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Biomedical subjects

M Meyer

Publications and source records attributed to M Meyer.

At least 793 records · Page 44Linked to original sources
PubMedDate not supplied

GDNF increases the density of cells containing calbindin but not of cells containing calretinin in cultured rat and human fetal nigral tissue.

Among the dopaminergic neurons in substantia nigra pars compacta and in the ventral tegmental area, subpopulations express the calcium-binding proteins calbindin (CB) and calretinin (CR), and the CB-containing neurons are supposed to be less prone to degeneration in Parkinson's disease. Glial cell line-derived neurotrophic factor (GDNF) is a potent survival factor for nigrostriatal dopaminergic neurons. Using free-floating roller-tube (FFRT) cultures derived from fetal rat (E14) ventral mesencephalon we found that GDNF (10 ng/ml) significantly increased the number of surviving tyrosine hydroxylase (TH)-immunoreactive neurons. The possible effects of GDNF treatment on CB-immunoreactive (CB-ir) and CR-ir neurons in such cultures were examined in the present study. The neuronal cell densities were measured by quantifying the numbers of CB-ir and CR-ir neurons in areas of sections through the most extensive parts of the spherical cultures. In 4-day-old and 8-day-old cultures GDNF treatment increased the density of CB-ir neurons by 50% and 59%, respectively. Partial co-existence of TH and CB was shown using the method of double immunolabeling. The density of CR-containing neurons was unaffected by GDNF treatment as confirmed by Western blotting for CR. Parallel effects of GDNF treatment were obtained for cultures of human fetal ventral mesencephalon (8 weeks postconception). In conclusion, our findings identify GDNF as a potent factor for fetal rat and human nigral CB-ir neurons able to promote their survival in culture. Referring to a suggested neuroprotective role of CB, the results may be of relevance in the context of neuronal transplantation of patients suffering from severe Parkinson's disease.

Animals↗
PubMedDate not supplied

Lack of effect of short-term depletion of plasma complement C3 on the survival of syngeneic dopaminergic neurons following grafting into the intact rat striatum.

Metabolically compromised cells may be subject to complement-mediated cytotoxicity. The aim of this study was to clarify to what extent plasma complement C3 might contribute to the low survival (5-20%) of grafted dopaminergic neurons. The survival of intrastriatal cell suspension grafts of syngeneic dopaminergic, tyrosine hydroxylase (TH)-containing neurons was compared in rats subjected to short-term i.v. treatment with 1) cobra venom factor (CVF), or 2) placebo treatment. Depletion of plasma complement C3 by CVF was confirmed by crossed immunoelectrophoresis. With 159 +/- 37 (mean +/- SEM) TH-immunoreactive and 154 + /- 40 TH mRNA-expressing neurons in the CVF-treated rats (n = 9), and 117 +/- 34 TH-immunoreactive and 160 +/- 49 TH mRNA-expressing neurons in placebo rats (n = 6), the CVF treatment did not increase the survival of the grafted dopaminergic neurons. Similarly, CVF had no apparent effect on the astroglial, microglial, or oligodendroglial cell response within and around the graft. The data indicate that depletion of plasma complement C3 at the time of grafting has no effect on the long-term survival of syngeneic ventral mesencephalic dopaminergic neuronal grafts.

Animals↗
PubMedDate not supplied

Computer-aided design of novel siderophores: pyridinochelin.

Pyridinochelin, a novel tetradentate catecholate-type siderophore, has been designed on the basis of the active analog enterobactin and was then synthesized. Growth promotion tests indicate that this synthetic siderophore feeds various pathogenic bacteria most effectively with iron even though it lacks one catecholate group compared to enterobactin. The superposition of the mentioned siderophore structures suggests that the structure of the skeleton connecting the catecholate groups might be an important factor for the iron transport.

Bacteria↗
PubMedDate not supplied

Rebreathing and single breath pulmonary CO diffusing capacity in man at rest and exercise studied by C18O isotope.

The pulmonary diffusing capacity for carbon monoxide, Dco, was estimated in normal subjects, using both a single breath technique (DcoSB) and a rebreathing technique (DcoRB). In order to measure CO by mass spectrometry, the stable isotope C(18)O was used. In three normal subjects Dco was measured at different lung volumes at rest, and at different levels of bicycle exercise. DcoRB was found on the average 30% higher than DcoSB when compared at the same mean lung volume, and both increased slightly during exercise. The advantages and drawbacks of the rebreathing method are critically discussed.

Acetylene↗
PubMedDate not supplied

Cre recombinase expression in cerebellar Purkinje cells.

The cerebellar cortex and its sole output, the Purkinje cell, have been implicated in motor coordination, learning and cognitive functions. Therefore, the ability to generate Purkinje cell-specific mutations in physiologically relevant genes is of particular neurobiological interest. A suitable approach is the Cre/loxP strategy that allows temporally and spatially controlled gene inactivation. Here, we present the characterization of transgenic mouse strains expressing Cre recombinase controlled by the L7/pcp-2 gene. Endogenous L7/pcp-2 protein is expressed exclusively in Purkinje cells and retinal bipolar neurones. Recombination was detected by beta-galactosidase histochemistry in tissues from crosses of the L7/pcp-2:Cre transgenic lines with two different indicator strains, GtROSA26 and ACZL. Purkinje cells in all folia of the cerebellum displayed intense beta-galactosidase staining, whereas only few blue cells were observed in the retina and other parts of the CNS. Thus, these transgenic lines are potentially of great importance for genetic manipulations in cerebellar Purkinje cells.

Animals↗
PubMedDate not supplied

Neural xenotransplantation: pretreatment of porcine embryonic nigral tissue with anti-Gal antibodies and complement is not toxic for the dopaminergic neurons.

The immunogenicity of porcine tissue is a major obstacle to its use as donor material in xenotransplantation for neurodegenerative diseases. We are currently evaluating a novel strategy for reducing the immunogenicity, in which the alpha-galactosyl epitope (Galalpha1,3Galbeta1,4GlcNAc-R) is used as a target for antibody- and complement-mediated removal of microglia. In the present study, our aim was to determine whether a pretreatment with antibodies against the alpha-galactosyl epitope (anti-Gal) and complement would lyse or otherwise damage dopaminergic neurons in porcine embryonic ventral mesencephalon (VM), the donor tissue for treatment of Parkinson's disease by xenotransplantation. Cell suspensions prepared from VM tissue from 27-day-old pig embryos were incubated with anti-Gal, purified from normal human serum by affinity chromatography, or medium only (control), and subsequently with rabbit complement. After these pretreatments, the cell suspensions were transplanted into the right striatum of 14 adult rats (two groups of 7 animals). The animals were sacrificed 20 days after transplantation, the brains were processed for histology, and the sections were stained for Nissl substance, porcine neurofilament, tyrosine hydroxylase, and rat CD45 to determine graft volume, presence of porcine neurons, content of dopaminergic cells, and leukocyte infiltration, respectively. The VM tissue pretreated with anti-Gal and complement gave rise to dopaminergic grafts that were indistinguishable from those derived from VM tissue given the control pretreatment. In 5 of the 14 animals, the grafts were infiltrated by host leukocytes, but in two of these recipients, the infiltration was only minimal. We conclude that anti-Gal and complement can be applied to porcine embryonic VM tissue without damaging the dopaminergic neurons and their precursors.

Animals↗
PubMedDate not supplied

Integrating ophthalmological and optometric services in a VA hospital program.

Basic eye care has been available at the Veterans Administration Medical Center (VAMC), Northport, NY, for the past 20 years. The demand for these services increased as the mission of this medical center was broadened to include major medical and surgery services. Increased migration of veterans to Long Island and their subsequent aging further increased the demand for eye-vision care. Originally, primary eye-vision care was provided independently by optometry and ophthalmology services. There was unnecessary duplication of equipment and inappropriate utilization of providers. Consequently, the services provided were quite limited in scope and sophistication. Both patients and providers became disenchanted with this practice mode. In December 1983, the administration of the Northport VAMC approved the establishment of a coordinated eye-vision care program that integrates ophthalmological and optometric services in a matrix structure. Since the program became operational in April 1984, patient satisfaction has increased, the working relationships between optometrists and ophthalmologists have improved, the ophthalmology residency program has been upgraded, and the combined staff productivity has increased.

Consumer Behavior↗
PubMedDate not supplied

[Short-term outcome of infants hospitalized for an attack of acute bronchiolitis].

The authors report the clinical, biological, radiological findings of 109 infants hospitalised for acute bronchiolitis. A prospective study was possible in 74 of them with an average of follow up of 18 months. After the admission, 31% were asymptomatic, 56% suffered at least one or several episode of wheezing, 13% have recurrent or chronic bronchopulmonary symptoms including cough and airway obstruction. Three points appeared determinant to predict recurrent wheezing: the rate of IgE, a familial history of atopy, and radiological pulmonary hyperexpansion. There was no statistic difference of evolution between the infants with wheezing at the admission and the others. The main prospective studies were analysed for discussion of the prognostic problems.

Acute Disease↗
PubMedDate not supplied

[Treatment of acute bronchiolitis in infants by oral suspension theophylline. Double-blind study in 62 children].

The present study reviews 62 children who where admitted to the department of pediatrics for acute bronchiolitis. We adopted the following therapeutic protocol: treatments were applied randomly and we administered a fast action theophylline solution (Theophylline Bruneau R) or a placebo solution every six hours by oral route or stomach probe at 10 mg/kg between 2 and 6 months, 12 mg/kg between 6 and 12 months and 16 mg/kg between 12 and 24 months. Evaluations of theophylline levels were systematically carried out (immunoenzymatic method) for every infant on day 1, day 3, and day 4 two hours after morning administration and the results studied to see if any changes were necessary. This treatment was well tolerated. Statistical analysis was performed before removal of blind. The homogeneity of the two groups was respected if we considered ages (placebo group: 7.1 months +/- 1.0, theophylline group: 5.6 months +/- 0.6), the initial seriousness as evidenced by hypoxemia (placebo group 61 +/- 2 Torr, theophylline group: 58 +/- 3 Torr) hypercapnia (placebo group: 37.8 +/- 1.0, theophylline group: 35.5 +/- 2) and chest retractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMedDate not supplied

[Segmental dilatation of the small intestine in a 10-year-old child].

Segmental dilatation of the small bowel is a rare disease. Formed during the first year of life, it could be due to a malformation or a subacute intestinal ischemia sometimes accompanying a deterioration of the myenteric plexus. The discovery of a dilated ileum in a 10 year old healthy child suggests that the anterior pathogenic hypothesis are invalid, especially because the anatomical study does not find any muscular or neurological deterioration. We may regret not to have measured the tissular V.I.P. which could perhaps have helped in the comprehension of the etiology of this disease.

Child↗
PubMedDate not supplied

[Gastric tumor in children. Apropos of 3 cases].

Gastric tumours are exceptional in children and are usually discovered due to digestive tract bleeding or after palpation of a mass in the abdomen. Appropriate exploratory techniques are need to correctly localize the lesions in the stomach. Nevertheless, the absence of any particular signs can mask the polymorphic nature of the lesions that can only be determined by pathologic examinations. The extent of the surgical exeresis and prognosis depend on the nature of the pathological process.

Adolescent↗