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Biomedical subjects

G Conti

Publications and source records attributed to G Conti.

At least 181 records · Page 10Linked to original sources
PubMed1989

Pressure support ventilation (PSV) reverses hyperinflation induced isorhythmic A-V dissociation.

We report a case of hyperinflation induced isorythmic atrio-ventricular dissociation with circulatory failure in a patient with chronic obstructive pulmonary disease. The arrythmia was successfully treated by applying "pressure support ventilation" (PSV: 20 cmH2O) which, by decreasing the respiratory rate and increasing the expiratory time reduced the level of auto-PEEP. In order to explain this result the Authors recorded, in the same patient, the level of auto-PEEP and delta FRC obtained with Intermittent Positive Pressure Ventilation (IPPV), Intermittent Mandatory Ventilation (IMV) and PSV at the same gas exchange values. PSV showed a dramatic reduction of both these parameters. (Auto-PEEP: IPPV 12 cmH2O, IMV 17 cmH2O, PSV 7 cmH2O).

Aged↗
PubMed1989

A comparative study on ethanol and acetaldehyde as inducers of chromosome malsegregation in Aspergillus nidulans.

The activity of ethyl alcohol and acetaldehyde on mitotic chromosome segregation and conidial germination in Aspergillus nidulans was studied. Ethanol effectively induced malsegregation in a narrow range of concentrations (4.5-5.5%, v/v) and was inactive at doses which arrested conidial germination (above 6%). The same bell-shaped dose-response curve was shown by the spindle poison chloral hydrate, which was active in the range 6-10 mM. Acetaldehyde displayed a diphasic dose-response curve. Genetic analysis of induced segregants suggests that the disturbance of chromosome segregation is the primary genetic effect at low doses (0.025-0.037%), while at higher doses (above 0.1%), when growth was arrested, chromosome damage was primarily induced. The same pattern of segregants was produced by hydroquinone, a substance which indirectly affects chromosome segregation in A. nidulans. These differences in the genotoxic profiles of ethanol and acetaldehyde suggest that the effect exerted by ethanol on A. nidulans mitosis is not dependent on its conversion into acetaldehyde. In the absence of an effect of ethanol on in vitro polymerization of tubulin (actively inhibited by acetaldehyde at doses above 0.075%), a direct effect of ethanol on cell membranes is hypothesized. Comparison of the inhibition of growth and the effectiveness in aneuploidy induction displayed by ethanol, methanol, n-propanol and n-butanol demonstrates, in fact, a fair correlation with logP, a descriptor of lipophilicity related to the partitioning of compounds in biological membranes.

Acetaldehyde↗
PubMed1989

Human penile erection and organic impotence: normal histology and histopathology.

A very large amount of human material (7 embryos, 12 stillborns, 12 penes of males aged between 2 and 86 years, as well as bioptical material from 80 subjects affected by impotence problems) has been examined so as to study the penis arterial and venous walls, the blood flow regulation mechanisms and the intracavernal trabecular morphology. The amount of muscle tissue and of collagenous connective tissue has been numerically quantified by computer-assisted methods. This study enables the authors to underline three fundamental facts: (a) it confirms the normal penile erection mechanism, and the consequent theory, (b) it confirms that vascular sclerosis is a systemic phenomenon correlated to age, and that the penis is not exempt, and (c) in the case of impotence problems, the same sclerosis phenomenon may appear at an earlier age, and therefore induce pathological impotence.

Aging↗
PubMed1989

[Filmed evidence for locally changing pauses in the contraction of heart muscle fibrils in the chick embryo: a cell culture observation].

In studies of the pulsation of embryonic heart muscle cells in culture, pauses can be sometimes observed during which, for some seconds, all interconnected cells rest. This can be remarked in the whole field of vision. At once the pulsation starts again and, with unbroken force, the activity continues until the next pause. Such pauses in the heart function of warm-blooded animals would be lethal. However, in culture, the rests can be limited to only one fibril of the cell complex. In that case, the performance of the heart would be maintained. Rests can be observed in even only a few sarcomeres, if not one single sarcomere of fibrils of the striated heart muscle. The sarcomeres are alternately exempted from contraction and the shortening of the fibril by the contraction is practically not diminished. This mechanism could provide a mode of recovery for the ever pulsating heart. The phenomenon of sarcomerical release from fibril contraction could be made visible in the film by a 4-fold slowdown.

Animals↗
PubMed1988

High tumour prolactin receptor content and lack of increase in serum prolactin levels as predictors of good response to endocrine therapy in rat mammary cancer.

Correlations between anti-neoplastic activity of medroxyprogesterone acetate (MPA), on the one hand, and serum prolactin (PRL) levels as well as tumour PRL and insulin receptor content, on the other, were investigated in female rats bearing dimethylbenzanthracene (DMBA)-induced mammary tumours. Changes in liver PRL receptor concentrations were also studied. MPA was injected for 15 days. Regression was observed in 16 out of 50 (32%) tumours from rats treated with MPA. Twenty-seven out of 50 (54%) continued to grow regardless of treatment. Stasis was seen in the remaining 7 tumours (14%). Serum PRL levels increased significantly in rats with tumours which were non-responsive to MPA. Concentration of PRL receptors in the liver of all animals was reduced by MPA treatment. A remarkable increase occurred only in those mammary tumours which responded to therapy. The concentrations of PRL receptors in the tumours non-responsive to MPA were similar to those detected in control tumours. Unlike PRL receptors, tumour insulin receptor levels were not modified by MPA treatment. Five out of 14 tumours (35.7%), previously growing in spite of MPA administration, regressed when bromocriptine was added to MPA. A significant reduction in serum PRL levels occurred in all rats undergoing the latter treatment. No difference was observed between responsive and non-responsive animals; on the contrary, the PRL receptor content of responsive tumours increased significantly in comparison with that of non-responsive tumours.

Adenocarcinoma↗
PubMed1988

High frequency jet ventilation (HFJV) has no better haemodynamic tolerance than controlled mechanical ventilation (CMV) in cardiogenic shock.

Six patients with acute myocardial infarction (AMI) complicated by cardiogenic shock were studied in order to compare the haemodynamic tolerance of controlled mechanical ventilation (CMV) and high frequency jet ventilation (HFJV). The comparative analysis of the two techniques was performed with the same levels of PaO2 (CMV: 101 +/- 13 mmHg; HFJV: 104.2 +/- 14 p = ns); and PaCO2 (CMV: 37 +/- 1.7; HFJV: 35.7 +/- 1.4 p = ns). In this situation the values of mean airway pressure (Paw) did not differ significantly (CMV: 13 +/- 3 cm H2O; HFJV: 12.6 +/- 3.8 cm H2O) and no statistically significant difference in haemodynamic values was observed. These results demonstrate that in patients with cardiogenic shock, there is no difference between HFJV and CMV in terms of haemodynamic tolerance. Because of the more difficult clinical management of HFJV, this technique does not seem indicated as ventilatory support in patients with cardiogenic shock states.

Aged↗
PubMed1988

Induction of chromosome malsegregation by halogenated organic solvents in Aspergillus nidulans: unspecific or specific mechanism?

Three chloromethanes (dichloromethane, chloroform and carbon tetrachloride) and 8 chlorinated ethanes (1,1- and 1,2-dichloroethane, 1,1,1- and 1,1,2-trichloroethane, 1,1,1,2- and 1,1,2,2-tetrachloroethane, pentachloroethane and hexachloroethane) were assayed in tests for the induction of mitotic segregation in Aspergillus nidulans diploid strain P1. Eight of the 11 compounds assayed (dichloromethane, chloroform, carbon tetrachloride, 1,1- and 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1,2- and 1,1,2,2-tetrachloroethane) significantly increased the frequency of morphologically abnormal colonies which produced euploid whole-chromosome segregants (haploids and non-disjunctional diploids). Only in one case (1,1,1,2-tetrachloroethane) was a borderline increase in crossing-over frequency observed, thus suggesting the involvement of non-DNA targets in aneuploidy induction by these chlorinated hydrocarbons. Conclusive evidence for the induction of aneuploidy as the primary genetic event was provided by experiments in haploid strain 35 with 1,2-dichloroethane and 1,1,1,2-tetrachloroethane. Mutagenic, lethal and growth-arresting activities were quantitatively estimated and compared to a series of descriptors of physical and chemical properties of the molecules by means of multivariate statistical analysis. Lipophilicity, known to be related to c-mitotic activity, did not show any significant relationship with aneuploidizing activity, whereas a possible correlation among physico-chemical descriptors and toxic properties of test chemicals was highlighted.

Aneuploidy↗
PubMed1988

The morphological basis for the Polster theory of penile vascular regulation.

The discovery of the papaverine erection test by Virag in 1982 stimulated the interest of research workers in the physiology of the penis. Since then, the scheme of functioning proposed by Conti [Acta anat. 14:217-262, 1952] in 1952 has been frequently cited in the literature, although its finalism is evident. It is based upon the presence of regulatory mechanisms along penile arteries, veins and arteriovenous anastomoses. In spite of the fact that these anastomoses were unanimously admitted, recently the presence of arterial and venous cushions has been controverted or even denied. Before attempting any functional explanation using nerves and chemical mediators, we made sure first of the concrete material reality of these anatomical structures. Thirty-five years after the main study, the present observations confirm the morphologic descriptions made in 1952. The contrary would have been astonishing. In fact, arterial and venous cushions were demonstrated by the School of Anatomy of Padova, the most ancient and venerable of all (Fallope, 1550), then by other institutes of morphology that dealt with these cushions in practically all the organs of the human body. It remains to establish their role in erection - whether it is null, complementary or primordial: that is the question.

Adult↗
PubMed1988

Evaluation of the mutagenic activity of leucinostatins, a novel class of antibiotic peptides produced by Paecilomyces marquandii, in the modul Aspergillus nidulans.

Leucinostatins A, B, C, D, E, G, H, and K were thoroughly investigated for their genotoxic activity using the modul Aspergillus nidulans as the test organism. The results of assays for gene mutation (8-azaguanine resistance and methionine suppressors), gene conversion, mitotic crossing-over and mitotic aneuploidy induction suggest that these peptide antibiotics lack significant mutagenicity and that non-genotoxic mechanism(s) underlie their cytotoxic properties.

Anti-Bacterial Agents↗
PubMed1988

Latency of the auditory brainstem response (ABR) and head size. Evidence of the relationship by means of radiographic data.

The role of head size to determine the inter-subject variability of the auditory brainstem response (ABR) was investigated in 32 normally hearing adults (19 females, 13 males, aged 18 to 52). The ABRs were evaluated in respect to the absolute latency of waves I, III and V and the interpeak latencies I-III, III-V and I-V. Plain films of the skull (3 views) were also taken of each subject and several measures were calculated in order to obtain an evaluation of the dimensions of both the most rostral parts of the skull and of the posterior fossa. The radiographic data as well as the ABR parameters showed significantly shorter values in females than in males. There was a strong positive correlation between the two variables when a linear regression procedure was applyed. The highest value of the correlation coefficient (r = 0.8) was found in the relationship between the wave V latency and the posterior fossa measures. High r values and similar factors in the regression equation were also found after considering the subjects separately according to sex. These results show that the ABR latencies linearly increase together with the skull size as it appears in the X-rays, regardless of the subject's sex. We can consequently deduce that the length of the neural pathway is the main factor of inter-sex variability of the response.

Adult↗
PubMed1987

Clinical use of differential continuous positive airway pressure in the treatment of unilateral acute lung injury.

In some instances of unilateral acute lung injury (ALI) refractory to conventional ventilatory support, the intact lung is still able to ensure an efficient CO2 washout, the concomitant hypoxaemia being due to the loss of volume of the injured parenchyma. In these cases, the administration of a sufficient selective continuous distending pressure by means of differential continuous positive airway pressure may restore to normal the resting volume and thus the ventilatory performance of the affected lung, contemporarily avoiding the occurrence of pulmonary and systemic barotrauma.

Adult↗
PubMed1987

Inhibitory effect of diamidinophenylindole on the replication of influenza virus in permissive cellular hosts. Brief report.

The production of avian and human strains of influenza virus was altered to various extents by treatment of various host cells with 40 micrograms/ml of diamidinophenylindole (DAPI). In infected LLC-MK 2 cells only an abortive replication cycle occurred; in other cell lines there was partial inhibition or no inhibition of replication. Virus polypeptide synthesis in LLC-MK 2 cells was confined to the early pattern of viral multiplication; only the P proteins, the nucleoprotein NP, and the non-structural protein NS 1 were synthesized. The stage of replication mainly affected by DAPI was between the fourth and the sixth hour after infection. The mode of action of the drug and its modulating effect on virus production is discussed.

Animals↗
PubMed1987

On the mechanism of mitotic segregation induction in Aspergillus nidulans by benzene hydroxy metabolites.

The principal hydroxy-metabolites of benzene--hydroquinone, catechol and phenol--were assayed in tests for mitotic segregation induction in Aspergillus nidulans diploid strain 19. Hydroquinone was the most effective chemical, increasing the frequency of mitotic segregants up to 10-fold at 1-3 mM. Catechol was similarly active at 10-20 mM and phenol was weakly positive at 15 mM. Genetic characterization of induced abnormal segregating colonies by replating and complementary assays with haploid strain 35 suggest that gross chromosomal aberrations, instead of numerical abnormalities, are the primary genetic damages induced by hydroxybenzenes in A. nidulans. The protecting activity exerted by L-cysteine against equimolar concentrations of hydroquinone supports a free radical mechanism for hydroxybenzenes genotoxicity in A. nidulans.

Aspergillus nidulans↗