Curva de aprendizaje para el acceso con trocar óptico en cirugía pélvica laparoscópica: estudio prospectivo / Learning curve of optical trocar access during laparoscopic pelvic surgery: A prospective study

Introducción El acceso con trocar óptico (ATO) es una técnica modificada de laparoscopia cerrada cuyo objetivo es minimizar el riesgo de lesiones vasculares o intestinales y reducir la posible fuga de gas. Se ha analizado el efecto de la curva de aprendizaje (CA) para el ATO, considerando n=30 procedimientos como umbral para definir un nivel aceptable de experticia. Nuestro objetivo es evaluar el impacto de la CA en los primeros 30 casos de ATO realizados por un aprendiz. Métodos Se trata de un estudio prospectivo aleatorizado en 60 pacientes planificadas para cirugía ginecológica laparoscópica. Las pacientes fueron seleccionadas aleatoriamente para el ATO realizado por un cirujano sin entrenamiento previo en la técnica o por un cirujano experto. La CA se evaluó mediante: 1) tiempo hasta lograr el acceso; 2) número de correcciones hechas por el experto; 3) número de veces en que la punta del trocar se detuvo en la capa preperitoneal; 4) errores al realizar la incisión en la piel; 5) veces en que la punta del trocar termina bajo el epiplón; 6) complicaciones. Para analizar el CA en los 30 primeros casos, se estratificaron los procedimientos en 3 grupos (casos 1-10; 11-20; 21-30) tanto para el aprendiz como para el experto y se compararon las variables de la CA. Resultados De forma global, el tiempo medio de inserción para el ATO fue de 56s. No se registraron complicaciones intraoperatorias ni postoperatorias graves. El tiempo medio de inserción fue estadísticamente más largo para el aprendiz en comparación con el experto en los 10 primeros casos (91s frente a 33s, respectivamente, p=0,01). En los casos 11-20 y 21-30, la ventaja de tiempo del cirujano experto se hizo menos evidente (p=0,05). El número de veces que la punta del trocar se detuvo en la capa preperitoneal fue similar entre los grupos, así como las veces que la punta del trocar llegó por debajo del epiplón. Conclusiones La técnica de ATO es rápida y reproducible . ... (AU)

Introduction The optical trocar access (OTA) is a modified closed technique that aims to minimize the risk of vascular or bowel injuries while reducing the likelihood of gas leakage. A learning curve (LC) effect for OTA has been invoked with n=30 procedures being considered as a threshold to define expertise. We aim to evaluate the impact of the LC within the first thirty cases of OTA performed by a trainee. Methods This is a prospective randomized study on 60 patients elected to laparoscopic gynecological surgery. Patients were randomized to have OTA insertion by a junior surgeon or by an expert. LC was evaluated by: 1) insertion time; number of: 2) corrections by the senior; 3) times the tip of the trocar stopped in the preperitoneal layer; 4) mistakes of skin incision; 5) times the tip of the trocar ends under the omentum; 6) complications. To analyze the LC within the first 30 cases, procedures were stratified in 3 groups (cases 1-10; 11-20; 21-30) for both trainee and expert and LC variables were compared. Results Overall, mean OTA insertion time was 56s. No major intra- and post-operative complications were recorded. Mean insertion time was statistically significantly longer for the trainee compared to the expert within the first 10 cases (91 vs 33s respectively, p=0.01). For cases 11-20 and 21-30, time advantage of the senior surgeon is less evident (p=0.05). The number of times the tip of the trocar stopped in the preperitoneal layer was similar between groups, as well as times the tip of the trocar ends under the omentum. Conclusions OTA is a fast and simple way to achieve the pneumoperitoneum and first trocar insertion as a single step. The current series confirms the effectiveness of the technique since the beginning of the LC. (AU)

Learning curve of optical trocar access during laparoscopic pelvic surgery: A prospective study.

INTRODUCTION: The optical trocar access (OTA) is a modified closed technique that aims to minimize the risk of vascular or bowel injuries while reducing the likelihood of gas leakage. A learning curve (LC) effect for OTA has been invoked with n = 30 procedures being considered as a threshold to define expertise. We aim to evaluate the impact of the LC within the first thirty cases of OTA performed by a trainee. METHODS: This is a prospective randomized study on 60 patients elected to laparoscopic gynecological surgery. Patients were randomized to have OTA insertion by a junior surgeon or by an expert. LC was evaluated by: 1) insertion time; number of: 2) corrections by the senior; 3) times the tip of the trocar stopped in the preperitoneal layer; 4) mistakes of skin incision; 5) times the tip of the trocar ends under the omentum; 6) complications. To analyze the LC within the first 30 cases, procedures were stratified in 3 groups (cases 1-10; 11-20; 21-30) for both trainee and expert and LC variables were compared. RESULTS: Overall, mean OTA insertion time was 56 s. No major intra- and post-operative complications were recorded. Mean insertion time was statistically significantly longer for the trainee compared to the expert within the first 10 cases (91 vs 33 s respectively, P = .01). For cases 11-20 and 21-30, time advantage of the senior surgeon is less evident (P = .05). The number of times the tip of the trocar stopped in the preperitoneal layer was similar between groups, as well as times the tip of the trocar ends under the omentum. CONCLUSIONS: OTA is a fast and simple way to achieve the pneumoperitoneum and first trocar insertion as a single step. The current series confirms the effectiveness of the technique since the beginning of the LC.

New ultralow-cost telemetric system for a rapid electrochemical detection of vitamin C in fresh orange juice.

Ascorbic acid (AA), one of the principal micronutrients in horticultural crops, plays a key role in the human metabolism, and its determination in food products has a great significance. Citrus fruits are rich in AA, but its content is highly susceptible to change during postharvest processing and storage. We present a new ultralow-cost system, constituted of an amperometric microsensor composed of three rod carbon electrodes connected to a telemetric device, for online detection of AA in orange juice, as an alternative to conventional analytical methods. The in vitro calibration, ranged from 0 to 5 mM, and AA juice content was calculated by adding low volumes of sample into an acetate buffer solution at a constant potential of +120 mV vs carbon pseudoreference. This new approach, which is simple, expandable, and inexpensive, seems appropriate for large scale commercial use.

Menses recovery and fertility after artery embolization for PPH: a single-center retrospective observational study.

To evaluate long-term effects of arterial embolization (AE) for postpartum hemorrhage (PPH) on menses recovery and subsequent pregnancies. One hundred thirteen consecutive patients, recruited from 1999 to 2006, who had undergone AE for severe PPH were evaluated in a retrospective monocentric study. As embolization agents, pledgets of absorbable gelatine sponge (Curaspon) were used in 106 cases, Curaspon powder in 3 cases, and inert microparticles in 4 cases. In 111/113 cases (98.1%), AE was successful in controlling PPH. In two cases (1.7%), the AE was unsuccessful and required a total abdominal postembolization hysterectomy. Concerning fertility, 6 patients were lost to follow-up and 107 were available. The average time to follow-up was 46.4+/-21.8 months. Of the 107 patients, 99 had recovery of menses (92.5%). Of the 107 (61%) patients, 66 reported regular menstruation with normal delay after the delivery. Thirty-three patients (31%) reported subjective changes in the frequency and amount of menses. Six patients (5.6%) had documented amenorrhea after AE and developed diffuse uterine synechiae at the hysteroscopic investigation. Out of 29 patients who desired and attempted conception, 18 patients (62%) reported a total of 19 pregnancies at the end of the follow-up. One miscarriage at 12 weeks of gestation was reported. The 18 pregnancies at term were uneventful until delivery, but 3 cases of further PPH (15%) occurred due to abnormal placentation requiring a further AE. All full-term newborns were healthy. AE is a feasible, safe, and reproducible technique to control PPH, allowing a very high resumption of menses and subsequent pregnancies; in these cases, considering the elevated incidence of further PPH due to abnormal placentation, an accurate ultrasonographic monitoring during pregnancy seems appropriate.

Serum from patients with severe heart failure downregulates eNOS and is proapoptotic: role of tumor necrosis factor-alpha.

BACKGROUND: Cytokine activation and endothelial dysfunction are typical phenomena of congestive heart failure (CHF). We tested the hypothesis that incubating human umbilical vein endothelial cells with serum from patients with CHF will downregulate endothelial constitutive nitric oxide synthase (eNOS) and induce apoptosis. METHODS AND RESULTS: We studied 21 patients with severe CHF. Levels of tumor necrosis factor-alpha (TNF-alpha) and several neuroendocrine parameters were assessed. eNOS was measured by Western Blot analysis and apoptosis by optical microscopy and flow cytometry. We observed (1) eNOS downregulation (difference versus healthy subjects at 24 hours [P<0.05] and 48 hours [P<0.001]), (2) nuclear morphological changes typical of apoptosis; and (3) a high apoptotic rate with propidium iodide (increasing from 2.1+/-0.4% to 11.3+/-1.2% at 48 hours; P<0.001 versus healthy subjects) and annexin V. An anti-human TNF-alpha antibody did not completely counteract these effects. A strong correlation existed between eNOS downregulation and apoptosis (r = -0.89; P<0.001). CONCLUSIONS: Serum from patients with severe CHF downregulates eNOS expression and increases apoptosis. High levels of TNF-alpha likely play a role, but they cannot be the only factor responsible.

Induction of functional inducible nitric oxide synthase in monocytes of patients with congestive heart failure. Link with tumour necrosis factor-alpha.

AIMS: We studied the induction of monocytic inducible nitric oxide synthase expression and the tumour necrosis factor-alpha system in patients with congestive heart failure. METHODS AND RESULTS: Forty-three congestive heart failure patients and 15 healthy subjects were studied. Antigenic tumour necrosis factor-alpha and its soluble receptors, measured by ELISA, were increased in chronic heart failure and the increase was related to the clinical severity of the syndrome (tumour necrosis factor-alpha from 8.2+/-5.2 in NYHA class II to 18.2+/-7.2 in class III and 26.9+/-13.2 pg. ml(-1)in class IV, P<0.0001 classes III and IV vs class II; soluble tumour necrosis factor receptor I from 1.0+/-0.2 in class II to 2.3+/-1.1 in class III and 5.5+/-3.2 ng. ml(-1)in class IV, P<0.0001 classes III and IV vs class II; soluble tumour necrosis factor receptor II from 2.7+/-0.7 in class II to 4.9+/-1.9 in class III and 8.4+/-5.0 ng. ml(-1)in class IV, P<0.002 classes III and IV vs class II). Monocytic inducible nitric oxide synthase assessed by Western blot, was expressed only in congestive heart failure patients (13 out of 43). The association among monocytic inducible nitric oxide synthase expression, tumour necrosis factor-alpha system activation, neurohormones and other clinical parameters was studied. The univariate logistic regression showed that inducible nitric oxide synthase expression was strictly associated with NYHA class (P<0.05), antigenic tumour necrosis factor-alpha (P<0.01) and its soluble receptors (P<0.05). The multivariate analysis showed that antigenic tumour necrosis factor-alpha was the only predictor for monocytic inducible nitric oxide synthase expression (P<0.05, RR=2.75, CI 1. 34-5.43). CONCLUSIONS: Inducible nitric oxide synthase is expressed in circulating monocytes of patients with severe congestive heart failure. This phenomenon is linked to the activation of the tumour necrosis factor-alpha system.

Effects of chronic noradrenaline on the nitric oxide pathway in human endothelial cells.

Altered endothelium-dependent vasodilation has been observed in congestive heart failure (CHF), a disease characterized by a sustained adrenergic activation. The purpose of our study was to test the hypothesis that chronically elevated catecholamines influence the nitric oxide (NO) pathway in the human endothelium. Human umbilical vein endothelial cells (HUVEC) were exposed for 7 days to a concentration of noradrenaline (NA, 1 ng/mL) similar to that found in the blood of patients with CHF. Kinetics of endothelial constitutive NO synthase (ecNOS) and inducible NO synthase (iNOS) activity, measured by [3H]L-arginine to [3H]L-citrulline conversion, and protein expression of ecNOS and iNOS, assessed by Western blot analysis, were unaffected by chronic NA treatment. Furthermore, no changes in subcellular fraction-associated ecNOS were found; this indirectly shows that chronic NA did not cause phosphorylation of the enzyme. Moreover, [3H]L-arginine transport through the plasma membrane was conserved in chronically NA-treated cells. The data demonstrate that prolonged in vitro exposure to pathologic CHF-like NA does not affect the L-arginine: NO pathway in human endothelial cells.

Oxidative stress during myocardial ischaemia and heart failure.

Oxidative stress is a condition in which oxidant metabolites exert toxic effects because of their increased production or an altered cellular mechanism of protection. The heart needs oxygen but it is also susceptible to oxidative stress, which occurs during post-ischaemic reperfusion, for example. Ischaemia causes alterations in the defence mechanisms against oxygen free radicals. At the same time, production of oxygen free radicals increases. In man, there is evidence of oxidative stress during surgical reperfusion of the whole heart, or after thrombolysis, and it is related to transient left ventricular dysfunction or stunning. At present, there are few data on oxidative stress in the failing heart. It is not clear whether the defence mechanisms of the myocyte are altered or whether the production of oxygen free radicals is increased, or both. Recent data have shown a close link between oxidative stress and apoptosis. Importantly, tumour necrosis factor causes a rapid rise in intracellular reactive oxygen intermediates and apoptosis. This series of events is not confined to the myocytes, but also occurs at the level of endothelium, where tumour necrosis factor causes expression of inducible nitric oxide synthase, production of the reactive radical nitric oxide, oxidative stress and apoptosis. The immunological response to heart failure may result in endothelial and myocyte dysfunction through oxidative stress-mediated apoptosis. A better understanding of these mechanisms may lead to novel therapeutic strategies.

Heat shock protein changes in hibernation: a similarity with heart failure?

Myocardial hibernation is an adaptive phenomenon occurring during ischaemia. Patients with hibernating myocardium often have a history of an acute ischaemic insult, followed by prolonged hypoperfusion and symptoms of congestive heart failure (CHF), which is a complex syndrome involving several adaptational mechanisms. We tested the hypothesis that these two conditions evoke the myocardial expression of heat shock protein 72 (hsp72) as an adaptive response at the molecular level. Short-term acute hibernation was induced in isolated and perfused rat hearts subjected to 8 min total ischaemia followed by 292 min low-flow ischaemia (coronary flow: 1.0 ml/min), followed by 60 min of reperfusion. Total ischaemia caused quiescience. Subsequent low-flow resulted in a temporal early increase of lactate release, no re-establishment of developed pressure, no increase in diastolic pressure. Reperfusion resulted in 85.7 +/- 7.2% recovery of developed pressure, a small washout of lactate and CPK, no contracture, confirming that viability was maintained despite prolonged hypoperfusion. This sequence of events was linked to an increase in hsp72 content in the right (from 18.1 +/- 3.8% to 34.6 +/- 2.3%. P < 0.01) and left (from 19.7 +/- 2.6% to 37.6 +/- 3.3%, P < 0.01) ventricles. Three-hundred min of low-flow perfusion of the rat heart in absence of the short period of total ischaemia caused irreversible damage and failed to induced hsp72. CHF was induced in rats by intraperitoneal administration of monocrotaline. As a result, right ventricular weight increased from 171.3 +/- 7.2 to 412.3 +/- 18.7 mg. P < 0.001, peripheral and pleural effusion were evident and measurable, plasma arterial natriuretic peptide increased from 15.2 +/- 1.9 to 123.5 +/- 5.4 pg/ml, P < 0.001, confirming the occurrence of the syndrome of CHF. This was concomitant with significant expression of hsp72, more evident in the right (from 5.0 +/- 0.9% to 39.4 +/- 1.6%, P < 0.001) than in the left (from 3.5 +/- 0.6% to 13.0 +/- 1.2%, P < 0.001) ventricle. These data suggest that an adaptational process occurs at myocardial level during either hibernation or CHF. The expression of hsp72 could be viewed as a stereotyped adaptational reaction of the cardiac cell to stress conditions.

Aorta and skeletal muscle NO synthase expression in experimental heart failure.

Nitric oxide (NO), the free radical that accounts for the biological activity of endothelium-derived relaxing factor, is synthesized from L-arginine by NO synthase (NOS). There is evidence that NO availability is reduced in the peripheral vasculature of patients with congestive heart failure (CHF). The aim of this study was to investigate the expression of NOS in the descending aorta and in the skeletal muscles of rats subjected to heart failure. The alkaloid, monocrotaline, was used to induce pulmonary hypertension and cardiac failure in rats. The expression of both the constitutive (ecNOS) and the inducible (iNOS) isoforms of the enzyme was assessed by Western blot analysis. In CHF animals, the ecNOS location in the aorta is altered: the endothelial protein expression is substantially reduced (from 0.083 +/- 0.012 to 0.003 +/- 0.004 OD/microgram total proteins, P < 0.001) whereas the expression of ecNOS in the smooth muscle is increased (from 0.024 +/- 0.004 to 0.059 +/- 0.009 OD/ microgram total proteins, P < 0.01). The total aortic ecNOS is diminished in CHF respect to control animals (0.062 +/- 0.009 v 0.107 +/- 0.013 OD/microgram total proteins, P < 0.01). On the contrary, no difference in ecNOS protein expression was observed in the extensor digitorum longus and soleus muscles. Furthermore, iNOS was not detected in any of the tissues considered. In conclusion, experimental CHF causes a re-setting of the ecNOS protein expression in the descending aorta but not in skeletal muscles. The reduced abundance of ecNOS in the aortic endothelium is consistent with the impairment of the vasodilating function reported in patients with CHF.

Effects of felodipine on the ischemic heart: insight into the mechanism of cytoprotection.

To assess whether the administration of felodipine protects the myocardium in a dose-dependent manner against ischemia and reperfusion, isolated rabbit hearts were infused with three different concentrations of felodipine: 10(-10), 10(-9), and 10(-8) M. Diastolic and developed pressures were monitored; coronary effluent was collected and assayed for CPK activity and for noradrenaline concentration; mitochondria were harvested and assayed for respiratory activity; and ATP production and calcium content and tissue concentration of ATP, creatine phosphate (CP), and calcium were determined. The occurrence of oxidative stress during ischemia and reperfusion was also monitored in terms of tissue content and release of reduced (GSH) and oxidized (GSSG) glutathione. Treatment with felodipine at 10(-10) and 10(-9) M had no effect on the hearts when perfused under aerobic conditions, whilst the higher dose reduced developed pressure from 57.7 +/- 2.6 to 30.0 +/- 2.6 mmHg (p < 0.01). On reperfusion treated hearts recovered better than the untreated hearts with respect to left ventricular performance, replenishment of ATP and CP stores, and mitochondrial function. Recovery of developed pressure was 100% at 10(-8) M, 55% at 10(-9) M, and 46% at 10(-10) M. The reperfusion-induced tissue and mitochondrial calcium overload, release of CPK and noradrenaline, and oxidative stress were also significantly reduced. The effects of felodipine were dose dependent. Felodipine inhibited the initial rate of ATP-driven calcium uptake but failed to affect the initial rate of mitochondrial calcium transport. It is concluded that felodipine infusion provides dose-dependent protection of the heart against ischemia and reperfusion. Because this protection also occurred at 10(-9) M and 10(-10) M in the absence of a negative inotropic effect during normoxia and of a coronary dilatory effect during ischaemia, it cannot be attributed to an energy-sparing effect or to improvement in oxygen delivery. From our data we can envisage two other major mechanisms-(1) membrane protection and (2) reduction in oxygen toxicity. The ATP-sparing effect occurring at 10(-8) M is likely to be responsible for the further protection.

Right heart failure chronically stimulates heat shock protein 72 in heart and liver but not in other tissues.

OBJECTIVES: During cardiac failure several ontogenically developed adaptional mechanisms are activated. Among these, heat-shock proteins (HSP) are expressed in response to stress. The aim of the present study was to investigate the HSP72 protein expression in lungs, liver, cardiac and skeletal muscles during congestive heart failure (CHF). METHODS: CHF was induced in Sprague-Dawley rats by a single intraperitoneal injection of monocrotaline (50 mg/kg). Two groups of animals emerged: a CHF group (n = 10) with right ventricular hypertrophy, pleural and peritoneal effusions, and an Hypertrophy group (n = 12) with right ventricular hypertrophy without CHF. The data for each group were compared with those of control (saline infused) age-matched rats. Lungs, liver, right and left ventricles, soleus, extensor digitorum longus and tibialis anterior muscles were excised and analyzed for HSP72 concentration by Western blot analysis using a specific monoclonal antibody. Noradrenaline levels in the heart were also measured using HPLC. RESULTS: The CHF group showed: (1) reduced right (0.460 +/- 0.090 vs 0.830 +/- 0.070 nmol/ventricle, P < 0.01) and left (1.10 +/- 0.09 vs 2.10 +/- 0.130 nmol/ventricle, P < 0.001) ventricular content of noradrenaline compared to the control; (2) significant activation of HSP72 concentration in right and left ventricles (39.4 +/- 1.6 vs 5 +/- 0.9% and 13 +/- 1.2 vs 3.5 +/- 0.6%, P < 0.001 both) and in the liver (39.8 +/- 11 vs 6 +/- 2%, P < 0.001); (3) no modification in HSP72 concentration in lungs and all of the peripheral muscles considered. The Hypertrophy group showed: (1) unchanged total noradrenaline tissue content as compared to the control; and (2) unmodified HSP72 concentration in all tissues analyzed. CONCLUSIONS: The present study demonstrates that CHF, but not compensatory hypertrophy, is a specific stimulus for chronic HSP72 induction in the heart and liver. On the contrary, CHF does not affect HSP in lungs and peripheral muscles. HSP 72 induction represents an intracellular marker of stress reaction which can persist chronically.

[Activation and role of the tumor necrosis factor-alpha in congestive heart failure]. / Attivazione e ruolo del fattore di necrosi tumorale alfa nello scompenso cardiaco congestizio.

Recently, an activation of the immune system has been demonstrated in congestive heart failure (CHF). Aim of this study was to evaluate the effects of CHF on the activation of alpha tumor necrosis factor (TNF-alpha), a pleiotropic cytokine. Since the soluble forms of the TNF membrane receptors, sTNF-RI and sTNF-RII, have been shown to modulate TNF-alpha biological activity, we determined antigenic TNF-alpha, bioactive TNF-alpha, sTNF-RI and sTNF-RII in 52 patients with varying degrees of CHF (NYHA functional class II, III, IV). The etiology of CHF was coronary artery disease in 51% of the patients, idiopathic dilated cardiomyopathy in 38% and valvular disease in 11%. All patients were treated with ACE-inhibitors, digoxin and inotropic agents. Antigenic TNF-alpha was significantly increased in NYHA functional class IV patients (from 12.1 +/- 7.6 to 38.5 +/- 12.4 pg/ml, p < 0.001) whereas cytotoxic activity was always under the detection limit of the assay (100 pg/ml). Soluble TNF receptors were significantly elevated in NYHA functional class IV patients: sTNF-RI increased from 1.27 +/- 0.48 to 4.54 +/- 2.11 ng/ml (p < 0.001) and sTNF-RII from 2.25 +/- 0.55 to 7.78 +/- 2.13 ng/ml (p < 0.001). The possible modulation of TNF-alpha biological activity by the soluble receptors was investigated by means of spiking experiments after addition of 625 pg/ml human recombinant TNF-alpha to each serum sample. The biological activity of the added TNF-alpha was significantly inhibited by the high levels of soluble receptors present in the sera of NYHA functional class IV patients (from 625 to 249 +/- 176 pg/ml, p < 0.001). The results show that TNF-alpha and its soluble receptors are activated in severe CHF. The high concentration of soluble TNF receptors circulating in CHF patients are likely to play a protective role against TNF-alpha biological activity.

Heat shock protein 72 in cardiac and skeletal muscles during hypertension.

In order to elucidate the relationship between hypertension and hypertrophy in the production of heat shock proteins, we studied the induction of the HSP72 synthesis by the heart and gracilis muscles of normo (WKY) and hypertensive (SHR) rats subjected to hyperthermia (42 degrees C +/- 0.5 for 15 min). Two age groups were investigated in each strain: young (2 months, with developing cardiac hypertrophy) and old (18 months, with fully developed chronic cardiac hypertrophy). The gracilis muscle never developed hypertrophy, independently of hypertension or aging. 72 kDa inducible protein was determined by Western blot analysis using a specific monoclonal antibody. We also used a commercial standard, loaded on each blot, to quantitate densitometrically the signal. The heart of young SHR responds to heat shock more than their normotensive age-matched control (298.8 +/- 24.7% vs 88.3 +/- 8.5%, p < 0.001). This response is not maintained during aging as we did not find any significant difference between normo- and hypertensive old rats after exposure to hyperthermia (43.6 +/- 5.3% vs 65.3 +/- 10.4%). Unlike the heart, the gracilis muscle shows a basal spontaneous HSP72 synthesis in both the SHR (71.4 +/- 10.8%) and WKY (40.6 +/- 11.7%) animals. There was a significant increase in HSP72 synthesis in the gracilis muscle of young SHR with respect to their control (186.2 +/- 18.7% vs 115.8 +/- 9.9%, p < 0.02) which was maintained also during aging (171.9 +/- 17.3% vs 95.2 +/- 10.5%, p < 0.01). In conclusion, these data show that hypertension results in an increased synthesis of HSP72 both in cardiac and gracilis muscle in response to heat shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of ANP synthesis during congestive heart failure in rats treated with monocrotaline.

We studied plasma concentration, content, and mRNA for atrial natriuretic peptide (ANP-mRNA) in heart chambers of monocrotaline-treated rats. Three distinct groups emerged: group 1, with moderate congestive heart failure (CHF; pleural effusion < 1 ml; no peritoneal effusion); group 2, with severe CHF (pleural and peritoneal effusion > 1 ml); and group 3, with right hypertrophy and no CHF. Group 1 and 2 rats had right atrial and ventricular hypertrophy, raised plasma ANP (from 16.31 +/- 11.32 to 98.50 +/- 22.50 and 124.09 +/- 57.29 pg/ml, respectively; P < 0.001), and depletion of right atrial ANP (from 143.23 +/- 29.79 to 21.70 +/- 17.70 and 18.12 +/- 14.64 nmol/g, respectively; P < 0.001). Ventricular ANP concentration was unchanged. ANP-mRNA rose in the right atrium [10.6 (P < 0.02) and 7.9 (P < 0.01) times] and right ventricle (53.0 and 46.6 times; P < 0.01). In left unhypertrophied chambers it also increased, although to a smaller extent. Group 3 rats had isolated right ventricular hypertrophy, normal ANP levels in plasma and tissues, and no activation of synthesis. These data suggest that 1) plasma concentration and ANP synthesis are increased only in animals with CHF, 2) activation of ANP synthesis is maximal in early stages of CHF and is not related to the degree of hypertrophy, and 3) ANP-mRNA is also expressed in unhypertrophied heart chambers of rats with CHF but is not expressed in hypertrophied chambers of animals without CHF.

Hypertension, aging, and myocardial synthesis of heat-shock protein 72.

We determined the temperature-induced synthesis of the 72-kD heat-shock protein (hsp72) in hearts of normotensive and spontaneously hypertensive rats (SHR) subjected to whole-body hyperthermia (42.0 +/- 0.5 degrees C for 15 minutes). The animals were studied at three different ages: young (2 months), adult (6 months), and old (18 months). The hsp72 was determined by Western blot analysis using a monoclonal antibody. The results were calculated densitometrically as a percentage of a commercial standard. Young SHR responded to hyperthermic stress with increased synthesis of hsp72 compared with age-matched normotensive rats (298.8 +/- 70.0% versus 88.3 +/- 25.5%). This trend was maintained in adult rats (118.1 +/- 31.0% versus 54.8 +/- 21.3%) but not in old rats (65.3 +/- 29.4% versus 43.6 +/- 15.1%). Aging caused a reduction of hsp72 expression in response to hyperthermic stress in both SHR (4.6-fold) and normotensive rats (twofold). These data show that hearts of young and adult SHR respond to heat shock with enhanced synthesis of hsp72. This abnormal response, attenuated by aging, is independent of the presence and degree of hypertension or hypertrophy and is potentially linked to the genetic determination of the disease.

How do calcium antagonists differ in clinical practice?

The majority of calcium antagonists used clinically belong to three distinct chemical classes: the phenylalkylamines, the dihydropyridines, and the benzothiazepines. In recent years their mode of action has been unravelled, their limitations recognized, and their efficacy and use in the management of patients with a broad spectrum of cardiovascular and other disorders defined. It is clear, however, that these drugs are not all alike, providing an explanation for their differing effects. The final therapeutic effect in humans depends on the mechanisms of action at the molecular level, the tissue selectivity, and the hemodynamic changes of each agent. All these aspects are examined in detail in this article. Concepts that are highlighted are as follows: (a) Molecular biology has allowed recognition of the polypeptide components of the alpha 1 subunit of the L-type Ca2+ channel and the finding of peptide segments covalently labelled by all three classes of drugs. (b) The location of these segments within the peptides is different: Binding sites for dihydropyridines are located externally, whereas those for verapamil and diltiazem are located internally, in the cytosolic part of the membrane. (c) Dihydropyridine binding is voltage dependent. This explains the selectivity of this class of drugs for vascular smooth muscle, which is more depolarized than cardiac muscle. (d) Phenylalkylamines and benzothiazepines reach their receptors at the internal surface of the sarcolemma through the channel lumen. Their binding is facilitated by the repetitive depolarization of atrioventricular and cardiac tissue, a phenomenon described as use dependence. This explains why these drugs are not highly selective, but equipotent for the myocardium, the atrioventricular conducting tissue, and the vasculature. (e) Dihydropyridines act through selective vasodilatation and may increase heart rate and contractility via a reflex mechanism. On the contrary, phenylalkylamines and diltiazem act through a combination of effects, including reduction of afterload, heart rate, and contractility. When taken together, all these differences distinguish the preferential clinical utilization of one of these compounds for a given cardiovascular pathology.