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M Lammens

Publications and source records attributed to M Lammens.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Development and developmental disorders of the human brain. III. Neuronal migration disorders of the cerebrum].

Neuronal migration disorders of the cerebral cortex form a heterogeneous group of abnormalities, characterised by mental retardation, epilepsy and hypotonia. They are prevalent in 1% of the population and in 20-40% of the untreatable forms of epilepsy. Disorders at the start of the migration result in nodular heterotopias. Bilateral periventricular nodular heterotopias are X-linked disorders, in which cortical neurons are unable to leave their position at the ventricular surface due to the absence of filamin 1. The large group of lissencephalies can be divided into a number of syndromes, each of which is characterised by a gene mutation (LIS1, DCX, RELN). These mutations result in agyria and pachygyria, which are characteristic for this group. A number of these abnormalities, especially the smaller nodular heterotopias and focal cortical dysplasia, may be treated by neurosurgical excision.

Cell Movement↗
PubMed2001

[Development and developmental disorders of the human brain. II. Development of the cerebral cortex and major tract systems].

In the development of the cerebral cortex, two phases can be distinguished: (a) the formation of the preplate, a superficial layer essential for a normal lamination of the cerebral cortex; (b) the formation of the cortical plate. The cortical plate divides the preplate into a superficial marginal zone (the future layer I) and the subplate. The transient subplate is important for the formation of thalamocortical projections. Most cortical neurons arise in the ventricular zone of the pallium and migrate along radial glial cells (radial migration) to the cortical plate. The gamma-aminobutyric acid (GABA)ergic cortical interneurons, however, originate from the ganglionic eminences and reach the cerebral cortex through tangential migration.

Brain↗
PubMed2001

Clinical and pathologic abnormalities in a family with parkinsonism and parkin gene mutations.

A Dutch family with autosomal recessive early-onset parkinsonism showed a heterozygous missense mutation in combination with a heterozygous exon deletion in the parkin gene. Although the main clinical syndrome consisted of parkinsonism, the proband clinically had additional mild gait ataxia and pathologically showed neuronal loss in parts of the spinocerebellar system, in addition to selective loss of dopaminergic neurons in the substantia nigra pars compacta. Lewy bodies and neurofibrillary tangles were absent, but tau pathology was found.

Aged↗
PubMed2001

[Development and the developmental disorders of human brain. I. Early development of the cerebrum].

The recent discovery of many genes that regulate brain development is revolutionizing our knowledge of neuroembryology and, moreover, our understanding of how gene defects cause human birth defects. The first 8 weeks of the development of the cerebrum can be subdivided into 23 stages, with early development of mostly the spinal cord and the brain stem. Regionalization of the brain has been related to genes that play a part in it. A characteristic developmental disorder for this early phase in the development of the forebrain is holoprosencephaly, a brain patterning disorder. Numerous genes play a part in its occurrence; abnormal function of signal factors as well as of transcription factors may lead to holoprosencephaly.

Brain↗
PubMed2001

Characteristic chromosomal aberrations in sporadic cerebellar hemangioblastomas revealed by comparative genomic hybridization.

Hemangioblastomas (HBs) of the central nervous system are benign tumors and occur as sporadic (sp) tumors (75%) or as a manifestation of the von Hippel-Lindau (VHL) disease (25%). VHL-disease is an autosomal dominant disorder characterized by HBs of the central nervous system and retina, renal cell carcinoma (RCC), phaeochromocytoma (PHEO), islet tumors of the pancreas, and endolympatic sac tumors as well as cysts and cystadenoma in the kidney, pancreas and epididymis. In VHL patients a large spectrum of germline mutations in the VHL gene has been detected. In spHBs VHL alleles are reported to be inactivated in up to 50% of the tumors. To our knowledge the involvement of other genes in spHBs has not been investigated. To elucidate the oncogenesis of spHBs, we performed CGH on 10 spHBs to screen for chromosomal imbalances throughout the entire tumor genome. Aberrations most frequently detected are losses of chromosomes 3 (70%), 6 (50%), 9 (30%), and 18q (30%) and a gain of chromosome 19 (30%). Based on these frequencies and the co-occurrence of these aberrations in the analyzed tumors we hypothesize that loss of chromosome 3 (harboring the VHL gene) is an early event in the oncogenesis of spHBs, followed by loss of 6, and then losses of chromosomes 9, 18q and gain of chromosome 19. Comparison of the chromosomal imbalances in spHBs to those previously reported in RCCs and PHEOs reveals that the pathway of spHBs shows similarities to both the RCCs and PHEOs.

Adrenal Gland Neoplasms↗
PubMed2000

Effect of Flavobacterium psychrophilum strains and their metabolites on the oxidative activity of rainbow trout oncorhynchus mykiss phagocytes.

The oxidative activity of rainbow trout phagocytes was studied using a chemiluminescence technique using 12 different Flavobacterium psychrophilum strains and their metabolites. Phagocytes were obtained from the head kidney of rainbow trout Oncorhynchus mykiss. The addition of viable F. psychrophilum or their metabolites to the phagocytes resulted in an immediate chemiluminescence response. The stimulating effects of both the F. psychrophilum and their metabolites on the phagocytes were found to be heat stable. No significant differences in stimulation capacity were found between the strains tested. To investigate the nature of the stimulating agent, both the bacteria and the supernatant were treated with either sodium metaperiodate or polymyxin B. Adding polymyxin B to the bacterial cells and supernatant did not change the chemiluminescence pattern, suggesting that the capacity of F. psychrophilum to stimulate the phagocytes probably is not due to lipopolysaccharides (LPS). However, following incubation of the bacteria and their metabolites with sodium metaperiodate, the capacity to stimulate phagocytes was significantly impaired. This suggests that a carbohydrate component most likely plays an important role in the ability of F. psychrophilum to stimulate phagocytes. Opsonisation of the bacteria with native trout serum or with rabbit anti-F. psychrophilum serum resulted in an additional chemiluminescence peak which was significantly higher than the first peak. This extra peak disappeared following heat treatment of the trout serum and the rabbit anti-F. psychrophilum serum, pointing towards the involvement of heat labile complement in opsonisation.

Animals↗
PubMed2000

Peripheral primitive neuroectodermal tumour of the cervix.

Peripheral primitive neuro-ectodermal tumours (PNET) of the cervix are very rare. Here, we report the clinical, pathological, immunohistochemical and genetic features of a case of a PNET located in the cervix. Hysterectomy revealed a cervical tumour. On microscopic examination, a vaguely lobular arrangement of uniformly appearing neoplastic cells, with round to oval nuclei, distinct nuclear membranes and a clear, moderately glycogen-rich cytoplasm was seen. Cells stained positive for LEU 7, S 100, monoclonal NSE and particularly for MIC2. Neurogenic differentiation was also seen by electron microscopic examination. The genetic hallmark of PNET, a 22q12 rearrangement was demonstrated by fluorescence in situ hybridisation experiments, supporting the diagnosis. Awareness of the existence of primary PNET of the cervix is important to avoid confusion with other tumours of the cervix.

Biomarkers, Tumor↗
PubMed2000

Difficulties in experimental infection studies with Flavobacterium psychrophilum in rainbow trout (Oncorhynchus mykiss) using immersion, oral and anal challenges.

This study was carried out in order to try to establish an efficacious and reliable experimental infection model for Flavobacterium psychrophilum, the causative agent of rainbow trout fry syndrome, using contact, oral and anal challenges. Ten F psychrophilum strains of different origin were included. The influence of water temperature, scarification, water quality, stress and growth conditions of the pathogen on the experimental infection was assessed. For each challenge protocol, all strains failed to reproduce disease signs or mortality in rainbow trout (Oncorhynchus mykiss L.) fry. Histological and bacteriological examination of the skin, gills and internal organs of the fish 3 weeks following inoculation were found to be negative. Different hypotheses to explain the inability of the challenge models to reproduce the disease experimentally are discussed.

Animals↗
PubMed2000

Neuronal migration disorders in man.

A classification of neuronal migration disorders based on the gross morphology of the disorder with subclassifications according to the cause of the underlying disorder as far as that is known is presented. Emphasis is on disorders of the neocortex. The classical entities classical lissencephaly, cobblestone lissencephaly, polymicrogyria, neuronal heteropia within the white matter and leptomeningeal glial and glioneuronal heterotopia are described. Recent findings on the genetics of neuronal migration disorders are discussed. More subtle structural abnormalities such as cortical dysgenesis or dysplasia remain still more controversial as separate entities.

Brain↗
PubMed2000

14q terminal deletion: prenatal diagnosis in a child with severe congenital anomalies.

A fetal patient presented at 27.3 weeks of gestation with polyhydramnion. Ultrasound examination showed enlarged cerebral ventricles, abnormal position of the fingers and abnormal external genitals. Chromosome studies in chorionic villus material were normal male: in cultured amniocytes a distal deletion 14q32 was demonstrated and confirmed by FISH analysis. The baby was born at 37 weeks and died spontaneously during labour. This is the first report of prenatal diagnosis of a terminal 14q deletion.

Abnormalities, Multiple↗
PubMed1999

Clinical and genetic heterogeneity in autosomal recessive nemaline myopathy.

Autosomal recessive nemaline (rod) myopathy is clinically and genetically heterogeneous. A clinically distinct, typical form, with onset in infancy and a non-progressive or slowly progressive course, has been assigned to a region on chromosome 2q22 harbouring the nebulin gene Mutations have now been found in this gene, confirming its causative role. The gene for slow tropomyosin TPM3 on chromosome 1q21, previously found to cause a dominantly inherited form, has recently been found to be homozygously mutated in one severe consanguineous case. Here we wished to determine the degree of genetic homogeneity or heterogeneity of autosomal recessive nemaline myopathy by linkage analysis of 45 families from 10 countries. Forty-one of the families showed linkage results compatible with linkage to markers in the nebulin region, the highest combined lod scores at zero recombination being 14.13 for the marker D2S2236. We found no indication of genetic heterogeneity for the typical form of nemaline myopathy. In four families with more severe forms of nemaline myopathy, however, linkage to both the nebulin and the TPM3 locus was excluded. Our results indicate that at least three genetic loci exist for autosomal recessive nemaline myopathy. Studies of additional families are needed to localise the as yet unknown causative genes, and to fully elucidate genotype-phenotype correlations.

Child↗
PubMed1999

Primary malignant peripheral nerve sheath tumour of the heart.

AIMS: Malignant peripheral nerve sheath tumour (MPNST) is an unusual sarcoma of the heart and should be differentiated from other spindle cell sarcomas. METHODS AND RESULTS: We combined morphological, immunohistochemical and cytogenetic techniques in the differential diagnosis, particularly from monophasic synovial sarcoma. The tumour consisted of dense fascicles, alternating with hypocellular, myxoid zones. There was a marked herniation of tumour cells into the vascular lumen. Immunohistochemically, the tumour cells expressed vimentin and focally S100 protein. There was no expression of cytokeratin or epithelial membrane antigen (EMA). Although we found a complex karyotype, the finding of involvement of 17q11. the loss of chromosome 22, and the absence of a t(X:18)(p11.2:q11.2), which characterizes synovial sarcoma allowed us to the final diagnosis of malignant peripheral nerve sheath tumour. CONCLUSION: MPNST of the heart can be diagnosed by combining morphological and immunohistochemical data. Cytogenetics can be useful in reaching a correct diagnosis, also by helping to rule out monophasic synovial sarcoma.

Aged↗
PubMed1998

The linear naevus sebaceus syndrome.

The linear naevus sebaceus syndrome (LNSS) is a phakomatosis, characterized in general by a triad consisting of naevus sebaceus of Jadassohn, seizures, and mental retardation. In addition, a broad spectrum of neurological, ophthalmological, skeletal, urogenital and cardiovascular symptoms may be encountered. According to our literature review, seizures and mental retardation were reported in 67 and 61% of cases, respectively. Because ophthalmological abnormalities (59%) and involvement of other organ systems (61%) occur frequently, we advise avoidance of adhering to the classical triad for recognizing or describing LNSS. Gross structural abnormality of the cerebrum or cranium was frequently observed (72%), consisting mainly of enlargement of one lateral ventricle, hemimegalencephaly and hemimegacranium. We report a case of a male patient with the clinical features of LNSS, but without cerebral developmental abnormalities at autopsy examination.

Adult↗
PubMed1998

Neuropathological findings in Moebius syndrome.

Pathological findings in two patients with Moebius syndrome and lethal fetal akinesia sequence are described. In both patients a congenital brain stem malformation with neuronal loss in the cranial nerve nuclei and tegmental microcalcifications was observed. In one patient, the association with splenogonadal fusion was observed, whilst in the second patient, the association with tetraperomelia was present. As the association of peromelia and splenogonadal fusion is a well-known association, the different combination of splenogonadal fusion, peromelia and Moebius syndrome due to congenital brain stem anomalies with necrosis might be the result of a disruptive phenomenon during a prolonged vulnerable critical period in the 5th and 6th week of embryonic life. The finding of olivary dysplasia in one case, reminiscent of olivary dysplasia in Zellweger syndrome and in Miller Dieker syndrome, might suggest a primary malformation underlying Moebius syndrome due to brain stem defects.

Abnormalities, Multiple↗
PubMed1997

Fetal akinesia sequence caused by nemaline myopathy.

Nine patients with the characteristic signs of fetal akinesia sequence (polyhydramnion, multiple joint contractures and lung hypoplasia) are described. In 8 of the 9 patients nemaline myopathy could be demonstrated with histology. The ninth patient presented the same phenotype as his 4 affected siblings in whom the nemaline myopathy could be histologically proven. Seven of the patients belonged to 2 families; the other 2 patients were isolated cases. In one fetal case nemaline myopathy was documented at week 22 of gestation. These observations demonstrate that nemaline myopathy can cause the fetal akinesia sequence, with onset of first symptoms as early as the beginning of the second trimester of pregnancy.

Abnormalities, Multiple↗
PubMed1996

[Granulomatous hepatitis attributed to the combination pyrimethamine-chloroquine].

After her holiday in South Africa, a 50-year-old woman was admitted because of fever and pain in the upper abdomen. The laboratory tests showed moderately increased serum liver enzyme activities. The liver biopsy showed a granulomatous hepatitis. Further investigations revealed no evidence for sarcoidosis, tuberculosis or infectious hepatitis, nor for other granulomatous diseases or infectious diseases relevant to South Africa. Upon discontinuation of the malaria prophylaxis with Daraclor (pyrimethamine and chloroquine (sulphate)) the symptoms disappeared and the liver function tests returned to normal. It was concluded that Daraclor was the probable cause of granulomatous hepatitis in this patient. This adverse effect was not published before.

Antimalarials↗