Induction of the synthesis of tumor necrosis factor receptors by interferon-gamma

Human HT-29 colon carcinoma and HeLa D98/AH2 and SK-MEL-109 melanoma cells were sensitive to synergistic growth inhibition by concentrations of recombinant human tumor necrosis factor (rTNF) and interferon-gamma (rIFN-gamma) which individually were only slightly inhibitory. We investigated whether this synergism could be explained by the presence of an increased number of TNF receptors in cells treated with rIFN-gamma. These receptors were measured by incubating cells resuspended from monolayers with 125I-rTNF. HT-29 cells treated for a few hours with rIFN-gamma could bind more 125I-rTNF than control untreated cells, but this binding returned to the level of control cells after 24 hr. The treatment with rIFN-gamma did not change the binding affinity of TNF receptors, but increased their number to 1800 per cell from a basal level of about 800 per cell. Inhibitors of RNA synthesis prevented this increase. HT-29 cells were significantly more growth-inhibited when treated first for 6 to 12 hr with rIFN-gamma and then with rTNF, than when treated first with rTNF and then with rIFN-gamma. Untreated HeLa D98/AH2 and SK-MEL-109 cells had 2400 and 9000 receptors per cell, with a KD similar to that of HT-29 cells (approximately 2 X 10(-10)M). A significant increase in TNF receptors after treatment with rIFN-gamma was observed in HeLa D98/AH2, but not in SK-MEL-109 cells. No increase in TNF receptors was detected in cells treated with rIFN-alpha 2. These results indicate that the synergism between rTNF and rIFN-gamma may be due, at least in part, to a transient induction of the synthesis of TNF receptors by rIFN-gamma in cells with a relatively low number of these receptors.

[Role of scanography in the diagnosis of parathyroid adenomas. Apropos of 27 cases]

Scanner imagine pre-operatively in 27 patients with hyperparathyroidism provided assessment of the sensitivity (92 p.cent) and diagnostic precision (92.5 p.cent) of this investigational method. The need for a strict methodology and the advantages gained by high resolution and angioscanning programmes are emphasized. After analyzing the results, a review of the published literature enables the advantages and the limits of the scanner X to be defined, and a strategy for exploration of parathyroid adenomas to be proposed.

[Inferior mesenteric arteriovenous fistula of congenital origin. A report on one case and review of the published literature (author's transl)]

A fourth case of inferior mesenteric arteriovenous fistula of congenital origin is described by the authors, who also review the general characteristics of mesenteric (or portal) arteriovenous fistulae. Early clinical signs are hemorrhage from the digestive tract and chronic anemia. Endoscopy and barium X-rays are normal, and angiography is the only means of diagnosis. Surgical treatment is essential because of the risk of hemorrhages and portal hypertension.

Identification of a Leu-lle internalization motif within the cytoplasmic domain of the leukaemia inhibitory factor receptor

Leukaemia inhibitory factor (LIF) signals via a heterodimeric receptor complex comprised of the LIF receptor (LIFR) and the interleukin (IL)-6 signal transducer gp130. Upon binding to its cognate receptor LIF is internalized. In this study, we show that the LIFR is endocytosed independently of gp130. By using a heterochimaeric receptor system we identified a dileucine-based internalization motif within the cytoplasmic domain of the LIFR. Our findings suggest that a heterodimeric LIFR/gp130 complex and homodimeric gp130/gp130 complex are endocytosed via distinct internalization signals.

Organization and chromosomal localization of the human interleukin 5 receptor alpha-chain gene

The gene for the hIL-5R alpha subunit, which is present in a single copy in the human genome, has been analysed in detail. It is located on chromosome 3 in the region 3p26. The gene organization reflects its relationship to the cytokine/haematopoietin receptor superfamily. Three introns are located in the 5' untranslated region. The subsequent exons determine the functional domains of the hIL-5R alpha protein: the signal peptide, three fibronectin type III-like (FN-like) modules, each built up by two exons, the membrane anchor and two exons forming the cytoplasmic tail, the first of which contains the proline cluster region. In addition, a specific exon generating a soluble isoform is located before the membrane anchor exon. This specific exon contains an in frame TAA stop codon, followed by a polyadenylation signal. Hence, a normal splicing event leads to a soluble IL-5R alpha variant, whereas alternative splicing is required for cell membrane anchoring. A second area of alternative splicing is found in the 5' leader sequence, and possibly relates to the presence of short open reading frames preceding the main ATG. All intron-exon junctions meet the GT-AG rule. The gene structures of all cytokine/haematopoietin receptors documented so far have also been compared with respect to intron phasing. This shows that all introns between the FN-III-like modules are of the +1 type, but in addition, splice sites within the Cys-module and WS-WS-module are invariably of the +2 and 0 type, respectively.

Leiomyoma and leiomyosarcoma of the digestive tract--a report of 45 cases and review of the literature

The authors discuss the general and radiologic characteristics of leiomyomas and leiomyosarcomas, based on experience with forty-five cases involving the digestive tract and a review of over one thousand cases reported in the literature. Thirty-six leiomyomas (oesophagus 9, stomach 18, small intestine 9) and nine leiomyosarcomas (oesophagus 2, stomach 2, small intestine 4, colon 1) were observed and compared with reports from the literature. Leiomyomas of the oesophagus lend themselves to radiologic surveillance since there is no tendency for lesion degeneration in this location. Leiomyomas of the stomach are frequently asymptomatic and discovered following radiologic or endoscopic examination. With involvement of the small intestine, the most sensitive radiologic examination remains angiography, even though the information provided does not allow evaluation of the evolution of the tumour. Localization in the colon remains rare.