Role of P2z purinergic receptors in ATP-mediated killing of tumor necrosis factor (TNF)-sensitive and TNF-resistant L929 fibroblasts

Two closely related cell lines were characterized in their responses to extracellular ATP (ATPo): the fibroblast cell line L929 and a TNF-resistant variant L929/R. Both lines showed ATPo-activated increases in intracellular Ca2+, inward current, and sustained depolarization of the plasma membrane, cell responses compatible with activation of purinergic receptors of the P2y, P2x, or P2z subtype; however, only the L929/R variant was susceptible to ATPo-dependent early permeabilization of the plasma membrane to hydrophilic solutes of M(r) below 900, a response uniquely caused by the activation of P2z receptors. Both cell types were susceptible to the cytotoxic effect of ATPo, but killing of the L929/R variant required much shorter incubations in the presence of this nucleotide. Morphologic examination of ATPo-challenged L929 and L929/R cells showed that cell death occurred by two alternative mechanisms: colloido-osmotic lysis or apoptosis. Occurrence of apoptosis was confirmed by agarose gel analysis of cellular DNA. Although ATPo caused a fast mobilization of intracellular Ca2+, neither colloido-osmotic lysis nor apoptosis were Ca2+ dependent. Our results show that the L929/R variant, but not the L929 parental fibroblast cell line, expresses functional purinergic receptors of the P2z subtype. The presence of P2z receptors confers to L929/R cells enhanced susceptibility to ATPo-mediated cytotoxicity.

Role of P2z purinergic receptors in ATP-mediated killing of tumor necrosis factor (TNF)-sensitive and TNF-resistant L929 fibroblasts

Two closely related cell lines were characterized in their responses to extracellular ATP (ATPo): the fibroblast cell line L929 and a TNF-resistant variant L929/R. Both lines showed ATPo-activated increases in intracellular Ca2+, inward current, and sustained depolarization of the plasma membrane, cell responses compatible with activation of purinergic receptors of the P2y, P2x, or P2z subtype; however, only the L929/R variant was susceptible to ATPo-dependent early permeabilization of the plasma membrane to hydrophilic solutes of M(r) below 900, a response uniquely caused by the activation of P2z receptors. Both cell types were susceptible to the cytotoxic effect of ATPo, but killing of the L929/R variant required much shorter incubations in the presence of this nucleotide. Morphologic examination of ATPo-challenged L929 and L929/R cells showed that cell death occurred by two alternative mechanisms: colloido-osmotic lysis or apoptosis. Occurrence of apoptosis was confirmed by agarose gel analysis of cellular DNA. Although ATPo caused a fast mobilization of intracellular Ca2+, neither colloido-osmotic lysis nor apoptosis were Ca2+ dependent. Our results show that the L929/R variant, but not the L929 parental fibroblast cell line, expresses functional purinergic receptors of the P2z subtype. The presence of P2z receptors confers to L929/R cells enhanced susceptibility to ATPo-mediated cytotoxicity.

Mitochondrial DNA is not fragmented during apoptosis

We have exposed mouse thymocytes and P-815 mastocytoma cells to four different conditions reported to cause apoptosis: 1) incubation in the absence of mitogenic factors; 2) incubation in the presence of dexamethasone; 3) stimulation with external ATP; 4) treatment with high concentrations of the K+ ionophore valinomycin. These treatments caused DNA fragmentation to a varying extent in the two cell types. High stringency hybridization with a cDNA probe specific to a mitochondrial DNA sequence revealed that during apoptosis induced by lack of mitogenic factors, dexamethasone, or extracellular ATP, mitochondrial DNA was not fragmented. On the contrary, valinomycin caused extensive degradation of mitochondrial DNA. These results support the notion that DNA fragmentation during apoptosis is a specific nuclear event and suggest that other agents, such as valinomycin, may act less selectively.

Hypersensitivity to pets in Italy

Eight hundred and two consecutive symptomatic outpatients (with asthma and rhinitis) were studied to evaluate the incidence of prick test positivity to cat and dog danders and the association of exposure to these animals in the home, as revealed by a standard questionnaire. 14.3% were found to be skin positive to cat and/or dog danders. The incidence of cutaneous hypersensitivity to cat and/or dog danders was 25% in the 216 subjects who kept animals, significantly higher (p less than 0.0005) than the 10.4% of 586 subjects who did not keep animals. In the 57 subjects who owned both dogs and cats, a significantly higher incidence of skin hypersensitivity was found compared to the other subjects. Our data does not demonstrate a greater incidence in sensitivity to cat danders compared to dog danders, or increased sensitization to dermatophagoides pteronyssinus, nor a different incidence of clinical manifestations (asthma and rhinitis) between those with animals in the house and those without.

Quantitative and functional abnormalities of total T lymphocytes in relatives of patients with Hodgkin's disease

Seven patients, long-term survivors of Hodgkin's disease, and 24 of their relatives (parents, siblings and children), together with normal controls were studied for percentages, absolute counts and mitogen-proliferative responses by means of monoclonal antibodies, E rosette technique and in vitro cultures with PHA, ConA and PWM. The aim of the study was to ascertain whether the impaired cell-mediated immunity of Hodgkin's patients was also present in relatives in order to elucidate the still debated etiology of the defect and of the disease (congenital? environmental? infectious?). The results show that both Hodgkin's patients and their relatives have a significant decrease of total T cells (as T3+, T11+ and E rosette-forming cells) in peripheral blood and a significant impairment of polyclonal responses to all the mitogens employed. The Leu-7+ cells (i.e. a consistent amount of natural killer cells) are significantly increased only in the Hodgkin's patients but not in their relatives. The T cell subpopulations (T4 and T8), B cells and monocytes do not show any difference between the patients, their relatives and normal controls. Our results seem to support, at least in part, the presence of a common defect of T cell lineage both in patients and in their relatives, but its etiology still remains uncertain (genetic? environmental?).

"One year's survey of airspora in Siena (central Italy)"

An investigation of fungal airspora in Siena was carried out for one year using a Burkard trap. The spores were counted daily and expressed in number per m3 of air. The main spore period is the May-October semester which includes 85% of the annual spora caught. Cladosporium was by far the most common genus, representing 68% of the total spora amount. Ascospores were next in frequency but represented only 8,2% of the total. Basidiospores showed values and distribution similar to Ascospores. Another important allergenic spora collected was Alternaria which reached its maximum value in July. The quantity of airborne spores was very low when compared with values previously found in other European cities.

The pollen calendar of Siena (Central Italy)

The atmospheric pollen count at Siena was carried out for 4 years (1978-1981) to determine the average quantity of airborn pollen and the families, genera or species which contribute to such pollen dispersal. The pollination period stretches from February to mid October. The highest pollination period is from May to July when the most important pollen producers are Poaceae, Urticaceae, Pinus, Quercus, Oleaceae and Castanea sativa. Also in March there are high pollen production values due to Cupressaceae, Corylaceae, Alnus and Ulmus.

Angular distribution of light transmitted by a cylindrical guide

In this paper the problem of the light transmission through a cylindrical guide is analyzed. Equations are derived that allow us to evaluate the off-axis distribution of rays both with and without optical contact between the light source and the guide. In the latter case a very peculiar behavior is found for values of the refractive index satisfying the condition: [equation]. The over-all transmission of the guide is also evaluated in the various cases.