Extracellular HIV-1 Tat protein activates phosphatidylinositol 3- and Akt/PKB kinases in CD4+ T lymphoblastoid Jurkat cells

The biological basis for the pleiotropic activity of extracellular human immunodeficiency virus (HIV)-1 Tat protein on lymphoid T cell survival is not well understood. We have here demonstrated that the addition in culture of 0.1–10 nM Tat protein to 36-h serum-starved lymphoblastoid Jurkat T cells rapidly stimulates the catalytic activity of phosphatidylinositol 3-kinase (PI 3-K). The peak of activation was observed 30 min after Tat addition. Extracellular Tat also stimulated the catalytic activity of the Akt/PKB kinase, a major target of PI 3-K lipid products. Pretreatment of serum-starved Jurkat cells with 100 nM wortmannin (WT) or 10 μM LY294002, two unrelated pharmacological inhibitors of PI 3-K, markedly suppressed the catalytic activity of both PI 3-K and Akt/PKB in Jurkat cells. Moreover, at low concentrations (0.1–1 nM), extracellular Tat showed a small but reproducible protection of Jurkat cells from apoptosis induced by serum deprivation (p < 0.05), while the combination of Tat plus 100 nM WT significantly (p < 0.05) increased the percentage of apoptosis with respect to cells left untreated or treated with Tat alone. Taken together, these data suggest that the anti-apoptotic activity of low concentrations of Tat protein on Jurkat cells is mediated by a PI 3-kinase/Akt pathway.     

Currant allergy and the Rosaceae-grass pollen allergy syndrome: a case report.

BACKGROUND: Despite the increasing use of currants in culinary recipes, currant allergy has rarely been reported. OBJECTIVES: To study a case of currant allergy and to explore cross-reactivity between grass pollen and Rosaceae family fruit allergens. METHODS: Skin prick tests to pollen and skin prick-to-prick tests with currants and peach were performed. Specific IgE levels were determined using the CAP method. We prepared a protein extract of 0.1 mg/mL in phosphate-buffered saline using red currant in the presence of protease inhibitors. Immunoblot inhibition studies were performed to explore cross-reactivity between grass pollen and currant allergens. RESULTS: Skin prick test results were positive to Dactylis, arizonic, and olive pollens. Results of skin prick-to-prick tests with fresh red and black currants were negative and positive, respectively, to peach. The specific IgE level was 5.7 KU/L to red currant and 2.92 KU/L to peach (CAP). Western blot analysis with red currant extract revealed specific IgE protein bands of 37 and 26 kDa. Preincubation of sera with extracts from red currant and peach inhibited both IgE bands, and preincubation with Dactylis pollen inhibited the 37-kDa band only. CONCLUSIONS: We report a case of allergy to grass pollen with an oral allergy syndrome involving several fruits from 2 different families of the Rosidae subclass confirmed by in vitro tests. Inhibition studies demonstrated cross-reactivity between different fruits (currant and raspberry) from the Rosidae subclass and were incomplete with grass pollen allergens.     

Induction of micronucleated cells in the shed skin of salamanders (Ambystoma sp.) treated with colchicine or cyclophosphamide

The micronucleus (MN) assay can be used to detect the genotoxic effects of chemical agents in virtually any cell that divides frequently. Salamanders (Ambystoma sp.) are amphibians that can be easily maintained and bred in the laboratory and spontaneously shed their skin every 2.5-4 days. In this present study, we have evaluated the usefulness of this shed skin for the MN assay. We exposed salamanders to different concentrations of both the aneugen colchicine (COL) and the clastogen cyclophosphamide (CP) and we determined the frequency of micronucleated cells (MNCs) in their sheds. Fragments of shed skin were placed on clean slides, fixed, stained, observed with a light microscope, and the number of MNCs was counted. The MNC frequency was increased significantly by all doses of COL and CP tested, administered either as single or repeated exposures. The presence of MNCs in the shed skin and the speed of sloughing lead us to propose that the sheds of Ambystoma sp., or other amphibians that slough their skin, are suitable alternative models for detecting genotoxic exposures relevant to aquatic environments.     

Short rib-polydactyly syndrome and pericentric inversion of chromosome 4

We report on a newborn infant with clinical and radiological manifestations of some type of short rib-polydactyly syndrome who died soon after birth. Chromosomal studies on peripheral blood lymphocytes and chondrocytes demonstrated an apparently balanced pericentric inversion of chromosome 4 (present in the mother also). This association may have occurred by chance but, if not, the chromosomal breakpoints could interrupt the gene responsible for short rib-polydactyly syndromes, or else be related to the mechanism of short rib-polydactyly syndromes. © 1994 Wiley-Liss, Inc.     

Prevalence of obesity and hyperinsulinemia: its association with serum lipid and lipoprotein concentrations in healthy individuals from Maracaibo,Venezuela

The aim of this study was to analyse the prevalence of obesity and hyperinsulinemia and their association with lipid profile alterations on apparently healthy individuals from Maracaibo, Venezuela. We evaluated 306 men and 41 women, ages ranging from 33 to 65 years. All subjects underwent cardiovascular evaluation and laboratory examination after 10-12 h fasting, for glycaemia, total cholesterol, TG, VLDL-C, LDL-C and HDL-C as well as insulin. Seventy-four percent of men and 56.1% of women showed obesity (BMI > 25 Kg/m2). Men showed high concentrations of TG (48.3%), total cholesterol (40.2%), VLDL-C (48.3%) and LDL-C (33.9%) and low HDL-C levels (48%). The most frequent alteration on the lipid profile in women was high total cholesterol (46%) and LDL-C (51.2%). Men had significantly higher insulin concentrations than women (p < 0.005). After they were classified as obese or non obese, the obese subjects (men and women) showed higher prevalence of lipid profile alterations and insulin concentrations than non obese. The insulin concentration in obese men correlated with BMI, TG, VLDL-C and HDL and, in women with BMI, TG and VLDL-C. In conclusion, a high percentage of men and women in this study showed obesity and this obesity, specially in men, was strongly associated with lipid profile alterations and high insulin concentrations both well known cardiovascular risk factors.     

Fibrinogen stabilizes placental-maternal attachment during embryonic development in the mouse

In humans, maternal fibrinogen (Fg) is required to support pregnancies by maintaining hemostatic balance and stabilizing uteroplacental attachment at the fibrinoid layer found at the fetal-maternal junction. To examine relationships between low Fg levels and early fetal loss, a genetic model of afibrinogenemia was developed. Pregnant mice homozygous for a deletion of the Fg-gamma chain, which results in a total Fg deficiency state (FG(-/-)), aborted the fetuses at the equivalent gestational stage seen in humans. Results obtained from timed matings of FG(-/-) mice showed that vaginal bleeding was initiated as early as embryonic day (E)6 to 7, a critical stage for maternal-fetal vascular development. The condition of afibrinogenemia retarded embryo-placental development, and consistently led to abortion and maternal death at E9.75. Lack of Fg did not alter the extent or distribution pattern of other putative factors of embryo-placental attachment, including laminin, fibronectin, and Factor XIII, indicating that the presence of fibrin(ogen) is required to confer sufficient stability at the placental-decidual interface. The results of these studies demonstrate that maternal Fg plays a critical role in maintenance of pregnancy in mice, both by supporting proper development of fetal-maternal vascular communication and stabilization of embryo implantation.     

Expression of human CD81 in transgenic mice does not confer susceptibility to hepatitis C virus infection

We previously demonstrated that hepatitis C virus (HCV) binds to human CD81 through the E2 glycoprotein. Therefore, expression of the human CD81 molecule in transgenic mice was expected to provide a new tool to study HCV infection in vivo, as the chimpanzee is the only species currently available as a laboratory animal model that can be infected with HCV. We produced transgenic mice expressing the human CD81 protein in a wide variety of tissues. We confirmed binding of recombinant E2 glycoprotein to the liver tissue as well as to thymocytes and splenic lymphocytes in the transgenic mice. We inoculated chimpanzee plasma infected with HCV into these animals. None of these transgenic animals showed evidence of viral replication. Furthermore, human CD81 transgenic mice that lack expression of endogenous mouse CD81 were also resistant to HCV infection. We conclude that expression of human CD81 alone is insufficient to confer susceptibility to HCV infection in the mouse. The presence of additional possible factors for HCV infection is discussed.     

The B-cell activation pathway in human systemic lupus erythematosus: Imbalancedin vitro production of lymphokines and association with serum analytical findings

Recent knowledge of B-lymphocyte physiology has clarified the role of T cell-derived lymphokines in clonal proliferation and differentiation of B-cell responses. Lymphokine production was analyzed in 19 systemic lupus erythematosus (SLE) patients and sex- and age-matched controls in relation to clinical activity and steroid treatment. Whenin vitro production of interleukin-2 (IL-2) and B-cell growth factor (BCGF) was tested, both activities were found to be diminished in the group of patients (P<0.01), while B-cell differentiation factor (BCDF) activity was higher in this group with respect to normal controls (P<0.01). Interestingly enough, thisin vitro BCDF synthesis was positively correlated with clinical activity regardless of low-dose steroid treatment. A correlation was also found between BCDF production and the levels of IgG (r=0.64,P<0.01), anti-DNA antibodies (r=0.52,P<0.05), and the IgG/IgM ratio (r=0.7,P<0.01) in serum. Implications of these abnormal T-lymphocyte functions in SLE with respect toin vivo B-cell function are discussed.     

Dominant negative mutations in the C-propeptide of COL2A1 cause platyspondylic lethal skeletal dysplasia, torrance type, and define a novel subfamily within the type 2 collagenopathies

Platyspondylic lethal skeletal dysplasia (PLSD) Torrance type (PLSD-T) is a rare skeletal dysplasia characterized by platyspondyly, brachydactyly, and metaphyseal changes. Generally a perinatally lethal disease, a few long-term survivors have been reported. Recently, mutations in the carboxy-propeptide of type II collagen have been identified in two patients with PLSD-T, indicating that PLSD-T is a type 2 collagen-associated disorder. We studied eight additional cases of PLSD-T and found that all had mutations in the C-propeptide domain of COL2A1. The mutational spectrum includes missense, stop codon and frameshift mutations. All non-sense mutations were located in the last exon, where they would escape non-sense-mediated RNA-decay. We conclude that PLSD-T is caused by mutations in the C-propeptide domain of COL2A1, which lead to biosynthesis of an altered collagen chain (as opposed to a null allele). Similar mutations have recently been found to be the cause of spondyloperipheral dysplasia, a non-lethal dominant disorder whose clinical and radiographical features overlap those of the rare long-term survivors with PLSD-T. Thus, spondyloperipheral dysplasia and PLSD-T constitute a novel subfamily within the type II collagenopathies, associated with specific mutations in the C-propeptide domain and characterized by distinctive radiological features including metaphyseal changes and brachydactyly that set them apart from other type 2 collagenopathies associated with mutations in the triple-helical domain of COL2A1. The specific phenotype of C-propeptide mutations could result from a combination of diminished collagen fibril formation, toxic effects through the accumulation of unfolded collagen chains inside the chondrocytes, and alteration of a putative signaling function of the carboxy-propeptide of type 2 collagen.