[Hygienic evaluation of the total mutagenic activity of snow samples from Magnitogorsk].

The paper gives the results of 4-year monitoring of the total mutagenic activity of snow samples from different Magnitogork areas in a test for induction of dominant lethal mutations (DLM) in the gametes of Drosophila melanogaster. An association was first found between the rate of DLM and the content of some chemical compounds in the ambient air and snow samples; moreover all the substances present in the samples, which had found genotoxic effects, showed a positive correlation with the rate of DLM. Furthermore, direct correlations were first established between the rate of DLM and the air pollution index and morbidity rates in 5-7-year-old children residing in the areas under study. The findings allow the test for induction of dominant lethal mutations (DLM) in the gametes of Drosophila melanogaster to be recommended due to its unique informative and prognostic value for monitoring ambient air pollution and for extensive use in the risk assessment system.

[Effects of trivalent antimony on the rat hormonal status under experimental conditions].

The paper gives the data of experimental studies of oral trivalent antimony used at 1 and 20 maximum permissible concentrations (MPC) on the rat hormonal status. The findings are indicative of the specific features of changes in the hormonal status of experimental animals depending on the dose of trivalent antimony. The concentration of trivalent antimony at the level of 20 MPC is shown to act as a role of a reprotoxic agent that causes a change in the serum content of hormones, such as follicle-stimulating and luteinizing ones.

Nodal T cell blast crisis in chronic myeloid leukemia.

We report the case of a 54 year old male with an original diagnosis of chronic myeloid leukemia (CML) who developed a nodal T cell blast crisis (BC) while he was in a complete hematological remission (CR). We describe the clinical presentation and the histological, immunophenotypic and molecular characterization of the lymph node blast cells. Our case, together with other rare similar reports in the literature, argue that a T cell nodal blast crisis of CML resembles the presentation of a T-cell non-Hodgkin's lymphoma.

[Prophylaxis of muscular stress in physical labor]. / Profilaktika myshechnogo perenapriazheniia pri fizicheskoi rabote.

The authors demonstrated that work of female molders, acquisitors and stacking packers is characterized by physical load, great number of cliched manual movements, intensive inclinations of corpse and constrained working posture. Prolonged exposure to unfavorable occupational factors results in neuromuscular and cardiovascular stress that induces pathologic changes with increasing length of service. Complex of prophylactic measures suggested by the authors proves effective as releases working strain and delays fatigue during the working shift.

[Specific aspects of fatigue formation in professionals working with video-displaying terminals]. / Osobennosti razvitiia utomleniia u professional'nykh pol'zovatelei videodispleinykh terminalov.

The article presents laboratory results describing influence of hand and arm temperature on capacity of fingers' flexor muscles for dynamic physical work. New means and method for individual protection from local vibration are designed. The authors discuss efficiency of these novelties for exposure of hands to local physical load and vibration.

Isolation of a trifluoroleucine-resistant mutant of Saccharomyces cerevisiae deficient in both high- and low-affinity L-leucine transport.

A yeast mutant defective in permeases S1 and S2 which transport L-leucine was isolated from a parental strain already deficient in the general amino acid permease, GAP1. The mutant was selected as a spontaneous, trifluoroleucine-resistant (TFLR) strain. Full resistance depended upon the presence of two unlinked mutant genes designated let1 and let2. The let1 mutation completely inactivates the high-affinity leucine transport system defined kinetically as S1. Although the let2 mutation caused a marked decrease in the Jmax of the low-affinity transport system, S2, residual leucine transport in the let1 let2 gap1 mutant had the same KT as in the LET1 LET2 gap1 parent. The mutant exhibited a marked decrease in growth on minimal medium containing leucine, isoleucine or valine as a sole nitrogen source. Moreover, assimilation of methionine, phenylalanine, serine and threonine was decreased, whereas basic and acidic amino acids supported normal growth. This indicates that at least one of the leucine permeases has a fairly broad, but still limited, specificity. Reversion of the gap1 gene restored leucine transport. The revertant was sensitive to TFL when grown on proline but resistant when NH4+ was the nitrogen source. The previously published mutations (shr3, aat1, lup1 or raa) would not be related to either LET1 or LET2.

[Use of polymerase chain reaction (PCR) in oncohematology. Detection of minimal residual disease]. / Aplicaciones de la reacción en cadena de la polimerasa (PCR) en oncohematologia. Detección de enfermedad minima residual.

The early detection of clonogenic cells able to survive cytotoxic therapy and to initiate a neoplastic process, defined as Minimal Residual Disease (MRD), represents a major objective for the development of new and more sensitive diagnostic methods. The cloning of different chromosomal translocations along with the application of the Polymerase Chain Reaction (PCR) technique has allowed the characterization of various hematological disorders at the molecular level. This approach has led to the development of PCR based assays able to detect a minimum number of malignant cells with very high specificity. In the present paper we discuss the use of PCR and its value as a predictor for relapse in lymphomas, chronic myelogenous leukemia and acute promyelocytic leukemia, characterized by the t(14;18) t(9;22) and t(15;17) translocations, respectively.

[Changes in the functional state of the visual analyzer during work at video display terminals of graphic images]. / Izmenenie v funktsional'nom sostoianii zritel'nogo analizatora pri rabote s videoterminalami graficheskogo izobrazheniia.

The examination covered female operators of sewing pickup, engaged into the work at video-displays. The total work load appeared to equal 77.6% and the work at video-display--75.2% of the shift time. Functional state of the vision demonstrated a decrease even after 2 hrs of the work, then stabilized by midpoint of the shift and afterwards lowered by 10-12 hrs of the work. Those objective changes correlated with the sensation of orbital discomfort. The findings served as a base for prophylaxis to restore the performance during the regulated breaks.

Aplicaciones de la reacción en cadena de la polimerasa (PCR) en oncohematologia. Detección de enfermedad minima residual. / [Use of polymerase chain reaction (PCR) in oncohematology. Detection of minimal residual disease]

The early detection of clonogenic cells able to survive cytotoxic therapy and to initiate a neoplastic process, defined as Minimal Residual Disease (MRD), represents a major objective for the development of new and more sensitive diagnostic methods. The cloning of different chromosomal translocations along with the application of the Polymerase Chain Reaction (PCR) technique has allowed the characterization of various hematological disorders at the molecular level. This approach has led to the development of PCR based assays able to detect a minimum number of malignant cells with very high specificity. In the present paper we discuss the use of PCR and its value as a predictor for relapse in lymphomas, chronic myelogenous leukemia and acute promyelocytic leukemia, characterized by the t(14;18) t(9;22) and t(15;17) translocations, respectively.

L-leucine transport systems in Saccharomyces cerevisiae participation of GAP1, S1 and S2 transport systems.

L-leucine uptake in Saccharomyces cerevisiae is mediated by three different transport systems, S1, S2 and GAP1. Their activities are dependent on the nitrogen source of the culture media. Wild type cells grown in L-proline exhibit a single transport system with high affinity and high Vmax that is partially inhibited by L-citrulline. A gap1 mutant shows two transport systems with Km and Vmax values similar to those previously described as S1 and S2, this transport activity is not inhibited by D-leucine, D-isoleucine or D-valine. Two systems can be also determined in wild type cells grown in rich medium containing a mixed nitrogen source where decreased GAP1 function is observed. In either wild type or gap1 cells grown in medium containing ammonium ions as sole nitrogen source, L-leucine uptake kinetics shows two systems with lower Vmax and similar Km values to those of the S1 and S2 systems. These results show that in S. cerevisiae GAP1, S1 and S2 participate in L-leucine entrance in cells grown in a poor nitrogen source, and that S1 and S2 are two ammonia-sensitive permeases that mediate the uptake in cells grown in a rich nitrogen source.

Immunological analysis of GLUT4-enriched vesicles. Identification of novel proteins regulated by insulin and diabetes.

In adipocytes and muscle, insulin stimulates the translocation of glucose transporter proteins from an intracellular vesicle pool to the plasma membrane. To study the molecular basis of this process, we used the anti-GLUT4 antibody 1F8 to isolate intracellular vesicles from rat adipocytes that are enriched in the muscle/fat glucose transporter isoform. These vesicles were then used as immunogens to generate monoclonal antibodies against their protein components. We isolated an antibody, 3F8, that recognizes three polypeptides, designated GTV3, migrating in the 36-40-kDa range as analyzed by SDS-polyacrylamide gel electrophoresis and Western blotting. These proteins are enriched in GLUT4-containing vesicles, and the two smallest of the polypeptides recognized by 3F8 translocate to the cell surface in response to insulin. GTV3 proteins are also present in plasma membranes of fat cells and liver as well as in a wide number of tissues, red blood cells being the only exception. In adipocytes from streptozotocin-induced diabetic rats, GTV3 protein levels decrease dramatically and return to normal levels when animals are treated with insulin. The localization of GTV3 in glucose transporter-containing vesicles as well as their wide tissue distribution suggests that these proteins may be involved in vesicle mediated transport and regulated trafficking between membrane compartments.

Differential regulation of glucose transporter 1 and 2 mRNA expression by epidermal growth factor and transforming growth factor-beta in rat hepatocytes.

We have examined by Northern blot analysis the expression of two members of the glucose transporter family of genes (GLUT-1 and GLUT-2) in regenerating liver and in hepatocytes cultured under various conditions. GLUT-1, although thought to be a growth-associated gene, is not expressed in normal or regenerating liver, whereas GLUT-2, a liver-specific gene, is abundant in normal liver and gradually up-regulated during liver regeneration. Conversely, in hepatocytes cultured conventionally on dried rat tail collagen (RTC) in the presence of EGF and insulin, which potentiate proliferation, GLUT-1 mRNA is rapidly and abundantly expressed, whereas GLUT-2 is depressed. To investigate the causes of this "switch" in glucose transporter expression seen when hepatocytes are removed from the liver and cultured under the conventional proliferative conditions, we examined the effects of specific growth factors and extracellular matrices on cultured hepatocytes. EGF, a potent liver mitogen, although causing a threefold induction of GLUT-1, was found to have no effect on GLUT-2 expression, suggesting that the increase in GLUT-2 seen in regenerating liver is not due to EGF. Inhibition of protein synthesis by cycloheximide in cultured hepatocytes does not prevent the induction of GLUT-1 mRNA. In addition, treatment of cells with cycloheximide appears to stabilize the GLUT-2 mRNA, preventing the usual down-regulation of this gene in cultured hepatocytes. The expression of the two glucose transporter mRNAs also differed when the hepatocytes were adherent to particular cell matrices. Culture of hepatocytes on a reconstituted basement membrane gel matrix (EHS) is known to restrain their growth and mediate high levels of differentiated hepatocytic functions that are lost under conventional culture conditions. Unlike cells on RTC, hepatocytes on EHS expressed low levels of GLUT-1 mRNA, and decreased GLUT-2 mRNA. TGF-beta, an attenuator of DNA synthesis, when added to cultures on RTC, substantially down-regulated GLUT-2 but had no effect on GLUT-1. We propose that the effectors, EGF, TGF-beta and basement membrane components, play a significant role in the regulation of expression of GLUT-1 and GLUT-2 in hepatocytes.

Expression of the glucose transporter isoform GLUT 4 is insufficient to confer insulin-regulatable hexose uptake to cultured muscle cells.

Glucose transporter isoform expression was studied in the skeletal muscle-like cell line, C2C12. Northern and Western blot analysis showed that the insulin-responsive muscle/fat glucose transporter isoform, GLUT 4, was expressed in these cells at very low levels, whereas the erythrocyte isoform, GLUT 1, was expressed at readily detectable levels. Insulin did not stimulate glucose transport in this cultured muscle cell line. The C2C12 cells were then transfected separately with either GLUT 1 or GLUT 4, and stable cell lines expressing high levels of mRNA and protein were isolated. GLUT 1-transfected cells exhibited a 3-fold increase in the amount of the GLUT 1 transporter protein which was accompanied by a 2- to 3-fold increase in the glucose uptake rate. However, despite at least a 10-fold increase in GLUT 4 mRNA and protein detected after GLUT 4 cDNA transfection, the glucose uptake of these cells was unchanged and remained insulin-insensitive. By laser confocal immunofluorescence imaging, it was established that the transfected GLUT 4 protein was localized almost entirely in cytoplasmic compartments. In contrast, the GLUT 1 isoform was detected both at the plasma membrane as well as in intracellular compartments. These results suggest that acute insulin stimulation of glucose transport is not solely dependent on the presence of the insulin receptor and the GLUT 4 protein, and that the presence of some additional protein(s) must be required.

[Effect of ammonium ions on the uptake of L-leucine in Saccharomyces cerevisiae. Repression and inhibition of transport systems]. / Efecto de iones amonio sobre la entrada de L-leucina en Saccharomyces cerevisiae. Represión e inhibición de los sistemas transportadores.

L-leucine entrance into Saccharomyces cerevisiae is mediated by the general amino acid permease, GAP and two transport systems, S1 and S2, kinetically characterized. S1 is a high-affinity, low-velocity transport system, operating at lower L-leucine external concentration (0.05-0.1 mM), while S2 is a low-affinity, high-velocity transport system, operating at higher L-leucine external concentration (1.0 mM). In cells grown in minimal medium containing ammonium as sole nitrogen source the values of L-leucine entrance and uptake are smaller than those in cells grown in L-proline containing medium. When GAP is repressed by ammonium, L-leucine entrance is mediate by systems S1 and S2. Both systems are inhibited by ammonium. When GAP is derepressed, in cells grown in L-proline medium, L-leucine is transported by systems S1 and GAP (lower L-leucine external concentration), and mainly by S2 (higher L-leucine external concentration). GAP is the largest system inhibited by ammonium.

Efecto de iones amonio sobre la entrada de L-leucina en Saccharomyces cerevisiae. Represión e inhibición de los sistemas transportadores / [Effect of ammonium ions on the uptake of L-leucine in Saccharomyces cerevisiae. Repression and inhibition of transport systems]

L-leucine entrance into Saccharomyces cerevisiae is mediated by the general amino acid permease, GAP and two transport systems, S1 and S2, kinetically characterized. S1 is a high-affinity, low-velocity transport system, operating at lower L-leucine external concentration (0.05-0.1 mM), while S2 is a low-affinity, high-velocity transport system, operating at higher L-leucine external concentration (1.0 mM). In cells grown in minimal medium containing ammonium as sole nitrogen source the values of L-leucine entrance and uptake are smaller than those in cells grown in L-proline containing medium. When GAP is repressed by ammonium, L-leucine entrance is mediate by systems S1 and S2. Both systems are inhibited by ammonium. When GAP is derepressed, in cells grown in L-proline medium, L-leucine is transported by systems S1 and GAP (lower L-leucine external concentration), and mainly by S2 (higher L-leucine external concentration). GAP is the largest system inhibited by ammonium.

Efecto de iones amonio sobre la entrada de L-leucina en Saccharomyces cerevisiae. Represión e inhibición de los sistemas transportadores. / [Effect of ammonium ions on the uptake of L-leucine in Saccharomyces cerevisiae. Repression and inhibition of transport systems]

L-leucine entrance into Saccharomyces cerevisiae is mediated by the general amino acid permease, GAP and two transport systems, S1 and S2, kinetically characterized. S1 is a high-affinity, low-velocity transport system, operating at lower L-leucine external concentration (0.05-0.1 mM), while S2 is a low-affinity, high-velocity transport system, operating at higher L-leucine external concentration (1.0 mM). In cells grown in minimal medium containing ammonium as sole nitrogen source the values of L-leucine entrance and uptake are smaller than those in cells grown in L-proline containing medium. When GAP is repressed by ammonium, L-leucine entrance is mediate by systems S1 and S2. Both systems are inhibited by ammonium. When GAP is derepressed, in cells grown in L-proline medium, L-leucine is transported by systems S1 and GAP (lower L-leucine external concentration), and mainly by S2 (higher L-leucine external concentration). GAP is the largest system inhibited by ammonium.

Insulin-regulated glucose uptake in rat adipocytes is mediated by two transporter isoforms present in at least two vesicle populations.

We have recently described a monoclonal antibody (1F8) that recognizes a form of glucose transporter unique to fat and muscle (James, D. E., Brown, R., Navarro, J., and Pilch, P. F. (1988) Nature 333, 183-185), tissues that respond acutely to insulin by markedly increasing their glucose uptake. Here, we report that rat adipocytes possess two immunologically distinct glucose-transporters: one recognized by 1F8, and one reactive with antibodies raised against the human erythrocyte glucose transporter. Immunoadsorption experiments indicate that these glucose transporters reside in different vesicle populations and that both transporter isoforms translocate from intracellular sites to the plasma membrane in response to insulin. The insulin-regulatable transporter resides in a unique vesicle that comprises 3% or less of the low density microsomes of fat cells and has a limited protein composition that does not include the bulk of another translocatable protein, the insulin-like growth factor II receptor. Immunoprecipitation with 1F8 of microsomal glucose transporters photoaffinity labeled with [3H]cytochalasin B brings down 90% of the label. Similarly, immunoprecipitation with 1F8 of glucose transporters from insulin-stimulated plasma membranes photolabeled with 3-[125I]iodo-4-azidophenethylamido-7-O-succinyldeacetyl-f ors kolin, another transporter-selective reagent, results in 75% of the labeled transporter localized in the immunoprecipitate. Thus, insulin action involves the combined effect of translocation from at least two vesicle pools each containing different glucose transporters. The 1F8-reactive transporter comprises the majority of the total transporter pool that is responsible for the insulin-induced increase in glucose transporter number.