Comparative study of the phospholipid composition of plasma membranes isolated from rat primary hepatomas induced by 3'-methyl-4-dimethylaminoazobenzene and from normal growing rat livers

Plasma membranes (PM's) were isolated from primary hepatomas induced in Wistar rats by 3'-methyl-4-dimethylaminoazobenzene, from nonhepatomal regions of the same rat livers, and also from various normal rat livers, including the resting and regenerating livers of adult rats and developing livers of postnatal rats. Phospholipid analyses of these PM preparations revealed the following differences in the hepatoma PM in comparison with those of the PM of normal adult resting livers: (a) decrease in the content of total phospholipids; (b) large increase in plasmalogen content; (c) relative increase of sphingomyelin and ethanolamine phospholipids, and the decrease of choline phosphoglycerides, i.e., decrease of the ratios of choline phosphoglycerides to choline phosphosphingoside and of choline-containing phospholipids to ethanolamine-containing phospholipids; (d) decrease in phosphatidylserine and phosphatidylinositol. The phospholipid composition of the PM's from normal growing livers showed definite decreases in phosphatidylserine and sphingomyelin and increases in ethanolamine phospholipids; however, no significant alteration was observed in plasmalogen content in comparison to the PM of normal adult resting livers. The PM from the nonhepatomal regions of the hepatoma-bearing livers did not show those differences observed in hepatoma PM.

Isolation of octapeptin D (studies on antibiotics from the genus Bacillus. XXVII)

A new peptide antibiotic complex, named octapeptin D, was isolated from culture broth of a microorganism belonging to the genus Bacillus. The trihydrochloride of the antibiotic was obtained as a colorless powder, soluble in water and methanol. The empirical formula, C47H88N12O11.3HCl.H2O, was indicated by elemental analysis. Amino acid analysis on the acid hydrolyzate demonstrated the presence of 2,4-diaminobutyric acid (4 moles), serine (1 mole) and leucine (3 moles). Gas chromatographic analysis with the methylated product of the ethereal extract of the acid hydrolyzate revealed the presence of beta-hydroxy isodecanoic acid, beta-hydroxy decanoic acid, beta-hydroxy isoundecanoic acid and beta-hydroxyanteisoundecanoic acid. Octapeptin D is active against Gram-negative and Gram-positive bacteria in vitro and in vivo.

Tendomycin, a new antitumor antibiotic isolated from Streptomyces No. 9034

A new antibiotic designated tendomycin was isolated from the culture of Streptomyces No. 9034. The antibiotic is active against Gram-positive bacteria, fungi and cultured cancer cells, and shows an inhibitory effect of EHRLICH carcinoma in mice.

Role of somatic afferents in autonomic system control of the intestinal motility

(1) In anesthetized (chloralose-urethane) rats, strong mechanical stimuli which were applied to the abdominal skin always inhibited motility of the small intestine. This reflex is referred to as an 'inhibitory cutaneo-intestinal reflex'. Similar stimuli applied to the skin of the upper chest, neck, forepaws, or hindpaws, however, evoked the opposite effect, which is referred to as a 'facilitatory cutaneo-intestinal reflex'. (2) By recording the activity of efferent sympathetic nerves to the small intestine and by transecting intestinal sympathetic or parasympathetic nerves we found that the inhibitory cutaneo-intestinal reflex was largely due to an increase in intestinal sympathetic efferent activity, and that the facilitatory cutaneo-intestinal reflex was due to decrease in the intestinal sympathetic efferent nerve activity; both changes reflexly evoked. (3) The inhibitory cutaneo-intestinal reflex was shown to be a propriospinal reflex which was caused by excitation of group IV (unmyelinated) cutaneous afferent nerve fibers. On the other hand, the facilitatory cutaneo-intestinal reflex seemed to be mediated through supraspinal pathways, and was evoked by excitation of mainly group III (A-delta group) cutaneous afferent nerve fibers. (4) Interaction between the cutaneo-intestinal reflex and intestino-intestinal reflex was demonstrated. (5) The possibility of a dorsal root reflex contribution to cutaneo-intestinal reflex was eliminated. (6) Significance of the cutaneo-intestinal reflex in neural control of the gastro-intestinal tract was discussed.

Alterations of lipid and protein composition in myelin of acute experimental allergic neuritis

Lipid and protein components of the myelin isolated from the spinal roots of rabbits at the acute stage of experimental allergic neuritis (EAN) and of control rabbits were analyzed. The results obtained from the EAN myelin in comparison with the control myelin were as follows: (1) The content of cholesterol increased and that of cerebroside significantly decreased, while the content of plasmalogen and phospholipid was not changed. The level of cholesterol ester was negligible both in EAN and control myelin. (2) The sum of saturated fatty acids increased while the sum of unsaturated fatty acids decreased. (3) The decrease of the basic proteins P1 and P2 was more noticeable than that of the PO + Y protein. Concomitant to these observations, with 1,6-diphenyl 1,3,5-hexatriene as a fluorescent probe, the microviscosity of the isolated myelin was measured. The results indicated that myelin obtained from EAN was less fluid. Diminished myelin fluidity in EAN was consistent with the results of the lipid and fatty acid analyses.

IgE antibodies produced in mice instrumental in analyses of antigenicity of cephalothin preparation

IgE antibodies to a cephalothin preparation were produced in mice which had been immunized with cephalothin-Ascaris extract conjugate mixed with Al(OH)3 gel plus Bordetella pertussis. Mice which had been irradiated just before receiving the booster injection wtih the conjugate showed higher IgE antibody levels against the preparation in comparison with unirradiated mice. The specificities of IgE antibodies against the preparation were examined with an inhibition test of passive cutaneous anaphylactic (PCA) reaction. The intensity of the PCA reaction evoked by the cephalothin preparation in the rats was substantially or partially reduced by a pretreatment of the animals with an injection of a cephalothin preparation from another source or a cephaloridine preparation. Meanwhile, a prior injection of a cefazolin, a 7-aminocephalosporanic acid, a benzylpenicillin (PcG) preparation, or an aminobenzylpenicillin preparation into the animals showed only weak or no influence on the PCA reaction. These results suggest that the acyl side chain of cephalothin plays an important role as eliciting antigenic determinant in the PCA reaction. The difference in the antigenic specificity between the cephalothin and PcG preparation is also discussed.

Rhythmic patterns of discharge in hypothalamic neurosecretory neurons of cats and dogs

Recent studies in rats suggest that vasopressin- and oxytocin-secreting neurons in supraoptic nuclei and paraventricular nuclei of the hypothalamus show two different patterns of activity: one a "bursting" or rhythmic pattern and the other, irregular continuous discharges. This possibility was investigated in cats and dogs anesthetized with chloralose or Nembutal by recording electrical activity of single supraoptic and paraventricular neurons. Only some of the "identified" neurosecretory cells showed rhythmic, intermittent discharges ("bursting" cells in rats); the majority showed an irregular continuous firing pattern. Furthermore, the pattern of discharge sometimes changed from one ot the other during long periods of observation. This occurred without apparent stimulus in certain instances; in others, the rhythmic firing was associated with fluctuation in blood pressure and heart rate and was likely to be caused by changes in baroreceptor activity. Possible origins of rhythmic discharges and the physiological importance of such patterns in terms of hormone secretion are discussed.

Effect of different physical states of phospholipid substrates on partially purified platelet phospholipase A2 activity

Partial purification of alkaline phospholipase A2 (EC 3.1.1.4) from rabbit platelets was carried out and the effect of different physical states of the substrate phosphatidylcholine on the activity was investigated. (1) The enzyme was purified about 1020-fold by means of Sephadex gel chromatography after extraction from a particulate fraction of rabbit platelets, followed by CM-cellulose chromatography, and had a molecular weight of approx. 12 000 as determined by gel chromatography. (2) The activity of the purified enzyme was enhanced by the addition of detergents. Sodium deoxycholate and sodium cholate markedly stimulated the activity, and the effect of these substances was observed well below the critical micelle concentrations. Triton X-100 stimulated the activity moderately, and the activation was observed only above the critical micelle concentration. (3) The addition of negatively charged phospholipids to the substrate egg phosphatidylcholine induced a moderate activation of hydrolysis. (4) The addition of long-chain cation to the substrate induced an inhibition of the activity, whereas the addition of long-chain anion activated the hydrolysis of egg phosphatidylcholine, but did not activate the hydrolysis of phosphatidylcholine in the total lipid extract of rabbit platelets. (5) Hydrolysis of dimyristoyl phosphatidylcholine increased in the temperature region of the phase transition of the substrate. Addition of cholesterol at the concentration of 20 mol% diminished the effect of phase transition. (6) Release of [1-14C]arachidonic acid from an equimolar mixture of egg phosphatidylcholine with dipalmitoyl or distearoyl phosphatidylcholine was activated at the temperature of 0 degrees C or 20 degrees C, respectively. From these results, we suggest that platelet phospholipase A2 can be activated to release fatty acids from the platelet phospholipids at the domains within membranes, where exist the structural irregularities and/or accumulation of negative charge within the bilayers.

Reciprocal and non-reciprocal action of the vagal and sympathetic nerves innervating the heart

Simultaneous recordings were made from vagal and sympathetic fibers innervating the heart in dogs anesthetized with chloralose. Reciprocal relationship between the two autonomic nerves was clearly seen in the baroreceptor reflex. Stimulation of chemoreceptors, however, evoked non-reciprocal responses of the two nerves; at the onset of the chemoreceptor reflex cardiac vagal and sympathetic discharges both increased, then, as baroreceptors became excited due to a pressor response, sympathetic nerve activity suddenly decreased while vagal discharges remained high, indicating the appearance of the reciprocal action typifying the baroreceptor reflex. Decrease in ventilatory volume and a slight increase in end-expired CO2 level augmented greatly both vagal and sympathetic discharges. As the phrenic-locked activity of the two nerves (i.e. the activity in vagus nerve occurs only in the absence of phrenic bursts while sympathetic discharges increase with phrenic bursts) increased, the alternate discharges between the two nerves became more conspicuous and the heart rate fluctuated with the respiratory (phrenic) rhythm. Thus, strong reciprocity between vagus and sympathetic can result in an oscillatory heart rate. When ventilatory volume was increased, both nerve activities decreased below control level. Mild hypoxia had similar effects to hypercapnia though changes in nerve activity were greater. When coactivation of vagal and sympathetic nerve was produced in reflex action, changes in vagal discharges occurred earlier and faster than in the sympathetic fibers. The magnitude of change in vagus activity was also far greater. The elimination of afferents in the vagi, the aortic and sinus nerves reduced cardiac vagal activity greatly. However, discharges were still present and occurred between phrenic bursts, indicating that the vagal "tone" is maintained centrally as well as peripherally by input from receptors in the cardiovascular system. The physiological significance of reciprocal and non-reciprocal control of vagal and sympathetic nerves innervating the heart was discussed.

Trophic effect of tetragastrin on the stomach, duodenum and pancreas in rats

Subcutaneous injections of a large dose of tetragastrin (2 mg/day) into a rat for 4 weeks caused hypertrophy of parietal cells of the stomach, intestinal glandular cells of the duodenum, and pancreatic acinar cells. Ths histometrical analysis revealed that these trophic effects of tetragastrin were produced in varying degrees in different sites.

Influence of carotid and aortic baroreceptors on neurosecretory neurons in supraoptic nuclei

(1) The effects of arterial baroreceptor stimulation on the activity of 'identified' neurosecretory cells in supraoptic nuclei (SON) of the hypothalamus were investigated in anesthetized cats. (2) Stimulation of baroreceptors by distension of an 'isolated' carotid sinus greatly inhibited SON activity. A linear relationship was found to exist between stimulus intensity (an increase in the sinus pressure) and the degree of inhibition of SON neuron activity. This inhibitory effect was abolished by section of the sinus nerve. (3) The inhibitory effect of baroreceptors on SON neuron activity was most pronounced in the first 5 sec during stimulation, and the effect became less when the stimulus lasted for a long period. At the end of stimulation there was a transient reversal of the response. (4) The excitation of aortic baroreceptors by occluding descending aorta strongly inhibited SON neuron activity. (5) Occlusion of carotid arteries augmented the SON neuron activity. Electrical stimulation of the sinus nerve caused an excitation or an inhibition of SON neurons, depending on the stimulus intensities. Apparently these stimuli produced different degrees of excitation in baro- and chemoreceptors. (6) Combination of chemo- and baroreceptor stimulations revealed that the excitatory effect exerted by chemoreceptor stimulation on SON neurons was reversed or blocked by baroreceptor activation, indicating the powerful inhibitory influence of baroreceptors.

[Studies of intrarenal distribution by macroautoradiogram and tissue distribution of 99mTc-gluconate (author's transl)]

1) The experimental studies have demonstrated that 99mTc-gluconate reaches a high concentration in the kidneys within 1-2 hours after injection and its concentration in organs adjacent to the kidney is low. 2) The initial images of serial macroautoradiograms visualized the inner medulla as well as the cortex and outex medulla, whereas the delayed images revealed only the outer cortex and outer stripes in the outer medulla. These findings suggest that this renal agent consists of two components and the delayed component deposits in the convoluted and straight segments of proximal tuble. 3) This renal agent visualizes the calyceal system and excretory pathways in the initial study and the renal morphology in the delayed study. Therefore, using this renal agent, it may be possible to evaluate a variety of renal diseases, including obstructive uropathy, space-occupying lesions, congenital deformities, etc,.