Single word reading in developmental stutterers and fluent speakers.
(65/1930)
Ten fluent speakers and nine developmental stutterers read isolated nouns aloud in a delayed reading paradigm. Cortical activation sequences were mapped with a whole-head magnetoencephalography system. The stutterers were mostly fluent in this task. Although the overt performance was essentially identical in the two groups, the cortical activation patterns showed clear differences, both in the evoked responses, time-locked to word presentation and mouth movement onset, and in task-related suppression of 20-Hz oscillations. Within the first 400 ms after seeing the word, processing in fluent speakers advanced from the left inferior frontal cortex (articulatory programming) to the left lateral central sulcus and dorsal premotor cortex (motor preparation). This sequence was reversed in the stutterers, who showed an early left motor cortex activation followed by a delayed left inferior frontal signal. Stutterers thus appeared to initiate motor programmes before preparation of the articulatory code. During speech production, the right motor/premotor cortex generated consistent evoked activation in fluent speakers but was silent in stutterers. On the other hand, suppression of motor cortical 20-Hz rhythm, reflecting task-related neuronal processing, occurred bilaterally in both groups. Moreover, the suppression was right-hemisphere dominant in stutterers, as opposed to left-hemisphere dominant in fluent speakers. Accordingly, the right frontal cortex of stutterers was highly active during speech production but did not generate synchronous time-locked responses. The speech-related 20-Hz suppression concentrated in the mouth area in fluent speakers, but was evident in both the hand and mouth areas in stutterers. These findings may reflect imprecise functional connectivity within the right frontal cortex and incomplete segregation between the adjacent hand and mouth motor representations in stutterers during speech production. A network including the left inferior frontal cortex and the right motor/premotor cortex, likely to be relevant in merging linguistic and affective prosody with articulation during fluent speech, thus appears to be partly dysfunctional in developmental stutterers. (+info)
Correlation between in vitro and in vivo antifungal activities in experimental fluconazole-resistant oropharyngeal and esophageal candidiasis.
(66/1930)
Oropharyngeal and esophageal candidiasis (OPEC) is a frequent opportunistic mycosis in immunocompromised patients. Azole-resistant OPEC is a refractory form of this infection occurring particularly in human immunodeficiency virus (HIV)-infected patients. The procedures developed by the Antifungal Subcommittee of the National Committee for Clinical Laboratory Standards (NCCLS) are an important advance in standardization of in vitro antifungal susceptibility methodology. In order to further understand the relationship between NCCLS methodology and antifungal therapeutic response, we studied the potential correlation between in vitro susceptibility to fluconazole and in vivo response in a rabbit model of fluconazole-resistant OPEC. MICs of fluconazole were determined by NCCLS methods. Three fluconazole-susceptible (FS) (MIC, /=64 microgram/ml) isolates of Candida albicans from prospectively monitored HIV-infected children with OPEC were studied. FR isolates were recovered from children with severe OPEC refractory to fluconazole, and FS isolates were recovered from those with mucosal candidiasis responsive to fluconazole. Fluconazole at 2 mg/kg of body weight/day was administered to infected animals for 7 days. The concentrations of fluconazole in plasma were maintained above the MICs for FS isolates throughout the dosing interval. Fluconazole concentrations in the esophagus were greater than or equal to those in plasma. Rabbits infected with FS isolates and treated with fluconazole had significant reductions in oral mucosal quantitative cultures (P < 0.001) and tissue burden of C. albicans in tongue, soft palate, and esophagus (P < 0.001). In comparison, rabbits infected with FR isolates were unresponsive to fluconazole and had no reduction in oral mucosal quantitative cultures or tissue burden of C. albicans versus untreated controls. We conclude that there is a strong correlation between in vitro fluconazole susceptibility by NCCLS methods and in vivo response to fluconazole therapy of OPEC due to C. albicans. (+info)
Oral and bronchial provocation tests with aspirin for diagnosis of aspirin-induced asthma.
(67/1930)
In 35 asthmatic patients with acetylsalicylic acid (aspirin; ASA) intolerance (AIA) and 15 asthmatics tolerating ASA well, the authors compared the diagnostic value of the placebo-controlled oral ASA versus inhaled L-lysine (L) ASA challenges. All AIA subjects gave a history of asthmatic attacks following ingestion of ASA and in all of them the intolerance was confirmed by oral challenge test over the past 10 yrs. Doses of ASA increasing in geometric progression were used in oral tests 10-312 mg (cumulative dose 500 mg); in bronchial tests 0.18-115 mg (cumulative dose 182 mg). Either challenge was considered as positive, if forced expiratory volume in one second (FEV1) dropped at least 20% from the baseline value and/or strong extrabronchial symptoms of intolerance occurred. Urinary leukotriene E4 excretion was determined at baseline and following the challenges. In 24 out of 35 patients the oral test was positive, based on a 20% decrease in FEV1. When including extrabronchial symptoms this was positive in 31 cases. Bronchial L-ASA challenge led to > or =20% fall FEV1 in 21 out of 35 cases, and in 27 cases when including extrabronchial symptoms. No correlation was observed between ASA provocative dose causing a 20% fall in FEV1, determined by the oral route compared to the inhalation route. Urinary LTE4 increased after both challenges the rise being higher following oral as compared to inhalation provocation (p=0.0001). It is concluded that both tests had similar specificity whilst the oral test showed a tendency to higher sensitivity for the clinical diagnosis of acetylsalicylic acid intolerance. The inclusion of extrabronchial symptoms into the criteria of test positivity enhanced the diagnostic value of both procedures. In both tests the highest leukotriene E4 increases were found in the presence of extrabronchial symptoms, suggesting the participation of tissues other than the lung in aspirin induced leukotriene E4 release to urine. (+info)
Natural history of Streptococcus sanguinis in the oral cavity of infants: evidence for a discrete window of infectivity.
(68/1930)
The heterogeneous group of oral bacteria within the sanguinis (sanguis) streptococci comprise members of the indigenous biota of the human oral cavity. While the association of Streptococcus sanguinis with bacterial endocarditis is well described in the literature, S. sanguinis is thought to play a benign, if not a beneficial, role in the oral cavity. Little is known, however, about the natural history of S. sanguinis and its specific relationship with other oral bacteria. As part of a longitudinal study concerning the transmission and acquisition of oral bacteria within mother-infant pairs, we examined the initial acquisition of S. sanguinis and described its colonization relative to tooth emergence and its proportions in plaque and saliva as a function of other biological events, including subsequent colonization with mutans streptococci. A second cohort of infants was recruited to define the taxonomic affiliation of S. sanguinis. We found that the colonization of the S. sanguinis occurs during a discrete "window of infectivity" at a median age of 9 months in the infants. Its colonization is tooth dependent and correlated to the time of tooth emergence; its proportions in saliva increase as new teeth emerge. In addition, early colonization of S. sanguinis and its elevated levels in the oral cavity were correlated to a significant delay in the colonization of mutans streptococci. Underpinning this apparent antagonism between S. sanguinis and mutans streptococci is the observation that after mutans streptococci colonize the infant, the levels of S. sanguinis decrease. Children who do not harbor detectable levels of mutans streptococci have significantly higher levels of S. sanguinis in their saliva than do children colonized with mutans streptococci. Collectively, these findings suggest that the colonization of S. sanguinis may influence the subsequent colonization of mutans streptococci, and this in turn may suggest several ecological approaches toward controlling dental caries. (+info)
Peroral small-intestinal biopsy: experience with the hydraulic multiple biopsy instrument in routine clinical practice.
(69/1930)
Experience of the peroral, hydraulic, multiple, small-bowel biopsy instrument is recorded and compared with reported experience of other peroral biopsy instruments. It is concluded that, in routine clinical practice, there is no particular danger associated with this instrument despite warnings to the contrary. Furthermore, biopsies are obtained at least as quickly as with other instruments and with great reliability. Since this instrument also enables multiple, precisely located biopsies to be taken from various levels of the small intestine, it could be considered the instrument of choice for peroral jejunal biopsy. (+info)
Identification of saliva-regulated genes of Streptococcus gordonii DL1 by differential display using random arbitrarily primed PCR.
(70/1930)
Attachment of Streptococcus gordonii to the acquired pellicle of the tooth surface involves specific interactions between bacterial adhesins and adsorbed salivary components. To study saliva-regulated gene expression in S. gordonii, we used random arbitrarily primed PCR (RAP-PCR). Bacteria were incubated in either brain heart infusion medium or saliva. Total RNA from both conditions was purified and RAP fingerprinted and then PCR amplified with an arbitrary primer. The differentially displayed DNA fragments were cloned, sequenced, and analyzed using the BLAST search network service. Three DNA products were up-regulated. One was identified as that of the sspA and -B genes, which encode the salivary agglutinin glycoprotein-binding proteins SspA and SspB of S. gordonii; another had 79% identity with the Lactococcus lactis clpE gene, encoding a member of the Clp protease family; and the third product showed no significant homology to known genes. Five down-regulated genes were identified which encode proteins involved in bacterial metabolism. We have shown, for the first time, direct induction of sspA and -B in S. gordonii by human saliva. (+info)
Growth of several cariogenic strains of oral streptococci in a chemically defined medium.
(71/1930)
A chemically defined medium in which Streptococcus mutans strains AHT, BHT, GS-5, JC-2, Ingbritt, At6T, At9T, 6715, and OMZ-176 and Streptococcus salivarius strain HHT grew rapidly to high turbidities was formulated. Maximal turbidities of each strain were observed after 8 to 12 h of aerobic growth. The subsequent transfer of exponentially growing cells into fresh medium resulted in growth at the same rate without lag. Growth of these strains occurred with rates at least one-half of those observed in an organic medium, such as Todd-Hewitt broth. S. mutans strains FA-1 and OMZ-61 grew at relatively slow rates in the defined medium, but more rapidly growth to higher turbidities of both strains was obtained when sodium bicarbonate was added to the medium. Streptococcus sanguis strain OMZ-9 and another group H streptococcus (strain 72 times 46) grew rapidly in the defined medium after the addition of sodium carbonate. The presence of carbonate or bicarbonate yielded higher turbidities of all the other strains, and the growth rates of several of the strains tested were also increased. (+info)
Amino acid requirements of Streptococcus mutans and other oral streptococci.
(72/1930)
The amino acid requirements of Streptococcus mutans strains AHT, OMZ-61, FA-1, BHT, GS-5, JC-2, Ingbritt, At6T, OMZ-176, 6715, Streptococcus salivarius HHT, Streptococcus sanguis OMZ-9, and strain 72x46 were determined in a chemically defined medium. When grown anaerobically in the presence of sodium carbonate (or bicarbonate for a few strains), few amino acids were required. All strains tested required cystine (or cystine) as a nutrient. Three strains (S. mutans OMZ-176, FA-1, and BHT) required glutamate (and/or glutamine). A third amino acid (lysine for S. mutans FA-1 and histidine for S. mutans OMZ-176) was required by two of the three strains which required glutamate. The amino acids mentioned above were required for all conditions of incubation (and inoculum) tested. The requirements for several other amino acids were conditional, that is, dependent on the incubation conditions and inoculum used. For example, when carbonate was not added, glutamate was required by S. mutans GS-5. Aerobic incubations, with carbonate or bicarbonate added, resluted in requirements for glutamate and leucine by several strains. With these incubation conditions, one strain required isoleucine (S. mutans FA-1), another valine (S. mutans AHT), and a third tyrosine (72x46). Aerobic incubations in the absence of carbonate or bicarbonate further increased the number of amino acids required by several strains. Furthermore, when stationary-phase cultures replaced exponentially growing cultures as an inoculum, several strains required additional amino acids, presumably for the initiation of growth. (+info)