ACE mediates ventilator-induced lung injury in rats via angiotensin II but not bradykinin.

Ventilator-induced lung injury is characterised by inflammation and apoptosis, but the underlying mechanisms are poorly understood. The present study proposed a role for angiotensin-converting enzyme (ACE) via angiotensin II (Ang II) and/or bradykinin in acute lung injury. The authors assessed whether ACE and, if so, Ang II and/or bradykinin are implicated in inflammation and apoptosis by mechanical ventilation. Rats were ventilated for 4 h with low- or high-pressure amplitudes in the absence or presence of the ACE inhibitor captopril. Nonventilated animals served as controls. ACE activity, Ang II and bradykinin levels, as well as inflammatory parameters (total protein, macrophage inflammatory protein-2 and interleukin-6) were determined. Apoptosis was assessed by the number of activated caspase-3 and TUNEL (terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick-end labelling)-positive cells. Bronchoalveolar lavage fluid ACE activity, levels of total protein, inflammatory parameters and the number of apoptotic cells were increased in the high-pressure amplitude group as compared with the control group. Blocking ACE activity by captopril attenuated inflammation and apoptosis in the latter group. Similar results were obtained by blocking Ang II receptors, but blocking bradykinin receptors did not attenuate the anti-inflammatory and anti-apoptotic effects of captopril. The current authors conclude that inflammation and apoptosis in ventilator-induced lung injury is, at least in part, due to angiotensin-converting enzyme-mediated angiotensin II production.

Noradrenergic and cholinergic reinnervation of islet grafts in diabetic rats.

Grafted islets become denervated due to the islet transplantation procedure. The aim of the present study was 1) to examine whether islet grafts in the liver, the spleen, and under the kidney capsule in rats become reinnervated following the transplantation and experimental procedures used in our laboratory, 2) whether there is any difference in reinnervation at these different sites, and 3) how these results relate to previous physiological experiments. Isogeneic isolated islets were transplanted into diabetic Albino Oxford rats, resulting in normoglycaemia. After at least 5 wk, graft-receiving organs were removed and several antibodies were employed to detect insulin, neuron-specific proteins, and cholinergic and noradrenergic nerve fibers. Islets in all three receiving organs contained viable insulin-positive B-cells. Neuron-specific enolase (NSE) as well as the growth-associated protein B-50 was observed at all sites. The cholinergic marker choline acetyltransferase (ChAT) was localized in islets grafts at all sites, but with the lowest density in the spleen. Staining for the noradrenergic markers tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) was observed in islet grafts at all sites with the lowest density in grafts under the kidney capsule. All these neurochemical substances were most frequently observed in fibers associated with blood vessels, which may be the route along which nerves grow into the graft. It can be concluded that 1) islet grafts in the liver, in the spleen and under the kidney capsule become reinnervated; 2) the innervation pattern of the islet grafts differs only slightly from that in the control pancreatic islets; and 3) in combination with our previously physiological data, we can conclude that these nerve fibers are, at least partly, functionally active.

The influence of septicaemia on spontaneous motility in preterm infants.

The qualitative assessment of general movements (GMs) in preterm infants is a sensitive method to investigate the integrity of the central nervous system. The question arises whether systemic infections affect the quality of GMs in a similar fashion to brain lesions. We were able to provide an answer to this problem in six infants (gestational age 24.4-32.4 weeks, birth weight 600-1660 grams), who had initially normal GMs as analyzed from sequential video-recordings. All infants sustained a proven septicaemia (Candida albicans in two, Staphylococcus aureus in three, a coagulase-negative staphylococcus in one infant). Unintentionally, recordings were also made during the acute phase. The complexity and variability of the GMs remained largely intact in five of the six infants; only one infant had transiently abnormal GMs. Compared with 1 week before the acute phase, the speed and amplitude of the GMs were diminished, giving the GMs a sluggish appearance. One to two weeks after the acute phase of septicaemia, the quality of GMs, i.e. speed and amplitude, had normalized in all infants. This study demonstrates that it is possible to discriminate between abnormal GMs due to cerebral lesions and sluggish GMs due to severe systemic infections, when the complexity of the GMs is considered as the main characteristic for judgement of normality of GM-quality.

Spontaneous motility in preterm, small-for-gestational age infants. I. Quantitative aspects.

The developmental course of the quantitative aspects of early spontaneous motility was studied longitudinally in fourteen intrauterine growth-retarded infants, with a birth weight below the 5th percentile, in relation to perinatal variables, brain ultrasound findings and neurological outcome. Quantitative motility was studied during the preterm period until term age, from 1 h videotape recordings, using Prechtl's classification of different spontaneous movement patterns. Comparison to a low-risk reference group, consisting of preterm, appropriate-for-gestational age infants, showed that significant differences were inconsistent and obviously by chance, with the possible exception of a decreased rate of startles from the 2nd to the 6th postnatal weeks. A trend of increasing duration of GMs was present with increasing postnatal age. There were hardly any correlations between perinatal variables and quantitative motility, and if present the correlations were weak. Such correlations were found between the reduction of heart-rate variability on cardiotocography and the rate of startles and twitches during the first week and furthermore between the neonatal blood glucose level and the rate of isolated arm movements and total motility during the first week. This study demonstrates that intrauterine growth retardation has little or no influence on the quantitative aspects of spontaneous motility postnatally during the preterm period.

Qualitative assessment of general movements in high-risk preterm infants with chronic lung disease requiring dexamethasone therapy.

OBJECTIVE: The objective of this study was to determine in preterm infants at risk for severe chronic lung disease (1) the quality of general movements (GMs) and (2) the effect of dexamethasone treatment on spontaneous motor activity. STUDY DESIGN: In 15 very low birth weight infants the quality of GMs was assessed from repeated videotape recordings. Recordings were made at weekly intervals during the preterm period until term age and thereafter three times until the twentieth postterm week. All infants required dexamethasone therapy, and additional recordings were made a few hours before and 24 hours, 48 hours, and 7 days after dexamethasone was started. The relationship among movement quality, brain ultrasonographic abnormalities, and long-term outcome was explored. Acute effects of dexamethasone on motor activity were examined. RESULTS: After dexamethasone therapy was started, a significant transient reduction of the quantity of most spontaneous movements (p < 0.05) and a reduction of speed and amplitude of GMs was found (p < 0.05). A significant relationship was found between the severity of brain ultrasonographic abnormalities and the extent to which developmental trajectories of GMs were abnormal (p < 0.001). The development of cerebral palsy was related to the presence of cramped-synchronized movements near term (p < 0.02) and to the absence of fidgety movements at the age of 3 months after term (p < 0.05). CONCLUSION: In preterm infants with severe chronic lung disease and brain lesions, dexamethasone treatment leads to an acute reduction in motility and changes in the speed and amplitude of GMs. Until more is known about long-term neurologic sequelae, a cautious use of systemic dexamethasone therapy in preterm infants is recommended.