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C Kopp

Publications and source records attributed to C Kopp.

At least 19 recordsLinked to original sources
PubMed2001

Locomotor activity rhythm in inbred strains of mice: implications for behavioural studies.

Due to the well-known influence of arousal on behavioural responsiveness, this paper focused on the differences in the daily locomotor activity rhythm between inbred strains. The lighting conditions of the environment can provide a regular, defined LD cycle or be constant, e.g. constant dim light or constant darkness. Under a light:dark cycle (daily rhythm) and under free-running conditions, i.e. constant darkness (circadian rhythm), such differences between mouse strains emphasise the relevance of a defined time of day for performing tests in order to obtain reliable behavioural results, and consequently the importance of a well-controlled LD cycle, which constitutes a necessary condition for the stability of daily rhythms. Both the LD cycle in the animal room (during breeding, as well as during the experiments) and the experiment schedule within the LD cycle appear as important factors for a better understanding of behavioural results. This information may be relevant to explain part of the apparently contradictory behavioural results reported in the literature.

Animals↗
PubMed2001

Diazepam-induced changes in sleep: role of the alpha 1 GABA(A) receptor subtype.

Ligands acting at the benzodiazepine (BZ) site of gamma-aminobutyric acid type A (GABA(A)) receptors currently are the most widely used hypnotics. BZs such as diazepam (Dz) potentiate GABA(A) receptor activation. To determine the GABA(A) receptor subtypes that mediate the hypnotic action of Dz wild-type mice and mice that harbor Dz-insensitive alpha1 GABA(A) receptors [alpha1 (H101R) mice] were compared. Sleep latency and the amount of sleep after Dz treatment were not affected by the point mutation. An initial reduction of rapid eye movement (REM) sleep also occurred equally in both genotypes. Furthermore, the Dz-induced changes in the sleep and waking electroencephalogram (EEG) spectra, the increase in power density above 21 Hz in non-REM sleep and waking, and the suppression of slow-wave activity (SWA; EEG power in the 0.75- to 4.0-Hz band) in non-REM sleep were present in both genotypes. Surprisingly, these effects were even more pronounced in alpha1(H101R) mice and sleep continuity was enhanced by Dz only in the mutants. Interestingly, Dz did not affect the initial surge of SWA at the transitions to sleep, indicating that the SWA-generating mechanisms are not impaired by the BZ. We conclude that the REM sleep inhibiting action of Dz and its effect on the EEG spectra in sleep and waking are mediated by GABA(A) receptors other than alpha1, i.e., alpha2, alpha3, or alpha5 GABA(A) receptors. Because alpha1 GABA(A) receptors mediate the sedative action of Dz, our results provide evidence that the hypnotic effect of Dz and its EEG "fingerprint" can be dissociated from its sedative action.

Animals↗
PubMed2001

5-substituted 3,4-dihydro-3-amino-2H-1-benzopyran derivatives: synthesis and interaction with serotoninergic receptors.

A new series of 3,4-dihydro-3-amino-2H-1-benzopyran derivatives (1 and 2) bearing various substituents on the 5-position was successfully prepared via palladium-mediated cross-coupling reactions. Some of the new compounds showed high affinity for 5-HT1A and 5-HT7 receptors. The best affinity for the 5-HT1A and 5-HT7 receptors was obtained for 2b (Ki = 0.3 nM for 5-HT1A and 3.1 nM for 5-HT7). The anxiolytic activity of compound 2b was evaluated.

Animals↗
PubMed2000

Anxiolytic-like properties of melatonin receptor agonists in mice: involvement of mt1 and/or MT2 receptors in the regulation of emotional responsiveness.

The anxiolytic-like properties of melatonin have been established in rodents. The present study investigated the possible involvement of melatonin receptors/binding sites in the regulation of emotional responsiveness in mice, using an mt1/MT2 receptor specific agonist (S 23478) and two specific ligands of MT3 binding sites with agonistic properties (N-acetylserotonin (NAS) and 5-methoxycarbonylamino N-acetyltryptamine (5-MCA-NAT)). We examined the behavioural effects of these compounds in C3H/He mice confronted with two anxiety models: the free-exploratory test, in which C3H/He mice present neophobic reactions ("trait" anxiety), and the light/dark choice test, which is an unconditioned conflict test (inducing "state" anxiety). Melatonin and S 23478 decreased anxious reactions in both the free-exploratory test (5-25 mg/kg) and the light/dark choice test (melatonin: 20 mg/kg; S 23478: 10-20-40 mg/kg). NAS exerted anxiolytic-like effects only at a dose of 35 mg/kg in the free-exploratory test and at a dose of 40 mg/kg in the light/dark choice test. Finally, 5-MCA-NAT was devoid of anxiolytic-like effects in both tests. These results suggest that the anxiolytic properties of melatonin could involve the activation of mt1 and/or MT2 receptors rather than of the MT3 binding site.

Analysis of Variance↗
PubMed2000

Hypoexpression of benzodiazepine receptors in the amygdala of neophobic BALB/c mice compared to C57BL/6 mice.

The distribution of benzodiazepine receptors in the brain of neophobic BALB/c mice was studied by autoradiographic analysis using [3H]-diazepam and compared to that of the same receptors of the "nonemotional" C57BL/6 mice. This technique revealed no significant interstrain difference except for a lower density of diazepam binding sites in the amygdala of BALB/c mice. Therefore, the expression of benzodiazepine receptors in the amygdala of the two strains of mice were quantified by binding studies on brain membranes. The amygdala of BALB/c mice exhibited a fivefold decrease in the density of benzodiazepine receptors compared to C57BL/6 mice. These results suggest that the trait anxiety (neophobia) that characterizes BALB/c mice could be due, at least in part, to a genetic modulation of benzodiazepine receptor expression in the amygdala, a structure known to be strongly involved in fear behavior.

Amygdala↗
PubMed2000

Involvement of sst2 somatostatin receptor in locomotor, exploratory activity and emotional reactivity in mice.

Somatostatin (SRIF) controls many physiological and pathological processes in the central nervous system but the respective roles of the five receptor isotypes (sst1-5) that mediate its effects are yet to be defined. In the present study, we attempted to identify functions of the sst2 receptor using mice with no functional copy of this gene (sst2 KO mice). In contrast with control 129Sv/C57Bl6 mice, sst2 mRNA was no longer detectable in the brain of sst2 KO mice; 125I-labeled Tyr0DTrp8-SRIF14 binding was also greatly reduced in almost all brain structures except for the hippocampal CA1 area, demonstrating that sst2 accounts for most SRIF binding in mouse brain. Invalidation of this subtype generated an increased anxiety-related behaviour in a number of behavioural paradigms, while locomotor and exploratory activity was decreased in stress-inducing situations. No major motor defects could be detected. sst2 KO mice also displayed increased release of pituitary ACTH, a main regulator of the stress response. Thus, somatostatin, via sst2 receptor isotype pathways, appears involved in the modulation of locomotor, exploratory and emotional reactivity in mice.

Adrenocorticotropic Hormone↗
PubMed1999

[Socio-demographic and life-style factors in a Swiss study of HIV non-progression].

OBJECTIVES: The study investigates associations between socio-demographic or lifestyle factors and the progression of HIV. METHODS: We recruited a Swiss cohort (n = 56) of long-term survivors and conducted a cross-sectional study of laboratory data as well as factors concerning socio-demography, life-style, and psychology. On the basis of laboratory results, the cohort was divided into 2 subgroups, non-progressors (n = 31) and slow progressors (n = 25), which were subsequently compared. RESULTS: The comparison of socio-demographic factors showed that non-progressors were younger and had a higher income than slow progressors. Our data do not show an association between lifestyle and disease progression. DISCUSSION: Younger age as a cofactor of non-progression confirms various other studies. The association between income and disease progression, also found in another cohort, cannot be explained by unequal access to therapies since, in accordance with the inclusion criteria, no one in our cohort had received antiretroviral therapies. Further research in this field seems important to determine possible links between socio-economic status and disease progression. The lack of association between disease progression and lifestyle factors such as drug use, physical activity or nutrition is in contrast to a common view of HIV in our study population, but is confirmed by a majority of the research in this field.

Adult↗
PubMed1999

[The first transplantation of a hand in humans. Early results].

The first hand allograft was performed on September 23, 1998. The right distal forearm and hand of a brain dead donor was transplanted to a 48 year old recipient who had undergone a traumatic amputation of the distal third of his right forearm. The donor's arm was irrigated with organ preservation solution (UW) and transported to Lyon in a cool container. Two teams simultaneously dissected the donor's limb and the recipient's stump to identify anatomical structures. Transplantation involved bone fixation, arterial and venous anastomoses, nerve sutures, joining of the muscles and tendons, and skin closure. Immunosuppression consisted of anti-lymphocyte, polyclonal and monoclonal antibodies, tacrolimus, mycophenolic acid, and prednisone. Mild clinical and histological signs of rejection occurred at week 9 after surgery. They disappeared with adjustments of the immunosuppressant doses. Seven months after surgery the patient was in good general condition. Intensive physiotherapy led to satisfactory progress of motor function. Sensory progress is excellent, reaching the fingertips. A longer follow-up is necessary to appreciate the final result. In the absence of further rejection, the functional prognosis of the graft should be similar to that reported after successful autoreconstruction.

Adenosine↗
PubMed1999

Effects of melatonin on neophobic responses in different strains of mice.

Anxiolytic properties of melatonin in rodents had usually been examined in behavioral tests based on stressful situations, i.e., in animal models of "state" anxiety. However, no study reports effects of melatonin on emotionality of rodents submitted to situations devoid of stressful components as in the free-exploratory test, which gives to animals the opportunity to choose freely between familiar and unfamiliar places. This procedure has been proposed as a method for measuring an endogenous form of anxiety called "trait" anxiety. The present study first investigated the effects of melatonin on neophobic responses of male C57BL/6, C3H/He, and BALB/c mice submitted to a free-exploratory test. Results demonstrated that melatonin had no effect in C57BL/6 mice that presented very low neophobic responses, whereas it was effective in reducing neophobia of BALB/c and C3H/He mice that presented, respectively, strong and intermediate avoidance responses towards unfamiliarity. Indeed, mice of both latter strains treated with melatonin made fewer attempts to enter into the unfamiliar compartment, exhibited a lower latency of the first entry into the unfamiliar places, and spent more time in them. Thus, melatonin appeared to be equally effective in reducing "trait" anxiety in both BALB/c and C3H/He mice. Moreover, flumazenil was able to counteract, in a dose-dependent manner, the anxiolytic activity of melatonin in BALB/c, suggesting involvement of central GABAergic system in the pharmacological effects of melatonin.

Animals↗
PubMed1999

Antagonistic effects of S 22153, a new mt1 and MT2 receptor ligand, on the neophobia-reducing properties of melatonin in BALB/c mice.

When exposed to a free-exploratory situation, BALB/c mice are well known to exhibit strong avoidance responses toward unfamiliar places (neophobia). Because melatonin was found to significantly reduce neophobia in BALB/c mice, it seemed interesting to examine potential antagonistic effects of S 22153, a new melatonin mt1 and MT2 receptor ligand, on the neophobia-reducing properties of melatonin in BALB/c mice confronted with the free-exploratory paradigm. S 22153 was able to block, in a dose-dependent manner, the anxiolytic-like properties of melatonin when it was administered 5 min before melatonin. The antagonistic effects of S 22153 persisted when the drug was administered 2 or 4 h before melatonin, and were almost abolished when it was administered 6 h before melatonin. These results suggest that the anxiolytic-like effects of melatonin on the neophobic responses in BALB/c mice are mediated by mt1 and/or MT2 receptors.

Animals↗
PubMed1999

Ciliary body detachment caused by capsule contraction.

A 74-year-old woman developed capsule contraction associated with hypotony and choroidal effusion 18 months after uneventful phacoemulsification with 3-piece poly(methyl methacrylate) intraocular lens implantation. Ultrasound biomicroscopy revealed ciliary body detachment and stretched zonules. A radial neodymium: YAG anterior capsulotomy was performed, resulting in the resolution of the ciliary body detachment and choroidal effusion as well as in normal intraocular pressure over 4 days.

Aged↗
PubMed1999

The effects of melatonin on the behavioural disturbances induced by chronic mild stress in C3H/He mice.

In rodents, exposure to chronic mild stress (CMS) is known to induce unresponsiveness to environmental stimuli, as well as sleep disturbances, suggesting some analogies between this syndrome and human depression. Furthermore, numerous studies reported a decrease in nocturnal melatonin concentration in depressed patients, compared with controls. The present study was conducted to test a possible preventative action of daily treatment with melatonin on behavioural alterations induced in C3H/He mice by CMS exposure. In addition to daily spontaneous locomotor activity and preference for sucrose solution, the emotional behaviour of mice was examined in a stressful situation (light/dark choice test), as well as in a situation devoid of constraining components (free-exploratory paradigm), after three weeks of CMS. The results showed that the behaviour of C3H/He mice was disrupted after CMS. Stressed mice exhibited blunted emotional reactivity in both the light/dark choice test and the free-exploratory situation. While unstressed mice presented no variation in their preference for a sucrose solution, stressed mice presented a decrease in such preference towards the end of the CMS exposure. Furthermore, daily spontaneous locomotor activity of the mice was reduced after CMS. Daily treatment of stressed mice with melatonin was able to prevent several CMS-induced disturbances, except in the light/dark choice test, where melatonin was ineffective. Compared to the effects of 10 mg/kg of fluoxetine, which completely prevented CMS-induced dysregulation of behaviour, melatonin was less effective. The present results support the idea that melatonin may be implicated in an homeostatic system which protects animals from disruptions induced by chronic stress.

Animals↗
PubMed1999

Regulation of emotional behaviour by day length in mice: implication of melatonin.

Pineal melatonin secretion occurs at night in all vertebrates and the duration of its secretion is negatively correlated with day length. As short-day exposure was previously shown to decrease emotional behaviour of mice toward an unfamiliar environment, the present study was designed to determine whether such behavioural changes could be mediated by melatonin. In a first experiment, the effects of a 3-week exposure to various day lengths (18h-6h, 12h-12h and 6h-18h light-dark conditions) on neophobic behaviour (free-exploratory paradigm) were examined in both BALB/c mice, which exhibit a very transitory melatonin peak of low amplitude in a 12h light-12h dark cycle, and C3H/He mice, which present a clear melatonin rise during the night-time. A second experiment was designed to determine if the decrease of emotional reactivity induced by a short-day exposure (6h-18h light-dark cycle during 3 weeks) in C3H/He mice could be counteracted by a daily treatment with a melatonin antagonist, S 22153 (1, 5 and 25 mg/kg/day). The short-day exposure was found to decrease neophobic reactions in both C3H/He and BALB/c mice. In contrast, the long-day exposure enhanced neophobia in C3H/He mice only. S 22153 was found to counteract, in a dose-dependent manner, the anxiolytic-like effects induced by the short-day exposure in C3H/He mice. The present results provide evidence that the modulation of circulating melatonin could be involved in the emotional changes related to day-length variations. Further studies are needed to investigate whether pinealectomy could counteract the photoperiod-related changes in anxiety.

Animals↗
PubMed1999

Clonal infection with Actinobacillus actinomycetemcomitans following periodontal therapy.

Mechanical debridement results in a shift of the bacterial composition in the periodontal pocket on the species level. It is unknown, however, whether a clonal change within a species could lead to the emergence of strains with different levels of virulence. Therefore, in the present study, the genetic variability of Actinobacillus actinomycetemcomitans was assessed and strains identified which were associated with periodontal disease progression following periodontal therapy, i.e., refractory periodontitis. Twenty adult patients with untreated periodontitis and subgingival colonization of A. actinomycetemcomitans were randomly assigned to receive full-mouth scaling alone or scaling with an adjunctive antimicrobial therapy. Both groups received supportive periodontal therapy at 3, 6, 9, 12, 18, and 24 months. Subgingival plaque samples were taken at every visit; venous blood was obtained at 24 months only. A. actinomycetemcomitans isolates were typed by the RAPD method, and antibody reactivity against outer membrane proteins was assessed by immunoblot analysis. Eleven distinct RAPD patterns were found in 18 patients completing the study. All patients harbored only one A. actinomycetemcomitans genotype, and within each patient this genotype persisted throughout the 24-month observation period. No differences in the expression of antibody reactivity against outer membrane proteins were found between strains isolated at baseline and at 24 months. Three genotypes were associated with reduced survival rates of teeth without probing attachment loss of 2 mm or more. The results indicated that (i) most patients harbored only one A. actinomycetemcomitans genotype; (ii) the genotype persisted following therapy; and (iii) only some genotypes were associated with refractory periodontitis.

Adult↗
PubMed1999

[From vestibular nystagmus to the transfer function of the vestibulo-ocular reflex].

A new method for the separation of the two phases of the vestibular nystagmus (slow eye velocity and fast eye velocity) is presented. The aim is to calculate the transfer coefficients of the human vestibulo-ocular reflex (VOR). With a combination of thresholds on the eye velocity and the eye acceleration signals, the different phases of fast eye velocity in the vestibular nystagmus can be located with a good accuracy. So this phases which are not of vestibular origin can be eliminated. The dependence of the transfer function and of the coherence function from the values of the thresholds is studied. This study shows that our method is very robust and that the consequence of the systematic errors occurring with the preceding methods, we have used, is a bad estimation of the gain of the VOR. The values of the coherence function we obtained show that the VOR has a linear behaviour within the range of frequencies we studied (0.01-0.5 Hz).

Electronystagmography↗
PubMed1998

Effects of a daylight cycle reversal on locomotor activity in several inbred strains of mice.

There is some evidence of melatonin implication in the nycthemeral regulation of running activity rhythm in rodents. Because some inbred strains of mice such as C57BL/6 and BALB/c have been generally found to present no nocturnal melatonin peak, in contrast to others such as C3H/He and CBA mice, the aim of this study was to examine the adaptation of daily locomotor activity to a light/dark cycle phase shift in these four strains. An apparatus consisting of two boxes connected by a tunnel was used to record spontaneous locomotor activity, defined as the number of transitions between the two boxes. Locomotor activity was monitored continuously during 3 days before and 14 days after a 12-h phase delay of the light/dark cycle. Results essentially showed that the adaptation of the locomotor activity rhythm to the phase shift was faster in C57BL/6 and BALB/c mice than in C3H/He and CBA mice. This could be related, at least in part, to the differences in melatonin synthesis between the former strains and the latter ones. Although melatonin nocturnal peak is not necessary to a daylight regulation of circadian functions in rodents, it could be considered as an endocrine message that takes part in the anticipation of the following light/dark cycle.

Animals↗