Aerosolized prostacyclin and inhaled nitric oxide in septic shock — different effects on splanchnic oxygenation?

Objectives To compare the effects of inhaled nitric oxide and aerosolized prostacyclin (PGI₂) on hemodynamics and gas exchange as well as on the indocyanine-green plasma disappearance rate and gastric intramucosal pH in patients with septic shock.Design Prospective, randomized, interventional clinical study.Setting Intensive care unit in a university hospital.Patients Sixteen patients with pulmonary hypertension and septic shock according to the criteria of the ACCP/SCCM consensus conference all requiring norepinephrine and/or epinephrine to maintain mean arterial blood pressure above 65 mmHg.Methods and interventions Patients were randomly assigned to receive either nitric oxide or aerosolized prostacyclin. Nitric oxide was inhaled using a commercially available delivery system, prostacyclin was administered with a modified ultrasound nebulizer. Both nitric oxide and prostacyclin were incrementally adjusted to obtain a 15% decrease of mean pulmonary artery pressure. Hemodynamics and gas exchange as well as indocyaninegreen plasma disappearance rate and gastric intramucosal pH were determined at baseline after 90 min in steady state, after 90 min of nitric oxide inhalation or prostacyclin aerosol administration had elapsed in stable conditions, and after 90 min in stable conditions after nitric oxide or prostacyclin with-drawal.Results Both inhaled nitric oxide and aerosolized prostacyclin selectively reduced the mean pulmonary artery pressure from 35±4, 30±4 mmHg (p<0.05) and 34±4 to 30±3 mmHg (p<0.05) respectively; after removal of nitric oxide and prostacyclin, the mean pulmonary artery pressure returned to the baseline values. Systemic hemodynamics remained unaltered during the vasodilator treatment. While the mean PaO₂ was not significantly influenced, it increased in 4/8 of the NO- and 3/8 of the PGI₂ — treated patients. Neither of the drugs influenced indocyanine-green plasma disappearance rate, but prostacyclin — unlike nitric oxide — significantly increased gastric intramucosal pH (from 7.26±0.07 to 7.30±0.05,p<0.05) which remained elevated in four of these patients after prostacyclin removal, and decreased the arterial-gastric mucosal pressure of carbon dioxide gap from 19±6 to 15±4 mmHg (p<0.05).Conclusions Our data suggest that aerosolized prostacyclin — unlike nitric oxide — has similar beneficial effects on splanchnic perfusion and oxygenation as intravenous prostacyclin without detrimental effects on systemic hemodynamics. The different effects of prostacyclin and nitric oxide might be explained by the longer half-life of prostacyclin associated with a certain spillover into the systemic circulation.Presented in part at the Masterclass Symposium Sepsis in the ICU, Maastricht, June 27–29, 1995     

Closing the theory—practice gap: a model of nursing praxis

Summary

• ? Despite the efforts of nursing theorists, educationalists and practitioners, the theory-practice gap continues to defy resolution. This paper argues that only by reconsidering the relation between theory and practice can the gap be closed.
• ? Drawing upon ideas from teaching and other practice-based disciplines, including nursing, the article suggests that the current model of viewing theory as informing and controlling practice should give way to a mutually enhancing model in which theory is derived from practice, and in turn influences future practice.
• ? This coming together of theory and practice is referred to as nursing praxis, and suggests that informal theory should be unique to each individual encounter with each patient.
• ? The clinical nurse is thus not only a practitioner, but a theorist and researcher, who responds to patients not according to some grand, inflexible theory, but by the process of reflection-in-action, drawing upon their expertise and a repertoire of past experiences and encounters.

     

Human erythrocyte band 3 (EPB3) polymorphism: Analysis of blood and bloodstains by an immunodetection method and frequency of the EPB3* Memphis variant

Summary The erythrocyte band 3 (EPB3) variant, band 3 Memphis (EPB3*Memphis), was detected by immunoblotting with a monoclonal antibody to the 41 kDa cytoplasmic N-terminal domain of band 3 without protease treatment of erythrocytes. EPB3*Memphis was also detected by immunoblotting from 3-month-old bloodstains subjected to -chymotrypsin treatment. A population genetic study using this method indicated that the EPB3 variant would be useful for forensic work in Japan, since the frequency of this variant in Japanese (Wakayama prefecture) is relatively high (0.159).     

Experimental approach to the pathogenesis of the anomalies of amniotic disease

By intra-adnexal injection of glucose in the rabbit embryo, we were able to stimulate all the anomalies associated with "Amniotic Disease". Since we were even able to obtain amniotic bands, this study provides an excellent experimental model of this disease. Resulting lesions occur early in development, corresponding to the first trimester of human gestation. All of the anomalies can ultimately be explained by the destruction of the most superficial cells: epiblastic cells of the embryo and the amnion, subjacent mesenchyme, and endothelial cells. The subsequent lack of interaction between these cells and the importance of the anatomical localizations of resulting hematomas can lead to the pathogenetic approach to this disease. In light of the present study, the disease appears to be caused by an external factor within the amniotic fluid. The exact nature of the destructive agent(s) remains a mystery in man.     

Current therapy of retrolental fibroplasia. Retinopathy of prematurity

Retrolental fibroplasia, frequently referred to now as the "retinopathy of prematurity," has shown an increased incidence in recent years. This is apparently due to advances in neonatal care, which have resulted in a four- to five-fold improvement in the survival of the extremely low birthweight infants and it is these infants who are at the highest risk of developing retrolental fibroplasia. The use of large supplements of vitamin E, a known antioxidant, is discussed along with other forms of therapy.     

Endothelins Inhibit Junctional Permeability in Cultured Mouse Astrocytes

Endothelins, a family of potent vasoconstrictor peptides initially characterized in peripheral tissues, have also been reported to be synthesized in the brain. In this structure several cell types, including astrocytes, endothelial cells and certain neurons, are potential targets for these peptides. In astrocytes, endothelins induce changes in the concentration of several second messengers (calcium, diacylglycerol, arachidonic acid, cAMP) known to be involved in the regulation of gap junction channels. Using the scrape loading/dye transfer technique we have observed that two isoforms of endothelin, endothelin-1 and endothelin-3, strongly inhibit the extent of dye-coupling between confluent astrocytes, suggesting that gap junction permeability was reduced. This inhibitory effect on dye coupling was reproduced by the snake venom sarafotoxin. When used at 10⁻⁷ M, these three compounds had inhibitory effects on gap junction channels which were comparable to those induced by the well known uncoupling agents octanol and halothane. In the absence of extracellular calcium, the effects of endothelins were largely prevented, suggesting that second messengers linked to the activation of phospholipases C and/or A₂, which both are dependent on external calcium, could be involved in the uncoupling mechanism.     

Plastic and Reconstructive Body Contouring in the Post-vertical Banded Gastroplasty Patient: a retrospective review

Class IV obesity (body mass index > 40) is associated with an increased risk of a variety of health problems, many of them potentially life-threatening or life-shortening. Vertical banded gastroplasty (VBG) is currently the most frequently performed surgical procedure used to restrict food intake and assist with weight loss. After massive weight loss, however, redundant abdominal and breast tissue can result in physiological and psychological problems related to an unusual body habitus. Patients complain of difficulties with daily activities, choice of clothing, social acceptance, etc. Body contouring has proven to be an important part of the rehabilitation of the morbidly obese patient, and we have therefore reviewed the records of 55 patients who experienced massive weight loss following VBG and then underwent abdominoplasty with or without mammoplasty/mastopexy, in order to assess the parameters which will be seen more frequently in the future by plastic surgeons as bariatric surgery becomes more widely accepted and performed.     

Prefrontal cortical projections to the cholinergic neurons in the basal forebrain

The prefrontal cortex (PFC) projections to the basal forebrain cholinergic cell groups in the medial septum (MS), vertical and horizontal limbs of the diagonal band of Broca (VDB and HDB), and the magnocellular basal nucleus (MBN) in the rat were investigated by anterograde transport of Phaseolus vulgaris leuco-agglutinin (PHA-L) combined with acetylcholinesterase (AChE) histochemistry or choline acetyltransferase (ChAT) immunocytochemistry. The experiments revealed rich PHA-L-labeled projections to discrete parts of the basal forebrain cholinergic system (BFChS) essentially originating from all prefrontal areas investigated. The PFC afferents to the BFChS display a topographic organization, such that medial prefrontal areas project to the MS, VDB, and the medial part of the HDB, whereas the orbital and agranular insular areas predominantly innervate the HDB and MBN, respectively. Since the recurrent BFChS projection to the prefrontal cortex is arranged according to a similar topography, the relationship between the BFChS and the prefrontal cortex is characterized by reciprocal connections. Furthermore, tracer injections in the PFC resulted in anterograde labeling of numerous "en passant" and terminal boutons apposing perikarya and proximal dendrites of neurons in the basal forebrain, which were stained for the cholinergic marker enzymes. These results indicate that prefrontal cortical afferents make direct synaptic contacts upon the cholinergic neurons in the basal forebrain, although further analysis at the electron microscopic level will be needed to provide conclusive evidence.     

Light-adaptive effects of retinoic acid on receptive field properties of retinal horizontal cells

Besides its role in ocular development, retinoic acid (RA), which is a light-correlated byproduct of the phototransduction cycle, was recently shown to affect light-driven synaptic plasticity in the outer plexiform layer of the adult fish retina. Tuning by ambient light conditions of the retinal network properties is very prominent in outer plexiform layer circuits, and we therefore examined whether RA could affect cone horizontal cell physiology similar to ambient light. Performing intracellular recordings and dye injections in the dark-adapted inverted eyecup preparation of the carp, we found that RA reduced the receptive fields of horizontal cell somata and impaired gap junctional communication. This action was not observed among coupled axon terminals of horizontal cells and appeared to be stereospecific because it could only be attributed to all-trans and 13-cis RA but not to the 9-cis isomer and photoisomerized all-trans RA. Modulation of receptive field size occurred independently of the dopaminergic system. Furthermore, RA affected the light responsiveness of cone horizontal cells. Compared to the dark-adapted condition, responsiveness to intense light stimulation was enhanced but decreased when low intensities were used. Moreover, following RA treatment H2-type horizontal cells of dark-adapted retinae which do not give rise to colour-opponent light properties became colour-opponent and performed depolarizing responses to long-wavelength stimulation. In all these cases RA perfectly matched the effects of light adaptation, supporting the notion that RA acts as an endogenous neuromodulator.     

Left Ventricular Anomalous Muscle Band and Electrocardiographic Repolarization Changes

A child with considerable electrocardiographic (ECG) repolarization abnormalities is reported in whom, after clinical and hemodynamic evaluation, only a large muscular false tendon within the left ventricular cavity was found. The genesis of the ECG changes in such cases is discussed, and the differential diagnosis from apical hypertrophic cardiomyopathy is analyzed.