Alveolar liquid pressures in newborn and adult rabbit lungs

To study the effects of lung maturation and inflation on alveolar liquid pressures, we isolated lungs from adult and newborn rabbit pups (1-11 days old). We used the micropuncture technique to measure alveolar liquid pressure at several transpulmonary pressures on lung deflation. Alveolar liquid pressure was greater than pleural pressure but less than airway pressure at all transpulmonary pressures. Alveolar liquid pressure decreased further below airway pressure with lung inflation. At high transpulmonary pressure, alveolar liquid pressure was less in newborn than in adult lungs. To study the effects of edema, we measured alveolar liquid pressures in newborn lungs with different wet-to-dry weight ratios. Alveolar liquid pressure increased with progressive edema. In addition, we compared alveolar liquid and perivenular interstitial pressures in perfused newborn lungs and found that they were similar. Thus alveolar liquid pressure can be used to estimate perivenular interstitial pressure. We conclude that the transvascular pressure gradient for fluid flux into the interstitium might increase with lung inflation and decrease with progressive edema. Furthermore, this gradient might be greater in newborn than adult lungs at high inflation pressures.     

Randomised controlled trial of effects of coordinating care for terminally ill cancer patients.

OBJECTIVES--To measure effects on terminally ill cancer patients and their families of coordinating the services available within the NHS and from local authorities and the voluntary sector. DESIGN--Randomised controlled trial. SETTING--Inner London health district. PATIENTS--Cancer patients were routinely notified from 1987 to 1990. 554 patients expected to survive less than one year entered the trial and were randomly allocated to a coordination or a control group. INTERVENTION--All patients received routinely available services. Coordination group patients received the assistance of two nurse coordinators, whose role was to ensure that patients received appropriate and well coordinated services, tailored to their individual needs and circumstances. MAIN OUTCOME MEASURES--Patients and carers were interviewed at home on entry to the trial and at intervals until death. Interviews after bereavement were also conducted. Outcome measures included the presence and severity of physical symptoms, psychiatric morbidity, use of and satisfaction with services, and carers'' problems. Results from the baseline interview, the interview closest to death, and the interview after bereavement were analysed. RESULTS--Few differences between groups were significant. Coordination group patients were less likely to suffer from vomiting, were more likely to report effective treatment for it, and less likely to be concerned about having an itchy skin. Their carers were more likely to report that in the last week of life the patient had had a cough and had had effective treatment for constipation, and they were less likely to rate the patient''s difficulty swallowing as severe or to report effective treatment for anxiety. Coordination group patients were more likely to have seen a chiropodist and their carers were more likely to contact a specialist nurse in a night time emergency. These carers were less likely to feel angry about the death of the patient. CONCLUSIONS--This coordinating service made little difference to patient or family outcomes, perhaps because the service did not have a budget with which it could obtain services or because the professional skills of the nurse-coordinators may have conflicted with the requirements of the coordinating role.     

Lung overexpansion increases pulmonary microvascular protein permeability in young lambs

To study the effects of inflation pressure and tidal volume (VT) on protein permeability in the neonatal pulmonary microcirculation, we measured lung vascular pressures, blood flow, lymph flow (QL), and concentrations of protein in lymph (L) and plasma (P) of 22 chronically catheterized lambs that received mechanical ventilation at various peak inflation pressures (PIP) and VT. Nine lambs were ventilated initially with a PIP of 19 +/- 1 cmH2O and a VT of 10 +/- 1 ml/kg for 2-4 h (base line), after which we overexpanded their lungs with a PIP of 58 +/- 3 cmH2O and a VT of 48 +/- 4 ml/kg for 4-8 h. QL increased from 2.1 +/- 0.4 to 13.9 +/- 5.0 ml/h. L/P did not change, but the ratio of albumin to globulin in lymph relative to the same ratio in plasma decreased, indicating altered protein sieving in the pulmonary microcirculation. Seven other lambs were mechanically ventilated for 2-4 h at a PIP of 34 +/- 1 cmH2O and a VT of 23 +/- 2 ml/kg (base line), after which their chest and abdomen were bound so that PIP increased to 54 +/- 1 cmH2O for 4-6 h without a change in VT. QL decreased on average from 2.8 +/- 0.6 to 1.9 +/- 0.3 ml/h (P = 0.08), and L/P was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)     

Some rumen ciliates have endosymbiotic methanogens

Abstract Most of the small ciliate protozoa, including Dasytricha ruminantium and Entodinium spp. living in the rumen of sheep, were found to have intracellular bacteria. These bacteria were not present in digestive vacuoles. They showed characteristic coenzyme F₄₂₀ autofluorescence and they were detected with a rhodamine-labelled Archaea-specific oligonucleotide probe. The measured volume percent of autofluorescing bacteria (1%) was close to the total volume of intracellular bacteria estimated from TEM stereology. Thus it is likely that all of the bacteria living in the cytoplasm of these ciliates were endosymbiotic methanogens, using H₂ evolved by the host ciliate to form methane. Intracellular methanogens appear to be much more numerous than those attached to the external cell surface of ciliates.     

The dependence of reproductive rate on cell size and temperature in freshwater ciliated protozoa

Summary Reproductive rates have been calculated for ten species of ciliated protozoa in defined conditions. Interspecific double log regressions of generation time vs. cell volume have been computed at each of three temperatures (8.5° C, 15° C, and 20° C) indicating a significant dependence of reproductive rate on cell size. Recorded generation times varied from 6.38 h in Vorticella microstoma at 20° C to 1004 h in Spirostomum teres at 8.5° C. These values correspond to a range in r _m (day)^-1 of 2.607 to 0.017 and (day)^-1 of 13.554 to 1.017. The relationship between these data and similar published data for marine ciliates is examined and the value of such regressions in ecological studies of the protozoa is discussed.     

Ultrastructure of Babesia major vermicules from the tick Haemaphysalis punctata as demonstrated by negative staining.

The ultrastructure of Babesia major vermicules was studied in samples derived from the haemolymph of Haemaphysalis punctata adults and negatively stained with phosphotungstic acid. Most of the organelles observed were typical of those found in apicomplexan parasites. These were the apical complex with the polar ring and the ribs, micronemes and subpellicular microtubules. The number of ribs was 27 or 28. The outer membrane of the pellicle was composed of a large number of fibrils running along the length of the parasite. The inner membrane had large numbers of irregularly scattered holes. A cytoplasmic organelle similar to the granular body described in Theileria annulata ookinetes was seen for the first time in a B. major vermicule.     

Effect of hypoproteinemia on lung fluid balance in awake newborn lambs

To study the influence of plasma protein concentration on fluid balance in the newborn lung, we measured pulmonary arterial and left atrial pressures, lung lymph flow, and concentrations of protein in lymph and plasma of eight lambs, 2-3 wk old, before and after we reduced their plasma protein concentration from 5.8 +/- 0.3 to 3.6 +/- 0.6 g/dl. Each lamb underwent two studies, interrupted by a 3-day period in which we drained protein-rich systemic lymph through a thoracic duct fistula and replaced fluid losses with feedings of a protein-free solution of electrolytes and glucose. Each study consisted of a 2-h control period followed by 4 h of increased lung microvascular pressure produced by inflation of a balloon in the left atrium. Body weight and vascular pressures did not differ significantly during the two studies, but lung lymph flow increased from 2.6 +/- 0.1 ml/h during normoproteinemia to 4.1 +/- 0.1 ml/h during hypoproteinemia. During development of hypoproteinemia, the average difference in protein osmotic pressure between plasma and lymph decreased by 1.6 +/- 2 Torr at normal left atrial pressure and by 4.9 +/- 2.2 Torr at elevated left atrial pressure. When applied to the Starling equation governing microvascular fluid balance, these changes in liquid driving pressure were sufficient to account for the observed increases in lung fluid filtration; reduction of plasma protein concentration did not cause a statistically significant change in calculated filtration coefficient. Protein loss did not influence net protein clearance from the lungs nor did it accentuate the increase in lymph flow associated with left atrial pressure elevation.(ABSTRACT TRUNCATED AT 250 WORDS)     

The fine structure of Culicinomyces clavisporus invading mosquito larvae

Electron microscope observations were made of the Australian and U.S. strains of Culicinomyces clavisporus infecting mosquito larvae. The wall of the conidium is composed of an inner (primary) layer, an outer (secondary) layer, and an exterior coating of a mucopolysaccharide substance believed responsible for conidial adhesion to the host cuticle prior to germination and penetration. In some instances the wall of the conidium is ruptured during germination and new wall layers and mucoid coating form around the germ tube whereas in other specimens the conidial wall layers extend around the germ tube without fracturing. The most common invasion site is through the larval foregut following ingestion of conidia. The apex of the germ tube presses tightly against the surface of the foregut cuticle and the mucilaginous coating is stripped away. There is evidence to suggest that the host epicuticle, which disappears across the zone of contact with the germ tube, is utilized for nutrition of the invading fungus. A collar of cuticle forms around the germ tube apex and a narrow penetrant hyphae extends into the procuticle. It is believed that cuticular penetration is primarily enzymatic assisted by mechanical pressure. The penetrant hypha swells into an oval cell in the hypodermal region and vegetative hypha then invade the hemocoel. The cells of the hypodermis develop signs of degeneration presumably due to the secretion of toxic substances from the invading hyphae. Host reactions, involving melanization of the host tissues, are sometimes evident among the invading penetrant hyphae in the cuticle or in the hypodermal cells in contact with the fungus. Melanized capsules form around some of the hyphae within the hemocoel. These latter reactions do not directly involve host blood cells and are examples of “humoral encapsulation” similar to that described by other authors during invasion of pathogenic organisms into mosquito larvae and chironomid larvae.