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C Ferrario

Publications and source records attributed to C Ferrario.

11 recordsLinked to original sources
PubMed2005

Comparison of stimulation patterns for FES-cycling using measures of oxygen cost and stimulation cost.

AIM: The energy efficiency of FES-cycling in spinal cord injured subjects is very much lower than that of normal cycling, and efficiency is dependent upon the parameters of muscle stimulation. We investigated measures which can be used to evaluate the effect on cycling performance of changes in stimulation parameters, and which might therefore be used to optimise them. We aimed to determine whether oxygen cost and stimulation cost measurements are sensitive enough to allow discrimination between the efficacy of different activation ranges for stimulation of each muscle group during constant-power cycling. METHODS: We employed a custom FES-cycling ergometer system, with accurate control of cadence and stimulated exercise workrate. Two sets of muscle activation angles ("stimulation patterns"), denoted "P1" and "P2", were applied repeatedly (eight times each) during constant-power cycling, in a repeated measures design with a single paraplegic subject. Pulmonary oxygen uptake was measured in real time and used to determine the oxygen cost of the exercise. A new measure of stimulation cost of the exercise is proposed, which represents the total rate of stimulation charge applied to the stimulated muscle groups during cycling. A number of energy-efficiency measures were also estimated. RESULTS: Average oxygen cost and stimulation cost of P1 were found to be significantly lower than those for P2 (paired t-test, p<0.05): oxygen costs were 0.56+/-0.03l min-1 and 0.61+/-0.04l min-1 (mean+/-S.D.), respectively; stimulation costs were 74.91+/-12.15 mC min-1 and 100.30+/-14.78 mC min-1 (mean+/-S.D.), respectively. Correspondingly, all efficiency estimates for P1 were greater than those for P2. CONCLUSION: Oxygen cost and stimulation cost measures both allow discrimination between the efficacy of different muscle activation patterns during constant-power FES-cycling. However, stimulation cost is more easily determined in real time, and responds more rapidly and with greatly improved signal-to-noise properties than the ventilatory oxygen uptake measurements required for estimation of oxygen cost. These measures may find utility in the adjustment of stimulation patterns for achievement of optimal cycling performance.

Biomedical Engineering↗
PubMed1999

Managing hypertension in the southeastern United States: applying the guidelines from the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI).

The southeastern United States has the highest occurrence of heart disease and stroke and among the highest rates of congestive heart failure and renal failure in the country. The Consortium for Southeastern Hypertension Control (COSEHC) is cooperating with other organizations in implementing initiatives to reduce morbidity and mortality from hypertension-related conditions in the southeastern United States. This article outlines for clinicians special consideration for implementation of the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) in the southeastern United States. Clinicians are encouraged to adapt the recommendations of JNC VI to their own patient groups, paying attention to these specific areas: (1) Ensure screening for hypertension in your practice and community. (2) Evaluate all patients for accompanying risk factors and target organ damage. (3) Promote lifestyle management for individual patients and populations for prevention and treatment of hypertension. (4) Set a goal blood pressure for each patient, and monitor progress toward that goal. (5) Recognize that many patients will be candidates for blood pressure goals of <130/85 mm Hg. (6) Pay attention to compelling and special indications such as diabetes, congestive heart failure, and renal dysfunction. (7) Consider combination therapy. (8) Maximize staff contributions to enhance patient adherence. (9) Encourage patient, family, and community activities to promote healthy lifestyles and blood pressure control.

Black or African American↗
PubMed1998

NK1 receptor antagonist blocks angiotensin II responses in renin transgenic rat medulla oblongata.

Angiotensin (Ang) II increases substance P (SP) efflux from perfused slices of medulla oblongata, and a peptide antagonist of SP, [Leu11,psiCH2NH10-11]SP, blocks the acute hypotension and bradycardia caused by Ang II injected into the nucleus tractus solitarii (nTS) of Harlan Sprague-Dawley (SD) rats. We investigated whether the same relationships exist in (mRen2)27 renin transgenic (TG) rats, which have chronic elevations of medullary tissue Ang II levels. Ang II increased SP efflux (48% above control; P<0.01) from slices of medulla prepared from 8- to 12-week old male TG rats. Injections of Ang II (250 fmol in 30 nL) into the nTS of chloralose-urethane anesthetized TG rats produced a significant increase in pressure of 7+/-2 mm Hg before a 13+/-3 mm Hg fall in pressure. Ang II induced similar depressor responses in Hannover SD rats but no increase in pressure. After nTS injection of the NK1-selective SP antagonist CP-96,345 (30 pmol in 60 nL), Ang II-induced hypotension was blocked in both groups, as was the pressor component in hypertensive rats. Hypotensive and bradycardic effects of glutamate (0.6 nmol in 30 nL) injected into the nTS were not altered by CP-96,345. In vitro receptor autoradiography showed that the SP antagonist (10 or 100 microM) did not compete for 125I-Ang II binding in the dorsal medulla, a result suggesting that it did not interact directly with Ang II receptors. Thus, the nTS cardiovascular effects of Ang II are mediated by SP in both normotensive rats and a model of hypertension with altered endogenous levels of Ang II. These findings link Ang II-induced effects on SP release from brain slices of the medulla oblongata to acute cardiovascular actions of the peptide through an NK1 receptor.

Angiotensin II↗
PubMed1992

Analysis of heart rate variability to assess hemodynamic alterations following induction of anesthesia.

Extensive changes in hemodynamics and cardiac rhythm during induction of anesthesia may be mediated by altered responses of the autonomic nervous system to anesthetic agents. Analysis of the power spectrum of the heart rate (PSHR) variability can supply information about the autonomic nervous system, and may be used in order to assess this phenomenon. In this study, 78 patients undergoing coronary artery bypass graft surgery were evaluated. Anesthesia was induced with sufentanil, and neuromuscular blockade with vecuronium, a combination that may cause a decrease in heart rate. Before and after induction of anesthesia, the heart rate (HR), blood pressure (BP), cardiac output (CO), cardiac index (CI), and PSHR components were recorded. PSHR was obtained by using a special algorithm and data acquisition system for real-time spectral analysis. A low-frequency component (LFa, mainly sympathetic) was analyzed from a band of 0.04 Hz to 0.1 Hz. A high-frequency component (RFa, parasympathetic) was identified by the respiratory frequency spectrum. Alterations of the heart rate after induction of anesthesia were defined in order to separate the patient population into two groups: slow heart rate (slow-HR) and stable heart rate (stable-HR). Slow heart rate was defined as a decrease in HR of more than 20% of the baseline value. The variables were analyzed and compared between the slow-HR (n = 25) and stable-HR (n = 53) groups in order to verify the possibility of identifying patients prone to hemodynamic changes after anesthesia induction. There were no differences in preoperative HR, BP, CO, or CI between groups before anesthesia induction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Biological activity of angiotensin-(1-7) heptapeptide in the hamster heart.

Angiotensin II has been reported to have both a positive inotropic effect and a coronary constrictor action in the hamster heart. To study the contribution to these responses of phenylalanine in position 8, we assessed the direct cardiac effects of angiotensin-(1-7), which lacks phenylalanine in position 8. Syrian hamsters were used to determine the effects of angiotensin-(1-7) on cardiac performance in the diseased and normal hearts. We used the isolated isovolumic heart preparation perfused either at a constant pressure of 50 mm Hg or at a constant coronary (myocardial) flow rate of 7 ml/min (seven cardiomyopathic hamsters [CMH] and seven normal hamsters [NH] in each subgroup). At constant perfusion pressure, coronary (myocardial) flow rate decreased (p less than 0.01) in both CMH and NH (-31 +/- 8% vs. -39 +/- 4% of baseline, respectively); but the percent decrease in left ventricular pressure and the first derivative of left ventricular pressure over time (LV + dP/dt) was significant only in NH (-8 +/- 1% and -9 +/- 4%) but not in CMH (-14 +/- 5% and -21 +/- 8%). On the other hand, at a constant coronary (myocardial) flow rate, left ventricular pressure and LV + dP/dt tended to increase in both CMH and NH (+10 +/- 3% and +6 +/- 2% of baseline vs. +7 +/- 7% and +7 +/- 5%, respectively) but these changes were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin I↗
PubMed1987

Hypertonicity of intestinal smooth muscle as a factor of intestinal ischemia in necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is thought to be secondary to mucosal ischemia. Because blood flow to the submucosal plexus is derived from vessels traversing three separate layers of visceral smooth muscle (longitudinal, circular, and muscularis mucosa), we investigated whether an increase in their tone might elicit mucosal ischemia. The intestinal intraluminal pressure (IIP) and the superior mesenteric artery (SMA) blood flow were evaluated in 23 dogs before and after either ligation of the SMA or neostigmine infusion into the SMA. Changes in vascularity were assessed by silicone rubber casting, India ink, or arteriography. Ten minutes after ligation of the SMA, there was a considerable increase in peristalsis, IIP, and inability to fill the intestinal microcirculation by the three methods described. Mucosal necrosis was present three hours later. In the neostigmine infusion group after a transient increase in mesenteric flow, the IIP rose 750%, while the mesenteric flow fell by 40%, mucosal necrosis occurred in one hour. When myotomy was performed on the antimesenteric border, mucosal necrosis was prevented. In a third group, neostigmine infused (femoral artery) in the hind limb demonstrated vasodilating effects. The data indicate that an increase in the myogenic tone and frequency of contraction of intestinal smooth muscle can produce mucosal ischemia, thus, intestinal hypertonicity may be an important factor in the pathogenesis of intestinal ischemia and possibly NEC. The effects of neostigmine in these experiments raise questions regarding its use during anesthesia in neonates with intestinal low flow states.

Animals↗
PubMed1980

Immunodeficiency in Down's syndrome: low levels of serum thymic factor in trisomic children.

The activity of thymus-dependent serum factor SF was significantly lower in 18 children wit Down's syndrome (DS) than in 14 matched controls. The percentage of circulating T lymphocytes forming E-rosettes was also low in DS. Together with the previous finding of immature of T lymphocytes in peripheral blood, the present data suggest that the basic immune defect of DS is failure in differentiation of peripheral post-thymic precursors to fully immunocompetent T lymphocytes resulting from lack of thymic hormonal factors.

Child, Preschool↗
PubMedDate not supplied

Questioning the utility of pooling samples in microarray experiments with cell lines.

We describe a microarray experiment using the MCF-7 breast cancer cell line in two different experimental conditions for which the same number of independent pools as the number of individual samples was hybridized on Affymetrix GeneChips. Unexpectedly, when using individual samples, the number of probe sets found to be differentially expressed between treated and untreated cells was about three times greater than that found using pools. These findings indicate that pooling samples in microarray experiments where the biological variability is expected to be small might not be helpful and could even decrease one's ability to identify differentially expressed genes.

Antineoplastic Agents, Hormonal↗