Normal Hydration Research Articles

Straylight and corneal edema

Abstract Purpose It is known that corneal edema is associated to increased light scatter. It was the purpose of this study to calculate the intensity and angular distribution of scattered light in a series of corneal samples at different hydration, using a sensitive optical technique. Methods Sixteen fresh porcine eyes were obtained from a local abattoir. To isolate the role of corneal stroma the the epithelium was carefully removed with a mechanical brush. The central 8 mm of each cornea was harvested using a Barron's PKP trephine. To establish corneal hydration, corneal buttons were immersed in Dextran (300kDa) solutions, with concentrations ranging from 5 to 20% w/w, for at least 3 hours. The intensity and angular distribution of scattered light was measured for all corneas by means of a purposely‐developed camera lens that incorporated excised corneas between its glass elements. This lens was used with a CCD camera to record images projected on a computer screen. Before scatter measurements the thichness of each corneal sample was measured by means of a mechanical pachymeter (Mitutoyo IDC 112T, Japan). Results The mean scatter coefficients for the corneas at normal hydration levels was 0.22 (SD=0.059). This value was effectively double (0.46 ; SD= 0.048) at a moderate increase of stromal thickness by 17% and reached a value of 0.56 (SD=0.079) at a relative increase of corneal thickness of 62%. The angular distribution did not significantly deppend on hydration. Conclusion Scattered light intensity increases with corneal edema. Even small changes in corneal hydration affect significantly the narrow angle light scattering properties of corneal stroma.

The influence of various toxic effects on the cornea and changes in corneal light transmission

Normal corneal hydration is necessary for the maintenance of corneal transparency. Damage of the corneal epithelium or endothelium by various external influences disturbs the mechanism by which the cornea maintains normal hydration and transparency. The cornea swells, and the corneal thickness increases, resulting in increased scatter and the development of corneal opacity. The transmission of light across the cornea is changed. The purpose of this study is to investigate spectrophotometrically the corneal light transmission under the influence of the various factors affecting the cornea. We developed a spectrophotometric method to measure the light transmission across the cornea under the influence of various factors affecting the cornea, such as treatment with 0.9% NaCl, saline, or phosphate buffered saline (PBS), solutions employed as placebo eye drops (negative controls) in experimental studies, agents toxic to the cornea, such as diluted acids or alkalis. The method distinguishes between changes in corneal light transmission caused by altered corneal thickness (the level of hydration) and changes resulting from other corneal disturbances which in turn affect corneal light transmission. The results obtained show that the corneal light transmission is decreased following the application of toxic substances on the corneal surface. This decrease is highly dependent on the severity of the corneal injury evoked by individual noxes, and the resulting changes in corneal hydration and transparency. The influence of various influences applied to the cornea, manifested as changes in corneal light transmission, can be measured using our spectrophotometric method with a high degree of sensitivity.

Bee Honey Added to the Oral Rehydration Solution in Treatment of Gastroenteritis in Infants and Children

Among honey's benefits are its anti-inflammatory and antimicrobial effects. Because gastroenteritis is an acute inflammation of the gastrointestinal tract that may be caused by a variety of microbes, the aim of the present study was to verify whether the addition of honey in oral rehydration solution (ORS) could affect the duration of symptoms of acute gastroenteritis in infants and children. One hundred infants and children with acute gastroenteritis were randomly assigned to one of two treatment groups, each consisting of 50 patients: Group I received ORS for rehydration (control), and Group II received ORS with honey. The mean ages of patients of Groups I and II were 1.5 +/- 1.2 and 1.1 +/- 0.8 years, respectively. In the honey-treated group the frequencies of vomiting and diarrhea were significantly reduced compared to the control group (P < .001 and P < .05, respectively). Also, the recovery time, defined as the number of hours from initiation of treatment to when normal soft stools are passed, with the patient showing normal hydration and satisfactory weight gain, was significantly shortened after honey ingestion (P < .001). In conclusion, honey added to ORS promoted rehydration of the body and sped recovery from vomiting and diarrhea.

The effects of different hydration strategies before endovascular treatments to the renal function of the arteriosclerosis obliterans patients

To compare the efficacies of different hydration strategies in protecting the renal function of the arteriosclerosis obliterans (ASO) patients undergoing endovascular treatments. 40 patients who underwent endovascular treatments for arteriosclerosis obliterans of lower extremities in the Vascular Surgery Department of PLA Hospital from January 2009 to October 2009 were divided into normal (serum creatinine < or = 110 micromol/L) and abnormal (serum creatine > 110 micromol/L) groups according to their baseline serum concentration of creatinine before treatments. Each group was treated by different hydration strategies 12 h before procedures. Changes of serum creatinine and creatinine clearance were measured 6, 24, 48 h after procedures to evaluate the changes of renal function and the effects of different hydration strategies. No contrast-induced nephropathy (CIN) was observed among the 40 patients. There are significant differences between normal saline hydration group and control group in the changes of serum creatinine and creatinine clearance 24 h and 48 h after exposure to contrast medium for the normal renal function patients (P < 0.05). For the patients pre-existing renal dysfunction, no significant difference was found between Sodium Bicarbonate + Saline group and Saline group in the changes of Scr and Ccr 6, 24, 48 h after exposure to contrast medium (P > 0.05). Sodium chloride provides a good efficacy for preventing the adverse effect of contrast medium to the renal function of the ASO patients. For the patients pre-existing renal dysfunction, Combination hydration with sodium bicarbonate is not more effective than normal saline alone in preventing contrast-induced renal dysfunction.

Regulation of airway mucosal hydration

Ion channels control the hydration status of the airway epithelium through apical anion secretion and cation absorption, which is accompanied by osmotically obligated water. The key channels in this process are the cystic fibrosis (CF) transmembrane conductance regulator (CFTR), which is principally responsible for Cl- secretion by airway epithelial cells, and the epithelial Na+ channel (ENaC), which is responsible for the absorption of Na ions. In CF, defective CFTR-mediated Cl- secretion and an accompanying upregulation in ENaC-mediated Na absorption results in a reduction in airway surface liquid volume, leading to poorly hydrated mucus and impaired mucociliary clearance. Restoration of normal airway hydration by modulation of ion channel activity represents an important therapeutic strategy for CF. CFTR corrector and potentiator compounds are being developed with the aim of recovering normal Cl- secretion. Ca2+-activated Cl- channels (CaCCs) are expressed by the respiratory epithelia and are reported to be functionally upregulated in CF and offer a ‘surrogate’ pathway for Cl- secretion. TMEM16A has recently been described as a CaCC in the airway epithelium and, as such, represents an alternative target for restoring Cl- secretion in CF. An alternative therapeutic strategy for CF is to inhibit ENaC, thereby blocking excessive Na absorption. This can be achieved by direct blockade of ENaC or inhibition of the channel-activating proteases (CAPs), whose activity regulates ENaC function. This review will describe the regulation of airway mucosal hydration by ion channels and the efforts currently underway to restore normal mucosal hydration in disease patients by modulating the function of these channels.

Assessment of degree of hydration in dialysis patients using whole body and calf bioimpedance analysis

Prescription of an appropriate post hemodialysis (HD) dialysis target weight requires accurate evaluation of the degree of hydration. The aim of this study was to investigate whether a state of normal hydration as defined by calf bioimpedance spectroscopy (cBIS) could be characterized in HD and normal subjects (NS). cBIS was performed in 62 NS (33 m/29 f) and 30 HD patients (16 m /14 f) pre- and post-dialysis to measure extracellular resistance. Normalized calf resistivity at 5 kHz (ρN,5) was defined as resistivity divided by body mass index. Measurements were made at baseline (BL) and at a state of normal hydration (NH) established following the progressive reduction of post-HD weight over successive dialysis treatments until the ρN,5 was in the range of NS. Blood pressures were measured pre- and post-HD treatment. ρN,5 in males and females differed significantly in NS (20.5±1.99 vs 21.7±2.6 10-2 Ωm3/kg, p>0.05). In patients, ρN,5 notably increased and reached NH range due to progressive decrease in body weight, and systolic blood pressure (SBP) significantly decreased pre- and post-HD between BL and NBH respectively. This establishes the use of ρN,5 as a new comparator allowing the clinician to incrementally monitor the effect of removal of extracellular fluid from patients over a course of dialysis treatments.

Acute renal failure with acyclovir treatment in a child with leukemia

Acyclovir is an effective, frequently used antiviral agent. Adverse effects of this drug are well known and are especially seen with high doses and/or dehydration. In this article, we report a 6-year-old boy with leukemia with nonoliguric acute renal failure in normal hydration status after using acyclovir treatment. He had no preexisting renal impairment, and there were no additional symptoms. Dimercaptosuccinic acid radionucleid scyntigraphy and other laboratory findings revealed impairment of proximal tubule function, in addition to distal tubule. We emphasize that renal functions should be monitored carefully during treatment with acyclovir, and asymptomatic nephrotoxicity must be kept in mind.

Prevention of acute kidney injury in the intensive care unit

Summary Acute Kidney injury (AKI) is a relatively common condition in the intensive care unit and is associated with an increase in mortality. Whilst it can be treated by the use of renal replacement therapies an independent increase in mortality still exists. It is therefore seems intuitive that the prevention of AKI should be associated with a reduction in both mortality and morbidity and an improvement in patient care for this reason there has been many attempts to develop strategies to reduce the incidence of AKI. These strategies involve the use of therapeutic agents to prevent renal failure, the avoidance of nephrotoxic agents and the maintenance of normal hydration and renal perfusion. More recently there has been focus on the early recognition of patients at risk of developing AKI and focussing care to avoid exacerbation of risk factors.

CARACTERÍSTICA DAS FEZES E EXCREÇÃO FECAL DE AREIA EM EQUINOS MANTIDOS A PASTO NO MUNICÍPIO DE CACHOEIRO DO ITAPEMIRIM, ESPÍRITO SANTO, BRASIL

The characteristic of feces and fecal excretion of sand were evaluated in 112 mares in the Cachoeiro do Itapemirim city, state of Espirito Santo, Brazil. From each animal were collected 200 grams of feces by transrectal palpation, and after collection were evaluated for consistency, hydration, color, smell, size of fiber, grains and presence of foreign body. Simultaneously was performed the test of sedimentation of sand to determine the fecal excretion of sand. In 100% of animals feces were firm with the unique odor. As for color, 90% (101/112) of the animals showed feces of moss green color, while 10% (11/112) showed dark olive green stool. For consistency, 23.21% (26/112) had stool slightly pasty and 76.79% (86/112) had stool firm. Regarding the degree of hydration, 23.21% (26/112) had stool with slight increase in water content, while 76.79% (86/112) had stool with normal hydration. The test of sedimentation of the sand revealed that 100% (112/112) of animals excreted sand at the time of the study. Although the prevalence of fecal excretion of sand has been high, the presence of sand in the gastrointestinal tract of animals evaluated is not causing gastroenteric changes. KEY WORDS: Equine, feces, sand.

Water, electrolytes, vitamins and trace elements - Guidelines on Parenteral Nutrition, Chapter 7.

A close cooperation between medical teams is necessary when calculating the fluid intake of parenterally fed patients. Fluids supplied parenterally, orally and enterally, other infusions, and additional fluid losses (e.g. diarrhea) must be considered. Targeted diagnostic monitoring (volume status) is required in patients with disturbed water or electrolyte balance. Fluid requirements of adults with normal hydration status is approximately 30–40 ml/kg body weight/d, but fluid needs usually increase during fever. Serum electrolyte concentrations should be determined prior to PN, and patients with normal fluid and electrolyte balance should receive intakes follwing standard recommendations with PN. Additional requirements should usually be administered via separate infusion pumps. Concentrated potassium (1 mval/ml) or 20% NaCl solutions should be infused via a central venous catheter. Electrolyte intake should be adjusted according to the results of regular laboratory analyses. Individual determination of electrolyte intake is required when electrolyte balance is initially altered (e.g. due to chronic diarrhea, recurring vomiting, renal insufficiency etc.). Vitamins and trace elements should be generally substituted in PN, unless there are contraindications. The supplementation of vitamins and trace elements is obligatory after a PN of >1 week. A standard dosage of vitamins and trace elements based on current dietary reference intakes for oral feeding is generally recommended unless certain clinical situations require other intakes.

Validity of Bioelectrical Impedance Analysis to Estimate Body Composition Changes After Bariatric Surgery in Premenopausal Morbidly Women

In obese patients, subtle variations of the hydration of soft tissues can propagate errors in bioelectrical impedance analysis (BIA) measures of body composition. Bioelectrical impedance vector analysis (BIVA) is a useful method to evaluate tissue hydration. Laparoscopic adjustable gastric banding (LAGB) is a purely restrictive bariatric surgical procedure resulting in lower fat-free mass (FFM) loss than other malabsorptive or mixed intervention. The aim of this study was to evaluate the 6- and 12-month changes in body composition in a homogeneous group of premenopausal morbidly obese women treated by LAGB by comparing the results of conventional BIA and BIVA with dual-energy X-ray absorptiometry (DXA) method. Forty-five consecutive morbidly obese patients (mean age, 35.3 +/- 9.1 years; body mass index, 34.5-48.7 kg/m(2)) were prospectively evaluated at the Endocrinology Unit of the Department of Molecular and Clinical Endocrinology and Oncology. The LAGB device (Lap-Band System; Inamed Health, Santa Barbara, CA, USA) was inserted laparoscopically. Soft tissue hydration was evaluated by BIVA; fat mass (FM) and FFM were evaluated by BIA (BIA 101 RJL, Akern Bioresearch, Firenze, Italy) and by DXA (Hologic QDR 4500A S/N 45622; Hologic Inc., Bedford, MA, USA). Pre- and postoperative BIVA vectors indicated a normal hydration in all patients. Postoperatively, the excess of body weight loss was mainly due to a decrease in FM. The regression analysis of BIA and DXA methods at baseline and at the 6- and 12-month follow-up for FM r (2) values were 0.98, 0.94, and 0.99, respectively (p < 0.001); FM% r (2) values were 0.91, 0.89, and 0.98, respectively (p < 0.001); and FFM r (2) values were 0.87, 0.82, 0.99, respectively (p < 0.001). BIA and DXA measurements of body composition exhibit a high relative agreement in the study group of normo-hydrated obese subjects. BIA tends to overestimate FFM, but this effect is reduced along with the weight loss during the follow-up. Under the stable hydration, the BIA method may be useful as an alternative to DXA in a selected clinical setting when repeated comparisons of body composition are required.

Long-Term Effects of Dietary Sodium Intake on Cytokines and Neurohormonal Activation in Patients With Recently Compensated Congestive Heart Failure

Background A growing body of evidence suggests that the fluid accumulation plays a key role in the pathophysiology of heart failure (HF) and that the inflammatory and neurohormonal activation contribute strongly to the progression of this disorder. Methods and Results The study evaluated the long-term effects of 2 different sodium diets on cytokines neurohormones, body hydration and clinical outcome in compensated HF outpatients (New York Heart Association Class II). A total of 173 patients (105 males, mean age 72.5 ± 7) recently hospitalized for worsening advanced HF and discharged in normal hydration and in clinical compensation were randomized in 2 groups (double blind). In Group 1, 86 patients received a moderate restriction in sodium (120 mmol to 2.8 g/day) plus oral furosemide (125 to 250 mg bid); in Group 2, 87 patients: received a low-sodium diet (80 mmol to 1.8 g/day) plus oral furosemide (125 to 250 mg bid). Both groups were followed for 12 months and the treatment was associated with a drink intake of 1000 mL daily. Neurohormonal (brain natriuretic peptide, aldosterone, plasma rennin activity) and cytokines values (tumor necrosis factor-α, interleukin-6) were significantly reduced with a significant increase of the anti-inflammatory cytokine interleukin-10 at 12 months in normal, P < .0001) than low-sodium group. The low-sodium diet showed a significant activation of neurohormones and cytokines and worsening the body hydration, whereas moderate sodium restriction maintained dry weigh and improved outcome in the long term. Conclusions Our results appear to suggest a surprising efficacy of a new strategy to improve the chronic diuretic response by increasing Na intake and limiting fluid intake. This counterintuitive approach underlines the need for a better understanding of factors that regulate sodium and water handling in chronic congestive HF. A larger sample of patients and further studies are required to evaluate whether this is due to the high dose of diuretic used or the low-sodium diet.

Automated Noninvasive Clinical Dehydration Detection Device

Dehydration is a common problem in healthy individuals as well as the elderly and chronically ill. People are often poorly attuned to hydration, and despite widespread awareness of the problem, fatal and near-fatal episodes occur frequently. Typical indicators of hydration status include changes in body weight, urine specific gravity, blood plasma levels, and bioelectrical impedance. Challenges to estimating hydration status from these indicators include the invasive nature of some methods as well as the cost and time required. We have developed a noninvasive device for monitoring hydration status. Our design is inspired by the traditional clinical protocol that approximates fluid loss on the order of 1-2% dehydration by assessing radial pulse before and after a supine to standing transition. The prototype comprises an inertial measurement unit (Xsens MTi) and a wearable heart rate monitor (Polar S810i). In order to compare heart rate behavior under normal and low hydration levels, fluid loss equivalent to 1-4% of the baseline body weight was induced by exercise in three healthy subjects during two data collection sessions. In the first (control) session, subjects replaced fluids every 15 minutes during exercise to maintain their body weight within 0.2% of their baseline value. Fluids were not replaced during the second (test) session, and subjects lost an average of 1.2% of their body weight. Heart rate and body position measurements were recorded before and after exercise while subjects performed repeated supine-to-standing movements and knee-to-chest stretching exercises (supine position only). All post-processing was performed using MATLAB (The MathWorks). Average heart rate was calculated over a 10 second period. Pilot data demonstrates the device's ability to detect hydration changes on the order of 1% in one-third the time required by the traditional clinical protocol (30 seconds compared to 90 seconds). The average rise time from baseline to maximum heart rate and the maximum heart rate following supine-to-standing transitions were significantly longer and greater, respectively, in the dehydrated subjects. Although not statistically significant, the average heart rate during knee-to-chest stretching exercises was elevated in the dehydrated state.

Transmembrane Protein 16A (TMEM16A) Is a Ca2+-regulated Cl– Secretory Channel in Mouse Airways

For almost two decades, it has been postulated that calcium-activated Cl(-) channels (CaCCs) play a role in airway epithelial Cl(-) secretion, but until recently, the molecular identity of the airway CaCC(s) was unknown. Recent studies have unequivocally identified TMEM16A as a glandular epithelial CaCC. We have studied the airway bioelectrics of neonatal mice homozygous for a null allele of Tmem16a (Tmem16a(-/-)) to investigate the role of this channel in Cl(-) secretion in airway surface epithelium. When compared with wild-type tracheas, the Tmem16a(-/-) tracheas exhibited a >60% reduction in purinoceptor (UTP)-regulated CaCC activity. Other members of the Tmem16 gene family, including Tmem16f and Tmem16k, were also detected by reverse transcription-PCR in neonatal tracheal epithelium, suggesting that other family members could be considered as contributing to the small residual UTP response. TMEM16A, however, appeared to contribute little to unstimulated Cl(-) secretion, whereas studies with cystic fibrosis transmembrane conductance regulator (CFTR)-deficient mice and wild-type littermates revealed that unstimulated Cl(-) secretion reflected approximately 50% CFTR activity and approximately 50% non-Tmem16a activity. Interestingly, the tracheas of both the Tmem16a(-/-) and the CFTR(-/-) mice exhibited similar congenital cartilaginous defects that may reflect a common Cl(-) secretory defect mediated by the molecularly distinct Cl(-) channels. Importantly, the residual CaCC activity in Tmem16a(-/-) mice appeared inadequate for normal airway hydration because Tmem16a(-/-) tracheas exhibited significant, neonatal, lumenal mucus accumulation. Our data suggest that TMEM16A CaCC-mediated Cl(-) secretion appears to be necessary for normal airway surface liquid homeostasis.

Molecular basis of transport and regulation in the Na+/betaine symporter BetP

Osmoregulated transporters sense intracellular osmotic pressure and respond to hyperosmotic stress by accumulation of osmolytes to restore normal hydration levels. Here we report the determination of the X-ray structure of a member of the family of betaine/choline/carnitine transporters, the Na(+)-coupled symporter BetP from Corynebacterium glutamicum, which is a highly effective osmoregulated uptake system for glycine betaine. Glycine betaine is bound in a tryptophan box occluded from both sides of the membrane with aromatic side chains lining the transport pathway. BetP has the same overall fold as three unrelated Na(+)-coupled symporters. Whereas these are crystallized in either the outward-facing or the inward-facing conformation, the BetP structure reveals a unique intermediate conformation in the Na(+)-coupled transport cycle. The trimeric architecture of BetP and the break in three-fold symmetry by the osmosensing C-terminal helices suggest a regulatory mechanism of Na(+)-coupled osmolyte transport to counteract osmotic stress.

Calcium aluminate cement hydration in a high alkalinity environment

The present paper forms part of a broader research project that aims primarily to devise new cementitious products via the alkali activation of silico-aluminous materials. This work addresses the possibility of using small percentages of calcium aluminate cement (CAC) as a source of reactive aluminium. For this reason, a preliminary review was needed of the behaviour of CACs in highly alkaline media (2, 8 and 12M NaOH solutions). Two, 28- and 180-day mechanical strength was determined and the reaction products were characterized with XRD and FTIR. The water-hydrated CAC was used as the control.The results obtained showed that CAC hardening took place much more slowly in highly alkaline media than in water. Nonetheless, the 28-day compressive strength obtained, ≥80MPa. As main reaction products, to ambient temperature and from the two days of cured, cubic aluminate C3AH6), and AH3 polymorphs are formed, instead of the usual hexagonal aluminatos (CAH10 and C2AH8) that are formed in the normal hydrate with water.

Association between intestinal tight junction permeability and whole-body electrical resistance in healthy individuals: A hypothesis

Objective Intestinal permeability describes non-carrier–mediated modes of transport through the intestinal epithelium. Wrist–ankle bioimpedance analysis (BIA) is a standard method to determine body composition based on the measurements of whole-body electrical resistance and reactance values. The present report deals with the coincidentally observed associations between permeability results and electrical raw values of BIA and their subsequent reproduction in a larger group of individuals. Methods Tetrapolar wrist–ankle BIA was performed on day 1 in the initial sample (12 women, 36 ± 11 y of age) and the validation sample (36 healthy subjects, 26 women and 10 men, 35 ± 14 y of age). Intestinal permeability tests (lactulose and mannitol) were implemented within 1 wk thereafter. Wrist–ankle electrical resistance plus electrical resistance between current-conducting electrodes and voltage-sensing electrodes (Rtotal) was measured at 5 kHz and 100 kHz. Results Permeability and bioimpedance raw values were normal, indicating normal tight junction permeability and normal hydration. Lactulose correlated to R 50total in the initial sample (ρ = 0.639, P = 0.025) and in the validation sample (ρ = 0.673, P < 0.001). Weaker associations to R 50total were observed with mannitol (ρ = 0.381, P = 0.008) and lactulose/mannitol (ρ = 0.369, P = 0.010) in the total group of individuals. Regression analyses demonstrated that R 50total alone accounted for 41.3% of the variance in lactulose permeability. Conclusion The nature of the observed positive association between intestinal tight junction permeability and whole-body electrical resistance is unclear. We hypothesize that regulation involving submolecular mechanisms based on the principles of quantum physics might have caused the observed association. Such coherent mechanisms might possibly play a role in basal physiologic regulation in humans.

Biophysical characteristics of skin in diabetes: a controlled study

Cutaneous complications are common in diabetes. Previous assays suggest that hyperglycemia and decreased insulin signal are involved in the impairment of skin function. The aim of this study was to evaluate the biophysical characteristics of skin in patients with diabetes mellitus and compares them with healthy non-diabetic controls. To measure biophysical characteristic of skin including transepidermal water loss (TEWL), water content, sebum and skin elasticity in patients with diabetes mellitus and compare them with healthy non-diabetic controls. This case-control study was conducted on 38 patients with diabetes and 40 age- and sex-matched healthy people. The biophysical properties of skin including stratum corneum (SC) hydration, sebum content, TEWL and skin elasticity were measured and compared between the two groups at three different locations of the body. The measurement of SC hydration and TEWL showed no significant difference between diabetics and controls. The skin surface lipids on the forehead but not other sites were significantly lower in the diabetics than in the controls. Acoustic wave propagation speed, a measurement related to skin elasticity, was significantly lower in forearm and forehead of diabetics. Diabetes affects some functional properties of epidermis and dermis that may responsible for many cutaneous manifestations of diabetes. These results suggest that patients with diabetes mellitus tend to show a normal hydration state of the SC together with decreased sebaceous gland activity and impaired skin elasticity, without any impairment of the SC barrier function.

Bioelectrical phase angle values in a clinical sample of ambulatory rehabilitation patients

BackgroundPhase angle (PhA) is derived from the resistance and reactance measurements obtained from bioelectric impedance analysis (BIA) and is considered indicative of cellular health and membrane integrity. This study measured PhA values of rehabilitation patients and compared them to reference values, measures of functional ability and serum C-reactive protein (CRP) levels to explore their utility as a clinical tool to monitor disease progression and treatment efficacy.MethodsThis cross-sectional observational study was conducted on 215 ambulatory rehabilitation patients aged 20 – 94 years. All participants had been hospitalised for a stroke, orthopaedic or other condition resulting in a functional limitation. PhA was derived from BIA analysis and functional ability characterised using the Functional Independence Measure (FIM), timed up and go (TUG) and maximal quadriceps strength (MQS). Serum levels of CRP were also collected.ResultsStroke patients had the highest PhA (5.3°) followed by elective orthopaedic surgery (5.0°) with the other group (4.3°) significantly lower than both previous categories (p < 0.001). Ambulatory rehabilitation patients' PhA values were dependent on age and sex (p < 0.001), lower than published age matched healthy reference values (p ≤ 0.05) and similar to other hospitalised or sick groups, but also higher than values reported in critically ill patients. Patients with CRP values less than 10 mg.L-1 had significantly (p = 0.005) higher mean PhA values. Furthermore, the highest functional status quartiles had significantly higher PhAs (p ≤ 0.04) for the FIM, MQS and TUG measures.ConclusionThe results suggest that the phase angles of rehabilitation patients are between those of healthy individuals and seriously ill patients, thereby supporting claims that PhA is indicative of general health status. Phase angles are a potentially useful indicator of functional status in patients commencing an ambulatory rehabilitation program with a normal hydration status.

Density Functional Study of Intradimer Proton Transfers in Hydrated Adenine Dimer Ions, A2+(H2O)n (n = 0−2)

Structures of mono- and dihydrated adenine dimers and their cations were calculated using B3LYP density functional theory with the 6-31+G(d,p) basis set, in order to help understand photofragmentation experiments of hydrated adenine dimers from the energetics point of view. Several important pathways leading to the major fragmentation product, protonated adenine ion (AH(+)), thermodynamically at minimum costs were investigated at the ground-state electronic potential surface of hydrated adenine dimer cations. Our calculations suggest that the proton transfer from one adenine moiety to the other in hydrated dimer ions readily occurs with negligible barriers in normal hydration conditions. In asymmetrically hydrated ions, however, the proton transfer to more hydrated adenine moieties is kinetically hindered due to heightened transition-state barriers, while the other way is still barrierless. Such directional preference in proton transfer may be characterized as a unique dimer ion property, stemming from the difference in basicity of the two nitrogen atoms involved in the double hydrogen bond that would be equivalent without hydration. We also found that dimer cleavage requires about 4 times larger energy than evaporation of individual water molecules, so it is likely that most solvent molecules evaporate before the eventual dimer cleavage when available internal energy is limited.