Antithrombin III deficiency as a risk factor for catheter-related central vein thrombosis in cancer patients

The fibrin sleeve of venous catheters (VC) and parietal thrombi represent frequent and dangerous side-effects of central venous catheterization (CVC), due to the risk of embolism. Reduced levels of coagulation clotting factors inhibitors (such as Antithrombin III) are known to be associated with increased thrombogenic risk. The aim of this study was to evaluate the role of Antithrombin III (AT III) deficiency as a risk factor for thrombosis in cancer patients undergoing CVC. The study groups included patients with a reduced AT III activity (< 70%, 20 consecutive patients) and with normal AT III values (> 70%, 20 randomly selected patients), requiring a VC for chemotherapy and/or total parenteral nutrition. The study protocol included evaluation of Hb, PLTs, PT (INR), aPTT, Fibrinogen and AT III at days 0, 1, 3 and 8 after CVC and upon VC removal. Peripheral and pullout phlebographies were performed in all patients on catheter withdrawal. A quantitative scale was developed to evaluate both VC and parietal thrombus degree in each catheter-containing venous segment (subclavian, innominate, superior vena cava); the sum of the mean values was defined as overall thrombus. The average VC dwelling time was similar in both groups. There were no significant differences in Hb, PLTs, PT (INR), aPTT, Fibrinogen and in the remaining parameters of the study between the two groups. The group with AT III deficiency presented a higher degree of both parietal (p < 0.05) and overall thrombus (p < 0.02). Data showed a higher severity of CVC-related thrombosis in patients with AT III deficiency than in the control group. Further studies are needed to evaluate whether the therapeutically-induced normalization of AT III levels can reduce the thrombosis degree.

Tumor cells in blood shed from the surgical field

OBJECTIVES

To analyze blood shed from the surgical field during oncologic surgery for tumor cells and to assess functional characteristics of these cells.

DESIGN AND PATIENTS

Series of 61 patients with cancer who underwent surgery for an abdominal, orthopedic, urological, gynecological, or head and neck malignant tumor, and blinded comparison with 15 patients with benign diseases undergoing surgery.

SETTING

A 500-bed tumor center and a tertiary care hospital.

MAIN OUTCOME MEASURES

Tumor cells were isolated from intraoperatively salvaged and washed blood by density gradient centrifugation. They were identified in cytospin specimens by their content of cytokeratins and nucleolar organizer regions with a sensitivity of 10 cells in 500 mL of blood. Clonogenicity was tested in a cell colony assay; invasiveness, in Boyden chambers; and tumorigenicity, in nude mice.

RESULTS

In 57 of 61 patients, tumor cells were detected in the blood shed during oncologic surgery. They demonstrated proliferation capacity, invasiveness, and tumorigenicity. The total number of tumor cells identified ranged from 1 x 10(1) to 7 x 10(6), with no close correlation to the amount of blood loss. Circulating tumor cells were demonstrated in only 26% of these patients and in small numbers.

CONCLUSIONS

Malignant cells identified regularly in the blood shed during tumor surgery and different from circulating tumor cells are of concern, since at the surgical site they may cause local tumor recurrence, or in the salvaged blood they may cause hematogenic metastasis after retransfusion. Therefore, the contraindication of intraoperative autotransfusion in tumor surgery is strongly supported, and a review of surgical procedures and adjuvant therapy may be indicated, as the passage of the identified cells to the shed blood is yet unknown.

Functional and phenotypic characterization of human peripheral blood stem cell harvests: a comparative analysis of cells from consecutive collections

A considerable number of patients with malignancies who are treated with high-dose therapy and hematopoietic stem cell transplantation subsequently relapse. Analyses of peripheral blood stem cell (PBSC) harvests obtained from 49 cancer patients showed that the PBSC harvest contained precursors for antitumor effector cells. Ex vivo manipulation of these harvests to maximize the antitumor effector cell activity may provide a new therapeutic approach to decrease or eliminate any minimal residual disease that remains after high-dose therapy. Characterization of PBSC from consecutive collections determined the collections best suited for ex vivo augmentation of antitumor cytotoxic effector cells. We report the results of a functional and phenotypical characterization of PBSC obtained from six consecutive collections from 18 cancer patients receiving granulocyte-macrophage colony-stimulating factor (GM-CSF) for hematopoietic stem/progenitor cell mobilization. The PBSC were evaluated for their cytotoxicity using the 51Cr-release assay. The frequency and subsets of lymphocytes were determined using flow cytometry with appropriate specific marker antibodies and differential cell counts. The content of hematopoietic progenitor cells in each collection was determined using a colony-forming unit granulocyte-macrophage (CFU-GM) culture assay. The frequency of cytotoxic effector cells including lymphokine-activated killer (LAK) cell precursors and lymphocytes was significantly greater (P < .05) in the early collections, whereas the later collections contained significantly (P < .05) more CFU-GM progenitor cells and fewer cytotoxic effector cells. Thus, our results show that PBSC obtained from advanced cancer patients do contain considerable levels of precursor cells for the generation of LAK cell populations. These results suggest that cells from the earlier collections are best suited for ex vivo manipulation to augment the antitumor effects.

Tumour markers

Tumour markers are now used in the diagnosis, anatomical localization, staging, monitoring and definition of prognosis of a wide range of malignancies. The last decade has seen an expansion of our definition of these markers to include oncogenes and oncogene products, and provided us with new possibilities of developing more specific tests to help in the management of cancer.

Morphine-6-glucuronide concentrations and opioid-related side effects: a survey in cancer patients

The active morphine metabolite, morphine-6-glucuronide (M-6-G), may contribute to both the analgesia and the adverse effects observed during morphine (MOR) therapy. To evaluate the relationship between M-6-G and adverse effects, we measured steady-state plasma concentrations of MOR and M-6-G and concurrently noted the presence or absence of moderate to severe cognitive impairment or myoclonus in 109 cancer patients who were receiving either oral (n = 71) or parenteral (n = 38) morphine. MOR and M-6-G plasma concentrations were determined by HPLC with electrochemical detection. The presence of cognitive impairment or myoclonus was analyzed in relation to molar M-6-G/MOR ratio, age, morphine dose, the use of other centrally acting drugs, renal function (blood urea nitrogen (BUN) and serum creatinine), hepatic function (serum bilirubin, serum glutamic oxalacetic transaminase (SGOT), and alkaline phosphotase) and serum lactate dehydrogenase (LDH). The patient population consisted of 60 women and 49 men. The mean age was 51.5 years (range: 10-85 years). The mean morphine dose (total dose-prior 48 h) was 486 mg (range: 40-4800 mg) for the oral group and 931 mg (range: (10-9062 mg) for the parenteral group. The mean molar M-6-G/MOR ratios were 6.1 (SD: 18.2; range: 0.01-153.3) for the oral treatment group and 2.7 (SD: 4.16; range: 0.05-23.8) for the parenteral treatment group. Overall, the M-6-G/MOR ratio demonstrated a moderate but significant correlation with BUN (r = 0.4; P < 0.001) and creatinine (r = 0.45; P < 0.001) levels, but not with the other clinical variables examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of cancer-related thrombocytopenia by low-dose subcutaneous interleukin-2 plus the pineal hormone melatonin: a biological phase II study

Despite the platelet production in response to IL-2, cancer immunotherapy with IL-2 tends to induce thrombocytopenia, which probably depends on an enhanced peripheral destruction. On the basis of our previous studies, this effect may be neutralized by a concomitant administration of the pineal hormone melatonin (MLT). This study was performed to investigate the influence of an immunotherapeutic combination with low-dose IL-2 and MLT on platelet number in advanced cancer patients showing persistent thrombocytopenia. The study included 14 advanced solid tumor patients, affected by thrombocytopenia due to different causes (portal hypertension: 9; previous chemotherapies: 3; DIC: 2). IL-2 was injected at 3 million IU/day subcutaneously for 6 days/week for 4 weeks, in association with MLT (40 mg/day orally). A normalization of platelet number occurred in 10/14 (71%) patients, and platelet mean number significantly increased on treatment. No important therapy-related toxicity was observed. This preliminary study would suggest that the concomitant administration of MLT is able not only to neutralize IL-2-induced thrombocytopenia, but also to increase platelet number in thrombocytopenic cancer patients.

Blood-derived autografts collected during granulocyte colony-stimulating factor-enhanced recovery are enriched with early Thy-1+ hematopoietic progenitor cells

It was the objective of the study to characterize CD34+ hematopoietic progenitor cells from peripheral blood (PB) and bone marrow (BM) in a group of 24 cancer patients. After cytotoxic chemotherapy, R-metHu granulocyte colony-stimulating factor (R-metHuG-CSF; filgrastim, 300 micrograms daily, subcutaneously) was given to shorten the time of neutropenia as well as to increase the rebound of peripheral blood progenitor cells (PBPC) for harvesting. The proportion of CD34+ cells in the leukapheresis products (LPs) was 1.4-fold greater than in BM samples that were obtained at the same day (LP: median, 1.4% v BM: median, 1.0%, P < .01). Two- and three-color immunofluorescence showed that blood-derived CD34+ cells comprised a greater proportion of a particular early progenitor cell than CD34+ cells of bone marrow. Blood-derived progenitor cells tended to have a higher mean fluorescence intensity of CD34 and expressed significantly lower levels of HLA-DR (mean fluorescence intensity of HLA-DR: 442.6 +/- 44.9 [LP] v 661.5 +/- 64.6 [BM], mean +/- SEM, P < .01). Furthermore, the blood-derived CD34+ cells comprised a 1.7-fold greater proportion of Thy-1+ cells (LP: median, 24.4% v BM: median, 14.4%, P < .001) and expressed significantly less c-kit (LP: median, 20.5% v BM: median, 31.0%, P < .01). Three-color analysis showed that high levels of Thy-1 expression were restricted to CD34+/HLA-DRdim or CD34+/HLA-DR- cells confirming the early developmental stage of this progenitor cell subset. The proportion of CD34+/CD45RA(bright) cells representing late colony-forming unit granulocyte-macrophage (CFU-GM) was smaller in LPs compared with BM (P < .05). For an examination of BM CD34+ cells before the mobilization chemotherapy, samples of 16 patients were available. The mean proportion of c-kit expressing CD34+ cells in the bone marrow during G-CSF-stimulated reconstitution decreased 1.8-fold compared with baseline values. There was no difference in the proportion of BM-derived CD34+/Thy-1+ cells and CD34+/CD45RA+ cells between steady-state hematopoiesis and G-CSF-supported recovery. Our data suggest that during G-CSF-enhanced recovery, CD34+ cells in the PB are enriched with more primitive progenitor cells to evenly replenish the BM after the chemotherapy-related cytotoxic damage.

Time-dependent photodynamic damage to blood vessels: correlation with serum photosensitizer levels

We have used the technique of dynamic capillaroscopy to study the time-course of photodynamic vascular occlusion in mice injected intraperitoneally with either of two photosensitizers; hematoporphyrin esters (HPE) or meso-tetrahydroxyphenyl chlorin (mTHPC). The peak of vascular occlusion induced by HPE coincided in time with peak serum levels of this photosensitizer (about 3 h after injection). However, there was also a second peak of occlusive activity at about 12 h after injection, at which time serum HPE was falling monotonically. In the case of mTHPC, no peak of occlusive activity was seen at 3 h after injection, even though the serum levels of this photosensitizer, like those of HPE, were highest around this time. Instead, a steady rise in photosensitizing activity was observed, peaking at 11 h. This decoupling between serum drug levels and vascular photosensitization--partial for HPE and complete for mTHPC-suggests that direct photosensitization of endothelial cells is unlikely wholly to explain the vascular collapse. Instead, there must be either another compartment that accumulates photosensitizer more slowly and in which photodynamic activity has an indirect effect on the blood capillaries or a slow metabolic transformation of mTHPC into a more active sensitizer.

Cellular fibronectin in serum and plasma: a potential new tumour marker?

The concentration of cellular fibronectin (cFN) containing the extra domain A (EDA) was measured in 479 plasma and 300 serum samples from healthy blood donors by a competitive enzyme immunoassay (EIA). Serum and plasma samples contained low concentrations of EDAcFN. The mean concentration of EDAcFN was higher in plasma (2.46 mg l-1) than in serum (0.30 mg l-1). No significant differences between sexes or age groups were found. The EDAcFN concentrations were also measured in 120 patients with various malignancies. The mean values in serum were 4.28 mg l-1, 2.01 mg l-1 and 5.18 mg l-1 in patients with digestive tract malignancies, breast cancer and a group of miscellaneous cancers respectively. In plasma, the corresponding values were 12.26 mg l-1, 4.38 mg l-1 and 11.12 mg l-1 respectively. The serum EDAcFN concentration was higher than the 97.5th percentile level of healthy blood donors in 86% of patients with digestive tract and in 76% with miscellaneous malignancies. In patients with breast cancer 60% had elevated levels of EDAcFN. The corresponding figures for plasma samples in patients with digestive tract and miscellaneous malignancies were 79% and 71% respectively. In patients with breast cancer only 30% had elevated plasma levels of EDAcFN. The mean values in serum and plasma of 20 patients with benign diseases were below the cut-off levels. Consistent with the EIA results, Western blotting revealed increased amounts of EDAcFN in blood samples from cancer patients. Pregnancy did not affect the EDAcFN concentration. The mean values in 20 pregnant women were below the cut-off levels.

Current sample handling methods for measurement of platinum-DNA adducts in leucocytes in man lead to discrepant results in DNA adduct levels and DNA repair

DNA adduct levels were measured with atomic spectroscopy in white blood cells (WBCs) from patients with solid tumours who were treated with six weekly courses of cisplatin. In 21 patients (I) the WBCs were collected after thawing frozen whole-blood samples according to a previously described method. In 32 other patients (II) WBCs were collected immediately after blood sample collection. The two methods for WBC collection were also compared in vitro. The maximal DNA adduct levels in vivo after the first course were in I 2.48 +/- 1.14 and in II 1.28 +/- 0.40 pg of platinum per microgram of DNA (P < 0.0001). The DNA 'repair' in the first course (DNA adduct level at the end of the infusion minus the level 15 h post infusion) was in I 40% +/- 29% and in II 18% +/- 29% (P = 0.009). These differences were consistent in all measured courses. In vitro, the DNA adduct levels in the freshly prepared WBCs were significantly lower at 0, 1 and 4, but not 24 h, after start of the incubation with cisplatin than in the WBCs collected after freezing and thawing the blood sample. The same experiment with carboplatin in vitro also resulted in significantly lower adducts in freshly isolated WBCs. The higher DNA adduct levels and DNA 'repair' in I are caused by remaining unbound cisplatin in the sample tubes, which can form DNA adducts ex vivo. The same results in vivo can be anticipated when carboplatin is used.

Vitamin B6 and cancer: adenosine-N6-diethylthioether N1-pyridoximine 5'-PO4, a circulating human tumor marker

Studies in my laboratory on the metabolism and utilization of labeled vitamin B6 by tumor-bearing animals and tumor cells in culture have shown the production and presence in the circulation of a novel pyridoxal 5'-phosphate conjugate metabolite (1-5). Using specific radiolabeling and analytical tests, its structure was tentatively identified (now confirmed) as adenosine-N6-diethylthioether-N1-pyridoximine 5'-phosphate (4-6). The novel vitamin conjugate was isolated from the plasma of patients and control subjects following extraction with perchloric acid and separation by pair-ion HPLC. This communication reports the chromatographic separation of the novel compound and its plasma levels in control subjects, cancer patients and patients with other ailments. The results show that the novel metabolite is a circulating human tumor marker with levels of up to 4x or greater seen in cancer patients compared to controls and to subjects with other ailments. The results indicate strongly that the novel circulating vitamin B6 conjugate compound can be successfully used for the detection of different malignancies in humans by evaluating its level in circulation.

Characterization of plasma lipids in patients with malignant disease by 13C nuclear magnetic resonance spectroscopy and gas liquid chromatography

The purpose of this study was to characterize possible changes in fatty acid composition of plasma lipids associated with malignancy. The very low, low, and high-density lipoproteins were isolated by gradient density ultracentrifugation of plasma from 16 patients with malignant disease and from 15 controls. The triglyceride, esterified cholesterol, and phospholipid constituents of each lipoprotein fraction were isolated, and the fatty acid composition within each lipid component was determined by gas liquid chromatography (GLC). In the 10- to 45-parts-per-million (ppm) region of the carbon-13 (13C) nuclear magnetic resonance (NMR) plasma spectrum, differences were found between patients with malignant disease and controls. The ratio of the 31.6/32.1 ppm resonance intensities was lower in the group of cancer patients. The ratio of the 24.4/24.9 ppm resonance intensities in patients with malignant disease was different from the nonpregnant controls. The NMR changes were interpreted in light of GLC data that indicated derangements in the composition of fatty acids within lipoprotein lipids. In total plasma esterified cholesterol, the relative amount of linoleic acid (18:2, n-6) was lower, whereas oleic acid (18:1, n-9) was higher in the group of patients with malignant disease. In total plasma triglycerides, the amount of oleic acid was higher in the cancer patient group. For total plasma phospholipids, no differences in fatty acid composition between patients and controls were found. Throughout the lipoprotein fractions, the same differences in oleic acid and linoleic acid distribution for triglyceride and esterified cholesterol were found when comparing cancer and control subjects. In conclusion, we found that there are certain differences in the 13C NMR spectra and fatty acid profiles between a small and heterogeneous group of cancer patients after they have received their initial treatment and a group of healthy controls. We suggest that carbon NMR spectroscopy could be useful in characterizing malignancy-associated lipid changes.

A phase I and pharmacokinetic study of a new camptothecin derivative, 9-aminocamptothecin

Camptothecins are the only available antitumor agents which target the nuclear enzyme topoisomerase I. 9-Aminocamptothecin (9-AC) is a water-insoluble derivative of camptothecin which has demonstrated impressive antitumor activity in preclinical models. While two other water-soluble derivatives, CPT-11 and topotecan, have successfully completed Phase I and Phase II testing, biochemical and tissue culture studies suggest that camptothecin analogues differ in characteristics which may be important in determining antitumor activity. We performed a Phase I trial of 9-AC to determine the pharmacokinetics, dose-limiting toxicity, and maximum tolerated dose of this agent when administered as a 72-h continuous i.v. infusion. Thirty-one patients with resistant solid cancers received 5-60 microgram/m2/h 9-AC for 72 h, repeated at 3-week intervals. The drug was administered in a vehicle containing dimethylacetamide, polyethylene glycol, and phosphoric acid. Blood samples were collected and the lactone (closed ring) form of 9-AC was quantitated. The maximum tolerated dose of 9-AC was determined to be 45 microgram/m2/h. Dose-limiting toxicity consisted of neutropenia. Thrombocytopenia was also prominent. There were no significant nonhematological toxicities. Minimal responses were seen in patients with gastric, colon, and non-small cell lung cancer. Although significant interpatient variation in plasma 9-AC lactone levels was observed, pooled data were fit to a two-compartment model, with a terminal half-life of 36 h. Analyses of topoisomerase protein levels in peripheral blood cells indicated decreases in topoisomerase I accompanied by increases in topoisomerase II in two of three patients. 9-AC is an active antitumor agent and may be administered safely as a 72-h infusion in patients with cancer. Although Phase II trials with a 72-h infusion of 9-AC are warranted, alternate schedules should be evaluated given the dramatic preclinical activity seen with more prolonged administrations.

G-CSF after autologous bone marrow transplantation for malignant diseases in children. Spanish Working Party for Bone Marrow Transplantation in Children

The use of recombinant human granulocyte-stimulating factor (G-CSF) has been shown to effectively accelerate granulocytic recovery after autologous bone marrow transplantation (BMT) in adults. The experience, however, is limited in children. We evaluated the hematopoietic reconstitution in 41 consecutive children undergoing autologous BMT for hematologic malignancies (21 acute lymphoblastic leukemia, five non-Hodgkin's lymphoma) and solid tumours (seven neuroblastoma, two brain tumor, three Ewing's sarcoma, two Wilms' tumor, one rhabdomyosarcoma). Their ages ranged from 2 to 16 years (mean 7.2 years). rhG-CSF was given at a dose of 10 micrograms/kg/day i.v. in a 2h infusion from day +1 until +28 or until the absolute neutrophil count (ANC) was > 1 x 10(9)/L. These patients were compared with a similar historical control group of 38 children who did not receive rhG-CSF after autologous BMT. The number of cells infused was similar in both groups. At the dose and schedule used in the present study, rhG-CSF was well tolerated and no side-effects were observed. The number of cell infused was similar in both groups. At the dose and schedule used in the present study, rhG-CSF was well tolerated and no side-effects were observed. Our data show that rhG-CSF accelerates engraftment and reduces the number of febrile days and antibiotic use. Furthermore, patients who were treated had less infections.

Contribution of parathyroid hormone-related peptide to the evaluation of hypercalcemia

Hypercalcemia of malignancy is due either to local osteolysis at the site of bone metastases or to production by the malignancy of parathyroid hormone-related peptide, which shares some of the effects of parathyroid hormone. We used a radioimmunoassay (antiserum specific to the amino-terminus) to measure serum parathyroid hormone-related peptide levels in controls (n = 61), chronic renal failure patients (n = 10), patients with primary hyperparathyroidism (n = 19), cancer patients with (n = 35) or without (n = 57) hypercalcemia and/or bone metastases (n = 53 and n = 39, respectively), and patients with hematologic malignancies (n = 15). We set the upper limit of normal of the parathyroid hormone-related peptide assay at 2.7 pmol/L. The peptide was undetectable in two-thirds of healthy controls. Renal failure did not interfere with the assay. Eighteen of the 19 patients with primary hyperparathyroidism had normal levels. In contrast, 82% of patients with humoral hypercalcemia of malignancy (i.e., without detectable bone metastases) had increased levels; in this subgroup there was a significant inverse correlation between serum levels of the peptide and phosphorus. Elevation of parathyroid hormone-related peptide levels was less common among hypercalcemic patients with metastatic bone disease (38%). Four of the seven hypercalcemic patients with hematologic malignancies had elevated parathyroid hormone-related peptide levels. In our overall study population, serum calcium levels were weakly but significantly correlated with parathyroid hormone-related peptide levels. In conclusion, elevated parathyroid hormone-related peptide in a patient with hypercalcemia suggests a malignant disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Short communication: normal tissue injury after cancer therapy is a local response exacerbated by an endocrine effect of TGF beta

The sensitivity of normal tissues rather than of the tumour usually limits the effectiveness of cancer treatment. The normal tissue side effects from chemotherapy and/or radiotherapy result from both direct cellular loss and the extensive fibrosis that develops at the site of injury. Recent evidence suggests that the cytokine, transforming growth factor beta (TGF beta), mediates this fibrogenic process. Herein, we provide evidence in support of the hypothesis that the fibrosis formation following therapy results not only from TGF beta produced locally in the injured normal tissue, but also from circulating TGF beta released by the tumour. Thus, therapy-induced normal tissue damage appears in part to be a local manifestation of a systemic condition.

Double-lumen inferior vena cava catheters for peripheral stem cell apheresis and transplantations

No previously published studies have described double-lumen hemodialysis/apheresis catheters for use with continuous-flow apheresis collection of peripheral stem cell (PSC). We prospectively evaluated experiences with these catheters during both PSC collection and transplantation. Because of previously-described successful experiences with single-lumen apheresis catheters placed in the inferior vena cava, all catheters evaluated in this study were placed in this anatomic location. Our experience demonstrated high rates of thrombotic occlusion (65%) and catheter-related infections (15%). This method of access should not be considered optimal in its present state of use. Further investigation into preferred catheter design, anatomic location, and thrombosis prophylaxis during continuous-flow apheresis is warranted.

Humoral hypercalcemia of malignancy: some enigmas on the clinical features

Humoral hypercalcemia of malignancy (HHM) is a common paraneoplastic syndrome mediated by tumor-derived parathyroid hormone-related peptide (PTHRP), which bears structural and functional similarities to PTH. Thus the clinical features of HHM are very similar to those of primary hyperparathyroidism (1 degree HPT), a prototype of humoral hypercalcemia caused by PTH. On the other hand, HHM syndrome differs from 1 degree HPT in several aspects, including serum 1,25(OH)2D levels, acid-base balance, and bone remodeling process, the reason of which remains largely unknown. We approached these questions using a unique animal model of HHM, nude rats implanted with PTHRP-overproducing human carcinomas. In this review we will summarize the results and discuss the implications in understanding the disease mechanism.

Comparison of 2- and 3-compartment models for the Bayesian estimation of methotrexate pharmacokinetics

Moderate and high-dose methotrexate was given by a 4-h infusion to 10 patients. The pharmacokinetics of methotrexate, determined by fluorescence polarization immuno-assay, was successively described by a 2- and a 3-compartment open model with elimination from the central compartment. Population pharmacokinetic parameters were obtained by non-linear regression from 8 data points for each course and were subsequently used to fit the same data by the Bayesian estimation method. According to Akaike's information criterion, the 3-compartment model was found statistically superior in 7 patients out of 10. Using this model clearance was well predicted (+/- 5%) by the Bayesian method with only 2 points taken at the end of the infusion and 24 h after. The prediction was less good for the steady-state volume of distribution (+/- 18%) and the half-lives (+/- 20-30%). This procedure enables a good estimation of individual pharmacokinetic parameters for methotrexate, specially with clearance, at minimal cost and minimal disturbance for the patient.

Growth factors, cytokines and soluble forms of receptor molecules in cancer patients

A wide range of growth factors has been identified in recent years, some of which have been found to play a crucial role in neoplastic processes. Some tumours produce considerable amounts of these peptides and their requirement for growth factors is often much reduced leading to a degree of autonomy which may itself contribute to tumourigenicity. In addition, growth factors such as TGF-alpha, PDGF, FGF and IGFs have been found to be overexpressed in tumours. The growth factor effector pathway is thus open to intervention, e.g. by blocking the receptor using specific antibodies or interfering with posttranscriptional activation. This is even more evident as oncogenes such as erbB and v-sis encode for growth factor receptors. Soluble receptors, due to high affinity binding, might also be used to sequester growth factors from its specific membrane-bound receptors. Tyrosine-specific protein kinase activity may be inhibited by tyrosine analogues such as erbstatin or by more specific tyrosine-kinase inhibitors. Some therapeutical concepts have already been developed in clinical trials. Tumour necrosis factor (TNF) has successfully been used in extremity melanoma and sarcoma and monoclonal antibodies directed against the EGF receptor has also been applied in patients with advanced squamous lung cancer. Synthetic growth factor analogues which bind to the receptor without eliciting a signal may soon become a supplementary part in cancer treatment. Growth factor action is also blocked by suramin and its analogues and clinical phase I and II trials are underway. These novel therapeutical aspects will profoundly change the nature of cancer treatment.

[Postoperative hypermyoglobinemia. Mechanism of occurrence. Predictive value]

The time course of free myoglobin content and the rate of lipid peroxidation were simultaneously studied in cancer patients. The initial concentrations of myoglobin, hydroperoxides and malonic dialdehyde (MDA) were found to be higher than the control values, thus suggesting the increased rate of lipid peroxidation in these patients, which was responsible for destruction of cell membranes. Within the first 24 hours after surgery, there was a drastic release of myoglobin, its levels being sometimes higher in case of a complicated postoperative period than those in its smooth course. The increase in content of MDA was less marked, by reaching its maximum on days 1-2. The postoperative levels of hydroperoxides was considerably decreased, yet it began gradually increasing on day 2. The rather high correlation coefficients between the content of myoglobin and MDA suggest that there is a relationship between hypermyoglobinemia and the state of cell membranes. However, surgical intervention, enhancing lipid peroxidation, concurrently activates the mechanisms aimed at maintaining cell homeostasis.