Cardiovascular Dynamics in Crocodylus porosus Breathing Air and During Voluntary Aerobic Dives

Pressure records from the heart and outflow vessels of the heart of Crocodylus porosus resolve previously conflicting results, showing that left aortic filling via the foramen of Panizza may occur during both cardiac diastole and systole. Filling of the left aorta during diastole, identified by the asynchrony and comparative shape of pressure events in the left and right aortae, is reconciled more easily with the anatomy, which suggests that the foramen would be occluded by opening of the pocket valves at the base of the right aorta during systole. Filling during systole, indicated when pressure traces in the left and right aortae could be superimposed, was associated with lower systemic pressures, which may occur at the end of a voluntary aerobic dive or can be induced by lowering water temperature or during a long forced dive. To explain this flexibility, we propose that the foramen of Panizza is of variable calibre. The presence of a 'right-left' shunt, in which increased right ventricular pressure leads to blood being diverted from the lungs and exiting the right ventricle via the left aorta, was found to be a frequent though not obligate correlate of voluntary aerobic dives. This contrasts with the previous concept of the shunt as a correlate of diving bradycardia. The magnitude of the shunt is difficult to assess but is likely to be relatively small. This information has allowed some new insights into the functional significance of the complex anatomy of the crocodilian heart and major blood vessels

End-stage renal disease preceded by rapid declines in kidney function: a case series

<p>Abstract</p> <p>Background</p> <p>Few studies have defined alternate pathways by which chronic kidney disease (CKD) patients transition into end-stage renal disease (ESRD).</p> <p>Methods</p> <p>We studied all consecutive patients initiated on maintenance hemodialysis or peritoneal dialysis over several years at two dialysis units in Northern California. Rapid decline in kidney function was considered to have occurred if a patient was documented to have estimated GFR > 30 ml/min/1.73 m²within three months prior to the initiation of chronic dialysis.</p> <p>Results</p> <p>We found that 8 out of 105 incident chronic dialysis patients one dialysis unit (7.6%; 95% confidence interval 3.4-14.5%) and 9 out of 71 incident patients at another (12.7%, 95% CI 6.0%-22.7%) suffered rapid decline in kidney function that was the immediate precipitant for the need for permanent renal replacement therapy. All these patients started hemodialysis and all relied on catheters for vascular access. Documentation submitted to United States Renal Data System did not fully reflect the health status of these patients during their "pre-ESRD" period.</p> <p>Conclusions</p> <p>A sizeable minority of ESRD cases are preceded by rapid declines in kidney function. The importance of these periods of rapid decline may have been under-appreciated in prior studies of the natural history of CKD and ESRD.</p

Insights from extreme coral reefs in a changing world

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Coral reefs are one of the most biodiverse and economically important ecosystems in the world, but they are rapidly degrading due to the effects of global climate change and local anthropogenic stressors. Reef scientists are increasingly studying coral reefs that occur in marginal and extreme environments to understand how organisms respond to, and cope with, environmental stress, and to gain insight into how reef organisms may acclimate or adapt to future environmental change. To date, there have been more than 860 publications describing the biology and/or abiotic conditions of marginal and extreme reef environments, most of which were published within the past decade. These include systems characterized by unusually high, low, and/or variable temperatures (intertidal, lagoonal, high-latitude areas, and shallow seas), turbid or urban environments, acidified habitats, and mesophotic depth, and focus on reefs geographically spread throughout most of the tropics. The papers in this special issue of Coral Reefs, entitled Coral Reefs in a Changing World: Insights from Extremes, build on the growing body of literature on these unique and important ecosystems, providing a deeper understanding of the patterns and processes governing life in marginal reef systems, and the implications that these insights may have for the future of tropical coral reefs in our rapidly changing world

IgA in the horse: cloning of equine polymeric Ig receptor and J chain and characterization of recombinant forms of equine IgA

As in other mammals, immunoglobulin A (IgA) in the horse has a key role in immune defense. To better dissect equine IgA function, we isolated complementary DNA (cDNA) clones for equine J chain and polymeric Ig receptor (pIgR). When coexpressed with equine IgA, equine J chain promoted efficient IgA polymerization. A truncated version of equine pIgR, equivalent to secretory component, bound with nanomolar affinity to recombinant equine and human dimeric IgA but not with monomeric IgA from either species. Searches of the equine genome localized equine J chain and pIgR to chromosomes 3 and 5, respectively, with J chain and pIgR coding sequence distributed across 4 and 11 exons, respectively. Comparisons of transcriptional regulatory sequences suggest that horse and human pIgR expression is controlled through common regulatory mechanisms that are less conserved in rodents. These studies pave the way for full dissection of equine IgA function and open up possibilities for immune-based treatment of equine diseases

Synthesis and Detection of Oxygen-18 Labeled Phosphate

Phosphorus (P) has only one stable isotope and therefore tracking P dynamics in ecosystems and inferring sources of P loading to water bodies have been difficult. Researchers have recently employed the natural abundance of the ratio of 18O/16O of phosphate to elucidate P dynamics. In addition, phosphate highly enriched in oxygen-18 also has potential to be an effective tool for tracking specific sources of P in the environment, but has so far been used sparingly, possibly due to unavailability of oxygen-18 labeled phosphate (OLP) and uncertainty in synthesis and detection. One objective of this research was to develop a simple procedure to synthesize highly enriched OLP. Synthesized OLP is made up of a collection of species that contain between zero and four oxygen-18 atoms and, as a result, the second objective of this research was to develop a method to detect and quantify each OLP species. OLP was synthesized by reacting either PCl5 or POCl3 with water enriched with 97 atom % oxygen-18 in ambient atmosphere under a fume hood. Unlike previous reports, we observed no loss of oxygen-18 enrichment during synthesis. Electrospray ionization mass spectrometertry (ESI-MS) was used to detect and quantify each species present in OLP. OLP synthesized from POCl3 contained 1.2% P18O16O3, 18.2% P18O216O2, 67.7% P18O316O, and 12.9% P18O4, and OLP synthesized from PCl5 contained 0.7% P16O4, 9.3% P18O316O, and 90.0% P18O4. We found that OLP can be synthesized using a simple procedure in ambient atmosphere without the loss of oxygen-18 enrichment and ESI-MS is an effective tool to detect and quantify OLP that sheds light on the dynamics of synthesis in ways that standard detection methods cannot

Form factor π0→γ∗+γ∗\pi^0\to \gamma^* +\gamma^* at different photon virtualities

The $\pi^0 \gamma\gamma$ vertex for virtual photons of squared masses $q_1^2$ and $q_2^2$ plays a vital r\^ole in several physical processes; for example for $q_1^2<0$, $q_2^2<0$, in the two-photon physics reaction $e^+ e^-\to e^+ e^- \pi^0$, and for $q_1^2>0$, $q_2^2>0$, in the annihilation process $e^+ e^-\to \pi^0 l^+ l^-$. It is also of interest because of its link to the axial anomaly. We suggest a new approach to this problem. We have obtained a closed analytic expression for the vertex in the limit in which at least one of $|q_1^2|$ and $|q_2^2|$ is large for arbitrary fixed values of the ratio $q_1^2/q_2^2$. We compare our results with those obtained previously by Brodsky and Lepage. It should be straightforward to test our predictions experimentally.Comment: harvmac tex, 30 pages, 11 figures; references are correcte

Tuberculous meningitis in Denmark: a review of 50 cases

<p>Abstract</p> <p>Background</p> <p>Tuberculous meningitis is the most severe manifestation of extrapulmonary tuberculosis with a high mortality rate and a high rate of sequelae among survivors. The aim of this study is to assess the current epidemiology, clinical features, diagnostic procedures, treatment and outcome in patients with tuberculous meningitis in Denmark, a country with a low tuberculosis incidence.</p> <p>Methods</p> <p>A nationwide retrospective study was conducted, comprising all patients notified with tuberculous meningitis (TBM) in Denmark from 2000-2008. Medical records were reviewed using a standardised protocol.</p> <p>Results</p> <p>Fifty patients, including 12 paediatric patients, were identified. 78% of the patients were immigrants from countries of high tuberculosis endemicity. 64% of all patients had a pre-existing immunosuppressive condition; 10% were HIV positive, 48% were HIV seronegative and 42% had an unknown HIV status. Median symptom duration before admission was 14 days in the Danish patient population and 20 days in the immigrant group. Biochemical analysis of cerebrospinal fluid (CSF) samples revealed pleocytosis in 90% with lymphocyte predominance in 66%. Protein levels were elevated in 86%. The most common findings on neuro-radiological imaging were basal meningeal enhancement, tuberculomas and hydrocephalus. Lumbar puncture was performed on 42 patients; 31 of these specimens (74%) had a positive CSF culture for mycobacteria and 9.5% were smear positive for acid-fast bacilli. The overall mortality rate was 19% and 48% of the remaining patients had neurological sequelae of varying degree.</p> <p>Conclusion</p> <p>TBM is a rare but severe manifestation of extrapulmonary TB in Denmark. The clinician must be prepared to treat empirically if the suspicion of TBM has arisen to improve treatment outcome.</p

Association of physical function with predialysis blood pressure in patients on hemodialysis

BACKGROUND: New information from various clinical settings suggests that tight blood pressure control may not reduce mortality and may be associated with more side effects. METHODS: We performed cross-sectional multivariable ordered logistic regression to examine the association between predialysis blood pressure and the short physical performance battery (SPPB) in a cohort of 749 prevalent hemodialysis patients in the San Francisco and Atlanta areas recruited from July 2009 to August 2011 to study the relationship between systolic blood pressure and objective measures of physical function. Mean blood pressure for three hemodialysis sessions was analyzed in the following categories: <110 mmHg, 110-129 mmHg (reference), 130-159 mmHg, and ≥160 mmHg. SPPB includes three components: timed repeated chair stands, timed 15-ft walk, and balance tests. SPPB was categorized into ordinal groups (≤6, 7-9, 10-12) based on prior literature. RESULTS: Patients with blood pressure 130-159 mmHg had lower odds (OR 0.57, 95% CI 0.35-0.93) of scoring in a lower SPPB category than those whose blood pressure was between 110 and 129 mmHg, while those with blood pressure ≥160 mmHg had 0.56 times odds (95% CI 0.33-0.94) of scoring in a lower category when compared with blood pressure 110-129 mmHg. When individual components were examined, blood pressure was significantly associated with chair stand (130-159 mmHg: OR 0.59, 95% CI 0.38-0.92) and gait speed (≥160 mmHg: OR 0.59, 95% CI 0.35-0.98). Blood pressure ≥160 mmHg was not associated with substantially higher SPPB score compared with 130-159 mmHg. CONCLUSIONS: Patients with systolic blood pressure at or above 130 mmHg had better physical performance than patients with lower blood pressure in the normotensive range. The risk-benefit tradeoff of aggressive blood pressure control, particularly in low-functioning patients, should be reexamined

Association of Frailty based on self-reported physical function with directly measured kidney function and mortality

BACKGROUND: Use of serum creatinine to estimate GFR may lead to underestimation of the association between self-reported frailty and kidney function. Our objectives were to evaluate the association of measured GFR (mGFR) with self-reported frailty among patients with CKD and to determine whether self-reported frailty was associated with death after adjusting for mGFR. METHODS: Participants in the Modification of Diet in Renal Disease study (1989–1993) had GFR measured using iothalamate clearance (mGFR), and GFR was estimated based on the CKD-EPI creatinine (eGFRcr) and cystatin C (eGFRcys) equations. We defined self-reported frailty as three or more of: exhaustion, poor physical function, low physical activity, and low body weight. Death was ascertained through 2007 using the National Death Index and the United States Renal Data System. RESULTS: Eight hundred twelve MDRD participants (97 %) had complete data on self-reported frailty (16 % prevalence, N = 130) and mGFR (mean (SD) 33.1 ± 11.7 ml/min/1.73 m(2)). Higher GFR was associated with lower odds of self-reported frailty based on mGFR, (OR 0.71, 95 % CI 0.60–0.86 per 10 ml/min/1.73 m(2)), eGFRcr (OR 0.80, 95 % CI 0.67–0.94 per 10 ml/min/1.73 m(2)), and eGFRcys (OR 0.75, 95 % CI 0.62–0.90 per 10 ml/min/1.73 m(2)). Median follow-up was 17 (IQR 11–18) years, with 371 deaths. Self-reported frailty was associated with a higher risk of death (HR 1.71, 95 % CI 1.26–2.30), which was attenuated to a similar degree when mGFR (HR 1.48, 95 % CI 1.08–2.00), eGFRcr (HR 1.57, 95 % CI 1.15–2.10), or eGFRcys (HR 1.51, 95 % CI 1.10–2.10) was included as an indicator of kidney function. CONCLUSIONS: We found an inverse association between kidney function and self-reported frailty that was similar for mGFR, eGFR and eGFRcys. In this relatively healthy cohort of clinical trial participants with CKD, using serum creatinine to estimate GFR did not substantially alter the association of GFR with self-reported frailty or of self-reported frailty with death