Maintain Fluid Balance Research Articles

Ultra-small neonatal dialysis circuits do not maintain safe fluid balance

Nishimi and colleagues have designed a renal replacement device for tiny babies in which the extracorporeal circuit volume (ECV) is Bultra-small^ at only 3.2 ml, by just using one operating syringe [1]. They note that their current system does not maintain fluid balance Baccurately , but that they Bare working on^ this Bserious weakness^. Unfortunately, they will not be able to regulate the ultrafiltration rate without adding extra components to the circuit. This is because water moves across a dialyser according to the transmembrane pressure (TMP), and this cannot be regulated while the filter is exposed to the pressures in the blood access or return lines. In their earlier (manual) circuit design, the proximal operating syringe created a positive TMP by pushing blood through the dialysis filter, and generated a mean daily ultrafiltrate of 40 ml (abstracted from their Figure 5a). Their new (automated) circuit uses a distal syringe to draw blood through the filter, which generates a negative TMP that drew amean of 112 ml/day of water into the blood (range 16 to 260; P=0.02, one-sample t test; Figure 5b). Large, unpredictable fluid shifts like this could harmfully overload small infants, most of whom are fluid-replete when they commence renal replacement therapy. Two ways of isolating the dialysis filter pressure from the rest of the blood circuit include using a valve and second syringe, as we have done in the Nidus [2], and generating a TMP by using a computer-controlled intermittent isolation valve distally. The latter requires a pressure transducer in the circuit, and a method of continuously measuring the ultrafiltration rate to provide feed-back to the computer algorithm. So far, devices that use this approach cannot produce precise fluid control; the Prismaflex is inaccurate by ±30 ml/h [3], and the CARPEDIEM by ±7.5 % of the dialysate fluid flow, despite weighing its ultrafiltrate to the nearest gram [4]. All methods of controlling fluid balance inevitably increase the ECV, which makes safe Bultra-small^ renal replacement devices difficult to build.

PENGARUH STIMULASI PEMBERIAN TABLET HISAP VITAMIN CTERHADAP PENINGKATAN SEKRESI SALIVA PADA PASIEN GAGALGINJAL KRONIK YANGMENJALANI TERAPI HEMODIALISADI RS PKU MUHAMMADIYAH GOMBONG

Chronic renal failure is a progressive deterioration in kidney function and irreversible, in where the body is unable to maintain fluid balance and electrolyte metabolism. Inpractice, patients must limit fluid diet to prevent complications. However, such action may affect some aspect of the human body, that is dry mouth or xerostomiadue to decrease saliva production. To reduce patient complaint, actions which can be done is to stimulate gland salivary with chemical stimulation using lozenges sour taste vitamin C. The aim of this study is to the determine the stimulation effect of the vitamin C lozenges provision to increase salivary secretion in patients with chronic renal failure undergoing hemodialysis therapy in PKU Muhammadiyah Gombong Hospital.This study used a quasi experimental design with pretest — postest design. Samples amounts 42 respondents, consisting of 21 respondents control and 21 respondents intervention by using Purposive Sampling technique. Data analysis technique using Paired t Test to determine whether there were significant differences in salivary secretion in the pretest and postest.Based on a statistical test Paired t Test found a significant increase in the salivary secretion between pretest saliva and postest one intervention group with a value of p=0,003. In conclusion, stimulation of vitamin C lozenges giving has affect to increase saliva secretion in patients with chronic renal failure undergoing hemodialysis therapy in PKU Muhammadiyah Gombong Hospital. Keywords: stimulation, secretion of saliva, chronic renal failure

Milk: An Alternative Beverage for Hydration?

The hydration status of a physically active individual or athlete can influence his/her physical or mental performance. The degree of hypohydration may lead to serious health problems, and consequently to impair athletic performance. The consumption of water or carbohydrate-electrolyte beverages before, during and after exercise is essential to maintain fluid balance and prevent dehydration. Besides these drinks, research findings have pointed using bovine milk as an alternative to sports drinks to optimize hydration levels in athletes and physically active individuals. The nutritional composition of cow’s milk promotes post-exercise rehydration process, due to the natural presence of water and electrolytes such as sodium and potassium. Although most studies have confirmed that bovine milk is a viable alternative for rehydration, recent studies have not reported significant differences between milk and some sports drinks for hydration process. Thus, milk consumption could be used as an alternative beverage for the hydration process.

에너지개발기술에 있어 유체주입에 따른 유발지진 발생 사례분석

Induced seismicity related to four energy development technologies that involve fluid injection or withdrawal: geothermal energy, conventional oil and gas development including enhanced oil recovery (EOR), shale gas recovery, and carbon capture and storage (CCS) is reviewed by literature investigation. The largest induced seismic events reported in the technical literature are associated with projects that did not balance the large volume of fluids injected into, or extracted from the underground reservoir. A statistical observation shows that the net volume of fluid injected and/or extracted may serve as a proxy for changes in subsurface stress conditions and pore pressure, and other factors. Energy technology projects that are designed to maintain a balance between the amount of fluid being injected and the amount of fluid being withdrawn, such as geothermal and most oil and gas development, may produce fewer induced seismic events than technologies that do not maintain fluid balance, such as long-term wastewater disposal wells and CCS projects.

Photoacoustic lymphatic imaging with high spatial-temporal resolution.

Despite its critical function in coordinating the egress of inflammatory and immune cells out of tissues and maintaining fluid balance, the causative role of lymphatic network dysfunction in pathological settings is still understudied. Engineered-animal models and better noninvasive high spatial-temporal resolution imaging techniques in both preclinical and clinical studies will help to improve our understanding of different lymphatic-related pathologic disorders. Our aim was to take advantage of our newly optimized noninvasive wide-field fast-scanning photoacoustic (PA) microcopy system to coordinately image the lymphatic vasculature and its flow dynamics, while maintaining high resolution and detection sensitivity. Here, by combining the optical-resolution PA microscopy with a fast-scanning water-immersible microelectromechanical system scanning mirror, we have imaged the lymph dynamics over a large field-of-view, with high spatial resolution and advanced detection sensitivity. Depending on the application, lymphatic vessels (LV) were spectrally or temporally differentiated from blood vessels. Validation experiments were performed on phantoms and in vivo to identify the LV. Lymphatic flow dynamics in nonpathological and pathological conditions were also visualized. These results indicate that our newly developed PA microscopy is a promising tool for lymphatic-related biological research.

Performance Nutrition Guidelines for International Rugby Sevens Tournaments

Rugby sevens is an abbreviated version of rugby union, played by teams of seven players over 7-min halves. International competitions are usually played in a tournament format. While shorter in duration, the movement demands of rugby sevens per min of match time are greater than rugby union, resulting in an accentuated load on players. This load can be repeated up to six times over a typical 2- or 3-day competition period. The potential cumulative effect of inadequate carbohydrate, protein and/or fluid intake over the course of a tournament is the greatest nutrition-related concern for players. Nutritional strategies before and during competition are suggested to replenish substrate stores, maintain fluid balance and promote recovery between matches. The use of ergogenic aids known to enhance intermittent, high-intensity activity and/or the execution of motor skills may be advantageous to rugby sevens performance and is discussed. This review provides a best-practice model of nutritional support for international rugby sevens competition based on our current understanding of the sport combined with pragmatic guidelines and considerations for the practitioner.

No Evidence of Dehydration with Moderate Daily Coffee Intake: A Counterbalanced Cross-Over Study in a Free-Living Population

It is often suggested that coffee causes dehydration and its consumption should be avoided or significantly reduced to maintain fluid balance. The aim of this study was to directly compare the effects of coffee consumption against water ingestion across a range of validated hydration assessment techniques. In a counterbalanced cross-over design, 50 male coffee drinkers (habitually consuming 3–6 cups per day) participated in two trials, each lasting three consecutive days. In addition to controlled physical activity, food and fluid intake, participants consumed either 4×200 mL of coffee containing 4 mg/kg caffeine (C) or water (W). Total body water (TBW) was calculated pre- and post-trial via ingestion of Deuterium Oxide. Urinary and haematological hydration markers were recorded daily in addition to nude body mass measurement (BM). Plasma was analysed for caffeine to confirm compliance. There were no significant changes in TBW from beginning to end of either trial and no differences between trials (51.5±1.4 vs. 51.4±1.3 kg, for C and W, respectively). No differences were observed between trials across any haematological markers or in 24 h urine volume (2409±660 vs. 2428±669 mL, for C and W, respectively), USG, osmolality or creatinine. Mean urinary Na+ excretion was higher in C than W (p = 0.02). No significant differences in BM were found between conditions, although a small progressive daily fall was observed within both trials (0.4±0.5 kg; p<0.05). Our data show that there were no significant differences across a wide range of haematological and urinary markers of hydration status between trials. These data suggest that coffee, when consumed in moderation by caffeine habituated males provides similar hydrating qualities to water.

Black Tea Magic: Overview of Global Research on Human Health and Therapeutic Potentialities

Tea is the second most frequently consumed cheapest non-alcoholic beverage worldwide, black tea is the most produced type, followed by green and Oolong tea. The venture of this paper is to focus on the latest research efforts regarding the health effects related to consumption of black tea and derive some future research directions towards its therapeutic potentialities. With a view of the above, comprehensive information on the fermentation process, composition, and quality of black tea has been provided. Several major beneficial roles of black tea are antioxidant activity, antiulcer effect, anti-inflammatory effect, antimicrobial properties, anticancer properties, antimutagenic activity along with the attenuating or reducing effects on blood pressure, CHD and cardiovascular disease, atherosclerosis, oxidative damage are important. Moreover, black tea has proven to enhance insulin activity, helps in treating asthma, retard cataract, maintains fluid balance, bone health and dental health, improves mean body mass index and body weight, prevents cellular DNA damage, inhibits HIV, lowers stress hormone levels, etc. The potential effect on human biosynthetic pathways related to oxidative processes as well as that on cognitive performance has also been discussed with citation from various research findings.

Roles of YehZ, a Putative Osmoprotectant Transporter, in Tempering Growth of Salmonella enterica serovar Typhimurium

Salmonella, a main cause of foodborne diseases, encounters a variety of environmental stresses and overcomes the stresses by multiple resistance strategies. One of the general responses to hyperosmotic stress is to import or produce compatible solutes so that cells maintain fluid balance and protect proteins and lipids from denaturation. The ProP and ProU systems are the main transport systems for compatible solutes. The OsmU system, recently identified as a third osmoprotectant transport system, debilitates excessive growth as well by reducing production of trehalose. We studied a fourth putative osmoprotectant transport system, YehZYXW, with high sequence similarity with the OsmU system. A Salmonella strain lacking YehZ, a predicted substrate-binding protein, did not suffer from hyperosmolarity but rather grew more rapidly than the wild type regardless of glycine betaine, an osmoprotectant, suggesting that the YehZYXW system controls bacterial growth irrespective of transporting glycine betaine. However, the growth advantage of ΔyehZ was not attributable to an increase in OtsBA-mediated trehalose production, which is responsible for the outcompetition of the ΔosmU strain. Overexpressed YehZ in trans was capable of deaccelerating bacterial growth vice versa, supporting a role of YehZ in dampening growth. The expression of yehZ was increased in response to nutrient starvation, acidic pH, and the presence of glycine betaine under hyperosmotic stress. Identifying substrates for YehZ will help decipher the role of the YehZYXW system in regulating bacterial growth in response to environmental cues.

FLUID BALANCE IN ELITE SHORT TRACK SPEED SKATERS

The aim of this study was to investigate sweat loss in elite short track speed skaters across 6 different training sessions over a three day period, and sweat sodium loss...

Permeability and contractile responses of collecting lymphatic vessels elicited by atrial and brain natriuretic peptides

Atrial and brain natriuretic peptides (ANP and BNP, respectively) are cardiac hormones released into the bloodstream in response to hypervolaemia or fluid shifts to the central circulation. The actions of both peptides include natriuresis and diuresis, a decrease in systemic blood pressure, and inhibition of the renin-angiotensin-aldosterone system. Further, ANP and BNP elicit increases in blood microvessel permeability sufficient to cause protein and fluid extravasation into the interstitium to reduce the vascular volume. Given the importance of the lymphatic vasculature in maintaining fluid balance, we tested the hypothesis that ANP or BNP (100 nM) would likewise elevate lymphatic permeability (Ps) to serum albumin. Using a microfluorometric technique adapted to in vivo lymphatic vessels, we determined that rat mesenteric collecting lymphatic Ps to rat serum albumin increased by 2.0 ± 0.4-fold (P = 0.01, n = 7) and 2.7 ± 0.8-fold (P = 0.07, n = 7) with ANP and BNP, respectively. In addition to measuring Ps responses, we observed changes in spontaneous contraction amplitude and frequency from the albumin flux tracings in vivo. Notably, ANP abolished spontaneous contraction amplitude (P = 0.005) and frequency (P = 0.006), while BNP augmented both parameters by ∼2-fold (P < 0.01 each). These effects of ANP and BNP on contractile function were examined further by using an in vitro assay. In aggregate, these data support the theory that an increase in collecting lymphatic permeability opposes the absorptive function of the lymphatic capillaries, and aids in the retention of protein and fluid in the interstitial space to counteract volume expansion.

Autoimmune Polyendocrine Syndrome: A Case-Based Review

You are seeing a 14-year-old white male athlete with atopy who complains of a 6-month history of progressive proximal muscle weakness, which significantly impacts his ability to run short distances and swing his baseball bat. His mother states he has presented to multiple emergency departments (ED) for continued weakness and that most diagnosed him with dehydration and educated the family on how to maintain fluid balance. At his last ED visit, a creatine kinase (CK) level was drawn and found to be elevated at 1,247 U/L (normal range 9-185 U/L). A referral to a neurologist was made. The neurologist noted worsening fatigue, dizziness, and a documented 17-pound weight loss at the patient’s initial visit. A possible infectious versus progressive inflammatory myositis was suspected. The neurologist recommended an electromyography (EMG) to evaluate the patient’s proximal muscle weakness. Prior to completion of this EMG, the teen presents to your clinic now complaining of pre-syncopal events. On further review of symptoms, you note the patient has persistent polydipsia, headaches, nausea/vomiting, intermittent abdominal pain, and hyperpigmentation. Family history is negative for myopathies or dystrophies, but positive for hypothyroidism (mother), pineal gland tumor s/p resection (father), and rheumatoid arthritis (maternal grandmother). PHYSICAL EXAMINATION Initial physical examination reveals an afebrile, thin, adolescent male with orthostatic blood pressure changes of 113/59 mm Hg at rest and 89/44 mm Hg while standing; a pulse of 87 beats/ min; and a respiratory rate of 16 breaths/ min. His HEENT exam reveals equally reactive pupils with moist mucous membranes and no thyromegaly. His neurologic exam including cranial nerves, mental status, speech, gait, and coordination is unremarkable; there is no tremor noted. His muscle strength is noted to be 4/5 in the quadriceps bilaterally but 5/5 throughout the rest of his muscle groups. His muscle bulk and tone are mildly decreased. His cardiovascular, pulmonary, and abdominal exams are all benign. He has physiologic pubertal gynecomastia with mild tenderness. His genitourinary examination reveals normal appearing Tanner 3 male genitalia. His skin exam is remarkable for diffuse hyperpigmentation, which extends into his intertriginous areas and most notably the palms and creases of his hands. Flexor surfaces on his arms and diffuse areas on his face show ecAutoimmune Polyendocrine Syndrome: A Case-Based Review

Copeptin, a surrogate marker for arginine vasopressin, is associated with declining glomerular filtration in patients with diabetes mellitus (ZODIAC-33)

Arginine vasopressin (AVP), the hormone important for maintaining fluid balance, has been shown to cause kidney damage in rodent models of diabetes. We investigated the potential role of AVP in the natural course of kidney function decline in diabetes in an epidemiological study. Plasma copeptin, a surrogate for AVP, was measured in baseline samples from patients with type 2 diabetes treated in primary care and included in the Zwolle Outpatient Diabetes project Integrating Available Care (ZODIAC) cohort. Samples from 1,328 patients were available; 349 were analysed separately because they used renin-angiotensin-aldosterone system inhibition (RAASi), which influences albumin/creatinine ratio (ACR) and estimated (e)GFR. In the other 979 patients (46% men, age 68 years [58-75], ACR 1.8 mg/mmol [0.9-5.7], eGFR 67 ± 14 ml min(-1) 1.73 m(-2)) baseline copeptin (5.3 pmol/l [3.2-9.5]) was significantly associated with log e [ACR] and eGFR, even after adjustment for sex, age and risk factors for kidney function decline (standardised [std] β 0.13, p < 0.001, std β -0.20, p < 0.001 respectively). Follow-up data were available for 756 patients (6.5 years [4.1-9.6]). Baseline copeptin was associated with increase in ACR (std β 0.09, p = 0.02), but lost significance after adjustment (std β 0.07, p = 0.08). Copeptin was associated with a decrease in eGFR after adjustment (std β -0.09, p = 0.03). The strength of the association of copeptin with change in eGFR was stronger than that of established risk factors for kidney function decline (e.g. BMI, HbA1c). In patients who used RAASi there was a significant association between baseline copeptin and ACR and eGFR, but not with change in ACR and eGFR. In patients with diabetes not using RAASi a higher baseline copeptin concentration is significantly associated with higher baseline ACR and lower eGFR values and with a decline in eGFR during follow-up. This last association is independent of, and stronger than, most traditional risk factors for kidney function decline.

Comparison of cardiovascular aquaporin-1 changes during water restriction between 25- and 50-day-old rats

Aquaporin-1 (AQP1) is the predominant water channel in the heart, linked to cardiovascular homeostasis. Our aim was to study cardiovascular AQP1 distribution and protein levels during osmotic stress and subsequent hydration during postnatal growth. Rats aged 25 and 50 days were divided in: 3d-WR: water restriction 3 days; 3d-WAL: water ad libitum 3 days; 6d-WR+ORS: water restriction 3 days + oral rehydration solution (ORS) 3 days; and 6d-WAL: water ad libitum 6 days. AQP1 was evaluated by immunohistochemistry and western blot in left ventricle, right atrium and thoracic aorta. Water restriction induced a hypohydration state in both age groups (40 and 25 % loss of body weight in 25- and 50-day-old rats, respectively), reversible with ORS therapy. Cardiac AQP1 was localized in the endocardium and endothelium in both age groups, being evident in cardiomyocytes membrane only in 50-day-old 3d-WR group, which presented increased protein levels of AQP1; no changes were observed in the ventricle of pups. In vascular tissue, AQP1 was present in the smooth muscle of pups; in the oldest group, it was found in the endothelium, increasing after rehydration in smooth muscle. No differences were observed between control groups 3d-WAL and 6d-WAL of both ages. Our findings suggest that cardiovascular AQP1 can be differentially regulated in response to hydration status in vivo, being this response dependent on postnatal growth. The lack of adaptive mechanisms of mature animals in young pups may indicate an important role of this water channel in maintaining fluid balance during hypovolemic state.

Total arch replacement using selective antegrade cerebral perfusion as the neuroprotection strategy.

Optimal neuro-protection strategy in aortic arch surgery is a controversial issue. The present study reported surgical outcomes of total arch replacement using selective antegrade cerebral perfusion (SACP). From January 2002 to December 2012, 438 consecutive patients (mean age 69.1±13.4 years) underwent total arch replacement using SACP through a median sternotomy. Acute aortic dissection was present in 86 patients (18.3; 80 type A, 6 type B) and shaggy aorta in 36 (8.2%). Emergent/urgent surgery was required in 144 (32.9%). Our current approach included: (I) meticulous selection of arterial cannulation site and type of arterial cannula; (II) selective antegrade cerebral perfusion; (III) maintenance of minimal tympanic temperature between 20 and 23 °C; (IV) early re-warming after distal anastomosis; and (V) maintaining fluid balance below 1,000 mL during cardiopulmonary bypass. A woven Dacron four branch graft was used in all patients. Overall hospital mortality was 4.6% (20/438). Hospital mortality was 9.7% (14/144) in urgent/emergent surgery and 2.0% (6/294) in elective cases. Permanent neurological deficit occurred in 5.3% (23/438) of patients. Prolonged ventilation was necessary in 58 patients (13.2%). Multivariate analysis demonstrated that risk factors for hospital mortality were octogenarian (OR 4.45, P=0.03), brain malperfusion (OR 23.52, P=0.002) and cardiopulmonary bypass time (OR 1.07, P=0.04). The follow-up was completed in 97.9% with mean follow up of 2.3±2.3 years. Survival at 5 and 10 years after surgery was 79.6±3.3% and 71.2±5.0% respectively. In the acute type A dissection group, 10-year survival was 96.8±2.9%, while in the elective non-dissection group 5- and 10-year survival were 81.4±7.2% and 77.0±5.9% respectively. Our current approach for total aortic arch replacement utilizing SACP was associated with low hospital mortality and morbidities leading to favorable long-term outcome.

Copeptina: utilidade na prática clínica

AbstractArginine vasopressin is a key hormone in maintaining fluid balance and vascular tone. Nevertheless,laboratory measurement is difficult and precludes its routine use in clinical practice. Arginine vasopressin derives from a larger precursor peptide along with copeptin, which is released in an equimolar ratio and is more stable in circulation and easy to determine. Copeptin was found to be a surrogate marker for arginine vasopressin release. Recently, copeptin measurement has been shown to be useful in various clinical contexts, such as the differential diagnosis of diabetes insipidus. Also, it has been proposed as a prognostic marker in patients with acute illnesses.

Hyponatremia and Thiazides

Thiazide diuretics were first introduced in 1957 and soon became recognized as a cause of hyponatremia.1 Thiazides are very commonly used for the treatment of hypertension and are recommended by the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7) as first-line therapy for uncomplicated hypertension.2 Thiazides can be the sole cause of hyponatremia, and they may also exacerbate hyponatremia in patients with syndrome of inappropriate antidiuretic hormone hypersecretion. Although thiazides do not inhibit the ability to concentrate urine like loop diuretics, they do impair the diluting ability by (1) inhibition of Na and Cl transport at the cortical diluting sites, (2) stimulation of vasopressin release, (3) reduction of glomerular filtration rate, and (4) enhanced proximal water reabsorption, which reduces delivery to distal diluting sites.1 Water retention from impaired water excretion combined with cation depletion may result in severe hyponatremia. It is recommended that thiazides be avoided in elderly frail patients with chronically high water intake, in patients who have psychogenic polydipsia, and heavy beer drinkers, as these patients depend on excretion of maximally dilute urine to maintain fluid balance.3, 4 Thiazide-induced hyponatremia is linked to increased morbidity and has costly implications. The prevalence of thiazide-induced hyponatremia is not well known and is based mostly on retrospective data and anecdotes. A recent study by Leung and colleagues5 addresses this issue. This retrospective study followed 2613 newly treated adult outpatients with hypertension for up to 10 years. Hyponatremia was classified as moderate if the serum sodium was 125 mmol/L to 130 mmol/L, severe if it was 120 mmol/L to 124 mmol/L, and very severe if <120 mmol/L. Secondary outcomes were total hospitalizations associated with hyponatremia. They compared 229 patients exposed to ongoing thiazide therapy with 2393 patients who were not exposed. In the thiazide-exposed group, 96% of patients were receiving hydrochlorothiazide, with chlorthalidone, indapamide, and metolazone making up the remaining 4%. In the thiazide treatment group, 66 (30%) patients developed hyponatremia (Na ≤130), which was moderate in 88% with a median time to onset of 21 months. The incidence rate was about 3-fold higher in the thiazide-treated patients. Most people responded to discontinuation of the thiazide. This study suggests that treating 15 patients over 5 years would result in one case of hyponatremia. In conclusion, thiazide-induced hyponatremia seems relatively common, and although it often occurs soon after treatment is initiated, patients continue to need monitoring since it can occur up to 10 years later. Our experience supports the current literature. We recommend avoidance of thiazides in patients with psychogenic polydipsia, heavy beer drinkers, and the frail elderly, as thiazide-induced hyponatremia is more likely to occur in people who consume a lot of water. However, thiazides are inexpensive, provide a reasonable reduction in blood pressure, and remain part of the treatment regimen in many patients with hypertension.

Evidence of a rudimentary colon in the elasmobranch, Leucoraja erinacea

The transition from aquatic to terrestrial life presented tetrapodamorphs with the challenge of maintaining water homeostasis and preventing desiccation on land. The colon evolved in terrestrial vertebrates to help maintain fluid balance. Although marine elasmobranchs lack a colon, their spiral intestine contains a subregion that histologically appears to be colon-like, possibly representing an evolutionary precursor to terrestrial digestive tracts. The distal-most region of the spiral intestine of elasmobranchs has no villi and a large number of acid mucins: hallmarks of water absorption in the colons of terrestrial animals. To determine if histologically distinct regions of the elasmobranch digestive tract correspond to functional differences, we compared water absorption in different subregions of the skate, Leucoraja erinacea digestive tract. Water absorption in stomach and spiral intestinal sacs was linear with time and not hydrostatic pressure-dependent. The histologically distinct distal portion of the spiral intestine had a threefold higher rate of water absorption than the proximal portion of the spiral intestine. In addition, the water-selective, colon-specific aquaporin 4 is expressed strongly in the distal spiral intestine epithelia, correlating with the region of the spiral intestine exhibiting the greatest rate of water absorption. We demonstrate that the distal spiral intestine is histologically and functionally distinct from the rest of the spiral intestine and represents a rudimentary colon within the vertebrate lineage.

Vasopressin, Copeptin, and Renal Concentrating Capacity in Patients with Autosomal Dominant Polycystic Kidney Disease without Renal Impairment

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent hereditary renal disease, characterized by cyst formation in the kidneys leading to end stage kidney failure. It is clinically acknowledged that ADPKD patients have impaired urine concentrating capacity, but the mechanism behind this observation is unknown. Fifteen ADPKD patients (estimated GFR ≥60 ml/min per 1.73 m(2)) and 15 age- and sex-matched healthy controls underwent a standard prolonged water deprivation test in which urine and plasma osmolality, vasopressin, and copeptin were measured. The effect of a synthetic vasopressin analog (desmopressin) injected at the moment of maximal urine concentrating capacity was also studied. After 14 hours of water deprivation, ADPKD patients tended to have higher plasma osmolality (P=0.07) and significantly higher vasopressin and copeptin levels (both P<0.05), whereas urine osmolality was similar in ADPKD patients and controls (710 versus 742 mOsmol/kg; P=0.61). Maximal urine concentrating capacity was lower in ADPKD patients (758 versus 915 mOsmol/kg in controls; P<0.001). At maximal urine concentrating capacity, plasma osmolality, vasopressin, and copeptin levels were significantly higher in ADPKD patients. The median increase in urine osmolality after desmopressin administration in ADPKD patients was less than in healthy controls. Already early in their disease, ADPKD patients have impaired maximal urine concentrating capacity brought out upon dehydration, with no evidence of impaired hypothalamic response. To maintain fluid balance, vasopressin concentration increases, which is hypothesized to play a role in ADPKD disease progression.

Renal Replacement Therapy in Critically Ill Patients Receiving Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is a lifesaving procedure used in neonates, children, and adults with severe, reversible, cardiopulmonary failure. On the basis of single-center studies, the incidence of AKI occurs in 70%-85% of ECMO patients. Those with AKI and those who require renal replacement therapy (RRT) are at high risk for mortality, independent of potentially confounding variables. Fluid overload is common in ECMO patients, and is one of the main indications for RRT. RRT to maintain fluid balance and metabolic control is common in some but not all centers. RRT on ECMO can be performed via an in-line hemofilter or by incorporating a standard continuous renal replacement machine into the ECMO circuit. Both of these methods require specific technical considerations to provide safe and effective RRT. This review summarizes available epidemiologic data and how they apply to our understanding of AKI pathophysiology during ECMO, identifies indications for RRT while on ECMO, reviews technical elements for RRT application in the setting of ECMO, and finally identifies specific research-focused questions that need to be addressed to improve outcomes in this at-risk population.