Risk factors for early death in non-insulin dependent diabetes and men with known glucose tolerance status.

OBJECTIVE--To identify risk factors for all cause mortality according to glucose tolerance status. DESIGN--Cohort study with an average 15.6 years'' follow up. SETTING--Paris, France. SUBJECTS--7166 working men aged 44-55 in 1968-72 in the Paris prospective study cohort, with non-insulin dependent diabetes or known result of two hour 75 g oral glucose tolerance test. MAIN OUTCOME MEASURES--Risk factors for death from all causes. RESULTS--128 men were known to be diabetic, 180 had diabetes diagnosed, and 697 had impaired glucose tolerance diagnosed. Compared with normoglycaemic men the relative risks of death in these groups were 2.0 (95% confidence interval 1.4 to 3.0), 2.7 (2.0 to 3.6), and 1.6 (1.3 to 2.0) respectively. Obesity, smoking, high blood pressure, and high non-esterified fatty acid concentration were risk factors for death in all subjects and were unaffected by glucose tolerance. The risks for fasting and two hour insulin concentrations and mean corpuscular volume were two times higher in known diabetic men than in men not known to be diabetic. Central obesity was significant only in men not known to be diabetic (1.6 (1.4 to 1.9)). In known diabetic men a two hour glucose concentration higher than 11.1 mmol/l carried a relative risk of death of 3.8 (1.4 to 9.4). CONCLUSIONS--Diabetic men have similar risk factors for early mortality to other men but are at higher risk from hyperinsulinaemia, hyperglycaemia, and high mean corpuscular volume.     

Growth and Osmotic Adjustment of Cultured Suspension Cells from Alternanthera philoxeroides (Mart.) Griseb After an Abrupt Increase in Salinity

We have developed a cell suspension culture from alligator weed(Alternanthera philoxeroides [Mart.] Griseb), a C₃ member ofthe Amaranthaceae. Intact plants of alligator weed can growat 400 mol m^–3 NaCl. Growth of alligator weed suspensionswas compared to growth of tobacco (Nicotiana tabacum L. cv.Wisconsin 38) suspensions after subculture to 200 mol m^–3NaCl. Fresh weight and cell density of salt-treated alligatorweed suspensions more than doubled by 7 d after subculture,but the fresh weight of salt-treated tobacco suspensions didnot double during the 21 d experiment. Correspondingly, cellviability dropped from about 90% to 77% in alligator weed andto 41% in tobacco, at 1 d after subculture to 200 mol m^–3NaCl. The symplastic volume of alligator weed cells declined36% by 2 h after subculture to 200 mol m^–3 NaCl, but cellcontents became iso-osmotic with the media at this point. Between2 h and 6 h there was a further decrease in osmotic potential,an increase in turgor potential and a partial recovery of symplasticvolume. Turgor potential was similar to that in control cellsby 24 h, indicating significant osmotic adjustment. Turgor potentialsremained similar in both treatments from 24 h through 21 d butthe average symplastic volume of salt-treated cells was 11 %less than in control cells. Therefore, alligator weed suspensioncells exhibit a rapid recovery of water balance and cell growthafter an abrupt and substantial increase in salinity. Key words: Cell culture, growth, osmotic adjustment, salinity, turgor potential     

Near ultraviolet light inactivation of dihydroxyacid dehydratase in Escherichia coli

The effects of near ultraviolet (NUV) light on a NUV chromophore-containing oxidant-sensitive enzyme, dihydroxyacid dehydratase (DHAD), were measured in seven strains of Escherichia coli. The strains differed in production of the oxidant-defense enzymes, superoxide dismutases (Fe-SOD and Mn-SOD), and catalases HPI and HPII. With the stress of aerobic growth but without NUV exposure, the strains lacking either Fe or Mn SOD or both SODs had 57%, 25%, and 12%, respectively, of the DHAD-specific activity of the parent (K12) strain. Under the same conditions, the catalase strains that were wild type, overproducing, and deficient had comparable DHAD-specific activities. When aerobic cultures were exposed for 30 min to NUV with a fluence of 216 J/m²/s at 310–400 nm, the percentage decreases in DHAD-specific activities were similar (ranging from 75% to 89%) in strains with none, either, or both SODs missing, and in the catalase-overproducing strain. However, the decreases were only 58% and 52% in the strain with catalase missing and in its parent, respectively. The NUV-induced loss of DHAD enzyme activity was not accompanied by any detectable loss of the DHAD protein as measured by polyclonal antibody to DHAD.     

Mu-opioid-receptor-mediated inhibition of the N-type calcium-channel current.

The predominant consequences of mu-opioid-receptor activation are depression of both neuronal activity and transmitter release. Mu-Opioid agonists have previously been observed to increase a potassium conductance and to inhibit adenylate cyclase. We now report that activation of mu-opioid receptors directly decreases the N-type calcium-channel current in a differentiated, human neuroblastoma cell line (SH-SY5Y). The coupling between the mu-opioid receptor and the calcium channel involves a pertussis toxin-sensitive G protein and is independent of changes in adenylate cyclase activity. The inhibition of the calcium-channel current is voltage dependent because it is largely overcome by strong membrane depolarization. It is not associated with changes in the kinetics of current inactivation. Therefore, the mu-receptor belongs to the superfamily of G-protein-coupled, inhibitory neurotransmitter receptors which modulate the activity of calcium and potassium channels and adenylate cyclase.     

Displacement of hepatic ornithine carbamoyltransferase from mitochondria to cytosol in Reye's syndrome.

In two patients with fatal Reye's Syndrome, total ornithine carbamoyltransferase (OCTase) activity in the liver was 50 and 75% of that found in three control livers. The levels of enzymatic activity would not be expected to have resulted in the 7- and 17-fold elevations in plasma ammonia levels found in the patients. Levels of 47 and 60% of the OCTase activity, however, were found in the cytosolic fraction compared to an average of 7% for control livers. Thus, the amount of enzymatic activity in the mitochondrial fractions was only 20 and 30% of that found in control mitochondrial fractions. This study suggests that, if only mitochondrial OCTase is active in the urea cycle, the decreases in functional enzyme found in Reye's Syndrome may be considerably greater than that reflected in total enzyme assays.     

Translation and ribosome assembly in extremely thermophilic archaebacteria.

Several features of translation and ribosome structure in extremely thermophilic, sulfur-dependent archaebacteria are described, including: i) a peculiar mechanism of transfer RNA-mediated 70S ribosome formation from free subunits; ii) poly(U)translation by hybrid ribosomes composed by one archaebacterial and one eucaryotic subunit; iii) ribosome assembly and homologous and heterologous RNA/protein recognition.