Altered Ca2+ responses in muscles with combined mitochondrial and cytosolic creatine kinase deficiencies

We have blocked creatine kinase (CK)-mediated phosphocreatine (PCr) -->/<-- ATP transphosphorylation in skeletal muscle by combining targeted mutations in the genes encoding mitochondrial and cytosolic CK in mice. Contrary to expectation, the PCr level was only marginally affected, but the compound was rendered metabolically inert. Mutant muscles in vivo showed significantly impaired tetanic force output, increased relaxation times, altered mitochondrial volume and location, and conspicuous tubular aggregates of sarcoplasmic reticulum membranes, as seen in myopathies with electrolyte disturbances. In depolarized myotubes cultured in vitro, CK absence influenced both the release and sequestration of Ca2+. Our data point to a direct link between the CK-PCr system and Ca2+-flux regulation during the excitation and relaxation phases of muscle contraction.

Amyloid in the horse: a report of nine cases

Out of approximately 16,000 horses referred for clinical examination, nine had amyloidosis. Six of these horses had localised amyloid deposits in the wall of the nasal meatus and ventral turbinates associated with epistaxis. Horse 1 also developed malignant histiolymphocytic lymphosarcomas. The amyloid deposits were potassium permanganate-resistant and tryptophan-positive. Gel filtration of solubilised amyloid fibrils from Horse 1 revealed a major retarded fraction with an apparent molecular weight of 20 kD. This protein had an amino acid composition similar to human AL-amyloid proteins and horse immunoglobulin light chains. On Western blot a strong cross-reaction was observed between horse 1gG2a light chains and the Horse 1 amyloid. Horses 7 to 9 had suppurative verminous aneurysm, tuberculosis and an adrenal cortical adenoma, respectively, and had generalised amyloid deposits in liver and spleen. These amyloid deposits were found to be potassium permanganate-sensitive and positive for tryptophan. Gel filtration of solubilised amyloid fibrils from Horse 8 revealed a major retarded fraction (protein AA) with an apparent molecular weight of 10 kD. Immunoperoxidase-antiperoxidase staining showed the localised deposits to be negative or only weakly positive with antisera against bovine, hamster, dog and human protein AA and to be positive with anti-horse-one amyloid protein. The generalised deposits were found to be positive with the antisera against allogenic protein AA. The results of the potassium permanganate incubation, biochemistry, immunoblotting and immunochemistry, indicate that the localised amyloid of Horse 1 and most likely the amyloid of Horses 2 to 6, is of the AL-type. The generalised amyloid deposits were found to be of the AA type.

The transcription factor Grainy head and the steroid hormone ecdysone cooperate during differentiation of the skin of Drosophila melanogaster

The arthropod epidermis is an epithelium that deposits the apical cuticle, which is a stratified extracellular matrix (ECM) protecting the animal against pathogens, preventing dehydration and also serving as an exoskeleton. Differentiation of the cuticle conceivably implies coordinated production, secretion and localization of its components. The underlying molecular mechanisms are poorly explored. In this work, we show that the transcription factor Grainy head and the steroid hormone ecdysone drive the production of two partially overlapping sets of cuticle factors. Nevertheless, Grainy head is needed to modulate the expression of ecdysone signalling factors; the significance of this cross-talk is yet unclear. In addition, we found that ecdysone signalling negatively regulates its own impact. In conclusion, our findings suggest that at least two independently triggered pathways have evolved in parallel to cooperatively ensure the stereotypic implementation of the cuticle. As Grainy head is also essential for epithelial differentiation in vertebrates, we speculate that it acts to decode the ancient skin programme common to all animals. Full differentiation of the skin necessitates a second, complementing taxon-specific programme that requires its own decoder, which is represented by ecdysone in arthropods, whereas the vertebrate specific one remains to be identified.

Interactions between dentists and anxious child patients: a behavioral analysis

The aim of this investigation was to study the effect of dentists' behavior on the (anxious) behavior of child patients. Twelve high-anxious and a matched group of 12 low-anxious children from 6 to 12 yr of age were selected and randomly assigned to one of six dentists: three with experience in treating fearful children and three without such experience. Each child was treated twice. The first treatment was prophylactic, the second, 2 wks later, consisted of preparation and restoration of a cavity (Class 1) under local anesthesia. While both treatment sessions were videotaped, only the latter one was used in this study. Data analysis which did not control for autocorrelations revealed 22 (out of 28) significant effects. Data analysis with a control for autocorrelations showed only two significant effects: 'working contact', which decreased fear-related behavior and 'no physical contact', which increased fear-related behavior.

Dental fear and caries in 6-12 year old children in Greece. Determination of dental fear cut-off points

AIM

To present: the normative data on dental fear and caries status; the dental fear cut-off points of young children in the city of Thessaloniki, Greece.

METHODS

Study Design: This is a cross-sectional study with two independent study groups. A first representative sample consisted of 1484 children from 15 primary public schools of Thessaloniki. A second sample consisted of 195 randomly selected age-matched children, all patients of the Postgraduate Paediatric Dental Clinic of Aristotle University of Thessaloniki. First sample: In order to select data on dental fear and caries, dental examination took place in the classroom with disposable mirrors and a penlight. All the children completed the Dental Subscale of the Children's Fear Survey Schedule (CFSS-DS). Second sample: In order to define the cut-off points of the CFSS-DS, dental treatment of the 195 children was performed at the University Clinic. Children&#x2041;s dental fear was assessed using the CFSS-DS and their behaviour during dental treatment was observed by one calibrated examiner using the Venham scale.

STATISTICS

Statistical analysis of the data was performed with IBM SPSS Statistics 20 at a statistical significance level of <0.05.

RESULTS

First sample: The mean CFSS-DS score was 27.1&#177;10.8. Age was significantly (p<0.05) related to dental fear. Mean differences between boys and girls were not significant. Caries was not correlated with dental fear. Second sample: CFSS-DS< 33 was defined as 'no dental fear', scores 33-37 as 'borderline' and scores > 37 as 'dental fear'. In the first sample, 84.6% of the children did not suffer from dental fear (CFSS-DS<33).

CONCLUSION

Dental fear was correlated to age and not to caries and gender. The dental fear cut-off point for the CFSS-DS was estimated at 37 for 6-12 year old children (33-37 borderlines).

Behavior of dentists and child patients during treatment

This study is part of a larger research project which aims to analyze children's dental fear by making a detailed analysis of the behavioral interactions between dentists and anxious child patients. The behavior of 12 high- and 12 low-anxious children was recorded on videotape during two dental visits in which the children were treated by either experienced or inexperienced dentists. Results indicated a relation between the dentist's experience in treating anxious children and the behavior of child patients. In general, children treated by experienced dentists showed more fear-related behaviors. Furthermore, the behavior of the dentist was related to both his experience and the fear level of the child patient. Experienced dentists showed more communicative behaviors than the inexperienced dentists, but all dentists communicated more with high- than with low-anxious children. Experienced dentists worked faster than inexperienced dentists, but treatment of the high-anxious children was not more time-consuming than treatment of the low-anxious children.

General method for analysing dentist-patient interaction

The interaction between dentist and patient during dental treatment may influence the frequency of dental visits in the future because this interaction may increase the dental fear of the patient. To find the characteristics of the dentist's behavior that increase or decrease dental fear a statistical analysis of the interaction may be used. Data of such interactions are known as time series. Because it is highly probable that the behavior of an individual at two different points in time is autocorrelated a correct statistical analysis of the interaction between dentist and patient must take this possibility into account. A general statistical method is proposed that can take autocorrelations into account. The method is compared with a simpler method that may not deal adequately with autocorrelations.

Comparative metabolism of aflatoxin B1 in mouse, rat and human primary hepatocytes using HPLC-MS/MS

Aflatoxin B1 (AFB1) is a highly hepatotoxic and carcinogenic mycotoxin produced by Aspergillus species. The compound is mainly metabolized in the liver and its metabolism varies between species. The present study quantified relevant AFB1- metabolites formed by mouse, rat, and human primary hepatocytes after treatment with 1 µM and 10 µM AFB1. The use of liquid chromatographic separation coupled with tandem mass spectrometric detection enabled the selective and sensitive determination of phase I and phase II metabolites of AFB1 over incubation times of up to 24 h. The binding of AFB1 to macromolecules was also considered. The fastest metabolism of AFB1 was observed in mouse hepatocytes which formed aflatoxin P1 as a major metabolite and also its glucuronidated form, while AFP1 occurred only in traces in the other species. Aflatoxin M1 was formed in all species and was, together with aflatoxin Q1 and aflatoxicol, the main metabolite in human cells. Effective epoxidation led to high amounts of DNA adducts already 30 min post-treatment, especially in rat hepatocytes. Lower levels of DNA adducts and fast DNA repair were found in mouse hepatocytes. Also, protein adducts arising from reactive intermediates were formed rapidly in all three species. Detoxification via glutathione conjugation and subsequent formation of the N-acetylcysteine derivative appeared to be similar in mice and in rats and strongly differed from human hepatocytes which did not form these metabolites at all. The use of qualitative reference material of a multitude of metabolites and the comparison of hepatocyte metabolism in three species using advanced methods enabled considerations on toxification and detoxification mechanisms of AFB1. In addition to glutathione conjugation, phase I metabolism is strongly involved in the detoxification of AFB1.

Lactic acidaemia due to hyperventilation in a child with severe mental retardation

A 16-year-old girl with severe mental retardation of unknown aetiology presented with increased blood content of lactate and pyruvate. It was demonstrated that the biochemical abnormalities were due to hyperventilation.

Predicting dental anxiety. The clinical value of anxiety questionnaires: an explorative study

AIM

This was to explore the usefulness of the Dental Subscale of the Children's Fear Survey Schedule (CFSS-DS) and the Child Behaviour Checklist (CBCL), used prior to treatment, in relation to the actual behaviour displayed during treatment.

METHODS

The study group was 26 children, referred to a special dental care clinic for behaviour management problems, mostly caused by dental fear. Questionnaires used were the parent versions of the Dental Subscale of the Children's Fear Survey Schedule (CFSS-DS) and the Child Behaviour Checklist (CBCL). Behaviour was registered on videotape and scored by independent observers using the modified Venham scale. Treatment consisted of a familiarization visit and two restorative sessions.

RESULTS

There was a significant reduction in fear, based on pre and post treatment CFSS-DS scores, and also the child's fearful behaviour during the two restorative sessions appeared to be related. But no correlation was found between the CFSS-DS and the CBCL, nor between the CFSS-DS and the behaviour displayed during the treatment sessions.

CONCLUSION

The child's anxious behaviour during actual restorative dental treatment is not so much related to its own anticipatory dental anxiety or the anxiety of the mother. Results support the role of a multifactorial model.

Dentists' behavior in response to child dental fear

Dental fear is a multifactorial problem frequently encountered during dental treatment of children. Studies have indicated that, among others, the behavior of the dentist may play a part in the development of this dental fear. The present study was undertaken to examine the behavioral aspects of the dentist-patient relationship, and specific dentists' behavior that can reduce dental fear. The behavior of forty children referred to a center for special dental care and of two dentists was assessed during treatment. T-test results showed that the children's level of fear decreased after treatment (mean 3.2 vs. 2.1, t = -5.6, p = .000). In addition, it was found that the dentists behaved more directly and authoritatively during the treatment of highly fearful children than during the treatment of relatively less fearful children (p < or = .034). It seems that this direct approach had a positive, long-term effect on these children's fearful behavior during treatment.

Integrated data from intravital imaging and HPLC-MS/MS analysis reveal large interspecies differences in AFB1 metabolism in mice and rats

Large interspecies differences between rats and mice concerning the hepatotoxicity and carcinogenicity of aflatoxin B1 (AFB1) are known, with mice being more resistant. However, a comprehensive interspecies comparison including subcellular liver tissue compartments has not yet been performed. In this study, we performed spatio-temporal intravital analysis of AFB1 kinetics in the livers of anesthetized mice and rats. This was supported by time-dependent analysis of the parent compound as well as metabolites and adducts in blood, urine, and bile of both species by HPLC-MS/MS. The integrated data from intravital imaging and HPLC-MS/MS analysis revealed major interspecies differences between rats and mice: (1) AFB1-associated fluorescence persisted much longer in the nuclei of rat than mouse hepatocytes; (2) in the sinusoidal blood, AFB1-associated fluorescence was rapidly cleared in mice, while a time-dependent increase was observed in rats in the first three hours after injection followed by a plateau that lasted until the end of the observation period of six hours; (3) this coincided with a far stronger increase of AFB1-lysine adducts in the blood of rats compared to mice; (4) the AFB1-guanine adduct was detected at much higher concentrations in bile and urine of rats than mice. In both species, the AFB1-glutathione conjugate was efficiently excreted via bile, where it reached concentrations at least three orders of magnitude higher compared to blood. In conclusion, major differences between mice and rats were observed, concerning the nuclear persistence, formation of AFB1-lysine adducts, and the AFB1-guanine adducts.