Antibacterial activity of chemically defined chitosans: influence of molecular weight, degree of acetylation and test organism.

Chitosans, polysaccharides obtained from the exoskeleton of crustaceans, have been shown to exert antibacterial activity in vitro and their use as a food preservative is of growing interest. However, beyond a consensus that chitosan appears to disrupt the bacterial cell membrane, published data are inconsistent on the chemical characteristics that confer the antibacterial activity of chitosan. While most authors agree that the net charge density of the polymer (reflected in the fraction of positively charged amino groups at the C-2 position of the glucosamine unit) is an important factor in antibacterial activity, conflicting data have been reported on the effect of molecular weight and on the susceptibility among different bacterial species to chitosan. Therefore, we prepared batches of water-soluble hydrochloride salts of chitosans with weight average molecular weights (M(w)) of 2-224kDa and degree of acetylation of 0.16 and 0.48. Their antibacterial activity was evaluated using tube inhibition assays and membrane integrity assays (N-Phenyl-1-naphthylamine fluorescence and potassium release) against Bacillus cereus, Escherichia coli, Salmonella Typhimurium and three lipopolysaccharide mutants of E. coli and S. Typhimurium. Chitosans with lower degree of acetylation (F(A)=0.16) were more active than the more acetylated chitosans (F(A)=0.48). No trends in antibacterial action related to increasing or decreasing M(w) were observed although one of the chitosans (M(w) 28.4kDa, F(A)=0.16) was more active than the other chitosans, inhibiting growth and permeabilizing the membrane of all the test strains included. The test strains varied in their susceptibility to the different chitosans with wild type S. Typhimurium more resistant than the wild type E. coli. Salmonellae lipopolysaccharide mutants were more susceptible than the matched wild type strain. Our results show that the chitosan preparation details are critically important in identifying the antibacterial features that target different test organisms.

Sphagnan--a pectin-like polymer isolated from Sphagnum moss can inhibit the growth of some typical food spoilage and food poisoning bacteria by lowering the pH.

AIMS: Investigate if the antibacterial effect of sphagnan, a pectin-like carbohydrate polymer extracted from Sphagnum moss, can be accounted for by its ability to lower the pH. METHODS AND RESULTS: Antibacterial activity of sphagnan was assessed and compared to that of three other acids. Sphagnan in its acid form was able to inhibit growth of various food poisoning and spoilage bacteria on low-buffering solid growth medium, whereas sphagnan in its sodium form at neutral pH had no antibacterial activity. At similar acidic pH, sphagnan had comparable antibacterial activity to that of hydrochloric acid and a control rhamnogalacturonan pectin in its acid form. CONCLUSIONS: Sphagnan in its acid form is a weak macromolecular acid that can inhibit bacterial growth by lowering the pH of environments with a low buffering capacity. SIGNIFICANCE AND IMPACT OF THE STUDY: It has previously been suggested that sphagnan is an antimicrobial polysaccharide in the leaves of Sphagnum moss with a broad range of potential practical applications. Our results now show that sphagnan in its acid form can indeed inhibit bacterial growth, but only of acid-sensitive species. These findings represent increased knowledge towards our understanding on how sphagnan or Sphagnum moss might be used in practical applications.

Mantle cell lymphoma: prognostic capacity of the Follicular Lymphoma International Prognostic Index.

The International Prognostic Index (IPI) is the most commonly used prognostic model for mantle cell lymphoma (MCL). However, the prognostic value of the IPI is limited. The recently published Follicular Lymphoma International Prognostic Index (FLIPI) is built on variables, which are pertinent to MCL. This study was conducted to evaluate the prognostic value of FLIPI in a population-based series of 93 patients with MCL diagnosed in a 7-year period. End points of the study were response to therapy, overall survival, and disease-free survival (DFS) according to the IPI and FLIPI. Applied to the whole series, the FLIPI identified three risk groups with markedly different outcome with 5-year overall survival rates of 65%, 42%, and 8% respectively. Notably, the high-risk group comprised 53% of patients. In contrast, the IPI only allocated 16% of cases to the high-risk group and had a lower overall predictive capacity. When both the FLIPI and IPI were included in a multivariate analysis, only the FLIPI was related to survival. Multivariate analysis of DFS also identified the FLIPI, and not the IPI, as independently significant. Thus, in the present study, the FLIPI was superior as a prognostic model compared with the IPI and can therefore be recommended as a clinical prognostic index for MCL.

Improved chitosan-mediated gene delivery based on easily dissociated chitosan polyplexes of highly defined chitosan oligomers.

Nonviral gene delivery systems based on conventional high-molecular-weight chitosans are efficient after lung administration in vivo, but have poor physical properties such as aggregated shapes, low solubility at neutral pH, high viscosity at concentrations used for in vivo delivery and a slow dissociation and release of plasmid DNA, resulting in a slow onset of action. We therefore developed highly effective nonviral gene delivery systems with improved physical properties from a series of chitosan oligomers, ranging in molecular weight from 1.2 to 10 kDa. First, we established structure-property relationships with regard to polyplex formation and in vivo efficiency after lung administration to mice. In a second step, we isolated chitosan oligomers from a preferred oligomer fraction to obtain fractions, ranging from 10 to 50-mers, of more homogeneous size distributions with polydispersities ranging from 1.01 to 1.09. Polyplexes based on chitosan oligomers dissociated more easily than those of a high-molecular-weight ultrapure chitosan (UPC, approximately a 1000-mer), and released pDNA in the presence of anionic heparin. The more easily dissociated polyplexes mediated a faster onset of action and gave a higher gene expression both in 293 cells in vitro and after lung administration in vivo as compared to the more stable UPC polyplexes. Already 24 h after intratracheal administration, a 120- to 260-fold higher luciferase gene expression was observed compared to UPC in the mouse lung in vivo. The gene expression in the lung was comparable to that of PEI (respective AUCs of 2756+/-710 and 3320+/-871 pg luciferase x days/mg of total lung protein). In conclusion, a major improvement of chitosan-mediated nonviral gene delivery to the lung was obtained by using polyplexes of well-defined chitosan oligomers. Polyplexes of oligomer fractions also had superior physicochemical properties to commonly used high-molecular-weight UPC.

Preparation and characterisation of oligosaccharides produced by nitrous acid depolymerisation of chitosans.

Two chitosans with widely different chemical composition (fraction of N-acetylated units (F(A))<0.001 and F(A)=0.59), were degraded by nitrous acid, to obtain the reactive 2,5-anhydro-D-mannose- (M-) unit at the new reducing end. The fully N-acetylated and fully N-deacetylated oligomers were separated by size-exclusion chromatography. Both the chemical structure and purity were studied by one- and two-dimensional 1H and 13C NMR methods. The fully N-acetylated oligomers were found to be stable, whereas the N-deacetylated oligomers reacted intermolecularly by a Schiff base reaction between the 2-amino group on the N-deacetylated units and the M-units, facilitating the cleavage of the glycosidic bond next to the M-unit and the formation of 5-hydroxymethylfurfural (HMF).

Molecular weight dependency on the production of the TNF stimulated by fractions of rye (1-->3),(1-->4)-beta-D-glucan.

Mixed-linkage (1-->3),(1-->4)-beta-D-glucan with a weight average molecular weight varying between 79,800 and 13,900 was purified from rye. These fractions were used for stimulation of human monocytes to produce tumour necrosis factor (TNF). A mixed-linkage beta-glucan with a weight average molecular weight of 18,900 was found to be the most potent immunostimulator.

Molecular weight, structure, and shape of oat (1-->3),(1-->4)-beta-D-glucan fractions obtained by enzymatic degradation with lichenase.

Oat beta-glucan was partially degraded by lichenase for different periods of time. Weight-average molecular weights were obtained from SEC-RI-RALLS-Visc and ranged from 5300 to 257,200. Weight-average intrinsic viscosities ranged from 7 to 160 mL/g. The determined viscosity equation, [eta] = 5.47 x 10(-3) M 0.82, indicated an extended coil conformation. When the coil was modeled as a wormlike chain a persistent length of 2.30 nm was obtained. 1H and 13C NMR spectroscopy were used to identify the structural units in the partially degraded beta-glucan. The identification of the disaccharide laminaribiose in the hydrolysates may suggest the presence of a new structural feature in cereal beta-glucan.

CB/CC diffuse lymphoma: a distinct subtype of non-Hodgkin's lymphoma? A study of 1593 patients from a Danish population-based registry. Danish LYFO Study Group.

Between 1983 and 1993, 3165 cases of non-Hodgkin's lymphoma (NHL) were reported to the West Danish Lymphoma Registry (LYFO). Out of these, 148 (4.7%) were of the CB/CC diffuse subtype according to the Kiel classification. However, in the new European-American NHL consensus classification (REAL, 1994), CB/CC diffuse lymphoma was categorized as a provisional subtype only. In the LYFO material, death-probability curves show a significantly shorter survival in CB/CC diffuse than in CB/CC follicular. In order to detect further possible differences between CB/CC diffuse and other NHL subtypes, a number of clinical parameters at presentation were analyzed in a subset of five types of lymphoma. This subset included 148 cases of CB/CC diffuse, 435 cases of CB/CC follicular, 667 cases of CB diffuse, 202 cases of CC diffuse, and 131 cases of peripheral T-cell lymphoma. Using logistic regression analysis, significant differences could be demonstrated between CB/CC diffuse and the four other subtypes as regards sex ratio, age distribution, and sites of both nodal and extranodal involvement. These findings indicate that CB/CC diffuse has a distinct clinical phenotype and imply the existence of real biological differences between CB/CC diffuse and other subtypes of lymphoma.

In B-cell chronic lymphocytic leukaemia chromosome 17 abnormalities and not trisomy 12 are the single most important cytogenetic abnormalities for the prognosis: a cytogenetic and immunophenotypic study of 480 unselected newly diagnosed patients.

Of 560 consecutive, newly diagnosed untreated patients with B CLL submitted for chromosome study, G-banded karyotypes could be obtained in 480 cases (86%). Of these, 345 (72%) had normal karyotypes and 135 (28%) had clonal chromosome abnormalities: trisomy 12 (+12) was found in 40 cases, 20 as +12 alone (+12single), 20 as +12 with additional abnormalities (+12complex). Other frequent findings included abnormalities of 14q, chromosome 17, 13q and 6q. The immunophenotype was typical for CLL in 358 patients (CD5+, Slg(weak), mainly FMC7-) and atypical for CLL in 122 patients (25%) (CD5-, or Slg(strong) or FMC7+). Chromosome abnormalities were found significantly more often in patients with atypical (48%) than in patients with typical CLL phenotype (22%) (P < 0.00005). Also +12complex, 14q+, del6q, and abnormalities of chromosome 17 were significantly more frequent in patients with atypical CLL phenotype, whereas +12single was found equally often in patients with typical and atypical CLL phenotype. The cytomorphology of most of the +12 patients was that of classical CLL irrespective of phenotype. In univariate survival analysis the following cytogenetic findings were significantly correlated to a poor prognosis: chromosome 17 abnormalities, 14q+, an abnormal karyotype, +12complex, more than one cytogenetic event, and the relative number of abnormal mitoses. In multivariate survival analysis chromosome 17 abnormalities were the only cytogenetic findings with independent prognostic value irrespective of immunophenotype. We conclude that in patients with typical CLL immunophenotype, chromosome abnormalities are somewhat less frequent at the time of diagnosis than hitherto believed. +12single is compatible with classical CLL, and has no prognostic influence whereas chromosome 17 abnormalities signify a poor prognosis. In patients with an atypical CLL immunophenotype, chromosome abnormalities including +12complex, 14q+, del 6q and chromosome 17 are found in about 50% of the patients, and in particular chromosome 17 abnormalities suggest a poor prognosis.

Physicochemical studies on xylinan (acetan). I. Characterization by gel permeation chromatography on sepharose Cl-2B coupled with static light scattering and viscometry.

Laboratory-made samples of the polysaccharide xylinan (acetan) were fractionated on Sepharose Cl-2B using 0.1M NaCl as eluant. The weight average molar masses and intrinsic viscosities were estimated in the fractions by multiangle laser light scattering (off-line) and capillary viscometry, respectively. The Mark-Houwink-Sakurada plot was found to be indicative of semiflexible coils (a = 0.90). The angular dependence of scattered light was interpreted by fitting with theoretically calculated "Master Curves" in terms of a wormlike chain model. The ambiguity of the interpretation of scattering curves owing to the overlapping effects of chain stiffness and polydispersity is discussed in detail. The experimental data is found to be consistent with a persistence length of Lp = 100 nm. The main proportion consists of double-stranded chains (consistent with a robust double-helix), but single- and multistranded chains also are present. Our results suggest a fractionation according to the contour length rather than the molar mass.

The bone-marrow infiltration pattern in B-cell chronic lymphocytic leukemia is not an important prognostic factor. Danish CLL Study Group.

In a multicentre study of 635 consecutive newly diagnosed patients with B-CLL, the histological bone marrow (BM) specimens were reviewed independently by each of 3 pathologists and found evaluable for BM infiltration pattern in 575 patients, 404 of whom had a CD5+, mainly FMC7-, faint surface-membrane immunoglobulin (SIg) fluorescence-intensity ppenotype. In these 404 patients the following BM infiltration patterns were found: mixed nodular-interstitial (30%), moderate interstitial (44%), heavy interstitial (20%) and diffuse packed (6%). In univariate survival analysis, significant differences were found according to BM pattern (p < 0.05), the presence of nodules being a favorable prognostic sign. In multivariate survival analysis in a model including age, clinical stage, BM pattern, BM lymphocytosis, WBC and sex, only age and stage but not BM pattern or BM lymphocytosis had independent prognostic significance. In stage A, progression-free survival was significantly longer in patients with nodular than in patients with non-nodular bone-marrow pattern. The overall survival of these patients, however, did not differ, possibly owing to the prompt and prolonged treatment given to most patients at the time of progression to stage B or C. We conclude that in CD5+, SIg(faint), mainly FMC7-B-CLL, bone-marrow histology may predict unstable disease in early clinical stage but is not important for treatment decisions, when these are based on clinical stage.

[Primary cerebral non-Hodgkin's lymphomas and primary malignant brain tumors in a well-defined geographical area. Population-based data from the registry of non-Hodgkin's lymphoma in western Denmark, LYFO and the cancer registry, Kraeftens Bekaempelse]. / Primaere cerebrale non-Hodgkins lymfomer og primaere maligne hjernetumorer i et veldefineret geografisk område. Populationsbaserede data fra det vestdanske non-Hodgkins lymfom-register, LYFO, og Cancerregisteret, Kraeftens Bekaempelse.

In a Danish population-based non-Hodgkin's lymphoma (NHL) registry (LYFO) representing a population of 2.7 million all new cases of NHL were registered from 1st January 1983 to 31st May 1994. Incidence data of primary malignant tumours of the brain and central nervous system in western Denmark for the period 1971-1990 have been obtained from the Danish Cancer Registry. During the approximate 11-year period 3124 new cases of NHL were registered. Of these, 1152 (37%) were extranodal and 48 were non-AIDS related primary central nervous system lymphomas (PCNSL) accounting for 4.2% of extranodal NHL and 1.5% of all NHL, respectively. The average annual incidence rate of non-AIDS related PCNSL during the period was 1.56 cases per million population (age range: 15-85 yrs, median: 62 yrs, M/F ratio: 1). In a 23-year period there was no trend towards an increasing incidence of non-AIDS related PCNSL in a well-defined population. PCNSL accounted for 1.7% of all primary malignant brain tumours. Incidence of primary malignant brain tumours was stable, except for age ranges over 70 years. Histologically, 85% were high grade, centroblastic diffuse (60%) and immunoblastic lymphoma (13%) (Kiel classification). No T-cell lymphomas were detected. Treatment included surgical resection, whole brain irradiation (WBRT) and chemotherapy. Median survival for those receiving either WBRT or WBRT and chemotherapy was eight months and 20 months, respectively (p = 0.78). Overall survival was 53%, 38% and 26% at one, two and five years. Cox-regression analysis identified only one factor having independent impact on survival in performance score > or = 2 (PCNSL p < 0.001, RR = 5.8).

Dependence of the content of unsubstituted (cellulosic) regions in prehydrolysed xanthans on the rate of hydrolysis by Trichoderma reesei endoglucanase.

Removal of side chains from the bacterial polysaccharides xanthan and xylinan (acetan) results in the formation of unsubstituted cellulosic regions that are susceptible to hydrolysis by cellulases (beta-1,4-endoglucanases). In contrast to cellulose derivatives, low degrees of substitution (DS) may be obtained in xanthan without affecting the solubility in water, and longer unsubstituted regions are obtained for the same DS due to the regular distribution of side chains. By varying the fraction of cellobiosic residues carrying a side chain from 1.0 to 0.54, the viscosimetrically detected rate of hydrolysis by cellulase of conformationally disordered xanthan, increased by 4 orders of magnitude. An increase was also obtained by removing side chains from xylinan. An analysis of the kinetic data suggests that very long unsubstituted regions (more than 10 glucose residues) are required for maximum rate of hydrolysis by cellulase.

Influence of selected clinical events on the need for red blood cell transfusion in patients with severe cytopenia following myeloablative chemotherapy.

The transfusional need in patients treated with myeloablative chemotherapy appears to be greater than that resulting from bone marrow suppression alone. The erythrocyte transfusional need may be expressed as delta hb = the daily loss of haemoglobin (mmol/l/day), and multivariate analyses of factors influencing delta hb have been carried out. We have studied 124 patients, mainly with acute myeloid leukaemia, treated with 537 courses of chemotherapy, inducing cytopenia (a white cell count < 1.0 x 10(9)/l) in 476 cases. The transfusional need was 2.5-3 times greater than expected, suggesting the presence of haemolysis and/or occult bleedings. Using multiple regression analysis and repeated measurement analysis the main factor influencing the transfusional need was type/dose of chemotherapy. The higher the dose of cytarabine the greater then transfusional need. Other factors significantly influencing the transfusional need were tumour burden, fever, treatment-related events such as positive blood cultures, systemic fungal infection, mucosal bleeding, melaena/haematemesis and diarrhoea. Finally, it was found that the transfusional need decreased gradually during the cytopenic period.

Degradation of double-stranded xanthan by hydrogen peroxide in the presence of ferrous ions: comparison to acid hydrolysis.

Conformationally ordered, double-stranded xanthan, degraded in the presence of H2O2 and Fe2+ (at 20 degrees C) or in dilute acid (0.1 M HCl at 80 degrees C), produced xanthan variants with weight-average molecular weights (Mw) ranging from 2 x 10(6) to 5.4 x 10(4). In both cases the fraction of cleaved linkages in the glucan backbone (alpha), measured as reducing ends, increased to very high values (0.05 for Mw = 2-3 x 10(4)), demonstrating that a large number of linkages in the backbone could be cleaved without a correspondingly large reduction in Mw, in accordance with the double-stranded nature of xanthan. Extensive degradation (more than 10-fold reduction in Mw) in both cases released single-stranded, conformationally disordered oligomers; this release was accompanied by an increase in the rate of acid hydrolysis of the glucan backbone and a pronounced increase in the rate of release of glucose monomer. In contrast, there was no significant change in the rate of reducing end-group formation associated with the release of oligomers upon degradation with H2O2/Fe2+. Both types of degradation were accompanied by changes in the composition of the side chains. However, in contrast to acid hydrolysis, where the terminal beta-D-mannose is preferentially hydrolyzed, the reaction with H2O2/Fe2+ resulted in removal of both mannose and glucuronic acid at approximately equal rates. This observation can be explained by a preferential attack on the inner alpha-D-mannose, with concomitant removal of the entire side chain. Removal of side chains and the release of single-stranded oligomers by H2O2/Fe2+ strongly influenced the optical rotation and also broadened the chiroptically detected conformational transition, whereas no change in the transition temperature was observed.

Complement activation by malignant B cells from patients with chronic lymphocytic leukaemia (CLL).

It has previously been reported that the expression of the complement receptors CR1 (CD35) and CR2 (CD21) on malignant B cells in CLL is reduced compared with the expression on normal B cells, while deposition of complement C3 fragments, as a consequence of alternative pathway (AP) activation of complement, is observed on mononuclear cells from patients with B CLL. Following our demonstration that normal B cells are capable of activating the AP of complement in a CR2-dependent fashion, we have chosen to re-examine the complement-activating ability of B CLL cells in relation to their altered phenotype with respect to CR2 and the complement regulatory membrane proteins, CR1, decay accelerating factor (DAF) (CD55) and membrane cofactor protein (MCP) (CD46). Flow cytometry was used to measure expression of complement receptors and regulatory proteins on CD5+ B cells from CLL patients, as well as the deposition of C3 fragments occurring both in vivo and after in vitro AP activation. We have confirmed the reduced expression of CR1 and CR2 on CLL cells and have shown that AP activation in the presence of homologous, normal serum was reduced on B CLL cells compared with normal B cells. The degree of AP activation correlated directly with CR2 expression. In addition, we observed that CLL cells bear in vivo-deposited C3d,g, although at a significantly lower level than normal B cells.

Clinicopathological features, survival and prognostic factors of primary central nervous system lymphomas: trends in incidence of primary central nervous system lymphomas and primary malignant brain tumors in a well-defined geographical area. Population-based data from the Danish Lymphoma Registry, LYFO, and the Danish Cancer Registry.

It has been claimed that Primary Central Nervous System Lymphomas (PCNSL), a rare neoplasm accounting for only a small fraction of malignant brain tumors and extranodal non-Hodgkin lymphomas (NHL), occur with increasing frequency in immunologically normal as well as in immunocompromised individuals. In an attempt to characterize the clinicopathological features, outcome and prognostic factors of PCNSL we here report our experience in a large unselected series of patients from a well-defined region. In addition, we present data on trends in incidence of PCNSL and primary malignant brain tumors in a well-defined geographical area. In a Danish population-based NHL registry (LYFO) representing a population of 2.7 million all new cases of NHL were registered during the approximate 11-year period from 1st January 1983 to 31st May 1994. Incidence data of primary malignant tumors of the brain and central nervous system in western Denmark for the period 1971-1990 have been obtained from the Danish Cancer Registry. During the approximate 11-year period 3124 new cases of NHL were registered. Of these, 1152 (37%) were extranodal and 48 were non-AIDS related PCNSL accounting for 4.2% of extranodal NHL and 1.5% of all NHL, respectively. The average annual incidence rate of non-AIDS related PCNSL during the period was 1.56 cases per million population (age range: 15-85 yrs, median: 62 yrs, M/F ratio: 1). In a 23-year period there was no trend towards an increasing incidence of non-AIDS related PCNSL in a well-defined population. PCNSL accounted for 1.7% of all primary malignant brain tumors. Incidence of primary malignant brain tumors was stable, except for age ranges over 70 years. However, diagnostic artifacts might be responsible for this apparent increase. Histologically, 85% were high grade. Using the Kiel classification centroblastic diffuse (60%) and immunoblastic lymphoma (13%) were the most common subtypes. Forty-three patients had B-cell lymphoma and no T-cell lymphoma was detected. Forty-seven cases were diagnosed pre mortem. Treatment included surgical resection (26 patients), whole brain irradiation (WBRT) (43 patients) and chemotherapy (28 patients). Median survival for those receiving either WBRT or WBRT and chemotherapy was 8 months and 20 months, respectively (p = 0.78). Overall survival was 53%, 38% and 26% at 1, 2 and 5 years. Cox-regression analysis identified only one factor having independent impact on survival in PCNSL: performances score > or = 2 (p < 0.001, RR = 5.8).

Incidence, clinicopathological features and outcome of primary central nervous system lymphomas. Population-based data from a Danish lymphoma registry. Danish Lymphoma Study Group, LYFO.

BACKGROUND: Primary Central Nervous System lymphomas (PCNSL), a rare neoplasm accounting for only a small fraction of malignant brain tumors and extranodal non-Hodgkin's lymphomas (NHL), seems to occur with increasing frequency in immunologically-normal as well as immunocompromised individuals. In an attempt to characterize the clinicopathological features, incidence rate and outcome of PCNSL, we here report our experience in a large unselected group of patients from a well-defined region. PATIENTS AND METHODS: In a Danish population-based NHL registry (LYFO) representing a population of 2.7 million, all new cases of NHL were registered during the 10-year period from 1st January 1983 to 31st December 1992. The number of malignant brain tumors reported to the Danish Cancer Registry from the region covered by LYFO, during the 7-year period from 1st January 1983 to 31st December 1989, is compared to the number of PCNSL. RESULTS: During the 10-year period 2687 new cases of NHL were registered. Of these, 1004 (37%) were extranodal and 42 were non-AIDS-related PCNSL, accounting for 4.2% of extranodal NHL and 1.6% of all NHL, respectively. The incidence rate for PCNSL during the ten-year period (age range: 21-85 yrs, median: 62 yrs, M/F ratio: 0.9) was 15.6 cases per million population. Eighteen and 24 cases were diagnosed during the first and the second 5-year period, respectively (p > 0.05). During the 7-year period 1866 primary malignant brain tumors were registered in the region covered by the LYFO study group. In the same period 30 cases of PCNSL were detected. Thus, PCNSL accounted for 1.6% of all primary malignant brain tumors diagnosed in Western Denmark. Histologically, 83% were high-grade. Using the Kiel classification centroblastic diffuse (62%) and immunoblastic lymphoma (12%) were the most common subtypes. Thirty-seven patients had B-cell lymphoma; no T-cell lymphomas were detected. Forty-one cases were diagnosed pre mortem. Treatment included surgical resection (23 patients), whole brain irradiation (WBRT) (37 patients) and chemotherapy (22 patients). Median survival for those receiving either WBRT or WBRT and chemotherapy was 7.5 months and 12 months, respectively (p > 0.05). Survival was 43.9%, 31.7% and 7.3% at 1, 2 and 5 years.