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Biomedical subjects

R A Roos

Publications and source records attributed to R A Roos.

At least 19 recordsLinked to original sources
PubMed1992

DNA-testing for Huntington's disease in The Netherlands: a retrospective study on psychosocial effects.

Presymptomatic DNA-testing for Huntington's disease has made it possible to predict whether or not at-risk individuals are gene-carriers with a reliability of about 98%. In our retrospective study of 18 tested individuals, most of the newly identified carriers function apparently well. They use avoidance and repression of affect as psychological defense strategies. However, 8 out of 9 non-carriers do not experience the expected relief about their test results. They experience survivor guilt and emotional numbness and find it difficult to cope with the effects of the test results on the family system. The partners of gene-carriers are at risk of becoming emotionally isolated by putting aside their own feelings for fear of seeming self-centered. Appreciation of these effects on tested individuals is important and professional support is needed to prevent post-traumatic stress disorders. Whatever the test result may be, the working through process may take years rather than months. These findings have important implications for patient care and necessitate an extended period of observation after presymptomatic testing.

Adult↗
PubMed1992

Acute phase proteins but not activated microglial cells are present in parenchymal beta/A4 deposits in the brains of patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type.

With immunohistochemical staining methods on cryostat sections we investigated the brains of three patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type, one of the cerebral beta/A4 amyloid diseases. Immunostaining for beta/A4 protein revealed numerous non-fibrillar beta/A4 depositions (amorphous or diffuse plaques) in the brain parenchyma in addition to extensive vascular amyloid deposition. All amorphous plaques contain complement proteins and alpha 1-antichymotrypsin but activated microglial cells expressing major histocompatibility (MHC) class II antigens HLA-DR and leucocyte adhesion molecules belonging to the lymphocyte-function-associated antigen (LFA)-1 family are virtually absent in cortical gray matter. Our findings are discussed from the view that a cascade of events including acute phase proteins and activated microglial cells are involved in classical amyloid plaque formation.

Acute-Phase Proteins↗
PubMed1992

Hereditary cerebral hemorrhage with amyloidosis-Dutch type: a study of fibrinolysis.

In view of reported associations between increased bleeding tendency and systemically decreased alpha 2-antiplasmin in patients with systemic amyloid deposition we studied alpha 2-antiplasmin, fibrinogen, C-reactive protein and blood levels of locally produced endothelial hemostasis factors in the acute and quiescent phase in 16 patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D). None of the factors measured in the quiescent phase of the disease was abnormal. In the acute phase, shortly after a stroke, only factor VIII:Ag was evidently elevated. We concluded that systemic abnormalities in the part of the fibrinolysis system studied are not likely to be responsible for multifocal and recurrent cerebral hemorrhages in HCHWA-D. The role of an elevated factor VIII:Ag level in the acute phase is unclear.

Amyloidosis↗
PubMed1992

Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis-Dutch type share a decrease in cerebrospinal fluid levels of amyloid beta-protein precursor.

The amyloid beta-protein is a 39-42 amino acid peptide that is deposited in senile plaques and in cerebral vessel walls in individuals with Alzheimer's disease, Down's syndrome, hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D), and, to a much lesser extent, normal aging. It is derived from abnormal proteolytic processing of its parent protein, the amyloid beta-protein precursor. Here we show that individuals with the HCHWA-D mutation and clinically manifesting the disease have markedly decreased cerebrospinal fluid levels of soluble amyloid beta-protein precursor (0.7 +/- 0.4 micrograms/ml) compared with age-matched normal subjects (3.0 +/- 0.2 micrograms/ml) as determined by quantitative immunoblotting and enzyme-linked immunosorbent assays. Similarly, age-matched patients diagnosed with probable Alzheimer's disease also have decreased cerebrospinal fluid levels of soluble amyloid beta-protein precursor (1.0 +/- 0.3 micrograms/ml). These parallel findings suggest a common biochemical marker for these two diseases and further establish the pathogenic relatedness of HCHWA-D and Alzheimer's disease.

Alzheimer Disease↗
PubMed1992

Morphology of cerebral plaque-like lesions in hereditary cerebral hemorrhage with amyloidosis (Dutch).

We studied the presence and morphology of plaque-like lesions in the frontal cortex of six patients, aged 40 to 76 years, with hereditary cerebral hemorrhage with amyloidosis--Dutch type (HCHWA-D), using beta/A4 immuno-, silver, Congo red and thioflavin S staining. Two types of beta/A4 immunoreactive and Congo red-negative plaques were detected. The first type was composed of argyrophilic fibrous material in periodic acid-methenamine silver (PAM) and modified Bielschowsky staining and lacked silver-stained degenerating neurites. Therefore, this type of plaque has the same staining properties as the diffuse plaque described in Alzheimer's disease, Down's syndrome and nondemented elderly. The second type of plaque, occurring only in the three oldest patients and numerically increasing with age, consisted of a spherical non-argyrophilic area of granular texture with a rim of PAM-positive material. The PAM-positive fibrous material of both types of plaques was mingled with coarser and compact, irregular-shaped argyrophilic structures in the oldest patient. The described plaques did not show bright fluorescence with thioflavin S staining. These results indicate, that the morphology of plaques, encountered in HCHWA-D, is diverse and changes with age.

Adult↗
PubMed1992

Are medium and long latency reflexes a screening tool for early Parkinson's disease?

We have studied whether assessment of medium latency (ML) and long latency (LL) reflex amplitudes may serve as a marker for early Parkinson's disease. Twenty-three patients with idiopathic Parkinson's disease (Hoehn and Yahr stage 1 to 4) and 24 controls received 20 4 degrees toe-up rotations of a platform upon which they were standing. All antiparkinsonian medication was withheld for at least 12 h before the study. ML reflexes in the stretched gastrocnemius muscle and LL reflexes in the shortened tibialis anterior muscle were recorded from both legs. ML responses were significantly enhanced in patients compared to controls. In contrast to previous studies which studied patients who continued their usual treatment, we observed that LL responses were significantly reduced in patients compared to controls. For the purpose of individual analysis, we subsequently determined the optimal specificity and sensitivity using various criteria for abnormality. The presence of either enhanced ML responses or reduced LL responses (or both) in at least one leg yielded a maximum sensitivity of 65.2% with a specificity of 75.0% (positive likelihood ratio 2.6; negative likelihood ratio 0.5). Abnormal reflexes were almost exclusively present in patients with advanced and long-standing Parkinson's disease. These results show abnormalities of ML and LL responses in advanced Parkinson's disease, but render it unlikely that these abnormalities are a suitable screening tool for early stages of the disease. The fact that LL responses were reduced in patients taken off antiparkinsonian medication raises the possibility that this reflex is under supraspinal dopaminergic control.

Aged↗
PubMed1992

Comparison between the Icelandic and Dutch forms of hereditary cerebral amyloid angiopathy.

Hereditary cerebral amyloid angiopathy has been described in Icelandic and Dutch families. Although the clinical manifestations show similarities, biochemical characterization revealed that amyloid in the Icelandic patients consists of cystatin C and in the Dutch patients of beta-protein. Both diseases are caused by a single base mutation leading to the same amino acid (viz. glutamine). Furthermore, both cystatin C and the beta-protein precursor are protease inhibitors. Therefore, the mechanism of amyloidogenesis may be similar in both diseases. A comparison of clinical, pathological, genetic, and biochemical aspects of these two types of hereditary cerebral amyloid angiopathy is presented.

Amyloid beta-Protein Precursor↗
PubMed1992

Copper-zinc superoxide dismutase in cerebrospinal fluid: implications for oxygen-radical stress in the central nervous system.

We determined the concentration of copper zinc superoxide dismutase (CuZnSOD) in cerebrospinal fluid (CSF) and plasma of 36 persons without neurological illness or with various central and peripheral nervous system disorders not supposed to generate abnormal radical formation. The CuZnSOD concentration in CSF was significantly higher compared with plasma, suggesting the presence of a high oxygen-radical load on the central nervous system. Our data may be considered to reflect normal values.

Adult↗
PubMed1992

Syncope or seizure? A matter of opinion.

We studied the diagnostic interpretation by physicians of written histories of 118 patients with a transient loss of consciousness. Considerable disagreement about a diagnosis of either syncope or seizure was found. Overall agreement was only 31%; an erroneous diagnosis was made in 16% of cases. We concluded that the diagnosis of a seizure after a single event is often too unreliable to justify early treatment.

Adolescent↗
PubMed1992

Non-invasive assessment of autonomic nervous function in Gilles de la Tourette syndrome.

Autonomic nervous function was investigated in 18 Gilles de la Tourette (GTS) patients and in 23 controls, who matched the patients in age, sex, baseline blood pressure and baseline heart rate. Four heart rate tests were used (variation at rest, during deep breathing, following standing up and during a Valsalva manoeuvre), and two blood pressure tests (standing up and sustained handgrip). The only significant difference between the groups was found in the Valsalva test. This was due to the initial heart rate increase which was higher in the GTS group; the subsequent decrease did not differ between the groups. Increased sympathetic activity is a possible explanation for this finding, but no additional evidence in its favour was found. No signs of autonomic failure were found.

Adolescent↗
PubMed1992

Clinical efficacy of Sinemet CR 50/200 versus Sinemet 25/100 in patients with fluctuating Parkinson's disease. An open, and a double-blind, double-dummy, multicenter treatment evaluation. The Dutch Sinemet CR Study Group.

In a multicenter study we selected 84 patients with fluctuating Parkinson's disease in order to evaluate the effects of controlled-release Sinemet 50/200 (=CR) versus standard Sinemet 25/100 (=STD) in an open-label 8-week titration period, followed by a double-blind, double-dummy 24-week treatment period. In contrast with previous double-blind studies, the efficacy of Sinemet CR proved to be significantly superior to that of Sinemet-STD according to NYUPDS and NUDS rating scales. This higher efficacy of Sinemet CR was not achieved at the expense of safety and/or tolerability. Actual total daily levodopa dosage in patients treated with Sinemet CR was increased by 33%; however, the plasma level of this dosage is calculated to be similar to that of the previous dosage of Sinemet-STD (bio-availability of Sinemet CR is 71%). Mean numbers of daily doses, off-hours, and off-periods were decreased significantly during Sinemet CR treatment. Although all other variables suggest that the number of on-hours had to be increased, statistical significance could not be reached in this respect.

Antiparkinson Agents↗
PubMed1992

Progressive dementia, without cerebral hemorrhage, in a patient with hereditary cerebral amyloid angiopathy.

A now 58-year-old female patient, carrier of the point-mutation in the beta-amyloid gene on chromosome 21 which causes hereditary cerebral hemorrhage with amyloidosis - Dutch type, developed progressive dementia after the age of 55 years. She never suffered from a cerebral hemorrhage. Dementia has been described as a feature of hereditary amyloid angiopathy before, but only in patients who also suffer from strokes. The clinical manifestation of the patient described here underlines the relation between the Dutch type of hereditary amyloid angiopathy and (familial) Alzheimer's disease.

Amyloid beta-Peptides↗
PubMed1992

Altered postural reflexes in Parkinson's disease: a reverse hypothesis.

In subjects standing on a movable platform, sudden dorsiflexion of the ankle joint elicits a set of reflexes in leg muscles. These responses include a short latency (SL) and medium latency (ML) stretch reflex in the gastrocnemius muscle and a distal to proximal innervation sequence of long latency (LL) reflexes in the shortened tibialis anterior and vastus lateralis muscles. Because of their role in maintaining upright stance these responses have been termed postural reflexes. In patients with Parkinson's disease (PD), the following abnormalities have been described: 1) enhanced ML-amplitudes; 2) a reversed LL innervation sequence; and 3) delayed onset latencies. These abnormalities are thought to be due to defective motor programming and disturbed control of spinal and supraspinal reflex centers by basal ganglia circuits. The altered reflexes have been held responsible for some of the clinical features of PD, including balance impairment and rigidity. In this paper, we argue the reverse hypothesis that postural reflexes are essentially normal in PD, and that the observed alterations are at least in part consequence rather than cause of balance impairment, the stooped parkinsonian posture and rigidity of PD patients.

Humans↗