Cerebellar neurones: Differentiation and modulation of sensitivity to excitotoxic treatment

The neurite outgrowth and adhesion complex (NOAC), isolated from rabbit sera has been dissociated in its major components by reverse-phase chromatography in HPLC by using a C₁₈ column. SDS-PAGE analisys of the active fractions revealed the presence of three major bands of approximately 100, 70 and 50 kDa. Studies on the biological activity of NOAC were carried out on rat cerebellar granule cells. NOAC-cultured cells exhibit a marked resistance to excitotoxic stimuli carried by glutamate.     

Astronotus ocellatus (Cichlidae:Pisces) and Macropodus opercularis (Anabatidae:Pisces) as predators of immature Aedes fluviatilis (Diptera:Culicidae) and Biomphalaria glabrata (Mollusca:Planorbidae).

Two fish species, Astronotus ocellatus (Cichlidae) and Macropodus opercularis (Anabatidae) were tested for predacious behavior toward immature mosquitoes (Aedes fluviatilis, Diptera:Culicidae) and schistosomiasis snail hosts (Biomphalaria glabrata, Mollusca:Planorbidae), in the presence or absence of non-living food and in laboratory conditions. A. ocellatus, a species indigenous to Brazil, was a very efficient predator of both organisms (alpha = 0.05); M. opercularis, an exotic species, preyed well on immature mosquitoes, but small snails and snail egg-masses were ingested only irregularly. Both fish species seemed to prefer live to non-living food.     

Blood sugar control in diabetic patients bearing microinfusors: the importance of the dawn phenomenon

Significant early morning hyperglycemia (the so-called "dawn phenomenon") has been observed in insulin-dependent diabetics who were otherwise well controlled. This phenomenon, if present, could lead to errors in adapting the basal insulin infusion in CSII treated diabetic patients, because a normal glucose level in the morning could be associated with asymptomatic hypoglycemic values in the night. In order to observe the occurrence and to quantify the magnitude of this phenomenon 14 well controlled CSII-treated type I diabetics were hospitalized for 1 night and samples for the determination of blood glucose (14 patients) and serum cortisol, free insulin and NEFA (8 patients) were drawn at 24.00, 02.00, 04.00, 06.00, 08.00 h. Blood glucose values were slightly but significantly higher at 06.00 than at 02.00 (106 +/- 7.92 v.s. 88.57 +/- 7.02 mg/dl, p less than 0.025, paired Student t test) while serum free insulin values decreased from midnight to 02.00 and then they remained stable. It is concluded that the small increase of blood glucose values in the morning is not a major clinical problem in CSII treated diabetic patients.     

Modifications in the oscillation of substrates in obese subjects subjected to variations in the pattern of meal-timing

In a group of obese subjects kept on hypocaloric diet during a period of 18 days, an eventual different behaviour of carbohydrates and lipids oxidation following to meal-timing manipulation (a single meal given only at 10.00 hr or at 18.00 hr of each day) has been studied by indirect calorimetry. No significant difference of body weight reduction was noticed in both dietetic regimens. In the group of obese subjects who consumed the single meal at 10.00, a slight increase of carbohydrates oxidation was noticed, without a statistical significance, whereas in the group with single meal at 18.00 h a significant increase of lipids oxidation resulted.     

Distribution of the molossinus allele of Sry, the testis-determining gene, in wild mice

When the Y chromosome of the laboratory inbred mouse strain C57BL/6 (B6) is replaced by the Y of certain strains of Mus musculus domesticus, testis determination fails and all XY fetuses develop either as hermaphrodites or XY females (XY sex reversal). This suggests the presence of at least two alleles of Sry, the male-determining gene on the Y:M. m. domesticus and B6. The B6 Y chromosome is derived from the Japanese house mouse, M. m. molossinus and therefore carries a molossinus Sry allele. As a first step to determine how the molossinus Sry allele evolved, its distribution pattern was determined in wild mice. The cumulative data of 96 M. musculus samples obtained from 58 geographical locations in Europe, North Africa, and Asia show the molossinus Sry allele is restricted to Japan and the neighboring Asian mainland and confirm that Japanese M. m. molossinus mice were derived in part from a race of M. m. musculus from Korea or Manchuria. Sry polymorphisms, as illustrated by the molossinus Sry allele, can serve as molecular markers for studies on the evolution of wild M. musculus populations and can help determine the role sex determination plays in speciation.      

Mechanisms of uremic erythrocyte-induced adhesion of human monocytes to cultured endothelial cells

In end-stage renal disease (ESRD) endothelium may represent a key target for the action of circulating elements, such as modified erythrocytes (RBC) and/or plasmatic factors, that may facilitate inflammation and the vasculopathy associated with uremia. We have previously demonstrated that phosphatidylserine (PS) exposure on the surface of RBC from ESRD patients increases RBC-human umbilical vein endothelial cell (HUVEC) interactions and causes decreased nitric oxide (NO) production. We postulated that, besides the pro-inflammatory effects due to decreased NO bio-availability, enhanced ESRD-RBC-HUVEC interactions might directly stimulate pro-inflammatory pathways leading to increased vascular adhesion molecule expression. ESRD-RBC-endothelial cell interactions induced a time-dependent up-regulation of VCAM-1 and ICAM-1 (measured by Western blot (WB) and real-time PCR), associated with mitogen-activated protein kinase (MAPK) activation and impairment of the Akt/endothelial nitric oxide synthase (eNOS) signaling cascade, measured by WB. In reconstitution experiments, normal RBC incubated with uremic plasma showed increased PS exposure and significantly increased VCAM-1 and ICAM-1 mRNA levels when incubated on HUVEC. Interestingly, ESRD-RBC induced increased expression of adhesion molecules was prevented by Annexin-V (AnV, able to mask PS on RBC surface), anti-integrin-alpha(v)beta3, anti-thrombospondin-1 (TSP-1), and PD98059 (a selective inhibitor of MAPK phosphorylation). Moreover, AnV reversed the ESRD-RBC effects on MAPK and Akt/eNOS signaling pathways. Our data demonstrate that, possibly via a direct interaction with the endothelial thrombospondin-(alpha(v)beta3) integrin complex, ESRD-RBC-HUVEC adhesion induces a vascular inflammatory phenotype. Thus, intervention targeting ESRD-RBC increased adhesion to endothelium and/or MAPK and Akt/eNOS pathways may have the potential to prevent vascular lesions under uremic conditions.     

Chromatin,gene silencing and HIV latency

One of the cellular defenses against virus infection is the silencing of viral gene expression. There is evidence that at least two gene-silencing mechanisms are used against the human immuno-deficiency virus (HIV). Paradoxically, this cellular defense mechanism contributes to viral latency and persistence, and we review here the relationship of viral latency to gene-silencing mechanisms.     

Modelling of the ABL and ARG proteins predicts two functionally critical regions that are natively unfolded

The ABL and ARG tyrosine kinases regulate many pivotal cellular processes and are implicated in the pathogenesis of several forms of leukemia. We have modelled the previously uncharacterized core domain (SH3-SH2-tyrosine kinase) and C-terminal actin-binding domain of ARG. We have also investigated the structural arrangement of the ABL and ARG Cap region and of the long multifunctional region located downstream of the tyrosine kinase domain. We report that the ARG core domain is homologous to the corresponding ABL region, therefore suggesting that ARG catalytic activity is likely regulated by the same SH3-SH2 clamp described for ABL. We also report that the Cap of both ABL and ARG is natively unfolded. Hence, biological events determining the folding of the Cap are critical to allow its interaction with the tyrosine kinase C-lobe. Furthermore, our results show that, with the exception of the C-terminal actin-binding domain, the entire region encoded by the ABL and ARG last exon is natively unfolded. Phosphorylation events or protein-protein interactions regulating the folding of this region will therefore modulate the activity of its numerous functional domains. Finally, our analyses show that the C-terminal actin-binding domain of ARG displays a four-helix bundle structure similar to the one reported for the corresponding ABL region. Our findings imply that many biological activities attributed to ABL, ARG, and their oncogenic counterparts are regulated by natively unfolded regions.     

Assessment of genetic diversity in Brazilian barley using SSR markers

Barley is a major cereal grown widely and used in several food products, beverage production and animal fodder. Genetic diversity is a key component in breeding programs. We have analyzed the genetic diversity of barley accessions using microsatellite markers. The accessions were composed of wild and domesticated barley representing genotypes from six countries and three breeding programs in Brazil. A total of 280 alleles were detected, 36 unique to Brazilian barley. The marker Bmag120 showed the greatest polymorphism information content (PIC), with the highest mean value found on chromosome three, and the lowest on chromosomes four and six. The wild accessions presented the highest diversity followed by the foreign genotypes. Genetic analysis was performed using Principal Coordinates Analysis, UPGMA clustering, and Bayesian clustering analysis implemented in Structure. All results obtained by the different methods were similar. Loss of genetic diversity has occurred in Brazilian genotypes. The number of alleles detected in genotypes released in 1980s was higher, whereas most of the cultivars released thereafter showed lower PIC and clustered in separate subgroups from the older cultivars. The use of a more diverse panel of genotypes should be considered in order to exploit novel alleles in Brazilian barley breeding programs.