Electroejaculation of the paraplegic male followed by pregnancy.

A method is described for the production of an ejaculate the paraplegic male by electrical stimulation from a probe placed in the rectum. A case is reported in which an ejaculate produced by this method was used to inseminate the wife of a paraplegic patient. Pregnancy resulted, but the infant died. Post-mortem examination revealed the presence of transposition of the great vessels.


Effects of radial artery cannulation.

A prospective study has been carried out in 40 patients of the effects of radial artery cannulation for monitoring purposes. A Doppler flow meter was used to secure objective evidence of the incidence of thrombosis in the cannulated radial artery. Twenty-two of the 41 arteries cannulated were shown to have undergone thrombosis, and the haemodynamic defect associated with the arterial block persisted in all but two until the time of the patient's discharge from hospital. Thirteen of the 20 hands in which a persistent block was demonstrated developed features of mild ischaemia. In four instances, these were transient, and disappeared within a few days. In the remaining nine hands, however, the features persisted to the time of the patient's discharge from hospital at an average of three weeks from the date of cannulation. The mean cannulation time was 45 hours. Radial artery cannulation carries a definite morbidity, and should not be used unless there is no other reasonable way of obtaining vital information for the management of a critically ill patient.


Intake of selected nutrients compared with socioeconomic status in young women.

In this survey the aim was to investigate the relationship between the socioeconomic status of young women of child bearing age and their daily intake of calcium and other selected nutrients. Although no significant relationship was found there were other findings of nutritional interest. Further support is given to the theory that young women are a vulnerable group with respect to nutrition.


Living and working in the United States of America. Some notes for the Australian graduate.

Medical licensing in the United State of America is dependent on examination in addition to education and training. Licenses are granted by each State, and each State has individual requirements. These requirements may include the Educational Council for Foreign Medical Graduates (ECFMG) certification, internship, visa status and the foreign licensing examination(FLEX) certificate. These factors are discussed in some detail. Temporary licensure for the physician who works in a training institution is also discussed. Ecomic pressures may force the physician on an Australian stipend to consider working outside his fellowhip or residency. Licensing for the foreign medical graduate who intends working in the United States is complex, and specific questioning of a potential employer regarding licensing is very important.


Patterns of tobacco smoking in Australia.

A large representative sample of Australians aged 14 years or more was interviewed about smoking. Forty-one per cent of the males and 29% of the females aged 16 years and over currently smoked cigarettes. Smoking rates for both sexes were highest in the 20 to 24 years age group. People in metropolitan areas smoked more than those in rural areas. There was a clear excess of smoking among British immigrants. Higher socioeconomic level was associated with lower smoking rates, with higher ex-smoking rates and with more frequent choice of low-tar brands. Low-tar cigarrettes were used more where health education had emphasized the importance of tar content. Choice of brands among young smokers appeared related to the advertising strategies employed by cigarette companies. The majority of ex-smokers over 60 years of age had given up more than five years previously. Although comparison with earlier surveys of smoking habits is difficult, the results suggested a decrease in cigarette smoking among males and a slight increase among females.


Attitudes and smoking habits of Australian doctors.

In a national survey of 1,276 Australian doctors, information was obtained about their present smoking havits, any changes in their smoking habits, their opinions of the health risks associated with smoking, and the advice they gave to their patients about smoking. The results indicated that only 14% of doctors currently smoked cigarettes, and that, of all the doctors who were now ex-smokers, 72% had given up smoking more than five years before-most of them for health reasons. Most exressed a strong belief that smoking and ill health were associated and 63% encouraged their patients to give up smoking whenever possible.


Enteric-coated L-dopa (prodopa). A new approach to L-dopa therapy in Parkinson's disease.

Seventeen patients treated for a mean period of 9-4 months with an enteric-coated form of L-dopa (Prodopa), obtained the usual spectrum of benefit as from conventional L-dopa. There was a significant dose-sparing effect with the use of the enteric-coated prepartion of the order of 40% to 50%, whilst reducing gastrointestinal side effects to a minimum, at the same time as achieving optimal clinicl benefit. Enteric-coated L-dopa appears to be a useful and welcome addition to the therapeutic armamentarium for Parkinson's disease.


Fascioliasis causing hepatitis in two eaters of water cress.

Fasciola hepatica infection of the liver in a husband and wife occurred after they had eaten water cress exposed to pollution by cattle. Diagnosis was a problem. Both responded to treatment with chloroquine and emetine. The epidemilology and pathology of infection of the liver by Fasciola hepatica are described. The danger of eating water cress is emphasized for this momentary delight may lead to a chronic debilitating illness.


The tratment of non-specific urethritis.

The treatment of non-specific urethritis should aim at curing the individual, preventing reinfection and eliminating the pool of infection from the community. Tetracyclines, the rubber condom and sound advice are the basis of treatment. Many patients have symptoms that arise from anxiety and guilt rather than from infection, and this possibility calls for special consideration. It is emphasized that non-specific urethritis can be eliminated from our community by existing means. The favourable outlook merits an active and positive approach to treatment.


Multidisciplinary health teams.

The medical profession needs to learn team skills and review its managerial functions in anticipation of increasing involvement with other health professionals in a team setting. Educatinal techniques for acquiring these skills are already available or are being developed for other organizations. Review of the traditional medical hierarchy and its legal implications, architecture of health institutions, medical records systems, and the selection of medical students are other areas for specific attention.


[A contribution on diagnostic and therapy of myxoedema coma (author's transl)].

With special reference to diagnostic and therapeutic problems, a case of myxoedema coma with secondary hyperaldosteronism and raised LDH-concentration is described. The significance of different states of consciousness due to this endocrine disorder is pointed out with respect to the differential diagnosis and particularly to the clinical symptoms. In addition, experience with an intravenously administrable triiodothyronine compound is described and the different dosages previously mentioned in the leterature are discussed. The long interval of 5 weeks from the beginning of the therapy until the remission of the omatous state was surprising.


[Ergometric findings depending on the severity and localization of coronary artery disease (author's transl)].

Ergometric and coronary angiographic findings were compared in 145 patients with proximal lesions of at least 50% of major coronary arteries. 75% of the patients had had a previous myocardial infarction. The following ergometric parameters occur most frequently in 3-vessel disease. (1) coronary insufficiency persisting after myocardial infarction, (2) ST-segment depression of at least 0.2 mV, (3) maximum exercise tolerance limited to less than 75 Watts. However, these parameters cannot predict 3-vessel disease with absolute certainty, nor can they exclude a single vessel disease. 3-vessel disease is not likely, if there is a maximum heart rate of 150 beats per minute or more. There were only slight differences between patients with 1-vessel disease and patients with 2-vessel disease. Patients who were limited at the 50 Watts level were found to have significant LAD disease, either alone or in combination with other vessels, with the exception of one patient.


[Hemodynamics at rest and during exercise depending on severity and localization of coronary artery disease (author's transl)].

Left ventricular filling pressure and cardiac output (C.O.) were studied at rest and during exercise in 145 patients with severe coronary artery disease, i.e. narrowing of at least one major coronary artery of greater than or equal to 50%. 95% of these patients had had a previous myocardial infarction. The most important findings are as follows: (1) Inappropriate C.O. at rest and during exercise indicates multiple vessel disease in most cases. (2) Marked increase of filling pressure during exercise indicates multiple vessel disease in most cases. (3) PCP during exercise is higher in patients with LAD disease (isolated or in combination with additional lesions), than in patients with RCA and/or left CX involvement.


[Electrocardiographic changes in electrolyte inbalance. Part 2: Alterations in serum calcium (author's transl)].

74 patients (hypocalcemia: 41 patients, hypercalcemia 13 patients, 20 patients as control) without heart disease were examined. A prolongation of the relative QT-interval was found in 90% and a flat or inverted T-wave in 25% of the patients with hypocalcemia. In 77% of the patients with hypercalcemia the QT-interval was shortened. A good, clinically useful correlation between the QT-interval and the serumcalcium-concentration could be established in patients with hypo- and hyper-calcemia.


[Orthostatic syndrome in old age. Frequency and therapy (author's transl)].

Largely confirmed Caird's figures. Using Schellong's test we recorded systolic pressure falls of 20 mm Hg and more in 25% of 160 residents in an old people's home in the age range 59-88 years. These cases of circulatory dysregulation were all manifestations of the hypodynamic form of the orthostatic syndrome. This means that only systolic blood pressure fell, diastolic pressure as well as heart rate being largely unaffected. The phenomenon appears to be due to age-related deterioration in circulatory regulation; at least no evidence has been found to suggest that it has a specific aetiology. In a double-blind cross-over study the effect of dihydroergotamine (DHE) was compared to placebo in 40 patients. Half the patients were given 2 mg DHE three times daily for 14 days and the other half placebo tablets; following one week's wash-out, the treatments were then reversed for a further 2-week period. Schellong's test (measurement of blood pressure and pulse after 10 minutes in the supine position and then after 1, 2, 5 and 10 minutes standing) was performed at the beginning and end of each treatment period. The average falls in upright systolic pressure for all 40 patients were as follows: before treatment 20 mm Hg, end of placebo periods 19 mm Hg, end of DHE periods 7 mm Hg. The differences between the values recorded after treatment with DHE and the other 2 values are statistically significant.


[Alterations in blood- and plasma-viscosity of patients with risk-factors (author's transl)].

In a series of tests, performed on patients with the risk-factors smoker and adiposity, a comparison with normal persons revealed a statistically significant hyperviscosity in plasma and whole blood for smokers and overweight patients. When both risk-factors occurred simultaneously, the blood- and plasma-viscosity displayed a distinctly additive increase. Furthermore, female patients taking contraceptives showed a significantly increased plasma- and blood-viscosity when comparing them with a group of normal persons. In a group of pregnant women, hyperviscosity could not be secured statistically.


[Serial puncture of lymphnodes. Simultaneous occurrence of chronic lymphatic leukemia and malignant lymphoma with cytologic picture of Hodgkin's disease (author's transl)].

A case of the rare coexistence of chronic lymphatic leukemia and a malignant lymphoma with cytological picture resembling that of Hodgkin's disease is described. The simultaneous occurrence makes the transition from one disease to the other rather doubtful. The author's conclusion is therefore, that it is a coinciding, simultaneous incidence of two different malignant diseases of the lymphatic system. The reader's attention is also drawn to the valuable diagnostic method of serial puncture of lymphnodes.


[Forearm and digital blood flow after arteriovenous anastomosis (author's transl)].

Forearm and digital blood flow were measured by venous occlusion plethysmography in 7 patients with terminal renal failure before and 8 days after surgically created arterio-venous end-to-end fistula similar to the method of Brescia and Cimino. The forearm blood flow rose significantly from 3.30 +/- 1.75 to 6.98 +/- 4.74 ml/min - 100 ml. Total forearm blood flow increased from 32.9 +/- 16.8 ml/min to 69.8 +/- 45.8 ml/min. Digital blood flow was not significantly altered. The relatively low fistula flow was due to the early postoperative measurement since it increased later.


[Angina abdominalis: Clinical findings and therapy (author's transl)].

Angiographic and clinical findings of angina abdominalis are demonstrated by the clinical course of four patients. Two of them suffered from athero-sclerotic stenosis and the remaining two from compression of the coeliac trunc respectively the upper mesenteric artery by fibrotic strings. One patient was treated by an interposition of a saphenous vein graft another one by tissue decompression. Two patients were not operated upon, because one of them had sufficient collateral circulation on angiography, and the other denied an operation, he died one year after diagnosis because of an occlusion of the coeliac trunc and the upper mesenteric artery with following gangrene of the small and large intestine. Danger of complete intestinal necrosis following arterial vessel occlusion as well as reconstructive operative procedures on arterial occlusion should be considered.


Host factor for coliphage Qbeta RNA replication is present in Pseudomonas putida.

Host Factor (HF)1, is a 12000 molecular weight polypeptide that is found in uninfected Escherichia coli and is required as a hexamer along with Qbeta replicase for in vitro replication of Qbeta phage RNA. It has recently been found to be associated with ribosomes and to bind tightly to poly(A). We report here the identification and purification of HF from Pseudomonas putida. HF can be detected in crude extracts by both functional activity in the Qbeta RNA replication assay and by immunodiffusion with antibody made against E. coli HF. HF from E. coli and P. putida chromatograph similarly on DEAE-cellulose and phosphocellulose. They have similar but not identical molecular weights as judged by SES-polyacrylamide gel electrophoresis. Like E. coli HF, P. putida HF was found to be associated with ribosomes and to bind tightly to poly(A). Furthermore, the pure protein from P. putida has full funcitonal activity in the in vitro Qbeta RNA replication assay. The findings that HF has been conserved during evolution, is associated with ribosomes, and binds poly(A), suggest that HF may be an important translational element in uninfected cells and that its role involves an interaction with RNA.


[Intranuclear particles in a patient with chronic aggressive hepatitis treated by immunosuppression].

After an acute HbsAg-positive transfusion hepatitis the patient--a 40 years old women--remained seropositive. Later a chronic aggressive hepatitis have developed, which could be evidenced by histological findings. On the electron microphage in the nucleus of liver cells ring-shaped particules 20--25 nm in diameter were revealed. They consisted of granula 2--3 nm in diameter. These particules are considered to represent so called virus-nuclei (core of the virus B of hepatitis) and to play a pathogenic role. These particules are commonly present and easily found. The great number of them--according to author's opinion--can be explained by the effect of immunosuppressive therapy.


[Peculiar changes in the mitochondrial structure of human glandular cells of adenocarcinoma of the uterine mucosa].

Author observed peculiar alterations in the structure of mitochondria of glandular cells of adenocarcinoma of the endometrium. Majority of the mitochondria reveal some lesions, but at the same time in some of them hyperplasia of the crystae and membranes could be observed. In another group of mitochondria rearrangment of the intracrystal fissures leads to the formation of a "honey-comb" structure. What factors lay in the base of these alterations are as yet unknown. To clear they function further investigations are needed.


[Ultrastructure of human yolk sac].

The yolk-sac of a 15 mm and 20 mm long human embryo was investigated by the aid of electron microscope. Ultrastructure of the yolk-sac and that of the precursors of haemopoietic cells is described. The latter have been found to have a close correlation with endodermal cells.


[Permeability of post-ischemic aortic wall in rats].

Examinations were carried out in order to reveal details of process of the permeability damage, its degrea and fate of the plasma-substances getting into the vessel all. Abdominal aorta has been cross-clapped for one hour by the aid of a double ligature. In a recirculatory period from 1 hour to 10 days material serving for labeling of the plasma has been determined in the vessel using histochemical and microchemical methods. Colloidal iron was administered to animals one hour before removing the aorta. The highest quantity of colloidal iron in the aortic wall could be revealed after 24--48 hours of recirculation. By the 10th day the vessel wall contained physiological iron quantity. Colloidal iron administered on the second day of recirculation--when damage to permeability is most marked--in the early phase could be seen in the whole aortic wall. By the 7th day it could be detected only in the outer part of media and in the adventitia. Endothelium inhibits the flow of plasma-substances into the vessel wall, when they got through it, only elastic lamina form a temporary mechanical obstacle for transfusion.


[Effect of transient hypoxia on the permeability of rat aorta. Electron microscopic study].

Infrarenal part of the abdominal aorta in rats was closed out from the circulation by the aid of a doubled ligature. Changes of the permeability at different intervals after recirculation were investigated using colloidal iron as a labelling substance. The latter in an hour after recirculation could already be detected in the interendothelial junction and in the subendothelial space. The lesion of the permeability was most striking on the second day, and on the tenth day no more lesion could be observed. Increase of the permeability of the endothelium was paralelly followed by an inhibition of the media, which leads to significant ultrastructural changes.


[Fluorescence study of X and Y chromatin in frozen sections].

Chinacrine fluorescence of the Y chromatin in histological sections is a useful tool for determination of nuclear sex. Nuclei of fibroblasts and smooth muscle cells seems to be most suitable for this investigation. Tissue specimens should be fixed for 5 minutes in hot formalin. Frequency of the Y chromatin in frozen sections of male origin was found to be 38--70 per cent, in paraffin embedded sections 28--44 per cent. It seems likely, that paraffin decreases chinacrin binding capacity of the Y chromatin. Frequency of the Barr-body in tissue specimens of female origin was found to be similar both in frozen and paraffin embedded sections. For the investigation of X and Y chromatin in tissue sections the technique of frozen sections should be used.


[Current problems of the differential diagnosis between live birth and stillbirth].

Data of the literature concerning of the livebirth and still-birth are reviewed. Pulmonal fluid formation in human lately has been prooved. At intrauterine asphyxia CO2 is deliberated causing distension of the alveoli and respiratory bronchioli. These changes have to be taken into consideration at evaluation of histological findings in the lung of newborn. Results of the newer observations can not yet be used for the differential diagnosis of live-birth and still-birth, since the validity of them is not yet prooved by practice.


[Scanning electron microscopic study of human bronchial mucosa under normal and pathological conditions].

Scanning electronmicroscopic picture of the normal human bronchial mucosa and alterations of it in chronic bronchitis are described. According to the author's findings in chronic bronchitis the regular arrangement of cilia disappears, the number of them decreases and they become shortened with a club-like formation on the end. Focal destruction of the cilia can also be seen. In the epithelium of the mucosa number of the cells without cilia increases. This is a consequence of the destruction of the cilia on one hand, and increase of the number of mucus secreting goblet cells on the other. Alterations of the bronchial mucosa in chronic bronchitis revealed by scanning electron microscopy may play an important part in the pathogenesis and persistence of chronic bronchitis of different origine.


[Experimental study of the hepatotoxic effect of toluol. II. Electron microscopic and electron histochemical studies].

The hepatotoxic effect of the analitically pure toluol and a toluol neing used in the Chemical Factory "Tiszai" was investigated. Single toxic and various subtoxic doses of toluol were administered intraperitoneally and subeutaneously to male rats of CFY. The liver of the animals was investigated by the aid of electron microscope. It was established that large doses of toluol lead to the decrease of glycogen content and increase of the number of mitochondria in the hepatic cells. Numerous dividing mitochondria were also observed, with a great deal of matrix graules. Electronhistochemical demonstration of the activity of succinic-dehydrogenase does not reveal any difference between the liver of experimental and control animals. As an effect of small doses of toluol degenerative changes-enlargement of the cysternae of the endoplasmatic reticulum, separation of ribosomes, increase of the number of autophag-vacuola-could be seen. The degenerative changes occurred only in a part of the hepatic cells which appeared to be distributed randomly in the liver lobules. Authors assume that lesions revealed are of reversible type.


[Scanning (SEM) and transmission (TEM) electron microscopic studies on post-ischemic endothelial lesions following recirculation].

The vessel wall endothelial surface was studied after recirculation for various periods following a transitory hypoxia. The acute changes consisted of a partial or total destruction of the endothelium in certain areas. Later on the regeneration (division and process formation) of endothelial cells took place to cover the damage areas. These events were demonstrated by both transmission and scanning electron microscopy. In case of severe vessel damaged also the subendothelial matrix, the collagen- and elastic fibres as well as the stomata were set free. Blood cells anchored to these areas were also overgrown later by endothelium. The restitution was practically complete in 10 days when only some small endothelial processes had shown the previous regenerative activity. In spite of the extensive damages to the endothelium no occluding thrombus-formation was seen. The phagocytes functioned only in removing debris and the thrombocytes in facilitating endothelial overgroth.


[Functional morphology of the odontoblast cell].

The most highly differentiated cells of the dental pulp - odontoblasts, taken from normal and carious teeth of persons of various age groups were investigated by the aid of electron microscope. Aim of the investigation to determine the relationship between the fine structure and function. Ultrastructural investigation shows that odontoblasts beside the 1) production of dentin take part in the 2) transport of substances and 3) tissue fluids. In the beginning and continuous promoting of the 4) crystallization of the enamel layers odontoblasts play a role of a border-surface which provide a necessary concentration 5) On the end part of nerve fibres they may function as supporting cells (replacement of the Schwann-cells). 6) When pathological processes present (caries) the ultrastructure shows cell-activity of defence type.


[Morphological and toxicological studies of experimental diquat poisoning].

Lesions caused by a single subtoxic dosis of diquat were studied in rats. After the administration of diquat on the first day it was revealed in highest concentration in the lung, but in two weeks no traces of the drug could be demonstrated. On the first and third day activity of peroxidase in the liver and the number of peroxisomes as well significantly increases. On the first day after the administration of diquat in the lung damage to the surfactanct and increase of the capillary permeability was observed. Later degenerative changes of the pneumocytes I and II type, focal haemorrhagic edema and presence of alveolar macrophages can be revealed. In two and in four weeks a slight pulmonary fibrosis remains to show the damage to the lung. In kidney tubular lesions of toxic origin, in the phase of the regeneration increase of the number of lyosomes could be revealed. On the basis of this study and the data of other authors the possible mechanism of the intoxication with diquat is discussed.


[Capillary fluorescence in brain smears].

A histochemical technique for the detection of catecholamines accumulated by endothelial cells of the capillaries of rat brain after L-DOPA treatment is reported. The main point is to obtain smaers from the cut surface of the brain without damage to the capillaries. Catecholamine raction in the latter, then should be examined by the Fakk's technique. The method described is very quick and gives an exact localization of catecholamines accumulated in the wall of the cerebral cpaillaries. It is a useful tool for the investigation of the monoaminoerg brain-blood barriere.


[Congenital neck teratoma].

A case of the congenital teratoma of the neck, detected at the autopsy of a stillborn baby is reported. In the Hungarian literature similar case has not yet been reported. Morphology of the tumour questions of its biological nature are discussed. Clinical symptoms are also rewieved. Surgical removal of the teratoma of the neck gives very good results.


Mutagenesis in cultured human diploid cells. III. Induction of 8-azaguanine-resistant mutations by furylfuramide.

Trans-2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide (furylfuramide: FF or AF2) was tested for ability to induce 8-azaguanine (8AG) resistant mutations in cultured human diploid cells. FF had a relatively severe cytotoxic effect on the cells. From the concentration-survival curve, the D0 value for 2-h treatment with FF was estimated to be 11 mug/ml. When cells were treated with FF at various concentrations for 2 h, cultured in normal medium for 48 h, and then selected in medium containing 8AG at 30 mug/ml, the induced mutation frequency increased gradually with increase in concentration of FF. When cells were treated with FF at 10 mug/ml for 2 h, cultured in normal medium for various periods of mutation expression time, and selected with 8AG at 30 mug/ml, the highest induced mutation frequency was obtained with 48 h of mutation expression time. Microscopic examination of the numbers of cells in colonies indicated that the total number of cells increased by half during this mutation expression time of 48 h.


Mutagenesis in cultured human diploid cells. IV. Induction of 8-azaguanine resistant mutations by phloxine, a mutagenic red dye.

Disodium 9-(3',4',5',6'-tetrachloro-o-carboxyphenyl)-6-hydroxy-2,4,5,7-tetrabromo-3-isoxanthone (phloxine), a red dye used as a food additive, was tested for its activity to induce 8-azaguanine (8AG) resistant mutations in cultured human embryonic cells. Phloxine had a severe cytotoxic effect on the cells at concentrations of 1 to 10 mug/ml. At concentrations of more than 30 mug/ml of phloxine no further decrease in cell survival was found. This cytotoxic effect of phloxine was not dependent on the duration of treatment. After treatment with phloxine for 2 h division of cells in normal medium was inhibited for 120 h. When cells were treated with phloxine at various concentrations for 2 h, cultured in normal medium for 48 h, and then selected with 30 mug/ml of 8AG, an increase in the induced mutation frequency was found. This increase in mutation frequency was dependent on the concentration of phloxine used as a mutagen and treatment with 100 mug/ml of phloxine increased the frequency to six times that in untreated cultures.


Mutagenicity of dimethylnitrosamine to mammalian cells as determined by the use of mouse liver microsomes.

The mutagenicity of dimethylnitrosamine (DMN) to mammalian cells was investigated using a metabolic activation system. Mutation from 8-azaguanine (8AG) sensitivity to resistance in FM3A cells, a cell line derived from C3H mouse mammary carcinoma, was found only in the presence of dimethylnitrosamine, mouse liver microsomes and cofactors. The different inducibility of the mutation was shown by the use of liver microsomes from different strains of mouse.


The effect of methylated oxypurines on the size of newly-synthesized DNA and on the production of chromosome aberrations after UV irradiation in Chinese hamster cells.

A comparison has been made, in Chinese hamster cells, of the ability of various methylated oxypurines to inhibit post-replication repair of DNA after UV irradiation and to potentiate UV-induced chromosome aberrations. DNA synthesized in UV-irradiated cells contains gaps, which are subsequently sealed by a process termed post-replication repair. In rodent cells this process is inhibited by caffeine and its analogues. This has been quantitated by measuring the molecular weight of the DNA synthesized in UV-irradiated cells during a 4-h pulse-labelling period in the presence or absence of inhibitors--the lower molecular weight the greater the inhibition. Eight methylated oxypurines were tested; caffeine and chlorocaffeine were always the most potent inhibitors, tetramethyluric acid was inactive, and the other five derivatives (methoxycaffeine, ethoxycaffeine, paraxanthine, theobromine and theophylline) had intermediate effects. Measurements of the potentiation of UV-induced chromosome aberrations showed that treatments with caffeine or chlorocaffeine again had the greatest effects, tetramethyluric acid and also theophylline had no potentiating activity, and methoxycaffeine was intermediate. This correlation between effects at the molecular and cytological levels is consistent with the hypothesis that the inhibition of post-replication repair by methylated oxypurines gives rise to the increased production of chromosome aberrations.


Absence of acrosome: an efficient tool in mammalian mutation research.

Spermatozoa without acrosomes ("acrosomeless") have been qualitatively and quantitatively analysed in several strains of mouse. The frequency of these abnormal cells was fairly constant within the same strain, but increased with age, consanguinity and after treatment of mice at pre-meiotic stages with alkylating agents. From this behaviour, it is thought that these abnormal cells are true mutants which could be used in mutation research.


Sister chromatid exchanges--a sensitive assay of agents damaging human chromosomes.

Sister chromatid exchange frequencies in human lymphocyte chromosomes are greatly increased by alkylating agents, but ionizing radiation has little if any such effect. Scoring these exchanges may provide a useful technique for exploring the mechanisms of chromosome breakage and repair.


Some properties of the protease from Aspergillus terricola.

The protease from Aspergillus terricola (terrilytin) was isolated and purified by the ion exchange method and by gel chromatography. The data on its molecular weight, isoelectric point, N-terminal amino acids were described. The protease included polysaccharide which stabilized the enzyme activity under the storage and lyophylization. Polysaccharides isolated from different fungi and yeasts were found to stabilize and activate terrilytin rising the affinity of enzyme to substrate. Terrilytin was revealed to exhibit the thrombolytic effect and expressive affinity to the fibrin in comparison with other substrates of high and low molecular weight. The enzyme showed the antigenic activity. From immune rabbit sera 7S gamma-globulins inhibiting proteolysis of caseine and 19S gamma-globulins activating the proteolysis of fibrin and fibrinogen by terrilytin were isolated by gel chromatography.


The atmospheric fungal flora of the Athens metropolitan area.

In the research programme of the Department of Microbiology of the Athens University the nature of the mycological flora of the Athenian air was studied. The research took place during the calendar year 1971. The open air was sampled twice weekly from two observation stations. The open plate technique was used, Petri dishes containing Sabourand's agar being exposed for 15 minutes. A total of 180 plates were exposed, and 1714 fungal colonies were isolated; these were subcultured and identified as follows: Alternaria alternata, Alternaria SP. (representing a common transitional form towards the genus Ulocladium), Aspergillus niger, Aspergillus oryzae, Aspergillus terreus, Chrysosporium SP., Candida SP., Geotrichum SP., Mucor SP., Penicillium patulum, Pencillium SP., Rhodotorula rubra, Saccharomyces SP., Streptomyces SP., Trichsporon SP. AND Ulocladium oudemansii. The genus Alternaria was most frequently isolated, representing 38% of the total colonies. Other genera occured in the following proportions: Penicillium 27%, Aspergillus 13%, Candida 9%, Rhodotorula 6% and Mucor 1%. Species of other genera accounted for 6% of colonies, including 4% which were classified as Mycelia Sterilia. It is of considerable interest that the most frequently isolated species are considered as allergens. An appropriate line of further investigations would appear to be the preparation of antigens, application of skin tests and classification of allergic reactions after relating laboratory findings to clinical observations.


Relationship between the metereological conditions and the air-borne fungal flora of the Athens metropolitan area.

The statistical relationship between the metereological conditions and the population of the air-borne fungi of the Athens metropolitan area were considered. It was found that during autumn and winter the number of suspended microfungi was more than double that which occurred during spring and summer. The fungal content appeared to be correlated positively with humidity and negatively with terperature, although during the analysis of the six predominant genera some exceptions were found to the general form of the results.


[Growth and sporulation of 6 species of Entomophthorales. II. Effect of various nitrogen sources].

Growth and sporulation of Entomophthora near obscura, E. destruens, E. near thaxteriana, E. virulenta, Basidiobolus ranarum and Conidiobolus osmodes were studied in solid synthetic media containing various nitrogen sources at 0,33 g N/liter. Thirty two nitrogen sources representing nitrates, ammonium salts, amino acids and protein hydrolysates were tested. E. near obscura did not grow on any medium. Protein hydrolysates, ammonium salts and ten of the sixteen amino acids tested were the best nitrogen sources for growth and resting spores production of the five other species.


[Common presence on strawberries of ascospores of Byssochlamys nivea capable of producing patulin].

Tha auteurs have obtained a strain of Byssochlamys nivea from heat processed strawberries. The mold grown on synthetic media shows antibiotic properties. The metabolite responsible is patulin which has been purified and characterized. Several strains of B. nivea produced this mycotoxin. Patulin seems to be stable in strawberries juice.


Observations of Microsporium canis with cryoscanning and scanning electron microscopy.

The observations of Microsporum canis with cryoscanning and scanning electron microscopy without fixation and dehydration were reported. In the former an almost native state was observed through showing some fuzzy outlines due to frost; in the latter it was shown that marked shrinkage and distortion had occured. There were many granules on the surface of the macroconidia though their function is uncertain.


Zearalenol and 8'-hydroxyzearalenone from Fusarium roseum.

Fusarium roseum f. sp. gibbosum and F. roseum f. sp. semitectum were isolated from blighted culms of grain sorghum. Zearalenol and 8'-hydroxyzearalenone were produced by these isolates cultured on grain sorghum or cracked yellow field corn. Zearalenol is reported to have uterotropic activity and might be an important mycotoxin in sorghum.


A critical study of the taxonomic value of some tests of assimilation used for the classification of the sporogenous yeasts.

Six texts of assimilation used in the taxonomy of yeasts, (lactose, maltose, cellobiose, trehalose, melibiose, sucrose) have been critically tested by the examination of intracellular enzymic systems. The results obtained among the sporogenous species of Saccharomyces, Kluyveromyces, Pichia, Hansenula, Debaryomyces indicate that cellobiose, lactose, maltose and trehalose tests no longer supply an important value for the speciation, because the number of cryptical osidases is so high.


Identification of two related pentapeptides from the brain with potent opiate agonist activity.

Enkephalin, a natural ligand for opiate receptors is composed of the pentapepides H-Tyr-Gly-Gly-Phe-Met-OH and H-Tyr-Gly-Gly-Phe-Leu-OH. The evidence is based on the determination of the amino acid sequence of natural enkephalin by the dansyl-Edman procedure and by mass spectrometry followed by synthesis and comparison of the natural and synthetic peptides.


Conservation of cytoplasmic poly (A)-containing RNA in mouse and rat.

By comparing the melting temperature of DNA-DNA duplexes between related species, it is shown that total single-copy DNA evolves at a faster rate that DNA which is transcribed into poly (A)-containing RNA. Such a comparison suggests that at least 70% of rat single-copy DNA does not code for protein.


Strategy and tactics of chemotherapeutic drug development.

Strategic approaches to generating chemotherapeutically active lead compounds are either empirical as in traditional synthetic programs or in the search for antibiotics; they are semiempirical as concerns the design of antimetabolites and more rational for the design of DNA-complexing drugs. The tactics of exploitation of active lead compounds in chemotherapeutic drug development involve molecular modification. This aims at either substances with greater activity and/or substances with improved pharmacokinetic parameters. From quantitative structure-activity relationships one might extrapolate to members of a chemical series with improved pharmacokinetic properties. Scientific advances render chemotherapy research more predictive and, hence, less empirical.


A procedure to produce gnotobiotic calves by cesarean section.

An effective and economical method was developed for procuring and rearing calves in gnotobiotic conditions. To evaluate apparatuses and surgical techniques, three calves, 1 to 3, welf 1 was weak and pale at delivery and died within 5 hours after delivery. Calf 2 was delivered alive, but died from a human error at 3 days of age. It was free from demonstrable bacteria and fungi at that time. Calf 3 was also successfully delivered and raised. It was killed at 10 days of age, since fungi were isolated from the feces and waste materials from it.


Five new species of Culicoides (Diptera: Ceratopogonidae) of the Nansei Islands.

Five new species of Culicoides of the Nansei Islands are described: C. sasai sp.n. from Amami-oshima Is., C. toshiokai sp.n. from Ishigaki Is., C. iriomotensis sp.n. from Iriomote Is., C. flavipunctatus sp.n. from Yonaguni Is., and C. yaeyamaensis sp.n. from the latter three islands. C. toshiokai sp.n. and C. iriomotensis sp.n. are tree-hole breeders, such as C. dendrophilus Amosova, which is common in similar habitats extending from Okinawa to Honshu.


The different fatty acids composition of lecithins in the sarcoplasmic reticulum vesicles and the membranes of adrenal chromaffin granules.

Calcium transporting membranes of sarcoplasmic reticulum (SR) and amine transporting membranes of chromaffin granules (AG) isolated from different animal species (ox, rabbit and rat) show similar values for their phospholipid phases (0.5 mumole phospholipids/mg protein). The AG-membranes, however, contain higher lysolecithin (LPC) (10 11%) than the SR-membranes (2-6%). In both types of membrane a characteristic distribution of fatty acids was found in the phosphatidylcholine (PC) fraction. In SR-membranes 18-carbon fatty acids are present in increasing order of unsaturation (18:0 less than 18:1 less than 18:2) and in AG-membranes in decreasing order (18:0 greater than 18:1 greater than 18:2). The fatty acid composition of PCs specific of each membrane seems to be dependent on the presence of different endogenous lysolecithins and suggest a fatty acid turnover in both positions of the PC by the de- and re-acylation cycle. The importance in membranes function with regard to the Ca2+ transport of SR and the amine transport of AG membranes as related to the typical lipid phase is discussed.


The acyltransferase activity of adrenal medulla and sacroplasmic reticulum of skeletal muscles.

The presence of acyl-CoA-lysolecithin-acyltransferase was studied in ox adrenal medulla fractionated by sucrose gradient centrifugation. The highest activity of this enzyme is localized in the microsomes and not in the membranes of chromaffin granules. Estimation of acyltransferase activity in fragments of sarcoplasmic reticulum (SR) from rabbit skeletal muscles before and after sucrose gradient centrifugation shows that in these membranes acyltransferase is a membrane bound enzyme. Both enzyme preparations transfer 18-carbon fatty acids in increasing order of unsaturation to 1-acyl-sn-glycer-3-phosphorylcholine (1-acyl-GPC) (18:0 less than 18:1 less than 18:2) and in decreasing order to 2-acyl-sn-glycero-3-phosphorylcholine (2-acyl-GPC) (18:0 greater than 18:1 greater than 18:2). For the acyltransferase present in ox adrenal medulla and fragments of sarcoplasmic reticulum, 1-acyl-sn-glycero-3-phosphorylethanolamine (1-acyl-GPE) is not a good acyl acceptor. The importance of acyltransferase in the de- and re-acylation cycle for the neogenesis of membranes-specific lecithin is discussed.


Optical isomers of verapamil on canine heart. Prevention of ventricular fibrillation induced by coronary artery occlusion, impaired atrioventricular conductance and negative inotropic and chronotropic effects.

Effects of optical isomers of verapamil on the canine heart were measured with a pressure catheter in the left ventricle and with the electrocardiogram. 1. Both isomers of verapamil caused impaired atrioventricular conduction. slowed the rate of the sinus pacemaker and depressed the contractile state of the myocardium. (-)-Verapamil was consistently more potent than (+)-verapamil in producing these effects. (-)/(+) potency ratios of 10 and 3 were estimated for atrioventricular blockade and for the negative chronotropic effect, respectively. 2. Negative inotropic effects of 0.06-2.0 mg/kg of (+)-verapamil were determined on hearts paced at constant rate. A similar dose-response relationship could not be established with (-)-verapamil because at concentration higher than 0.06 mg/kg the hearts did not follow the supraventricular driving stimulus. With doses of (-)- and (+)-verapamil which produced the same slowing of the sinus pacemaker rate in spontaneously beating hearts, (-)-verapamil caused greater negative inotropic effects than (+)-verapamil. 3. The following doses of isomers of verapamil reduced the incidence of ventricular fibrillation induced by coronary artery ligation: 0.2 mg/kg (-)-verapamil (P less than 0.001), 0.6 mg/kg (-)-verapamil (P less than 0.001) and 0.6 mg (+)-verapamil (P less than 0.01). 4. Intravenous administration of CaCl2 to dogs treated with either isomer of verapamil restored the contractile state and reversed atrioventricular blockade to sinus rhythm. Dog ventricles under the influence of concentrations of isomers of verapamil which, with normal plasmatic Ca2+-content, prevent fibrillation, consistently fibrillated after coronary artery occlusion when high doses of CaCl2 were administered. 5. The effects of the optical isomers of verapamil may occur predominantly via a blockade of the slow inward Ca2+-current.


Species differences in plasma binding and tissue uptake of 3H-digitoxin. A comparative study in rats and mice in vivo and in vitro.

The content of cardiac glycosides in plasma and several organs of rats and mice was investigated 30 min and 12 hrs after i.p. administration of 160 mug/kg b.w. 3H-digitoxin. In rat plasma a glycoside concentration of 124.8 and 44.7 ng/ml resp. was found. The corresponding values in the liver were 834.7 and 579.7 ng/g w.w. An opposite liver/plasma distribution was obtained in mice: while in plasma 772.5 and 571.8 ng/ml were recovered, the glycoside concentration in liver was relatively small (284.8 and 235.6 ng/g w.w.). In order to find out the reason for such species differences observed in vivo, liver slices of rats and mice were incubated with 3H-digitoxin in a medium with and without various plasma proteins. The uptake of 3H-digitoxin into liver slices was drastically reduced by adding mouse plasma or albumin to the medium, while rat plasma lowered the uptake far less. These differences are well reflected by binding studies on agargel electrophoresis: only in mouse plasma a binding of 3H-digitoxin could be demonstrated. The binding rate and binding constant analyzed by equilibrium dialysis were higher in mouse than in rat plasma. It is concluded that the lower tissue accumulation in mice compared to rats must be due to the affinity of 3H-digitoxin to mouse plasma albumin. Moreover digitoxin has a higher affinity to the rat than to the mouse liver in the presence of mouse or rat plasma as well as of bovine serum albumin.


Pupillometric studies in the beagle dog.

A method of measuring pupillary diameter in the dog using a Kowa RC-2 fundus camera, to which an eyepiece graticule had been fitted, is described. Pupil diameter was measured either directly by reading off from the calibrated graticule or from photographs. The pupillary diameters of 105 (53 male, 52 female) untreated English beagles aged between 8 and 32 months were measured under light intensities of 150-200 lux and 1000-1400 lux. Mydriatic and miotic pupillary diameters were measured in 62 male and 80 female dogs. Time-effect curves were plotted for two groups of 5 beagles receiving 75 mug/kg or 175 mug/kg atropine and 100 mug/kg or 300 mug/kg propantheline intravenously. The dose-effect curve for propantheline was found to be linear. A dose of 109 (97-121) mug/kg propantheline increased pupillary diameter by 3 mm, 20 min after administration. The time- and dose-effect curves, the significant sex differences and age dependency seen in this study indicate both a high degree of accuracy and the suitability of both of these methods for use in pharmacological and toxicological studies.


[The activity of visual cortex neurons during alimentary and defensive behavior].

The reactions of the rabbit visual cortex neurons in response to conditioned light flashes were investigated during the process of repeated changes of the feeding behaviour to the avoidance one. It is demonstrated that one and the same flash evokes different responses of the same neuron while triggering different behaviour.


[Physiologic mechanisms of the constancy of color perception].

The color constancy is the ability to recognize correctly the colours of the objects under different illuminations. For this purpose the visual system must identify the character of illumination and estimate the colour of the object, using the light reflected from this object according to the spectrum of illumination. The behavioral experiments with fishes showed that they possess the colour constancy. The electrophysiological studies on colour-coding ganglion cells showed that the simplest mechanisms of estimating the colours of objects according to illumination exist at the retinal level. The presence of colour vision facilitates the recognition of the volume form of the objects. The generally accepted view on the place and role of colour vision in the general function of the visual system of animals has to be changed on the basis of these facts.


[Types of receptive field in the external geniculate body and its functional model].

The functional differences between receptive fields of types I and II of lateral geniculate nucleus were investigated in cat. Some characteristics of these fields are shown to coincide with transient (Y-type ) and sustanied (X-type) receptive fields. Receptive fields of type I possess a limited range for transmission of information on luminance, those of type II--a normal dynamic range (2 log. unit). The investigation of a dynamic functional model showed that type of the receptive field is determined by the depth of inhibition mediated through an interneuron. The depth of inhibition is larger in type I. Types I and II have different frequency characteristics. It is suggested that receptive fields of type I serve to transmit information on the shape of the image (spatial and time contrasts) and those of type II on luminance.


[Image description at the level of the external geniculate body].

The responses of the receptive fields of the cat lateral geniculate body were investigated with a different position of the light stimuli in the receptive field. The stimuli were of the cross shape. On the basis of the obtained data the relief of excitation of the overlapping receptive fields was reconstructed. It is shown that at the level of the lateral geniculate body there exist a copy of the light stimuli. The description of the image is formed as a relief of excitation which changes in time. The magnitude of the excitation depends on the contrast of the stimuli.


[Statistical characteristics of the background and evoked activity of cat superior colliculus neurons].

Background and evoked neuronal activity in the superior colliculus was studied in cats immobilized by galamine and in the encephale isole cats. Statistical parameters of the unit activity were calculated in the light and darkness and during stimulation with a moving light spot. Differentiation of background active neurons into the following four groups was suggested: the first group with a mean interval value about 300 ms, variation coefficient 1.9 and two peaks in the autocorrelation histogram, the second group with similar statistical parameters, however, differing in a presence of a correlation with saccade eye movements; the third group with a mean interval about 100 ms, variation coefficient 1.0 and an exponential distribution of intervals; the fourth group with the symmetrical type of interval histogram, a mean interval about 50 ms, variation coefficient 0.4--0.5. Only in the neurons of the second group significant difference was found in statistical parameters under light and dark conditions. Comparison of the statistical parameters of background activity and that, evoked by a moving light spot, testifies to be possibility of coding information on stimulus movement in the 3d and 4th groups of units.


[Differences in the functional organization of the frog and cat visual centers].

Functional characteristics of neuronal responses of the frog tectum and the cat primary visual cortex were obtained under identical experimental conditions, the intensity and duration of flashes changing within the limits of 6 log. units. The comparison of the characteristics reveals a predominance of neurons with a short summation time and relatively lower thresholds in frogs, the response latencies being 5--7 times longer than those in cats. Nearly all the tectum units can react only to a very narrow range of photic energy different for different cells. In cats most cells react to changes in brightness within a range of 4--5 log. units; the units with a long summation time produce short latency responses with relatively higher thresholds. The revealed differences and comparison of various functional characteristics of neurons in the visual centre of both animals show that frogs possess fixed mechanisms of time and spatial interaction providing for the detection of stimulus brightness by means of inhibitory interaction of single units. In cats such interaction of neural populations and mutual inhibition between adjacent units of the visual cortex are not prominent. Complication and overlapping of interneuronal connections result in the convergence of day and night vision signals to one neuron and in the ability of single cells to react to the whole "working" light range used by the cat visual system.


[The effect of acetylcholine on the membrane potential of goldfish retina horizontal cells and the frog electroretinogram].

The effect of acetylcholine was studied as applied to horizontal cells of the goldfish retina and frog electroretinogram ACh (1-10-9--1-10-3 M) depolarized the cells. The highest level of depolarization never reached the O-level of the membrane potential and was approximately equal to the membrane potential in the dark. ACh (1-10-2--5-10-2 M) inhibited b- and d-waves and revealed the stable PIII component. It is supposed that ACh may be a transmitter in retinal outer synpatic layer.


[Morphologic types of bipolar cells identified by regular grids of their axonal varicosities in the inner synaptic layer of the clupeid retina].

A morphological structure of the inner plexiform layer in the acute vision area was studied in the retina of five Clupeidae species by a light microscope. It is shown that this layer is a three-dimensional regular grid formed by bulbous varicosities (synaptic complexes) of the axons of the bipolar cells. These varicosities arranged of different levels of the inner plexiform layer form mutually coordinated periodic grids differing in the orientation and periods. The analysis of this structure shows that not less than three types of bipolar cells take part in its organization.


[A microscopic study of the comparative morphology of the retina].

The cytoarchitecture layers and sublayers of the retina in pike, frog and cat are essentially different. The sublayers of internal granular layers 6a, 6b, 6c, 6d in these species differ qualitatively and quantitatively. The dendrites of ganglion cells and branches of amacrine cells are greatly laminated in the frog retina due to a complex stratification of the inner plexiform layer (about 10 sublayers). In all the vertebrates studied the ganglion cells are of two main types; symmetrical and asymmetrical with many variations. Asymmetrical amacrine cells are found in the pike and frog retina. The existence of vertical branches of amacrine cells in the outer plexiform layer in the cat retina is confirmed. The morphological features of the retina are discussed from the view point of physiological facts.


[Reactions of frog retinal rods to light].

The amplitude and shape of the rod photoresponses were investigated at different intensity, duration, wavelength and diameter of the light spot. Intracellular recordings were performed from the green and red rod outer sigments. An increase in the light intensity produced an increase in the amplitude and a decrease in the time rise of the response. An intensive light flash suppressed for a time the rod sensitivity to test flashes. At light spots of large diameter (100--1500 mum) delayed depolarizing deflection was observed. The latter was conditioned by illumination of receptor surroundings and, apparently, was due to horizontal cells activity. The possible role of the depolarizing effect of the rod surroundings illumination is discussed.


[The relationship between strength and the amplitude of evoked response components in the human somatosensory cortex].

The intensity curves were determined for the individual components of the human somatosensory evoked response, led off from the contra and ipsilateral motor and contralateral visual areas. The amplitude of the early components steeply increased, reached "saturation" and decreased with more intensive stimuli, their peak latencies being constant. The late components were characterised by continuous increase of amplitude, and the decrease of peak latencies for the lowest part of the curve. The responses in both frontal regions were identical, while those from the frontal and posterior leads were significantly different. The obtained data indicate a marked difference between mechanisms producing individual components of the evoked response.


[The effect of temperature changes on evoked potentials of the fish olfactory bulb].

Perches were kept at 10 degrees C and fixed in a chamber through which water was perfused. During the experiment the water temperature was changed. The potentials induced by electric stimulation of the olfactory nerve were recorded from the dorsal surface of the olfactory bulb. The oscillations of the evoked potentials separated into several components when the temperature was lowered. Six components were found in the evoked response of the olfactory bulb at 8 degrees C.


[Correlation of potentials evoked by tones and clicks during simultaneous recording from many points in the auditory cortex of awake cats].

In unanaestheized cats the vooked potentials to various tones and clicks er simultaneosly recorded at 7 auditory and 1-2 somatosensory cortical points. The comparions of the evoked potentials to pure tones of equal lodness ranging from 250 to 7000 Hz showed no common cortical tonotpic distribuion. However there is an individual dependence of the potential components on the soung pitch and location of the recording point in the auditory cortex. The knonwn evoked poteintial dependence on sound intensity was confirmed and more developed regularity of this relation was revelead. With a change in sound intensity the absoulte and relative mangnitude alterations in all the potential components were observed...


[Responses of neurons in the SI zone during a defensive conditioned reflex to sound].

Responses of single neurons in the primary projection zone of the somatosensory cortex to conditioned and electrocutaneous reinforcing stimuli were investigated in chronic experiments on cats with a preliminary developed sound conditioned defensive reflex. Five types of neuronal responses to reinforcing stimulus during application of combination were separated; such differentiation was impossible for neuronal responses appearing in the place of the absent reinforcing stimulus. A comparison of neuronal spike activity with the conditioned movement reaction revealed strict correlation between these processes. The conditioned movement reaction usually preceeded the conditioned neuronal response.


[Responses of squirrel visual cortex neurons to patterned visual stimuli].

The responses of visual cortical neurons to patterned visual stimuli were studied in squirrel Sciurus vulgaris. The direction selective, orientation-selective and non-selective neurons were observed. Most direction-selective and non-selective neurons were sensitive to high speeds of stimulus movement--hundreds deg/s. The direction-selective neurons exhibited their selectivity at such high speeds in spite of the short time of the stimulus movement through the receptive field. Orientation-selective neurons (with simple or complex receptive fields) were sensitive to lower speeds of the stimulus movement (tens deg/s). Some mechanisms of the properties described are discussed.


[The role of polymodal synaptic influences in the formation of temporary connections in the microsystems of association cortex neurons].

Significance of various sensory convergence of the neuronal activity was investigated in unanaesthetized cats in the process of elaboration of time connections. The elaboration of time connection was realized after studying neuronal responses elicited by the direct electrical or sensory stimulation (light, sound, tactile and proprioceptive stimulation). 42 per cent of all neurons and about 90 per cent of learned cells were found to be polysensory in the investigated cortex. The data obtained are considered from the standpoint position of the hypothesis on the microsystem principle of organization underlying time connection and convergence.


[The effect of adrenaline and adrenal desympathization on cerebral convulsive activity].

The influence of adrenalin and bilateral adrenal desympathization on the seizure activity of the brain caused by dorsal hippocampal electric stimulation was studied in adult cats. It is shown that within some days of adrenal bilateral desympathization the threshold of hippocampal epileptogenic stimulation fells and the duration of the seizure action grows. Intravenous injection of adrenalin causes an increase in the effectiveness of the hippocampal epileptogenic stimulation. Injection of small doses of adrenalin into the mesencephalic reticular formation causes suppression of the evoked seizure activity: the threshold of hippocampal epileptogenic stimulation increases and duration of seizure discharges reduces. It is assumed that one of the main factors limiting the seizure activity of the brain is the enrichment of the circulating blood with adrenalin.


[Functional interrelationships of the structures of the limbic system during initiation of seizure activity].

A functional epileptogenic focus was created by repeated electrical stimulation of the limbic structures activated by the conditioned sensory stimulus. Seizure activity in response to the conditioned stimulus was observed only in the hippocampus though other limbic structures were also stimulated. After bilateral electrolytic lesion of the septum no highly synchronized seizure activity was observed in response to the conditioned signal. In this case spontaneous high amplitude activity was found. These observations permit suggesting that the hippocampus plays the role of an initiator of the seizure activity, whereas the functional connection between the septum and hippocampus promotes its final synchronization.


[Efferent connections of the caudate nucleus in cats].

The structural and ultrastructural changes in the frontal cortex and globus pallidus were investigated after local or extensive destructions of the caudate nucleus. Using the Fink-Heimer method few degenerating fibres of medium and small sizes were observed in the frontal cortex following the local destruction of the caudate nucleus with preliminary implanted electrodes (2-16 months prior to electrolytic destruction). The extensive destruction of the caudate nucleus without preliminary implanted electrodes is accompanied by mass degeneration of fibres with different calibre in the frontal cortex. Light and electron microscopy of the globus pallidus confirmed the existence of thin degenerating axons 0.5-0.6 mum in diameter after the local lesion of the caudate nucleus. Degenerating changes in axo-dendritic and axo-somatic terminals of the pallidal region occur by "dark" type. The degenerating fibres of the medium size in the frontal cortex following the caudate nucleus destruction are suggested to be the axons of thalamic neurons but not those of the destructed nucleus cells.


[Morpho-functional changes in the tegmentum mesencephali of turtles following enucleation].

Morpho-functional changes in the mesencephalic centre of the turtle (Emys orbicularis L.) were studied during optic nerve degeneration. It was observed that synaptic terminals in this centre undergoing the "dark" degeneration are associated with myelinated optic fibres and terminals undergoing the "light" one are associated with unmyelinated fibres. The first low amplitude component of the evoked potential disappears with degeneration of myelinated fibres of large diameter during the "dark" degeneration (4-5 months after enucleation). The first high amplitude component disappears with degeneration of the middle-sized myelinated fibres and the end of the "dark" degeneration (7 months after enucleation). The characteristics of the second high amplitude component which reflects the excitation of both thin myelinated and all unmyelinated fibres, begin to change with degeneration of unmyelinated fibres during "light" degeneration (2.5-3.5 months). This component disappears with degeneration of the thin myelinated fibres (7 months).


[Comparative electrophysiologic characteristics of afferent representation in the cortical and striatal portions of the turtle forebrain].

Visual and somatic representations are established in the subcortical striatal sections of the forebrain (pallial thickening, dorsal ventricular ridge and putamen) of immobilized weakly anaesthetized turtles. According to electrophysiological characteristics they are similar to the corresponding sensory representations in the general cortex. The absence of reliable discrepancy between the latencies of potentials in the cortex and striatum evoked by light flash or by the electric stimulation of the dorsal thalamus indicates that visual projectional fibres ascending from the lateral geniculate nucleus terminate both in cortical and striatal structures. Differences in the latency distribution of single unit responses in the cortex and striatum to visual and thalamic stimulations can be due to the existence, besides the geniculo-telencephalic pathway, of a rotundo-telencephalic visual channel having direct connections with the striatum and polysynaptic ones with the general cortex. Significant differences in latency between the evoked potentials and neuronal responses in cortical and subcortical structures to electric stimulation of the skin shows that somatic projectional fibres on their way to the cortex are relayed in the striatum, thus indicating a lower corticolization degree of the somatosensory system as compared with that of the visual one.


[Polysynaptic components of the early somato-sympathetic reflex response in the lumbar white rami communicantes].

The second and third components of early somatosympathetic relfex discharge were studied in anesthetized cats. Polysynaptic components of the early somatosympathetic and propriospinal somatosomatic discharges were compared. Evidence was found that these reflexes have both common and specialized interneurons in their central polysynaptic chains. It is suggested that the components of the early somatosympathetic reflex are formed by different types of sympathetic preganglionic neurons, namely the second component by neurons of the lateral horns and the third one--by neurons detected in the lateral part of intermediate zone (axonal velocity less than 1.5 m/s). A classification of sympathetic preganglionic neurons is presented.


[Morphofunctional features of the catfish lateral line analyzer].

The peripheral and central portions of the catfish lateral line system were investigated by conventional light microscopical and electrophysiological methods. N. lat. post. X supplying the neuromasts and the small pit organs of the fish body consists of myelinated nerve fibres with the axonal diameters between 2 and 9 mum. The nerve also contains a number of unmyelinated fibres as well as lateral line nerves in other species. Axon conduction velocities were distributed within a range of 10-15 m/s. All afferents pass through the n. lat post. X to the area acoustico-lateralis of the medulla oblongata. Nucleus medialis is associated with the lateral line system. It consists of n. med. p. dors, and n. med. p. med. The former consists of medium size cell bodies (6-14 mum), which are of an oval or triangle shape. The latter consists of small (4-6 mum) oval cells. N. med. p. dors. and n. med. p. med. are the most distinct at the level caudally to the enter of auditory nerve VIII. Rostrally and caudally the both portions of the n. med. overlap each other. Responses to electrical and mechanical stimulation of the lateral line organs were recorded in the entire area acoustico-lateralis. All the neurons under study were situated at a depth of 400-800 mum in the area nucleus medialis.


[The inhibitory effect of carbon dioxide gas on the post-tetanic hyperpolarization of frog nerves].

CO2 as well as its mixture with O2 were passed through the Ringer solution with nerve in it or through the chamber with the preparation. This caused a cessation of posttetanic hyperpolarization of the nerve. An inhibitory effect of CO2 on the active ionic transport through the membrane of myelinated nerve fibres mediated by change in their internal pH is supposed.


[The influence of the cerebellum on the background activity of medial reticulospinal tract fibers].

Characteristics of background activity of 160 reticulo-spinal fibres of the ventral funiculus were studied in anaesthetized cats with an intact cerebellum. A reduction of the relative quantity of fast-conducting fibres with background activity and changes in the characteristics of this activity as compared with those in decerebellated cats were found. It is suggested that the activity of reticulo-spinal neurons is tonically inhibited by cerebellar influences, the inhibition being differently distributed among different groups of these neurons.


[Background impulse activity of cat pericruciate cortex neurons].

Background spike activity of 66 neurons was recorded extracellularly in the pericruciate cortex of narcotized cats. As a rule it is represented by an irregular spike sequences and occasionally by a burst of two-five spikes. In 77.3 per cent of units the mean frequency of the background activity varied from 0.6 to 20 imp/s, in the other it reached sometimes 100 imp/s. Types of interspike interval histograms are analyzed.


[Reflection of temporal parameters of an optic stimulus in neuronal responses of the senso-motor and visual cortex in cats].

Neuronal extracellular discharges in visual (area 17) and sensory-motor (area 4 and 6) cortical fields to optical stimuli with a duration up to 1000 ms were examined in the chloralozed cats (70 mg/kg). A comparative analysis of neuronal discharge types and of functional shift intervals revealed: 1) an amount of neurons with on--off discharges in the visual cortex is 25% and in the sensory-motor cortex--100%; 2) the functional shift intervals coincide with the on--off discharge time interval for the same neurons; 3) alongside with the common time interval there are specific ranges for each zone (0--200 ms for the visual cortex; 500 ms and more for the sensory-motor cortex); 1) the afterdischarge latency of a neuron is equal to the functional shift interval value of the same neuron. These data are considered as a reflection of the optical signal time parameters by the sensory-motor cortical neurons. Such peculiarities of the sensory-motor area might be important for the time organization of the cortical movement program.


[Findings and reflections on the reverberation of thalamocortical impulses].

Chang's experiments showing the rhythmic afterdischarge in slightly nembutalized cats which he considered as a manifestation of the activity of thalamocortical reverberating circuits, prompted us to study the origin of the afterdischarge in the auditory cortex arising in response to single sound clicks on unanesthetized immobilized and nembutalized cats. The rhythmic afterdischarge was found to be most pronounced at light anesthesia with a tendency of background activity to synchronization, which may be evidenced by rare bursts of spindles. During the prolonged spontaneous desynchronization as well as during stimulation of mesencephalic reticular formation no rhythmic afterdischarge and no spontaneous bursts of spindles arose. With a deepening of anesthesia slow afterdischarge undergoes precisely the same changes as spontaneous spindle bursts (the duration tends to increase for a while with a subsequent decrease, the frequency and then the amplitude of waves decrease and eventually they disappear altogether). These and other findings suggest that rhythmic afterdischarge of the auditory cortex arising to sound clicks seems to be similar to the evoked spindle in response to peripheral and central stimulations. It was reported in many previous and recent papers. The fact, that following the cooling or ablation of the auditory cortex the rhythmic afterdischarge to sound clicks as well as spontaneous spindle bursts keep arising in the medial geniculate body without changing their patterns, militates also against the possibility of thalamocortical reverberation.


[A comparative statistical study of the background impulse activity of hippocampal neurons in situ and in tissue culture].

Statistical characteristics of background impulse activity of the rat hippocampal pyramidal neurons in situ and in vitro were compared. A statistical analysis shows a good coincidence of the following numerical characteristics of interspike intervals distribution: mathematical expectations, standard deviations, coefficients of asymmetry and excess. This coincidence proves the preservation of normal functional properties of hippocampal neurons in tissue culture. However some differences were found in the structure of the compared spike sequences which may be attributed to essential differences between the neuronal networks in the objects studied.


[Background [corrected] activity and evoked responses of pigeon cerebellar cortex neurons to stimulation of the vagus nerve and nerves of the extremities].

Background activity and evoked responses of cortical cerebellar neurons to electrical stimulation of n. vagus and limb nerves were investigated in decerebrated pigeons. The neuronal responses were of tha same type independing of the type of stimulation. The phasic and tonic responses were chiefly of an excitatory type. The phasic responses were short (10-20 ms) and long-latent (up to 80 ms). The latter were predominant. The neuronal responses to n. vagus stimulation as compared with responses to limb nerves stimulation were observed in a smaller number of neurons and revealed longer latent periods and lower ability to rhythmic reproduction. They could not be produced through the climbing fibres.


[Participation of different groups of afferent fibers of mesenteric nerves in vasomotor reflexes].

The dependence of the magnitude and character of vasomotor reflexes on the amplitude of mesenteric nerve tetanic stimulation was studied in experiments with cats anesthetized with urethane and chloralose. A comparison of the stimulus amplitude reflex magnitude curves with the previously obtained data on electrical excitability of various groups of mesenteric nerves afferent fibres revealed that there are 3 groups of "vasomotor" afferents in mesenteric nerves: "fast" Adelta-fibres (conduction velocity above 8 m/s) the impulses of which evoke depressor or small pressor reflexes; "slow" Adelta-fibres (conduction velocity below 8 m/s) the impulses of which evoke pressor reflexes or interacting with impulses of lower-threshold "fast" Adelta-fibres, either decrease depressor reflexes evoked by impulses of these fibres or increase pressor reflexes evoked by these fibres impulses; C-fibres the impulses of which increase pressor reflexes evoked by impulses of "slow" Adelta-fibres.


[The effect of sodium, potassium and calcium ions on the functional characteristics of catfish electroreceptors].

Afferent responses of single afferent fibre from small pit organs to various concentration of potassium, sodium and calcium ions were studied in the catfish (Ictalurus nebulosus). The receptors were stimulated with d. c. pulses. Calcium concentration between 0.4-5 mM/1 were practically ineffective. Calcium concentration from 5 to 100 7m/1 increased the threshold to electrical stimulation. 2mM/1 sodium and potassium solutions caused an increase in the threshold to the anodic stimuli and elimination of the responses to the cathodic ones. This effect disappeared after the addition of 0.4 mM/1 CaCl2 or application of long anodic stimuli of great intensity (10(-8)-10(-7) A/mm2). With an increase in potassium concentration to 10-20 mM/1 the threshold returned to the initial level. Potassium concentrations above 20 mM/1 increased the threshold to electrical stimuli. The effect of ions was compared with the action of electric current.


[Several characteristics of the impulse reactions of crayfish receptor neurons to stimuli of different intensity].

Properties of the receptor cells responses in n. telsoni ventralis to the change in the direction, velocity and angle of displacement of the uropod hairs were studied in acute experiments with the crayfish Astacus leptodactylus. It is shown that the receptor neurons are characterized by an inverse relation between the latent period and the velocity of hairs displacement and by impulse frequency proportional to this velocity. The selective sensibility of the various receptor neurons to the direction and change of angular displacement of a hair was found. Certain zones of the angle of displacement of the uropod cells characterized by evoked maximum receptor cells responses are distinguished.


[Propagation of the action potential in the vicinity of the soma of giant neurons after the Hodgkin--Huxley model].

The Hodgkin--Huxley equations were used to investigate the loading effect of somatic membrane on spike generation in an axon. The depression of the amplitude of antidromic spike near the soma is demonstrated. It is shown that direct activation of the neuron by a current pulse through an intracellular electrode inserted in the soma causes the spike origination in the axon rather far from the cell body because of the loading effect. An increase in the magnitude of the current pulse causes a shift of the site of spike initiation towards the soma.


[The potential-dependent nature of the sodium pump of mollusk giant neuron membranes].

The effect of the membrane potential on the pump current induced by ionophoretic injection of sodium ions into the isolated and semiisolated neurons and the effect of sodium ions intracellular concentration on the potential dependence of the pump current were studied in snails Helix pomatia and Helix italiana. It is found in voltage clamp experiments that the pump current can reverse its direction under a sufficient membrane hyperpolarization (above--80 divided by --120 mV). Additional injections of sodium ions into the neuron increases the potential dependence of the pump current and facilitates the appearance of reversed pump current. It is supposed that this reversal may be due to activation of potassium permeability of the membrane coupled in some way with the acitvity of the enzymatic transport mechanism.


[Magnetic field perception by the electroreceptor system of fish].

Responses of 40 neurons in the acoustic-lateral area to electrical stimuli and changing magnetic induction were studied in the Black Sea skates Dasyates (Trigon) pastinaca. The smallest magnetic induction change which caused a response was 0.8 Gs/s, proving the possibility of perception of the geomagnetic field by electroreceptors of a slow-moving fish. Opposite reactions to magnetic stimulation were observed in neurons responding to electrical stimuli in the same way but connected with receptors of the right and left sides of the fish. Short-circuiting between the inner medium of the fish and the sea water showed that the induction current circuit is isolated from the inner medium and, apparently, formed by the ampullary canals.


[Monosynaptic inhibitory postsynaptic potentials of cerebral cortex neurons].

The auditory cortes of cats immobilized with d-tubocurarine was stimulated by monopolar macroelectrodes (tip diameter 100 mu) or micloelectrodes (tip diameter 100--15 mu). In both cases in cortical neurons located closely to the stimulation point IPSPs were recorded with latencies ranging between 0.4--1.2 and 1.4 6.0 ms. It is suggested that IPSPs of the first group are generated in response to direct stimulation of the bodies and axons of the inhibitory cortical neurons (monosynaptically). The amplitude of such IPSPs ranged in different neurons from 3 to 15 mV and their duration was between 4 and 15 ms. Many of them were complicated by later additional inhibitory volleys. 1.5% of all IPSPs generated in response to geniculocortical fibres stimulation had latencies between 0.8--1.3 ms. It is suggested that these IPSPs were also evoked monosynaptically.


[Electrical characteristics of neurons in the motor region of the cat cerebral cortex].

Electrical parameters of motor cortex neurons were studied in acute experiments on cats. Input resistance of cortical neurons varied from few to some tens of Momega (mean value 11.11 +/- 3.93 Momega). A hyperbolic relation between threshold current and input resistance for cortical neurons was found. Velocity of axon conduction and input resistance are negatively correlated. Time constant of the membrane (to) was 7.1 +/- 3.46 ms. In some neutrons a second time constant t1= 1.65 +/- 0.36 ms was also found. Using result of Rall's model, the electronic length of the dendrite was computed, it was found to be 3.66-0.94 in units of length constant. These data are compared with those obtained on motoneurons. Functional significance of electrical parameters of cortical neurons is discussed.


[Functional organization of pathways transmitting auditory signals in the somatosensory zone of the cat cerebral cortex].

The functional properties of the auditory projections to the somatosensory zones S2 and S were studied by recording evoked potentials in anesthetized and vigil unrestrained cats. The thresholds of evoked potentials recorded from SI and SII were higher by 15--35 db than those from AI. No tonotopical localization was found in SI and SII. Signals about pure tones of different frequencies were conducted to SI and SII via area AI. The signals about clicks were ascending to SI and SII not only through this pathway, but also through other ones. It suggested from the time constants analysis of the first positive wave of the evoked potentials that the interneuronal organization of the cortical auditory projections to AI is not so comples as that to SI and SII. The differences in amplitudes of evoked potential recorded in SI indicate that the head projection areas receive higher portion of the auditory projections. This is confirmed by the morphological evidence.


[Changes in the receptive fields of cat lateral geniculate body neurons following removal of corticofugal influence].

The number of spikes in responses of the lateral geniculate neurons increased after section of ipsilateral corticogeniculate connections. The operation caused a distinct intensification of lateral inhibition effects in the operated side. Zones of complete spatial summation in the receptive fields of neurons in the operated side changed according to the contrast of the used light stimuli. It is suggested that corticogeniculate influences are of inhibitory nature and that receptive fields possessing a changing zone of spatial summation are realized by intrageniculate mechanisms.


[The effect of peripheral stimulation on the electrical activity of the neocortex in chronic premesencephalic cats].

Chronic experiments were carried out with 19 adult cats. It is demonstrated that following a premesencephalic sectioning of the brain stem, with the lemniscal pathways being spared, on the second and third day after the surgery, auditory, olfactory and skin stimulations caused diffusive activation of the neocortex. Photic stimulation, though evoking responses in the visual cortex, was unable to desynchronize the neocortical electrical activity. Taking into account the data on the organization of hypothalamic afferent connections, it is suggested that diffuse activation of the neocortex in cats, when the mesencephalic reticular formation is completely excluded, occurs during auditory, olfactory and skin stimulations due to excitation of the posterior hypothalamus.


[Connections between the posterior lateral nucleus of the thalamus and the cortex of the cat suprasylvian gyrus].

Responses of neurons in the thalamic nucleus lateralis posterior (LP) to the stimulation of area 5b and 21 of the suprasylvian gyrus were studied in unanesthetized immobilized cats. Antidromic responses of these neurons indicate the existence of a direct pathways from LP to area 5b and 21. Such pathways are more extensive to area 5b. Relatively long latencies (1.2--60.0 ms) of antidromic responses show that axons of these neurons are slowly conducting (0.3--16.6 m/s). Short-latent 2--3 ms orthodromic responses to LP neurons indicate the existence of a direct pathway from the suprasylvian cortex to LP. Input to LP from area 5b is more powerful than from area 21. The converence of volleys from both areas is seen in 44% of investigated neurons. The stimulation of the suprasylvian cortex evokes postsynaptic inhibition in the most LP neurons.


[Spinal cord electrical activity during focal depression of inhibitory processes].

Cord dorsum potentials, dorsal root potentials and field potentials were studied in rats with local depression of inhibitory processes in lumbar spinal segments produced by tetanus toxin. The study was carried out at a stage when excitation of a neuronal population with depressed inhibitory processes (the so-called "determinative dispatch station") evoked generalized excitation of spinal and bulbar motoneurons. In experiments with spinal animals it was shown that the stimulation of a cutaneous nerve on the affected side evokes DRP's P-waves and field potentials of greater amplitude and longer duration than those evoked on the opposite side or in healthy rats. The prolonged P-wave revealed several components which coinsided with prolonged ventral root discharges. This wave could be recorded from an enlarged spinal cord region. The maximal increased and prolonged negative field potentials corresponding in time to the enlarged P-wave were found in the ventral quadrant of the affected side. In this region "spontaneous" rhythmical negative slow waves were recorded. The mechanisms of spreading excitation from the site with depressed inhibitory processes and the localization of this site are discussed.


[The possibility of different effects of primary afferent depolarization on spinal reflexes].

Intensive depolarization of central primary afferent terminals evoked by strong stimulation of afferent nerves or dorsal root produces recurrent discharges which may be recorded as antidromic dorsal root reflexes. It is shown that the discharges are simultaneously propagating in the dorso-ventral direction and thus produce facilitation of spinal reflexes. The obtained results allow suggesting the existence of two types of influences of the primary afferent depolarization on the reflex transmission to the spinal cord.


[The influence of bemegride on frog spinal cord root potentials].

The effect of the convulsant bemegride (beta-ethyl-beta-methyl-glutharimide) on the electronic potentials in the frog spinal roots was investigated in situ. Intravenous injection of the bemegride subconvulsant doses (6.8 +/- 2.7 mg/kg) depressed rapidly the electrotonic dorsal root potentials (DRP) evoked by a stimulation of the adjacent dorsal root (DR) or the ventral root (VR). They were reduced by 55--67% 3-6 min after the bemegride injection. The effect of bemegride was reversible and the DRP amplitude restored its initial value within an hour. Ventral root potentials after bemegride injection revealed only greater amplitude fluctuations. A conclusion is made that bemegride is a selective and potent depressor of the primary afferent depolarization in the frog spinal cord.


[Rubrofugal influences on the spike activity of neurons of the medial reticulo-spinal tract].

Synaptic influences from the red nucleus on the activity of the medial reticulo-spinal tract fibres were studied by microelectrode recording in throacic spinal cord of an anesthetized cat. It is found that the red nucleus establishes monosynaptic connections with many pontine and medullary reticulo-spinal neurons with fast (60-105 m/s) and moderate conducting (45-60 m/s) axons. Background activity of these fibres (characterized by grouping of impulses) is accelerated by repetitive stimulation of the red nucleus. Most neurons with slow conducting axons (10-45 m/s) are polysynaptically excited by the red nucleus stimulation, but their background activity (with uniform distribution of impulses) is depressed. Such rubro-reticular influences were also observed in cats with preliminary destroyed tectal and interstitial structures. Some functional aspects of the rubro-reticulo-spinal system are discussed.


[Membrane currents induced by entrance of sodium ions into giant mollusk neurons].

Membrane currents induced by the intake of sodium ions during tetanic stimulation or steady depolarization under voltage clamp conditions were studied on giant neurons of the mollusc Helix pomatia. It is shown that the induced current may be separated into two components: the fast one having a reversal potential close to the EK level, and the slow one slightly dependent on the membrane potential in the region --50 divided by --90 mV Strophanthin K and replacement of external sodium with lithium or calcium ions eleminated for slow component and reduced the fast one. A conclusion is made that the slow component is produced by the activation of the electrogenic sodium pump, and the fast one-- by an increase in potassium permeability probably coupled to intensive activity of this pump.


[Reactions of the neurons of the reticular and ventral anterior nuclei of the optic thalamus to afferent stimulation of different modalities].

Responses of 146 reticular (R) and 98 ventral anterior (VA) thalamic neurons to electrical stimulation of pads, to light flashes and sound clicks were studied in cats immobilized with d-tubocurarine or myorelaxine. The contralateral forepaw was the most effective receptive field: 24.9% of R and 31.3% of VA investigated neurons responded to its stimulation. Only 4.4% of R and 2.4% of VA neurons responded to the click. Almost all responding neurons reacted to different kind of the applied stimulation by phasic or tonic excitation. Inhibition of background activity was observed after the pads stimulation only in 2.6-4.3% of R and in 1.7%-2.1% of VA neurons. The latency of phasic responses in most neurons ranged: to electrical stimulation of the contralateral forepaw from 6 to 64 ms, to the contralateral hindpaw -- from 11 to 43 ms, to light -- 10-60 ms, and to the click -- 8-60 ms. 75.1-95.6% of R and 68.7-97.6% of VA neurons did not respond at all to different kinds of peripheral stimulation. Of a sample of cells tested to all inputs 25% of R and 47% of VA neurons responded to stimulation of more than one paw; 16% of R and 22% of VA neurons revealed convergence of volleys of different modality. The functional role of this convergence consists in inhibition (more seldom facilitation) of the neuronal response to a testing signal following 40-70 ms after a conditioning one.


[The relationship between the second zone of the auditory cortex and the medial geniculate body and first auditory zone].

Extracellular and intracellular responses of the second auditory (AII) cortical neurons to stimulation of geniculocortical fibres and first auditory cortex (AI) were studied in experiments carried out on cats immobilized with d-tubocurarine. It is shown that in these neurons there appear antidromic, mono-, di- and polysynaptic spike potentials to geniculate and AI stimulation. The number of antidromic reactions was about twice as low as in AI under the same conditions. Di- and polysynaptic responses predominated among orthodromic reactions. Intracellular recording revealed EPSP, EPSP-IPSP and primary IPSP in AII neurons. Response latencies in AII neurons to AI stimulation were in the range of 0.75-6.0, 6.1-16.0, 18.0-23.0 and 60.100 ms. After the medial geniculate body was removed, the number of responses with a latency of 6.1-16.0 ms decreased considerably. In some neurons spike pontentials appeared both to geniculate and AI stimulation. Comparison of the response latencies at both types of stimulation showed that impulses from AI come in AII not only to the neurons that are inputs for MGB impulses but also to neurons in the sebsequent link of intracortical neuronal chain. In most AII neurons disynaptic IPSP appeared at AI stimulation. Only in one case IPSP with a latency of 1.0 ms was recorded being probably monosynaptic.


[Conduction of excitation in the cat vixual system].

The responses of striate cortex units to the lateral geniculate body and optic tract stimulations were recorded extra- and intracellularly in experiments on cats immobilized with d-tubocurarine. 92% of responded cells were activated orthodromically with a latency ranging between 2 and 12.5 ms. Most of these responses may be divided into three groups--2-2.5, 3-3.5, 4-4.5 ms. The latency of each group coincided with the latency of three different parts of the evoked potentials positive components. 8% of the responding cells were activated antidromically. The difference of the response latency to the stimulation of both structures in 55.8% of cells ranged from 0.5 to 1 ms. The existence of three main groups of optic radiation fibres with conduction velocities of 28.5-16.6, 11.7-8.9, 7.4-6 m/s is postulated. A conclusion is made that peculiarities of the afferent volley formed in retino-geniculate paths are not significantly changed after its processing in the lateral geniculate body.


[Electrical characteristics of the granular neurons of the carp olfactory bulb].

Using the intracellular recording technique the electrical activity of the carp olfactory bulb granular cells and secondary neurons was studied. Early and late EPSP and IPSP were the synaptic responses of granular cells both to the olfactory nerve and olfactory tract electrical stimulation. The comparison of responses of the granular cells and secondary neurons led to the conclusion that the granular cells are interneurons producing post-synaptic inhibition of the secondary neurons. It was supposed that the granular neurons are excited by dendro-dendritic and reccurent-collateral pathways and that the inhibitory synapses are located on the dendrites of secondary neurons which are in contact with the olfactory nerve terminals.


[Responses of inferior colliculus neurons to frequency modulated signals and the temporal characteristics of inhibitory interaction].

Comparison of neuronal responses (118 units) in the inferior colliculus of anesthetized rats to frequency-modulated (FM) sounds and time characteristics of two-tone inhibition were carried out. High sensitivity to certain direction of FM in 2/3 of neurons coincide with spatial characteristics of excitatory and nihibitory areas: their shape, width and arrangement. In 1/3 of neurons directional response specificity is shown to be determined by different time course of inhibitory process evoked by high-frequency and low-frequency tones.


[Formation of a generator of excitation in the gigantocellular nucleus of the medulla oblongata during disruption of inhibitory processes].

Neuronal activity in the gigantocellular nucleus after injection of tetanus toxin was studied on decerebrated cats. The toxin was used as a substance producing a deep and continuous suppression of inhibitory processes. The increase in the amplitude and rate of neuronal discharges, in the integral background and evoked activity as well as in the number of active neurons and that of neurons with burst activity was recorded in the "poisoned" nucleus. The enhanced activity in the investigated regions of the poisoned nucleus might be temporarily suppressed by a strong direct electrical shock and by glycin administrations to those regions. The obtained data indicate that a pool of neurons with disturbed inhibitory processes forms a generator of enhanced excitation. The mechanisms and characteristic features of the activity of such generators are discussed. The possibility of modelling neurological syndromes by production of similar generators in various parts of the central nervous system and their relation to the earlier described phenomenon of "dispatch station" are considered.


[Classification of the vestibulospinal neurons of the cat Deiter's nucleus].

The antidromic activation of neurons in the cat Deiters nucleus to stimulation of spinal cerevical segments was studied using the intracellular microelectrode recording technique. Separate components of the antidromic action potential and its after-deflections were analyzed in fast- and slow-conducting neurons. A direct dependence between the parameters of the after-deflections and duration of the refractory period was revealed for these neurons. Variable responsivity of neurons with the same axonal conductance velocity is shown to be dependent on the after-depolarizing potential.