PubMed Health⌕ Search

Biomedical subjects

C Kopp

Publications and source records attributed to C Kopp.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1998

Detection of mi transcription factor (MITF) mRNA in a case of myelodysplastic syndrome and bone marrow mastocytosis.

Myelodysplastic syndromes (MDS) may be accompanied by systemic mastocytosis. The mechanisms which play a role in the evolution of mastocytosis, however, are not well understood. We report on a case of refractory and anemia with ringed sideroblasts (RARS), and co-existing bone marrow mastocytosis. Compact mast cell (MC) infiltrates were detected in bone marrow sections by immunohistochemistry using an antibody to tryptase. In addition, the MC were found to express c-kit, the tyrosine kinase receptor for MGF (mast cell growth factor = stem cell factor, SCF). Activating point mutations in the kinase domain of c-kit (often found in mastocytosis) were not detectable. However, the mononuclear cells (MNC) of the bone marrow expressed mRNA specific for MITF, a transcription factor that regulates expression of c-kit and differentiation of MC. Surprisingly, the c-kit ligand SCF was found to augment expression of MITF mRNA in bone marrow MNC. Whether this augmentation represents a general response (preventing loss of growth factor receptor expression during cell maturation) common to all types of hemopoietic progenitors, or is confined to (some forms of) mastocytosis, remains unknown.

Aged↗
PubMed1998

A 6-month comparison between formoterol and salmeterol in patients with reversible obstructive airways disease.

The aim of this randomized, open, parallel group study was to compare the clinical efficacy of formoterol dry powder capsule 12 micrograms b.i.d. and salmeterol dry powder 50 micrograms b.i.d. in the treatment of patients with reversible obstructive airways disease. The 6-month treatment was preceded by a 2 week run-in period. Morning pre-dose peak expiratory flow (PEF) during the last 7 days of treatment was the primary variable. Throughout the study, patients recorded morning and evening pre-dose PEF, use of rescue medication, respiratory symptoms and adverse events. Clinic visits were scheduled at monthly intervals. Of the 482 patients randomized (equal numbers in the two treatment groups), 428 completed the study. Four hundred and twenty-five patients were included in the efficacy analysis for the primary variable. For mean morning pre-dose PEF during the last 7 days of treatment, the 95% confidence interval (CI) for the treatment contrast formoterol minus salmeterol was included entirely in the pre-defined range of equivalence (CI limits = -8.69, +9.841 min-1). This was also the case for the morning PEF during the last week before each clinic visit. For mean evening pre-dose PEF, the estimated treatment contrasts showed a trend towards superiority of formoterol over salmeterol, which became statistically significant at 2, 3 and 4 months (P < 0.05; estimated contrasts 7.27, 10.45 and 10.511 min-1, respectively). No treatment group differences were found in use of rescue medication and respiratory symptom scores. The incidence of adverse events was similar in the two groups. These findings demonstrate that formoterol 12 micrograms b.i.d. and salmeterol 50 micrograms b.i.d., both formulated as dry powders, have similar long-term efficacy and safety profiles in patients with reversible obstructive airways disease.

Administration, Inhalation↗
PubMed1998

Differential effects of systemic metronidazole and amoxicillin on Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in intraoral habitats.

48 adult patients with untreated periodontitis harboring subgingival Actinobacillus actinomycetemcomitans and/or Porphyromonas gingivalis were randomly assigned to receive full mouth scaling alone (control) or scaling with systemic metronidazole plus amoxicillin and supragingivai irrigation with chlorhexidine digluconate (test). Subgingival plaque and swab samples from tongue, tonsils, and buccal mucosa were taken at baseline, 10 days and 3, 6, 9, and 12 months. A. actinomycetemcomitans was detected in the oral cavity, i.e., subgingival plaque and/or mucous membranes, less frequently in test patients compared to controls at 9 and 12 months (p<0.01), whereas, the intraoral detection frequency of P. gingivalis was significantly reduced only 10 days following therapy (p<0.001). At any time after therapy, A. actinomycetemcomitans was not detected intraorally in 5 of 10 (50%) test and 1 of 13 (8%) control patients harboring this pathogen at baseline; P. gingivalis was not detected in only 1 of 18 (6%) test and none of the 17 control patients harboring this pathogen at baseline. Although the data indicated that the assessed antimicrobial therapy may suppress A. actinomycetemcomitans from the entire oral cavity below detectable levels over a minimum of 12 months, P. gingivalis persisted or reoccurred.

Administration, Oral↗
PubMed1998

Pseudorandom rotational stimuli of the vestibulo-ocular reflex in humans: normal values of the transfer function.

Pseudorandom binary rotatory stimulation is used to study the vestibulo-ocular reflex (VeOR) frequency response (from 0.01 to 0.64 Hz). Fifty-two normal subjects volunteered for this test. The transfer function's gain and phase, and the corresponding coherence function between slow phase eye velocity and head velocity were computed. According to the linearity hypothesis, the results match the sinusoidal stimulation studies. In both cases, the variability of the gain was higher than that of the phase shift. Identification of some parameters of the VeOR's mathematical model were performed, using the experimental results.

Adult↗
PubMed1996

Analysis of 21 Stargardt's disease families confirms a major locus on chromosome 1p with evidence for non-allelic heterogeneity in a minority of cases.

BACKGROUND: Autosomal recessive Stargardt's disease is a macular degeneration characterised by a juvenile onset and a rapidly progressive course resulting in an atrophic macular area typically surrounded by yellowish retinal flecks. METHOD: The disease locus has previously been assigned to markers from chromosome 1p21-p13 by genetic linkage analysis in eight multiplex Stargardt's disease families. RESULTS: In an extended analysis, the assignment to chromosome 1p was confirmed in the majority of the 21 families with Stargardt's disease who were studied. In addition, a series of recombinant chromosomes further narrowed the Stargardt's disease region to an approximately 3 cM interval between markers at D1S424 and D1S497. CONCLUSION: Multipoint linkage analysis most probably excludes this locus in three of these families suggesting non-allelic heterogeneity with at least one additional minor Stargardt's disease locus.

Chromosomes, Human, Pair 1↗
PubMed1994

Inhibition of degranulation of polymorphonuclear leukocytes by angiogenin and its tryptic fragment.

A degranulation inhibiting protein was purified to apparent homogeneity from plasma ultrafiltrates of patients with uremia using gel-permeation chromatography, ion-exchange chromatography, affinity chromatography on blue Sepharose, and ion-exchange chromatography on a Mono S HR 5/5 fast protein liquid chromatography column. The identity of the isolated degranulation inhibiting protein with angiogenin was demonstrated by amino acid sequence determination, immunoblotting, and identical inhibitory activity effects on leukocyte degranulation. At concentrations in the nanomolar range, the protein inhibited spontaneous degranulation of polymorphonuclear leukocytes (PMNL) to 40%. The protein discharge of cells, which were preincubated with nanomolar concentrations of angiogenin and then stimulated with the chemotactic peptide formyl-norleucyl-leucyl-phenylalanyl-norleucyl-tyrosyl-leucine (FNLPNTL), was inhibited by 70%. Cellular functions such as chemotaxis, phagocytosis, and the oxidative respiratory burst were not obviously affected by angiogenin. A polyclonal antibody to human recombinant angiogenin abolished the inhibitory effect of the isolated protein upon PMNL. The same but reduced effect was induced by the disulfide C39-C92 containing tryptic angiogenin fragment L-H-G-G-S-P-W-P-P-C92-Q-Y-R-G-L-T-S-P-C39-K, indicating a new, so far unknown biologically active site of angiogenin which is different from the sites responsible for angiogenic or ribonucleolytic activity. Two synthetic peptides containing residues 83-95, one with S92 instead of C92, revealed the same inhibitory effect on the protein degranulation of PMNL as the entire tryptic fragment.

Amino Acid Sequence↗
PubMed1994

Treatment of non-healing skin ulcers with autologous activated mononuclear cells.

The aim of this study was to investigate whether cultured autologous mononuclear cells (MNC) effectively initiate, accelerate and improve granulation and epithelialisation of skin ulcers. Thirty-three patients with chronic arterial occlusive disease (CAOD; n = 21) or venous post-thrombotic syndrome (PTS; n = 12) were treated with autologous MNC and compared with a control group of 30 patients who received tissue culture medium alone. Previous treatments had been unsuccessful for a mean of 9.23 (3-19) months. MNC were harvested from the peripheral blood of each patient by standard techniques, cultured for three days and applied to the ulcer twice a week. After 4.6 +/- 1.9 weeks, 29/33 ulcers were closed in the MNC group. Patients in the control group took 8.1 +/- 1.2 weeks for 17/30 ulcers. Thus ulcer healing was significantly speedier with MNC seeding; 48% of all ulcers were closed after 30 days of MNC treatment and 92% after 60 days. Patients with PTS responded significantly faster than patients with CAOD. In 90% of patients with painful ulcers MNC treatment resulted in pain relief, whereas in the control group only 50% of patients became pain-free.

Aged↗