Insulin enhances vascular cell adhesion molecule-1 expression in human cultured endothelial cells through a pro-atherogenic pathway mediated by p38 mitogen-activated protein-kinase

AIMS/HYPOTHESIS

Although hyperinsulinaemia in Type 2 diabetes in states of insulin resistance is a risk factor for atherosclerotic vascular disease, underlying mechanisms are poorly understood. We tested the hypothesis that insulin increases monocyte-endothelial interactions, which are implicated in atherosclerosis.

METHODS

We treated human umbilical vein endothelial cells with insulin (10(-10) to 10(-7) mol/l) for 0 to 24 h. To dissect potentially implicated signal transduction pathways, we treated endothelial cells with known pharmacological inhibitors of two distinct insulin signalling pathways: the phosphatidylinositol-3'-kinase (PI3'-kinase) inhibitor wortmannin (3 x 10(-8) to 10(-6) mol/l), involved in insulin-induced endothelial nitric oxide synthase stimulation, and the p38 mitogen-activated protein (p38MAP) kinase inhibitor SB-203580 (10(-7) to 2 x 10(-6) mol/l). We measured adhesion molecule expression by cell surface enzyme immunoassays and U937 monocytoid cell adhesion in rotational adhesion assays.

RESULTS

At pathophysiological concentrations (10(-9) to 10(-7) mol/l), insulin concentration-dependently induced vascular cell adhesion molecule (VCAM)-1 (average increase: 1.8-fold) peaking at 16 h. By contrast, the expression of intercellular adhesion molecule-1 and E-selectin were unchanged. The effect on VCAM-1 was paralleled by increased U937 cell adhesion. In the absence of cytotoxicity, wortmannin significantly potentiated the effect of insulin alone on VCAM-1 surface expression and monocytoid cell adhesion, whereas SB-203580 (10(-6) mol/l) completely abolished such effects.

CONCLUSIONS/INTERPRETATION

These observations indicate that insulin promotes VCAM-1 expression in endothelial cells through a p38MAP-kinase pathway, amplified by the PI3'-kinase blockage. This could contribute to explaining the increased atherosclerosis occurring in subjects with hyperinsulinaemia, or in states of insulin resistance, which feature a defective PI3'-kinase pathway.

Mechanisms for reduction of endothelial activation by oleate: inhibition of nuclear factor-kappaB through antioxidant effects

In a model of early atherogenesis based on cultured endothelial cells, we observed that the incorporation of oleic acid in cellular lipids decreases the stimulated expression of several endothelial adhesion molecules and soluble products typically expressed during endothelial activation and involved in monocyte recruitment. We investigated possible mechanisms for this effect assessing the stimulated induction of nuclear factor-kappaB. In parallel, we also measured glutathione (GSH) content and the activity of antioxidant enzymes after oleate treatment and cytokine stimulation. Oleate prevented the stimulated depletion of GSH without any change in the activity of antioxidant enzymes. These results suggest an antioxidant mechanism by which oleate may exert direct vascular atheroprotective effects.

Vasculoprotective effects of oleic acid: epidemiological background and direct vascular antiatherogenic properties

BACKGROUND AND AIMS

The use of the "Mediterranean diet" as a means of preventing atherosclerotic vascular disease is gaining increasing acceptance. As early as in the late 1950s, it was found that the inhabitants of Greece and Southern Italy had a very low incidence of coronary artery disease and that, among other components, their diets were very rich in oleic acid, the main constituent of the olive oil, making up about 29% of their daily caloric intake. It is now clear that, in addition to its relatively minor effects on cholesterol levels, oleic acid directly interferes with the inflammatory response characterising early atherogenesis due to the endothelial expression of adhesion molecules for circulating monocytes.

RESULTS

In in vitro models of early atherogenesis based on cytokine-stimulated cultured endothelial cells, we have observed that the incorporation of oleic acid in total cell lipids is accompanied by decreased expression of a number of major pro-inflammatory proteins, such as endothelial leukocyte adhesion molecules.

CONCLUSIONS

The results of our investigations indicate that oleic acid has a direct vascular atheroprotective effect, and suggest that it may be possible to prevent atherosclerosis by modulating the vascular response to classical triggers (high levels of cholesterol and the advanced glycation end-products of diabetes) using a strategy that is fundamentally different from, and therefore complementary to, drug-based therapy.

Spontaneous baroreflex modulation of heart rate and heart rate variability during orthostatic stress in tetraplegics and healthy subjects

OBJECTIVE

This study was addressed to investigate the contribution of vagal and sympathetic mechanisms to the genesis of low-frequency (LF) oscillations of RR-interval.

DESIGN

To this aim, we utilized the pathophysiological model of tetraplegics, who have intact vagal afferent and efferent pathways of the baroreceptor reflex arc but interrupted medullary-spinal sympathetic pathways.

METHODS

We studied nine complete, traumatic, tetraplegics (C4-C7, TET) and 10 normally healthy subjects (NR) at rest and during physiological baroreceptors unloading induced by 70 degrees head-up tilt. Autoregressive power spectral analysis was used to investigate RR-interval and systolic arterial pressure (SAP) variabilities. Baroreflex modulation of sinus node was assessed by the spontaneous baroreflex sequences method.

RESULTS

Both at-rest and during-tilt LF and high frequency (HF) components were detected in RR-interval of NR, whereas in TET only the HF component was observed in both conditions (with one exception). Baroreflex sensitivity (BRS) did not significantly differ between TET and NR at rest, and underwent a significant and similar decrease during tilt in both groups, being accompanied in NR by a significant increase in LF relative power. Spectral analysis of SAP provided results similar to RR-interval. Tilt also slowed the centre frequency of the LF components of RR-interval and SAP.

CONCLUSIONS

During unperturbed physiological conditions, a change in efferent vagal activity to the heart from baroreflex stimulation by spontaneous arterial pressure changes, is unlikely to contribute on its own to the genesis of LF heart period oscillations in humans who lack the ability to modulate sympathetic nerve traffic to the heart. However, the possibility that a baroreflex modulation of LF oscillations require an intact sympathetic control should be carefully considered.

Positive and negative feedback mechanisms in the neural regulation of cardiovascular function in healthy and spinal cord-injured humans

BACKGROUND

We tested the hypothesis that in humans, hypertension/tachycardia and hypotension/bradycardia nonbaroreflex sequences that occur within spontaneous arterial pressure (AP) and R-R interval fluctuations are an expression of positive feedback mechanisms neurally regulating the cardiovascular system.

METHODS AND RESULTS

We studied 15 spinal cord-injured (SCI) subjects (8 tetraplegics and 7 paraplegics) and 8 healthy subjects. The occurrence of nonbaroreflex (NBseq) and baroreflex (Bseq) sequences, ie, hypertension-bradycardia and hypotension-tachycardia sequences, was assessed during rest and head-up tilt (HUT). The ratio between Bseq and NBseq (B/NB ratio) was also calculated. In resting conditions, the occurrence of NBseq was significantly lower (P:<0.05) in tetraplegics (7.9+/-1.5) than in paraplegics (16.2+/-3.2) and normal subjects (19.0+/-3.5), whereas the occurrence of Bseq was not significantly different between the 3 groups (38.6+/-11.9 versus 45.4+/-6.0 versus 47.0+/-11.9). In tetraplegics, the B/NB ratio showed a marked, significant decrease (from 8.4+/-4.2 to 1.9+/-0.8, P:<0.05) in response to HUT, whereas in normal subjects, it showed a significant increase (from 3.5+/-0.7 to 9.4+/-2.7, P:<0.05). In paraplegics, the B/NB ratio did not change significantly in response to HUT (from 4.5+/-1.6 to 4.8+/-1.1).

CONCLUSIONS

Our data suggest that nonbaroreflex sequences occur in humans and might represent the expression of an integrated, neurally mediated, feed-forward type of short-term cardiovascular regulation that is able to interact dynamically with feedback mechanisms of baroreflex origin.

Effects of a residential exercise training on baroreflex sensitivity and heart rate variability in patients with coronary artery disease: A randomized, controlled study

BACKGROUND

Myocardial ischemia and infarction impair baroreflex sensitivity (BRS), which when depressed is predictive of future cardiac events after myocardial infarction (MI). The main objective of this study was to determine whether exercise training improves BRS in patients with coronary artery disease.

METHODS AND RESULTS

Ninety-seven male patients with and without a previous MI were recruited after myocardial revascularization surgery and randomized into trained (TR) or untrained (UTR) groups. TR patients underwent a residential exercise program at 85% of maximum heart rate (HRmax) consisting of 2 daily sessions 6 times a week for 2 weeks. Eighty-six patients (45 TR and 41 UTR) completed the study. BRS was assessed at baseline and at the end of the protocol by the spontaneous baroreflex method. The standard deviation of mean R-R interval (RRSD) was also assessed as a measure of heart rate variability. At baseline, there were no significant differences between TR and UTR patients in any variable. In TR patients, BRS increased from 3.0+/-0.3 to 5.3+/-0.7 ms/mm Hg (P:<0.001), RRSD from 18.7+/-1.4 to 23.6+/-1.6 ms (P:<0.01), and R-R interval from 792. 0+/-15.5 to 851.3+/-20.5 ms (P:<0.001). No significant changes occurred in UTR patients. Increases in BRS and RRSD were significant in patients either with or without a previous MI.

CONCLUSIONS

Exercise training increases BRS and heart rate variability in patients with coronary artery disease. Improved cardiac autonomic function might add to the other benefits of exercise training in secondary prevention of ischemic heart disease.

Cerebral arteritis following methylphenidate use

Stroke is a well-documented complication of amphetamine abuse. Methylphenidate, chemically and pharmacologically similar to amphetamines, is widely used in the treatment of attention deficit disorder in children. The possibility of vasculitis connected to methylphenidate should not be surprising. A case is reported of stroke associated with ingestion of methylphenidate in an 8-year-old boy. Family history was negative and other causes of vasculitis were excluded. We draw your attention to the risk of using methylphenidate for a long period of time.

Effects of diet and of dietary components on endothelial leukocyte adhesion molecules

Endothelial-leukocyte adhesion molecules are involved in processes regulating the selective attachment of leukocytes to the vessel wall, which participate in tissue inflammation, atherogenesis, and immunity. There has been recent appreciation that diet or specific dietary components may modulate such processes. Highly unsaturated-- particularly omega-3 -- fatty acids and antioxidants are receiving increasing attention in this regard as potential antiatherogenic and anti-inflammatory agents. The vascular surface expression of endothelial leukocyte molecules can also be reflected by plasma levels of "soluble" adhesion molecules, thus allowing the assessment of the effects of diet and selected dietary components on these processes in vivo.

Tuberous sclerosis associated with MDR1 gene expression and drug-resistant epilepsy

Intractable seizures are the most common manifestation in severe cases of tuberous sclerosis. Multidrug resistance type 1 (MDR1) gene expression is directly linked to the resistance of tumor cells to chemotherapy as the major cause of treatment failure, but it has not been reported in tuberous sclerosis cells nor has the relationship between the MDR1 gene and antiepileptic drugs been described. A 4-month-old female is described with poorly controlled seizures secondary to tuberous sclerosis. The patient was treated with antiepileptic drugs, including phenytoin, phenobarbital, and lorazepam, without improvement of symptoms. Phenytoin blood levels were invariably subtherapeutic and ranged from 0.45 to 3.55 microg/mL, despite several consecutive intravenous loading doses. Surgical treatment with total resection of the brain lesions was performed as a last resort. Immunohistochemical analysis of the resected tissues revealed high levels of P-glycoprotein 170 expression, the product of the MDR1 gene. Both MDR1 gene expression and persistently low phenytoin levels likely share a common pathway liable to induce drug-resistant epilepsy.

Muscle metaboreflex contribution to sinus node regulation during static exercise: insights from spectral analysis of heart rate variability

BACKGROUND

It is currently assumed that during static exercise, central command increases heart rate (HR) through a decrease in parasympathetic activity, whereas the muscle metaboreflex raises blood pressure (BP) only through an increase in sympathetic outflow to blood vessels, because when the metaboreflex activation is maintained during postexercise muscle ischemia, BP remains elevated while HR recovers. We tested the hypotheses that the muscle metaboreflex contributes to HR regulation during static exercise via sympathetic activation and that the arterial baroreflex is involved in the HR recovery of postexercise muscle ischemia.

METHODS AND RESULTS

Eleven healthy male volunteers performed 4-minute static leg extension (SLE) at 30% of maximal voluntary contraction, followed by 4-minute arrested leg circulation (ALC). Autonomic regulation of HR was investigated by spectral analysis of HR variability (HRV), and baroreflex control of heart period was assessed by the spontaneous baroreflex method. SLE resulted in a significant increase in the low-frequency component of HRV that remained elevated during ALC. The normalized high-frequency component of HRV was reduced during SLE and returned to control levels during ALC. Baroreflex sensitivity was significantly reduced during SLE and returned to control levels during ALC when BP was kept elevated above the resting level while HR recovered.

CONCLUSIONS

The muscle metaboreflex contributes to HR regulation during static exercise via a sympathetic activation. The bradycardia that occurs during postexercise muscle ischemia despite the maintained sympathetic stimulus may be explained by a baroreflex-mediated increase in parasympathetic outflow to the sinoatrial node that overpowers the metaboreflex-induced cardiac sympathetic activation.

Direct vascular antiatherogenic effects of oleic acid: a clue to the cardioprotective effects of the Mediterranean diet

Atherosclerosis, the main cause of ischemic heart disease, is a process with relevant inflammatory components, in which LDL-cholesterol, largely emphasized in the last years as a "causal" factor following the improvement in prognosis with cholesterol-lowering agents, is only one of the culprits. Despite the use of new cholesterol-lowering drugs, atherosclerotic vascular disease will likely continue to be the main cause of death in Western countries. Furthermore, the statistical relationship between cholesterol and cardiovascular mortality only explains a relatively minor component of differences in mortality among diverse countries. For these reasons, the interest in preventive approaches complementary or alternative to cholesterol reduction should be one of the main objectives of cardiovascular research in the years to come. Already in the '70s the very low incidence of atherosclerotic diseases in Mediterranean countries (Greece and Southern Italy) and the importance of the "dietary factor" in such protection were noticed. Diets for people in these countries are, among other components, very rich in oleic acid, the main constituent of olive oil, with about 29% of daily caloric intake derived from monounsaturated fatty acids. Oleic acid, besides exerting relatively minor effects on the quantitative and qualitative regulation of cholesterol levels, appears to interfere directly with the inflammatory response that characterizes early atherogenesis. The endothelial expression of adhesion molecules for circulating monocytes, induced by inflammatory cytokines, minimally oxidized LDL and the advanced glycation end-products present in diabetes, substantially contributes to the onset and early progression of atherosclerosis. In an in vitro model of early atherogenesis based on cultured endothelial cells stimulated by cytokines, we observed that the incorporation of oleic acid in total cell lipids--mostly at the expenses of saturated fatty acids--decreases the expression of several endothelial leukocyte adhesion molecules, among which vascular cell adhesion molecule-1, involved in the selective monocyte recruitment in the arterial intima. Oleic acid also determines a parallel reduction in messenger RNA for this molecule, interfering with the activation of the most important transcription factor controlling endothelial activation, nuclear factor-kappa B. Thus, possibly in concert with other more highly unsaturated fatty acids, oleic acid may contribute to the prevention of atherosclerosis also through a modulation of gene expression for endothelial leukocyte adhesion molecules. This series of investigations emphasizes the possibility of preventive interventions in atherosclerosis based on the modulation of vascular response to classical "triggers" (cholesterol, advanced glycation end-products of diabetes), an intervention strategy fundamentally different from--and thereby complementary to--those now more in fashion.

Investigating feed-forward neural regulation of circulation from analysis of spontaneous arterial pressure and heart rate fluctuations

BACKGROUND

Analysis of spontaneous fluctuations in systolic arterial pressure (SAP) and pulse interval (PI) reveals the occurrence of sequences of consecutive beats characterized by SAP and PI changing in the same (+PI/+SAP and -PI/-SAP) or opposite (-PI/+SAP and +PI/-SAP) direction. Although the former reflects baroreflex regulatory mechanisms, the physiological meaning of -PI/+SAP and +PI/-SAP is unclear. We tested the hypothesis that -PI/+SAP and +PI/-SAP "nonbaroreflex" sequences represent a phenomenon modulated by the autonomic nervous system reflecting a feed-forward mechanism of cardiovascular regulation.

METHODS AND RESULTS

We studied anesthetized rabbits before and after (1) complete autonomic blockade (guanethidine+propranolol+atropine, n=13; CAB), (2) sympathetic blockade (guanethidine+propranolol, n=15; SB), (3) parasympathetic blockade (atropine, n=16), (4) sinoaortic denervation (n=10; SAD), and (5) controlled respiration (n=10; CR). Nonbaroreflex sequences were defined as >/=3 beats in which SAP and PI of the following beat changed in the opposite direction. CAB reduced the number of nonbaroreflex sequences (19. 1+/-12.3 versus 88.7+/-36.6, P<0.05), as did SB (25.3+/-11.7 versus 84.6+/-23.9, P<0.001) and atropine (11.2+/-6.8 versus 94.1+/-32.4, P<0.05). SB concomitantly increased baroreflex sensitivity (1.18+/-0. 11 versus 0.47+/-0.09 ms/mm Hg, P<0.01). SAD and CR did not significantly affect their occurrence.

CONCLUSIONS

These results suggest that nonbaroreflex sequences represent the expression of an integrated, neurally mediated, feed-forward type of short-term cardiovascular regulation able to interact dynamically with the feedback mechanisms of baroreflex origin in the control of heart period.

Oleic acid inhibits endothelial activation : A direct vascular antiatherogenic mechanism of a nutritional component in the mediterranean diet

Because oleic acid is implicated in the antiatherogenic effects attributed to the Mediterranean diet, we investigated whether this fatty acid can modulate endothelial activation, ie, the concerted expression of gene products involved in leukocyte recruitment and early atherogenesis. We incubated sodium oleate with human umbilical vein endothelial cells for 0 to 72 hours, followed by coincubation of oleate with human recombinant tumor necrosis factor, interleukin (IL)-1alpha, IL-1beta, IL-4, Escherichia coli lipopolysaccharide (LPS), or phorbol 12-myristate 13-acetate for a further 6 to 24 hours. The endothelial expression of vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and intercellular adhesion molecule-1 was monitored by cell surface enzyme immunoassays or flow cytometry, and steady-state levels of VCAM-1 mRNA were assessed by Northern blot analysis. At 10 to 100 micromol/L for >24 hours, oleate inhibited the expression of all adhesion molecules tested. After a 72-hour incubation with oleate and a further 16-hour incubation with oleate plus 1 microg/mL LPS, VCAM-1 expression was reduced by >40% compared with control. Adhesion of monocytoid U937 cells to LPS-treated endothelial cells was reduced concomitantly. Oleate also produced a quantitatively similar reduction of VCAM-1 mRNA levels on Northern blot analysis and inhibited nuclear factor-kappaB activation on electrophoretic mobility shift assays. Incubation of endothelial cells with oleate for 72 hours decreased the relative proportions of saturated (palmitic and stearic) acids in total cell lipids and increased the proportions of oleate in total cell lipids without significantly changing the relative proportions of polyunsaturated fatty acids. Although less potent than polyunsaturated fatty acids in inhibiting endothelial activation, oleic acid may contribute to the prevention of atherogenesis through selective displacement of saturated fatty acids in cell membrane phospholipids and a consequent modulation of gene expression for molecules involved in monocyte recruitment.

Effect of postural changes on cardiovascular responses to static exercise in hypertensive human beings

OBJECTIVE

In hypertensive patients, exaggerated increases in vascular resistance and arterial blood pressure have been reported on changing posture from supine to upright. In this study we tested the hypothesis that in hypertensive subjects, upright posture induces an increase in the vasoconstrictor and pressor responses to physical exercise.

SUBJECTS AND METHODS

We studied 17 males with mild hypertension and 10 sex- and age-matched normotensives. Each performed three bouts of static handgrip at 30% maximum voluntary contraction for 2 min after 10 min of supine rest and, in sequence, after 10 min of sitting and 10 min of standing. Arterial pressure, heart rate and forearm vascular resistance were measured by Finapres and plethysmography, respectively.

RESULTS

Exercise posture did not affect the mean arterial pressure and heart rate responses to static handgrip. No significant differences in these responses were observed between the hypertensives and the normotensives in any posture. In the hypertensives (n = 12), forearm vascular resistance did not change significantly from resting values during supine and sitting static handgrip but increased significantly during standing static handgrip. In the normotensives, forearm vascular resistance did not change significantly from resting values during static handgrip in any posture. The forearm vascular resistance response to the standing static handgrip was significantly greater in the hypertensives than the normotensives. The algebraic sum of forearm vascular resistance responses to postural change from sitting to standing plus that induced by sitting static handgrip (i.e. additive reflexes) was significantly less than the forearm vascular resistance response to the standing static handgrip (i.e. combined relexes), indicating a facilitatory interaction between exercise and orthostatic stimuli in hypertensives. In contrast, the algebraic sum of the heart rate responses to postural change from sitting to standing plus that induced by sitting static handgrip was significantly greater than the response to standing static handgrip, indicating an inhibitory interaction.

CONCLUSIONS

In hypertensive patients, physiological orthostasis causes an increased vasoconstrictor response to static exercise, but this is opposed by an inhibitory influence on the heart rate response, with the result that the pressor response to static exercise is unaffected by upright posture.

Role of muscular factors in cardiorespiratory responses to static exercise: contribution of reflex mechanisms

We investigated the effects of muscle mass and contraction intensity on the cardiorespiratory responses to static exercise and on the contribution afforded by muscle metaboreflex and arterial baroreflex mechanisms. Ten subjects performed static handgrip at 30% maximal voluntary contraction (MVC) (SHG-30) and one-leg extension at 15% (SLE-15) and 30% (SLE-30) MVC, followed by postexercise circulatory occlusion (PECO). Mean arterial pressure (MAP) and heart rate (HR) responses were greater during SLE-30 than during SHG-30. The difference in MAP was maintained by PECO, and the part of the pressor response maintained by PECO was greater after SLE-30 than after SHG-30 (88.3 +/- 10.6 and 67.8 +/- 12.7%, respectively, P = 0. 02). There were no differences in MAP and HR responses between SHG-30 and SLE-15 trials. Baroreflex sensitivity was maintained during SHG-30 and SLE-15, whereas it was significantly reduced during SLE-30 and recovered back to the resting level during PECO. Minute ventilation and oxygen uptake increased more during SLE-30 than during both SHG-30 and SLE-15 trials. Minute ventilation remained significantly elevated above rest only during PECO following SLE-30. These data suggest that during static exercise the muscle mass and contraction intensity affect 1) the magnitude of the cardiorespiratory responses, 2) the contribution of muscle metaboreflex to the cardiorespiratory responses, and 3) the arterial baroreflex contribution to HR control.

[Epidemiological monitoring of psychological, neurological and sensory handicaps in the 0-24-year-old Abruzzo population (Italy). Preliminary results]

OBJECTIVE

To describe the setting up of the Abruzzo Region (Italy) Service for Prevention and Epidemiological Register of Handicaps, to show prevalence data of occurring diseases and fit regression models aimed at explicating disease occurrence in terms of risk factors; to discuss services access data in terms of their efficacy in fitting social and health needs.

SETTING AND DESIGN

We managed data obtained from a regional information system, based upon primary information sources operating in the Local Health Agencies (i.e. school medicine services, general practitioners, paediatricians, familiar counseling services, rehabilitation centers) and specialistic structures for diagnostic detection (multidisciplinary school équipes, hospital division of infant neuropsychiatry, outpatient infant neuropsychiatry services). The data managing model is a population-based epidemiological register. The target population is the 0-24 years population of the Abruzzo Region.

MAIN OUTCOME MEASURES

Occurrence data are expressed as prevalence rates, using standardisation according to the global population of the area of interest. Diagnoses have been defined according to the standard ICD-9 and ICD-10 criteria; definition of handicaps has been made according to the WHO classification (1981). Association between indicator (socio-demographic and anamnestic) variables and occurrence of disease has been fitted by logistic regression models.

RESULTS

Prevalence estimates obtained for the main infant neuropsychiatric diseases, as well as for the main handicap-determining genetic and/or congenital diseases, are consistent with the findings of literature in similar settings. An exception is the high occurrence of hyperkinetic disorders in both sexes. Rehabilitation is the main health need for all diagnostic axes. With respect to social needs, school and home personal care seem to be scarcely relevant if related to disease prevalence. Logistic regression analysis indicates socio-economic status and presence of handicapped relatives in the family as factors associated with the occurrence of disease. Respectively, the two factors are negatively associated with the occurrence of hyperkinetic disorders and positively associated with occurrence of mental retardation. Moreover, living in a natural family is negatively associated with evolutive disorders.

CONCLUSIONS

This is a report about the preliminary results obtained by a specialised register for infant psychological and neurological handicaps. The findings suggest, as operating indications, the standardisation of diagnostic procedures and the definition of common managing guidelines in different areas. Anyhow, the findings of this report highlight the importance of an epidemiological knowledge of handicap in order to design correct prevention strategies and health services planning.

[Spontaneous baroreflex control of heart rate during chronic tandropril therapy]

Differently from other vasodilators, the antihypertensive effect of ACE-inhibitors is not accompanied by an increase in resting heart rate which suggests a modulatory action of these drugs on arterial baroreflex control of heart rate. It is debated whether this modulation involve, an increase in gain (or sensitivity) of baroreflex mechanisms controlling heart rate or is due to a baroreflex control resetting. In this study we investigated the arterial baroreflex control of heart rate both in supine rest and during active standing before and after 7 and 30 days of treatment with a new ACE-inhibitor, trandolapril (2 mg per os oid) in 15 mild hypertensive patients. Baroreflex control of heart rate has been dynamically and non-invasively assessed by analysis of the continuous relationship between beat-to-beat spontaneous fluctuations in systolic blood pressure and pulse interval. By this method, sequences of 3 or more consecutive beats in which systolic blood pressure and pulse interval change in the same direction (either increasing or decreasing) are identified and a linear regression is applied to each individual sequence. The mean individual slope of the systolic blood pressure/pulse interval ratio obtained by averaging all slopes computed within a given period, is calculated and taken as an estimate of the spontaneous baroreflex sensitivity for that period. Trandolapril reduced resting blood pressure significantly (from 147.5 +/- 3.3/95.3 +/- 1.5 to 129.5 +/- 3.7/83.6 +/- 1.6 and 126.6 +/- 3.9/84.5 +/- 1.7 mmHg after 7 e 30 days, respectively) without affecting heart rate. The treatment did not alter baroreflex sensitivity but resulted in an apparent leftward shift of the regression line relating systolic blood pressure to pulse interval along the pressure axis, reflecting the lower prevailing level of arterial pressure. The increases in heart rate and blood pressure induced by standing in control conditions were not significantly modified by trandolapril. Baroreflex sensitivity was significantly reduced by standing both in control conditions and, to the same extent, during treatment. These results suggest that ACE-inhibition does not alter the gain of the integrated baroreflex mechanisms controlling heart rate, but results in a baroreflex resetting that may explain the lack of tachycardia normally observed during antihypertensive therapy with ACE-inhibitors.

Evaluation of reproducibility of spontaneous baroreflex sensitivity at rest and during laboratory tests

OBJECTIVE

The aim of the present study was to examine the reproducibility of arterial baroreflex sensitivity (BRS) provided by the spontaneous baroreflex method at rest and during laboratory tests.

METHODS

Twenty healthy volunteers were studied 24 h apart, in the same laboratory and under the same environmental conditions, at rest, during active standing, while performing mental arithmetics and during static hand-gripping. Systolic blood pressure, mean arterial pressure and pulse interval were continuously and non-invasively measured by using a Finapres device. BRS was evaluated by analysing the slopes of spontaneously occurring sequences of three or more consecutive beats in which systolic blood pressure and pulse interval of the following beat both increased or decreased, in the same direction, in a linear fashion. Individual BRS were obtained by averaging all slopes computed within a given test.

RESULTS

Under each test condition BRS did not differ significantly between the two consecutive days, showing strikingly similar values. The mean group coefficients of variation (CVAR), obtained by averaging individual CVAR, between the two experimental days were 15.0, 13.9 and 19.7% for resting, standing, static hand-gripping and mental arithmetic, respectively. No relationships were found between individual CVAR and individual mean arterial pressure, pulse interval and number of baroreflex sequences under any tested condition, on both experimental days.

CONCLUSIONS

These results show that the spontaneous baroreflex method provides good BRS reproducibility under various stimuli that affect the neural control of circulation differently. They also suggest that BRS variability is dependent neither on haemodynamic modifications nor on the degree of baroreflex engagement, but it seems to reflect an inherent feature of the way in which arterial baroreflex modulate the heart period.

Childhood neuronal ceroid-lipofuscinoses in Argentina

We report on 30 cases of neuronal ceroid lipofuscinoses (NCL), mainly diagnosed in 1985-1993 in Argentina, whose population is predominantly of European descent. Twenty-four cases were late infantile Jansky-Bielschowsky (LINCL) and 6 were juvenile Spielmeyer-Vogt (JNCL). Sex ratio was female:male, 20:10. Age range and mean at onset and at diagnosis for the LINCL cases were 1-6 years, mean 3.1, and 2-11 years, mean 5.5, and for the JNCL cases, 5-9 years, mean 7, and 9-18 years, mean 13, respectively. Cases were referred for biopsy after neurological examination, and most included complete electrophysiological [electroencephalography (EEG) with photic stimulation, electroretinography (ERG), and visual-evoked potential (VEP)], neuroimaging, and neurometabolic investigation. NCL was the first suspected clinical diagnosis, followed by mitochondrial encephalopathy in some cases of recent onset. Except for 1 case, clinical findings were homogeneous in LINCL, characterized by refractive epilepsy, mental regression and progressive deterioration, ataxia, myoclonia, and visual loss. Abnormal VEP, ERG, and EEG, with polyphasic high-voltage spikes when photic stimulation was performed at low frequency, were observed. Visual impairment and retinitis pigmentosa were early manifestations in 4/6 JNCL, followed by mental abnormalities, motor deterioration, and myoclonic jerks, while 2/4 followed an atypical course. In both variants inheritance was autosomal-recessive. Five out of 27 families had more than 1 affected member, 3 of whom were included in our series. Diagnosis was initially performed in conjunctival biopsy in 3 cases, skin in 5, muscle in 17, and brain in 5, though most cases had a concomitant biopsy from another tissue including nerve, and there was a single brain autopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute "axonal" Guillain-Barré syndrome in childhood

We identified 5 of 44 consecutive children (11%) with Guillain-Barré syndrome who had electrophysiologic evidence of severe reduction of the mean amplitude of the compound motor action potentials (mean CMAP amplitude < 10% of lower limit of normal). EMG studies revealed profuse fibrillation activity in distal and proximal muscles after 2 weeks of onset. We compared this group with 16 consecutive children with GBS prospectively evaluated over 1 year, all of whom presented a mean CMAP amplitude > 10% of lower limit of normal. Children in the first group were more likely to require assisted ventilation (60% vs. 6.2%) and were more frequently quadriplegic at the peak of their disability (80% vs. 18.7%). They also required longer periods to improve one functional grade (mean 63.6 days vs. 16.6 days) and to become ambulatory (mean 156 days vs. 17.6 days). Moreover, only the children in the first group had distal atrophy of four limbs after 1 year of follow-up. Severe reduction of the mean amplitude of the CMAPs in children with GBS identifies a subgroup of patients with axonal damage that produces more severe weakness and delayed recovery.

Physiological unloading of cardiopulmonary mechanoreceptors by posture change does not influence the pressor response to isometric exercise in healthy humans

In recent studies in humans the role of cardiopulmonary baroreflexes in modulating the cardiovascular responses to isometric exercise (somatic pressor reflex) has been investigated by performing static handgrip exercise during deactivation of cardiopulmonary receptors produced by low levels of lower body negative pressure; however, findings from these studies have not been consistent. The purpose of this study was to investigate whether a more physiological unloading stimulus of cardiopulmonary baroreceptors, obtained by sequentially changing posture, could influence the pressor response to somatic afferent stimulation induced by isometric exercise. To accomplish this, ten healthy subjects performed a 2-min isometric handgrip (IHG) at 30% maximal voluntary contraction after 10 min of supine rest and, in rapid sequence, after 10 min of sitting and 10 min of standing, at the time when, owing to their transitory nature, the cardiovascular effects, due to arterial baroreceptor intervention should have been minimal. During IHG arterial pressure (BPa) was continuously and noninvasively measured to quantify accurately the blood pressure response to IHG both in magnitude and time course. Results showed that the pressor response to IHG was not significantly influenced by change in posture, either in magnitude or in time course. The mean arterial pressure increased by 17.4 (SEM 2.5), 18.6 (SEM 1.2) and 17.0 (SEM 1.3) mmHg in supine, sitting and standing [2.3 (SEM 0.3), 2.5 (SEM 0.2) and 2.3 (SEM 0.2) kPa] positions, respectively. Also the heart rate response to IHG was unaffected by change in posture.(ABSTRACT TRUNCATED AT 250 WORDS)

Scintigraphic assessment of "effort" axillary-subclavian vein thrombosis

"Effort" axillary-subclavian vein thrombosis (Paget-Schroetter syndrome) is an uncommon deep venous thrombosis due to repetitive activity of the upper limb. Clinical suspicion is usually confirmed by contrast venography. This report describes a case where the diagnosis was made by radionuclide venography (Tc-99m DTPA). The examination was carried out in the acute phase and clearly demonstrated the presence and the site of the obstruction as well as the collateral vessels. Despite a complete clinical recovery, obtained by medical therapy, further examinations performed in the follow-up period showed persistence of the thrombotic obstruction and a rich development of collateral vessels. In the authors' opinion, radionuclide venography is worth considering as a first-choice procedure when an axillary-subclavian vein thrombosis is suspected, and contrast venography should be performed only when surgical treatment is indicated.

[The physiopathological aspects and new therapeutic approaches in cardiac-circulatory failure]

Pathophysiological mechanisms are reviewed concerning the onset and the perpetuation of the clinical features of congestive heart failure. This syndrome is a severe condition of poor prognosis and bad life quality which in the last decades has reached, in the western industrial countries, the highest levels of general mortality, mainly due to the high prevalence of hypertensive and ischaemic myocardiopathies in the last years. To the clinical features of heart failure mainly contributes a deregulation of the physiological compensatory mechanisms contemporarily and concurrently activated following the primary deficiency of the heart pump function. In physiological conditions, following the myogenic adapting mechanisms reflex mechanisms intervene, activated by intracardiac and aortic and carotid-sinus mechanoreceptors following the variations in intracardiac and intravascular pressure and generally evoking negative feed-back effects. In patients with heart failure arterial high pressure mechanoreceptors respond to the reduction in effective arterial pressure thus provoking a deactivation of the tonic inhibition on the sympathetic cardiovascular drive. This leads to an activation of peripheral and renal vasoconstrictor tone, to a raised medullary catecholamine incretion, to heart rate and inotropism stimulation, and to an increase in pituitary gland ADH production as well as to an activation of renin-angiotensin-aldosterone system (RAAS). Analogous vasoconstrictive, and sodium and water retentive effects can be elicited by endothelin produced by endothelial cells and found in high plasma levels in CHF. These excitatory effects, leading to a rise in systemic vascular resistance and to hydro-electrolytic retention with volume expansion, are not efficiently counteracted by the opposite effects triggered by cardiopulmonary vagally mediated mechanoreceptors activated by the raised cardiac filling pressure and leading to sympathetic nervous inhibition, peripheral and renal vasodilation, ADH and RAAS inhibition. Analogous effects should be provoked by the raised production, due to enhanced heart wall distension, of atrial natriuretic factor leading to vasodilation, natriuresis and diuresis. Reduced sensitivity of cardiopulmonary baroreceptors and lowered production of ANF due to structural cardiac changes could represent, according to most opinions, the main factors responsible for the prevailing sympathetic activation and hydro-saline retention in CHF. The activation of cardiopulmonary sympathetic positive-feed back afferents, could be also involved in the characteristic alteration of the vago-sympathetic balance in heart failure. The persistent reduction in heart pump function could lead to the instauration of vicious circles among the various regulatory systems and create an overcompensation condition.(ABSTRACT TRUNCATED AT 400 WORDS)

[Integrated cardiorespiratory changes induced by chemical stimulation of muscular receptors]

Muscular exercise is accompanied by evident and perfectly matched cardiovascular and respiratory adjustments to avoid changes in arterial blood gases. The mechanisms responsible for this perfect regulation have not yet been defined. Our previous experimental investigations have shown that a consistent rate of cardiorespiratory reflex responses to exercise is caused by chemosensitive muscular receptors activation. The 2 different types of classical muscular exercise (rhythmic and isometric exercise) are joined with the 2 different patterns of cardiorespiratory reflex responses attributed in our opinion to the activation of 2 different kinds of muscle receptors (K and P). It has been observed that the increase in ventilation (VE), elicited by activation of both types of chemoreceptors during muscular experimental exercise is not accompanied by significant variations of partial pressure of CO2 (PaCO2) in the arterial blood (isocapnic hyperpnea). This suggest that muscular chemoreceptor activation during physical exercise determines an adequate cardiopulmonary matching. The main purpose of the present study has been to verify, in anesthetized rabbits, if also the chemical activation of muscular receptors was able to evoke reflexly an adequate degree of cardiopulmonary matching. The ventilation reflex changes and the concomitant variations of PaCO2 induced by injection of bradikinin (BK 250 ng) and hypertonic solutions (NaCl 10% 1 ml) in femoral artery have been evaluated in 10 anesthetized rabbits. The PaCO2 modifications observed during reflex hyperpnea have been compared with those recorded during hyperpnea induced by artificial ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Active specific immunotherapy with antiidiotypic antibodies in patients with solid tumors

Tumor-associated antigens (TAA) provide appropriate targets for selective manipulation of the patient's immune response in the immunotherapy of cancer. Active specific immunotherapy utilizing antiidiotypic antibodies to anti-TAA antibodies has been implemented in phase I clinical trials both in patients with colorectal carcinoma and in those with melanoma. The theoretical basis for immunotherapy with antiidiotypic antibodies, the results of these clinical trials, and an evaluation of appropriate parameters for future clinical trials of active specific immunotherapy with antiidiotypic antibodies in patients with solid tumors are reviewed.

[Bone echinococcosis]

Hydatidosis of the bone is a rare form of human echinococcosis. Due to the clinical, diagnostic, therapeutic and prognostic problems involved, the costal and occipital locations are of particular interest. Both are rare and differ from visceral locations in that they are always "primary" and have the capacity to destroy the bone matrix and infiltrate the adjacent tissues. The course of the disease is particularly slow and without specific signs and symptoms so that it can look like any bone condition. Laboratory tests are frequently negative and not wholly specific. While some authors claim that the radiological picture is of no diagnostic significance, others state that it offers pathognomonic signs. Diagnosis will be obtained through the combined assessment of clinical, radiological, laboratory and anamnestic data. Provenance from a rural area should reinforce the suspicion. Surgery, whether radical or conservative, is the key factor in treatment though local recurrences are common. Better results are obtained by combining surgery with Mebendazole for pre and postoperative prophylaxis. Large doses over a long period will give a better clinical course and reduce the incidence of recurrences. The prognosis is good for both sites as long as surgical treatment is given in good time.

[Muscular and subcutaneous hydatidosis]

Among unusual echinococcus cysts, muscular hydatidosis merits particular attention. Careful analysis of the statistics provided by the literature shows that the condition is not all that rare: its incidence varies from 0.5 to 4.7%, making it less common than hepatic or pulmonary cysts but more frequent than cysts of the kidneys, bone, pancreas, spleen or mesenterium. There are disagreements about the percentage distribution in the various muscular districts but it seems that the incidence gradually decreases as we go from the muscles of the torso and the root of the limbs to the distal extremities. The Palermo University case series includes 6 cases of which 5 muscular and one in the connective tissue. Of the 4 muscular cases, only one is to be considered secondary. For the purposes of correct preoperative diagnosis we should not neglect either anamnestic data or laboratory tests. Though the latter are not specific they are helpful for differential diagnosis from other muscular neoformation. Exploratory centesis that must be performed very cautiously in order to prevent dissemination appears to be more specific. Radiography and ultrasound examinations permit the direct study of cystic formations and a general assessment of the possibility of multiple hydatid locations. The only possible treatment is surgical. Though total removal of the cyst is the operation of choice, this is not always possible if the cyst is very big and adhering to other structures. In this case the procedure to be adopted is sterilisation and aspiration of the content, removal of the membrane and treatment of the pericystium.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiorespiratory reflexes from muscles during dynamic and static exercise in the dog

Cardiorespiratory reflex responses during the initial phase of dynamic and static contraction of hindlimb muscles were studied in anesthetized dogs. Muscle contractions were elicited by stimulating the femoral and gastrocnemius nerves at 3 and 100 Hz with the intensity of 2.0-2.5 times the motor threshold for a 20-s period. Rhythmic contractions caused a decrease in arterial pressure (Pa) and heart rate (HR) and increased pulmonary ventilation (VE) by increasing frequency (f) without significantly changing VT. Tetanic contractions provoked an increase in Pa and HR and a hyperpnea resulting from a rise in both f and VT. Similar responses were also obtained in anesthetized dogs with carotid sinuses denervated and cervical vagi cut. The abrupt increase in VE at the start of both types of exercise was not associated with immediate significant decreases in end-tidal CO2 values. These two patterns of cardiocirculatory and respiratory responses were closely similar to those reported in anesthetized rabbits in previous studies. Both patterns of responses were reflexes initiated by activation of muscle receptors verified by interrupting the afferents from the contracting muscles. It is concluded that, during dynamic and static work, two distinct muscular reflex mechanisms might exert their drives, related to the muscular metabolic rate, on the circulatory and respiratory function.

Evidence that nitroarene metabolites form mutagenic adducts with DNA-adenine as well as with DNA-guanine

Nitropyrenes as well as several other nitroarenes and their metabolites exhibit considerable mutagenicity for Salmonella tester strains (TA102 and TA96) which have adenine-thymine base pairs at the mutational target. This finding is unexpected as previous biochemical studies had shown that arylation at the C8 position of DNA-guanine is the only chemically and biologically significant reaction. This conclusion is supported by the extraordinary mutagenic potency of these chemicals in Salmonella strains with guanine at the mutational site (e.g., TA98). The present results indicate that a minor reaction with DNA-adenine may result in the formation of an unusually potent promutagenic DNA adduct.

Different patterns of respiratory reflexes originating in exercising muscle

In anesthetized rabbits, rhythmic contractions of the gastrocnemius muscle elicited by stimulating the gastrocnemius nerves (40 trains/min of 0.5-ms rectangular pulses at 2.0-2.5 mult of motor threshold), increased pulmonary ventilation by increasing frequency (f). Expiratory duration (TE) was greatly reduced, while inspiratory time (TI) was much less changed. Mean expiratory flow (VT/TE) was increased consistently more than mean inspiratory flow (VT/TI). Arterial pressure (Pa) and heart rate (HR) were decreased. During tetanic contractions (100 Hz, 2.0-2.5 X T) tidal volume (VT) increased considerably more and f considerably less than during rhythmic exercise, TE was shortened, and TI was only slightly affected. Pa and HR, after a transitory reduction, increased over the resting levels. Similar responses were also obtained in deafferented rabbits with carotid sinus, aortic, and cervical vagus nerves cut. These two patterns of cardiorespiratory changes were initiated by activation of muscle receptors verified by interrupting the afferents from the contracting muscles. It is concluded that, in the anesthetized rabbit, two different muscular reflex mechanisms are involved in controlling the pattern of breathing and ventilation during muscular exercise. One mechanism, predominantly activated during dynamic exercise, decreases TE and increases f, the other mechanism, mainly activated during static exercise, increases the inspiratory drive, thus increasing the depth of breathing.

[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.

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.