Levels Of Po Research Articles

Environmental factors affecting the bioavailability and toxicity of Cd and Zn to an anaerobic bacterium Desulfovibrio

Husainsagar lake receives heavy metal pollutants through a channel which passes from the industrial area. Concentrations of Cd, Cu and Zn in lake water were 4.6, 21.2 and 197.0 μg/l, respectively and were within permissible limits (ICMR 1975, 10, 50, 500 μg/l of Cd, Cu and Zn, respectively). However, the concentrations of Hg and Cr were 10 and 82 μg/l and have exceeded the limits (ICMR 1975, 2 μg/l of Hg and 50 μg/l of Cr), The concentrations of these metals were a few thousandfold more in surficial sediments. In the present study, the toxic levels of Cd and Zn to the growth of Desulfovibrio, a predominant sulfate reducing anaerobic bacterium, isolated from surficial sediments of the lake, were determined. Cd (23.0 μg/ml) and Zn (9.1 μg/ml) inhibited the growth of Desulfovibrio. Environmental factors have influenced the levels of toxicity of Cd and Zn. The concentration levels of Cl, Ca, PO 4, Fe and Mn, which gave maximum protection from Cd and Zn toxicity to Desulfovibrio, were determined. In contrast to aerobic organisms, Desulfovibrio was more sensitive to Zn. Cd and Zn together have showed a synergistic effect on the organism.

Expression of ribosomal phosphoprotein PO is induced by antitumor agents and increased in Mer− human tumor cell lines

We initiated this study to determine whether three structurally related bifunctional alkylating agents could induce the expression of a presumptive human DNA repair gene. The gene chosen for this study is known to encode the ribosomal phosphoprotein PO, but ironically may also share functions related to DNA repair. We now show by Northern analysis that PO is induced by L-phenylalanine mustard, 4-hydroperoxycyclophosphamide and mechlorethamine, which are DNA-damaging agents commonly used as chemotherapeutic antitumor agents. In further support of its involvement in DNA repair is the finding of a 30- to 50-fold constitutive overexpression of the PO gene in human tumor cell lines that are Mer-, cells which lack O6-methylguanine methyltransferase activity, when compared to Mer+ cell lines. This constitutively elevated level of PO in Mer- cell lines, which are thus DNA repair defective for O6-alkyguanine lesions, was not observed for other genes tested, including the human ribosomal gene S17 whose mRNA steady-state levels were uniformly the same in both Mer- and Mer+ cells. Taking these data together, it appears that increased levels of PO are somehow linked to DNA repair, and increased expression of PO may compensate for the decreased O6-methylguanine DNA methyltransferase activity in Mer- cells. Furthermore, the PO gene has also been shown to be overexpressed in colorectal tumors and polyps and the sera of some systemic lupus erythematosus patients contain antibodies against PO. The titer of the anti-PO antibodies rises significantly during lupus psychosis.

Serum and urinary levels of reproductive hormones associated with the estrous cycle in white‐tailed deer (Odocoileus virginianus)

AbstractConcentrations of estradiol‐17β (E2), progesterone (Po), and luteinizing hormone (LH) in serum and estrone glucuronide (E1G) and pregnanediol glucuronide (PdG) in urine were determined by direct radioimmunoassay in five yearling and three adult female white‐tailed deer (Odocoileus virginianus) from 14 October to 20 December 1985. Elevated levels of LH were recorded before the first estrus of the breeding season and immediately preceding or during behavioral estrus. Urinary E1G and PdG concentrations were poorly correlated with serum levels of E2 and Po, respectively. Serum Po levels prior to the first estrus of the breeding season indicate that pubertal yearlings experience silent ovulations and suggest that silent ovulations may be important in the transition from adolescence to cycling adult in white‐tailed deer. © 1992 Wiley‐Liss, Inc.

The effect of β-sympathomimetic stimulation on parotid salivation in the red kangaroo ( Macropus rufus)

Salivation was stimulated by intracarotid isoprenaline infusion given alone or combined with acetylcholine. By itself, isoprenaline (0.12 – 1.2 nmol kg −1 min −1) stimulated flow rates of 0.037 – 0.233 ml min −1 (2.77 – 10.5 μ1/g gland per min). Salivary Na, Cl, PO 4 and total solute concentrations were positively correlated with flow; K, Mg and urea were negatively correlated with flow; and Ca, H +, HCO 3, protein and amylase activity were not correlated with flow. Relative to cholinergic saliva, isoprenaline-evoked saliva had higher levels of amylase activity, urea, protein, K, Mg, H +, PO 4 and Cl but lower osmolality, Na, Ca and HCO 3. At a steady flow (1ml min −1), isoprenaline infusion (0.3nmol kg −1 min −1) superimposed on a pre-existing acetylcholine infusion increased salivary amylase activity, protein, urea, K, Mg, Cl and PO 4, reduced HCO 3 and did not alter Na, Ca, H + and osmolality. Superimposition of isoprenaline infusion (0.5 nmol kg −1 min −1) on a low-level acetylcholine infusion increased flow rate by 400–900%. Excretion rates of K, Mg, Cl and PO 4 were higher and Ca lower than predicted for saliva secreted at equivalent flows during acetylcholine stimulation. Na, H + and HCO 3 were as predicted for the same flow rate under cholinergic stimulation. The simplest coherent interpretation of these data is that isoprenaline affects transport of protein and ions at the end organs, but has little effect on the resting transport characteristics of the striated and excretory ducts of the kangaroo parotid, in accord with the known nerve distribution of this gland.

Temporal changes in PO and MBP gene expression after crush-injury of the adult peripheral nerve

The crush-injured sciatic nerve provides a model to study Schwann cell regulation of myelin gene expression during the process of demyelination and remyelination. In order to investigate the possible transcriptional regulation of myelin gene expression, the quantity, quality and translational efficiency of PO (the major myelin glycoprotein) and MBP (the myelin basic proteins) coding messages were investigated as a function of time following crush-injury of the adult rat sciatic nerve. Northern blot analysis indicated that the size of the PO and MBP transcripts remain unchanged in the distal segments of crushed sciatic nerves at 1, 2, 4, 7, 10, 14 and 21 days after crush-injury. Dot-blot analysis showed a sharp drop in levels of PO and MBP coding transcripts 1 day after crush-injury with the lowest steady-state levels at 4–7 days. Message levels were found to increase after 7 days, the highest increase in levels of message was found to be between 10 and 14 days. The highest steady-state level of both transcripts was observed at 21 days. In vitro translation and immunoprecipitation of PO-translated products from various stages of crush-injury also indicated this trend. The pattern of gene expression of PO- and MBP-coding transcripts parallel each other and follow the pattern of demyelination and remyelination. The results are also consistent with our previous interpretation which suggests that PO and MBP gene expression is regulated at the level of transcription and that these two genes might be coordinately expressed. Western blot analysis of PO protein from these stages revealed a similar decrease and then increase in the levels of the protein. However, the protein levels were significantly delayed compared to the levels of the transcript. The lowest level of in vivo PO protein was found 14 days after crush-injury. This temporal lag in the level of PO protein with respect to the level of PO coding transcript suggests possible post-transcriptional regulation of the PO gene in this experimental model of peripheral neuropathy.

Effects of sodium and phosphate on growth of cyanobacteria

We conducted laboratory experiments to evaluate the effects of NaCl and phosphorus enrichments on natural phytoplankton assemblages from Lake Michigan in continuous-flow systems, at a dilution rate of 0.25 d −1. The experiment was repeated four times, 1981–1982, using freshly-collected natural lakewater inocula and temperature regimes typical of near-surface waters at initiation (6, 12, 16 and 20°C), at two levels of PO 4−P (1–2 vs 91–92 μg l −1) and of Na + (3–4 vs 9–10 mg l −1) each time. As a single factor, sodium chloride enrichments had no significant effect on growth rates or densities of cyanobacteria in cultures containing natural phytoplankton assemblages from Lake Michigan. However, filamentous cyanobacteria proliferated in the presence of elevated phosphorus concentrations, both with and without concurrent NaCl additions, particularly in warmer waters. Our laboratory results were consistent with the hypothesis that cyanobacteria are favored in phytoplankton of large lakes with low N:P ratios.

The Esophageal Obturator Airway

To the Editor.— With reference to the article, Esophageal Obturator Airway, 1 I believe that there are several points that bear clarification and reinterpretation. It is to be stressed that the small series of patients of Schofferman et al, 2 which probably should be considered as unrepresentative and from which the authors quote, was analyzed by them in relation to the efficiency of ventilation and Pco 2 and the conclusion reached that patients had sustained mixed metabolic and respiratory acidosis. The mean Po 2 in this group (Table) receiving 100% oxygen was 201 mm (esophageal obturator airway [EOA]) and 152 mm (endotracheal tube [ET]), the Pco 2 levels being 61 mm (EOA) and 55 mm (ET), respectively. Levels of Po 2 for the entire series of patients were 120 mm (EOA) and 102 mm (ET), and Pco 2 levels were 62 mm (EOA) and 49 mm (ET), respectively. The

A DIFFUSION INTERPRETATION OF SOIL PHOSPHORUS DESORPTION

ABSTRACT In earlier papers, we showed the applicability of a power-form equation to describe the kinetics of soil P desorption for several soils in laboratory batch experiments and in a rainfall-runoff process where Pd is the amount of P desorbed in time t at a water: soil ratio of W, with Po being the initial amount of desorbable P present in the soil, and K, α, and β constants for a given soil. In this note, we have attempted to explain the above equation in terms of diffusion-controlled desorption. The development utilized some empirical deductions from the literature. The basic desorption rate equation is formulated as a diffusion equation, with the diffusion coefficient taken as a power function of the fraction of Po yet to be desorbed. This basic formulation is tested on experimental data for different levels of Po and t, at a large value of W. The basic equation is integrated and the results are simplified to derive the equation for Pd given above.

Hepatic oxygen supply in reversible and irreversible hemorrhagic shock

Data has been collected in a manner that clarifies the degree to which hepatic oxygen supply is affected during the circumstances of reversible and irreversible hemorrhagic shock. The liver PO 2 estimations support the concept that the liver is largely hypoxic during hemorrhagic hypotension. Subsequent nonsurvival is correlated with depressed hepatic reoxygenation and persisting lactic acidosis following retransfusion of all shed blood. By contrast, survivors established significant levels of hepatic PO 2 and reversed their acidotic state. We believe the profile of hepatic oxygen supply presented should contribute to the interpretation of alterations of hepatic function reported in other hemorrhagic shock studies.

Vacuum Ultraviolet Reflection Spectra of KDP and ADP

The reflection spectra of KDP and ADP are studied in the vacuum ultraviolet region up to 35 eV. Polarized light is used in the study of low energy part below 13 eV. Some peaks in the spectra are found to show remarkable dependence on the polarization of the incident light. The energy levels of PO 4 3- , H 2 PO 4 - and H 4 PO 4 + are calculated by the extended Huckel method. By comparing the peak energies in the reflection spectra with the energy levels and taking the polarization characteristics into consideration, tentative assignment is given to the bands observed.

Altered hemoglobin oxygen affinity in patients with acute myocardial infarction

Alterations in the oxyhemoglobin dissociation curve might affect calculations of arteriovenous oxygen differences and might contribute to maintenance of myocardial oxygénation in patients with acute myocardial infarction. Accordingly, we analyzed oxyhemoglobin dissociation curves by the dynamic scanning technique as well as red cell diphosphoglycerate and adenosine triphosphate (ATP) determinations in peripheral venous and arterial blood samples from 43 patients with acute myocardial infarction. The oxyhemoglobin dissociation curve in these patients was shifted to the right, as reflected by an increase in p 50 values beginning as early as 2 hours and as late as 10 days after the onset of infarction. The magnitude of the p 50 shift did not correlate with initial or prevailing levels of systemic or pulmonary arterial PO 2, red cell 2,3-diphosphoglycerate, ATP or cardiac index. The p 50 values in venous and simultaneously obtained arterial samples correlated closely. Peak P 50 was related to initial clinical class, size of infarct measured by serial serum creatine phosphokinase (CPK) analysis and acute mortality. Results obtained indicate that shifts in the oxyhemoglobin dissociation curve in. patients with acute infarction may facilitate oxygen availability to marginally perfused myocardium and must be taken into account when arteriovenous oxygen differences are calculated on the basis of PO 2 or hemoglobin oximeter determinations, or both.

Oxygen studies in retrolental fibroplasia. IX. The effects of elevated arterial oxygen tension on retinal vascular dynamics in the kitten.

The effects of increased arterial partial oxygen tensions (po 2 ) on retinal circulation of the young kitten were investigated by observing changes in the velocity of fluorescein wave fronts in the major arterial branches of the retina. Changes in velocity were correlated with simultaneous carotid arterial po 2 determinations. These studies on the larger retinal vessels are the first of a series aimed at determining levels of arterial po 2 that can be sustained without damage to any components of the retinal vascular bed.

Tonography in normal and malnourished children.

Tonographic studies were performed while 43 severely marasmic children and 33 normal controls ranging in age between 1 month and 1 year were under pentobarbital sodium sedation. The results showed no significant difference in the levels of Po and C values in the two groups. There was a statistically significant negative correlation between the levels of Po and weight in the normal children. These findings suggest similar dynamics in the eyes of the normal and marasmic children. The significance of these findings in relation to the smaller hyperopic error previously described in the marasmic children is discussed.

Small bowel blood flow in vivo and in vitro

1. 1. In vivo studies of denervated 5 foot segments of small bowel indicate that a blood flow of 77 to 90 ml. per minute at a pressure range of 150 100 and 100 60 mm. Hg, when the arterial blood pO 2 is within the range 175 and 400 mm. Hg, results in the maintenance of viability and acceptable levels of venous blood pH, pO 2, and pCO 2. 2. 2. In vitro studies of small bowel segments indicate that pulsatile blood flow to the segments is associated with blood flows of 75 to 90 ml. or more at pressures of 150 100 to 100 60 mm. Hg and the maintenance of viability and acceptable levels of venous blood pH, pO 2, and pCO 2, when the arterial blood pO 2 is within the range 175 and 400 mm. Hg. 3. 3. In vitro studies of small bowel segments indicate that nonpulsatile blood flow to the segments is associated with marked alterations in flow and pressure, loss of viability, an increase in venous blood pCO 2, and a decrease in venous blood pH and pO 2.

Factors affecting the measurement of the partial pressure of oxygen in blood using a covered electrode system

An electrode system and cuvette are described for the measurement of the partial pressure of oxygen (Po 2) in blood. The platinum cathode has a diameter of 1 mm and is covered by polyethylene 0.125 mm in thickness. The electrode is calibrated with water having a known Po 2, and a series of tonometer experiments have defined the fixed relationship between the diffusion current for blood and water of the same P O 2 The rate of fall of Po 2 in stored blood was found to be less than in earlier reports, probably because of the sterility maintained in the present experiments. The effect of oxygen contained in the dead space of the syringe was shown to be negligible except at very high Po 2. Other tonometer experiments showed that variation in the partial pressure of carbon dioxide had a small but significant effect on the measured Po 2 in blood. In the case of water this effect was found at only one of three levels of Po 2. Alterations in the packed cell volume of the blood significantly affected the measured Po 2, but correction for this would rarely be necessary.

THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: XI. THE EFFECT OF STEM RUST ON THE PHOSPHATE FRACTIONS IN WHEAT LEAVES

Inorganic, organic, and various organic phosphate fractions were determined in uninfected and infected first seedling leaves of Little Club wheat at various stages between 6 to 18 days after incubation with Puccinia graminis tritici Erikss. and Henn. (Race 15B). Inorganic (Pi), organic (Po), and total P per unit fresh weight increased as uninfected leaves aged and the levels of Pi were much more readily altered by changes in nutritional status and environmental conditions than the levels of Po. Infection increased total P and the highest concentrations occurred at the loci of rust pustules. Since the concentration of P was lower in uninfected portions of infected leaves than in comparable parts of uninfected leaves or in rust pustules, it appeared that P was transported into the pustules from uninfected parts of the leaf. Both Pi and Po were increased by infection, but the Pi/Po ratio was lowered. Acid-soluble bound P, easily hydrolyzable P, lipid P, RNA-P, and residual organic P were all increased by infection.When leaf pieces were infiltrated with and then floated on 10−4 M 2,4-dinitrophenol for 24 hours, the levels of all organic phosphate fractions were lowered and Pi was increased, both in uninfected and infected leaves. Dinitrophenol raised the Pi/Po ratio about 30% in uninfected and about 100% in infected leaves.The results militate against the view that the increase in respiration rate caused by infection is due to the uncoupling of oxidative phosphorylation.

Preliminary Description and Analysis of the Spectrum of Polonium

Purified polonium has been excited by high-frequency electrodeless discharges of 10, 30, and 400 Mc/sec at temperatures ranging from 200° to 800°C, and in an enclosed spark source. One hundred thirty-nine lines have been found in the spectrum from the electrodeless discharge. Thirty-five of these and thirteen additional lines have been observed in the spectrum of the spark discharge. Forty-eight lines have been classified as transitions involving twenty-four energy levels of Po i. Four levels of the fundamental configuration 6p4 have been identified. The observations have been compared with theoretical predictions for this configuration. Separations are well represented by theory with the parameter F2= 1096K and ζ= 12 379K. The absolute value of the lowest level 6p4 3P2′ has been estimated from the first two members of the series 6p3(4S0)ns. An estimate of 67 980K is obtained. This corresponds to an ionization potential of 8.43 v for the neutral polonium atom.