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  • 1
    ISSN: 1432-0983
    Keywords: Key words Mitochondrial DNA ; Mitochondrial transcription ; Heteroplasmy ; Drosophila subobscura
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eighty percent of DNA molecules are deleted in the mitochondrial population of an adult mutant strain of D. subobscura. Both intact and deleted genomes are autonomous monomers. The heteroplasmy level, which is lower in germ tissue, increases from the oocytes (60%) to the third larval instar (83%), and is then maintained throughout the life of the fly. The mtDNA/nuclear DNA ratio is on average two-times greater in the heteroplasmic strain than in the wild-type strain, irrespective of the stage, but the cellular content of mitochondria is elevated only in the embryos and pupae of the mutant strain. The steady state concentrations (SSCs) of the transcripts affected by the deletion are greatly reduced at the larval and adult stages, and less so at the pupal stage of the mutant strain compared with the wild-type. The SSCs of these transcripts are identical in the two strains at the embryonic stage. The fusion transcript, indicating that the deleted genome is expressed, was detected at all stages. The mechanisms involved in the changes in the heteroplasmy level during the course of development and in its maintenance from the third larval instar onwards are discussed.
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  • 2
    ISSN: 1432-1106
    Keywords: Key words Omnipause neurons ; OPN ; Saccade ; Gaze shift ; Tracking ; Perisaccadic drifts ; Moving target ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Pontine omnipause neurons (OPNs) have so far been considered as forming a homogeneous group of neurons whose tonic firing stops during the duration of saccades, when the head is immobilized. In cats, they pause for the total duration of gaze shifts, when the head is free to move. In the present study, carried out on alert cats with fixed heads, we present observations made during self-initiated saccades and during tracking of a moving target which show that the OPN population is not homogeneous. Of the 76 OPNs we identified, 39 were found to have characteristics similar to those of previously described neurons, ”saccade” (S-) OPNs: (1) the durations of their pauses were significantly correlated with the durations of saccades; (2) the discharge ceased shortly before saccade onset and resumed before saccade end; (3) visual responses to target motion were excitatory; and (4) during tracking, S-OPNs interrupted the discharge for the duration of saccades and resumed firing during perisaccadic ”drifts”. However, the characteristics of 37 neurons (”complex” (C-) OPNs) were different: (1) the pause duration was not correlated with the duration of self-initiated saccades; (2) time lead of pause onsets relative to saccades was, on average, longer than in the group of S-OPNs, and firing resumed after the saccade end; (3) visual target motion suppressed tonic discharges; and (4) during tracking, firing was interrupted for the total duration of gaze shifts, including not only saccades but also perisaccadic ”drifts”. We conclude that cat OPNs can be subdivided into two main groups. The first comprises neurons whose firing patterns are compatible with gating individual saccades (”saccade” OPNs). The second group consists of ”complex” OPNs whose firing characteristics are appropriate to gate total gaze displacements rather than individual saccades. The function of these neurons may be to disinhibit pontobulbar circuits participating in the generation of saccade sequences and associated perisaccadic drifts.
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  • 3
    ISSN: 1432-1106
    Keywords: Muscle spindles ; Skeletofusimotor efferents ; \ Innervation ; Glycogen depletion ; Primate motor control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A total of ten a motor axons which innervated the peroneus brevis muscle were isolated in two cynomolgus monkeys. In each experiment, the isolated α axons were stimulated collectively to deplete glycogen from their muscle units. The muscle was then frozen quickly, cut serially, and stained for glycogen. Of the 52 muscle spindles that were examined, zones of glycogen depletion were found in the intrafusal fibres of 32 spindles. The glycogen-depleted motor units included both fast-twitch and slow-twitch types. Depleted zones were observed in all three types of intrafusal muscle fibres. It was concluded that skeletofusimotor (β) efferents were among the stimulated motor axons. This finding constitutes the first anatomical evidence for the existence of β innervation in the primate.
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  • 4
    ISSN: 1432-1041
    Keywords: pentoxifylline ; diabetes (Type I) ; erythrocytes ; membrane fluidity ; fluorescence polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Erythrocytes from diabetic patients show abnormal rheology. Pentoxifylline, a methylxanthine, improves the abnormal deformability of diabetic erythrocytes, but its mechanism of action remains unclear. We have studied the effect of pentoxifylline on the lipid order of erythrocyte membranes from controls and patients with Type I diabetes. We studied the structural organization of membrane lipids in individual erythrocyte ghosts by fluorescence polarization using a cell sorter. Fluorescence polarization values (P) for 17 controls (P=0.244) and 20 diabetic patients (P=0.215) were significantly different. Pentoxifylline added in vitro had no effect on normal membranes, but significantly increased at 10−5 mol·l−1 (P=0.233), and normalized at 10−4 mol·l−1 (P=0.243), the P value of membrane ghosts from diabetics.
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  • 5
    ISSN: 1432-1041
    Keywords: Dextromethorphan ; ELISA ; polymorphism ; population study ; French Caucasians
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Simple, sensitive and selective enzyme immunoassays (ELISA) for monitoring urinary dextromethorphan and its major metabolite, dextrorphan, were developed. Dextromethorphan and dextrorphan hemisuccinates were linked to bovine serum albumin and specific antisera against each immunogen were raised in rabbits. The sensitivity of the ELISA was high (limit of detection 740 and 600 pg·ml−1 for dextromethorphan and dextrorphan, respectively). Intra- and interassay variation was 〈10%, and cross-reactivity between the two compounds was 〈1%. The ELISA was employed to phenotype 216 French subjects. The frequency of poor metabolizers was 5.1%.
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  • 6
    ISSN: 1432-1041
    Keywords: Carbamazepine ; Saliva ; Mania ; Carbamazepine epoxide ; drug concentration ; Concentration-response relationship ; therapeutic monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The study was designed to investigate the antimanic profile of carbamazepine as a first-line drug in affective or schizoaffective disorders, to correlate the clinical efficacy with the plasma level of carbamazepine and its 10,11-epoxide metabolite, and to test the potential value of monitoring the salivary level. It was administered alone for 3 weeks to 21 acute manic inpatients. During the first week, the dosage was rapidly increased to 800 mg/day in order to produce steady-state plasma levels of carbamazepine on Day 7. The individual dose was then adjusted to maintain the therapeutic range of 8–12 mg/l. Plasma and saliva levels of the drug and its metabolite, as well as clinical status were assessed weekly. Overall, there was 62% globally improved patients and 77% in affective disorders. The improvement of manic symptoms was significantly lower in schizoaffective than in affective disorders, whereas the dropout rate and the need for antipsychotic medication was higher in the former group. The antimanic response was significantly correlated with the plasma levels both of carbamazepine and its epoxide metabolite, with a time-lag consistent with a delayed drug effect. Drug and metabolite concentrations in saliva were close to their plasma free fraction and were strongly correlated with their plasma levels, suggesting the potential value of salivary drug monitoring.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-1068
    Keywords: Cementless ; Hip prosthesis ; Hydroxyapatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Careful analysis of total hip arthroplasty failures including data from biomechanical studies of normal and prosthetic hips, and histological investigation, leads to the conclusion that femoral stem failure is mainly due to inadequate transfer of load from the implant to cortical bone. The long term success of femoral stem implantation requires stable fixation. Primary stability relies on the shape and contour of the implant, - secondary stability relies on the area and type of the surface allowing bony ingrowth into the prosthesis without fibrous interposition and allowing the development of early bony trabecular bridging between implant and cortex. Long term stability is related to the mechanical properties of the metal and shape of the implant allowing optimal transfer of loads between bone and implant. The PRA femoral stem fulfils these requirements: its large proximal part fills the upper femur, avoiding distal migration by its shape and providing excellent resistance to rotational and torsional forces due to its trapezoidal cross-section. Longitudinal grooves and Hydroxyapatite coating of this large surface area allows rapid bony ingrowth. The progressive tapering of the distal part which is not coated, decreases its mechanical influence, so that most of the load transfer occurs at the proximal half of the stem. The excellent clinical and radiological results of the 76 implants performed between October 1988 and January 1992 support the theoretical advantages.
    Notes: Résumé Les échecs des implants fémoraux relèvent en très grande majorité de causes mécaniques. La conception de l'implant fémoral PRA exploite l'analyse des échecs observés et publiés, les études biomécaniques, les données histologiques pour satisfaire aux trois impératifs de la stabilité: Stabilité Primaire liée à la forme et aux reliefs de l'implant, Stabilité Secondaire liée à l'état et à l'étendue de sa surface, Stabilité Définitive, garantie par le transfert harmonieux des contraintes entre la tige prothétique et l'os. Implant en alliage de titane (Ti6Al4V), réalisant un bon remplissage et une surface développée maximale de contact os-implant dans la région métaphysaire, la tige PRA est progressivement réduite dans sa portion diaphysaire. Le revêtement de la portion métaphysaire la plus significative sur le plan mécanique par l'hydroxyapatite de calcium entraîne sa fixation rapide par adaptation osseuse sans interposition fibreuse, et le développement précoce d'un pontage trabéculaire osseux entre l'implant et la corticale. La qualité des résultats cliniques et radiologiques obtenus au cours des trois premières années d'implantation confirme le bien-fondé des principes biomécaniques et biologiques retenus dans sa conception.
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  • 8
    ISSN: 1432-1076
    Keywords: Chromosome 21 ; Tetrasomy ; Translocation ; Mosaicism ; Malformations ; Isochromosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 5-year-old boy with severe mental handicap, dysmorphic stigmata and a tetrasomy 21 in fibroblasts is reported. Blood lymphocytes of the patient have a normal karyotype. The origin of this tetrasomy 21 mosaicism is discussed.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Human genetics 〈Berlin〉 36 (1977), S. 129-141 
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Five new cases are added to the single published instance of Yq to Xp translocation (Xt) in man. It is shown that the anomaly can occur as a mutational event during meiosis, and can be inherited from a parent, but also that it can arise in a 47,XXY embryo. In individuals with 46,XXt karyotype the gonadal development, sexual differentiation, gonadal function and fertility are within the range of normal females. They do not present overt or discrete sings of virilisation. However, somatic stigmata, and more specifically short stature, are present in all patients. There is no uniform pattern of Xt inactivation which varies from random to apparently preferential inactivation. This phenomenon may be important for the better understanding of X-inactivation which for the Xt the authors believe is random but followed by differential proliferation of the resulting two types of cells.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Human genetics 〈Berlin〉 50 (1979), S. 105-106 
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A patient with primary thrombocytosis was found to present an acquired deletion of the long arm of chromosome 21 (21q-). A similar observation reported in the literature is hereby confirmed.
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