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Biomedical subjects

M Hazen

Publications and source records attributed to M Hazen.

At least 19 recordsLinked to original sources
PubMed2002

Effects of flavophospholipol on resistance in fecal Escherichia coli and enterococci of fattening pigs.

A "plasmid-curing effect" of multiresistant Escherichia coli by flavophospholipol, an antibiotic used as an antimicrobial growth promoter (AMGP) in animal feeds, has been reported to occur in vitro and in vivo under experimental conditions. In this study, the effect of flavophospholipol under field conditions was studied. The prevalence and degree (proportion of resistant strains to the total numbers present per gram of feces) of resistance of indicator bacteria, E. coli and enterococci, was determined in fecal samples from three groups of pigs that were fed a commercial finisher feed without any AMGP. Group A was the negative control group without any AMGP, group B received the same feed with 9 mg of flavophospholipol/kg of feed (study group), and group C received the same feed with 15 mg of avoparcin/kg (positive control). Fecal samples from each pig were collected at the start and at the end of the study and assessed for the prevalence and degree of resistance against antibiotics commonly used either for therapy in pig medicine or as an AMGP. Before the start of the study, all pigs were colonized with multiresistant E. coli by mixing three resistant pig isolates through their feed after disturbance of the colonization resistance of the intestinal flora by a 3-day course of lincomycin and spectinomycin. At the end of the study, the overall prevalence and degree of resistance of E. coli in the fecal flora had increased significantly in groups A and C but remained at the same level as at the start of the study in group B. The prevalence of vancomycin resistance was 44 and 41% in groups A and B, respectively, but only very low numbers of vancomycin-resistant enterococci (VRE) per gram of feces were found. In the avoparcin-fed group, the prevalence was 72%, and in 57% of the samples, more than 50% of all enterococci present were vancomycin resistant. The prevalence of resistant Enterococcus faecalis increased only in the flavophospholipol-exposed group, from 23% before the start of the study to 43% at the end of the study. It was concluded that flavophospholipol effectively suppressed the augmentation and dissemination of multiresistant E. coli in the intestinal flora of fattening pigs. Avoparcin use strongly selected for VRE carriage and excretion. Therefore, as neither flavophospholipol nor any related molecule is used therapeutically, no cross-resistance with therapeutic antibiotics exists and no transmissible resistance has been shown; the major decrease in resistance in intestinal E. coli of flavophospholipol-fed animals seemed to outweigh the small increase in the risk of transfer of flavophospholipol-resistant E. faecalis from animals to humans via the food chain.

Animal Feed↗
PubMed2000

Fast synaptic fatigue in shibire mutants reveals a rapid requirement for dynamin in synaptic vesicle membrane trafficking.

The GTPase dynamin is involved in endocytosis in many cell types, as first revealed by temperature-sensitive paralytic mutations in the Drosophila dynamin gene, shibire (shi), which disrupt synaptic vesicle endocytosis and deplete synaptic terminals of vesicles. Here we report that shi synapses exhibit a fast synaptic fatigue phenotype within 20 ms of repetitive stimulation, which cannot be explained by vesicle depletion, as we confirmed by electron microscopy. These results suggest that, in addition to its well-characterized role in synaptic vesicle recycling, dynamin may be required for short-term maintenance of the readily releasable pool of synaptic vesicles.

Animals↗
PubMed1995

The sterilization of honey with cobalt 60 gamma radiation: a study of honey spiked with spores of Clostridium botulinum and Bacillus subtilis.

Unprocessed honey is a recognized wound-healing remedy. However, to make clinical use of honey acceptable, it should be sterile. To find the lowest dose of irradiation needed for sterilization, six batches of honey (a-f) were gamma irradiated with 6, 12, 18, 22 and 25 kGy Cobalt-60. After a dose of 25 kGy the antibacterial activity was not altered. Presumably glucose oxidase (EC 1.1.3.4), which produces hydrogen peroxide, is not easily damaged by irradiation. Amylase activity on the other hand was significantly reduced to 19%, 19%, 21%, 22%, 43% in batches a), b), c), d) and f) respectively, whereas no decrease was observed in batch e). All batches spiked with approximately 10(6) spores from Cl. botulinum or B. subtilis per 50 g honey proved to be sterile after irradiation with a dose of 25 kGy. Honey was also spiked with Cl. botulinum at up to 5000 spores per 50 g honey, which is the upper limit of natural contamination. The sterilizing dose in this case was 18 kGy.

Anti-Bacterial Agents↗
PubMed1992

Chromatographic methods for the determination of toxicants in faeces.

Modern chromatographic techniques and their application in the determination of toxic compounds in faeces are reviewed. Faecal analysis may be of importance in toxicokinetic studies of xenobiotics in order to determine factors such as metabolism, body burden and major routes of elimination. Compounds of interest include various food constituents, drugs and occupational or environmental factors. Further, various mutagenic or carcinogenic compounds which are excreted by faeces have been indicated to represent risk factors for colorectal cancer. In this context, the chromatographic determination of the endogenously generated fecapentaenes and bile acids, both postulated etiological factors in colorectal carcinogenesis, is reviewed. For fecapentaene determination, several high-performance liquid chromatographic (HPLC) methods are available; however, the applicability of some of these methods is limited owing to insufficient separation of various isomeric forms or discrimination between fecapentaenes and their precursors. For the determination of bile acids in faeces, many chromatographic procedures have been reported, and the characteristics of the most relevant methods are compared and discussed. It is concluded that separation by gas chromatography (GC) in combination with mass spectrometry provides the highest selectivity and sensitivity. A relatively rapid alternative analysis for the determination of total and aqueous faecal bile acids is proposed. Further, methods for the determination of polycyclic aromatic hydrocarbons (PAHs) are reviewed. Although the use of radiolabelled PAHs in animal studies has many advantages, it cannot be applied for human biological monitoring and HPLC and GC provide sensitive alternatives. An HPLC method for the determination of non-metabolized PAHs in faeces is described.

Carcinogens↗
PubMed1992

[Occurrence of post-traumatic temporo-mandibular ankylosis. Trial of classification of anatomo-pathologic lesions].

According to the authors, who have an 18-year experience, the treatment of temporomandibular ankylosis in children consists in the resection of the ankylosis block and of the corresponding neck of the condyle, along with the preservation of the capsule and articular disk and a dynamic blockade with the mouth open until the mandibular condyle is completely reconstructed. After witnessing the constitution of ankylosis in a child who was initially examined 3 weeks after the trauma, we were able to carry out a thorough clinicopathological examination of the areas of tissue characterizing incipient ankylosis, both in the condylar cartilage and in the underlying bone. The initial stage produces the progressive emergence of the bony surfaces, which then bear no cartilage. This is osteogenesis as well as cartilage resorption, as evidenced by the presence of neoformed Haversian canals at that level. This is a formal argument in favor of a systematic dynamic blockade with the mouth open in all cases of fresh condylar surface and the menisceal surface of the joint is the best way to prevent ankylosis or malunion.

Ankylosis↗
PubMed1991

[Dynamic bite block in fractures of the mandibular condyle and following surgery of temporomandibular ankylosis in children].

Early mobilization is the rule in cases of fracture and temporomandibular joint surgery. When prematurely discontinued, it may sometimes prove insufficient to prevent temporomandibular ankylosis in the child. Blockade in the open-mouth position is in keeping with an important general orthopedic rule, i.e., immobilization of joint fractures in position of function (ankylosis is loss of function, and is reflected by the child's inability or limited capacity to open his/her mouth). Continued night wear of re-habilitation devices, once consolidation is acquired, affords active joint mobilization during meals that is sufficient owing to the strength of the elevator muscles (five times than of the depressors).

Ankylosis↗
PubMed1991

[Lingual-mandibular remodeling resection in prognathism].

The combination of --hypoplastic upper jaw, with narrow soft palate, --glossoptosis (or low, propulsive tongue), associated with protrusion of lower jaw, is well known. Early, exclusively orthopedic management combines enlargement of the superior arcade; functional/postural re-education of the tongue. Surgical management comes in later; it associates modeling resection of the tongue intended to position the tongue against the palate, with Chevron's mandibular resection, suppression of the first premolar, and salvaging the mental nerve. This type of osteotomy is indicated whenever a 6 to 8 mm mandibular retrusion is required. Fixation is monomaxillar, via extemporaneous splinting, associated with low external cortical osteosynthesis. The latter allows for gain of motor activity as early as the second day post-surgery.

Adolescent↗
PubMed1988

[Genioplasty in adolescence].

Different possible types of genioplasty in adolescence are envisaged: pure subtraction, conjugated subtraction, apposition, addition and in particular transfer for correction of the facial asymmetry of temporomandibular ankylosis sequelae. It is difficult to predict results and it is necessary to remain within a known framework in which esthetic and psychologic demands must occupy a very important place.

Adolescent↗
PubMed1986

[Capdepont dysplasia and vertical excess of the lower half of the face. Genetic syndrome or fortuitous association?].

The study of an Algerian family revealed that four of the seven children presented dentinogenesis imperfecta associated with an anomaly of the facial skeleton (maxillary hypoplasia, anterior expansion of skeletal origin due to widening of the angle of the gonion). This type of association and its very unusual type of transmission (no doubt recessive) leads to a discussion of genetic mechanisms of these syndromes.

Child↗
PubMed1986

[Facial profile--psychological profile].

The morphological organisation of the face reflects the individual's social context and heredity and also reveal certain personality traits. Emotional facial expression is a very special form of communication. This functional and behavioural dynamic leads to the formation of a certain anatomical structure as a result of repetitive functions. The psychological examination of nineteen retrognathic patients and seven prognathic patients revealed the timid, inhibited of even anxious personality of the first group of patients in contrast with the extraverted and frequently aggressive personality of prognathic patients.

Facial Expression↗
PubMed1986

[Fibromucosal nodular lesions in newborn infants].

The authors present the case of a neonate with four nodular lesions of the gingival fibromucosal with different histological types: two lesions consisted of epithelial inclusions and the other two were alveolar lymphangiomas. This case emphasises the importance of the histological examination in the diagnosis of clinically identical lesions.

Gingival Neoplasms↗
PubMed1981

The site of integration of the herpes simplex virus type 1 thymidine kinase gene in human cells transformed by an HSV-1 DNA fragment.

To analyze the site of integration of the herpes simplex virus type I (HSV-I) thymidine kinase (TK) gene in biochemically transformed human cells, TK-HeLa-(BU25) cells were transformed to the TK+ phenotype by a cloned, 2 kbp Pvull fragment of HSV-I DNA. The transformed cells [HeLa(BU25)/TF pAGO PP3] were fused with mouse LM(TK-) cells, and human-mouse somatic cell hybrid clones (LH PP3 clones 1, 2, 3, 5 and 6) were isolated in HATG-ouabain selective medium. The HeLa(BU25)/TF pAGO PP3 cells and the LH PP3 hybrid clones expressed HSV-I specific TK activity and a herpesvirus-associated nuclear antigen, and contained herpesvirus nucleotide sequences. Molecular hybridization experiments were carried out to map the HSV-I and flanking cellular nucleotide sequences in the biochemically transformed cells. These experiments demonstrated that the HSV-I nucleotide sequences were integrated at a single site, and that the same cellular nucleotide sequences flanked the viral DNA in transformed HeLa(BU25)/TF pAGO PP3 and LH PP3 clone 5 cells. TK- revertant subclones isolated by growing the LH PP3 clone 5 cells in BrdUrd (and diphtheria toxin) failed to form colonies in HATG medium, but retained HSV-I nucleotide sequences. Isozyme analyses on 21 gene-enzyme systems representing 21 human chromosomes revealed that all of the LH PP3 clonal lines expressed human hexosaminidase B, which has been assigned to chromosome 5, and all were sensitive to diphtheria toxin, which is also a marker for chromosome 5. Chromosome analyses showed that chromosome 5 was the nly human chromosome present in mitoses of LH PP3 clone 5 cells and that human chromosome 5 was present in most of the mitoses of LH PP3 clone 1, 2, 3, and 6 cells. The latter clones also contained 1 or 2 additional human chromosomes in some of the cells. As expected from the molecular hybridization analyses, TK- revertants of LH PP3 clone 5 cells retained portions of chromosome 5 and expressed human hexosaminidase B. The results indicate that HSV-I nucleotide sequences were stably integrated in the biochemically transformed cells, most likely in human chromosome 5.

Animals↗