Showing papers by "University of Turin published in 1972"

Reversal time distribution in the perception of visual ambiguous stimuli.

Abstract: Reversal of perspective for ambiguous optical stimuli (Necker cube, Schroder staircase, honeycomb) has been studied, determining the statistical distribution of time intervals spent on each percept. The experimental distributions can be fitted with the gamma function, characterized by two parameters n, b. The two parameters are not independent, showing a correlatiomn ϱ = 0.74. Subsequent intervals appear to be largely independent; from the beta distribution for the fraction of time spent on a given percept, one can show that the subjects differ only in regard to the variance of this variable.

Molecular basis of gouty inflammation: interaction of monosodium urate crystals with lysosomes and liposomes.

Abstract: Crystals of monosodium urate, like silica, rupture lysosomes and liposomes in media which do not constrain hydrogen bonding. Liposomes are rendered susceptible to urate-induced lysis if they contain cholesterol and testosterone, but refractory if they contain 17-β-oestradiol. Similar events in vivo may account for crystal-induced gouty inflammation as well as explain why men rather than women get acute gout.

Electron microscopical identification of the immunofluorescent gastrin cells in the cat pyloric mucosa.

Abstract: To solve the unsettled problem of the identification of the gastrin cells, a study has been undertaken on the electron microscopical characteristics of the gastrin-containing cells of the cat pyloric mucosa. Cells which, on semithin sections, were shown by an immunofluorescence method to contain gastrin, have been identified on serial ultrathin sections. The ultrastructural features of these cells are those which have been described as characteristic of the G cells of the antropyloric mucosa. Other non-entero-chromaffin endocrine cells, which have been recognized as the D cells of the gastro-intestinal mucosa, did not result to contain gastrin.

An experimental investigation on the mechanisms of interaction of asymmetrical acute epileptic foci

Abstract: UMMARY In the cat the activity of two asymmetrical foci created by bilateral cortical application of conjugated estrogens (Premarin®) was compared with that of identical foci individually induced. The activity of each focus was greatly enhanced in the presence of the contralateral focus. This indicated that a facilitatory reciprocal interaction occurred between the two foci. Investigations of the pathways followed in this interaction by callosal split or cortical-callosal isolation showed that in cats with both foci the procedures were followed by a marked increase or decrease in epileptic activity respectively. By contrast both procedures were without effect in cats affected with only one focus. Discussion of the results led to the conclusion that the facilitatory interaction between the two asymmetrical foci was the resultant of two opposing mechanisms, namely an inhibitory mechanism via transcallosal pathways and a predominant facilitatory mechanism using cortical-subcortical-cortical pathways. RESUME On a compare chez le chat l'activite de 2 foyers asymetriques crees par l'application sur le cortex, des 2 cotes, d'oestrogenes conjugues (Premarin®) avec celle de foyers identiques induits individuellment. L'activite de chaque foyer etait fortement augmentee en presence du foyer contro-lateral, ce qui indiquait l'existence d'une interaction reciproque facilitatrice entre les 2 foyers. Les voies empruntees pour cette interaction ont eteetudiees par la section calleuse ou l'isolement cortico-calleux et l'on a ainsi montre que chez, les chats porteurs de 2 foyers, ces experiences etaient suivies respectivement d'une augmentation ou d'une diminution marquee de l'activiteepileptique. Au contraire, elles etaient sans effet chez les chats porteurs d'un seul foyer. On a conclu, de ces resultats, que l'interaction facilitatrice entre les 2 foyers asymetriques etait la resultante de 2 mecanisme opposes, un mecanisme inhibiteur empruntant la voie transcallosale et un mecanisme facilitateur, predominant, utilisant les voies cortico - sous-cortico-corticales.

Chromosome banding with trypsin.

Abstract: Preliminary results on banding human chromosomes by trypsin after fixation are reported. This easy technique allows the identification of all the chromosomes of the human karyotype.

Immunohistochemical and ultrastructural detection of the secretin cell in the pig intestinal mucosa.

Abstract: Le cellule a secretina vengono identificate con l'immunofluorescenza nella mucosa duodenale e digiunale di maiale facendo uso di antisieri anti-secretina sintetica porcina. Parallele ricerche ultrastrutturali consentono di identificare in un tipo peculiare di cellular endocrina l'equivalente ultrastrutturale della cellular a secretina.

Embryonic and postnatal development of choline acetyltransferase activity in muscles and sciatic nerve of the chick.

Abstract: THE DEVELOPMENT of neuro-muscular correlations begins when the root motor fibres, growing out of the neural tube, reach the myotomes. In the chick embryo the first contact occurs between the 60th and the 70th h of incubation; at this stage a diffuse acetyl cholinesterase (AChE) activity can be demonstrated in myotomes by means of a histochemical technique (for review of the pertinent literature, see FILOGAMO and GABELLA, 1967). These observations have suggested that the synthesis of AChE might be induced by some compound released by the exploring fibres branching into the myotomes. Recently LENTZ (1971) has demonstrated that several nerve tissues are effective in maintaining the AChE activity of cultured adult newt muscles, even when the two explants are separated by a Millipore filter; this observation provides further evidence that the effect of nerve on muscular AChE is mediated by a diffusible factor. Most authors have discussed the possibility that the inductive factor involved in AChE appearance in myoblasts could be acetylcholine (ACh) itself (for review, see FILOGAMO and GABELLA, 1967; GUTH, 1968; FILOGAMO and MARCHISIO, 1971). In the present investigation the choline acetyltransferase (ChAc) activity was studied in developing muscles and nerves to obtain information about the following points: the ability of exploring fibres to synthesize ACh; the chronological relationship between the penetration of exploring fibres and the onset of both ChAc and AChE activities in myotomes and limb buds; the variations of ChAc activity in coincidence with the appearance and development of motor end-plates and the onset of neuro-muscular activity. Muscles and nerves were dissected from chick embryos and chicks at various developmental stages, from the 3rd day of incubation to hatching and from hatching to 3 months of age. ChAc activity was determined in axial (paravertebral) muscles, limb (thigh) muscles and sciatic nerve (intra-abdominal tract). Whole muscles were dissected out, owing to theuneven distribution of ChAc within single muscles (HEBB, KRNJEVIC and SILVER, 1964; ISRA~L, 1970; FLOOD, FONNUM and STORM-MATHISEN, 1970). In the case of axial and limb muscles, at earliest stages enzymic activity was determined in myotomes and limb buds, respectively. Dissection was carried out under a stereomicroscope and histological controls were made to check for possible contamination by heterogeneous materials. After dissection, samples were quickly frozen and stored at -40°C until assayed. ChAc activity was determined by means of the radiometric method described by FONNUM (1969) (microassay procedure). Homogenates were prepared in icecold 0.5 % Triton X-100 v/v. Tissue protein was determined in each sample by the method of LOWRY, ROSENBROUGH, FARR and RANDALL (1951) and ChAc activity was related to the protein content. Table 1 summarizes the results. In the interpretation of these data, it was borne in mind that ChAc is exclusively present in the nervous component of muscles (HEBB et al., 1964; ISRAEL, 1970; FLQOD et al., 1970). In embryonic axial and limb muscles, ChAc activity shows a similar pattern. At the 3rd day no activity could be measured in myotomes and limb buds. In the subsequent days (4th day in myotomes and 6th day in limb buds) a peak was measured. The peak is followed by a significant decrease (P <0.001) and by a new significant increase (2' <0001) after the 12th day, which leads to high values at the time of hatching. The early peak is measurable in the period when root motor fibres, sprouting from the neural tube, reach myotomes or limb buds and branch out among the myoblasts. They then contact myoblasts but end freely; synaptic structures have not been detected at this stage. At the same time a diffuse AChE activity first appears in the myoblast sarcoplasm (for review, see FILOGAMO and GABELLA, 1967). The delayed appearance of the early ChAc peak in limb buds is consistent with the

A CUCH-machine: The automatic treatment of bound variables

Abstract: This paper describes a machine for reducing a λ-formula (explicitly given or implicitly by a system of recursive equations) to principal β-η-normal form, with particular attention to the memory structures needed for the purpose, and with some important features: (1) any kind of collision is permitted; (2) the processing of subformulas which will be thrown away [e.g., ((λxy)x) in ((λyz)(λxy)x)] is avoided; (3) there is no need to introduce any fixed point operator like ϕ, etc. The machine structure entails: (1) some store to memorize as side-effects assignment statements with the r.h.s. of a given shape. (2) a number of stacks, one for every λ in the initial formula, partitioned naturally in classes (chains). These stacks admit as entries only words representing variables and they are peculiar in that the operations admitted on the top arewriting anderasing and the operations admitted on the pseudo-top arereading,read-protecting, andresetting readability (the last two operations are chain operations). This structure is critically motivated. (3) A workstack. (4) A pointerstack. The computation runs through four phases: β-generation, β-run, η-generation, η-run. Every generation- (run-) phase is rather recognition- (transformation-) oriented, but we found it more stimulating to emphasize technical similarities rather than methodological differences. Every phase is described and four examples are extensively developed.

Effect of dibutyryl cyclic AMP on interferon production by cells treated with viral or nonviral inducers. 1.

Abstract: SummaryTreatment of mouse L or rat embryo cells with dibutyryl cyclic AMP prevents, or strongly reduces, the production of interferon induced either by poly I.poly C or by Newcastle disease and Chikungunya viruses. The same effect was also observed in cells treated with adrenaline plus theophylline (enhancers of cyclic AMP). In addition the inhibitory activity of dibutyryl cyclic AMP was prevented by suppression of protein synthesis with cycloheximide. Preliminary evidence obtained using metabolic inhibitors suggests that the depression of interferon production may be due to an effect at the transcriptional level. The results are interpreted to indicate a possible role of cyclic AMP on the intracellular regulatory mechanisms of the interferon system.Part of the experiments reported in this paper have been performed at the Laboratory of Viral Diseases, NIAID, NIH, Bethesda, MD. The authors express their gratitude to Dr. S. Baron and Dr. H. B. Levy for their substantial help and criticism.

In vitro culture observations on neurinoma induced experimentally in the rat by ethylnitrosourea.

Abstract: Five neurinomas of the Vth cranial nerve, produced experimentally in rats by ethylnitrosourea, were cultivatedin vitro: they show a great resemblance with the human neurinomas. It must be emphasized that the resemblance is evident also in cultures of tumours which are characterized histologically by poor differentiation and by high invasiveness.

The neurohypophysis of the crested newt. II. Fine structure of the pars nervosa with special reference to ependymal cells.

Abstract: In the crested newt, the ultrastructural organization of the pars nervosa is analogous to that already known in non-mammal tetrapods. An orderly array of ependymal cells makes up the inner limiting layer while less abundant pituicytes are irregularly distributed within this organ. “Light” and “dark” pituicytes can be distinguished on the basis of the relative density of the cytoplasmic matrix and the distribution of the cell organelles. Both the ependymal cells and pituicytes are rich in dense bodies and possess extensive processes which ramify among the nerve fibers, often reaching the pericapillary space which they can line for long distances. The main components of the pars nervosa are nerve fibers and nerve terminals (type A), containing electron dense granules 1200–2000 A in diameter together with clear vesicles averaging 250–400 A. These fibers are likely to correspond to the aldehyde fuchsin positive neurosecretory fibers revealed by light microscopy. Differences in the granule size within the fibers and terminals lead to further recognition of two subgroups (A1 and A2). Other fibers and terminals (type B) containing clear vesicles and granular vesicles 600 to 1000 A in diameter, possibly of aminergic type, are also encountered. These fibers are rare and can be seen only in the portion of the pars nervosa near the pars intermedia of the adenohypophysis. Lastly, fibers and terminals containing only clear vesicles ranging from 250 to 400 A (type C) are occasionally found. Nerve endings are often formed by type A fibers on the perivascular space and on the perivascular processes of the ependymal cells and pituicytes. In agreement with recent findings available in the literature, the occurrence of synaptoid contacts between these terminals and both pituicytes and ependymal cells may confirm the active role of these cells in transport and release of neurosecretion.

Čerenkov light in (1011 ÷ 1012) eV EAS: Time dependence of the isophotes and multiple pulses

Abstract: We have calculated with a Monte Carlo method the radial and time dependence of the isophote diagrams for the Cerenkov light in (1011÷l012) eV E.A.S. A possible explanation for the Cerenkov pulse structure (rise time and width) observed with fast techniques is given.

Electron microscopical demonstration of sulphated mucopolysaccharides in mouse tracheal cartilage with a diaminobenzidine-osmium tetroxide technique.

Abstract: A diaminobenzidine-osmium tetroxide method for the demonstration of sulphated mucopolysaccharides has been tested at the electron microscopical level. The reaction (which involves treatment with diaminobenzidine in an acidic solution followed by oxidation with osmium tetroxide) has been carried out directly on ultra-thin sections of mouse tracheal cartilage embedded in water-soluble glycolmethacrylate. Sulphated mucopolysaccharides in the cartilage matrix were localized as a heavy, electron-dense precipitate. The method can be applied directly to sections, overcoming in this way the difficulties of penetration, and it seems to possess a higher specificity for sulphated mucopolysaccharides than that displayed by other techniques proposed previously for the ultrastructural demonstration of acid mucopolysaccharides.

Mass spectra of cobalt carbonyl complexes

Abstract: The mass spectra of the following acetylenic derivatives of Co2(CO)8 are reported: Co2(CO)6C2H2Co2(CO)6C 2,(CH3)2, Co2(CO)6 C2(CH2Cl)2, Co2(CO)6C2 (CF3)2, Co2(CO)2C2(C6H5)2 and Co2(CO)6C2(COOCH3)2. The effect of different C2RR′ on fragmentation modes is investigated. When R and R′ are aromatic groups, the major controlling factor is the stability of charged fragments; in other cases, it seems to be the loss of a stable neutral moiety. Transfer processes of alkoxylic groups are observed in Co2(CO)6C2(COOCH3)2, as well as in Co3(CO),9CCOOCH3, and Co3(CO)9CCOOC2H5. It is suggested that both cobalt and carbon atoms may be the migration sites.