University of Lodz an electron spectrometer--a new conversion-electron spectrometer for "in-beam" measurements.

The designed and constructed at the University of Lodz an electron spectrometer is devoted to "in-beam" measurements. The apparatus is characterized by high efficiency up to 9%, good energy resolution (FWHM = 5 keV at 482 keV) and, what is very important good suppression of delta electrons, positrons, and photons emitted by the targets. This achievement was obtained using a combination of magnetic field in two different layouts: perpendicular and parallel to the axis of the spectrometer being orthogonal to the beamline. The conversion-electron spectrometer coupled to the EAGLE array was successfully tested in an "in-beam" measurement.

Characterization of solid state nuclear track detectors of the polyallyl-diglycol-carbonate (CR-39/PM-355) type for light charged particle spectroscopy.

This paper presents a method which uses the characteristics of the etch pits induced in a polyallyl-diglycol-carbonate (PADC) detector of the CR-39/PM-355 type to estimate particle energy. This method is based on the data provided by a semiautomatic system that selects tracks according to two parameters, crater diameters, and mean gray level values. In this paper we used the results of the calibration measurements that were obtained in our laboratory in the period 2000-2014. Combining the information on the two parameters it is possible to determine unambiguously the incident projectile energy values. The paper presents the results of an attempt to estimate the energy resolution of the method when analyzing the tracks produced in the CR-39/PM-355 detector by energetic ions such as alpha particles, protons, and deuterons. We discuss the energy resolution of the measurement of light charged particle energy which is based on the parameters (crater diameter and mean gray level value) of tracks induced in solid state nuclear track detectors of the PADC type.

Investigations of protons passing through the CR-39/PM-355 type of solid state nuclear track detectors.

Solid State Nuclear Track Detectors of the CR-39∕PM-355 type were irradiated with protons with energies in the range from 0.2 to 8.5 MeV. Their intensities and energies were controlled by a Si surface barrier detector located in an accelerator scattering chamber. The ranges of protons with energies of 6-7 MeV were comparable to the thickness of the PM-355 track detectors. Latent tracks in the polymeric detectors were chemically etched under standard conditions to develop the tracks. Standard optical microscope and scanning electron microscopy techniques were used for surface morphology characterization.

Influence of high temperature on solid state nuclear track detector parameters.

This work concerns the influence of high temperatures on tracks induced in solid state nuclear track detectors of the CR-39/PM-355 type. In order to investigate this effect some samples of the detectors were irradiated with energetic protons and α particles and subsequently heated under controlled temperatures for different periods of time. After heating the samples were etched and the track evolution was analyzed using an optical microscope. The bulk etch rate V(B) of the PM-355 material was also determined as a function of heating temperature. The track etch rate V(T) values were estimated for craters induced by protons and α particles from track diameter measurement as a function of heating temperature.

Cell survival and chromosomal aberrations in CHO-K1 cells irradiated by carbon ions.

Chinese hamster ovary CHO-K1 cells were exposed to high LET (12)C-beam (LET: 830 keV/microm) in the dose range of 0-6 Gy and to (60)Co irradiation and the RBE value was obtained. Effects of (12)C-beam exposure on cell survival and chromosomal aberrations were calculated. The chromosomal aberration data were fitted with linear equation. The distribution of aberration in cells was examined with a standard u-test and used to evaluate the data according to Poisson probabilities. The variance to the mean ratio sigma(2)/Y and the dispersion index (u) were determined. Overdispersion was significant (p<0.05) when the value of u exceeded 1.96.

An irradiation facility with a horizontal beam for radiobiological studies.

A facility with a horizontal beam for radiobiological experiments with heavy ions has been designed and constructed at the Heavy Ion Laboratory in Warsaw University. The facility is optimal to investigate the radiobiological effects of charged heavy particles on a cellular or molecular level as in the region of the Bragg peak.

Efficacy of 1% permethrin for the treatment of head louse infestations among Kosovar refugees.

We assessed the prevalence of head louse infestation and the effectiveness of 1% permethrin against head lice in Kosovar refugees. A currently infested case was defined as a person with observable crawling lice (adults or nymphs) or a person with nits on the hair shaft within a quarter-inch of the scalp. Of the 1,051 refugees screened upon arrival in the United States, 107 (10%) were infested. Crawling lice (adults or nymphs) were observed on 62 (6%) of the individuals examined. Refugees with crawling lice were treated with a pediculicide containing 1% permethrin. Of these, 57 were reexamined the next day. Twenty of the 57 individuals were reexamined 7 days after treatment. No crawling lice were found on any of the refugees examined after treatment. We conclude that 1% permethrin treatment was effective in louse control in this refugee population.

Identification of T cell ligands in a library of peptides covalently attached to HLA-DR4.

While T cells have been clearly implicated in a number of disease processes including autoimmunity, graft rejection, and atypical immune responses, the precise Ags recognized by the pathogenic T cells have often been difficult to identify. This has particularly been true for MHC class II-restricted CD4+ T cells. Although such cells can be demonstrated to have undergone clonal expansion at sites of pathology, they are frequently difficult to establish as stable T cell clones. Furthermore, in general, larger peptides in higher concentrations are required to stimulate CD4+ T cells than CD8+ T cells, which makes some of the techniques developed to identify CD8+ T cell Ags impractical. To circumvent some of these problems, we developed a model system consisting of two parts. The first part involves the construction of an indicator T cell hybridoma expressing a chimeric TCR comprised of murine constant regions and human variable regions specific for influenza hemagglutinin 307-319 presented by DR4. The second part consists of a library of fibroblasts each expressing multiple peptides as amino terminal covalent extensions of the beta-chain of HLA-DR4 (DRA1*0101, DRB1*0401). Using this model system, we screened approximately 100, 000 peptides and identified three novel peptides stimulatory for the HA1.7 TCR. While there is some convergence at residues known to be important for T cell recognition, all three peptides differ markedly from each other and bear little resemblance to wild-type hemagglutinin 307-319.

The 1-month outcome of patients with a low probability Technegas ventilation/perfusion lung scan.

The objective was to study the 1-month outcome of patients who had a low probability ventilation/perfusion lung scan using Technegas radioaerosol as the inhalational agent and who did not receive anticoagulation. One hundred consecutive patients with suspected pulmonary embolism were studied retrospectively. Their Technegas lung scans were classified by two blinded and independent nuclear medicine physicians and the medical records of all patients with a low probability scan were reviewed. One hundred inpatients (42 males and 58 females) with a mean age of 63 years were studied. The three most common clinical presentations leading to lung scintigraphy were unexplained dyspnoea (30 cases), unexplained dyspnoea with pleuritic chest pain (26 cases) and pleuritic chest pain only (15 cases). Nine patients had been judged by their managing medical team to have a high clinical probability of true pulmonary embolism, 32 had an intermediate probability clinical presentation and 59 a low clinical probability of pulmonary embolism. None of the 100 patients experienced further episodes of suspected or proven pulmonary embolism during the follow-up period. Six patients died. In none of them was pulmonary embolism either the cause of or a major contributing factor to death. The finding of a low probability scan using Technegas as the ventilation scintigram agent of choice describes a group of patients who, even in the absence of therapeutic anticoagulation, have a favourable 1-month outcome free of either true or suspected clinical pulmonary embolism. Invasive, pulmonary angiography-based diagnostic strategies may not be needed in this group of patients.

Tissue distribution of Mtv-7-like exogenous retroviral transcripts and clonal deletion of V beta 6+ T cells in Mls-1b BALB/c mice.

We have previously described an Mls-1a-like clonal deletion of mature CD4+ T cells which express V beta 6 and V beta 8.1 chains of the TCR in half of the mice of a BALB/c, Mls-1b colony (BALB/c IC). This occurs in the absence of the Mtv-7 provirus which is responsible for the clonal deletion in Mls-1a mice. We developed a polymerase chain reaction assay in order to study the presence of retroviral transcripts homologous to the viral superantigen gene (vSAG) of Mtv-7 and Mtv-6 in various tissues. Mtv-7 homologous transcripts were present in the mammary glands of lactating BALB/c IC mice and in the thymuses and/or spleens of BALB/c IC virgin mice with deletion of V beta 6+ lymph node T cells, and not in BALB/c IC with normal V beta 6 expression. These results indicate that this BALB/c colony is infected with an exogenous mouse mammary tumour virus (MMTV) whose vSAG is similar to Mtv-7, as recently reported. Thymectomies performed at 4-5 weeks of age (at least 4 weeks before detection of clonal deletion), did not affect the occurrence of clonal deletion in peripheral lymph nodes when tested 20 weeks later. This suggests that clonal deletion can be achieved without further intrathymic contact with the antigen. Since MMTV is transmitted through milk and is likely to be present in the gut, we evaluated the percentage of V beta 6+CD4+ T cells within the gut intraepithelial lymphocyte (IEL) population. Mice with normal V beta 6 expression in lymph nodes may show partial deletion of V beta 6+CD4+ IEL.(ABSTRACT TRUNCATED AT 250 WORDS)

The mouse mammary tumour virus long terminal repeat encodes a type II transmembrane glycoprotein.

Superantigens are products of bacterial or viral origin which stimulate large numbers of T cells as a consequence of the interaction of particular V beta chains of the T cell receptor with class II major histocompatibility complex (MHC) molecules and superantigen on the stimulating cell. The Minor lymphocyte stimulatory (Mls) antigens, originally discovered as strong lymphocyte stimulatory determinants in vitro and subsequently shown to delete T cells expressing specific V beta chains during development, have recently been shown to be genetically linked to endogenous mouse mammary tumour viruses (MTVs). This stimulation is effectuated by an unidentified product encoded by an open reading frame (orf) present in the 3' long terminal repeat (LTR) of MTVs. Using in vitro translation in the presence of rough microsomal vesicles, we show that (i) the orf of MTV encodes a type II transmembrane glycoprotein (N-terminus intracellular, C-terminus extracytoplasmic), and (ii) a cotranslationally secreted orf protein is not produced. We have also isolated and sequenced several endogenous MTV orfs (MTV-1, MTV-6 and MTV-13) which are involved in the deletion of V beta-bearing T cells; each of these sequences are nearly identical to each other. These observations, together with sequence comparisons of several orf genes, lead to a model of action of viral superantigens.

Rearrangement by inversion of a T-cell receptor delta variable region gene located 3' of the delta constant region gene.

We have located a T-cell receptor variable (V) delta gene segment immediately 3' of the delta constant (C) region gene and 5' to the known joining (J) alpha gene segments. This V delta gene is in the opposite transcriptional polarity to C delta and has rearranged to C delta by inversion in a gamma/delta-expressing hybridoma, DN7.3. This V delta gene is commonly rearranged in adult but not fetal gamma/delta-expressing thymocytes and has not been observed among alpha gene rearrangements reported to date. The reciprocal joining sequence isolated from this cell line contains N region nucleotides between the recombination signal sequences, in contrast to previously analyzed reciprocal joints. The results are discussed in the context of models accounting for ordered V gene usage during lymphocyte development.

Predominant variable region gene usage by gamma/delta T cell receptor-bearing cells in the adult thymus.

Previous studies have indicated that the diversity of gamma genes expressed by gamma/delta-bearing murine T cells is limited, but comparable information concerning the expressed diversity of delta genes is lacking. In this study, we have investigated the rearrangement and expression of delta and gamma genes in T cell hybridomas that express gamma/delta T cell receptors. Three productive delta chain cDNA clones were isolated (delta 7.3, delta 7.1, and delta 2.3) that encode new variable region sequences. Two of the delta cDNAs differ significantly from those observed in the V alpha repertoire. In addition, one cDNA expressed a new J delta region (J delta 2), which was localized between J delta 1 and C delta genes. Using these and other delta gene probes and gamma gene probes, we found that five independent hybridomas expressed four different V delta s and three different V gamma s. However, analysis of an enriched population of gamma/delta-expressing cells from the adult thymus suggests that only a few V delta genes and one V gamma gene are used by the majority of the cells. These results suggest that important components of receptor chain that contribute to specificity (i.e., the germline V gene sequences) are relatively nondiverse in the thymic gamma/delta population.

Expression of HLA-DR antigen in human class II mutant B-cell lines by double infection with retrovirus vectors.

A new retrovirus vector containing the gene for hygromycin B resistance (hyg) as a selectable marker under the control of an internal simian virus 40 promoter was constructed. It was used, together with an analogous previously described vector, DO1, which contains the gene for G418 resistance, to introduce and express the genes for the two chains of a human class II major histocompatibility complex antigen in NIH 3T3 cells. In addition, these vectors were used to express DR antigens in two human mutant B-lymphoblastoid cell lines, one of which was deleted for both alleles of the DR alpha gene and the other of which expressed no class II antigens because of a genetic defect in a putative trans-acting regulatory factor.

Expression of human class II major histocompatibility complex antigens using retrovirus vectors.

Retrovirus vectors [direct orientation (DO) vectors] that permit the simultaneous expression of an inserted protein-coding sequence and a dominant-acting selectable marker have been constructed. In these vectors, an internal simian virus 40 or human metallothionein promoter sequence serves to drive the expression of the bacterial neomycin phosphotransferase or guanine-xanthine phosphoribosyltransferase genes, whereas the viral long terminal repeat sequences are utilized to promote expression of inserted sequences. In some of the vectors, the viral 5' splice site, normally used in the biogenesis of the subgenomic env-encoding mRNA, has been eliminated. These vectors yield high transient and stable titers of virus after transfection of viral packaging cell lines, show little or no depression of virus titer with a variety of inserts, and faithfully transmit recombinant proviral sequences to recipient cells. To characterize the expression potential of these vectors, a variety of inserts encoding the alpha and beta subunits of the human major histocompatibility complex class II antigen HLA-DR have been introduced into these vectors. NIH 3T3 cells infected by viruses containing HLA-DR alpha or beta cDNAs express these proteins as shown by immunoprecipitation of metabolically labeled extracts. In addition, through the sequential infection of cells with retrovirus constructions expressing two different selectable markers, both subunits of the class II antigen have been introduced into NIH 3T3 cells. Such infected cells express HLA-DR molecules at the cell surface.

Structure and expression of HLA-DQ alpha and -DX alpha genes: interallelic alternate splicing of the HLA-DQ alpha gene and functional splicing of the HLA-DQ alpha gene using a retroviral vector.

The nucleotide sequences of the two closely related HLA-DQ alpha and HLA-DX alpha genes have been determined. Exons coding for the signal peptide, alpha 2 and transmembrane domains are 94-99% homologous, whereas the alpha 1 exon and the promoter region have diverged as much as or more than introns and the 3' untranslated region. The promoter regions of both genes contain two short sequences thought to be important for regulation of transcription by gamma-interferon. Transfection studies established that the DQ alpha and DQ beta genes encode the HLA-DQ antigen. Transcripts of varying length are produced from different alleles as the result of the use of alternate splice and polyadenylation signals at the 3' end of the DQ alpha gene. Thus typing at the DQ alpha locus can be achieved by Northern blot analysis. No transcript of DX alpha was detected in B lymphocytes. The DX alpha gene was accurately spliced when introduced into a retroviral vector, suggesting that the lack of expression of DX alpha is not due to aberrant splice signals.

Genetic complexity and expression of human class II histocompatibility antigens.

The genes encoding nearly all of the serologically defined class II antigens of the major histocompatibility complex have been isolated. Three class II loci have been studied in great detail. The DR region contains a single alpha gene and 3 beta chain genes, 1 of which is a pseudogene. The DR alpha chain gene has been linked to a DR beta gene which encodes a beta protein which contains the serological determinant MT3. A second cosmid cluster contains 2 beta genes, 1 of which encodes the DR4 allospecificity. The identification of these genes has been made by the comparison of amino terminal sequences of DR molecules obtained from a DR4 cell line and the deduced protein sequences of the beta 1 exons from cosmid and phage clones. A conserved element including the promoter and signal sequence is found at the 5' end of each of the 3 DR beta genes. Additionally, this element occurs three more times in the DR region, raising the question of whether additional beta chain genes might be found. The DQ region contains 2 pairs of genes, 1 of which encodes the DQ antigen. The 2nd pair of genes, called DX alpha and beta, appears to be capable of expressing a DQ-related product, although, to date, there is no evidence for its expression. The DP region also contains 2 pairs of genes. One pair encodes the DP antigen while the 2nd alpha-beta pair is shown to be composed of pseudogenes. The location of polymorphic regions in these genes and aspects of their relationship to the serology, evolution, and function of the class II MHC are discussed. The control of expression of class II genes by gamma-interferon has been examined. The promoters of class II genes are characterized by two conserved sequences common to all alpha and beta chain genes as well as by conserved sequences specific for either alpha or beta chain genes. In addition to studies of expression by DNA-mediated gene transformation, a system for the gene transfer of MHC antigens utilizing transmissible retrovirus vectors is described. Retrovirus vectors have been used to transmit DR alpha, DR beta, and the invariant chain (gamma) sequences to recipient cells with resultant expression of these proteins.

Immune interferon activates multiple class II major histocompatibility complex genes and the associated invariant chain gene in human endothelial cells and dermal fibroblasts.

Immune interferon (IFN-gamma) increases the surface expression of HLA-A,B antigens and induces the surface expression of HLA-DR antigens on vascular endothelial cells and dermal fibroblasts. Here we report that IFN-gamma induces parallel expression of two other class II major histocompatibility complex (MHC) antigens, SB and DC. Maximal surface expression of all three antigens is reached in 4-6 days, and HLA-DR and -SB are induced to a higher level of expression than HLA-DC. For all three class II antigens, induction is marked by the de novo appearance of detectable transcripts of class II heavy and light chains and of the non-MHC-encoded invariant chain, suggestive of the transcription of multiple previously silent genes. Class I message levels and antigen expression are also increased by IFN-gamma at similar rates but from initial levels that are 50% of maximal. After removal of IFN-gamma, class II antigen expression persists for at least 4 days, while mRNA levels decrease rapidly. The parallel induction and persistence of the several class II MHC antigens may be important in conferring immune accessory function on vascular and stromal cells.