Fluency effect of frequency alterations of plus/minus one-half and one-quarter octave shifts in auditory feedback of people who stutter

The effect of frequency alterations in auditory feedback of people who stutter on stuttering frequency was investigated. Twelve participants who stutter read aloud under nonaltered auditory feedback (NAF) and four conditions of frequency-altered feedback ([FAF], plus/minus one-half and one-quarter octaves) at normal and fast speech rates. Stuttering frequency was significantly higher while reading aloud with NAF relative to the four conditions of FAF (p < 0.05). There were no differences among participants' stuttering frequency between the four FAF conditions (p > 0.05). Reductions in stuttering frequency of approximately 50% to 60% were found with FAF relative to NAF. More disfluencies occurred with the fast versus the normal speech rate condition (p = .0007) irrespective of auditory feedback condition. These findings suggest that slight alterations in the frequency of auditory feedback of people who stutter are fluency-enhancing.

Fluent speech, fast articulatory rate, and delayed auditory feedback: creating a crisis for a scientific revolution?

In 1970 Kuhn argued that science does not progress through a process of accretion. It is typified, rather, by the successive emergence of different paradigms which during their reign dictate the direction of normal science's puzzle-solving activity. Normal science inevitably exposes an anomaly which violates expectations predicted by the reigning paradigm. The "crisis" evoking anomaly may induce a destructive/constructive paradigm change. Transformations from one paradigm to another constitute a scientific revolution and dictate the growth and maturation of a field. This paper suggests the recent finding, that stutterers experience enhancement of fluency while speaking under delayed auditory feedback at a fast articulatory rate, be viewed as an anomaly. By challenging the notion that a slowed speech rate is necessary for amelioration of stuttering, the anomalous finding may be perceived as a crisis in the study of stuttering.

Stuttering amelioration at various auditory feedback delays and speech rates

The primary purpose of this study was to determine if the finding of Kalinowski et al. (1993) of dramatic reductions in stuttering under delayed auditory feedback (DAF) at normal and fast speech rates could be replicated. The second purpose was to determine if stuttering frequency is differentially affected by various delays in an attempt to identify the optimal delay for fluency enhancement for both normal and fast speech rates. Fourteen adult stutterers read eight different passages at either a normal or fast speech rate under non-altered auditory feedback (NAF) and DAF with delays of 25, 50 and 75 ms. Results showed that significant fluency enhancement occurred under DAF at both normal and fast speech rates at all DAF settings (p < 0.05). This finding corroborates the notion that a slowed rate of speech is not a necessary antecedent for fluency improvement under conditions of altered auditory feedback. In addition, the results indicated that 50 ms appears to be the shortest delay producing the maximum reduction in stuttering frequency.

The Corynebacterium xerosis composite transposon Tn5432 consists of two identical insertion sequences, designated IS1249, flanking the erythromycin resistance gene ermCX

Analysis of the 50-kb R-plasmid pTP10 from the clinical isolate Corynebacterium xerosis M82B revealed that the erythromycin resistance gene, ermCX, is located on a 4524-bp composite transposable element, Tn5432. The ends of Tn5432 are identical, direct repeats of an insertion sequence, designated IS1249, encoding a putative transposase of the IS256 family. IS1249 consists of 1385 bp with 45/42 imperfect terminal inverted repeats. The nucleotide sequence of the 1754-bp Tn5432 central region is 99% identical to the previously sequenced erythromycin resistance region of the Corynebacterium diphtheriae plasmid pNG2. It encodes the erythromycin resistance gene, ermCX, and an ORF homologous to the amino-terminal end of the transposase of IS31831 from Corynebacterium glutamicum. Transposons with regions flanking the insertion sites were recovered from the C. glutamicum chromosome by a plasmid rescue technique. Insertion of Tn5432 created 8-bp target site duplications. A Tn5432-induced isoleucine/valine-auxotrophic mutant was found to carry the transposon in the 5' region of the ilvBNC cluster; in pTP10 the transposon is inserted in a region similar to replication and partitioning functions of the Enterococcus faecalis plasmid pAD1 and the Agrobacterium tumefaciens plasmid pTAR.

Effect of single and combined altered auditory feedback on stuttering frequency at two speech rates

The purpose of this study was to determine if combining delayed auditory feedback (DAF) and frequency altered feedback (FAF) would enhance fluency more than either DAF or FAF alone. Ten stutterers read at normal and fast speech rates under nonaltered auditory feedback (NAF), DAF (i.e., a 50 ms delay), FAF (i.e., a one half octave downward shift), and a combination of DAF and FAF [(COMBO), i.e., a 50 ms delay plus a one half octave downward shift]. Results indicated that stuttering frequency was significantly reduced under all altered auditory conditions at high speech rates relative to the NAF condition. There were, however, no significant differences between the altered auditory feedback conditions (i.e., DAF, FAF, and COMBO). It is suggested that further studies be undertaken to explore the combination of altered auditory feedback conditions, as it may be the case that a floor effect was demonstrated with the singular presentations of DAF and FAF and further improvements in fluency enhancement could not be exhibited in the combined condition. Finally, these findings support the notion that a slowed rate of speech is not necessary for fluency enhancement under conditions of altered auditory feedback.

The erythromycin resistance gene of the Corynebacterium xerosis R-plasmid pTP10 also carrying chloramphenicol, kanamycin, and tetracycline resistances is capable of transposition in Corynebacterium glutamicum

The clinical isolate Corynebacterium xerosis M82B carries the 50-kb R-plasmid pTP10 that confers resistance to the antibiotics chloramphenicol, kanamycin, erythromycin, and tetracycline. A detailed restriction map of pTP10 was constructed by cloning and analyzing restriction fragments of pTP10 in Escherichia coli. The resistance determinants of pTP10 were located by studying the phenotype of the recombinant plasmids in E. coli and Corynebacterium glutamicum. Restriction patterns of fragments encoding the kanamycin and erythromycin resistances revealed striking similarity to the kanamycin resistance of transposon Tn903 and the erythromycin resistance on plasmid pNG2 from Corynebacterium diphtheriae, respectively. Expression of the resistance determinants in E. coli and C. glutamicum ATCC 13032 led to high resistance levels in both strains, with the exception of the tetracycline resistance gene, which could be expressed only in C. glutamicum. Furthermore, the erythromycin resistance gene was found to be located on a transposable element which is functional in C. glutamicum strains.

Isolation of insertion elements from gram-positive Brevibacterium, Corynebacterium and Rhodococcus strains using the Bacillus subtilis sacB gene as a positive selection marker

The sacB gene of Bacillus subtilis was successfully applied in various Arthrobacter, Brevibacterium, Corynebacterium and Rhodococcus strains for the isolation of transposable elements. Three different insertion sequence (IS) elements entrapped in sacB were isolated. The IS elements IS-Bl and IS-Cg isolated from Brevibacterium lactofermentum and Corynebacterium glutamicum, respectively, were found to be similar in size (1.45 kb) and generated target duplications of 8 bp. Their inverted repeats showed homology. In contrast, the IS element IS-Rf isolated from Rhodococcus fascians was only 1.3 kb long and generated a 3-bp target duplication. IS-Cg and IS-Rf were not restricted to their original host strains, and we also found strains harbouring more than one element.

Effect of frequency-altered feedback on stuttering frequency at normal and fast speech rates

The purpose of this study was to determine the effect of the magnitude and direction of the frequency shift of frequency-altered auditory feedback (FAF) on stuttering frequency at both normal and fast speech rates. Twelve adult male and 2 adult female subjects who stutter read 10 different passages at either a normal or fast speech rate under nonaltered auditory feedback (NAF) and each of four FAF conditions in which the feedback signal was shifted: up one-half octave; up one octave; down one-half octave; and down one octave. Mean stuttering frequency for NAF was significantly higher than mean stuttering frequencies for all FAF conditions (p < 0.05). There were no statistically significant differences between the FAF conditions (p > 0.05). Subjects exhibited significantly more disfluencies under the fast speech rate condition relative to the normal speech rate condition. Future research should examine the relationship between frequency shifts of less than one-half octave and stuttering amelioration.

Cloning and characterization of a DNA region encoding a stress-sensitive restriction system from Corynebacterium glutamicum ATCC 13032 and analysis of its role in intergeneric conjugation with Escherichia coli

RP4-mediated transfer of mobilizable plasmids in intergeneric conjugation of Escherichia coli donors with Corynebacterium glutamicum ATCC 13032 is severely affected by a restriction system in the recipient that can be inactivated by a variety of exogenous stress factors. In this study a rapid test procedure based on intergeneric conjugal plasmid transfer that permitted the distinction between restriction-negative and restriction-positive C. glutamicum clones was developed. By using this procedure, clones of the restriction-deficient mutant strain C. glutamicum RM3 harboring a plasmid library of the wild-type chromosome were checked for their restriction properties. A complemented clone with a restriction-positive phenotype was isolated and found to contain a plasmid with a 7-kb insertion originating from the wild-type chromosome. This plasmid, termed pRES806, is able to complement the restriction-deficient phenotype of different C. glutamicum mutants. Sequence analysis revealed the presence of two open reading frames (orf1 and orf2) on the complementing DNA fragment. The region comprising orf1 and orf2 displayed a strikingly low G+C content and was present exclusively in C. glutamicum strains. Gene disruption experiments with the wild type proved that orf1 is essential for complementation, but inactivation of orf2 also resulted in a small but significant increase in fertility. These results were confirmed by infection assays with the bacteriophage CL31 from Corynebacterium lilium ATCC 15990.

Corynebacterium glutamicum DNA is subjected to methylation-restriction in Escherichia coli

Efficient electroporation of Escherichia coli with plasmid DNA isolated from Corynebacterium glutamicum depends on the use of Mcr-deficient E. coli strains. The transformation frequency increased nearly 800-fold when the Mcr-deficient E. coli DH5 alpha MCR was used instead of E. coli DH5 alpha. We used E. coli strains with different mutations in the methyl-specific restriction systems to show that McrBC-deficiency is sufficient to generate this effect. The results imply that C. glutamicum DNA contains methylcytosine in specific sequences recognized by the E. coli McrBC system.

Small mobilizable multi-purpose cloning vectors derived from the Escherichia coli plasmids pK18 and pK19: selection of defined deletions in the chromosome of Corynebacterium glutamicum

Here we describe small mobilizable vectors based on the Escherichia coli plasmids pK18 and pK19. We combined the useful properties of the pK plasmids (e.g., multiple cloning site, lacZ alpha fragment, sequencing with M13 primers) with the broad-host-range transfer machinery of plasmid RP4 and a modified sacB gene from Bacillus subtilis. The new pK derivatives can be transferred by RP4-mediated conjugation into a wide range of Gram- and Gram+ bacteria, and should facilitate gene disruption and allelic exchange by homologous recombination. As an application example, the generation of a defined deletion of the hom-thrB genes in the chromosome of the Gram+ bacterium Corynebacterium glutamicum is presented.

Increased fertility of Corynebacterium glutamicum recipients in intergeneric matings with Escherichia coli after stress exposure

Corynebacterial recipient cells exposed to heat, organic solvents, pH shifts, or detergents show an increased fertility in subsequent interspecific matings with Escherichia coli. This effect is independent of de novo protein biosynthesis and seems to be due to a direct inactivation of a restriction system active against foreign DNA that enters the cell by IncP-mediated conjugation.

Interpreting results of the fluent speech paradigm in stuttering research: difficulties in separating cause from effect

This paper examines difficulties inherent in interpreting results of studies that compare the fluent speech characteristics of stutterers and nonstutterers. The majority of these studies have reported stutterer/nonstutterer differences in temporal parameters of fluent speech production. Such differences have been interpreted as indicating that stutterers possess temporal-motor deficits that are ever-present in speech and, therefore, causal to stuttering. However, a problem for researchers studying the fluent speech of stutterers is that samples may be contaminated by the influence of stuttering. In this paper, evidence is reviewed which suggests that characteristics of the perceptually fluent speech of stutterers change as a function of a number of variables: (a) context of experimental samples, (b) treatment history of subjects, (c) stuttering severity of subjects, and (d) developmental history of stuttering. In addition, evidence is presented which can be interpreted to show that each of these variables reflect stuttering, either directly or indirectly. It is argued that because these variables are difficult to fully control, or account for, comparison of the characteristics of the perceptually fluent speech of stutters and nonstutterers as a method of studying stuttering causation is problematic. Alternative directions for research activity are discussed.

[Nutritional evaluation of sweet potato cultivars Ipomea batata (L.) Lam used in bread as partial substitute of wheat flour]

Four hundred and forty entries of sweet potato tubers from the International Potato Center were evaluated for chemical characteristics related to nutritional value. Dry matter range in the group was 15 to 45g/100g. The native entries DLP 2393, DLP 1120, DLP 2312, DLP 1908 and the foreign RCB 361F were selected for use in bread manufacture. Their average dry matter and crude protein was 38.5 and 9.2% respectively. Sweet potato bread was made replacing 30% of wheat flour with grinded sweet potato tubers. This bread had 11.0% crude protein in dry matter basis which were the same for bread made of wheat flour. There were no differences in organoleptic characteristics or protein quality (Apparent biological value: 37 vs 42%; apparent digestibility: 81 vs 80%; net protein utilization: 33 vs 39%) between sweet potato or full wheat flour breads respectively.

Effects of alterations in auditory feedback and speech rate on stuttering frequency

This study investigated the effects of altered auditory feedback on stuttering frequency during speech production at two different speech rates, Nine stutterers, who exhibited at least 5% dysfluency during a reading task, served as subjects. They read eight different passages (each 300 syllables in length) while receiving four conditions of auditory feedback: nonaltered, masking, delayed, and frequency altered. For each auditory feedback condition, subjects read at both a normal and a fast rate. Results indicated that stuttering frequency was significantly decreased during conditions of delayed and frequency altered auditory feedback at both speech rates (p < 0.05). These findings refute the notion that a slowed speech rate is necessary for fluency enhancement under conditions of altered auditory feedback. Considering previous research and the results of this study, it is proposed that there may be two interdependent factors that are responsible for fluency enhancement: alteration of auditory feedback and modification of speech production.

Molecular analysis of the Corynebacterium glutamicum lysl gene involved in lysine uptake

Two Corynebacterium glutamicum mutants defective in lysine uptake were identified by analysing mutants resistant to S-(2-aminoethyl)-cysteine (AEC). A 5.6 kb genomic DNA fragment restoring AEC sensitivity and lysine uptake was isolated. A 4.2 kb subfragment was sequenced and three open reading frames were identified. Subcloning and gene disruption experiments showed that only the first open reading frame, termed lysl, is involved in lysine uptake. Lysl consists of 501 amino acids with a Mr of 53600. The hydrophobicity profile suggests that the lysl gene product is an integral membrane protein with 13 transmembrane segments. The amino acid sequence of lysl displays strong homology to that of the arcD gene product of Pseudomonas aeruginosa, which is proposed to act as an arginine-ornithine antiporter. Investigation of the influence of the lysl gene on lysine secretion suggests the existence of a separate lysine efflux system in C. glutamicum.

Characterization of pGA1, a new plasmid from Corynebacterium glutamicum LP-6

A new plasmid, pGA1, has been isolated from Corynebacterium glutamicum LP-6, and its detailed restriction map has been prepared. The 4.9-kb plasmid has a G + C content of 57%. It replicates in C. glutamicum ATCC13032 and is compatible with the three other plasmids, pCC1, pBL1 and pHM1519, commonly used for vector construction for amino acid-producing corynebacteria. Fusions of pGA1 with different Escherichia coli replicons (transferred from E. coli to Corynebacterium via transformation of spheroplasts or by filter mating experiments with intact cells) are shown to be suitable as shuttle plasmids; some of them are highly stable in C. glutamicum, even when propagated without any selection pressure.

Metabolic activity of zinc during late pregnancy and lactation of first-litter gilts and their offspring under low dietary zinc intake

The metabolism of Zn-65 was studied in littermate gilts fed either low-Zn (10 mg/kg) or Zn-supplemented (50 mg/kg) diets throughout pregnancy and lactation, and dosed with 100 microCi of Zn-65 at 100 days of pregnancy. Zinc-65 appeared earlier in urine of deficient gilts and about the same time after dose in feces of both groups. Total activity and proportion of the dose excreted via feces were higher in supplemented gilts, where as specific activity (SA) of feces was higher in deficient gilts. Excretion of endogenous Zn by supplemented gilts was triple that of deficient gilts whereas true absorption of Zn by deficient gilts was more than 4-fold that of their supplemented littermates. Biological half-life of Zn-65 was 46 d for the control and twice as long in deficient gilts. Total activity and SA of colostrum was higher in deficient gilts. Muscle, followed by liver, retained the highest proportion of the dose in both groups. Proportion of the dose retained in the liver and lungs was higher in control gilts where as Zn-65 retention in brain, heart, lungs and spleen was higher in deficient gilts. Most tissues from deficient gilts showed higher SA. Liver showed the highest Zn-65 concentration in control and lung in low-Zn newborn piglets. At two weeks of age, liver from both groups of piglets showed the highest Zn-65 retention. Proportion of the dose in brain and lungs was higher in deficient piglets. Specific activity of most organs from deficient piglets was higher than that of controls at both ages. Pregnant gilts under low dietary Zn intake made maximum utilization of this mineral by increasing true absorption and reducing endogenous excretion.

A functionally split pathway for lysine synthesis in Corynebacterium glutamicium

Three different pathways of D,L-diaminopimelate and L-lysine synthesis are known in procaryotes. Determinations of the corresponding enzyme activities in Escherichia coli, Bacillus subtilis, and Bacillus sphaericus verified the fact that in each of these bacteria only one of the possible pathways operates. However, in Corynebacterium glutamicum activities are present which allow in principle the use of the dehydrogenase variant and succinylase variant of lysine synthesis together. Applying gene-directed mutagenesis, various C. glutamicum strains were constructed with interrupted ddh gene. These mutants have an inactive dehydrogenase pathway but are still prototrophic, which is proof that the succinylase pathway of D,L-diaminopimelate synthesis can be utilized. In strains with an increased flow of precursors to D,L-diaminopimelate, however, the inactivation of the dehydrogenase pathway resulted in a reduced formation of lysine, with concomitant accumulation of N-succinyl-diaminopimelate in the cytosol up to a concentration of 25 mM. These data show (i) that both pathways can operate in C. glutamicum for D,L-diaminopimelate and L-lysine synthesis, (ii) that the dehydrogenase pathway is not essential, and (iii) that the dehydrogenase pathway is a prerequisite for handling an increased flow of metabolites to D,L-diaminopimelate.

Cleft palate fistulas: a multivariate statistical analysis of prevalence, etiology, and surgical management

A retrospective, multivariate statistical analysis of 129 consecutive nonsyndromic patients undergoing cleft palate repair was performed to document the incidence of postoperative fistulas, to determine their cause, and to review methods of surgical management. Nasal-alveolar fistulas and/or anterior palatal fistulas that were intentionally not repaired were excluded from study. Cleft palate fistulas (CPFs) occurred in 30 of 129 patients (23 percent), although nearly a half were 1 to 2 mm in size. Extent of clefting, as estimated by the Veau classification, was significantly more severe in those patients who developed cleft palate fistula. Type of palate closure also influenced the frequency of cleft palate fistula. Forty-three percent of patients undergoing Wardill-type closures developed cleft palate fistula versus 10, 22, and 0 percent for Furlow, von Langenbeck, and Dorrance style closures, respectively. The fistula rate was similar in patients with (30 percent) and without (25 percent) intravelar veloplasty. Age at palate closure did not significantly affect the rate of fistulization; however, the surgeon performing the initial closure did not have an effect. Thirty-seven percent of patients developed recurrent cleft palate fistulas following initial fistula repair. Recurrence of cleft palate fistulas was not influenced by severity of cleft or type of original palate repair. Following end-stage management, a second cleft palate fistula recurrence occurred in 25 percent of patients. Continued open discussion of results of cleft palate repair is recommended.

Genetic and biochemical analysis of the aspartokinase from Corynebacterium glutamicum

The lysC/asd gene cluster of Corynebacterium glutamicum ATCC 13032 was cloned and sequenced. The lysC locus coding for aspartokinase consists of two in-frame overlapping genes, lysC alpha encoding a protein of 421 amino acids (Mr 44,300) and lysC beta encoding a protein of 172 amino acids (Mr 18,600). The C. glutamicum aspartokinase was purified and found to contain two proteins of Mr 47,000 and Mr 18,000. A C. glutamicum mutant expressing a feedback-resistant aspartokinase was shown to be changed in a single base pair of the lysC beta gene, leading to an amino acid exchange in the beta-subunit of the aspartokinase. In addition, the identified mutation was found to be responsible for the enhanced expression of the asd gene located downstream of lysC.

Cloning of a DNA fragment from Corynebacterium glutamicum conferring aminoethyl cysteine resistance and feedback resistance to aspartokinase

The Corynebacterium glutamicum/Escherichia coli shuttle vector plasmid pZ1 was used to clone the S-(2-aminoethyl)-D,L-cysteine (AEC)-resistance gene from a lysine-excreting, AEC-resistant strain of C. glutamicum, the aspartokinase activity of which was released from feedback inhibition by mixtures of lysine and threonine or AEC and threonine respectively. A recombinant plasmid designated pCS2 carrying a 9.9-kb chromosomal insert that conferred AEC resistance and the ability to excrete lysine to its host was isolated. The aspartokinase activity of the pCS2-carrying strain was resistant towards inhibition by mixtures of lysine and threonine or AEC and threonine respectively. By deletion analysis the DNA region conferring AEC resistance to the host and feedback resistance to its aspartokinase activity could be confined to a 1.2-kb DNA fragment.

Nitrogen and trace mineral balance of pregnant gilts under low dietary zinc intake

Nitrogen (N) and mineral balance studies were carried out in littermate pregnant gilts fed either a zinc (Zn)-deficient basal diet (10 mg/Kg Zn) or a Zn-supplemented diet (50 mg/kg) from day 22 of pregnancy and in open gilts fed the Zn-supplemented diet. Collections were carried out at 60-66 and at 100-106 days of pregnancy. Open controls had N retention similar to that of Zn-restricted and Zn-supplemented gilts in early pregnancy. A trend towards better N utilization due to Zn supplementation was observed in late pregnancy. Pregnant, Zn-supplemented gilts were in negative Zn and copper (Cu) balance in early pregnancy, whereas open controls and Zn-restricted pregnant gilts were in positive Zn and Cu balance. Utilization of Zn and Cu tended to improve in late pregnancy with Zn-restricted gilts retaining somewhat more Zn and Cu than controls. In early pregnancy, Zn-supplemented gilts retained proportions of dietary iron (Fe) similar to that of open controls and twice the proportion retained by Zn-restricted gilts; the latter tended to increase Fe retention in late pregnancy, but Fe retentions by control gilts were still higher. Pregnant gilts were in negative manganese (Mn) balance in early pregnancy whereas open gilts were in positive balance. In late pregnancy both groups tended to improve their Mn economy, being close to Mn equilibrium. Positive Zn balance in Zn-restricted gilts was achieved by marked reduction of fecal Zn. The Zn-saving mechanisms appeared to influence Cu and Fe retention.

High-frequency conjugal plasmid transfer from gram-negative Escherichia coli to various gram-positive coryneform bacteria

We report on the mobilization of shuttle plasmids from gram-negative Escherichia coli to gram-positive corynebacteria mediated by P-type transfer functions. Introduction of plasmids into corynebacteria was markedly enhanced after heat treatment of the recipient cells. High-frequency plasmid transfer was also observed when the restriction system of the recipient was mutated. On the basis of our data, we conclude that efficient DNA transfer from gram-negative to gram-positive bacteria, at least to coryneform bacteria, is conceivable in certain natural ecosystems.

ISR1, a transposable DNA sequence resident in Rhizobium class IV strains, shows structural characteristics of classical insertion elements

ISR1 is a small transposable element, identified in Rhizobium class IV strains by its high frequent mutagenic insertion into plasmid RP4. Hybridization studies showed that ISR1 is present in, multiple copies in Rhizobium class IV strains. Nucleotide sequence analysis revealed that ISR1 has a length of 1260 bp and is characterized by perfect inverted repeats of 13 nucleotides followed by a stretch of 28/29 nucleotides with imperfect homology. The insertion under study generated a target site duplication of 4 bp. ISR1 carries a large open reading frame, encoding a putative polypeptide of 278 amino acids (ORFA*), and three smaller ones in antiparallel direction (ORFs A1, A2, A3). Two of them are completely covered by the large open reading frame. No significant homology to 17 other known insertion sequence elements could be detected, either at nucleotide or at amino acid levels.