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Biomedical subjects

M Rocco

Publications and source records attributed to M Rocco.

At least 73 records · Page 4Linked to original sources
PubMed1990

Auto-PEEP and dynamic hyperinflation in COPD patients during controlled mechanical ventilation and high frequency jet ventilation.

We investigated the levels of auto-PEEP and dynamic hyperinflation during high frequency jet ventilation (HFJV) and controlled mechanical ventilation (CMV) in six patients with chronic obstructive pulmonary disease within the first 36 h of acute exacerbation. The comparative evaluation was performed at similar conditions of gas exchange in HFJV and CMV: PaO2 77.6 +/- 11 mmHg vs 80.8 +/- 12 mmHg; PaCO2 46.8 +/- 2.5 mmHg vs 47 +/- 2.8 mmHg; pH 7.38 vs 7.38. In this situation, the values of auto-PEEP and dynamic hyperinflation, expressed as delta over the apneic functional residual capacity (FRC) did not differ: (auto-PEEPHFJV 8.9 +/- 3.8 cmH2O; auto-PEEPCMV 8.8 +/- 4.7 cmH2O; delta FRCHFJV 0.56 +/- 0.19 l; delta FRCCMV 0.54 +/- 0.2 l). This result suggests that, with a suitable machine setting and similar gas exchanges, HFJV produces the same level of auto-PEEP and dynamic hyperinflation as CMV in patients with chronic obstructive pulmonary disease.

Aged↗
PubMed1990

Oxygen tension monitoring in uremic patients during hemodialysis treatment.

The aim of this study was to evaluate the influence on cerebral and cutaneous vascular regions of PaO2 reduction during acetate dialysis, by monitoring conjunctival oxygen tension (PcjO2) and transcutaneous oxygen tension (PtcO2) during hemodialysis (HD) treatment. The study was performed on 23 patients with end-stage renal disease in chronic HD. All patients underwent dialytic treatment with cuprophan membranes and acetate containing dialysate. PcjO2 and PtcO2 were recorded and PaO2 and arterial carbon dioxide tension (PaCO2) were also measured. Results of the study show that hypoxemia during acetate dialysis with cuprophan membranes is not accompanied by changes of PcjO2 and therefore by changes in cerebral oxygenation. Moreover, PtcO2 remains constant during dialysis treatment. Furthermore, maintenance of normal oxygen tension at the conjunctival level is not obtained at the expense of the peripheral region of the skin.

Adult↗
PubMed1989

Interaction retinol-chromatin: an analysis of DNA from vitamin A-treated V79 Chinese hamster cells.

When V79 cells are incubated in the presence of radiolabeled retinol, a small but consistent amount of radioactivity remains associated with nuclear DNA. Chromatographic analysis of enzymatic hydrolysates of DNA shows that no irreversible changes, such as adducts, have taken place on DNA. We present evidence that this radioactive incorporation may occur via a metabolic conversion of retinol, leading mainly to the formation of radiolabeled thymidine, which is then incorporated into newly made DNA. Mutagenic effects by retinol, given at concentrations well above physiological levels, have been also excluded.

Animals↗
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

Parietal centripetal and centrifugal thickening neovascularization in the descending anterior coronary artery. Possible relations with the problem of collateral circulation.

Left coronary arteries of 30 human hearts, obtained at autopsy, were injected with contrast medium. A control group was formed from anterior descending coronary arteries free of atherosclerosis and a study group from anterior descending coronary arteries with areas of atherosclerotic injury. The following differences in the two groups were noted. The control group did not show successfully injected vessels in intima and media, while cases with atherosclerotic injury have them; the number of injected vessels in presence of atherosclerotic injury was three times greater than in healthy coronary arteries; there was a decreasing gradient from outside to in, in the number of injected vessels in both groups; and finally in atherosclerotic vessels we noted a lack of balance between parietal thickening and the residual lumen (conspicuous thickening was accompanied by a small reduction in the lumen). We interpret centrifugal thickening as a possible compensatory mechanism in the major branches for an inadequate canalization of vessel, and suggest possible formation, of coronary collateral circulation from vasa vasorum by a process of neovascularization.

Adult↗
PubMed1988

Remodeling of chromatin during male pronucleus formation in the sea urchin Tetrapygus niger.

After fertilization the cone shaped sperm nucleus is transformed into a spheroidal male pronucleus which fuses with the female pronucleus reestablishing the diploid genome. These morphological changes are correlated with biochemical transitions of sperm-specific chromosomal proteins. To obtain information on the rearrangements of chromosomal proteins after fertilization, we have followed sperm-specific nonhistones (Sp NHCP) and the sperm-specific histones (SpH) in zygotes harvested at different times post-insemination (p.i.). The acquisition of proteins synthesized de novo was determined during the time of male pronucleus formation, estimated to occur until 30 min p.i. The results obtained may be summarized as follows: 1. The fate of Sp NHCP, followed by Western blot analysis with polyclonal antibodies obtained in rabbits against the whole complement of Sp NHCP, indicates that the majority of Sp NHCP are lost shortly p.i., except two proteins of 58 Kd and 61 Kd that were not distinguishable from eggs NHCP because a crossreaction was obtained. Acidic proteins synthesized de novo were bound to chromatin between 3 and 30 min p.i., and the majority of these proteins comigrated with egg NHCP in SDS/PAGE. 2. The histones from sperm differ from their counterparts found in unfertilized eggs, both in their amino acid composition and their microheterogeneity in bidimensional gels. Sperm contain the five major SpH whereas eggs have seven major histone variants, distinct from each other, with an electrophoretic behaviour consistent with histones but a different amino acid composition. The total complement of histone variants found in zygotes collected at amphimixis is identical with that found in unfertilized eggs, suggesting that SpH should be lost before that time.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1987

Models of fibronectin.

The radius of gyration of human plasma fibronectin was determined by light scattering both under conditions in which the molecule is in an extended conformation (ionic strength 1.01 M, pH 8) and close to its native, more compact conformation (ionic strength 0.16 M, pH 8). These values were found to be 17.5 +/- 0.8 nm and 10.7 +/- 0.9 nm respectively, for a constant mol. wt of 533,000 +/- 8000, in excellent agreement with the value of 520,000 deduced from its known composition. A set of models, each made of two identical, end-to-end joined chains of 28 beads, was then constructed, and their calculated physico-chemical parameters were compared with those available for the whole fibronectin molecule and for some of its proteolytic fragments in both conformations. Two possible models for the circulating form are presented here: in both, the fibronectin molecule is in a compact, tangled conformation, with the amino-terminal end of one chain folded over to the carboxy end of itself or of the other chain either in a hairpin or in a circular fashion. With the exception of the carboxy-terminal fibrin(ogen)-binding domains, all the domains appear to be well exposed to the solvent, and thus free to interact with potential ligands.

Fibronectins↗
PubMed1986

Impairment of human polymorphonuclear leukocyte chemotaxis by 2,5-hexanedione.

The effect of n-hexane metabolites on human polymorphonuclear leukocyte chemotaxis and luminol-dependent chemiluminescence was investigated. No effect was detected when 2-hexanol, 2-hexanone and gamma-valerolactone were used; 2,5-hexanedione at 75 micrograms/ml inhibited chemotaxis and a direct correlation between increasing the xenobiotic concentration and the degree of inhibition was found. Chemotactic peptide-induced chemiluminescence was not affected by 2,5-hexanedione. In order to clarify the phenomenon, plasma membrane fluidity was investigated by fluorescence polarization of the fluorescent probe trimethylammonium diphenylhexatriene. 2,5-hexanedione increased the membrane fluidity, while the other n-hexane metabolites did not change the degree of fluorescence polarization. Results suggest that the cellular functions modulated by membrane-cytoskeletal organization are affected by 2,5-hexanedione also at the low concentrations.

Chemotaxis↗
PubMed1986

Acute water intoxication in healthy infants.

We have described two infants with profound hyponatremia and seizures due to metabolic derangements resulting from inappropriate feeding of large volumes of solute-poor liquids. All of the 23 similar cases in the current literature described children with normal renal and neurologic function before and after the episode of hyponatremia. The chronic feeding of solute-poor fluids in these infants impaired their ability to excrete free water, and continued feeding of solute-poor fluids resulted in progressive hyponatremia and convulsions. Upon reinstitution of normal sodium intake, all metabolic abnormalities disappeared.

Acute Disease↗
PubMed1986

Modifications of transcutaneous oxygen tension in lower limb peripheral arterial occlusive disease patients treated with spinal cord stimulation.

The current noninvasive techniques for investigating the response to epidural spinal cord stimulation in peripheral arterial occlusive disease patients are far from optimal. Transcutaneous oxygen tension measurements in these patients treated with spinal cord stimulation demonstrated a statistically significant increase during the stimulation and 30 min after the pacemaker has been switched off, suggesting the effectiveness of the spinal cord stimulation on cutaneous oxygenation. The transcutaneous oxygen tension measurements would represent in the future a reliable parameter to predict the effect and to modulate the pacemaker setting in peripheral arterial occlusive disease patients.

Aged↗