Angiotensin II induces contraction and proliferation of human hepatic stellate cells

BACKGROUND & AIMS

Circulating levels of angiotensin II (ANGII), a powerful vasoconstrictor factor, are frequently increased in chronic liver diseases. In these conditions, hepatic stellate cells (HSCs) proliferate and acquire contractile properties. This study investigated the presence of receptors for ANGII and the effects of ANGII in human HSCs activated in culture.

METHODS

The presence of ANGII receptors was assessed by binding studies. The effects of ANGII on intracellular calcium concentration ([Ca(2+)](i)), cell contraction, and cell proliferation were also assessed.

RESULTS

Binding studies showed the presence of ANGII receptors of the AT1 subtype. ANGII elicited a marked dose-dependent increase in [Ca(2+)](i) and cell contraction. Moreover, ANGII stimulated DNA synthesis and increased cell number. All these effects were totally blocked by losartan and reduced by nitric oxide donors or prostaglandin E(2). The effects of ANGII were barely detectable in quiescent cells (2 days in culture), suggesting that phenotypic transformation of HSCs is associated with a marked increase in the effects of ANGII.

CONCLUSIONS

ANGII induces contraction and is mitogenic for human-activated HSCs by acting through AT1 receptors. These results suggest that activated HSCs are targets of the vasoconstrictor action of ANGII in the intrahepatic circulation.

Bacterial colonization patterns in mechanically ventilated patients with traumatic and medical head injury. Incidence, risk factors, and association with ventilator-associated pneumonia

We prospectively evaluated the relation of upper airway, lower airway, and gastric colonization patterns with the development of pneumonia and its etiology in 48 patients with surgical (n = 25) and medical (n = 23) head injury. Initial colonization was assessed by cultures of nasal and pharyngeal swabs, tracheobronchial aspirates, gastric juice, and bronchoscopically retrieved protected specimen brush. Follow-up colonization was determined until the end points extubation, suspected ventilator-associated pneumonia (VAP), or death. The initial colonization rate at any site at ICU admission was 39/47 (83%). It mainly accounted for Group I pathogens (Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae) of the upper and lower airways. At follow-up, colonization rates with Group II pathogens (Gram-negative enteric bacilli and Pseudomonas spp.) increased significantly. The high initial bacterial load with Group I pathogens of the upper airways and trachea decreased during Days 2 to 4, whereas that of Group II pathogens increased. Upper airway colonization was an independent predictor of follow-up tracheobronchial colonization (odds ratio [OR], 9.9; 95% confidence interval [CI], 1.8 to 56.3 for initial colonization with Group I pathogens; OR, 23.9; 95% CI, 3.8 to 153.3 for follow-up colonization with Group II pathogens). Previous (short-term) antibiotics had a protective effect against colonization with Group I pathogens of the lower respiratory tract (OR, 0.2; 95% CI, 0.05 to 0.86), but they were a risk factor for colonization with Group II pathogens (OR, 6.1; 95% CI, 1.3 to 29). Initial tracheobronchial colonization with Group I pathogens was associated with a higher probability of early onset pneumonia (OR, 4. 1; 95% CI, 0.7 to 23.3), whereas prolonged antibiotic treatment (> 24 h) independently predicted late-onset pneumonia (OR, 9.2; 95% CI, 1.7 to 51.3). We conclude that patients with head injury are colonized in the airways mainly by Group I pathogens early in the evolution of illness. The upper airways represent the main reservoir for subsequent lower airway colonization with Group I pathogens. Previous (short-term) antibiotic treatment is protective against initial tracheobronchial colonization with Group I pathogens, but it represents a risk factor for subsequent lower airway colonization by Group II pathogens.

The greater risk of alcoholic cardiomyopathy and myopathy in women compared with men

OBJECTIVE

To compare the cardiac and muscular status of male and female alcoholics to determine if the response of women to alcohol is different from that of men.

DESIGN

Cross-section study.

SETTING

An ambulatory alcoholism treatment unit in the Hospital Clínic of Barcelona.

PATIENTS

Fifty asymptomatic alcoholic women, 100 asymptomatic alcoholic men, and 50 female nonalcoholic controls.

MAIN OUTCOME MEASURES

Studies included clinical assessment of muscle strength, muscle biopsy, echocardiography, radionuclide cardiac angiography, and treadmill exercise electrocardiographic recording test.

RESULTS

The mean strength of the deltoid muscle in alcoholic women was significantly lower than that in controls (P < .001) and half suffered clinical weakness (muscle strength > or = 2 SD below controls). Muscle biopsy specimens from half of all asymptomatic women showed histologic evidence of myopathy. Left ventricular ejection fractions tended to be depressed, and a third of the alcoholic women had evidence of cardiomyopathy. Muscular strength and ejection fractions in women were inversely correlated with the total lifetime dose of ethanol, whereas the left ventricular mass showed a direct correlation. Of the alcoholic men, 39% suffered clinical weakness, and 45% had histologic evidence of myopathy. Evidence of cardiomyopathy was found in almost a third of the men, and their ejection fractions also correlated inversely with the total lifetime dose of ethanol. However, the threshold dose for the development of cardiomyopathy was considerably less in women than in men, and the decline in the ejection fraction with increasing alcohol dose was significantly steeper (P < .001).

CONCLUSIONS

Despite the fact that the mean lifetime dose of alcohol in female alcoholics was only 60% that in male alcoholics, cardiomyopathy and myopathy were as common in female alcoholics as in male alcoholics. This finding, together with a more pronounced response of the ejection fraction to the dose of ethanol, indicates that women are more sensitive than men to the toxic effects of alcohol on striated muscle.

Comparison of systemic cytokine levels in patients with acute respiratory distress syndrome, severe pneumonia, and controls

BACKGROUND

The inflammatory response has been widely investigated in patients with acute respiratory distress syndrome (ARDS) and pneumonia. Studies investigating the diagnostic values of serum cytokine levels have yielded conflicting results and only little information is available for the differential diagnosis between ARDS and pneumonia.

METHODS

Clinical and physiological data, serum concentrations of tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6, and quantitative cultures of lower respiratory tract specimens were obtained from 46 patients with ARDS and 20 with severe pneumonia within 24 hours of the onset of the disease and from 10 control subjects with no inflammatory lung disease. Cytokine concentrations were compared between groups and determinants in addition to the diagnosis were tested.

RESULTS

Serum TNF-alpha levels were significantly higher in ARDS patients (67 (57) pg/ml) than in patients with severe pneumonia (35 (20) pg/ml; p = 0.031) or controls (17 (8) pg/ml; p = 0.007). For IL-1beta and IL-6 the observed differences were not statistically significant between patients with ARDS (IL-1beta: 34 (65) pg/ml; IL-6: 712 (1058) pg/ml), those with severe pneumonia (IL-1beta: 3 (4) pg/ml, p = 0.071; IL-6: 834 (1165) pg/ml, p = 1.0), and controls (IL-1beta: 6 (11) pg/ml, p = 0.359; IL-6: 94 (110) pg/ml, p = 0.262). TNF-alpha (standardised coefficient beta = 0.410, p<0.001) and IL-1beta (standardised coefficient beta = 0.311, p = 0.006) were most strongly associated with the degree of lung injury, even when the diagnostic group was included in the statistical model.

CONCLUSIONS

Serum TNF-alpha levels were higher in patients with ARDS than in those with severe pneumonia or in control subjects. Multivariate results suggest that the levels of systemic TNF-alpha and IL-1beta reflect the severity of the lung injury rather than the diagnosis.

Autonomic and peripheral neuropathies in patients with chronic alcoholism. A dose-related toxic effect of alcohol

OBJECTIVE

To assess autonomic and peripheral nervous system function in patients with chronic alcoholism.

DESIGN

A cross-sectional study.

PATIENTS

A consecutive sample of 107 alcoholic patients and 61 controls.

MAIN OUTCOME MEASURE

For autonomic assessment, heart rate variations during deep breathing and Valsalva maneuver and on standing were measured. Blood pressure response to standing up and to sustained handgrip were also evaluated. For assessment of the peripheral nervous system, an electrophysiologic examination was performed.

RESULTS

Alcoholic patients exhibited reduced heart rate variability compared with controls (P < .01, on all parasympathetic tests), whereas no differences in the mean values of the blood pressure responses between both groups were found. Twenty-six patients (24.3%) had criteria of autonomic neuropathy, and 34 (32%) had electrophysiologic criteria of peripheral neuropathy. None of the controls exhibited criteria of autonomic neuropathy, and only one had criteria of peripheral neuropathy. The estimated total lifetime dose of alcohol correlated inversely with the parasympathetic indexes (r = -.48 to -.51; P < .001 on all parasympathetic tests) and the sensory potential amplitudes of upper and lower limbs (r = -.43; P < .001, both limbs). Finally, a significant correlation between autonomic and peripheral neuropathies was observed (P = .01). By contrast, these lesions were not related to age, nutritional status, or other alcohol-related diseases.

CONCLUSIONS

Autonomic and peripheral neuropathies are common among hospitalized alcoholic patients. Alcohol appears to be toxic to autonomic and peripheral nerves in a dose-dependent manner.

Increased circulating leptin levels in chronic alcoholism

BACKGROUND

Malnutrition seen in chronic alcoholics is partly due to reduced energy intake. Leptin is a peptide hormone implicated in the regulation of appetite and expenditure of energy. The prevalence and significance of abnormal circulating leptin levels in alcoholics, as well as the relationship of these levels with nutritional status, liver disease, and ethanol consumption, remain uncertain.

METHODS

Serum leptin levels were measured in 60 active asymptomatic alcoholics, 20 active alcoholics with cirrhosis of the liver, 20 abstinent alcoholics, and 60 controls. Nutritional status and ethanol consumption also were assessed.

RESULTS

In the control group, circulating leptin levels (mean 4.7+/-0.3 microg/liter) correlated with body fat stores. Despite showing a lower fat area of the arm, active alcoholics had significantly higher leptin levels than the controls (p < 0.001), regardless of the presence of cirrhosis. By contrast, none of the abstinent alcoholics showed hyperleptinemia. In the multivariate regression analysis, the fat area of the arm (p < 0.001), the lifetime ethanol consumption (p = 0.007), and the number of cigarettes smoked per day (p = 0.02) were found to be independent factors that influenced leptin levels in active alcoholics. After we adjusted for age, fat area of the arm, and tobacco consumption, a significant correlation was observed between lifetime consumption of ethanol and serum leptin concentrations (r = 0.36, p < 0.001).

CONCLUSIONS

Circulating leptin levels are increased in a dose-dependent manner in chronic alcoholism, regardless of nutritional status or the presence of compensated liver disease.

Comparison of alcoholic cardiomyopathy in women versus men

To compare the prevalence and cardiac status of male and female alcoholics with alcoholic cardiomyopathy during a 5-year period, all chronic alcoholics with dilated cardiomyopathy who had clinical symptoms of heart failure were included. Alcoholic cardiomyopathy was diagnosed in 10 chronic alcoholic women and in 26 men; the prevalence of alcoholic cardiomyopathy was similar in both sexes. No significant differences were observed in age, nutritional parameters, and clinical and radiologic data of heart failure between the 2 groups. Alcoholic women reported a significantly lower daily dose of ethanol (p = 0.002), a shorter duration of alcoholism (p = 0.017), and a lower total lifetime dose of ethanol consumption (p = 0.001), and had a lower New York Heart Association functional class than men. Women also had lesser ventricular dysfunction than men. In a multivariate analysis, left ventricular systolic dysfunction was related to the total lifetime dose of ethanol consumption (p <0.04), but not to gender. Finally, when patients were matched for left ventricular ejection fraction, women had consumed a lower total lifetime dose of ethanol than men (p <0.001). The prevalence of alcoholic women with dilated cardiomyopathy was found to be similar to that of alcoholic men, although women required a lower total lifetime dose of ethanol to develop the disease.

Atrophy of the corpus callosum in chronic alcoholism

To determine the prevalence of corpus callosum atrophy in chronic alcoholics and its relationship to cognitive function and brain atrophy, a prospective clinicoradiologic study was carried out in 28 right-handed male patients with chronic alcoholism and 14 age- and sex-matched right-handed control subjects. Clinical evaluation, neuropsychological testing and measurement of the midsagittal corpus callosum area and thickness (genu, truncus and splenium), as well as the frontal lobe index and the width of the cortical sulci on T1- and T2-weighted magnetic resonance images were performed. Compared to controls, alcoholics had significantly decreased corpus callosum area and thickness, mainly in the genu. Two-thirds had a corpus callosum area 2 SD below the mean of the control group. The sagittal area of the corpus callosum body correlated negatively with the degree of frontal and cortical atrophies (r = -0.5579 and -0.6853, respectively p < 0.01, both). Alcoholics with corpus callosum atrophy exhibited impairment of visual and logical memories (p < 0.05 both) and those with reduced thickness of the genu showed impairment of frontal lobe tasks (p < 0.05). The reduction of corpus callosum indices (age-corrected) also correlated with the total lifetime dose of ethanol consumed (r = 0.6107, p < 0.001), but was not related to nutritional status or electrolyte imbalance. Atrophy of the corpus callosum is common among alcoholic patients and may reflect the severity and pattern of cortical damage. The degree of this atrophy also correlated with the severity of ethanol intake.

Arginine vasopressin induces contraction and stimulates growth of cultured human hepatic stellate cells

BACKGROUND & AIMS

Hepatic stellate cells (HSCs) are perisinusoidal cells believed to participate in the regulation of hepatic blood flow because of their contractile properties and presence of receptors for several vasoactive factors. It is unknown whether HSCs have receptors for vasopressin, one of the most potent endogenous vasoconstrictors. This study investigated the existence of receptors for and the effects of arginine vasopressin (AVP) on cultured human HSCs.

METHODS

intracellular calcium concentration ([Ca2+]i) and cell contraction were measured in individual cells loaded with fura-2 using a morphometric method with an epifluorescence microscope coupled to a CCD imaging system (Photometrics, Tucson, AZ). AVP-specific binding was measured with [3H]AVP. Mitogen-activated protein kinase (MAPk) activity and DNA synthesis were measured by in vitro phosphorylation of myelin basic protein and [3H]thymidine incorporation, respectively. Parallel experiments were performed in vascular smooth muscle cells.

RESULTS

AVP elicited a dose-dependent increase in [Ca2+]i and contraction of HSCs. Moreover, AVP increased MAPk activity, DNA synthesis, and cell number. These effects were similar to those observed in vascular smooth muscle cells and were blocked by a V1 receptor antagonist. The existence of V1 receptors was further confirmed by binding studies.

CONCLUSIONS

Human HSCs have V1-vasopressin receptors that induce effects similar to those observed in vascular smooth muscle cells. AVP may play a role in the regulation of HSC function.

Brain impairment in well-nourished chronic alcoholics is related to ethanol intake

To determine the influence of chronic ethanol intake on the central nervous system, we studied 40 asymptomatic, well-nourished, chronic alcoholics (mean age, 42.6 +/- 9.1 years) and 20 age-, sex-, and education-matched control subjects. Studies included neuropsychological testing, visual and short-latency auditory evoked potentials, and morphometric analysis of computed tomography scans. The mean daily ethanol consumption of the alcoholics was 204 gm over an average of 26.4 years. Compared to control subjects, chronic alcoholics exhibited a significant prolongation of the P100 latency of visual evoked potentials, and a prolongation and reduction in the amplitude of the latency of the V wave of short-latency auditory evoked potentials. These abnormalities were related to the lifetime dose of ethanol consumed. Brain morphometric analysis showed that alcoholics had a significantly greater degree of brain shrinkage with age, compared to control subjects. The cortical atrophy index correlated significantly with the lifetime ethanol consumption. Neuropsychological testing in alcoholics compared to controls revealed a significant impairment of frontal skills that was related to age, degree of scholarship, and the presence of frontal atrophy. In conclusion, well-nourished chronic alcoholics exhibited significant brain impairment, as demonstrated by neuropsychological testing, evoked potentials, and brain morphometric analysis, which was correlated with the lifetime dose of ethanol consumed.

In vitro and in vivo activation of rat hepatic stellate cells results in de novo expression of L-type voltage-operated calcium channels

Following chronic liver injury, hepatic stellate cells (HSCs) transdifferentiate into myofibroblast-like cells, which develop contractile properties and contribute to increased resistance to blood flow. We investigated whether this phenotypic activation includes changes in the expression of L-type voltage-operated Ca2+ channels (VOCC), which mediate Ca2+ influx and regulate cell contraction in vascular cell types. Rat HSCs were studied in the quiescent phenotype and after their activation in vitro (cultured on plastic for 14 days) and in vivo (isolated from rats with CCl(4)-induced cirrhosis). Patch-clamp studies showed Ca2+ currents through L-type VOCC in HSCs activated both in vitro and in vivo, whereas no currents were detected in quiescent HSCs. Moreover, binding studies with (3)H-isradipine, a specific L-type VOCC antagonist, showed a large number of binding sites in activated HSCs, while no specific binding was found in quiescent HSCs. Finally, messenger RNA (mRNA) encoding L-type VOCC was not detected in quiescent HSCs as assessed by reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis, whereas it was present in activated HSCs. Stimulation of L-type VOCC with KCl resulted in a marked increase in [Ca2+](i) followed by cell contraction in HSCs activated both in vitro and in vivo, whereas no effects were observed in quiescent HSCs. We conclude that the activation of HSCs is associated with up-regulation of L-type VOCC that mediate Ca2+ influx and cell contraction. These results may be relevant to the pathogenesis of portal hypertension.

High ethanol intake and malnutrition in alcoholic cerebellar shrinkage

To determine the influence of chronic ethanol intake and nutritional status on cerebellar shrinkage in alcoholism, we studied 12 undernourished patients with acute Wernicke's encephalopathy (WE), 12 undernourished and 24 well-nourished asymptomatic chronic alcoholics, and 24 age-matched well-nourished controls, using morphometric analysis of MRI scans with volumetry of the cerebellum. Alcoholics reported a mean daily intake of ethanol of 177+/-8 g over a period of 27+/-1 years. Most undernourished alcoholics and half of the well-nourished alcoholics, compared to one-tenth of the controls, showed a significant reduction in cerebellar volume (p< or =0.01, both). Alcoholics with cerebellar shrinkage (n=33) were older (p=0.05) and tended to report greater daily ethanol intake than alcoholics without cerebellar shrinkage (n=15), although not significantly so (p=0.09). Cerebellar volume correlated negatively with age in controls and asymptomatic alcoholics (r> or =0.52, p< or =0.01, both), with a significantly greater shrinkage for age in the latter (p=0.003). Logistic regression analysis showed that malnutrition (OR 6.6 [95%CI 1.7-25.6], p=0.005) and a daily ethanol intake of more than 140 g over ten years (OR 6.1 [95%CI 1.8-20.5], p=0.003) were independently associated with the development of cerebellar shrinkage.

A soft X-ray beamline for transmission X-ray microscopy at ALBA

The MISTRAL beamline is one of the seven phase-I beamlines at the ALBA synchrotron light source (Barcelona, Spain) that will be opened to users at the end of 2010. MISTRAL will be devoted to cryotomography in the water window and multi-keV spectral regions for biological applications. The optics design consists of a plane-grating monochromator that has been implemented using variable-line-spacing gratings to fulfil the requirements of X-ray microscopy using a reflective condenser. For instance, a fixed-focus condition independent of the included angle, constant magnification as well as coma and spherical aberration corrections are achieved with this system. The reported design is of wider use.

Chronic alcohol consumption increases serum levels of circulating endothelial cell/leucocyte adhesion molecules E-selectin and ICAM-1

A group of 30 chronic alcoholics without alcohol-related diseases and 30 controls (teetotallers) were selected to measure serum levels of endothelial adhesion molecules (AMs) (ICAM-1, VCAM-1, and E-selectin). ICAM-1 and E-selectin serum levels were higher in alcoholics, whereas VCAM-1 serum levels were similar in both groups. There was a significant correlation between daily alcohol intake and serum level of ICAM-1 (r = 0.49, P = 0.003) and E-selectin (r = 0.41, P = 0.02). A significant positive correlation between E-selectin and total lifetime dose of ethanol was also observed (r = 0.52, P = 0.003). These changes in serum levels of endothelial AMs of chronic alcoholics may reflect endothelial and/or immune activation, and could interfere with the reactions between immune cells and the endothelium.

Significance of type II fiber atrophy in chronic alcoholic myopathy

To determine the significance of type II fiber atrophy in alcoholic myopathy and its relationship with ethanol-related diseases a prospective study was carried out in 100 chronic alcoholics who showed clinical suspicion of skeletal myopathy. Measurement of muscle strength, laboratory analysis, nutritional assessment and open biopsy of deltoid muscle were performed in each case, as well as electrophysiological testing for peripheral neuropathy. Hepatic ultrasonography and liver biopsy, echocardiography and radionuclide cardiac scanning were carried out in selected subjects. According to histomorphometric analysis, type II fiber atrophy was found in 33 cases (33%), being selective for type II B fiber in 23 (70%). Skeletal myopathy was diagnosed in 61 cases, alcoholic cardiomyopathy in 26, peripheral neuropathy in 23 and cirrhosis in 12. Patients with type II fiber atrophy had a significantly higher total lifetime dose of ethanol, presented a greater incidence of skeletal myopathy and peripheral neuropathy, and exhibited significantly lower values of percentage of ideal body weight and lean body mass than their counterparts. However, the only independent factors for developing type II fiber atrophy were the coexistence of caloric malnutrition (p = 0.004) and the presence of skeletal myopathy (p = 0.043). Selective type II fiber atrophy is a non-specific finding in alcohol-induced muscle damage appearing, overall, in the patients with caloric malnutrition as well as in those with histologic evidence of myopathy.

Contraction of human hepatic stellate cells activated in culture: a role for voltage-operated calcium channels

BACKGROUND/AIMS

Voltage-operated calcium channels are essential for the regulation of vascular tone and are potential targets for vasodilating agents. They regulate calcium entry and thereby cell contraction in vascular cell types. Hepatic stellate cells in the activated phenotype have contractile properties and could participate in the regulation of sinusoidal blood flow. Thus, this study was aimed at investigating the presence of voltage-operated calcium channels in human hepatic stellate cells activated in culture and the effects of their stimulation on intracellular calcium concentration ([Ca2+]i) and cell contractility.

METHODS

Binding studies using [3H]-nitrendipine were performed to demonstrate the presence of voltage-operated calcium channels. Voltage-operated calcium channels were stimulated by causing cell membrane depolarization either by electrical field stimulation or extracellular high potassium. [Ca2+]i and cell contraction were measured in individual cells loaded with fura-2 using a morphometric method with an epifluorescence microscope coupled to a charge-coupled device-imaging system.

RESULTS

Binding studies demonstrated the existence of voltage-operated calcium channels in human activated hepatic stellate cells (7.1+/-1.4x10(4) sites/cell with a Kd of 2.1+/-0.1 nM). Both electrical field stimulation and potassium chloride-induced cell depolarization resulted in a marked and prolonged increase in [Ca2+]i followed by intense cell contraction. The degree of cell contraction correlated with the intensity of calcium peaks. Removal of extracellular calcium or preincubation of cells with nitrendipine, a specific antagonist of voltage-operated calcium channels, completely blocked the effects on [Ca2+]i and cell contraction, whereas preincubation of cells with BayK-8644, a specific agonist of voltage-operated calcium channels, increased calcium peaks and contraction.

CONCLUSION

Activated human hepatic stellate cells have a large number of voltage-operated calcium channels, the activation of which is associated with an increase in [Ca2+]i followed by marked cell contraction. Voltage-operated calcium channels probably play an important role in the regulation of activated hepatic stellate cells contractility.

Acute ethanol treatment decreases intracellular calcium-ion transients in mouse single skeletal muscle fibres in vitro

Alcohol misuse frequently leads to muscle weakness, which may also occur in the setting of acute and chronic alcoholic myopathies. At the cellular level, ethanol has been found to interfere with signalling mechanisms in cardiac myocytes, skeletal myotubes, and smooth muscle cells. In this study, we focused on the effects of ethanol on the intracellular calcium ([Ca(2+)](i)) transients responsible for excitation-contraction (EC) coupling in isolated mouse skeletal fibres loaded with the fluorescent Ca(2+) indicator fura-2. Following electrical stimulation, ethanol caused a significant reversible dose-dependent reduction in [Ca(2+)](i) transient amplitude, already significant at 100 mM ethanol (P = 0.03), without modifying resting [Ca(2+)](i). Evaluating the potential loci for the effects of ethanol, we indirectly measured sarcolemmal Ca(2+) entry by monitoring Mn(2+)-quenching of intracellular fura-2 via the nitrendipine-sensitive Ca(2+) channels during electrical pacing. Ethanol at doses of 20 mM and greater caused a dose-dependent reduction in the rate of fura-2 quenching (all at P<0.05). Moreover, the intracellular pool of Ca(2+) releasable by caffeine was found to be reduced at a minimum of 300 mM ethanol (P = 0.05). We conclude that ethanol reduces the [Ca(2+)](i) transients underlying EC coupling in single mouse skeletal muscle fibres. This acute effect of ethanol was primarily due to an inhibitory effect of ethanol on sarcolemmal Ca(2+) influx via voltage-operated Ca(2+)-channels and, to a lesser extent, to a reduction in the Ca(2+) sarcoplasmic reticulum loading state. This inhibitory effect of ethanol may be implicated in the development of muscle weakness with alcohol consumption.

Low-dose ethanol consumption allows strength recovery in chronic alcoholic myopathy

Chronic skeletal myopathy may affect one third of chronic alcohol misusers. It is generally accepted that abstinence allows partial recovery, and that continued high-dose ethanol consumption progressively deteriorates muscle function. However, the effect of low-dose ethanol consumption in alcoholic myopathy has not been studied. We studied 58 chronic alcoholic male patients with biopsy-proven chronic alcoholic myopathy over 5 years. We evaluated ethanol intake, biochemical and nutritional parameters, and assessed muscle strength. Eighteen patients who remained abstinent showed marked improvement in muscle strength. As expected, the 19 patients who persisted in high-dose ethanol consumption further diminished in their muscle strength. In the 11 patients who maintained low-dose (</=60 g ethanol/day) 'controlled' drinking, muscle strength improved (p=0.003), despite no change in nutritional and exercise status. There is a dose-dependent recovery in muscle strength according to the degree of ethanol consumption, and moderate controlled drinking of up to 60 g ethanol/day still allows improvement in muscle strength.

Ethanol acutely decreases calcium transients in cultured human myotubes

Ethanol consumption frequently leads to a number of skeletal muscle disorders, including acute and chronic alcoholic myopathy. Ethanol has been found to interfere with signal transduction mechanisms in cardiac and smooth muscle cells. We studied the effects of ethanol on the intracellular calcium ([Ca2+]i) transients responsible for excitation-contraction coupling in human myotubes from chronic alcoholic patients and healthy controls. Cultured myotubes were loaded with the fluorescent Ca2+ indicator fura-2 and evaluated on a single-cell basis. Following electrical stimulation, ethanol caused a significant reversible dose-dependent reduction in [Ca2+]i transient amplitude, achieving a mean decrease of 36+/-5% at 300 mM ethanol (p < 0.01), without modifying the basal [Ca2+]i. This acute effect of ethanol was similar in myotubes obtained from chronic alcoholics and controls. Similarly, ethanol caused a dose-dependent reduction of [Ca2+]i transient amplitude in control samples when depolarization was elicited by 100 mM KCl (p < 0.01). Several potential mechanisms of ethanol action were studied in control muscle samples. Sarcolemmal Ca2+ entry was measured indirectly by monitoring Mn2+-quenching of intracellular fura-2 via the nitrendipine-sensitive Ca2+ channels during electrical pacing. Ethanol at doses of 100 mM and greater caused a dose-dependent reduction in the rate of quench (p < 0.01). In addition, the intracellular pool of Ca2+ releasable by caffeine was found to be reduced at 300 mM ethanol (p < 0.05). We conclude that ethanol reduces the [Ca2+]i transients underlying excitation-contraction coupling in human myotubes, and that this occurs to a similar extent in cells obtained from chronic alcoholics and controls. This acute effect of ethanol was primarily due to an inhibitory effect of ethanol on sarcolemmal Ca2+ influx via voltage-operated Ca2+ channels, although there may also be an effect on the Ca2+ sarcoplasmic reticulum loading state.

Ceftolozane/tazobactam in the treatment of osteomyelitis and skin and soft-tissue infections due to extensively drug-resistant Pseudomonas aeruginosa: clinical and microbiological outcomes

Infections due to multidrug-resistant bacteria (MDR) are currently a clinical challenge, mainly in elderly patients. The antimicrobial spectrum, safety and efficacy of ceftolozane/tazobactam (C/T) make it an attractive option for the treatment of MDR bacterial infections beyond the indications approved to date. Here we report our experience with C/T in four cases of osteomyelitis and three cases of skin and soft-tissue infections due to extensively-drug-resistant Pseudomonas aeruginosa.

Washing machine associated 50 Hz detected as ventricular fibrillation by an implanted cardioverter defibrillator

This case report describes a patient with an automatic ICD who suffered a defibrillation shock without warning symptoms. An electrical interference can be observed in the stored EGM of the episode. The patient explained that the moment he felt the shock he was touching a washing machine. After correct grounding of this machine the patient did not suffer more inappropriate shocks.

Atrial natriuretic peptide antagonizes endothelin-induced calcium increase and cell contraction in cultured human hepatic stellate cells

Hepatic stellate cells (HSCs) participate in the regulation of hepatic microcirculation and have receptors for many vasoconstrictor factors. It is unknown whether HSCs have receptors for circulating vasodilators such as atrial natriuretic peptide (ANP). This study investigated the presence of ANP receptors in human HSCs and whether ANP antagonizes the effects of endothelin-1 in these cells. ANP receptors were assessed by binding and cross-linking studies, reverse-transcriptase polymerase chain reaction (PCR), and measuring intracellular cyclic guanosine monophosphate concentration. Intracellular calcium concentration ([Ca(2+)](i)) and cell contraction were measured in individual cells loaded with fura-2 using a morphometric method. Binding and cross-linking affinity experiments showed the existence of ANP receptors in human HSCs. PCR products with the expected length were obtained for guanylate cyclase A receptor, the physiological receptor of ANP, both in quiescent and activated human cells. ANP induced a dose-dependent increase in intracellular cyclic guanosine monophosphate concentration and blunted the increase in [Ca(2+)](i) elicited by endothelin-1. Most importantly, ANP markedly reduced cell contraction induced by endothelin-1. HSCs isolated from rats with carbon tetrachloride-induced cirrhosis showed a higher number of ANP receptors compared with HSCs isolated from normal rats, indicating that in vivo activation of HSCs is associated with an up-regulation of ANP receptors. These results indicate that human HSCs have receptors for ANP, the activation of which reduces the effects of endothelin-1 on [Ca(2+)](i) and cell contraction. ANP could participate in regulating the contractility of HSCs by antagonizing the effect of vasoconstrictors.

Persistence of intracranial diastolic flow in transcranial Doppler sonography exploration of patients in brain death

OBJECTIVE

The persistence of cerebral blood flow (CBF) in patients with whole brain death (BD) diagnosis is an unusual phenomenon. We describe patients with whole BD diagnosed despite persistence of intracranial blood flow on transcranial Doppler sonography (TDS).

MATERIALS AND METHODS

From January 2001 to December 2002, we reviewed the records of 11 patients. Etiology of BD was craniocephalic trauma in 2 cases, schemic cerebrovascular accident (CVA) in 4 cases, Hemorrhagic CVA in 3 cases, subaracnoid hemorrhage in 1 case, and acute hydrocephalus in 1 case. Six patients had a cerebral decompressive mechanism. In all patients, TDS was used to confirm BD after clinical diagnosis. Additionally, all patients underwent an electroencephalogram (EEG). In 3 patients cerebral angiography (CA) and in 2 others radionuclide angiography (RA) with Tc99m HMPAO were done.

RESULTS

All TDS studies showed persistent telediastolic positive flow in at least 1 artery. Because the TDS did not confirm the clinical diagnosis of BD, EEG tests were performed showing silence of bioelectrical activity. Those cases showed CA or RA results with a complete absence of CBF.

CONCLUSION

The TDS technique directly evaluates the intracranial but not the intracerebral circulation. For this reason, during the BD diagnosis for patients with previous decompressive techniques, it was possible to find persistence of intracranial telediastolic flow using TDS. In those cases, it is advisable to use other tests to confirm the clinical diagnosis of BD.

Reappraisal of the aetiology and prognostic factors of severe acute respiratory failure in HIV patients

The introduction of highly active antiretroviral therapy with protease inhibitors in 1996 has changed the morbidity and mortality of acquired immune deficiency syndrome patients. Therefore, the aetiologies and prognostic factors of human immunodeficiency virus (HIV)-infected patients with life-threatening respiratory failure requiring intensive care unit (ICU) admission need to be reassessed. From 1993 to 1998, we prospectively evaluated 57 HIV patients (mean+/-SEM age 36.5+/-1.3 yrs) admitted to the ICU showing pulmonary infiltrates and acute respiratory failure. A total of 21 and 30 patients were diagnosed as having Pneumocystis carinii and bacterial pneumonia, respectively, of whom 13 and eight died during their ICU stay (p=0.01). Both groups of patients had similar age, Acute Physiology and Chronic Health Evaluation (APACHE) II score, and severity in respiratory failure. The number of cases with bacterial pneumonia admitted to ICU decreased after 1996 (p=0.05). Logistic regression analysis showed that (APACHE) II score >17, serum albumin level <25 g.(-1), and diagnosis of P. carinii pneumonia were the only factors at entry associated with ICU mortality (p=0.02). Patients with bacterial pneumonia are less frequently admitted to the intensive care unit after the introduction of highly active antiretroviral therapy with protease inhibitors in 1996. Compared to the previous series, it was observed that the few Pneumocystis carinii pneumonia patients that need intensive care still have a bad prognosis.

Human myofibroblastic hepatic stellate cells express Ca(2+)-activated K(+) channels that modulate the effects of endothelin-1 and nitric oxide

BACKGROUND/AIMS

High-conductance Ca(2+)-activated K(+) (BK(Ca)) channels modulate the effects of vasoactive factors in contractile cells. It is unknown whether hepatic stellate cells (HSCs) contain BK(Ca) channels and what their role in the regulation of HSCs contractility is.

METHODS

The presence of BK(Ca) channels in HSCs was assessed by the patch-clamp technique. The functional role of BK(Ca) channels was investigated by measuring intracellular calcium concentration ([Ca(2+)](i)) and cell contraction in individual cells after stimulation with endothelin-1 in the presence or absence of specific modulators of BK(Ca) channels.

RESULTS

BK(Ca) channels were detected by patch-clamp in most of the activated HSCs studied. Incubation of cells with iberiotoxin, a BK(Ca) channel blocker, increased both the sustained phase of [Ca(2+)](i) elicited by endothelin-1 and the number of cells undergoing contraction, while the use of NS1619, a BK(Ca) channel opener, induced opposite effects. Stimulation of HSCs with S-nitroso-N-acetyl-penicillamine (SNAP), a nitric oxide (NO)-donor, increased the opening of BK(Ca) channels and reduced the effects of endothelin-1. Conversely, iberiotoxin abolished the inhibitory effect of SNAP on endothelin-induced [Ca(2+)](i) increase and cell contraction.

CONCLUSIONS

Activated human HSCs contain BK(Ca) channels that modulate the contractile effect of endothelin-1 and mediate the inhibitory action of NO.