Behavioral effects of aminochrome and dopachrome injected in the rat substantia nigra

The exact mechanism of cell death in neurodegenerative diseases remains obscure, although there is evidence that their pathogenesis may involve the formation of free radicals originating from the oxidative metabolism of catecholamines. The purpose of this study was to evaluate the degree of neurodegenerative changes and behavioral impairments induced by unilateral injection into the rat substantia nigra of cyclized o-quinones, aminochrome and dopachrome, derived from oxidizing dopamine and L-DOPA, respectively, with Mn(3+)-pyrophosphate complex. The behavioral changes were compared with those induced after selective lesions of dopaminergic neurons with 6-hydroxydopamine (6-OHDA). Intranigral injection of aminochrome and dopachrome produced impairment in motor and cognitive behaviors. The behavioral impairment was also revealed by apomorphine-induced rotational asymmetry. Apomorphine (0.5 mg/kg sc) significantly increased rotational behavior in rats injected with aminochrome and dopachrome. These rats presented a clear motor bias showing a significant contralateral rotation activity, similar but less vigorous that in rats injected with 6-OHDA. The avoidance conditioning was seriously impaired in rats injected with aminochrome and dopachrome although only dopachrome-injected rats showed a similar hypomotility to 6-OHDA-injected rats. The behavioral effects were correlated to the extent of striatal tyrosine hydroxylase (TH)-positive fiber loss. Rats receiving unilateral intranigral aminochrome and dopachrome injections exhibited a 47.9+/-5.1% and a 39.7+/-4.4% reduction in nigrostriatal TH-positive fiber density. In conclusion, this study provided evidence that oxidizing DA and L-DOPA to cytotoxic quinones, aminochrome and dopachrome appears to be an important mediator of oxidative damage in vivo.     

Temporal variations of adhesion molecules and matrix metalloproteinases in the course of MS

Thirty patients with clinically isolated syndromes (CIS) were evaluated at the onset of neurological symptoms and when they developed clinically definite MS (CDMS). Surface expression of LFA-1, VLA-4 and intercellular adhesion molecule-1 (ICAM-1) on PBMC and CSF cells was evaluated using flow cytometry. Serum and CSF concentrations of soluble vascular cell adhesion molecules-1 (VCAM-1), ICAM-1 and E-Selectin, as well as MMP-9 and MMP-2 serum concentrations were assayed using ELISA. Surface expression of LFA-1 and VLA-4 molecules on peripheral blood and CSF T cells and monocytes from CIS and CDMS was significantly increased compared with control subjects. Moreover, LFA-1 and VLA-4 expression was significantly higher in patients who developed CDMS compared with those with CIS. Similar changes were observed in the serum levels of MMP-9. Furthermore, patients with CIS and CDMS had significantly higher levels of CSF sVCAM and s-E-Selectin than control subjects. These data suggest that VLA-4, LFA-1 and MMP-9 play a leading role in the evolution of inflammatory demyelinating lesions in patients with CIS who develop CDMS.     

Methodological Challenges in Assessing Children's Mental Health Services Utilization

This paper describes the reliability and validity of the service assessment for children and adolescents (SACA) for use among Spanish-speaking respondents. The test-retest reliability of the instrument was assessed in a randomly selected clinical sample of 146 Puerto Rican children and adolescents aged 4–17. Both parents and children were administered the SACA twice by independent interviewers over an average 12-day follow-up period. The accuracy of parental and youth self-reports was assessed by comparing these reports to information obtained from medical records. The results showed that parents and children (aged 11–17) were able to report with fair to moderate reliability any last year use of mental health services, any outpatient mental health services, and school services. Residential and hospitalization services were reported by both informants with substantial test-retest reliability. Slight or no test-retest reliability was obtained for parent and child on the use of the specific type of mental health professionals, as well as parental reports of several treatment modalities. Substantial sensitivity of the SACA was obtained when comparing medical records to parental and child reports to lifetime use of any service and outpatient mental health service. Moderate sensitivity was obtained for last year use of mental health services for both parent and child informants.     

Antitumor activity of a recombinant soluble betaglycan in human breast cancer xenograft

We have demonstrated previously that ectopic expression of a soluble betaglycan, also known as transforming growth factor (TGF) beta type III receptor, can suppress the malignant properties of human carcinoma cells by antagonizing the tumor-promoting activity of TGF-beta (A. Bandyopadhyay et al., Cancer Res., 59: 5041-5046, 1999). In the current study, we investigated the potential therapeutic utility of a recombinant preparation of human and rat soluble betaglycan (sBG). Purified recombinant human sBG showed similar properties to its rat counterpart (M. M. Vilchis-Landeros et al., Biochem J., 355: 215-222, 2001). It bound TGF-beta with high affinity and isoform selectivity and neutralized the activity of TGF-beta(1) in two bioassays. Peritumoral (50 micro g/tumor, twice a week) or i.p. (100 micro g/animal, every alternate day) injection of sBG into human breast carcinoma MDA-MB-231 xenograft-bearing athymic nude mice significantly inhibited the tumor growth. The administration of sBG also reduced metastatic incidence and colonies in the lungs. The tumor-inhibitory activity of sBG was found to be associated with the inhibition of angiogenesis. Systemic sBG treatment significantly reduced tumor microvessel density detected with histological analyses and CD-31 immunostainings, as well as tumor blood volume measured with hemoglobin content. In an in vitro angiogenesis assay, treatment with the recombinant sBG significantly reduced the ability of human dermal microvascular endothelial cells to form a capillary tube-like structure on Matrigel. These findings support the conclusion that sBG treatment suppresses tumor growth and metastasis, at least in part by inhibiting angiogenesis. As such, it could be a useful therapeutic agent to antagonize the tumor-promoting activity of TGF-beta.     

Okadaic acid induces epileptic seizures and hyperphosphorylation of the NR2B subunit of the NMDA receptor in rat hippocampus in vivo

Overactivation of N-methyl-D-aspartate (NMDA) glutamate receptors is closely related to epilepsy and excitotoxicity, and the phosphorylation of these receptors may facilitate glutamate-mediated synaptic transmission. Here we show that in awake rats the microinjection into the hippocampus of okadaic acid, a potent inhibitor of protein phosphatases 1 and 2A, induces in about 20 min intense electroencephalographic and behavioral limbic-type seizures, which are suppressed by the systemic administration of the NMDA receptor antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclohepten-5,10-imine hydrogen maleate and by the intrahippocampal administration of 1-(5-isoquinolinesulfonyl)-2-methylpiperazine, an inhibitor of protein kinases. Two hours after okadaic acid, when the EEG seizures were intense, an increased serine phosphorylation of some hippocampal proteins, including an enhancement of the serine phosphorylation of the NMDA receptor subunit NR2B, was detected by immunoblotting. Twenty-four hours after okadaic acid a marked destruction of hippocampal CA1 region was observed, which was not prevented by the receptor antagonists. These findings suggest that hyperphosphorylation of glutamate receptors in vivo may result in an increased sensitivity to the endogenous transmitter and therefore induce neuronal hyperexcitability and epilepsy.     

Lyme disease--part I: epidemiology and etiology

Lyme disease (LD) is a tick-borne disease that typically presents with myalgia, fatigue, and a characteristic rash. LD occurs worldwide, and its incidence continues to increase. Prevention and early diagnosis based on increased understanding of disease transmission and pathomechanisms are crucial in stopping LD from progressing to its later stages. In this article, the first of a 2-part series on LD, we review epidemiologic and etiologic factors.     

Neocortical hyperexcitability after GABA withdrawal in vitro

The sharp interruption of the intracortical instillation of exogenous gamma-aminobutyric acid (GABA), generates an epileptic focus in mammals. Seizures elicited by GABA withdrawal last several days or weeks. The present work reports that GABA withdrawal-induced hyperexcitability can be produced in vitro: a sudden withdrawal of GABA (5 mM; 120 min) or benzodiazepine (60 microM flunitrazepam) from the superfusion, induced a gradual increase in the amplitude of the evoked population spike (PS) recorded on neocortical slices. PS enhancement reached 150% above the control value 2.5 h after GABA withdrawal. GABA withdrawal-induced hyperexcitability was facilitated by progesterone. PS enhancement induced by GABA withdrawal was associated with an impairment of GABA transmission occurring before epileptiform discharges were fully established. Paired pulse inhibition and evoked [3H]-GABA release appear decreased; suggesting that cortical hyperexcitability as a result of GABA withdrawal involves pre-synaptic changes. Specific muscimol binding decreased during GABA superfusion but recovered after GABA withdrawal. However, the sensitivity of the post-synaptic response to 3alpha-OH-5alpha-pregnan-20-one or allopregnanolone (alloP) was enhanced after GABA withdrawal, suggesting a functional change in the GABA(A) receptors. The changes described may be the cellular correlates of the withdrawal syndromes appearing after interruption of the administration of GABA(A) receptor agonists.