Differential extractability of creatine phosphate and ATP from cardiac muscle with ethanol and perchloric acid solution.

To compare the extractability of creatine phosphate with that of ATP by alcohol extraction, both compounds were extracted from normal perfused rat heart tissues by using various stepwise concentrations of ethanol and 0.4 M HClO4. Powdered samples (6-15 mg wet wt) from the freeze-clamped tissues were homogenized in 2 ml of the ethanol solutions. After centrifugation, the supernatant was removed; each centrifuged sediment was rehomogenized with 2 ml of 0.4 M HClO4 and centrifuged. The supernatant was neutralized with 0.4 m KHCO3. The same powdered samples were directly homogenized with 2 ml of 0.4 M HClO4 and treated in the same manner. Only a small amount of ATP in the tissues was extracted by an 85% or higher concentration of ethanol. Further, about 13% of the tissue ATP was not extractable by the subsequent perchloric acid extraction. In contrast to ATP, creatine phosphate in the tissues was partially extracted by 95% ethanol and nearly all of the tissue creatine phosphate was extracted by 70% ethanol. The total creatine phosphate obtained by 70% ethanol and by subsequent perchloric acid extraction was significantly higher than that obtained by direct perchloric acid extraction. From these results, it was concluded that the extractability of creatine phosphate in the tissue by alcohol extraction is clearly different from that of ATP. Additionally, the stepwise extraction is recommended as a useful method for the extraction of energy metabolites in perfused rat heart tissue.     

The content of pyridoxal coenzymes in the brain and liver of rats exposed to a single irradiation with x-rays

A study was made of the effect of a single exposure of rats to 0.4 Gy X-radiation on the content of pyridoxal phosphate and pyridoxamine phosphate in gray and white brain substances and liver. At the same time changes were noted in the activity of pyridoxal kinase in the tissues under study.     

Survey of normal appearing mouse strain which lacks enzyme and NAD+-linked glycerol phosphate dehydrogenase: Normal pancreatic beta cell function,but abnormal metabolite pattern in skeltal muscle

We studied a mouse doubly homozygous for mutations in the genes encoding malic enzyme (EC1.1.1.40) and cytosolic glycerol phosphate dehydrogenase (EC 1.1.1.8) (cGPD). This mouse, which we call the mmgg mouse and which is the product of intercrosses between the Mod-1 mouse and the BALB/cHeA mouse, lacks activity of both enzymes. Like both parental strains the mmgg mouse is completely normal in appearance. cGPD is one of the two enzymes that catalyze the reactions of the glycerol phosphate shuttle. The activity of the other enzyme of the glycerol phosphate shuttle, mitochondrial glycerol phosphate dehydrogenase (EC 1.1.99.5) (mGPD), is abundant in tissues, such as brain, skeletal muscle and the pancreatic islet, suggesting that the glycerol phosphate shuttle is important in these tissues which rapidly metabolize glucose. Cytosolic malic enzyme activity is important for shuttles which transport NADPH equivalents from mitochondria to the cytosol. The major finding of the study was a highly abnormal metabolite pattern in tissues of the mmgg mouse suggesting a block in the glycerol phosphate shuttle due to cGPD deficiency. The metabolite pattern did not suggest that malic enzyme deficiency caused an abnormality. Tissue levels of glycerol phosphate (low) and dihydroxyacetone phosphate (high) were only abnormal in skeletal muscle. Glycolytic intermediates, situated at or before the triose phosphates in the pathway, such as fructose bisphosphate and glyceraldehyde phosphate were increased depending on the tissue. Taken together with previous extensive data on the mouse deficient only in cGPD this suggests a block in glycolysis at the step catalyzed by glyceraldehyde phosphate dehydrogenase caused by an abnormally low NAD/NADH ratio resulting from a nonfunctional glycerol phosphate shuttle. Consistent with this idea the lactate/pyruvate ratio was high in skeletal muscle signifying a low cytosolic NAD/NADH ratio. The mmgg mouse was normal in all other factors studied including blood glucose and serum insulin levels, pancreatic islet mass, insulin release from isolated pancreatic islets, as well as the activities of five metabolic enzymes, including mGPD, in liver, kidney, skeletal muscle and pancreatic islets. cGPD enzyme activity was undetectable in pancreatic islets, 0.5% of normal in liver, and 2.1% of normal in kidney and skeletal muscle. Malic enzyme activity was undetectable in these same tissues.     

Histochemical Demonstration of Endogenous Dehydrogenase Systems by Supravital Perfusion

Endogenous dehydrogenase activity is demonstrated in fresh, intact organs by supravital perfusion with a tetrazolium solution. The animal is first injected intravenously with 1.5 mg Heparin/100 gm body weight. It is then anesthetized and a fine polyethylene cannula (PE50, Intramedic) is inserted into a major artery and secured with a ligature. An initial perfusion with warm (37°C) M/20 phosphate buffer (pH 7.6) to remove the blood from the tissues is followed by a 10 min perfusion with the same kind of buffer to which has been added 0.25% neotetrazolium chloride (Dajac Laboratories). The tetrazolium solution is delivered to the tissue at the rate of 1 ml/minute. A final perfusion with 10% formalin in warm phosphate buffer (pH 7.6) flushes and fixes the tissues. Frozen sections can then be cut and mounted in glycerol jelly. Fine, colored formazan crystals are deposited at the sites of enzyme activity. The method is simple and yields excellent histochemical preparations.     

A Combined Alkaline Phosphatase-Pas Staining Method

Gomori's calcium phosphate method for alkaline phosphatase has been combined with the periodic acid-Schiff reaction on the same section. Paraffin sections of both formalin and alcohol fixed tissues have been employed. The technic is recommended as a selective staining procedure rather than a specific histochemical method. The Gormori alkaline phosphatase-PAS method has been compared with the silver alkaline phosphatase-PAS method developed by Moffat.     

Expression of FGF23 is correlated with serum phosphate level in isolated fibrous dysplasia

Fibrous dysplasia (FD) patients sometimes suffer from concomitant hypophosphatemic rickets/osteomalacia, resulting from renal phosphate wasting. It was recently reported that FD tissue in the patients with McCune-Albright syndrome (MAS) expressed fibroblast growth factor-23 (FGF-23), which is now known to be as a pathogenic phosphaturic factor in patients with oncogenic osteomalacia and X-linked hypophosphatemic rickets. Since it remains controversial whether serum phosphate levels are influenced by FGF23 expressions in FD tissue, isolated FD patients without MAS syndrome were examined for the relationship between FGF23 expressions, circulating levels of FGF-23 and phosphate to negate the effects of MAS-associated endocrine abnormalities on serum phosphate. Eighteen paraffin embedded FD tissues and 2 frozen tissues were obtained for the study. Sixteen of 18 isolated FD tissues were successfully analyzed GNAS gene, which exhibited activated mutations observed in MAS. Eight of 16 FD tissues, which exhibited GNAS mutations, revealed positive staining for FGF-23. These evidence indicate that postzygotic activated mutations of GNAS is necessary for the FD tissue formation by mosaic distribution of mutated osteogenic cell lineage, but is not sufficient to elevate FGF23 expression causing generalized osteomalacia with severe renal phosphate wasting. The expression level of FGF23 in isolated FD tissue with hypophosphatemic osteomalacia determined by real-time PCR was abundant close to the levels in OOM tumors. Osteoblasts/osteocytes in woven bone were predominant source of circulating FGF-23 in FD tissues by immunohistochemistry. A negative correlation of the intensity of FGF-23 staining with serum inorganic phosphate levels indicated that the expression of FGF23 in focal FD tissues could be a prominent determinant of serum phosphate levels in isolated FD patient. These data provide novel insights into the regulatory mechanism of serum inorganic phosphate levels in isolated FD patients and extend the notion that FGF-23 originating from FD tissue may cause hypophosphatemia not only in isolated FD patients but also in the patients with MAS syndrome.     

The relative utilization of the acyl dihydroxyacetone phosphate and glycerol phosphate pathways for synthesis of glycerolipids in various tumors and normal tissues.

Rates of phosphatidate synthesis from dihydroxyacetone phosphate via acyl dihydroxyacetone phosphate or glycerol phosphate are compared in homogenates of 13 tissues, most of which are deficient in glycerol phosphate dehydrogenase (EC 1.1.1.8). In all tissues examined, dihydroxyacetone phosphate entered phosphatidate more rapidly via acyl dihydroxyacetone phosphate than via glycerol phosphate. Tissues with a relatively low rate of phosphatidate synthesis via glycerol phosphate, showed no compensating increase in the rate of synthesis via acyl dihydroxyacetone phosphate. The rates at which tissue homogenates synthesize phosphatidate from dihydroxyacetone phosphate via glycerol phosphate increase as glycerol phosphate dehydrongenase increase. Both glycerol phosphate dehydrogenase and glycerol phosphate: acyl CoA acyltransferase (EC 2.3.1.15) are more active than dihydroxyacetone phosphate : acyl CoA acyltransferase (EC 2.3.1.42). Thus, all the tissue homogenates possessed an apparently greater capability to synthesize phosphatidate via glycerol phosphate than via acyl dihydroxyacetone phosphate, but did not express this potential. This result is discussed in relation to in vivo substrate limitations.     

Possible influence of gonadotrophins on formation in vivo of pyridoxal phosphate

FSH administered to normal rats increased the activity of pyridoxine phosphate oxidase of both liver and kidney and, consequently, pyridoxal phosphate levels in these tissues were elevated. LH administration, on the other hand, decreased the activity of pyridoxine phosphate oxidase, resulting in diminished pyridoxal phosphate level in the tissues. The stimulatory effect of FSH on the activity of liver and kidney pyridoxine phosphate oxidase was not observed in castrated-adrenalectomised rats unless supplemented with cortisone and testosterone, respectively. Puromycin treatment prevented the FSH-induced rise in the activity of liver and kidney pyridoxine phosphate oxidases. It is suggested that FSH stimulates the activity of liver and kidney pyridoxine phosphate oxidase by increasing the synthesis of apoproteins of the enzyme, and the effect of FSH on liver is dependent on the presence of adrenal corticoids while the presence of testosterone is a prerequisite for the FSH to have its effect on kidney pyridoxine phosphate oxidase.     

New technique for processing paraffin-embedded tissue for Y chromosome fluorescence identification of trophoblastic disease

A new reprocessing technique for Y chromosome fluorescent body (q 12 region) detection of trophoblastic disease in previously paraffin-embedded tissues is described. Deparaffinized sections were treated with pronase and trypsin for digestion, followed by hydrolysis with HCl and acetic acid, staining with quinacrine hydrochloride fluorochrome and mounting in S?rensen's phosphate buffer (pH 5.5). Use of the technique resulted in sufficient fluorescence quality and better accuracy for Y and X heterochromatin scoring. The technique yielded the same results in retrospective formalin-fixed, paraffin-embedded trophoblastic specimens as in fresh tissues. The combinations of enzymes and acids and the dosages necessary for optimal results are discussed.     

Accumulation of phosphate, sulfate and sucrose by excised Phloem tissues

Excised petiolar vascular bundles and excised phloem tissues have been shown to take up phosphate, sulfate and sucrose by a true accumulation process and against high concentration ratios. Phosphate was accumulated principally as inorganic phosphate, and sucrose principally as sucrose. The rates of accumulation of the 3 solutes into the phloem-containing tissues were from 4 to 35 times higher than into comparable parenchyma tissue. It is suggested that this active accumulation mechanism plays an important role in the phenomenon of phloem transport.

The excised vascular, phloem and parenchyma tissues show an aging phenomenon: aerating the excised tissues for 18 hours prior to their use causes marked changes in the accumulatory behavior of the tissue. The data suggest that 1 phosphate accumulation system of low affinity but high capacity exists in fresh tissue, and that aging allows the development of a second, additional phosphate accumulation mechanism of high affinity and low capacity. A possible role in the control of phosphate movement is suggested.

     

Attività UDPG pirofosfatasica in Cucurbita e suo possibile rapporto con l'utilizzazione del galattosio

Abstract

UDPG-PYROPHOSMIATASE ACTIVITY IN CUCURBITA AND ITS POSSIBLE ROLE IN GALACTOSE UTILIZATION. — Preparations obtained by ammonium sulfate precipitation from homogenates of Cucurbita maxima tissues catalyze the hydrolysis of UDPG to UMP and Gl-l-P. The same tissues contain all the enzymes implicated in galactose metabolism, with the exception of Gal-l-P-uridyltransferase. Therefore the possibility is suggested that the UDPG-pyrophosphatase found may play an important role in the conversion of galactose to the phosphate esters of glucose. This suggestion is also supported by the finding that the amount of activity found in homogenates could account for the respiratory activity of the tissues if glucose arising from galactose were the main respiratory substrate.     

Synthesis of nucleotides by phosphotransferase from human tissues

Several human tissues (prostate greater than liver greater than kidney greater than spleen) contain phosphotransferase capable of synthesizing nucleoside monophosphate by low-energy phosphate transfer to pyrimidines, purines as well as ribo- and deoxyribonucleosides. Phenyl phosphate, AMP, TMP, GMP and IMP were good phosphate donors while thymidine, deoxyadenosine and deoxyuridine are the most effectively utilized substrates. The phosphatransferase activity is present in all particulate fractions with most activity in microsomes. The enzyme is being purified from human tissues.     

Alpha-tocopheryl phosphate: a novel, natural form of vitamin E

We have detected alpha-tocopheryl phosphate in biological tissues including liver and adipose tissue, as well as in a variety of foods, suggesting a ubiquitous presence in animal and plant tissue. Alpha-tocopheryl phosphate is a water-soluble molecule that is resistant to both acid and alkaline hydrolysis, making it undetectable using standard assays for vitamin E. A new method was therefore developed to allow the extraction of both alpha-tocopheryl phosphate and alpha-tocopherol from a single specimen. We used ESMS to detect endogenous alpha-tocopheryl phosphate in biological samples that also contained alpha-tocopherol. Due to the significance of these findings, further proof was required to unequivocally demonstrate the presence of endogenous alpha-tocopheryl phosphate in biological samples. Four independent methods of analysis were examined: HPLC, LCMS, LCMS/MS, and GCMS. Alpha-tocopherol phosphate was identified in all instances by comparison between standard alpha-tocopheryl phosphate and extracts of biological tissues. The results show that alpha-tocopheryl phosphate is a natural form of vitamin E. The discovery of endogenous alpha-tocopheryl phosphate has implications for the expanding knowledge of the roles of alpha-tocopherol in biological systems.     

The use of a transport medium (L15M15) for bulk tissue storage and retention of viability

Twenty-five human or mouse tissue samples, some up to 8×4×2 cm, were immersed in a special transport medium (TM), L15M15, up to 7 days before being processed or placed in tissue culture. To test the efficacy of this medium, we concurrently placed pieces of the same tissues in a sterile phosphate buffered solution (PBS). We also tested the preservative capabilities of TM and PBS at room temperature and with refrigeration. Differences between TM and PBS are demonstrated, which are more pronounced using room temperature up to 4 days time. The tissues stored in TM show fewer degenerative or autolytic changes than the same tissue stored in PBS under identical conditions. Using regrigeration further enhanced the preservative qualities of TM up to 4 days, but not PBS. There were no obvious differences between tissues stored in TM and PBS with refrigeration after 7 days. We conclude that transport medium L15M15 is a useful medium for preserving tissue viability, especially large tissue samples, up to 4 days, especially if refrigerated.     

Development of a label-free assay for sodium-dependent phosphate transporter NaPi-IIb

The most widely used assay format for characterizing plasma membrane transporter activity measures accumulation of radiolabeled substrates in tissues or cells expressing the transporters. This assay format had limitations and disadvantages; therefore, there was an unmet need for development of a homogeneous, nonradioactive assay for membrane transporter proteins. In this report, the authors describe the development of a label-free homogeneous assay for the sodium-dependent phosphate transporter NaPi-IIb using the Epic system. The addition of phosphate stimulated a dynamic mass redistribution (DMR) profile unique to cells expressing NaPi-IIb but not on parental cells. This DMR profile was phosphate specific because sulfate or buffer alone did not elicit the same response. Furthermore, the DMR response observed was phosphate and sodium dependent, with Km values in the micromolar and millimolar range, respectively. A known NaPi-IIb noncompetitive inhibitor was shown to completely inhibit the phosphate-stimulated DMR response, suggesting that this observed DMR response is an NaPi-IIb-mediated cellular event. The results demonstrate that a novel label-free assay was developed for studying transporter-mediated cellular activity, and this DMR assay platform could be applicable to other membrane transporter proteins.     

Effect of ischemia on NMR detection of phosphorylated metabolites in the intact rat heart

Phosphorus NMR spectroscopy is an important technique for the investigation of metabolism in tissues and intact organisms (including man). However, quantitation of the signals from an NMR experiment is difficult because it is not known from which regions of a cell metabolites are detected. It is generally believed that only metabolites free in the cytosol are observed. In this study a comparison of concentration measurements obtained by NMR and after freeze extraction was made in the normoxic and ischemic rat heart. The influence of ischemia was examined because of its potential effect on the level of phosphate metabolites in various compartments. The same fraction of ATP always appears visible to NMR, whereas inorganic phosphate is largely NMR invisible until after a period of ischemia and the phosphomonoesters are only partially observed early in ischemia.     

Response to Anoxia in Rice and Wheat Seedlings: Changes in the pH of Intracellular Compartments, Glucose-6-Phosphate Level, and Metabolic Rate

³¹P nuclear magnetic resonance spectroscopy was used to measure intracellular pH in living tissues. Oxygen deprivation caused fast cytoplasmic acidification from pH 7.4 to 7.0 in shoots of rice, Oryza sativa L. var arborio, a species highly resistant to anoxia. Acidification was complete after 10 minutes of anoxia. Alkalinization of both cytosplasm and vacuole followed thereafter. In the anoxia intolerant wheat shoots, Triticum aestivum L. var MEK, the same treatment caused a sharper cytoplasmic acidification, from pH 7.4 to 6.6, which occurred during a period of 2 hours. Cytoplasmic acidification continued with progress of anoxia and there was no vacuolar alkalinization comparable to the one observed in rice. In wheat oxyen, withdrawal also caused the reduction of both glucose-6-phosphate level and of metabolic rate. It also induced heavy losses of inorganic phosphate from tissues. Conversely, in rice, glucose-6-phosphate level and metabolic rate were increased and inorganic phosphate leakage from tissues was completely absent. These results are discussed in relation to the mechanisms of plant resistance to anoxia.     

Application of chromatography to the analysis of phosphate compounds in small biopsy tissue samples in different experimental conditions

Biochemical analysis of tissue biopsy samples for evaluation of the phosphate compounds of metabolism has been limited to a large tissue sample size, and thus, repeated biopsies on the same animal or patient are too difficult to obtain. We report here the use of the Bessman analyzer: anion exchange chromatography followed by automatic phosphorus analysis on small tissue samples. The method described here enables the repetitive measurement of high-energy phosphate compounds (ATP, ADP, AMP, creatine phosphate (CP], inorganic phosphorus (Pi), sugar phosphorus (glucose 6-phosphate and fructose 6-phosphate), and inosine monophosphate (IMP), an indicator of adequate biopsy processing and sample preparation. The data also emphasize the importance of adequate oxygenation of the experimental animal or patient. This method is easy to apply in almost any clinically oriented research laboratory for the study of needle biopsies from human and animal tissues and permits a more convenient and complete investigation of the high-energy phosphate compounds of intermediary metabolism than do the methods of firefly luminescence or the multiple, NAD-linked enzymatic systems required for the necessary sensitivity.     

Measurement of uridine diphosphate glucuronic acid concentrations and synthesis in animal tissues

1. A method for the isolation from animal tissues of UDP-glucuronic acid by one-dimensional paper chromatography is described and its concentrations in some tissues of several species of vertebrates are reported; the incorporation of [³²P]-phosphate into UDP-glucuronic acid in vivo was also investigated. 2. The concentration of UDP-glucuronic acid was higher in the liver of rats, rabbits and guinea pigs than in the same tissue of some species of birds, amphibia and fishes; also, the concentration of UDP-glucuronic acid in rat liver, kidney and small intestine was several times lower than that of the same tissues of guinea pigs. 3. The rate of [³²P]-phosphate incorporation into UDP-glucuronic acid was very high in rat liver and kidney and almost reached equilibrium with the radioactivity of UDP-glucose 30min after the administration of the [³²P]phosphate.