Venezuelan Virology Network

In November 2004, sponsored by the World Bank, the Venezuelan Foundation of Science, Technology and Innovation (Fonacit) and the Venezuelan Institute of Scientific Research (IVIC), delegates from the different virology research groups of the country, met in Caracas-Venezuela, with the aim to establish the "Venezuelan Virology Network". The symposium entitled "Molecular biology applied to virus of health importance in Venezuela", was divided into three areas, including human and animals viruses related to public health: 1) Dengue, others arboviruses and Hemorrhagic Fevers; 2) diarrhea-related and others veterinary viruses and 3) Hepatitis, HIV and others sexually transmitted viruses. This symposium allowed the delegates to evaluate the current strengths, weaknesses and needs of the different laboratories, becoming evident the necessity of developing collaborative work between the groups that share the same interests or lines of research; and also their need to exchange technical resources, human and bibliographical material and consequently, avoiding the duplication of efforts and the unnecessary cost of resources. One of the main strengths of Venezuelan virology is the presence, in most laboratories, of researchers with studies of fourth level and multidisciplinary teams of work. We aspire to achieve the raised objectives in the event, to the benefit of our virology and even more important, of our people.     

Alpha-thalassemia/mental retardation syndrome in a 45,X male

An unbalanced Y;autosome translocation leading to a male with a 45,X karyotype is rare with about 30 published cases. A male with a 45,X karyotype as a result of a unique, submicroscopic, unbalanced Y;16 translocation is presented with alpha-thalassemia/mental retardation syndrome.     

Virilizing mature ovarian cystic teratomas

 Three further cases of mature benign cystic teratomas of the ovary associated with virilization are added to the three previously reported in the literature. They were found in postmenopausal, obese, diabetic women aged 52, 61, and 67 years. The patients presented with hirsutism and voice changes and clitoromegaly was present in one. Testosterone and androstenedione levels were elevated but promptly regressed after removal of the tumours. Histologically, sheets of stromal luteinized cells were found peripherally at the interface between the neoplasm and ovarian tissue. Luteinization of ovarian stroma induced by an unknown factor related to diabetes mellitus is the origin of the virilization. Received: 8 January 1997 / Accepted: 28 February 1997     

Control of the cell survival/death decision by cannabinoids

Cannabinoids, the active components of Cannabis sativa (marijuana), and their derivatives produce a wide spectrum of central and peripheral effects, some of which may have clinical application. The discovery of specific cannabinoid receptors and a family of endogenous ligands of those receptors has attracted much attention to cannabinoids in recent years. One of the most exciting and promising areas of current cannabinoid research is the ability of these compounds to control the cell survival/death decision. Thus cannabinoids may induce proliferation, growth arrest, or apoptosis in a number of cells, including neurons, lymphocytes, and various transformed neural and nonneural cells. The variation in drug effects may depend on experimental factors such as drug concentration, timing of drug delivery, and type of cell examined. Regarding the central nervous system, most of the experimental evidence indicates that cannabinoids may protect neurons from toxic insults such as glutamaergic overstimulation, ischemia and oxidative damage. In contrast, cannabinoids induce apoptosis of glioma cells in culture and regression of malignant gliomas in vivo. Breast and prostate cancer cells are also sensitive to cannabinoid-induced antiproliferation. Regarding the immune system, low doses of cannabinoids may enhance cell proliferation, whereas high doses of cannabinoids usually induce growth arrest or apoptosis. The neuroprotective effect of cannabinoids may have potential clinical relevance for the treatment of neurodegenerative disorders such as multiple sclerosis, Parkinson's disease, and ischemia/stroke, whereas their growth-inhibiting action on transformed cells might be useful for the management of malignant brain tumors. Ongoing investigation is in search for cannabinoid-based therapeutic strategies devoid of nondesired psychotropic effects.     

Effects of exercise cessation on lipids and lipoproteins in distance runners and power athletes

Summary The purpose of this study was to determine the effects of short-term exercise cessation on lipid and lipoprotein profile and insulin sensitivity in highly trained runners (n=12; mean age 19.9 years) and power athletes (n=12; mean age 24.4 years). Following 14 days of exercise cessation, running time to exhaustion and maximal oxygen uptake decreased by 9.2% and 4.8% (P < 0.05) in the runners, while in the power athletes one repetition maximum squat and bench press did not change (P>0.05). No changes occurred in body composition. Data from a 2-h oral glucose tolerance test revealed an impairment of the glycemic state in all athletes (P<0.05). In contrast, exercise cessation did not significantly (P>0.05) alter plasma levels of cholesterol, triglycerides, and low density (LDL) and high density lipoprotein (HDL). No changes were observed in HDL₂, HDL_2b, and HDL₃ subfractions, LDL diameter, and qualitative LDL pattern (P>0.05). These data thus suggest that despite a decrease in insulin sensitivity, short-term exercise cessation, independent of exercise mode, was insufficient to alter plasma lipid and lipoprotein profiles in well-trained athletes.     

Tardive dyskinesia on Hungarian psychiatric wards

The authors found tardive dyskinesia (TD) in 23.5% of 200 hospitalized schizophrenic patients, most of whom had received neuroleptic treatment for at least two years. The frequency and severity of TD increased with age, and the more advanced the age at which the patient started taking neuroleptics, the more likely it was that TD would develop. Severe TD was more common in men than in women. Prolonged treatment with neuroleptics or the use of antiparkinsonism drugs increased the risk of TD.     

Trisomy 3 Is Not a Common Feature in Malignant Lymphomas of Mucosa-Associated Lymphoid Tissue Type

The genetic background of extranodal marginal zone B-cell non-Hodgkin’s lymphoma (NHL) of mucosa-associated lymphoid tissue (MALT) type is poorly understood. In contrast to most entities of primary nodal lymphomas, few cytogenetic data are available, and gene rearrangements frequently encountered in and highly characteristic of certain entities of systemic NHL are absent in this type of lymphoma. Recently, it was suggested that MALT-type NHLs are associated with certain numerical chromosome aberrations and especially with trisomy 3. We performed an extensive study using a sensitive double (bicolor) fluorescence in situ hybridization technique for the analysis of trisomies for chromosomes 3, 7, 12, and 18 in 60 samples of low-grade and 45 high-grade MALT-type tumors. In the low-grade cases, trisomy 3 was found in a frequency of only 20%. High-grade lymphomas of MALT type were associated with trisomies 3, 7, 12, and 18 in 36, 20, 18, and 13% of the cases, respectively. Whereas no difference was encountered for trisomy 3 in primary and secondary/simultaneous high-grade lymphomas, +7 and +12 were associated with primary lymphomas, and a +18 was predominantly found in secondary/simultaneous high-grade NHL. These results challenge earlier reports describing a high frequency of +3 in low-grade MALT-type NHL and indicate a possibly different genetic evolution pattern of primary and secondary/simultaneous high-grade lymphomas of primary mucosal origin.     

Histamine H3 receptor activation inhibits dopamine D1 receptor-induced cAMP accumulation in rat striatal slices

In striatal membranes bearing significant levels of histamine H3 receptors (72 +/- 14 fmol/mg protein), the H3 agonist immepip (1 microM) increased [35S]GTPgammaS binding to 119 +/- 2% of basal, an effect prevented by the H3 antagonist clobenpropit and by pre-treatment with pertussis toxin. In slices labelled with [3H]adenine and in the presence of 1 mM isobutylmethylxantine (IBMX), the selective dopamine D1-like (D1/D5) receptor agonist SKF-81297 stimulated cyclic [3H]AMP ([3H]cAMP) accumulation (maximal stimulation 205 +/- 24% of basal, EC50 113 +/- 12 nM), an effect fully blocked by the D1/D5 antagonist SCH-23390. The accumulation of [3H]cAMP induced by 1 microM SKF-81297 was inhibited in a concentration-dependent manner by the selective H3 receptor agonist immepip (maximal inhibition 60+/-5%, IC50 13 +/- 5 nM). The inhibitory action of 100 nM immepip was reversed in a concentration-dependent manner by the H3 antagonist thioperamide (EC50 13 +/- 3 nM, Ki 1.4 +/- 0.3 nM). Forskolin-induced [3H]cAMP accumulation (726 +/- 57% of basal) was also reduced by H3 receptor activation, although to a lesser extent (19.1 +/- 3.2% inhibition), an action not affected by the absence of either IBMX or Ca2+ ions in the incubation medium. Neither the density of [3H]SCH-23390 binding sites (D1 receptors) nor the inhibition by SKF-81297 were affected by 1 microM immepip, ruling out a direct interaction between D1 and H3 receptors. These results indicate that through H3 receptors coupled to Galphai/o proteins, histamine modulates cAMP formation in striatal neurones that possess D1 receptors, most probably GABAergic striato-nigral neurones.