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Biomedical subjects

J Michiels

Publications and source records attributed to J Michiels.

At least 19 recordsLinked to original sources
PubMed1992

Transcription of the Azospirillum brasilense nifH gene is positively regulated by NifA and NtrA and is negatively controlled by the cellular nitrogen status.

The expression of a translational Azospirillum brasilense nifH-uidA fusion was studied in A. brasilense and in Rhizobium meliloti strains with mutations in nifA, ntrA and ntrC. Induction of the fusion was observed in the R. meliloti wild-type and NtrC- strains on incubation under microaerobic conditions but not in the NifA- and NtrA- strains, showing the absolute requirement of both sigma 54 and NifA for activation of the nifH promoter. Histochemical analysis of the root nodules elicited by R. meliloti wild-type showed expression of the fusion in the late symbiotic zone but not in the meristematic and the early symbiotic zones. No induction of the nifH-uidA fusion was observed in the R. meliloti wild-type or NifA- strains incubated aerobically in nitrogen-free medium, indicating that, in contrast to R. meliloti nifH, A. brasilense nifH cannot be activated directly by NtrC. Expression of the nifH gene in A. brasilense only occurs under nitrogen-limiting, microaerobic conditions, suggesting the presence of a nitrogen-dependent control system for nif gene expression.

Azospirillum↗
PubMed1992

Magnetic resonance imaging, microangiography, and histology in a rat model of primary liver cancer.

RATIONALE AND OBJECTIVES: N-nitrosodiethylamine is able to induce various benign and malignant liver lesions in rats with a high success rate and a low mortality rate. It provides a more appropriate model that better simulates the various lesions occurring in patients than the usual model of tumor implantations. METHODS: Hepatic carcinogenesis was induced in 58 Wistar rats using oral N-nitrosodiethylamine. The rats subsequently were studied by liver magnetic resonance imaging (MRI), postmortem microangiography, and histologic examination. RESULTS: Hepatic tumors developed in 57 rats. A wide variety of the tumors in the degree of vascularization, the type of vessels, the areas of intratumoral secretion and necrosis, and the tumor cell differentiation resulted from the tumor model. The authors were able to assess the contribution of the vascular, extravascular, and cellular components in the final pattern of contrast enhancement in MRI. CONCLUSIONS: The N-nitrosoethylamine model for hepatic tumor induction is simple, and provides a more representative range of tumors for experimental evaluation.

Animals↗
PubMed1991

Molecular cloning and nucleotide sequence of the Rhizobium phaseoli recA gene.

A recombinant lambda phage carrying the recA gene of Rhizobium phaseoli was isolated from a R. phaseoli genomic library by complementation of the Fec- phenotype of the recombinant phage in Escherichia coli. When expressed in E. coli, the cloned recA gene was shown to restore resistance to both UV irradiation and the DNA alkylating agent methyl methanesulphonate (MMS). The R. phaseoli recA gene also promoted homologous recombination in E. coli. The cloned recA gene was only weakly inducible in E. coli recA strains by DNA damaging agents. The DNA sequence of the R. phaseoli recA gene was determined and compared with published recA sequences. No LexA-binding site was detected in the R. phaseoli recA upstream region.

Amino Acid Sequence↗
PubMed1990

Phase II study of lomustine, cytarabine, mitoxantrone, and prednisone (CAMP) combination chemotherapy for doxorubicin-resistant intermediate- and high-grade malignant non-Hodgkin's lymphoma.

A phase II study was conducted to evaluate the efficacy and toxicity of lomustine, cytarabine, mitoxantrone and prednisone (CAMP) chemotherapy in doxorubicin-resistant intermediate- and high-grade malignant non-Hodgkin's lymphomas (NHL). Among 30 patients, the complete remission rate was 27% (duration: 10, 16, 22, 35, 35+, 42+, 51+, 55+ months) and the partial remission rate was 20%. Median survival for complete responders was more than 4 years. The best responses were seen in patients with relapsed NHL compared to those with primary refractory NHL. Toxicity was mainly related to myelosuppression. The results suggest that the CAMP schedule can be applied on an outpatient basis with satisfactory efficacy in patients with relapsing intermediate- and high-grade malignant NHL.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Immunoglobulin E in aqueous humour.

The level of immunoglobulin E (IgE) was determined in the aqueous humour (AH) and serum by particle counting immunoassay (limit of sensitivity: 0.2 IU ml-1). This level in the AH was below 0.75 IU ml-1 in case of senile cataract (n = 22) and ranged from this assumed normal value to 550 IU ml-1 in case of uveitis (n = 37), Fuchs' cyclitis (n = 11), intraocular tumour (n = 7) and perforating ocular injury (n = 6). To know whether the IgE increase was related to a possible local production the AH/serum concentration ratio for IgE was calculated and divided by that for albumin. Values higher than 0.60 were considered as suggestive of a local synthesis and were observed in 31 of the 37 samples examined.

Aqueous Humor↗
PubMed1985

[Rehabilitation programs for patients with cochlear implants as a function of acquired experience in logopedics for deaf children].

Rehabilitation of patients after cochlear implant surgery should be planified along the same basic principles as those that have been envolved for the adaptation of patients to a classical hearing aid or acoustic prosthesis. When this is adapted to a patient with a sensorineural hearing loss, the quality of hearing differs from that of normal hearing because the pathological inner ear introduces distorsions. The patient therefore has to be trained to equate the new auditory sensations with those he had previously, which is basically the same situation as with a cochlear implant. Some profoundly or totally deaf patients are fitted with vibro-tactile aids and they also have to be trained to make use of these new sensations in a meaningful way for an aid to speech understanding. For the above reasons the term "cochlear prosthesis" is considered particularly adequate. It also has the advantage of playing down the surgical aspect of this new technique, often overemphasized by the media and creating exaggerated emotional involvement of the patients. If the above facts are recognized, one should entrust the rehabilitation of patients fitted with cochlear prostheses to logopeds (speech therapists) well trained in the habilitation and prosthetic adaptation of profoundly deaf children. Only they have the expertise necessary to devise and apply a program founded upon experience. This will help avoid the pitfalls into which several surgically directed cochlear implant teams are currently falling. One of these is to design a training program in function of the tests meant to measure the patients' new capacities.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1979

[Aicardi's syndrome].

Explore the source record for details and available documents.

Agenesis of Corpus Callosum↗
PubMed1979

Heredoataxia (spinocerebellar degeneration), ERG alterations, temporal aspects.

Electroretinographic recordings with 'implicit time' study of 6 patients with different forms of heredoataxia and without clinical ophthalmologic abnormalities were done. ERG showed diminished photopic amplitude of the 'b' wave with delayed photopic 'implicit time' in the presence of increased scotopic latencies. The retinal temporal dysfunction of the ERG in heredoataxia is probably a constant feature. Because the ERG registration, with amplitude and 'implicit time', is required for precise diagnosis, the constant association between retinal alteration and heredoataxia has probably been missed in the past.

Adolescent↗