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Biomedical subjects

P Longoni

Publications and source records attributed to P Longoni.

14 recordsLinked to original sources
PubMed1991

Altered pattern of circadian neural control of heart period in mild hypertension.

We addressed the problem of the circadian changes in neural control of heart period in ambulant hypertensive subjects. A running spectral analysis of R-R variability from Holter tapes provided markers of sympathetic, i.e. low-frequency component (LF) almost equal to 0.10 Hz, and vagal, i.e. high-frequency component (HF) almost equal to 0.25 Hz, controlling activities for the 24-h period of the recording. Significant circadian differences were observed in LF between the two groups of subjects: during night-time rest (0300-0400 h), LF was greater in hypertensives than in normotensives (56 +/- 2 and 48 +/- 2 nu, respectively; P less than 0.05). Furthermore, the difference between daytime and night-time LF values was progressively reduced with increasing severity of the hypertensive state, as assessed by resting arterial pressure levels. Spectral analysis of R-R variability suggests that essential hypertension may be characterized by a reduced day-night oscillation in sympathetic activity than can be quantified non-invasively using this approach.

Adult↗
PubMed1984

[Changes induced by dimethylformamide on platelet function and coagulation activity].

The effect of Dimethylformamide on platelet function and on clotting system has been studied on eight workers exposed to the product, widely used in industry as a solvent of acrylic resins. A significant reduction of the number of the platelets and a drawing out of PTT and PT has been noticed. Such informations has been explained as chronical peripheral use or as modification of phospholipid components induced by DMF instead of synthesis defect, as no significant variation of the fibrinogen and of AT III values, proteins synthetized by liver, has been observed. The platelet aggregation has pointed out, in vivo, a reduction of ADP aggregation in the exposed subjects; in vitro, increasing quantities have determined an increasing reduction of the primary ADP and adrenaline aggregation.

Adult↗
PubMed1984

[Platelet aggregation and resistance to osmotic shock of platelet concentrates obtained by discontinuous-flow cell separation with the surge pump technic].

We studied the ultrastructural morphology and function of platelets collected by apheresis procedure with discontinuous flow using the Surge Pump Technique. The platelet concentrates obtained by this technique are free of erythrocyte and lymphocyte contamination. The platelet morphology as well as the platelet aggregation induced by ADP, adrenaline and collagen of platelet concentrates were similar to those observed in PRP before the apheresis. The response to the hypotonic shock of platelet concentrates was also normal, indicating membrane integrity and good platelet metabolism. These results show that platelet concentrates obtained by the Surge Pump Technique maintain their haemostatic effects and may be infused in thrombocitopenic patients, reducing the risk of alloimmunization related to the presence of erythrocytes and lymphocytes.

Adenosine Diphosphate↗
PubMed1983

Identification of a streptococcal penicillin-binding protein that reacts very slowly with penicillin.

Penicillin-binding protein (PBP) 5 of Streptococcus faecium ATCC 9790 has an unusually low affinity for penicillin (50% binding occurred at a penicillin level of 8 micrograms/ml after 60 min of incubation, and the protein only became labeled after 20 min of incubation with high concentrations of radioactive penicillin). PBPs with similar properties are carried by strains of Streptococcus durans, Streptococcus faecalis, and Streptococcus lactis but not by strains of groups A, B, C, and G streptococci or Streptococcus pneumoniae. The strains carrying the slow-reacting PBP demonstrated a sensitivity to penicillin that was several hundred times lower than that of strains not carrying it. Spontaneous mutants with minimal inhibitory concentrations of penicillin of 20, 40, and 80 micrograms/ml were isolated from S. faecium ATCC 9790. They all showed a dramatic increase in the amount of slow-reacting PBP produced. Mutants with increased penicillin resistance were also isolated from wild-type strains of S. durans, S. faecalis, and S. faecium. All of them carried a greater amount of the slow-reacting PBP than that carried by the parent. Finally, it was found that resistant S. faecium ATCC 9790 mutants grew normally in the presence of penicillin concentrations that were far above that saturating all PBPs except PBP 5. Cell growth was, on the contrary, inhibited by a penicillin concentration that saturated the slow-reacting PBP by 90%. This penicillin dose was equal to the minimal inhibitory concentration.

Bacterial Proteins↗
PubMedDate not supplied

Effects of dimethylformamide (DMF) on coagulation and platelet activity.

The effects of dimethylformamide (DMF) on hemostatic functions, especially on platelet activity, were examined both in vitro and in vivo in 15 workers exposed to DMF (27 mg/m3, median value). Twenty-eight control subjects who were not exposed to DMF, but comparable for age, anthropometric data, and smoking habits, were also studied. Workers exposed to DMF showed a decrease in the number of platelets and had longer coagulation times, probably due to a change caused by DMF on the membrane receptor of platelets and on the phospholipid components of the clotting system.

Adenosine Diphosphate↗