Identification of multiple compartments present during the mastication of solid food

The particle size distributions (PSDs) of two portion sizes (2g and 4g) of five foods (cake, cereal bar, muesli bar, cooked pasta and peanuts) after human mastication were determined. The PSD of the expectorated bolus and residual 'debris' rinsed from the mouth were each determined by wet sieving. There were significant differences in the PSD between food types, between portion sizes in the debris fraction and between the bolus and debris fractions. The latter suggests the existence of a two compartment system where particles are comminuted in at least one compartment within the oral cavity.

Effect of Texture of Plastic and Elastic Model Foods on the Parameters of Mastication

Mastication is continually modified throughout the chewing sequence in response to the texture of the food. The aim of this work was to compare the effects of an increase in hardness of two model food types, presenting either elastic or plastic rheological properties, on mastication. Each model food type consisted of four products of different hardness. Sensory testing experiments conducted with one group of 14 subjects showed significant perceived differences between products in terms of their increasing hardness. Fifteen other volunteers were asked to chew three replicates of each elastic and plastic product during two sessions. EMGs of masseter and temporalis muscles were recorded simultaneously with jaw movement during chewing. Numerous variables were analyzed from these masticatory recordings. Multiple linear regression analyses were used to assess the respective effects of food hardness and rheological properties on variables characterizing either the whole masticatory sequence or different stages of the sequence. Muscle activities were significantly affected by an increase in hardness regardless of the food type, whereas the shape of the cycles depended on the rheological properties. The masticatory frequency was affected by hardness at the initial stage of the sequence but overall frequency adaptation was better explained by a change in rheological behavior, with plastic products being chewed at a slower frequency. A dual hypothesis was proposed, implicating first a cortical–brain stem preprogrammed mechanism to adapt the shape of the jaw movements to the rheological properties of the food, and second, a brain stem mechanism with mainly sensory feedback from the mouth to adapt muscle force to the food hardness.

Pharmacokinetics, tolerability, and clinical effectiveness of quetiapine fumarate: an open-label trial in adolescents with psychotic disorders

BACKGROUND

This is the first investigation of the pharmacokinetics, tolerability, and efficacy of quetiapine fumarate in adolescents with chronic or intermittent psychotic disorders.

METHOD

Ten patients with DSM-IV chronic or intermittent psychotic disorders (ages 12.3 through 15.9 years) participated in an open-label, rising-dose trial and received oral doses of quetiapine twice daily (b.i.d.), starting at 25 mg b.i.d. and reaching 400 mg b.i.d. by day 20. The trial ended on day 23. Key assessments were pharmacokinetic analysis of plasma quetiapine concentrations and neurologic, safety, and efficacy evaluations.

RESULTS

No statistically significant differences were observed between 100-mg b.i.d. and 400-mg b.i.d. quetiapine regimens for total body clearance, dose-normalized area under the plasma concentration-time curve, or dose-normalized premorning- or postmorning-dose trough plasma values obtained under steady-state conditions after multiple-dose regimens. No unexpected side effects occurred with quetiapine therapy, and no statistically significant changes from baseline were observed for the UKU Side Effect Rating Scale items that were rated. No serious adverse events or clinically important changes in hematology or clinical chemistry variables were reported. The most common adverse events were postural tachycardia and insomnia. Extrapyramidal side effects improved, as evidenced by significant (p < .05) decreases from baseline to endpoint in the mean Simpson-Angus Scale total scores and Barnes Akathisia Scale scores. Quetiapine improved positive and negative symptoms, as shown by significant (p < .05) decreases from baseline to endpoint in the mean Brief Psychiatric Rating Scale total score, the Clinical Global Impressions-Severity of Illness scale, and the Modified Scale for the Assessment of Negative Symptoms summary score.

CONCLUSION

Quetiapine pharmacokinetics were dose proportional in adolescents and were similar to those previously reported for adults. Quetiapine was well tolerated and effective in the small number of adolescents studied.

Olanzapine in the treatment of adolescent acute mania: a report of seven cases

BACKGROUND

Clozapine may be effective in adults and adolescents with treatment-resistant bipolar disorder. Olanzapine has a receptor affinity profile similar to that of clozapine.

METHODS

The responses of seven consecutive adolescents (ages 12-17) with DSM-IV bipolar disorder, manic episode, treated with olanzapine were evaluated. Response to olanzapine was rated as marked, moderate, minimal, none or worse.

RESULTS

Five (71%) adolescents showed a marked or moderate response. The mean+/-SD olanzapine dose was 0.146+/-0.086 mg/kg/day (11+/-6 mg/day).

CONCLUSION

Olanzapine may have antimanic effects in some adolescents with acute mania. Controlled studies of olanzapine in adolescent bipolar disorder appear to be warranted.

Fever, tumor necrosis factor, and interleukin-6 in young, mature, and aged Fischer 344 rats

The purpose of this study was to compare the febrile responses of Fischer 344 rats of different ages [young (3-5 mo), mature (12-15 mo), and aged (24-27 mo; n = 8)] to two psychological stress paradigms, cage switch and exposure to an open field, as well as to injection of lipopolysaccharide (LPS). In addition, the cytokines tumor necrosis factor-alpha (TNF) and interleukin-6 were also measured in the plasma of these rats at 90 min postinjection with LPS. There was no significant difference among groups in febrile responses to switching their cages. Exposure to an open field for 30 min resulted in a smaller rise in temperature in the aged rats (0.62 degree C) than in the young rats (1.26 degrees C). This difference disappeared if rats were exposed to an open field for 60 min. Injection of LPS led to fevers that developed at a slower rate in aged rats than in the mature groups. The peak fevers, however, were not different. The activity of interleukin-6 90 min after injection of LPS was higher in aged rats (297,858 U/ml) than in young (17,462 U/ml) and mature rats (28,819 U/ml). TNF levels were also higher in aged rats (16,380 U/ml) compared with young (574 U/ml) and mature rats (36 U/ml). We conclude that although the magnitude of the febrile response is not different among rats of different ages, the rise in body temperature occurs slower in aged rats.(ABSTRACT TRUNCATED AT 250 WORDS)