Pesticides and pharmaceuticals data collected during two consecutive years in a Mediterranean micro-estuary

The Alexander micro-estuary, located at the eastern edge of the Mediterranean Sea, is a typical example of small water bodies that suffer from a combination of urban and agricultural pollution, and overuse of its natural water sources. It is∼6.5 km long, with maximum depth of 3 m and maximum width of 45 m. To evaluate the anthropogenic stress on the system and its ability to mitigate pollution, water samples were collected within the framework of Ruppin's Estuarine and Coastal Observatory [1]. Water samples were collected from the estuary head, which drains about 510 km2, and at a point 300 m upstream from the estuary mouth before water flows into the Mediterranean Sea. A total of 236 stormwater and 44 base-flow water samples between December 2016 and December 2018. Stormwater samples were collected every 0.25 - 4 h along the entire course of the flow events using an automated samplers (Sigma 900, Hach Company, Loveland CO, USA; and ISCO 3700 Full-Size Portable Sampler, Teledyne, Lincoln, NE, USA). Base-flow samples were taken once a month using a horizontal grab sampler (5 L, model 110B, OceanTest Equipment, Fort Lauderdale, FL, USA). All samples were filtered using 90mmGF/F filters (nominal pore size of 0.7 µm, MGF, Sartorius, Göttingen, Germany) and immediately frozen (-20°C) before chemical analysis. Chemical analysis was performed using liquid chromatography with high-resolution mass spectrometry (LC-HRMS) analysis using a QExactive Plus hybrid FT mass spectrometer coupled with a Dionex Ultimate 3000 RS UPLC (Thermo Fisher Scientific, Waltham, MA, USA). The targeted analysis, which included 15 fungicides, 25 herbicides, 18 Insecticides, and 19 pharmaceuticals, concluded with a total of 21,142 entries. All entries are organized in a worksheet, along with location, date, flood section duration, discharge rate, and the total water volume discharged during the relevant period. The provided data offers an opportunity to explore the sources, transport, and impact of a large mixture of organic pollutants in a confined aquatic system located in an urbanized coastal environment.

Environmental risk dynamics of pesticides toxicity in a Mediterranean micro-estuary

Pesticides are potentially toxic to aquatic systems, even at low concentration, depending on their individual ecotoxicological properties and their mixture composition. Thus, to evaluate possible ecological stress due to pesticide load, a thorough assessment of the potential toxicity of pesticide mixtures is required. Here we report water discharge and quality data of an eastern Mediterranean micro-estuary (Alexander stream), targeting the temporal distribution of a pesticide mixture. Over 150 water samples were collected during 2 hydrological years representing base-flow and flood conditions. On average, each water sample contained 34 and 45 different pesticides with peak concentrations of 1.4 μg L^-1 of Imidacloprid and 55 μg L^-1 of Diuron during base-flow and flood events, respectively. Pesticide mixtures were potentially toxic to benthic invertebrates and algae during flood events, surpassing the toxicity benchmark with medians of 110% and 155%, respectively. The herbicide Diuron and the insecticide Imidacloprid were the main pesticides responsible for the high potential toxicity during flood events. The falling limb of the flood hydrographs was found to inflict the highest stress on the estuarine environment due to elevated toxicity combined with prolonged residence time of the water. Examination of the potential chronic toxicity of single compounds showed continuous stress for plants, algae, amphibians, crustaceans, insects and fish from nine pesticides. Our data show that the ecosystem of the Alexander micro-estuary is under a continuous chronic stress with acute peaks in potential toxicity during flood events and the period that follows them. We propose that analyzing a small set of flood-tail samples is needed for the evaluation of small estuarine ecosystems risk during the rainy season. From a management perspective, we suggest better control of application practices for Diuron in the watershed to minimize the stress to the estuarine ecosystem.

Transformation of lamotrigine by white-rot fungus Pleurotus ostreatus

One of the most persistent pharmaceutical compounds commonly found in treated wastewater is lamotrigine (LTG). It has also been detected in soils and crops irrigated with treated wastewater. Here we focused on the ability of the white-rot edible mushroom Pleurotus ostreatus to remove and transform LTG in liquid cultures. At concentrations of environmental relevance (1 and 10 μg L^-1) LTG was almost completely removed from the culture medium within 20 days. To elucidate the mechanism of LTG removal and transformation, we applied a physiological-based approach using inhibitors and a competing agent. These experiments were conducted at a higher concentration for metabolites detection. Based on identification of sulfur-containing metabolites and LTG N2-oxide and the effect of specific inhibitors, cytochrome P450 oxidation is suggested as one of the reaction mechanisms leading to LTG transformation. The variety and number of transformation products (i.e., conjugates) found in the current study were larger than reported in mammals. Moreover, known conjugates with glucuronide, glutathione, or cysteine/glycine, were not found in our system. Since the majority of the identified transformation products were conjugates of LTG, this study highlights the persistence of LTG as an organic pollutant in ecosystems exposed to wastewater.

Optimized small-molecule pull-downs define MLBP1 as an acyl-lipid-binding protein

Abscisic acid (ABA) receptors belong to the START domain superfamily, which encompasses ligand-binding proteins present in all kingdoms of life. START domain proteins contain a central binding pocket that, depending on the protein, can couple ligand binding to catalytic, transport or signaling functions. In Arabidopsis, the best characterized START domain proteins are the 14 PYR/PYL/RCAR ABA receptors, while the other members of the superfamily do not have assigned ligands. To address this, we used affinity purification of biotinylated proteins expressed transiently in Nicotiana benthamiana coupled to untargeted LC-MS to identify candidate binding ligands. We optimized this method using ABA-PYL interactions and show that ABA co-purifies with wild-type PYL5 but not a binding site mutant. The K_d of PYL5 for ABA is 1.1 μm, which suggests that the method has sufficient sensitivity for many ligand-protein interactions. Using this method, we surveyed a set of 37 START domain-related proteins, which resulted in the identification of ligands that co-purified with MLBP1 (At4G01883) or MLP165 (At1G35260). Metabolite identification and the use of authentic standards revealed that MLBP1 binds to monolinolenin, which we confirmed using recombinant MLBP1. Monolinolenin also co-purified with MLBP1 purified from transgenic Arabidopsis, demonstrating that the interaction occurs in a native context. Thus, deployment of this relatively simple method allowed us to define a protein-metabolite interaction and better understand protein-ligand interactions in plants.

The Goldilocks effect of respiration on canavanine tolerance in Saccharomyces cerevisiae

When glucose is available, Saccharomyces cerevisiae prefers fermentation to respiration. In fact, it can live without respiration at all. Here, we study the role of respiration in stress tolerance in yeast. We found that colony growth of respiratory-deficient yeast (petite) is greatly inhibited by canavanine, the toxic analog of arginine that causes proteotoxic stress. We found lower amounts of the amino acids involved in arginine biosynthesis in petites compared with WT. This finding may be explained by the fact that petite cells exposed to canavanine show reduction in the efficiency of targeting of proteins required for arginine biosynthesis. The retrograde (RTG) pathway signals mitochondrial stress. It positively controls production of arginine precursors. We show that canavanine abrogates RTG signaling especially in petite cells, and mutants in the RTG pathway are extremely sensitive to canavanine. We suggest that petite cells are naturally ineffective in production of some amino acids; combination of this fact with the effect of canavanine on the RTG pathway is the simplest explanation why petite cells are inhibited by canavanine. Surprisingly, we found that canavanine greatly inhibits colony formation when WT cells are forced to respire. Our research proposes a novel connection between respiration and proteotoxic stress.

Carryover Effects of Acute DEHP Exposure on Ovarian Function and Oocyte Developmental Competence in Lactating Cows

We examined acute exposure of Holstein cows to di(2-ethylhexyl) phthalate (DEHP) and its carryover effects on ovarian function and oocyte developmental competence. Synchronized cows were tube-fed with water or 100 mg/kg DEHP per day for 3 days. Blood, urine and milk samples were collected before, during and after DEHP exposure to examine its clearance pattern. Ovarian follicular dynamics was monitored through an entire estrous cycle by ultrasonographic scanning. Follicular fluids were aspirated from the preovulatory follicles on days 0 and 29 of the experiment and analyzed for phthalate metabolites and estradiol concentration. The aspirated follicular fluid was used as maturation medium for in-vitro embryo production. Findings revealed that DEHP impairs the pattern of follicular development, with a prominent effect on dominant follicles. The diameter and growth rate of the first- and second-wave dominant follicles were lower (P < 0.05) in the DEHP-treated group. Estradiol concentration in the follicular fluid was lower in the DEHP-treated group than in controls, and associated with a higher number of follicular pathologies (follicle diameter >25 mm). The pattern of growth and regression of the corpus luteum differed between groups, with a lower volume in the DEHP-treated group (P < 0.05). The follicular fluid aspirated from the DEHP-treated group, but not the controls, contained 23 nM mono(2-ethylhexyl) phthalate. Culturing of cumulus oocyte complexes in the follicular fluid aspirated from DEHP-treated cows reduced the proportion of oocytes progressing to the MII stage, and the proportions of 2- to 4-cell-stage embryos (P < 0.04) and 7-day blastocysts (P < 0.06). The results describe the risk associated with acute exposure to DEHP and its deleterious carryover effects on ovarian function, nuclear maturation and oocyte developmental competence.

Co-existence of clonal expanded autologous and transplacental-acquired maternal T cells in recombination activating gene-deficient severe combined immunodeficiency

It is commonly accepted that the presence of high amounts of maternal T cells excludes Omenn syndrome (OS) in severe combined immunodeficiency (SCID). We report a SCID patient with a novel mutation in the recombination activating gene (RAG)1 gene (4-BP DEL.1406 TTGC) who presented with immunodeficiency and OS. Several assays, including representatives of specific T cell receptors (TCR), Vβ families and TCR-γ rearrangements, were performed in order to understand more clearly the nature and origin of the patient's T cells. The patient had oligoclonal T cells which, based on the patient-mother human leucocyte antigen (HLA)-B50 mismatch, were either autologous or of maternal origin. These cell populations were different in their numbers of regulatory T cells (T(reg)) and the diversity of TCR repertoires. This is the first description of the co-existence of large amounts of clonal expanded autologous and transplacental-acquired maternal T cells in RAG1-deficient SCID.

Mechanochemically enhanced degradation of pyrene and phenanthrene loaded on magnetite

The enhancement of the degradation of polycyclic aromatic hydrocarbons (PAHs), exemplified by pyrene and phenanthrene, using mild grinding in the presence of common minerals was investigated. Magnetite, birnessite, and Na- and Cu-montmorillonite samples were loaded with pyrene or phenanthrene and ground manually or in a ball mill for short periods of time. The ground samples were analyzed for PAHs and for their metabolites, using high-performance liquid chromatography and liquid chromatography-mass spectrometry. No degradation of pyrene occurred when it was in contact with Na-montmorillonite or birnessite. Sorption of pyrene on Cu-montmorillonite enhanced its degradation, but grinding of the loaded clay actually inhibited pyrene's degradation. Phenanthrene hardly degraded on Cu-montmorillonite. Grinding magnetite loaded with either PAH resulted in a significant degradation of both (∼50% after grinding for 5 min), while in the nonground samples, negligible degradation was detected. The extent of degradation increased with the duration of grinding. The degradation of either PAH loaded on magnetite yielded oxidized products. In soil samples contaminated with PAHs and mixed with magnetite, a similar grinding-induced degradation pattern was observed, but with a lower rate. A liquid phase was required to initiate degradation in the soil. The liquid phase apparently served as the medium through which the pollutants reached the surface of the degradation-enhancing mineral.

Effect of CMV infection and high temperatures on the enzymes involved in raffinose family oligosaccharide biosynthesis in melon plants

Ultrastructural and molecular studies have provided experimental evidence for the classification of cucurbits as symplastic loaders, mainly translocating the raffinose family oligosaccharides (RFOs) raffinose and stachyose. Earlier studies established that cucumber mosaic virus (CMV) infection causes a significant increase in the sucrose-to-RFO ratio in the phloem sap of melon plants. The alteration in phloem sap sugar composition was associated with upregulation of CmSUT1 transcript within the vascular bundles. The current research aimed to explore the effect of CMV infection on the enzymes involved in symplastic phloem loading and RFO biosynthesis. Viral infection did not affect the activity of either raffinose or stachyose synthases in source leaves, but caused upregulation of the respective transcripts. Interestingly, activity of galactinol synthase was higher in CMV-infected leaves, associated with upregulation of CmGAS2. A significant increase in CmGAS2 expression in source leaves of melon plants exposed to high temperatures indicated that this response is common for both biotic and abiotic stresses. However, the effect of CMV or heat stress on phloem sap sugar composition is not due to alteration in RFO biosynthesis.

Amelioration of diabesity-induced colorectal ontogenesis by omega-3 fatty acids in mice

Postnatal intestinal ontogenesis in an animal model of diabesity may recapitulate morphological and transduction features of diabesity-induced intestinal dysplasia and its amelioration by endogenous (n-3) polyunsaturated fatty acids (PUFA). Proliferation, differentiation, and transduction aspects of intestinal ontogenesis have been studied here in obese, insulin-resistant db/db mice, in fat-1 transgene coding for desaturation of (n-6) PUFA into (n-3) PUFA, in db/db crossed with fat-1 mice, and in control mice. Diabesity resulted in increased colonic proliferation and dedifferentiation of epithelial colonocytes and goblet cells, with increased colonic β-catenin and hepatocyte nuclear factor (HNF)-4α transcriptional activities accompanied by enrichment in HNF-4α-bound (n-6) PUFA. In contrast, in fat-1 mice, colonic proliferation was restrained, accompanied by differentiation of crypt stem cells into epithelial colonocytes and goblet cells and by decrease in colonic β-catenin and HNF-4α transcriptional activities, with concomitant enrichment in HNF-4α-bound (n-3) PUFA at the expense of (n-6) PUFA. Colonic proliferation and differentiation, the profile of β-catenin and HNF-4α-responsive genes, and the composition of HNF-4α-bound PUFA of db/db mice reverted to wild-type by introducing the fat-1 gene into the db/db context. Suppression of intestinal HNF-4α activity by (n-3) PUFA may ameliorate diabesity-induced intestinal ontogenesis and offer an effective preventive modality for colorectal cancer.

Quorum-sensing quenching by rhizobacterial volatiles

We show that volatile organic compounds (VOCs) produced by rhizospheric strains Pseudomonas fluorescens B-4117 and Serratia plymuthica IC1270 may act as inhibitors of the cell-cell communication quorum-sensing (QS) network mediated by N-acyl homoserine lactone (AHL) signal molecules produced by various bacteria, including strains of Agrobacterium, Chromobacterium, Pectobacterium and Pseudomonas. This quorum-quenching effect was observed when AHL-producing bacteria were treated with VOCs emitted by strains B-4117 and IC1270 or with dimethyl disulfide (DMDS), the major volatile produced by strain IC1270. LC-MS/MS analysis revealed that treatment of strains Pseudomonas chlororaphis 449, Pseudomonas aeruginosa PAO1 or Ps. fluorescens 2-79 with VOCs emitted by strain IC1270 or DMDS drastically decreases the amount of AHLs produced by these bacteria. Volatile organic compounds produced by Ps. chlororaphis 449 were able to suppress its own QS-induction activity, suggesting a negative interaction between VOCs and AHL molecules in the same strain. Quantitative RT-PCR analysis showed that treatment of Ps. chlororaphis 449 with VOCs emitted by cells of IC1270, B-4117 or 449 itself, or with DMDS, leads to significant suppression of transcription of AHL synthase genes phzI and csaI. Thus, along with AHLs, bacterial volatiles might be considered another type of signal molecule involved in microbial communication in the rhizosphere.

Transformation of the recalcitrant pharmaceutical compound carbamazepine by Pleurotus ostreatus: role of cytochrome P450 monooxygenase and manganese peroxidase

Carbamazepine (CBZ) is an environmentally recalcitrant compound highly stable in soil and during wastewater treatment. In this study, we examined the mechanisms by which the white-rot fungus Pleurotus ostreatus metabolizes CBZ in liquid culture using a physiological approach. P. ostreatus PC9 was grown in media known to support different levels of a multiplicity of enzyme systems such as cytochrome P450 (CYP450) and manganese peroxidase (MnP). When both CYP450 and MnP systems were active, 99% of the added CBZ was eliminated from the solution and transformed to 10,11-epoxycarbamazepine. High removal of CBZ was also obtained when either MnP or CYP450 was active. When both CYP450 and MnP were inactivated, only 10 to 30% of the added CBZ was removed. In this latter system, removal of CBZ might be partially attributed to the activity of versatile peroxidase. P. ostreatus was able to eliminate CBZ in liquid culture even when CBZ was added at an environmentally relevant concentration (1 μg L(-1)). On the basis of our study, we suggest that two families of enzymes are involved in the oxidation of CBZ in liquid culture: MnP in a Mn(2+)-dependent or independent manner and CYP450. Our study also highlights the potential of using P. ostreatus for bioremediation systems.

Uptake of carbamazepine by cucumber plants--a case study related to irrigation with reclaimed wastewater

Reclaimed wastewater is an important source of irrigation in semiarid and arid zones. Here we report data on carbamazepine (CBZ) uptake by cucumber plants in hydroponic culture and greenhouse experiments using different soil types irrigated with fresh water or reclaimed wastewater. Data obtained from the hydroponic culture experiments suggest that CBZ is mainly translocated by water mass flow, and thus it is concentrated and accumulated to the largest extent in the mature/older leaves. Carbamazepine concentration in cucumber fruits and leaves was negatively correlated with soil organic matter content. The concentrations of CBZ in the roots and stems were relatively low, and most CBZ in the plant (76-84% of total uptake) was detected in the leaves. A greenhouse experiment using fresh water and reclaimed wastewater spiked, or not, with CBZ at 1 μg L(-1) (typical concentration in effluents) revealed that CBZ can be taken up and bioaccumulated from its background concentration in reclaimed wastewater. Bioaccumulation factor (calculated as the ratio of CBZ concentration in the plant to that in the soil solution) for the fruits (0.8-1) was significantly lower than the value calculated for the leaves (17-20). This study emphasizes the potential uptake of active pharmaceutical compounds by crops in organic-matter-poor soils irrigated with reclaimed wastewater and highlights the potential risks associated with this agricultural practice.

Contactless respiratory and heart rate monitoring: validation of an innovative tool

PRIMARY OBJECTIVE

To assess the accuracy of the EverOn™ piezoelectric sensor based contactless heart rate and respiration rate monitoring system.

METHODS

Measurements of the EverOn™ and reference devices were performed in a sleep lab and an intensive care unit (ICU) setting. One minute measurements by both the reference device and the EverOn™ were averaged and compared. Accuracy was defined in accordance with industry criteria.

RESULTS

Respiration rate (RR) accuracy in the 41 children and 16 adults evaluated in the sleep lab was 93.1% and 90.6% respectively, and heart rate (HR) accuracy was 94.4% and 91.5% respectively. For the 42 ICU patients RR accuracy was 82.0% and 75% (versus end-tidal CO(2) and manual respectively), while accuracy of HR was 94.0%. The EverOn™ was found to be superior to the impedance technique in measuring RR.

CONCLUSIONS

The system described was found to be accurate in accordance with regulatory and industry criteria.

Sorption and mobility of pharmaceutical compounds in soil irrigated with reclaimed wastewater

Use of reclaimed wastewater for irrigation is an important route for the introduction of pharmaceutical compounds (PCs) into the environment. In this study, the mobility and sorption-desorption behavior of carbamazepine, naproxen and diclofenac were studied in soil layers sampled from a plot irrigated with secondary-treated wastewater (STWW). Carbamazepine and diclofenac were significantly retarded in the 0-5 cm soil sample rich in soil organic matter (SOM): carbamazepine was not affected by the water quality (freshwater versus STWW), whereas diclofenac exhibited a higher retardation factor (RF) in the freshwater system. Naproxen exhibited significantly lower RFs than diclofenac but with a similar trend - higher retardation in the freshwater versus STWW system. In the 5-15 cm soil sample containing low SOM, naproxen was highly mobile while carbamazepine and diclofenac were still retarded. In the 15-25 cm sample, all compounds exhibited their lowest RFs. Sorption data suggested that SOM governs the studied PCs' interactions with the soil samples. However, higher carbon-normalized sorption coefficients were measured for the PCs in the 15-25 cm sample, suggesting that both quantity and the physicochemical nature of SOM affect sorption interactions. While both naproxen and carbamazepine exhibited reversible sorption isotherms, diclofenac exhibited pronounced sorption-desorption hysteresis. This study suggests that carbamazepine and diclofenac can be classified as slow-mobile compounds in SOM-rich soil layers. When these compounds pass this layer and/or introduced into SOM-poor soils, their mobility increases significantly. This emphasizes the potential transport of PCs to groundwater in semiarid zones due to intensive irrigation with reclaimed wastewater in SOM-poor soils.

Priming of antimicrobial phenolics during induced resistance response towards Pectobacterium carotovorum in the ornamental monocot calla lily

Calla lilies are herbaceous monocotyledonous plants that are highly sensitive to Pectobacterium carotovorum, the causal agent of soft-rot disease. Results demonstrate that, in response to elicitation using plant defense activators, the calla lily produces elevated levels of antimicrobial phenolics and that these compounds contribute to increased resistance against P. carotovorum, as shown by reduced bacterial proliferation in elicited leaves. The polyphenolic nature of the induced compounds was supported by autofluorescence, absorbance spectra, and reaction with Folin-Ciocalteu reagent. Two plant defense activators, Bion and methyl jasmonate, differed in both their capacity to induce accumulation of polyphenols and their resistance against the pathogen. Methyl jasmonate elicitation brought about higher accumulation of free phenolics relative to Bion, suggesting priming of bioactive polyphenols as a principal factor in the calla lily defense against P. carotovorum. To further characterize the nature of induced compounds, two major compounds were collected and identified as swertisin and isovitexin by mass and nuclear magnetic resonance spectroscopies.

Preparative separation of isomeric and stereoisomeric dicarboxylic acids by pH-zone-refining counter-current chromatography

This work involves the preparative separation of some isomeric dicarboxylic acids using pH-zone-refining counter-current chromatography (CCC), a relatively new preparative technique for the separation of ionizable compounds. The paper concentrates especially on the separation of a synthetic mixture of closely related cis and trans pairs of 1-methyl- and 1,3-dimethyl-1,3-cyclohexanedicarboxylic acids. The elution sequence of the isomers is discussed in terms of their relative acidities (pK(a) values) in solution and gas phase, hydrophobicities, and steric configuration. Two possible explanations are suggested for the mechanism of separation. They both involve the amount of retainer acid used, as it affects the separation and plays a role in the chemohydrodynamic equilibrium of the dicarboxylic acids in the column.

Postoperative brain stem tension pneumocephalus causing transient locked-in syndrome

The incidence of pneumocephalus after supratentorial craniotomy has been reported to be as high as 100%. However, transformation of postoperative pneumocephalus into tension pneumocephalus (symptomatic intracranial air) is a rather rare phenomenon. Tension pneumocephalus after posterior fossa surgery is reported mainly when the surgery is performed in a sitting position. We hereby report on a patient who developed brain-stem tension pneumocephalus in the early postoperative period after posterior fossa craniotomy for an exophytic brainstem astrocytoma, operated in the prone position. A complete locked-in syndrome resolved following surgical relief of the trapped air.

Hydrogen-shift isomerism: mass spectrometry of isomeric benzenesulfonate and 2-, 3- and 4-dehydrobenzenesulfonic acid anions in the gas phase

The isomeric 3- and 4-dehydrobenzenesulfonic acid anions b and c were prepared by collision induced dissociation (CID) of the [M - H](-) ions of isomeric sulfobenzoic acids obtained by negative electrospray ionization (ESI). The CID spectra (MS(3)) of anions b and c are different from each other, and both are different from that of the isomeric benzenesulfonate anion a, obtained from benzenesulfonic acid. The stability of ions b and c shows that 1,2-proton transfer does not take place in this system under the conditions of the CID experiment. Density functional (DFT) calculations at B3LYP/6-31+G(2d,p) level of theory show that benzenesulfonate anion a is the most stable isomer, and the energies of isomers b and c are higher by more than 65 kcal mol(-1). The calculated energies of the transition states involved in the 1,2-hydrogen migration leading to the interconversion of the isomeric anions are very high (>120 kcal mol(-1)relative to ion a, barrier energies >55 kcal mol(-1)), much higher than those of transition structures leading to fragmentation. This situation does not allow isomerization of ions b and c to a, under the conditions of the CID experiments. The isomeric 2-dehydrobenzenesulfonic acid anion isomerizes to the benzenesulfonate anion a by a facile proton transfer from the SO(3)H group to the adjacent position 2. The results of this work indicate that the gas phase deprotonation of meta- and para-sulfobenzoic acids is a kinetically controlled process.

Blood transfusion practice indicated by paediatric intensive care specialists in response to four clinical scenarios

OBJECTIVE

Several clinical guidelines exist for blood transfusion in adults but only one refers to children. There are no guidelines for blood transfusion in critically ill children and the paediatric intensive care specialist's approach is unknown. We wished to evaluate the approach toward blood transfusion among a group of paediatric intensive care specialists.

METHODS

All certified paediatric intensive care specialists from the Israeli society of pediatric intensive care medicine were requested to complete a questionnaire, which described four hypothetical common scenarios in paediatric intensive care units. In each case, the physicians were asked to denote the haemoglobin threshold at which they would prescribe a blood transfusion and the transfusion volume they would use. The specialists were also asked for their reasons for increasing their haemoglobin threshold for blood transfusion.

RESULTS

The questionnaire was posted to twenty six paediatric intensive care specialists, twenty one of whom responded (i.e. 80.8%). There was a wide variation for each scenario in both the suggested haemoglobin thresholds for transfusion (varying by 20-50 g/L) and the transfusion volume (varying by 10-20 mL/kg). The reasons given for increasing their blood transfusion threshold included, in order of importance, shock, haemodynamic instability and hypoxaemia.

CONCLUSIONS

There is a marked variability among paediatric intensive care specialists regarding both the threshold haemoglobin level at which blood transfusion is prescribed as well as the volume used.

Mediastinal tumors in children: a single institution experience

Mediastinal masses in children are a heterogeneous group of asymptomatic or potentially life-threatening congenital, infectious, or neoplastic lesions that present complex diagnostic and therapeutic dilemmas. Some patients are asymptomatic; in others, the mass may compress mediastinal structures and cause sudden asphyxia. In these cases, close cooperation is needed among pediatric surgeons, anesthesiologists, intensivists, oncologists, and radiologists. The files of 45 children with mediastinal masses admitted between 1986 and 1999 to the Pediatric Intensive Care Unit (PICU) of Schneider Children's Medical Center of Israel were reviewed. Twenty-one were admitted for perioperative care, and 21 for emergency care, including 19 with respiratory distress. Five of the emergency care group had asphyxia and 10 needed assisted ventilation. Two children were admitted for evaluation and 1 for leukopheresis. The children admitted on an emergency basis had more clinical findings than the postoperative group: almost 80% had dyspnea and more than 45% had oxygen desaturation; 33% had cough and noisy breathing, and 25%, superior vena cava syndrome or hepatosplenomegaly. Eight patients (17.8%) had benign disease and 37 (82.2%) malignant disease. The patients with a benign mass were significantly younger than the patients with a malignant mass (p<0.005); in 5 cases (12.5%), a congenital anomaly presented as a mediastinal mass. Most of the malignant masses were of hematologic origin (40.5%), followed by neurogenic tumors (27%). Twenty-seven patients underwent surgery, including 6 emergency procedures (3 partial resections, 2 biopsies, 1 lymph node biopsy). There were no intraoperative or postoperative deaths. The present series emphasizes the complex care children with a mediastinal mass require. They should be treated in a tertiary center with a multidisciplinary approach.

Acute diaphragmatic paralysis caused by chest-tube trauma to phrenic nerve

A 3 1/2-year-old child developed unilateral diaphragmatic paralysis after chest drain insertion. Plain chest X-ray demonstrated paravertebral positioning of the chest-tube tip, and magnetic resonance imaging revealed hematomas in the region of the chest-tube tip and the phrenic nerve fibers. The trauma to the phrenic nerve was apparently secondary to malposition of the chest tube. This is a rare complication and has been reported mainly in neonates. Radiologists should notify the treating physicians that the correct position of a chest drain tip is at least 2 cm distant from the vertebrae.

Benign occipital epilepsy mimicking a catastrophic intracranial event

OBJECTIVE

To describe the rare, dramatic, presentation of benign occipital epilepsy.

METHODS

We describe three children who presented to the pediatric emergency department from 1992 to 1996 with a clinical picture of catastrophic intracranial event.

RESULTS

The main signs and symptoms were loss of consciousness in all patients, apnea in two, hemiclonus in two, general hypertonicity in two, eye deviation in two, fixed dilated pupils in one, and decorticate rigidity in two. All underwent emergency intubation, brain scan, and lumbar puncture, and all were treated with antibiotics, in addition to antiviral drugs in two. Two patients were also treated for suspected increased intracranial pressure. Two patients recovered within a few hours and one within 24 hours of admission without any residual neurologic deficit. Electroencephalograms, done within 48 hours after the event, revealed the classic pattern of occipital epilepsy in two patients and bilateral occipital slow wave in one. A 3- to 5-year clinical and electroencephalographic follow-up supported the diagnosis.

CONCLUSION

Benign occipital epilepsy in children can mimic a catastrophic intracranial event. Electroencephalography, performed early in the Pediatric Intensive Care Unit, may avoid or shorten unnecessary and aggressive treatments such as hyperventilation, diuretic agents, and prolonged antiviral therapy.

Accidental busulfan overdose: enhanced drug clearance with hemodialysis in a child with Wiskott-Aldrich syndrome

A 4.6 kg infant with Wiskott-Aldrich syndrome received an accidental overdose of busulfan during preparation for allogeneic stem cell transplantation. Pharmacokinetic analysis of plasma busulfan levels alerted staff to the dosing error. Hemodialysis was immediately performed and resulted in accelerated clearance of busulfan. There were no acute neurologic and hepatic side-effects of the busulfan overdose, and despite 2 months of cough accompanied by rales, the patient is now free of pulmonary symptoms. Stable partial donor chimerism occurred after transplantation. At present, the patient is thriving and infection-free 12 months after transplantation, although his platelet count remains at the lower limit of normal.

Yield of bronchoalveolar lavage in ventilated and non-ventilated children after bone marrow transplantation

A study was undertaken to retrospectively evaluate the yield of bronchoalveolar lavage (BAL) in a single-institution series of children after bone marrow transplantation (BMT) and to compare the yield of BAL between the ventilated and nonventilated patients. We reviewed charts of 52 consecutive children after BMT who underwent BAL. Thirty patients (41 BALs) were nonventilated (group 1) and 33 patients (45 BALs) were ventilated for respiratory failure (group 2). Eleven patients were included in both groups. BAL was performed a median of 255 and 28.5 days after BMT in groups 1 and 2, respectively (P < 0.001). Group 1:17 pathogens were isolated from 13 BALs; a single pathogen from 10 BALs. Group 2:15 pathogens were isolated from 14 BALs (31.1% positive). Viruses were isolated from 13 BALs in group 2. A severe complication of BAL occurred in only one patient from group 1 (1.1%). Open lung biopsies were performed in one patient in group 1 and eight patients in group 2. The histological findings correlated with the BAL findings in 66.7%. In conclusion, there was no difference in the yield of BAL between the groups. Therapy was changed in one third of the patients dictated by the BAL findings. The risk of severe complications was relatively low. A good correlation between open lung biopsy (OLB) and BAL was found.

Superantigens and cystic fibrosis: resistance of presenting cells to dexamethasone

Staphylococcus aureus, a common pulmonary pathogen in cystic fibrosis (CF), produces exotoxins that are extremely potent superantigens. A number of animal studies have shown that superantigens cause pulmonary inflammation, but the possible role of superantigens in CF has not been investigated. The present study assessed possible differences between control and CF B cells in presenting superantigens to T cells. Immortalized B-cell lines were used as superantigen-presenting cells to avoid environmental influences (e.g., infection or antibiotics) common to freshly isolated cells. The results show that CF B-cell lines presented a staphylococcal superantigen to the immortalized T-cell line (Jurkat) as effectively as did control B-cell lines as measured by interleukin-2 production. However, in contrast to the case for control B-cell lines, dexamethasone did not inhibit CF B-cell lines from presenting superantigen. The resistance of superantigen-presenting CF B cells to corticosteroids suggests that the pulmonary response to superantigens may be poorly regulated in CF, leading to an exaggerated inflammatory response to S. aureus.

Hemophagocytic lymphohistiocytic syndrome: Unrecognized cause of multiple organ failure

OBJECTIVE: To describe an often-unrecognized clinical picture of multiple organ failure in hemophagocytic lymphohistiocytic syndrome (HLS). DESIGN: Retrospective chart review. SETTING: A ten-bed pediatric intensive care unit (PICU) in a tertiary children's university hospital. PATIENTS: A total of 11 children (age, 5 months to 13 yrs) who fulfilled the criteria for the diagnosis of familial- or infectious-associated hemophagocytic lymphohistiocytosis and who required intensive care support for organ failure. INTERVENTION: None. MAIN RESULTS: During a 10-yr period, 5,439 children were hospitalized in our PICU. A total of 11 children were diagnosed as suffering with HLS. Of these 11 patients, three (27%) had the familial form and eight had the infectious-associated form. After admission to the PICU, seven patients (63%) were diagnosed as suffering with HLS and each had one or more organ failures (patients 3-7, 9, and 10). All presented with fever, hepatomegaly, and splenomegaly; in addition, all had at least two of the following: anemia, neutropenia, or thrombocytopenia. All 11 had lymphohistiocytic accumulation in bone marrow (n = 10), lymph node (n = 2), lung (n = 2), and/or liver (n = 1). Organ failure was noted most often in the respiratory system (n = 7) attributable to severe, acute respiratory distress syndrome and pleural effusion. Of the 11 patients, six had cardiovascular involvement that manifested as shock in three and as capillary leak syndrome in three. Renal failure occurred in four patients. Of these, two required hemodiafiltration and one required peritoneal dialysis. Liver failure occurred in three and central nervous system involvement and coma in three. Most of the patients required massive therapeutic intervention, including assisted ventilation (n = 6), inotropic support (n = 3), and hemofiltration (n = 3). A total of seven patients (63%) died. CONCLUSIONS: Hemophagocytic lymphohistiocytic syndrome in the pediatric population may have a dramatic clinical picture, with multiple organ failure as a presenting symptom or early in the disease course, mandating intensive support in the PICU.

Cytokine response during hyperoxia: sequential production of pulmonary tumor necrosis factor and interleukin-6 in neonatal rats

BACKGROUND

Exposure of newborn animals to high concentrations of oxygen leads to diffuse alveolar damage similar to that seen in bronchopulmonary dysplasia in human infants. Therefore, neonatal rats are a suitable practical model of hyperoxic lung damage in human infants.

OBJECTIVE

To determine the involvement of tumor necrosis factor-alpha and interleukin-6 in lung injury in neonatal rats exposed to 100% O2 concentration.

METHODS

A randomized controlled study was designed in which litters of term Sprague-Dawley rat pups were assigned to experimental or control groups. The pups in the experimental group were placed in 100% O2 from birth for 9 days, while the control pups were placed in room air. Twelve to 15 pups from each group were sacrificed on day 1, 3, 6, 9 and 13 after birth for bronchoalveolar lavage collection and lung histologic study. The bronchoalveolar lavage fluid was assayed for TNF alpha and IL-6.

RESULTS

Newborn rats exposed to 100% O2 for the first 9 days of life showed severe pulmonary edema and hypercellularity on days 1 and 3, which then improved to nearly complete resolution on days 6 and 9. Pulmonary TNF alpha was produced early on O2 exposure (day 3) and pulmonary IL-6 later (days 6 and 9).

CONCLUSIONS

Hyperoxia induces sequential production of pulmonary TNF alpha and IL-6, which corresponds to the severity of the pathological findings and the known inflammatory and anti-inflammatory role of these cytokines.

Open lung biopsy--successful diagnostic tool with therapeutic implication in the critically ill paediatric population

Open lung biopsy (OLB) is an important diagnostic tool in children with immune deficiency and/or chronic lung disease with diffuse pulmonary compromise. These patients require a tailored therapeutic approach owing to their fragile status and the side effects of unnecessary or inadequate treatment. Twenty-six patients of mean age 5.6 y underwent 41 open lung biopsies in our centre between 1991 and 1995. Seventeen (65%) were immunocompromised (including 13 with malignancy) and 9 had other lung diseases. The biopsies were diagnostic in 25 patients (96%), and complete clinical-pathological correlation was found in 11 (42%). A specific infectious aetiology was detected in nine patients (35%), all of them immunocompromised. Therapeutic changes were instituted on the basis of the biopsy findings in 18 patients (69%). Two patients had postoperative complications (prolonged pleural leak). We conclude that OLB is a safe diagnostic procedure even in the critically ill child and should be employed without hesitation when conventional methods fail to provide a definitive diagnosis to help redirect therapy.

Prolonged croup due to herpes simplex virus infection

Herpes simplex virus (HSV) is an uncommon cause of acute laryngitis in immunocompetent patients since it mostly occurs in immunocompromised subjects. We present two previously healthy children with prolonged gingivostomatitis and stridor (lasting 3 and 4 weeks) in whom HSV-1 was isolated from subglottal ulcers.

CONCLUSION

HSV should be considered a possible pathogen in cases of prolonged or atypical croup not only in immunocompromised or elderly patients but also in otherwise healthy children.

Interleukin-6 levels in serum and lung lavage fluid of children undergoing open heart surgery correlate with postoperative morbidity

OBJECTIVE

To evaluate the relationship of perioperative levels of interleukin 6 (IL-6) in serum and bronchoalveolar fluid with morbidity and mortality in children undergoing cardiopulmonary bypass (CPB).

DESIGN

Prospective, noninterventional study.

SETTING

Operating room and pediatric intensive care unit (PICU) of a university hospital.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

IL-6 levels were measured in serum and lung lavage fluid obtained before, during, and after CPB using the B9.9 bioassay. Alveolar epithelial lining fluid (AELF) volume was calculated using the urea correction method. Mean intraoperative AELF IL-6 levels increased fourfold compared to preoperative levels, and mean serum IL-6 levels increased fivefold after CPB. Mean intraoperative AELF IL-6 levels correlated with intraoperative blood transfusion (r2 = 0.18; p = 0.049) and duration of inotropic support (r2 = 0.29; p = 0.009), mechanical ventilation (r2 = 0.24; p = 0.019), and PICU stay (r2 = 0.29; p = 0.008). Mean serum IL-6 levels 2 h after CPB correlated with intraoperative blood transfusion (r2 = 0.3;p = 0.007), and with Pediatric Risk of Mortality score on postoperative day 3 (r2 = 0.24; p = 0.022), and were higher in patients with massive fluid retention (p = 0.014) and in nonsurvivors (p = 0.003).

CONCLUSIONS

Serum and alveolar IL-6 levels increase after CPB, and correlate with postoperative morbidity. Serum IL-6 levels also correlate with mortality. They may be useful in assessing the severity of the systemic inflammatory response after CPB.

Experimental use of raffinose as an osmotic agent for peritoneal dialysis

Conventional glucose-based solutions for peritoneal dialysis fluids have been shown to raise problems of biocompatibility. We therefore evaluated the ultrafiltration capabilities of raffinose as an alternative osmotic agent in a non-uremic rat model. Animals were divided into four groups and injected intraperitoneally with solutions containing raffinose (4.5%, 345 mOsm/kg; 16.7%, 518 mOsm/kg) or glucose (1.5%, 346 mOsm/kg; 4.25%, 489 mOsm/kg). Data obtained from animals exposed to 16.7% raffinose were excluded because of precipitation of the osmotic agent. Low-osmolality raffinose solution induced higher ultrafiltered volume than the low-osmolality glucose-enriched fluid at 120 minutes of dwelling time. No significant differences were observed in effluent sodium and potassium concentration and protein dialysate-to-plasma (D/P) ratio. The D/P ratio of phosphate was higher in the low-osmolality raffinose-based fluid than in the low-osmolality glucose solution. The osmolality of the solutions was significantly decreased after a dwelling time of 120 minutes. We conclude that 4.5% raffinose is an effective osmotic agent. Total or partial replacement of glucose by raffinose for clinical peritoneal dialysis could be eventually considered after appropriate evaluation of its biocompatibility and general side effects.

Sclerosing encapsulating peritonitis

Sclerosing encapsulating peritonitis (SEP), idiopathic or secondary, is a form of intraperitoneal fibrosclerosis that causes intestinal obstruction. In the case of a 41-year-old man with dialysis-induced SEP presented here, we show that intraperitoneal hemorrhage may play an important pathogenetic role and that the process may develop in < or = 12 weeks. Regardless of cause, the treatment of obstruction is operative, with dissection of the encasing membrane from the intestine and separation of adherent loops of small bowel until they are laid free and returned to their normal configuration. The prognosis after appropriate operative therapy is good but depends on coexisting diseases.

Laryngomalacia: a cause for early near miss for SIDS

Six infants had recurrent apnea of infancy episodes (near miss sudden infant death syndrome) during their neonatal period. Physical examination and laboratory investigation were normal. Polygraphic sleep monitoring revealed recurrent obstructive sleep apnea. These infants underwent fiberoptic endoscopy which showed that airway obstruction occurred at the laryngeal orifice as a result of laryngomalacia. It is suggested that laryngomalacia may be a cause for early apnea of infancy.

Exercise tolerance of end-stage renal disease patients

The purpose of this study was to evaluate the exercise tolerance of end-stage renal disease patients, and to examine pulmonary function and blood lactate as its possible limiting factors. Ten end-stage renal disease patients (age 30 +/- 11) were tested at rest and in a subsequent graded treadmill test to exhaustion. Velocity was 4.8 km/h and the grade was incremented by 2.5% every 4 min. One minute of rest, used for blood sampling, separated successive stages. Pulmonary functions (FVC, FEV1) at rest were both 76% of predicted. Resting heart rate, systolic and diastolic blood pressures, and ventilatory equivalent values were higher than normal. At peak exercise, heart rate, oxygen uptake, oxygen pulse and blood lactic acid were lower than normally predicted for maximal exercise, while ventilatory equivalent and diastolic blood pressure were higher. Only six patients reached blood lactate levels beyond 4 mM.l-1 (onset of blood lactic acid), at which point they utilized 88 +/- 5% of their respective peak Vo2. The results suggest that the low exercise tolerance demonstrated in end-stage renal disease patients is not limited by the somewhat compromised pulmonary capacity or by excessive blood lactate levels.

Intraperitoneal phosphate administration in hungry bone syndrome

Hypophosphatemia complicating parathyroidectomy for secondary hyperparathyroidism in renal failure is usually corrected by the oral or intravenous routes. We present a case in which those methods of treatment were not possible, and the phosphate was administered intraperitoneally. Phosphate was added as one molar sodium diphosphate solution to the dialysis fluid. In our case the procedure was well tolerated, phosphate blood levels were rapidly corrected, no alterations in calcium, magnesium or other parameters were detected and the patient was discharged in good condition. In selected cases of hungry bone syndrome after parathyroidectomy, intraperitoneal phosphate can be used safely.

Adaptive myocardial hypertrophy in the renal ablation model

We have previously reported downregulation of the vascular alpha 1-receptor in the 5/6 renal ablation model. In this investigation we have examined the adaptive response of the heart following 5/6 renal ablation. Renal ablated and sham rats were maintained under identical conditions for 6 weeks. Despite the presence of systemic hypertension in renal ablated rats (185 +/- 10 mm Hg, P less than .01), heart weight did not differ from sham. [125I] +/- CYP binding was performed and myocardial norepinephrine (NE) content determined to evaluate myocardial sympathetic neuroeffector mechanisms. Scatchard analysis and 1-isoproterenol competition curves did not reveal a difference in the binding properties of the myocardial beta-receptor. No difference in myocardial NE was found in renal ablated and sham rats. Unexpectedly, 1-isoproterenol stimulation of adenylate cyclase was impaired in renal ablated rats (32.6 +/- 6 v 58.6 +/- 5 pmol/mg/min, P less than .01) and the dose response curve shifted to the right. We conclude that despite systemic hypertension an adaptive hypertrophic response was not present in hearts of renal ablated rats; myocardial sympathetic neuroeffector mechanisms are not altered in this model; and impaired stimulation of adenylate cyclase appears to be the result of a post-receptor defect.

The prevalence of high insertion of scrotum, hydrocele and mobile testis in the newborn infant (36-42 weeks gestation)

The prevalence of some minor abnormalities of the male genitalia was studied in 271 boys born over a period of 2 months. The scrotal insertion on the ventral side of the penis was determined in an objective manner by measuring the ratio of the ventral and dorsal length of the unstretched penis. A scrotal insertion ratio of less than 0.48 defined high insertion of the scrotum which was found in 2.7% of our newborn infants. This anatomical finding has an important clinical significance for the performance of early circumcision. The prevalence of hydrocele in all male newborn infants was 57.9%. Extravaginal (communicating) type was present in 86% of all infants, intravaginal (noncommunicating) in 9.5%, while both types of hydrocele in the same neonate was observed in 4.5%. The relatively high frequency of mobile testes (22%) is of interest. The natural history of this entity is not fully understood and the question of follow-up remains open.

Amelioration of systemic hypertension by converting enzyme inhibition in the renal ablation model

Hypertension associated with a reduction in renal mass has been traditionally thought of as a volume-dependent state. Recent investigations suggest important roles for systemic and glomerular resistance vessels in the pathogenesis of systemic hypertension (SHT) and progression of end-stage renal disease. To examine this relationship, investigations were performed in two groups of rats maintained for 6 weeks following 5/6 renal ablation. Group A received converting enzyme inhibition (CEI) for 6 weeks. Group B received no treatment. Systolic blood pressure and weight of remnant kidney tissue were both increased in group B (P less than 0.01). BUN did not differ in groups A and B; however, renal PGI2 excretion was increased in group A (P less than 0.01). Renal morphology was preserved in group A, with little or no evidence of glomerular sclerosis. CEI prevents SHT and enhances renal PGI2 excretion in this model. The selective increase in PGI2 may mediate systemic and renal effects of this agent.

Myocardial hypertrophy: the effect of sodium and the role of sympathetic nervous system activity

Dietary sodium and the myocardial alpha 1-receptor have been implicated in the hypertrophic response of myocardial tissue. Alterations in sodium homeostasis have been demonstrated to influence sympathetic nervous function, centrally and peripherally. In this investigation, we have examined the effect of dietary sodium on the development of myocardial hypertrophy; and the role of sympathetic neuroeffector mechanisms in the hypertrophic response. Studies were performed in three groups of uninephrectomized rats: A-regular diet; B-1% saline/regular diet; C-1% Saline/doca/regular diet. Groups A and B did not develop systemic hypertension (SHT). Saline treatment increased heart weight and the density of surface alpha 1-receptors; myocardial norepinephrine (NE) was reduced. Group C developed SHT. Heart weight was greatest in Group C; and myocardial NE was severely depleted. Downregulation of myocardial alpha 1-receptors, a finding consistent with the hyperadrenergic state, was observed in Group C. Our results suggest dietary sodium may modulate hypertrophic response in myocardial tissue, by altering sympathetic neuroeffector mechanisms.

Upregulation of the vascular alpha-1 receptor in malignant DOCA-salt hypertension

In this investigation we describe regulation of the vascular alpha-1 receptor and functional properties of resistance vessels in malignant hypertensive DOCA-salt rats (DOCA-salt). Uninephrectomized control and DOCA-salt rats were maintained for 6 weeks; microscopic renal morphology provided an index of vascular injury. Radioligand binding studies indicated a striking increase in the density of mesenteric alpha-1 binding sites in DOCA-salt (542 +/- 44 fm/mg) vs. salt control (206 +/- 4 fm/mg) and water control (223 +31 fm/mg) P less than .01. The affinity of the receptor for the radioligand [125I] (+/-) BE 2254 was reduced in DOCA-salt rats. Electrical nerve stimulation and agonist dose response curves were performed on isolated perfused mesenteric arteries. A singular correlation between increased receptor density and vascular responses in DOCA-salt rats could not be demonstrated. The norepinephrine (NE) content of mesenteric arteries was reduced in DOCA-salt (1001 +/- 32 ng/g) vs. water control (1522 +/- 44 ng/g) and saline control (1538 +/- 30 ng/g) P less than .01. Our results indicate, upregulation of the mesenteric alpha-1 receptor occurs in DOCA-salt rats, however, additional factors participate in the vascular response to adrenergic stimulation in this model.

Externally applied abdominal vibration as a method for improving efficiency of peritoneal dialysis

We studied the effect of externally applied vibration onto the abdominal wall on the efficiency of peritoneal dialysis (PD). Ten patients were studied. Three consecutive PD exchanges (control sessions, CS) were compared with vibration sessions (VS). Samples of blood and dialysate were analyzed for urea nitrogen (UN), creatinine (Cr) and potassium (K). Mean clearance was calculated. We found that vibration increased significantly the mean UN, Cr and K clearances.

Effect of chronic uremia on the cardiovascular alpha 1 receptor

Adrenergic dysfunction in uremia has been well described. Several lines of evidence suggest disorders of blood pressure regulation and myocardial response may occur secondary to adrenergic dysfunction; attenuated pressor response to norepinephrine (NE) in uremia; attenuated chronotropic responses during dialysis induced hypotension. Since the adrenergic receptors are the effector component of the adrenergic nervous system, we have employed the partially nephrectomized uremic rat, to examine the effect of chronic uremia (4-6 weeks) on the binding properties of alpha 1 receptors in rat mesenteric artery and myocardial tissue. The results indicate that moderate levels of uremia alter the binding properties of both the alpha 1 vascular and myocardial receptor.