Tityus perijanensis González-Sponga (Scorpiones, Buthidae): molecular assessment of its geographical distribution and venom lethality of Venezuelan populations.

An extensive field survey allowed us to expand the geographical distribution of the scorpion Tityus perijanensis in the Perijá range, western Zulia State, Venezuela, including areas where adult cases of severe scorpionism have been reported. 16S ribosomal RNA (rRNA) gene sequencing, DL(50) determination, and native PAGE suggest low genetic and venom proteomic divergence across the distribution range. The results also indicate phylogenetic divergence between T. perijanensis and T. discrepans, the species prevalent in northcentral Venezuela. T. perijanensis venom lethality (0.91-0.94 mg/kg) is comparable to that of the Brazilian T. serrulatus and ranks highest among toxic Venezuelan Tityus studied so far. The data indicate that the Perijá range should be included amongst the endemic areas of scorpionism of Venezuela and Colombia.     

Bioimpedance analysis highlights changes in body composition at the early stages of impairment of kidney transplant function.

OBJECTIVE: Kidney transplantation restores renal filtration, although it does not achieve the function of 2 native kidneys, and with time it may involute back to chronic renal failure. We hypothesized that bioelectrical impedance analysis (BIA) might highlight differences for body compartments among kidney transplants (Tx) with different filtration rates. METHODS: Thirty transplantation patients (19 male, 11 female) were studied at 62.4+/-26.6 months postsurgery and were divided into 3 groups: good creatinine clearance (crCl, mL/min/1.73 m2; >65.0), borderline (35.0相似文献   

Osteosarcoma of the craniofacial bones. A clinico-pathological study

Thirty-four cases of osteosarcoma involving the craniofacial bones over a period of 19 years were reviewed. They formed 6.2% of osteosarcomas occurring in the skeleton during the same period at the Tata Memorial Hospital. Mean age of occurrence was 30.9% years, with a range of 7 to 61 years. Male preponderance was noted in maxillary tumours (M:F = 2.6:1), while the mandibular tumours occurred with equal frequency in both sexes. The mandible was the bone of origin in 56%, maxilla in 32% and other craniofacial bones in 12% of patients. Histological sub-type did not affect the prognosis. Radical surgery with resection of adequate disease-free margins is the most effective mode of treatment. Morbidity and mortality is due to extensive local recurrence of disease, particularly with maxillary tumours. Metastasis to other organs occurs rarely. No statistically significant difference in survival was observed between tumours of the mandible and maxilla, or between patients above and below 20 years of age.     

Blockade of K+ channels induced by AMPA/kainate receptor activation in mouse oligodendrocyte precursor cells is mediated by NA+ entry

AMPA/kainate receptor activation in cultured oligodendrocyte precursor cells from embryonic mouse cortex leads to a blockade of delayed rectifying K⁺ currents. In the present study, we provide evidence using the patch-clamp technique in the whole-cell configuration that the mechanism linking kainate receptor activation and K⁺ conductance blockade is due to the receptor-mediated Na⁺ entry: (1) The blockade was not observed in Na⁺ -free bathing solution nor when intracellular [Na⁺] was elevated by dialzying the cell with a pipette solution containing high [Na⁺]. (2) Elevation of intracellular [Na⁺] alone led to a blockade of outward currents in contrast to cells dialyzed by sucrose. High [Li⁺]_i also reduced the outward currents, and in Li⁺-containing bathing solution the kainate-induced blockade of K⁺ channels was more pronounced. Probably, Li⁺ accumulates intracellularly after permeation through the receptor pore due to slower extrusion mechanisms. Experiments with GTPγS or GDPβS and pertussis toxin indicated that GTP-binding protein-mediated mechanisms were not of importance for the kainate-induced K⁺ conductance blockade. Our data suggest that in glial precursor cells AMPA/kainate receptor activation leads to an intracellular [Na⁺] increase which blocks delayed rectifying K⁺ channels. © 1995 Wiley-Liss, Inc.     

Invasive pneumococcal infection in a healthy infant caused by two different serotypes

We present a case of invasive pneumococcal infection in a healthy 10-month-old infant from whom Streptococcus pneumoniae serotype 23F was isolated from the blood and serotype 23B was isolated from the cerebrospinal fluid. Both serotypes were penicillin nonsusceptible. Pulsed-field gel electrophoresis analysis demonstrated that the two serotypes had distinct DNA patterns, indicating that infection did not occur as a result of capsular transformation but as a result of a mixed infection with two distinct pneumococcal serotypes.     

Light-activated ion channels for remote control of neuronal firing

Neurons have ion channels that are directly gated by voltage, ligands and temperature but not by light. Using structure-based design, we have developed a new chemical gate that confers light sensitivity to an ion channel. The gate includes a functional group for selective conjugation to an engineered K(+) channel, a pore blocker and a photoisomerizable azobenzene. Long-wavelength light drives the azobenzene moiety into its extended trans configuration, allowing the blocker to reach the pore. Short-wavelength light generates the shorter cis configuration, retracting the blocker and allowing conduction. Exogenous expression of these channels in rat hippocampal neurons, followed by chemical modification with the photoswitchable gate, enables different wavelengths of light to switch action potential firing on and off. These synthetic photoisomerizable azobenzene-regulated K(+) (SPARK) channels allow rapid, precise and reversible control over neuronal firing, with potential applications for dissecting neural circuits and controlling activity downstream from sites of neural damage or degeneration.