Distribution of neurotensin-like immunoreactivity in rat and cat area postrema

The distribution of neurotensin-like immunoreactive (NT-LI) fibers and cell bodies in the area postrema (AP) of rat and cat, utilizing the peroxidase, antiperoxidase (PAP) technique, is described. In the rat, the greatest accumulation of NT-LI fibers were present along the borders of the AP, while there were very few NT-LI fibers in central regions. In the cat, scattered NT-LI fibers occupied the majority of the central AP, while moderate numbers of NT-LI fibers were present at the ventromedial border. In more rostral cat AP levels, the number of NT-LI fibers decreased. NT-LI somata were present in rat AP, but were lacking in cat AP. The localization of NT within the AP suggests that the cardiovascular and gastric effects attributed to NT may be mediated, in part, through the AP.     

Single "early" action potential cause by Ni2+ ions in true pacemaker cells of the sinoatrial ring of the dace heart

Single "early" action potentials (AP) or "early" postdepolarization (EAD) were recorded in multicellular stripes working in the regimen of true pacemaker cells located in the basis of the sinoatrial valve of the dace (Leuciscus rutilus) heart after Ni2+ (0.3 mM) were added to superfused solution on the 15 th min. The standard microelectrode technique was used. The appearance of single EAD was preceded by increase of AP spike duration almost 1.5-fold due to increase of the duration of a final repolarization phase and of diastolic depolarization. EADs appeared at different levels of repolarization from -20 to -60 mV. EAD's amplitude was lower than the AP proper. The effect is reversible. Nifedipine (2 microM) decreased by 20% the AP duration to 50% repolarization in the cells of atrial type. In case the stripes were primarily subjected to nifedipine effect and then even after a long procedure of washout, the Ni2+ (0.3 mM) did not cause EADs. The hypothesis has been tested of what is the main reason of single EAD appearance in pacemaker cells under the effect of Ni2+; it is either blocking Ca release from the cell by Ni2+, or reactivation of L-type Ca-channels' conductivity. The analysis of the data obtained leads to the conclusion that 30-50% Na-Ca-exchangers block is the basic reason of single EAD appearance in pacemaker cells.     

Numerical sensitivity modeling for the detection of skin tumors by using tetrapolar probe

The measurement of electrical impedance of skin using surface electrodes permits the assessment of changes in local properties of the skin and can be used in the detection of tumors. The sensitivity of this technique depends mainly on the geometry of the probe and the size of the tumor. In this article, the impedance method was used to estimate the sensitivity of a tetrapolar probe in detecting small regions of increased conductivity in a stratified model of human skin. The impedance method was used to model the potential distribution using fasorial analysis to solve the node equations of the equivalent circuit. Interpolation was applied to reduce discretization error. The skin was modeled as a three-layer structure with different conductivity and permittivity obtained from the literature. A tumor was modeled as a small volume with admittivity four times higher than the normal tissue. Sensitivity calculation was made as a function of electrode diameter and separation, tumor size, and excitation frequency. The simulations indicated that by inserting a one square millimeter tumor in the epidermis, the load impedance to the current source varies about 1% while the transfer impedance varied 8%. The sensitivity also increases nonlinearly with increasing tumor area and thickness. Additionally, it was found that the sensitivity of the transfer impedance has a maximum value when the electrodes are separated by 1.8 mm. The results show that transfer impedance measurements of the skin may detect small skin tumors with a reasonable sensitivity by using an appropriate tetrapolar probe.     

Numerical sensitivity modeling for the detection of skin tumors by using tetrapolar probe

The measurement of electrical impedance of skin using surface electrodes permits the assessment of changes in local properties of the skin and can be used in the detection of tumors. The sensitivity of this technique depends mainly on the geometry of the probe and the size of the tumor. In this article, the impedance method was used to estimate the sensitivity of a tetrapolar probe in detecting small regions of increased conductivity in a stratified model of human skin. The impedance method was used to model the potential distribution using fasorial analysis to solve the node equations of the equivalent circuit. Interpolation was applied to reduce discretization error. The skin was modeled as a three-layer structure with different conductivity and permittivity obtained from the literature. A tumor was modeled as a small volume with admittivity four times higher than the normal tissue. Sensitivity calculation was made as a function of electrode diameter and separation, tumor size, and excitation frequency. The simulations indicated that by inserting a one square millimeter tumor in the epidermis, the load impedance to the current source varies about 1% while the transfer impedance varied 8%. The sensitivity also increases nonlinearly with increasing tumor area and thickness. Additionally, it was found that the sensitivity of the transfer impedance has a maximum value when the electrodes are separated by 1.8?mm. The results show that transfer impedance measurements of the skin may detect small skin tumors with a reasonable sensitivity by using an appropriate tetrapolar probe.     

The functional importance of <Emphasis Type="Italic">Acropora austera</Emphasis> as nursery areas for juvenile reef fish on South African coral reefs

Many coral reef fish species use mangrove and seagrass beds as nursery areas. However, in certain regions, the absence or scarcity of such habitats suggests that juvenile coral reef fish may be seeking refuge elsewhere. The underlying biogenic substratum of most coral reefs is structurally complex and provides many types of refuge. However, on young or subtropical coral reefs, species may be more reliant on the living coral layer as nursery areas. Such is the case on the high-latitude coral reefs of South Africa where the coral communities consist of a thin veneer of coral overlaying late Pleistocene bedrock. Thus, the morphology of coral species may be a major determinant in the availability of refuge space. Acropora austera is a branching species that forms large patches with high structural complexity. Associated with these patches is a diverse community of fish species, particularly juveniles. Over the past decade, several large (>100 m²) A. austera patches at Sodwana Bay have been diminishing for unknown reasons and there is little evidence of their replacement or regrowth. Seven patches of A. austera (AP) and non-A. austera (NAP) were selected and monitored for 12 months using visual surveys to investigate the importance of AP as refugia and nursery areas. There were significant differences in fish communities between AP and NAP habitats. In total, 110 species were recorded within the patches compared to 101 species outside the patches. Labrids and pomacentrids were the dominant species in the AP habitats, while juvenile scarids, acanthurids, chaetodons and serranids were also abundant. The diversity and abundance of fish species increased significantly with AP size. As the most structurally complex coral species on the reefs, the loss of APs may have significant implications for the recruitment and survival of certain fish species.     

High lateral mobility of endogenous and transfected alkaline phosphatase: a phosphatidylinositol-anchored membrane protein

The lateral mobility of alkaline phosphatase (AP) in the plasma membrane of osteoblastic and nonosteoblastic cells was estimated by fluorescence redistribution after photobleaching in embryonic and in tumor cells, in cells that express AP naturally, and in cells transfected with an expression vector containing AP cDNA. The diffusion coefficient (D) and the mobile fraction, estimated from the percent recovery (%R), were found to be cell-type dependent ranging from (0.58 +/- 0.16) X 10(-9) cm2s-1 and 73.3 +/- 10.5 in rat osteosarcoma cells ROS 17/2.8 to (1.77 +/- 0.51) X 10(-9) cm2s-1 and 82.8 +/- 2.5 in rat osteosarcoma cells UMR106. Similar values of D greater than or equal to 10(-9) cm2s-1 with approximately 80% recovery were also found in fetal rat calvaria cells, transfected skin fibroblasts, and transfected AP-negative osteosarcoma cells ROS 25/1. These values of D are many times greater than "typical" values for membrane proteins, coming close to those of membrane lipid in fetal rat calvaria and ROS 17/2.8 cells (D = [4(-5)] X 10(-9) cm2s-1 with 75-80% recovery), estimated with the hexadecanoyl aminofluorescein probe. In all cell types, phosphatidylinositol (PI)-specific phospholipase C released 60-90% of native and transfection-expressed AP, demonstrating that, as in other tissue types, AP in these cells is anchored in the membrane via a linkage to PI. These results indicate that the transfected cells used in this study possess the machinery for AP insertion into the membrane and its binding to PI. The fast AP mobility appears to be an intrinsic property of the way the protein is anchored in the membrane, a conclusion with general implications for the understanding of the slow diffusion of other membrane proteins.     

Immunohistochemical localization of epidermal growth factor in rat and man

Epidermal growth factor (EGF) is a peptide which stimulates cell mitotic activity and differentiation, has a cytoprotective effect on the gastroduodenal mucosa, and inhibits gastric acid secretion. The immunohistochemical localization of EGF in the Brunner's glands and the submandibular glands is well documented. The localization of EGF in other tissues is still unclarified. In the present study, the immunohistochemical localization of EGF in tissues from rat, man and a 20 week human fetus were investigated. In man and rat, immunoreaction was found in the submandibular glands, the serous glands of the nasal cavity, Brunner's glands of the duodenum, the Paneth cells of the small intestine, and the tubular cells of the kidney. In the fetus EGF was found in the kidney and in the intestinal Paneth cells. Antisera raised against rat submandibular EGF did not recognize EGF in human tissues, whereas antisera against human urinary EGF worked in rat as well as man. EGF was found only in cells with an exocrine function.     

Correlations between the endothelium-dependent relaxation of the aorta and arterial pressure in rats with myocardial infarction

The effect of experimental myocardial infarction on endothelium-dependent relaxation was studied on isolated rat aorta and compared with the dynamics of arterial pressure (AP). It was shown that the endothelium-dependent relaxation of aorta was increased 1.8 times 3 h following the myocardial infarction. Simultaneously the drop in AP which had begun immediately following the experimental infarction became maximal. In 24 h both the indices were restored practically to the initial level. There was a significant negative correlation between the extent of endothelium-dependent relaxation and AP. It was suggested that the increase in endothelium-dependent relaxation could influence vascular tone, the drop in AP, and, finally, the development of cardiogenic shock in myocardial infarction in man.     

Immunohistochemical localization of epidermal growth factor in rat and man

Summary Epidermal growth factor (EGF) is a peptide which stimulates cell mitotic activity and differentiation, has a cytoprotective effect on the gastroduodenal mucosa, and inhibits gastric acid secretion.The immunohistochemical localization of EGF in the Brunner's glands and the submandibular glands is well documented. The localization of EGF in other tissues is still unclarified.In the present study, the immunohistochemical localization of EGF in tissues from rat, man and a 20 week human fetus were investigated. In man and rat, immunoreaction was found in the submandibular glands, the serous glands of the nasal cavity, Brunner's glands of the duodenum, the Paneth cells of the small intestine, and the tubular cells of the kidney. In the fetus EGF was found in the kidney and in the intestinal Paneth cells.Antisera raised against rat submandibular EGF did not recognize EGF in human tissues, whereas antisera against human urinary EGF worked in rat as well as man. EGF was found only in cells with an exocrine function.     

"Blood-contacting neurons" in the brain of the Japanese eel Anguilla japonica

To discriminate "blood-contacting neurons" within the brain of the eel, Evans blue (EB) was injected intraperitoneally. After five days, six brain areas were externally stained blue with the dye; the saccus dorsalis (SD), the epiphysis (E), the area postrema (AP), the posterior part of the magnocellular preoptic nucleus (PM), the pituitary (Pit), and the saccus vasculosus (SV). Among the EB-positive area, some cells in the PM, the anterior tuberal nucleus (NAT) and the AP were discriminated as the "blood-contacting neurons" histologically, whereas EB-positive neurons were not detected in the SD, the E, the Pit and the SV regions. In the PM, most EB-positive neurons (90 %) were immunoreactive to vasotocin (AVT) antibody, indicating that these neurons are vasotocinergic. The remaining EB-positive neurons (10 %) were not immunoreactive to ANG II and tyrosine hydroxylase (TH) antibodies. Although some neurons in the PM were immunoreactive to ANG II antibody, they were EB-negative. In contrast, almost all EB-positive neurons in the AP showed TH-like immunoreactivity (-lir), indicating that these neurons utilize catecholamine(s) as a neurotransmitter. The EB-positive neurons in the NAT were not immunoreactive to AVT, ANG II and TH antibodies, whereas some neurons without EB-staining showed ANG II-lir. Possible roles of these neurons in regulating drinking behavior in eels are discussed.     

Thirty-five years of progress in the study of MSH

In this paper, initial work on MSH at Dr. Lerner's laboratory in Portland, Oregon, from 1952 to 1954 is presented. The development of an in vitro bioassay method enabled us to show increased urinary excretion of MSH in Addison's disease. The ability of MSH to increase skin pigmentation in man was also demonstrated. Subsequent work on MSH during the past thirty years is reviewed, such as characterization of alpha- and beta-MSH and their precursors in the pituitary gland and localization of MSH-like peptides in various regions of the brain. Finally there are presented the characterization of gamma-MSH, the hypothermic effect of intracisternal administration of gamma-MSH, the effect of corticortropin releasing factor on increased secretion of alpha-MSH from rat pituitary, and the effect of arginine vasopressin on secretion of alpha-MSH from pituitary adenoma.     

Groundwater and surface water hydrology of a small groundwater-fed fen

The hydrology of a small quaking fen was investigated by measuring all components of the water budget. Water-level measurements indicated that the fen is a focus for groundwater discharge, and that there is a lateral (subsurface) flow from the fen toward surrounding areas during most of the year. The hydrology, however, is strongly influenced by man, as water tables are maintained during dry periods by pumping water into the area. This action results in a reversal of flow patterns as surface water from a ditch infiltrates the fen and groundwater recharge occurs.Two approaches for calculation of groundwater and surface water terms were compared. The two procedures differ in the way that vertical and horizontal hydraulic conductivity of the soil is calculated. Hydraulic conductivity estimated from in situ tube experiments was one to two orders of magnitude lower than hydraulic conductivity estimates from numerical water budget analyses.Four one-month periods were selected for calculations of complete water budgets. Results of calculations of water flow were compared in respect to the overall error in the water budget (calculated as percent difference between inputs and outputs). Water budgets calculated from data on hydraulic conductivity gave high residual errors (56.% ± 16.3%). When hydraulic conductivity was derived from numerical analyses, the errors were very small (2.8% ± 3.1%) and the difference between inputs and outputs over a period of 127 days was only 2.6 mm (0.45%).     

Variability of alkaline phosphatase activity in diploid human cells in vitro

Experiments were made with 19 strains obtained from different tissues (skin, lungs, muscles) of 8-10-week-old medical abortions and skin biopsies of healthy donors to study the manifestations of alkaline phosphatase (AP) activity in human diploid cells in vitro. Based on the data obtained it is concluded that AP activity is marked by demonstrable intra- and interstrain variability. The spectrum of "AP activity" trait variability is broader for transformed cells than for human diploid cells.     

Intragenic deletion in the Desmoglein 4 gene underlies the skin phenotype in the Iffa Credo "hairless" rat

The Iffa Credo (IC) "hairless" rat is an autosomal recessive hypotrichotic animal model actively used in pharmacological and dermatological studies. Although the molecular basis of the IC rat phenotype was never defined, the designation "hr/hr" (hairless) has been used for this rat mutation. Despite the observation that IC rats share many phenotypic similarities with Charles River (CR) 'hairless rats', crossbreeding between CR and IC rats indicated that these mutations are not allelic, and moreover, genetic analysis of both CR and IC hairless mutant rats showed no mutations in the hr gene. Here, we present a detailed analysis of the skin phenotype in the IC rat. While the initial stages of hair follicle (HF) morphogenesis reveal no significant abnormalities, the subsequent processes of inner root sheath and hair shaft formation are severely disturbed due to impaired proliferation in the hair matrix and abnormal differentiation in the precortex zone. This results in significant reduction of hair bulb volume, and the formation of dysmorphic "blebbed" hair shafts lacking medullar structure and resembling "lanceolate" hairs. Based on the presence of lance-head hairs typical of rodent lanceolate mutants, we performed molecular analysis of the desmoglein 4 gene and found a large intragenic deletion encompassing nine exons of the gene. This finding, together with specific morphological features of skin and hairs, confirms that the IC rat is allelic with the lanceolate hair (lah) mutations in mice and rats. Our results elucidate the genetic and morphological basis of the IC rat mutation, thus providing a new model to study molecular mechanisms of hair growth control.     

A new gas lesion syndrome in man, induced by "isobaric gas counterdiffusion".

Normal men have been found to develop pruritis and gas bubble lesions in the skin, and disruption of vestibular function, when breathing nitrogen or neon with oxygen while surrounded by helium at increased ambient pressure. This phenomenon, which occurs at stable ambient pressures, at 1 or many ATA, has been designated the "isobaric gas counterdiffusion syndrome." In a series of analyses and experiments in vivo and in vitro the cause of the syndrome has been established as due to gas accumulation and development of gas bubbles in tissues as a result of differences in selective diffusivities, for various respired and ambient gases, in the tissue substances between capillary blood and the surrounding atmosphere. The phenomenon here described in man is an initial stage of a process shown later in animals to progress to continuous, massive, lethal, intravascular gas embolization.     

玛河流域扇缘带盐穗木土壤速效养分的"肥岛"特征

比较了玛河流域扇缘带盐穗木灌丛在单生条件下及与猪毛菜共生条件下的土壤速效养分的"肥岛"特征。结果表明,盐穗木灌丛周围土壤的"肥岛"现象主要体现在土壤表层,沿立地点向外每隔0.6m逐渐减弱,且沿土层深度增加逐渐减弱。盐穗木在单生条件下,灌丛土壤碱解氮和速效钾在立地中心有明显的富集现象。在从立地原点向外3m的表层土壤中,两种养分分别从 2.75 g/kg和56.67 mg/kg下降至1.66 g/kg和29.0 mg/kg,且沿土壤剖面向下呈现显著性降低趋势(P<0.05),但均显著性高于裸地的同类值。而速效磷含量整体呈现亏损状态,其平均值较裸地速效磷含量低25.33%,表明盐穗木种群具有促进氮和钾的富积、但消耗磷的生态功能。在盐穗木-猪毛菜共生条件下,无论是在土壤表层还是沿土壤剖面,3种速效养分的含量整体上显著性高于裸地。共生条件下土壤的碱解氮含量整体低于单生条件下的值,而速效磷和速效钾的含量则是共生大于单生。研究表明,盐穗木单一种群条件下土壤速效磷的亏损状态可在猪毛菜共生条件下出现逆转,两者具有互补效应。该结论为干旱盐碱化地区植物与土壤关系研究提供了新的理论潜力。     

Dynamic changes in nitric oxide and mitochondrial oxidative stress with site-dependent differential tissue response during anoxic preconditioning in rat heart

In this study, dynamic changes in nitric oxide (NO) and mitochondrial superoxide (O(2)(*-)) were examined during anoxic preconditioning (AP) in rat heart model. AP and anoxia-reoxygenation (A/R) were performed on isolated hearts and single cardiomyocytes. The cellular insult in the form of infarct size and DNA damage were localized and correlated with NO synthases (endothelial and inducible) expression levels. The results showed that endocardium was the most affected region in AP groups, whereas the larger area of infarct was confined to mid- and epicardium in the A/R group. Interestingly, a high-level expression of immunofluorescent NO synthases was restricted to viable areas in the AP. In contrast to the gradual increase in O(2)(*-) level that occurred in the AP group, a sudden massive increase in its level was demonstrated at the onset of reoxygenation in the A/R group. The observed increase in NO production during reoxygenation in the AP group was attenuated by inducible NO synthase inhibitor. The study revealed, on a real-time basis, the role played by preconditioning for modulating NO and O(2)(*-) levels on behalf of cell survival. The results afford a better understanding of cardiac-adapting mechanism during AP and the role of inducible NO synthase in this important phenomenon.     

The "intermediate component" of the radiosodium efflux from frog skeletal muscle

The influence of diversity in the size of the cells of the frog's sartorius on the radiosodium efflux from the muscle was investigated. Morphometric analyses of light micrographs of complete cross sections of the muscle were done in the proximal and distal regions. The results were used to predict the shape of the radiosodium washout curve under the following assumptions: the cells differ in size and shape, but each has a single internal pool of exchangeable sodium; the sodium exchange properties of the limiting membranes are the same for all cells; and the diversity of the true areas of the limiting membranes is reflected by the diversity of the apparent areas measured at the light microscopic level. Radiosodium efflux measurements were performed on similar muscles. The model correctly predicted the occurrence of a continuous decline of the fractional loss of radiosodium, which was not due to diffusional delay and which would be interpreted as a second internal compartment in a compartmental analysis, and an effect of short versus long isotope loading intervals on the efflux. It was concluded that the existence of cell size diversity satisfactorily explains the flux data. No "special region" must be postulated.