Analysis of the Prevalence and Causes of Ultrafiltration Failure during Long-Term Peritoneal Dialysis: A Cross-Sectional Study

Background

Ultrafiltration failure (UFF) is a major complication of peritoneal dialysis (PD). It can occur at any stage of PD, but develops in time and is, therefore, especially important in long-term treatment. To investigate its prevalence and to identify possible causes, we performed a multicenter study in The Netherlands, where patients treated with PD for more than 4 years were studied using a peritoneal function test (standard peritoneal permeability analysis) with 3.86% glucose. UFF was defined as net UF < 400 mL after a 4-hour dwell.

Results

55 patients unselected for the presence or absence of UFF were analyzed. Mean age was 48 years (range 18 – 74 years); duration of PD ranged from 48 to 144 months (median 61 months); UFF was present in 20 patients (36%). Patients with and without UFF did not differ in age or duration of PD. Median values for patients with normal UF compared to patients with UFF were, for net UF 659 mL versus 120 mL ( p < 0.01), transcapillary UF rate 3.8 versus 2.1 mL/minute ( p < 0.01), effective lymphatic absorption 1.0 versus 1.6 mL/min ( p < 0.05), mass transfer area coefficient (MTAC) for creatinine 9.0 versus 12.9 mL/min ( p < 0.01), dialysate-to-plasma ratio (D/P) for creatinine 0.71 versus 0.86 ( p < 0.01), glucose absorption 60% versus 73% ( p < 0.01), maximum dip in D/P sodium (as a measure of free water transport) 0.109 versus 0.032 ( p < 0.01), and osmotic conductance to glucose 3.0 versus 2.1 μL/min/mmHg ( p < 0.05). As causes for UFF, high MTAC creatinine, defined as > 12.5 mL/min, or a glucose absorption > 72%, both reflecting a large vascular surface, a lymphatic absorption rate (LAR) of > 2.14 mL/min, and a decreased dip in D/P sodium of < 0.046 were identified. Most patients had a combination of causes (12 patients), whereas there was only a decreased dip in D/P sodium in 3 patients, only high MTAC creatinine in 1 patient, and only high LAR in 2 patients. We could not identify a cause in 2 patients. Both groups had similar clearances of serum proteins and peritoneal restriction coefficients. However, dialysate cancer antigen 125 concentrations, reflecting mesothelial cell mass, were lower in the UFF patients (2.79 vs 5.38 U/L).

Conclusion

The prevalence of UFF is high in long-term PD. It is caused mainly by a large vascular surface area and by impaired channel-mediated water transport. In addition, these patients also had signs of a reduced mesothelial cell mass, indicating damage of the peritoneum on both vascular and mesothelial sites.

Complete regeneration of large bone defects in rats with commercially available fibrin loaded with BMP-2

This study aimed at investigating in vitro and in vivo the efficiency of commercially available fibrin as a carrier for controlled and sustained bone morphogenetic protein-2 (BMP-2) release to induce bone formation and reduce the side effects of its use. In vitro release and activity of low-dose recombinant human BMP-2 (rhBMP-2) (37.5 µg/mL) embedded in commercially available fibrin were evaluated and, subsequently, critical-size femur defects in rats were grafted to study bone regeneration and vascularisation by micro-computed tomography (µCT) and histology. In vitro experiments showed a sustained BMP-2 release with a high BMP activity remaining after 28 d. In vivo, fibrin loaded with BMP-2 showed an extremely fast bone healing, with a large amount of new bone formation throughout the entire defect in the first 4 weeks and complete cortical repair and fusion after 8 weeks, with no ectopic bone formation. In contrast, the control fibrin group did not fuse after 12 weeks. Vascularisation was similar in both groups at 4 and 12 weeks after implantation. In conclusion, commercially available fibrin is a very efficient carrier for rhBMP-2 to graft critical-size cortical bone defects and might be a more optimal delivery vehicle for BMP-2-induced bone regeneration than currently available collagen sponges.

Occupational asbestos exposure: how to deal with suspected mesothelioma cases—the Dutch approach

INTRODUCTION

Patients with asbestos-related diseases, such as malignant mesothelioma (MM), are not uniformly treated in Europe when they apply for compensation. In The Netherlands, the Institute of Asbestos Victims (IAV) acts on behalf of patients with a malignant mesothelioma. In the majority of cases, the diagnosis is clear but in some, uncertainty remains. In these cases a specialist opinion of the Mesothelioma Group of the Dutch Thoracic Society (DTS) is required. The process of data handling and final outcome for these patients is discussed and compared with the situation in other European countries.

MATERIALS AND METHODS

Dutch patients with a possible malignant mesothelioma and occupational exposure to asbestos presented their cases to the IAV. In 10% of the cases, pathological confirmation of a malignant mesothelioma could not be obtained. These cases were presented to the Mesothelioma Group to obtain a clinical diagnosis based on clinical reports, occupational history, X-ray examination and other factors. Each case was reviewed by three independent pulmonologists experienced in MM. The majority view was binding for acceptance or rejection of the diagnosis.

RESULTS

In the period January 2000 until May 2005, the IAV received 1747 cases for compensation. In 161 cases no definitive diagnosis could be made on pathology and were presented to the Mesothelioma Group. Of these cases, 117 (73%) were considered to be compatible with the clinical diagnosis malignant pleural mesothelioma. Forty-four cases (27%) were rejected. In 75% of the cases (112 of 150), the conclusion of the three independent specialists was unanimous; in 11 cases one specialist refrained from a diagnosis. The median time from request to submission of the report was 34 days (range 1-185 days).

CONCLUSIONS

Compared with other European countries, this approach, as determined by the IAV and Mesothelioma Group of the DTS, is an effective and rapid way to investigate claims of patients with a possible occupationally related malignant mesothelioma.

Molecular structure of the "low molecular weight antigen" of Toxoplasma gondii: a glucose alpha 1-4 N-acetylgalactosamine makes free glycosyl-phosphatidylinositols highly immunogenic

Toxoplasma gondii is a ubiquitous parasitic protozoan causing congenital infection and severe encephalitis in the course of the acquired immunodeficiency syndrome. Glycosyl-phosphatidylinositols of T. gondii have been shown to be identical with the low molecular weight antigen which elicits an early immunoglobulin M immune response in humans. A detailed study of the structures of these glycolipid antigens was performed. Radiolabelled glycolipids were extensively analysed by chemical and exoglycosidase treatments in combination with high pH anion-exchange chromatography, gel-filtration and lectin affinity chromatography. In addition, carbohydrate fragments prepared and purified from bulk preparations of unlabelled glycolipids by high performance liquid chromatography were subjected to two-dimensional 1H nuclear magnetic resonance spectroscopy, fast-atom bombardment-mass spectrometry, and methylation linkage analysis in order to elucidate the structure of T. gondii GPIs. The following structures were identified: (ethanolamine-PO4)-Man alpha 1-2Man alpha 1-6(GalNAc beta 1-4)Man alpha 1-4GlcN alpha-inositol-PO4-lipid and the novel structure (ethanolamine-PO4)-Man alpha 1-2Man alpha 1-6(Glc alpha 1-4GalNAc beta 1-4)Man alpha 1-4 GlcN alpha-inositol-PO4-lipid both with and without terminal ethanolamine phosphate. Evidence is provided, that only T. gondii GPIs bearing the unique glucose-N-acetylgalactosamine side branch are immunogenic in humans and that this structure is widely distributed among T. gondii isolates. Monoclonal antibodies have been characterized to recognize structures with different degrees of side-chain modification. We suggest that these reagents in combination with recently devised techniques for insertional mutagenesis in T. gondii should greatly facilitate the cloning of genes essential for GPI side-chain modification.

Glycosyl-phosphatidylinositols in protozoa structure, biosynthesis and intracellular localisation

We are investigating the structure and biosynthesis of glycosyl-phosphatidylinositols (GPI) in the protozoa Toxoplasma gondii, Plasmodium falciparum, Plasmodium yoelii and Paramecium primaurelia. This comparison of structural and biosynthesis data should lead us to common and individual features of the GPI-biosynthesis and transport in different organisms.

Evaluation of a new third generation anti-HIV-1/anti-HIV-2 assay with increased sensitivity for HIV-1 group O

Although the HIV-1 group O virus found in two persons of Cameroonian origin has been described in 1990 (De Leys et al., 1990), sera from group O infected individuals became available only recently. Several studies showed that some of the anti-HIV-1/HIV-2 screening tests failed to detect all of these samples (Loussert-Ajaka et al., 1994; Simon et al., 1994; Schable et al., 1994; Gürtler et al., 1995). In the current version of an anti-HIV-1/anti-HIV-2 screening assay, namely the Vironostika HIV Uni-Form II, an HIV-O specific peptide was introduced in order to improve HIV-1 group O reactivity. The peptide was derived from the immunodominant region of HIV-1 group O gp41 strain ANT70. All 30 anti-HIV-1 group O sera were detected by the so-called plus O assay, while 29 samples of this panel were positive the current assay. The sensitivity of the plus O assay for anti-HIV-1 and anti-HIV-2 positive samples is identical to that of the reference test without HIV-1 group O peptide. The clinical specificity of the HIV Uni-Form II plus O assay is improved to > or = 99.92% by an adjustment of the coat concentration of HIV-1 p24 (to avoid false positive p24 only reactions) without affecting sensitivity of the assay. The specific reaction of an HIV-1 group O specific rabbit serum for quality control purposes is presented.

Gitelman's variant of Bartter's syndrome, inherited hypokalaemic alkalosis, is caused by mutations in the thiazide-sensitive Na-Cl cotransporter

Maintenance of fluid and electrolyte homeostasis is critical for normal neuromuscular function. Bartter's syndrome is an autosomal recessive disease characterized by diverse abnormalities in electrolyte homeostasis including hypokalaemic metabolic alkalosis; Gitelman's syndrome represents the predominant subset of Bartter's patients having hypomagnesemia and hypocalciuria. We now demonstrate complete linkage of Gitelman's syndrome to the locus encoding the renal thiazide-sensitive Na-Cl cotransporter, and identify a wide variety of non-conservative mutations, consistent with loss of function alleles, in affected subjects. These findings demonstrate the molecular basis of Gitelman's syndrome. We speculate that these mutant alleles lead to reduced sodium chloride reabsorption in the more common heterozygotes, potentially protecting against development of hypertension.

Dose-finding and sequencing study of paclitaxel and carboplatin in non-small cell lung cancer

A dose-finding study was set up to identify the optimal dose of the combination of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) and carboplatin for phase II studies in patients with advanced chemotherapy-naive non-small cell lung cancer (NSCLC). The influence of drug sequence on the toxicity and pharmacokinetics of both agents was also assessed. To develop an ambulatory regimen for palliation of advanced NSCLC, paclitaxel was infused over 3 hours with standard premedication and carboplatin over 30 minutes. Cycles were repeated every 4 weeks. At each dose level, at least six patients were randomized to receive either paclitaxel followed by carboplatin or the reverse sequence. In the second and following cycles the alternate sequence was administered. The pharmacokinetics of both paclitaxel and carboplatin were compared in the first two cycles in at least two patients per dose level. Sixty-two patients have been entered in this study. Paclitaxel was increased from 100 mg/m2 in 25 mg/m2 increments up to a maximum of 225 mg/m2 combined with a fixed carboplatin dose (300 mg/m2). Thereafter, the drug doses were increased to a maximum of 400 mg/m2 carboplatin and 250 mg/m2 paclitaxel. In 243 cycles, the most frequent side effects were neutropenia, alopecia, and mild emesis. Only one patient developed a major hypersensitivity reaction to paclitaxel. Bone pain, myalgia, and peripheral neurotoxicity occurred more frequently at paclitaxel doses above 200 mg/m2. No significant differences in toxicity or in the pharmacokinetics of either drug were observed between the two drug sequences. The pharmacokinetics of paclitaxel were nonlinear and consistent with saturation. At the highest paclitaxel dose (250 mg/m2 with carboplatin 350 mg/m2) a toxic death due to severe leukopenia, thrombocytopenia, and hemorrhage occurred. Safe doses for phase II trials in untreated NSCLC are 200 mg/m2 paclitaxel with 300 mg/m2 carboplatin. Of 50 evaluable patients, five of the six major responses were observed at paclitaxel doses of 175 mg/m2 and above, which suggests a dose-response relationship for paclitaxel in NSCLC.

Preliminary results of two dose-finding studies of paclitaxel (Taxol) and carboplatin in non-small cell lung and ovarian cancers: a European Cancer Centre effort

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) given as a 24-hour infusion, and carboplatin have activity in advanced non-small cell lung cancer (NSCLC) and ovarian cancer. Two dose-finding studies were initiated to identify the optimal doses for the paclitaxel/carboplatin combination when paclitaxel is given in a 3-hour infusion. The fact that the pharmacologic interaction between paclitaxel and cisplatin increases the toxicity of paclitaxel when cisplatin is given before it also prompted an investigation of the influence of drug sequence on toxicity and pharmacokinetics in the NSCLC trial. Thirty-three patients with advanced NSCLC and 11 with advanced ovarian cancer previously untreated by chemotherapy have been enrolled to date. In the NSCLC trial escalating doses of paclitaxel were given in combination with a fixed carboplatin dose of 300 mg/m2, while both drugs were escalated in the ovarian cancer study. In both studies paclitaxel was infused over 3 hours and carboplatin over 30 minutes, and cycles were repeated every 4 weeks. The most frequent side effect has been neutropenia, although this did not result in any infectious episodes. Alopecia and mild emesis also have been frequently encountered. Mild skin reactions have been reported in a few patients. Bone pain and myalgia occur more frequently at the highest paclitaxel doses. No difference in toxicity has been observed thus far between the two drug sequences in the NSCLC study. Both studies are still accruing patients as the maximum tolerated doses of paclitaxel in combination with carboplatin have not yet been reached (carboplatin 300 mg/m2 with paclitaxel 175 mg/m2 in the NSCLC study; carboplatin 400 mg/m2 with paclitaxel 150 mg/m2 in the ovarian cancer study). An investigation of maximum tolerated doses with granulocyte colony-stimulating factor support is planned thereafter.

Radiosensitization by cytotoxic drugs. The EORTC experience by the Radiotherapy and Lung Cancer Cooperative Groups

A three-arm randomized trial was performed to assess the acute and late toxicity and the impact on survival of the combination high-dose, split-course radiotherapy with 30 mg/m2 cisplatin (cDDP) weekly, with 6 mg/m2 cisplatin daily compared to radiotherapy alone in patients with non-small cell lung cancer (NSCLC). The study started in May 1984 and was closed in May 1989 after 331 patients were randomised. The analysis was performed after a minimum follow-up period of 22 months. Radiotherapy (RT) consisted of 30 Gy, 10 fractions, five fractions a week; then a 3-week split followed by 25 Gy in 10 fractions. Nausea and vomiting were increased for a majority of the patients in the combined treatment arms during treatment. There was no addition of bone marrow suppression, renal dysfunction or esophagitis. Increase of late radiation damage was not observed. Local control (= absence of local progression) was improved for patients treated according to the daily cisplatin arm. This has lead to an improvement in overall survival. There was no effect in time to distant metastasis due to the combined modality. The treatment influence was confirmed in the multivariate analysis.

CONCLUSION

local control and survival can be improved by combining radiotherapy with daily low-dose cisplatin in patients with inoperable NSCLC.

Feasibility of curative radiotherapy with a concomitant boost technique in 33 patients with non-small cell lung cancer (NSCLC)

Thirty-three patients with an inoperable NSCLC were treated with a dose of 60 Gy/20 fractions/25 days, using a concomitant boost technique. A dose of 40 Gy/2 Gy/25 days was given to the tumor area and a part (15 patients) or the whole (18 patients) mediastinum. During each session a simultaneous boost to the tumor of 1 Gy was administered. Moderate acute oesophageal toxicity was observed in 7/33 patients (22%). One out of 33 patients developed serious late oesophageal toxicity. A correlation between the oesophageal toxicity, absorbed oesophageal dose of irradiation and length of the elective field was observed. Five out of 33 patients developed subacute radiation pneumonitis grade 2 or 3. In selected patients with inoperable NSCLC radiotherapy, with a dose of 60 Gy/20 fractions/25 days, using a concomitant technique is feasible.

Effects of concomitant cisplatin and radiotherapy on inoperable non-small-cell lung cancer

BACKGROUND AND METHODS

Cisplatin (cis-diamminedichloroplatinum) has been reported to enhance the cell-killing effect of radiation, an effect whose intensity varies with the schedule of administration. We randomly assigned 331 patients with nonmetastatic inoperable non-small-cell lung cancer to one of three treatments: radiotherapy for two weeks (3 Gy given 10 times, in five fractions a week), followed by a three-week rest period and then radiotherapy for two more weeks (2.5 Gy given 10 times, five fractions a week); radiotherapy on the same schedule, combined with 30 mg of cisplatin per square meter of body-surface area, given on the first day of each treatment week; or radiotherapy on the same schedule, combined with 6 mg of cisplatin per square meter, given daily before radiotherapy.

RESULTS

Survival was significantly improved in the radiotherapy-daily-cisplatin group as compared with the radiotherapy group (P = 0.009): survival in the radiotherapy-daily-cisplatin group was 54 percent at one year, 26 percent at two years, and 16 percent at three years, as compared with 46 percent, 13 percent, and 2 percent, respectively, in the radiotherapy group. Survival in the radiotherapy-weekly-cisplatin group was intermediate (44 percent, 19 percent, and 13 percent) and not significantly different from survival in either of the other two groups. The survival benefit of daily combined treatment was due to improved control of local disease (P = 0.003). Survival without local recurrence was 59 percent at one year and 31 percent at two years in the radiotherapy-daily-cisplatin group; 42 percent and 30 percent, respectively, in the radiotherapy-weekly-cisplatin group; and 41 percent and 19 percent, respectively, in the radiotherapy group. Cisplatin induced nausea and vomiting in 86 percent of the patients given it weekly and in 78 percent of those given it daily; these effects were severe in 26 percent and 28 percent, respectively.

CONCLUSIONS

Cisplatin, given daily in combination with the radiotherapy described here to patients with nonmetastatic but inoperable non-small-cell lung cancer, improved rates of survival and control of local disease at the price of substantial side effects.

Bovine immunodeficiency virus: immunochemical characterization and serological survey

Bovine immunodeficiency virus (BIV) was purified by isodensity centrifugation; viral activities were monitored in gradient fractions using the reverse transcriptase assay and a p26-specific monoclonal antibody ELISA. In the coincident peak fractions (density about 1.17 g/ml) proteins with Mr values of 26K, 17K, 53K, 14K and 100K (with decreasing intensity) were detected by Western blotting using serum of a calf after experimental BIV infection. When 957 randomly collected cattle sera from The Netherlands were tested by indirect immunofluorescence and confirmed using Western blot and/or radioimmunoprecipitation, 1.4% appeared seropositive. Thus BIV infection is not uncommon in one European cattle population.

Suppression of feline immunodeficiency virus infection in vivo by 9-(2-phosphonomethoxyethyl)adenine

The acyclic purine nucleoside analogue 9-(2-phosphonomethoxyethyl)adenine [PMEA; formerly referred to as 9-(2-phosphonylmethoxyethyl)adenine] is a potent and selective inhibitor of human immunodeficiency virus replication in vitro and of Moloney murine sarcoma virus-induced tumor formation in mice. In the latter system PMEA has stronger antiretroviral potency and selectivity than 3'-azido-3'-thymidine (AZT). We have now investigated the effect of the drug in cats infected with the feline immunodeficiency virus (FIV). In vitro, PMEA was found to efficiently block FIV replication in feline thymocytes (50% effective dose, 0.6 microM). When administered to cats at doses of 20, 5, or 2 mg/kg per day, PMEA caused a dose-dependent suppression of FIV replication and virus-specific antibody production. Seropositive field cats with signs of opportunistic infection (gingivitis, stomatitis, and diarrhea) showed clinical improvement during PMEA therapy (5 mg/kg per day) and recurrence of the disease after treatment was discontinued. Thus, FIV infection in cats is an excellent model to test the efficacy of selective anti-human immunodeficiency virus agents in vivo.

[Infections with feline T-lymphotropic lentivirus]

A new retrovirus was recently discovered in cats affected with an immunodeficiency syndrome (AIDS). The virus shows morphological and biological similarities with the human immunodeficiency virus (HIV), which causes AIDS in human individuals. As the T-lymphocyte is the primary target of the virus, it is termed Feline T-Lymphotropic Lentivirus (FTLV). FTLV is not antigenically related to HIV. Transmission of the virus from animals to human subjects has not been recorded. Cats infected with this virus showed lymphadenopathy, leukopenia, anorexia, chronic stomatitis/gingivitis and other opportunistic forms of infection. Neurological symptoms were also observed. Research is focused on diagnosis, treatment and prevention. Results obtained may contribute to research on AIDS in human subjects.