Excitatory/inhibitory neuronal metabolic balance in mouse hippocampus upon infusion of [U-13C6]glucose

Hippocampus plays a critical role in linking brain energetics and behavior typically associated to stress exposure. In this study, we aimed to simultaneously assess excitatory and inhibitory neuronal metabolism in mouse hippocampus in vivo by applying ¹⁸FDG-PET and indirect ¹³C magnetic resonance spectroscopy (¹H-[¹³C]-MRS) at 14.1 T upon infusion of uniformly ¹³C-labeled glucose ([U-¹³C₆]Glc). Improving the spectral fitting by taking into account variable decoupling efficiencies of [U-¹³C₆]Glc and refining the compartmentalized model by including two γ-aminobutyric acid (GABA) pools permit us to evaluate the relative contributions of glutamatergic and GABAergic metabolism to total hippocampal neuroenergetics. We report that GABAergic activity accounts for ∼13% of total neurotransmission (V_NT) and ∼27% of total neuronal TCA cycle (V_TCA) in mouse hippocampus suggesting a higher V_TCA/V_NT ratio for inhibitory neurons compared to excitatory neurons. Finally, our results provide new strategies and tools for bringing forward the developments and applications of ¹³C-MRS in specific brain regions of small animals.     

Metabotropic glutamate receptor subtypes as targets for neuroprotective drugs.

Metabotropic glutamate (mGlu) receptors have been considered as potential targets for neuroprotective drugs, but the lack of specific drugs has limited the development of neuroprotective strategies in experimental models of acute or chronic central nervous system (CNS) disorders. The advent of potent and centrally available subtype-selective ligands has overcome this limitation, leading to an extensive investigation of the role of mGlu receptor subtypes in neurodegeneration during the last 2 years. Examples of these drugs are the noncompetitive mGlu1 receptor antagonists, CPCCOEt and BAY-36-7620; the noncompetitive mGlu5 receptor antagonists, 2-methyl-6-(phenylethynyl)pyridine, SIB-1893, and SIB-1757; and the potent mGlu2/3 receptor agonists, LY354740 and LY379268. Pharmacologic blockade of mGlu1 or mGlu5 receptors or pharmacologic activation of mGlu2/3 or mGlu4/7/8 receptors produces neuroprotection in a variety of in vitro or in vivo models. MGlu1 receptor antagonists are promising drugs for the treatment of brain ischemia or for the prophylaxis of neuronal damage induced by synaptic hyperactivity. MGlu5 receptor antagonists may limit neuronal damage induced by a hyperactivity of N-methyl-d-aspartate (NMDA) receptors, because mGlu5 and NMDA receptors are physically and functionally connected in neuronal membranes. A series of observations suggest a potential application of mGlu5 receptor antagonists in chronic neurodegenerative disorders, such as amyotrophic lateral sclerosis and Alzheimer disease. MGlu2/3 receptor agonists inhibit glutamate release, but also promote the synthesis and release of neurotrophic factors in astrocytes. These drugs may therefore have a broad application as neuroprotective agents in a variety of CNS disorders. Finally, mGlu4/7/8 receptor agonists potently inhibit glutamate release and have a potential application in seizure disorders. The advantage of all these drugs with respect to NMDA or AMPA receptor agonists derives from the evidence that mGlu receptors do not "mediate," but rather "modulate" excitatory synaptic transmission. Therefore, it can be expected that mGlu receptor ligands are devoid of the undesirable effects resulting from the inhibition of excitatory synaptic transmission, such as sedation or an impairment of learning and memory.     

Therapeutic ultrasound after sciatic nerve compression of Wistar rats

Objectives: The present study analyzed the effect of therapy with therapeutic ultrasound on the sciatic nerve after compression injury, comparing two similar doses of SATA.

Methods: In total, 32 Wistar rats were used, divided into the following groups: CG — control; IG — compression injury of the sciatic nerve; IGCU — injury and continuous ultrasound; and IGPU — injury and 20% pulsed ultrasound. The treatment with ultrasound started on the 3rd postoperative day, with a frequency of 1 MHz, 0.4 W/cm² (SATA) for IGCU. IGPU received 2.0 W/cm² (SATP), with 20% of the active cycle, for 3 minutes. The treatment was performed on a daily basis, totaling 15 days of therapy. Evaluations were performed for functional, histological, and morphometric forms.

Results: Both the Sciatic Functional Index and the withdrawal threshold and grip strength failed to show an advantage of using therapeutic ultrasound. For the morphometric evaluations of nerve fiber diameter and axons, myelin sheath thickness, and G quotient and nerve fiber estimates, IGPU values were estimated to be significantly lower. The morphological analysis revealed intense inflammatory response and neovascularization, as well as degeneration of axons and the myelin sheath, for the injury group and IGCU; however, IGPU showed greater tissue disorganization.

Conclusion: There were no significant differences, showing functional or nocicepitive recovery of the treated groups, including with characteristics pointing to the pulsed group with worse results.     

Physical activity in children and youth in Spain: future actions for obesity prevention

The aim of the study presented here was to determine the relationship between age and certain socioeconomic factors and the effect that physical activity may have on the prevalence of overweight and obesity among Spanish children and adolescents. The sample derived from the enKid study, a cross-sectional study of a representative sample of the Spanish population aged 2–24 years. Body mass index was calculated from measured weight and height. A physical activity questionnaire was administered. Age, socioeconomic level of the families, the mother's level of education, and the geographical area of residence were related to the prevalence of overweight and obesity among Spanish males.     

Diagnosis of tuberculosis lymphadenitis using a polymerase chain reaction on peripheral blood mononuclear cells

Providing prompt and precise laboratory confirmation of a clinical diagnosis of tuberculous lymphadenitis is difficult given the paucibacillary nature of lymph node specimens. In this study carried out in Karachi, Pakistan, a polymerase chain reaction (PCR) assay aimed at detecting Mycobacterium tuberculosis DNA in peripheral blood mononuclear cells (PBMC-PCR) was standardized and compared with standard M. tuberculosis diagnostic techniques or a lymph node PCR (LN-PCR) for the diagnosis of tuberculosis lymphadenitis. Thirty-seven (77%) specimens from 48 patients with clinical or diagnosis of tuberculosis lymphadenitis were positive by cytology [17/48 (35%) with no acid fast bacilli (AFB) (suggestive), and 20/48 (42%) with AFB (positive) in direct smears], 30 (63%) by PBMC-PCR, 16 (33%) by LN-PCR, and 13 (27%) by culture. All controls were negative, with the exception of one false-positive LN-PCR. These data suggest the PBMC-PCR may be helpful in the diagnosis of tuberculous lymphadenitis.     

Long-term treatment with insulin induces apoptosis in brown adipocytes: role of oxidative stress

Trying to define the precise role played by insulin regulating the survival of brown adipocytes, we have used rat fetal brown adipocytes maintained in primary culture. The effect of insulin on apoptosis and the mechanisms involved were assessed. Different from the known effects of insulin as a survival factor, we have found that long-term treatment (72 h) with insulin induces apoptosis in rat fetal brown adipocytes. This process is dependent on the phosphatidylinositol 3-kinase/mammalian target of rapamycin/p70 S6 kinase pathway. Short-term treatment with the conditioned medium from brown adipocytes treated with insulin for 72 h mimicked the apoptotic effect of insulin. During the process, caspase 8 activation, Bid cleavage, cytochrome c release, and activation of caspases 9 and 3 are sequentially produced. Treatment with the caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp (Z-VAD), prevents activation of this apoptotic cascade. The antioxidants, ascorbic acid and superoxide dismutase, also impair this process of apoptosis. Moreover, generation of reactive oxygen species (ROS), probably through reduced nicotinamide adenine dinucleotide phosphate oxidases, and a late decrease in reduced glutathione content are produced. According to this, antioxidants prevent caspase 8 activation and Bid cleavage, suggesting that ROS production is an important event mediating this process of apoptosis. However, the participation of uncoupling protein-1, -2, and -3 regulating ROS is unclear because their levels remain unchanged upon insulin treatment for 72 h. Our data suggest that the prolonged hyperinsulinemia might cause insulin resistance through the loss of brown adipose tissue.     

Brain-derived neurotrophic factor regulates expression of vasoactive intestinal polypeptide in retinal amacrine cells

Brain-derived neurotrophic-factor (BDNF) is expressed in the retina and controls the development of subtypes of amacrine cells. In the present study we investigated the effects of BDNF on amacrine cells expressing vasoactive intestinal polypeptide (VIP). Rats received three intraocular injections of BDNF on postnatal days (P) 16, 18, and 20. The animals were sacrificed on P22, P40, P60, P80, and P120, and VIP expression in their retinas was detected by immunohistochemistry (P22, P40) and by radioimmunoassay (RIA; P22, P40, P60, P80, P120) to assess the time course of BDNF effects on VIP. A significant increase in the density of VIP-positive amacrine cells was detected in BDNF-treated retinas, and VIP concentration was up-regulated by 150% both at P22 and at P40 with respect to untreated controls. VIP concentration then slowly declined in the treated retinas over a period of 3 months; however, a statistically significant increase of 50% was still detectable on P120. The impact of endogenous BDNF on the regulation of VIP expression in the retina was analyzed in mice homozygous for a targeted deletion of the BDNF gene locus (bdnf-/-). VIP immunohistochemistry revealed a marked reduction of VIP-positive amacrine cells and of VIP-immunopositive processes in the inner plexiform layer of the BDNF knockout mice. Mice lacking BDNF expressed only 5% of the VIP protein in their retinas compared with the retinas of wild-type mice as measured by RIA. Our data show that BDNF is a major regulator of VIP expression in retinal amacrine cells and exerts long-lasting effects on VIP content.     

Characterization of an O-glycosylated plaque-associated protein from Alzheimer disease brain

In this work we characterized a 90-kDa glycoprotein from Alzheimer disease (9OAzgp) brain extracts that is recognized by the GalNAc-specific lectin from Amaranthus leucocarpus (ALL), as determined through Western blot. The 90Azgp was purified by electro-elution, and its amino acid sequence determined from peptides obtained after trypsin digestion through MALDI-TOF (Matrix-assisted laser desorption ionization-time of flight), and compared with the relative values obtained from the NCBInr (Swiss-Prot 10/01/2001) database. The 90Azgp showed 32% and 42% homology with the KIAA0310 protein from human brain and the human gastric mucin, respectively. Presence of O-glycosidically linked glycans in the proteins recognized by ALL was confirmed by inhibition of the lectin-glycoprotein interaction through hapten-inhibition assays and also by elimination of the O-glycosidically linked glycans after treatment with O-glycanase from Diplococcus pneumoniae. Electron transmission microscopy confirmed that the receptor recognized by the lectin is processed in the Golgi apparatus of AD neurons. Although the specific role of this glycoprotein has not been identified, considering that the presence of this lectin receptor co-localized with neuritic plaques and in AD sprouting neurons, it could suggest that the O-glycosyl-protein identified by the A. leucocarpus lectin participates in the pathogenesis of neurodegenerative diseases.     

Newborn hearing screening using the evoked otoacoustic emission: The Philippine General Hospital experience

The evoked otoacoustic emission (EOAE) test is a universally well-known and established procedure for screening the hearing of babies during the newborn period. It has been documented in foreign literature that the prevalence of hearing loss is significantly higher in high-risk neonates. In the Philippine General Hospital, 301 high-risk neonates and 105 non high-risk neonates were screened for hearing loss using the EOAE during a period of one year from March 2000 to March 2001. The initial failure rate in the high-risk population was 33% and 11% in the non high-risk population.