Correction of hyponatremia

The development of selective oral V2 receptor antagonists has led to confirmation of established concepts of the pathogenesis of hyponatremia and to new approaches to its treatment. V2 receptor antagonists are effective and promising agents. Their properties as specific pharmacologic tools will facilitate the treatment of the different types of hyponatremia because of the improved predictability of response, and improved control of fine tuning of responses, compared with what is achieved by current therapies. In addition, the quality of life of hyponatremic patients will improve because there will be less need for severe fluid restrictions. It is likely that these agents can be administered over prolonged periods of time.

Hip Pain as the Presenting Manifestation of Acute Gouty Sacroiliitis

Gout can present in a variety of less typical forms. We describe a case of an elderly woman presenting with hip and lower extremity pain. It remained undiagnosed for several days but proved to be secondary to gouty involvement of the right sacroiliac (SI) joint. Monosodium urate crystals were identified in computed tomographic guided aspiration of the SI joint. The importance of obtaining a good history and performing a complete physical examination if the diagnosis of sacroiliitis (or any other musculoskeletal disorder) is to be made, its cause defined, and proper treatment instituted is emphasized.

A quantitative, internally controlled real-time PCR Assay for the detection of parvovirus B19 DNA

Parvovirus B19 is an erythrovirus causing diverse clinical manifestations ranging from asymptomatic or mild, to more severe outcomes in, for example, immune-compromised patients. B19 is spread primarily via the respiratory route, but it can also be transmitted via blood and blood products. Viral loads in blood or plasma donations amount up to 10(11) genome equivalents/ml. Therefore, screening of plasma for fractionation for the presence of B19 and removal of highly loaded donations is a way to limit considerably the input of B19 into production pools and to improve further the safety of plasma products. An assay for the quantitative detection of B19 DNA, based on real-time PCR using ABI Prism SDS7700 (TaqMan) is described here. This assay allows precise quantitation of viral loads over 7 orders of magnitude. An exogenous internal control (internal quality marker) is included in each individual sample to prevent false negative results. A linearized plasmid is used as an internal quality marker that contains the identical sequence of the B19 target sequence but with an altered probe hybridization site. This allows co-amplification of B19 and internal quality marker and co-detection of FAM (6-carboxyfluorescein) or VIC labeled probes respectively. The assay is validated according to current guidelines (of the International Conference on Harmonization, Paul Ehrlich Institute, and the Council of Europe) and is optimized for high throughput screening.

Interactive effects of elevated CO2 concentration and nitrogen supply on partitioning of newly fixed 13C and 15N between shoot and roots of pedunculate oak seedlings (Quercus robur)

Pedunculate oak (Quercus robur L.) seedlings were grown for 3 or 4 months (second- and third-flush stages) in greenhouses at two atmospheric CO2 concentrations ([CO2]) (350 or 700 micromol mol(-1)) and two nitrogen fertilization regimes (6.1 or 0.61 mmol N l(-1) nutrient solution). Combined effects of [CO2] and nitrogen fertilization on partitioning of newly acquired carbon (C) and nitrogen (N) were assessed by dual 13C and 15N short-term labeling of seedlings at the second- or third-flush stage of development. In the low-N treatment, root growth, but not shoot growth, was stimulated by elevated [CO2], with the result that shoot/root biomass ratio declined. At the second-flush stage, overall seedling biomass growth was increased (13%) by elevated [CO2] regardless of N fertilization. At the third-flush stage, elevated [CO2] increased growth sharply (139%) in the high-N but not the low-N treatment. Root/shoot biomass ratios were threefold higher in the low-N treatment relative to the high-N treatment. At the second-flush stage, leaf area was 45-51% greater in the high-N treatment than in the low-N treatment. At the-third flush stage, there was a positive interaction between the effects of N fertilization and [CO2] on leaf area, which was 93% greater in the high-N/elevated [CO2] treatment than in the low-N/ambient [CO2] treatment. Specific leaf area was reduced (17-25%) by elevated [CO2], whereas C and N concentrations of seedlings increased significantly in response to either elevated [CO2] or high-N fertilization. At the third-flush stage, acquisition of C and N per unit dry mass of leaf and fine root was 51 and 77% greater, respectively, in the elevated [CO2]/high-N fertilization treatment than in the ambient [CO2]/low-N fertilization treatment. However, there was dilution of leaf N in response to elevated [CO2]. Partitioning of newly acquired C and N between shoot and roots was altered by N fertilization but not [CO2]. More newly acquired C and N were partitioned to roots in the low-N treatment than in the high-N treatment.

Treatment of severe hyponatremia: conventional and novel aspects

Hyponatremia is a frequent electrolyte disorder. A hyponatremia is called acute severe (<115 mM) when the duration has been <36 to 48 h. Such patients often have advanced symptoms as a result of brain edema. Acute severe hyponatremia is a medical emergency. It should be corrected rapidly to approximately 130 mM to prevent permanent brain damage. In contrast, in chronic severe hyponatremia (>4 to 6 d), there is no brain edema and symptoms are usually mild. In such patients, a number of authors have recommended a correction rate <0.5 mM/h to approximately 130 mM to minimize the risk of cerebral myelinolysis. Sometimes it is not possible to diagnose whether a severe hyponatremia is acute or chronic. In such cases, an initial imaging procedure is helpful in deciding whether rapid or slow correction should be prescribed. The modalities of treatment of severe hyponatremia have so far consisted of infusions of hypertonic saline plus fluid restriction. In the near future, vasopressin antagonists will become available. Preliminary experience has already demonstrated their efficiency of inducing a sustained water diuresis and a correction of hyponatremia.

Immune response to influenza vaccine in healthy elderly: lack of association with plasma beta-carotene, retinol, alpha-tocopherol, or zinc

Immunity and nutritional status are compromised with age, yet the relationship between them is unclear. Immune responses and plasma micronutrient levels of 61 healthy elderly (mean 81 years) and 27 young (mean 27 years) were assessed before and after immunization with trivalent influenza vaccine (FLU). FLU-induced proliferation and IFN-gamma levels of elderly were lower than young before and after immunization. Proliferation and IFN-gamma levels increased after immunization of young, but not elderly. FLU-induced IL-6 and IL-10 levels did not change after immunization of either group. While antibody titers to all three FLU components increased after vaccination of young and elderly, post-vaccination titers of elderly were lower than young. Although plasma retinol and zinc levels of young and elderly were similar before and after vaccination, elderly had higher plasma beta-carotene and alpha-tocopherol levels at both assessments that increased after vaccination. Importantly, plasma micronutrient levels were comparable for elderly with or without intact (titers >/=40 and fourfold rise post-vaccination) antibody responses after vaccination. These results suggest that differences in these plasma micronutrients (1) are not required to observe decreased FLU responses of healthy elderly compared to young and (2) are not associated with differences in antibody responses among healthy elderly.

Temperature effects on hydraulic conductance and water relations of Quercus robur L

The effects of temperature on root and shoot hydraulic conductances (g(shoot) and g(root)) were investigated for Quercus robur L. saplings. In a first experiment, conductances were measured with a High Pressure Flow Meter on excised shoots and detopped root systems. The g(root) and g(shoot) increased considerably with temperature from 0-50 degrees C. Between 15 degrees C and 35 degrees C, g(shoot) and g(root) varied with water viscosity. In a second experiment, the impact of temperature-induced changes in g(root) on sapling transpiration (E) and leaf water potential (psileaf) was assessed. Intact plants were placed in a growth cabinet with constant air and variable soil temperatures. E increased linearly with soil temperature but psileaf remained constant. As a consequence, a linear relationship was found between E and g(plant). The results illustrate the significance of g(plant) for the stomatal control of transpiration and the significance of temperature for tree water transport.

The C-terminal domain-phosphorylated IIO form of RNA polymerase II is associated with the transcription repressor NC2 (Dr1/DRAP1) and is required for transcription activation in human nuclear extracts

Activation of class II gene transcription may involve alleviation of transcription repression as well as stimulation of the assembly and function of the general RNA polymerase (RNAP) II transcription machinery. Here, we investigated whether activator-reversible transcription repression by NC2 (Dr1/DRAP1) contributes to maximum induction levels in unfractionated HeLa nuclear extracts. Surprisingly, we found that depletion of NC2 does not significantly affect basal transcription, but dramatically reduces activated transcription. Immunoblot analyses revealed that the loss of activator function coincides with selective removal of the C-terminal domain (CTD)-hyperphosphorylated RNAP IIO along with NC2. Coimmunoprecipitation experiments with purified factors confirmed that NC2 interacts with RNAP IIO, but not with the unphosphorylated or hypophosphorylated RNAP IIA or CTD-less RNAP IIB forms. Finally, we demonstrate that, in contrast to previously published observations in cell-free systems reconstituted with purified factors, only the CTD-phosphorylated form of RNAP II can mediate activator function in the context of unfractionated HeLa nuclear extracts. These findings reveal an unexpected link between NC2 and transcription activation and suggest that regulation of RNAP II transcription through reversible CTD phosphorylation might be more complex than previously proposed.

[Hyponatremia--with comments on hypernatremia]

Disorders of the serum sodium concentration (hypo- and hypernatremia) are amongst the most frequent electrolyte disorders in clinical medicine. They are attributable to disturbance of to water metabolism. Hyponatremia is almost always a condition of water excess while hypernatremia is due water deficiency. Physiological normonatremia (normal plasma osmolality) is maintained by an integrated system involving regulated water intake via thirst and control of water excretion via antidiuretic hormone secretion. Therefore hypo- and hypernatremia should be analyzed in terms of dysregulated ADH secretion, fluid intake and renal water excretion. Hyponatremia is usually a disorder of vasopressin excess, due to 'non-osmotic' vasopressin release. The latter may occur in two different settings: (I) SIADH, (II) baroreceptor mediated vasopressin secretion (cardiac failure, liver cirrhosis). This entities are easy to distinguish in clinical practice. SIADH is associated with striking lower plasma concentrations of urate, creatinine and urea. In SIADH the blood pressure is normal and there is no edema. In contrast in the hyponatremia of liver cirrhosis and heart failure the plasma measurements indicated are usually slightly elevated, the blood pressure is low and there is edema. The typical patient with hypernatremia is old and has no thirst sensation. Hypo- or hypernatremia may cause major neurologic symptoms. These symptoms are more related to the rate of change in the serum sodium concentration than to the absolute level of a hypo- or hypernatremia reached. The traditional treatment for hyponatremia used to be water restriction. However V2-Vasopressin-Antagonists may provide a better treatment modality in the future. Hypernatremia is treated by slow rehydratation.

Respiration as the main determinant of carbon balance in European forests

Carbon exchange between the terrestrial biosphere and the atmosphere is one of the key processes that need to be assessed in the context of the Kyoto Protocol. Several studies suggest that the terrestrial biosphere is gaining carbon, but these estimates are obtained primarily by indirect methods, and the factors that control terrestrial carbon exchange, its magnitude and primary locations, are under debate. Here we present data of net ecosystem carbon exchange, collected between 1996 and 1998 from 15 European forests, which confirm that many European forest ecosystems act as carbon sinks. The annual carbon balances range from an uptake of 6.6 tonnes of carbon per hectare per year to a release of nearly 1 t C ha(-1) yr(-1), with a large variability between forests. The data show a significant increase of carbon uptake with decreasing latitude, whereas the gross primary production seems to be largely independent of latitude. Our observations indicate that, in general, ecosystem respiration determines net ecosystem carbon exchange. Also, for an accurate assessment of the carbon balance in a particular forest ecosystem, remote sensing of the normalized difference vegetation index or estimates based on forest inventories may not be sufficient.

Sensitive single-stage PCR using custom-synthesized internal controls

A new approach for an internally controlled PCR was developed using a custom-synthesized oligonucleotide as the internal control. Three different PCR setups demonstrated the usefulness of this approach: (i) the addition of the respective internal control to samples containing ssDNA virus Parvo B19; (ii) the co-extraction of plasma samples and the respective internal control for the detection of the ssDNA virus TTV; and (iii) the addition of the respective internal control to a crude lysate of tail pieces for the genotyping of FVIII knockout mice, demonstrating that this approach is also applicable for dsDNA.

The treatment of hyponatraemia using vasopressin antagonists

Hyponatraemia is a frequent electrolyte disorder. It is primarily attributable to vasopressin excess plus sustained fluid intake. Hyponatraemia causes CNS symptoms, especially during the first 2-4 days; these symptoms are related to brain swelling. Hyponatraemia occurs in the setting of liver cirrhosis and congestive cardiac failure, in which it is related to stimulation by low arterial blood pressure acting through baroreceptors. Hyponatraemia also occurs in the syndrome of inappropriate antidiuretic hormone secretion, usually from neoplasms releasing vasopressin. The conventional treatment of hyponatraemia used to be fluid restriction and treatment of the underlying disorder. This kind of treatment has been unreliable, cumbersome and difficult to comply with for the patient. In the future, effective vasopressin V2 antagonists will become available for clinical use in the treatment of hyponatraemia, and are expected to improve the management of hyponatraemia. Pharmacological characteristics and observations of biological effects of three antagonists are reported in the present article.

Impact of the endothelin system on water and sodium excretion in patients with liver cirrhosis

BACKGROUND

Impaired renal function in patients with liver cirrhosis is a serious complication and is characterized by sodium and water retention in the absence of identifiable specific causes of renal dysfunction. The endothelin system has been shown to be activated in liver cirrhosis and might contribute to impaired renal function. However, the mechanisms leading to an activation of the endothelin system in these patients and the effects of an activated endothelin system on renal function in these patients are as yet unknown.

METHODS

To determine the correlation between the activity of the endothelin system and the ability to excrete water and sodium in patients with liver cirrhosis, we measured plasma endothelin-1 concentrations by reversed phase-HPLC followed by an endothelin RIA and performed an oral water load tests in 10 healthy control subjects and 43 patients with liver cirrhosis. In addition, we analysed possible mechanisms/factors like plasma endotoxin that might contribute to the activation of the endothelin system in liver cirrhosis.

RESULTS

This study showed that the endothelin system is activated in patients with liver cirrhosis in a disease-stage-dependent manner. Patients with Child C liver cirrhosis have a 5.45-fold increased plasma ET-1 concentration compared to healthy controls, whereas plasma ET-1 is only increased 2.74-fold in Child A patients. An oral water load test revealed a highly significant (P < 0.0001) inverse correlation between the plasma endothelin-1 concentrations and the ability to excrete a given water load. Plasma endotoxin, a well-known stimulus of ET-1, is significantly (P < 0.03) correlated with plasma ET-1 in cirrhotic patients. The ET-1 concentrations in the ascites of patients with liver cirrhosis were lower and not related to plasma ET-1.

CONCLUSION

The activity of the endothelin system in patients with liver cirrhosis depends on the severity of liver impairment. Plasma endotoxin might be an important stimulus of the endothelin system in liver cirrhosis. We observed a highly significant inverse correlation between the plasma endothelin-1 concentrations and the ability to excrete a given water and sodium load, suggesting that the endothelin system plays a role in the regulation of water excretion in patients with liver cirrhosis.

Risk of degenerative ankle joint disease in volleyball players: study of former elite athletes

To estimate the influence of long-term, high-intensity volleyball playing on premature osteoarthritis (OA) of the ankle joint, we examined a group of 22 former elite volleyball-players age (34 +/- 6 yrs.) who had played for at least 3 years in the highest volleyball league in Switzerland, and 19 normal healthy untrained controls (35 +/- 6 yrs.). Volleyball-athletes had played during an average of 5.5 (+/- 2) h/wk for 8.5 (+/- 3) yrs. Twenty of the 22 players had suffered from at least one ankle sprain (average: 3.5), 10 had had ruptures of the lateral ligaments (8 of them operated). Four players had severe mechanical instability, 5 a talar varus tilt in the stress X-ray of more than 8 degrees. Subchondral sclerosis and osteophytes were more prevalent in volleyballers than in controls (p < 0.001), while the difference in joint space was not significant. No severe grades of OA could be observed in these former elite volleyball players. Yet, a radiologic score of degenerative ankle disease was elevated in 19/22 of them, but only in 2/19 controls (p<0.001). In multiple regression analysis among athletes, the anterior drawer sign and a feeling of instability were the only significant and independent predictors of an increased radiological index (p = 0.003 and p = 0.02, respectively) from an initial set of 9 variables covering career length and intensity as volleyball player, clinical signs of ankle instability and age. Even if in the present study, athletes had clearly more radiologic findings than controls--such as spur formation and subchondral sclerosis--long-term, high-intensity volleyball playing alone could not be confirmed as an independent risk factor for OA of the ankle joint however, a combination of chronic lateral ankle instability with intensive volleyball playing could marginally increase the risk of ankle OA.

Immune response to influenza vaccination in a large healthy elderly population

Elderly individuals not only demonstrate a greater risk of morbidity and mortality from influenza than the young, but also have greater difficulty mounting a protective response to influenza vaccine. The mechanism of the decreased efficacy of influenza vaccination in the elderly is not well understood. The present study was designed to assess the interaction between cell-mediated and humoral immune responses to influenza vaccine in a large population (n = 233) of healthy elderly individuals (mean age = 80.7) living in six continuing care retirement communities (CCRCs). While influenza vaccination resulted in significant increases in the mean anti-influenza antibody titres and mean proliferative responses of peripheral blood mononuclear cells to purified subvirion trivalent influenza vaccine one month after vaccination, only 48.9% and 30.0% of subjects had intact humoral and cell-mediated immune responses, respectively. No association was observed between intact cell-mediated and humoral responses: 14.7% of subjects had an intact cell-mediated, but not humoral response, and 32.6% of subjects had an intact humoral, but not cell-mediated response. However, IFNgamma production was significantly correlated with both antibody and cell-mediated responses to influenza vaccination, a finding not previously reported in the elderly. These results indicate that there is considerable heterogeneity among immune responses of the elderly to influenza vaccination. This heterogeneity needs to be a major consideration in evaluation of new vaccine preparations.