A review of the taxonomy and systematics of the pentastomid genus Raillietiella Sambon, 1910 with a description of a new species

Systematic Parasitology - Four previously established Raillietiella spp. are redescribed. Two of these, R. kochi and R. shipleyi from African monitor lizards, cannot be reliably separated, R....     

Thyrotoxicosis: relations between clinical state and biochemical changes during carbimazole treatment.

The relation between clinical and biochemical changes in thyrotoxicosis were studied in 12 patients with Graves''s disease who were being treated with carbimazole. Clinical assessment (using the Crooks-Wayne index) was combined with the measurement of free thyroxine and triiodothyronine indices (FT4I and FT3I) and the assessment of two tissue markers of thyroid hormone action--sex-hormone-binding globulin (SHBG) levels and the thyrotrophin responses to TRH. In general the FT4I and FT3I fell rapidly once treatment was started, and returned to normal in one to four weeks, followed shortly by SHBG levels. The thyrotrophin response returned at this time in two patients, who still had borderline high levels of FT3I and SHBG. The clinical score fell more slowly and variably and was less closely related to any of the biochemical indices than these were to each other. During the early phase of treatment with antithyroid drug the clinical evaluation may be an unreliable indicator of persisting thyroid hormone excess, and when the patient seems clinically but not biochemically thyrotoxic the symptoms should be treated on their own merits with beta-blocking drugs and not with increased doses of antithyroid drugs.     

Heritability of Quasi-Continuous Skeletal Traits in a Randombred Population of House Mice

Heritabilities of 11 quasi-continuous skeletal traits were estimated in randombred house mice of three separate ages (1, 3, and 5 months). Three separate methods—regression, maximum likelihood correlation, and Falconer's Method—were used to obtain heritabilities for each of the separate age groups. Significant differences in the incidences of seven of the skeletal traits were found among ages, but they did not affect the heritability estimates, these estimates being pooled over ages. Heritabilities calculated from female parents were consistently higher (by about 13%) than those from male parents, indicating the presence of maternal effects. Mid-parent estimates made by all three methods gave very similar mean levels (0.17 — 0.20). Although low, this level compared favorably with that expected on the basis of previously estimated rates of accumulation of genetic variance. Maternal effects estimated from full sib correlations averaged 0.08.     

Ultrastructure of Porocephalus crotali (Pentastomida) cuticle with phylogenetic implications.

The cuticle of P. crotali is pro-arthropodan, composed of an epi-, exo-, and endocuticle. The exo- and endocuticles are separated by a 600-A intermediate cuticular zone. The epicuticle is homogeneous and varies from 100 to 350 A in thickness. The exocuticle varies from 2 to eight mu in thickness and is divided into superficial and deep exocuticular zones. The endocuticle is lamellate and varies from 8 to 30 mu in thickness. Lamellae result from ordered parabolic orientations of 40-A chitin fibrils. Underlying cells lack a basement membrane. Subcuticular muscle cells insert tonofibrils directly into the adjacent endocuticle. No apodemes or apophyses occur.     

Factors associated with the development of cross-reactive neutralizing antibodies during human immunodeficiency virus type 1 infection

The characterization of the cross-reactive, or heterologous, neutralizing antibody responses developed during human immunodeficiency virus type 1 (HIV-1) infection and the identification of factors associated with their generation are relevant to the development of an HIV vaccine. We report that in healthy HIV-positive, antiretroviral-naïve subjects, the breadth of plasma heterologous neutralizing antibody responses correlates with the time since infection, plasma viremia levels, and the binding avidity of anti-Env antibodies. Anti-CD4-binding site antibodies are responsible for the exceptionally broad cross-neutralizing antibody responses recorded only in rare plasma samples. However, in most cases examined, antibodies to the variable regions and to the CD4-binding site of Env modestly contributed in defining the overall breadth of these responses. Plasmas with broad cross-neutralizing antibody responses were identified that targeted the gp120 subunit, but their precise epitopes mapped outside the variable regions and the CD4-binding site. Finally, although several plasmas were identified with cross-neutralizing antibody responses that were not directed against gp120, only one plasma with a moderate breadth of heterologous neutralizing antibody responses contained cross-reactive neutralizing antibodies against the 4E10 epitope, which is within the gp41 transmembrane subunit. Overall, our study indicates that more than one pathway leads to the development of broad cross-reactive neutralizing antibodies during HIV infection and that the virus continuously escapes their action.     

Oral levodopa rescues retinal morphology and visual function in a murine model of human albinism

Albinism is a group of disorders characterized by pigment deficiency and abnormal retinal development. Despite being a common cause for visual impairment worldwide, there is a paucity of treatments and patients typically suffer lifelong visual disability. Residual plasticity of the developing retina in young children with albinism has been demonstrated, suggesting a post‐natal window for therapeutic rescue. L‐3, 4 dihydroxyphenylalanine (L‐DOPA), a key signalling molecule which is essential for normal retinal development, is known to be deficient in albinism. In this study, we demonstrate for the first time that post‐natal L‐DOPA supplementation can rescue retinal development, morphology and visual function in a murine model of human albinism, but only if administered from birth or 15 days post‐natal age.     

Regulation of purine hydroxylase and xanthine dehydrogenase from Clostridium purinolyticum in response to purines, selenium, and molybdenum

The discovery that two distinct enzyme catalysts, purine hydroxylase (PH) and xanthine dehydrogenase (XDH), are required for the overall conversion of hypoxanthine to uric acid by Clostridium purinolyticum was unexpected. In this reaction sequence, hypoxanthine is hydroxylated to xanthine by PH and then xanthine is hydroxylated to uric acid by XDH. PH and XDH, which contain a labile selenium cofactor in addition to a molybdenum cofactor, flavin adenine dinucleotide, and FeS centers, were purified and partially characterized as reported previously. In the present study, the activities of these two enzymes were measured in cells grown in media containing various concentrations of selenite, molybdate, and various purine substrates. The levels of PH protein in extracts were determined by immunoblot assay. The amount of PH protein, as well as the specific activities of PH and XDH, increased when either selenite or molybdate was added to the culture medium. PH levels were highest in the cells cultured in the presence of either adenine or purine. XDH activity increased dramatically in cells grown with either xanthine or uric acid. The apparent increases in protein levels and activities of PH and XDH in response to selenium, molybdenum, and purine substrates demonstrate that these enzymes are tightly regulated in response to these nutrients.