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PubMed1984

Short-term systems to assess thiophosphoryl chloride standards.

The rat acute oral LD50 value of PSCl3 is 750 mg per kg body weight. A rat 90-day oral feeding study at dose levels of 7.5 mg (P1) and 37.5 mg (P5) per kg resulted in increased body weight gain. Other responses inconsistently varied between dose levels. At 7.5 mg kg-1, a trend towards enhancement of relative weight of liver, spleen, kidney and adrenals was noted; at 37.5 mg kg-1, decreasing relative spleen and adrenal weights were observed. The most of the hematological and biochemical changes in blood serum cannot be believed to be transitory adaptive changes, but valid toxic effects. On the other hand, there are some indicators that suggest a possible trophic effect of this compound. However, the reversible dystrophic changes in liver, as well as the histochemical and histoenzymical results, require us to take into account that inactive chronic hepatitis could be reactivated by further toxic insult. A teratology study demonstrated increased number, body weight and length of fetuses, without apparent pathological events (tumors, external malformations). A mutagenicity test performed on rat femoral bone marrow after 30-days feeding of 37.5 mg kg-1 did not indicate any significant change in the incidence of chromosomal aberrations, compared with the control group. The recommended maximum allowable concentration in the working zone for thiophosphoryl chloride in air was set at 3 mg m-3.

Abnormalities, Drug-Induced↗
PubMed1988

pH and compartmentation of isolated perfused rat liver studied by 31P and 19F NMR.

The phosphorus NMR spectra of isolated perfused rat liver displays a prominent inorganic phosphate peak at 2.76 +/- 0.05 ppm relative to liver glycerolphosphocholine at 0.49 ppm. From titration curves of phosphorus-containing compounds this corresponds to a pH of 7.4. The spectra also display a shoulder on the prominent inorganic phosphate peak at 2.22 +/- 0.55 ppm corresponding to a pH of 7.0. Fructose is phosphorylated in the C1 position by the liver and the resulting fructose-1-phosphate is located in the cytosol. From the titration curves, this compound was at pH 7.0. When inorganic phosphate was added to the perfusate, 13 of 25 livers showed two inorganic phosphate peaks resolved in the difference spectra, one originating from the perfusate, the other at pH 7.0. When large (50 mM) fructose doses were administered to the liver, the prominent peak decreased allowing two peaks to be resolved. FCCP treatment of the liver caused the two peaks to coalesce with the final pH of both the fructose-1-phosphate and inorganic phosphate being the same. 19F NMR of difluoromethylalanine gave an intracellular pH of 7.4 for the isolated perfused liver. The data presented do not lend themselves to satisfactory interpretation, and call into question the correctness of the traditional assignment of liver inorganic phosphate being cytosolic in origin.

Animals↗
PubMed1990

Octa(thymidine methanephosphonates) of partially defined stereochemistry: synthesis and effect of chirality at phosphorus on binding to pentadecadeoxyriboadenylic acid.

Block condensation of MePOCI2 or MeP(NEt2)2 with appropriately protected tetra(thymidine methanephosphonates) of predetermined sense of chirality at asymmetric phosphonate centres gave two pairs of diastereomeric mixtures, namely (SpSpSpSpSpSpSp + SpSpSpRpSpSpSp) 5a and (RpRpRpRpRpRpRp + RpRpRpSpRpRpRp) 5b. A comparison of the CD spectra of 5a and 5b with those of octathymidylic acid (7) and a random mixture of diastereomers of octa(thymidine methanephosphonate) (6), and also a comparison of the Tm of complexes formed between 5a, 5b, 6 or 7, and pentadecadeoxyriboadenylic acid (8), indicates that octamer 5b and its complex with its complementary oligonucleotide has a well-ordered structure due to the 'outward' or 'pseudoequatorial' orientation of the methyl group of each internucleotide methanephosphonate function of Rp configuration. Results presented in this report clearly indicate that the stability of hybrids formed between octa(thymidine methanephosphonate) and pentadecadeoxyriboadenylic acid depends on the stereochemistry of each internucleotide methanephosphonate function and strongly suggests that stereoselective synthesis of P-chiral oligonucleotide analogues is an important goal.

Chemical Phenomena↗
PubMed2003

Direct determination of monolinuron, linuron and chlorbromuron residues in potato samples by gas chromatography with nitrogen-phosphorus detection.

A gas chromatography with nitrogen-phosphorus detection direct method for methoxyurea herbicide determination in powdered potato and fresh potato samples has been developed. A previous study of the thermal stability of the phenylurea herbicides seems to confirm that the ones containing the methoxy radical, i.e. monolinuron, linuron and chlorbromuron, were stable. The herbicides were extracted from the sample through liquid-liquid extraction with dichloromethane-light petroleum (1:1), followed by solid-phase extraction in a C8 cartridge. The recoveries were in the range 84-95% for powdered potato and 86-101% for fresh potato. The RSD values were less than 10%, at 0.1 microg g(-1) concentration level (n = 4) for both types of samples. Detection limits of the method were 7.0-30 ng g(-1) for powdered potato and 6.0-50 ng g(-1) for fresh potato.

Chromatography, Gas↗
PubMed1998

Reappraisal of the quantity and nature of renal calcifications and mineral metabolism in the magnesium-deficient rat. Effects of treatment with potassium citrate or the combination magnesium citrate and potassium citrate.

There is an urgent need for drugs capable of inhibiting renal calcifications, nephrocalcinosis and stones included, in humans. Current anticalcification medication is based mainly on alkalinization of the metabolism using potassium-containing citrate alone, despite the fact that calcium stone patients suffer marginally from both magnesium and potassium deficiency. We investigated the anticalcification efficacy of oral potassium citrate versus the combined administration of this drug and magnesium citrate in the magnesium-deficient rat developing corticomedullary nephrocalcinosis and luminal microliths in the long term. Among other things we employed specific stains for calcium and oxalate, light microscopy and element analysis for renal tissue and calcifications, respectively. In addition, minerals in renal tissue, urine and plasma were determined, as well as the state of extracellular calcium homeostasis. Magnesium deficiency caused pure calcium phosphate tissue deposits, containing no magnesium, but no deposition of calcium oxalate in the tubular lumen; tissue magnesium, calcium and phosphorus were increased, and there was marked potassium wastage via urine; despite mild hypercalcemia other signs of hyperparathyroidism were not found. Alkalinization with the two kinds of medication evoked an increase in urinary pH, citrate, and potassium; however, potassium citrate alone tended to aggravate renal concretions, whereas the combination of this drug with magnesium citrate completely prevented concretions. It was concluded that: (1) magnesium deficiency-induced calcifications are oxalate-free and are not sensitive to mobilization by alkalinization with potassium citrate, which might explain the failure of the drug to prevent stone recurrence in clinical stone patients, and (2) the combination of potassium citrate and magnesium citrate, which shows enormous anticalcification efficacy, deserves high priority in clinical trials aimed at evaluating strategies for the prevention of stones.

Animals↗
PubMed1984

Metabolic status of fresh v eye-bank-processed corneas. A phosphorus nuclear magnetic resonance study.

The concentrations of corneal phosphatic metabolites in fresh and eye-bank-processed corneas were measured by phosphorus 31 nuclear magnetic resonance of perchloric acid corneal extracts to determine whether metabolic differences exist between these two corneal preparations. Cat corneas were prepared using an eye-bank protocol, including specular microscopic examination and transport to a distant location. Fresh cat corneas were used as controls. The hexose 6-phosphate resonance band, the nucleoside monophosphate band, the phosphodiesters, and adenosine triphosphate of eye-bank-processed corneas were significantly decreased relative to fresh control corneas. Phosphatic metabolites that significantly increased relative to control corneas included inorganic orthophosphate and phosphocreatine. A calculated corneal tissue-energy index was significantly decreased for eye-bank-processed corneas relative to control. This decline demonstrates a compromise in the metabolic energy status of the tissue and is indicative of a diminished ability of the cornea to maintain its complement of high-energy phosphates.

Adenosine Triphosphate↗
PubMed1990

Light-induced membrane protein phosphorylation in the bovine rod outer segment. A magic angle spinning 31P-NMR study.

Magic angle spinning 31P-NMR (MAS 31P-NMR) spectra of bovine rod outer segments, unphosphorylated and phosphorylated, were obtained. In the phosphorylated samples the spectra showed new resonances not assignable to phospholipids. These signals were present only when stimulation of receptor phosphorylation occurred. These resonances were not due to exogenous, soluble phosphorus-containing compounds. Limited proteolysis to remove the carboxyl-terminal region of the photoreceptor that contains the phosphorylation sites removed these resonances. The chemical shifts were in the usual range for serine phosphate and threonine phosphate. The pKa obtained from a pH titration of the 31P chemical shift was typical of serine phosphate. Therefore, these 31P-NMR resonances were assigned to the phosphorylation sites on membrane proteins in the rod outer segment disk membranes. Static 31P-NMR measurements revealed that at least some of these sites gave rise to relatively narrow resonances, indicative of considerable motional freedom of the carboxyl-terminal segment of the photoreceptor when phosphorylated. These data indicate that it is possible to study phosphorylation sites on membrane proteins using MAS 31P-NMR, and that using in vivo 31P 'spin labelling' one can study directly and selectively regions of receptors crucial to receptor function.

Animals↗
PubMed1996

Depletion of high energy phosphate compouds in the tumor-bearing state and reversal after tumor resection.

BACKGROUND: Cancer cachexia is a syndrome manifested by a variety of metabolic abnormalities that include depletion of host energy stores. We studied liver and skeletal muscle high energy phosphate compounds, inorganic phosphorus (Pi), and the energy charge in tumor-bearing (TB), pair fed non-tumor-bearing (NTB), and tumor-bearing resected (RES) rats. METHODS: F344 rats were randomized into TB (n = 13), NTB (n = 13), and RES (n = 5) groups. On day 0, the flanks of the TB and RES animals were injected with 1 x 10(7)n methylcholanthrene (MCA)-induced sarcoma cells. On day 19, TB and NTB rat liver and skeletal muscle were analyzed for adenine nucleotides, phosphocreatine, and Pi, and RES animals underwent tumor resection followed by tissue analysis 10 days later. RESULTS: Although the liver adenylate energy charge was maintained, the level of liver adenosine monophosphate was significantly increased and the liver adenosine diphosphate level was decreased in the TB animals (3.55 +/- 0.6, 3.70 +/- 0.3 mumoles/gm dry weight, p < 0.05, p = 0.05, respectively) when compared with the NTB animals (3.06 +/- 0.4, 4.00 +/- 0.5 mumoles/gm dry weight, respectively). Muscle adenosine diphosphate levels were significantly decreased in the TB animals (1.57 +/- 0.7 mumoles/gm dry weight) as compared with NTB animals (2.23 +/- 0.7 mumoles/gm dry weight, p < 0.05). In addition, muscle adenosine triphosphate, phosphocreatine, and phosphocreatine/adenosine triphosphate ratios were significantly decreased in TB animals (19.94 +/- 4.5, 81.51 +/- 12.8, and 4.20 +/- 0.8 mumoles/gm dry weight, respectively) as compared with NTB animals (24.44 +/- 1.9, 116.72 +/- 7.5, and 4.81 +/- 0.4 mumoles/gm dry weight, respectively, p < 0.05) and RES animals (24.08 +/- 3.3, 124.10 +/- 12.2, and 5.19 +/- 0.5 mumoles/gm dry weight, respectively, p < 0.05). CONCLUSIONS: These alterations in high energy phosphate compounds in liver and skeletal muscle indicate that although the energy charge is maintained, energy depletion occurs early in the tumor-bearing state. These changes are tumor specific, not related to anorexia, and revert to non-tumor-bearing levels after tumor resection.

Adenosine Triphosphate↗
PubMed2002

Long-term (1956-1999) dynamics of phosphorus in a shallow, subtropical Chinese lake with the possible effects of cyanobacterial blooms.

This paper describes the long-term dynamics of phosphorus concentrations in both the lake water and the sediment in a subtropical Chinese lake, Lake Donghu. The total phosphorus (TP) concentration in the lake water experienced an upward trend from the 1950s, and peaked in 1983/1984, but declined obviously afterwards. From the 1950s to thel990s. TP content in the upper 10cm sediment of the lake increased steadily from 0.307 to 1.68mg P gDW(-1) at Station I and from 0.151 to 0.89 mg P g DW(-1) at Station II, respectively. The TP increase in the lake water before mid-1980s was mainly attributed to the massive input of sewage P. The outbreak of cyanobacterial blooms coincided with the peaks of TP and Orthophosphate (PO4-P) in the water in mid-1980s, and the maximum TP of the water reached as high as 1.349mg/l at Station I and 0.757mg/l at Station II (in 1984), respectively. The declines of TP and P04-P in the water after mid-1980s was coincident with the disappearance of cyanobacterial bloom.

China↗
PubMed1987

31P nuclear magnetic resonance (NMR) spectroscopy of brain in aging and Alzheimer's disease.

Phosphorus-31 (31P) NMR is proving to be a powerful analytical method for investigating molecular/metabolic issues in neural tissues. Recent studies have demonstrated high levels of phosphomonoesters and phosphodiesters in mammalian brain, and revealed the influence of brain maturation, development, and aging on these levels. Preliminary studies in Alzheimer's disease have demonstrated elevated levels of phosphomonoesters and phosphodiesters in the areas of Alzheimer's brain which exhibit neuropathological changes. Moreover, phosphomonoester levels were also elevated in areas of Alzheimer's brain that were devoid of neuropathological changes. These findings suggest that the phosphomonoester elevations in Alzheimer's brain antedate changes in cellular morphology and structure. Abnormalities in protein kinase function could potentially explain these findings, as well as the reported hyperphosphorylation of tau protein in Alzheimer's brain. Recent studies from this laboratory suggest that aluminum could also be involved in the changes in phosphomonoesters and phosphodiesters.

Aging↗
PubMed2005

Metal concentrations and mycorrhizal status of plants colonizing copper mine tailings: potential for revegetation.

A field survey of metal concentrations and mycorrhizal status of plants growing on copper mine tailings was conducted in Anhui Province, China. Available phosphorus and organic matter in the tailings were very low. High concentrations of Pb, Zn, As and Cd as well as Cu were observed on some sites. The dominant plants growing on mine tailings belonged to the families Gramineae and Compositae, and the most widely distributed plant species were Imperata cylindrica, Cynodon dactylon and Paspalum distichum. Coreopsis drummondii also grew well on the arid sites but not on wet sites. Very low or zero arbuscular mycorrhizal (AM) fungal colonization was observed in most of the plants, but extensive mycorrhizal colonization was recorded in the roots of C. drummondii and C. dactylon. Metal concentrations in plant tissues indicated that I. cylindrica and P. distichum utilized avoidance mechanisms to survive at high metal concentrations. The investigation suggests that remediation and revegetation of heavy metal contaminated sites might be facilitated by selection of tolerant plant species. Isolation of tolerant AM fungi may also be warranted.

Arsenic↗
PubMed1990

Determination of the toxicity of cyclotriphosphazene hydraulic fluid by 21-day repeated inhalation and dermal exposure.

Cyclotriphosphazene (CTP) ester is one of a series of compounds developed for use as a fire-resistant hydraulic fluid. The most significant routes of industrial exposure to hydraulic fluids are dermal, because of spills or leaks, and aerosol inhalation from pressurized system leaks. This study was designed to evaluate the toxic effects associated with repeated or continuous exposure to CTP by both dermal and inhalation routes. Male and female Fischer 344 (F-344) rats were exposed for 3 weeks to air alone, or to 0.25, 0.50, or 1.00 mg CTP/L. No deaths or signs of toxic stress occurred during the exposure period. A depression in mean body weight gain and increases in numbers of pulmonary alveolar macrophages and renal hyaline droplets were noted in both genders. Male and female New Zealand White (NZW) rabbits were treated dermally for 3 weeks with mineral oil, or 0.25, 0.50, or 1.00 g CTP/kg. No toxic effects were noted in either gender of rabbits.

Administration, Cutaneous↗
PubMed2006

A niobaziridine hydride system for white phosphorus or dinitrogen activation and N- or P-atom transfer.

This short review describes a breakthrough embodied by the synthesis of a niobaziridine hydride complex. This reactive entity reacts directly with white phosphorus to provide a bridging diphosphorus diniobium complex that upon reduction splits to afford a terminal niobium phosphide anion, isolated as its sodium salt. Reactions of the latter with acid chlorides constitute a new synthesis of phosphaalkynes, while treatment with chlorodiorganophosphanes leads to complexed 1,1-diorganophosphanylphosphinidene systems. Additionally, reactions of the sodium salt of the niobium phosphide anion with divalent main group element salts (E = Ge, Sn, or Pb) provide complexed triatomic EP2 triangles. Dinitrogen cleavage was realized via reduction of a heterodinuclear niobium/molybdenum dinitrogen complex, and this provided an entry to a nitrogen-15 labeled terminal nitride anion of niobium as its sodium salt. In a fashion analogous to the aforementioned phosphaalkyne synthesis, acid chlorides are transformed upon reaction with the niobium nitride anion into corresponding nitrogen-15 labeled organic nitriles. Complete synthetic cycles are achieved in both the phosphaalkyne and the organic nitrile syntheses, as the oxoniobium(v) byproduct can be recycled in high yield to the title niobaziridine hydride complex.

Alkynes↗
PubMed1983

Phosphatic metabolites of the intact cornea by phosphorus-31 nuclear magnetic resonance.

The principal low molecular weight phosphatic metabolites of the intact cornea were identified and quantitated nondestructively by phosphorus-31 nuclear magnetic resonance (P-31 NMR) spectroscopy. As part of this analytical procedure, the intracorneal pH was approximated from the resonance shift position of inorganic orthophosphate. In addition the metabolic and pH stability of incubated corneas at 37 C in MK medium was evaluated during an 8-hr time course and compared to similar dynamic analyses performed on corneas with denuded endothelium. Perchloric acid extracts prepared from these same corneas were analyzed by P-31 NMR to verify the metabolite peak assignments and to quantitate the concentrations of minor corneal metabolites. The concentrations of phosphatic metabolites of the cornea, including three previously unidentified phosphorus-containing substances, were determined for freshly excised corneas. The initial corneal spectroscopic profile was not altered by removal of the endothelium. At 37 C the MK media-incubated intact whole corneas experienced a time-dependent decline in ATP levels with a concomitant rise in inorganic orthophosphate; however, the tissue levels of the other principal phosphatic metabolites were not altered by prolonged incubation. In contrast, removal of the endothelial layer of the cornea-induced progressive metabolic deterioration of intact corneas characterized, most prominantly, by time-dependent declines in ATP and glycerol 3-phosphorylcholine levels and concomitant increases in ADP and inorganic orthophosphate levels relative to intact whole corneas. This study has established the feasibility of monitoring the metabolic status of intact rabbit corneas nondestructively and noninvasively. As such, P-31 NMR spectroscopy offers a promising method that may enable analysis of the metabolic viability of intact human donor corneas to provide a basis for selecting donor corneas for transplantation.

Adenosine Triphosphate↗
PubMed1988

31P nuclear magnetic resonance determination of changes in energy state in lung preservation.

The significance of dynamic changes in energy state during lung harvesting and preservation has not been extensively studied. Phosphorus 31 nuclear magnetic resonance spectra at 81 MHz were obtained from degassed rabbit lungs. Changes in the adenosine 5'-triphosphate-to-inorganic phosphate peak-intensity ratios were used to measure changes in energy state. Two groups of rabbit preparations were studied to evaluate the effect of hypothermia during the initial 120 minutes of harvesting (n = 8 at 36 degrees C and n = 5 at 4 degrees C). The significance of these changes was assessed in a second experiment in which lungs were reperfused in vitro at selected intervals of hypothermia (5, 12, and 24 hours) and assessed for injury. Hypothermic preservation sustained a significantly higher energy state. The depletion of energy state was correlated with injury, particularly as measured by lung edema (r2 = -0.715). Short periods of warm ischemia (30 minutes) result in a significant depletion of energy state, which may be a component of pulmonary injury during harvesting and preservation.

Adenosine Triphosphate↗
PubMed2000

The 31P-NMR stress test: an approach for detecting myocardial ischemia.

31P-NMR spectroscopy has the potential to assess myocardial damage directly and noninvasively by ascertaining the relative abundances of phosphorus-containing compounds relevant to metabolism under stress conditions. Decrease in the PCr/ATP ratio during exercise is an indicator of the level of stress to which the myocardium is subject. This ratio will remain constant under mild to moderate exercise conditions in a healthy subject, but may show a precipitous decrease even under mild exercise when regions of the myocardium are ischemic. The studies examined here indicate that cardiac patients with some forms of ischemia showed a PCr/ATP ratio decrease even under light exercise, while no decrease was observed in patients whose heart disease was known to be nonischemic. Hypertension and nonstenotic chest pain in women can, in some cases, produce a decrease in PCr/ATP ratio. Only the hypertensive patients showed a significant difference in the prestress PCr/ATP ratio when compared with controls. These studies suggest that 31P-NMR spectroscopy before and during mild exercise in the bore of the magnet can be a useful indicator of the presence or absence of an ischemic component to myocardial disorder.

Adenosine Triphosphate↗
PubMed1988

A new microvascular model for noninvasive nuclear magnetic resonance spectroscopy of the transplanted kidney.

The cellular biology of graft rejection is not well understood. Phosphorus-31 nuclear magnetic resonance (31P NMR) spectroscopy is a new noninvasive technique for the measurement of intracellular pH and relative amounts of phosphorus-containing compounds, such as adenosine triphosphate (ATP), inorganic phosphate, phosphocreatine, and sugar phosphates, in any tissue from which a clear signal can be obtained. Biochemical analysis of such precision, without the need for tissue destruction, represents an unusual opportunity for analysis of in vivo cellular metabolism under varying conditions, including graft rejection. 31P NMR study of intra-abdominal viscera has not been feasible in most laboratories without laparotomy because of signal interference from abdominal wall muscle. In this study, to eliminate this interference, a rat kidney was transplanted to the groin, where it could be serially studied without overlying skeletal muscle. This new vascular technique was successful in 11 of 11 attempts and maintained normal serum creatinines in 10 chronic survivors after removal of both native kidneys. The 31P NMR spectroscopic signal from the groin kidney is clear and highly reproducible. This new microvascular model will make it possible to carry out noninvasive long-term spectroscopic studies that could potentially identify a reliable marker for allograft rejection.

Adenosine Triphosphate↗