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Background: On the basis of the contradiction between data on experimental head trauma showing oxidative stress-mediated cerebral tissue damage and failure of the majority of clinical trials using free radical scavenger drugs, we monitored the time-course changes of malondialdehyde (MDA, an index of cell lipid peroxidation), ascorbate, and dephosphorylated ATP catabolites in cerebrospinal fluid (CSF) of traumatic brain-injured patients.Methods: CSF samples were obtained from 20 consecutive patients suffering from severe brain injury. All patients were comatose, with a Glasgow Coma Scale on admission of 6 +/- 1. The first CSF sample for each patient was collected within a mean value of 2.95 hours from trauma (SD=1.98), after the insertion of a ventriculostomy catheter for the continuous monitoring of intracranial pressure. During the next 48 hours, CSF was withdrawn from each patient once every 6 hours. All samples were analyzed by an ion-pairing high-performance liquid chromatographic method for the simultaneous determination of MDA, ascorbic acid, hypoxanthine, xanthine, uric acid, inosine, and adenosine.Results: In comparison with values recorded in 10 herniated-lumbar-disk, noncerebral control patients, data showed that all CSF samples of brain-injured patients had high values (0.226 micromol/L; SD=0.196) of MDA (undetectable in samples of control patients) and decreased ascorbate levels (96.25 micromol/L; SD=31.74), already at the time of first withdrawal at the time of hospital admission. MDA was almost constant in the next two withdrawals and tended to decrease thereafter, although 48 hours after hospital admission, a mean level of 0.072 micromol/L CSF (SD=0.026) was still recorded. The ascorbate level was normalized 42 hours after hospital admission. Changes in the CSF values of ATP degradation products (oxypurines and nucleosides) suggested a dramatic alteration of neuronal energy metabolism after traumatic brain injury.Conclusions: On the whole, these data demonstrate the early onset of oxygen radical-mediated oxidative stress, proposing a valid explanation for the failure of clinical trials based on the administration of oxygen free radical scavenger drugs and suggesting a possible rationale for testing the efficacy of lipid peroxidation "chain breakers" in future clinical trials. [ABSTRACT FROM AUTHOR]

Hospital logistics automation applied to the dispensing of medicines to patients in care transition (hospital discharge or outpatient visit) offers significant opportunities to improve risk management and ensure the quality of healthcare. The adoption of technological innovation in hospital requires organizational changes, development of new workflows, collaboration between different professionals and acquisition of new skills. The logistics automation system was analyzed using NOISE analysis, as a strategic planning tool, in order to assess the impact of this innovation. The analysis highlighted the consistency of the innovation with local health policies, the assessment of feasibility in the hospital context and the reorganization focused on process optimization. As a result, operational steps were initiated leading to the acquisition of the new technology in February 2023. The application of strategic planning techniques to healthcare processes is crucial to ensure technological advancement in healthcare, the maximization of public investments and the development of a new professional culture capable of optimising innovations.

Purpose: Telepharmacy (TF) represents a tool to manage the complexity related to drug therapies and to guarantee continuity of patient empowerment in transitions of care. The aim of this work is to analyze the critical issues related to the implementation of the TF service, in order to enhance its application., Results: Over 27 months, the TF service was offered to 60 patients. 48% of patients used the service (mean age=38 years; N=13 (45%) M). Although they accepted the service, 17% of patients (mean age=56 years; N=2 (20%) M) were unable to access the platform once they returned home. Poor digital skills and lack of a caregiver were barriers to service acceptance for 35% of patients (mean age=63 years; N=13 (62%) M). Overall, patients with a mean age ≥56 years did not use the service., Conclusions: TF represents an opportunity in care transitions to identify early critical issues related to drug therapy and to contribute to the integration of different levels of care. The analysis highlights that only the youngest patients (with an average age of 38 years), being more skilled in IT, have actually had access to the TF service. It will be necessary in the near future to make health teleconsultations increasingly widespread and accessible.

This study explores the potential use of ChatGPT, an AI-based language model, in assessing herbal-drug interactions (HDi) to enhance clinical decision-making. HDi can pose significant health risks by reducing drug efficacy or causing unwanted side effects. Clinical pharmacists play a key role in identifying these HDIs, and currently, there are limited tools available for checking drug interactions. The research focuses on a case study of a rectal adenocarcinoma patient treated with capecitabine and 26 supplements, which contain a total of 80 herbal substances. ChatGPT 3.5 was asked three questions regarding potential HDIs: "Are there possible HDIs?", "What is the pharmacokinetic mechanism?", and "What is the bibliographic source of the interaction?". The results were reviewed by an oncology clinical pharmacist and compared to existing databases and independent bibliographic research. The findings highlight ChatGPT's advantage in processing large amounts of data quickly, with 16% of interactions classified as "unlikely", confirmed by the pharmacist. However, 73% of the suggested mechanisms were false positives, and 4% were categorized as "hallucinations". Additionally, most of the bibliographic sources provided by ChatGPT were outdated or unavailable. While ChatGPT proves useful for initial HDI screening, its limitations include outdated data (last updated in January 2022), lack of access to private databases, and occasional inaccuracies. Further applications of AI in this area are recommended, though expert validation remains essential in the clinical decision-making process.

The protein kinase C activator phorbol 12-myristate 13-acetate (PMA) is known to interact with aquaporin 4 (AQP 4), a water-selective transporting protein that is abundant in astrocytes, and has experimentally been found to decrease osmotically-induced cell swelling. The purpose of this study was to examine whether PMA reduces brain edema following focal ischemia induced by middle cerebral artery (MCA) occlusion by modulation of AQP4 expression. Male Sprague-Dawley rats were randomly assigned to either sham surgery (n = 6), or a continuous intravenous infusion of vehicle (1% dimethylsulfoxide), followed by MCA occlusion (n = 18), and administration of PMA at 50 microg/kg (n = 6) or at 200 microg/kg (n = 6) starting 60 min before or 30 min (200 microg/kg; n = 6) or 60 min (200 microg/kg; n = 6) after MCA occlusion. Cerebral blood flow was monitored with laser Doppler over the MCA territory, and confirmed a 70% reduction during occlusion. After a 2-h period of ischemia and 2 h of reperfusion, the animals were sacrificed for assessment of brain water content and sodium and potassium concentration. AQP4 expression was assessed by immunoblotting and quantified by densitometry (n = 24). Statistical analysis was performed by ANOVA followed by Tukey's post-hoc test. PMA treatment at 200 microg/kg significantly reduced brain water concentration in the infarcted area when started 60 min before or 30 min after occlusion (p < 0.001 and p = 0.022, respectively), and prevented the subsequent sodium shift (p < 0.05). PMA normalized the AQP4 upregulation in ischemia (p = 0.021). A downregulation of AQP4 in the ischemic area paralleling the reduction in brain edema formation following PMA treatment suggests that the effect was mediated by AQP4 modulation.

Background: We have pursued the concept that traumatic brain edema is predominantly cellular and that water entry is modulated in part by aquaporins. Aquaporin-4 (AQP4) has been shown to play a significant role in cellular edema formation. Phorbol myristate acetate (PMA) is a potent PKC activator; purportedly involved in modulation of AQP4 activity. Alternatively, AQP4 may be regulated by arginine-vasopressin. Administration of the vasopressin antagonist (SR49059) reduced brain water content and sodium shift following MCAo. To investigate if edema formation is affected by the reduction of AQP4 expression, we utilized PMA and SR49059 following middle cerebral artery occlusion model (MCAo), and measured AQP4 expression by Western-Blot (WB) techniques., Methods: Male Sprague Dawley rats were randomly assigned to sham (n=4) or MCAo groups (vehicle, PMA or SR49059 infusion; n=6 each). Each solution was infused for 5 hours, starting 1 hour before injury. After a two-hour period of ischemia and two-hour reperfusion, animals were sacrificed and brain regions of interest were processed by WB to quantify the effect of treatment on AQP4 expression., Results: These studies demonstrate that MCAo results in a significant up-regulation of AQP4 on the ischemic zone when compared to the contralateral un-injured hemisphere (p < 0.05) and that PMA and SR49059 treatment significantly down-regulated AQP4 expression compared to the vehicle group (p < 0.05)., Conclusions: These studies support the hypotheses that PMA and SR49059 may be useful in reducing cerebral water accumulation by modulating AQP4 expression and that pharmacological manipulation of AQP4 may emerge as a viable strategy for the reduction of fulminating edema following ischemic injury.

Objectives: To compare biochemical and clinical parameters in a case of fatal severe traumatic brain injury (TBI) with secondary insult., Design and Methods: A TBI patient was catheterized for intracranial pressure (ICP) monitoring and cerebrospinal fluid (CSF) analysis of ascorbate, malondialdehyde, oxypurines, and nucleosides., Results: Oxidative brain damage preceded ATP catabolite increment in the CSF even with ICP below 20 mm Hg. Sustained oxidative stress caused irreversible energy state derangement followed by a refractory ICP rise. Massive oxypurine and nucleoside release was recorded 36 h before brain death., Conclusions: Molecular events, detected by biochemical CSF analysis and preceding modification of clinical parameters in severe TBI with secondary insult, are discussed.

A simple and reliable method for the preparation of biological samples for the evaluation of biochemical parameters representative of the redox and energy states, such as glutathione (GSH), oxidized glutathione (GSSG), oxidized nicotinamide adenine dinucleotide (NAD+), reduced nicotinamide adenine dinucleotide (NADH), oxidized nicotinamide adenine dinucleotide phosphate (NADP+), reduced nicotinamide adenine dinucleotide phosphate (NADPH), coenzyme A (CoASH), oxidized CoASH, ascorbate, malondialdehyde, oxypurines, nucleosides, and energy metabolites, is presented. Fast deproteinization under nonoxidizing conditions is obtained by tissue homogenization in ice-cold, nitrogen-saturated CH3CN + 10 mM KH2PO4 (3:1; v:v), pH 7.40. After sample centrifugation to pellet precipitated proteins, organic solvent removal is performed on clear supernatants by three washings with large volumes of high-performance liquid chromatography (HPLC)-grade chloroform. The remaining aqueous phase, free of solvent and any lipid-soluble substances that may interfere with the further metabolite analysis, is used for the simultaneous ion-pairing HPLC determination of 39 compounds by means of a Kromasil C-18, 250 x 4.6-mm, 5-microm-particle-size column with tetrabutylammonium hydroxide as the pairing reagent. Results obtained by using the present method to prepare different rat tissue extracts demonstrate that it is possible to perform a single tissue preparation only for monitoring, in the same sample, compounds representative of the redox state (through the direct determination of GSH, GSSG, NAD+, NADH, NADP+, NADPH, CoASH, and oxidized CoASH) and of the cell energy state (by the analysis of oxypurines, nucleosides, and energy metabolites). Applicability of this sample processing procedure to quantify variations of the aforementioned compounds under pathological conditions was effected in rats subjected to moderate closed-head trauma.

Atrial natriuretic peptide (ANP) plays an important role in the regulation of water and sodium in the body via cyclic GMP (cGMP) pathway. Although ANP has been shown to be protective in cerebral ischemia or intracerebral hemorrhage, its role in traumatic brain injury (TBI) has yet to be elucidated. We herein assessed ANP effects on brain water and sodium in TBI. Controlled cortical impact (3 mm depth, 6 m/sec) was used to induce an experimental cortical contusion in rats. Continuous administration of ANP 0.2 (n = 6) or 0.7 microg/kg/24 h (n = 6), cGMP analogue (8-Bromo-cGMP) 0.1 (n = 5) or 0.3 mg/kg/24 h (n = 5), or vehicle (n = 6) was begun 15 minutes after injury, using a mini-osmotic pump implanted into the peritoneal cavity. At 24 hours after injury, ANP significantly exacerbated brain edema in the injured hemisphere in a dose-dependent manner while it reduced brain sodium concentrations in both hemispheres. These ANP effects could be mimicked by a cGMP analogue. In the second series (n = 20), BBB integrity was assessed by evaluating the extravasation of Evans blue dye. ANP or cGMP analogue significantly worsened BBB disruption in the injured hemisphere at 24 hours after injury. These findings suggest that ANP administration exacerbates brain edema after the experimental cortical contusion in rats, possibly because of an increase in the BBB permeability via cGMP pathway, whereas it reduces brain sodium levels.

The cyanidin-3-O-beta-glucopyranoside (C-3-G) antioxidant capacity towards reactive oxygen species (ROS)-mediated damages was assessed in tissue and cells submitted to increased oxidative stress. In the isolated ischemic and reperfused rat heart, 10 or 30 degreesM C-3-G protected from both lipid peroxidation (66.7 and 94% inhibition of malondialdehyde (MDA) generation in 10 and 30 microM C-3-G-reperfused hearts, respectively, in comparison with control reperfused hearts) and energy metabolism impairment (higher ATP concentration in 10 and 30 microM C-3-G-reperfused hearts than in control reperfused hearts). These effects were associated to C-3-G permeation within myocardial cells, as indicated by results obtained in the isolated rat heart perfused for 30 min in the recirculating Langendorff mode under normoxia with 10 and 30 microM C-3-G. Protective effects were exerted, in a dose-dependent manner, by C-3-G also in 2 mM hydrogen peroxide-treated human erythrocytes. With respect to MDA formation, an apparent IC50 of 5.12 microM was calculated for C-3-G (the polyphenol resveratrol used for comparison showed an apparent IC50 of 38.43 microM). The general indications are that C-3-G (largely diffused in dietary plants and fruits, such as pigmented oranges very common in the Mediterranean diet) represents a powerful natural antioxidant with beneficial effects in case of increased oxidative stress, and at pharmacological concentrations it is able to decrease tissue damages occurring in myocardial ischemia and reperfusion.

The effect of oxidative stress on human red blood cell AMP-deaminase activity was studied by incubating either fresh erythrocytes or hemolysates with H(2)O(2) (0.5, 1, 2, 4, 6, 8, and 10 mm) or NaNO(2) (1, 5, 10, 20, and 50 mm), for 15 min at 37 degrees C. AMP-deaminase tremendously increased by increasing H(2)O(2) or NaNO(2) at up to 4 and 20 mm, respectively (maximal effect for both oxidants was 9.5 and 6.5 times higher enzymatic activity than control erythrocytes or hemolysates, respectively). The incubation of hemolysates with iodoacetate (5-100 mm), N-ethylmaleimide (0.1-10 mm), or p-hydroxymercuribenzoate (0.1-5 mm) mimicked the effect of oxidative stress on AMP-deaminase, indicating that sulfhydryl group modification is involved in the enzyme activation. In comparison with control hemolysates, changes of the kinetic properties of AMP-deaminase (decrease of AMP concentration necessary for half-maximal activation, increase of V(max), modification of the curve shape of V(o) versus [S], Hill plots, and coefficients) were recorded with 4 mm H(2)O(2)- and 1 mm N-ethylmaleimide-treated hemolysates. Data obtained using 90% purified enzyme, incubated with Fenton reagents (Fe(2+) + H(2)O(2)) or -SH-modifying compounds, demonstrated that (i) reactive oxygen species are directly responsible for AMP-deaminase activation; (ii) this phenomenon occurs through sulfhydryl group modification; and (iii) the activation does not involve the loss of the tetrameric protein structure. Results of experiments conducted with glucose-6-phosphate dehydrogenase-deficient erythrocytes, challenged with increasing doses of the anti-malarial drug quinine hydrochloride and showing dramatic AMP-deaminase activation, suggest relevant physiopathological implications of this enzymatic activation in conditions of increased oxidative stress. To the best of our knowledge, this is the first example of an enzyme, fundamental for the maintenance of the correct red blood cell energy metabolism, that is activated (rather than inhibited) by the interaction with reactive oxygen species.

In the present study, the antioxidant activity, the interaction with reactive oxygen species and the redox potential of cyanidin-3-O-beta-glucopyranoside (C-3-G), the main anthocyanin present in juice of pigmented oranges, were evaluated in detail. C-3-G effects on low density lipoproteins (LDL) oxidation induced by 40 microM Cu at a pH of 7.4 were compared with those of resveratrol and ascorbic acid, two other natural antioxidants. All cyanidin-3-O-beta-glucopyranoside concentrations used (1, 2, 5, 10, 20, 50, 100 and 200 microM) inhibited malondialdehyde (MDA) generation (an index of lipid peroxidation), the inhibition being significantly higher than that obtained with equal concentrations of resveratrol and ascorbic acid (IC50 = 6.5 microM for C-3-G, 34 microM for resveratrol and 212 microM for ascorbic acid). Experiments of LDL oxidation performed at a pH of 5.0 or 6.0 showed that C-3-G antioxidant activity is not influenced by pH variations between 5.0 and 7.4. This suggests that metal chelation, exerted by C-3-G through the eventual dissociation of its phenolic groups, plays a minor role in its protective mechanism. The presence of C-3-G produced significantly higher protective effects of pigmented orange juice (obtained from Moro cultivar) with respect to blond orange juice, when tested on copper-induced LDL oxidation. The evaluation of the direct interaction with reactive oxygen species (H2O2, -O2, OH*), demonstrated that C-3-G is quickly oxidized by these compounds and it is, therefore, a highly efficient oxygen free radical scavenger. The powerful C-3-G antioxidant activity is in excellent agreement with the very negative redox potential (-405 mV), determined through direct current cyclic voltammetry measurements. On the basis of these results, C-3-G should be considered as one of the most effective antioxidants that can be assumed with dietary plants; therefore, pigmented oranges represent a very relevant C-3-G source because of the high content of this anthocyanin in their juice.

Background: On the basis of the contradiction between data on experimental head trauma showing oxidative stress-mediated cerebral tissue damage and failure of the majority of clinical trials using free radical scavenger drugs, we monitored the time-course changes of malondialdehyde (MDA, an index of cell lipid peroxidation), ascorbate, and dephosphorylated ATP catabolites in cerebrospinal fluid (CSF) of traumatic brain-injured patients., Methods: CSF samples were obtained from 20 consecutive patients suffering from severe brain injury. All patients were comatose, with a Glasgow Coma Scale on admission of 6 +/- 1. The first CSF sample for each patient was collected within a mean value of 2.95 hours from trauma (SD=1.98), after the insertion of a ventriculostomy catheter for the continuous monitoring of intracranial pressure. During the next 48 hours, CSF was withdrawn from each patient once every 6 hours. All samples were analyzed by an ion-pairing high-performance liquid chromatographic method for the simultaneous determination of MDA, ascorbic acid, hypoxanthine, xanthine, uric acid, inosine, and adenosine., Results: In comparison with values recorded in 10 herniated-lumbar-disk, noncerebral control patients, data showed that all CSF samples of brain-injured patients had high values (0.226 micromol/L; SD=0.196) of MDA (undetectable in samples of control patients) and decreased ascorbate levels (96.25 micromol/L; SD=31.74), already at the time of first withdrawal at the time of hospital admission. MDA was almost constant in the next two withdrawals and tended to decrease thereafter, although 48 hours after hospital admission, a mean level of 0.072 micromol/L CSF (SD=0.026) was still recorded. The ascorbate level was normalized 42 hours after hospital admission. Changes in the CSF values of ATP degradation products (oxypurines and nucleosides) suggested a dramatic alteration of neuronal energy metabolism after traumatic brain injury., Conclusions: On the whole, these data demonstrate the early onset of oxygen radical-mediated oxidative stress, proposing a valid explanation for the failure of clinical trials based on the administration of oxygen free radical scavenger drugs and suggesting a possible rationale for testing the efficacy of lipid peroxidation "chain breakers" in future clinical trials.

The effect of different oxygen radical-generating systems on NAD(P)H was determined by incubating the reduced forms of the pyridine coenzymes with either Fe2+-H2O2 or Fe3+-ascorbate and by analyzing the reaction mixtures using a HPLC separation of adenine nucleotide derivatives. The effect of the azo-initiator 2,2'-azobis(2-methylpropionamidine)dihydrochloride was also tested. Results showed that, whilst all the three free radical-producing systems induced, with different extent, the oxidation of NAD(P)H to NAD(P)+, only Fe2+-H2O2 also caused the formation of equimolar amounts of ADP-ribose(P) and nicotinamide. Dose-dependent experiments, with increasing Fe2+ iron (concentration range 3-180 microM) or H2O2 (concentration range 50-1000 microM), were carried out at pH 6.5 in 50 mM ammonium acetate. NAD(P)+, ADP-ribose(P) and nicotinamide formation increased by increasing the amount of hydroxyl radicals produced in the medium. Under such incubation conditions NAD(P)+/ADP-ribose(P) ratio was about 4 at any Fe2+ or H2O2 concentration. By varying pH to 2.0, 3.0, 4.0, 4.5, 5.0, 5.5, 6.0, 7.0 and 7.4, NAD(P)+/ADP-ribose(P) ratio changed to 5.5, 3.2, 1.8, 1.6, 2.0, 2.5, 3.0, 5.4 and 6.5, respectively. Kinetic experiments indicated that 90-95% of all compounds were generated within 5s from the beginning of the Fenton reaction. Inhibition of ADP-ribose(P), nicotinamide and NAD(P)+ production of Fe2+-H2O2-treated NAD(P)H samples, was achieved by adding mannitol (10-50 mM) to the reaction mixture. Differently, selective and total inhibition of ADP-ribose(P) and nicotinamide formation was obtained by performing the Fenton reaction in an almost completely anhydrous medium, i.e. in HPLC-grade methanol. Experiments carried out in isolated postischemic rat hearts perfused with 50 mM mannitol, showed that, with respect to values of control hearts, this hydroxyl radical scavenger prevented reperfusion-associated pyridine coenzyme depletion and ADP-ribose formation. On the basis of these results, a possible mechanism of action of ADP-ribose(P) and nicotinamide generation through the interaction between NAD(P)H and hydroxyl radical (which does not involve the C-center where "conventional" oxidation occurs) is presented. The implication of this phenomenon in the pyridine coenzyme depletion observed in postischemic tissues is also discussed.

To study the influence of oxidative stress on energy metabolism and lipid peroxidation in erythrocytes, cells were incubated with increasing concentrations (0.5-10 mM) of hydrogen peroxide for 1 h at 37 degrees C and the main substances of energy metabolism (ATP, AMP, GTP and IMP) and one index of lipid peroxidation (malondialdehyde) were determined by HPLC on cell extracts. Using the same incubation conditions, the activity of AMP-deaminase was also determined. Under nonhaemolysing conditions (at up to 4 mM H2O2), oxidative stress produced, starting from 1 mM H2O2, progressive ATP depletion and a net decrease in the intracellular sum of adenine nucleotides (ATP + ADP + AMP), which were not paralleled by AMP formation. Concomitantly, the IMP level increased by up to 20-fold with respect to the value determined in control erythrocytes, when cells were challenged with the highest nonhaemolysing H2O2 concentration (4 mM). Efflux of inosine, hypoxanthine, xanthine and uric acid towards the extracellular medium was observed. The metabolic imbalance of erythrocytes following oxidative stress was due to a dramatic and unexpected activation of AMP-deaminase (a twofold increase of activity with respect to controls) that was already evident at the lowest dose of H2O2 used; this enzymatic activity increased with increasing H2O2 in the medium, and reached its maximum at 4 mM H2O2-treated erythrocytes (10-fold higher activity than controls). Generation of malondialdehyde was strictly related to the dose of H2O2, being detectable at the lowest H2O2 concentration and increasing without appreciable haemolysis up to 4 mM H2O2. Besides demonstrating a close relationship between lipid peroxidation and haemolysis, these data suggest that glycolytic enzymes are moderately affected by oxygen radical action and strongly indicate, in the change of AMP-deaminase activity, a highly sensitive enzymatic site responsible for a profound modification of erythrocyte energy metabolism during oxidative stress.

An ion-pairing high-performance liquid chromatographic method for the determination of N-acetylaspartate and N-acetylglutamate using a C-18 column and a UV detection at 210 nm wavelength, by means of a diode array detector, is presented. A buffer containing 2.8 mM tetrabutylammonium hydroxide, 25 mM KH(2)PO(4), 1.25% methanol, pH 7. 00, is utilized for the isocratic separation of these N-acetylated amino acids, at a flow rate of 1 ml/min and a column temperature of 23 degrees C. The suitability of this chromatographic separation (without additional chromatographic steps prior to HPLC assay) to monitor variations both of N-acetylaspartate and of N-acetylglutamate in perchloric acid brain extracts from rats subjected to the impact acceleration model of diffuse brain injury is also reported. According to the data presented, this HPLC method allows the separation of the two N-acetylated amino acids considered from the many possible interfering compounds, commonly present in extracts of cerebral tissue, which have high extinction coefficients at 210 nm wavelength. Values of N-acetylaspartate and N-acetylglutamate determined by this method showed that cerebral trauma negatively affects both compounds, according to the severity of trauma itself., (Copyright 2000 Academic Press.)

The effect of mild closed head trauma, induced by the weight-drop method (450 g from a 1-m height), on lipid peroxidation and energy metabolism of brain tissue was determined at various times after cerebral injury in spontaneously breathing rats (1, 10, 30 minutes and 2, 6, 15, 24, 48, and 120 hours). Animals were continuously monitored for the evaluation of blood pressure, blood gases, heart rate, and intracranial pressure. Analysis of malondialdehyde (MDA) as an index of lipid peroxidation, ascorbic acid, high-energy phosphates, nicotinic coenzymes, oxypurines, and nucleosides was performed by high-performance liquid chromatography (HPLC) on neutralized perchloric acid extract of the whole brain. Data showed that MDA, undetectable in control, sham-operated rats, was already present within 1 minute of trauma (1.77 nmol/g wet weight; SD = 0.29) and reached maximal values by 2 hours (72.26 nmol/g w.w.; SD = 11.26), showing a progressive slow decrease thereafter. In contrast, ATP, GTP, and nicotinic coenzyme (NAD and NADP) concentrations showed significant reduction only by the second hour postinjury. Maximal decrease of the ATP and GTP concentrations were seen at 6 hours postinjury, whereas NAD and NADP concentrations showed maximum decline by 15 hours. Values recorded in mechanically ventilated rats did not differ significantly from those obtained in spontaneously breathing animals. These findings, supported by the absence of blood gas and blood pressure changes in the spontaneously breathing rats, strongly support the premise that biochemical changes (primarily lipid peroxidation) are not caused by secondary ischemic-hypoxic phenomena but rather are triggered by these forces acting on the brain at the time of impact. In addition, these results suggest that depression of energy metabolism might be caused by peroxidation of the mitochondrial membrane with a consequent alteration of the main mitochondrial function-that is, the energy supply.