Evidence that luminant and equiluminant motion signals are integrated by directionally selective mechanisms

Three experiments tested whether motion information for nonequiluminant (luminant) and equiluminant dots affects direction judgments when both types of stimuli are moving simultaneously in the same display. The motion directions for the two sets of dots were manipulated to produce four direction differences (0 degrees, 30 degrees, 60 degrees, and 90 degrees). The equiluminant dots were moved in a perfectly correlated fashion, but the percentage of correlated motion for the luminant dots was varied. When subjects judged whether the directions of the equiluminant and luminant dots were the same or different, performance for the conditions with 0 degrees, 60 degrees, and 90 degrees difference improved as the percentage of correlated luminant motion increased. The same result occurred for a control display that contained two sets of luminant dots. However, for the 30 degrees difference, performance was at chance level for the control display, but dropped below chance for the equiluminant-luminant display. When subjects indicated just the direction of the luminant dots, judgments were not affected by equiluminant motion. Judgments for the equiluminant dots also were accurate, except for the conditions with 30 degrees difference; these responses were biased by the luminant motion, indicating some form of motion capture. The interactive effects are discussed in terms of a directionally selective mechanism that combines equiluminant and luminant motion signals.     

Aedes albopictus and Ae. triseriatus eggs survive waste tire processing

Tires that were either crudely chopped or more finely processed into shreds contained viable eggs. Field-collected remnants of 2-3 chopped tires contained viable Aedes albopictus eggs. After shredding tires seeded with mosquito eggs, 34 (4.6%) of an estimated 746 Ae. albopictus eggs and 21 (2.7%) of an estimated 774 Aedes triseriatus eggs survived. Chopped and shredded tire remnants may serve as a means of dispersing mosquitoes.     

Rapidly progressive herpetic retinal necrosis: a blinding disease characteristic of advanced AIDS

Eleven patients with rapidly progressive herpetic retinal necrosis (RPHRN) complicating AIDS were investigated retrospectively to study the disease spectrum, systemic involvement, and therapy. The mean CD4 cell count was 24/microL. There was a characteristic disease pattern with rapid progression, 82% bilaterality, relative resistance to intravenous antiviral therapy, and 70% retinal detachment. Varicella-zoster virus was the probable cause in 10 patients (detected by polymerase chain reaction in two eyes investigated), and herpes simplex virus was the probable cause in one. Cutaneous zoster occurred previously in 73% but was not concurrent. Seventy-three percent had central nervous system disease, possibly virus-related. RPHRN may be a local herpetic recrudescence in an immune-privileged site with transneural spread. Only four of 20 affected eyes retained useful vision. Poor ocular bioavailability, retinal ischemia, acquired drug resistance, and strain pathogenicity may underlie treatment failure. Acyclovir therapy appears relatively ineffective. Combined intravenous and intravitreal therapy with foscarnet and ganciclovir may be the best current management. Research advances are needed urgently.     

Observation of steady state in blood and urine following human ingestion of hexavalent chromium in drinking water

The uptake and elimination of Cr(VI) in a male volunteer who ingested 2 L/d of water containing 2 mg/L for 17 consecutive days was measured. Total chromium was measured in urine, plasma, and red blood cells (RBCs) for 4 d prior to and 2 wk after dosing (34 d total). The estimated bioavailability (2%) and the plasma elimination half-life (36 h) were consistent with our previous studies of Cr(VI) ingestion in humans. Steady-state chromium concentrations in urine and blood were achieved after 7 d of Cr(VI) ingestion. Both plasma and red blood cell (RBC) chromium concentrations returned rapidly to background levels within a few days after cessation of dosing. Since the concentration of chromium in the RBC should not decrease quickly if the chromium had entered the RBC as Cr(VI), these data support our prior work suggesting that concentrations of 10 mg Cr(VI)/L or less in drinking water of exposed humans appears to be completely reduced to Cr(III) prior to systemic distribution. Clinical chemistry data indicate that no toxicity occurred.     

Thalidomide: lack of mutagenic activity across phyla and genetic endpoints

The human and rabbit teratogen thalidomide has been tested for mutagenicity in a wide range of assays, ranging from bacterial gene mutation assays conducted in vitro to in vivo cytogenetic assays conducted using rabbits, and including a variety of human-derived tissues. Thalidomide was not mutagenic to 6 strains of Salmonella when tested both in the presence and absence of Aroclor-induced rat liver S9 mix. This inactivity was confirmed in strains TA98 and TA100 using a 1-h pre-incubation assay protocol with the same S9 mix (10% S9), and additionally, in strain TA98 using 3 concentrations of S9 (4%, 10% and 30% S9 in S9 mix). Thalidomide was not clastogenic either to cultured human lymphocytes (whole blood cultures, minus S9 mix) or to Chinese hamster ovary (CHO) cells treated in vitro. Further, no cytotoxicity was observed in purified human lymphocytes when exposed to thalidomide up to the limit of its solubility in the medium in the presence and absence of liver S9 from Aroclor-induced pregnant rabbit. The CHO assays were conducted without metabolic activation and in the presence of a variety of sources of auxiliary metabolic activation (PB/beta NP-induced rat liver S9 mix, pooled male and female human liver S9 mix, uninduced and Aroclor-induced pregnant rabbit liver S9 mix and foetal rabbit S9 mix). Thalidomide did not induce micronuclei in isolated human lymphocytes (minus S9 mix) and it was non-mutagenic to mouse lymphoma L5178Y TK+/- cells when tested to the limits of its solubility in the culture medium (+/- S9 mix). No indication of recombinogenic or clastogenic activity was observed for thalidomide when tested in Drosophila. In addition, it failed to induce chromosome aberrations in grasshopper neuroblasts when tested in the presence and absence of Aroclor-induced rat liver S9 mix. Some unusual chromosome morphologies were observed in the grasshopper cytogenetic preparations indicating a potential of thalidomide to interact with chromosomal proteins. However, this potential was not evident in the human lymphocyte micronucleus assay, and thalidomide was apparently not reactive to the proteins of the mouse skin, as it gave negative results in a mouse local lymph node assay for skin sensitizing agents. Thalidomide was inactive in bone marrow micronucleus assays conducted using males and females from two strains of mice, and female New Zealand white rabbits. It is concluded that thalidomide is neither a mutagen nor an aneugen. This conclusion is discussed within the context of the results of earlier mutagenicity studies, the recent claim that thalidomide may be a heritable germ cell mutagen to humans, and the current interest in thalidomide for the treatment of immune system-related diseases.     

Effect of H+ extracellular and intracellular buffering capacity on the activity Ca2+/H+ exchange in the lymphocyte plasma membrane

Formation of delta pH is registered when studying Ca2+ passive transport through lymphocytes' plasma membrane (PM). The pHi values strongly depended on pH0. Changes of pH0 lead to unidirectional changes of pHi and affect Ca2+ concentration in cytoplasm of the intact cells. The presence of Ca(2+)-channels antagonists does not affect this phenomenon. Ca2+/H+ exchange is supposed to exist in PM. It is also of great interest that cytoplasmic Ca2+ and H+ activities are some equal in physiological range. Besides, H(+)-buffering as well as Ca(2+)-buffering systems are present in the cell and have their maximal capacity about 7.2 in the intact cells. The spectrofluorimetric study of internal lymphocytes' H(+)-buffering capacity with titration technique using weak base, acid or other buffer addition has demonstrated maximal value of 9.0-1.1 mM depending on the substance to be added.     

Substrate utilization and maturation of cumulus cell-enclosed mouse oocytes: evidence that pyruvate oxidation does not mediate meiotic induction

This review article describes various quantitation methods for the insulin-regulatable glucose transporter (Glut4). Several methods including reconstituted glucose transport, cytochalasin B binding assays, immunocytochemistry, immunoblots, ELISA, and the more recently developed exofacial labels are discussed. Since Glut4 translocates from an intracellular compartment to the plasma membrane in response to the action of insulin, it is of particular interest to measure Glut4 changes in the membrane fractions. Hence, the measurement of Glut4 commonly involves the isolation of cell membranes using subcellular fractionation in combination with one of the quantitation methods. The limitations of each quantitation method due to the use of subcellular fractionation are discussed in this article. As well, the advantages and disadvantages in terms of isoform specificity and technical difficulties of each method are presented.