Oral perception of liquid volume changes with age.

Bolus volume has been widely studied, and research has demonstrated a variety of physiological impacts on swallowing and swallowing disorders. Oral perception of bolus volume has not, to our knowledge, been investigated in association with normal ageing processes. Research suggests many sensory changes with age, some within the oral cavity, and changes in swallowing function with age have been defined. The role of perception in oropharyngeal deglutition with age requires further investigation. The purpose of this study was to establish the psychophysical relationship between liquid volume and oral perception and examine changes with age. Healthy young and older adults were prospectively assessed using a magnitude estimation task differentiating five volumes of water delivered randomly to the oral cavity. Results suggest a fourfold increase in liquid volume is required by older participants to perceive an approximate twofold increase in the perception of volume compared with younger healthy adults. Sensory receptors in the oral cavity provide a feedback loop that modulates the swallowing motor response so that it is optimal for the size and consistency of the bolus. Changes in perception of bolus volume with age are consistent with other perceptual changes and may provide valuable information regarding sensorineural rehabilitation strategies in the future.

Laterality, frequency and replication of rTMS treatment for chronic tinnitus: pilot studies and a review of maintenance treatment.

This manuscript reports on findings of three open-label, pilot studies and it reviews studies using rTMS as a maintenance treatment for any disorder. The first pilot study examined whether a patient's original treatment response to 1 Hz rTMS over temporal cortex could be replicated by stimulating a homologous region of the opposite hemisphere. The second study examined whether a patient's response to 1 Hz rTMS could be replicated by applying 10 Hz rTMS over the same treatment site. The third study applied a 3-day course of maintenance rTMS, either at 1 or 10 Hz, when subjects indicated that the benefit of their last course of treatment was waning. Patients with bilateral subjective tinnitus of at least 6 months duration were recruited from a prior, sham controlled study with treatment crossover that applied 1 Hz rTMS over temporal cortex. Both treatment responders and non-responders were recruited. Results indicated, first, that the original treatment response, both positive and negative, is replicated after stimulating a homologous region of the opposite hemisphere; second, patients respond similarly to 1 and 10 Hz stimulation of the same treatment site (an exception was one patient who initially failed 1 Hz stimulation but responded positively to 10 Hz stimulation); and, third, maintenance rTMS had a sustained and additive benefit for tinnitus among treatment responders. Conclusions are that rTMS-induced effects on tinnitus are neither hemisphere specific nor frequency dependent; although, different frequencies of rTMS may have greater potency for a given subject. Maintenance treatment is a well tolerated approach with demonstrated feasibility for managing chronic tinnitus in persons who respond positively to an initial course of treatment.

The primary structures of four subunits of the human, high-molecular-weight proteinase, macropain (proteasome), are distinct but homologous.

Macropain (proteasome) is a high-molecular-weight proteinase complex composed of at least 13 electrophoretically distinct subunits. Previous work, including peptide mapping and limited amino acid sequencing, suggested that most of the subunits belong to an evolutionarily related group of different gene products (Lee et al. (1990) Biochim. Biophys. Acta. 1037, 178-185). In order to define the extent and pattern of subunit relatedness, and to determine the structural basis for possible similarities and differences in subunit functions, we are deducing the primary structures of macropain subunits by cDNA cloning and DNA sequence analysis. We report here the primary structures of four subunits. The data clearly demonstrate that the proteins represent different, but homologous gene products. Surprisingly, no evidence for homology with any other protein, including proteinases, was obtained. These results suggest that macropain is comprised of a previously unidentified family of evolutionarily related polypeptides. Because biochemical data indicate that macropain contains several different proteinase activities, the current results raise the possibility that the macropain complex is composed of a group of novel proteinases, distinct from those of other structurally identifiable proteinase families.

A human gene family with sequence homology to Drosophila melanogaster Hsp70 heat shock genes.

A growing literature describes the structure and regulation of prokaryotic and eukaryotic heat shock genes. We here report the isolation of several members of a human heat shock protein 70 (hsp 70) multigene family which contains at least 10 different genes and/or pseudogenes exhibiting sequence homology to the hsp70 gene of Drosophila melanogaster. Eight nonoverlapping recombinant lambda phages from a lambda-Charon4A human genomic library were studied by restriction mapping. One lambda clone was sequenced and characterized as a hsp70 pseudogene inserted into a rearranged human HindIII 1.9-kilobase repeated DNA sequence. This pseudogene is probably located on the X chromosome. Its predicted amino acid sequence shows extensive homology to those of Drosophila hsp70, trout hsp70, Xenopus hsp70, yeast hsp70, and some homology to the heat-inducible dnaK gene product of Escherichia coli. Amino acid homology is clustered, suggesting evolutionary conservation of domains critical to the function of this protein in both prokaryotic and eukaryotic cells.

The development of correct toothbrushing technique in preschool children.

This study examined the effects of an intensive training program on the toothbrushing skills of three preschool children, using both performance measures and outcome (plaque level) indicators. Toothbrushing was broken into 16 steps that involved actual manipulation of the brush in the mouth. Correct brushing included four criteria: (a) appropriate angle of bristles, (b) appropriate motion of brush, (c) appropriate tooth surface, and (d) minimum duration of brushing. Training included instructions, a three-phase modeling procedure, physical guidance, and reinforcement. Results of a multiple baseline design across subjects showed that the children completed an average of 8.6% of the steps prior to training, as compared with an average of 95.8% of the steps following training. Plaque levels decreased from an average of 58% during baseline to 24.6% after training. Follow-up measures revealed that 86.6% of the steps were maintained. The study demonstrated that the effectiveness of the procedures in teaching very young children a complex motor skill that is essential to their future health.