylbiguanide (PBG), mimicked the action of 5-HT and dose-dependently produced a significant increase in PI turnover (46-76% of the 5-HT response). The stimulatory action of 2-Me-5-HT and phenylbiguanide was blocked completely by granisetron, ondansetron and ICS 205-930 but not by other receptor antagonists such as (+/-)-pindolol (a beta, 5-HT1A and 5-HT1B receptor antagonist), methy-sergide (a 5-HT1 and 5-HT2 receptor antagonist), ritanserin (a 5-HT1C and 5-HT2 receptor antagonist), SR 95103 (gamma-aminobutyric acidA receptor antagonist), scopolamine (a muscarinic antagonist), (-)-eticlopride (a D2 receptor antagonist), SCH 23390 (a D1 5-HT2/1C receptor antagonist) and prazosin (an alpha-1 receptor antagonist). In addition, the stimulation of PI turnover by 2-Me-5-HT was antagonized stereospecifically by the 5-HT3 receptor blocker zacopride. Thus, only the active enantiomer (S)-zacopride, but not the less active enantiomer (R)-zacopride, was effective in blocking the 2-Me-5-HT-induced effect.(ABSTRACT TRUNCATED AT 250 WORDS)

MDMA: further evidence that its action in the medial prefrontal cortex is mediated by the serotonergic system

Systemically administered (+/-)-MDMA (3,4-methylenedioxymethamphetamine, 'Ecstasy') suppressed the firing rates of the majority of neurons in the medial prefrontal cortex (mPFc). The responses of mPFc cells to (+/-)-MDMA is mimicked by (+)-MDMA but not (-)-MDMA. Furthermore, pretreatment with fluoxetine (a specific 5-HT uptake blocker) but not GBR 12909 (a specific dopamine uptake blocker) prevented the suppressant action of MDMA. These data support the notion that the 5-HT system mediates (+/-)-MDMA's action.

Clinical correlation and genetic polymorphism of the human immunodeficiency virus proviral DNA obtained after polymerase chain reaction amplification

Polymerase chain reaction (PCR) was used to amplify a long sequence of human immunodeficiency virus (HIV) DNA, to assess the correlation between PCR signal and clinical stage of disease, and to demonstrate the genotypic variability of different HIV isolates. Twenty-four (96%) of 25 anti-HIV-reactive patients and none of 12 controls were positive for HIV proviral DNA by PCR. After quantification of the PCR signal, a significant difference in the relative amount of HIV proviral DNA per 10(5) peripheral blood mononuclear cells between symptomatic patients (Centers for Disease Control [CDC] class IV) (32,284 +/- 5225 cpm [mean +/- SE], equivalent to 802 HIV plasmid DNA copies) and patients without symptoms (CDC class II/III) (5484 +/- 1469 cpm [mean +/- SE], equivalent to 67 HIV plasmid DNA copies) was observed (P less than .01). Restriction analysis of PCR products in selected samples showed extensive genetic polymorphism between different isolates and more than one viral genotype per isolate. There was a clear correlation between the appearance of clinical symptoms in HIV infection and high levels of viral replication.

Identification of an insertion-sequence-like genetic element in the newly recognized human pathogen Mycoplasma incognitus

Cloned 2.2-kb DNA (plasmid psb-2.2) of Mycoplasma incognitus, a pathogen in AIDS and non-AIDS patients [Lo et al., Am. J. Trop. Med. Hyg. 41 (1989) 364-376; 601-616], contains a 1405-bp genetic element closely resembling bacterial insertion sequence (IS) elements. This IS-like element has 29-bp terminal inverted repeats with seven mismatches, is immediately flanked by 3-bp direct repeats, and has typical stem-and-loop structures at or near both the termini. Two potential open reading frames (ORF-1 and ORF-2) encode 143 amino acids (aa) and 103 aa, respectively, in this IS-like element. Part (57 aa) of the deduced aa sequence of ORF-2 has a significant homology (43%) with the putative transposase of Escherichia coli IS3. In this study, a series of synthetic oligodeoxyribonucleotides each containing a specific sequence of a selected segment in psb-2.2, have been used as probes which reveal that the IS-like element occurs more than ten times in the genome of M. incognitus. This potentially transposable element has many characteristic features in common with bacterial IS elements.

[Immunohistochemical study of thymus in patients with congenital heart disease or rheumatic heart disease]

A series monoclonal antibodies were used to study the intrathymic distribution of T and B cells and the process of intrathymic differentiation of T cells on frozen sections of 14 patients' thymuses by a more sensitive immunohistochemical method. The observation indicated that most of the cortical lymphocytes reacted with Leu 1, Leu 2 a, Leu 3 a and Leu 4 antibodies, thus indicating coexpression of multiple antigen on cortical lymphocytes. In cortex, the numbers of Leu 1 and Leu 4 positive cells were less than medulla. In contrary, the numbers of Leu 2 a and Leu 3 a positive cells in the cortex were more than the medulla: and the medullary thymocytes showed segregation into Leu 2 a+ Leu 3 a- and Leu 3 a+ Leu 2 a- subsets. The ANAE+ and AIG 3+ cells were almost limited to the medulla. Hence, the staining profile of medulla approximated the staining pattern of peripheral T cell subsets, which were programmed for their respective role as helper and suppressor cells. Our results supported the conclusion that the mature T cells presented in the medulla were derived from the immature cells in the cortex. In addition, the expression of Leu 7 was not only limited to the NK cells scattered in the medulla, but also found at the cortical-septa border. On the other hand, a small number of B lymphocytes scattered in the medulla stained with Leu 14, OKB-2, BA-1 and IgM antibodies. The Hassall's corpuscles were cross reaction with the B cell antibodies mentioned above; while the epithelial cells in thymic parenchyma were only stained with IgM antibody. Based on these findings we conclude that the human thymus predominantly consist of T cells, but it also contains a fraction of B cells and epithelial cells.

One year of continuous treatment with haloperidol or clozapine fails to induce a hypersensitive response of caudate putamen neurons to dopamine D1 and D2 receptor agonists

In a "blind" experimental design, the sensitivity of caudate-putamen (CPu) cells to the selective dopamine (DA) D1 receptor agonist SKF-38393 and D2 receptor agonist LY171555 (quinpirole) in rats treated with either haloperidol (HAL), clozapine or tap water for 1 year was compared using the techniques of single cell recording and microiontophoresis. Although the maximum binding value for D2 receptors was elevated in chronic HAL-treated rats, there was no sign of electrophysiological supersensitivity of CPu neurons to the selective DA D1 and D2 receptor agonists. CPu cells were subsensitive to LY-171555 in HAL-treated rats without a drug withdrawal period. This suggests that residual HAL in the rat brain actively blocked the D2 DA receptors. In contrast, in clozapine-treated rats with or without a drug withdrawal period, the sensitivity of CPu cells to either the D1 or D2 agonists was not altered. Coadministration of SKF-38393 and LY-171555 onto the CPu neurons primarily produced an additive effect and only two cells both from the HAL group showed a synergistic action. The majority of CPu cells failed to respond to iontophoretic application of CCK-8S in either the control or antipsychotic drug-treated rats. If these findings can be extended to humans, they do not support the view that tardive dyskinesia is the result of CPu DA receptor supersensitivity.

Genetic and serologic relatedness between Mycoplasma fermentans strains and a mycoplasma recently identified in tissues of AIDS and non-AIDS patients

A mycoplasma previously identified in the tissues of both AIDS and non-AIDS patients dying of an acute fatal disease was earlier shown to share some biologic and genetic properties with a strain of Mycoplasma fermentans, an organism occurring infrequently in the human lower urogenital tract. More extensive genetic and serologic comparisons using DNA/DNA hybridization, DNA base composition (guanine + cytosine), restriction endonuclease DNA analysis, cellular protein patterns and metabolism inhibition serologic procedures confirm that the organism previously designated as "Mycoplasma incognitus" (Mi) is indeed very closely related to strains of M. fermentans. While the genetic and serologic features observed among the newly isolated mycoplasma and two M. fermentans strains suggest a species relationship, it now seems useful to re-examine the biological activities of other freshly isolated M. fermentans strains from man.

Alcohol abuse in patients with dilated cardiomyopathy. Laboratory vs clinical detection

Detection of alcohol abuse is of utmost importance in the diagnosis and management of alcoholic cardiomyopathy. The ability of laboratory tests and clinical signs to detect alcohol abuse was compared in 31 patients with severe heart failure due to underlying dilated cardiomyopathy. Alcoholic cardiomyopathy was diagnosed in 13 patients and a variety of nonalcoholic cardiomyopathies were diagnosed in the remaining 18 patients. At the time of hospital admission, all patients received a complete cardiovascular examination as well as routine hematologic and biochemical tests. Details concerning past and recent alcohol intake were obtained by an individual who was unaware of the diagnostic status of the patients. The two groups of patients did not differ with respect to clinical presentation, self-report of recent drinking patterns, or clinical signs and medical history items that have been found to be associated with chronic alcohol abuse. However, the group with alcoholic cardiomyopathy had significantly higher values for mean corpuscular volume and gamma-glutamyltranspeptidase. Our results suggest that a combination of routine laboratory tests may be effective in the detection of alcohol abuse in patients with dilated cardiomyopathy.

The effect of intraventricular administration of the 5-HT3 receptor agonist 2-methylserotonin on the release of dopamine in the nucleus accumbens: an in vivo chronocoulometric study

In the present study we have examined the effects of the serotonin3 (5-HT3) agonist 2-methylserotonin (2-Me-5HT) on the dopamine (DA) release in the nucleus accumbens (NAc) of rats using in vivo chronocoulometric recording. The intraventricular (i.c.v.) administration of 2-Me-5HT dose-dependently increased the DA release in the NAc. This effect was blocked by the selective 5-HT3 antagonist BRL-43694 (granisetron), but not by the 5-HT1/5-HT2 antagonist metergoline. The i.c.v. injection of 8-hydroxydipropylaminotetraline (8-OHDPAT, a selective 5-HT1a agonist) or (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI, a 5-HT2/5-HT1c agonist) failed to alter the DA release in the NAc. The increase in the DA release produced by 2-Me-5HT was abolished in animals that had received acute bilateral injections of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. Our results suggest that the 2-Me-5HT-induced DA release in the NAc is mediated by 5-HT3 receptors. In addition, 2-Me-5HT induced effect is dependent upon the impulse flow of DA cells.

Chronic BRL 43694, a selective 5-HT3 receptor antagonist, fails to alter the number of spontaneously active midbrain dopamine neurons

In this study, we examined the effect of chronic administration of the selective 5-HT3 receptor antagonist BRL 43694 on the number of spontaneously active A9 (substantia nigra pars compacta) and A10 (ventral tegmental area) dopamine (DA) cells using the technique of extracellular single unit recording. Overall, chronic BRL 43694 (21 days, 5 mg/kg per day or 2.5 mg/kg q.i.d) failed to alter the number of spontaneously active DA cells in either area compared to saline-injected controls. Furthermore, the acute i.v. administration of BRL 43694 did not change A10 DA cell baseline firing rate. These data suggest that if BRL 43694 possesses antipsychotic activity, it is not the result of its action on midbrain DA neurons.

Effects of antipsychotic drugs on 5-HT2 receptors in the medial prefrontal cortex: microiontophoretic studies

Microiontophoretic application (10-80 nA) of the relatively selective serotonin 2 (5-HT2) agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [+/-)-DOI), suppressed medial prefrontal cortical (mPFc) cell's firing rate in a dose-dependent manner. This effect was antagonized by the antipsychotic drugs (APDs) clozapine (CLOZ) and spiperone (SPIP), with CLOZ displaying a greater potency in blocking DOI's action in the mPFc. In contrast, the typical APDs haloperidol (HAL) and L-sulpiride (SUL) failed to block DOI's effect. These results suggest that certain APDs interact with 5-HT2 receptors. Although 5-HT2 antagonism alone may not distinguish typical versus atypical APDs, it is possible that their 5-HT2/dopamine 2 (D2) binding ratio is important.

Electrophysiological characterization of 5-hydroxytryptamine2 receptors in the rat medial prefrontal cortex

The aim of the present study was to characterize 5-hydroxytryptamine2 (5-HT2) receptors in the rat medial prefrontal cortex (mPFc) by single cell recording and microiontophoretic techniques. This was accomplished using 5-HT2 receptor agonists 1-[2,5-dimethoxy-4-iodophenyl]-2-aminopropane [(+/-)-DOI] and 1-[2,5-dimethoxy-4-bromophenyl]-2-aminopropane [(+/-)-DOB]. DOI ejected at a low current (0.5 nA) potentiates glutamate (GLU)-induced activation of mPFc neurons and this effect is blocked by spiperone. At higher currents. DOI invariably inhibits GLU-induced neuronal activity. The microiontophoretic ejection of both DOI and DOB predominantly inhibits spontaneously active mPFc cells. The inhibitory action of DOI on spontaneously active cells is dose-dependent and is blocked by putative 5-HT2 receptor antagonists, with a rank order of potency as follows: ritanserin greater than metergoline approximately LY-53857 greater than spiperone greater than mesulergine greater than mianserin approximately ketanserin. Interestingly, ketanserin and mianserin only weakly block the effect of DOI. The suppressant action of DOI is probably not related to its interaction with 5-HT10 sites as spiperone, which has low affinity for these sites, potently blocks the effect of DOI. The suppressant effect of DOI is not blocked by other receptor antagonists such as BRL-43694 (5-HT3), (+/-)-pindolol (5HT 1a,1b, beta adrenergic, beta), prazosin (adrenergic1, alpha-1), pyrilamine (histamine1, H1), l-sulpiride (dopamine2, D2) or SR 95103 (gamma-aminobutyric acid, GABAA). Overall our results indicate that DOI predominantly inhibits mPFc cells in a direct manner and this effect is mediated by 5-HT2 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of 5-hydroxytryptamine3 receptors in the medial prefrontal cortex: a microiontophoretic study

The microiontophoretic application of the selective 5-hydroxytryptamine3 (5-HT3) agonist 2-methylserotonin suppresses medial prefrontal cortex cell firing. This effect is blocked by the 5-HT3 antagonists BRL 43694 and ICS205930, but not by metergoline or (+/-)-pindolol. Continuous microiontophoretic administration of magnesium chloride or the gamma-aminobutyric acidA antagonist SR 95103 did not alter 2-methylserotonin's suppressant action, suggesting that this effect is direct. Our results suggest that 5-HT3 receptors have a functional role in the medial prefrontal cortex.

Virus-like infectious agent (VLIA) is a novel pathogenic mycoplasma: Mycoplasma incognitus

The newly recognized pathogenic virus-like infectious agent (VLIA), originally reported in patients with AIDS but also known to be pathogenic in previously healthy non-AIDS patients and in non-human primates, was cultured in cell-free conditions using a modified SP-4 medium and classified as a member of the order Mycoplasmatales, class Mollicutes. The infectious microorganism is tentatively referred to as Mycoplasma incognitus. M. incognitus has the unique biochemical properties of utilizing glucose both aerobically and anaerobically, as well as having the ability to metabolize arginine. Among all known human mycoplasmas, these specific biochemical characteristics were found previously only in a rarely isolated species, M. fermentans. In comparison with M. fermentans, M. incognitus appears to be even more fastidious in cultivation requirements and fails to grow in all tested mycoplasma media other than modified SP-4 medium. In addition, M. incognitus grows much more slowly, has a smaller spherical particle size and occasional filamentous morphology, and forms only irregular and very small colonies with diffuse edges on agar plates. Antigenic analysis using polyclonal and monoclonal antibodies and DNA analysis of sequence homology and restriction enzyme mappings in M. incognitus, M. orale, M. hyorhinis, M. hominis, M. pneumoniae, M. fermentans, M. arginini, M. genitalium, M. salivarium, Ureaplasma urealyticum, and Acholeplasma laidlawii revealed that M. incognitus is distinct from other mycoplasmas, but is most closely related to M. fermentans.

Identification of Mycoplasma incognitus infection in patients with AIDS: an immunohistochemical, in situ hybridization and ultrastructural study

Monoclonal antibodies (Mabs) were developed against antigens from a pure culture of Mycoplasma incognitus grown in modified SP-4 medium. All the Mabs obtained were shown to react only with M. incognitus, and not with other species of human mycoplasma. The Mabs identified M. incognitus immunohistologically in thymus, liver, spleen, lymph node, or brain from 22 patients with AIDS, as well as in 2 placentas delivered by patients with AIDS. Using an 35S-labeled DNA probe specific for M. incognitus and in situ hybridization technique, we also identified M. incognitus-specific genetic material in these tissues. Furthermore, ultrastructural studies of the specific areas of tissues which were highly positive for M. incognitus antigens revealed characteristic structures of mycoplasma organisms. These mycoplasma-like particles could be identified intracellularly and extracellularly. Histopathology of the tissues infected by M. incognitus varied from no pathological changes to fulminant necrosis with or without an associated inflammatory reaction. M. incognitus, a novel pathogenic mycoplasma, was cytopathic and cytocidal.

Effects of (+/-)-DOI on medial prefrontal cortical cells: a microiontophoretic study

The relatively selective 5-HT2 receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [+/-)-DOI) ejected by microiontophoresis at low currents potentiates glutamate (GLU)-induced excitation and at higher currents (greater than 20 nA) invariably inhibits both spontaneous and GLU-induced activity of cells in the medial prefrontal cortex (mPFc). The inhibitory action of DOI is blocked by the 5-HT2 antagonists, ritanserin, metergoline and spiperone, but not other receptor antagonists. Microiontophoresis of 1 M Mg2+ for 5-20 min did not alter DOI's inhibitory effect suggesting that DOI's action is a direct one. These results show that DOI predominantly inhibits mPFc neuronal activity and this inhibitory action is mediated by 5-HT2 receptors.

Long-term treatment with antipsychotics does not alter the phosphoinositide response to muscarinic or D2 dopaminergic agonists in rat striatum

The effects of the muscarinic agonist carbachol and the D2 dopaminergic agonist quinpirole on phosphoinositide hydrolysis were studied in the corpus striatum of rats which had been treated for one year with either haloperidol or clozapine. In the presence of LiCl, carbachol increased the accumulation of inositol monophosphate (greater than 100%) and bisphosphate (greater than 20%). Quinpirole had no effect on either basal or carbachol-stimulated accumulation of inositol phosphates. There was no difference in these responses between the drug-treated animals and age-matched controls.

Association of the virus-like infectious agent originally reported in patients with AIDS with acute fatal disease in previously healthy non-AIDS patients

We studied 6 patients from 6 different geographic areas who presented with acute flu-like illnesses. The patients developed persistent fevers, lymphadenopathy or diarrhea, pneumonia, and/or heart, liver, or adrenal failure. They died in 1-7 weeks. These patients had no serological evidence of HIV infection and could not be classified as AIDS patients according to CDC criteria. The clinical signs as well as laboratory and pathological studies of these patients suggested an active infectious process, although no etiological agent was found despite extensive infectious disease work-ups during their hospitalization. Post-mortem examinations showed histopathological lesions of fulminant necrosis involving the lymph nodes, spleen, lungs, liver, adrenal glands, heart, and/or brain. No viral inclusion cells, bacteria, fungi, or parasites could be identified in these tissues using special tissue stains. We report that immunohistochemistry using rabbit antiserum raised against VLIA, the virus-like infectious agent previously identified in patients with AIDS and shown to cause fatal systemic infection in primates, revealed VLIA antigens in these necrotizing lesions. In situ hybridization using an 35S labeled VLIA-specific DNA probe also detected VLIA genetic material in the areas of necrosis. Furthermore, virus-like particles closely resembling VLIA were identified ultrastructurally in these histopathological lesions. VLIA was associated with the systemic necrotizing lesions in these previously healthy non-AIDS patients with an acute fatal disease.

One year treatment with haloperidol or clozapine fails to alter neostriatal D1- and D2-dopamine receptor sensitivity in the rat

Rats were treated continuously with either haloperidol (HAL), clozapine (CLOZ) or tap water for one year. There were no differences between age-matched control and antipsychotic drug (APD) treated groups regarding the effects of the D1-agonist (+)-SKF 38393 or the D2-agonist quinpirole on striatal cAMP content. However, the combination of SKF (10 microM) and quinpirole (1 microM) produced a marked synergistic response in HAL-treated animals as compared to controls. Our data fail to support the hypothesis that APD produce their neurological side effects by inducing D2-receptor hypersensitivity in the basal ganglia. However, the results do suggest that chronic APD treatment alters the interaction between D1- and D2-neostriatal receptors.

Haloperidol and clozapine: differential effects on the sensitivity of caudate-putamen neurons to dopamine agonists and cholecystokinin following one month continuous treatment

The effects of one month continuous treatment with either the typical antipsychotic drug (APD) haloperidol (HAL) or atypical APD clozapine (CLOZ) on the responses of caudate-putamen (CPu) neurons to dopamine (DA) D1 receptor agonist (+)SKF-38393, D2 receptor agonist quinpirole and sulfated cholecystokinin octapeptide (CCK-8S) were compared. The sensitivity of CPu neurons to microiontophoretically applied quinpirole was markedly enhanced in HAL-treated rats; the current (dose)-response curve for quinpirole to suppress the firing activity of CPu cells was shifted significantly to the left as compared to that of saline-treated controls. In addition, in the HAL-treated rats, a higher percentage of CPu neurons responded to quinpirole. In contrast, the responsiveness of CPu cells to quinpirole was not altered in the CLOZ group. Nor was the sensitivity of CPu neurons to selective D1 receptor agonist (+)SKF-38393 changed in APD-treated groups. These results support the view that supersensitive D2 receptors in the CPu may be related to neuroleptic-induced neurological side-effects since the atypical APD CLOZ has low likelihood for causing neurological side-effects and it was ineffective in altering the sensitivity of DA receptor subtypes in the CPu. Interestingly, a greater number of CPu neurons were found to be activated by CCK-8S in CLOZ-treated rats as compared to either the saline-control or HAL group. Whether the enhanced CCK-8S action in the CPu might contribute to CLOZ's low potential for causing neurological side-effects remains to be elucidated.

Validation of a coronary prognostic index for the Chinese--a tale of three cities

In order to confirm the efficacy of a new coronary prognostic index for the prediction of mortality of acute myocardial infarction in the Chinese in general, this index was applied to 886 patients from six general hospitals in Hong Kong (435 patients), Guangzhou (212 patients) and Shanghai (239 patients), respectively. They could be successfully stratified into seven clinical subsets with stepwise increasing mortality. The overall mortality tallied with that predicted by the original coronary prognostic index. The efficacy of this prognostic index for the prediction of mortality from acute myocardial infarction among the Chinese is verified and its application in the objective assessment of patients with acute myocardial infarction is recommended.

Fatal infection of silvered leaf monkeys with a virus-like infectious agent (VLIA) derived from a patient with AIDS

Four silvered leaf monkeys, inoculated with a virus-like infectious agent (VLIA) derived from transformed NIH/3T3 cells (sb51) transfected with Kaposi's sarcoma DNA of an AIDS patient, showed wasting syndromes and died in 7-9 months. Two monkeys had a transient lymphadenopathy in earlier stages. Two moribund animals showed lymphopenia. Although 3 of the VLIA inoculated monkeys had persistent low grade fever early in the infection, the animals became afebrile in the later stages. One VLIA inoculated animal had a prominent antibody response, which occurred 7 months after VLIA inoculation. The other 3 monkeys had a transient or poor antibody response in the later stages. These 3 animals revealed periodic VLIA antigenemia during the course of the experiment. A control monkey was killed 8 months after the last VLIA inoculated monkey succumbed and showed neither an antibody response nor evidence of antigenemia. VLIA-specific DNA could be directly detected in necropsy tissues of all 4 monkeys inoculated with VLIA using the polymerase chain reaction method. VLIA infection was identified in all 4 spleens, 2 of 4 livers, 1 of 2 kidneys, and all 3 brains tested from these 4 animals, but not in the tissues from the control monkey. The necropsy examination of the 4 VLIA inoculated animals revealed no opportunistic infections, acute inflammatory lesions, malignancy or cause of death other than VLIA infection. We believe that the VLIA caused a fatal systemic infection in these monkeys.

[A study of lymphocyte subsets in human normal tonsil and lymph node]

A series of T and B lymphocyte specific monoclonal antibodies was used to determine the localization of lymphocyte subpopulation in frozen and paraffin tissue sections of human normal tonsil and lymph node by means of immunocytochemical technique. In the paracortical and interfollicular area of tonsil and lymph node, most lymphocytes reacted with Leu 1, Leu 3 a, Leu 4 and OKT4. The numbers of Leu 2 a and OKT8 positive cells were rare in tissue. These cells were not only limited in paracortical area, they also appeared in considerable numbers in medullary cords of lymph nodes. Leu 2 a and OKT 8 positive cells decreased with prominent follicular hyperplasia of tonsils. In addition, substantial leu 3 a and Leu 4 cells were found in the germinal centers. This finding supports the importance of these lymphocyte subsets in regulation of human immune response. In the mantle zone of secondary follicles, the majority of lymphocytes were positive for OKB 2 and BA 1, whereas, the IgM positive cells were predominately observed in the cytoplasma and extracellular substance of B lymphocytes in the germinal centers, but the lymphocytes bearing sIgM were rarely observed. In the mantle zone, the IgM were frequently found on the surface of membrane of small lymphocytes, however, the staining intensity was much than that in the germinal centers.

A novel virus-like infectious agent in patients with AIDS

A novel virus-like infectious agent (VLIA), obtained by direct transfection of DNA from Kaposi's sarcoma of a patient with acquired immune deficiency syndrome (AIDS), was transmissible from culture to culture by cell-free filtrate. VLIA contained an outer limiting membrane and had a buoyant density of 1.17-1.20 g/ml in a sucrose gradient. The DNA genome of VLIA was estimated to be greater than 150 kilobase (kb) pairs and carried repetitive sequences. An 8.6 kb pair cloned probe (psb-8.6) and a 2.2 kb pair cloned probe (psb-2.2) of VLIA detected specific sequences in DNA of VLIA infected cells, but not in DNA of uninfected NIH/3T3 cells. By Southern blot hybridization analysis, VLIA was distinct from all known members of human herpes virus, from vaccinia virus, monkey herpes virus saimiri (HVS), and mouse cytomegalovirus (MCMV). Using synthetic primers with the VLIA specific DNA sequences and the polymerase chain reaction (PCR) method, we detected VLIA sequences in DNA isolated from 7 out of 10 patients with AIDS. VLIA infection was identified in spleen, liver, brain, lymph node, Kaposi's sarcoma tissues, or peripheral blood mononuclear cells from these patients, but not in 5 different organs and a tumor from 5 subjects without AIDS. Antiserum raised against VLIA in rabbit positively immunostained brain and lymph node tissues from these AIDS patients.

Cholecystokinin antagonist lorglumide reverses chronic haloperidol-induced effects on dopamine neurons

Intravenous administration of the cholecystokinin (CCK) antagonist lorglumide (LORG) reversed chronic haloperidol (CHAL)-induced depolarization inactivation (DI) of dopamine (DA) cells in both the A9 and A10 areas. Moreover, microinjection of LORG, but not naloxone, directly into the medial nucleus accumbens (mNAc) dose-dependently reversed CHAL-induced effect. LORG injected into other brain regions was without effect. These results suggest that CCK receptors in the mNAc form an important link for maintaining CHAL-induced DI of DA cells and that CCK is involved in the therapeutic action of antipsychotic drugs.

Comparison of effects of D-1 and D-2 dopamine receptor agonists on neurons in the rat caudate putamen: an electrophysiological study

Extracellular single-unit recording and microiontophoretic techniques were used to characterize the pharmacological properties of dopamine (DA) receptor subtypes within the rat caudate putamen (CPu), a striatal structure that receives a dense innervation from DA neurons originating from the substantia nigra pars compacta (A9 DA neurons). Similar to the action of DA, the DA D-1 receptor agonist (+)SKF-38393 generally potentiated the activation produced by glutamate (GLU) at low ejection currents (less than or equal to 5 nA); at higher ejection currents, it depressed 97% of the CPu neurons tested. By contrast, the D-2 receptor agonist LY-171555 (quinpirole) was much less effective in affecting the firing rate of CPu cells. The selective D-1 antagonist SCH-23390, administered either intravenously or iontophoretically, completely blocked the (+)SKF-38393-induced effects on CPu cells but failed to change the depressant effects produced by either quinpirole or 5-HT. On the other hand, the selective D-2 antagonist I-sulpiride, blocked the effects induced by quinpirole but not (+)SKF-38393. These observations suggest that the D-1 and D-2 DA receptor agonists elicit their effects via distinct DA receptor subtypes. A comparison of these results with our previous results obtained from the nucleus accumbens (NAc) indicates that NAc cells are more responsive to DA D-2 agonist, whereas CPu cells are more sensitive to D-1 agonist. Therefore, D-1 receptors in the CPu may have a critical role in mediating the effect produced by DA.(ABSTRACT TRUNCATED AT 400 WORDS)

Disinhibition of nucleus accumbens neurons by the dopamine D2 receptor agonist LY-141865: prevented by 6-OHDA pretreatment

Intravenous administration of LY-141865, a specific dopamine (DA) D2 receptor agonist, caused a biphasic increase/decrease in the firing rate of cells in the rat nucleus accumbens (NAc). 6-Hydroxydopamine injected directly into the medial forebrain bundle, through which the ascending DA fibers pass, prevented the initial rate increase of NAc neurons produced by low doses of LY-141865. In contrast, pretreatment of rats with 5,7-dihydroxytryptamine did not alter the biphasic response of NAc neurons to LY-141865. These results, together with previous findings that D2 autoreceptors are much sensitive to DA and DA agonists, strongly support the hypothesis that the initial rate-increase caused by low doses of LY-141865 is the result of disinhibition.

Chronic treatment with high doses of haloperidol fails to decrease the time course for the development of depolarization inactivation of midbrain dopamine neurons

Using extracellular single unit recording techniques, we investigated the effects produced by chronic treatment with high doses of haloperidol (CHAL, 5 mg/kg/day, s.c.) on midbrain dopamine (DA) neuronal activity. This regimen of HAL treatment produced a time-dependent reduction in the number of spontaneously active DA neurons. Additionally, this dose regimen induced an irregular firing pattern in many of the remaining active DA neurons in both the ventral tegmental area (A10) and substantia nigra pars compacta (A9) regions. These effects were comparable to those obtained previously in rats treated chronically with lower doses of HAL (0.5 mg/kg/day, s.c.). However, there was a greater decrease in the number of spontaneously active DA cells detected in rats treated with high doses of HAL for three weeks compared to those receiving the low doses. On the other hand, higher doses of apomorphine (200 micrograms/kg, i.v.) were required to reverse both the reduction of DA activity and irregular discharge pattern in rats treated chronically with high doses of HAL. In conclusion, the results of the present study substantiate the view that CHAL-induced depolarization inactivation (DI) of DA neurons is a time-dependent process and chronic treatment with high doses of HAL did not shorten the time course required for the development of DI on the majority of midbrain DA neurons.

Possible involvement of the A20-A21 peptide bond in the expression of the biological activity of insulin. 3. [21-Desasparagine,20-cysteine ethylamide-A]insulin and [21-desasparagine,20-cysteine 2,2,2-trifluoroethylamide-A]insulin

We have synthesized [21-desasparagine,20-cysteine ethylamide-A]insulin and [21-desasparagine,20-cysteine 2,2,2-trifluoroethylamide-A]insulin, which differ from natural insulin in that the C-terminal amino residue of the A chain, asparagine, has been removed and the resulting free carboxyl group of the A20 cysteine residue has been converted to an ethylamide and a trifluoroethylamide group, respectively. [21-Desasparagine,20-cysteine ethylamide-A]insulin displayed equivalent potency in receptor binding and biological activity, ca. 12% and ca. 14%, respectively, relative to bovine insulin. In contrast, [21-desasparagine,20-cysteine 2,2,2-trifluoroethylamide-A]insulin displayed a divergence in these properties, ca. 13% in receptor binding and ca. 6% in biological activity. This disparity is ascribed to a difference in the electronic state of the A20-A21 amide bond in these two analogues. A model is proposed to account for the observation of divergence between receptor binding and biological activity in a number of synthetic insulin analogues and naturally occurring insulins. In this model, changes in the electronic state and/or the orientation of the A20-A21 amide bond can modulate biological activity independently of receptor binding affinity. The A20-A21 amide bond is thus considered as an important element in the "message region" of insulin.

Possible involvement of the A20-A21 peptide bond in the expression of the biological activity of insulin. 1. [21-Desasparagine,20-cysteinamide-A]insulin and [21-desasparagine,20-cysteine isopropylamide-A]insulin

The C-terminal region of the A chain of insulin has been shown to play a significant role in the expression of the biological activity of the hormone. To further delineate the contribution of this segment, we have synthesized [21-desasparagine,20-cysteinamide-A]insulin and [21-desasparagine,20-cysteine isopropylamide-A]insulin, in which the C-terminal amino acid residue of the A chain of insulin, asparagine, has been removed and the resulting free carboxyl group of the A20 cysteine residue has been converted to an amide and an isopropylamide, respectively. Both insulin analogues display biological activity, 14-15% for the unsubstituted amide analogue and 20-22% for the isopropylamide analogue, both relative to bovine insulin. In contrast, a [21-desasparagine-A]insulin analogue has been reported to display less than 4% of the activity of the natural hormone [Carpenter, F. (1966) Am. J. Med. 40, 750-758]. The implications of these findings are discussed, and we conclude that the A20-A21 amide bond plays a significant role in the expression of the biological activity of insulin.

Repeated tandem translocations in a clone and subclones of B16-F10 murine melanoma

In one clone and three subclones isolated from the F10 line of the B16 mouse melanoma, a family of extraordinarily long marker chromosomes was found. Banding analyses showed that these long markers represented repeated tandem translocations. Most of these markers exhibited only two or three C-bands. Immunofluorescence staining using antikinetochore serum revealed that these markers had either two active kinetochores or one active and one inactive kinetochore. The original clone and one of the subclones were highly unstable with respect to the composition of the markers and to the ability for retaining the markers. The other two subclones were found to be relatively stable. Because all three subclones were derivatives of one clone, which was unstable, our data suggest that stable genomes can be generated from unstable progenitors.

Spontaneous mutation rates in cloned murine tumors do not correlate with metastatic potential, whereas the prevalence of karyotypic abnormalities in the parental tumors does

We tested the hypothesis that highly malignant cell lines are genomically more unstable than their less malignant counterparts, and that this instability is more pronounced in clones than in cell lines. We compared MDAY-D2 to its non-metastatic variant, D36W25, with regard to (1) the rate of development of ouabain resistance within parallel clones and (2) the prevalence of G-banded karyotypic abnormalities. We detected no significant difference between the spontaneous mutation rates for ouabain resistance. However, the MDAY-D2 cell line possessed both a higher prevalence and greater diversity of chromosomal abnormalities. One possible explanation for these seemingly inconsistent results is that genomic instability may remain essentially constant throughout tumor progression, whereas an accumulation of genetic changes may be responsible for the observed increased prevalence of abnormalities and the development of selective survival advantages during progression.

Rate of generation of major karyotypic abnormalities in relationship to the metastatic potential of B16 murine melanoma

To test the hypothesis that genetic instability correlates with malignant potential, we compared the rate of generation of marker chromosomal abnormalities in clones of B16 F1 and B16 F10 murine melanoma. These rates were estimated through an adaptation of fluctuation analysis of Luria and Delbruck (S. E. Luria and M. Delbruck, Genetics, 28: 491-511, 1943). The highly metastatic F10 line showed the same degree of marker chromosomal instability as the poorly metastatic F1 line (0.01 variants/cell/generation). When subclones of a karyotypically unstable F10 clone were compared with those of a more stable F10 clone, both groups caused the same number of pulmonary metastases, thus demonstrating a further lack of correlation of malignant potential with the level of genomic instability. Since measurements based on marker chromosomes may not truly reflect all of the changes detectable by G-banding, we also analyzed the G-banded karyotypes of the cell lines and their clones (chromatid or chromosomal breaks were not considered in this study). The F10 clones possessed an additional copy of chromosome 1 and also a significantly higher prevalence of the translocation t(9,12) when compared with the F1 clones. Rather than general rates of major karyotypic change determining tumor progression, we suggest the importance of other genetic or epigenetic mechanisms, particularly subtle nonrandom genetic or molecular changes, as the determining factors for malignant potential.

Differential effects of acute clozapine and haloperidol on the activity of ventral tegmental (A10) and nigrostriatal (A9) dopamine neurons

Extracellular single-unit recording techniques were used to evaluate the effects of acute intravenous (i.v.) clozapine (CLOZ) and haloperidol (HAL) on the activity of dopamine (DA) neurons of the ventral tegmental area (VTA or A10) and the substantia nigra pars compacta (SNC or A9). CLOZ increased the firing rate of A10 but not A9 cells, and drove 9/23 (39%) of A10 cells into an apparent depolarization blockade. HAL, on the other hand, produced a rate elevation and, at higher doses, depolarization inactivation in both subpopulations of DA neurons. Cell firing was restored in inactivated cells with i.v. apomorphine (APO) or iontophoretic GABA. CLOZ always fully reversed APO-induced suppression of A10 DA activity, but in many cases only partially reversed suppression of A9 DA neurons. Scopolamine did not mimic the effects of CLOZ on A10 neurons, and it also failed to block the activating effect of HAL on A9 units, indicating that the selective action of CLOZ cannot be interpreted simply by its anticholinergic properties. After hemi-transections of the diencephalon, which severed the medial forebrain bundle and other feedback pathways to the DA somata, CLOZ was still ineffective in altering A9 DA activity. This suggests that the lack of effect on CLOZ on A9 cells is not due to the inhibitory influence of forebrain feedback pathways. This hemi-transection also left intact the activation of A10 neurons produced by HAL and CLOZ, but it did prevent the excitatory action of HAL on most A9 neurons sampled. This indicates that forebrain feedback pathways are less critical in mediating the action of APDs on A10 DA neurons. Finally, iontophoretic application of CLOZ and HAL into the vicinity of DA cell bodies blocked the rate-reducing effects of locally applied DA, but not those of GABA. This suggests that both APDs block somatodendritic DA autoreceptors. However, HAL was considerably more potent than CLOZ in producing this blockade. It is suggested that the different pharmacological and clinical properties of HAL and CLOZ may be partially explained by a differential mode of action on the A10 and A9 subpopulations of DA cells. The data also provide pharmacological evidence that these 2 groups of DA cells are regulated by different mechanisms.

Effects of acute thioridazine, metoclopramide and SCH 23390 on the basal activity of A9 and A10 dopamine cells

Extracellular single-unit recording techniques were employed to examine the effects of various dopamine (DA) antagonists on the basal activity of spontaneously active DA cells. Metoclopramide and thioridazine were both effective in reversing apomorphine-induced suppression of A9 and A10 DA cells. SCH 23390 produced only a partial reversal of this suppression. When the antagonists were given without any pretreatment, thioridazine preferentially increased the firing rate of A10 DA cells, and was relatively ineffective in altering A9 activity. Metoclopramide, on the other hand, increased the activity of most A9 DA cells, but was less effective in doing so with A10 cells. SCH 23390 did not significantly affect the basal activity of either cell subpopulation. These data support the hypothesis that the so-called 'atypical' antipsychotic drugs act preferentially on the A10 DA system. Taken together with previous results, they also suggest that the acute effects of DA antagonists on DA cell subpopulations coincide with their chronic effects.

Failure of subchronic lisuride to modify A10 dopamine autoreceptors' sensitivity

The concept that prolonged treatment with dopamine (DA) mimetics results in a subsensitivity of DA autoreceptors generally is accepted. However, the present study indicates that the administration of a rather specific DA-D2 agonist, lisuride hydrogen maleate (LIS), for one week (200 micrograms/kg/daily) failed to modify the sensitivity of DA autoreceptors of A10 neurons. Indeed, by using extracellular single unit recording in chloral hydrate-anesthetized rats, we observed that neither intravenous apomorphine nor microiontophoresis of DA changed their firing rate-depressant potency when it was estimated at 1 or 3 days after the last LIS injection. A possible interpretation of the results is that the subchronic stimulation of DA-D2 receptors activates an unknown compensatory mechanism which avoids the changes in their sensitivity. Alternatively, the possibility that LIS may also possess antagonistic properties for DA receptors, which might balance the D2 receptors activation, is discussed.

Clonal origin of metastasis in B16 murine melanoma: a cytogenetic study

A cell line isolated from the B16 melanoma and carried in continuous culture for 8 years (the parent line) exhibited great heterogeneity in terms of marker chromosome content. A lung metastasis from a C57BL/6 mouse inoculated im with cells of this line showed karyotypic homogeneity. Inoculation iv of cells from the parent line produced numerous tumor foci in various organs. Cytogenetic analyses of 18 such lesions led to the following conclusions: Cells from each metastatic colony exhibited relatively homogeneous karyotypic characteristics, indicating that metastases are of clonal origin; many parental cells with different marker chromosomes had metastatic potential; and some genomes maintained homogeneity longer than others.

Methylated DNA-binding protein from human placenta recognizes specific methylated sites on several prokaryotic DNAs

Methylated DNA-binding protein (MDBP) from human placenta recognizes specific DNA sequences containing 5-methylcytosine (m5C) residues. Comparisons of binding of various prokaryotic DNAs to MDBP indicate that m5CpG is present in the recognition sites for this protein but is only part of the recognition sequence. Specific binding to MDBP was observed for bacteriophage XP12 DNA, which naturally contains approximately 1/3 of its residues as m5C, and for Micrococcus luteus DNA, M13mp8 replicative form (RF) DNA, and pBR322 when these three DNAs were methylated at CpG sites by human DNA methyltransferase. Five DNA regions binding to MDBP have been localized by DNase I footprinting or restriction mapping in methylated pBR322 and M13mp8 RF DNAs. A comparison of their sequences reveals a common 5'-m5CGRm5CG-3' element or closely related sequence in which one of the m5C residues may be replaced by a T. In addition to this motif, one upstream and one downstream m5CpG as well as other common residues over an approximately 20-bp long region may be recognized by MDBP.

Modulation of cholecystokinin release from posterior nucleus accumbens by D-2 dopamine receptor

The effect of specific D-2 dopamine (DA) receptor agonists and antagonists on potassium (55 mM)-evoked release of cholecystokinin-like immunoreactivity (CCK-LI) was studied in tissue slices of the rat posterior nucleus accumbens (NAc). Incubating the tissue slices in 100 nM or 1 microM of LY-141865, a specific D-2 DA receptor agonist, reduced the release of CCK-LI as indicated by a significant decrease in the S2/S1 ratio. Addition of 10 microM of (-)-sulpiride, a specific D-2 DA receptor antagonist, blocked the inhibitory effect of 100 nM of LY-141865 on the release of CCK-LI. In contrast, 10 microM of the specific D-1 DA receptor antagonist SCH 23390 was unable to attenuate the decrease in release of CCK-LI caused by 100 nM of LY-141865. Furthermore, the active isomer of LY-141865, LY-171555 at 0.1 to 50 nM, also decreased the release of CCK-LI from the tissue slices, while the inactive isomer, LY-181990 at 1 nM, did not affect CCK-LI release. The inhibitory effect of LY-171555 on the release of CCK-LI was lost when its concentration was increased to 100 nM, thus revealing a biphasic effect of D-2 DA receptor stimulation on the release of CCK-LI. These results demonstrate that stimulation of D-2 DA receptor can modulate the release of CCK from in vitro slices of the rat posterior NAc.

Effect of site-specific DNA methylation and mutagenesis on recognition by methylated DNA-binding protein from human placenta

Methylated DNA-binding protein (MDBP) from human placenta is the first protein shown to bind specifically to certain DNA sequences only when they are methylated at cytosine residues. Among the sites recognized by MDBP is pB site 1, a pBR322-derived sequence which has a high affinity for MDBP when methylated at all CpG positions. We have substituted pB site 1 with 5-methyl-cytosine (m5C) residues at one to three of its CpG dinucleotides on one strand by the use of m5C-containing oligonucleotides. MDBP binds best when all three CpG dinucleotides in the region 5'-ATCGTCACGGCGAT-3' are methylated. Even more binding is obtained when both strands are methylated. Alteration of various residues in this binding site by oligonucleotide-directed mutagenesis decreased the binding. However, two mutations which increased the dyad symmetry of part of the binding site yielded ligands with a higher affinity for MDBP.