Occlusion pressure in the first 100 ms of inspiration (P0.1) as an index of the possibility of decreasing respiratory support in acute respiratory failure

The need in making the process of transfer of patients to spontaneous respiration using ventilation of the lungs with inspiratory pressure support (VLIPS) after prolonged mechanical ventilation of the lungs prompted the authors to analyze the prognostic value of criteria traditionally used by the physician to cease or decrease the respiratory support (vital capacity of the lungs, peak spontaneous flow, PaO2, etc.) and the P0.1 occlusion pressure in the airways at the end of the first 100 msec of inhalation. This latter value proved to be the most sensitive (88%), specific (86%), positive (95%) and negative (67%) prognostic value in predicting the results of decrease of respiratory support under conditions of VLIPS. The P0.1 value determining the result of decrease of respiratory support in patients with parenchymatous pulmonary diseases under conditions of VLIPS is 3.8 cm H2O.     

Randomised trial of elective continuous positive airway pressure (CPAP) compared with rescue CPAP after extubation

AIM: To determine if a weaning regimen on flow driver continuous positive airway pressure (CPAP) would decrease the number of ventilator days but increase the number of CPAP days when compared with a rescue regimen. METHODS: Fifty eight babies of 24-32 weeks gestation with respiratory distress syndrome (RDS) were studied prospectively. After extubation they were randomly allocated to receive CPAP for 72 hours (n = 29) according to a weaning regimen, or were placed in headbox oxygen and received CPAP only if present "start CPAP" criteria were met (n = 29, rescue group). RESULTS: There was no difference in successful extubation at 72 hours, 1 and 2 weeks, between the groups in terms of the number of reventilation episodes, reventilation days, or in total days of CPAP. Birthweight, gestational age, race, day of first extubation, antenatal or postnatal steroids, patent ductus arteriosus status and maximal mean airway pressure used were of no value in predicting success or failure at 72 hours, 1, or 2 weeks. CONCLUSION: The weaning regimen did not decrease the number of ventilator days or days on CPAP compared with the rescue regimen. The rescue regimen on flow driver CPAP seems to be a safe and effective method of managing a baby of 24-32 weeks gestation who has been ventilated for RDS or immature lung disease.     

Epidemiology of porcine reproductive and respiratory syndrome (PRRS): an overview

PRRS disease was first recognised in the USA in 1987 and in Europe in 1990 and since then the disease has spread widely throughout many pig-producing countries. After a severe epidemic phase, the infection has become endemic. The prevalence of infection is generally high in infected countries. However, in areas with a low density of pigs, infection may spread slowly and if infected animal movements are not significant, farm-to-farm spread can be controlled and prevalence of infection maintained at a low level. The PRRS virus (PRRSV) was completely unknown before 1986, and the question of its origin remains unanswered. The exact epidemiologic relationship between American and European strains of PRRSV is difficult to establish because different isolates appear to belong to two distinct sub-populations which are only distantly antigenically related. In the environment, virus survival is optimal when temperature is cold and when ultra-violet light exposure is low (little sunshine). These conditions are easily attained in winter and that may explain why virus spread increases during this period. Pigs of any age (including wild boars) are the only animals known to be naturally infected with PRRSV. Relatively close contact between pigs is the primary factor in virus transmission. Aerial transmission is a second mechanism of spread, particularly in winter and particularly over distances of less than 3 km. A third route of transmission is via semen. The role of fomites is not clearly documented, however since the virus is excreted in faeces and urine, slurry should be considered as a potential source of contamination. Within herds, the virus spreads rapidly with up to 85 to 95% of pigs in a herd becoming sero-positive within two to three months. Thereafter, virus activity persists for extended periods (several month to years). Nevertheless, some authors have reported spontaneous elimination of PRRSV from infected farms. For the future, there remain questions concerning the possible evolution of the disease (in terms of its sanitary and economic impacts), and the possible influence of vaccines on the epidemiological features of PRRS.     

Malignant hyperthermia: attempt at an early diagnosis by means of determination of creatine phosphokinase (CPK) and its isoenzymes

Creatinphosphokinase (CPK) was elevated in sera of patients with malignant hyperthermia and in sera of some of their relatives. Only the MM-isoenzyme (but not the MB- or the BB-isoenzyme) could be detected by paperchromatographic analysis. In some of the patients elevation of muscle aldolase was also observed. Thus, the appearance of the BB-isoenzyme in sera of patients with malignant hyperthermia, as described by another group of investigators, was not confirmed. No specific screening method exists as yet to detect patients with a high risk of developing this often lethal reaction to anesthesia. However, in patients without muscle disease or trauma and without prior i.m. injections, myocardial infarction or major physical strain, elevation of CPK in serum should be interpreted as meaning that malignant hyperthermia may develop during anesthesia. The pathophysiology of malignant hyperthermia is discussed.     

Three phase 99Tcm (V)DMSA scintigraphy in Paget's disease: an indicator of pamidronate effect

The use of three phase 99Tcm (V)DMSA scintigraphy is reported in a patient with Paget's disease of bone before and after intravenous pamidronate therapy. It was a useful modality for estimating the activity of Pagetoid lesions and the therapeutic effect of pamidronate, from a different aspect to bone scintigraphy. Three phase 99Tcm (V)DMSA scintigraphy evaluates both the blood flow and the metabolic activity of Pagetoid bone.     

Possible presence of calcium channel blocker(s) in Rubia cordifolia: an indigenous medicinal plant

Crude extract of Rubia cordifolia (RC) was tested in isolated tissue preparations for its possible calcium channel antagonistic activity. RC suppressed the spontaneous contractions of guinea-pig atria, rabbit jejunum and rat uterus in a concentration dependent manner (0.1-3 mg/ml). In rabbit aorta, it inhibited norepinephrine (10 microM) and KCl (80 mM) induced contractions. Replacement of physiological salt solution with calcium free solution abolished the spontaneous movements of rabbit jejunum. However, addition of calcium (25 micrograms/ml) in the tissue bath restored the spontaneous movements. When the tissues were pretreated with plant extract (1 mg/ml) or verapamil (0.5 microgram/ml), addition of calcium failed to restore spontaneous contractions. These results indicate that the plant extract exhibits spasmolytic activity similar to that of verapamil suggestive of presence of calcium channel blocker like constituent(s) in this plant.     

Measurement of respiratory effort (esophageal pressure) and estimation of resistance of the upper airway in polysomnography: indications, limitations and results

During polysomnography, measurement of airflow and respiratory effort are essential for classifying the type of respiratory event and for evaluating the efficacy of treatment. There are various ways to measure respiratory effort, the reference technique being oesophageal manometry. This measures fluctuations in intrathoracic pressure which correspond to variations in upper airway resistance and therefore allows differentiation between central and obstructive respiratory events. Thus the simple snorer can be distinguished from an individual with the upper airway resistance syndrome (UARS). In the UARS abnormally high resistance develops in the upper airway in the absence of identifiable apnoeas and hypopnoeas. The characteristic cresendo-decresendo pattern of the oesophageal pressure signal, when associated with the micro-arousals which are responsible for the hypersomnolence, is pathognomonic of this condition. The clinical application of oesophageal manometry is limited by its poor tolerance in certain individuals and by the potential deleterious effect the catheter itself has on sleep quality and on the dynamics of the upper airway. Other less invasive techniques, such as nasal pressure and pulse transit time, are currently under evaluation.     

Early age at repair prevents restrictive right ventricular (RV) physiology after surgery for tetralogy of Fallot (TOF): diastolic RV function after TOF repair in infancy

Single-unit spike trains recorded from parietal cortex of monkeys performing a tactile short-term memory task show characteristic fluctuations (transitions) in their firing frequency that are related to memory. Spike trains recorded during the memory period, when the animal must retain information for the short term, show a higher rate of such transitions than spike trains recorded during intertrial baseline periods. In the present study, an analysis of multiple temporal resolutions over which these transitions are observed reveals that the memory-related transitions occur most prominently in the 25-50 Hz range. The results of this study suggest that, in the monkey, high frequency fluctuations of neuronal discharge in the parietal cortex are correlated with haptic short-term memory. The presence of such fluctuations are also consistent with theoretical models of short-term memory.     

kan-1 (bile acid CoA:amino acid N-acyltransferase) messenger RNA as a novel predictive indicator for prognosis of hepatocellular carcinoma patients after partial hepatectomy

We identified kan-1 complementary DNA (cDNA), the sequence of which is identical to bile acid CoA:amino acid N-acyltransferase (BAT), a liver enzyme that catalyzes the conjugation of bile acids with glycine or taurine. Kan-1(BAT) messenger RNA (mRNA) levels of the resected specimens obtained from 37 hepatocellular carcinoma (HCC) patients were studied in an attempt to evaluate prognostic significance in HCC patients after partial hepatectomy. Using Northern blot hybridization, kan-1(BAT) mRNA levels were quantified in tumorous and nontumorous tissues, and the ratio of the former to the latter was defined as the kan-1(BAT) ratio. Twelve patients had a kan-1(BAT) ratio < 0.5 (low kan-1[BAT] ratio), and 25 patients had a ratio >0.5 (high kan-1[BAT] ratio). The patients with a low kan-1(BAT) ratio demonstrated poorer survival than the patients with a high kan-1(BAT) ratio (P = .0013). The overall estimated hazard ratio for death in patients with a low kan-1(BAT) ratio was 68.05 according to a multivariate model (P = .0005). Thus, the kan-1(BAT) ratio may serve as a new molecular prognostic marker in HCC patients, following hepatic resection.     

Increased NAD(P)H oxidase-mediated superoxide production in renovascular hypertension: evidence for an involvement of protein kinase C

BACKGROUND: Angiotensin II infusion has been shown to cause hypertension and endothelial dysfunction and to increase superoxide (O-.2) production in vascular tissue, mainly via an activation of nicotinamide adenine dinucleotide (phosphate) [NAD(P)H]-dependent oxidase, the most significant O-.2 source in endothelial and/or smooth muscle cells. With these studies, we sought to determine whether endothelial dysfunction in renovascular hypertension is secondary to an activation of these oxidases. METHODS: Endothelial function in aortas from rats with two kidney-one clip (2K-1C) hypertension and age-matched controls was assessed using isometric tension studies in organ chambers. Changes in vascular O-.2 production were measured using lucigenin-enhanced chemiluminescence and electron spin resonance spectroscopy. RESULTS: In hypertensive animals, relaxation to endothelium-dependent (acetylcholine) and endothelium-independent nitrovasodilators (nitroglycerin) was impaired. Constriction to a direct activator of protein kinase C (PKC) phorbol ester 12,13 dibutyrate (PDBu) was enhanced, and vascular O-.2 was significantly increased compared with controls. Vascular O-.2 was normalized by the PKC inhibitor calphostin C, by the inhibitor of flavin-dependent oxidases, diphenylene iodonium, and recombinant heparin-binding superoxide dismutase, whereas inhibitors of the xanthine oxidase (oxypurinol), nitric oxide synthase (NG-nitro-l-arginine) and mitochondrial NADH dehydrogenase (rotenone) were ineffective. Studies of vascular homogenates demonstrated that the major source of O-.2 was a NAD(P)H-dependent oxidase. Incubation of intact tissue with PDBu markedly increased O-. 2, the increase being significantly stronger in vessels from hypertensive animals as compared with vessels from controls. Endothelial dysfunction was improved by preincubation of vascular tissue with superoxide dismutase and calphostin C. CONCLUSIONS: We therefore conclude that renovascular hypertension in 2K-1C rats is associated with increased vascular O-.2 leading to impaired vasodilator responses to endogenous and exogenous nitrovasodilators. Increased vascular O-.2 is likely secondary to a PKC-mediated activation of a membrane-associated NAD(P)H-dependent oxidase.     

Suppression of luteal steroidogenesis by an LHRH antagonist (Nal-Lys antagonist: antide) in vitro during early pregnancy in the rat

Gap-junctional intercellular communication (GJIC) in 20 primary human liver tumors with different degrees of malignancy has been studied at the functional and molecular levels. When GJIC capacity was determined by dye-transfer assay performed directly with freshly removed tumor tissue, significant reduction was found in all samples, regardless of their morphology. In addition, a selective lack of GJIC between tumor and surrounding non-tumorous cells was observed in some cases, probably due to the physical separation between them resulting from encapsulation of tumors. There was, however, no essential change in the level of expression of the major liver gap-junction protein, connexin (cx) 32, in liver tumors as measured by Northern and Western blot analyses. Immunohistochemical study revealed aberrant localization of cx 32 in the majority of malignant liver tumors. Instead of cytoplasmic membrane localization at intercellular contacts, cx 32 was detected mainly either intracytoplasmically or in plasma membrane free from contact with other cells. We did not detect any mutation in the coding sequence of the cx 32 gene from any of the human liver tumors we tested. Thus it is likely that the aberrant localization of cx 32 in tumor cells is due to disruption of the mechanisms for establishment of this protein into gap-junction plaques, rather than to structural abnormality of the cx 32 protein itself. Another member of the connexin family, cx 43, not detectable in non-tumorigenic hepatocytes, was expressed in several tumors, especially in invasive areas, but was detected in only a few tumor cells and was localized intracytoplasmically, suggesting that cx 43 protein is not involved in GJIC in the tumors.