The regulation of 3-hydroxy-3-methylglutaryl-CoA reductase activity, cholesterol esterification and the expression of low-density lipoprotein receptors in cultured monocyte-derived macrophages.

Human blood monocytes cultured in medium containing 20% whole serum showed the greatest activity of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase and [14C]acetate incorporation into non-saponifiable lipids around the 7th day after seeding, the period of greatest growth. Although there was enough low-density lipoprotein (LDL) in the medium to saturate the LDL receptors that were expressed by normal cells at that time, HMG-CoA reductase activity and acetate incorporation were as high in normal cells as in cells from familial-hypercholesterolaemic (FH) patients. Both the addition of extra LDL, which interacted with the cells by non-saturable processes, and receptor-mediated uptake of acetylated LDL significantly reduced reductase activity and increased incorporation of [14C]oleate into cholesteryl esters in normal cells and cells from FH patients ('FH cells'), and reduced the expression of LDL receptors in normal cells. Pre-incubation for 20h in lipoprotein-deficient medium apparently increased the number of LDL receptors expressed by normal cells but reduced the activity of HMG-CoA reductase in both normal and FH cells. During subsequent incubations the same rate of degradation of acetylated LDL and of non-saturable degradation of LDL by FH cells was associated with the same reduction in HMG-CoA reductase activity, although LDL produced a much smaller stimulation of oleate incorporation into cholesteryl esters. In normal cells pre-incubated without lipoproteins, receptor-mediated uptake of LDL could abolish reductase activity and the expression of LDL receptors. The results suggested that in these cells, receptor-mediated uptake of LDL might have a greater effect on reductase activity and LDL receptors than the equivalent uptake of acetylated LDL. It is proposed that endogenous synthesis is an important source of cholesterol for growth of normal cells, and that the site at which cholesterol is deposited in the cells may determine the nature and extent of the metabolic events that follow.     

Physiological Studies of Methane and Methanol-Oxidizing Bacteria: Oxidation of C-1 Compounds by Methylococcus capsulatus

Methylococcus capsulatus grows only on methane or methanol as its sole source of carbon and energy. Some amino acids serve as nitrogen sources and are converted to keto acids which accumulate in the culture medium. Cell suspensions oxidize methane, methanol, formaldehyde, and formate to carbon dioxide. Other primary alcohols are oxidized only to the corresponding aldehydes. Oxidation of formate by cell suspensions is more sensitive to inhibition by cyanide than is the oxidation of other one carbon compounds. This is due to the cyanide sensitivity of a soluble nicotinamide adenine dinucleotide-specific formate dehydrogenase. Oxidation of formaldehyde and methanol is catalyzed by a nonspecific primary alcohol dehydrogenase which is activated by ammonium ions and is independent of pyridine nucleotides. Some comparisons are made with a strain of Pseudomonas methanica.     

A study of diabetes in relation to blood groups and cholesterol levels

Summary Four hundred and sixteen patients suffering from diabetes were studied for AB0 Rhesus blood groups, to find out whether there is any association between blood group and diabetes. Though the relative incidence was found to be higher in blood group 0 and B, the difference was not statistically significant. This study confirms the earlier findings of high cholesterol levels in diabetes, particularly in patients with blood groups A and AB, and the overall mean cholesterol level as 253 mg/100 ml. This study also shows that diabetes with a cholesterol level of more than 300 mg/100 ml is a coronary risk factor.

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Zusammenfassung 416 Patienten mit Diabetes wurden nach AB0 und Rh untersucht, um Assoziationen zwischen Blutgruppe und Diabetes zu finden. Es fand sich ein leichtes, nicht signifikantes Überwiegen von 0 und B. Ein besonders hoher Serum-Cholesteral-Spiegel fand sich beim Diabetes insbesondere bei Patienten der Gruppen A und AB. Die Studie zeigt auch, daß ein Cholesteral-Spiegel von mehr als 300 mg% ein Risikofaktor für Coronarerkrankungen ist.

     

Physiological Studies of Methane- and Methanol-Oxidizing Bacteria: Immunological Comparison of a Primary Alcohol Dehydrogenase from Methylococcus capsulatus and Pseudomonas sp. M27

A primary alcohol dehydrogenase was purified from cell extracts of two apparently unrelated microorganisms, namely, Pseudomonas sp. M27 and Methylococcus capsulatus. Rabbit antiserum prepared against the purified enzyme from M. capsulatus revealed distinctive antigenic determinants by quantitative and gel precipitin reactions. Rabbit antiserum to M27 enzyme detected both distinctive and shared antigenic determinants. Certain methane- and methanol-oxidizing bacteria were grouped on the basis of serological cross-reacting enzyme specificities.     

Determination of each constituent in mixtures of catechol and protocatechuic acid,quinol and gentisic acid,phenol and p-hydroxybenzoic acid,and pyrogallol and gallic acid

Simple, rapid spectrophotofluorometric methods were developed for determining each constitutent in the mixtures of catechol and protocatechuic acid and in mixtures of quinol and gentisic acid. A colorimetric method involving the use of 4-aminoantipyrine and extraction with chloroform was proposed for determining each constituent in mixtures of phenol and p-hydroxybenzoic acid. Two simple and rapid colorimetric methods were used in conjunction to determine each constituent in mixtures of pyrogallol and gallic acid. The accuracy of all methods was within ±5%.     

Effect of different iron-, potassium-, phosphate-, and calcium-manganese relationships on the growth and chemical composition of aromatic strain of bidi tobacco (Nicotiana tabacum L.)

Summary In order to study the Mn nutrition ofbidi tobacco plant (Nicotiana tabacum L. aromatic strain 2-1) when it is supplied with nutrient solutions containing different ratios of Mn with Fe, P, K and Ca, a sand-culture experiment was carried out in four different series viz. Fe-Mn, K-Mn, P-Mn and Ca-Mn. No characteristic deficiency symptoms except general loss of green colour and diminished growth were observed at 0.1 ppm Mn in the nutrient solution. Toxicity was observed when Mn in the nutrient solution was 100 ppm and severity of the symptoms decreased with increase in Fe-Mn or K-Mn ratios, but it increased when P-Mn ratio increased while in Ca-Mn series it first decreased and then increased at still higher concentration of Ca on account of chloride ion effect as CaCl₂ had to be added to bring about 500 ppm concentration of Ca necessary for the treatment. No symptoms of deficiency or toxicity were observed when Mn in nutrient solution varied from 1 to 10 ppm and Fe-Mn ratio for the leaf varied from 0.4 to 6.1 and its Mn content varied from 190 to 1575 ppm. Slight loss of green colour and plant vigour appeared when Fe-Mn ratio for the leaf was higher than 12.8 even though the Mn content was as high as 90 ppm. Toxic effect due to excessive Mn was felt when Fe-Mn ratio was 0.35 or less and leaf content 1875 ppm or more. Nicotine content was inversely related to the intensity of Mn-toxicity.Contribution from the Agricultural Chemistry and Soil Science Division, Institute of Agriculture, Anand, G.S., India.Prof. and Head of the Agricultural Chemistry and Soil Science Division, and Lecturer in Agricultural Chemistry, respectively.