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Biomedical subjects

C Heitz

Publications and source records attributed to C Heitz.

17 recordsLinked to original sources
PubMed2006

Effects of the LactoSorb bioabsorbable plates on the craniofacial development of rabbits: direct morphometric analysis using linear measurements.

The use of plates for the treatment of fractures can affect craniofacial bone development. This study investigated the effect of bioabsorbable plates and titanium microscrews on the growth of the craniofacial skeleton of rabbits (Oryctolagus cuniculus), in the neonatal period. A LactoSorb plate and PROMM titanium microscrews were positioned across the coronal suture in animals in the study group. In the control group, only PROMM titanium microscrews were attached to the cranium. Anteroposterior linear measurements were obtained using 3 different gauging devices: digital precision caliper, EKG caliper and nylon string. Frontal-nasal (FN) distances were statistically different between the left and right side when the digital caliper (P<or=0.01), EKG caliper (P<or=0.01) and nylon string (P<or=0.05) were used. Mean right-side FN distances in the control and study groups were significantly different (P<or=0.05) when measured with the EKG caliper. Normal neonatal craniofacial growth of rabbits was affected by the use of bioabsorbable plates in this study. Further studies should be conducted to investigate whether these plates affect growth in human beings.

Absorbable Implants↗
PubMed2006

Cross-condensation and particle growth in aqueous silane mixtures at low concentration.

We have observed the condensation of a mixture of gamma-glycidoxypropylmethyldiethoxysilane and 3-aminopropyltriethoxysilane in dilute aqueous solutions. NMR and IR spectroscopy have allowed to follow the condensation process in the mixture, which is noticeably enhanced and proceeds faster than for each silane on its own. Cross-condensation between the two silanes was evidenced. When the hydrophilic aminosilane is in excess, the condensation, as evidenced by dynamic light scattering, proceeds toward gel formation because the oligomers formed are essentially hydrophilic. When the more hydrophobic epoxysilane is in excess, oligomer growth proceeds slowly and results in a destabilization of the solution: due to their hydrophobic character, the oligomers formed coalesce suddenly into 200-nm-diameter aggregates. Coatings deposited from such solutions with high epoxysilane content can be used to strengthen glass. We show that the progress of condensation in solution results in a wetting transition during deposition of the silane film on glass by dip coating. The production of increasingly hydrophobic oligomers as the reaction time increases results in adsorption of more hydrophobic aggregates at the surface, which eventually leads to dewetting of the film: in the absence of film, glass strengthening disappears.

Journal Article↗
PubMed2004

[Pharmacists' role in the management of asthma: a survey of 120 pharmacists in Bas-Rhin].

INTRODUCTION: The pharmacist plays an essential role in the management of the asthmatic patients on account of their frequent visits to the pharmacy to obtain their medication. METHODS: In order to evaluate the practice and knowledge of asthma among the pharmacists of the department of Bas-Rhin, 120 pharmacists were selected at random to reply to a standardised questionnaire. RESULTS: The 86 pharmacists who replied to the questionnaire had a good general understanding of asthma and its treatment. However, only 26.4% knew all the criteria of the severity of an attack of asthma. Among the 57 pharmacists who gave a demonstration of the use of inhaler devices, 16.3% showed all the steps in the use of a metered dose aerosol. These results are comparable to those of non-specialist doctors and nurses in whom poor techniques were found in 63-100% and 65-96% respectively. The mean scores of the pharmacists were 10.5/12 (+/- 1.2) steps for metered dose aerosols, 10.4/11 (+/- 1.0) for the Tubuhaler, 9.3/12 (+/- 1.7) for the Autohaler and 8.1/9 (+/- 0.9) for the Volumatic spacer. The asthmatic patient's main expectation of the pharmacist concerned the use of the prescribed systems (87.2%), underlining the lack of information received by the patient at the time of prescription. CONCLUSIONS: An improvement in the knowledge of the signs of severity of asthma and the use of inhaled devices could usefully be one of the objectives in the training of a dispensing pharmacist.

Adult↗
PubMed1993

Dynamics of DNA under pulsed-field gel electrophoresis as analyzed from birefringence rise and decay.

The orientation of DNA induced by electrophoretic transport in agarose gel has been studied by optical birefringence. From its field-free decay, it is clearly demonstrated that the degree of orientation results from two processes: alignment along the electric field (stretching of the end-to-end vector) and elongation of the primitive path in the gel (overstretching). Separation of the two contributions allows the experimental determination of the effective charge per base pair, the gel pore size seen by the reptating molecule, the reptation time, the degree of overstretching and the mean relaxation time of the overstretching. Their field and DNA length dependences compare well with theoretical predictions. Similarly, the time at which overstretching presents an overshoot in the rise of the orientation follows closely the predictions of a model based on the evolution of J-shaped conformations. The recovery of such conformations is studied by a sequence of two pulses with variable delay time. The use of directly measured or extrapolated characteristic times and fields in the design of efficient pulse schemes for pulsed-field gel electrophoresis is emphasized.

Birefringence↗
PubMed1988

Effects of inaktin on calcium metabolism in the rat.

Experiments were designed to investigate further the alterations in calcium metabolism caused by inaktin, a thiobarbiturate that impairs parathyroid hormone action in rats (1981). Treatment with an anesthetic dose of inaktin induced a drop in serum calcium without any variation in immunoreactive parathyroid hormone serum level and slowed body calcium turnover as studied with 45Ca, but was without effect on blood pH or partial pressures of oxygen and carbon dioxide. In contrast, calcium metabolism in rats was unchanged after treatment with an anesthetic dose of pentothal, another thiobarbiturate anesthetic. The effect of inaktin on body calcium turnover was dose-dependent and significant even at non-anesthetic levels. A marked slowing of the fast phenomena accounting for the initial dilution of the tracer in the animal was observed, accompanied by a corresponding decrease in rapid 45Ca uptake into bone, but not other tissues. These results show that inaktin slows calcium turnover, especially the fast renewal of calcium in bone. These effects were not correlated with anesthesia or immobilization, and we suggest that inaktin-induced changes in calcium metabolism involve an impairment of hypocalcemia-induced parathyroid hormone secretion, in addition to the impairment of parathyroid hormone effects previously reported. Furthermore, the present findings suggest that inaktin might be a useful tool for investigation of the rapid mobilization of bone calcium, which is as yet not well understood.

Anesthesia, General↗
PubMed1988

Stereoselective blockade of alpha-adrenoceptors by berbine derivatives.

The effects of the two enantiomers of berbine (5,6,13,13a-tetrahydro-8H-dibenzo[a,g]quinolizine) and of derivatives obtained by introducing various substitutions on aromatic rings were investigated on alpha 1- or alpha 2-adrenoceptor subtypes. Binding studies carried out on rat cerebral cortex membranes using [3H]prazosin or [3H]yohimbine showed that the affinities of the (+) and (-)enantiomers for alpha 1 and alpha 2 binding sites were different and were differently modified by substitutions added to the berbine nucleus, leading to alpha 1- and alpha 2-selective compounds. Experiments performed on the isolated rat aorta and in pithed rats in vivo demonstrated the alpha-blocking property of berbine derivatives and confirmed the stereoselectivity of the effects of the (+) and (-)enantiomers on alpha 1- and alpha 2-adrenoceptor subtypes.

Adrenergic alpha-Antagonists↗
PubMed1986

Alpha-adrenoceptor antagonistic and calcium antagonistic effects of nicergoline in the rat isolated aorta.

The activity of the alpha-adrenoceptor antagonist nicergoline, a molecule composed of two constituent parts, ergoline and bromonicotinic acid, was investigated in the rat isolated aorta. Nicergoline (10 nM-0.1 microM) displaced concentration-effect curves elicited by noradrenaline and phenylephrine to the right and inhibited maximal responses elicited by both alpha-adrenoceptor agonists without significantly affecting prostaglandin F2 alpha-induced contractions. Higher concentrations of nicergoline (1 microM-50 microM) displaced to the right the concentration-effect curves elicited by calcium in a depolarizing medium. This calcium antagonist activity was not shared by either of the constituent parts. Nicergoline 100 microM abolished the 45Ca influx induced into rat aorta by 100 mM K+-containing physiological solution. The selectivity of nicergoline for alpha 1-adrenoceptors seen in binding experiments also depends on the presence of the bromonicotinic moiety of the molecule. It is concluded that nicergoline, but not its substituent parts, displays both alpha 1-adrenoceptor and calcium antagonism. The latter property may account for some of the observed effects of this compound.

Animals↗
PubMed1984

Age-related changes of in vivo beta-adrenergic responsiveness in normotensive and spontaneously hypertensive rats.

The variations of plasma cyclic AMP concentration caused by propranolol and isoproterenol were studied in order to investigate endogenous stimulation and responsiveness of the beta-adrenoceptor-cyclic AMP system in vivo, in 7 and 18 week old unanaesthetized male SHR and WKY. In both age groups, the basal cyclic AMP level was higher in SHR than in controls but was significantly reduced to a comparable value in the two strains after intraperitoneal injection of 2.5 mg X kg-1 propranolol, a dose which markedly depressed or even abolished the effect of isoproterenol. Cumulative dose-response curves of plasma cyclic AMP concentration obtained in another group of rats after successive subcutaneous injections of isoproterenol showed that the ED50 value of this drug was higher in SHR than in WKY and increased in a parallel manner in the two strains between 7 and 18 weeks of age (respectively from 0.21 +/- 0.01 to 0.34 +/- 0.02 mumol X kg-1 in WKY and from 0.32 +/- 0.02 to 0.52 +/- 0.03 mumol X kg-1 in SHR). At the same time blood pressure increased much less markedly in WKY (from 115 +/- 4 to 119 +/- 2 mm Hg) than in SHR (from 134 +/- 3 to 179 +/- 3 mm Hg). Altogether these results show that endogenous beta-adrenergic stimulation of the cyclic AMP system was higher in SHR of both ages in spite of a diminished responsiveness of this system to exogenous isoproterenol.

Aging↗
PubMed1984

Different effects of phenylephrine and clonidine on 86Rb efflux and on contraction in the rat caudal artery.

A large transitory efflux of 86Rb was induced by concentrations of phenylephrine (10(-6) and 10(-4)M) or clonidine (10(-4)M) which were able to produce phasic contraction. By contrast, a lower concentration of clonidine (10(-6) M), which could only induce a slower (tonic) contraction, only produced a weak but sustained 86Rb efflux. These results show qualitative and quantitative differences in the effects of the two alpha-agonists. They further support the view that phasic and tonic alpha-adrenergic responses may be related to different mechanisms.

Animals↗
PubMed1981

Parathyroid hormone effects on calcium metabolism in the rat are impaired by 5-ethyl-5'-(1-methylpropyl)-2-thiobarbiturate (inaktin).

The mechanism by which inaktin, a thiobarbiturate, promotes a moderate drop in serum calcium has been investigated. The effect was cancelled in hypocalcemic parathyroidectomized rats. On the other hand inaktin antagonized the serum calcium raising effects of parathyroid extract in these animals. In rats wit intact parathyroid glands inaktin caused a two-fold increase in urinary calcium excretion and a marked decrease in body and bone calcium turnover (measured with 45 Ca). These results support the view that inaktin impairs the parathyroid hormone effects on calcium metabolism.

Anesthetics↗