Search PubMed⌕ Search

Biomedical subjects

G Macchi

Publications and source records attributed to G Macchi.

At least 55 records · Page 3Linked to original sources
PubMed1989

Experimental allergic encephalomyelitis in guinea pig: variability of response to intradermal emulsion injection.

Different forms of experimental allergic encephalomyelitis were obtained in 4 groups of guinea pigs: 7 adult Hartley guinea pigs (Group I), 12 adults of the same strain (Group II), 6 juvenile strain 2 guinea pigs (Group III) and 6 juvenile strain 13 animals (Group IV), by the injection of emulsions. Groups I and II received emulsions containing 250 mg and 500 mg respectively of fresh isologous spinal cord tissue, complete Freund adjuvant (CFA) and saline solution while Groups III and IV received an emulsion containing 120 mg of isologous spinal cord, CFA, saline solution and 15 mg of Mycobacterium tuberculosis. The increased antigen load induced a disease with delayed onset and prolonged progressive course (C-P-EAE) in Groups I and II, although 8 animals showed no symptoms of illness. The findings in C-P-EAE were large demyelinated plaques, perivenous fibrosis and large areas of infiltration. Demyelinated areas occurred within the spinal cord white matter only in two asymptomatic animals. C-P-EAE was obtained in 4 of the Strain 2 animals. In conclusion, the increased antigen load induced a range of lesions in Hartley guinea pigs, although not all animals were affected. C-P-EAE was induced also in strains of guinea pig other than the Heartley strain. These different reactions may have been the outcome of partial or complete inactivation of the cell-mediated response to the inoculated antigens.

Acute Disease↗
PubMed1988

A retrospective study of Creutzfeldt-Jakob disease in Italy (1972-1986).

In a retrospective study of Creutzfeldt-Jakob disease (CJD) in Italy from 1972 to 1986, we found 79 cases which fulfilled the diagnostic criteria for CJD. The annual mortality rate was 0.09 cases per million inhabitants. In this series the female to male ratio was 2.59, a value significantly higher than that found in Italian population (1.05). The mean age at death was 62.1 +/- 9.4 years and the mean duration of the disease was 5.3 +/- 3.0 months. No familial cases of CJD were found in our series. Mental deterioration was present in all of our cases, myoclonus in 85% and the other clinical signs were present at a lower rate. Periodic EEG activity was found in 92% of the cases. Two patients had had neurological or ophthalmic surgery and 17% of our cases had undergone general surgery within 5 years prior to the clinical onset of CJD.

Adult↗
PubMed1987

Human renovascular effects of dopexamine hydrochloride: a novel agonist of peripheral dopamine and beta 2-adreno-receptors.

The effects of dopexamine on the renal circulation have been examined to show whether any augmentation of renal blood flow (RBF) was secondary to the effect of the drug on cardiac output (CO) or whether it had any additional direct renal vasodilator activity. Eight male patients with mild to moderate hypertension, who were undergoing renal vein catheterization for renin estimation, were studied. Dose related increments in RBF (baseline (B) = 504 ml X min-1; after treatment (D) = 605 ml X min-1), CO (B = 5.9 l X min-1; D = 6.7 l X min-1), heart rate (B = 77 beats/min; D = 100 beats/min) and systolic blood pressure (B = 143 mmHg; D = 166 mmHg) were observed on administration of dopexamine 3 micrograms X kg-1 X min-1, with insignificant changes in diastolic blood pressure (B = 84.4 mmHg; D = 90 mmHg) and total peripheral resistance (B = 17.85; D = 17.25 Units). There was a slight but significant reduction in renal vascular resistance (B = 20.59, D = 18.75). The ratio of RBF to CO (%) confirmed that the increase in RBF due to dopexamine hydrochloride was greater that attributable to the increase in CO or perfusion pressure alone (RBF/CO B = 8.5%, D = 9%), consistent with selective renal vasodilatation. The fall in renin activity and lack of systemic vasodilatation suggest that this was a DA1-receptor mediated effect.

Adrenergic beta-Agonists↗
PubMed1987

[Long-term effects of competitive sport activity on the heart of professional ex-athletes].

Cardiac adaptation due to sport activity are usually interpreted as physiological process induced by cardiac overload during vigorous and continued muscle activity. The aim of this work was to evaluate long term cardiac effects of competitive sport activity performed in youth, after retirement. In particular we investigated: 1) whether cardiac adaptations to exercise are reversible and 2) whether or not previous competitive activity affects the cardiac ageing process or modifies ventricular function. We studied 23 professional retired athletes (PRA): 16 football players and 7 boxers, aged 40-60, who had been active in their sports for 16 years mean and who completely interrupted training and competition for at least 10 years. Our evaluation consisted of a questionnaire, a clinical assessment, an electro- and echocardiographic examination at rest. Data obtained in PRA were compared with those of twenty subjects matched for sex, age and weight who had never been athletes (control group = C) (Tab. I). We found: left ventricular hypertrophy in 5 cases (according to the "Point Score System" electrocardiographic evaluation): tall T waves in the precordial leads in 4 and conduction defects in other 4 cases. One subject had evidence of ischemic heart disease. Eleven cases were normal (Tab. II). Echocardiographic data demonstrated concentric heart hypertrophy and depressed ventricular function in PRA. Cardiac mass calculations were significantly higher in PRA with respect to C, more so for wall thickening than for cavitary enlargement. We concluded that: 1) cardiac adaptation due to physical exercise are not completely reversible and 2) systolic ventricular work, evaluated by means echocardiographic indices (EF, CSF and CSR) is depressed in PRA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Spinal afferents and cortical efferents of the anterior intralaminar nuclei: an anterograde-retrograde tracing study.

The topographical relations among the terminal field of spinothalamic fibers and the cells projecting upon areas 4 and 5 were studied in the anterior intralaminar nuclei of the cat. Terminals anterogradely labeled from the spinal cord and cell populations retrogradely labeled from the lateral pericruciate and anterior suprasylvian cortex were simultaneously observed by means of a multiple fluorescent tracing strategy. The present findings confirm that spinal afferents in the central lateral and paracentral nuclei overlap with the cells projecting to area 4. Further, the present data demonstrate that spinal terminals are largely segregated from the intralaminar cell population projecting to area 5.

Animals↗
PubMed1986

Multiple cortical targets of one thalamic nucleus: the projections of the ventral medial nucleus in the cat studied with retrograde tracers.

The organization of the cortical projections of the ventral medial thalamic nucleus (VM) was studied in the cat with retrograde tracers. The extent of the VM-cortical projections was first investigated with horseradish peroxidase injected in different cortical fields. The results obtained in the experiments indicated that the main target of VM efferents is represented by a large territory anterior to the cruciate sulcus involving area 6 and the gyrus proreus and extending into the anterior part of the medial cortical surface. The afferents to these precruciate fields arise from throughout the VM. In addition, the lateral third of VM projects upon the lateral precruciate cortex that is coextensive with the precruciate part of area 4, whereas VM efferents do not extend into the posterior sigmoid gyrus. A second major target of VM efferents is represented by the insular cortex in the anterior sylvian gyrus. VM projections also reach the prepyriform cortex and the cingulate gyrus. An anteroposterior decrease of density was found in the VM-cingulate projections. Sparse VM projections reach the temporal cortex, the adjacent posterior sylvian and ectosylvian fields, and the anterior ectosylvian gyrus. No VM projections were found either upon the visual areas 17 and 18 or upon the primary auditory cortex. The interrelations between some VM-cortical cell populations and their divergent collateralization were studied by using double retrograde labeling with fluorescent tracers. The results of these experiments demonstrated that a relatively high number (at least 20%) of VM cells projecting to the insula are also connected to the precruciate fields by means of axon collaterals. This finding indicates that VM is a highly collateralized structure of the cat's thalamus. Very few branched cells were found in the other combinations of cortical fields here examined (precruciate vs. posterior sylvian fields, lateral precruciate vs. proreal cortex, anterior vs. posterior cingulate fields). Altogether these data indicate that VM branched cells preferentially interconnect the two main cortical targets of the nucleus, i.e., precruciate and insular fields. The results of the present study are discussed in regard to the literature on the VM projections in the rat and the previously available data in the cat, to the afferent VM organization in the cat, to the relationships between VM and the nucleus submedius, and to the anatomical and functional role of VM in relation to the so-called "nonspecific" thalamocortical system.

Animals↗
PubMed1986

[The organization of thalamic connections].

Connections ascending to the thalamus. Contrary to classical opinion, all thalamic nuclei receive extrathalamic afferents. Segregation or convergence within a topographically defined nucleus represent two modalities of thalamic afferents. In addition, certain topographically organized thalamic afferents possess "privileged" or primary "targets" in the thalamic nucleus while others possess supplementary "targets" in other thalamic nuclei (see cerebellar, pallidal and spinothalamic projections). Ascending connections from several brain stem structures can converge on the same nucleus or diverge to several thalamic nuclei. Thalamic connections with the telencephalon. Methods for determining axonal transport have demonstrated that all thalamic nuclei, with the exception of the reticular nucleus and the ventral part of the lateral geniculate body, project towards the cerebral cortex. Four nuclear complexes can be recognized in the cat as a function of the different modalities of localization, concentration and lamination of the projections towards the cortex and the central grey nuclei. In general, the thalamocortical connections have reciprocal ipsilateral corticothalamic projections originating in the infragranular layers of the cerebral cortex. The reticular nucleus and the ventral part of the lateral geniculate body, which is not projected to the cerebral cortex, are exceptions. Each cortical area receives a "privileged" connection from a thalamic nucleus and a supplementary connection- from one or several other thalamic nuclei. The "privileged" connections usually pass to the fourth and third layers of the neocortex, and sometimes also to the first layer. In contrast, the supplementary connections pass to different superficial or deep cortical layers. Each nucleus is formed of subunits which possess different hodologic and topographic characteristics as a function of the nucleus considered. Convergence or divergence of thalamocortical and corticothalamic projections on the different thalamic nuclei, as well as the laminar distribution of efferents in the cerebral cortex, are related strictly to the hodologic organization of different cellular subunits constituting the nuclei. Concentration or diffusion of thalamic projections on cerebral cortex is related more to the single or multiple projection of cell populations belonging to a thalamic nucleus than to widespread collateralization of thalamocortical axons.

Afferent Pathways↗
PubMed1985

Efferent fibers from the motor cortex terminate bilaterally in the thalamus of rats and cats.

The anterograde transport of lectin-conjugated horseradish peroxidase (WGA-HRP) was here employed in order to visualize crossed corticothalamic efferents of the motor cortex in rats and cats. After WGA-HRP cortical injections in the rat retrogradely labeled cells were observed in the ipsilateral thalamus, and heavy anterograde labeling was observed both in the ipsi- and contralateral thalamus. The contralateral anterograde labeling was less intense than the ipsilateral one and it was distributed in the anterior intralaminar structures, in the parafascicular nucleus, in the ventromedial, ventrolateral and ventrobasal nuclei and in the posterior complex, symmetrically to the labeling observed on the ipsilateral side. Further experiments were made in the rat in order to ascertain that the bilateral anterograde labeling in the thalamus derived unilaterally from the cortex. To this purpose, kainic acid was injected unilaterally either into the frontal cortex or into the thalamus, and WGA-HRP was later injected on the same side in the frontal cortex. Moreover, WGA-HRP was injected into the frontal cortex after splitting of the corpus callosum. The results obtained in these experiments confirmed that cortical neurons projected bilaterally upon the thalamus. Further, these experiments indicated that at least the majority of the contralateral fronto-thalamic fibers crossed the midline in the thalamic massa intermedia. WGA-HRP injections into the pericruciate cortex in the cat confirmed the presence of anterogradely labeled terminals in the contralateral anterior and posterior intralaminar, ventral anterior, ventromedial and ventrolateral nuclei. The labeling was in all cases heavier in the intralaminar nuclei than in the other structures, but it was less intense than that observed in the rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

The organization of the ipsi- and contralateral claustrocortical system in rat with notes on the bilateral claustrocortical projections in cat.

The organization of the claustrocortical system was investigated in rat by means of cortical injections of either lectin-conjugated horseradish peroxidase or retrograde fluorescent tracers. The latter were also employed in cat. Evans Blue, Fast Blue, True Blue, Nuclear Yellow and Diamidino Yellow were used in different combinations and were injected, uni- or bilaterally, in different cortical fields. Cells retrogradely labeled from each cortical injection were observed in the ipsi- and contralateral claustrum. Anterogradely labeled terminals were also seen in the claustra of both sides in the horseradish peroxidase experiments. The topographic and quantitative study of the distribution of labeled neurons showed a topographic organization of the rat's claustrocortical system, although a certain degree of overlap of the cell populations projecting to frontal and occipital fields was also evident. Four types of branched claustrocortical neurons were observed in the double labeling experiments: neurons branching ipsilaterally (A) or contralaterally (B) to anterior and posterior cortical fields; neurons branching bilaterally to homotopic (C) or heterotopic (D) cortical fields. Each population of branched neurons was equivalent to a different percent value of the total labeled cell populations; the percent value decreased from type A to type D. Type C branched neurons were also identified in the claustrofrontal system of the cat. The intricate organization of the claustral-ascending projections suggests that the nucleus is involved in different cortical activities and that its efferents may also provide the substrate of a powerful subcortical mechanism of interhemispheric communication.

Animals↗