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Biomedical subjects

A Brun

Publications and source records attributed to A Brun.

At least 91 records · Page 5Linked to original sources
PubMed1995

Scanning gel densitometry of amniotic fluid acetylcholinesterase and butyrylcholinesterase: quantification of 'faint-positive' bands in fetal malformations.

The quantification of 'faint-positive' cholinesterases in amniotic fluid was performed in 40 patients with positive acetylcholinesterase (AchE) tests. Fetuses with anencephaly and open spina bifida presented an AchE/butyrylcholinesterase (A/B) ratio of more than 0.3 with clearly dense bands. Fetuses with gastroschisis showed a 'faint-positive' AchE band (A/B < 0.3). In 5 fetuses (1 teratoma, 3 open spina bifida, 1 unaffected) we found faint AchE and butyrylcholinesterase bands.

Acetylcholinesterase↗
PubMed1995

Performance of sulfhydryl boron hydride in patients with grade III and IV astrocytoma: a basis for boron neutron capture therapy.

This study investigated the rationale of boron neutron capture therapy (BNCT) for the treatment of Grade III and IV astrocytoma. The European Community joint research program on BNCT plans to use sulfhydryl boron hydride (BSH) in clinical trials. The work presented here, examines the performance of BSH in eight patients with Grade III and IV astrocytoma using a measurement technique which precisely correlates the boron uptake with the histology of the tumor and the peritumoral brain. Astrocytomas are exceptionally heterogeneous and spread migrating tumor cells into the surrounding brain. The patients were infused with 50 mg BSH per kilogram of body weight at 12, 18, 24 or 48 hours before surgery. At the time of operation, specimens were obtained of the tumor, skin, muscle, dura, blood, urine, and, when surgically possible, the brain adjacent to tumor. In three patients the intracellular boron distribution was investigated by subcellular fractionation. The blood clearance was biphasic with half-lives of 0.6 and 8.2 hours. After 3 days, approximately 70% of the dose injected was excreted in the urine. The maximum boron concentration in the tumor was 20 ppm, 12 hours after the infusion. The tumor-to-blood ratios ranged between 0.2 and 1.4, with the highest values after 18 to 24 hours. In the brain specimens the boron concentration never exceeded 1 ppm. This work confirms a selective uptake of boron in the tumor compared to the surrounding brain and that boron, to some extent, is incorporated in the tumor cells.

Astrocytoma↗
PubMed1995

A comparative study on the pharmacokinetics and biodistribution of boronated porphyrin (BOPP) and sulfhydryl boron hydride (BSH) in the RG2 rat glioma model.

Boron neutron capture therapy is a treatment modality for cancer that depends on the specific uptake of boron by the tumor cells. The infiltrative growth of malignant gliomas requires that boron reach and accumulate in migrating cells outside the margin of the tumor; thus, it is important that the biodistribution of new boron compounds is also studied in the surrounding healthy brain tissue. This study is undertaken in the present work, in which the biodistribution and pharmacokinetics of sulfhydryl boron hydride (BSH) and boronated porphyrin (BOPP) in the RG2 rat glioma model are investigated. This model mimics the characteristics of human glioma with cells migrating into the surrounding brain. The animals were infused intravenously with either BSH (25 micrograms or 175 micrograms of boron per gram of body weight) or BOPP (12 micrograms of boron per gram body weight). For the low dose of BSH, the maximum tumor-boron content was 8 ppm at approximately 9 hours after the infusion with a tumor-to-blood ratio of 0.6. At the higher dose, the corresponding figures were 15 ppm after 12 hours with a tumor-to-blood ratio of 0.5. For BOPP, a tumor-boron concentration of 81 ppm was achieved 24 hours after the infusion and sustained in that range for at least 72 hours. The tumor-to-blood ratio at 24 hours was slightly above 6, but continued to increase as the blood was cleared. These results indicate that both compounds are spread into the normal brain tissue following the same pathways as the migrating tumor cells and in this way can be taken up even in distant tumor cell foci.

Animals↗
PubMed1995

[Monitoring neurotoxic effects among laboratory personnel working with organic solvents].

The relationship between organic solvent exposure and central nervous disorders make early detection of neurophysiologic et neuropsychologic alterations in organic solvent exposed workers a priority. Moreover, the variability in the frequency of exposure and the numerous organic solvents encountered in scientific laboratories render the environmental and biological measurements used in medical surveys almost impossible. The present study was undertaken to appreciate the potential neurotoxic effects of organic solvents handling in laboratory employees. Neurophysiological and neuropsychological tests batteries were used with each worker and data were adjusted for potential confounding factors (age and education level). A Principal Components Analysis were performed to reduce the information and the first five factors corresponded to: mood states, speed coding, contrast vision in high frequencies, manual dexterity and contrast vision in low frequencies. These five factors were compared between the daily manipulators of at least one solvent (n = 75) and the non or occasional solvent users (n = 35). The results from this study showed that subjects directly in contact with solvents had a poorer mood state than those who were not or rarely exposed (p < 0.01) and that independently of the "work activity". Mood state impairment in chronic solvent exposed workers has been shown by many authors, with or without psychomotor alteration, and may reflect possible over-exposure. Detection of this instability may lead to early neurophysiologic alteration in exposed workers and permit health services to intervene before the development of irreversible effects.

Adult↗
PubMed1994

Respiration of [14C]alanine by the ectomycorrhizal fungus Paxillus involutus.

The ectomycorrhizal fungus Paxillus involutus efficiently took up exogenously supplied [14C]alanine and rapidly converted it to pyruvate, citrate, succinate, fumarate and to CO2, thus providing direct evidence for the utilisation of alanine as a respiratory substrate. [14C]alanine was further actively metabolised to glutamate, glutamine and aspartate. Exposure to aminooxyacetate completely suppressed 14CO2 evolution and greatly reduced the flow of carbon from [14C]alanine to tricarboxylic acid cycle intermediates and amino acids, suggesting that alanine aminotransferase plays a pivotal role in alanine metabolism in Paxillus involutus.

Agaricales↗
PubMed1994

Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz.

Biological effects of electromagnetic fields (EMF) on the blood-brain barrier (BBB) can be studied in sensitive and specific models. In a previous investigation of the permeability of the blood-brain barrier after exposure to the various EMF-components of proton magnetic resonance imaging (MRI), we found that the exposure to MRI induced leakage of Evans Blue labeled proteins normally not passing the BBB of rats [Salford et al. (1992), in: Resonance Phenomena in Biology, Oxford University Press, pp. 87-91]. In the present investigation we exposed male and female Fischer 344 rats in a transverse electromagnetic transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulse-modulated with repetition rates of 8, 16, 50, and 200 s-1. The specific energy absorption rate (SAR) varied between 0.016 and 5 W/kg. The rats were not anesthetized during the 2-hour exposure. All animals were sacrificed by perfusion-fixation of the brains under chloral hydrate anesthesia about 1 hour after the exposure. The brains were perfused with saline for 3-4 minutes, and thereafter fixed in 4% formaldehyde for 5-6 minutes. Central coronal sections of the brains were dehydrated and embedded in paraffin and sectioned at 5 microns. Albumin and fibrinogen were demonstrated immunohistochemically. The results show albumin leakage in 5 of 62 of the controls and in 56 of 184 of the animals exposed to 915 MHz microwaves. Continuous wave resulted in 14 positive findings of 35, which differ significantly from the controls (P = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1994

An African swine fever virus gene with similarity to the T-lymphocyte surface antigen CD2 mediates hemadsorption.

An open reading frame, LMW8-DR, in the African swine fever virus (ASFV) genome possesses striking similarity to the lymphocyte membrane antigen CD2. All characterized CD2 domains, including the amino-terminal signal sequence, IgV, hinge, IgC2, stalk, transmembrane, and proline-rich carboxy cytoplasmic domains, are highly conserved in the ASFV gene. Critical residues for the binding of the lymphocyte function-associated antigen (LFA-3) and CD59 and for T-cell activation are also partially conserved. LMW8-DR is actively transcribed in ASFV-infected swine macrophages and Vero cells at late times in the infection cycle and Vero and COS cells transiently expressing the LMW8-DR open reading frame hemadsorbed swine red blood cells. The structural and functional similarities of LMW8-DR to CD2, a protein that is involved in cell-cell adhesion and immune response modulation, suggest a possible role in the pathogenesis of ASFV infection.

African Swine Fever Virus↗
PubMed1994

Phenotyping autologous red cells within 1 day after allogeneic blood transfusion by using immunomagnetic isolation of reticulocytes.

BACKGROUND: When a transfused patient develops multiple or weak blood group antibodies, posttransfusion phenotyping is useful in antibody identification. To perform a correct phenotyping after transfusion, isolation of autologous red cells is necessary. However, mature autologous red cells are impossible to separate from their donor counterparts. Since the proportion of autologous reticulocytes compared to donor reticulocytes increases rapidly after transfusion, selective isolation of reticulocytes provides autologous cells for antigen typing. STUDY DESIGN AND METHODS: Extensive phenotyping was performed on red cells from 10 surgical patients before transfusion and on red cells and reticulocytes after the transfusion of 5 or more red cell units. Reticulocytes were isolated by using an antibody against the human transferrin receptor coupled to magnetic beads. RESULTS: The data showed nearly full agreement between pretransfusion phenotyping of red cells and posttransfusion typing of reticulocytes. Correct phenotyping of transferred patients could be obtained 8 to 10 hours after transfusion using isolated reticulocytes. CONCLUSION: This method is helpful in selecting compatible blood when patients have developed antibodies and have an urgent need for further transfusions.

Blood Grouping and Crossmatching↗
PubMed1994

Enhanced boron uptake in RG 2 rat gliomas by electropermeabilization in vivo--a new possibility in boron neutron capture therapy.

Accumulation of boron in tumor tissue is an indispensable requirement for boron neutron capture therapy and it is important that the uptake is as high as possible. In this work we have studied the influence of electropermeabilization in vivo on the uptake of boron in normal and RG 2 glioma bearing Fischer 344 rats. Two different boron compounds, a sulfhydryl boron hydride (BSH) and a boronated porphyrin (BOPP), have been investigated. The rats were infused intravenously during 5 min with 175 micrograms BSH/g body weight or 12 micrograms BOPP/g body weight. Two electrodes were placed 5 mm apart in the brain and electropermeabilization was performed with eight square 400 V pulses at 4 and 7 min after the end of the infusion. After 6 h the animals were killed, and the boron content in the tumors and the surrounding brain was measured with neutron-activated autoradiography. In electropermeabilized healthy animals the BOPP uptake was low and limited to the electrode lesions, whereas BSH was spread extensively throughout the hemisphere. Rats with gliomas showed doubled (BOPP) to 10-fold (BSH) uptake of boron in the tumor when electropermeabilization was performed as compared with untreated animals. We conclude that electropermeabilization in the future may provide an interesting possibility to increase the uptake of certain boron compounds before neutron capture therapy.

Animals↗
PubMed1994

Chlorpromazine in combination with nitrosourea inhibits experimental glioma growth.

Modern cancer therapy has improved the prognosis for several tumour types. This, however, does not apply to the largest group of brain tumours, the malignant astrocytomas grades III-IV. Hence, there is need for new ideas to improve treatment. Ca2+ and the Ca(2+)-binding protein calmodulin have been shown to be involved in the processes conferring stability to DNA in proliferating neoplastic cells. We have combined the calmodulin-inhibiting neuroleptic drug chlorpromazine (CPZ), with the anti-neoplastic drug 1,3-bis(2-chloroethyl-1)-nitrosourea (BCNU) in a treatment regime for rats with glioma cells implanted in the brain. A highly significant inhibiting effect upon the tumour growth was noticed, not by CPZ or BCNU as single drugs, but with their combination.

Animals↗
PubMed1993

A new brain tumour therapy combining bleomycin with in vivo electropermeabilization.

The potentials of in vivo electropermeabilization in combination with bleomycin in brain tumor treatment have been explored. In the brain of normal Fischer 344 rats, 2 electrodes were placed 5 mm apart. Electropermeabilization was performed with 8 to 12 exponential 400 V pulses with a time constant of 325 microseconds. Some animals were given bleomycin i.v., 1mg/kg b.w., 4 minutes before electric pulses delivery. No adverse effects were recorded during the observation of the animals during the following month. The effect of bleomycin and electropermeabilization upon tumour growth was studied in rats with glioma cells (RG2) implanted in the head of the right caudate nucleus. Treatment was given at different time intervals after the implantation of tumor cells and the effect upon survival was studied. Bleomycin alone did not prolong the survival of the animals. On the contrary, bleomycin plus electropermeabilization on the 10th, 11th or 12th day after inoculation increased the survival time to almost double that of untreated animals. We conclude that this treatment may be of value in brain tumour therapy.

Animals↗
PubMed1993

Joubert syndrome associated with Leber amaurosis and multicystic kidneys.

We describe a boy with manifestations of Joubert syndrome, Leber congenital amaurosis, and multicystic kidneys. In infants with unexplained neonatal tachypnea and late developmental delay, absence or hypoplasia of the cerebellar vermis should be sought. Joubert syndrome probably is an autosomal recessive disorder. In the subsequent pregnancy of the propositus' mother, we were able to make a prenatal diagnosis of Joubert syndrome, one of the first to be reported.

Cerebellum↗
PubMed1993

Genetic characterization of a familial non-specific dementia originating in Jutland, Denmark.

Dementias with non-specific pathological changes are a relatively common but under diagnosed form of presenile dementia. A high proportion of reported cases are familial. We report on molecular genetic findings in the largest known pedigree with this syndrome. We have excluded the mutations known to cause familial prion disease, APP-linked familial Alzheimer's disease and candidate regions for Huntington's disease, other forms of Alzheimer's disease and motor neuron disease. We have demonstrated that familial non-specific dementia is a novel genetic dementia.

Aged↗
PubMed1993

Neutron capture imaging of 10B in tissue specimens.

Boron Neutron Capture Therapy (BNCT) is an attractive concept for radiation treatment of malignant tumours. The patients receive a 10B-carrying compound with selective uptake in tumour cells, after which they are irradiated with epithermal neutrons. Theoretically, the tumour cells are killed by the high-LET particles produces in 10B(n, alpha)7Li reactions inside or close to the cell nucleus, while healthy brain cells with no boron uptake will be spared. In practice, a successful BNCT depends on the actual boron-distribution in the tissue, and consequently a new boron-compound aimed for BNCT must undergo detailed bio-distribution studies before clinical trials. In experimental work there is accordingly a great need for methods for quantitative bio-distribution measurements in tissue samples. In this paper we present an improved technique for neutron activated autoradiography providing quantitative boron images of freeze-sectioned tissue specimens from highly malignant rat brain gliomas. Particular attention has been paid to the correlation with the morphology of the specimens and to the altered self-absorption properties due to freeze-drying. A self-absorption correction factor for tumour tissue has been experimentally determined.

Absorption↗
PubMed1993

Prefrontal neocortical disturbances in mental retardation.

Morphometrical analysis of the frontal lobe neocortex of seven selected cases of mental retardation of unclassified aetiology and pathology, showing mild dysplastic changes of the neocortex on routine workup, were compared with nine normal controls and seven cases with Down's syndrome. In comparison with the normal controls, the group with 'unclassified' mental retardation showed an increased percentage of disoriented pyramidal neurons in layers III and IV-V (8-17%, P < 0.01), an abnormal distribution of small pyramidal cells with a shift from superficial to deeper layers of the prefrontal cortex (P < 0.01), and an increased cortical thickness (+38%, P < 0.05) of Brodmann area 10, as well as a tendency to a decreased gyration of the frontal lobe sulci (-14%, P = 0.18). However, no statistically significant macroscopical differences either in frontal lobe gyration or in the size of the cerebrum and its frontal lobes were found between these two groups. On the other hand, the Down's syndrome group had a significantly decreased gyration (-36%, P < 0.01). These findings may indicate an inhibited and disordered migration of putative small pyramidal neurons in cases of 'unclassified' mental retardation.

Adult↗
PubMed1993

Serological studies on the potential synergism of porcine reproductive and respiratory syndrome virus and influenza-, corona- and paramyxoviruses in the induction of respiratory symptoms in swine.

Sera from 265 finishing pigs belonging to 70 herds, in which severe respiratory disorders were observed, were examined for antibody prevalence to porcine reproductive and respiratory syndrome virus (PRRSV), influenza virus subtypes H3N2 and H1N1, porcine respiratory corona virus (PRCV) and a recently described porcine paramyxovirus (PPMV). By immunoperoxidase-monolayer assay 69.1% of these sera were positive for PRRSV. Hemagglutination inhibiting activity was found in 55.1% of the sera for influenza virus subtype H1N1 (strain A/swine/Arnsberg/1/81). in 51.3% for influenza virus subtype H3N2 (strain A/Hong Kong/1/68) and in 14.3% for PPMV. PRCV specific antibodies, as determined by differential competitive blocking enzyme-linked immunosorbent assay were demonstrated in 192 of 236 (81.3%) sera. In order to reveal associations interspecific coefficients were calculated for antibody prevalence between PRRSV and the other viruses. Positive associations to PRRSV titres were found to PRCV, PPMV and influenza virus subtype H1N1 titres. chi-square analysis showed the statistical significance of associations regarding PRCV and influenza virus subtype H1N1. Depletion of lung macrophages after PRRSV infection is discussed as a possible mechanism for the promotion of secondary infections.

Animals↗
PubMed1993

Vascular dementia: diagnostic criteria for research studies. Report of the NINDS-AIREN International Workshop.

Criteria for the diagnosis of vascular dementia (VaD) that are reliable, valid, and readily applicable in a variety of settings are urgently needed for both clinical and research purposes. To address this need, the Neuroepidemiology Branch of the National Institute of Neurological Disorders and Stroke (NINDS) convened an International Workshop with support from the Association Internationale pour la Recherche et l'Enseignement en Neurosciences (AIREN), resulting in research criteria for the diagnosis of VaD. Compared with other current criteria, these guidelines emphasize (1) the heterogeneity of vascular dementia syndromes and pathologic subtypes including ischemic and hemorrhagic strokes, cerebral hypoxic-ischemic events, and senile leukoencephalopathic lesions; (2) the variability in clinical course, which may be static, remitting, or progressive; (3) specific clinical findings early in the course (eg, gait disorder, incontinence, or mood and personality changes) that support a vascular rather than a degenerative cause; (4) the need to establish a temporal relationship between stroke and dementia onset for a secure diagnosis; (5) the importance of brain imaging to support clinical findings; (6) the value of neuropsychological testing to document impairments in multiple cognitive domains; and (7) a protocol for neuropathologic evaluations and correlative studies of clinical, radiologic, and neuropsychological features. These criteria are intended as a guide for case definition in neuroepidemiologic studies, stratified by levels of certainty (definite, probable, and possible). They await testing and validation and will be revised as more information becomes available.

Brain↗