N2-(1-carboxyethyl)methionine. A ''pseudo-opine'' in octopine-type crown-gall tumours.

A novel methionine-containing plasmid-determined compound, N2-(1-carboxyethyl)methionine (NCEM) has been identified in crown-gall tumours induced by octopine-type strains of Agrobacterium tumefaciens. NCEM is probably synthesized by octopine synthase. Cell-free preparations from octopine-type strains of A. tumefaciens can degrade NCEM; however, the bacterium cannot transport the compound into the cell, although these strains can take up and degrade the octopine family of opines.     

Role of K+, Na+, and Ca2+ ions in the cardiodepressive action of blood plasma in burn shock and the crush syndrome

Ion-selective electrodes were employed to measure the concentration of K+, Na+ and Ca2+ in blood plasma of rabbits with burn shock or crush syndrome (CS). No significant changes in the plasma concentration of Na+, and Ca2+ were found under both pathological conditions. The plasma concentration of K+ in burn shock significantly increased from 3.06 +/- 0.73 (control) to 5.28 +/- 2.65 mM (n = 10), whereas in CS from 3.42 +/- 1.03 to 4.92 +/- 1,29 mM (n = 8). The rise of K+ concentration in the control plasma to the maximal values seen in the "burn" and "syndrome" plasma led to an increase in the duration of intracellular action potentials (AP) but did not substantially change the amplitude of isometric contractions of the papillary muscles of rabbit heart. Meanwhile the similar rise of the duration of intracellular AP during perfusion of the papillary muscles with the "burn" and "syndrome" plasma was accompanied by an appreciable drop of the amplitude of isometric contractions. It is suggested that elevation of K+ concentration in blood plasma, inducing an increase in the duration of intracellular AP of cardiocytes may be responsible for changes in the ECG in burn and CS. At the same time inhibition of myocardial contractility in burn shock and CS is virtually not linked with hyperkalemia.     

How the activity of membrane enzymes is regulated

The pattern of dependence of catalytic function for a number of key membrane bound enzymes on the state and properties of their lipid environment is analysed in the review presented. Using hexokinase, cytochrome c-oxidase, transport ATPases and other membrane bound oligomeric systems it has been shown that phospholipid bilayer regulates the interaction of protein components of these ensembles in the bilayer. This feature of membrane structures regulates the substrate accessibility and affinity to the corresponding active centres, the formation and a life-time of the oligomeric associates (that is especially important for membrane channels), their stability and so on. As the microviscosity of membrane bilayer is strongly modified not only in the course of pathologic but also in the process of adaptive alterations as well as depending on the day time, season and as a result of action of biologically active substance on membrane, the regulation of the functional activity of membrane proteins by this factor is an effective mode for metabolic control.     

Action of benzohydrothiochromylium salts on bacterial membranes

Cultivation of Staphylococcus 209-P and Micrococcus lysodeikticus cells on media containing new antibacterial preparations--iodide and trifluoroacetate derivatives of benzohydrothiochromylium resulted in a remarkable lesion of the membrane respiratory apparatus, i.e. the amounts of membrane polypeptides, the specific concentration of cytochromes, the activities of reductases and oxidases--NADH, malate and lactate decreased. Profound changes in the cell cytology were observed.     

Submicroscopic changes in the capillary cells of an area of osteogenesis during body uptake of lead acetate

Ultrastructurometry has revealed that daily entry of lead acetate in a dose of 50-100 mg/kg per body weight for 1-2.5 months increases chromatin condensation in nuclei, promotes swelling and myelin-like degeneration of the mitochondria, hyperplasia of the endoplasmic net, as well as appearance of the "enlightment" zones in the cytoplasm of endotheliocytes and perivascular cells of the capillaries from a metaphyseal zone of the rat femur. These changes are a consequent of the edema of cells and of the decrease in their biosynthetic activity.     

Reduction in headache patients' medical expenses associated with biofeedback and relaxation treatments

Comparisons are made of self-reported medical costs from a sample of headache patients who underwent various combinations of relaxation training and biofeedback training. The average costs for the 2 years prior to self-regulatory treatment were $955±480 (3 SEM) for 45 patients; for the 2 years after completing treatment the average costs were $52±28 (3 SEM) for patients. Within the limitations of the study, medical costs do seem to have been markedly reduced.This research was supported by a grant from NINCDS, NS-15235.     

Headache at high altitude is not related to internal carotid arterial blood velocity

The cause of headache in persons going to high altitude is unknown. Relatively severe hypoxemia in susceptible subjects could induce large increases in cerebral blood flow that then could initiate the headache. Thus we measured noninvasively, by Doppler ultrasound, changes in internal carotid arterial blood velocity (velocity) in 12 subjects in Denver (1,600 m) and repeatedly up to 7 h at a simulated altitude of 4,800 m (barometric pressure = 430 Torr). Six subjects, selected because of prior history of high-altitude headache, developed comparatively severe headache at 4,800 m, and four subjects, without such history, remained well. Two subjects developed moderate headache. Velocity at 4,800 m did not correlate with symptom development, arterial O2 saturation, or end-tidal PCO2. Also, neither velocity nor blood pressure was consistently elevated above the Denver base-line values. During measurements of hypercapnic ventilatory response in Denver, velocity increased linearly with end-tidal PCO2, confirming that our Doppler method could demonstrate an increase. Also, 30 min of isocapnic or poikilocapnic hypoxia caused small increases in velocity (+8 and +6%) during the base-line measurement at low altitude. Although even a small increase in cerebral perfusion could contribute to headache symptoms at high altitude, cerebral blood flow does not appear to play a primary role.