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Biomedical subjects

F Lombardi

Publications and source records attributed to F Lombardi.

At least 217 records · Page 12Linked to original sources
PubMed1976

Reflex sympathetic tachycardia during intravenous infusions in chronic spinal cats.

The reflex tachycardia elicited by rapid intravenous infusions of a blood substitute was studied in 21 chronic cats with spinal sections at C8. All animals could breath spontaneously. The day after section the average resting heart rate (HR) and arterial pressure (AP) were 109 beats/min and 98/67 mmHg, respectively. Vagal blockade with atropine (0.5-0.7 mg/kg iv) was performed prior to each infusion, increasing the average HR To 127 beats/min. In 39 infusions in 21 cats the average increase in HR was 10 beats/min (range from -6 to +22 beats/min). A tachycardia was observed in all but five trials, four of which were obtained in two cats that subsequently responded with a tachycardia. In seven animals the neural circuit mediating the response was partially or totally interrupted by section of several thoracic dorsal roots (T1-T4 or T1-T6) and of the spinal cord at the inferior level of these sections (between T6 and T7). The tachycardia response was progressively reduced and finally abolished by these procedures. These experiments indicate that spinal neural mechanisms are likely to contribute to the phenomenon first described by Bainbridge.

Animals↗
PubMed1976

Mechanical stimuli exciting type A atrial vagal receptors in the cat.

The activity of type A right atrial vagal receptors was recorded from the right cervical vagus in cats anesthetized with sodium pentobarbital, immobilized with gallamine, and with their chests open. Nerve impulses initiated by receptor activation were recorded simultaneously with instantaneous right atrial pressure and dimensional changes under various hemodynamic conditions. Atrial volume changes induced by infusion of saline, bleeding, and occlusion of the inferior vena cava did not alter consistently the systolic activity of the receptors. Electrical stimulation of the right stellate ganglion significantly increased the frequency of discharge during systole, whereas electrical stimulation of the left thoracic vagus significantly reduced the frequency of discharge. These inotropic interventions produced similar effects when the heart was paced at a fixed rate. Pacing the right atrial appendage increased the systolic discharge of the receptors only when at high rates the atrium contracted against closed atrioventricular valves. To investigate the influence of tonic efferent sympathetic activity on spontaneous receptor discharge, three receptors were studied before and after bilateral surgical stellectomy, and in cats with their chest closed three receptors were studied before and after infusion of propranolol. Both of these interventions markedly reduced the systolic activity. In addition to having effects on systolic activity, injection of saline, vagal stimulation, and sympathetic "denervation" always activated the receptors during filling. Our results indicate that: (1) the systolic discharge of type A receptors is a function of the active tension developed by atrial muscle during contraction; and (2) the pattern of discharge of the receptors during the atrial cycle depends on both the degree of atrial distention and the state and extent of contraction.

Animals↗
PubMed1975

Spinal sympathetic reflexes in the cat and the pathogenesis of arterial hypertension.

1. In vagotomized anaesthetized cats with both common carotid arteries occluded, stretch of the thoracic aorta induced reflex increases in arterial blood pressure, heart rate and left ventricular dP/dtmax. Similar responses were obtained in cats with spinal transection at the level of the first cervical nerve roots. 2. The hypothesis is advanced that sympathetic excitatory reflexes may contribute to the maintenance of hypertension through positive feedback.

Animals↗
PubMed1975

Response of type B atrial vagal receptors to changes in wall tension during atrial filling.

In anesthetized curarized cats with their chests open, we recorded the activity of type B right atrial vagal stretch receptors, right atrial pressure, and instantaneous dimensional changes of the right atrium. The nervous activity was analyzed during alterations in atrial dynamics produced by acute volume loading of the right atrium under control conditions and during sympathetic and vagal stimulations. Our results demonstrated that the mean frequency of discharge in the burst was dependent on the absolute tension and the rate of change in tension developed in atrial muscles during filling. The responses of different receptors to changes in atrial dynamics were qualitatively similar but characteristic for each receptor studied. In some experiments nervous activity was recorded after the cats had been killed: static and dynamic changes in atrial tension were then produced by injecting blood into the right atrium. Under these conditions dynamic stimuli always activated the receptors at tensions below the threshold for static stimuli. During dynamic stimuli the instantaneous firing rate was always higher than it was during static stimuli applied at the same level of tension. This study indicates that the nervous activity of type B atrial vagal receptors is closely dependent on static and dynamic changes in atrial wall tension.

Animals↗
PubMedDate not supplied

Serum antibodies against Coxsackie B1-6 viruses in type 1 diabetics.

Twenty-two newly diagnosed insulin-dependent diabetics and 46 control subjects have been examined for Coxsackie B1-6 serum antibodies. Evidence for CoxB4 neutralizing antibodies at titers greater than or equal to 16 and two seroconversions for this single virus type were shown in the diabetic group (31.8% of patients with titers greater than or equal to 16 in comparison with 10% of controls, p = 0.08). Reduced titers against CoxB2 and CoxB5 in diabetics were also observed. In agreement with the majority of publications, these data suggest the hypothesis that CoxB4 infections are frequently associated with type 1 diabetes, and the positive relationship found only for this type of virus may be related to greater tropism for the pancreas. The specificity of this viral infection, as shown by our serologic results, could suggest a possible causative role in the development of type 1 diabetes only in a limited number of cases. The authors propose new studies with monoclonal and IgM specific antibodies, obtained from new isolates, to detect more accurately the qualiquantitative differences between type 1 diabetics and controls.

Adolescent↗
PubMedDate not supplied

Comparative kinetics of oxiracetam in serum and CSF of patients with dementia of Alzheimer type.

The purpose of the study was to determine whether oxiracetam crosses the human blood-brain barrier and to evaluate its comparative kinetics in serum and in cerebro-spinal fluid (CSF). Six DAT patients, undergoing CSF collection for diagnostic purposes, received 2 g oxiracetam daily, by a 60 min i.v. infusion, for 7 days. On the last day, in four patients blood samples were collected at time 0, 30, 60 and 120 min, and lumbar drainage was performed at the end of infusion: at this time mean CSF concentration was 3.5 micrograms/ml, i.e. 4.0% of the serum one, demonstrating that oxiracetam crosses the blood-brain barrier. In two patients, blood samples were collected at time 0, 60, 120 and 240 min, and lumbar drainage was performed 60 min after the end of infusion: at this time mean CSF concentration was 2.8 micrograms/ml, i.e. 5.3% of the serum one, indicating a persistence of oxiracetam within this deep compartment. These results provide the first evidence in humans that oxiracetam penetrates the central nervous system and contribute to the understanding of its long-lasting pharmacodynamic effect in man.

Aged↗
PubMedDate not supplied

Nitrogen oxides from waste incineration: control by selective non-catalytic reduction.

An experimental study of the selective non-catalytic reduction (SNCR) process was carried out to determine the efficiency of NOx removal and NH3 mass balance, the NOx reducing reagent used. Experimental tests were conducted on a full-scale SNCR system installed in a hospital waste incineration plant. Anhydrous NH3 was injected at the boiler entrance for NOx removal. Ammonia was analyzed after each flue-gas treatment unit in order to establish its mass balance and NH3 slip in the stack gas was monitored as well. The effective fraction of NH3 for the thermal NOx reduction was calculated from measured values of injected and residual NH3. Results show that a NOx reduction efficiency in the range of 46.7-76.7% is possible at a NH3/NO molar ratio of 0.9-1.5. The fraction of NH3 used in NOx removal was found to decrease with rising NH3/NO molar ratio. The NH3 slip in the stack gas was very low, below permitted limits, even at the higher NH3 dosages used. No direct correlation was found between the NH3/NO molar ratio and the NH3 slip in the stack gas since the major part of the residual NH3 was converted into ammonium salts in the dry scrubbing reactor and subsequently collected in the fabric filter. Moreover, another fraction of NH3 was dissolved in the scrubbing liquor.

Journal Article↗
PubMedDate not supplied

[Cobalt therapy in the treatment of carcinoma of the oropharynx].

A clinical retrospective evaluation of 177 cases of carcinoma of the oropharynx treated with Cobalt therapy from 1959 to 1965 has been made. The analysis of long term results has shown that Cobalt therapy alone does not satisfactorily control carcinomas of oropharynx. In fact, less than 30% of the patients is still alive after 3 years. Survival is directly affected by the local extent of disease since, while the 5-year survival of T1 and T2 cases is respectively 26.8% and 21.5%, only 6.5% of patients with T3 carcinomas is still alive after 5 years. Particularly disappointing is the survival rate in cases with mono- or bilateral involvement of neck nodes, since none of these cases are alive 2 years after the initial therapy. In 69.4% of the cases, treatment failure has to be attributed to minimal response or early recurrence of primary tumor, while lymph node relapses have been observed in more than 25% of the cases. To allow a detailed clinical evaluation of the results, the different regions of the oropharynx should be considered separately, since differences in clinical evolution of various carcinomas would call for a different therapeutic approach. The results of this study in oropharyngeal carcinomas, indicate that improvement of long term results may only be obtained through a multidisciplinary therapeutic approach.

Cobalt Radioisotopes↗