Caspase-14 protects against epidermal UVB photodamage and water loss.

Caspase-14 belongs to a conserved family of aspartate-specific proteinases. Its expression is restricted almost exclusively to the suprabasal layers of the epidermis and the hair follicles. Moreover, the proteolytic activation of caspase-14 is associated with stratum corneum formation, implicating caspase-14 in terminal keratinocyte differentiation and cornification. Here, we show that the skin of caspase-14-deficient mice was shiny and lichenified, indicating an altered stratum-corneum composition. Caspase-14-deficient epidermis contained significantly more alveolar keratohyalin F-granules, the profilaggrin stores. Accordingly, caspase-14-deficient epidermis is characterized by an altered profilaggrin processing pattern and we show that recombinant caspase-14 can directly cleave profilaggrin in vitro. Caspase-14-deficient epidermis is characterized by reduced skin-hydration levels and increased water loss. In view of the important role of filaggrin in the structure and moisturization of the skin, the knockout phenotype could be explained by an aberrant processing of filaggrin. Importantly, the skin of caspase-14-deficient mice was highly sensitive to the formation of cyclobutane pyrimidine dimers after UVB irradiation, leading to increased levels of UVB-induced apoptosis. Removal of the stratum corneum indicate that caspase-14 controls the UVB scavenging capacity of the stratum corneum.

Cellular basis of growth suppression by submergence in azuki bean epicotyls.

BACKGROUND AND AIMS: Complete submergence severely reduces growth rate and productivity of terrestrial plants, but much remains to be elucidated regarding the mechanisms involved. The aim of this study was to clarify the cellular basis of growth suppression by submergence in stems. METHODS: The effects of submergence on the viscoelastic extensibility of the cell wall and the cellular osmotic concentration were studied in azuki bean epicotyls. Modifications by submergence to chemical properties of the cell wall; levels of osmotic solutes and their translocation from the seed to epicotyls; and apoplastic pH and levels of ATP and ethanol were also examined. These cellular events underwater were compared in etiolated and in light-grown seedlings. KEY RESULTS: Under submergence, the osmotic concentration of the cell sap was substantially decreased via decreased concentrations of organic compounds including sugars and amino acids. In contrast, the viscoelastic extensibility of the cell wall was kept high. Submergence also decreased ATP and increased the pH of the apoplastic solution. Alcoholic fermentation was stimulated underwater, but the resulting accumulated ethanol was not directly involved in growth suppression. Light partially relieved the inhibitory effects of submergence on growth, osmoregulation and sugar translocation. CONCLUSIONS: A decrease in the levels of osmotic solutes is a main cause of underwater growth suppression in azuki bean epicotyls. This may be brought about by suppression of solute uptake via breakdown of the H(+) gradient across the plasma membrane due to a decrease in ATP. The involvement of cell wall properties in underwater growth suppression remains to be fully elucidated.

[Study of the systemic-organ blood circulation in acute period of the multiple trauma based on water-electrolytic metabolism and its correction with EHF-therapy].

In the present paper the new approach to study of relationships of system blood circulation and its correction with the help of effect of EHF-therapy on the organism of person is offered. The method is based on the study of dynamic indexes of water-electrolytic metabolism, cell structure of a blood, ECG, REG, computer-aided tomography of the brain. The correlation between cell structure of blood, ionic structure and dynamic indexes of water-electrolytic metabolism is found out. Some parameters, factor of solubility of oxygen, parameters of a common water of organism were designed.

Stiffening effects of riboflavin/UVA corneal collagen cross-linking is hydration dependent.

The collagen cross-linking is a relatively new treatment option for strengthening the cornea, delaying, and in some cases stopping the progression of keratoconus. The uniaxial tensile experiments are among the most commonly used techniques to assess the effectiveness of this therapeutic option in enhancing tensile properties. In the present study, we investigated the possible effects of hydration on stiffening effects of corneal collagen cross-linking procedure, as measured by the uniaxial tensile testing method. For this purpose, after cross-linking bovine corneas, we let the strips to dehydrate in air or swell in a solution until their thickness reached an average thickness of 0.5, 0.7, 0.9, 1.1, and 1.5 mm. Using thickness as a representative of hydration, we divided corneal strips into five different groups and measured their stress-strain behavior by conducting uniaxial tensile experiments in mineral oil. It was observed that the collagen cross-linking treatment and hydration together affect the tensile behavior of the bovine cornea. While corneal collagen cross-linking resulted in a significant increase in the tensile stress-strain response of each thickness group (P<0.01), less hydrated collagen cross-linked samples showed a significantly stiffer response (P<0.01). A master curve was found for representing the tensile behavior of the collagen cross-linked bovine cornea at different levels of hydration. The results of the present research confirmed that the amount of mechanical stiffening of the corneal collagen cross-linking, as measured by uniaxial tensile testing, strongly depends on the hydration. Therefore, it is concluded that uniaxial tensile experiments could only be used to assess stiffening effects of the collagen cross-linking treatment if the hydration of specimens is fully controlled.

Pathophysiological aspects of malignant brain tumors studied with positron emission tomography.

To further understand the control of brain tumor fluid balance and pH, the following studies were undertaken. The transport of a water soluble molecule across the brain and tumor capillary endothelium was studied during glucocorticoid and radiation treatment. The brain and brain-tumor acidity (pH) was evaluated as a single measurement in patients receiving a low maintenance dose of glucocorticoid. Transport changes and pH were measured in 61 patients with cerebral tumors using 82Rubidium (82Rb) and 11C-Dimethyloxa-zolidindione (11C-DMO), respectively, and Positron Emission Tomography (PET). Supplementary studies of tumor and contralateral brain blood flow and blood volume using the C15O2/PET and C15O/PET technique, respectively, were included to validate the 82Rb/PET model and obtain further information. A total of 125 PET scans were performed. Supplementary studies were undertaken to estimate delay of blood registration and form distribution of arterial blood isotope activity curves. Blood-to-tumor barrier transport was outlined at baseline and at 6 and 24 hours after the start of glucocorticoid treatment, finding a significant decrease in the transport. Radiation treatment (2-6 gray) did not alter the blood-to-tumor barrier transport when restudied within one hour in patients receiving glucocorticoid. In accordance with others, we observed pH values in gray and white matter in the range of 6.74-7.09 and 6.77-7.03 respectively. The pH in brain tumors was as high as 6.88-7.26, suggesting that tumors are more alkalotic than the normal brain. The permeability surface area product and the permeability coefficient were determined from the 82Rb/PET transport and C15O2/PET flow studies. Baseline permeability values were comparable to the literature values both for 82Rb and potassium. No difference in tissue blood volume was seen between 82Rb/PET and C15O/PET models and was of the same magnitude in the tumor and the contralateral tissue. The pH and fluid control in human brain tumors are perceived as metabolically controlled rather than, as previously believed, a result of simple passive exchange of alkalotic or osmotic active molecules between plasma and tumor interstitial space. Aspects of tumor alkalosis, tumor edema production, glucocorticoid edema clearance, and relationship between the anti-edema effect of glucocorticoid and the shown transport changes to 82Rb will be reviewed in the light of metabolic control mechanisms.

Hypertension after bilateral kidney irradiation in young and adult rats.

The mechanism of a rise in blood pressure after kidney irradiation is unclear but most likely of renal origin. We have investigated the role of the renin-angiotensin system and dietary salt restriction in the development of systolic hypertension after bilateral kidney irradiation in young and adult rats. Three to 12 months after a single X-ray dose of 7.5 or 12.5 Gy to both kidneys of young and adult rats, the systolic blood pressure (SBP) and plasma renin concentration (PRC) were measured regularly. A single X-ray dose of 12.5 Gy caused a moderate rise in SBP and a slight reduction in PRC in both young and adult rats. A dose of 7.5 Gy did not significantly alter the SBP or PRC during the follow-up period of 1 year. In a second experiment, the kidneys of young rats received an X-ray dose of 20 Gy. Subsequently, rats were kept on a standard diet (110 mmol sodium/kg) or a sodium-poor diet (10 mmol sodium/kg). On both diets, SBP started to rise rapidly 3 months after kidney irradiation. Sodium balance studies carried out at that time revealed an increased sodium retention in the irradiated rats compared to controls on the same diet. In rats on a low sodium intake, there was neither a delay nor an alleviation in the development of hypertension. Compared to controls, the PRC tended to be lower in irradiated rats up to 4 months after irradiation. Subsequently, malignant hypertension developed in all 20 Gy rats, resulting in pressure natriuresis, stimulating the renin-angiotensin system. Our findings indicated that hypertension after bilateral kidney irradiation was not primarily the result of an activation of the renin-angiotensin system. Although there were some indications that sodium retention played a role, dietary sodium restriction did not influence the development of hypertension.

Bile loss in the acute intestinal radiation syndrome in rats.

The effects of bile duct ligation (BDL), choledochostomy, bile acid sequestering within the intestinal lumen by cholestyramine, and fluid and electrolyte replacement on survival time and development of diarrhea after whole-body exposure to doses of ionizing radiation that result in death from acute intestinal injury were studied. BDL significantly prolonged survival and delayed the onset of diarrhea after exposure to 137Cs gamma rays, fission neutrons, or cyclotron-produced neutrons in the range of doses that produce intestinal death or death from a combination of intestinal and hematopoietic injuries. Cannulation of the bile duct with exteriorized bile flow (choledochostomy) to protect the irradiated intestine from the mucolytic action of bile salts did not duplicate the effect of BDL in increasing survival time. Choledochostomy without fluid replacement eliminated the occurrence of diarrhea in 15.4 Gy irradiated rats. Diarrhea did occur in irradiated animals with choledochostomy if they received duodenal injections of fluid and electrolytes to replace the fluid lost as a result of bile drainage. Duodenal injection of fluid and electrolytes, however, had no significant effect on survival time in irradiated rats. In contrast, injection of fluid and electrolytes into the peritoneal cavity of irradiated rats resulted in an increase in survival time that was comparable to that observed after BDL. Addition of antibiotics to the peritoneally injected fluid and electrolytes further increased survival time (up to 9 days). This survival time approached that seen in animals receiving the same radiation dose but which had the intestine exteriorized and shielded to minimize radiation injury to the intestine. Postmortem histological examinations of the irradiated small intestine showed mucosal regeneration in these long-term survivors receiving fluid and antibiotic therapy. In contrast, duodenal injection of cholestyramine post irradiation to bind bile acids had no effect on survival time or diarrhea incidence. The conclusions from these experiments are that BDL prolongs survival and postpones the onset of diarrhea in irradiated rats dying from acute intestinal injury primarily by slowing down the loss of fluid and electrolytes and that bile acids play no significant role.

Fluid and sodium loss in whole-body-irradiated rats.

Whole-body and organ fluid compartment sizes and plasma sodium concentrations were measured in conventional, GI decontaminated, bile duct ligated, and choledochostomized rats at different times after various doses of gamma radiation. In addition, sodium excretion was measured in rats receiving lethal intestinal radiation injury. After doses which were sublethal for 3-5 day intestinal death, transient decreases occurred in all the fluid compartments measured (i.e., total body water, extracellular fluid space, plasma volume). No recovery of these fluid compartments was observed in rats destined to die from intestinal radiation injury. The magnitude of the decreases in fluid compartment sizes was dose dependent and correlated temporally with the breakdown and recovery of the intestinal mucosa but was independent of the presence or absence of enteric bacteria or bile acids. Associated with the loss of fluid was an excess excretion of 0.83 meq of sodium between 48 and 84 h postirradiation. This represents approximately 60% of the sodium lost from the extracellular fluid space in these animals during this time. The remaining extracellular sodium loss was due to redistribution of sodium to other spaces. It is concluded that radiation-induced breakdown of the intestinal mucosa results in lethal losses of fluid and sodium as evidenced by significant decreases in total body water, extracellular fluid space, plasma volume, and plasma sodium concentration, with hemoconcentration. These changes are sufficient to reduce tissue perfusion leading to irreversible hypovolemic shock and death.

Impact of ultraviolet-B radiation on planktonic fish larvae: alteration of the osmoregulatory function.

Coastal marine ecosystems are submitted to variations of several abiotic and biotic parameters, some of them related to global change. Among them the ultraviolet-B (UV-B) radiation (UVBR: 280-320 nm) may strongly impact planktonic fish larvae. The consequences of an increase of UVBR on the osmoregulatory function of Dicentrarchus labrax larvae have been investigated in this study. In young larvae of D. labrax, as in other teleosts, osmoregulation depends on tegumentary ion transporting cells, or ionocytes, mainly located on the skin of the trunk and of the yolk sac. As early D. labrax larvae passively drift in the top water column, ionocytes are exposed to solar radiation. The effect of UVBR on larval osmoregulation in seawater was evaluated through nanoosmometric measurements of the blood osmolality after exposure to different UV-B treatments. A loss of osmoregulatory capability occured in larvae after 2 days of low (50 µWcm(-2): 4 h L/20 h D) and medium (80 µWcm(-2): 4 h L/20 h D) UVBR exposure. Compared to control larvae kept in the darkness, a significant increase in blood osmolality, abnormal behavior and high mortalities were detected in larvae exposed to UVBR from 2 days on. At the cellular level, an important decrease in abundance of tegumentary ionocytes and mucous cells was observed after 2 days of exposure to UVBR. In the ionocytes, two major osmoeffectors were immunolocalized, the Na+/K(+)-ATPase and the Na+/K+/2Cl- cotransporter. Compared to controls, the fluorescent immunostaining was lower in UVBR-exposed larvae. We hypothesize that the impaired osmoregulation in UVBR-exposed larvae originates from the lower number of tegumentary ionocytes and mucous cells. This alteration of the osmoregulatory function could negatively impact the survival of young larvae at the surface water exposed to UVBR.

Role of electro-osmosis in the impedance response of microchannel-nanochannel interfaces.

The influence of net fluid flow on the low-frequency ac response of a microchannel-nanochannel interface under dc bias is studied theoretically using a simple 1D model based on the Poisson-Nernst-Planck-Stokes equations. The model describes cross-sectional averaged transport wherein the electro-osmotic flow is controlled by the magnitude of the dc bias and captures essential features of the problem related to the micro-nano interface, specifically geometric focusing effects and nanochannel control of the net fluid flow. This model predicts behavior which differs from that predicted by a purely electrodiffusive formulation. The high-frequency edge of the Warburg branch of the complex impedance plot has a slope which deviates from the π/4 Warburg value, decreasing with increasing bias, and there are corresponding changes in the overall phase as seen in the Bode plots. This can be attributed to a streaming contribution to the capacitive reactance of the device as well an increase in the conductance of the depleted region, both due to net fluid flow. The increase in conductance, corresponding to reduced interfacial depletion, also permits dc currents above the classical electrodiffusive limit.

Study of damage to red blood cells exposed to different doses of γ-ray irradiation.

BACKGROUND: The aims of this research were to study alterations in the ultrastructure of red blood cells, the changes in concentrations of plasma electrolytes and the killing effect of lymphocytes in samples of blood exposed to different doses of γ-ray irradiation. MATERIALS AND METHODS: Blood samples were treated with different doses of γ-ray irradiation and then preserved for different periods. Specimens were prepared for standard electron microscopy and transmission electron microscopy. At the same time, changes in the concentrations of Na(+), K(+) and Cl(-) and pH values in the plasma as well as Fas and FasL expression of lymphocytes before and after irradiation were determined. RESULTS: The proportions of reversibly and irreversibly transformed cells, for example, echinocytes, sphero-echinocytes, and degenerated forms, increased with increasing doses of irradiation and storage period, while the number of discocyte shaped red blood cells decreased. The change in K(+) concentration was greater than that of Na+ or Cl(-) after irradiation and was dosage-dependent. Plasma pH was influenced by different doses of radiation and storage time. After exposure to (137)Cs γ-irradiation, the expression of both Fas and FasL in lymphocytes differed significantly from that in the control group: the expression was positively correlated with irradiation dose (r=0.95, 0.96), but no significant difference in the Fas/FasL ratio was observed (P>0.05). DISCUSSION: We conclude that the ultrastructure of red blood cells is not changed obviously by irradiation with some doses of γ-rays and various periods of storage. However, irradiation does have some dose-dependent and time-dependent adverse effects on the erythrocytes.

Swelling-activated pathways in human T-lymphocytes studied by cell volumetry and electrorotation.

Small organic solutes, including sugar derivatives, amino acids, etc., contribute significantly to the osmoregulation of mammalian cells. The present study explores the mechanisms of swelling-activated membrane permeability for electrolytes and neutral carbohydrates in Jurkat cells. Electrorotation was used to analyze the relationship between the hypotonically induced changes in the electrically accessible surface area of the plasma membrane (probed by the capacitance) and its permeability to the monomeric sugar alcohol sorbitol, the disaccharide trehalose, and electrolyte. Time-resolved capacitance and volumetric measurements were performed in parallel using media of different osmolalities containing either sorbitol or trehalose as the major solute. Under mild hypotonic stress in 200 mOsm sorbitol or trehalose solutions, the cells accomplished regulatory volume decrease by releasing cytosolic electrolytes presumably through pathways activated by the swelling-mediated retraction of microvilli. This is suggested by a rapid decrease of the area-specific membrane capacitance C(m) (microF/cm2). The cell membrane was impermeable to both carbohydrates in 200 mOsm media. Whereas trehalose permeability remained also very poor in 100 mOsm medium, extreme swelling of cells in a strongly hypotonic solution (100 mOsm) led to a dramatic increase in sorbitol permeability as evidenced by regulatory volume decrease inhibition. The different osmotic thresholds for activation of electrolyte release and sorbitol influx suggest the involvement of separate swelling-activated pathways. Whereas the electrolyte efflux seemed to utilize pathways preexisting in the plasma membrane, putative sorbitol channels might be inserted into the membrane from cytosolic vesicles via swelling-mediated exocytosis, as indicated by a substantial increase in the whole-cell capacitance C(C) (pF) in strongly hypotonic solutions.

Effects of low intensity infrared laser radiation on the water transport in the isolated toad urinary bladder.

BACKGROUND AND OBJECTIVES: The aim of this work was to study the effects of low intensity laser radiation on water transport in the toad bladder in vitro. STUDY DESIGN/MATERIALS AND METHODS: The water flow through the membrane was measured gravimetrically in bag preparations of the membrane. RESULTS: Laser radiation did not alter the water transport in the presence nor in the absence of vasopressin. In contrast, when the hemibladders were previously treated with vasopressin, the laser decreased by approximately 33.70% arginine-vasopressin (AVP)-mediated water transport. Laser radiation increased 3'5'-cyclic adenosine monophosphate (3'5'-cAMP) mediated water transport by approximately 23%. The association of laser radiation with indomethacin (IND) did not affect AVP-mediated water transport. CONCLUSIONS: This data suggests that the laser may have two effects on AVP-mediated water transport: one inhibitory effect on 3'5'-cAMP synthesis by inhibiting the adenylate cyclase complex and another stimulatory effect by inhibiting nucleotide-phosphodiesterase activity. Our results also indicate that the laser does not interfere in the prostaglandins biosynthesis induced by AVP.