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Hormonal aspects of fluid and sodium balance in the elderly.

Normal aging is accompanied by many changes in the hormonal systems involved in control of sodium and water balance. These alterations, together with age-associated changes in renal function, diminish the capacity of the elderly person to withstand the challenges of illness, drugs, and physiologic stresses. Thus, the aging individual is at increased risk of developing clinically significant alterations in sodium and water balance, which are commonly expressed as hyperatremia and hypoatremia. Awareness of the limitations of homeostatic ability allow the physician to anticipate the impact of illness and drugs on volume and electrolyte status and lead to prevention or to a rational approach to therapeutic intervention and management.

Aged↗

The health of Bosnian refugees in Canada.

UNLABELLED: Many investigators of refugee health have assumed that due to the stresses associated with trauma and forced resettlement, refugees experience more pathology and resulting poor health than their host populations. However, because contradictory findings have emerged from some of these studies, a clear connection between the experiences of trauma, resettlement and health remain ambiguous. OBJECTIVES: The goal of this descriptive study was to put aside initial assumptions pertaining to the health of Bosnian refugees in the study. Rather, health was defined primarily by participants, through personal descriptions and perceptions of their experiences and associated health over time. DESIGN: Ten Bosnian refugees were selected according to age, gender, ability to speak English, and period of time in Canada. Each participant was interviewed on three occasions over a 3-month period in order to gather information pertaining to their experiences and health. Qualitative and quantitative methods were triangulated, that is, an informal, unstructured interview was augmented by investigator observations and structured health and demographic questions. RESULTS: The findings have shown that while war trauma and forced resettlement indeed posed serious risks to participants' health, on balance, they verbalized and were observed to be experiencing positive health and function. CONCLUSIONS: The ability of experience positive health and function in varying degrees following exposure to war trauma and forced resettlement appeared to be largely due to interactions between life events and cumulative personal, psychosocial, and cultural characteristics over time that modified the health risks associated with war trauma and forced resettlement.

Adaptation, Psychological↗

Newborn mice develop balanced Th1/Th2 primary effector responses in vivo but are biased to Th2 secondary responses.

Newborn mice are impaired in their abilities to mount protective immune responses. For decades, it was generally held that the poor responses of newborns were largely due to the developmentally immature state of the T cells. In vitro studies showing that neonatal T cells were deficient in Th1 cytokine production, proliferation, and secondary responsiveness strongly supported this idea. Recently, several studies have challenged this view; animals exposed to Ag as neonates were shown to have mature Th1 responses in adulthood. However, it is not clear whether the mature immune responses were actually mounted by T cells generated after the neonatal stage. We have reexamined this issue by analyzing the capabilities of neonatal lymph node T cells to develop into Ag-specific effector cells during the actual neonatal period. Our results demonstrate that the capacity to develop a balanced Th1/Th2 primary effector response is fully mature within the first week of life. However, while neonatal and adult primary cytokine profiles were very similar, Th2 secondary responses predominated in animals first immunized as newborns. Moreover, we have observed other differences between adults and neonatal responses, including 1) the kinetics of cytokine production and responsiveness to adjuvant during the primary response, and 2) the contribution of spleen and lymph node to secondary responses. We propose that these differences reflect developmental regulation of effector cell function that has important consequences to neonatal immune function.

Animals↗

Molecular determinants of sodium and water balance during early human development.

The past decade has seen enormous progress in understanding the renal regulation of salt and water homeostasis. Most of the key transporters have been cloned, and their physiological importance has been revealed from studies of children with inherited diseases and from mutagenesis studies on a cellular level. We are beginning to understand the complexity with which the activity of these transporters is regulated by hormones. Studies on experimental animals have uniformly shown that the majority of renal salt and water transporters undergo profound changes in the postnatal period. There is generally a robust increase in the number of transporters expressed in a single tubular cell. Many of the transporters also shift their expression from one isoform to another with a somewhat different function. The short-term regulation of salt and water transporters, the key to a well-functioning homeostatic system, is often blunted in the early postnatal period. Taken together, these findings explain some phenomena well known in infants. The low urinary concentrating capacity can, for example, be at least partially attributed to immaturity of the expression of water channels, sodium losses in preterm infants to low expression of the energy generator for salt transport, Na(+),K(+)-ATPase, and the disposition to acidosis to immaturity of the Na(+)/H(+)exchanger. We propose that further studies on how these transporters are regulated will lead to the improved prevention and treatment of salt water balance disorders in infants.

Animals↗

[Renal tubular function in preterm neonates].

Renal tubular function and functional changes in the preterm neonate are discussed. The proximal tubule has a limited capacity in preserving sodium, leading to a daily sodium need from 3 to 5 mEq/kg/day. The reabsorption of glucose, phosphate and amino acids is also low compared to older children but increases quickly for glucose and phosphate. At the level of the distal tubule, a temporary insensibility for aldosterone leads to a lowered sodium-potassium exchange. A limitation in acid excretion is present. Concentration capacity is restricted with a maximal urine osmolality of 360 mosm/liter. Despite this immature tubular function a glomerulotubular balance exists even in the preterm neonate. The kidneys are thus capable to preserve their homeostatic function.

Acid-Base Equilibrium↗

Digestibility, nitrogen excretion, and mean retention time by North American porcupines (Erethizon dorsatum) consuming natural forages.

North American porcupines (Erethizon dorsatum) subsist predominantly on low-protein, high-fiber, high-tannin diets. Therefore, we measured the porcupine's ability to digest dry matter, fiber, and protein by conducting digestion trials on eight natural forages and one pelleted ration varying in concentration of fiber, nitrogen, and tannins. On these diets, dry matter intake ranged from 5 to 234 g/kg(0.75)/d and dry matter digestibility ranged from 62% to 96%. Porcupines digested highly lignified fiber better than many large hindgut fermenters and ruminants. The porcupine's ability to digest fiber may be explained, in part, by their lengthy mean retention time of particles (38.43+/-0.56 h). True nitrogen digestibility was 92% for nontannin forages and pellets. Endogenous urinary nitrogen was 205 mg N/kg(0.75)/d, and metabolic fecal nitrogen was 2.8 g N/kg dry matter intake. Porcupines achieved nitrogen balance at relatively low levels of nitrogen intake (346 mg N/kg(0.75)/d). Tannins reduced the porcupines' ability to digest protein. However, the reduction in protein digestion was not predictable from the amount of bovine serum albumin precipitated. Like many herbivores, porcupines may ameliorate the effects of certain tannins in natural forages on protein digestibility through physiological and behavioral adaptations.

Animals↗

Balance training to maintain mobility and prevent disability.

Balance is important for the safe performance of many activities that allow older people to remain independent in their community. Housework, cooking, shopping, and travel generally require the ability to stand, reach, turn, and bend down and pick up objects from the floor. Multiple interacting factors are implicated in the deterioration of balance. Several strategies have been tested to improve balance and reduce falls. Home-based individualized training that attempted to improve identified deficits reduced falls and improved physical performance and stabilized or reduced disability. Home-based exercise programs that included low-intensity strength and balance training have improved balance and reduced fall rates by about 40% compared to controls. Class-based exercise programs in senior centers or exercise centers have improved balance and physical performance, and some have reduced falls. Programs such as tai chi and social dance look promising and should be further investigated.

Accidental Falls↗

Predicting long-term care institution utilization among post-rehabilitation stroke patients in Taiwan: a medical centre-based study.

PURPOSE: Early identification of predictive factors relevant to the utilization of long-term care institution for stroke patients is important and thus investigated in this study on stroke patients receiving rehabilitation therapy. METHODS: This prospective follow-up investigation carried out during patients' clinical visits, at homes or long-term care institutions, was conducted at least 6 months after stroke on 151 stroke survivors. Functional ability was evaluated with the functional independence measure (FIM) instrument at discharge of the inpatient rehabilitation programme. Balance status was measured using the seven item balance scale of the Fugl-Meyer sensorimotor assessment (FMSA). Major medical, rehabilitative and sociodemographic factors were also examined during hospitalization period as independent variables. RESULTS: Of all the patients surveyed, 23 (15.2%) had been living in long-term care institutions. Univariate statistical analysis indicated that the significant factors related to long-term care institution utilization included recurrence of attack, bilateral involvement, impaired orientation, and functional and balance status at discharge. CONCLUSIONS: Basing on the significant predictors identified, analysis using the logistic regression model correctly classified three quarters of the subjects as long-term care institution residents. The strongest predictors of long-term care institution utilization for stroke patients following rehabilitation therapy were: bilaterally affected, impaired orientation and poor standing ability at discharge.

Aged↗

A new class of low-molecular-weight amphiphilic gelators.

A new powerful class of low-molecular-weight amphiphilic compounds has been synthesized and their structure-property relationships with respect to their gelation ability of organic solvents have been investigated. These compounds are able to gel organic solvents over a broad range of polarity. Especially polar solvents such as valeronitrile and gamma-butyrolactone can be gelled even at concentrations far below 1 wt %. It was found that the gelation ability of these asymmetrically substituted p-phenylendiamines depends on a well-balanced relation of the terminal head group, the units involved in hydrogen bonding (amide or urea groups), and on the length of the alkyl chain. With this class of new gelators it is possible to tailor thermal and mechanical properties in different organic solvents and open various application possibilities.

4-Butyrolactone↗

Sagittal alignment of spine and pelvis regulated by pelvic incidence: standard values and prediction of lordosis.

Pelvis and spinal curves were studied with an angular parameter typical of pelvis morphology: pelvic incidence. A significant chain of correlations between positional pelvic and spinal parameters and incidence is known. This study investigated standards of incidence and a predictive equation of lordosis from selective pelvic and spinal individual parameters. One hundred and forty nine (78 men and 71 women) healthy adults, aged 19-50 years, with no spinal disorders, were included and had a full-spine lateral X-ray in a standardised upright position. Computerised technology was used for the measurement of angular parameters. Mean-deviation section of each parameter and Pearson correlation test were calculated. A multivariate selection algorithm was running with the lordosis (predicted variable) and the other spinal and pelvic parameters (predictor variables), to determine the best sets of predictors to include in the model. A low incidence (<44 degrees ) decreased sacral-slope and the lordosis is flattened. A high incidence (>62 degrees ) increased sacral-slope and the lordosis is more pronounced. Lordosis predictive equation is based on incidence, kyphosis, sacral-slope and +/-T9 tilt. The confidence limits and the residuals (the difference between measured and predicted lordosis) assessed the predicted lordosis accuracy of the model: respectively, +/-1.65 and 2.41 degrees with the 4-item model; +/-1.73 and 3.62 degrees with the 3-item model. The ability of the functional spine-pelvis unit to search for a sagittal balance depended both on the incidence and on the variation section of the other positional parameters. Incidence gave an adaptation potential at two levels of positional compensation: overlying state (kyphosis, T9 tilt), underlying state (sacral slope, pelvic tilt). The biomechanical and clinical conditions of the standing posture (as in scoliosis, low back pain, spondylisthesis, spine surgery, obesity and postural impairments) can be studied by comparing the measured lordosis with the predicted lordosis.

Adult↗

A multi-electrode array for combined microiontophoresis and multiple single-unit recordings.

A remotely controlled multi-electrode array, equipped with a combined electrode (CE) and 3 regular tungsten-in-glass electrodes (TEs) is described. The CE enables ejection of different neuroactive substances from 6 barrels and recording of single-unit activity from the etched tungsten rod placed in the central glass capillary. The CE is prepared with standard tungsten rod, glass-capillaries, and regular micropipette pullers. Such CEs possess a good stiffness-flexibility balance, length, easy cell isolation, high stability of recordings, effective ejection properties, and ability to survive penetration of dura. The efficiency of a 4-electrode array, including the CE, was tested by recording the effects of extracellularly ejected drugs (glutamate, acetylcholine and atropine) on single neurons in the auditory cortex of anesthetized guinea pigs. Induced modifications of single-neuron firing patterns and evoked responses were in agreement with the known effects of individual and combined applications of these drugs. Using this multi-electrode array and spike sorting techniques, the pharmacological environment of up to 12 simultaneously recorded cells can be modulated, and its effect on single neurons and on their interactions can be monitored at distances of up to 900 microns from the CE's tip.

Action Potentials↗

Chronic nimodipine treatment in aged rats: analysis of motor and cognitive effects and muscarinic-induced striatal dopamine release.

Nimodipine is a calcium channel blocker reported to have beneficial effects on treatment of ischemic damage as well as the potential for retarding aspects of brain and behavioral aging when provided chronically to rats. We treated aged male F-344 rats (24 months) with nimodipine in SC pellets in the following doses: 0 (controls), 20 mg (low-dose), or 40 mg (high-dose) replenished after 6 weeks. After 3 months of treatment, surviving rats and a group of young controls (6 months) were tested in a behavioral battery involving exploratory activity in an open field and in a runwheel cage as well as motor abilities required for remaining on an inclined screen, suspended from a wire, and balanced on a rotorod. Rats were also pretrained for one-way active avoidance in a straight runway before being trained in a 14-unit T maze. During 20 trials rats were required to negotiate each of 5 maze segments within 10 s to avoid foot shock (0.8 mA). Nimodipine treatment produced no significant effects on body weight, food intake, or survival of aged rats. Analysis of behavioral results indicated significant age-related decline in performance of all tasks except in open-field behavior. Nimodipine treatment had no significant effects on behavioral performance of aged rats except in maze learning. Rats on the high-dose regimen performed significantly better than aged controls in the maze. The results indicate that chronic nimodipine treatment of aged rats had no toxic effects and might be beneficial for preventing age-related decline in learning performance.

Aging↗

Sustainable systems as organisms?

Schrödinger [Schrödinger, E., 1944. What is Life? Cambridge University Press, Cambridge] marvelled at how the organism is able to use metabolic energy to maintain and even increase its organisation, which could not be understood in terms of classical statistical thermodynamics. Ho [Ho, M.W., 1993. The Rainbow and the Worm, The Physics of Organisms, World Scientific, Singapore; Ho, M.W., 1998a. The Rainbow and the Worm, The Physics of Organisms, 2nd (enlarged) ed., reprinted 1999, 2001, 2003 (available online from ISIS website www.i-sis.org.uk)] outlined a novel "thermodynamics of organised complexity" based on a nested dynamical structure that enables the organism to maintain its organisation and simultaneously achieve non-equilibrium and equilibrium energy transfer at maximum efficiency. This thermodynamic model of the organism is reminiscent of the dynamical structure of steady state ecosystems identified by Ulanowicz [Ulanowicz, R.E., 1983. Identifying the structure of cycling in ecosystems. Math. Biosci. 65, 210-237; Ulanowicz, R.E., 2003. Some steps towards a central theory of ecosystem dynamics. Comput. Biol. Chem. 27, 523-530]. The healthy organism excels in maintaining its organisation and keeping away from thermodynamic equilibrium--death by another name--and in reproducing and providing for future generations. In those respects, it is the ideal sustainable system. We propose therefore to explore the common features between organisms and ecosystems, to see how far we can analyse sustainable systems in agriculture, ecology and economics as organisms, and to extract indicators of the system's health or sustainability. We find that looking at sustainable systems as organisms provides fresh insights on sustainability, and offers diagnostic criteria for sustainability that reflect the system's health. In the case of ecosystems, those diagnostic criteria of health translate into properties such as biodiversity and productivity, the richness of cycles, the efficiency of energy use and minimum dissipation. In the case of economic systems, they translate into space-time differentiation or organised heterogeneity, local autonomy and sufficiency at appropriate levels, reciprocity and equality of exchange, and most of all, balancing the exploitation of natural resources--real input into the system--against the ability of the ecosystem to regenerate itself.

Animals↗

Eye injuries on the battlefields of Iraq and Afghanistan: public health implications.

BACKGROUND: The U.S. Army faces major challenges in balancing the need to protect a soldier from harm while not impeding his ability to fight. Unfortunately, the incidence of combat eye injuries has increased over time, despite the development of protective measures. METHODS: A cross-sectional study of soldiers evacuated from Operation Iraqi Freedom and Operation Enduring Freedom with eye injuries was performed from March 2003 through December 2004. Data for this study came from the Military Office of the Surgeon General (OTSG) Patient Tracking Database. RESULTS: A total of 368 patients (451 eyes) were evacuated for eye-related problems. From March 2003 through December 2004, 15.8% (258 of 1,635 patients, 309 eyes) of all medical evacuations were a result of battle eye injuries (BI), 17.3% (283 of 1,635 patients, 337 eyes) were a result of eye injuries (BI and nonbattle injuries [NBI] combined), and 22.5% (368 of 1,635 patients, 451 eyes) of all evacuations were because of eye-related complaints alone (BI, NBI, or disease) or in combination with other bodily injuries. CONCLUSION: Developing combat eye protection that meets the unique requirements of the military, issuing eyewear to soldiers, and supporting and enforcing its use, will provide the best eye protection for American soldiers during military training exercises and future conflicts.

Afghanistan↗

Unlocking the relationship of biotic integrity of impaired waters to anthropogenic stresses.

The Clean Water Act expressed its goals in terms of restoring and preserving the physical, chemical and biological integrity of the Nation's waters. Integrity has been defined as the ability of the water body's ecological system to support and maintain a balanced integrated, adaptive community of organisms comparable to that of a natural biota of the region. Several indices of biotic integrity (IBIs) have been developed to measure quantitatively the biotic composition and, hence, the integrity. Integrity can be impaired by discharges of pollutants from point and nonpoint sources and by other pollution-related to watershed/landscape and channel stresses, including channel and riparian zone modifications and habitat impairment. Various models that link the stressors to the biotic assessment endpoints, i.e., the IBIs, have been presented and discussed. Simple models that link IBIs directly to single or multiple surrogate stressors such as percent imperviousness are inadequate because they may not represent a true cause-effect proximate relationship. Furthermore, some surrogate landscape parameters are irreversible and the relationships cannot be used for development of plans for restoration of the water body integrity. A concept of a layered hierarchical model that will link the watershed, landscape and stream morphology pollution stressors to the biotic assessment endpoints (IBIs) is described. The key groups of structural components of the model are: IBIs and their metrics in the top layer, chemical water and sediment risks and a habitat quality index in the layer below, in-stream concentrations in water and sediments and channel/habitat impairment parameters in the third layer, and watershed/landscaper pollution generating stressors, land use change rates, and hydrology in the lowest layer of stressors. A modified and expanded Maximum Species Richness concept is developed and used to reveal quantitatively the functional relationships between the top two layers of the structural components and parameters of the model.

Animals↗

In vivo and in vitro regulation of [3H]glyburide binding to brain sulfonylurea receptors in obesity-prone and resistant rats by glucose.

Select brain neurons increase their firing rate when ambient glucose levels rise, possibly via a neuronal ATP-sensitive K+ (KATP) channel and its associated sulfonylurea receptor (SUR). We used receptor autoradiographic binding of 20 nM [3H]glyburide (in the presence or absence of Gpp(NH)p which blocks binding to low-affinity sites) to assess the in vivo and in vitro effects of altering glucose availability upon high- and low-affinity binding to brain SUR. Since the brain's ability to monitor and regulate glucose metabolism is critical to maintenance of energy balance, testing was done in chow-fed male Sprague-Dawley rats which had an underlying predisposition to develop either diet-induced obesity (DIO-prone) or to be diet-resistant (DR-prone) when subsequently fed a high-energy diet. Under control conditions, both in vivo and in vitro studies showed DIO-prone rats to have reduced levels of low-, but not high-affinity [3H]glyburide binding in most forebrain areas. As compared to equiosmolar infusions of mannitol, 60 min unilateral intracarotid glucose infusions at 4 mg/kg/min in awake rats reduced low-affinity [3H]glyburide binding in numerous hypothalamic and amygdalar areas of both DR- and DIO-prone rats with little effect on high-affinity binding. Only in the paraventricular nucleus of DR-prone rats was there a phenotype-specific downregulation of low-affinity binding. Brain sections from other rats were incubated with [3H]glyburide in the presence of 0, 5 or 10 mM glucose. The resultant in vitro effects of glucose were more variable and widespread than intracarotid infusions. Here, glucose often increased low-affinity [3H]glyburide binding, particularly in DR-prone rats at 5 mM. Again, there was little effect on high-affinity binding. Thus, glucose may affect the firing of glucose-responsive neurons by indirectly altering KATP channel function via its effects on low-affinity cell body SUR.

ATP-Binding Cassette Transporters↗

Physiologic mechanisms of adaptation in the fetal calf at birth.

At the moment the umbilicus separates from the fetus during the birthing process, several physiologic functions formerly supported by the dam must become operational in the neonate to ensure survival of the calf. These functions include the ability to maintain adequate oxygen saturation of blood, to regulate acid-base balance, to engage endogenous metabolic pathways for energy production, and to preserve body temperature within critical limits. This article reviews cardiopulmonary function, acid-base balance, and energy metabolism in the fetus and neonate.

Acid-Base Equilibrium↗