Modification of haloperidol-induced pattern of c-fos expression by serotonin agonists

Acute challenge with clozapine and haloperidol produce different anatomical patterns of c-fos expression in the forebrain. The pharmacological profile of atypical antipsychotics suggests that serotonin might contribute to the unique therapeutic benefits of these drugs. In order to test this possibility, we examined the abilities of 5-HT1A and 5-HT2A/2c agonists to modify the pattern of c-fos expression induced by haloperidol and clozapine. Various groups of rats were pretreated with either saline, DOI, 8-OH-DPAT, and 8-OH-DPAT + DOI 30 min prior to haloperidol or clozapine administration. Rats were killed 90 min after antipsychotic administration. In saline-pretreated rats, haloperidol produced intense Fos-LI in all four striatal quadrants while the effect of clozapine was restricted to the medial part of the striatum. Prior administration of 8-OH-DPAT significantly reduced haloperidol-induced Fos-LI in all four striatal quadrants while DOI and 8-OHDPAT + DOI significantly reduced Fos-LI only in dorso- and ventrolateral quadrants. In the nucleus accumbens, haloperidol induced intense Fos-LI in the core and the shell regions whereas clozapine induced c-fos expression only in the shell. Pretreatment with 8-OHDPAT in haloperidol treated rats reduced Fos-LI in the core region yielding to a c-fos pattern similar to that induced by clozapine. In the prefrontal cortex of saline-pretreated rats, haloperidol produced a moderate c-fos expression compared with the intense expression produced by clozapine. Pretreatment with serotonin agonists before haloperidol brought the number of FOS-positive neurons to the same level as in clozapine treated rats. These results show the ability of 5-HT agonists to transform the typical pattern of c-fos expression induced by haloperidol into a pattern resembling that of clozapine.     

Dental embryology, anatomy, development, and aging

Equine practitioners should be knowledgeable of dental anatomy and development to enhance their skill of age estimation of horses. The permanent teeth of horses are continually undergoing changes in shape and appearance. These changes may be used to suggest a reasonable age range for a horse.     

Direct inhibition of the pancreatic beta-cell ATP-regulated potassium channel by alpha-ketoisocaproate

The ATP-regulated potassium (KATP) channel plays an essential role in the control of insulin release from the pancreatic beta-cell. In the present study we have used the patch-clamp technique to study the direct effects of alpha-ketoisocaproate on the KATP channel in isolated patches and intact pancreatic beta-cells. In excised inside-out patches, the activity of the KATP channel was dose-dependently inhibited by alpha-ketoisocaproate, half-maximal concentration being approximately 8 mM. The blocking effect of alpha-ketoisocaproate was fully reversible. Stimulation of channel activity by the addition of ATP/ADP (ratio 1) did not counteract the inhibitory effect of alpha-ketoisocaproate. In the presence of the metabolic inhibitor sodium azide, alpha-ketoisocaproate was still able to inhibit single channel activity in excised patches and to block whole cell KATP currents in intact cells. No effect of alpha-ketoisocaproate could be obtained on either the large or the small conductance Ca2+-regulated K+ channel. Enzymatic treatment of the patches with trypsin prevented the inhibitory effect of alpha-ketoisocaproate. Based on these observations, it is unlikely that the blocking effect of alpha-ketoisocaproate is due to an unspecific effect on K+ channel pores. Leucine, the precursor of alpha-ketoisocaproate, did not affect KATP channel activity in excised patches. Our findings are compatible with the view that alpha-ketoisocaproate not only affects the beta-cell stimulus secretion coupling by generation of ATP but also by direct inhibition of the KATP channel.     

A new method of readout in radiochromic film dosimetry

Radiochromic film as a dosimetry medium offers several advantages in high-resolution radiography. A new technique of readout was developed to measure the optical density distributions of the film in purely directed light. This technique implements radiochromic film dosimetry near the film's absorption maximum by using a single-mode top-surface emitting laser diode (675.2 nm). The effective sensitivity of the film, compared with a helium-neon laser densitometer (632.8 nm), is increased approximately threefold. Good accuracy, high spatial resolution and simple assembly of the readout system is achieved. Beam profiles of the four final collimator helmets of a Leksell Gamma Knife (Elekta Inc., Sweden) were experimentally determined. Measured profiles and full-widths at half maximum are consistent with the computer generated data of the dose planning system (Kula 4.4, Elekta Inc., Sweden). The output factor of the 4 mm collimator (the smallest collimator with the steepest dose gradient), essential for the application of well defined doses, was checked. The measurements established an output factor of 826 +/- 9 that lies 9 +/- 1% lower than the adjusted one.     

Evaluation of skin- versus teeth-attached markers in wireless optoelectronic recordings of chewing movements in man

This study evaluated the applicability of skin- and teeth-attached reflex markers fixed to the mandible and the head for optoelectronic recording of chewing movements. Markers were attached to the upper and lower incisors and to the skin on the forehead, the bridge of the nose, the tip of the nose and the chin in seven subjects. Chewing movements were recorded in three dimensions using a high-resolution system for wireless optoelectronic recording. Skin markers were systematically displaced due to skin stretch. The largest displacement was observed for the chin marker, whereas minor displacement was found for markers located on the forehead and the bridge of the nose. In repeated recordings, the smallest intra-individual variation in displacement was found for the marker on the bridge of the nose. In spite of relatively large displacement for the chin marker, the temporal estimates of the mandibular movement were not affected. Teeth markers were found to significantly increase the vertical mouth opening, although the duration of the chewing cycle was unaffected. This indicates an increase in chewing velocity. We suggest that markers located on the bridge of the nose are acceptable for recordings of chewing movements. Skin markers on the chin can be reliably used for temporal analysis. They are also acceptable for spatial analysis if an intra-individual variability of 2 mm is allowed. Teeth-attached markers may significantly influence the natural chewing behavior. Thus, both types of marker systems have advantages as well as disadvantages with regard to the accuracy of the chewing movement analysis. Selection of a marker system should be based on the aims of the study.     

Evaluation of expanded polytetrafluoroethylene as a soft-tissue filling substance: an analysis of design-related implant behavior using the porcine skin model

Soft-tissue augmentation using the synthetic nonfluid biomaterial expanded polytetrafluoroethylene (ePTFE) has been supported by number of recent reports citing the favorable characteristics of biocompatibility, soft and natural feel, ease of use, and permanent augmentation. Concern has been expressed about this application for ePTFE material because of the proximity of the implants to the skin surface and potential problems with infection and extrusion. We evaluated the behavior of a series of specific ePTFE implant designs using a long-term subcutaneous augmentation model. By using a porcine model, 466 implants of ePTFE in the form of strips, rolls, or tubes were placed using a percutaneous insertion device subcutaneously over the dorsum and face. The animals were divided into three study groups by length of implantation (3 weeks, control; 6 months, intermediate term; and 12 months, long-term) and en-bloc tissue specimens, including skin, implants, and underlying soft tissue, were harvested for gross and histologic examination. Implants were removed at the earliest sign of infection, exposure, or extrusion and the difficulty of removal was ascertained and recorded. These data reveal that ePTFE material elicits acceptable levels of tissue activity with low extrusion rates over the short and long term supporting its use for soft-tissue augmentation. The data show a clear difference, however, in the host response and behavior of the implants for this application based on shape or design. A statistically significant difference in the low, but measurable, extrusion rates was observed amongst these implant designs. ePTFE tubes showed greater stability and predictable augmentation over other implant designs for soft-tissue augmentation and seem to represent a substantial improvement for this application.     

Gas chromatographic separation of linoleic acid hydroperoxides as trimethylsilyl ethers of methyl hydroxystearates

The primary products, 9- and 13-hydroperoxy-octadecadienoic acids, from lipoxygenase catalyzed oxidation of linoleic acid, were converted into the trimethylsilyl ethers of methyl 9- and 13-hydroxystearates which were completely separated by gas chromatography on an OV-17 methyl silicone (50% phenyl groups), capillary column.