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Biomedical subjects

G Raimondi

Publications and source records attributed to G Raimondi.

70 records · Page 4Linked to original sources
PubMed1981

[Comparative study of cardiocirculatory response and respiratory reflex to the injection of bradykinin, inorganic phosphates and prostaglandins into the femoral artery].

In 15 anesthetized rabbits the reflex changes in arterial pressure, heart rate and respiratory rate in response to injections of bradykinin inorganic phosphate and prostaglandins into femoral artery have been studied. Intraarterial injection of bradykinin produced a reflex fall in arterial pressure, bradycardia and tachypnea. The latency of response ranged from 6 to 7 sec. The threshold dose was about 50 ng. This effect was accompanied by a consistent increase in the afferent discharge in the saphenus nerve. Isotonic mixtures of Na2HPO4 and NaH2PO4 at pH 7, PGE1, PGE2, and PGA, when injected into femoral artery even in high doses, failed to produce any significant cardiocirculatory or respiratory reflex responses. Infusion of PGE1 (1 ug/min) into femoral artery, although inactive by itself, enhanced the reflex effect of bradykinin.

Animals↗
PubMed1981

Cardiovascular and respiratory reflexes from muscles during dynamic and static exercise.

In anesthetized and deafferented rabbits, rhythmic and static contractions of the hindlimb muscles were elicited by stimulating the femoral nerve at 3 and 100 Hz with the intensity of 2.0-2.5 times threshold for the motor fibers. Rhythmic contractions caused a decrease in systemic blood pressure, heart rate, and vascular resistance of the resting hindlimb with hyperpnea. Tetanic contractions caused a rise in arterial pressure, in vascular resistance of the nonexercising hindlimb, and in pulmonary ventilation with small increases in heart rate. These responses were not obtained after sectioning the somatic nerves of the exercised limb or when the cut central end of the femoral nerve or the intact nerve in curarized animals was stimulated with the same intensity of 2.0-2.5 times the motor threshold. Both depressor and pressor responses were, therefore, reflexes initiated in the contracting limbs. Removal of the skin from the exercising limb did not change the typical patterns of response. The most likely source of the observed reflexes is that from receptors activated by metabolites released in the exercising muscles.

Animals↗
PubMed1979

Cardiovascular and respiratory chemoreflexes from the hindlimb sensory receptors evoked by intra-arterial injection of bradykinin and other chemical agents in the rabbit.

Intra-arterial injections of bradykinin into the hindlimb of the rabbit cause two types of cardiovascular reflex effects displayed in succession. The first-type effects appear early and are of inhibitory nature, being represented by systemic hypotension, contralateral hindlimb vasodilation and bradycardia; the second-type effects appear later and are excitatory in nature, consisting of hypertension, hindlimb vasoconstriction and tachycardia and occur closely associated with behavioral manifestations typical of the reaction to pain. Both the depressor and pressor effects are accompanied by hyperventilation. Analogous biphasic reflex responses may be caused by intraarterial injections of potassium ions. On the contrary, hypertonic solutions (NaCl, glucose) usually only produce second-type excitatory responses. No significant cardiocirculatory reflex effects are induced by even high doses of serotonin, nicotine, adenosine, adenosine triphosphate, adrenalin, noradrenalin, angiotensin, vasopressin and oxytocin. General anesthesia greatly inhibits the pressor reflexes and potentiates the depressor responses (to bradykinin and K ions) but does not appear to be a necessary condition for provoking depressor reflexes by chemical stimulation of somatic afferents. Both chemoreflex responses are prevented by sectioning the somatic nerves of the injected limb. Denervation of sinoaortic areas and of cardiopulmonary receptors by bilateral cervical vagotomy or complete removal of the skin from the injected limb does not prevent either type of chemoreflex response. These depressor and pressor chemoreflexes have been ascribed to activation of two functionally distinct types of sensory receptors in the skeletal muscle, differently sensitive to chemical substances and selectively concerned with different patterns of cardiocirculatory reflex response.

Animals↗
PubMedDate not supplied

Difficult diagnosis of infliximab-related miliary tuberculosis.

The use of Infliximab in the treatment of patients with rheumatoid diseases unresponsive to conventional therapies has been reported to be complicated by opportunistic infections. We report the case of a 56-yr old female rheumatoid arthritis patient complaining of fever and respiratory symptoms 9 months after commencing Infliximab, who received no ethiologic diagnosis for the six months before admission. Tuberculosis was suspected upon chest radiographic pictures and empirical treatment for miliary tuberculosis instated in the wake of microbiological confirmation. The case typifies the difficulties of diagnosing miliary tuberculosis in the immunocompromised as well as in the immunocompetent patient.

Antibodies, Monoclonal↗
PubMedDate not supplied

[Atrial natriuretic factor and pulmonary function].

The aim of this review is to provide a critical and concise discussion of present knowledge on the role of atrial natriuretic factor (ANF) in physiological as well as pathological pulmonary conditions. The lung contributes only to a small extent to the production of circulating ANF; on the other hand, the lung represents the major degrading site of the protein. Plasmatic ANF concentration increment during lung disease may therefore be due to a reduction in ANF plasma removal enzyme rather than to increased ANF production. Lung tissue shows more ANF receptor sites than any other organ. The effect of ANF on bronchial and pulmonary artery muscle lining is particularly evident. In fact ANF administration in asthmatic patients leads to bronchodilation comparable to dilation induced by salbutamol. Furthermore, elevated levels of circulating ANF seem to influence fluid redistribution through alveolar-capillary membrane leading to protein mobilization through the alveolar space. On the contrary, in the cardiomyopathic hamster ANF induces relevant guanylate cyclase activation before the animal has developed hemodynamic changes. Guanylate-cyclase activation may protect the lung through counteracting pulmonary edema formation, as shown by fluid reduction in alveolar spaces following pneumotoxic agents administration. This effect seems independent of natriuretic and hypotensive ANF effects.

Animals↗
PubMedDate not supplied

Cardiorespiratory effects evoked by electrical stimulation of somatic afferent fibers.

Several neurophysiological studies have shown that electrical activation of afferent fibers of somatic nerves can evoke inhibitory or excitatory cardiovascular responses. The present investigation was undertaken to examine the effects induced by electrical stimulation of somatic nerves on cardiocirculatory and respiratory functions in anesthetized rabbits. Both low frequency stimulation and high frequency stimulation of afferent fibers of somatic nerves caused two distinct patterns of cardiocirculatory and respiratory reflex responses absolutely similar to those observed in our previous experiments on rabbits with dynamic and static exercise. The present findings do not support the existence in the somatic nerves of afferent fibers with cardiorespiratory effect having physiological functions different from that of producing cardiopulmonary adjustments to muscular activity.

Afferent Pathways↗
PubMedDate not supplied

[Biology and space medicine. New prospects for internal medicine].

Most of the functional problems astronauts may suffer during and after long-term space missions are mainly associated with the reduction of the gravity force which causes a central fluid shift and a redistribution of the blood flow. Blood volume centralization induces a rapid increase in diuresis with elimination of consistent amounts of water and electrolytes which leads to a reduction of cardiac output, body fluid and to a hypodynamic state of the cardiovascular system. The effects of micro-gravity on skeletal and muscular systems are quite severe causing rapid bone demineralization, especially in the spine and lower extremities, and hypotrophy of the muscular masses. Micro-g also appears to determine cellular and molecular modifications with inhibition of the immune system, hematopoiesis and resistance to infections. Orthostatic intolerance, with feeling sick, instability and sometimes syncope, is characteristically observed after the return to earth due to a remarkable fluid shift in the lower part of the body and an acute reduction in blood flow to the brain. Physical exercise may play an important role among the countermeasures proposed to reduce most of the cardiovascular and musculo-skeletal effects of micro-g. Furthermore, micro-g offers many interesting prospects for the development of new technologies for the synthesis of biologically active substances for pharmacological use. Further severe limiting factors, for more prolonged manned space missions, are the so called "human factors" including psycho-emotional and social behaviour, especially regarding the future of astronauts after their return to earth.

Aerospace Medicine↗
PubMedDate not supplied

[Multiplanar computerized angiotomography in the evaluation of aneurysms of the posterior inferior cerebellar artery].

Two cases of posterior inferior cerebellar artery aneurysms are reported. The diagnosis was made by dynamic multiplanar computerized tomography and afterwards confirmed by angiography and surgery. The role of CT in the diagnosis and follow-up of subarachnoid hemorrhage is discussed. Intracranial posterior fossa aneurysms are nicely demonstrated and localized by dynamic multiplanar CT.

Aged↗