Anti-inflammatory and analgesic activity of total flavone of Cunninghamia lanceolata.

The present study was undertaken to investigate the anti-inflammatory and analgesic activity of total flavone of branches and leaves of Cunninghamia lanceolata (TFC) to provide a scientific basis for its clinical use and resource development. TFC was evaluated for anti-inflammatory and analgesic activity in mice or rats using chemical and thermal models of nociception, including acetic acid-induced writhing test, hot plate latency test, formalin test and carrageenan induced paw oedema test. Results showed that TFC given orally can significantly attenuate acetic acid-induced writhing in mice in a dose-dependent manner. In the hot plate latency test, TFC showed common activity in prolonging duration time only at the highest dose (400 mg/kg). Each dose of TFC could not significantly inhibit the first phase but was active in the later phase of formalin-induced pain, whereas morphine showed notable activity in the two phases. In the carrageenan-induced paw oedema model, TFC could significantly and dose-dependently reduce the carrageenan-induced paw edema at the third and fifth hour, and decrease the content of PEG(2) in paw edema tissue and that of COX-2 in blood serum. It may be concluded that TFC showed both anti-inflammatory and analgesic effects, showing that it can be of importance in drug development, especially in the field of pain and inflammation.

Detection of calprotectin and apoptotic activity within the equine colon from horses with black walnut extract-induced laminitis.

The black walnut extract (BWE) model of equine laminitis is associated with a systemic inflammatory response manifest by increased expression of inflammatory cytokines in the lungs and liver as well as the laminae. The specific role of the gastrointestinal tract in development of this response is unclear and is of utmost importance, as gastrointestinal disease and laminitis are intimately related. We investigated calprotectin expression and epithelial and endothelial apoptosis in the colon of horses exposed to orally administered BWE. Sections of colon from 19 horses including 7 controls not exposed to BWE, 6 horses at the developmental time-point of leukopenia (DTP) and 6 at the onset of Obel grade 1 laminitis (LAM) after BWE-administration were histologically examined. Immunohistochemical evaluation for calprotectin expression with MAC 387 antibody was performed along with assessment of epithelial and endothelial apoptosis with caspase-3 active antibody. Calprotectin expression and percentage of apoptotic cells were compared between controls and the two treatment groups and presence of a correlation between calprotectin expression and apoptosis was evaluated. Histological findings from BWE-treated horses included eosinophil and lymphocyte epitheliotropism. The DTP group had a higher (p<0.01) calprotectin score with respect to the control group, while there was no significant difference in percentage of epithelial and endothelial apoptotic cells between groups (p=0.08 and p=0.48 respectively). No significant correlation was found between calprotectin score and epithelial or endothelial apoptosis (p=0.69 and p=0.29 respectively). There is preliminary evidence that exposure of horses to BWE results in an early inflammatory response in the colon. Further studies are needed to characterize the nature of the colonic injury in BWE-exposed horses and the link to the development of laminitis.

Effects of a supplement containing chromium and magnesium on morphometric measurements, resting glucose, insulin concentrations and insulin sensitivity in laminitic obese horses.

REASONS FOR PERFORMING STUDY: Obesity and insulin resistance are risk factors for laminitis in equids and supplements containing chromium and magnesium might improve insulin sensitivity. HYPOTHESIS: A supplement containing chromium, magnesium and other nutraceuticals would alter morphometric measurements, blood variables, and insulin sensitivity in laminitic obese horses. METHODS: Twelve previously laminitic obese (body condition score ≥ 7/9) horses were randomly allocated to treatment (n = 6) and control (n = 6) groups and 2 obese horses with clinical laminitis were included in the treatment group. Treated animals received 56 g supplement with 0.25 kg oats once daily for 16 weeks. The supplement contained chromium (5 mg/day as yeast), magnesium (8.8 g/day as oxide/proteinate), and other nutraceuticals. Insulin-modified frequently sampled i.v. glucose tolerance tests were performed with hay provided at 0, 8 and 16 weeks, and insulin sensitivity was estimated by minimal model analysis. Physical measurements were collected at the same points. Horses were not exercised. RESULTS: Hyperinsulinaemia (>30 µu/ml) was detected in 12 of 14 horses prior to treatment. Glucose and insulin data from one mare with clinical laminitis were excluded because of persistent pain. Mean ± s.d. insulin sensitivity was 0.64 ± 0.62 × 10(-4) l/min/mu prior to treatment for the remaining 13 horses. Time and treatment × time effects were not significant for any of the variables examined, with the exception of resting insulin concentrations, which significantly increased over time (P = 0.018). Health status remained the same. CONCLUSIONS: The supplement containing chromium and magnesium evaluated in this study did not alter morphometric measurements, blood variables, resting insulin concentrations or insulin sensitivity in laminitic obese horses. POTENTIAL RELEVANCE: Additional research is required to determine the appropriate use of chromium and magnesium supplements in horses.

Role of oxidative tissue injury in the pathophysiology of experimentally induced equine laminitis: a comparison of 2 models.

BACKGROUND: Oxidative stress reportedly plays a role in sepsis-induced organ dysfunction and failure in many species. In septic horses, laminae are targeted; evidence of laminar oxidative stress has been reported experimentally in the black walnut extract (BWE) model. Carbohydrate (CHO)-induced laminitis may be more similar to clinical sepsis-related laminitis than the BWE model in that animals with CHO-induced disease commonly develop laminar failure. The role of oxidative stress in the CHO model remains unknown. HYPOTHESIS/OBJECTIVES: Markers of oxidative stress will be increased in laminae from horses with BWE- and CHO-induced laminitis. ANIMALS: Banked laminar tissue from various time points from animals subjected to BWE (n = 15) and CHO (n = 20) protocols. METHODS: Laminar 4-hydroxynonenal (4-HNE) and protein carbonyl content were evaluated by slot blot analysis. Laminar 3-nitrotyrosine (3-NT) immunohistochemistry was performed. RESULTS: The number of laminar 3-NT (+) cells was increased at developmental and Obel grade 1 (OG1) time points in the BWE model (versus control [CON]; P= .013) and lower in OG1 tissues than CON in the CHO model (P = .04). No change in 4-HNE content was observed in the CHO model, and no increase in laminar protein carbonyl content was present in either model (P > .05). CONCLUSIONS AND CLINICAL IMPORTANCE: These results do not support a prominent role for oxidative stress at examined time points in CHO-overload laminitis and support transient oxidative stress in the BWE model. Tissue oxidation does not appear to be a central early pathophysiologic event in CHO-associated laminitis.

Black walnut extract: an inflammatory model.

The black walnut extract (BWE) model was developed after the discovery that horses bedded on shavings from black walnut trees commonly developed laminitis. The first investigators that consistently induced laminitis with black walnut shavings established that it was only the heartwood of the tree that induced laminitis. The BWE model of laminitis has allowed investigators to determine many of the early pathologic signaling events likely to occur in the developmental and acute clinical stages of the disease process, and has brought inflammatory injury to the forefront of laminitis research. These events must also be assessed in the carbohydrate overload models, the models that more closely reflect the clinical case of laminitis.

Evaluation of the possible role of prostaglandin F(2 alpha) in laminitis induced in horses by nasogastric administration of black walnut heartwood extract.

OBJECTIVE: To provide insights into the role of prostaglandin F(2 alpha) (PGF(2 alpha)) in the developmental stages of laminitis induced in horses by ingestion of black walnut heartwood extract (BWHE). SAMPLE POPULATION: 10 adult mixed-breed horses. PROCEDURES: Horses were separated into 2 groups and were euthanatized at 12 hours after placebo (water) administration (control horses) or after BWHE administration and development of Obel grade 1 laminitis. Blood samples were obtained to determine plasma PGF(2 alpha) concentrations hourly for the first 4 hours and subsequently every 2 hours after substance administration. Laminar arteries and veins were isolated, and responses to increasing concentrations of PGF(2 alpha) were measured before and after preincubation of blood vessels with prostanoid and thromboxane receptor antagonists SQ 29,548, SC-19220, and AH 6809. RESULTS: Plasma PGF(2 alpha) concentrations increased in horses given BWHE; the WBC count decreased concurrently. In control horses, PGF(2 alpha) was a potent contractile agonist for laminar veins but not for laminar arteries. In horses given BWHE, PGF(2 alpha) was similarly selective for laminar veins; however, the magnitude of PGF(2 alpha)-induced venoconstriction was less than that in control horses. After preincubation with SQ 29,548, laminar veins from control horses responded to PGF(2 alpha) with a small degree of dilation, whereas laminar veins from horses given BWHE did not. CONCLUSIONS AND CLINICAL RELEVANCE: PGF(2 alpha) may play a role in the inflammatory and vascular dysfunction associated with the prodromal stages of laminitis. Prostanoids such as PGF(2 alpha) may be viable targets for the prevention of acute laminitis in horses.

Temporal aspects of laminar gene expression during the developmental stages of equine laminitis.

The results of recent studies indicate that inflammatory responses occurring in the early stages of equine laminitis lead to downstream events that eventually result in failure of the bond between the hoof wall and the distal phalanx. In order to gain further insights into the molecular mechanisms involved in the development of laminitis, an equine-specific cDNA microarray consisting of transcripts for more that 3000 genes was used to assess temporal changes in gene expression in laminar tissues at 1.5, 3 and 12 h after administration of either a laminitis-inducing agent (black walnut heartwood extract; BWHE) or an equal volume of water (control). As early as 1.5 h after BWHE administration, pro-inflammatory genes associated with leukocyte activation and emigration, including MCP-3/CCL7, MCP-1/CCL2, IP-10/CXCL10 and ICAM-1 were up-regulated. At both 1.5 and 3h after administration of BWHE, expression of B-cell specific transcripts (e.g., Ig-gamma 3, Ig-gamma 1 and lambda-light chain) were decreased in the laminar tissues. At the onset of Obel grade 1 lameness in horses administered BWHE, other genes involved in inflammatory processes (e.g., serum amyloid A, calgranulin C and NFAT-activation molecule 1), regulation of inflammation (e.g., inter-alpha-trypsin inhibitor, BiP/GRP78 [Ig binding protein], L-plastin, serpin and nexin-1), antioxidant responses (e.g., superoxide dismutase), matrix turnover (e.g., MMP-9 and TIMP-1), and anti-microbial responses (e.g., serotransferrin, beta-defensin-1 and elafin) were up-regulated. These results provide convincing evidence that genes associated with inflammation, activation and extravasation of leukocytes, antimicrobial activities, and destruction of the lamellar basement membrane are induced during the early stages of development of laminitis in response to administration of BWHE.

Indices of inflammation in the lung and liver in the early stages of the black walnut extract model of equine laminitis.

The liver and lung are not only described as "target organs" in sepsis in most species, but are purported to be sources of circulating inflammatory mediators central to the systemic inflammatory response syndrome (SIRS). As we have recently reported an inflammatory response in the laminar tissue in laminitis similar to that described in "target organs" in human sepsis, we investigated the inflammatory response of the lung and liver in the black walnut extract (BWE) model of equine laminitis to determine (1) if a similar systemic inflammatory response occurs in this laminitis model as described for these organs in human sepsis, and (2) if these organs may be an important source of the inflammatory mediators leading to laminar inflammation. Real-time quantitative PCR (RT-qPCR) was used to measure hepatic and pulmonary mRNA concentrations of IL-1beta, IL-4, IL-6, IL-8, IL-10, TNF-alpha, COX-1 and COX-2. Hepatic samples were assessed from two time points in the developmental/prodromal period: (1) 1.5h post-BWE administration (BWE-1.5H, n = 5), and (2) the "developmental time point" (onset of leukopenia, approximately 3h post-BWE administration, BWE-DEV, n = 5). Pulmonary samples were only assessed for the BWE-DEV group. One control group (CON-3H, n = 5) was used for both the 1.5H and DEV groups. Finally, CD13 immunohistochemistry was performed to assess leukocyte emigration into hepatic and pulmonary parenchyma. Hepatic and pulmonary mRNA concentrations of the proinflammatory cytokines IL-6, IL-8 and TNF-alpha were significantly increased (P < 0.05) in BWE-1.5H and BWE-DEV groups compared to the control group; IL-1beta mRNA concentrations were only increased in the lung. The "anti-inflammatory" cytokines, IL-10 and IL-4, underwent transient decreases at different time points. Significant increases in parenchymal leukocyte numbers occurred in both the lung and liver at the BWE-DEV time point. Hepatic and pulmonary proinflammatory cytokine expression differ from that previously reported for the laminae in that TNF-alpha was increased in the hepatic and pulmonary tissues, the increases in expression of IL-6 and IL-8 are dramatically smaller for the liver and lung compared to those reported for the laminae, and the peak changes appear to occur later in the disease process in the liver than in the laminae (BWE-DEV in liver vs. 1.5H in the laminae).

Tissue concentrations of 4-HNE in the black walnut extract model of laminitis: indication of oxidant stress in affected laminae.

In the septic horse prone to laminitis, a similar activation of the innate immune system appears to occur as reported in the septic human prone to organ failure. Because oxidant injury plays a central role in organ failure occurring due to an overzealous innate immune response in human sepsis, this study was performed to determine whether there was evidence of oxidant stress in the laminar tissue in the early stages of laminitis. 4-Hydroxy-2-nonenal (4-HNE), a lipid aldehyde that forms due to lipid peroxidation occurring during episodes of oxidant stress, readily forms adducts with cellular proteins; these adducts can be assessed as a marker of oxidant stress in the form of lipid peroxidation. In this study, a slot blot technique was used to assess 4-HNE adduct concentrations in the laminae, lung, liver, and intestinal tract in the black walnut extract (BWE) model of laminitis. Significant increases in laminar 4-HNE adduct concentrations were identified at two early stages in the BWE model, in the absence of such changes in the other tissues. These data indicate that oxidant stress may play an important role in the laminar failure in laminitis, and further support the concept that a poor antioxidant response in the laminae relative to other equine tissues may be responsible for failure of the laminae in the septic horse. In contrast, tissues such as the lung and liver that undergo oxidant injury in human sepsis appear to be relatively protected in horses.

[Animal welfare in prevention and therapy of laminitis]. / Tierschutzaspekte bei der Prophylaxe und Therapie der Hufrehe.

Laminitis is a systemic disease which is manifested as a non infectious condition in the foot. The management of feeding and housing conditions is necessary to treat the endocrinological and metabolic disturbances of laminitic horses. The Equine Metabolic Syndrome (EMS) is predisposing for developing laminitis, and it is characterised by obesity, insulin resistance, hypertension and dyslipidaemia. A genetical predisposition is supposed and EMS is accompanied by a lack of exercise and inadequate energy intake. Laboratory examinations are of great importance for diagnosis. Analyses of insulin, glucose and ACTH are of interest. Several approaches to treat laminitis are available, including pharmacological and orthopaedic strategies as well as the management of the feeding and housing conditions. However, the prophylaxis to prevent laminitis has to be emphasised. Predisposed horses should be detected and adequately treated; especially weight reduction in obese horses is in the focus of interest. Horses in the acute stage of laminitis have to be stabled. Furthermore redistributing weight from the most stressed wall is necessary to prevent pain and to minimise laminar damage and displacement of the distal phalanx. In cases of displacement of the distal phalanx a close communication between the veterinarian and the authorised farrier is necessary, in these cases treatment should be supported by x-ray diagnosis. Horses have to be treated with NSAISs to ensure a proper therapy to consider animal welfare. Horses have to be fed with hay and supplemented with minerals and vitamins. Feeding exclusively straw and feed restriction has to be avoided.

Effect of biotin supplementation on hoof health and ceramide composition in dairy cattle.

The effect of biotin supplementation on various foot lesions and hoof ceramide composition of toe (wall) and sole portions of hooves was studied in crossbred dairy cattle. Biotin supplementation was done for five months in 14 cattle at a farm and the other 14 animals kept as control. A significant decline was observed in heel erosions and sole avulsions along with total disappearance of white line fissures and double soles in the biotin supplemented cattle resulting in decrease in the overall disease score. Thin layer chromatographs of the hoof lipids revealed 11 types of ceramides in sole lipids and 6 types of ceramides in toe (wall) lipids. The ceramides were typed and identified according to their Rf values. A qualitative increase in the density of thin layer chromatographs of sole lipids was observed in biotin supplemented cattle whereas a non-significant difference in density of thin layer chromatographs of toe lipids was observed after supplementation of biotin.

Early laminar events involving endothelial activation in horses with black walnut- induced laminitis.

OBJECTIVE: To determine proinflammatory gene expression, endothelial adhesion molecule gene expression, and matrix metalloproteinase (MMP) concentrations in laminar specimens at 1.5 hours after administration of black walnut extract (BWE) and to compare these values with later time points. ANIMALS: 25 horses. PROCEDURES: After nasogastric administration of BWE, anesthesia was induced at 1.5 hours in early time point (ETP) horses (n = 5), between 3 and 4 hours in developmental time point horses (5), and between 9 and 10 hours in acute onset of lameness time point horses (5). Anesthesia was induced at 3 and 10 hours after nasogastric administration of water in 2 groups of control horses (3-hour control group, n = 5; 10-hour control group, 5). Real-time quantitative PCR assay was performed on laminar specimens from control and ETP horses for cyclooxygenase (COX)-1, COX-2, interleukin (IL)-1beta, tumor necrosis factor-alpha, IL-6, IL-8, IL-10, MMP-2, and MMP-9 gene expression; and on laminar specimens from all groups for endothelial adhesion molecules, intercellular adhesion molecule (ICAM)-1, and E-selectin gene expression. Leukocyte emigration was assessed via CD13 immunohistochemistry, and gelatinase accumulation was determined by gelatin zymography. RESULTS: Laminar concentrations of IL-1beta, IL-6, IL-8, COX-2, ICAM-1, and E-selectin mRNA were significantly increased in ETP horses, compared with control horses. Concentrations of IL-1beta, IL-8, ICAM-1, and E-selectin mRNA peaked at 1.5 hours. In ETP horses, leukocyte emigration was present in 3 of 5 horses and pro-MMP-9 was detected in 2 of 5 horses. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that endothelial activation and laminar inflammation are early events in laminitis; MMP accumulation likely is a downstream event.

Dynamic changes in circulating leukocytes during the induction of equine laminitis with black walnut extract.

Administration of black walnut heartwood extract (BWHE) via nasogastric tube induces acute laminitis in horses. However, the processes responsible for the development of laminitis, including laminitis induced with BWHE, remain unclear. The results of recent studies indicate that administration of BWHE initiates an inflammatory response in the laminar tissues and that this response may be due to extravasation of activated leukocytes from the circulation. This study examines the effects of BWHE administration on the dynamics of circulating neutrophils and monocytes, and the capacity of blood leukocytes to produce radical oxygen species (ROS) over the time period from administration of BWHE to the development of lameness consistent with Obel grade I laminitis. Individual horses, free of pre-existing musculoskeletal disease, were administered either 6l of BWHE or an equal volume of water at time 0 (T=0). Blood samples were collected prior to dosing and at 1, 2, 3, 4, 6, 8, 10 and 12h after dosing, or until the onset of Obel grade I laminitis. For each sample, total leukocyte counts were determined followed by collection of buffy coats and removal of erythrocytes by hypotonic lysis. Leukocytes were either fixed for flow cytometric assessment of differential counts or maintained in culture to measure endogenous and phorbol ester-induced production of ROS. At each sample time, the number of cells recovered and the flow cytometric differential counts were compared with corresponding total leukocyte counts determined by the Clinical Pathology laboratory. Horses administered BWHE had a significant reduction in circulating leukocytes at 3-4 h relative to values for horses administered the same volume of water. Horses that developed Obel grade I laminitis had a significant reduction in circulating leukocytes when compared to values for horses administered BWHE that did not become lame. Flow cytometric analysis revealed a consistent decrease in the total number of monocytes obtained from horses that developed laminitis. In these same horses, the endogenous level of ROS production was significantly higher at T=0 than for horses that did not become lame. Furthermore, production of ROS by leukocytes from horses that developed laminitis increased significantly and coincided with the decrease in circulating leukocytes. Collectively, these findings support a role for systemic activation of leukocytes and induction of inflammation by BWHE as a factor in the early pathogenesis of acute laminitis. Because laminitis often develops as a sequel to diseases characterized by systemic inflammatory events, activation and emigration of neutrophils and monocytes may be important factors in the early pathogenesis of laminitis in clinical cases.

Studies on the concentrations of arsenic, selenium, copper, zinc and iron in the hair of blackfoot disease patients in different clinical stages.

Flame atomic absorption spectrophotometric methods were developed for, arsenic, selenium, copper, zinc and iron in hair samples. Data from blackfoot disease patients at five clinical stages were compared with those from healthy controls. The copper and zinc concentrations showed only slight differences in all clinical stages, which indicated the less relation to blackfoot disease. The decrease of selenium and iron in all stages was attributed to the antagonistic effect of arsenic; arsenic increased in the first and second stages, but decreased in the later stages. The decrease of selenium and iron during the progression of the disease is thought to be due to persistence of the antagonistic effect of arsenic in the initial stages, so that very low concentrations of selenium are found in the advanced stages, despite the later decrease of arsenic. There was also a progressive decrease of iron with advance of the disease, and the later stages also showed a decrease in haemoglobin. It was shown that arsenic is a major cause of blackfoot disease, and that it antagonises selenium and iron, which decreased in the advanced clinical stages of the disease.

Trace elements in hair of Blackfoot disease.

Blackfoot disease is a peripheral vascular disease resulting in gangrene of the lower extremities. Though extensive epidemiological study has implicated that high arsenic content in artesian well water of the endemic area bears some important connection with the disease, the etiology of the disease is still unknown. In this study, attention is paid to multielement determination in order to find out whether the trace elements in hair of Blackfoot disease patients are different from those of the controls. Experimental results indicate that the concentrations of As and Se in hair of patients are significantly higher than those of the controls, but Ca and Zn are significantly lower than those of the controls. The possible connection of these elements with the etiology of the disease is discussed.

Neonatal capsaicin treatment attenuates spinal Fos activation and dynorphin gene expression following peripheral tissue inflammation and hyperalgesia.

An animal model of nociception involving unilateral hindpaw inflammation has been used to examine behavioral, molecular, and biochemical aspects of well-characterized spinal cord neural circuits involved in pain transmission. The neurotoxin capsaicin administered neonatally was used to modify this neuronal system by producing a selective destruction of most small, unmyelinated primary afferent axons. Capsaicin had minimal effects on the behavioral hyperalgesia and edema associated with the hindpaw inflammation and on the constitutive expression of preprodynorphin (PPD) mRNA and preproenkephalin mRNA in the spinal cord. However, the inflammation-induced increases in Fos-like immunoreactivity (Fos-LI) and in PPD mRNA were greatly attenuated by neonatal capsaicin treatment. The data indicate that input from small-diameter unmyelinated primary afferents is important for the stimulus-induced increase in Fos-LI and PPD mRNA. Our finding that neonatal capsaicin reduces the levels of Fos-LI and PPD mRNA in a related fashion in the spinal dorsal horn provides further evidence for a relationship between the protein product of the c-fos protooncogene and regulation of dynorphin gene transcription.

Biotin studies in pigs. 1. Biotin deficiency in the young pig.

Sixteen pigs were given a purified diet of maize flour and casein from 5 to 25 d of age with or without a biotin supplement (100 micrograms/kg). From 26 to 94 d of age, eight of the pigs were changed to a wheat and casein diet with or without the biotin supplement and eight continued on the maize flour and casein diet. The weight gain and feed conversion ratio of the pigs were not affected by the dietary biotin supplement or the carbohydrate source. The pigs given the unsupplemented maize flour diet developed foot lesions, scaly skins and showed a reduction in carcass length. The excretion of biotin in the faeces was similar for the pigs given the biotin-supplemented and unsupplemented diets. The excretion of biotin in the faeces of pigs given the wheat diet was ten times as great as that of the pigs given the maize flour diet. The excretion of biotin in urine was 6 micrograms/d in the pigs given the unsupplemented maize flour diet and 67 micrograms/d in the pigs given the biotin-supplemented diet between 91 and 94 d of age. The biotin contents of the liver, heart, kidney, adrenals and plasma were increased by biotin supplementation of the maize flour diet. The 16:1/16:0 and 18:1/18:0 fatty acids ratios in the liver were decreased by biotin supplementation of the maize flour diet.

Impact of hyperthermic regional perfusion therapy on cell metabolism of malignant melanoma monitored by 31P MR spectroscopy.

For the first time, the influence of hyperthermic regional perfusion therapy on tumor cell metabolism has been monitored by means of 31P MR spectroscopy. Shortly after treatment, a complete depletion of high energy phosphates, a significant increase of inorganic phosphate, phosphomono- and phosphodiester resonances and a decrease of pH have been observed. Healthy muscle tissue showed only minor effects caused by this aggressive therapy. The time course of the transient variation of phosphate metabolite concentrations is explained in the framework of a simple pathophysiological model. The results demonstrate that the imediate effect of chemotherapy on tumor tissue can be detected by 31P MRS before any clinical signs of tumor response are visible.