Validation of the QTL on SSC4 for meat and carcass quality traits in a commercial crossbred pig population.

Porcine chromosome 4 harbours many quantitative trait loci (QTL) affecting meat quality, fatness and carcass composition traits, detected in resource pig populations previously. However, prior to selection in commercial breeds, QTL identified in an intercross between divergent breeds require confirmation, so that they can be segregated. Consequently, the objective of this study was to validate several QTL on porcine chromosome 4 responsible for meat and carcass quality traits. The experimental population consisted of 14 crossbred paternal half-sib families. The region of investigation was the q arm of SSC4 flanked by the markers S0073 and S0813. Regression analysis resulted in the validation of three QTL within the interval: Minolta a* loin, back fat thickness and the weight of trimmed ham. The results were additionally confirmed by factor analysis. Candidate genes were proposed for meat colour, which was the most evident QTL validated in this study.

Associations of functional candidate genes derived from gene-expression profiles of prenatal porcine muscle tissue with meat quality and muscle deposition.

Ten genes (ANK1, bR10D1, CA3, EPOR, HMGA2, MYPN, NME1, PDGFRA, ERC1, TTN), whose candidacy for meat-quality and carcass traits arises from their differential expression in prenatal muscle development, were examined for association in 1700 performance-tested fattening pigs of commercial purebred and crossbred herds of Duroc, Pietrain, Pietrain x (Landrace x Large White), Duroc x (Landrace x Large White) as well as in an experimental F(2) population based on a reciprocal cross of Duroc and Pietrain. Comparative sequencing revealed polymorphic sites segregating across commercial breeds. Genetic mapping results corresponded to pre-existing assignments to porcine chromosomes or current human-porcine comparative maps. Nine of these genes showed association with meat-quality and carcass traits at a nominal P-value of < or = 0.05; PDGFRA revealed no association reaching the P < or = 0.05 threshold. In particular, HMGA2, CA3, EPOR, NME1 and TTN were associated with meat colour, pH and conductivity of loin 24 h postmortem; CA3 and MYPN exhibited association with ham weight and lean content (FOM) respectively at P-values of < 0.003 that correspond to false discovery rates of < 0.05. However, none of the genes showed significant associations for a particular trait across all populations. The study revealed statistical-genetic evidence for association of the functional candidate genes with traits related to meat quality and muscle deposition. The polymorphisms detected are not likely causal, but markers were identified that are in linkage disequilibrium with causal genetic variation within particular populations.

Partial rescue of epithelial phenotype in integrin beta4 null mice by a keratin-5 promoter driven human integrin beta4 transgene.

Integrin beta4 null mice exhibit extensive epidermal detachment, reminiscent of the human skin blistering disease junctional epidermolysis bullosa associated with pyloric atresia. Hemidesmosomes, the stable adhesion structures of squamous epithelia, are not formed in the absence of alpha6beta4. Null mutant mice die shortly after birth, but apart from their striking epithelial phenotype, no obvious developmental defects have been observed. To elucidate the cause of death in these mice, we generated transgenic mice with a heterologous construct consisting of the squamous epithelial-specific keratin-5 promoter and a human integrin beta4 subunit cDNA. The transgene was not expressed in the presence of endogenous beta4, probably as a result of competition for a limited pool of alpha6 subunits. In a beta4 null background, however, the transgene was expressed, and its expression pattern followed that of squamous epithelial-specific keratins. These rescued pups appeared healthy and ultrastructural analysis revealed that the interspecies heterodimer alpha6(mouse)/beta4(human) was sufficient to trigger the assembly of hemidesmosomes. After a variable period of up to 48 hours after birth these animals began to exhibit haemorrhages at the plantar and palmar areas. We observed the formation of small blisters and found that the transgene was not detectably expressed in this region, which is devoid of hair follicles. The rescued neonates became increasingly cyanotic and died soon after the onset of this phenomenon. We performed a developmental study of the expression of beta4 in the complete respiratory tract, but we found no correlation between the spatiotemporal distribution of beta4 and the onset of the respiratory insufficiency. It became clear, however, that there was a gradual detachment of squamous epithelia in the oral and nasal cavities which led to obstruction of the respiratory tract, suggesting that in beta4 null and rescued mice, neonatal death was a direct consequence of decreased adhesion properties of hairless squamous epithelia, rather than a developmental defect of the lungs.

Genomic structure of the human PLZF gene.

The human PLZF (promyelocytic leukaemia zinc finger) gene encodes a Krüppel-like zinc finger protein, which was identified via the reciprocal translocation t(11;17)(q23;q21) fusing it to the retinoic acid receptor alpha (RARalpha) gene in promyelocytic leukaemia. To determine its complete genomic organisation, we constructed a cosmid-map fully containing the hPLZF gene. The gene has seven exons, including a novel 5' untranslated exon, varying in size from 87 to 1358bp and spans at least 120kb. Flanking intronic sequences were identified and all splice acceptor and donor sites conformed to the gt/ag rule. Five polymorphic markers could be fine located in its vicinity. These data will facilitate mutation analysis of hPLZF in t(11;17) leukaemia cases, as well as assist mapping and loss-of-heterozygosity analysis. Here we have tested hPLZF as a possible candidate for the PGL1 locus involved in hereditary head and neck paragangliomas. However, mutation analysis revealed no aberration in 12 paraganglioma patients from different families.

Founder effect at PGL1 in hereditary head and neck paraganglioma families from the Netherlands.

PGL1, a gene responsible for hereditary paragangliomas of the head and neck, recently was mapped to a 2-cM interval on chromosome 11q22-q23, by linkage and haplotype-sharing analysis of a large multibranch Dutch family. We determined the disease-linked haplotype, as defined by 13 markers encompassing a large interval on 11q21-q23, in 10 additional families ascertained from the same geographical locale. Alleles were identical for six contiguous markers, spanning a genetic distance of 6 cM and containing PGL1. Despite this strong indication of a common ancestor, no kinships between the families could be demonstrated through genealogical surveys going back to 1800 a.d. We conclude that a single ancestral mutation is responsible for most, if not all, hereditary paragangliomas, in this region of The Netherlands, and that strong founder effects may exist at the PGL1 locus.

PMMA bead versus parenteral treatment of Staphylococcus aureus osteomyelitis.

A. rabbit model of Staphylococcus aureus osteomyelitis was used to compare 3 weeks of clindamycin-impregnated polymethylmethacralate (PMMA) bead treatment with 3 weeks of gentamicin-impregnated polymethylmethacralate bead treatment, 4 weeks of parenteral clindamycin treatment, and surgical debridement without any antibiotic treatment. The animals were weighed throughout the course of the experiment and cortical bone and marrow flush specimens were obtained for bacterial culture at the end of therapy. The cortical specimens were bacteria free in 100% (6/6) of the animals receiving parenteral clindamycin, 83% (5/6) of the animals in the clindamycin PMMA group and, none of the animals in the gentamicin PMMA group. The marrow flush specimens were bacteria free in 83% (5/6) of the animals in the parenteral clindamycin group, 67% (4/6) of the animals in the clindamycin PMMA group, and 40% (2/5) of the animals in the gentamicin PMMA group. While these findings are preliminary and further studies with larger numbers of animals are needed, the authors suggest that when PMMA bead therapy is being contemplated, serious consideration should be given to replacing gentamicin with clindamycin in treatment of gram-positive osteomyelitis. Furthermore, incorporation of clindamycin with gentamicin (or tobramycin) should be considered when treating mixed gram-positive and gram-negative osteomyelitis.

Lexicalization in adults who stutter.

Three recent theories have implicated lexical processing failures as a possible source of fluency disruption in persons who stutter. Two experiments that bear upon these theories are reported. Both evaluate the effects on speech response latency of picture naming tasks designed to place selective demands on lexicalization: Experiment I, effects of one-word versus two-word responses; Experiment II, effects of a word's frequency of occurrence versus its number of syllables. Twelve adults who stutter and 12 with normally fluent speech participated in each experiment. In Experiment I, increases in naming latency for two-word (noun + verb) versus one-word (noun or verb) responses showed that demands for parallel processing did not differentiate the experimental groups. However, the between-group difference, showing longer latencies among those who stutter, was six times greater for the verb, than for the noun, task. Moreover, the group difference for verbs fully accounted for the size of the difference in the two-word task. Experiment II showed that the relative increase in naming latency associated with the word frequency effect versus the syllable latency effect was significantly greater in the stuttering than the nonstuttering group. Outcomes of the two experiments suggest that during lexicalization, as early as the L1 stage and first phase of L2, slow processing could serve to disrupt fluency in some persons who stutter. Under certain conditions, as specified in the three theories cited, such disruptions could set the occasion for stutter events.

Homozygotes for CDKN2 (p16) germline mutation in Dutch familial melanoma kindreds.

The p16 gene (CDKN2) which is localized on chromosome 9p21, is deleted in a significant number of sporadic cancers. Moreover, germline mutations identified in some melanoma-prone kindreds last year suggested that CDKN2 is identical to the 9p21-linked melanoma susceptibility gene (MLM); however, failure to identify p16 mutations in all melanoma kindreds putatively linked to 9p21 left some doubts. We have analysed CDKN2 coding sequences in 15 Dutch familial atypical multiple mole-melanoma (FAMMM) syndrome pedigrees, and identified a 19 basepair (bp) germline deletion in 13 of them. All 13 families originate from an endogamous population. The deletion causes a reading frame shift, predicted to result in a severely truncated p16 protein. Interestingly, two family members are homozygous for the deletion, one of whom shows no obvious signs of disease. This surprising finding demonstrates that homozygotes for this CDKN2 mutation are viable, and suggests the presence of a genetic mechanism that can compensate for the functional loss of p16. Our results also greatly strengthen the notion that p16 is indeed MLM.

Word familiarity, syllabic stress pattern, and stuttering.

The correspondence of stuttering and linguistic characteristics of utterances has led to speculations that a source factor for stutter events is a speaker's inadequate formulation of the speech code. In this study, the effects of word frequency and syllabic stress pattern on stuttering frequency were evaluated using specially designed sentences read orally by 10 adult stutterers and 10 adult nonstutterers. Results revealed statistically significant differences in stuttering frequency between sentences with low and high frequency words, but not between sentences with regular and irregular syllabic stress patterns. The significant rank order correlation between stutterers' word recognition vocabulary scores and amount of stuttering on sentences with high versus low frequency words affirmed that word familiarity, not simply word prominence, is an important factor contributing to the word frequency effect. The outcomes are discussed in relation to current psycholinguistic theories of stuttering, proposing that word access and phonological encoding difficulties could be a source factor that underlies the occurrence of stutter events.

Constancy of interstress intervals in the fluent speech of people who stutter during adaptation trials.

The constancy of interstress intervals (ISIs) was studied in the fluent speech of 2 people who stutter during five adaptation trials. Counter to prediction, ISI constancy did not improve as an accompaniment to the reduction of stuttering from Readings 1-5. Overall, the subjects' ISIs were substantially more variable in duration than those of 2 nonstutterers. This was accounted for by the subjects' unusually long ISIs in utterances that placed greater demands on speech motor control processes. Implications for impairment source factors in stuttering are discussed.

Syllabic stress and the occurrence of stuttering.

The occurrence of stuttering on stress-peak and unstressed syllables in connected speech was studied in 10 young adult stutterers. Results showed a significant coincidence of stutter events and syllabic stress peaks, particularly in polysyllabic words. Stuttering on the first three words of principal clauses, however, appeared independent of syllabic stress. Similarities between the loci of stutter events and segmental errors of speech are considered in relation to explanations that regard stuttering as evidence of failure in normal speech production processes.

Acoustical durations of speech segments during stuttering adaptation.

Acoustical durations of stutter- and disfluency-free speech segments from Readings #1 and #5 in an adaptation series were measured in 4 adapting, 4 nonadapting, and 4 nonstuttering subjects. The segment durations measured were intervocalic interval, stop-gap, voice onset time, and vowel duration. No clear trends in the change of acoustical durations from Reading #1 to Reading #5 distinguished the adapting, nonadapting, or nonstuttering subjects. Moreover, on the basis of speech naturalness judgements, listeners did not differentiate the Reading #1 and #5 phrase segments of subjects with high adaptation versus those with low adaptation scores. From these findings and related literature, adaptation of stuttering, as well as other fluency-inducing conditions, are viewed as circumstances that reduce demands upon central motor-linguistic processes.

Response contingent stimuli and stuttering: issues and implications.

The first papers concerning effects of response contingent stimuli (RCS) on stuttering and speech disfluency were published approximately 30 years ago. Research in this area fluorished until about 1980 after which relatively few studies have been reported. Reasons for the decline in interest are not altogether clear because crucial issues remain unresolved. This paper highlights and evaluates these issues and considers their implications for future research.

Defense preference and stutterers' speech disfluencies: implications for the nature of the disorder.

Psychological defense mechanism preference was assessed in 16 adult stutterers. From this group, two subgroups of six subjects each were identified by their opposite extremes in defensive style: (1) expressive defenders; (2) avoidance defenders. Subsequently, these subgroups were found to be significantly different in measures of stuttering frequency and disfluency type. The expressive defenders showed higher frequency stuttering than the avoidance defenders (21.5% vs. 4.66%) while the avoidance subgroup showed preference for the use of accessory-type disfluencies; that is, interjections, phrase repetitions, and whole word repetitions. The possibility that the speech disfluencies of stutterers may vary as a function of defense preference is discussed in relation to: (1) definitions of stuttering phenomena and the disorder; (2) the developmental nature of stuttering as a problem and the role of learning; (3) different syndromes of stuttering; and (4) the contributions of etiologic versus pathogenic factors to the origins of the disorder.

Principal and differential effects of haoperidol and placebo treatments upon speech disfuluencies in stutterers.

Fourteen stutterers completed a double-blind crossover study of the effects of Haloperidol and Placebo treatments upon their speech disfluencies. Although clearly not clinically effective, Haloperidol had a statistically significant effect upon reducing disfluency frequency and increasing speaking rate. For most subjects, drug-related reductions in disfluency severity resulted from a decrement in whole-word and phrase repetition, interjection, and revision-type disfluencies rather than from fewer part-word (elemental) repetitions and prolongations of sound or of silence. Neurotic personality profile correlated positively with an overall placebo effect, and there was a positive correlation between abnormal EEG and the drug effect. These findings are discussed in light of the nature of speech disfluency and stuttering and Haloperidol's biochemical and behavioral actions.

Neural response time of stutterers and nonstutterers in selected oral motor tasks.

Neural response time (NRT) was compared for 12 adult stutterers and 12 matched normal speakers on two verbal tasks (production of /pae/ and /bae/) and one oral, nonverbal task (lip closure) in response to visual and auditory stimulation. The auditory response stimulus was presented separately to the left and right ears, and the visual stimulus to both eyes. NRT was defined as the time interval between stimulus offset and the onset of electromyographic (EMG) activity from orbicularis oris superior muscle. Results show, in general, that stutterers are slower in NRT for all response tasks in both stimulus modes. Significant differences were found, however, for only the auditory mode. Analyses of the differences between and within groups for response tasks and stimulus modes are discussed in terms of recent research in and theory of timing disturbances in stuttering.