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Biomedical subjects

A Tempini

Publications and source records attributed to A Tempini.

11 recordsLinked to original sources
PubMed2000

Role of the sympathetic nervous system during the development of obesity-induced hypertension in rabbits.

We have previously reported that weight gain induced by high-fat diet (HFD) leads to an increase in mean arterial pressure (MAP, +14%) and heart rate (HR, +31%) in the adult rabbit. In the present study, we tested the hypothesis that an increased activity of the sympathetic nervous system may contribute to the development of obesity-induced hypertension. A combination of alpha- and beta-adrenergic blockers (terazosin + propranolol) was chronically administered to rabbits housed in metabolic cages for continuous monitoring of arterial pressure by telemetry, 24 h a day. After 2 weeks of adrenergic blockade under control diet, animals were switched to HFD for the next 6 weeks. HFD induced a progressive increase in body weight, but no increase in mean arterial pressure (+0.2+/-2.5%) and a slight increase in heart rate (+14+/-3%). Time-control animals fed normal diet showed no changes in MAP or HR with long-term alpha- and beta-adrenergic blockade. Our results indicate that the activation of the sympathetic nervous system may play an important role in the pathogenesis of obesity-induced hypertension.

Adrenergic alpha-Antagonists↗
PubMed1999

Serial changes in cardiovascular and renal function of rabbits ingesting a high-fat, high-calorie diet.

To explore the mechanisms of obesity-induced hypertension we analyzed the sequential changes in cardiovascular and renal function in adult rabbits switched to high-fat diet (HFD) for 8 weeks. Animals were housed in metabolic cages for continuous 24-h recording of arterial pressure by telemetry and daily urine collection. High-fat diet induced a progressive increase in body weight (+47%) and a rapid rise in mean arterial pressure, heart rate, and glomerular filtration rate that stabilized, respectively, at 14%, 31% and 68% greater than control values. Time-course analysis of changes in blood pressure may reveal two components of obesity-induced hypertension, an early phase related to HFD itself and a later phase related to weight gain.

Animals↗
PubMed1999

Regulation of blood pressure during long-term ouabain infusion in Long-Evans rats.

We tested whether ouabain, an inhibitor of the sodium pump, can lead to chronic hypertension in Long-Evans rats using sensitive 24-h measurements of blood pressure. After a control week of vehicle isotonic saline infusion (14.4 mL/day), ouabain was infused intravenously at 30 microg/kg/day in intact (2K) and uninephrectomized (1K) Long-Evans rats for a total of 4 weeks. Although plasma ouabain concentration rose to 0.97 +/- 0.15 nmol/L with ouabain infusion, mean arterial pressure did not change in either 2K (delta = -0.6 +/- 1.3 mm Hg) or 1K (delta = -1.2 +/- 0.7 mm Hg) rats. These data suggest that Long-Evans rats are insensitive to the hypertensive effects of ouabain.

Animals↗
PubMed1998

Dexterity in adult monkeys following early lesion of the motor cortical hand area: the role of cortex adjacent to the lesion.

Infant monkeys were subjected to unilateral lesions of the motor cortex (mainly its hand representation). After maturation, they showed normal use of the contralateral hand for global grip movements. However, as compared with the ipsilateral hand, precision grip tasks requiring relatively independent finger movements were performed with less dexterity, particularly if adjustments of the wrist position were necessary. The purpose of this study was to investigate mechanisms which may be responsible for the rather well, although not complete, preservation of manipulative behaviour of these adult monkeys. To this end, the hand representations were mapped bilaterally with intracortical microstimulation in the mature monkeys, and the dexterity of both hands assessed quantitatively in a precision grip task. The behavioural effects of reversible inactivations of the primary (M1) and supplementary (SMA) motor cortical areas were then tested. The following were found. (i) The hand contralateral to the lesion exhibited subtle but significant dexterity deficits, as compared with the ipsilateral hand; the deficit was essentially for complex movements requiring dissociation of the thumb-index finger pinch from the other digits, involving also an arm rotation. (ii) Reversible inactivation of the M1 hand representation in the intact hemisphere dramatically impaired dexterity of the opposite hand without affecting the ipsilateral hand (contralateral to the early lesion). (iii) A relatively complete hand representation was found to occupy a new territory, medial to the old lesion. (iv) The role of this new displaced representation was crucial for the preserved dexterity of the opposite hand, as evidenced by its functional inactivation. In contrast, inactivation of both SMA cortices did not interfere with the manipulative behaviour. It is thus concluded that the preserved functional capacity of manipulations with the hand opposite the early lesion can be essentially attributed to a cortical reorganization around the old lesion. Under the present experimental conditions, contributions from either the SMA or the intact M1 appear not to be crucial.

Animals↗
PubMed1998

Neuronal activity in the primate supplementary motor area and the primary motor cortex in relation to spatio-temporal bimanual coordination.

Single neuronal activity was recorded from the supplementary motor area (SMA-proper and pre-SMA) and primary motor cortex (M1) in two Macaca fascicularis trained to perform a delayed conditional sequence of coordinated bimanual pull and grasp movements. The behavioural paradigm was designed to distinguish neuronal activity associated with bimanual coordination from that related to a comparable motor sequence but executed unimanually (left or right arm only). The bimanual and unimanual trials were instructed in a random order by a visual cue. Following the cue, there was a waiting period until presentation of a "go-signal", signalling the monkey to perform the instructed movement. A total of 143 task-related neurons were recorded from the SMA (SMA-proper, 62; pre-SMA, 81). Most SMA units (87%) were active in both unimanual contralateral and unimanual ipsilateral trials (bilateral neurons), whereas 9% of units were active only in unimanual contralateral trials and 3% were active only in unimanual ipsilateral trials. Forty-eight per cent of SMA task-related units were classified as bimanual, defined as neurons in which the activity observed in bimanual trials could not be predicted from that associated with unimanual trials when comparing the same events related to the same arm. For direct comparison, 527 neurons were recorded from M1 in the same monkeys performing the same tasks. The comparison showed that M1 contains significantly less bilateral neurons (75%) than the SMA, whereas the reverse was observed for contralateral neurons (22% in M1). The proportion of M1 bimanual cells (53%) was not statistically different from that observed in the SMA. The results suggest that both the SMA and M1 may contribute to the control of sequential bimanual coordinated movements. Interlimb coordination may then take place in a distributed network including at least the SMA and M1, but the contribution of other cortical and subcortical areas such as cingulate motor cortex and basal ganglia remains to be investigated.

Animals↗
PubMed1997

Effects of reversible inactivation of the supplementary motor area (SMA) on unimanual grasp and bimanual pull and grasp performance in monkeys.

The supplementary motor area (SMA) was reversibly inactivated by muscimol microinfusion in two monkeys while they were performing two motor tasks: (1) a delayed conditional bimanual drawer pulling and grasping sequence which was initiated on a self-paced basis; (2) a unimanual reach and grasp task (modified Kluver board task). Unilateral or bilateral inactivation of the SMA induced a prominent deficit in trial initiation of bimanual sequential movements, affecting the hand contralateral to the inactivated side or both hands, respectively. The deficit was a long lasting (10-15 min or more) inability of the monkey to place its hand (s) in the ready position on start touch-sensitive pads, a condition required to initiate the drawer task. However, if after such a deficit period, the experimenter put his hand on the start touch-sensitive pad to initiate the trial, then the monkey executed the drawer task without obvious motor deficit. SMA inactivation did not affect unimanual reaching and grasping movements in the board task. In contrast to the SMA, inactivation of other motor areas (primary, premotor dorsal, anterior intraparietal area) did not affect the initiation of movement sequences in the drawer task. These data thus indicate that the SMA plays a crucial and specific role in initiation of self-paced movement sequences. However, SMA inactivation did not prevent the monkeys to perform coordinated movements of the two forelimbs and hands, indicating that SMA is not necessary for bimanual coordination.

Animals↗
PubMed1996

Electrically induced fos-like immunoreactivity in the auditory pathway of the rat: effects of survival time, duration, and intensity of stimulation.

The goal of the present study was to establish how Fos-like immunoreactivity (FLI) elicited in the rat auditory pathway by unilateral electric stimulation of the cochlea is affected by the following experimental parameters: duration and intensity of stimulation, duration of survival time after offset of stimulation. The dense FLI found in the ipsilateral dorsal cochlear nucleus, as well as the moderate FLI found in the contralateral dorsal cochlear nucleus and in the posteroventral cochlear nucleus on both sides, were consistent after survival times ranging from 0 to 2-3 h, but they significantly decreased after longer survival times (5 and 6 h). In the same nuclei, FLI was increased even by short durations of stimulation (5 and 10 min) as compared to control rats, although FLI progressively increased for longer stimulation (20 and 45 min). In the auditory thalamus, FLI was found mainly in the peripeduncular nucleus, the dorsal and medial divisions of the medial geniculate body, whereas its ventral division was virtually devoid of immunoreactive neurons. This pattern of FLI distribution in the auditory thalamus persisted even after relatively long survival times (5 and 6 h). In both the cochlear nucleus and auditory thalamus, the density of FLI slightly increased in parallel with the intensity of stimulation. In other auditory nuclei, such as the inferior colliculus and the nucleus of the lateral lemniscus, there was no simple relation between the density of FLI and the three tested experimental parameters. Thus, the distribution and density of FLI did not vary in parallel in the various nuclei of the auditory pathway as a function of the tested experimental parameters; different patterns of FLI changes were instead observed in different auditory nuclei.

Action Potentials↗
PubMed1993

[Polychlorinated biphenyls as a cause of sterility in women?].

A total of 59 female infertile patients were investigated for the concentration of polychlorinated biphenyls (PCB) in their blood serum and follicular fluid. The average concentration of PCB in 66 related samples of follicular fluid and blood serum was 1.6 and 1.8 ng/ml, respectively. A splitting of the patients into two collectives, one with explained infertility, the other with unexplained infertility, showed no evidence of a higher PCB concentration in unexplained infertility patients. These results may exclude PCB as a primary reason for unexplained infertility.

Adult↗
PubMed1991

Lung diffusing capacity and red blood cell volume.

The aim of this study was to test whether a large surface to volume ratio of the red blood cells is advantageous for O2 transfer in lungs. Suspensions of washed large (human) and small (sheep) red blood cells were used to perfuse in random order isolated cat lungs (n = 7). The lungs were kept at 27 degrees C, ventilated with 1.0 l/min and perfused with 110 ml/min. Hemoglobin concentration was 70 g/l. Assuming an inhomogeneous lung with an alveolar dead space compartment, pulmonary diffusing capacity for O2 (DLO2) was 0.53 +/- 0.10 ml.min-1.mmHg-1 (mean +/- SD) when perfusing with sheep red cells and 0.52 +/- 0.13 with human red cells. On the basis of a lung model with a low VA/Q and a high VA/Q compartment the values were 0.86 and 0.93. Thus, DLO2 was not larger with smaller red blood cells, i.e. with higher red cell surface area per blood volume. Possible explanations for this unexpected result are discussed.

Animals↗
PubMedDate not supplied

[Simultaneous measurement of blood concentrations of O2 and CO with a Van Slyke apparatus].

imultaneous analysis of a blood sample for its O2 and CO contents (Co2 and Cco) with the original manometric technique of Van Slyke entails a directional error on Co2 and Cco when blood contains CO. This important drawback is due to the fact that Na2S2O4 employed for the O2 absorption also reduces methemoglobin into hemoglobin which then reabsorbs a variable amount of the extracted CO. This amount is equal to the directional error and results in an overestimation of Co2 and in an underestimation of Cco. In order to analyze and possibly correct for this error, we have measured it by gas chromatography by determining Cco on blood samples with and without O2 absorption by Na2S2O4. The error has been found to be a function of both blood CO and Hb contents. An equation and a nomogram are presented allowing correction of the results obtained by the Van Slyke method. So corrected the results are equally precise in presence and in absence of CO (+/- 0.1 volume %) which makes simultaneous Co2 and Cco measurements with this classical and unexpensive method quite acceptable.

Blood Gas Analysis↗