Insulin-dependent diabetes, an autoimmune disease

In type I (insulin-dependent) diabetes evidence for an autoimmune process is now fully established. This is also true for a similar disease observed in the NOD mouse and the BB rat. In addition to circulating antipancreatic antibodies, we demonstrated T-lymphocyte mediated cellular immunity in both these diabetic animals and in the human. Immunological abnormalities precede the development of diabetes and may be responsible for beta cell alteration. Evidence for this interpretation appears stronger for cell-mediated than for humoral immunity. However, full demonstration and understanding of the relationship between anti-beta cell immunity and beta cell alteration still raise many unresolved problems.     

Enzymic synthesis ofL-Lysine fromDL-α-Amino-ε-caprolactam by new microbial strains

The production of L-lysine fromDL-α-amino-ε-caprolactam (DL-ACL) by new strains producingL-α-amino-ε-caprolactamase and aminocaprolactam racemase is described. Optimal conditions for hydrolysis ofL-ACL byCryptococcus sp. and for racemization of ACL by cells of a strain isolated in nature and identified asPseudomonas sp. were determined. Synthesis ofL-α-amino-ε-caprolactamase is induced byDL-ACL orL-lysine with the same effectivity. A positive effect of phosphates (potassium salts) on reduction of the induction lag was detected, the synthesis of this enzyme was found to be repressed by glucose and some possibilities of the reversion of this repressive effect were demonstrated. Under conditions optimal for the production of both enzymes a quantitative theoretical conversion of 10 % aqueousDL-ACL toL-lysine by a mixture of native cells in a mass ratio of 1: 2 (producer of ACL-hydrolase to producer of ACL-racemase) occurred in 8 h at 40 °C and pH 8.0     

Detection of Staphylococcal Enterotoxin A,B, and C in Milk By an Elisa Procedure

Enterotoxigenic reference strains of Staphylococcus aureus were cultivated in sterile whole and skim milk for 18 h at 37°G. Staphylococcal enterotoxin A, B, and C were detected directly in the milk by an enzyme linked immunosorbent assay (ELISA), sensitive down to 1 ng/ml. Enterotoxins in the range of 1 ng–20 µg/ml milk were detected without any concentration or extraction. Skim and whole milk were almost identical as medium for enterotoxin production.     

Glycosylation of catalase inhibitor necessary for activity

A protein isolated from maize scutella which inhibits catalase in vitro has been shown to contain 12% carbohydrate in the form of galactose. This corresponds to four galactose molecules per inhibitor subunit. Removal of the carbohydrate with β-galactosidase or blockage with a galactose-specific lectin abolished activity of the inhibitor.     

Mutagenicity testing of dichloromethane in short-term mammalian test systems

Several short-term mammalian test systems were used for mutagenicity testing of the organic solvent dichloromethane. The compound was negative in the forward mutation test on the HGPRT locus in Chinese hamster cells and the unscheduled DNA synthesis test in both human and hamster cells. In the test on DNA synthesis inhibition, dichloromethane caused an aspecific inhibition in both human and hamster cells, but in this test the effect did not indicate a DNA-damaging action. A weak positive effect was found in the test on sister-chromatid exchanges in hamster cells.     

Biology, serology and biochemistry of leucemogenic viruses derived from a radiation-induced tumor of C57BL mice

Two distinct rat propagates of a radiation leukemia virus (RadLV-Rs) from the C57BL mouse respectively induced characteristic leukemogenic effects. These were found to be related with the infection titers of the isolates, but not with either their antigenic specificities or their viral and proviral genome sequences.     

Yeast cell mortality related to a high-pressure shift: occurrence of cell membrane permeabilization

The shrinkage of yeast cells caused by high-pressure treatment (250 MPa, 15 min) was investigated using direct microscopic observation. A viable staining method after treatment allowed the volume variation of two populations to be distinguished: an irreversible volume decrease (about 35% of the initial volume) of pressure-inactivated cells during pressure holding time, and viable cells, which were less affected. A mass transfer was then induced during high-pressure treatment. Causes of this transfer seem to be related to a pressure-induced membrane permeabilization, allowing a subsequent leakage of internal solutes, where three ions (Na+, K+ and Ca2+), plus endogenous glycerol, were verified. This glycerol leakage was found to occur after yeast pressurization in a medium having low water activity, although the yeast was not inactivated. All these observations lead to the hypothesis that pressure-induced cell permeabilization could be the cause of yeast inactivation under pressure.