Abyssal Benthic Rover, an autonomous vehicle for long-term monitoring of deep-ocean processes.

The deep-ocean carbon cycle is poorly quantified. An abyssal benthic rover was developed to make long time-series measurements of seafloor processes related to organic carbon remineralization and sequestration. Benthic Rover II (BR-II) is an autonomous dual-tracked vehicle that measures bottom water temperature and oxygen concentration, current velocity, and sediment community oxygen consumption (SCOC; respiration). BR-II is programmed to transit with low surface-contact pressure across the seafloor, photograph bottom conditions, and stop regularly to occupy respirometer incubation sites, with deployment periods up to 1 year. Now, continuously operational at a 4000-m station in the northeast Pacific over 5 years, substantial weekly, seasonal, annual, and episodic events have been recorded, which are critical to assessing the deep-ocean carbon cycle. There was a significant increase in phytodetritus cover (P < 0.01) arriving on the seafloor from the overlying water column between 2015 and 2020 that was negatively correlated with bottom water dissolved oxygen concentration (P < 0.01). Over the continuous 5-year monitoring period from November 2015 to November 2020, SCOC was positively correlated with phytodetritus cover (P < 0.01) and increased significantly from 2015 to 2020 (P < 0.01). These results show important influences of biological processes on the carbon cycle. The demonstrated success of BR-II now creates opportunities to expand the long-term monitoring of the deep sea to resolve the coupling of water column and benthic processes key to understanding the oceanic carbon cycle on a planet engulfed in a changing climate.

Processes influencing seasonal hypoxia in the northern California Current System.

This paper delineates the role of physical and biological processes contributing to hypoxia, dissolved oxygen (DO) < 1.4 mL/L, over the continental shelf of Washington State in the northern portion of the California Current System (CCS). In the historical record (1950-1986) during the summer upwelling season, hypoxia is more prevalent and severe off Washington than further south off northern Oregon. Recent data (2003-2005) show that hypoxia over the Washington shelf occurred at levels previously observed in the historical data. 2006 was an exception, with hypoxia covering ~5000 km(2) of the Washington continental shelf and DO concentrations below 0.5 mL/L at the inner shelf, lower than any known previous observations at that location. In the four years studied, upwelling of low DO water and changes in source water contribute to interannual variability, but cannot account for seasonal decreases below hypoxic concentrations. Deficits of DO along salinity surfaces, indicating biochemical consumption of DO, vary significantly between surveys, accounting for additional decreases of 0.5-2.5 mL/L by late summer. DO consumption is associated with denitrification, an indicator of biochemical sediment processes. Mass balances of DO and nitrate show that biochemical processes in the water column and sediments each contribute ~50% to the total consumption of DO in near-bottom water. At shorter than seasonal time scales on the inner shelf, along-shelf advection of hypoxic patches and cross-shelf advection of seasonal gradients are both shown to be important, changing DO concentrations by 1.5 mL/L or more over five days.

Clinical intra-amniotic infection with meconium-stained fluid at term: an analysis of Apgar scores.

A retrospective analysis of 1- and 5-minute Apgar scores of patients at term gestation (37 to 42 weeks) with evidence of clinical intra-amniotic infection and meconium-stained amniotic fluid was performed. The patients were selected from the labor and delivery records of two Detroit hospitals during the study period from January 1988 through May 1994. The author suggests that the presence of clinical intra-amniotic infection with meconium-stained fluid does not affect Apgar scores of term infants.

Recurrence of intravenous talc granulomatosis following single lung transplantation.

Advanced pulmonary disease is an unusual consequence of the intravenous injection of oral medications, usually developing over a period of several years. A number of patients with this condition have undergone lung transplantation for respiratory failure. However, a history of drug abuse is often considered to be a contraindication to transplantation in the context of limited donor resources. A patient with pulmonary talc granulomatosis secondary to intravenous methylphenidate injection who underwent successful lung transplantation and subsequently presented with recurrence of the underlying disease in the transplanted lung 18 months after transplantation is reported.

Synthesis and activity of 6-substituted purine linker amino acid immunostimulants.

A series of 6-substituted purinyl alkoxycarbonyl amino acids were synthesized and evaluated for their ability to stimulate cytotoxic T lymphocytes (CTLs) and the mixed lymphocyte reaction (MLR). A few of these compounds, in particular [[5-[6-(N,N-dimethylamino)purin-9-yl]pentoxy]-carbonyl]D-arginine (BCH-1393, 4a), displayed an in vitro stimulation of CTLs comparable to interleukin 2 (IL 2). BCH-1393 increased the CTL response between 10(-9) M and 10(-5) M. Further, this potent in vitro activity was reflected as a significant increase in CTL cell number in vivo. However, immunophenotyping of some of the other equipotent compounds did not reveal a parallel relative increase in CTLs in vivo. It was difficult to formulate a rigorous structure-activity relationship based on in vitro CTL activity. Nevertheless, the activity was dependent upon the nature of the 6-substituent on the purine, the type and stereochemistry of the amino acid, and the distance and spatial freedom between the purine and amino acid as defined by the length and rigidity of the linker. These compounds were generally nontoxic, as exemplified by BCH-1393. BCH-1393 is a promising immunostimulant which may be targeted for those disease states which require an increased CTL or TH1 type response.

The establishment of hepatocyte cell surface polarity during fetal liver development.

Antibodies to six glycoproteins present in different domains of the hepatocyte plasma membrane were used to study the establishment of cell surface polarity during rat fetal liver development. The proteins were immunoprecipitated from fetal liver homogenates between 14 and 21 days of gestation and quantified by immunoblotting. Aminopeptidase N, CE 9, and HA 321, which reside in the apical, basolateral, and lateral plasma membrane in the adult hepatocyte, respectively, were present in high concentrations at 14 days of gestation and remained high until birth. In contrast, two apical proteins (HA 4 and dipeptidyl peptidase IV) and two basolateral proteins (ASGP receptor and EGF receptor) were first detected between 16 and 18 days of gestation and increased linearly until birth. HA 4 was the only molecule for which the fetal and adult forms differed, with the former having a faster mobility on SDS-PAGE, due to differences in N-linked oligosaccharides. With two exceptions, the localization of the molecules from earliest detection was restricted to the same domain as that in the adult. At 15 days of gestation, HA 321 and a small portion of aminopeptidase were detected on the basolateral membrane. By 21 days both molecules had assumed their adult localization pattern. Our results indicate that the biogenesis of cell surface polarity is an early event, implying that the mechanisms for sorting plasma membrane molecules are functional very early in development. Furthermore, the different patterns of appearance of the six molecules, irrespective of domain, indicate that the biochemical composition of the cell surface changes dramatically during fetal liver development.

Receptor-mediated endocytosis of epidermal growth factor by rat hepatocytes: receptor pathway.

Substantial amounts of epidermal growth factor (EGF) are cleared from the circulation by hepatocytes via receptor-mediated endocytosis and subsequently degraded within lysosomes. We have used a combined biochemical and morphological approach to examine the fate of the receptor after exposure to EGF. Polyclonal antibodies were prepared against the purified receptor and their specificity established by immunoprecipitation and immunoblotting techniques. The EGF receptor was then localized by immunofluorescence and immunoperoxidase techniques and quantified on immunoblots. In untreated livers, EGF receptor was restricted to the sinusoidal and lateral surfaces of hepatocytes. 2-4 min after exposure of cells to EGF, the receptor was found in small vesicles (i.e., coated vesicles) as well as larger vesicles and tubules at the cell periphery. By 15 min the receptor was found in multivesicular endosomes located near bile canaliculi. Exposure of hepatocytes to EGF also resulted in a rapid loss of receptor protein from total liver homogenates and a decrease in its half-life from 8.7 h in control livers to 2.5 h. This EGF-induced loss of receptors was not observed when lysosomal proteinases were inhibited by leupeptin or when endosome/lysosome fusion was prevented by low temperature (16 degrees C). In the presence of leupeptin, receptor could be detected in structures identified as lysosomes using acid-phosphatase cytochemistry. All these results suggested rapid internalization of EGF receptors in response to ligand and degradation within lysosomes. However, four times more ligand was degraded at 8 h than the number of high-affinity (Kd of 8-15 nM) EGF-binding sites lost, suggesting either (a) high-affinity receptors were recycled, and/or (b) more than 300,000 receptors were available for EGF uptake. We identified and characterized a latent pool of approximately 300,000 low-affinity receptors (Kd approximately 200 nM) that could be separated on sucrose gradients from the plasma membrane pool of approximately 300,000 high-affinity receptors (Kd of 8-15 nM). Despite the differences in their binding affinities, the high- and low-affinity receptors appeared to be structurally identical and were both EGF-dependent protein kinases. In addition, the dynamics of the low-affinity receptors were consistent with a functional role in EGF uptake and delivery to lysosomes.

Transcellular transport of polymeric IgA in the rat hepatocyte: biochemical and morphological characterization of the transport pathway.

Polymeric IgA (pIgA) is transported by liver parenchymal cells (hepatocytes) from blood to bile via a receptor-mediated process. We have studied the intracellular pathway taken by a TEPC15 mouse myeloma pIgA. When from 1 microgram to 1 mg 125I-pIgA was injected into the saphenous vein of a rat, 36% was transported as intact protein into the bile over a 3-h period. The concentration of transported 125I-pIgA was maximal in bile 30-60 min after injection, and approximately 80% of the total 125I-pIgA ultimately transported had been secreted into bile by 90 min. A horseradish peroxidase-pIgA conjugate (125I-pIgA-HRP) was transported to a similar extent and with kinetics similar to that of unconjugated 125I-pIgA and was therefore used to visualize the transport pathway. Peroxidase cytochemistry of livers fixed in situ 2.5 to 10 min after 125I-pIgA-HRP injection demonstrated a progressive redistribution of labeled structures from the sinusoidal area to intermediate and bile canalicular regions of the hepatocyte cytoplasm. Although conjugate-containing structures began accumulating in the bile canalicular region at these early times, no conjugate was present in bile until 20 min. From 7.5 to 45 min after injection approximately 30% of the labeled structures were in regions that contained Golgi complexes and lysosomes; however, we found no evidence that either organelle contained 125I-pIgA-HRP. At least 85% of all positive structures in the hepatocyte were vesicles of 110-160-nm median diameters, with the remaining structures accounted for by tubules and multivesicular bodies. Vesicles in the bile canalicular region tended to be larger than those in the sinusoidal region. Serial sectioning showed that the 125I-pIgA-HRP-containing structures were relatively simple (predominantly vesicular) and that extensive interconnections did not exist between structures in the sinusoidal and bile canalicular regions.

Pulmonary amyloid nodule simulating pancoast tumor.

Solitary pulmonary amyloid nodules may be confused with a bronchogenic carcinoma. The diagnosis may be suspected from the presence of calcification within the nodule and confirmed by trephine or needle aspiration biopsy.

Regional ionic and albumin content of fluid in the tracheobronchial tree in dogs.

We have devised a technique for collecting airway fluid from the bronchi in order to investigate the biochemical indices of airway fluid in normal dogs and the changes produced in them by pharmacological interventions. We collected airway fluid from the trachea by a screen technique and by means of filter paper cylinders inserted through a fiberoptic bronchoscope (the new method) and from main and segmental bronchi by the new method only. When bronchial fluid was compared with plasma, the concn of albumin was found to be much lower, Na+ lower, and Cl- either higher or similar. The Na+:Cl- ratio was lowest in fluid from the trachea (1.04) and highest in fluid from segmental bronchi (1.14), but was significantly lower at all levels than in plasma (1.32). Subcutaneous administration of methacholine chloride significantly increased the weight of airway fluid collections. Infusion of 5% hypertonic saline induced changes in the concns of electrolytes (but not of albumin) that correlated with changes in the plasma. The major differences in electrolyte and albumin concns in airway fluid and plasma likely reflect a bidirectional transepithelial flux of these ions. The regional differences in electrolyte concns and ratios may be due to differences in anatomic structure and in the functioning of ionic pumps along the tracheobronchial tree.

Simultaneous comparison of canine tracheal transport of anion exchange resin particles to albumin macroaggregates and sulfur colloid. Effects of subcutaneous methacholine chloride and intravenous hypertonic saline.

We compared simultaneously measured canine tracheal transport rates of Dowex anion exchange particles with macroaggregates of albumin, and with sulfur colloid. We found that sulfur colloid moved significantly faster than large Dowex particles (diameter 180 micrometer), which had transport rates similar to macroaggregates of albumin, and small Dowex particles diameter 3 micrometer). We examined the alteration of airway fluid caused by intravenous 5% saline or subcutaneous methacholine chloride. We then studied the effects of the altered airway fluid on the transport rates of large Dowex particles and sulfur colloid. We found that sulfur colloid continued to be transported faster than Dowex particles. Although we do not have an explanation for the faster transport of sulfur colloid, we believe that the physiochemical properties of the marker may influence its rate of tracheal transport.

Caval catheter haemodialysis.

We describe a five-year experience using vena caval access for haemodialysis utilizing the McIntosh double-lumen catheter. A description of the catheter, method of insertion and of its performance including complications in 88 patients is given. The McIntosh catheter is a rapid, simple, effective and safe means of obtaining access for short-term haemodialysis.

Simultaneous canine tracheal transport of different particles.

We describe a method to study simultaneously the transport of 2 different markers in the canine trachea. In our studies, we found that choice of radioisotopic label and variation in marker size from 3 to 180 micrometer did not affect the transport rate of basic anion exchange resin particles. Furthermore, anion exchange and acidic cation exchange particles of the same size had similar tracheal transport rates. This method may help to determine the influence of the physicochemical properties of markers on mucous transport.