Intestinal calcium transport: the role of sodium.

The role of sodium in intestinal calcium transport was investigated in everted rat intestine. Ethacrynic acid, but not ouabain, inhibited calcium transport. However, ouabain did inhibit net water transport and, therefore, sodium transport, establishing the dissociation of the two transport processes. In addition to a magnesium-dependent adenosine triphosphatase (activated by sodium and potassium), a phosphatase dependent on sodium and calcium was localized to the lateral and basal membrane fractions of the mucosal cell. Activity of the latter phosphatase, similar to calcium transport in intact tissue, was inhibited by ethacrynic acid and not by ouabain. Sodium, therefore, may participate in the calcium transport process by activating an enzyme complex, dependent on adenosine triphosphate, that mediates calcium transport.

Indentification of an intestinal sodium and calcium-dependent phosphatase stimulated by parathyroid hormone.

Previous reports suggest that the site of the energy-dependent intestinal calcium transport against an electropotential and concentration gradient is located along the basal-lateral membrane of the mucosal cell. Accordingly, basal-lateral membranes were prepared from rat intestinal homogenates in order to identify the enzyme mediating this step in the transport process. An alkaline phosphatase was delineated which utilized ATP as a substrate and was dependent on both Na(-) and Ca(++) with optimum enzyme activity at 200 mM and 0.04 mM, respectively. Furthermore, the activity of the enzyme was demonstrated to decrease with the advance in age of the animal and to decrease with removal of the parathyroid glands, consistent with a decreased rate of (45)Ca release from mucosal cells under the same experimental conditions. Calcium binding to basal-lateral membrane fragments was also sodium dependent and enhanced by the prior administration of parathyroid extract. The consistent correlation between the rate of calcium transport across the basal-lateral membrane of the mucosal cell and the activity of this Na, Ca-dependent phosphatase under a variety of experimental conditions suggest that this enzyme may mediate the parathyroid hormone-sensitive active transport of calcium across the intestine.

Vocal fundamental frequency characteristics of infant hunger cries: birth to 12 months.

The vocal fundamental frequency (Fo) characteristics of four infants' hunger cries are reported. The infants were audio recorded at monthly intervals during the first year of life. In general, each infant's Fo increased across the one-year period. The increase in Fo was attributed to the transition from early reflexive crying to intentional vocalization behavior, rather than anatomical and physiological growth influences. Discussion focuses on the regulation of infant crying behavior across the first year of life, as well as the diagnostic implications of these findings.

An acoustic analysis of excellent female esophageal, tracheoesophageal, and laryngeal speakers.

Acoustic data for female esophageal speakers is sparse, particularly with regard to characteristics of female tracheoesophageal speakers. This study quantified and compared six acoustic characteristics of excellent female tracheoesophageal (TE), standard esophageal (SE), and laryngeal (LA) speakers. Results indicated there were no significant differences between TE and SE speakers with regard to mean F0 of sustained /a/, mean F0 (reading), signal-to-noise ratio, total duration of passage read, number of pauses, or syllables per minute. Significant differences were found between LA speakers and both alaryngeal groups for all variables, with the exception of mean F0 (reading).

Acoustic comparison of vowel articulation in normal and reverse phonation.

Acoustic characteristics of the vowels /i,u,a/ produced by adult females and males during normal phonation were compared with the same vowels produced on deliberate ingressive airflow (i.e., "reverse" phonation). Results of the analysis revealed the average fundamental frequency (F0) of reverse phonation to be significantly higher than the corresponding normal phonations. There were no significant differences noted in the vocal tract resonance (F1 and F2 frequency) values for /i/ during normal and reverse phonation. However, the F1 values for /a/ were significantly lower, and the F2 values for /u/ significantly higher, during reverse phonation. The results are discussed with regard to differences in the articulatory control of the speech mechanism during reverse phonation as compared to normal expiratory phonation. Also discussed are the implications of using reverse phonation as a voice management technique.

Formant frequency development: 15 to 36 months.

Developmental characteristics of formant 1 (F1) and formant 2 (F2) are reported for spontaneous vocalizations produced by four young children. Each child was systematically sampled at between 15 and 36 months of age. Results indicated that both F1 and F2 remained relatively unchanged prior to 24 months of age. Significant decreases in average F1 and F2 occurred between 24 and 36 months. When F1 and F2 values were categorized according to tongue elevation and tongue advancement, the most significant changes were associated with high/back articulations. The pattern of formant frequencies noted in the present group of children appears to reflect developmental changes in vocal tract growth and reconfiguration.

Some aerodynamic and acoustic characteristics of acute laryngitis.

The purpose of the present study was to describe the effects of acute laryngitis on some aerodynamic, acoustic, and perceptual measures. Eleven subjects with diagnosed acute laryngitis due to upper respiratory infection were recorded during a laryngitic episode and 1 week to 10 days after amelioration of the laryngitic condition. Fundamental frequency, values, collapsed across the five vowels, were significantly reduced in the laryngitic compared with the normal speaking condition. The decrease in fundamental frequency associated with acute laryngitis suggests an increase in the mass of the vocal folds. In addition, aerodynamic values differed significantly for the laryngitic condition compared with the normal speaking condition, suggesting the presence of laryngeal hypofunction. Perceptual data indicated that speakers in the laryngitic condition were judged to have a hoarse voice when compared with the normal speaking condition.

Speech characteristics of miners with black lung disease (pneumoconiosis).

Speech samples were obtained from 10 miners with diagnosed black lung disease and 10 nonminers who had never worked in a dusty environment and who had no history of respiratory diseases. Frequency, intensity and durational measures were used as a basis upon which to compare the two groups. Results indicated that four of the six pausal measures, vowel duration, vowel intensity variation and vowel perturbation differentiated the miners from the nonminers. The results indicate that black lung disease may affect not only respiratory physiology associated with speech production but also laryngeal physiology.

Speaking fundamental frequency in three groups of hearing-impaired individuals.

The purpose of the present investigation was to provide speaking fundamental frequency data for three groups: 4-6, 8-10, and 16-25-yr-old hearing-impaired individuals. The hearing-impaired children between the ages of 4 to 6 and 8 to 10 yr exhibited mean speaking fundamental frequency values that were 55 Hz and 41 Hz higher, respectively, than values obtained for normally hearing children of similar ages. Fundamental frequency values for postpubescent hearing-impaired males and females were 20 Hz and 30 Hz higher, respectively, when compared to values reported in the literature for normally hearing individuals of similar age and sex.

Nasal airflows in parkinsonian speakers.

Velopharyngeal control in individuals with Parkinson's disease (PD) was studied by obtaining rates of nasal airflow during syllable repetitions. Nasal airflows were described with respect to disease progression, phonetic context, and speaking rate. Significant differences in nasal airflows were obtained for disease progression and phonetic context. The data suggested that velopharyngeal control deteriorates systematically with disease progression. Parkinson's patients at mild and moderate levels of disease progression differentiated the nasal consonant from the oral consonants with increased nasal airflow associated with the nasal consonant. Differences, while not significant, were also observed in nasal flow rate values when the PD patients increased speaking rate from 1 to 5 syllables per second.

Relation between voice profile ratings and aerodynamic and acoustic parameters.

The present study sought to examine the relation between Wilson Voice Profile ratings and certain aerodynamic and acoustic variables. Subjects in this study were 20 adults with voice disorders and five adults with no voice disorders. A series of stepwise multiple correlations were used. The variance in perceptual ratings accounted for by aerodynamic and acoustic variables included in the present study ranged from 29% for tension ratings of connected speech to 81% for pitch ratings of connected speech for the female speakers. It is clear from the present findings that ratings on the Wilson Voice Profile are only partially accounted for by the variables included in the present study.

Speaking fundamental frequency characteristics of institutionalized adults with Down's syndrome.

Mean speaking fundamental frequency was obtained from 16 institutionalized adults with Down's syndrome (8 males, 8 females) and from 16 nonretarded adults of similar age and sex. Both male and female adults with Down's syndrome exhibited a higher mean speaking fundamental frequency than did the nonretarded adults of the same sex. This finding does not support early reports of a characteristically low-pitched voice among Down's syndrome individuals.

A respirometric technique for evaluating velopharyngeal closure in children.

Respirometric quotients, indices of velopharyngeal closure, were determined from oral and nasal air volumes measured separately but simultaneously. Ten children aged 6-10 years were the subjects. The quotients were significantly lower for speech stimuli involving nasal sounds than for those involving nonnasal sounds. In contrast to the quotients obtained in previous research with children, the quotients obtained in this study were close to, but not in excess of, unity.

Preparation, purification and properties of a crosslinked trimer of G-actin.

Phenylenebismaleimide has been used to form crosslinks between actin monomers [Knight, P. and Offer, G. (1978) Biochem. J. 175, 1023-1032]. We have purified a trimer of actin monomers as well as a dimer and a mixture of higher molecular weight oligomers. The trimer is much more effective than the dimer in enhancing the rate of polymerization while higher oligomers do not appear to be any more effective than the trimer. A lag in the polymerization process, as measured fluorescence enhancement of trace pyrene-actin, still occurs in the presence of trimers serving as the nuclei, suggesting that the mechanism for polymerization is more complex than nucleation followed by elongation.

Relation of selected acoustical parameters and perceptual ratings to voice quality of Down syndrome children.

Judges using the Wilson Voice Profile rated the voice quality of 14 noninstitutionalized, 7- to 10-year-old Down syndrome children and a group of nonretarded children. The Down syndrome children received ratings different from the nonretarded children on the Severity subscale of the Wilson Voice Profile. Voice samples were analyzed acoustically in terms of fundamental frequency, fundamental frequency range, frequency and amplitude perturbations, and spectral noise-to-harmonic component ratios. Frequency perturbations, amplitude perturbations, and spectral noise-to-harmonic component ratios were significantly greater for the Down syndrome children. There were also significant correlations between judges' Severity ratings and frequency perturbation levels, amplitude perturbations levels, and spectral noise-to-harmonic component ratios.

A respirometric technique to evaluate velopharyngeal function in speakers with cleft palate, with and without prostheses.

There is a paucity of respirometric quotient (RQ) data on individuals with velopharyngeal inadequacy. Paesani (1964) reported data using a technique that involved separate productions of the same task to obtain the RQ. The RQ values obtained were greater than unity, which is theoretically impossible. In the present study, respirometric quotients, the ratio of oral air volume expended to total volume expended, were obtained using separate but simultaneous productions of oral and nasal airflow. RQ values were calculated for 10 speakers with cleft palate, with and without their prosthetic appliances, and 10 normal speakers. As a group, those with cleft palate and without their appliances exhibited RQ values that were significantly lower than values obtained from the normal speakers and from speakers with the appliances in place. These findings indicated that there were no statistically significant differences in RQ values when comparing sentence repetition and counting tasks. These values were lower than those obtained for the nonnasal syllable repetition tasks, with the /mv/ syllable repetition task generally being associated with the lowest RQ value of any of the speech tasks. The correlation between RQ values and perceptual judgments was -.60, indicating that there was modest agreement between the two measures. As RQ values decreased, perceptual judgments of nasality increased.

Malate dehydrogenases. The lack of evidence for dissociation of the dimeric enzyme in kinetic analyses.

The kinetic parameters of beef heart cytoplasmic and pig heart mitochondrial malate dehydrogenases have been examined over a wide range of enzyme concentration. No significant changes are observed in these properties. In conjunction with active enzyme sedimentation and sedimentation equilibrium experiments, it is concluded that there is no evidence for dissociation of the dimeric enzyme at any enyzme level in the kinetic analyses. Thus, if dissociation occurs, it must be too slow to be of significance in determining the kinetic properties of the enzyme. It is shown that unless a subunit and its dimeric form have identical kinetic and substrate binding characteristics, the kinetic parameters should change as a function of enzyme concentration.

Developmental aspects of formant frequency and bandwidth in infants and toddlers.

Average formant frequency and formant bandwidth values are reported in a cross-sectional sample of 20 children between 4 and 25 months of age. With the exception of a slight rise in F1 at 18 months of age, average F1 and F2 values changed little during the time period, while the average bandwidths for F1 (B1) and F2 (B2) were found to significantly decrease as age increased. The pattern observed for both average formant frequencies and formant bandwidths were attributed to developmental reconfiguration of the vocal tract.

A fluorescent probe for conformational changes in skeletal muscle G-actin.

Actin from rabbit skeletal muscle has been modified with the fluorescent label N-iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine (1,5-I-AEDANS). Under conditions where the actin is in the unpolymerized form (G-actin), the addition of Mg2+ or KCl results in enhancement of the fluorescence. Titration of the labeled G-actin with Mg2+ at varying concentrations of CaCl2 gives, by extrapolation, a value for the dissociation constant for Mg2+ of 35 microM in the absence of Ca2+ and a calculated value of 10 microM for Ca2+ in the absence of Mg2+. The two metal ions compete with each other. The fluorescence enhancement induced by Mg2+ is reversed by the addition of Ca2+ and both processes are time-dependent, indicating a reversible conformational change of G-actin as a consequence of addition of divalent metal. KCl also enhances the fluorescence of the labeled G-actin but does not appear to compete with the divalent metal ion. The enhancement of the fluorescence is very rapid and any conformational change induced by KCl is probably different from that induced by divalent metal ions. Finally, it is shown that loss of fluorescence of the labeled G-actin may be associated with inactivation of the actin.