Antibodies raised against tobacco aquaporins of the PIP2 class label viscin tissue of the explosive dwarf mistletoe fruit.

Dwarf mistletoes, genus Arceuthobium, are parasitic flowering plants and forest pests. In western North America, Arceuthobium americanum (lodgepole pine dwarf mistletoe) is principally found on Pinus contorta var. latifolia (lodgepole pine). Dwarf mistletoes disperse their seeds by an explosive process that involves the buildup of hydrostatic pressure within a mucilaginous fruit tissue called the 'viscin'. Living viscin tissue envelops the discharged seeds. This study examined the possibility that aquaporins, critical in plant water relations, might be found in the dwarf mistletoe fruit, specifically the viscin cells. An antibody raised against a tobacco plasma membrane intrinsic 2 (PIP2) aquaporin was used with a gold-labeled secondary antibody to probe dwarf mistletoe fruit at various developmental stages. Viscin cell plasma membranes were successfully labeled with the anti-tobacco probe, and the validity of the immunolabeling was supported by Western blot analysis, showing a strong signal at about 30 kDa, which is at the expected size of a PIP2. A definitive immunolabeling pattern, supported by quantification of gold signal per membrane length, was observed: viscin cells sampled early in development had abundant gold label at their plasma membranes (1.93 +/- 0.13 to 2.13 +/- 0.33 gold particles per microm membrane), while other areas of the cells had no discernible label. Viscin cells sampled near the time of explosive discharge had significantly less label at the plasma membrane (0.21 gold particles +/- 0.11 per microm membrane, P < 0.05), and label was seen at vesicular membranes. Aquaporins likely have a role in directing water to the viscin mucilage early in development, but are retrieved via endocytosis to prevent excess water loss from viscin cells when discharge is imminent.

The natural history of epistaxis in hereditary hemorrhagic telangiectasia.

The purpose of this retrospective study is to document the natural history of epistaxis in patients with hereditary hemorrhagic telangiectasia. A telephone questionnaire was administered to 73 patients who had been previously screened for pulmonary arteriovenous malformations (PAVMs). The incidence of epistaxis in this population was 93%, with a mean onset age of epistaxis of 12 years, a mean frequency of bleeding of 18 episodes per month, and a mean duration of bleeding of 7.5 minutes. More than 90% of patients experienced the onset of epistaxis before the age of 21 and symptoms were progressive with age. There were no differences in the age of onset, frequency of epistaxis, or duration of epistaxis between patients with PAVMs versus those without PAVMs. Although the natural history of epistaxis does not predict the presence or absence of pulmonary arteriovenous malformations, epistaxis is an early marker of the disease, hereditary hemorrhagic telangiectasia, and might guide screening for pulmonary and cerebral arteriovenous malformations in children of affected parents.

Localization of tritiated 1,25-dihydroxy vitamin D3 in fetal rat mandible, kidney, and intestine.

In the fetal rat the specific uptake of this hormone appears in the kidney and in the mandible-tooth germ, but not by the intestine. Furthermore, uptake by the two former tissues was greatly influenced by gestational age. Localization in the mandible and tooth germ increased from approximately 50 DPM/mg wet weight of tissue on day seventeen of gestation to over 300 DPM/mg wet weight on the nineteenth day. A similar, but not as dramatic, increase occurred in the kidney. Thus, these data demonstrate: (1) the development of the specific uptake of 1,25-dihydroxy vitamin D3 in the kidney and bone with gestational age, and (2) the absence of specific receptive sites in the fetal intestine.

Composition and mechanical properties of gutta-percha endodontic points.

Gutta-percha endodontic filling points were found to contain approximately 20% gutta-percha (matrix), 66% zinc oxide (filler), 11% heavy metal sulfates (radiopacifier), and 3% waxes and/or resins (plasticizer). The mechanical properties were indicative of a partially crystalline viscoelastic polymeric material. They were found to obey Hooke's law and displayed a prominent upper and lower yield point when stressed beyond the proportional limit. The essential differences in mechanical properties of individual brands were found to be a function of the gutta-percha and zinc oxide concentration.