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Biomedical subjects

M Porta

Publications and source records attributed to M Porta.

At least 145 records · Page 8Linked to original sources
PubMed1989

[Results of long-term follow-up of patients with ureterosigmoidostomy].

The late results of ureterosigmoidostomy (US) have been known for many years; however, the incidence rates of second neoplasms that have been reported for the foregoing procedure are in disagreement with our own findings. A comprehensive review we had undertaken demonstrates that although it is a risk factor, its true incidence is much lower than that widely-accepted and published. Its very long latency period make it a currently valid surgical procedure in some adult conditions.

Colon, Sigmoid↗
PubMed1988

Lumbar myelography with iopamidol: a methodological approach to the investigation of side effects.

Pathophysiology of adverse reactions occurring during myelography with non-ionic contrast agents, such as iopamidol, seem related to their direct action on the nervous system. The authors try a multivariate approach, involving neurophysiological, neuropsychological and neurochemical parameters on a pilot group of twelve subjects. Any possible change in the above examinations is thoroughly analyzed and correlated to the postulated neurotoxic properties of contrast media.

Central Nervous System Diseases↗
PubMed1988

[Endothelium and its morphofunctional changes in the pathogenesis of diabetic microangiopathy].

Recent advances in our knowledge of endothelial function in health and in the presence of generalized microvascular damage, such as found in diabetic microangiopathy, are discussed in this review article. In microangiopathy there are no typical morphological signs of endothelial stress, apart from ubiquitous thickening of the basement membrane and the finding of both hyper- and acellular capillaries, whereas important derangements of endothelial function may occur in the early stages of the disease, like accelerated turnover, intracellular accumulation of potentially toxic intermediate metabolites, hyperpermeability of the vessel wall, altered synthesis of some haemostatic factors, expression of angiogenetic potentialities in inappropriate situations. The possible pathogenetic mechanisms underlying such alterations are reviewed, with special emphasis on the shortcomings of the experimental models available for laboratory investigation and on the in vivo situation.

Animals↗
PubMed1988

High glucose concentrations inhibit DNA synthesis and replication without causing death or impairing injury repair in cultured human endothelial cells.

Endothelial cells are directly exposed to the metabolic derangements of diabetes mellitus and may be damaged early, if not primitively, in the pathogenesis of diabetic microangiopathy. Cultured human umbilical vein endothelial cells were subjected to equimolar concentrations of glucose or mannitol for the evaluation of 3H-thymidine uptake, cell replication, cell death and repair of standard mechanical lesions. 3H-thymidine uptake was inhibited dose-dependently and to a similar extent by both glucose and mannitol. The former reduced cell replication whereas the latter did not (p less than 0.01 at 27.8 mmol/l, p less than 0.001 at 50.0 mmol/l). Neither caused excess cell death nor interfered with lesion repair. These results suggest that supra-physiological amounts of glucose inhibit DNA synthesis with osmotic mechanisms, delay cell replication through at least partially non osmotic effects, do not cause excess cell death and do not impair local injury repair. The above effects may play a role in the pathogenesis of long-term complications of diabetes.

Cell Count↗
PubMed1988

Poverty, health services, and health status in rural America.

Access to health services for everyone has been a major policy goal in the United States: inequitable access is assumed to lead to inequitable health status, particularly for low-income groups. A sophisticated model of the relation between poverty, health care needs, service use, and health outcomes is used to analyze cross-sectional data on 7,823 adults from 36 rural communities. Improved access and use are helpful, but evidence clearly indicates that combined health and social initiatives will be necessary to reduce inequalities in health status.

Cross-Sectional Studies↗
PubMed1987

Intracellular Ca2+ concentration and the antidiuretic hormone-induced increase in water permeability: effects of ionophore A23187 and quinidine.

The hydroosmotic responses induced by oxytocin and 8-bromo-cyclic AMP, in frog and toad urinary bladders, were recorded minute by minute. 3HHO and 45Ca unidirectional fluxes as well as prostaglandin B2 liberation were also measured. It was observed that: (1) Addition of the calcium ionophore A23187 or quinidine to the serosal bath inhibited the response to oxytocin, but not to 8-bromo-cyclic AMP, while increasing prostaglandin E1 liberation into the serosal but not into the mucosal bath. (2) Addition of A23187 to the mucosal bath induced a transient and temperature-dependent inhibition of the response elicited by 8-bromo-cyclic AMP. The time-course of this reduction in water permeability and its sensitivity to medium temperature were similar to those observed after the withdrawal of agonist, but clearly different of those observed after intracellular acidification. (3) The hydroosmotic response was also transitorily inhibited when the Ca2+ concentration was step-changed in the mucosal bath. (4) When added to the mucosal or to the serosal baths, the ionophore increased either the apical or the laterobasal Ca2+ permeabilities. It is concluded that manipulation of intracellular Ca2+ interferes with the hydroosmotic response at two different levels. (1) A first target point located 'pre-cyclic-AMP production'. This effect would be mediated by prostaglandin liberation. (2) A second target point located after cyclic AMP production and before the 'temperature-dependent rate-limiting step'. This effect is probably related to the mechanism controlling the insertion and removal of water channels.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1987

Initial treatment of thyrotoxic Graves' disease with methimazole: a randomized trial comparing different dosages.

We evaluated the efficacy of different doses of methimazole (MMI) as the initial therapy for Graves' disease. Fourteen patients were treated with 15 mg/die of the drug (group A) and 14 with 30 mg/die (group B). Blood samples for T3, T4, FT3 and FT4 were obtained before beginning therapy, every 48 h during the first 12 days and on the 45th day of treatment. All these hormonal parameters fell significantly from the 2nd day of therapy in both groups. All the patients, except for one in group B, had normal or subnormal levels of thyroidal hormones on the 45th day of treatment. The comparison between the two groups of regression coefficients over the first 12 days showed no significant differences. The absolute decrease of each examined parameter on day 12 was positively correlated with the relevant pretreatment value. These results demonstrate that doses of MMI (15 mg/die) much lower than those commonly recommended are able to rapidly control thyroidal overproduction as effectively as 30 mg/die.

Adult↗
PubMed1987

Levels of serum angiotensin-converting enzyme before and after forearm venous stasis in diabetic microangiopathy.

The levels of angiotensin-converting enzyme and Factor VIII-related antigen, 2 endothelial synthesized glycoproteins, were measured in basal conditions and after forearm venous stasis in 12 healthy controls and 12 patients with diabetic microangiopathy. Angiotensin-converting enzyme levels were similar in the controls and in the patients both basally (185 +/- 17 nm/ml/min (SEM) and 192 +/- 15, respectively) and after stasis (238 +/- 17 and 220 +/- 15), whereas Factor VIII-related antigen was lower in the former basally (101 +/- 13% vs 184 +/- 16%, p less than 0.001) and after stasis (140 +/- 21% and 243 +/- 21%, p less than 0.01). It is concluded that Factor VIII-related antigen is a more sensitive indicator of endothelial cell damage in diabetic microangiopathy than angiotensin-converting enzyme.

Antigens↗
PubMed1986

[Lactic acidosis].

Lactic acidosis is a metabolic disturbance characterized by an increase of the production/clearance ratio of lactate. Lactate is a catabolite of glycolysis when this takes place under anaerobic conditions. Clinically LA is characterized by: signs of acidosis, venous blood lactate greater than 5 mMol/l, arterial pH less than 7.25. LA is classified in type A, due to shock, and type B which, in turn, can be divided according to its pathogenesis in B1 correlated to particular pathologies, B2 due to exogenous substances and B3 caused by congenital metabolic diseases. LA is of particular interest in type II diabetes mellitus treated by phenformin. Current therapeutic directions, although suboptimal, are: to eliminate the causes of lactate hyperproduction by maintaining a sufficient efficiency of the cardio-vascular apparatus, to correct acidosis by using alkalinizing solutions, to remove pharmacologically or by dialysis the excess of lactate.

Acidosis↗
PubMed1986

A study of the possible interactions between human platelets and the antibiotic MDL-507 (teicoplanin).

Teicoplanin, a new glycopeptide antibiotic, was tested for its ability to induce agglutination and/or aggregation of fresh and fixed human platelets in vitro. Two chemically related substances, ristocetin and vancomycin, were used as controls in the same experimental conditions, as they are known to be active and, respectively, nonactive on platelets. The studies with fresh platelet rich plasma (PRP) taken from 10 healthy volunteers and the studies with fixed washed platelets (FWP) were carried out at the final concentrations of teicoplanin and vancomycin of 10, 100, 2000 and 5000 mg/l. Unlike ristocetin, teicoplanin did not exhibit any agglutinating or aggregating activity, even when tested for concentrations 50 times as high as those measured in vivo during the peak time. At high concentrations it induced protein precipitation, albeit to a lesser extent than vancomycin.

Adult↗
PubMed1986

Follow-up study of pseudoephedrine users.

A follow-up study of over 100,000 persons below age 65 years who filled a total of 243,286 prescriptions for pseudoephedrine indicated that there were no hospitalizations among users that could be attributed to the drug. There were no admissions within 15 days of filling a prescription for pseudoephedrine for cerebral hemorrhage, thrombotic stroke, or hypertensive crisis. There were a small number of hospitalizations for myocardial infarction, seizures and neuropsychiatric disorders, but the rate of such admissions among the pseudoephedrine users was close to the expected rate in the population at large.

Adolescent↗