Loss of temporal structure of tropical soundscapes with intensifying land use in Borneo.

Conservation and sustainable management efforts in tropical forests often lack reliable, effective, and easily-communicated ways to measure the biodiversity status of a protected or managed landscape. The sounds that many tropical species make can be recorded by pre-programmed devices and analysed to yield measures of biodiversity. Interpreting the resulting soundscapes has developed along two paths: analysing the whole soundscape using acoustic indices, used as a proxy of biodiversity, or focusing on individual species that can be either manually or automatically recognized from the soundscape. Here we develop an intermediate approach to divide the soundscape into frequency categories belonging to broad taxonomic groups of vocalizing animals. While the method was unable to distinguish between amphibian and mammal communities, it was successful in assigning parts of the soundscape as likely produced by birds and insects. Applying the approach in Borneo revealed that, with increasing land use intensity, i) the spectral saturation of the soundscape, a proxy of species richness, loses dawn and dusk peaks, ii) bird acoustic communities lose recurrent diurnal patterns, becoming less synchronized across sites, and that iii) insect Soundscape Saturation increases at night. If soundscapes are partitioned similarly in different regions, our method could be used to bridge soundscape-level and individual-species level analyses. Regaining dawn and dusk peaks, the synchrony of bird acoustic communities, and losing nocturnal dominance of insect could be used as a set of simple indicators of tropical forest retaining high levels of biodiversity.

The reporting of mental disorders research in British media.

BACKGROUND: While the media may significantly influence public attitudes and government policies affecting the research agenda, how mental health research is reported in the media has been virtually unstudied. The aim of this study was to examine stories concerning mental health research published on the British Broadcasting Corporation (BBC) website between 1999 and 2008 and in New Scientist between 2008 and 2010. METHOD: Stories were retrieved from on-line archives. Story content was coded and assessed against: 'disease burden' of mental disorders; the general corpus of research papers in mental health and the countries from which they originated; the journals in which cited papers were published; and funding sources. RESULTS: A total of 1015 BBC stories reporting mental health research and 133 New Scientist stories were found. The distribution of stories did not reflect 'disease burden'; research on dementia was over-represented, while depression and alcohol were under-represented. There was an emphasis on biological research while stories on psychological interventions were rare. UK research was over-represented. Research funded by government and private non-profit sources was over-represented. Commentators from Alzheimer's Disease charities were prominent. CONCLUSIONS: Consideration of reported stories may suggest approaches to working with the media to improve the public understanding of, and support for, mental health research. The role of commentators may be especially important.

How do the media report cancer research? A study of the UK's BBC website.

This study examined cancer research stories on the BBC web archive (July 1998-June 2006). There were about 260 BBC stories per year, of which about 170 were classed as relevant to reports of cancer research. The stories focused heavily on breast cancer, and over one-third of them mentioned this (compared with a cancer disease burden of 13%); the next most covered sites were lung and prostate cancers, although the former was much less mentioned than its cancer disease burden of almost 20% would have suggested. The focus of the stories was often on new or improved drugs or vaccines (20% of stories), with lifestyle choices (12%), genetic developments (9%), and food and drink (8%) also featuring fairly prominently. The BBC stories cited about 1380 research papers that could be identified as journal articles. About three-quarters of the cited papers were in the field of cancer. The papers of these authors came from over 60 countries, and 40% were from the United Kingdom and 36% from the United States. UK cancer research was heavily overcited, by about 6:1, relative to its presence in world oncology research and US research was cited about in proportion. That of most other countries, especially Japan, Germany, and Austria, was relatively undercited. These cited papers also acknowledged more funding bodies. Most of the BBC stories were put in context by external commentators, of whom the large majority was from the UK's cancer research charities.

Intra-operative gas exchange and post-operative hypoxaemia.

The relation between intra-operative gas exchange and post-operative oxygen saturation was examined using pulse oximetry (SpO2) 30 h after anaesthesia for upper abdominal surgery. The inspired oxygen partial pressure (PIO2) was varied during anaesthesia to produce a plot of PIO2 vs. SpO2. Gas exchange during anaesthesia was inferred from the relation between PIO2 and SpO2 which was described by its lateral and vertical displacement away from the position of a standard oxygen dissociation curve. With patients breathing air, the SpO2 was measured over a 10-min period at 30 h after surgery. The correlation coefficient of the lateral displacement with post-operative SpO2 was 0.7, and that of the vertical displacement with post-operative SpO2 was 0.66. The correlation coefficient of intra-operative SpO2 at PIO2 = 21 kPa with post-operative SpO2 was 0.69. It can be concluded that gas exchange abnormalities during anaesthesia deduced from the displacement of the PIO2 vs. SpO2 curve correlate with SpO2 30 h post-operatively and may help to identify patients at risk of post-operative hypoxaemia.

A model to describe the rate of oxyhaemoglobin desaturation during apnoea.

We have developed a model to describe the rate of oxyhaemoglobin desaturation during apnoea. This model takes into account the non-steady-state kinetics which pertain to this situation. We first derived a mathematical expression for instantaneous oxygen flux rate from the alveolar compartment. We then derived an expression to describe the effect of shunt on this flux. The effect of circulation time on real-time arterial mixed venous oxygen content difference and oxygen flux in the lung was determined graphically. We finally described a manoeuvre to accommodate the effect of the Bohr shift which is related to the increase in FACO2 during apnoea. We present plots of arterial oxyhaemoglobin saturation (SaO2) vs duration of apnoea to illustrate the individual effects of the initial fractional concentration of oxygen in the alveolus (FAO2initial), alveolar volume (VA), shunt fraction (QS/QT), oxygen consumption rate (VO2), total blood volume (QT) and haemoglobin concentration (Hb). The model is illustrated by examples of paediatric, morbidly obese and post-operative scenarios. The postoperative scenario is particularly notable for the effect of a combination of small changes in individual variables leading to a large overall effect on the rate of oxyhaemoglobin desaturation.

Elevated exhaled nitric oxide in patients with hepatopulmonary syndrome.

The hypoxaemia of hepatopulmonary syndrome, seen in severe chronic liver dysfunction, occurs as a result of precapillary pulmonary arterial dilatation and arteriovenous communications. These abnormalities contribute to the mismatch between ventilation and perfusion, and the right to left blood flow shunting. Nitric oxide (NO) is a powerful vasodilator concerned with the regulation of pulmonary vascular tone in man. Using a chemiluminescence analyser, we have measured endogenously produced NO in the exhaled air of three patients with the hepatopulmonary syndrome, six normoxaemic cirrhotic patients and six healthy volunteers. The subjects breathed NO-free air throughout the measurements. The molar rate of production of exhaled NO was raised almost threefold in the patients with hepatopulmonary syndrome compared with normal volunteers and with normoxaemic cirrhotic patients. Hypoxia per se, achieved in the normal volunteers by breathing a hypoxic gas mixture, reduced rather than increased the exhaled NO. One hepatopulmonary syndrome patient received an orthotopic liver transplant and achieved normoxaemia after 3 months. The exhaled NO also returned to normal. Increased pulmonary production of NO could contribute to the development of the hepatopulmonary syndrome.

Causes of oxyhaemoglobin saturation instability in the postoperative period.

Healthy, young patients tend to have stable patterns of oxygen saturation (SaO2) in the perioperative period, but unstable patterns of oxygen saturation data in the postoperative period have been described which are associated with wide fluctuations in the value of SaO2 over short periods of time and with a propensity for severe desaturation. This investigation was designed to study the cause of these unstable, hypoxaemic patterns. SpO2 was measured by pulse oximetry in an "at risk" patient group (n = 20) before and after operation and displayed as sequential distribution diagrams and centile plots. In 16 of these patients SpO2 was determined also at different values of PlO2 (21-50 kPa) before and after operation. Instability of SpO2, assessed over periods of 1 h, was common (n = 18) after operation; it was caused by both acute desaturations and a fluctuating baseline SpO2. The PlO2 vs SpO2 relationship was displaced after operation, with both lateral (rightwards) and downwards displacement. The result was to bring the PlO2 to or near to the steep part of the curve. In patients who displayed an unstable pattern of SpO2 over a short period of time (< 5 min), this was abolished by increasing PlO2. We postulate that the displacement of the PlO2 vs SpO2 curve increases the propensity to desaturation in those patients with impaired control by placing the steep part of the curve near to a PlO2 value of 21 kPa.

Analysis of factors which affect the relationship between inspired oxygen partial pressure and arterial oxygen saturation.

The adoption of pulse oximetry in anaesthesia and intensive care has resulted in oxyhaemoglobin saturation (SaO2) becoming an important and widely used clinical descriptor of gas exchange, although its full potential has not been realized. We have explored the effect of impaired gas exchange on the relationship between PIO2 and SaO2. A curve of oxygen content vs PIO2 for an ideal lung was constructed using the oxygen dissociation curve and allowing for the effect of dissolved oxygen in plasma. A plot of PIO2 vs SaO2 was derived from this content curve. The effect of impaired gas exchange (shunt and V/Q effects) on this relationship was then modelled using for shunt the equation Qs/Qt = (Cc' O2-CaO2)/(Cc' O2-CvO2) and for V/Q, a graphical method using the equation V/Q = k(Cc' O2-CvO2)/ (PIO2-PAO2) and the oxygen content curve to model the effect of a spread of V/Q ratios. A total of nine compartments were used to model the scatter of V/Q, and the size of these compartments were determined by their relative blood supply. Plots of PIO2 vs SaO2 were derived for different values of shunt and V/Q. The PIO2 vs SaO2 curve reflected the shape of the oxygen dissociation curve but lay to the right by PIO2-PAO2. Shunt caused a depression of the plateau of this curve with relatively little lateral movement, whereas a low mean V/Q ratio caused a marked rightwards lateral displacement. Increased IogSD Q caused a flattening of the relationship. The combined effect of shunt and a spread of V/Q ratios caused both lateral and vertical displacements. Thus a series of simple measurements of PIO2 and SaO2 gave information about both shunt and V/Q abnormality.

Liver function tests in the critically ill patient.

The liver has a wide range of functions that may be disturbed in different ways by the many diseases which affect it and, in consequence, there are a large number of tests which look at different aspects of its function. Specific diagnoses are made using a range of clinical, biochemical, histological and radiological methods. Measurement of the plasma concentration of alanine aminotransferase (ALT, SGPT), gamma-glutamyl transpeptidase (gammaGT) and albumin are particularly valuable as these substances are specifically affected by liver disease. Their elevation can reveal increases in the membrane permeability of hepatocytes (ALT), cholestasis and toxic damage (gammaGT), or an impairment of liver protein synthesis and secretion (albumin), respectively. If their activities remain within the normal range the likelihood of significant liver disease is less than 2%. A series of quantitative liver function tests are described which each examine one aspect of hepatic function. Table 1 lists several situations where the assessment of hepatic function is necessary. Liver function tests are classified in Table 2.

Patterns of oxygenation after thoracotomy.

We have studied patterns of oxygen saturation (SpO2) before and after thoracotomy in 20 patients monitored nightly from the preoperative night to the fourth postoperative night. After operation, 10 patients received paravertebral bupivacaine (PVB) infusion and 10 received paravertebral saline (PVS) infusion. Papaveretum was given as required. Before operation the SpO2 profiles formed two groups: stable with SpO2 greater than 94% and stable with a median SpO2 less than 94% (hypoxaemia). During the first night after operation SpO2 profiles formed four groups: stable, not hypoxaemic (2/20); stable, hypoxaemic but improving (8/20); stable and constant hypoxaemia (5/20); unstable, hypoxaemic and deteriorating (5/20). Eleven patients remained hypoxaemic as late as the fourth night after operation. All patients who were hypoxaemic before operation were hypoxaemic after operation. Postoperative hypoxaemia was predicted in only 50% of cases. Papaveretum requirement was reduced in the PVB group, but regional analgesia did not affect the proportion of patients showing each SpO2 profile. Papaveretum caused a decrease in SpO2 in both analgesic groups.

Atrial natriuretic peptide released by rapid ventricular pacing in dogs does not cause a natriuresis.

1. The relationships between the haemodynamic, renal and endocrine changes induced by rapid ventricular pacing were studied in ten chloralose-anaesthetized dogs paced from the right ventricular apex for 60 min at 250 beats/min. 2. Pacing increased mean right atrial and mean pulmonary wedge pressure (P less than 0.05), and decreased cardiac output and mean arterial pressure (P less than 0.05). 3. Coronary sinus atrial natriuretic peptide (ANP) concentrations were approximately fourfold greater than arterial concentrations; both increased markedly during pacing (P less than 0.01). Plasma concentrations of arginine vasopressin and plasma renin activity did not change significantly. 4. Urine flow and free water clearance increased during the latter 30 min of pacing (P less than 0.05). There was no significant change in sodium clearance despite high sustained concentrations of ANP. 5. Without the availability of specific inhibitors of ANP release or action, we are unable to exclude the possibility that ANP may have prevented sodium clearance from otherwise decreasing during rapid ventricular pacing. Nevertheless, the dissociation between elevated ANP concentrations and natriuresis in this study indicates that a rise in ANP concentrations per se is not sufficient to produce a natriuresis.

Oxygen analysers. An evaluation of five fuel cell models.

Five currently available fuel cell oxygen analysers were studied with a view to their use in anaesthesia. The accuracy, response time and safety features of these analysers are discussed. Fuel cell analysers appear to be suitable oxygen monitors for routine anaesthetic use.

Urinary tract anomalies in patients with hypospadias.

Fifty-five patients with hypospadias were reviewed. Intravenous urography was carried out on 80%. The incidence of upper urinary tract anomalies was 22%. This was independent of the severity of the hypospadias. Patients with hypospadias and undescended testis were reviewed as a separate group. The incidence of upper urinary tract anomaly here was 31%. Again, the incidence was not influenced by the severity of the hypospadias. None of the upper urinary tract anomalies required surgical intervention. It is concluded that routine IVU is not indicated in all cases of hypospadias.