Different energy metabolism in two human small cell lung cancer subpopulations examined by 31P magnetic resonance spectroscopy and biochemical analysis in vivo and in vitro

Two human small cell lung cancer tumor lines, maintained as solid tumor xenografts on nude mice and as in vitro cell cultures, were studied by in vivo 31P magnetic resonance spectroscopy and by biochemical analysis of extracts of solid tumors and cell cultures. The tumor lines CPH SCCL 54A and CPH SCCL 54B are subpopulations from the same tumor. In solid tumors (n = 125), the ATP/Pi ratio was greater in 54A than in 54B. This was due to a higher ATP level in 54A, whereas there was no difference in Pi, ADP, and AMP. A decrease in ATP/Pi during growth was caused by a decline in ATP, whereas Pi remained unchanged. Small amounts of phosphocreatine were found in the xenografts and in tumor extracts, but not in the cell extracts; correspondingly, there was a low creatine kinase activity in solid tumors and no activity in the cell cultures. Thus, the phosphocreatine content of the solid tumors originated from the stroma. A difference in ATP content between 54A and 54B was also found in cell cultures; hence, the metabolic difference is an intrinsic quality of the malignant cells and is not caused by the host system.

Dibasic amines as competitive ions improve the resolution between polyanionic nucleotides

Aliphatic diamines when used as single ion pairing reagents were capable of resolving 3'-,5'- and 2'-,5'- nucleotidyl diphosphates from one another while conventional ion pairing reagents did not separate these positional isomers. The use of 1,2-diamines resulted in the greatest resolution while increasing spacing between the amino groups progressively reduced the resolution while increasing the retention volume. A competitive ion pairing system was also developed using triethylamine as an additional ion pairing reagent. Using this system ethylenediamine, 1,2- and 1,3-diaminopropane were nearly equivalent in their ability to resolve adenosine 3'-phosphate 5'-phosphate, from adenosine 2'-phosphate 5'-phosphate, and adenosine 3'-phosphate 5'-beta-methylenephosphosulfate (3'-mePAPS) from adenosine 2'-phosphate 5'-beta-methylenephosphosulfate (2'-mePAPS), respectively. The ability to easily resolve these positional isomers allows the use of a more simplified synthetic procedure that does not involve the use selective protecting groups to specifically phosphorylate the 2' or 3' hydroxyl group. We have used this procedure on a semipreparative scale to obtain small quantities of both mePAPS and 2'-mePAPS for use in enzymatic studies.

Visibility of ATP and ADP in freeze-trapped tissue from perfused rat liver during normoxia and ischemia using 31P-cryo-NMR

The visibility of ATP and ADP to NMR was studied by comparing simultaneous measurements of freeze-trapped tissue sections from perfused rat liver under normoxia and ischemia using a modified 31P-cryo-NMR method and biochemical assay. The 31P-cryo-NMR method provides good time resolution and allows the quantitation of absolute metabolite concentrations. Prior to 31P-cryo-NMR measurements, freeze-trapped tissues were thawed in the presence of cryoprotectant and EDTA. With this sample preparation procedure, the integrity of the plasma and mitochondrial membranes was not maintained, inducing homogeneous microviscosity and chelation of intracellular divalent cations, thereby increasing the visibility of metabolites compared to the in vivo NMR measurement. With ischemic stress, total cellular ATP concentration decreased significantly (P less than 0.001). While ADP concentrations measured by cryo-NMR and biochemical analysis were consistent during normoxia and ischemia, ATP concentrations measured by cryo-NMR were significantly lower (P less than 0.05) than those obtained by biochemical analysis. The amount of invisible ATP (0.42 +/- 0.10 mumol/g wet weight: mean +/- S.E.) did not change after the induction of ischemia. The results of this study suggest that ATP invisibility to cryo-NMR is not due to compartmentation into regions of high paramagnetic ion concentrations or high microviscosity, but is influenced by other factors.

Bacterial DNA supercoiling and [ATP]/[ADP] ratio: changes associated with salt shock

When Escherichia coli K-12 was shifted from a medium lacking salt to one containing 0.5 M NaCl, both the [ATP]/[ADP] ratio and negative supercoiling of plasmid DNA increased within a few minutes. After about 10 min both declined, eventually reaching a level slightly above that observed with cells growing exponentially in the absence of salt. Since in vitro the [ATP]/[ADP] ratio influences the level of supercoiling generated by gyrase (H. Westerhoff, M. O'Dea, A. Maxwell, and M. Gellert, Cell Biophys. 12:157-181, 1988), the physiological response of supercoiling to salt shock is most easily explained by the sensitivity of gyrase to changes in the intracellular [ATP]/[ADP] ratio. This raises the possibility that the [ATP]/[ADP] ratio is an important factor in the control of supercoiling.

Titrimetric determination of muscle buffering capacity (beta mtitr) in biopsy samples

In vitro titration of muscle homogenates has been used to assess muscle buffering capacity (beta mtitr) in a variety of species. In the present study, factors likely to affect the estimation of beta mtitr were investigated. Also, values of beta mtitr from normal Thoroughbred horses are presented. A non-linear titration curve was obtained with addition of HCl to muscle homogenates. As a result, beta mtitr is expressed as the mumol H+ required to change the pH of 1g of dry muscle or wet muscle from 7.1 to 6.5. An effect of dilution on the initial pH was found below 40 mg wet muscle per ml homogenising reagent (10 mg dry muscle per ml) and on beta mtitr below 10 mg wet muscle. As a result, 40 mg wet muscle or 10 mg dry muscle per ml was chosen as the minimum concentration for determination of beta mtitr. Incubation of homogenates up to 60 mins did not affect beta mtitr significantly. As a mean, beta mtitr in wet muscle was approximately 25 per cent higher compared to dry muscle. The beta mtitr of dry muscle was increased by approximately 18 per cent when HCO3- was added in an amount equivalent to the calculated HCO3- content of wet muscle at rest. The homogenisation process resulted in complete loss of adenosine triphosphate and phosphocreatine with only small changes in adenosine diphosphate and adenosine monophosphate. It was concluded that the estimates of beta mtitr did not include any contribution from 'dynamic' buffering via rephosphorylation of adenosine diphosphate by phosphocreatine, and in dry muscle it was accounted for mainly through physico-chemical buffering by phosphates, proteins and dipeptides. beta mtitr determined in biopsy samples of muscle from 20 Thoroughbred horses ranged from 100.8 to 131.8 mumol H+/g dry muscle pH 7.1 to 6.5 (mean 121.2, sd +/- 7.4).

Changes in glutathione and cellular energy as potential mechanisms of papaverine-induced hepatotoxicity in vitro

The purpose of this study was to elucidate the mechanism of hepatotoxicity of papaverine hydrochloride (papaver) in vitro. To evaluate the role of metabolism in the toxicity of papaver, cells were pretreated with SKF-525A or benzyl imidazole (cytochrome P450 system inhibitors) for 24 hr at 1 x 10(-5) or 1 x 10(-4) M, respectively, or with phenobarbital sodium (cytochrome P450 system inducer) for 3 days at 2 x 10(-3) M. Cells then were exposed to concentrations of papaver ranging from 1 x 10(-5) to 1 x 10(-3) M for 4 to 24 hr. Cytotoxicity was evaluated by enzyme leakage (lactate dehydrogenase) and by energy status of the cells (ATP/ADP). The role of biological reactive intermediates in the toxicity of papaver was investigated by measuring changes in cellular reduced glutathione levels (GSH), by inhibiting GSH synthesis, and by determining the production of lipid peroxidation (LPX). Papaverine produced concentration- and time-dependent increases in enzyme leakage, with significant effects occurring by the 8-hr exposure period. Pretreatment with SKF-525A or benzyl imidazole increased enzyme leakage induced by papaver especially at a later time frame (24 hr), but pretreatment with phenobarbital delayed the onset of cytotoxicity from 8 to 12 hr. Decreases in GSH levels paralleled the time course of enzyme leakage. However, the administration of buthionine sulfoximine to cell cultures dramatically decreased the time by which papaver induced cellular injury (2 hr vs 8 hr). Changes in cellular energy status (ATP/ADP) were also detected earlier than enzyme leakage (4 hr vs 8 hr). In contrast, no significant production of lipid peroxidation was noted in papaver-treated cultures. We suggest that the mechanism of papaver-induced hepatotoxicity may be related to alterations in glutathione balance of the cells and to disruption of energy homeostasis.

Quantitation of high energy phosphate compounds and metabolic significance in the developing dog brain

The phosphate metabolites, PCr, ATP, ADP and inorganic phosphate (Pi), were quantitated in the brain of the newborn, neonatal, juvenile and adult dog to investigate the potential control mechanisms responsible for increased ATP demands during development. The concentrations of PCr and Pi were measured in vivo by MRS using the enzymatic-measured ATP as the internal standard. Phosphocreatine values increased during development from 2.08 mmol/kg wet weight in the 0-2 day newborn to 5.11 mmol/kg wet weight in the adult brain and paralleled the increases in the total creatine pool (PCr + Cr) from 4.12 to 10.05 mmol/kg wet weight. Brain ATP concentrations increased approximately 40% during postnatal development; however, when expressed as intracellular concentration, no increase in ATP was apparent due to the age-dependent decrease in extracellular space. The Pi concentration, estimated by MRS, increased significantly during postnatal development with a range of 1.78 to 2.52 mmol/kg wet wt, then decreased to 1.97 mmol/kg wet weight at adulthood. In those developmental stages where total Pi was measured enzymatically on freeze-clamped tissue, the NMR visible Pi comprised about 48 to 93% of the total, with the highest percentage being visible in the newborn brain. The intracellular pH decreased from 7.21 in the newborn to 7.10 in the adult. With development, the free ADP concentration, calculated from the components of the creatine kinase equilibrium, ranged from 27 to 34 microM. These values are close to the apparent in vitro Km of ADP for oxidative phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet function and interferon alpha-2a treatment in essential thrombocythaemia

The effects of interferon (IFN) alpha-2a treatment on platelet function were evaluated in 20 patients affected by essential thrombocythaemia (ET). Baseline data documented the well-known abnormalities of in vitro platelet aggregation and the constant presence of a delta-storage pool deficiency. The therapy in all patients reduced the platelet count, and in the majority of them caused a partial improvement of in vitro platelet aggregation. Although the mean intraplatelet ADP level improved during treatment, it always remained below the normal range documenting persistence of the delta-storage pool deficiency. The plasma beta-TG levels, which initially were high, significantly decreased during treatment, but the beta-TG ratio and the platelet beta-TG values always remained within the normal range--this suggests an absence of platelet activation either before or during therapy. Our results demonstrate that, despite significantly reducing the platelet count, IFN alpha-2a treatment only partially corrects the qualitative platelet abnormalities in ET.

Methodological problems of direct bioluminescent ADP assay in platelets and erythrocytes

We have developed a method for ADP bioluminescent measurement in platelets and erythrocytes which complements our previous method for ATP assay. When the different parameters of the system under investigation are taken into account, a linea range between 10(-9) and 10(-7) g/ml can be obtained without incubation or troublesome extraction. This makes the method easy and useful for identifying any disease-induced alterations in ATP and/or ADP levels in these blood cells. The data obtained correlate well with those of a bioluminescent method requiring extraction with ethanol/EDTA and incubation, giving the reference intervals of 3.5-5.5 mumol/10(11) PLT for ATP determination and 1.9-3.7 mumol/10(11) PLT for ADP determination in platelets, and 3.2-3.8 mumol/g Hgb for ATP determination and 0.56-0.73 mumol/g Hgb for ADP in erythrocytes. This assay was applied to quality control on blood bags in transfusion centers and proved to be a rapid and reliable method for testing the viability of stored blood cells.

Electrotransfer of [32P]NAD allows labeling of ADP-ribosylated proteins in intact Chinese hamster ovary cells

CHO-K1D cells electroporated in buffers containing [32P]NAD incorporated the label in a voltage-dependent manner. Electroporation with 650 V/cm at 1460 microF in Ham's F12 medium supplemented with 10 mM Hepes, pH 7.1, resulted in a greater than 20-fold increase in [32P]NAD uptake, while decreasing relative cellular survival by only 6%. Exposure of cells to gamma irradiation (20 Gy) prior to electroporation increased the steady-state level of poly(ADP-ribosylated) nuclear proteins two- to four-fold over that of unirradiated control cells. These data indicate that electrotransfer of [32P]NAD is a simple and rapid means of labeling the cellular NAD pool and should prove useful in the analysis of the relationship between poly(ADP-ribosylation) of nuclear proteins and DNA repair.

Phosphate depletion impairs insulin secretion by pancreatic islets

Phosphate depletion (PD) is associated with resistance to the peripheral action of insulin and with glucose intolerance. However, data on the effect of PD on insulin secretion are not consistent, and were derived indirectly by measurements of blood levels of insulin during intravenous glucose tolerance test (IVGTT) or with hyperglycemic clamp technique. Direct evidence for an effect of PD on insulin secretion by pancreatic islets is not available, and the potential mechanisms through which PD may affect insulin secretion are not known. We performed IVGTT, examined in vitro insulin secretion by pancreatic islets, and evaluated various factors involved in insulin secretion in PD and pair weighed (PW) rats. PD animals had fasting hyperglycemia and normal plasma insulin levels, and displayed abnormal IVGTT as compared to PW rats. Both initial and late phases of D-glucose-induced insulin secretion from islets were markedly and significantly (P less than 0.01) lower than from islets of PW rats. In contrast, D-glyceraldehyde-induced insulin release in PD rats was similar to that of PW rats. [H3]2-deoxyglucose uptake by islets and their cyclic AMP content after exposure to D-glucose, D-glyceraldehyde or forskolin were not different among the two groups of animals. Insulin content in PD islets was modestly but significantly (P less than 0.01) higher than PW islets. In PD islets, ATP content and the ATP/ADP ratio at basal state and after incubation with 16.7 mM D-glucose were significantly (P less than 0.01) lower and resting cytosolic calcium was significantly (P less than 0.01) higher than in PW islets.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the invasive potential of superficial bladder cancer by adenosine triphosphate measurement

In order to predict the malignant potential of superficial bladder cancer, in 121 patients with this malignancy adenine nucleotide levels (adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate) and energy charge in bladder cancer cells were determined. The nucleotides were analyzed according to the method of Bücher, and the energy charge was calculated by applying the formula of Atkinson. It was clearly pointed out that superficial bladder tumors, which became invasive and/or metastatic, had higher levels of adenylate compounds than those which became not. Our results show that a high correlation exists between adenine nucleotide content and tumor progression.

Metabolism of fructose-1,6-bisphosphate by mature boar spermatozoa

Mature epididymal boar spermatozoa converted glucose and fructose to carbon dioxide and lactate and maintained high concentrations of ATP. In the presence of (S)-alpha-chlorohydrin these processes were inhibited and there was an accumulation of fructose-1,6-bisphosphate and dihydroxyacetone phosphate. With fructose-1,6-bisphosphate as the substrate, the concentration of ATP was maintained, carbon dioxide was evolved and dihydroxyacetone phosphate accumulated. Cells pre-incubated with (S)-alpha-chlorohydrin did not maintain ATP levels, evolved less carbon dioxide and produced dihydroxyacetone phosphate. Assays of incubates in which fructose-1,6-bisphosphate was used as the substrate showed the presence of equilibrium quantities of fructose-6-phosphate and glucose-6-phosphate which were not detected when either fructose or glucose were used as substrates. [14C]Fructose and [14C]glucose were not produced from [14C]fructose-1,6-bisphosphate in spermatozoal incubates which had or had not been pre-incubated with (S)-alpha-chlorohydrin. Evidence is presented that a high concentration of fructose-1,6-bisphosphate leads to the formation of fructose-6-phosphate and glucose-6-phosphate but not of fructose and/or glucose.

Desmopressin-induced improvement in bleeding times in chronic renal failure patients correlates with platelet serotonin uptake and ATP release

Hemostatic defects resulting in life-threatening hemorrhagic episodes are a common occurrence in the chronic renal failure patient. Hemorrhagic tendencies correlate best with laboratory tests of bleeding times. The identification of a specific hemostatic defect and its role in bleeding dyscrasias has yet to be elucidated. Our studies demonstrate that factor VIII coagulant activity and factor VIII related antigen (vWF:Ag) are normal or greatly elevated in uremic renal failure patients with greatly prolonged bleeding times. The multimeric state of the von Willebrand factor is also normal in these patients. The bleeding times were normalized in all 15 patients, 90 minutes post-infusion with desmopressin (DDAVP). No significant changes in factor VIII/vWF associated properties, blood cell counts, or coagulation factors were observed post-DDAVP treatment. However, a significant increase in platelet serotonin uptake (p less than .025) and ATP release (p less than .025) was detected after DDAVP treatment. These results indicate that DDAVP acts on the platelet membrane. This is further substantiated by the ability of DDAVP to block vasopressin-induced platelet aggregation in a dose- and time-dependent fashion. Perturbations in the movement and storage of serotonin and the release of adenosine 5'-triphosphate (ATP) in the platelets of uremic individuals are proposed to play a critical role in regulating bleeding times.

Myocardial accumulation of iodinated beta-methyl-branched fatty acid analogue, iodine-125-15-(p-iodophenyl)-3-(R,S)methylpentadecanoic acid (BMIPP), in relation to ATP concentration

To clarify the relationship between the myocardial accumulation of 125I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and intracellular adenosine-5'-triphosphate (ATP) content, the effect of 2,4-dinitrophenol (DNP, an electron transport uncoupler) on myocardial BMIPP accumulation was studied, in comparison with that of thallium-201-chloride (201Tl-Cl). In the mouse myocardium, DNP decreased the intracellular ATP and ADP levels, without affecting either acyl-CoA synthetase activity or the level of CoA-SH. Following treatment with DNP, decreases in myocardial BMIPP accumulation correlated well with those of ATP, while 201Tl-Cl showed slightly increased accumulation in the myocardium. Thus, in some diseases, BMIPP may be useful in evaluating myocardial ATP levels.

Endothelium-dependent contraction induced by platelet-derived substances in canine basilar arteries

The supernatant obtained from platelet-suspension incubated with thrombin caused contractions in both intact and endothelium-removed canine basilar arteries. Cyproheptadine (5 x 10(-7) M), which reduced the serotonin-induced contraction to about 20%, attenuated the supernatant-induced contraction to 51% in intact arteries and to 24% in endothelium-removed arteries. In both absence and presence of cyproheptadine, the supernatant-induced contraction of intact arteries was significantly larger than that of endothelium-removed arteries. The cyproheptadine-resistant contraction by the supernatant of intact arteries was attenuated by aspirin, OKY-046 (a thromboxane A2 synthetase inhibitor) and ONO-3708 (a thromboxane A2 antagonist), whereas such contraction of endothelium-removed arteries was not affected by these agents. The concentrations of serotonin, ATP and ADP in the supernatant used here were approximately 3, 67 and 44 micrograms/ml, respectively. The mixed solution of serotonin, ATP and ADP, at the same concentrations as the supernatant, also induced cyproheptadine-resistant, endothelium-dependent contractions in intact arteries. The contraction induced by the mixed solution in intact arteries was also attenuated by aspirin, OKY-046 and ONO-3708. The present experiments indicate that the supernatant causes endothelium-dependent contraction in canine cerebral arteries and that platelet-derived ATP and ADP contribute to this contraction.

Transmural high energy phosphate distribution and response to alterations in workload in the normal canine myocardium as studied with spatially localized 31P NMR spectroscopy

Spatially localized phosphorus-31 nuclear magnetic resonance (31P NMR) spectroscopy has been applied to the study of the normal canine myocardium to measure the relative content of high energy phosphates across the left ventricular wall. Transmural NMR data were acquired in five voxels spanning the wall of the left ventricle using the FLAX-ISIS technique. The validity of the FLAX-ISIS approach in acquiring localized spectra for transmural studies and in providing quantitative information from the localized spectra was examined rigorously by studies involving phantoms, intact rats, and the canine myocardium in vivo. The results indicated that (1) this technique yields spatially resolved spectra with partial overlap between adjacent voxels and virtually no overlap between every other voxel; (2) in the canine heart, signals from subepicardium, midwall, and subendocardium can be detected separately without cross contamination; and (3) relative metabolite contents within a voxel and among voxels can be quantitated. Transmural 31P NMR spectra were acquired with cardiac gating on 29 separate animals either at early systole or late diastole, and at three different workloads with the heart rate peak systolic pressure product (RPP) increasing from 6000 mmHg/min to 35,000 mmHg/min. The data revealed that in the normal canine myocardium, the creatine phosphate (CP) content and the CP/ATP ratio was significantly lower in the subendocardium than in the subepicardium. ATP levels were transmurally constant. Both the CP content and the CP/ATP ratio measured for each voxel remained unaltered in relation to either the phase of the cardiac cycle or approximately fourfold increase in workload. Free ADP levels calculated for each voxel showed that ADP was relatively higher in the subendocardium than the subepicardium, and in all transmural layers was higher than its apparent Km for oxidative phosphorylation. In this domain changes in ADP content with workload and MVO2 are not expected and were not observed.

Direct injection of blood samples into a high-performance liquid chromatographic adenine analyser to measure adenine, adenosine, and the adenine nucleotides with fluorescence detection

Adenine (Ade), adenosine (Ado) and its nucleotides such as AMP, cAMP, ADP and ATP in blood or plasma were determined by a high-performance liquid chromatographic (HPLC) adenine analyser with fluorescence detection. In order to inject samples directly into the HPLC system without pretreatment except dilution, the analyser consisted of two systems each, having three columns (pre-, mini- and analytical). A precolumn with an inlet filter of pore size 40 microns was common to both systems and packed with Butyl-Toyopearl 650-M to remove hydrophobic compounds and blood cell membranes. In the system for analysis of the nucleotides, a mini-column of Hitachi anion-exchange gel 3013-N was used for adsorbing AMP, cAMP, ADP and ATP. The adsorbed nucleotides were separated by the Hitachi gel 3013-N analytical column. In the other system for analysis of Ado and Ade, they were adsorbed on a Develosil ODS-5 mini-column and separated by an Asahipak GS-320H size-exclusion analytical column. The adenine compounds in each eluate were derivatized on-line in a 15-m reaction coil at 115 degrees C with bromoacetaldehyde as the fluorescent reagent in each mobile phase for the analytical column, and detected by spectrofluorimetry. ATP, ADP and AMP were accurately determined by the direct injection of hamster, rat and human whole blood. Authentic Ade and Ado were well separated and Ado in human plasma was determined, but it was difficult to determine it in rat plasma owing to interference from an unknown compound.

Measurement of adenine nucleotide levels with an adenine analyser as an index of freshness of porgy

In a prototype of an adenine analyser, adenosine and adenine nucleotides were derivatized with a fluorescent reagent, bromoacetaldehyde, after separation on a Hitachi gel No. 3012-N column by high-performance liquid chromatography. The previous analyser was improved by using a shorter reaction coil and by introduction of a Hitachi gel No. 3013-N with 5-microns particles of porous polystyrene-divinylbenzene, and applied to estimate the freshness of porgy. Total amounts of ATP, ADP and AMP in an isolated muscle just after death gradually decreased to 60% of the original amount after 5 h, and the ATP content rapidly decreased to 20% after 1 h. A good correlation was found between the levels of total adenine compounds and the energy charge values obtained from nineteen porgies frozen at a prerigour state. On the other hand, there existed no relationship between total adenine levels and the K values, which were indices for estimating freshness of fish. The analyser will be useful to evaluate the freshness of tissues and cells based on the higher contents of total adenine compounds, especially ATP.

ATP and ADP in human pre-embryos

Spare human oocytes and pre-embryos from an in-vitro fertilization (IVF) programme were individually analysed for ATP and ADP content using a bioluminescence method employing the firefly luciferin-luciferase reaction. The ATP content of oocytes that failed to fertilize in vitro was 1.71 +/- 0.28 pmol (n = 10), pronuclear stage ova 1.93 +/- 0.08 (n = 6), 2-cell stage 1.78 +/- 0.20 (n = 7), 4-cell stage 1.73 +/- 0.15 (n = 6), 6-8 cell stage 2.76 +/- 0.53 (n = 8), morula stage 2.36 +/- 0.68 (n = 8), early blastocyst stage 2.08 +/- 0.25 (n = 7) and expanded blastocyst stage 2.26 +/- 0.15 (n = 3) pmol. The ADP content of these pre-embryos was low in all stages with a small increment in the 2-4 cell stages and the blastocyst stage. This gave an elevated ATP/ADP ratio (range 19-92) indicating a good energy status. The sensitive luciferin-luciferase assay may be a tool for studying the energy status of spare oocytes and pre-embryos under different incubation conditions in human IVF programmes.

Nerve and drug-induced release of adenine nucleosides and nucleotides from rabbit aorta

The purpose of the present study was to assess the possible sites which contribute to the nerve stimulation- and alpha-agonist-induced overflow of endogenous adenine nucleosides and nucleotides in vascular tissue. Particular attention was focused on the endothelium because it is known that endothelial cells have a high concentration of ATP and its metabolites. Segments of rabbit thoracic aorta, some denuded of endothelial cells by rubbing the lumen of the vessel, were incubated in organ baths and subjected to transmural nerve stimulation or stimulated with the alpha-1 adrenoceptor agonist methoxamine. A portion of the bathing solution was processed for the determination of norepinephrine by high-performance liquid chromatography with electrochemical detection and a portion for determination of ATP, ADP, AMP and adenosine by high-performance liquid chromatography with fluorescence detection. Transmural stimulation led to a significant release of both norepinephrine and the adenine nucleosides and nucleotides in a ratio of 1 to 350. Removal of the endothelium did not change the release of norepinephrine but reduced the release of adenosine and its derivatives by 90%. Methoxamine also caused the release of adenosine and the adenine nucleotides which was reduced by 93% by removal of the endothelium. Thus, the endothelium seems to be a major source of transmural nerve stimulation and alpha-agonist induced overflow of adenosine and adenine nucleotides. The endothelium is not the exclusive source of these purine congeners, however. In the case of transmural stimulation there is approximately 10% of the total which is independent of the endothelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Distention promotes platelet and leukocyte adhesion and reduces short-term patency in pig arteriovenous bypass grafts

A pig model of autologous saphenous vein to common carotid artery bypass grafting was developed. An end-to-end anastomotic technique led to lower middle graft and distal turbulence. Saphenous veins were surgically prepared with or without distention at 600 mm Hg, implanted into the arterial circulation, and removed 2 hours later. Medial integrity was then assessed by adenosine triphosphate/adenosine diphosphate concentration ratio, and endothelial integrity, leukocyte and platelet adhesion by scanning electron microscopy. In grafts made with undistended vein adenosine triphosphate/adenosine diphosphate concentration ratio was not significantly lower (3.0 +/- 0.1, n = 32) than in freshly isolated vein (3.3 +/- 0.1, n = 26), endothelial cover was 98% +/- 1%, n = 6, and there was little platelet or leukocyte adhesion. In distended grafts adenosine triphosphate/adenosine diphosphate concentration ratio was reduced to 2.2 +/- 0.2 (n = 7, p less than 0.005), endothelial cover was reduced to 38% +/- 14% (n = 6, p less than 0.001), and there was extensive platelet and leukocyte adhesion to exposed subendothelium. In separate experiments graft patency measured at 1 to 5 weeks was significantly greater (96%, n = 25) when undistended vein was used than when distended vein was used (64%, n = 25, p less than 0.005). The data show that distention leads to medial and endothelial damage and that this is associated with increased platelet and leukocyte adhesion and with reduced early patency.

Fosfadecin and fosfocytocin, new nucleotide antibiotics produced by bacteria

Two new nucleotide antibiotics, fosfadecin and fosfocytocin, have been isolated from the culture filtrates of Pseudomonas viridiflava PK-5 and Pseudomonas fluorescens PK-52, respectively. These antibiotics were purified by column chromatographies using adsorption, gel filtration and ion exchange resins. On the basis of the spectroscopic and degradation studies, the chemical structures of fosfadecin and fosfocytocin were determined. These antibiotics were either enzymatically or chemically hydrolyzed to generate fosfomycin and a new antibiotic, fosfoxacin, which are also produced in the culture filtrates. They showed antibacterial activity against Gram-positive and Gram-negative bacteria. The antibacterial activity of these nucleotide antibiotics was weaker than that of fosfomycin and fosfoxacin.