Mutagenicity of 5,6-dimethoxysterigmatocystin, a metabolite from Aspergillus multicolor, in the Salmonella/microsome system.

The natural sterigmatocystin derivative, 5,6-dimethoxysterigmatocystin, was found to be a mutagen for Salmonella typhimurium strains TA98 and TA100 after metabolic activation in a mammalian microsome system.     

Purification and characterization of a 22-kDa microsomal protein from rat parotid gland which is phosphorylated following stimulation by agonists involving cAMP as second messenger

Stimulation of secretion in exocrine glands by agonists involving cAMP as second messenger leads to the phosphorylation of the ribosomal protein S6 (protein I) and two other particulate proteins with apparent molecular masses of 24 kDa (protein II) and 22 kDa (protein III) [Jahn, R., Unger, C. & S?ling, H. D. (1980) Eur. J. Biochem. 112, 345-352]. This report describes the purification and characterization of protein III. Solubilization studies indicate that protein III is an intrinsic membrane protein. It could be extracted from the endoplasmic reticulum membrane only with Triton X-100, SDS or concentrated formic or acetic acid. The purification of this protein involved extraction of the microsomes with Triton X-100, removal of the detergent by acetone precipitation, extraction of water-soluble proteins, lipids and lipoproteins, and preparative SDS polyacrylamide gel electrophoresis. The protein has a basic pI (greater than 8.7). For determination of the amino acid composition of protein III and for sequencing of its amino-terminal portion, the protein was electroeluted out off the gel, the detergent removed and the protein finally purified by reversed-phase HPLC. Protein III could be phosphorylated in vitro by the catalytic subunit of the cAMP-dependent protein kinase to a degree of approximately 0.14 mol phosphate/mol protein. The only phosphopeptide obtained after in vitro phosphorylation and subsequent tryptic or chymotryptic digestion was identical with the phosphopeptide obtained after stimulation of intact rat parotid gland lobules with isoproterenol. The sequence of this peptide was Lys-Leu-Ser(P)-Glu-Ala-Asp-Asn-Arg. It was confirmed by an analysis of the synthetic peptide following in vitro phosphorylation with cAMP-dependent protein kinase. The first 41 N-terminal residues of protein III were sequenced. So far no sequence homology with other known peptides or proteins could be found.     

Selective fetal malnutrition: The effect of ethanol and acetaldehyde upon in vitro uptake of alpha amino isobutyric acid by human placenta

Uptake of alpha amino isobutyric acid was measured in human placental villus tissue exposed $\text{in vitro}$ to ethyl alcohol (ethanol) (0.3 g/dl–2 g/d1) or acetaldehyde (50 μM-20 mM). Ethanol and acetaldehyde significantly inhibited uptake of amino acid at higher, pharmacologic concentrations (2 g/dl and 2–20 mM respectively). Inhibition by 10 mM acetaldehyde was partially reversible. The results suggest that the human placenta is resistant to acute ethanol-associated effects upon amino acid transport $\text{in vitro}$. However, both ethanol and its major circulating metabolite, acetaldehyde, may still alter placental function during $\text{in vivo}$ chronic exposure.     

Changes of telomere lengths in human intracranial tumours

The termini of human chromosomes comprise stretches of G-rich repeats that are about 5–20 kilobase (kb) in length. The size of the telomeres can be determined by hybridization with probes specific for these (ttaggg)_n sequences after digestion of chromosomal DNA with appropriate restriction enzymes and electrophoretic separation of the fragments. Here, probing with the ³²P-labelled synthetic (TTAGGG)₃ oligonucleotide revealed length changes of the telomeres occurring in intracranial tumours. Among 60 samples analysed, 41.7% showed telomere elongation, and 21.7% telomere reduction, whereas 36.7% of the tumours exhibited equal lengths compared with the patients' peripheral blood leukocytes. Most of the elongated glioma telomeres exceeded in length those of untransformed astrocytes derived from human fetal tissue.     

Auer bodies in acute lymphocytic leukaemia and B-cell lymphoma: evidence for a common progenitor of myeloid and lymphoid cells?

In a patient with acute lymphocytic leukaemia (pre-T ALL) and another patient with leukaemic generalization of B-cell lymphoma Auer bodies were found in a few immature cells. The diagnosis in both cases was based on clinical grounds, morphology, cytochemistry, and immunological marker analysis of the blasts. Auer bodies are known to be a marker of high significance for acute non-lymphocytic leukaemias. Therefore the findings described suggest mixed leukaemias with either T-cell or B-cell predominance. It provides further evidence for the existence of a common progenitor of myeloid and lymphoid cells.     

Immunofluorescence with monoclonal antibodies on poly-L-lysine coated slides: an alternative to conventional methods

It is sometimes difficult to perform immunofluorescence tests because of low cell numbers. Therefore a simple method using poly-L-lysine coated slides was applied to immunofluorescence and compared with the routine suspension method. Peripheral blood lymphocytes from normal persons, samples of normal bone marrow, thymus and tonsil as well as samples from patients with leukemia or lymphoma were tested with these two methods using 20 different monoclonal antibodies. The PLL-slide method was shown to be comparable with the suspension method and is an alternative in case of low cell numbers, since as few as 3 X 10(4) cells can be tested for one antigen.     

Expression of PGK-A in the Australian brush-tailed possum,Trichosurus vulpecula (Kerr), consistent with paternal X inactivation

An extensive survey of erythrocytes of marsupials other than kangaroos for electrophoretic variation in X-linked enzymes revealed two rare PGK-A phenotypes in the phalangerid Trichosurus vulpecula and one in Trichosurus caninus. Four putatively heterozygous females expressed only the variant allelic isozyme in some tissues but expressed a trace of the normal isozyme in others. A putatively hemizygous male expressed only the variant isozyme in all tissues. The phenotypic patterns were consistent with those observed in kangaroos known to exhibit partial or complete paternal X inactivation in cells of females. Two of the T. vulpecula were a mother and her female pouch young, further suggesting that paternal X inactivation occurs in T. vulpecula. This peculiar mechanism of dosage compensation may not be restricted to kangaroos.This work was supported by grants to D. W. C. from the Australian Research Grants Committee and Macquarie University, J. L. V. was the recipient of a Fulbright-Hays Award from the Australian-American Educational Foundation and a postgraduate fellowship from General Motors-Holden.     

Comparison of enzyme-cytochemical findings and immunological marker investigations in acute lymphatic leukemia (ALL).

APh-activity and PAS-positive deposits were studied in 50 cases of ALL, classified as T-ALL and O-ALL according to immunological marker investigations. Correlation between morphological features of the cells and APh and PAS reactions, as well as between morphology and immunological markers was not detected. APh-activity in general was stronger in T-ALL (R+ and R-), while PAS-content was more pronounced in O-ALL. The results suggest that cytochemical methods, especially APh and PAS reaction, are valuable to distinguish T-ALL from O-ALL but not reliable enough to replace immunological marker investigations.     

B-cell lymphoma lacking Fc- and C3d-receptors.

Various cell surface markers were studied in a patient with lymphosarcoma cell leukemia. The B-cell derived feature of the neoplastic cells could be identified by demonstration of monoclonal surface immunoglobulin of IgM-kappa type of high density synthesized by the cells. Interestingly, there were no Fc- nor C3d-receptors demonstrable using various techniques. Only 22% of the leukemic cells expressed C3b receptors. The failure of rosette formation with mouse erythrocytes was an additional surface feature distinguishing from ordinary chronic lymphatic leukemia of the B cell type. The phenotype of the leukemia cells is discussed as corresponding to that of a less differentiated B lymphocyte.