A PDGFRA promoter polymorphism, which disrupts the binding of ZNF148, is associated with primitive neuroectodermal tumours and ependymomas

BACKGROUND

Platelet derived growth factor receptor alpha (PDGFRalpha) expression is typical for a variety of brain tumours, while in normal adult brain PDGFRalpha expression is limited to a small number of neural progenitor cells. The molecular mechanisms responsible for the PDGFRalpha expression in tumours are not known, but in the absence of amplification, changes in transcriptional regulation might be an important factor in this process.

METHODS AND RESULTS

We have investigated the link between single nucleotide polymorphisms (SNPs) within the PDGFRalpha gene promoter and the occurrence of brain tumours (medulloblastomas, supratentorial primitive neuroectodermal tumours (PNETs), ependymal tumours, astrocytomas, oligodendrogliomas, and mixed gliomas). These SNPs give rise to five different promoter haplotypes named H1 and H2alpha-delta. It is apparent from the haplotype frequency distribution that both PNET (10-fold) and ependymoma (6.5-fold) patient groups display a significant over-representation of the H2delta haplotype. The precise functional role in PDGFRalpha gene transcription for the H2delta haplotype is not known yet, but we can show that the H2delta haplotype specifically disrupts binding of the transcription factor ZNF148 as compared to the other promoter haplotypes.

CONCLUSIONS

The specific over-representation of the H2delta haplotype in both patients with PNETs and ependymomas suggests a functional role for the ZNF148/PDGFRalpha pathway in the pathogenesis of these tumours.

[Hydrops fetalis as an indication for a systematic investigation into the presence of lysosomal storage diseases]

As a result of the decreased incidence of immunological hydrops fetalis and increased insight, the role of inborn errors of metabolism (IEM) as a cause of hydrops fetalis has acquired increased significance. This growing awareness of the manifestation of IEM in pregnancy has revealed that some 20 of these disorders may cause hydrops fetalis, accounting for a few percent of all cases. These IEM are, for the most part, lysosomal storage diseases. We recommend that standard metabolites and enzymes reflecting lysosomal storage diseases be measured in the amniotic fluid and the amniocytes already withdrawn for karyotyping. The value of the diagnosis of lysosomal storage diseases lies in the opportunity for risk evaluation, genetic counselling and targeted prenatal diagnostics in case of subsequent pregnancies. Obtaining insight into the possible therapestic interventions during the pregnancy in which the hydrops is observed is not a goal of this protocol since the necessary investigations are too time-consuming.

Growth factor analysis of low-grade glioma CSF: PDGF and VEGF are not detectable

Platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF-2) are involved in the development of grade 2 gliomas. The aim of the present study was to determine the presence of these growth factors in the cerebrospinal fluid (CSF) and to assess their usefulness as biological markers. CSF was collected from 7 adult patients with newly diagnosed supratentorial low-grade gliomas by lumbar puncture and was analysed together with matched serum samples using radioreceptor and enzyme-linked immunosorbant assays. Neither PDGF nor VEGF were detected in the CSF, and FGF-2 was measurable at extremely low concentrations in only 2 of 7 patients. Serum levels were within normal limits. We conclude that these growth factors are not released into the CSF in any significant amounts and are therefore not suitable as biological markers in grade 2 gliomas.

Prognostic value of platelet derived growth factor alpha receptor expression in grade 2 astrocytomas and oligoastrocytomas

OBJECTIVE

To determine whether the expression of platelet derived growth factor alpha receptor (PDGFRalpha) in low grade astrocytomas and oligoastrocytomas is associated with survival.

METHODS

Formalin fixed and paraffin embedded tumour samples of 40 consecutive patients with supratentorial diffuse astrocytomas and oligoastrocytomas of WHO grade 2, resected between 1986 and 1993, were used for immunohistochemical staining. The fraction of tumour cells expressing PDGFRalpha protein was quantified and entered into univariate and multivariate survival analyses. Changes in PDGFalpha expression over time were analysed in seven patients in whom reoperations had been performed.

RESULTS

Patients with a relatively high fraction of PDGFRalpha expressing cells had a more favourable outcome in both univariate (p = 0.04) and multivariate analyses (p = 0.02). Expression of PDGFRalpha was greater in oligoastrocytomas than in astrocytomas (p = 0.05). In four reoperated patients with histologically confirmed malignant transformation, there was a marked decrease in the number of cells expressing the receptor.

CONCLUSIONS

There is an association between high PDGFRalpha expression and long survival time in patients with grade 2 astrocytomas and oligoastrocytomas. The findings suggest that expression of the receptor may be a useful prognostic marker in such patients.

Low-grade gliomas: clinical and pathobiological aspects

The optimal management of patients with low-grade gliomas remains a challenge for the treating physician. The natural history of the disease shows a large variety, and there is a substantial controversy about many of everyday treatment recommendations. However, new developments in clinical and basic research in neuro-oncology have occurred during the last years. In this review some of these new insights into clinical and biological aspects of low-grade gliomas are discussed, with focus on the translation of new knowledge from basic research into clinical practice. For example, molecular genetic profiling of tumour material has started to guide treatment recommendations and clinical management of some patients with oligodendrogliomas. Experimental studies of the different molecular pathways in tumour cells and in their normal counterparts involved in cell-cycle check-point control have elucidated some of the underlying mechanisms of resistance of gliomas to radiotherapy and chemotherapy. Finally, improved classification of the different subtypes of low-grade gliomas may be achieved in the near future by characterization of the genetic heterogeneity within the tumour and by identification of a putative stem cell as the origin of the tumour cells.

Positron emission tomography (11)C-methionine and survival in patients with low-grade gliomas

BACKGROUND

Considerable numbers of patients with low-grade gliomas experience an early malignant course and may benefit from aggressive treatment. These patients are difficult to identify using established prognostic factors. A retrospective study was performed to determine whether the (11)C-methionine uptake in tumor is a survival factor in adult patients with supratentorial gliomas classified as World Health Organization Grade 2.

METHODS

The authors identified 89 patients with histologically confirmed low-grade gliomas in whom an (11)C-methionine positron emission tomography (PET) scan had been performed as part of the diagnostic tumor investigation from 1983 to 1998. Clinical data were collected, and the PET scans were re-evaluated according to a fixed protocol. The (11)C-methionine uptake in the tumor and relevant clinical parameters were entered into univariate and multivariate survival analyses.

RESULTS

At the end of the study, 49 patients (55.1%) had died. The median overall survival was 5.7 years. Low methionine uptake was significantly favorable in the multivariate survival analysis (P = 0.04) along with oligodendroglioma (P = 0.003). In the histologic subgroups, (11)C-methionine uptake was an important survival factor among patients with astrocytomas (P = 0.05) and oligodendrogliomas (P = 0.03). Tumor resection was a favorable prognostic factor in patients with high methionine uptake (P = 0.01) but not in patients with low uptake.

CONCLUSIONS

Baseline (11)C-methionine PET is a prognostic indicator in patients with low-grade gliomas. The results imply that PET is a valuable tool in the clinical management of these patients and may assist in the selection of patients for therapy.

Molecular analysis of a familial case of renal cell cancer and a t(3;6)(q12;q15)

We identified a novel familial case of clear-cell renal cancer and a t(3;6)(q12;q15). Subsequent cytogenetic and molecular analyses showed the presence of several abnormalities within tumour samples obtained from different patients. Loss of the der(3) chromosome was noted in some, but not all, of the samples. A concomitant VHL gene mutation was found in one of the samples. In addition, cytogenetic and molecular evidence for heterogeneity was obtained through analysis of several biopsy samples from one of the tumours. Based on these results and those reported in the literature, we conclude that loss of der(3) and subsequent VHL gene mutation may represent critical steps in the development of renal cell cancers in persons carrying the chromosome 3 translocation. Moreover, preliminary data suggest that other (epi)genetic changes may be related to tumour initiation.

Introduction of an N-glycosylation site increases secretion of heterologous proteins in yeasts

Saccharomyces cerevisiae is often used to produce heterologous proteins that are preferentially secreted to increase economic feasibility. We used N-glycosylation as a tool to enhance protein secretion. Secretion of cutinase, a lipase, and llama V(HH) antibody fragments by S. cerevisiae or Pichia pastoris improved following the introduction of an N-glycosylation site. When we introduced an N-glycosylation consensus sequence in the N-terminal region of a hydrophobic cutinase, secretion increased fivefold. If an N-glycosylation site was introduced in the C-terminal region, however, secretion increased only 1.8-fold. These results indicate that the use of N glycosylation can significantly enhance heterologous protein secretion.

[Risk of increased malignancy a reason for follow-up of low malignancy grade glioma. Early identification of high-risk patients is the key to good care]

Management of patients with low-grade gliomas remains a challenge. Controversies exist regarding the value of surgery and radiotherapy as well as the right timing of these treatments with respect to disease course. Several factors have been shown to have a positive correlation with better outcome, involving tumor size and localization, age and clinical condition of the patient on presentation, and epileptic seizures as a single symptom. The absence of contrast enhancement on CT-scans is also a favorable prognostic factor. Taking into account the results of these studies as well as our own experience, we suggest some strategies for the management of patients with low-grade gliomas. The importance of identifying "high-risk" patients by systematic clinical and radiological follow-up is discussed.

[Low malignancy grade glioma in the Uppsala++/Orebro region. Prognostic factors and survival among 119 patients]

The benefit of surgery and radiotherapy for patients with low-grade gliomas is controversial. We studied case records of 119 patients diagnosed with low-grade glioma during 1987-1993 at our hospital. Statistical analysis was made on overall survival and on survival related to histological diagnosis and treatment modality. A large variation in survival of patients with similar histological diagnosis was seen. No correlation was found between survival and treatment modality. This clinical diversity probably reflects variations in tumor biological characteristics of low-grade gliomas. Greater understanding of the biology of these tumors will thus be needed for more effective therapies.

Noninvasive test for fragile X syndrome, using hair root analysis

Identification of the FMR1 gene and the repeat-amplification mechanism causing fragile X syndrome led to development of reliable DNA-based diagnostic methods, including Southern blot hybridization and PCR. Both methods are performed on DNA isolated from peripheral blood cells and measure the repeat size in FMR1. Using an immunocytochemical technique on blood smears, we recently developed a novel test for identification of patients with fragile X syndrome. This method, also called "antibody test," uses monoclonal antibodies against the FMR1 gene product (FMRP) and is based on absence of FMRP in patients' cells. Here we describe a new diagnostic test to identify male patients with fragile X syndrome, on the basis of lack of FMRP in their hair roots. Expression of FMRP in hair roots was studied by use of an FMRP-specific antibody test, and the percentage of FMRP-expressing hair roots in controls and in male fragile X patients was determined. Control individuals showed clear expression of FMRP in nearly every hair root, whereas male fragile X patients lacked expression of FMRP in almost all their hair roots. Mentally retarded female patients with a full mutation showed FMRP expression in only some of their hair roots (<55%), and no overlap with normal female controls was observed. The advantages of this test are (1) plucking of hair follicles does no appreciable harm to the mentally retarded patient, (2) hairs can be sent in a simple envelope to a diagnostic center, and (3) the result of the test is available within 5 h of plucking. In addition, this test enabled us to identify two fragile X patients who did not show the full mutation by analysis of DNA isolated from blood cells.

Platelet-derived growth factor (PDGF) in primary brain tumours of neuroglial origin

It has become clear that disruptions in the genome of somatic cells play a causative role in tumour development. We know that the ultimate formation of a malignancy is the result of a multistep process in which the functional loss and/or the altered or increased expression of genes play important roles. One such family of genes are the oncogenes, encoding protein products with mainly growth stimulating effects. Platelet-derived growth factor (PDGF) belongs to the family of oncogenes. It is likely that PDGF plays an essential role in the development of at least a subgroup of malignant astrocytic tumours that do not contain amplification of the EGF-receptor. The expression of PDGF alpha-receptors is related to tumour progression in these tumours, and some of the most malignant tumours were shown to contain amplification of the PDGF alpha-receptor. It is also clear now from several experimental studies that PDGF can drive the transformed phenotype, and that PDGF antagonists, by blocking the PDGF autocrine pathway revert the transformed phenotype of certain tumour cells. Because of the findings that receptor protein tyrosine kinases such as the EGF- and the PDGF-receptor play a crucial role in the development of gliomas, it is possible that inhibitors of the phosphorylation of the protein tyrosine kinases will be future candidates for glioma therapy. They might be able to at least delay the development of a fully malignant glioma. The role of PDGF in other tumours of neuroglial origin in the central nervous system has not been studied as extensively as its role in gliomas. Recent data suggest that also for the primitive neuroectodermal tumours overexpression of the PDGF alpha-receptor is related to malignancy of the tumours. For other tumours, such as neuroblastomas, PDGF exerts a differentiating rather than a mitogenic function and is an important survival factor. Further studies are needed to elucidate the role of PDGF in these non-glial primary brain tumours. Moreover, for a complete understanding of the role of PDGF in malignancies of the CNS, it is important to explore its function in the development of the normal CNS further.

A familial case of renal cell carcinoma and a t(2;3) chromosome translocation

Cytogenetic analysis was performed on peripheral blood lymphocytes of members of a family with inherited renal cell cancer. Four family members in three generations developed multiple/bilateral renal cell carcinomas of the clear cell type. In one additional case a bladder carcinoma was diagnosed. In two of the renal cell carcinoma patients a constitutional t(2;3)(q35;q21) was encountered, whereas in the two other (deceased) patients the presence of this translocation could be deduced. Also, the bladder cancer patient was found to be positive for t(2;3)(q35;q21). This is the third familial renal cell carcinoma-associated chromosomal translocation ever described. The previously reported cases also involved chromosome 3, thereby supporting the notion that this chromosome may play a crucial role in the development of renal cell carcinomas. Interestingly, the translocation breakpoints in these three families map at different locations, suggesting that multiple genes on chromosome 3 may be involved.

Intraspecific isozyme polymorphism of Anopheles gambiae in relation to environment, behavior, and malaria transmission in southwestern Burkina Faso

A cellulose acetate electrophoresis system was used to study the isozyme polymorphism of the Anopheles gambiae complex in a rural village and a city in southwestern Burkina Faso. In both areas A. gambiae Giles was the dominant species (95%) whereas A. arabiensis Patton represented only 5%. Both species were separated readily by octanol dehydrogenase Odh and mannose phosphate isomerase (Mpi) even if they shared some alleles at these two loci. Polymorphism analysis (13 loci) at the intraspecific level of A. gambiae showed a significant difference between the specimens collected in the city from those collected in the village in their allelic and genotypic frequencies of isocitrate dehydrogenase-1 and malate dehydrogenase-1 and in their allelic frequencies for Mpi. No genetic difference was observed between the human biting A. gambiae collected inside or outside the houses in either the village or the city. The Plasmodium falciparum-infected A. gambiae differed from the noninfected ones in their allelic and genotypic frequencies at Mpi and acid phosphatase (Acp). A two-fold difference in infection rate was found for the genotype Mpi130/130 and Acp110/100 compared with other genotypes. However, infected anophelines were found in all genotypes that belonged to these two enzyme systems. Consequently, no refractory mechanism occurs in these natural populations.

Rapid antibody test for diagnosing fragile X syndrome: a validation of the technique

To date, the identification of patients and carriers of the fragile X syndrome has been carried out by DNA analysis by means of the polymerase chain reaction and Southern blot analysis. This direct DNA analysis allows both the size of the CGG repeat and methylation status of the FMR1 gene to be determined. We have recently presented a rapid antibody test on blood smears based on the presence of FMRP, the protein product of the FMR1 gene, in lymphocytes from normal individuals and the absence of FMRP in lymphocytes from patients. Here, we have tested the diagnostic value of this new technique by studying FMRP expression in 173 blood smears from normal individuals and fragile X patients. The diagnostic power of the antibody test is "perfect" for males, whereas the results are less specific for females.

At least nine cases of trisomy 11q23-->qter in one generation as a result of familial t(11;13) translocation

Carriers of balanced reciprocal translocations may have a (high) risk for producing liveborn children with an unbalanced karyotype. We report a large family in which a translocation between the long arm of chromosome 11 and the short arm of chromosome 13 is segregating in at least five generations. During the course of our study 15 carriers of the balanced translocation were identified and nine cases of partial trisomy of the long arm of chromosome 11 were detected during pre- and postnatal studies. Several of the patients were thoroughly clinically examined and compared with similar published cases.

Evaluation of general practice care by chronically ill patients: effect of the method of administration

BACKGROUND

Although the patient survey has become a popular method for learning about patients' views and experiences, little attention has been paid to the validity and feasibility of different survey methods.

OBJECTIVE

A study was undertaken to compare handing out written questionnaires to chronically ill patients who consecutively visited the general practice with mailing questionnaires to chronically ill patients who were sampled from the patient register.

METHOD

Patient surveys were performed in eight general practices in The Netherlands, applying both methods of administering the questionnaire to patients in each practice (n = 345).

RESULTS

The response rate was 63% in the mail survey and 72% in the hand-distributed survey. The sample composition was almost equal, except that patients in the hand-distributed survey more often reported having 'a different chronic disease.' The item-response for each aspect of care was similar in both methods of administration.

CONCLUSION

Patients in the mail survey tended to use the extreme categories on the scale for certain aspects of care more often than patients in the hand-distributed survey, but the overall trend was not significant.

Enzyme polymorphisms in the Anopheles gambiae (Diptera:Culicidae) complex related to feeding and resting behavior in the Imbo Valley, Burundi

A cellulose acetate electrophoresis system was used to study the Anopheles gambiae complex at 2 villages in Central Imbo Valley and at 1 village in South Imbo Valley (Burundi). In South Imbo, only An. gambiae Giles sensu stricto was present. In the drier Central Imbo, the dominant species was An. arabiensis Patton (97.5%); An. gambiae s.s. represented only 2.5%. Both species were separated readily by Odh and Mpi, because they did not share alleles at those loci. Indoor resting An. gambiae s.s. from South Imbo differed significantly from outdoor resting females at 2 Ioci, Mpi, and Got-2. In Central Imbo, total An. arabiensis did not differ between adjacent villages. Endophagic An. arabiensis significantly differed at loci alpha-Gpd, and Idh-1 between the 2 villages, whereas no difference was observed between exophagic females. Allelic and genotypic frequencies at the locus Mdh-2 were significantly different between indoor and outdoor biting An. arabiensis. Active choice for the best place to bite or to rest seemed to be associated with specific genotypes. The Nei genetic distance values were typical of conspecific populations, ranging from 0.154 to 0.160 between An. gambiae s.s. and An. arabiensis. Even though vector populations were structured at spatial and behavioral levels, they were panmictic, and thus selection of exophilic or exophagic vectors, or both, by insecticide pressure is not likely to occur.

Indicators of the quality of general practice care of patients with chronic illness: a step towards the real involvement of patients in the assessment of the quality of care

OBJECTIVE

To develop a list of indicators of the general practice care of people with chronic illnesses considered important by both patients and practitioners and to identify the indicators that are considered relevant for patient assessment of health care quality.

DESIGN

Qualitative study with focus group interviews and a written consensus procedure.

SETTING

General practice in the Netherlands in 1993.

SUBJECTS

34 patients with chronic illness, mostly members of patient organisations, and 19 general practitioners with expertise in either chronic disease management or experience with patient surveys.

MAIN MEASURES

Aspects of general practice care considered important for the delivery of good quality care that emerged from focus group interviews; the relevance of evaluations of 41 aspects of care for patients explored through the written consensus procedure. Those aspects of general practice care agreed to be both important and relevant by patients and general practitioners were considered to be suitable indicators for patient assessment of the quality of care.

RESULTS

Patients and general practitioners differed to some extent in their assessment of the aspects of care that they considered important for quality. They agreed that most indicators of care that related to the ¿doctor-patient relation¿ and to ¿information and support¿ were relevant and therefore suitable as indicators for patient assessment of health care quality. There was less agreement about the relevance of indicators of ¿medical and technical care,¿ ¿availability and accessibility,¿ and ¿organisation of services.¿

CONCLUSIONS

Several indicators of the quality of general practice care of patients with chronic illness were thought to be suitable for the patient assessment of healthcare quality, but other indicators were not, mainly because of reservations by general practitioners.

IMPLICATIONS

Qualitative methods can contribute to the selection of indicators for assessment of the quality of health care in areas where scientific evidence is limited or where patients' and providers' preferences are particularly important.