Cubic aluminum silicides RE8Ru12Al49Si9(Al(x)Si12-x) (RE = Pr, Sm) from liquid aluminum. Empty (Si,Al)12 cuboctahedral clusters and assignment of the Al/Si distribution with neutron diffraction

Two new quaternary aluminum silicides, RE8Ru12Al49Si9(Al(x)Si12-x) (x approximately 4; RE = Pr, Sm), have been synthesized from Sm (or Sm2O3), Pr, Ru, and Si in molten aluminum between 800 and 1000 degrees C in sealed fused silica tubes. Both compounds form black shiny crystals that are stable in air and NaOH. The Nd analog is also stable. The compounds crystallize in a new structural type. The structure, determined by single-crystal X-ray diffraction, is cubic, space group Pm3m with Z = 1, and has lattice parameters of a = 11.510(1) A for Sm8Ru12Al49Si9(Al(x)Si12-x) and a = 11.553(2) A for Pr8Ru12Al49Si9(Al(x)Si12-x) (x approximately 4). The structure consists of octahedral units of AlSi6, at the cell center, Si2Ru4Al8 clusters, at each face center, SiAl8 cubes, at the middle of the cell edges, and unique (Al,Si)12 cuboctohedral clusters, at the cell corners. These different structural units are connected to each other either by shared atoms, Al-Al bonds, or Al-Ru bonds. The rare earth metal atoms fill the space between various structural units. The Al/Si distribution was verified by single-crystal neutron diffraction studies conducted on Pr8Ru12Al49Si9(Al(x)Si12-x). Sm8Ru12Al49Si9(Al(x)Si12-x) and Pr8Ru12Al49Si9(Al(x)Si12-x) show ferromagnetic ordering at Tc approximately 10 and approximately 20 K, respectively. A charge of 3+ can be assigned to the rare earth atoms while the Ru atoms are diamagnetic.

Performance of transcutaneous PCO2 and pulse oximetry monitors in newborns and infants after cardiac surgery

We examined the effect of core and skin temperature on the accuracy of two pulse oximeters (Nellcor Symphony and Hewlett Packard saturation module, M1020A) and a transcutaneous PCO2 monitor (Fastrac Transcutaneous monitor) immediately after cardiac surgery in a group of newborns and infants. Seventy-nine sets of data were collected from 46 patients. Core temperatures ranged from 35.3 degrees C to 39.4 degrees C, skin temperatures ranged from 27.0 degrees C to 37.4 degrees C and core-skin temperature gradients ranged from 0.1 degree C to 10.1 degrees C. Data analysis consisted of comparing the difference between transcutaneous PCO2 and arterial PCO2 and the differences between oxygen haemoglobin saturation measured by both pulse oximeters and oxygen haemoglobin saturation measured by co-oximeter to core temperature, skin temperature and core-skin temperature gradients. The mean differences +/- standard deviations and limits of agreement for transcutaneous PCO2 and oxygen haemoglobin saturation measured by the Hewlett Packard and Nellcor pulse oximeters were 0.95 +/- 4.10 mmHg (-7.09 mmHg to 8.99 mmHg), -1.07 +/- 1.84% (-4.68% to 2.54%) and -1.23 +/- 2.23% (-5.60% to 3.14%) respectively. Analysis of correlation coefficients showed that the accuracy of the transcutaneous PCO2 monitor and the pulse oximeters were not affected by core temperature, skin temperature or core-skin temperature gradient in the ranges encountered. We therefore conclude that these devices are acceptably accurate and suitable for use in infants when core and skin temperatures and core-skin temperature gradient are in the range normally found after cardiac surgery.

Measurement of functional residual capacity in rabbits and children using an ultrasonic flow meter

A sulfur hexafluoride (SF(6)) washin/washout technique was developed using an ultrasonic flowmeter to measure functional residual capacity (FRC) during mechanical ventilation. The ultrasonic flowmeter measures simultaneously flow and molar mass of the mainstream gas. Ventilation distribution was studied using moment ratios analysis (alveolar-based mean dilution number). Accuracy and precision of the measurement technique were tested in a mechanical lung model, and the method's sensitivity to changes of FRC was assessed in seven ventilated rabbits and six children. In the mechanical lung model with a volume range from 10 to 60 mL, the mean error of FRC measurement was 0.096 +/- 0.9 mL (range, 0-2 mL). In seven rabbits (mean body weight, 3.6 kg), measurements of FRC and alveolar-based mean dilution number were made at positive end-expiratory pressures (PEEP) of 0, 3, and 6 cm H(2)O. The mean coefficient of variation of 66 FRC-measurements was 5.5% (range, 0-15.3%). As the applied PEEP increased, mean FRC per kilogram body weight increased from 13.3 +/- 3.4 mL/kg (PEEP of 0 cm H(2)O) to 16.7 +/- 3.6 mL/kg (PEEP of 3 cm H(2)O) and to 20.8 +/- 4.3 mL/kg (PEEP of 6 cm H(2)O). Alveolar-based mean dilution number decreased accordingly from 1.94 +/- 0.42 (PEEP = 0; mean +/- SD), to 1.91 +/- 0.45 (PEEP = 3) and to 1.59 +/- 0.35 (PEEP = 6). In the six children, as applied PEEP increased, mean FRC per kilogram increased from 21.1 +/- 4.51 mL/kg (PEEP = 0), to 22.4 +/- 1.8 mL/kg (PEEP = 5) and 27.2 +/- 3.4 mL/kg (PEEP = 10). FRC measurement using the ultrasonic flowmeter is accurate and simple to use in ventilated and spontaneously breathing children.

A randomized trial of very early decompressive craniectomy in children with traumatic brain injury and sustained intracranial hypertension

OBJECT

The object of our study was to determine, in children with traumatic brain injury and sustained intracranial hypertension, whether very early decompressive craniectomy improves control of intracranial hypertension and longterm function and quality of life.

METHODS

All children were managed from admission onward according to a standardized protocol for head injury management. Children with raised intracranial pressure (ICP) were randomized to standardized management alone or standardized management plus cerebral decompression. A decompressive bitemporal craniectomy was performed at a median of 19.2 h (range 7.3-29.3 h) from the time of injury. ICP was recorded hourly via an intraventricular catheter. Compared with the ICP before randomization, the mean ICP was 3.69 mmHg lower in the 48 h after randomization in the control group, and 8.98 mmHg lower in the 48 hours after craniectomy in the decompression group (P=0.057). Outcome was assessed 6 months after injury using a modification of the Glasgow Outcome Score (GOS) and the Health State Utility Index (Mark 1). Two (14%) of the 14 children in the control group were normal or had a mild disability after 6 months, compared with 7 (54%) of the 13 children in the decompression group. Our conclusion was that when children with traumatic brain injury and sustained intracranial hypertension are treated with a combination of very early decompressive craniectomy and conventional medical management, it is more likely that ICP will be reduced, fewer episodes of intracranial hypertension will occur, and functional outcome and quality of life may be better than in children treated with medical management alone (P=0.046; owing to multiple significance testing P <0.0221 is required for statistical significance). This pilot study suggests that very early decompressive craniectomy may be indicated in the treatment of traumatic brain injury.

Arthrolysis of the shoulder for ruptures of the rotator cuff

Complete repair of tears of the rotator cuff may be difficult, but with superior arthrolysis by the Apoil-Dautry technique the lesion in the cuff is not treated. We report 17 patients who had this procedure for large cuff defects. The outcome is directly related to the duration of symptoms, and we only had good results in a few patients, although intensive physiotherapy improves function. A wide debridement is needed, followed by intensive physiotherapy for the deltoid and shoulder stabilising muscles. We recommended that this technique should be used in elderly patients who will put less demand on their shoulders.

Tracheal gas insufflation reduces requirements for mechanical ventilation in a rabbit model of respiratory distress syndrome

Tracheal gas insufflation is known to lower PaCO2 in larger animal models of respiratory distress syndrome, but its ability to reduce the ventilator pressures and tidal volume needed to achieve an acceptable PaCO2 has not been examined in small animals using modes of ventilation employed in neonatal intensive care. In this study, the effect of insufflating humidified gas into the lower trachea was examined in a saline lung lavage model of respiratory distress syndrome in rabbits, while the peak airway pressure during conventional pressure-limited ventilation was adjusted to keep the PaCO2 approximately constant. Tracheal gas insufflation significantly reduced the peak airway pressure required and reduced the delivered tidal volume but did not affect the AaDO2. The effects were more marked at a ventilator rate of 30 breaths per minute than at 60 bpm and more during continuous insufflation than when gas was insufflated only during expiration. These results suggest that tracheal gas insufflation may reduce the risk of ventilation-induced lung disease in the newborn.

Anthraquinones in Rheum palmatum and Rumex dentatus (Polygonaceae), and phorbol esters in Jatropha curcas (Euphorbiaceae) with molluscicidal activity against the schistosome vector snails Oncomelania, Biomphalaria and Bulinus

Hot water extracts of Rheum plamatum and Rheum dentatus (from China) showed molluscicidal activity against the snails Oncomelania hupensis, Biomphalaria glabrata and Bulinus globosus, which are vectors of Schistosoma japonicum, S. mansoni and S. haematobium, respectively. Activity was correlated with antraquinones which were identified by HPLC: rhein and chrysophanol-anthron were most active (> 50% dead snails after 2 days in a 0.03% solution). Molluscicidal activity was intermediate with Rheum-emodin and physcion and was not detectable with cinnamic acid or Aloe-emodin. The snail O. hupensis tended to be more sensitive for several compounds than B. glabrata. Extracts of Jatropha curcas seeds (from Mali) showed molluscicidal activity against both B. glabrata and O. hupensis, the latter being the more sensitive snail. The activity was associated with phorbol esters extracted from Jatropha oil. Of the pure phorbol esters tested, 4 beta-phorbol-13-decanoate killed both snail species at a concentration of 0.001% (10 p.p.m). As Jatropha is locally grown in Mali for other purposes, it might potentially be exploited for schistosomiasis control.

Effects of nitric oxide synthase inhibition combined with nitric oxide inhalation in a porcine model of endotoxin shock

1. The present investigation compares the effects of intravenous infusion of the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) with that of an inhalation with NO gas in a porcine model of endotoxin (lipopolysaccharide, LPS) shock. In addition, the effects of the combination of these two treatments were also investigated. 2. Male pigs were anaesthetized and instrumented for the measurement of haemodynamic parameters. Blood samples were withdrawn at different time intervals for determination of blood gases, pH, and plasma levels of nitrite/nitrate and tumour necrosis factor. 3. Endotoxin infusion (15 micrograms kg-1 h-1 for 3 h) caused a progressive fall in mean arterial blood pressure (MABP) and cardiac output (CO) and a biphasic increase in mean pulmonary arterial pressure (MPAP) and pulmonary vascular resistance (PVR). A continuous infusion of L-NMMA (0.1 mg kg-1 min-1) significantly attenuated the fall in MABP, but did not affect MPAP, CO and PVR. NO-inhalation (50 p.p.m.) did not affect MABP, but significantly blunted the biphasic increase in MPAP and PVR and significantly delayed the fall in CO. The combination of L-NMMA infusion (0.1 mg kg-1 min-1) with NO-inhalation (50 p.p.m.) completely prevented the fall in MABP, significantly improved CO, and attenuated the biphasic increase in MPAP and PVR. 4. Endotoxin also caused a decline in PaO2 and a rise of PaCO2. Infusion of L-NMMA neither affected the fall in PaO2 nor the increase in PaCO2. In contrast, inhalation with NO gas alone as well as the combined administration of L-NMMA infusion and NO-inhalation completely prevented the fall in Pao2 and significantly protected against the increase in Paco2.5. Infusion of endotoxin for 180 min resulted in a mortality of 58%, which was not affected by L-NMMA (63%). In contrast, treatment of LPS-animals with either NO-inhalation alone or NO inhalation plus L-NMMA completely prevented mortality.6. This investigation demonstrates that treatment with NO-inhalation, in order to prevent the dramatic increase in MPAP, PVR and the alterations in peripheral blood gases combined with systemic L-NMMAto improve systemic MABP and thus organ perfusion, may be a new therapeutic regimen in the treatment of septic shock.

GP-hospice interaction. When should patients be referred?

Patients should be referred early to hospice services. Regular communication between patient, family, treating general practitioner and hospice improves 'control' and life quality for patients. Pain control is a major problem and specialist care is frequently required. Hospice units can correct non terminal conditions, returning patients to the community in better health.

Effects of the renin inhibitor N-[N-(3-(4-amino-1-piperidinyl-carbonyl)-2(R)-benzylpropionyl)-L- histid inyl] -(2S,3R,4S)-1-cyclohexyl-3,4-dihydroxy-6(2-pyridyl)-hexane-2-amide acetate in anesthetized rhesus monkeys

The renin inhibitory effect of the non-peptide renin inhibitor S 2864 (N-[N-(3-(4-Amino-1-piperidinyl-carbonyl)-2(R)-benzylpropionyl)-L- histidinyl]-(2S,3R,4S)-1-cyclohexyl-3,4-dihydroxy-6(2-pyridyl)-hexane-2- amide acetate, CAS 135683-92-0) was characterized in vitro and in vivo in primates. In vitro, S 2864 inhibited the activity of purified human plasma renin with an IC50 of 3.8 x 10(-10) mol/l and did not affect related human aspartyl proteases like human cathepsin E, cathepsin D or pepsin. In vivo, in anesthetized sodium depleted rhesus monkeys S 2864 decreased mean arterial blood pressure after intraduodenal (i.d.) administration of 2 mg/kg significantly by 27% from 94 +/- 8 to 62 +/- 6 mmHg for 90 min. Heart rate was not changed. Cumulative intravenous (i.v.) administration of S 2864 or remikiren in doses of 1, 10 and 30 micrograms/kg significantly decreased systemic blood pressure, dP/dtmax and cardiac output while heart rate was not changed. Plasma angiotensin II (ANG II) levels as well as renin activity were dose dependently reduced after 10, 30 and 60 min. It is concluded that S 2864 is an effective specific inhibitor of human renin eliciting marked blood pressure lowering activities in primates.

Antiischemic effects of pirsidomine, a new nitric oxide donor

The antiischemic effect of pirsidomine (CAS 936 (3-(cis-2,6-dimethylpiperidino)-N-(4-methoxybenzoyl))-sydnon imine), a new nitric oxide donor, was investigated in a model of myocardial infarction in the dog. Dogs were anaesthetised, thoracotomized, and the left descending coronary artery was occluded for 6 h. Pirsidomine was given intraduodenally (i.d.) at the dose of 1.0 mg/kg to 11 dogs 30 min prior to coronary occlusion. Eleven dogs received the solvent i.d. and served as controls. Pirsidomine administration completely prevented the increase in left ventricular end-diastolic pressure and pulmonary artery pressure induced by the coronary occlusion and resulted in a marked decrease in systolic and diastolic blood pressure, cardiac output, left ventricular contractility, left ventricular work and left ventricular oxygen consumption. Additionally, pirsidomine completely prevented the occlusion-induced increase in flow in the non-occluded circumflex coronary artery. Regional blood flow measurements (with radioactive microspheres) revealed that pirsidomine induced a significant reduction in blood flow in the non-ischemic areas (both epi- and endocardial) but in the course of the ischemia, significantly increased flow in the ischemic epicardial areas. Infarct-size (triphenyltetrazolium chloride technique) in control dogs was 45% of the area at risk, but only 26% (P < 0.05) in pirsidomine-treated dogs. Thus, pirsidomine had a marked antiischemic effect in this model. This was probably due to the hemodynamic unloading of the heart as well as to redistribution of blood from the non-ischemic to the ischemic areas of the myocardium.

N-Acetylserotonin prevents the hypotension induced by bacterial lipopolysaccharides in the rat

Nitric oxide is produced by the NO synthase, which catalyses the conversion of arginine to citrulline and NO using tetrahydrobiopterin as an essential cofactor. N-Acetylserotonin, an inhibitor of the tetrahydrobiopterin biosynthesis, given 30 min before bacterial lipopolysaccharide to anesthetized rats, inhibited both the decrease in blood pressure and the increase in nitrite plasma levels induced by lipopolysaccharide. Thus, during endotoxemia the availability of tetrahydrobiopterin appears to be essential for the activity of NO synthase.

Renin inhibitors containing a pyridyl amino diol derived C-terminus

Based on the concept of transition-state analogs, a series of nonpeptide renin inhibitors with the new (2S,3R,4S)-2-amino-1-cyclohexyl-3,4-dihydroxy-6-(2-pyridyl)hexane moiety at the C-terminal functionality were synthesized and evaluated for inhibition of renin both in vitro and in vivo. All compounds exhibited potencies in the nanomolar or even subnanomolar range when tested versus human renin in vitro. Selected inhibitors were evaluated in anesthetized, sodium-depleted rhesus monkeys and produced a marked reduction in mean arterial blood pressure (MAP) upon intraduodenal administration of a dose of 2 mg/kg. Compound 38 (S 2864) containing an amino piperidyl succinic acid derived N-terminal is the most promising member in this series. 38 inhibited human renin with an IC50 of 0.38 nM, did not affect other human aspartic proteinases, and decreased mean arterial blood pressure significantly by 27% with a duration of action of 90 min after administration of 2 mg/kg id in anesthetized, sodium-depleted rhesus monkeys.

Renin inhibitory pentols showing improved enteral bioavailability

Incorporation of a C-terminal pentahydroxy functionality led to potent, low molecular weight hydrophilic renin inhibitors lacking the P1' side chain. As these compounds are easy to synthesize and have sufficient water solubility, they were chosen for further study. Compound 33 was transported across rabbit intestinal brush border membrane vesicles and yielded a hypotensive effect in sodium-depleted rhesus monkeys which lasted for 90 min when dosed at 2 mg/kg id.

Emergency transport of critically ill children: stabilisation before departure

OBJECTIVE

To provide up-to-date practical information, relevant to Australian conditions and practice, on stabilising the condition of critically ill children who need transport to a paediatric hospital.

DATA SOURCES AND SELECTION

Information on current resuscitation practice was sought from relevant original articles and reviews in the recent medical literature, from textbooks and monographs published in the last 10 years.

DATA SYNTHESIS AND CONCLUSIONS

A recent study found that 47% of 100 children who needed emergency interhospital transfer experienced problems which should have been preventable by greater availability to referring doctors of information on pretransport stabilisation of critically ill children. Hypoventilation, hypoxaemia and hypotension are commonly found in critically ill children before transport, as are difficulties with endotracheal tube care, sedation and analgesia. Mild physiological disturbances are likely to become severe and life-threatening during transfer unless they are corrected before departure. Early discussion of the child's problems and the transfer plan with senior staff at the nearest paediatric intensive care unit may be helpful in planning the pre-transfer resuscitation.