The saturation loss for plane parallel ionization chambers at high dose per pulse values

The use of plane parallel ionization chambers with electron beams with high dose per pulse entails dose uncertainties due to the overestimation of the ion recombination factor, k, up to 20% if conventional dosimetric protocols are used. In this work MD-55-2 radiochromic films have been used as reference dosimeters to obtain dose to water per pulse DGAF(w) values for three Novac7 (Hitesys) electron beams of E0 = 5.8 MeV. However, the beam calibration by MD-55-2 films is time consuming and the use of plane parallel chambers is fundamental for a periodic quality control procedure. Three plane parallel chambers have been used and the general formula for the k determination has been tested using the calibration doses, DGAF(w). In particular, consistent ion recombination factors ksat(V0) (with the ion chamber polarized at V0), that follow the Boag theory, have been estimated at different dose per pulse values for the three plane parallel ionization chambers. This means that at present any ion chamber needs a specific ksat (V0) determination by using a reference dosimeter for which the response is independent of the dose rate. An accurate determination of ksat(V0), using a reference quality beam, can be used to determine the dose to water per pulse for electron beams of different quality and geometrical configuration.     

Molecular cloning and complete nucleotide sequence of carnation Italian ringspot tombusvirus genomic and defective interfering RNAs

Summary The complete sequences of genomic and defective interfering (DI) RNAs of carnation Italian ringspot tombusvirus (CIRV) were determined. The genome (4760 nt) has an organization identical to that reported for other tombusviruses except that the pre-readthrough domain of the viral replicase encoded by the 5-proximal open reading frame (ORF) is larger. In particular, the N-terminal region of this protein differs from the corresponding region of the other members of the genusTombusvirus andCarmovirus. Two DI RNAs were found in infected tissues whose sequences were completely derived from genomic RNA. The smaller molecule (474 nt) is contained completely within the larger molecule (656 nt), which suggests that it is derived from the larger one.The nucleotide sequence data reported in this paper will appear in the EMBL, GenBank and DDBJ Nucleotide Database under the accession number X85215.     

Neuropathological Diagnostic Criteria for Creutzfeldt-Jakob Disease (CJD) and Other Human Spongiform Encephalopathies (Prion Diseases)

Neuropathological diagnostic criteria for Creutzfeldt-Jakob disease (CJD) and other human transmissible spongiform encephalopathies (prion diseases) are proposed for the following disease entities: CJD - sporadic, iatrogenic (recognised risk) or familial (same disease in 1st degree relative): spongiform encephalopathy in cerebral and/or cerebellar cortex and/or subcortical grey matter; or encephalopathy with prion protein (PrP) immuno-reactivity (plaque and/or diffuse synaptic and/or patchy/perivacuolar types). Gerstmann-Sträussler-Scheinker disease (GSS) (in family with dominantly inherited progressive ataxia and/or dementia): encephalo(myelo)pathy with multicentric PrP plaques. Familial fatal insomnia (FFI) (in member of a family with PRNP178 mutation): thalamic degeneration, variable spongiform change in cerebrum. Kuru (in the Fore population). Without PrP data, the crucial feature is the spongiform change accompanied by neuronal loss and gliosis. This spongiform change is characterised by diffuse or focally clustered small round or oval vacuoles in the neuropil of the deep cortical layers, cerebellar cortex or subcortical grey matter, which might become confluent. Spongiform change should not be confused with non-specific spon-giosis. This includes status spongiosus (“spongiform state”), comprising irregular cavities in gliotic neuropil following extensive neuronal loss (including also lesions of “burnt-out” CJD), “spongy” changes in brain oedema and metabolic encephalopathies, and artefacts such as superficial cortical, perineuronal, or perivascular vacuolation; focal changes indistinguishable from spongiform change may occur in some cases of Alzheimer's and diffuse Lewy body diseases. Very rare cases might not be diagnosed by these criteria. Then confirmation must be sought by additional techniques such as PrP immunoblotting, preparations for electron microscopic examination of scrapie associated fibrils (SAF), molecular biologic studies, or experimental transmission.     

Impaired macrophage phagocytosis of apoptotic neutrophils in patients with human immunodeficiency virus type 1 infection

Dysfunction of neutrophils (polymorphonuclear leukocytes [PMNL]) and macrophagic cells occurs as a consequence of human immunodeficiency virus type 1 (HIV-1) infection. Macrophages contribute to the resolution of early inflammation ingesting PMNL apoptotic bodies. This study investigated macrophage ability to phagocytose PMNL apoptotic bodies in patients with HIV-1 infection in comparison with uninfected individuals and the effect of HIV Nef protein on apoptotic body phagocytosis to determine if phagocytic activity is impaired by HIV infection. Monocytes/macrophages were isolated from 10 HIV-1-infected patients and from five healthy volunteers, whereas PMNL were isolated from healthy volunteers. Macrophage phagocytosis of apoptotic PMNL was determined by staining of apoptotic bodies with fluorescein-conjugated concanavalin A or with fluorescein-labeled phalloidin. Our data show significant impairment of PMNL apoptotic body macrophage phagocytosis in subjects with HIV-1 infection presenting a concentration of CD4(+) T lymphocytes of >200/mm(3) and in particular in those with <200 CD4(+) T lymphocyte cells/mm(3). In addition, HIV-1 recombinant Nef protein is able to decrease phagocytosis of apoptotic PMNL from normal human macrophages in a dose-dependent manner. The results of our study suggest that impaired macrophage phagocytosis of PMNL apoptotic bodies may contribute to the persistence of the inflammatory state in HIV-infected subjects, especially during opportunistic infections that are often favored by defective phagocytic activity.     

Apparent genotype–phenotype correlation in childhood,adolescent, and adult Chediak‐Higashi syndrome

Chediak‐Higashi syndrome (CHS) is a rare autosomal recessive disorder characterized by severe immunologic defects, reduced pigmentation, bleeding tendency, and progressive neurological dysfunction. Most patients present in early childhood and die unless treated by bone marrow transplantation. About 10–15% of patients exhibit a much milder clinical phenotype and survive to adulthood, but develop progressive and often fatal neurological dysfunction. Very rare patients exhibit an intermediate adolescent CHS phenotype, presenting with severe infections in early childhood, but a milder course by adolescence, with no accelerated phase. Here, we describe the organization and genomic DNA sequence of the CHS1 gene and mutation analysis of 21 unrelated patients with the childhood, adolescent, and adult forms of CHS. In patients with severe childhood CHS, we found only functionally null mutant CHS1 alleles, whereas in patients with the adolescent and adult forms of CHS we also found missense mutant alleles that likely encode CHS1 polypeptides with partial function. Together, these results suggest an allelic genotype–phenotype relationship among the various clinical forms of CHS. © 2002 Wiley‐Liss, Inc.     

A radio (51Cr) micro-tube leukocyte adherence inhibition assay: specific tumor-associated immunity in 3 murine tumor systems.

A radio (51Cr) micro-tube leukocyte adherence inhibition assay is described. In this study, murine mononuclear cells were labeled with 51Cr, plated into tissue culture plates with different tumor extracts and counts/min (cpm) of the non-adherent cells were used as a parameter of adherence inhibition. This assay was used to measure anti-tumor immunity, in vitro, in 3 murine tumor systems: MCA-38 colon adenocarcinoma, L1210 lymphoma and P815 mastocytoma. Tumor immunity was detected using 3 doses (0.01-0.001 mg/ml) of tumor extract in the MCA-38 tumor model, and using 2 doses (0.1-0.05 mg/ml) of tumor extract in both the L1210 and P815 tumor models. It was observed that specific tumor-associated adherence inhibition could be measured in the MCA-38 tumor model between days 7 and 22 of tumor growth and in the L1210 and P815 tumor models between days 7 and 17 of tumor growth. The radio-LAI assay described is an easy, specific and reproducible way to measure tumor-associated adherence inhibition, in vitro.     

Serious conduct problems in the children of adolescent mothers: disentangling confounded correlations

Early motherhood (less than 20 years of age) was found to be significantly correlated (r = .33) with the number of DSM-III symptoms of conduct disorder in a sample of 253 boys aged 6-13 years who had been referred to outpatient clinics. The following models were compared using path analysis: (a) Teenage motherhood, parental antisocial personality, and SES each contribute uniquely to the prediction of childhood conduct problems; (b) teenage motherhood mediates the association of SES and parental antisocial personality with child conduct problems; and (c) teenage motherhood is spuriously related with child conduct problems because of common associations with SES and parental antisocial personality. Model (c) best fit our data. Similar results were obtained whether maternal age at the birth of the firstborn child or the proband child was used to define maternal age and when teenage motherhood was defined as giving birth at less than 18 years.     

The stage-specific 90-kilodalton surface antigen of metacyclic trypomastigotes of Trypanosoma cruzi

The 90-kDa antigen, previously identified by the monoclonal antibody 1G7 to be a stage-specific surface protein of metacyclic trypomastigotes of Trypanosoma cruzi, has been further characterized in this study. Experiments of metabolic labeling with [35S]methionine, [2H]mannose and [3H]galactose revealed that the 90-kDa antigen is the main glycoprotein synthesized by metacyclic forms (G strain). Through pulse-chase experiments with [35S]methionine-labeled metacyclic trypomastigotes, it was found that the antigen is synthesized as a 75-kDa precursor polypeptide that is rapidly processed to the mature 90-kDa molecule. When metacyclic trypomastigotes were treated with tunicamycin, the production of 90-kDa antigen was greatly diminished, and the 75-kDa species, which was also expressed on the cell surface, accumulated. Concanavalin A bound strongly to the 90-kDa antigen, but failed to recognize the 75-kDa polypeptide. Treatment of neuraminidase had no effect on the 90-kDa antigen, whereas digestion by endoglycosidase H generated a polypeptide of 82 kDa. Altogether these data indicate that the 90-kDa antigen is a glycoprotein containing N-linked oligosaccharide side chains of the high-mannose type. The 90-kDa glycoprotein may be involved in the process of host cell invasion, since the internalization of metacyclic forms into Vero cells was partially inhibited by monoclonal antibody 1G7.