Activation of bovine liver glycerol kinase by ethanol.

The crystallization of bovine glycerol kinase (ATP:glycerol 3-phosphotransferase EC 2.7.1.30) is reported along with a study on the unusual activation of this enzyme by ethanol. The enzyme was extracted from calf lever andusual activation of this enzyme by ethanol. The enzyme was extracted from calf liver and purified 5900-fold giving crystals with a 5% yield. The kinetics of the enzyme with regard to glycerol and ATP were studied by varying the concentration of one substrate while keeping the other at saturating levels, and the effect of ethanol was observed by adding it at levels of 5% (v/v). Ethanol increased the V in both cases almost 2-fold. The apparent Km of ATP was 3.5 - 10(-6) and was increased to 7.6 - 10(-6) in the presence of ethanol. The apparent Km for glycerol was 3 - 10(-5) and was increased to 12 - 10(-5) when ethanol was added. A number of other alcohols had a similar activating effect except for 1,2-diols which only inhibited the enzyme. These findings are consistent with the explanation that alcohols compete with glycerol (hence also with the glycerophosphate product) for a hydroxy binding site on the enzyme. This leads to more rapid dissociation of the glycerophosphate (i.e. an increase in the steady-state constant, "k+2" resulting in an increased V).

Dietary supplementation with omega-3 fatty acids prolongs platelet survival in hyperlipidemic patients with atherosclerosis.

Enhanced dietary omega-3 fatty acid consumption is thought to be associated with a reduced incidence of atherothrombotic disorders. This effect may be mediated in part through suppression of in vivo platelet activity by omega-3 fatty acids. We observed that platelet survival, a sensitive indicator of in vivo platelet activity was prolonged from 6.4 +/- 1.5 days to 7.7 +/- 1.4 days by moderate amounts of dietary omega-3 fatty acid supplementation for 6 weeks in a group of hyperlipidemic patients with preexisting, established atherothrombotic disorders. This effect on platelet survival was associated with a decrease in platelet arachidonic acid levels from 26.7 +/- 3.5% to 20.9% +/- 2.5% and a rise in platelet eicosapentaenoic and docosahexaenoic acid measurements from essentially undetectable to 2.8% +/- 1.6% and 1.9% +/- 1.0%. Plasma total cholesterol, low-density lipoprotein cholesterol, and serum apolipoprotein B levels rose significantly during the omega-3 fatty acid supplementation period. Platelet aggregation did not change. This study demonstrates that a modest amount of dietary omega-3 fatty acid supplementation can significantly effect in vivo platelet activity in a population at high risk for recurrent atherothrombotic disorders.

Thyrotropin stimulation of 32P incorporation into the phospholipids of canine thyroid adenocarcinoma.

Six carcinomas of the canine thyroid were studied. Five of the six tumors were functional on 131I scan and caused hyperthyroidism in two cases. The tumors were all of predominantly compact cellular histology with rare to moderate numbers of microfollicles. After surgical removal tumor slices were incubated with 32P in Krebs-Ringer-tris buffer with or without 0.1 U/ml of bovine TSH, and the specific activity of the extracted phospholipids was measured. TSH stimulated phosphatide turnover clearly in 5 cases and probably also in the 6th. Analysis of fractionated phospholipids in 2 cases showed that the response to TSH was mainly in the phosphatidic acid and phosphatidylinositol. These studies show that a malignant tumor may still retain at least one complete control system extending from TSH receptors to the final metabolic response.

Acalculous cholecystitis: a case with variable cholescintigram.

A 62-yr-old man with acalculous cholecystitis is presented. At different stages of his disease his cholescintigram was abnormal and then normal. The case demonstrates the variations of the cholescintigram that may occur during the disease and illustrates the difficulties that may be encountered in making the diagnosis.

Uptake of 67Ga in the lactating breast and its persistence in milk: case report.

The concentration of 67Ga in the milk of a postpartum woman was measured at intervals up to 8 days after the injection of 3 mCi of 67Ga-citrate. The 67Ga concentration was about 0.15 muCi/ml at 3 days after injection and fell to 0.035 muCi/ml by 8 days. Since the biologic clearance of gallium was slow (T1/2 approximately 9 days), the major determinant of the clearance of radioactivity was the physical decay of the gallium. An estimate of the radiation dose to a nursing infant suggests that nursing be interrupted for about 2 weeks after the mother has had a 67Ga study.

Comparing filtered backprojection and ordered-subsets expectation maximization for small-lesion detection and localization in 67Ga SPECT.

UNLABELLED: Iterative reconstruction of SPECT images has recently become clinically available as an alternative to filtered backprojection (FBP). However, there is conflicting evidence on whether iterative reconstruction, such as with the ordered-subsets expectation maximization (OSEM) algorithm, improves diagnostic performance over FBP. The study objective was to determine if the detection and localization of small lesions in simulated thoracic gallium SPECT images are better with OSEM reconstruction than with FBP, both with and without attenuation correction (AC). METHODS: Images were simulated using an analytic projector acting on the mathematic cardiac torso computer phantom. Perfect scatter rejection was assumed. Lesion detection accuracy was assessed using localization receiver operating characteristic methodology. The images were read by 5 nuclear medicine physicians. For each reconstruction strategy and for each observer, data were collected in 2 viewing sessions of 100 images. Two-way ANOVA and, when indicated, the Scheffé multiple comparisons test were applied to check for significant differences. RESULTS: Little difference in the accuracy of detection or localization was seen between FBP with and without AC. OSEM with AC extended the contrast range for accurate lesion detection and localization over that of the other methods investigated. Without AC, no significant difference between OSEM and FBP reconstruction was detected. CONCLUSION: OSEM with AC may improve the detection and localization of thoracic gallium-labeled lesions over FBP reconstruction.

Spreading properties of dimyristoyl phosphatidylcholine at the air/water interface.

The spreading behavior of bulk lipid crystals and lipid dispersed in water has been investigated for dimyristoyl phosphatidylcholine at the air/water interface. The stable surface pressures reached with dispersed lipid were found to increase with lipid concentration up to a concentration of approximately 1.2 mg ml-1 where the spreading pressure approached 45 mN m-1, the value for excess lipid crystals placed on the surface (at 30.5 degrees C). These low surface pressures obtained with dispersions are attributed to the existence of 'pre-equilibria': surface pressures that appear steady because of the extremely slow approach to final equilibrium. Attainment of this pre-equilibrium condition usually takes about 20 h, whereas bulk crystals held at the surface generated a high and steady surface pressure within about 1 h. Hydration of the bulk lipid slows down the spreading rate, but does not affect the final surface pressure.

[Suicide risk and care of suicide attempters]. / Risques suicidaires et prise en charge des suicidants.

Starting from the notion of suicidal risk and a critique of its usage, it is possible to distinguish groups whose suicidal risk is particularly high. The suicidal group-composed of persons who have already attempted to commit suicide once-is in this paper the subject of general considerations as well as personal research. The latter shows that it is still difficult to detect those persons who are about to commit suicide and that tell-tale signs-be they clinical or resulting from tests-are still not very reliable. The difficulties encountered by secondary prevention are made obvious by two pieces of research done on the taking in charge of suicide-prone persons in a university general hospital. the timely recognition of the pre-suicidal syndrome and of the self-denial syndrome is very important for suicide prevention. Self-depreciation, and consequently the narcissistic blow is, as are the aggression phenomena, one of the psychological cores which lead to an act of suicide. Medical attitudes concerning the suicidal person are analyzed, and the difficulty in the psychotherapeutic relationship is stressed. Pratical considerations on the psychotherapeutic approach to the suicidal person close up the article.