Experimental ductus arteriosus: the relationships of atrial pressure, dilatation and flow with ANF secretion

The design of the study was to determine whether an increased blood flow as seen in shunt lesions could serve as a stimulus for the secretion of atrial natriuretic factor (ANF). Since atrial pressure, flow, and dilatation are closely related, an experimental ductus arteriosus model was utilized, in which acute changes of flow are assumed not to dilate the left atrium. In six dogs, a Dacron graft was constructed between the main pulmonary artery and the innominate artery. Constricting and releasing the tape around the graft adjusted the amount of "ductal" shunting. The total pulmonary flow and the shunt flow were measured by electromagnetic-flow transducers around the aortic root and around the graft. Plasma ANF concentration was measured from both cardiac atria. The size of the left atrium was determined from echocardiographic measurements made from a short-axis view. The total pulmonary flow varied between 1.2 and 5.8 1/min. The highest measured ANF was 396 pg/ml, and this was from the left atrium when the pressure was 18 mmHg, the highest left atrial pressure recorded. The highest right atrial pressure (5 mmHg) also correlated with the highest right-atrial level of ANF (366 pg/ml). The right atrial pressure had a significant correlation with plasma ANF concentration (R = 0.43, p less than 0.05). Pulmonary flow and plasma ANF concentration did not correlate; neither did left atrial size and ANF levels in 16 flow states where the size was measured. In the absence of atrial dilatation there was minimal stimulus for ANF secretion. A transient increase of left atrial pressure, without a concomitant significant atrial dilatation, did not serve as a significant stimulus for ANF secretion.     

Cerebral microvascular and parenchymal phospholipid composition in the mouse

Cerebral microvessels consisting predominantly of capillaries and small arterioles (<30 m dia.) were isolated from the cerebral cortex and cerebellum of 3-month-old mice. Lipids were extracted from both microvascular and brain parenchymal fractions and the major phospholipid classes (choline phosphoglyceride, ethanolamine phosphoglyceride, inositol phosphoglyceride, serine phosphoglyceride, and sphingomyelin) separated by 2-dimensional TLC. Comparison of mol % determined by phosphate analysis of each phospholipid revealed significant differences in membrane composition of ethanolamine phosphoglyceride, inositol phosphoglyceride, and sphingomyelin between microvascular and parenchymal components of the central nervous system. Moreover, the choline phosphoglyceride/sphingomyelin mol ratio, one of three determinants of membrane fluidity, is significantly lower for microvessel membrane than for membranes of the brain parenchyma.     

Expression of human papillomavirus type 11 L1 protein in insect cells: in vivo and in vitro assembly of viruslike particles.

The L1 coat protein of human papillomavirus type 11 (HPV-11) was expressed in Sf-9 insect cells with the recombinant baculovirus vector Ac11L1. Viruslike particles (VLPs) were identified by electron microscopy in the nucleus and cytoplasm of Sf-9 cells infected with Ac11L1. The L1 protein was purified from Ac11L1-infected insect cells. The purified protein spontaneously assembled in vitro into various aggregates, including particles appearing similar to empty virions. Reaction of VLP-containing insect cell extracts with antisera directed against either denatured or nondenatured capsid epitopes in Western blot (immunoblot) and immuno-dot blot assays suggested that conformational epitopes present in native HPV-11 infectious virions were also present on the baculovirus-produced HPV-11 VLPs. Immuno-dot blot assays using human sera obtained from individuals with biopsy-proven condyloma acuminatum correlated closely with results previously obtained in HPV-11 whole virus particle-based enzyme-linked immunosorbent assays. These morphologic and immunologic similarities to native HPV-11 virions suggest that recombinant VLPs produced in the baculovirus system may be useful in seroepidemiology and pathogenesis studies of genital HPV infection and that they may also be potential candidates for vaccine development.     

Isolation and Propagation of Human Papillomavirus Type 16 in Human Xenografts Implanted in the Severe Combined Immunodeficiency Mouse

We report the isolation and propagation of human papillomavirus type 16, the main agent of cervical cancer, using human foreskin fragments implanted in severe combined immunodeficiency mice. The infection produced viral particles, and with each passage of the virus it caused lesions identical to intraepithelial neoplasia, the precursor to carcinoma.     

The product of the cellular crk gene consists primarily of SH2 and SH3 regions.

We have cloned and sequenced a complementary DNA encoding the cellular homologue of the transforming oncogene v-crk of avian sarcoma virus CT10. This complementary DNA contains an open reading frame of 915 base pairs that encodes a polypeptide of 305 amino acids. The first 205 amino acids of this c-Crk protein were identical to those of the CT10 encoded v-Crk protein, with the exception of 5 amino acids. Like v-Crk, this portion of c-Crk contained one each of the Src homology domains SH2, SH2', and SH3. The 100 carboxy-terminal amino acids of c-Crk protein, which are not coded for in the CT10 viral genome, contain another SH3 region. We found limited sequence homology between c-crk and the avian retrovirus genome, which explains recombination events in the transduction of this protooncogene. Using a polyclonal antiserum made against bacterially expressed v-crk, we identified a 35-kilodalton protein in normal chicken embryo fibroblasts and in all embryonic chicken tissues examined. This 35-kilodalton protein was indistinguishable from a polypeptide made by in vitro translation of c-crk complementary DNA.     

A study of spin-probe solubility in mitochondrial membranes correlated with ATP-dependent conformational changes

Addition of ATP to submitochondrial particles causes considerable changes in the ESR spectra of hydrophobic spin-probe bound to particles which indicate an improvement in probe solubilization in the submitochondrial particle membranes due to energization. This effect is abolished by 2,4-dinitrophenol (10^-4 M) and oligomycin (I μg/mg of protein). At lower concentrations (0.1–0.2 μg/mg), oligomycin, on the contrary, promotes the action of ATP on the submitochondrial particle-bound spinprobe ESR spectra as well as activates the ATP-dependent transhydrogenase reaction in submitochondrial particles.     

Activated monocytes resist elimination by retinal pigment epithelium and downregulate their OTX2 expression via TNF‐α

Orthodenticle homeobox 2 (OTX2) controls essential, homeostatic retinal pigment epithelial (RPE) genes in the adult. Using cocultures of human CD14⁺ blood monocytes (Mos) and primary porcine RPE cells and a fully humanized system using human‐induced pluripotent stem cell‐derived RPE cells, we show that activated Mos markedly inhibit RPEOTX2 expression and resist elimination in contact with the immunosuppressive RPE. Mechanistically, we demonstrate that TNF‐α, secreted from activated Mos, mediates the downregulation of OTX2 and essential RPE genes of the visual cycle among others. Our data show how subretinal, chronic inflammation and in particular TNF‐α can affect RPE function, which might contribute to the visual dysfunctions in diseases such as age‐related macular degeneration (AMD) where subretinal macrophages are observed. Our findings provide important mechanistic insights into the regulation of OTX2 under inflammatory conditions. Therapeutic restoration of OTX2 expression might help revive RPE and visual function in retinal diseases such as AMD.     

Native Consumers and Seed Limitation Constrain the Restoration of a Native Perennial Grass in Exotic Habitats

Native consumers and seed limitation may be particularly important in the restoration of native plants where they have been displaced by exotic plants. We used experimental exclosures and seed additions to examine the role of native mammalian consumers and seeding density (500 or 1,000 seeds/m²) in affecting the establishment of a native perennial grass, Purple needlegrass ( Nassella pulchra ), in the grasslands of California. To focus solely on consumers and propagule density, experimental areas were tilled and weeded. Consumers were important determinants of restoration success: averaged across propagule density, consumers reduced N. pulchra seedling recruitment by nearly 30%, reduced seedling height by 44%, reduced plant establishment by 52%, and reduced reproductive tiller length by 43%. Small rodents affected seedling establishment, especially where seeding density was high but did not affect seedling height. Plots accessible by squirrels and rabbits exhibited significantly decreased seedling height and plant establishment, whereas there was no additional impact of allowing large consumers (i.e., deer) access. Despite strong, spatially variable effects of consumers, doubling seed density led to nearly doubled N. pulchra establishment on average. Consumer effects were persistent, shaping N. pulchra abundance in the subsequent growing season and remaining evident over 18 months after the experiment was initiated. Our work suggests that, despite strong consumer effects, seed addition may be a viable strategy for restoration of N. pulchra in invaded areas where it has been displaced by exotic plants, especially when combined with restoration strategies that reduce competition with exotic plants.