PubMed Health⌕ Search

Biomedical subjects

M C Loonen

Publications and source records attributed to M C Loonen.

At least 19 recordsLinked to original sources
PubMed2000

Recombinant human alpha-glucosidase from rabbit milk in Pompe patients.

Pompe's disease is a fatal muscular disorder caused by lysosomal alpha-glucosidase deficiency. In an open-label study, four babies with characteristic cardiomyopathy were treated with recombinant human alpha-glucosidase (rhGAA) from rabbit milk at starting doses of 15 mg/kg or 20 mg/kg, and later 40 mg/kg. The enzyme was generally well tolerated. Activity of alpha-glucosidase normalised in muscle. Tissue morphology and motor and cardiac function improved. The left-ventricular-mass index decreased significantly. We recommend early treatment. Long-term effects are being studied.

Animals↗
PubMed1998

Muscle computed tomography in adult-onset acid maltase deficiency.

Nine patients with adult-onset acid maltase deficiency (Pompe's disease) were examined clinically and with computed tomography (CT). The CT scan showed early and severe involvement of the muscles of trunk and thighs, with selective sparing of the tensor fasciae latae, short head of biceps femoris, gracilis, and sartorius muscles. Shoulder and leg muscles were less affected. The disease spread over the years from trunk to extremities. Muscle strength and CT findings were positively correlated.

Adult↗
PubMed1996

A quality of life instrument for adolescents with chronic headache.

We developed a generic Quality of Life (QL) measurement scale for adolescents between 12 and 18 years of age, primarily for use on youngsters with chronic headaches or migraine. The Quality of Life Headache in Youth (QLH-Y) is a 71 item (69 multiple choice items and two visual analogue scales) QL measurement scale. It assesses an individual's QL in six QL subdomains. Study 1 (n = 223) was aimed at item selection and scale construction. Thirteen subscales were developed to cover the four QL subdomains Psychological Functioning, Functional Status, Physical Status and Social Functioning. The QL subdomains Satisfaction with Life in General and Satisfaction with Health were covered by two visual analogue scales. Internal consistency of nearly all the subscales was satisfactory. Study 2 (n = 159) was conducted to evaluate the validity and stability of the QLH-Y. Indications for parent-youth agreement, construct validity and sensitivity for headache and migraine were obtained. Stability coefficients were between 0.47 and 0.72 for the 1-week interval and between 0.31 and 0.60 for the 6-month interval. Nearly all of the QLH-Y subscales appeared to be more sensitive to differences between subjects with headaches and headache-free subjects, while the QL subdomain Functional Status was most sensitive for subjects who had suffered from a recent headache.

Adaptation, Psychological↗
PubMed1995

Carrier detection of Batten disease (juvenile neuronal ceroid-lipofuscinosis).

Batten disease, or the juvenile form of neuronal ceroid lipofuscinosis, is an autosomal recessive neurodegenerative disorder manifesting with progressive blindness, seizures, and dementia, leading to an early death. The CLN3 locus which is involved in Batten disease had been localized to chromosome 16p11.2. Linkage disequilibrium has been observed between CLN3 and polymorphic microsatellite markers D16S288, D16S299, and D16S298, making carrier detection and prenatal diagnosis by haplotype analysis possible. For the purpose of carrier detection, haplotypes from Dutch Batten patients and their families were constructed. Most patients share the same D16S298 allele, suggesting the presence of a founder effect in the Dutch population. In a large inbred Dutch family, in which Batten disease occurs with high frequency, haplotype analysis has been carried out with high accuracy for carrier detection.

Alleles↗
PubMed1994

Solomon's epidermal nevus syndrome (type: linear nevus sebaceus) and hypophosphatemic vitamin D-resistant rickets.

BACKGROUND: Epidermal nevus syndrome is very variable in symptoms and associated abnormalities. Synonyms of this syndrome are linear nevus sebaceus syndrome or Schimmelpenning-Feuerstein-Mims syndrome or Solomon syndrome. The combination with vitamin D-resistant rickets is rare and only sporadically described. Less than 10 cases with this combination of symptoms have been described in the literature. OBSERVATIONS: We describe a boy suffering from epidermal nevus syndrome (type: nevus sebaceus). This child also presented with severe rickets with hyperphosphaturia, resistant to vitamin D. Our patient was seen in consultation at birth, but after a delay of 4 years we were consulted again for a second opinion and treatment; the vitamin D-resistant rickets was recognized. Treatment with 1,25-dihydroxy vitamin D3 and phosphorus resulted in healing of rickets. Removal of parts of the tumors did not influence the rickets. This is in contrast with a formerly described case. Removal of fibroangiomas led in that case to normalization of the alkaline phosphatase, calcium, and phosphate serum levels. CONCLUSIONS: The rickets results from massive phosphate excretion by defective renal tubular reabsorption of phosphate. In all patients described, rickets developed at an early age. Clinical symptoms were marked bone abnormalities, muscle weakness, and bone pain.

Child↗
PubMed1993

X-linked ataxia, weakness, deafness, and loss of vision in early childhood with a fatal course.

An X-linked recessive disease with, in almost all patients, a fatal course in early childhood, occurring in a five-generation family is described. The 12 affected boys had early-onset floppiness, ataxia, liability to infections especially of the upper respiratory tract, deafness, and later, a flaccid tetraplegia and areflexia. Eleven boys died before the age of 5 years. One boy is still alive at the age of 12 years, but in addition to the above-mentioned signs, he must be ventilated at night and is nearly blind due to optic atrophy. In the only patient whose central nervous system could be examined at the time of autopsy, an almost complete absence of myelin in the posterior columns of the spinal cord was found. This may be the main pathological substrate for the neurological findings. No biochemical or immunological defects were detected. The family also counted 16 healthy male siblings and 13 definite of 28 possible female carriers. Some carriers developed a hearing impairment in early adulthood. As far as is known now, this disease has not been described before.

Ataxia↗
PubMed1993

Blind, deaf and mute after a status epilepticus caused by hyperpyrexia from shigellosis--a case report with a four-year follow-up.

A nearly four-year-old boy awoke blind, deaf and mute from a coma of five days duration after a status epilepticus caused by hyperpyrexia from shigellosis. The authors give a detailed report of the recovery. Visual and auditory functions recovered within six months after the onset but expressive language difficulties remained. Following a discussion of the underlying mechanisms producing the cerebral damage, the hypothesis of a type of "disconnection syndrome" is put forward to explain the persisting language deficit.

Age of Onset↗
PubMed1990

Acquired childhood aphasia. Outcome 1 year after onset.

The effects of the variables age at onset, cause, severity and bilaterality of lesion, and type of aphasia on course and outcome were investigated in a group of 28 aphasic children. Analysis of spontaneous speech and tests of auditory verbal comprehension were used to determine the presence of aphasia. The severity of the cerebral lesion was assessed using a rating scale for computed tomographic scans. Most of the children had not recovered completely 1 year after onset. Recovery was significantly different according to etiological categories. Complete recovery was seen in the majority of traumatic cases.

Adolescent↗
PubMed1990

Diagnostic features and clinical signs of 21 patients with lissencephaly type 1.

Lissencephaly type I has been described as either the cerebral expression of a complex malformation syndrome such as Miller-Dieker syndrome (MDS), or as isolated lissencephaly sequence (ILS). In a nation-wide study in The Netherlands, of 21 patients with lissecephaly type I, four were found to have MDS and 17 ILS. New clinical aspects were as follows: the mean life-span of the entire group was longer than previously reported; patients with lissencephaly grades 3 or 4 (mixture of agyria and pachygyria, or complete pachygyria) developed seizures later than those with grades 1 and 2 (complete and almost complete agyria); microcephaly was not always present in patients with grades 3 and 4 lissencephaly; and patients with lissencephaly grades 1 and 2 had hardly any psychomotor development, while those with grades 3 and 4 were severely retarded.

Cerebral Cortex↗
PubMed1990

Rat heart perfusion as model system for enzyme replacement therapy in glycogenosis type II.

Cardiac failure and skeletal muscle weakness are the main clinical features of glycogenosis type II, a lysosomal storage disorder caused by acid alpha-glucosidase deficiency. In our study, we have investigated in a rat heart perfusion-recirculation system whether acid alpha-glucosidase can be taken up from the vascular system into cardiomyocytes. When rat hearts were perfused with mannose 6-phosphate-containing acid alpha-glucosidase purified from bovine testis, a 3- to 4-fold increase of enzyme activity was obtained. Perfusion with human placental acid alpha-glucosidase not containing the mannose 6-phosphate recognition marker did not have such an effect. The presence of bovine testis acid alpha-glucosidase in heart tissue was demonstrated by immunoblotting. Immunocytochemistry provides evidence for uptake of the exogenous enzyme in lysosomes of the cardiomyocytes. The relevance of these findings for enzyme therapy in glycogenosis type II is discussed.

Animals↗
PubMed1989

The natural history of the Guillain-Barré syndrome in 18 children and 50 adults.

Plasma exchange (PE) is indicated in adult patients with a severe Guillain-Barré syndrome (GBS). For children this has not been proven. If the disease runs a milder course in children, the problems experienced with PE might outweight the benefit. In order to evaluate the need for such a specific treatment in children, we compared the severity of the disease between 18 children and 50 adults; no significant differences were found. The mean duration of hospitalisation of all children was 84 days, four children needed artificial ventilation for a mean of 21.5 days and two children died. We conclude therefore that PE is indicated in children with a severe GBS. The final decision, however, depends also on the practical feasibility of the procedure.

Adolescent↗
PubMed1989

[The Landau-Kleffner syndrome: a special form of acquired childhood aphasia].

The syndrome of "acuqired aphasia with convulsive disorder" occurs in children between 3 and 7 years of age and is characterized by a language disorder with heterogeneous epileptic manifestations. The pathogenesis is unknown. The course can show marked fluctuations. Our study of 6 children shows that the outcome can range from extremely unfavorable to complete recovery. The variables that possibly influence the course are discussed.

Aphasia↗
PubMed1988

Prospect for enzyme therapy in glycogenosis II variants: a study on cultured muscle cells.

Impairment of skeletal muscle function is the common feature of distinct clinical forms of glycogenosis type II. In the present study, muscle cultures from different patients were used to investigate the cause of clinical heterogeneity and the feasibility of enzyme replacement therapy. The activity of acid alpha-glucosidase appears to be the primary factor in determining the extent of lysosomal glycogen storage in muscle, and thereby the clinical severity of the disease. Neutral alpha-glucosidases do not seem influential. Correction of the enzymatic defect was achieved in skeletal muscle cultures from patients by administration of a "high-uptake" form of acid alpha-glucosidase, purified from human urine. The enzyme reaches the lysosomes, including the glycogen storage vacuoles, and the lysosomal glycogen content is reduced to control level. In normal muscle cells 20% of the total cellular glycogen pool is segregated in lysosomal compartments. This percentage is higher than in fibroblasts, which may partly explain why muscles are more prone to store glycogen. The relevance of this study for enzyme therapy is discussed.

Cells, Cultured↗
PubMed1988

Receptor-mediated uptake of acid alpha-glucosidase corrects lysosomal glycogen storage in cultured skeletal muscle.

Attempts at treatment of glycogenosis type II and other lysosomal storage disorders by enzyme replacement have been reported. Parenteral enzyme administration has been ineffectual. Treatment by bone marrow transplantation is currently under investigation. We have used cultured skeletal muscle cells from a patient with infantile glycogenosis type II to study fundamental aspects of enzyme replacement therapy. Efficient uptake of acid alpha-glucosidase was achieved by using the mannose-6-phosphate receptor on the cell surface as a target for an enzyme precursor with phosphorylated high-mannose types carbohydrate chains purified from human urine. We found that the enzyme was channeled to the lysosomes and converted to mature acid alpha-glucosidase. Glycogen storage was reversed. The results are discussed in relation to treatment of glycogenosis type II.

Carrier Proteins↗
PubMed1987

Cranial CT in the Sjogren-Larsson syndrome.

Cranial CT in a case of Sjögren-Larsson syndrome (SLS) showed a striking loss of attenuation of supratentorial white matter. This is in accordance with the myelin loss found at microscopic brain examination of patients with SLS, but not with the only report of five patients examined by cranial CT. The considerable myelin loss may be detected only by more recent generations of CT scanners and seems to be stationary during lifetime.

Brain↗
PubMed1987

Cytochrome c oxidase deficiency in subacute necrotizing encephalomyelopathy.

Two new patients with Leigh's syndrome (subacute necrotizing encephalomyelopathy) due to deficiency of cytochrome c oxidase are presented and their data are compared with those of the four Leigh's syndrome patients previously reported with this deficiency. It is not possible to distinguish between the various biochemical aetiologies of Leigh's syndrome on clinical grounds. Investigation of pyruvate metabolism and of the respiratory chain will reveal the enzymatic defect in some of the patients. It has now been firmly established that a relationship exists between Leigh's syndrome and deficiency of cytochrome c oxidase. There are, however, other syndromes which are also associated with a deficiency of this enzyme. In Leigh's syndrome, the enzyme deficiency has been reported in many organ systems and in cultured fibroblasts. In the liver, however, decreased, intermediate or normal values of cytochrome c oxidase activity have been found. Selective or more widespread involvement of organ systems, due to mutations of either the nuclear or the mitochondrial DNA encoding for different subunits of the enzyme molecule (some of which may be organ- or tissue-specific), could explain the clinical and biochemical heterogeneity of syndromes associated with a cytochrome c oxidase deficiency.

Brain↗
PubMed1987

Breakdown of lysosomal glycogen in cultured fibroblasts from glycogenosis type II patients after uptake of acid alpha-glucosidase.

Fibroblast cultures from patients with different clinical subtypes of glycogenosis type II were compared with respect to residual acid alpha-glucosidase activity and lysosomal glycogen content. Lysosomal glycogen storage was most pronounced in fibroblasts from patients with the rapidly progressive infantile form of the disease, and the most severe enzyme deficiency. In fibroblasts from adult patients with more than 10% of the control activity storage did not occur, and 15% of the total cellular glycogen was found in the lysosomes as in control cells. The strict correlation between residual acid alpha-glucosidase activity and lysosomal glycogen accumulation was further illustrated in two adult Pompe patients with an unusually low enzyme activity. The mild clinical course is unexplained in these particular cases. The enzyme deficiency in all the different mutant cell lines was corrected by the uptake of bovine testis acid alpha-glucosidase from the culture medium. As a result of this, the lysosomal glycogen storage disappeared, and the balance between lysosomal and cytoplasmic glycogen was restored to normal. The implications of this study as a model for enzyme replacement therapy are discussed.

Cell Fractionation↗