Complementation between mutants of CHO cells resistant to a variety of plant lectins

Chinese hamster cell mutants resistant to the lectins PHA, WGA, RIC, LCA, and CON A were previously grouped into 8–10 distinct phenotypes on the basis of their unique patterns of lectin resistance and lectin-binding properties. All but one of these classes of lectin-resistant (Lec^R) mutants behave recessively in somatic cell hybrids. One ricin-resistant class ( behaves dominantly. Test for complementation, by measuring the lectin-resistant properties of appropriate hybrids, show that seven distinct complementation groups can be delineated among the phenotypically recessive mutants.     

Selection by [3H] amino acids of CHO-cell mutants with altered leucyl- and asparagyl-transfer RNA synthetases

Efficient selection procedures, using [³ H]amino acids as the selecting agent, were developed for isolating temperature-sensitive (TS) mutations in CHO cells affecting protein synthesis. After chemical mutagenesis, leucyl-tRNA synthetase mutants were obtained when [³ H]leucine was used as the selecting agent in two independent experiments. These mutations seem to involve the same genetic locus as the TSH1 mutant described previously (1). A selection with [³ H]valine, in which all amino acids except leucine were at low concentration in the selective medium, resulted in a new class of mutants with reduced asparagyl-tRNA synthetase activity. These results were consistent with the finding that all mutants were phenotypically dependent on the concentration of amino acid, specific to the altered synthetase, in the medium. Our observations suggest that although leucyl synthetase mutations are a relatively common class of TS mutations in CHO cells, the spectrum of mutants obtained can be at least partially manipulated through concentrations of amino acids in selective media. The asparagylsynthetase mutation was shown to be recessive and to complement the leucylsynthetase mutation in cell-cell hybrids.     

Early prophylactic inhaled beclomethasone in infants less than 1250 g for the prevention of chronic lung disease

OBJECTIVE:

Inflammation plays an important role in the development of chronic lung disease (CLD), which has become a major cause of morbidity in surviving infants less than 1250 g at birth. The authors hypothesized that the progression of this inflammation and, therefore, the establishment of CLD would be decreased with the use of early prophylactic inhaled corticosteroids. Short, and long term respiratory and neurodevelopmental outcomes were also examined.

DESIGN:

A double-blind, randomized placebo controlled trial.

SETTING:

Level-III neonatal intensive care unit.

POPULATION STUDIED:

Sixty infants less than 1250 g at birth, diagnosed with respiratory distress syndrome and requiring ventilatory support at 72 h of age were enrolled in the study.

INTERVENTION:

Infants enrolled received either placebo or beclomethasone diproprionate by a metered dose inhaler, which was used in-line with the ventilator circuit while the infant was ventilated and then via a spacer until 28 days of age.

RESULTS:

Thirty infants were given beclomethasone and 30 were given placebo. There were two deaths in each group. Among the surviving infants, the frequency of moderate-to-severe CLD was 17% in each study group. Mean time to extubation was not different for beclomethasone compared with placebo at 16.4 and 12.5 days (P=0.12), respectively. The requirement for intravenous corticosteroids was lower in the beclomethasone-treated group (RR 0.67, 95% CI 0.43 to 1.04), although this difference was not statistically significant. The incidence of growth failure, infection and intraventricular hemmorhage did not differ between the two groups. Long term outcomes were not different with respect to the incidence of respiratory re-admissions, cerebral palsy, developmental delay, blindness or deafness.

CONCLUSIONS:

Early treatment with inhaled beclomethasone diproprionate did not reduce the incidence of CLD or decrease the duration of mechanical ventilation. The decrease in intravenous corticosteroid use was not statistically significant. Long term outcome was not affected.     

Wasp recruitment to the T cell:APC contact site occurs independently of Cdc42 activation

Cdc42 and WASP are critical regulators of actin polymerization whose function during T cell signaling is poorly understood. Using a novel reagent that specifically detects Cdc42-GTP in fixed cells, we found that activated Cdc42 localizes to the T cell:APC contact site in an antigen-dependent manner. TCR signaling alone was sufficient to induce localization of Cdc42-GTP, and functional Lck and Zap-70 kinases were required. WASP also localized to the T cell:APC contact site in an antigen-dependent manner. Surprisingly, WASP localization was independent of the Cdc42 binding domain but required the proline-rich domain. Our results indicate that localized WASP activation requires the integration of multiple signals: WASP is recruited via interaction with SH3 domain-containing proteins and is activated by Cdc42-GTP concentrated at the same site.     

Umbilical cord plasma interleukin-6 and fetal growth restriction in preeclampsia: a prospective study in Norway

OBJECTIVE: To study the association between umbilical plasma levels of interleukin-6 (IL-6) in relation to fetal growth in subgroups of preeclampsia, and in control pregnancies. METHODS: Umbilical cord plasma was collected from 12,804 consecutive births. A total of 271 singleton cases of preeclampsia were identified, and classified as mild or severe, and as disease with early or late onset. As controls, 611 singleton pregnancies without preeclampsia were selected, and the ratio between observed and expected birth weight was used as a measure of fetal growth. In the analysis, we also included maternal smoking during pregnancy. Umbilical cord plasma IL-6 concentration was measured with an IL-6 bioassay. Comparing controls with subgroups of preeclampsia (severe and early onset), this study had a statistical power of 90% to detect a difference in cord IL-6 of 10 pg/mL. RESULTS: In severe preeclampsia, cord plasma IL-6 concentration was lower than among controls (P <.001), and there was a sharp decrease in cord plasma IL-6 with decreasing birth weight ratio (P trend <.001). By further dividing the preeclampsia group into early or late onset, the strong association between low IL-6 levels and low birth weight ratio appeared to be present mainly in early-onset disease. These results were not confounded by maternal smoking. CONCLUSION: Restricted fetal growth related to preeclampsia is associated with reduced umbilical cord plasma IL-6 concentration in cases with early-onset disease. In these cases, fetal growth restriction could be mediated by impaired trophoblast function.     

TUBULAR PROTEINURIA AFTER PERINATAL HYPOXIA

ABSTRACT. Milt7eacute;nyi, M., Pohlandt, F., Bóka, G. and Kun, E. (2nd Department of Paediatrics, Semmelweis University, Medical School, Budapest, Hungary, and the Section of Neonatology, Centre of Paediatrics, University of Ulm, Federal Republic of Germany). Tubular proteinuria after perinatal hypoxia. Acta Paediatr Scand, 70:399, 1981.–Urinary total protein (UTP) and urinary protein pattern have been studied in 23 newborn infants with Apgar scores ±S3 at one minute or acidosis (pH ±7.15) on the first day. On the first and second day UTP excretion was increased in 13 out of 18 patients. At this time the excretion of low molecular weight microproteins (T-4 and T-5) was elevated in 12 patients without increased plasma urea concentration in any case. The increased excretion of the smallest microproteins T-4/T-5 is an early sign of an impaired tubular function.