Circulating anions usually associated with the Krebs cycle in patients with metabolic acidosis

Introduction: Acute metabolic acidosis of non-renal origin is usually a result of either lactic or ketoacidosis, both of which are associated with a high anion gap. There is increasing recognition, however, of a group of acidotic patients who have a large anion gap that is not explained by either keto- or lactic acidosis nor, in most cases, is inappropriate fluid resuscitation or ingestion of exogenous agents the cause. Methods: Plasma ultrafiltrate from patients with diabetic ketoacidosis, lactic acidosis, acidosis of unknown cause, normal anion gap metabolic acidosis, or acidosis as a result of base loss were examined enzymatically for the presence of low molecular weight anions including citrate, isocitrate, α-ketoglutarate, succinate, malate and d-lactate. The results obtained from the study groups were compared with those obtained from control plasma from normal volunteers. Results: In five patients with lactic acidosis, a significant increase in isocitrate (0.71 ± 0.35 mEq l-1), α-ketoglutarate (0.55 ± 0.35 mEq l-1), malate (0.59 ± 0.27 mEq l-1), and d-lactate (0.40 ± 0.51 mEq l-1) was observed. In 13 patients with diabetic ketoacidosis, significant increases in isocitrate (0.42 ± 0.35 mEq l-1), α-ketoglutarate (0.41 ± 0.16 mEq l-1), malate (0.23 ± 0.18 mEq l-1) and d-lactate (0.16 ± 0.07 mEq l-1) were seen. Neither citrate nor succinate levels were increased. Similar findings were also observed in a further five patients with high anion gap acidosis of unknown origin with increases in isocitrate (0.95 ± 0.88 mEq l-1), α-ketoglutarate (0.65 ± 0.20 mEq l-1), succinate (0.34 ± 0.13 mEq l-1), malate (0.49 ± 0.19 mEq l-1) and d-lactate (0.18 ± 0.14 mEq l-1) being observed but not in citrate concentration. In five patients with a normal anion gap acidosis, no increases were observed except a modest rise in d-lactate (0.17 ± 0.14 mEq l-1). Conclusion: The levels of certain low molecular weight anions usually associated with intermediary metabolism were found to be significantly elevated in the plasma ultrafiltrate obtained from patients with metabolic acidosis. Our results suggest that these hitherto unmeasured anions may significantly contribute to the generation of the anion gap in patients with lactic acidosis and acidosis of unknown aetiology and may be underestimated in diabetic ketoacidosis. These anions are not significantly elevated in patients with normal anion gap acidosis

The Use of Cisplatin in the Management of Appendicular Osteosarcoma in the Dog

This dissertation presents analysis of various features of cases of canine osteosarcoma (including one case of chondrosarcoma) managed in the Department of Veterinary Surgery, Glasgow University Veterinary School. These features include: -the clinical outcome in cases managed with surgery and cisplatin chemotherapy - experiences with the use of bone allografts for limb reconstruction following en bloc resection - analysis of certain aspects of the pharmacokinetics of the drug administered to selected patients These findings are presented in the light of published work on the treatment of osteosarcoma and the use of cisplatin in the dog and man. The major conclusions are: - subsets of the tumour may exist, with the potential for varying biological behaviour - the management of osteosarcoma with cisplatin chemotherapy has a positive benefit on survival, in selected patients, but death due to metastatic disease is almost inevitable - the design of chemotherapeutic protocols for canine osteosarcoma is not finalised - though the area under the platinum in plasma ultrafiltrate concentration-time curve gave a consistent value in the clinic at Glasgow University Veterinary School it is not suitable, in isolation, for comparing administration protocols - the use of massive allografts in conjunction with cisplatin chemotherapy requires further evaluation - multi-centre prospective trials would be the way to pursue these goals

Influence of single and multiple doses of amifostine on the efficacy and the pharmacokinetics of carboplatin in mice.

We have previously reported that amifostine potentiates the anti-tumour activity of carboplatin in mice. The present study was carried out in well-established human ovarian cancer xenografts OVCAR-3, A2780 and FMa grown subcutaneously in the nude mouse. It was found that a single dose of amifostine resulted in a higher increase in the anti-tumour activity of carboplatin than three doses of amifostine. A single dose of amifostine increased the AUC (area under the curve) values of total platinum in plasma ultrafiltrate (30.1 vs 18.2 microM x h), liver (307.7 vs 236.4 nmol g(-1) x h), kidney (500.8 vs 368.3 nmol g(-1) x h) and OVCAR-3 tumour tissue (184.0 vs 146.8 nmol g(-1) x h). Despite this increase in total platinum, a decrease in platinum (Pt)-DNA adduct levels was observed in liver, kidney and bone marrow, which was significant in liver. In tumour tissue an insignificant increase in Pt-DNA adduct levels, specifically the Pt-GG adduct, was observed after treatment with a single dose of amifostine, which may explain the increase in anti-tumour activity. The increase in the AUC of total platinum was probably caused by a reduction in body temperature, which was most severe after three doses of amifostine. The extreme hypothermia may be the reason that three doses of amifostine resulted in less potentiation of the efficacy of carboplatin

Possible depression of canine papillary muscle contractility with plasma from aged dogs

http://www.worldcat.org/oclc/589981

Phase I clinical and pharmacokinetic study of the oral platinum analogue JM216 given daily for 14 days

Background: The oral bis (acetate) ammine dichloro cyclo-hexylamine platinum (IV) analogue (BMS-182751) was brought into clinical development because it was shown to be cytotoxic against some human tumour cell lines and to have an antitu-mor activity in murine tumours at least comparable to that of parenteral cisplatin and carboplatin. In early clinical studies in which the optimal schedule of treatment was daily for five consecutive days, dose-dependent nausea and vomiting occurred in about two-thirds of patients. Patients and methods: To evaluate if the use of lower daily doses for longer periods of time could result in a better toler-ability, JM216 was given once daily for 14 consecutive days every four to five weeks to adult patients with solid tumors. Oral antiemetics were given prophylactically only at the highest doses. The pharmacokinetics of total and ultrafiltrable platinum were studied on days 1 and 14 of the first cycle by Inductively Coupled-Mass-Spectrometry (ICP-MS). Results: Forty-six patients were treated at doses ranging from 10 mg/m2/d to 50 mg/m2/d and 39 were evaluable for hematologic toxicity over 74 cycles. MTDs were reached at 45 mg/m2/d and 50 mg/m2/d × 14 repeated every five weeks in patients with extensive, or limited/no prior treatment, respectively. The dose-limiting toxicity was neutropenia which was delayed and variable among patients. Other non-hematological toxicities were severe vomiting (22% of cycles), diarrhea (28% of cycles) and drug-associated fever (32% of patients), controlled with paracetamol. Subjective improvement with disappearance of tumour-related pain was observed in one patient with chemotherapy-resistant metastatic prostate cancer and in one previously untreated patient with malignant mesothelioma. Cmax and AUC values of both total and ultrafiltrable platinum on days 1 and 14 were highly variable among patients. Only Cmax on day 1 was linearly related to the dose. Total and ultrafiltrable platinum were still detectable two weeks after the last dose. No relationship could be established between AUC values and toxicities. Conclusions: Daily doses of JM216 of 40 mg/m2 and 45 mg/m2 for 14 consecutive days every five weeks with oral antiemetic prophylaxis are selected for phase II evaluation of single agent in patients with extensive or limited/no prior treatment, respectively. The administration of JM216 on a day × 14 schedule produced nausea and vomiting comparable to that observed with the day × 5 regimen but of longer duration. The variability of pharmacokinetics and pharmacodynamics, even though limited at the doses proposed for phase II evaluation of JM216 as single agent, recommend a careful monitoring of the patient

The new platinum-based anticancer agent LA-12 induces retinol binding protein 4 in vivo

<p>Abstract</p> <p>Background</p> <p>The initial pharmacokinetic study of a new anticancer agent (<it>OC</it>-6-43)-bis(acetato)(1-adamantylamine)amminedichloroplatinum (IV) (LA-12) was complemented by proteomic screening of rat plasma. The objective of the study was to identify new LA-12 target proteins that serve as markers of LA-12 treatment, response and therapy monitoring.</p> <p>Methods</p> <p>Proteomic profiles were measured by surface-enhanced laser desorption-ionization time-of-flight mass spectrometry (SELDI-TOF MS) in 72 samples of rat plasma randomized according to LA-12 dose and time from administration. Correlation of 92 peak clusters with platinum concentration was evaluated using Spearman correlation analysis.</p> <p>Results</p> <p>We identified Retinol-binding protein 4 (RBP4) whose level correlated with LA-12 level in treated rats. Similar results were observed in randomly selected patients involved in Phase I clinical trials.</p> <p>Conclusions</p> <p>RBP4 induction is in agreement with known RBP4 regulation by amantadine and cisplatin. Since retinol metabolism is disrupted in many cancers and inversely associates with malignancy, these data identify a potential novel mechanism for the action of LA-12 and other similar anti-cancer drugs.</p

Biochemical investigations into problems relating to epilepsy

Investigations have been carried out in three separate areas of research related to epilepsy.I. In the first of these investigations an attempt was made to clarify a possible role of folic acid derivatives in epilepsy. This investigation took the form of two self- contained studies involving dogs.A. The first study concerned the effects of anticonvulsant treatment on (a) folate activity in cerebrospinal fluid (c.s.f.). (b) the concentrations of 5- hydroxyindol- 3- ylacetic acid (5 -HIAA) and hornovanillic acid (HVA) in c.s.f.Routine sampling of ventricular and cisternal c.s.f. in the dog was achieved by the implantation of permanent guide tubes to the lateral ventricle and the cisterna magna. 5 -HIAA and HVA in c.s.f. samples were estimated by fluorescence assay techniques. Folate activity in c.s.f. and plasma samples was estimated microbiologically with a folatedependent strain of 1. casei.In control studies the c.s.f. folate activity was found to be between 2 and 7 times higher than the plasma folate activity. A positive correlation was found between c.s.f. and plasma folate activities. HVA and 5 -HIAA studies confirmed the concentration gradient which exists for these two acids between the lateral ventricular c.s.f. and the cisternal c.s.f.Selected anticonvulsant drugs (diphenylhydantoin, 7.5 mg/kg; phenobarbitone, 15 mg/kg; sulthiame 15 mg/kg; carbamazepine 15 mg /kg) were administered daily to the dogs for a period of five weeks. During this Period no change was seen in the folate activity of either c.s.f. or plasma. The anticonvulsants were also without effect on the concentrations of HVA and 5 -HIAA in c.s.f.These findings are discussed in relation to the folate deficiency states produced in man by chronic anticonvulsant therapy.B. The second study in the folate investigations was concerned with the effect of oral folic acid administration (a) folate activity in plasma, plasma ultrafiltrate and c.s.f. (b) the concentrations of HVA and 5 -HIAA in the c.s.f.During the control period of this study no correlation was found between c.s.f. and plasma folate activity, such as was found in the first study. Possible reasons to account for this discrepancy are discussed. Estimation of folate activity in plasma and plasma ultrafiltrate confirmed that much of the folate activity in dog plasma is protein- bound.Folic acid (31 mg/kg) was administered daily to dogs over a 5 -week period. During this treatment period the mean plasma folate activity was 10 times higher than normal; plasma ultrafiltrate folate activity was 5 times higher the normal; but c.s.f. folate activity was unchanged. These findings were interpreted as evidence for an increased plasma level of a folate derivative, probably folic acid itself, which was more strongly bound to protein than normal plasma folate derivatives, and was unable to enter the c.s.f. In two experiments in the rabbit no evidence was found for the active transport of methyl -tetrahydrofolate (normally the predominant form of folate in the plasma) into the c.s.f. HVA and 5 -HIAA concentrations in the c.s.f. were unaltered during the period of folic acid treatment. It was concluded that oral folic acid administration is unlikely to have any significant effect on normal cerebral function.The implications of this study are discussed in relation to (a) the role of folic acid derivatives in epilepsy and mental illness. (b) the mechanisms responsible for the normal distribution of folate activity between c.s.f. and plasma.II. The second investigation concerned the effects of barbiturate anaesthetics and anticonvulsant drugs on the c.s.f. potassium fluxes of the conscious dog.A new technique was developed for "open" perfusion of the cerebroventricular system of the conscious dog. The dog was perfused from lateral ventricle to cisterna magna with artificial r c.s.f. containing inulin, and tracer amounts of 42K. K, total potassium and inulin assays were performed on the inflow and out - flow fluids. From this data it was possible to calculate, for each sample of outflow fluid collected, values for both the potassium efflux from, and the potassium influx into, the c.s.f. After a period of between 65 -100 minutes of perfusion a "steady - state" was reached in which the potassium fluxes, as measured by this technique, were relatively constant. Drugs actions were studied by administering the drug during the "steady- state" period and ascertaining the effect upon the "steady- state" potassium fluxes.It was shown that - (1) The barbiturate anaesthetics, sodium pentobarbitone and o sodium thipentone, in doses sufficient to induce light anaesthesia, may depress both potassium influx into, and potassium efflux from c.s.f. Both fluxes were affected equally on any one occasion. Flux alterations of up to 50% were observed. (2) Diazepam has a consistent depressant effect on the potassium fluxes of the c.s.f. This effect was less marked, but more consistently observed, than in the case of the barbiturate anaesthetics. - v - (3) Diphenylhydantoin has no significant effect on potassium efflux from the c.s.f. but may have a slight depressant effect on potassium influx into the c.s.f. (4) Paraldehyde in a dose sufficient to induce light anaesthesia slightly increases the c.s.f. potassium fluxes. These results are discussed in relation to (a) previously published studies on c.s.f. potassium fluxes in anaesthetised animals (b) possible mechanisms of action of these drugs.The effects of the barbiturate anaesthetics and diazepam were interpreted as being secondary to a decrease in potassium exchange between brain intracellular and entracellular compartments.It was concluded that the anaesthetic or anticonvulsant action of a drug is not related to the drug's effect on c.s.f. potassium fluxes.III. The third investigation concerned the development and preliminary application of a method for the analysis of GABA and associated amino acids in small areas of tissue from the primary and secondary epileptic foci of rats with a cobalt- induced epileptogenic lesion.The existing specific enzymic methods for GABA analysis were examined and found to be either too insensitive or too complex to act as suitable micro- methods. The standard techniques for amino acid analysis, involving column separation and colorimetric estimation were also considered to be too insensitive.Reaction of the amino group of amino acids with 1- dimethyl- amnonapthalene-5- sulphonyl chloride (dansyl chloride) produces stable, highly- fluorescent derivatives which can be readily separated by thin -layer chromatography.A highly sensitive isotope dilution assay, based on the preparation of dansyl derivatives, was evolved for the estimation of free amino acids in brain tissue.The tissue was homogenised in perchloric acid and known amounts of ¹⁴C -amino acid standards were added to an aliquot of the perchlorate extract to act as internal standards for recovery of amino acid through the method. The extract was then taken to pH 9.3 - 9.8 with potassium carbonate solution, precipitating perchlorate as its insoluble potassium salt. An aliquot of the alkaline extract was dansylated with an equal volume of H³-dansyl chloride in acetone. After a 30 minute reaction period the dansylation mixture was taken to dryness and extracted with acetone: glacial acetic acid solution (3:2). An aliquot of this extract was applied to a polyamide micro- chromatography plate which was then developed in two dimensions. Under u.v. light specific dansyl -amino acid spots were identified by their characteristic position on the developed plate. These spots were cut from the plate and counted for ³H and ¹⁴C activity in a liquid scintillation counter.The total amount of dansyl-amino acid in a spot was calculated from its ³H activity. Combining this figure with the ¹⁴C activity of the spot allowed calculation of the specific activity (w.r.t. ¹⁴C) of the dansyl-amino acid in the spot. Comparison of this specific activity with the specific activity of the ¹⁴C -amino acid standard which had been added as a recovery standard gave a measure of the dilution of exogenous radioactive amino acid by endogenous non-radioactive amino acid. From this dilution factor it was possible to calculate the concentration of endogenous amino acid in the original perchlorate extract of brain tissue. Determination of the weight of protein precipitated from the tissue sample by the perchloric acid extraction allowed calculation of the amino acid content of tissue in terms of }moles amino acid per 100 mg protein.The two dimensional chromatography did not achieve a separation of dansyl glutamine and dansyl -threonine; as a result glutamine and threonine were estimated as the sum total of their two concentrations.The method was applied to the estimation of control values for GABA, glutamate, glutamine/threonine, glycine, aspartate and hydroxyproline levels in rat cortex. The values obtained for GABA, glutamate, glutamine /threonine and glycine were highly reproducible and in good agreement with previously published values. Aspartate was not satisfactorily estimated. Hyroxyproline was not detected in rat cortex.The dansylation method was applied to the analysis of brain tissue from three rats with 11 day-old cobalt-induced epileptogenic lesions in the frontal cortex. There was evidence that GABA and glutamate levels were lowered, and glutamine/threonine and glycine levels raised, in the region of the secondary epileptogenic ( "mirror ") focus. This was the site from which epileptiform spike discharges were most frequent.The significance of these findings have been discussed along with general comments on the problems of amino acid studies in brain. It was concluded that disorders in amino acid metabolism may be involved in epileptic processes

Cremophor EL causes (pseudo-) non-linear pharmacokinetics of paclitaxel in patients

The non-linear plasma pharmacokinetics of paclitaxel in patients has been well established, however, the exact underlying mechanism remains to be elucidated. We have previously shown that the non-linear plasma pharmacokinetics of paclitaxel in mice results from Cremophor EL. To investigate whether Cremophor EL also plays a role in the non-linear pharmacokinetics of paclitaxel in patients, we have established its pharmacokinetics in patients receiving paclitaxel by 3-, 24- or 96-h intravenous infusion. The pharmacokinetics of Cremophor EL itself was non-linear as the clearance (Cl) in the 3-h schedules was significantly lower than when using the longer 24- or 96-h infusions (Cl175–3 h = 42.8 ± 24.9 ml h−1 m−2; Cl175–24 h = 79.7 ± 24.3; P = 0.035 and Cl135–3 h = 44.1 ± 21.8 ml h−1 m−1; Cl140–96 h = 211.8 ± 32.0; P < 0.001). Consequently, the maximum plasma levels were much higher (0.62%) in the 3-h infusions than when using longer infusion durations. By using an in vitro equilibrium assay and determination in plasma ultrafiltrate we have established that the fraction of unbound paclitaxel in plasma is inversely related with the Cremophor EL level. Despite its relatively low molecular weight, no Cremophor EL was found in the ultrafiltrate fraction. Our results strongly suggest that entrapment of paclitaxel in plasma by Cremophor EL, probably by inclusion in micelles, is the cause of the apparent nonlinear plasma pharmacokinetics of paclitaxel. This mechanism of a (pseudo-)non-linearity contrasts previous postulations about saturable distribution and elimination kinetics and means that we must re-evaluate previous assumptions on pharmacokinetics–pharmacodynamics relationships. © 1999 Cancer Research Campaig

Adaptive dosing of anticancer drugs in neonates: facilitating evidence-based dosing regimens

PURPOSE: Selection of the most appropriate chemotherapy dosing regimens for neonates treated within the first weeks of life represents a significant clinical dilemma. Due to a lack of information relating to the clinical pharmacology of anticancer drugs in these challenging patients, current dosing guidelines are based on limited scientific rationale. In the current study, we investigate the utilisation of therapeutic drug monitoring approaches in neonates with localised hepatoblastoma, Wilms' tumour and stage 4S neuroblastoma, being treated with widely used anticancer drugs. METHODS: Plasma concentrations of cisplatin, vincristine, etoposide and carboplatin were quantified in two neonates being treated within the first 3 weeks of life and in a 32-week preterm infant treated at a gestational age of 40 weeks. Therapeutic drug monitoring was carried out where appropriate, based on the pharmacokinetic data obtained in conjunction with clinical response and toxicity. RESULTS: Treatment of a child aged 2 weeks with a recommended cisplatin dose reduction for weight to 1.8 mg/kg resulted in achievement of unbound cisplatin plasma concentrations of 0.01-0.08 µg/mL, markedly lower than exposures previously reported in infants and older children. A dose increase to 2.7 mg/kg was implemented, leading to the achievement of levels more in-line with those previously reported. This increased dose level was well tolerated over six courses of treatment, resulting in a good response to cisplatin monotherapy and the patient remains in remission at 3.5 years. In contrast, a 50 % vincristine dose reduction for weight in a 3-week-old neonate resulted in plasma concentrations comparable to levels observed in older children, leading to successful treatment and continued remission at 2 years. In a third patient, etoposide and carboplatin clearance values normalised to body weight were comparable to those reported in older children, resulting in comparatively lower exposures following reduced dosing. CONCLUSIONS: The current report provides unique data on the pharmacokinetics of several widely used anticancer drugs in neonates treated within the first few weeks of life. The provision of these data acts as a useful reference point to support future dosing decisions to be made by clinicians in the treatment of these challenging patients

Pericardium: structure and function in health and disease

Normal pericardium consists of an outer sac called fibrous pericardium and an inner one called serous pericardium. The two layers of serous pericardium: visceral and parietal are separated by the pericardial cavity, which contains 20 to 60 mL of the plasma ultrafiltrate. The pericardium acts as mechanical protection for the heart and big vessels, and a lubrication to reduce friction between the heart and the surrounding structures. A very important role in all aspects of pericardial functions is played by mesothelial cells. The mesothelial cells form a monolayer lining the serosal cavity and play an important role in antigen presentation, inflammation and tissue repair, coagulation and fibrinolysis. The two major types of mesothelial cells, flat or cuboid, differ substantially in their ultrastructure and, probably, functions. The latter display abundant microvilli, RER, Golgi dense bodies, membrane-bound vesicles and intracellular vacuoles containing electron-dense material described as dense bodies. The normal structure and functions of the pericardium determine correct healing after its injury as a result of surgery or microbial infection. The unfavorable resolution of acute or chronic pericarditis leads to the formation of adhesions between pericardial leaflets which may lead to serious complications