Are speech perception deficits associated with developmental dyslexia?

Phonological awareness and phoneme identification tasks were administered to dyslexic children and both chronological age (CA) and reading-level (RL) comparison groups. Dyslexic children showed less sharply defined categorical perception of a bath-path continuum varying voice onset time when compared to the CA but not the RL group. The dyslexic children were divided into two subgroups based on phoneme awareness. Dyslexics with low phonemic awareness made poorer /b/-/p/ distinctions than both CA and RL groups, but dyslexics with normal phonemic awareness did not. Examination of individual profiles revealed that the majority of subjects in each group exhibited normal categorical perception. However, 7 of 25 dyslexics had abnormal identification functions, compared to 1 subject in the CA group and 3 in the RL group. The results suggest that some dyslexic children have a perceptual deficit that may interfere with processing of phonological information. Speech perception difficulties may also be partially related to reading experience.

Env-specific CTL predominate in cats protected from feline immunodeficiency virus infection by vaccination

Animal models of HIV-1 have a key role to play in elucidation of the cellular mechanisms responsible for protective immunity. Vaccination of domestic cats with whole inactivated feline immunodeficiency virus (FIV) elicits virus-neutralizing Abs and virus-specific CTL in the peripheral blood and lymphoid organs and affords protection from homologous virus challenge. In the present study we confirm the induction of virus-specific CTL following immunization with whole inactivated FIV vaccine and demonstrate that cats are protected for up to 1 yr following vaccination. Long term protection in vaccinated cats correlates with both higher levels of FIV Env-specific CTL in the peripheral blood following vaccination and the presence of FIV Env-specific memory CD8+ CTL in the lymph nodes, which persist for up to 1 yr following challenge in the absence of detectable virus. The CTL responses observed in vaccinated protected cats differ qualitatively from those in FIV-infected cats. The latter cats either do not generate a memory CTL response or exhibit a Gag-specific memory CTL response. These results show that the protective immunity observed in whole inactivated virus-vaccinated cats is associated with the induction of high levels of Env-specific CTL activity.

Env-specific CTL predominate in cats protected from feline immunodeficiency virus infection by vaccination

Animal models of HIV-1 have a key role to play in elucidation of the cellular mechanisms responsible for protective immunity. Vaccination of domestic cats with whole inactivated feline immunodeficiency virus (FIV) elicits virus-neutralizing Abs and virus-specific CTL in the peripheral blood and lymphoid organs and affords protection from homologous virus challenge. In the present study we confirm the induction of virus-specific CTL following immunization with whole inactivated FIV vaccine and demonstrate that cats are protected for up to 1 yr following vaccination. Long term protection in vaccinated cats correlates with both higher levels of FIV Env-specific CTL in the peripheral blood following vaccination and the presence of FIV Env-specific memory CD8+ CTL in the lymph nodes, which persist for up to 1 yr following challenge in the absence of detectable virus. The CTL responses observed in vaccinated protected cats differ qualitatively from those in FIV-infected cats. The latter cats either do not generate a memory CTL response or exhibit a Gag-specific memory CTL response. These results show that the protective immunity observed in whole inactivated virus-vaccinated cats is associated with the induction of high levels of Env-specific CTL activity.

Heterogeneity and lability of endogenous digitalis-like substances in the plasma of the toad, Bufo marinus

Three major groups of endogenous digitalis-like substances (EDLS) have been identified in the plasma of the toad, Bufo marinus. One group of compounds, present in fresh plasma, is composed of chromatographically homogeneous polar conjugates, principally bufadienolide 3-sulfates, which exhibit relatively weak Na(+)-K(+)-adenosinetriphosphatase (ATPase) inhibitory activity. A second and larger group of compounds, also found in fresh plasma, includes chromatographically heterogeneous conjugates, which are effective inhibitors of Na(+)-K(+)-ATPase; these compounds possess properties similar to those of bufotoxins. The third group of EDLS consists of free unconjugated bufadienolides, which are also effective Na(+)-K(+)-ATPase inhibitors. These unconjugated bufadienolides are present in relatively low concentrations in fresh toad plasma, but appreciable quantities are enzymatically generated from conjugates (believed to consist principally of bufotoxins) during the in vitro incubation of plasma. We suggest that the extent to which circulating polar EDLS are enzymatically deconjugated in vivo may be important in the regulation of the digitalis-sensitive Na(+)-K(+)-ATPase of toad brain, the only known digitalis-sensitive Na(+)-K(+)-ATPase in the toad.

New medical technologies and clinical practice: a survey of lymphocyte subset monitoring

BACKGROUND

Since its inception in the early 1980s, lymphocyte subset (LS) monitoring of transplant patients has been a controversial technique. The clinical literature is replete with contradictory claims concerning its usefulness. No systematic information is however available on clinicians' attitudes towards the new technology.

METHOD

We carried out a mail survey of the members of The Transplantation Society concerning the availability, use, value, and critical assessment of LS monitoring.

RESULTS

Results show that LS monitoring technology is available in most clinical settings surveyed and is regularly used by about half of the respondents associated with a clinical transplant program. About half of the users obtain diagnostically relevant measurements (T4/T8 ratios), as opposed to measurements related to OKT3 anti-rejection therapy. While claiming that LS measurement is a useful tool, respondents attribute a low average score to the diagnostic value of the technique; about 2/3 believe that its absence would not affect their clinical judgment. Finally, 25% of the respondents send blood for LS measurements although they do not believe the technique is useful.

CONCLUSIONS

The results suggest that research instruments which generate clinical interest may develop clinical-diagnostic routines despite a lack of consensus concerning their usefulness. More importantly, these routines avoid a critical assessment of key notions such as "immune monitoring" which tend to blur the distinction between research and therapy.

Evidence for the expression of two distinct MHC class II DR beta like molecules in the sheep

This study used monoclonal antibodies to sheep MHC class II molecules as well as an L cell transfectant (T8.1) which expresses DRA and DRB genes to show that two distinct DR beta chains are expressed in the sheep. Two anti-beta chain specific monoclonal antibodies VPM37 and VPM43 react with DR antigen but not DQ antigen by ELISA. These two antibodies do not react with the DR beta chain expressed in the T8.1 cell line. Two-dimensional immunoblotting shows that these antibodies recognize a subgroup of the spots recognized by the DR-specific monoclonal antibody VPM57 which does react with the T8.1 beta chain. Amino-terminal sequence analysis of the alpha chain associated with VPM37 beta chain shows that this alpha chain is homologous to the human DR alpha chain strongly indicating that the beta chain is DR-like. VPM37 and VPM43 are shown to be directed against different epitopes on sheep MHC class II molecules so it is highly unlikely that the data can be explained by the presence of post-translational modifications or the existence of a very common allele. These data provide clear evidence for the expression of two distinct DR beta chains in the sheep.

Patterns of major histocompatibility complex class II expression on T cell subsets in different immunological compartments. 1. Expression on resting T cells

In this study we have investigated the expression of major histocompatibility complex (MHC) class II molecules on T cells from various lymphoid compartments in the sheep. Monoclonal antibodies which react specifically with sheep MHC class II molecules homologous to the human DQ and DR molecules have been characterized. These antibodies have been used, together with the monoclonal antibodies specific for sheep CD4-, CD8- and T19-positive T cells, to quantitate DQ and DR expression on T cell subsets in adult and fetal peripheral blood, afferent lymph, lymph node and efferent lymph. The results show that expression of class II by T cells depends on the age of the animal and the physiological location of the T cell. In fetal blood there is no expression of class II on CD8+ or T19+ cells and very low expression on CD4+ T cells. In adult peripheral blood and efferent lymph a significant proportion of cells express DR but not DQ. A very different situation is found in afferent lymph and the peripheral lymph node: in afferent lymph the majority of T cells in all three subsets express both DQ and DR molecules; in the lymph node over 50% of T cells express DR and 30% are DQ+. These results suggest that within all T cell subsets there is a progression from DQ-DR- to DQ-DR+ and DQ+DR+ which correlates with physiological stages of T cell differentiation in vivo.

Detection of thyrotropin binding inhibitory activity in neonatal blood spots

Recent studies have suggested that maternal TSH receptor-blocking antibodies might be of primary etiological importance in some cases of transient congenital hypothyroidism (CH). Because these antibodies are extremely potent, we evaluated the feasibility of identifying babies at risk by using readily available newborn blood spots. Blood spots obtained from 84 normal babies (group 1) and from 354 infants whose initial T4 was less than the tenth percentile for the assay and whose TSH was 40 mU/L or more (group 2) were studied without knowledge of the diagnosis. Blood was eluted from spots overnight and evaluated for [125I]TSH binding inhibition (TBI) to solubilized porcine thyroid membranes. Four spots obtained from 3 group 2 babies, but none of those from the group 1 infants, exhibited TBI activity greater than 3 SD above the normal mean (33.9%). Four additional hypothyroxinemic infants whose mothers had Graves' disease were also negative. Subsequent follow-up revealed that all 3 positive babies had transient CH, and all 3 mothers had primary myxedema. Potent TBI activity was confirmed in the serum of all 3 mothers and in the 2 babies in whom it was evaluated at birth. We conclude that newborn blood spots can be used to detect potent maternal TBI activity, and that this identifies a baby likely to have transient, rather than permanent, CH. Because of their stability and ease of collection and handling, newborn blood spots should offer a convenient tool for future studies aimed at defining in more detail the incidence and clinical characteristics of this unique syndrome.

The optimisation of a novel iodide microassay and its application in an immunoassay for human antibody levels in serum

Radioactive iodine has been used as an antibody label in many immunoassays. The feasibility of using non-radioactive iodine as a label was investigated. A microassay for iodide based on the Sandell-Kolthoff reaction was optimised. It was used to detect iodine-labelled antibody and successfully applied to the detection of human IgG in serum samples. The performance of this assay system compared with enzyme-linked immunosorbent assay using HRP was evaluated.

Fronted velars, palatalized velars, and palatals

Articulatory and acoustic characteristics of various stop consonants in Czech, Hungarian, English, and Russian are compared: velars before back and before front vowels, palatalized velars, and palatals. The articulatory data consist of X-ray tracings and palatograms taken from the literature. The acoustic data consist of LPC spectra of brief intervals at stop release and at vowel onset. These data indicate that all of these consonant types are distinct. Contextual fronting of velars is a gradient effect, less extreme than phonemic palatilization of velars. True palatals are even further forward on the palate and contrast with contextually fronted velars before front vowels. Thus these consonant types should not be collapsed by feature systems.

Thyroid growth immunoglobulins in feline hyperthyroidism

Feline hyperthyroidism bears a strong clinical and pathologic resemblance to toxic nodular goiter in humans. To evaluate whether the observed thyroid growth might be due to circulating thyroid antibodies, as has been postulated in humans, we studied the effect of purified immunoglobulin (Ig) G preparations on a rat thyroid follicular (FRTL-5) cell line. When compared with control, hyperthyroid cat IgG caused significantly increased [3H]-thymidine (Tdr) incorporation into DNA (p less than 0.02) and stimulated cellular proliferation 15-fold. Stimulation of 3H-Tdr incorporation tended to be biphasic and could be inhibited completely by a potent, specific TSH receptor blocking antibody. Hyperthyroid cat IgG also significantly inhibited 125I-bTSH binding to porcine thyroid membranes, an effect that could be reproduced using electrophoretically pure IgG and normal cat thyroid membranes. Unlike its effect on growth, hyperthyroid cat IgG did not stimulate intracellular cAMP, and there was no correlation between thyroid function in vivo and IgG growth-promoting activity in vitro. These data suggest that elevated titers of thyroid growth IgGs, probably acting through the TSH receptor, are present in feline hyperthyroidism and may play a role in goiter formation. Unlike growth, the thyroid hyperfunction observed is not IgG dependent. Further study of feline hyperthyroidism may contribute important insights into human nodular goiter and into the mediation of thyroid growth in general.

Use and detection of nonradioactive iodine-labeled antibodies for immunoassay

Traditionally radioactively labeled iodine has been used as a reporter group for the detection of antibodies in immunoassay. We have recently developed a microassay system for the detection of very low concentrations of iodide which eliminates the need for the use of radiolabeled iodine (O'Kennedy, R. et al. 1989, Anal. Biochem. 179, 138-144). The successful application of this assay for the detection of mouse IgG is described. The performance of this system compared with enzyme immunoassay was evaluated.

Maternal thyroid-blocking immunoglobulins in congenital hypothyroidism

We evaluated 24 mothers whose babies had congenital hypothyroidism (CH) for the presence of immunoglobulins (Igs) that inhibited [125I]bovine TSH binding and blocked TSH-induced growth and function of FRTL-5 cells. Results were compared with those from 2 mothers with known primary myxedema (atrophic thyroiditis) whose babies had transient CH and with normal controls. Only 1 prospectively evaluated CH mother had potent TSH binding inhibitory, growth inhibitory, and function inhibitory IgGs. Further study of this discordant mother's serum indicated that she was hypothyroid, probably due to atrophic thyroiditis. Both mothers with known primary myxedema had blocking IgGs. The thyroid growth-blocking activity was verified by cell count, could be absorbed by and eluted from Staphylococcal protein-A, indicating that it was an IgG, and was not an anti-TSH idiotype. Half-maximal inhibition was similar in the three different assays for thyroid-blocking activity, suggesting that TSH binding inhibitory, growth inhibitory, and function inhibitory IgGs in some patients with primary myxedema may be the same antibody population. There was no correlation with the titer of antimicrosomal antibodies. These data suggest that maternal thyroid-blocking IgGs interacting with the TSH receptor do not play a role in most cases of sporadic CH. Determination of TSH binding inhibitory IgGs, but not antimicrosomal antibodies, is a sensitive screening test for the presence of TSH receptor-blocking antibodies.