Ha-ras-1 alleles in Norwegian lung cancer patients

Summary We have examined DNA restriction fragment length polymorphisms (RFLP) of the Ha-ras-1 gene in DNA from 118 lung cancer patients and 123 unaffected controls. When DNA samples were digested with MspI/ HpaII restriction endonucleases. Southern blot analysis demonstrated 4 common, 4 intermediate and 7 different rare alleles in the combined population after hybridization to the pGDa1 probe. Six of the rare alleles were unique for the lung cancer group and 1 rare allele for the control group. The frequency of rare alleles in lung cancer patients (10/236) was significantly different (P<0.01) from the control group (1/246). The lung cancer group also had a significantly lower frequency of the common 2.57 kb fragment than the controls (P<0.02). The results thus indicate that Ha-ras genotyping may be of value in lung cancer risk assessment.     

The effect of ranitidine on cellular immunity in patients with multiple myeloma

Summary Multiple myeloma is characterized by an increased susceptibility to infections and to other malignancies. In a double-blind, placebo-controlled study the potential impact of immunomodulation by ranitidine was studied in 20 patients with multiple myeloma. Three patients were untreated, while 17 after previous cytotoxic therapy were in a stable phase of their disease. All were without clinical signs of infections and at that time had not been treated with other immunomodulating agents. The patients were randomized to oral ranitidine 300 mg twice a day for 21 days or placebo, and several immunological parameters related to multiple myeloma were studied. The blood monocyte chemotactic response was improved in patients treated with ranitidine, and superoxide anion production increased from 2.02 nmol/min to 3.86 nmol/min (median values), while it was unchanged in patients given placebo (2.19–2.25 nmol/min) (P <0.005 between groups). Among ranitidine-treated patients spontaneous NK cell activity was unchanged, while in vitro interleukin-2- and interferon--stimulated NK cell activity decreased (P <0.03, respectively). As production of oxygen radicals constitutes an important mechanism of monocyte killing activity against microorganisms and probably against malignant cells, it is suggested that ranitidine may be of beneficial impact in the treatment of multiple myeloma.     

Bud dormancy and vegetative growth in Salix polaris as affected by temperature and photoperiod

Summary Vegetative growth of two ecotypes (lat. 78° 15N and 69°37N) of Salix polaris L. was studied in phytotron experiments. Dormancy of the winter buds was broken by chilling at 0.5°C for 14 to 42 days. Chilling requirement increased with decreasing growth temperature. The optimum temperature for bud break and shoot growth was about 15°C for both ecotypes. Cessation of apical shoot growth and abscission of shoot tip was not prevented by long photoperiods. However, at high temperature, 15°C or more, and in 18 to 24 h photoperiod, two or three growth flushes occurred frequently in both ecotypes. Leaf abscission in the arctic ecotype from lat. 78°N was not affected by photoperiod when grown at 6°C, but was stimulated by short photoperiod when grown at 15°C. In the ecotype from lat. 69°N leaf abscission was enhanced by short photoperiod even at 6°C.     

Are L-tyrosine and L-dopa hormone-like bioregulators?

Some amino acids have bioregulatory functions, which far exceed those of precursors for proteins or of substrates for specific enzymes. Two of these amino acids, L-tyrosine and L-dopa, are precursors to melanin and catecholamines. In vertebrates, they can act as inducers and regulators of the melanogenic apparatus and of MSH receptors--two quite complex functions that could hardly be performed by mere substrates. Focussing on the pigmentary system as a study model, we therefore explore the hypothesis that L-tyrosine and L-dopa act as hormone-like bioregulators in mammals, with melanocytes regulating tyrosine and dopa activity via their metabolic consumption.     

Influence of fatty acids and bovine serum albumin on the growth of human hepatoma and immortalized human kidney epithelial cells

Summary The protective influence of bovine serum albumin against growth inhibition caused by fatty acids was studied in human hepatoma (HepG2) and immortalized human kidney epithelial (IHKE) cells. In general, growth inhibition by unsaturated fatty acids (0.15 mmol/liter) increased with increasing number of double bonds. For HepG2 cells crude albumin (1g/100 ml) did not greatly modify growth inhibition by arachidonic, eicosapentaenoic, and docosahexaenoic acid. With oleic, linoleic, and linolenic acids, crude and defatted albumin stimulated cell growth. In contrast, for IHKE cells both albumins counteracted growth inhibition by unsaturated fatty acids to approximately the same extent. When HepG2 cells were cultured in the presence of saturated fatty acids (0.3 mmol/liter), C2, C6, and C8 had no or little inhibitory effect. C10 and C12 inhibited cell growth appreciably, whereas C14, and especially C16, had poor inhibitory effects. Crude albumin counteracted growth inhibition by all these fatty acids. In contrast, defatted albumin had little or no effect (except against C10 and C12), and even increased the growth inhibition by C14 and C16. With unsaturated fatty acids there seemed to be an inverse relationship between cell growth and the concentration of thiobarbituric acid reactive substances (TBARS) in media. Vitamin E abolished growth inhibition (and the increase in TBARS concentration) by unsaturated fatty acids. The complex interaction between fatty acids and albumins calls for great caution when interpreting data on growth effects.     

(Na + K)-ATPase activity of crude homogenates of rat skeletal muscle as estimated from their K-dependent 3-O-methylfluorescein phosphatase activity

A highly sensitive fluorimetric assay using 3-O-methylfluorescein phosphate as substrate was used in the determination of K⁺-dependent phosphatase activity in preparations of rat skeletal muscle. The gastrocnemius muscle was chosen because of mixed fibre composition. Crude, detergent treated homogenate was used so as to avoid loss of activity during purification. K⁺-dependent phosphatase activities in the range 0.19–0.37 μmol · (g wet weight)⁻¹ · min⁻¹ were obtained, the value decreasing with age and K⁺-deficiency. Complete inhibition of the K⁺-dependent phosphatase was obtained with 10⁻³ M ouabain. Using a KSCN-extracted muscle enzyme the intimate relation between K⁺-dependent phosphatase activity and (Na⁺ + K⁺)-activated ATP hydrolysis could be demonstrated. A molecular activity of 620 min⁻¹ was estimated from simultaneous determination of K⁺-dependent phosphatase activity and [³H]ouabain binding capacity using the partially purified enzyme preparation. The corresponding enzyme concentration in the crude homogenates was calculated and corresponded well with the number of [³H]ouabain binding sites measured in intact muscles or biopsies hereof.     

A newborn child with karyotype 47,XX,+der(12) (12pter→12q12::8q24→8qter),t(8;12) (q24;q12) pat

Summary A case of Meckel or Gruber syndrome is reported, together with a survey of the relevant literature of recent years (1971–1977), in reference to a probably autosomal recessive inheritance of this malformation.     

Melanotropic activity of gamma MSH peptides in melanoma cells.

We studied the pigmentary activity of the peptides gamma 1, gamma 2 and gamma 3 melanocyte stimulating hormone (MSH), which differ in the structure of their C-termini, using hamster and mouse melanoma cell lines responsive to beta-MSH by increasing tyrosinase activity. Gamma 1-MSH alone or in combination with beta-MSH had no effect on either cell line. Gamma 2-MSH alone was biologically inactive but potentiated beta-MSH stimulation of tyrosinase activity. Gamma 3-MSH at high concentration (10 microM) induced tyrosinase activity and dendrite formation in the hamster melanoma line. When added together with beta-MSH, gamma 3-MSH partially inhibited the tyrosinase activity response to beta-MSH. Thus, gamma-MSH peptides have low intrinsic melanotropic activity in mammalian melanoma cells; the specific pigmentary responses appear to be affected by the structure of the C-terminal portion.     

The cyclic diguanylic acid regulatory system of cellulose synthesis in Acetobacter xylinum. Chemical synthesis and biological activity of cyclic nucleotide dimer, trimer, and phosphothioate derivatives

An unusual compound, cyclic-bis(3'----5') diguanylic acid (c-di-GMP or cGpGp), is involved in the regulation of cellulose synthesis in the bacterium Acetobacter xylinum. This cyclic dinucleotide acts as an allosteric, positive effector of cellulose synthase activity in vitro (Ka = 0.31 microM) and is inactivated via degradation by a Ca2(+)-sensitive phosphodiesterase, PDE-A (Km = 0.25 microM). A series of 13 analogs cyclic dimer and trimer nucleotides were synthesized, employing a phosphotriester approach, and tested for the ability to mimick c-di-GMP as activators of cellulose synthase and as substrates for PDE-A. Seven of the synthetic compounds stimulate cellulose synthase activity and all of these activators undergo the Ca2(+)-inhibited degradation reaction. The order of affinities for synthase activators is cGpGp approximately cdGpGp approximately cGp(S)Gp (S-diastereomer) greater than cIpGp greater than cdGpdGp greater than cXpGp greater than cIpIp greater than cGp(S)Gp (R-diastereomer). Three cyclic dinucleotides of negligible affinity for either enzyme are cApAp, cUpUp, and cCpCp. This same order of affinities essentially pertains to the analogs as inhibitors of PDE-A activity, but at least one cyclic dinucleotide, cXpXp, which does not bind to cellulose synthase, is also a substrate for the degradation reaction, demonstrating that although the two enzymes share a similar, high degree of specificity for c-di-GMP, their cyclic dinucleotide binding sites are not identical. Phosphodiester bonds of activators in which an exocyclic oxygen is replaced with an atom of sulfur (cGp(S)Gp isomers) resist the action of PDE-A, and such derivatives may be prototypes for synthetic non-hydrolyzable c-di-GMP analogs.