Down-modulation of CD4+ T helper type 2 and type 0 cells by T helper type 1 cells via Fas/Fasligand interaction

Fas was recently demonstrated to be the major target molecule engaged by CD4⁺ cytolytic T lymphocytes (CTL). We examined Fas expression on various cloned T cell subpopulations and their susceptibility to lysis by CD4⁺ or CD8⁺ CTL. A reciprocal relationship in Fas and Fas-ligand expression was observed in CD4⁺ T helper (Th)1- and Th2-type clones, and Fas mRNA was predominantly detected in Th2 clones, whereas Fas-ligand mRNA was principally found in Th1 clones. The two Th0 clones tested expressed both Fas and Fas-ligand, but only one exhibited cytolytic activity, whereas both were sensitive to CD4-mediated lysis. A functional consequence of the inverse Fas-Fas-ligand expression pattern was that Th2 and Th0 cells were sensitive to lysis by both Th1 CD4⁺ CTL and a CD8⁺ CTL clone in a Fas-dependent manner. These results suggest that cytolytic CD4⁺ Th1 cells may play an immunomodulatory role, regulating a Th2/Th0 response by Fas-mediated lysis.     

Stage-specific protein synthesis by asexual blood stage parasites of Plasmodium falciparum

Highly synchronised cultures of cloned Plasmodium falciparum (clone T9-94) were metabolically radiolabelled with [35S]methionine during eight consecutive non-overlapping intervals, while parasites developed from young rings to mature schizonts. Analysis of equal amounts of trichloroacetic acid precipitable radioactivity from each interval by sodium dodecyl sulphate-polyacrylamide gel electrophoresis fluorography allowed the stage specificity of protein synthesis to be investigated. More than forty polypeptides with molecular weights of 20 000 to 200 000 can be distinguished. While some proteins are synthesised throughout erythrocytic schizogony many are shown to be stage-specific. Among these are a range of high molecular weight proteins synthesised only during nuclear division. Detailed morphological information permits correlations to be made between synthesis of particular polypeptides and parasite structure.     

Estimation of the parameters of the relationship between power and time to exhaustion from a single ramp test.

This study aimed to estimate the power/time relationship from a single ramp test (RT) assuming critical power (Pc) from ventilatory threshold (VT) and energy reserve (W') from total work during RT These estimates from single RT were compared to those from a series of 4 constant power exercises (CPT) and from a series of 4 RT. Only W' from CPT was higher than from the series of RT and from single RT using VT (p < 0.05).     

Genetic and clinical characterization of patients with an interstitial duplication 15q11-q13, emphasizing behavioral phenotype and response to treatment

The clinical significance of an interstitial duplication of (15)(q11-q13) remains unclear and controversial. The reported phenotypes vary widely and appear to be influenced by the parent of origin of the duplication. Aside from cases of dup(15) reported with autism, the behavioral phenotype of individuals with dup(15) has not been described. We present three families, two with intrachromosomal duplication (15)(q11-q13) ascertained because of developmental delay in a relative. Two families show clear evidence of multigenerational maternal inheritance. The individuals discussed in this paper have minor anomalies and developmental delays. In addition, we describe a behavioral phenotype which often includes attention deficit hyperactivity disorder (ADHD) and autistic spectrum disorder. Responses to medications used to manage these behaviors are also described, including a positive response to methylphenidate and a poor response to fluoxetine. The duplication in each presenting individual, and available family members, was investigated utilizing cytogenetic and molecular techniques including high resolution cytogenetics, fluorescence in situ hybridization (FISH), DNA methylation studies, and quantitative fluorescence PCR. High resolution cytogenetic techniques alone missed some cases, demonstrating the need to confirm results with other methods.     

Problems with measuring alexithymia

Research evaluating the relationship of alexithymia to medical and psychiatric disorders has been compromised by the poor psychometric properties of the instruments that have been used to measure alexithymia. This study evaluated the psychometric properties of a recently introduced measure of alexithymia--the revised Schalling-Sifneos Personality Scale (SSPS-R). While the factor structure of the SSPS-R was found to be reasonably congruent with the theoretical domains of the alexithymia construct, the scale lacked homogeneity and internal reliability. These results are compared with the reliability and validity of other available measures of alexithymia. Recommendations are offered for the improved assessment of alexithymia in future research studies.     

Cationization of bovine serum albumin alters its conformation as well as its charge

The molecular charge on bovine serum albumin (BSA) was modified by substituting carboxyl groups on the protein with ethylenediamine, thereby producing a highly cationic derivative with a pI of 9.3 to 9.5. Gel-filtration studies showed that the molecular weight of BSA was not significantly altered after cationization. When the cationized BSA was administered to rabbits using a chronic serum sickness schedule of injections, the animals developed a membranous glomerulopathy similar to the human disease, except that approximately one-third of the animals also showed focal and segmental endocapillary proliferation. Comparison of the circular dichroism spectra of native and cationized BSA showed that the substitution of the carboxyl groups resulted in a 50% reduction in the alpha-helical content of the native molecule. This conformational change should be considered as a possible determinant of the different immune response and immunopathology associated with the cationized molecule compared with native BSA.     

Sprouting of mossy fibers and presynaptic inhibition by group II metabotropic glutamate receptors in pilocarpine-treated rat hippocampal slice cultures

Mossy fibre sprouting (MFS) is a phenomenon observed in the epileptic hippocampus. We have studied MFS, in 7, 14 and 21 day in vitro (DIV) organotypic slice cultures, or in slice cultures treated with pilocarpine (0.5 mM) or pilocarpine and atropine (0.1 mM or 0.5 mM) for 48-72 h at 5 DIV and tested at 21 DIV. Acute application of pilocarpine directly activated hilar neurons and elicited epileptic-like discharges in CA3 pyramids and mossy cells of 5-8 DIV cultures, without causing substantial cell death, as assessed by lactate dehydrogenase measurements. Timm staining revealed increases in MFS in chronic pilocarpine-treated cultures, which was prevented by prior application of atropine. Extracellular synaptic responses were recorded in the granule cell layer and elicited by antidromic mossy fibre stimulation. The GABA(A) antagonist 6-imino-3-(4-methoxyphenyl)-1(6H)-pyridazinebutanoic acid (1 microM) induced a greater increase in the coastline bursting index in pilocarpine-treated cultures than in 21 DIV controls. However, there was no significant increase in the frequency of spontaneous or miniature synaptic events recorded in granule cells from pilocarpine-treated cultures. Granule cells were filled with biocytin and morphometric analysis revealed that the length of axon collaterals in the granule and molecular layer was longer in pilocarpine-treated cultures than in 21 DIV controls. Dual recordings between granule cells and between granule and hilar neurons showed that pilocarpine-treated cultures had a larger proportion of monosynaptic and polysynaptic connections. The group II metabotropic glutamate receptor (mGluR) agonist LY354740 (0.5 microM) suppressed excitatory but not inhibitory monosynaptic currents. LY354740 also inhibited antidromically evoked action currents in granule cells from pilocarpine- and to a lesser extent in pilocarpine and atropine-treated cultures, suggesting that group II mGluRs can reside along the axon and suppress action potential invasion. We provide direct evidence for the development of functional MFS and suggest a novel, axonal mechanism by which presynaptic group II mGluRs can inhibit selected synapses.     

Endocytosis of horseradish peroxidase-poly-lysine conjugate by glomerular epithelial cells: an in vivo study

Native horseradish peroxidase (HRP) is known to pass rapidly through glomeruli when injected into rats. We have found that a conjugate of HRP with poly-lysine is readily endocytosed by glomerular epithelial cells (GEC). We have used this conjugate to study the GEC endocytotic process in male Wistar rats. The conjugate has an approximate molecular weight of 55-58,000, a pI of greater than 10.0, and almost the same secondary conformation as HRP; it does not increase urinary protein excretion significantly or alter the morphology of the renal glomeruli. After intravenous injection of the conjugate, it could be found in the GBM from 1 min to 4 h. At 1 min, it was evenly distributed on GEC foot processes and plasma membrane. GEC start to take up the conjugate from 1 min post-injection, by cellular membrane invagination. This reached a maximum at 4 h. Some of the endocytosed conjugate passed to lysosomes from the endosomal system. The amount of peroxidase demonstrable in the glomerular epithelial cells was considerably reduced by 24 h.