Interleukin-2 receptor gamma chain mutation results in X-linked severe combined immunodeficiency in humans

The interleukin-2 (IL-2) receptor gamma chain (IL-2R gamma) is a component of high and intermediate affinity IL-2 receptors that is required to achieve full ligand binding affinity and internalization. We have localized the IL-2R gamma gene to human chromosome Xq13. Genetic linkage analysis indicates that the IL-2R gamma gene and the locus for X-linked severe combined immunodeficiency (XSCID) appear to be at the same position. Moreover, we demonstrate that each of three unrelated patients with XSCID has a different mutation in his IL-2R gamma gene resulting in a different premature stop codon and predicted C-terminal truncation. These data establish that XSCID is associated with mutations of the IL-2R gamma gene product. Since XSCID is characterized by absent or markedly reduced numbers of T cells, our findings imply that IL-2R gamma plays a vital role in thymic maturation of T cells. These results also have important implications for prenatal and postnatal diagnosis, carrier female detection, and gene therapy for XSCID.

Skeletal 210Pb levels and lung cancer among radon-exposed tin miners in southern China

A preliminary case-control study of 19 lung cancer cases older than 55 y and 141 age-matched controls was carried out among a group of underground miners in Southern China who were exposed to 222Rn and its decay products. 210Pb activity levels were measured in the skull to estimate radon exposure. Radon exposure was also estimated in working level months, based on work histories and available industrial hygiene data. There was a smooth gradient of lung cancer risk with categories of skeletal 210Pb level at time of last radon exposure; relative risks of 1.0, 2.9, 3.2, and 4.7 for categories < 51.8, 51.8-77.7, 77.8-107.3, and > or = 107.4 Bq (< 1,400, 1,400-2,099, 2,100-2,899, and > or = 2,900 pCi), respectively. Relative risks were unaffected by adjustment for exposure to arsenic in the mine or by adjustment for working level months. Risks also increased with cumulative working level month exposure, but the gradient of risk lessened after adjustment for exposure to arsenic. 210Pb, at the time of last radon exposure (p = 0.13) and at the current 210Pb level (p = 0.01), was not highly correlated with the working level month estimate. Data were sparse but smoking had minimal effect on risk gradient with level of skeletal 210Pb activity. This study suggests measured 210Pb level may be a more precise predictor of lung cancer risk than working level month.

Localization of the hydroxyindole-O-methyltransferase gene to the pseudoautosomal region: implications for mapping of psychiatric disorders

The human hydroxyindole-O-methyltransferase (HIOMT) gene has been mapped to the X chromosome using cDNA probes from the 3' and 5' regions of a human cDNA clone. Southern blot analysis of a panel of human-rodent somatic cell hybrid DNAs revealed that the gene was localized to the short arm of chromosome X, and most probably the pseudoautosomal region of the human X (Xp22.3) and Y (Yp11.3) chromosomes. Several multiallelic restriction fragment length polymorphisms were detected at this locus allowing further localization of the gene by two-point and multipoint linkage analysis in the 40 CEPH families. These results confirmed the pseudoautosomal localization of the HIOMT gene and allowed ordering of the gene in close proximity to DXYS17 at a position about 600-800 kb from the pseudoautosomal boundary and about 1800 to 2000 kb from the telomere. It will be possible to readily identify or exclude the involvement of this gene in genetic diseases by linkage analysis of the disease locus with the high frequency multiallelic polymorphisms at this locus.

Confocal imaging of the retrograde tracer fluoro-gold using a non-ultraviolet laser

Until now, Fluoro-gold confocal imaging has been problematic because it requires an ultraviolet laser. We describe here a practical method to visualize Fluoro-gold in a confocal laser scanning microscope without an ultraviolet laser through an immunofluorescence procedure using antibodies against Fluoro-gold.

Roles of heme insertion and the mannose-6-phosphate receptor in processing of the human myeloid lysosomal enzyme, myeloperoxidase

Biosynthesis of myeloperoxidase (MPO), a myeloid lysosomal hemoprotein critical for the optimal oxygen-dependent microbicidal activity of human neutrophils, is incompletely understood. The primary translation product undergoes cotranslational N-linked glycosylation with subsequent insertion of the Fe-containing prosthetic group into the peptide backbone, thereby converting the enzymatically inactive, heme-free apoproMPO into the peroxidatively active precursor, proMPO. Eventually, proMPO undergoes proteolytic processing into native, lysosomal MPO, with subunits of 59 and 13.5 Kd. We studied three unanswered questions regarding MPO biosynthesis: (1) At what point during MPO biosynthesis is the heme moiety inserted into the apoenzyme? (2) What consequences does heme-insertion have on subsequent processing events? (3) What role does the mannose-6-phosphate receptor (M6PR) system play in the delivery of MPO to the lysosome? Disruption of Golgi by brefeldin A (BFA) produced two major changes in MPO biosynthesis: (1) processing of the 89-Kd precursor to mature MPO was blocked and (2) constitutive secretion of the MPO precursor was inhibited. Inhibition of heme synthesis with succinyl acetone (SA) reduced peroxidase activity and profoundly blocked processing of proMPO to mature MPO. This inhibition of processing was not a generalized effect on all lysosomal enzymes, because the maturation of a non-heme-containing lysosomal enzyme, beta-glucuronidase, was not altered. Electron microscopy showed that, although the normal peroxidase staining of endoplasmic reticulum was absent in SA-treated cells, there were MPO-related peptides in the ER. The role of the M6PR system was assessed by immunoprecipitating fractions obtained from M6PR affinity column chromatography. The 89-Kd proMPO failed to adhere to the M6PR affinity column, whereas the 59-Kd heavy subunit of mature MPO was specifically eluted from the column. We interpret these data to indicate that: (1) processing of proMPO to mature MPO occurs in a post-ER compartment that is itself BFA-sensitive or is distal to a BFA-sensitive compartment and (2) heme insertion into apoproMPO precedes and may be a prerequisite for proteolytic processing to enzymatically active mature MPO. Our analysis of the M6PR system in MPO biosynthesis led to the unanticipated finding that there were phosphomannosyl residues on mature MPO, but none on proMPO. We suggest that the bulk of proMPO at any time is not phosphorylated, but, when generated, the phosphorylated proMPO is quickly processed to the phosphorylated 59-Kd subunit of mature MPO. Thus, if the M6PR is important in the intracellular transport of MPO, it is the phosphorylated mature MPO that is directed to the lysosomal compartment by this system.(ABSTRACT TRUNCATED AT 400 WORDS)

The morphologic characteristics of tumor blood vessels as a marker of tumor progression in primary human uveal melanoma: a matched case-control study

Nine morphologic patterns of tumor vessels were identified in eyes removed for ciliary body or choroidal melanoma by the examination of tissue sections stained with fluorescein-conjugated Ulex europaeus I using laser scanning confocal microscopy. This technique also highlights intravascular tumor invasion. Each of these nine morphologic patterns of tumor vessels also may be demonstrated by a modification of the periodic acid-Schiff reaction, viewed with a green narrow band pass filter, but this modified histochemical technique does not accurately identify intravascular tumor invasion. Most tumors have a heterogeneous distribution of vascular patterns. Melanomas in two groups of 20 tumors each were matched by tumor size and location (one group of tumors from patients who survived at least 15 years free of metastatic melanoma after enucleation and one group of tumors from patients who died of metastatic melanoma). A matched case-control analysis indicates that the presence of at least one closed vascular loop in a uveal melanoma is the most significant vascular pattern associated with death from metastatic melanoma after enucleation. Closed loops are associated with other histologic features that are predictive of an unfavorable outcome after enucleation: epithelioid cells and mitotic figures. In this preliminary study the formation of closed vascular loops is a marker of tumor progression in ciliary body and choroidal melanomas.

Tetrin polypeptides are colocalized in the cortex of Tetrahymena

There is a complex system of 2- to 5-nm filaments in the oral apparatus of Tetrahymena. Four major subunit proteins, called tetrins, have been isolated from the filaments. These proteins, showing apparent molecular weights in polyacrylamide gels of 79-89 kDa, will assemble in vitro into 2- to 5-nm filaments. Tetrin filaments in vivo show different packing arrangements in different regions of the oral apparatus. We sought to determine the distributions of tetrin polypeptides within the complex oral structure by obtaining monoclonal antibodies specific for individual tetrins, then mapping their distributions within the oral apparatus using standard fluorescence microscopy, confocal laser scanning fluorescence microscopy, and electron microscopy. The results indicate that the four tetrin polypeptides are colocalized everywhere within the oral apparatus of Tetrahymena. Tetrin-binding proteins or specific nucleating structures may need to be invoked to explain the complex organization of the tetrin network. The 16 monoclonal antibodies obtained were also used to search for evidence of immunological relationships between tetrin and cytoskeletal proteins in multicellular organisms. None was found.

[Determination of baicalin in xiaoer feire kechuan mixture by dual-wavelength spectrophotometry]

A method for the determination of baicalin in traditional Chinese medicine Xiaoer Feire Kechuan Mixture with dual-wavelength spectrophotometry is described. The interference of coexisting ingredients may be eliminated without separation of the samples. Both 751 and UV-3000 spectrophotometers were used.

Stress analysis of the human tooth using a three-dimensional finite element model

A three-dimensional finite element model has been developed for the purpose of analyzing the stress distribution in a human mandibular right first molar. The model takes into account the non-symmetric geometry and loading, and the material inhomogeneities of the tooth. Comparisons with existing two-dimensional analyses are given.