Working from the hypothesis that modest deviations from physiological oxygen tension will influence cell characteristics important for infections/immunity and tumor development, cells were studied at three oxygen tensions during in vitro aging. Primary mouse embryo fibroblasts were established and subsequently passaged at 3, 6, and 18 kPa oxygen tension (6 representing normal tissue tension and 18 being the conventionally tension at in vitro cultures). The growth rate was slightly higher at 6 than 3 and 18 kPa. All cultures eventually stopped growing and subsequently transformed to nonmalignant cells with unlimited growth capacity. Cells kept at 3 kPa reached the highest number of cell doublings before crisis. Stimulation with PolyI:C resulted in detectable interferon response only at the high oxygen tension, and after transformation none of the cultures responded with interferon production. Expression of the major histocompatibility complex H-2K was elevated above and below physiological oxygen tension, indicating regulatory processes optimizing MHC expression at about physiological oxygen tension.

Animals↗

PubMedDate not supplied

Clonal analysis suggests provirus expression in a subpopulation of human malignant trophoblast cells harbouring the human T cell lymphotropic virus type-I genome.

Previous studies have indicated that the villous trophoblast may be involved in intrauterine HTLV-I infection. Although the data furnished by our group (Liu et al., 1995) have demonstrated that the human trophoblast-derived malignant cell lines JAR and JEG-3 are susceptible to HTLV-I, the infection, even after thorough analysis, appeared to be limited to expression at the transcriptional level. In the present report, we sought to explore virus expression at the single cell level using eight clonally selected cell lines which were derived by limiting dilution from the previously infected parental cultures. Of the three cell lines JAR-H2, JAR-H3, and JEG-H3, all of which harboured full-length provirus, only in two (JAR-H2 and JEG-H3) were the virus-specific tax/rex and env transcripts demonstrated using RT-PCR. When compared with MT-2 cells, the detected steady-state levels of HTLV-I mRNA appeared to be lower by three orders of magnitude. Viral Tax protein displaying a typical intranuclear localization was found in 1-2% of JAR-H2 and JEG-H3 cells. Moreover, an altered phenotype characterized by multinucleated syncytia was observed in these cell cultures with the same frequency as Tax transactivator, implying a fusogenic activity of env protein. Infectious virus, however, could not be rescued from JAR-H2 or JEG-H3 clones by coculture with cord blood mononuclear cells. Our data suggest that trophoblast represents a susceptible, albeit a slightly permissive, host system for HTLV-I.

Base Sequence↗

PubMedDate not supplied

In vitro infection of human placental trophoblast by wild-type vaccinia virus and recombinant virus expressing HIV envelope glycoprotein.

Short-time (< or = 7 days) cultures of trophoblast mononuclear cells isolated from term placentae were challenged with vaccinia virus. Cytopathic effects were induced in crude placental cell preparations as well as in cultures established after negative immunosorting of major histocompatibility complex class I epitope-expressing cells, i.e. cultures exclusively derived from villous cytotrophoblast according to our present state of knowledge. The trophoblast in vitro supported a full replicative cycle of both wild-type viruses and a recombinant clone serving as a vector for the human immunodeficiency virus type 1 envelope gene. Results may shed light on mechanisms involved in the rarely observed foetal damage caused by smallpox vaccination during pregnancy.

Animals↗

PubMedDate not supplied

Susceptibility of MHC class I expressing extravillous trophoblast cell lines to killing by natural killer cells.

Purified human first trimester extravillous trophoblast (EVT) cell lines HTR-8 and HT-116 were examined for susceptibility to natural killer (NK) cell-mediated lysis. Based upon nucleic acid sequencing of an amplified fragment of cDNA, Western blot analysis and immunostaining of fixed and live cells, it was shown that both EVT cell lines expressed HLA-G mRNA and protein within the cytoplasm when cultured on laminin-coated plates. Very weak HLA-G expression was detectable on the cell surface under these conditions. However, strong cell surface expression of a classical MHC class I molecule (most likely HLA-C) was exhibited by these EVT cell lines when grown on laminin, as indicated by W6/32 FACS analysis (Ab recognizing pan MHC class I), and Western immunoblotting with HC10 (Ab recognizing HLA-B/C). When these EVT cells, cultured on laminin, were used as targets for peripheral blood natural killer (NK) cells in a standard chromium release assay, both HTR-8 and HT-116 cells were lysed by NK cells in a dose-dependent manner. The respective percentage specific lysis at an effector to target (E/T) ratio of 100 was 28+/-7, and 48+/-14. The choriocarcinoma cell lines JAR and JEG-3 which were respectively MHC class I negative and HLA-G positive were resistant to NK cell lysis. Thus, there was no clear relationship between the MHC class I expression and NK cell resistance or susceptibility among the EVT cell lines and choriocarcinoma cells. These findings raise the possibility that NK cells may take part in the surveillance of the invasive EVT cells during normal placentation.

Cell Line↗

PubMedDate not supplied

Branhamella catarrhalis respiratory infections.

Branhamella catarrhalis, a normal commensal of the oropharynx, is increasingly recognized as an important cause of bronchitis and bacterial pneumonia. Six patients with B. catarrhalis pneumonia documented by transtracheal aspirate or blood culture were studied, and 429 previously reported cases of B. catarrhalis bronchitis and pneumonia were reviewed. The mean age of patients with B. catarrhalis infection was 64.8 years, and preexisting chronic obstructive pulmonary disease was common. The typical clinical picture was that of purulent tracheobronchitis; patients with pneumonia were not severely ill and differed from those with bronchitis mainly by the presence of patchy lower-lobe infiltrates on chest roentgenogram. Fifty-three percent of reported strains produced beta-lactamase. Thirty-nine percent of the cultures were mixed, predominantly with Haemophilus influenzae and Streptococcus pneumoniae. The microbiologic, immunologic, and clinical features of B. catarrhalis infection, as well as the antimicrobial susceptibilities of this organism, were reviewed. The reasons for the lack of recognition of this common pathogen and possible solutions were considered.

Antibodies, Bacterial↗

PubMedDate not supplied

Familial achalasia with absent tear production.

Three of five siblings were evaluated because of dysphagia and failure to thrive. Radiologic and manometric studies were consistent with achalasia of the cardia. All of these siblings had deficient tear production. This report documents the unusual association of familial achalasia and deficient tear production, which is probably an autosomal recessive inherited syndrome.

Child↗

PubMedDate not supplied

Celiac disease as a cause of transient hypocalcemia and hypovitaminosis D in a 13 year-old girl.

We report a thirteen year-old girl with symptomatic hypocalcemia secondary to celiac disease. Serum vitamin D levels [25OH-VitD3 and 24,25(OH)2-VitD3] were low, whereas 1,25(OH)2D3 and PTH levels were higher than normal. Shortly after introducing a gluten-free diet, the patient became asymptomatic, regaining normal growth and pubertal development and serum calcium levels returned to normal.

Adolescent↗

PubMedDate not supplied

[Regeneration of myelinated nerve fibers in autologous and homologous transplants: light and electron microscopy studies].

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Animals↗