Baroreflex contribution to blood pressure and heart rate oscillations: time scales, time-variant characteristics and nonlinearities

The aim of this paper is to highlight the aspects of the baroreflex control of the cardiovascular system that could be relevant to the analysis and modelling of cardiovascular oscillations and regulation. In particular, complex and/or controversial issues of the baroreflex control are addressed on the basis of results obtained in previous studies by others as well as by our group. Attention has been focused on time-variant and nonlinear characteristics of the baroreflex function and on the influence of this physiological mechanism on different frequency regions of blood pressure and heart rate spectra.

Identification, molecular biotyping and ultrastructural studies of bacterial communities isolated from two damaged frescoes of St Damian's Monastery in Assisi

AIM

To investigate the composition of the microbial community in biodeterioration of two frescoes in St Damian's Monastery in Assisi.

METHODS AND RESULTS

A total of 1292 colonies were isolated from the most deteriorated parts, analysed by microbiological, biomolecular and ultrastructural techniques, and taxonomically classified. Molecular biotyping of Staphylococcus cohnii colonies, one of the most prevalent bacterial species, showed a very restricted genome diversity while Bacillus licheniformis were very homogeneous by RFLP, tDNA-PCR and random-amplified polymorphic DNA. Electron microscopy confirmed heterogeneity of the bacterial population in the different sampling areas.

CONCLUSIONS

Several of the identified species are widespread in the soil or saprophytes of human skin. Although unable to demonstrate that they are involved in biodeterioration, they may represent trophic elements contributing to fungi-related chromatic alterations when adequate environmental conditions occur. Deterioration may in part be prevented or controlled by adequate air filtering or conditioning of the room.

Nitric oxide-dependent vasodilation and the regulation of arterial blood pressure

Conflicting evidence has been reported on the hypothesis that vascular nitric oxide (NO) release is modulated by autonomic influences. Another controversial question is whether an insufficient degree of NO-dependent vasodilation may play a contributory role in the genesis of arterial hypertension. To address these questions we evaluated NO-dependent vasodilation in conscious rats subjected to various experimental manipulations that interfere with autonomic function: chronic chemical sympathectomy (CCSx), acute ganglionic blockade (AGx) and chronic sinoaortic denervation (CSAD). Experiments were also carried out on 6- and 12-week-old spontaneously hypertensive rats (SHR) (i.e. during the pre-hypertensive and the early established hypertensive stage) and in age-matched Wistar-Kyoto (WKY) rats. Nitric oxide-dependent vasodilation was quantified from the extent of blood pressure (BP) elevation in response to acute inhibition of NO synthesis by L-nitromonomethyl-L-arginine (L-NMMA). Chronic chemical sympathectomy was produced by repeated 6-hydroxydopamine injections; AGx was induced by hexamethonium infusion; and CSAD was obtained by aortic nerve section and carotid sinus wall stripping. Nitric oxide synthesis inhibition by L-NMMA was followed by a marked BP elevation in all groups. Rats with CCSx, Agx or CSAD never showed reduced BP responses to L-NMMA compared to intact, control rats. Neither 6- nor 12-week-old SHR had attenuated pressor responses to L-NMMA compared to age-matched WKY rats. In conclusion, the data indicate that (i) in unanaesthetized quietly-behaving rats there is no significant modulation of NO release by autonomic influences and (ii) young SHR have unimpaired NO-dependent vasodilation so it is unlikely that a deficit of vascular NO release plays any etiologic role in the BP elevation of this experimental model.

Evidence for the involvement of phosphatidylinositol 3-kinase in fMLP-stimulated neutrophil adhesion to ICAM-1-transfected cells

Phosphatidylinositol 3-kinase (PI-3K) controls important intracellular steps involved in inflammation, immunity, and cell growth. PI-3K also modulates leukocyte integrin adhesiveness. In this study we evaluated the role of PI-3K on neutrophil adhesion to intercellular adhesion molecule-1 (ICAM-1)-transfected cells. N-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated neutrophil adhesion was inhibited by wortmannin and LY294002, two unrelated PI-3K inhibitors, whereas phorbol myristate acetate (PMA)-induced neutrophil adhesion was not inhibited by them. After fMLP stimulation, a rapid activation of AKT and ERK was observed. However, only activation of AKT was reversed by the PI-3K inhibitors. Neutrophil expression of the beta2-integrins Mac-1, lymphocyte function-associated antigen-1(LFA-1), and gp150.95 was not affected by wortmannin, nor was expression of the activation epitope recognized by MAB24. We conclude that (a) PI-3K is involved in fMLP-activated neutrophil adhesion to ICAM-1-transfected cells, (b) the mechanism involved is not mediated by the modulation of beta2-integrin expression or activation, and (c) another mechanism seems to involve the adhesion to ICAM-1 when a cellular system of adhesion is used.

Correlation between the immune response elicited in rabbits by env-recombinant avipox vaccines and the inhibition of HIV-1-specific functions

The fine immunoreactivity of the rabbit humoral response elicited by four env-recombinant avipoxviruses and their ability to stimulate a memory T-cell response and a protective immunity have been studied. The antibody specificity was compared with the serum neutralizing activity and virus-specific T-cell proliferative response. Resistance to challenge by cell-associated HIV-1 was monitored by PCR. Canarypox (CP) and fowlpox (FP) constructs, containing the complete env gene (IS(+)) from the HIV-1(SF2) strain, induced a higher profile of epitope recognition than their counterparts expressing the env gene deleted of the putative immunosuppressive region (IS(-)). Serum neutralizing activity was in agreement with fusion inhibition and lymphoproliferative response in rabbits immunized with CPIS(+), and only partially with FPIS(+). Rabbits failed to be infected, but anti- p55 gag-specific antibodies could be demonstrated by Western blot. This study confirms the ability of these non-replicative live recombinant viruses to elicit a complete immune response, capable of inhibiting specific HIV-1 functions.

Altered blood pressure variability in patients with congestive heart failure

OBJECTIVE

Congestive heart failure (CHF) is characterized by sympathetic overactivity but reduced variability of heart interval and sympathetic nerve activity; little information exists, however, about the alterations in blood pressure variability in this syndrome, especially during excitatory manoeuvres such as tilting or exercise.

DESIGN AND METHODS

Nine patients with CHF (age 62+/-1 years, NYHA class II-III, ejection fraction 33+/-1%, peak VO2 14.1+/-3.2 ml/min per kg body weight [mean +/- SEM]) and eight healthy control subjects (age 58+/-1 years) with normal left ventricular function were studied. Blood pressure (Finapres), R-R interval (ECG) and respiration (nasal thermistor) were recorded during 15-min periods of supine rest, 70 degree head-up tilting, submaximal bicycling exercise and post-exercise recovery. Total variance and the power of the spectral components of blood pressure (HF, respiratory-related; LF, 0.03-0.14 Hz; and VLF, 0.02-0.003 Hz) were measured.

RESULTS

Compared with control subjects, CHF patients have, first, a normal overall blood pressure variability during supine rest but a failure to increase this variability in response to head-up tilt and exercise; second, a suppressed LF spectral component of blood pressure at rest and in response to head-up tilt and exercise; and third, reappearance of LF blood pressure power during postexercise recovery.

CONCLUSIONS

In CHF patients, overall blood pressure variability and its LF spectral component are altered at rest and during sympathoexcitatory manoeuvres. Somewhat paradoxically, however, the depressed LF blood pressure power is partially restored during a 15-min recovery period, indicating that at least part of the CHF-related alterations of blood pressure variability have the potential to revert back towards normal under appropriate physiological circumstances.

Nitric oxide dependent vasodilation in young spontaneously hypertensive rats

Conflicting evidence exists on the possible impairment of tonic nitric oxide (NO) mediated vasodilation as a causative factor in the genesis of human as well as experimental hypertension. We evaluated the tonic NO-dependent vasodilation from the pressor response to NO synthesis inhibition by NG-monomethyl-L-arginine (L-NMMA) in 9 conscious, chronically instrumented spontaneously hypertensive rats (SHR) at 12 weeks of age, ie, during the early established hypertensive stage. Nine age-matched Wistar-Kyoto rats (WKY) were used as controls. The pressor responses to L-NMMA (100 mg . kg-1 IV bolus plus 1.5 mg . kg-1 . min-1 infusion for 60 minutes) as well as to non NO-dependent pressor stimuli, namely, vasopressin (2, 4, and 8 ng . kg-1) and phenylephrine (0.5, 1, and 2 microg . kg-1) given as IV boluses, were assessed both under control conditions and during suppression of autonomic reflexes by hexamethonium (30 mg . kg-1 IV bolus+1.5 mg . kg-1 . min-1 infusion). Rather than being reduced, the pressor responses to L-NMMA were 39% and 71% larger in the control and areflexic conditions, respectively, than those observed in WKY (both P<0.01). A similar pattern was observed for the pressor responses to vasopressin (+37% and +68% in the control and areflexic conditions, respectively; both P<0.01) and phenylephrine, (+20% and +52%; both P<0.05). Additional groups of 6-week-old prehypertensive SHR (n=11) and age-matched WKY (n=11) were subjected to an identical protocol: in these animals, the pressor responses to L-NMMA were similar in each strain, as were the pressor responses to vasopressin and phenylephrine in both control and areflexic conditions. In conclusion, our observations indicate that during the developmental phase of hypertension in the SHR model, namely, during the prehypertensive as well as the early established hypertensive stage, NO-dependent vasodilation is preserved (if not enhanced) so that a putative impairment of this function provides no significant pathogenic contribution to the onset of hypertension in this experimental model.

Genetic variation in a human immunodeficiency virus type 2 live-virus Macaca nemestrina vaccine model

Four pigtailed macaques were inoculated with an infectious, apathogenic human immunodeficiency virus type 2 (HIV-2) molecular clone (HIV-2KR) and subsequently challenged with a highly pathogenic strain, HIV-2287, together with two naive control animals. After challenge, two animals inoculated with a high dose of the immunizing strain were protected from CD4 decline and immunodeficiency. To examine the role of genetic heterogeneity in protection, fragments of the env gene were amplified from peripheral blood mononuclear cell DNA and plasma RNA of challenged animals by PCR, examined by using a heteroduplex tracking assay (HTA), and sequenced. By HTA, variation was detected principally within the V1 and V2 regions of envelope. Extent of variation in viral DNA clones as assessed by HTA correlated with inoculum size, as did the degree of variation in sequences of clones derived from viral DNA. Conversely, a rapid reduction in the number of plasma viral RNA variants was noted by HTA at 8 weeks postinfection in protected animals; this reduction was not present in naive or unprotected macaques. Sequences derived from plasma viral RNA were found to be more closely related than corresponding viral DNA sequences, and protection correlated with a significant reduction in variation in plasma RNA sequences in animals given the identical inocula of HIV-2287. Nonsynonymous mutations were significantly less prevalent in the protected animals. An additional potential glycosylation site was predicted to be present in the V2 region in all but one clone, and amino acid signatures related to protection were identified in viral DNA and RNA clones within both the V1 and V2 regions. Examination of the role of viral variation in this HIV-2 live-virus vaccine model may provide valuable insights into immunopathogenesis.

beta-chemokines and neutralizing antibody titers correlate with sterilizing immunity generated in HIV-1 vaccinated macaques

One of the obstacles to AIDS vaccine development is the variability of HIV-1 within individuals and within infected populations, enabling viral escape from highly specific vaccine induced immune responses. An understanding of the different immune mechanisms capable of inhibiting HIV infection may be of benefit in the eventual design of vaccines effective against HIV-1 variants. To study this we first compared the immune responses induced in Rhesus monkeys by using two different immunization strategies based on the same vaccine strain of HIV-1. We then utilized a chimeric simian/HIV that expressed the envelope of a dual tropic HIV-1 escape variant isolated from a later time point from the same patient from which the vaccine strain was isolated. Upon challenge, one vaccine group was completely protected from infection, whereas all of the other vaccinees and controls became infected. Protected macaques developed highest titers of heterologous neutralizing antibodies, and consistently elevated HIV-1-specific T helper responses. Furthermore, only protected animals had markedly increased concentrations of RANTES, macrophage inflammatory proteins 1alpha and 1beta produced by circulating CD8(+) T cells. These results suggest that vaccine strategies that induce multiple effector mechanisms in concert with beta-chemokines may be desired in the generation of protective immune responses by HIV-1 vaccines.

Cardiovascular autonomic testing in adolescents with type I (insulin-dependent) diabetes mellitus: an 18-month follow-up study

1. Autonomic abnormalities are frequent in adult patients with diabetes mellitus and progress slowly; little is known about frequency and progression of autonomic abnormalities in childhood. 2. To assess whether autonomic abnormalities are already present in childhood, we evaluated the cardiovascular reflexes, the spectral analysis of spontaneous fluctuations in RR interval and blood pressure (low- and high-frequency), and the baroreflex sensitivity at rest, and after vagal (controlled breathing) and sympathetic activation (tilting) in 25 adolescents with Type I diabetes mellitus, aged 10-17 years, at baseline and after 18 months follow-up, and in 20 age- and sex-matched controls. 3. Cardiovascular reflexes were similar in both patients and controls. Similar significant changes in percentage low- and high-frequency (P < 0.005) from rest to tilting and to control breathing were observed in both patients and controls. The baroreflex sensitivity was also similar in patients and controls. Mild and non-systematic correlations were observed between autonomic tests and disease duration or metabolic control. After 18 months follow-up no changes were observed in any of the measured variables. Correlations with metabolic control remained unchanged. 4. These results indicate a substantial stability of cardiovascular autonomic function in childhood diabetes, and suggest that autonomic abnormalities are likely to develop at an older age.

A minimally replicative HIV-2 live-virus vaccine protects M. nemestrina from disease after HIV-2(287) challenge

M. nemestrina immunized with an apathogenic HIV-2 molecular clone (HIV-2KR) were protected from CD4 decline and disease upon challenge with HIV-2(287), after any immunizing virus could be detected. Higher but not lower inocula of HIV-2KR were protective against intravenous inoculation of either 10(5) or 10(1) TCID50 of HIV-2(287). Protected animals displayed substantial reductions in PBMC proviral burden (1-3 logs), viral titers (1-2 logs), and plasma viral RNA (2-4 logs) compared to unprotected or naive animals as early as 1 week postinfection. Plasma viral RNA became undetectable after 24 weeks in protected animals, but remained high in unprotected animals. No viral RNA was present in the spleen of the protected animal necropsied more than a year after challenge (though viral DNA was still present). No neutralizing responses could be demonstrated, but CTL activity was detected sooner and at higher levels after challenge in protected than in unprotected macaques. In this novel HIV-2 vaccine model, protection was clearly dose-dependent, and clearance of challenge virus RNA from the plasma did not require detectable ongoing replication of the immunizing virus at the time of challenge.

Lack of autonomic contributions to tonic nitric oxide-mediated vasodilatation in unanesthetized free-moving rats

OBJECTIVE

To clarify the controversial issue of whether autonomic influences modulate vascular nitric oxide-mediated vasodilatation or even directly contribute to production of nitric oxide (NO) via nitroxidergic fibers.

METHODS

Chronic venous and arterial catheters were implanted in Wistar-Kyoto rats (n = 65) for continuous blood pressure measurement, drug administration and blood sampling. Tonic NO-dependent vasodilatation in the conscious free-moving animal was evaluated as the pressor response to inhibition of NO synthesis by intravenous L-monomethylarginine (a 100 mg/kg intravenous bolus plus 0.5 mg/kg per min infusion for 30 min). Experiments were performed under control conditions, chemical sympathectomy by 6-hydroxy-dopamine, ganglionic blockade by hexamethonium, and surgical denervation of sino-aortic baroreceptors.

RESULTS

Baseline mean arterial pressure was 100+/-4 mmHg (mean +/- SEM) in control rats and 73+/-3, 62+/-5, and 105+/-10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. The peak increase in mean arterial pressure after administration of L-monomethylarginine was 38+/-3 mmHg in control rats and 51+/-3, 50+/-6, and 63+/-10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. Epinephrine and norepinephrine levels in rats of separate groups of unanesthetized control, sympathectomized and ganglion-blocked animals were measured by high-performance liquid chromatography from an arterial blood sample, the results indicating drastic reductions in levels of both catecholamines in the ganglion-blocked (but not in the sympathectomized) rats compared with those in the control rats.

CONCLUSIONS

Tonic NO-dependent vasodilatation can normally be maintained in the unanesthetized unrestrained rat irrespective of autonomic or humoral adrenergic influences.

Characterization of a molecular clone of HIV type 2 infectious for Macaca nemestrina

A lambda phage clone containing a full-length HIV-2 provirus, designated HIV-2KR, was obtained from the genomic DNA of Molt4 clone 8 (Molt4/8) lymphoblastic cells infected with the HIV-2PEI2 strain. HIV-2KR is genetically distinct from known HIV-2 isolates, possessing both a unique deletion in the LTR promoter region, and a long rev reading frame. It is replication competent in vitro after transfection into Molt4/8 cells, replicates in a variety of established human T lymphoblastic (Molt-3, Molt4/8, SupT1, H9, C8166) and myelomonocytic (U937) cell lines, and displays prominent cytopathic effects on infection of Molt4/8 cells, reflecting usage of both CCR5 and CXCR4 coreceptors. In addition, HIV-2KR was found to be infectious for human and Macaca nemestrina peripheral blood lymphocytes, and primary human monocyte-macrophage cultures. Intravenous inoculation of cell-free virus into M. nemestrina resulted in infection characterized by transient, low-level viremia and modest temporary decline in CD4 lymphocyte numbers, making HIV-2KR the first HIV-2 molecular clone reported to be infectious for this primate species.

Soluble E-selectin and intercellular adhesion molecule-1 plasma levels increase during acute myocardial infarction

Previous studies have shown that adhesion molecules play a crucial role in leukocyte-endothelium interactions that occur during myocardial ischemia and reperfusion. We assessed the plasma levels of the soluble form of E-selectin (sE-selectin) and intercellular adhesion molecule-1 (sICAM-1) in 15 patients with acute myocardial infarction (AMI) and in 15 controls with chronic stable angina. In patients with AMI, the levels of sE-selectin and sICAM-1 increased significantly during the first 8 h after infarction and subsequently decreased. Soluble E-selectin levels were inversely related to the peak plasma levels of creatine kinase-MB (CK-MB), and the time course of their appearance in plasma correlated with that of neutrophil count and plasma D-dimer. In individual patients, peak and mean sICAM-1 levels correlated respectively with plasma D-dimer concentrations and monocyte count, but no correlation were found when their time courses were analyzed. Eight hours after symptom onset, the mean plasma sE-selectin levels were higher in patients with AMI than in those with stable angina, whereas no significant differences were found in mean plasma sICAM-1 levels between the two groups at every time analyzed. In the acute phase of MI (a) sE-selectin and sICAM-1 levels increase during the first 8 h and subsequently decrease; (b) the increase in sE-selectin probably reflects activation of endothelial cells, correlates with other inflammatory and coagulation parameters, and is inversely related to the degree of myocardial damage; and (c) sICAM-1 plasma levels do not represent a good marker of "cell activation" because they reflect activation of different cells and may be affected by different conditions.

Expression and immunogenicity of V3 loop epitopes of HIV-1, isolates SC and WMJ2, inserted in Salmonella flagellin

Synthetic oligonucleotides corresponding to specific V3 loop portions of two HIV-1 isolates, SC and WMJ2, were expressed in the flagella of a Salmonella live-vaccine strain. Expression of the inserted epitopes in flagellin and their exposure at the surface of flagellar filaments were shown by immunoblotting and immunogold labeling with anti-flagellin (Salmonella d) and anti-HIV-1(IIIB) V3 loop peptide sera. Live recombinant Salmonella strains expressing either one of the two V3 loop inserts were administered intraperitoneally to BALB/c mice. All these animals developed antibodies specific for the heterologous glycoprotein 120 (gp120) of HIV-1 MN strain, as detected by enzyme-linked immunosorbent assays (ELISA), two of the sera had neutralizing activity against the heterologous HIV-1 MN strain. Moreover, oral administration of the live Salmonella recombinant strains to mice evoked specific IgA directed against gp120.

Simvastatin modulates the heat shock response and cytotoxicity mediated by oxidized LDL in cultured human endothelial smooth muscle cells

Oxidized low density lipoproteins (OxLDL) are toxic to cells of the arterial wall and trigger the expression of the inducible form of hsp 70 in cultured endothelial cells (EAhy-926) and smooth muscle cells (HUVSMC). The latter response is believed to protect cells from toxicity since heat shock protein 70 (hsp70) is synthesized by cells under stress condition to protect proteins from irreversible denaturation. Simvastatin (10(-8) M to 10(-5) M), a competitive inhibitor of hydroxy methyl glutaryl coenzyme A reductase (HMG-CoA reductase), a key enzyme in cholesterol biosynthesis, enhanced the toxicity of OxLDL (300 micrograms/mL) to endothelial cells and smooth muscle cells in a dose-dependent manner, as detected by 3H-adenine release and the MTT test. In EAhy, 3H-adenine release with OxLDL was 0.419 +/- 0.048 (ratio of radioactivity released in the medium to total radioactivity) versus 0.337 +/- 0.008 of control; in the presence of simvastatin and OxLDL this value increased from 0.49 +/- 0.01 at 10(-8) M to 0.918 +/- 0.001 at 10(-5) M with simvastatin alone (10(-5) M) this value was 0.463 +/- 0.025. Furthermore simvastatin reduced in a dose-dependent manner the expression of hsp 70 triggered by OxLDL, as detected by immunoblotting. To address whether this finding was due to the effect of simvastatin on the cholesterol pathway, mevalonate (100 microM) was used to bypass the HMG-CoA reductase block. This compound completely prevented the enhancement of OxLDL toxicity by simvastatin and restored the expression of hsp70. To verify whether cholesterol synthesis was required for the induction of hsp70 by OxLDL, squalestatin I (25 nM to 100 nM), an inhibitor of squalene synthase, another key enzyme of the cholesterol pathway, was used: OxLDL toxicity and hsp70 expression were not affected by this compound. These results indicate that simvastatin increases OxLDL cytotoxicity in vitro with a concomitant decrease of hsp70 expression triggered by OxLDL and that the key step in the cholesterol synthesis responsible for these effects must be between mevalonate and squalene formation.

Cardiovascular reflex changes preceding episodes of vasovagal syncope in paediatric subjects

1. The cardiovascular reflex changes preceding episodes of vasovagal syncope (VVS) in paediatric age were investigated in 12 subjects and in 20 controls, supine and upright, by spectral analysis of RR interval, respiration, systolic and diastolic blood pressure. 2. The sympatho-vagal control on the heart and blood pressure was assessed by the power of the low- (LF: index of sympathetic activity) and high-frequency oscillations (index of vagal activity to the heart). 3. In VVS group the supine blood pressure was lower than in controls and fell after tilt, while remained unchanged in controls. The blood pressure LF increased in control group during early and prolonged orthostasis, whereas in the VVS group the LF tended to decrease after early orthostasis and were not significantly greater than supine before VVS. 4. In the VVS group the sympathetic control of blood pressure appears reduced or ineffective, and progressively worsens before the VVS episode.

Physical training enhances sympathetic and parasympathetic control of heart rate and peripheral vessels in chronic heart failure

1. Physical training has been proposed to increase vagal control of heart rate in chronic heart failure. We studied the effects of physical training on cardiovascular control in 6 moderate to severe heart failure (NYHA II-III) patients and 6 age matched normal controls in a randomized controlled cross over trial (Training vs Detraining). 2. Five weeks training (20 min/day, 5 days/week bicycle exercise) increased peak VO2 in both C (from 31.2 +/- 1.4 to 37.7 +/- 2.4 ml/kg/min p < 0.01) and CHF patients (from 12.16 +/- 2.2 to 14.13 +/- 2 ml/kg/min p < 0.05). The sympathovagal control of heart rate and sympathetic control of the resistance vessels was assessed by the power of the oscillations (LF:0.03-0.15 Hz index of sympathetic activity, HF: 0.18-0.35 Hz index of vagal activity) in RR interval, blood pressure (systolic and diastolic by Finapres) and respiration by autoregressive spectral analysis, during free and controlled breathing (15b/min), in order to increase vagal activity. 3. T increased heart rate vagal control both in C (LF/HF ratio fb to cb: (D) 1.73 +/- 0.35 to 1.19 +/- 0.43 p = NS: (T) 2.9 +/- 1.2 to 1.13 +/- 0.3 p < 0.05) and in CHF patients (LF/HF ratio fb to cb: (D) 2.05 +/- 0.56 to 1.24 +/- 0.21 p = NS; (T) 2.6 +/- 0.89 to 0.87 +/- 0.15 p < 0.05; and in cb HF%: 36.2 +/- 2.7 (D) to 46.2 +/- 4.8 (T) p < 0.05). Before T, the sympathetic modulation of peripheral vessels (% LF compared to total variability) was depressed in CHF vs C (SBP: 9 +/- 2 vs 42 +/- 12% p < 0.05; DBP: 29 +/- 7 vs 55 +/- 31%, p < 0.05), and increased significantly after T in CHF (SBP from 9 +/- 2 (D) to 19 +/- 5% (T) p < 0.05; DBP from 29 +/- 7 to 41 +/- 11% (T) p < 0.05). This suggests an overall increase of autonomic control, both vagal on the heart and sympathetic on the peripheral vessels, in CHF by physical training.

[Anticoagulant-induced pseudo-thrombocytopenia: an important laboratory artifact]

In the medical unit of our regional hospital we observed eight cases of anticoagulant-related pseudothrombocytopenia within two years. Attention is drawn to this often misdiagnosed laboratory artefact. In every unexpected thrombocytopenia found by automatic cell-counting a simple blood smear should be studied especially for thrombocyte-aggregates and the automatic platelet-count should be repeated using another anticoagulant, before other investigations are undertaken.

Drug-induced in vitro inhibition of neutrophil-endothelial cell adhesion

1. Leukocyte-endothelial cell interactions play an important role during ischaemia-reperfusion events. Adhesion molecules are specifically implicated in this interaction process. 2. Since defibrotide has been shown to be an efficient drug in reducing damage due to ischaemia-reperfusion in many experimental models, we analysed the effect of defibrotide in vitro on leukocyte adhesion to endothelial cells in basal conditions and after their stimulation. 3. In basal conditions, defibrotide (1000 micrograms ml-1) partially inhibited leukocyte adhesion to endothelial cells by 17.3% +/- 3.6 (P < 0.05), and after endothelial cell stimulation (TNF-alpha, 500 u ml-1) or after leukocyte stimulation (fMLP, 10(-7) M), it inhibited leukocyte adhesion by 26.5% +/- 3.4 and 32.4% +/- 1.8, respectively (P < 0.05). 4. In adhesion blockage experiments, the use of the monoclonal antibody anti-CD31 (5 micrograms ml-1) did not demonstrate a significant inhibitory effect whereas use of the monoclonal antibody anti-LFA-1 (5 micrograms ml-1) significantly interfered with the effect of defibrotide. 5. This result was confirmed in NIH/3T3-ICAM-1 transfected cells. 6. We conclude that defibrotide is able to interfere with leukocyte adhesion to endothelial cells mainly in activated conditions and that the ICAM-1/LFA-1 adhesion system is involved in the defibrotide mechanism of action.

Autonomic control of skin microvessels: assessment by power spectrum of photoplethysmographic waves

1. Although it is well known that the microvessels of the skin constantly undergo spontaneous variations in volume, the significance of these rhythmic changes remains uncertain. 2. In 10 healthy males and in 15 patients in intensive care, we assessed the origin of the autonomic influences on spontaneous fluctuations in the microcirculation of the skin, obtained by an infra-red photoplethysmographic device; we used spectral analysis techniques to compare these fluctuations (which were recorded simultaneously in two sites) with those of blood pressure, in order to test the presence of autonomic control of any synchronous fluctuations in these different measurements from the cardiovascular system. In order to minimize mechanical fluctuations caused by occasional slow breaths, rather than nervously mediated fluctuations in skin blood flow, respiration was controlled at 15 breaths/min (0.25 Hz). 3. Spontaneous infra-red photoplethysmographic fluctuations were observed in different body areas (left index finger and left ear lobe, right and left index finger), and all were evident at 0.1 Hz, as well as respiration-related components at 0.25 Hz. Active standing increased the power of the 0.1 Hz fluctuations (sympathetic activity) in both blood pressure (from 62.7 +/- 7.1 to 79.2 +/- 3.7 normalized units, P < 0.05) and IRP (finger: from 68.5 +/- 6.4 to 86.9 +/- 3.4 normalized units, P < 0.05; ear: from 59.0 +/- 5.9 to 88.1 +/- 2.0, P < 0.01). There was a high (> 0.5) coherence between the fluctuations obtained in blood pressure, in IRP signals obtained simultaneously at the finger and at the ear, and in R-R interval. This synchronization between the oscillations in all these signals, which were unrelated to the respiratory frequency or to the pulse rate, suggests a common neural, non-local origin. The phase between IRP and blood pressure was positive in the 0.1 Hz region (+1.65 +/- 0.41 radians, i.e. IRP was leading blood pressure, showing that 0.1 Hz fluctuations were not passively transmitted to the skin microvessels from large arteries) and negative in the 0.25 Hz region (-0.74 +/- 0.19 radians, P < 0.01 compared with phase in the 0.1 Hz region, i.e. IRP was lagging behind blood pressure, suggesting possible passive transmission to the skin microvessels of blood pressure fluctuations caused by respiration). Fluctuations at lower frequency were observed in all IRP recordings, suggesting a local origin for these. Intra-arterial and IRP fluctuations were compared in the 15 intensive care patients and gave similar results. 4. The skin microcirculation is thus not only under local control, but also reflects changes in sympathetic activity; the effect of these changes on the skin microcirculation can be easily evaluated by the spectral analysis of the IRP signal obtained simultaneously in multiple areas, in conjunction with the spectra of R-R interval and blood pressure.

A new antisense tRNA construct for the genetic treatment of human immunodeficiency virus type 1 infection

Different strategies proposed in the literature to attempt gene therapy of AIDS are based mainly on the intracellular production of RNA and protein therapeutics. This report describes the construction and the anti-human immunodeficiency virus type 1 (HIV-1) activity of a new type of antisense tRNA directed against a nucleotide region in the first coding exon of HIV-1 tat (nucleotides 5924 to 5943; Los Alamos data bank) which is conserved among many HIV-1 clones. The anti-tat antisense sequence was inserted into a tRNA(Pro) backbone by replacement of the anticodon loop, without altering the tRNA canonic tetraloop structure. The antisense tRNA was able to interact effectively with its target in vitro. Jurkat cells that constitutively expressed the anti-tat tRNA following retroviral vector transduction exhibited significant resistance to HIV-1 de novo infection. Resistance seemed to correlate with the level of antisense expression. This is the first time that such a tRNA antisense strategy has been shown to be effective as a genetic treatment of HIV-1 infection in tissue culture. The construct design proposed in this report has some intrinsic advantages: the transcript is driven by a polymerase III promoter, the short length of the RNA minimizes effects of intramolecular base pairing that may impair target recognition, and the antisense RNA has the stability and intracellular fate of a native tRNA molecule.

Determinants of heart rate variability in heart transplanted subjects during physical exercise

Respiratory sinus arrhythmia has been described in heart transplanted subjects. In order to investigate the mechanisms involved in the generation of this condition in the transplanted heart and its evolution after surgery, graded exercise was performed (0-75 W in 25 W steps) on a cycle ergometer by 41 subjects (mean age 44 years) who had undergone heart transplantation 28 months (range 3-60) earlier and by six age matched-control subjects. R-R interval, respiratory signal, O2 consumption (VO2) and CO2 production (VCO2) were measured. Respiratory sinus arrhythmia was assessed by the autoregressive power spectrum of the R-R interval and respiration. All subjects reached the anaerobic threshold (heart transplants: 60% at 50 W, 40% at 75 W Controls: 150 W). In control subjects, the respiratory sinus arrhythmia was higher than in heart transplanted subjects (5.80 +/- 0.30 vs 1.45 +/- 0.16 1n ms2) and it decreased significantly (4.66 +/- 0.30 1n ms2, P < 0.05) during exercise, despite the increase in breathing rate and depth. When, the group of heart transplanted subjects was considered as a whole, respiratory sinus arrhythmia was found to be present in all conditions. It significantly increased at 25 W (from 1.45 +/- 0.16 to 2.00 +/- 0.17 1n ms2, P < 0.01), then significantly fell below baseline during recovery (to 0.97 +/- 0.23 1n ms2, P < 0.01). Multiple regression analysis showed that a linear combination of heart rate (inverse correlation) and VO2 (direct correlation) together with months having passed since transplantation surgery, could explain the observed changes in heart rate during exercise (multiple regression: r = 0.658, P < 0.0001). In five long-term transplanted subjects, non respiratory-related low frequency (0.1 Hz) waves were present on the R-R spectrum, but respiratory sinus arrhythmia is also present in the recently transplanted heart and depends on the opposing effects of ventilation and heart rate. In a few cases, sympathetic modulation (re-innervation) could not be excluded.

Autonomic and ventilatory components of heart rate and blood pressure variability in freely behaving rats

The relative role of parasympathetic, sympathetic, and ventilatory influences in the genesis of blood pressure and R-R interval variability is controversial. In 13 freely behaving WKY rats instrumented with venous and arterial catheters and chest electrodes, mean arterial pressure (MAP, mmHg), R-R interval (ms), and respiratory fluctuations were monitored for 90 min in the control condition and after intravenous atropine (0.75 mg/kg) and/or propranolol (1 mg/kg). Spectral power (pw) in the 0.25- to 0.75-Hz (midfrequency, MF) and the 0.75- to 3.0-Hz (high-frequency, HF, respiratory-synchronous) bands was computed in sequences of 400 heartbeats by use of a combined autoregressive analysis. Atropine reduced but did not abolish HF R-R interval pw (from 1.73 +/- 0.50 to 0.39 +/- 0.27 ms2, P < 0.01) and halved HF MAP pw (from 0.41 +/- 0.30 to 0.21 +/- 0.12 mmHg2, P < 0.05), whereas propranolol did not affect HF pw of the R-R interval or MAP. Propranolol also failed to significantly modify MF R-R interval pw (from 0.48 +/- 0.44 to 0.40 +/- 0.34 ms2, P = NS) or MF MAP pw (from 0.54 +/- 0.39 to 0.42 +/- 0.20 mmHg2, P = NS), whereas atropine virtually abolished MF R-R interval pw (from 0.48 +/- 0.44 to 0.01 +/- 0.01 ms2, P < 0.01) and also significantly reduced MF MAP pw (from 0.54 +/- 0.39 to 0.33 +/- 0.24 mmHg2, P < 0.01). The effects of combined blockade were similar to those of atropine alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Sympathectomy and cardiovascular spectral components in conscious normotensive rats

We examined the extent to which sympathetic influences are reflected by spectral powers of blood pressure and pulse interval in specific frequency bands in spontaneously behaving Wistar-Kyoto rats subjected to continuous intraarterial blood pressure recording. The rats were pretreated with 6-hydroxydopamine (150 mg/kg twice in 1 week, n = 19) to produce chemical sympathectomy or received vehicle (n = 15). In the sympathectomized group, additional monitoring sessions were performed with rats under alpha-adrenergic receptor blockade with phenoxybenzamine (n = 8), beta-receptor blockade with propranolol (n = 7), or cholinergic receptor blockade with atropine (n = 8). Blood pressure signals were analyzed by a computer to calculate spectral powers (fast Fourier transform) in the low-frequency (0.025 to 0.1 Hz), mid-frequency (0.1 to 0.6 Hz), and high-frequency (0.8 to 3.0 Hz) bands. In sympathectomized rats, low-frequency power of blood pressure was 70% greater than in intact rats, whereas mid-frequency power was 60% smaller (P < .05 for both) and high-frequency power was unchanged. High-frequency power of pulse interval was also unchanged in sympathectomized rats, whereas low- and mid-frequency powers were reduced by approximately 50% (P < .05). No further alterations in spectral powers were observed by adding alpha- or beta-adrenergic blockade to sympathectomy, whereas adding cholinergic blockade caused a striking reduction in all pulse interval powers. Thus, mid-frequency blood pressure power depends on sympathetic but also to a substantial extent on nonsympathetic influences. Sympathetic influences do not contribute to low-frequency blood pressure power, having instead a restraining effect. The low- and mid-frequency pulse interval powers depend on both sympathetic and vagal influences. Thus, no blood pressure or pulse interval power in the mid- and low-frequency ranges can be regarded as a specific marker of sympathetic activity.

Low-frequency spontaneous fluctuations of R-R interval and blood pressure in conscious humans: a baroreceptor or central phenomenon?

1. We have tested the hypothesis that the non-respiratory, low-frequency (around 0.1 Hz) fluctuations of heart rate variability are generated by the baroreflexes, but with a delay caused by the slower response of the efferent sympathetic arm, (compared with the vagus), in 11 healthy subjects (mean age +/- SD 27 +/- 5 years). 2. In random order, at the onset of 20 s of apnoea starting at end expiration, we applied either 600 ms neck suction (-40 mmHg) to the carotid sinus region, or no stimulus (anticipation control), or a loud whistle (alerting control), every 60 s, for 30 min. (i.e. 10 of each 'stimulus'). We recorded neck pressure, blood pressure (Finapres), R-R interval (ECG), infra-red plethysmographic skin blood flow and respiration (impedance). By subtracting the alerting response from the neck suction response we obtained the responses caused purely by baroreceptor stimulation. 3. The initial reflex bradycardia and hypotension was followed by arteriolar vasoconstriction, presumably due to recompensation by the baroreflex, and then by a further reflex bradycardia-producing a decaying oscillation of the R-R interval about the control R-R. The period of this damped oscillation was 0.103 +/- 0.024 Hz, similar to the frequency of the low-frequency peak obtained by power spectral analysis of heart rate variability (0.093 +/- 0.016 Hz, not significant) at rest. These two values were significantly correlated in individual subjects (r = 0.715, P < 0.025). 4. These findings support the hypothesis that the low-frequency waves of heart rate variability can be generated from baroreceptor sensed blood pressure fluctuations.

[Sacral chordoma: a consideration in low back pain]

We present the case of a sacral chordoma (S3-S5). Its diagnostic problems as well as its pathological properties and the epidemiologic situation are discussed. The therapy and the surgical procedure are outlined.

Inducible nitric oxide synthase modulates fibronectin production in the EA.hy926 cell line and cultured human umbilical vein endothelial cells

We wished to test the hypothesis of a connection existing between inducible nitric oxide (NO) synthesis and production of extracellular matrix proteins in endothelial cells (EC). We recently reported that the inducible-NO pathway contributes to cytokine-induced enhancement of tumor cell (TC) adhesion to cultured vascular endothelium, independent of changes in E-selectin expression on endothelial cells (EC). We now show that inducible NO-synthase is involved in enhancing fibronectin production by EC. Indeed, fibronectin synthesis and secretion increased both in the EA.hy926 EC line and in human umbilical vein EC (HUVEC) after prolonged exposure to tumor necrosis factor-alpha (TNF-alpha) or interferon-gamma (IFN-gamma). This effect was reversed by the reported inhibitor of NO synthase N omega-nitro-L-arginine methyl ester (L-NAME 10(-5) M). The two cytokines exerted no additive effect, suggesting that they trigger a common metabolic pathway. NO production by cytokine-stimulated EC was dependent on the inducible NO-pathway, as demonstrated by studies of EC-dependent inhibition of platelet aggregation. This inhibition was also evident in calcium-free medium and was reversed by L-NAME and by two inhibitors of protein synthesis that are reported to block the inducible-NO synthase, such as dexamethasone (Dex 10(-7) M) and cycloheximide (Chx 10(-6) M). We conclude that modulation of the inducible NO-synthase may regulate matrix protein production by vascular endothelium during inflammation.

[Cholesterol embolism: a heavy price to pay after successful fibrinolysis]

We attribute a case of acute irreversible renal failure associated with "blue toe syndrome" and eosinophilia to a cholesterol embolism after "successful" treatment of myocardial infarction with fibrinolysis. This case shows that CE can be caused not only by invasive arterial procedures but also by thrombolytic as well as by anticoagulant treatment. In modern medicine, the importance of this often fatal but usually undetected systemic affection is increasing. For patients with serious atherosclerosis it is essential to analyze the risks and benefits before undertaking arterial invasive procedures or fibrinolysis.

Cardiovascular autonomic modulation in essential hypertension. Effect of tilting

To better understand the role played by the autonomic nervous system in essential hypertension, we used autoregressive power spectrum analysis to study the noncasual oscillations in RR interval, blood pressure, and skin blood flow in 40 subjects with mild to moderate hypertension and in 25 age-matched control subjects at low frequency (index of sympathetic activity to the heart and the peripheral circulation) and high frequency, respiratory related (index of vagal tone to the heart). RR interval, respiration, noninvasive systolic blood pressure, and skin arteriolar blood flow were simultaneously and continuously recorded with subjects in the supine position and immediately after tilting. The low-frequency component was not significantly different in the two groups either at the cardiac level (control versus hypertensive subjects: 39.1 +/- 4.3 versus 39.9 +/- 3.7 normalized units [NU]) or at the vascular level (1.52 +/- 0.17 versus 1.69 +/- 0.13 ln mm Hg2). After head-up tilting, the RR interval fluctuations were less in hypertensive subjects (low-frequency components from 39.9 +/- 3.7 to 48.4 +/- 4.1 NU, P < .05; high-frequency components from 53.9 +/- 3.7 to 44 +/- 4 NU, P < .05) than in control subjects (low-frequency components from 39.1 +/- 4.3 to 64.4 +/- 4.9 NU, P < .001; high-frequency components from 56.0 +/- 4.5 to 31.2 +/- 4.6 NU, P < .001); the low-frequency components in systolic blood pressure increased similarly in hypertensive subjects (to 2.43 +/- 0.17 ln mm Hg2, P < .0001) and in control subjects (to 2.44 +/- 0.21 ln mm Hg2, P < .01), but the low-frequency components in skin blood flow increased only in control subjects (from 5.34 +/- 0.45 to 6.55 +/- 0.53 mm Hg2, P < .01), not in hypertensive subjects (from 5.55 +/- 0.34 to 5.60 +/- 0.35 ln mm Hg2). In hypertensive subjects with left ventricular hypertrophy, the low-frequency components in systolic blood pressure did not increase after tilting (from 1.75 +/- 0.33 to 2.05 +/- 0.41 ln mm Hg2). Baroreflex sensitivity, as assessed by spectrum analysis, was significantly lower in hypertensive than in control subjects (5.17 +/- 0.49 versus 13.18 +/- 2.44 ms/mm Hg, P < .001. Power spectrum analysis did not reveal an increased sympathetic activity or reactivity either at the cardiac or at the vascular level. The decreased baroreceptor sensitivity in hypertensive subjects could explain the reduced change in sympathovagal balance in the tilt position at the cardiac level. In hypertensive subjects without left ventricular hypertrophy, cardiopulmonary reflex deactivation induced by tilting and/or amplification of sympathetic nervous tone by arteriolar structural change could have preserved the sympathetic activation at the vascular level.

Antiherpesvirus Activity of the Combination of 5-iodo-2′-deoxycytidine with methotrexate: Anin vitroandin vivoStudy

We evaluated the in vitro and in vivo antiviral activity of the deoxyribonucleoside analogue 5-iodo-2′-deoxycytidine (IDC) combined with the dihydrofolate reductase inhibitor methotrexate (MTX) on herpes simplex virus types 1 and 2 (HSV-1, HSV-2). The IDC-MTX combination synergistically inhibited HSV-1 and HSV-2 replication in vitro at concentrations that did not reduce cellular viability and was very effective in reducing the severity of cutaneous lesions in the experimental guinea pig model in vivo. The antiviral activity of the IDC-MTX combination in guinea pigs was also compared with that of acyclovir and was demonstrated to be higher.

Expression of HIV-1 envelope gene by recombinant avipox viruses

Recombinant canarypox (CP) and fowlpox (FP) viruses that contained two forms of the HIV-1 (SF2 strain) env gene were engineered and their expression analysed in chick, simian and human cells. These vectors can efficiently replicate in avian but not in mammalian cells, in which infection is abortive. The two forms, consisting of the entire env open reading frame (IS+) or of the same gene lacking the putative immunosuppressive (IS-) region (amino acids 583-599), were individually inserted into the two virus vector backgrounds. In order to avoid premature transcription termination of the foreign gene and to improve protein expression, a mutagenesis was also performed within the T5NT motif without altering the amino acid sequence. By immunoprecipitation analyses, cells infected with CP and FP recombinants expressed HIV-1 env polypeptides of the appropriate molecular weight. We observed that the gp160 precursor was proteolytically cleaved except in MRC-5 cells infected with the IS- recombinants and that these polypeptides were glycosylated. Further analysis of these recombinant viruses by indirect immunofluorescence and syncytia inhibition assays indicated that the gp120 gp41 complex was present on the surface of infected cells, the number of syncytia being significantly lower when cells were infected by the CPIS- or FPIS- recombinants. Moreover, sera of immunized rabbits revealed the presence of specific antibodies in animals inoculated either with CP or with FP recombinants. These new constructs, which are unable to support a productive infection in human cells, might therefore also be a good anti-HIV-1 candidate vaccine in seropositive hosts.

Humoral and cell-mediated immunity in rabbits immunized with live non-replicating avipox recombinants expressing the HIV-1SF2 env gene

The canarypox (CP) and fowlpox (FP) viruses, which are unable to replicate productively in non-avian species, have been utilized as live vectors carrying the HIV-1SF2 env gene with the putative immunosuppressive (IS) region complete (CPIS+ and FPIS+) or deleted (CPIS- and FPIS-). To determine if these avipox-env recombinants could be utilized to elicit a specific immune response against HIV-1, six groups of rabbits were immunized with CPIS+, CPIS-, FPIS+, FPIS- constructs or their non-engineered wild-type CPwt or FPwt counterparts. After a primary inoculation and successive boosters, env-specific humoral and cell-mediated immunity were demonstrated by ELISA, immunoblots and lymphoproliferation assays. Antibody titres and neutralization activities were higher in CP- than FP-inoculated rabbits, the CPIS+ always showing a similar immunogenic capacity to CPIS-. Evidence is also presented indicating that rabbit sera possess group-specific antibodies, which were, however, unable to cross-neutralize divergent HIV-1 strains. Although the protective capacity against HIV-1 experimental infection has not yet been determined in these animals, our results suggest that these recombinants might represent promising and safer candidate vaccines against HIV-1.

Non-respiratory components of heart rate variability in heart transplant recipients: evidence of autonomic reinnervation?

1. Although the high-frequency fluctuations in R-R interval (respiratory sinus arrhythmia) observed in heart transplant recipients are not a reliable marker of reinnervation because of a previously shown direct mechanical effect of breathing, the presence of a non-respiration-related low-frequency oscillation reflects rhythms generated outside the heart, and thus could be neurally mediated. 2. To evaluate the presence of reinnervation, the spontaneous variability in R-R interval was investigated, supine and after passive tilting, in 23 heart transplant recipients (age 43 years, range 23-64 years) and in 25 normotensive control subjects by autoregressive spectral analysis of low- and high-frequency spontaneous fluctuations in R-R interval and respiration. The response of R-R interval to amyl nitrite inhalation was also evaluated in five heart transplant recipients and eight control subjects. 3. Detectable low-frequency oscillations, unrelated to respiration, were present in 13/23 heart transplant recipients, particularly in those who were transplanted at least 20 months earlier (11/14). The natural logarithm of the power of low-frequency fluctuations was markedly lower than in control subjects (0.75 +/- 0.21 versus 5.62 +/- 0.20 ms2, P < 0.001). The low-frequency but not the high-frequency fluctuations correlated with time since transplantation (r = 0.44, P < 0.05). The subjects with low-frequency fluctuations showed a sudden decrease in R-R interval with amyl nitrite linearly related to the decrease in mean blood pressure (r > or = 0.94). The slopes obtained in these heart transplant recipients were comparable (although of lower values) with those obtained in control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of mild physical activity, atenolol and the combination on ambulatory blood pressure in hypertensive subjects

OBJECTIVE

To evaluate whether beta-blocker treatment could enhance the effect of a mild physical training programme upon blood pressure.

DESIGN AND METHODS

In 12 hypertensive subjects (mean age: 40.3 years) a prospective randomized Latin square-design trial was performed with three treatments: physical training and placebo tablets; atenolol 50 mg once a day and inactivity; and physical training and atenolol 50 mg once a day.

RESULTS

Training significantly increased maximal ventilatory oxygen consumption (VO2MAX), and there was a decrease in ambulatory diastolic blood pressure (DBP) which did not reach statistical significance. Atenolol alone significantly reduced ambulatory systolic blood pressure (SBP) and DBP. Atenolol alone did not reduce VO2MAX. The combination of training and atenolol resulted in an increase in VO2MAX compared with atenolol alone, but no additional significant fall in blood pressure.

CONCLUSIONS

Atenolol did not enhance the effect of physical training upon blood pressure and had little if any effect upon the training-induced increase in exercise tolerance.

Controlled trial of physical training in chronic heart failure. Exercise performance, hemodynamics, ventilation, and autonomic function

BACKGROUND

Many secondary abnormalities in chronic heart failure (CHF) may reflect physical deconditioning. There has been no prospective, controlled study of the effects of physical training on hemodynamics and autonomic function in CHF.

METHODS AND RESULTS

In a controlled crossover trial of 8 weeks of exercise training, 17 men with stable moderate to severe CHF (age, 61.8 +/- 1.5 years; left ventricular ejection fraction, 19.6 +/- 2.3%), increased exercise tolerance (13.9 +/- 1.0 to 16.5 +/- 1.0 minutes, p less than 0.001), and peak oxygen uptake (13.2 +/- 0.9 to 15.6 +/- 1.0 ml/kg/min, p less than 0.01) significantly compared with controls. Training increased cardiac output at submaximal (5.9-6.7 l/min, p less than 0.05) and peak exercise (6.3-7.1 l/min, p less than 0.05), with a significant reduction in systemic vascular resistance. Training reduced minute ventilation and the slope relating minute ventilation to carbon dioxide production (-10.5%, p less than 0.05). Sympathovagal balance was altered by physical training when assessed by three methods: 1) RR variability (+19.2%, p less than 0.05); 2) autoregressive power spectral analysis of the resting ECG divided into low-frequency (-21.2%, p less than 0.01) and high-frequency (+51.3%, p less than 0.05) components; and 3) whole-body radiolabeled norepinephrine spillover (-16%, p less than 0.05). These measurements all showed a significant shift away from sympathetic toward enhanced vagal activity after training.

CONCLUSIONS

Carefully selected patients with moderate to severe CHF can achieve significant, worthwhile improvements with exercise training. Physical deconditioning may be partly responsible for some of the associated abnormalities and exercise limitation of CHF, including abnormalities in autonomic balance.

The influence of ambulatory blood pressure monitoring on the design and interpretation of trials in hypertension

OBJECTIVE

To describe the reproducibility of diastolic blood pressure (DBP) measurement by clinic and ambulatory monitoring and to evaluate the effects of this reproducibility on the design and interpretation of clinical trials in hypertension research.

DESIGN

Prospective single-blind study of repeat measurement reproducibility of blood pressure recording.

SETTING

Tertiary referral hospital hypertension clinic.

PATIENTS

One hundred untreated mild-to-moderate hypertensive subjects taking 1 month of single-blind placebo.

MAIN OUTCOME MEASURES

A single clinic measurement of DBP was poorly reproducible and the results for single DBP estimates taken out of a daytime ambulatory recording were similar. Average ambulatory DBP was much more reproducible, although this improvement depended upon the averaging of many measurements taken throughout the day.

CONCLUSIONS

Ambulatory monitoring would decrease antihypertensive trial size by a factor of four or halve the size of detectable DBP difference between treatments. The use of poorly reproducible DBP measurements such as single clinic readings may have led to an underestimation of the risks of minor degrees of blood pressure elevation because of a 'regression dilution' bias. For single clinic DBP readings, we calculate this underestimation to be as much as 69%, and for average ambulatory DBP approximately 20%.

[The variability of the heart rate, arterial pressure and peripheral circulation as the indices of autonomic control in essential hypertension]

In recent years the influence of autonomic nervous system on cardiac rhythm and blood pressure has been increasingly studied by analysis of cardiovascular fluctuations, particularly in diabetic and normal persons under various physiologic conditions, while still few data exist on essential hypertension. To characterize the autonomic cardiovascular control in essential hypertension we studied 22 untreated hypertensives, diagnosed within 1 year (mean age 43 +/- 2 years, mean +/- SEM) and 16 age-matched normotensives. Recordings of RR interval, breathing activity, noninvasive blood pressure (Finapres) and skin arteriolar flow (infrared photoplethysmogram) were obtained while in supine position and after sympathetic activation induced by passive transition to upright posture (tilting table). Autoregressive power spectral analysis was then carried out, and low- (0.03-0.15 Hz, LF) and high-frequency fluctuations (0.15-0.35 Hz, HF) were measured. LF and HF have been considered as markers of sympathetic and parasympathetic activity on the heart, respectively, and as markers of sympathetic and mechanic chest activity on the circulation, respectively. In supine position both cardiac and vascular variability were similar in both hypertensive and normotensive groups. After tilting however the increase in the sympathetic component of cardiac variability was blunted in hypertensives with respect to normotensives (hypertensives LFnu from 43.6 +/- 4.7 nu to 59.4 +/- 5.1 nu, p less than 0.005; normotensives LFnu from 36.9 +/- 3.3 nu to 83.4 +/- 2.6 nu, p less than 0.001), the increase in LFnu being statistically (p less than 0.001) reduced in the hypertensive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin-converting enzyme inhibition and physical training in heart failure

A total of 12 patients (mean age +/- SEM 63 +/- 2.6 years) with moderate to severe heart failure (ejection fraction = 23 +/- 3.2%) were included in a placebo-controlled crossover trial. Patients were randomly allocated to 4 periods of 6 weeks each: placebo, placebo and physical training, lisinopril 10 mg daily, and lisinopril and physical training. The exercise time increased from 13.6 +/- 0.9 min with placebo to 15 +/- 1 min with training alone, and to 16.1 +/- 0.7 min with lisinopril and training. With lisinopril alone there was a non-significant increase in exercise time, to 14.5 +/- 0.6 min. Improvements in exercise time were accompanied by a similar increase in peak oxygen consumption. Overall, the most significant improvements in symptoms and indices of cardiorespiratory fitness were achieved with a combination of lisinopril and training. Thus physical training is not only a useful adjunct to the existing medical therapy for heart failure, but it may also provide symptomatic benefits in its own right.

Ambulatory blood pressure monitoring: validation of the accuracy and reliability of the TM-2420 according to the AAMI recommendations

The accuracy of the TM-2420 ambulatory blood pressure monitor (A&D Co, Japan) has been assessed by the indirect method according to the recommendations of the Association for the Advancement of Medical Instrumentation (AAMI). Ninety subjects (43 men and 47 women), aged 19-89 with a range of systolic blood pressures (SBP) of 81-211 mmHg and diastolic blood pressures (DBP) of 32-113 mmHg were studied. The monitor was compared with two observers using the Hawksley random zero sphygomomanometer. The standard deviation of the difference (SDD) between the observers was 3.0 mmHg for SBP and 2.3 mmHg for DBP. The mean differences between observers were -0.31 mmHg for SBP and 0.32 mmHg for DBP (both NS). The average of three readings for each subject recorded by the monitor was compared with the average of the simultaneous readings by the observers. The SDD was 7.2 mmHg for SBP and 5.5 mmHg for DBP (within the recommendations for accuracy). The differences between methods were -0.98 mmHg for SBP and 0.18 mmHg for DBP; these differences were not significant (NS). The monitor was also assessed against direct intra-brachial artery pressure in 12 subjects (36 readings). The mean difference between the monitor and simultaneous individual intra-arterial reading was -9.5 mmHg for SBP (P less than 0.001) and 3.7 mmHg for DBP (P less than 0.001). The SDD's between methods were 12 mmHg for SBP and 5.0 mmHg for DBP. Use of the monitor in general clinical practice in 100 patients was also assessed. The rate of errors was low (6.8%), and the device found to be acceptable.(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory blood pressure in relation to drug treatment and clinical trials

Spontaneous differences in blood pressure from one clinic visit to another inevitably lead to the use of unnecessarily high doses of drugs in the treatment of hypertension and to unnecessarily high recommended doses of new antihypertensive drugs. This can be avoided by the use of ambulatory blood pressure monitoring. The improved reproducibility achieved by ambulatory monitoring substantially reduces the number of subjects required to detect small differences in pressure between one treatment and another. Furthermore, 24-h monitoring eliminates time-related fluctuations and makes it possible to use crossover trials to compare the antihypertensive effects of different drugs. Differences of 5 mmHg in diastolic pressure between two treatments can thus be detected in a trial on less than 20 subjects.

[Blood platelet alpha adrenergic receptors in congestive heart failure. Effects of ACE inhibition]

Platelet alpha-2-adrenergic receptor number and affinity were examined in 12 patients with class IV NYHA congestive heart failure (CHF) and 10 normal volunteers paired for age and sex. Platelet alpha-2-adrenergic receptor number is significantly decreased in CHF patients (178 +/- 18 fmol/mg prot. vs 282 +/- 21 fmol/mg prot. p less than 0.05). After Captopril treatment (6 weeks) alpha-2-receptor number increased but this increase was not statistically significant (236 +/- 28 fmol/mg prot.). This study supports the hypothesis that increased levels of circulating catecholamines in CHF lead to a decrease in platelet alpha-2-adrenoreceptors. Improved cardiac function following administration of Captopril could lead to a withdrawal of sympathetic tone. Captopril may also interact with sympathetic nervous function.

[Platelet adrenergic alpha receptors in hypertensive subjects undergoing treatment with calcium antagonists]

The effects of two different calcium-channel blocking agents on platelet alpha-2 adrenoceptors were studied in 18 mild to moderate hypertensive patients. The subjects were randomly assigned in a double blind fashion to treatment with either nifedipine 10 mg t.i.d. or tiapamil 300 b.i.d. for six weeks. Platelet alpha-2 receptors were studied before and following 6 weeks of treatment using radioligand binding assay (3H Rauwolscine). Both agents induced a reduction in alpha-2 receptors, which reached statistical significance only for nifedipine. Such a reduction may contribute to the antihypertensive effect of calcium-channel blocking drugs.

Biological and molecular analysis of LCV, an endogenous retrovirus with defective env gene

Retrovirus infectivity is the result of a cooperative interaction of three structural genes, gag, pol, and env. Since the L-cell endogenous retrovirus (LCV) lacks the env gene translation product, our aim was to study the biological and molecular basis of its non-infectiousness. Fusion experiments between LCV and homologous or heterologous cells demonstrated that virus production could be obtained only after LCV artificial penetration in murine cells and that the new progeny was still noninfectious. Northern blot analysis and heteroduplex mapping of the genomic RNA revealed a 0.99 kb deletion including the 3' region of the pol reading frame, the whole xenotropic and part of the ecotropic domain of the env gene. The results suggest that the observed deletion is responsible for the absence of the gp 70 and the gp 15 E molecules in the virion and seems therefore to be the molecular basis for the non-infectiousness of this retrovirus.

Circadian rhythm of the in vivo migration of neutrophils in psoriatic patients

Neutrophil chemotaxis in ten subjects with psoriasis was evaluated in vivo by the quantitative skin-window technique using autologous serum and in vitro using a modified Boyden technique. The in vitro chemotaxis values of the psoriatics were significantly lower (P less than 0.01) than those of healthy controls. When measured in vivo, however, we found that, after 9, 12, and 24 h, the values of the migrating polymorphonuclear leukocytes (PMNL) of psoriasis patients were only slightly and non-significantly lower than normal values. Analysing the in vivo chemotaxis data by a chronobiological method, we demonstrated statistically significant circadian rhythms in nine of the ten psoriasis patients. In seven of the patients, we found that the population had a significant rhythm, with the acrophase at -328 degrees. Our in vitro and in vivo values are in agreement with previously published values. However, there was a definite circadian rhythm of migration that we could not demonstrate in normal controls. We consider that our data reveal a significant and important difference between neutrophil chemotaxis in vivo in normal subjects and that in patients with psoriasis.