Biomedical subjects
Publications and source records attributed to J Michiels.
We report the identification and cloning of Rhizobium leguminosarum biovar phaseoli fixABCX homologous genes and the complete nucleotide sequence of the fixA gene. The corresponding gene product is highly homologous to the Rhizobium meliloti and Azorhizobium caulinodans FixA proteins. Putative NtrA- and NifA-binding sites are identified in the fixA promoter region.
Explore the source record for details and available documents.
OBJECTIVES AND RATIONALE: Negative enhancement of implanted liver tumors has been achieved in preclinical studies on manganese dipyridoxal-diphosphate (Mn-DPDP), a new hepatobiliary specific contrast agent for magnetic resonance imaging (MRI). The authors investigated the effects of Mn-DPDP on primary liver cancer and its possible mechanisms. METHODS: Magnetic resonance imaging was performed in 15 rats with chemically induced hepatocellular carcinoma (HCC) before and after Mn-DPDP injection. Both tumor-liver contrast-to-noise ratio and absolute tumor enhancement were evaluated and compared with the MRI results of a nonspecific contrast agent, gadolinium-DOTA, and correlated with corresponding microangiographic and histologic findings. RESULTS: Mn-DPDP injection led to a persistent positive enhancement in differentiated solid HCCs (22/23) with maximal conspicuity at 24 hours. Undifferentiated HCCs were all delineated by a prompt negative enhancement (20/20) with maximal conspicuity within 30 minutes.
Explore the source record for details and available documents.
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.
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.
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.
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.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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.
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)
Explore the source record for details and available documents.
The authors analyze and compare the teratogenic effects produced on the embryo eyes of rats by Maumee saccharin, by non purified Remsem saccharin and several pollutants. The study has been made on 2708 embryos of rats whose mothers have received per os several pollutants at several rates; 16 diets have been studied. The histological lesions are described: the cataract, the retinal coloboma, the major microphthalmos, the anophthalmos, the presence of aberrant nervous fibers, the anarchic globes. The authors describe the retinal eversion phenomenon in the retinal coloboma as well as its repercussion on the ocular malformations (retinal dysplasia and colobomatous cyst of the orbit). The presence of aberrant nervous fibers inside the retinal coloboma could explain the cases of double papilla, which were observed in clinic. The major microphthalmia are frequent. The serious anophthalmia are explained by an early perturbation of the embryogenesis. The anarchic globes could be interpreted as a form of congenital cystic eye. Under the different pollutants of the saccharin, four of them are more toxic: it is the ortho-sulfobenzoic acid, the para-sulfobenzoic acid, the para-sulfamolybenzoic acid, the para-toluenesulfonamide which communicate the Remsen saccharin its teratogenic effect. On the other hand, the ortho-toluene sulfonamide is without any teratogenic effect. The authors conclude on the necessity of a large purity of the commercial saccharin.
Explore the source record for details and available documents.