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Biomedical subjects

J J Byrnes

Publications and source records attributed to J J Byrnes.

At least 19 recordsLinked to original sources
PubMed2001

Increased sensitivity of dopamine systems following reproductive experience in rats.

Several studies have suggested that alterations in forebrain dopamine activity during the postpartum period may result in the onset of postpartum psychosis in women [J. Psychosom. Obstet. Gynecol. 19 (1998) 104; Prog. Neuro-Psychopharmacol. Biol. Psychiatry 17 (1993) 571; J. Clin. Psychiatry 51 (1990) 365.]. The present study investigated whether increased dopamine activity in these forebrain regions is a normal consequence of reproductive experience in rodents. Both intact and ovariectomized parous and nulliparous females were tested for their responses to the dopamine agonist apomorphine using two behavioral measures, prepulse inhibition (PPI) and oral stereotypy. In addition, dopamine and DOPAC levels were measured in tissue from the striatum and nucleus accumbens together with circulating plasma prolactin levels. The results of the behavioral studies demonstrate an increased response to apomorphine in parous females. Parous subjects also had increased levels of dopamine and DOPAC in striatal tissue and lower levels of circulating prolactin. Ovariectomy in nulliparous females resulted in a potentiated response to apomorphine with regard to the disruption of PPI, as well as a significant decrease in the plasma prolactin levels, as compared with intact nulliparous females. These data suggest that increased dopamine activity in forebrain regions occurs as a consequence of parity, which persists for a minimum of several weeks postpartum. These findings support the hypothesis that increased dopamine sensitivity in forebrain dopamine regions may be one potential mechanism underlying the development of postpartum psychosis in women.

Animals↗
PubMed2000

Inhibition of nitric oxide synthase in the ventral tegmental area attenuates cocaine sensitization in rats.

1. Male Sprague-Dawley rats were pretreated via bilateral infusion of the VTA with the selective neuronal nitric oxide synthase inhibitor, 7-nitroindazole (0, 8, or 40 ng/hemisphere), prior to each of 7 daily systemic cocaine (30 mg/kg, i.p.) or saline (1 ml/kg) treatments. 2. After a 7-day treatment withdrawal period, rats received a final systemic challenge with either cocaine (30 mg/kg, i.p.) or saline (1 ml/kg). 3. Locomotor and stereotypic activity were measured following the first and last treatments. 4. Daily cocaine treatment led to the development of sensitization to its stereotypic effects as revealed upon drug challenge. 5. The development of sensitization of cocaine-induced stereotypy was completely blocked by daily intra-VTA pretreatment with 7-nitroindazole. 6. In addition, attenuation of the locomotor effects of cocaine challenge was also observed in animals that received daily intra-VTA 7-nitroindazole (40 ng/hemisphere) infusions. 7. The results indicate that VTA nitric oxide is necessary for the development of sensitization of cocaine-induced stereotypic behavior, and that its repeated inhibition may produce lasting effects on the locomotor response to the drug.

Animals↗
PubMed2000

The disruptive effect of cocaine on prepulse inhibition is prevented by repeated administration in rats.

These experiments tested the hypothesis that pretreatment with a behaviorally sensitizing regimen of cocaine alters the ability of cocaine to disrupt prepulse inhibition (PPI). Male Sprague-Dawley rats were treated with cocaine (30 mg/kg, i.p.) or saline vehicle for seven consecutive days followed by challenge treatment seven days later. Repeated cocaine treatment produced sensitization of stereotyped activity. Cocaine challenge following repeated vehicle treatment significantly reduced PPI, but this effect was completely abolished by repeated cocaine treatment. These data suggest that neuroadaptation following repeated treatment might prevent PPI disruption caused by psychomotor stimulants.

Animals↗
PubMed2000

Green tea polyphenols induce apoptosis in vitro in peripheral blood T lymphocytes of adult T-cell leukemia patients.

Green tea polyphenols (TEA) are known to exhibit antioxidative activity as well as tumor-suppressing activity. In order to examine the tumor-suppressing activity of TEA against adult T-cell leukemia (ATL), we cultivated peripheral blood T lymphocytes of ATL patients (ATL PBLs), an HTLV-I-infected T-cell line (KODV) and healthy controls (normal PBLs) for 3 days in the presence of TEA and its main constituent, epigallocatechin-3-gallate (EGCg), to measure cell proliferation and apoptosis, and to quantitate mRNAs of HTLV-I pX and beta-actin genes of the cultured cells. Growth of ATL PBLs was significantly inhibited by 9-27 microg/ml of TEA and EGCg, in contrast to minimal growth inhibition of T cells of normal PBLs. Inhibition of KODV was intermediate between ATL PBLs and normal PBLs. The ATL PBLs and KODV treated with 27 microg/ml of either TEA or EGCg induced apoptotic DNA fragmentation, producing terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells, while the normal PBLs treated with the same concentration of TEA or EGCg produced a negligibly small number of TUNEL-positive cells, in which apoptotic DNA fragmentation was not detectable. Expression of HTLV-I pX mRNA was suppressed more than 90% in ATL PBLs by treatment with 3-27 microg/ml of either TEA or EGCg, while expression of beta-actin mRNA was much less suppressed by treatment with the same concentration of TEA or EGCg. These results indicate that TEA and EGCg inhibit growth of ATL PBLs, as well as HTLV-I-infected T-cells, by suppressing HTLV-I pX gene expression and inducing apoptotic cell death.

Adult↗
PubMed1998

Detection of HTLV-1 by polymerase chain reaction in situ hybridization in adult T-cell leukemia/lymphoma.

A method for nonradioactive polymerase chain reaction in situ hybridization was developed and used to determine the distribution of human T-lymphotropic virus type I (HTLV-I) proviral DNA in paraffin-embedded surgical specimens of adult T-cell leukemia/lymphoma (ATLL). As controls, we used biopsy samples of five cases of mycosis fungoides, cells of an HTLV-I-infected cell line (MT2), as well as HTLV-1-negative cells (YAS). We successfully detected the amplicon of the HTLV-1 tax sequence in the nuclei of the cutaneous infiltrating lymphoid cells in 90% (9/10) of ATLL cases. Studies also revealed the existence of HTLV-1 provirus DNA in nuclei of sweat gland epithelial cells and vascular endothelial cells as well as lymphoid cells in ATLL patients. Mycosis fungoides and YAS cells were negative for the HTLV-I tax sequence, but MT2 cells were strongly positive. The results indicated that this technique was more sensitive in detecting intracellular amplicons than was the previous in situ hybridization method. Through its use, we were able to easily determine the distribution of HTLV-I-positive cells among the various cells and tissues of paraffin-embedded archival materials.

Adult↗
PubMed1997

Amphetamine-induced sensitization and release of dopamine in slices from the ventral tegmental area of rats is enhanced following administration of cholera toxin into the ventral tegmental area.

Administration of cholera toxin (CTX) into the ventral tegmental area (VTA) markedly potentiates the development of behavioral sensitization to amphetamine. Experiments were conducted to determine whether this phenomenon is associated with altered dopamine release from the VTA and nucleus accumbens (NAC). Adult, male rats received bilateral injections of CTX (0-1 microgram) or its vehicle into the VTA. Half of the animals then received four injections of amphetamine (0.5 mg/kg, i.p.) given every other day, while the other half received no additional treatments. In both groups, locomotor responses to amphetamine (0.5 mg/kg, i.p.) were measured on experimental day 18. One day later, amphetamine-induced [3H]dopamine release was measured in tissue slices of the VTA and NAC. Amphetamine-induced locomotor activity was augmented in rats receiving 0.5 or 1.0 microgram intra-VTA CTX pretreatment and the repeated amphetamine regimen. Amphetamine-induced [3H]dopamine release was increased from VTA but not NAC slices obtained from animals showing this behavioral sensitization. Thus, intra-VTA CTX treatment facilitates sensitization to low doses of repeated amphetamine which appears to be associated with the increased ability of this psychostimulant to release dopamine in the VTA.

Amphetamine↗
PubMed1997

Robust sensitization to amphetamine following intra-VTA cholera toxin administration.

Studies were conducted regarding the hypothesis that enhanced cAMP formation in the ventral tegmental area (VTA) affects the magnitude of the behavioral responses elicited by psychostimulant drugs. In the first paradigm, spontaneous and amphetamine-elicited locomotor activity was measured at various times following injection of cholera toxin (CTX), a known activator of adenylate cyclase, into the VTA. Adult male rats showed enhanced amphetamine-stimulated locomotor activity when tested 1 or 3 days after treatment with 0.5 microgram CTX into the VTA. Spontaneous activity was markedly increased 1 and 3 days following treatment with the higher dose of 1.0 microgram CTX into the VTA, and amphetamine was still capable of eliciting an increased level of locomotor activity above this high baseline. Using a paradigm in which repeated amphetamine injections were given on an intermittent schedule following injection of CTX into the VTA, it was observed that a single low dose of amphetamine (0.5 mg/kg) given 1 day after CTX (0.5 microgram) injection into the VTA led to a markedly potentiated locomotor activity response to subsequent treatment with amphetamine. Evaluation of this protocol (initial amphetamine dose 24 h after CTX injection, and challenge treatment of amphetamine at various times thereafter) showed that the sensitization was long-lasting and could be observed after an initial dose of amphetamine as low as 0.1 mg/kg. A sensitized response was also expressed when the challenge dose was given directly into the nucleus accumbens. These data suggest that injection of CTX into the VTA enhances the induction of locomotor sensitization to amphetamine.

Adenylyl Cyclases↗
PubMed1997

Protection from apoptotic cell death by interleukin-4 is increased in previously treated chronic lymphocytic leukemia patients.

Chronic lymphocytic leukemia (CLL) cells were cultured in a medium supplemented with 0.01-1 ng/ml interleukin-4 (IL-4) for 18 h, fixed and analyzed on a flow cytometer. The percentage of apoptotic (AP) cells with hypodiploid DNA content was determined from DNA histograms. IL-4 at 0.01 ng/ml protected from spontaneous apoptosis of cells from previously treated CLL patients, but had very little effect on apoptotic death in cultures of cells from untreated patients. The number of AP cells in the absence of IL-4 was similar in cultures from treated and untreated patients. The concentration of IL-4 which inhibited spontaneous apoptosis by 50% was less than 0.01 ng/ml for pretreated patients and close to 1 ng/ml for untreated patients. Stage of the disease had no effect on the level of spontaneous apoptosis and its sensitivity to IL-4. Protection from apoptosis by IL-4 was not accompanied by the upregulation of bcl-2 protein. The number of AP cells in methylprednisolone hemisuccinate (MP) treated cultures from previously treated patients was significantly lower than in cultures from untreated patients in the presence of 0.01-1.0 ng/ml IL-4. Treatment with the combination L-phenylalanine mustard (L-PAM)+ fludarabine induced synergistic apoptotic response. Apoptosis induced by this combination was relatively resistant to IL-4 in patients treated with chlorambucil and prednisone, but not in patients previously treated with fludarabine. Protection from cytotoxicity by IL-4 may be one of the mechanisms of acquired drug resistance in CLL.

Adult↗
PubMed1997

Comparison of sensitization elicited by amphetamine and pertussis toxin: characterization of locomotor behavior and limbic dopamine release.

1. Male, Sprague-Dawley rats were pretreated with one of several regimens of repeated, intermittent amphetamine or with a single-dose of intra-VTA pertussis toxin (PTX). 2. An amphetamine challenge dose (0.5 mg/kg, i.p.) produced increased locomotor activity in both amphetamine and pertussis toxin-pretreated rats. 3. The magnitude of activity in PTX pretreated rats exceeded 5-fold that of the amphetamine-pretreated rats. 4. There were no significant differences in the levels of sensitized behavior elicited by 4 distinct amphetamine pretreatment protocols. 5. Neither of the drug pretreatments caused significant changes in the ability of 10 microM amphetamine to promote dopamine efflux from nucleus accumbens or striatal tissue in vitro. 6. The sensitized behaviour cannot be explained by in vitro alterations in pre-synaptic dopamine release, which may suggest an up-regulation of post-synaptic activity.

Amphetamine↗
PubMed1997

Adult T-cell leukemia/lymphoma associated with noninfectious epithelioid granuloma in the skin: a clinicopathologic study.

Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) are infrequently associated with noninfectious granulomas in involved or noninvolved organs. Adult T-cell leukemia/lymphoma (ATLL) is an aggressive lymphoproliferative neoplasm associated with T-lymphotropic virus type 1 (HTLV-1). We describe a case of cutaneous type ATLL, affecting mainly the skin as a maculopapular eruption, in which some skin biopsies contained epithelioid cell granulomas in the lymphoma cutis (ATLL) lesion. These Lennert's-like epithelioid clusters were also present in lymph nodes, which showed some degree of invasion by the ATLL lymphocytes. Although prognosis of ATLL is generally poor, our patient has had a less aggressive course, with a survival time to date of 13 years. Our findings suggest that the presence of epithelioid granulomata in an ATLL patient may be a manifestation of a host response which confers some protection against the disease progression. To our knowledge, this is the first report of a case of ATLL with a noninfectious granuloma similar to a Lennert's lesion.

Connective Tissue Diseases↗
PubMed1996

Thrombotic microangiopathies associated with drugs and bone marrow transplantation.

This type of thrombotic microangiopathy more commonly resembles the hemolytic-uremic syndrome (HUS) than thrombotic thrombocytopenic purpura (TTP). The syndrome has been associated with the use of cyclosporin, mitomycin C, combinations of other chemotherapeutic and immunosuppressive agents, and total body irradiation. Endothelial cell injury and von Willebrand factor may be involved in pathogenesis of the intravascular platelet aggregation and tissue (especially renal) ischemia and infarction that characterize the entity. The most effective therapy for thrombotic microangiopathy associated with drugs and bone marrow transplantation has not been determined.

Antineoplastic Agents↗