The Electrical Conductivity of Bovine Milk in Mastitis Diagnosis

The electrical conductivity (EC) of milk is mainly a function of the electrolyte concentration in the milk and therefore raised in mastitis. The present investigation was aimed at elaborating, if possible, a diagnostic model for screening purposes based on EC determinations and consistent with the diagnostic procedures and interpretations commonly used in laboratory milk diagnosis in the Nordic countries (Klastrup 1975). According to this diagnosis (here called reference diagnosis) cell numbers above 300,000/ml (cell count or the corresponding CMT-score) in foremilk quarter samples during the main part of the lactation period and significantly above the lowest value on within-udder comparison during late lactation are considered indicative of mastitis and bacteriological examinations are made when called for.     

Formation of prostanoids in human umbilical vessels perfused in vitro

Four major prostanoids (6-keto-PGF1 alpha, PGE2, PGF2 alpha and TXB2) were measured by specific radioimmunoassays in the outputs from human umbilical vessels perfused in vitro. As evaluated by scanning electron microscopy (SEM) only few blood platelets were attached to the vessel wall. After an initial flush with decreasing concentrations of all four prostanoids, a stable stage was reached, lasting for 4-5 hours. During this stage the production could be inhibited by indomethacin and only slightly stimulated with arachidonic acid. The TXA2 synthetase inhibitor UK 38485 depressed the TXB2 production, while only slightly affecting the other three prostanoids at very high concentrations. The arteries produced relatively more 6-keto-PGF1 alpha than did the vein.     

Aerodynamics of Ephedra trifurca

Computer simulations are used to predict the behavior of pollen grains with different physical properties within the acceleration field created around the ovules of the gymnosperm Ephedra trifurca. A modelling procedure is given that (1) calculates the number of pollen grains captured by an ovule's pollination-droplet and (2) gives a correlation between pollination efficiency and the physical properties (= mass, size) of different types of pollen. Based on this procedure, the number of Ephedra pollen grains captured by micropyles can be less than the number captured from other species. However, the mass and size of Ephedra pollen grains appear to coincide with those predicted to yield a local maximum of pollination efficiency, i.e. slightly larger or smaller values of either mass or size would decrease the probability of capture. In addition, the properties of Ephedra pollen grains operate synergistically in the aerodynamic environment around ovules and are focused to collide with pollination-droplets. By analogy, the properties of Ephedra pollen coincide with those predicted for a localized adaptive peak. The physical properties of pollen grain types other than E. trifurca that can maximize pollen capture are not generally represented in the aerobiology of Ephedra during the pollination season. Therefore, the phenology of pollen release, community taxonomic-composition, and the physics of particle capture play collectively important roles in the reproductive success of Ephedra trifurca.     

Dilution and acidification effects during the spring flood of four Swedish mountain brooks

The seasonal variation in water chemistry was followed during 1980 and 1981 in four mountain brooks in the southern part of Swedish Lapland. In the area investigated the soil is calcareous and the brook water is very well buffered during the major part of the year, with alkalinity varying between 0.4 and 1.0 milliequivalents per liter and with pH values about 7.5. These years the snow had a pH of approximately 5.2, which was considerably higher than has been reported from adjacent areas in the lower, coniferous region. During snowmelt the water discharge increased drastically, and although the net transport of bicarbonate increased, alkalinity showed low values due to dilution with meltwater. pH decreased, but not further than to 6.3–6.5, far from values reported in 1979 (pH less than 5), apparently due to the comparatively clean snow. A slight deficit in alkalinity, as compared to the nonmarine calcium and magnesium content, points to an acidification impact on the area. During maximum runoff some chemical variables, like aluminium, iron, nitrogen and phosphorus, behaved reversely to what might be expected during dilution and reached maxima in concentrations. It is concluded that the extreme runoff characteristics of high mountain areas make brook water more sensitive to acid precipitation than might be expected when regarding only the calcareous properties of soil and bedrock.     

25-Hydroxyvitamin D3-24-hydroxylase in rat kidney mitochondria

Assay conditions for the measurement of 25-hydroxyvitamin D3-24-hydroxylase activity in rat kidney mitochondria have been worked out. The product, 24,25-dihydroxyvitamin D3 was quantitated either by high pressure liquid chromatography or by isotope dilution-mass spectrometry. By these procedures, the enzyme activity could be measured with saturating concentration (greater than 2.5 X 10(-6) M) of substrate. Pretreatment of the animals by aminophylline (Kulkowski, J. A., Chow, T., Martinez, J., and Ghazarian, J. G. (1979) Biochem. Biophys. Res. Commun. 90, 50-57) stimulated the 24-hydroxylase activity in vitro at least 2 to 3-fold. The identity of the product was verified by gas chromatography-mass spectrometry. The rates of the reaction varied between 1.5 and 5 pmol/mg of mitochondrial protein.min (at 25 degrees C), and the K'm was determined to be 4.2 X 10(-7) M. Malate, succinate, and isocitrate were all able to support the reaction. Low O2 tension, CO, KCN, and the uncoupler carbonyl cyanide m-chlorophenylhydrazone inhibited the reaction, while the respiratory inhibitor rotenone had no effect. Metyrapone inhibited the reaction with 50% inhibition at a concentration of 2.5 mumol/ml. The enzyme was found to be localized inside the inner mitochondrial membrane. The results indicate that in the rat the renal mitochondrial 25-hydroxyvitamin D3-24-hydroxylase is a cytochrome P-450 and that the reducing equivalents are primarily supplied by NADPH via the energy-dependent transhydrogenase.     

Evidence for a lack of regulatory importance of the 12 alpha-hydroxylase in formation of bile acids in man: an in vivo study

The possibility that the 12 alpha-hydroxylase involved in formation of bile acids is of regulatory importance for the ratio between cholic acid and chenodeoxycholic acid in bile was studied with an in vivo technique. [4-14C]7 alpha-Hydroxy-4-cholesten-3-one and [6 beta-3H]7 alpha, 12 alpha-dihydroxy-4-cholesten-3-one were synthesized, and a mixture of these two bile acid intermediates was administered intravenously in five healthy subjects and in one patient with severe liver cirrhosis. The patient with liver cirrhosis was included in the study because of a considerable reduction in biosynthesis of cholic acid. Since the [4-14C]-labeled steroid is an intermediate just proximal to and since the [6 beta-3H]-labeled steroid is an intermediate just distal to the 12 alpha-hydroxylase step, the 3H/14C ratio in the cholic acid formed should reflect the relative 12 alpha-hydroxylase activity. The 3H/14C ratio varied between 1.8 and 3.9 in the cholic acid isolated from the healthy subjects and was 3.6 in the cholic acid isolated from the patient with liver cirrhosis. The ratio between cholic acid and chenodeoxycholic acid varied between 0.6 and 3.9 in the bile from the control subjects and was only 0.4 in the bile from patients with liver cirrhosis. There was no correlation between the 3H/14C ratios and the ratios between cholic acid and chenodeoxycholic acid in bile.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oxidation of omega-hydroxylated fatty acids and steroids by alcohol dehydrogenase

Recrystallized alcohol dehydrogenase from horse liver was found to oxidize 17-hydroxystearic acid into 17-oxostearic acid, the 17-L-enantiomer faster than the 17-D-enantiomer. Alone at high pH or in combination with aldehyde dehydrogenase, the alcohol dehydrogenase also catalyzed conversion of 18-hydroxystearic acid into 1, 18-octadecadioic acid and 5β-cholestane-3α,7α,12α,26-tetrol into 3α,7α,12α-trihydroxy-5β-cholestanoic acid. All the activities as well as the ethanol dehydrogenase activity disappeared after specific carboxymethylation of a single cystein residue at the active site of alcohol dehydrogenase. These results conclusively show that alcohol dehydrogenase itself has ω-hydroxyfatty acid dehydrogenase activity and ω-hydroxysteroid dehydrogenase activity.     

A histochemically demonstrable thiaminepyrophosphatase activity in the sinusoidal endothelium of the liver

Summary A new histochemically demonstrable thiaminepyrophosphatase activity in liver tissue is described. It appears to be localized solely to the cytosomes of the sinusoidal endothelium. The activity, which requires high concentration of lead ion for its demonstration, has a high degree of substrate specificity. It resists formaldehyde fixation, ethanol and many inhibitors. The optimum pH is at pH 6.This study was supported in part by a grant from the Swedish Medical Research Council.