Intracellular phosphates in inclusion body myositis--a 31P magnetic resonance spectroscopy study

Muscle phosphorus magnetic resonance spectroscopy was used to study oxidative metabolism at rest and during recovery from exercise in 7 patients with sporadic inclusion body myositis (s-IBM), compared with normal controls (n=8) and mitochondrial myopathies (n=20). At rest, 6/7 patients had elevated inorganic phosphates. Recovery parameters were not different from controls, in contrast with mitochondrial myopathies, who showed abnormal rest and recovery. The normal recovery suggests that mitochondrial oxidative capacity is not impaired in s-IBM.     

Evaluation of cardiac 31P magnetic resonance spectroscopy: reviewing NMR principles

Methylguanidine, guanidinoacetic acid and guanidinosuccinic acid are endogenous substances in body tissues. Extremely high levels of these substances are known to be related to the pathogenesis of epilepsy and renal failure such as uremia. In this study it was demonstrated that methylguanidine, guanidinoacetic acid and guanidinosuccinic acid, and arginine generate hydroxyl radicals in aqueous solution. These findings suggest that a high level of guanidino compounds accumulating near or within cells such as neurons (in an epileptogenic focus) or nephrons (in uremic patients) may cause free radical damage leading to these clinical disorders. Arginine may have a similar role in the pathogenesis of hyperarginemia.     

In vivo study of halothane hepatotoxicity in the rat using magnetic resonance imaging and 31P spectroscopy

Using magnetic resonance imaging (MRI) and spectroscopy (MRS), in vivo halothane hepatotoxicity was assessed in male Wistar rats. With 1.5% halothane in 100 or 20% O2, an edematous region, characterized by increased intensity on T2 weighted images and an increase in regional tissue water content (rho water), was seen proximal to the hepatic portal vein in the liver. Both spin-lattice relaxation (T1) and spin-spin relaxation (T2) increased in this region, relative to distal regions of the liver. Similarly, a high signal intensity on proton density weighted images was observed in this area. As halothane anaesthesia progressed, a decrease in the adenosine triphosphate-inorganic phosphate ratio (ATP/Pi) and an increase in the phosphomonoester-phosphodiester (PME/PDE) ratio was detected in the liver. In addition, intracellular pH decreased and intracellular free magnesium concentration [Mg2+] increased with time of exposure. Excessive vacuolation, ribosomal disappearance from rough endoplasmic reticulum, mitochondrial swelling and fragmentation of smooth endoplasmic reticulum were observed by transmission electron microscopy (TEM) in samples from the edematous region of the liver.     

31P magnetic resonance spectroscopy demonstrates expansion of the extracellular space in the skeletal muscle of starved rats

Starvation significantly alters the distribution of body water. To study the effects of starvation on cellular energetics and water distribution in skeletal muscle, a novel 31P magnetic resonance technique (31P MRS) was developed to measure water compartments. After 31P MRS-visible water space markers which distribute in total body water (dimethyl methylphosphonate, DMMP) and extracellular water (phenylphosphonate, PPA) were infused intravenously, 31P MRS spectra were obtained from the gastrocnemius muscle of male virus-free Wistar rats at baseline and after starvation or ad libitum feeding for 4 days. Muscle water spaces were also measured using the chloride method and Nernst's equation. Muscle water contents as determined by drying were equivalent in the two groups. In vivo measurements of changes in DMMP relative to all of the MRS visible phosphates also demonstrated that the total water space was similar in control and starved rats. However, starvation significantly increased the ratio of PPA/DMMP (0.67 +/- 0.05 vs 0.87 +/- 0.04, Control vs Starvation; P < 0.001), and therefore the ratio of extracellular water to total water in the gastrocnemius. Furthermore, because muscle water contents were comparable between the groups, this expansion of the extracellular space was accompanied by contraction of the intracellular compartment in starved animals. Equivalent changes were detected in vitro using the chloride method. Lastly, phosphocreatine/ATP ratios, which measured changes in high-energy phosphate stores, decreased after starvation (4.09 +/- 0.06 vs 3.61 +/- 0.06; P < 0.001) and were inversely related to changes in PPA/DMMP (r = -0.61; P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Signal profile measurements of single- and double-volume acquisitions with image-selected in vivo spectroscopy for 31P magnetic resonance spectroscopy

The volume-selection performance was studied for single- and double-volume-of-interest (VOI) acquisition with the volume-selection method image-selected in vivo spectroscopy for 31P magnetic resonance spectroscopy. High-resolution signal profiles were measured using a phantom simulating a brain. Inside the phantom there was a small, remotely controlled, movable signal source filled with ortho-phosphoric acid. Signal profiles of the VOI were measured in three perpendicular directions for 1VOI (single VOI) and 2VOI (double VOI) acquisition. The measured signal profiles for both acquisitions were very similar, but they showed a discrepancy with regard to the intended VOI (iVOI). The transition regions were on average 3.8 mm and the average full width at half maximum of the signal profile was 30 mm for an iVOI size of 30*30*30 (mm3). No displacement was observed in the signal profiles. To avoid overlapping signal profiles, the minimum separation between two iVOIs was found to be 10 mm in our magnetic resonance (MR) system. A substantial negative signal contribution from regions outside the iVOI was measured in the y-direction for 1VOI acquisition and one of the two VOIs in 2VOI acquisition. The other VOI in 2VOI acquisition exhibited only minor contamination. The measurements presented underline the importance of detailed knowledge on the volume selection performance in in vivo magnetic resonance spectroscopy.     

Early radiation effects in highly apoptotic murine lymphoma xenografts monitored by 31P magnetic resonance spectroscopy

PURPOSE: To assess the efficacy and toxicity of combined modality therapy with short intensive primary chemotherapy in the treatment of primary CNS lymphoma (PCL). METHODS AND MATERIALS: Prospective study of 31 nonimmunodeficient patients with PCL treated with initial chemotherapy (13 shortened MACOP-B; and 18 modified MACOP with high dose methotrexate) followed by radiotherapy (whole brain and a boost). Patients were aged 18-72 years (median 51 years). Eight patients had positive CSF cytology of which one had spinal meningeal disease; one patient had vitreous involvement. RESULTS: The overall complete response (CR) rate after chemotherapy and radiotherapy was 69% (95% Confidence Interval: 49-84%). At a median follow-up of 24 months (4 months to 10 years) median survival was 23 months and 5-year survival 34%. Age, sex, performance status, number of lesions, CSF cytology, and extent of surgery were not of prognostic significance for survival on univariate analysis. Eleven patients developed mucositis (Grade 3+) and 21 hematological toxicity (Grade 3+) with 22 septicemic episodes in 15 patients. Three patients developed dementia, one assumed to be treatment related, and two due to recurrent disease. CONCLUSION: The survival results of short intensive primary chemotherapy followed by radiotherapy are similar to the results of chemotherapy in Stage IV aggressive systemic non-Hodgkin's lymphoma, although the treatment was associated with high morbidity. The apparently favorable results when compared to radiotherapy alone may at least in part be due to selection of patients with good prognostic factors. To confirm the benefit of combined chemotherapy and radiotherapy over either of the two modalities alone requires evaluation in large prospective and ideally randomized studies.     

Epidermal and dermal phospholipids of the human eyelid: a 31P nuclear magnetic resonance spectroscopy study

The phospholipids of the skin are difficult to quantify because they represent only a small fraction of the skin tissue. In this study, 31P nuclear magnetic resonance, which permits precise profiling of these phospholipids, was used to compare the phospholipids of upper eyelid epidermal and dermal lipid extracts (n = 13 profiles). Phospholipid profiles included alkylacylphosphatidylcholine (AAPC), dihydrosphingomyelin (DHSM), diphosphatidylglycerol (cardiolipin), ethanolamine plasmalogen (EPLAS), lysophosphatidylcholine, phosphatidic acid, phosphatidylcholine (PC), phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, sphingomyelin, and uncharacterized phospholipids (U1 and U2, particularly enriched in the epidermis). The computed phospholipid metabolic index (n = 86 indexes) findings can be summarized as follows: a lower content of the en-ol and ether phospholipids in the epidermis relative to the dermis, internal compensation among the component phospholipids so as to maintain the choline functional group ratio, and a greater concentration of hydroxyl-containing functional groups in the epidermis. A membrane index (fmem) value of -0.37 for the epidermis deviated considerably from the value of -0.06 characteristic of living membranes and the dermis. The production of the reduced phosphatides, EPLAS and AAPC, indicates the use of alternative pathways between the two tissues. Relative to the dermis, increased PC in the epidermis coupled with decreased DHSM, EPLAS, and AAPC are factors enabling the epidermis of eyelid tissue to be an effective water barrier.     

Effect of anaemia correction on skeletal muscle metabolism in patients with end-stage renal disease: 31P magnetic resonance spectroscopy assessment

Skeletal muscle metabolism during exercise was compared in 5 patients with end-stage renal disease (ESRD) and 8 healthy controls, using a noninvasive technique, 31P magnetic resonance spectroscopy (MRS). After 3 months of anaemia correction with recombinant human erythropoietin (rHuEPO) these patients were re-evaluated. Maximal power achieved by the ESRD patients during a dynamic wrist flexion exercise test was 33% lower (p < 0.05) than the controls. Similarly in the ESRD group, the power at the onset of metabolic acidosis (the intracellular threshold) was 29% less than controls. The metabolic differences observed in the patients indicated a lower aerobic capacity. Three months of rHuEPO treatment resulted in a 55% increase in mean haematocrit but conferred no significant improvement in metabolic parameters at rest or during exercise. The lack of any significant changes in muscle metabolism following the correction of anaemia suggests that oxygen availability is not the exclusive limiting factor for aerobic metabolism in ESRD patients.     

Superiority of blood over saline resuscitation from hemorrhagic shock: a 31P magnetic resonance spectroscopy study

OBJECTIVE: To study the relation between blood and saline administration, postresuscitation hematocrit (Hct) level, and metabolic recovery after hemorrhagic shock. SUMMARY BACKGROUND DATA: It is generally believed that crystalloid can be substituted, in whole or in part, for blood during resuscitation of hemorrhagic shock. This is based on the belief that Hct can be safely reduced but should not fall below a critical level. METHODS: Male rats weighing 200 g were subjected to an isobaric hemorrhagic shock at a mean arterial pressure of 30 mmHg for 14 minutes, after which they were randomized to one of three resuscitation regimens. Control group (n = 36) were resuscitated by return of all shed blood. Mid-Hct (n = 39) and low-Hct (n = 60) groups were depleted of one third and one half of their circulating blood volumes, respectively, and were resuscitated with three times that volume of normal saline. Skeletal muscle intracellular energetics and pH were measured serially using 31P magnetic resonance spectroscopy at baseline, during shock, and after resuscitation. Arterial blood was sampled at the same time points. The number of surviving animals in each group at 24 hours was recorded. RESULTS: After resuscitation, surviving rats in the low-Hct group demonstrated a greater consumption of high-energy phosphocreatine stores than did the other groups (control = 0.479 +/- 0.003, mid-Hct = 0.465 +/- 0.004, low-Hct = 0.457 +/- 0.007, mean +/- standard error of the mean; p < 0.01 low-Hct vs. other groups by analysis of variance). The rats that received saline resuscitation developed a relative intracellular acidosis (control = 7.29 +/- 0.02, mid-Hct = 7.25 +/- 0.02, low-Hct = 7.23 +/- 0.02; p < 0.05 controls vs. other groups by analysis of variance). At 24 hours, the death rates were significantly different among the groups: control = 1 of 36 rats (2.8%), mid-Hct = 6 of 39 (15.4%), and low-Hct = 14 of 60 (23.3%) (p < 0.05 by chi square analysis). CONCLUSION: The oxygen-carrying capacity of resuscitation fluid has an important impact on intracellular metabolism and outcome.     

Impaired aerobic glycolysis in muscle phosphofructokinase deficiency results in biphasic post-exercise phosphocreatine recovery in 31P magnetic resonance spectroscopy

Using 31P magnetic resonance spectroscopy, energy metabolism in calf muscles of two patients with biochemically and genetically proven muscular phosphofructokinase deficiency, and an asymptomatic heterozygote was monitored during isometric foot plantarflexion performed under aerobic and anaerobic conditions and in the aerobic recovery phases. In the heterozygote only a moderate alteration from normal was found in terms of an elevated ATP demand during exercise. In the homozygote, hexose phosphates, indicated as phosphomonoesters, increased dramatically during contraction. Phosphomonoester accumulation resulted in consumption of free inorganic phosphate (P(i)). During ischemic exercise the absence of glycolytic ATP formation resulted in a linear time course of phosphocreatine breakdown and a moderate alkalinization. During the recovery, phosphocreatine resynthesis showed a biphasic time course, indicating that mitochondrial function itself was not directly affected. At first glance, the early depletion of P(i) below initial resting levels and the rate of phosphate splitting from sugar phosphates seemed to become the limiting factor for the rate of the oxidative phosphorylation and creatine kinase reaction. However, the actual concentrations of P(i) and ADP estimated at the onset of delay were too high to exclusively explain the dramatic delay in PCr resynthesis. For this reason, a reduced turnover of the citric acid cycle was assumed, which was caused by the complete absence of glycolysis in PFK deficiency patients. Furthermore, results from PFK deficiency patients were compared with previous findings from myophosphorylase deficiency patients in the literature.     

Increased incidence of a resonance in the phosphodiester region of 31P nuclear magnetic resonance spectra in the skeletal muscle of fibromyalgia patients

OBJECTIVE: To determine if patients with fibromyalgia syndrome (FMS) are more susceptible to activity-induced muscle damage than are healthy subjects. METHODS: Eleven FMS patients and 10 healthy subjects performed concentric and eccentric exercise with their dominant and nondominant forearms, respectively. 31P magnetic resonance spectroscopy (to assess inorganic phosphate [P(i)] and phosphocreatine [PCr]) and dolorimetry (to assess pain) were performed before and 20 minutes after exercise and at 4 subsequent 24-hour intervals. RESULTS: Neither group exhibited increased P(i)/PCr ratios or reduced dolorimetry scores following the exercise protocols. FMS patients did display a phosphodiester resonance at a higher rate than healthy subjects (37% versus 12%), but this was not related to the exercise. CONCLUSION: Unchanged P(i)/PCr ratios and dolorimetry scores following acute exercise provide evidence against the hypothesis that FMS patients are more susceptible to activity-induced muscle damage than are healthy subjects, although P(i)/Pcr and pain may not adequately document such damage. The frequent occurrence of phosphodiester in the spectra of FMS patients may indicate a sarcolemmal abnormality in these subjects.     

Plasmalemmal pH-gradients in drug-sensitive and drug-resistant MCF-7 human breast carcinoma xenografts measured by 31P magnetic resonance spectroscopy

31p Magnetic resonance spectroscopy (MRS) was employed to investigate tumor pH in xenografts of drug-sensitive and drug-resistant MCF-7 human breast carcinoma cells. Measured extracellular pH values were found to be lower than the intracellular pH in all three tumor types investigated. The magnitude of this acid-outside plasmalemmal pH gradient increased with increasing tumor size in tumors of two drug-resistant variants of MCF-7 cells, but not in tumors of the parent (drug-sensitive) cells. The partitioning of weak-base or weak-acid drug molecules across the plasma membrane of a tumor cell is dependent upon the acid-dissociation constant (pKa) of the drug as well as the plasmalemmal pH gradient. A large acid-outside pH gradient, such as those seen in MCF-7 xenografts, can exert a protective effect on the cell from weak-base drugs such as anthracyclines and Vinca alkaloids, which have pKa values of 7.5 to 9.5. The possibility of enhancing the therapeutic efficacy of weak-base drugs by dietary or metabolic manipulation of the extracellular pH, in order to reduce or reverse the plasmalemmal pH gradient, deserves investigation.     

Changes in energy metabolism of calf muscle in patients with intermittent claudication assessed by 31P magnetic resonance spectroscopy: a phase II open study

An effect of EACA given in the daily dose of 85-230 mg/kg for 1-1-days on the activity of certain plasma protease inhibitors in 7 children with steroid-sensitive and steroid-dependent nephrotic syndrome (age between 3.5 and 18 years), and in 6 children with Sch?nlein-Henoch syndrome (aged between 3.5 and 6 years). Additionally, an effect of EACA on clinical status, dynamics of improvement, proteinuria and/or erythrocyturia, and incidence of adverse reactions was studied. It was found that EACA significantly increased antithrombin III activity by approximately 68.8% proteinase alpha 1-inhibitor by 41.8% alpha 2-antiplasmin by 55% in patients with nephrotic syndrome, and increased an activity of protease alpha 1-inhibitor by 75% in patients with Sch?nlein-Henoch syndrome. EACA given together with corticosteroids enhanced their efficiency manifested--especially in children with Sch?nlein-Henoch syndrome--by a rapid diminishment of skin changes, proteinuria and erythrocyturia. A drop in blood pressure, loose stools, upper respiratory inflammation, and fever were most frequent adverse reactions. EACA given alone produced rapidly increasing edema in patients with hephrotic syndrome. It seems that EACA may be used as an adjuvant therapy in some cases of nephrotic and Sch?nlein-Henoch syndromse.     

Energy charge monitoring via magnetic resonance spectroscopy 31P in the perfused human placenta: effects of cadmium, dinitrophenol and iodoacetate

Phosphorus 31 nuclear magnetic resonance spectroscopy as a non-invasive technique was applied to monitor the metabolic activity of the human placenta during perfusion in vitro. During control perfusions (n = 3) there was an initial increase in adenosine triphosphate (ATP) and a fall in inorganic phosphate (Pi). Thereafter, however, the level of both ATP and Pi remained constant throughout the perfusion period (11 h). Additional biochemical parameters such as glucose consumption, lactate production and the release of hormones, human chorionic gonadotrophin (hGC). measured in the perfusate samples, were also used to assess the viability of the placental tissue. As with ATP, all these biochemical parameters under the control conditions showed a stable rate of metabolic activity throughout the length of the experiments. In additional experiments, the effect of the metabolic inhibitor dinitrophenol (n = 2) and dinitrophenol (DNP) together with iodoacetic acid (IOA, n = 2) were studied. DNP (0.1 mM) alone showed a slight decrease of all parameters. In contrast, the addition of IOA (0.1 mM) with DNP (0.1 mM) not only blocked the production of ATP but also produced a substantial impact on placental metabolic activity. The effect of a toxic dose of cadmium (20 nmol/ml) was studied also (n = 3). This dose of cadmium demonstrated no effect on phosphorus metabolism. However, the rate of glucose consumption and the release of hCG were significantly reduced.     

Assessment of testicular function in experimental varicocele rats by phosphorus-31 magnetic resonance spectroscopy

To assess testicular function in experimental varicocele rats, we used 31P magnetic resonance (MR) spectroscopy and compared MR spectroscopic parameters with flow cytometric DNA analysis. In vivo 31P MR spectroscopy and flow cytometric DNA analysis of testes were performed in 10 sham-operated and 9 induced varicocele rats. Although the testicular phosphomonoester (PM)/ATP ratio did not differ between sham-operated and induced varicocele rats, the phosphodiester (PD)/ATP ratio was significantly reduced and the inorganic phosphate (Pi)/ATP ratio was significantly increased in induced varicocele rats. There was no difference between the right and left sides. DNA flow cytometry showed a decrease in the percentage of haploid cells in induced varicocele rats, regardless of the side. This study indicates that in vivo 31P MR spectroscopy provides valuable information for assessment of testicular function.     

A metabolism study of human masseter muscle by 31P magnetic resonance spectroscopy during long periods of exercise and recovery

The metabolism of the human masseter muscle was investigated using phosphorus (31p) magnetic resonance spectroscopy (MRS) during long periods of exercise and recovery. Eleven subjects aged 19 to 28 yr were examined by 31p MRS during four consecutive periods of 13 min each: rest, exercise, recovery 1 and 2. For each subject, a biting force equal to 20% of maximum voluntary biting force was applied and controlled during the exercise period to produce maximum fatigue. 31p MR spectra were localized from a 24 cm3 volume of interest using an image selected in vivo spectroscopy (ISIS) sequence and a 6 cm diameter surface coil placed on the left masseter. Compared to the resting level, the phosphocreatine (PCr) content decreased by 26% during exercise, while the inorganic phosphate (Pi) concentration increased by 65%. During the two recovery periods, the Pi content remained decreased compared with the resting level by 36% and 30%, respectively. The Pi/PCr ratio was increased from 0.30+/-0.04 at rest to 0.63+/-0.13 during exercise while the adenosine triphosphate (ATP)/Pi ratio was decreased. The pH decreased from 7.02+/-0.03 to 6.93+/-0.04 during exercise and returned to control level (7.09+/-0.08) only during the second recovery period. These results suggest that the masseter muscle is characterized by high ATP turnover and, therefore, high oxidative phosphorylative activity in agreement with its constitution of predominantly fatigue resistant type I fibers.     

Cardiac magnetic resonance spectroscopy

The article reviews cardiac magnetic resonance spectroscopy (MRS) in Canada. 31P MRS has been used to study cardiac energetics and intracellular pH in hearts subjected to ischemia-reperfusion and to evaluate the effects of pharmacological interventions. 23Na, 87Rb, and 7Li MRS have provided unique probes to study ion balance and fluxes in intact tissue under normal and stressful physiological conditions. 1H MRS has been used to monitor the accumulation of lactate and lipids in hearts subjected to ischemia-reperfusion and follow the effects of diet on cardiac lipid levels and function. The isolated rat heart has been used most commonly to study the effects of pharmacological agents on energy balance, pH, ion fluxes, and contractile function of the heart subjected to ischemia-reperfusion. The pig heart has been developed as an alternative to the rodent heart because its metabolism is more similar to that of the human heart. Human atrial appendages have been useful in evaluating the effects of preservation strategies (temperature, composition of preservation solutions) on energy levels. The pig heart model has been useful in evaluating the effects of preservation solutions on cardiac function of hearts destined for transplantation. An isolated blood-perfused pig heart model has been developed to assess the effects of cardioplegic strategies on the preservation of contractile function of hearts following surgery on the heart. An in vivo canine model has been used to study myocardial infarction and the effects of therapies to reduce the infarct zones and areas of the heart at risk of infarction. Studies of human hearts in vivo have provided insight into the metabolic adaptations that occur in individuals living at high altitudes.     

Definition of a diagnostic score of malignant hyperthermia using P-31 magnetic resonance spectroscopy

OBJECTIVES: To assess the metabolic muscular disorders associated with malignant hyperthermia (MH) using 31-P MRS, in order to develop a diagnostic tool for MH. STUDY DESIGN: Retrospective analysis of a series of case. PATIENTS: Group of 39 subjects, including 13 MH susceptible (MHS), and 26 not susceptible (MHN) members of recognized MHS families, according to the results of the in vitro contracture tests. METHODS: Each subject underwent two protocols, both including rest, exercise and recovery periods. Exercise was performed successively under aerobic and ischaemic conditions. RESULTS AND DISCUSSION: A significant early acidosis was recorded for the MHS group under both conditions of exercise (normoxia and ischaemia). However, the sensitivity of this parameter (77%) was not high enough to be considered as discriminant. Therefore a MRS score has been defined, corresponding to the sum of metabolic anomalies (acidosis, anomalies in PCr tum-over and in ATP or phosphomonoesters concentrations) recorded throughout both protocols. This score provided satisfactory results for both sensitivity (93%) and specificity (93%). CONCLUSION: 31-P MRS can act as a reliable diagnostic tool for MH.     

Urinary excretion of cyclophosphamide in humans, determined by phosphorus-31 nuclear magnetic resonance spectroscopy

Phosphorus-31 NMR spectroscopy was used to analyze urine samples from patients treated with cyclophosphamide (CP) on 2 consecutive days. CP and all of its known phosphorylated metabolites except the tautomeric pair 4-hydroxycyclophosphamide/aldophosphamide, i.e. carboxycyclophosphamide (CXCP), dechloroethylcyclophosphamide (DCCP), alcophosphamide, ketophosphamide, and phosphoramide mustard (PM), were determined. Several other signals corresponding to unknown CP-related compounds were observed. Seven of them were identified; all were hydrolysis products of CP or its metabolites (one from CP, two from CXCP, three from DCCP, and one from PM). Twenty-four-hour urinary excretion of unmetabolized CP was not significantly different on the first (17% of the daily administered dose) and second (16%) days of treatment. The amounts of phosphorylated metabolites excreted in 24-hr urine samples were much higher after the second CP dose (37%) than after the first (20%), suggesting autoinduction of CP metabolism. CXCP and its two degradation products (accounting for 7-10% of CXCP) were by far the major metabolites (11.5 and 23% after the first and second doses, respectively). DCCP plus its degradation products and alcophosphamide each represented 2-3% on the first day of treatment and 5% on the second day of treatment. Levels of PM and its degradation products were extremely low (0.3 and 0.6% after the first and second CP doses, respectively), as were those of ketophosphamide (0.4 and 0.6% on the first and second days of treatment, respectively). We noted only modest interpatient variation in excreted levels of CP and all of its metabolites.     

Phosphorus metabolism during growth of lymphoma in mouse liver: a comparison of 31P magnetic resonance spectroscopy in vivo and in vitro

Large phosphomonoester (PME) signals are detected in the phosphorus magnetic resonance spectra (31P MRS) of many neoplastic and rapidly dividing tissues. In addition, alterations in phosphodiester (PDE) signals are sometimes seen. The present study of a murine lymphoma growing in liver showed a positive correlation between the hepatic PME/PDE ratio measured in vivo by 31P MRS at 4.7 T and the degree of lymphomatous infiltration in the liver, quantified by histology. High-resolution 31P MRS of liver extracts at 9.7 T showed that the PME peak consists largely of phosphoethanolamine (PE) and to a lesser extent of phosphocholine (PC). The concentration of both PE and PC increased positively with lymphomatous infiltration of the liver. In vivo, the PDE peak contains signals from phospholipids (mostly phosphatidylethanolamine and phosphatidylcholine) and the phospholipid breakdown products glycerophosphoethanolamine (GPE) and glycerophosphocholine (GPC). Low levels of GPE and GPC were detected in the aqueous extracts of the control and infiltrated livers; their concentrations remained unchanged as the infiltration increased. The total concentration of phospholipids measured by 31P MRS of organic extracts decreased about 3-fold as the infiltration increased to 70%. Thus, our data showed that the increased PME/PDE ratio in vivo is due to both an increase in the PME metabolites and a decrease in the PDE metabolites. We propose that this ratio can be used as a non-invasive measure of the degree of lymphomatous infiltration in vivo.