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Biomedical subjects

J Wiener

Publications and source records attributed to J Wiener.

124 records · Page 7Linked to original sources
PubMed1965

Cytological alterations related to stimulation of the zona glomerulosa of the adrenal gland.

The structure of the zona glomerulosa of the rat adrenal gland stimulated by sodium restriction has been studied by light and electron microscopy. The major changes observed during the course of the experiment in stimulated glands involve cytoplasmic droplets, mitochondria, and the endoplasmic reticulum. There is a progressive decrease in the number of cytoplasmic droplets of low electron opacity. Numerous, greatly elongated mitochondria containing parallel arrays of tubules are noted. These tubules extend from within the mitochondria through gaps in the mitochondrial-limiting membranes into the cytoplasm. In addition, amorphous intramitochondrial deposits, possibly aldosterone precursors, are seen. Increased amounts of smooth-surfaced endoplasmic reticulum, often showing complex arrangements, are another feature of the stimulated zona glomerulosa. Other alterations include the presence of large numbers of dense bodies as well as cytoplasmic droplets of high electron opacity. These observations are discussed in relation to the biosynthesis of aldosterone.

Adrenal Glands↗
PubMed1965

Ultrastructure and permeability of nuclear membranes.

The fine structures of nuclear envelopes known to have different permeability properties were compared. Membranes of salivary gland cell nuclei of Drosophila (third instar) and Chironomus (prepupae), which are strong barriers to ion diffusion, and membranes of oocyte nuclei (germinal vesicle) of Xenopus and Triturus, which are much more ion-permeable, show no essential difference in size, frequency, and distribution of their membrane gaps ("pores") which could account for the marked disparities in membrane permeability. The gaps are occupied by diffuse electron-opaque material with occasional central regions of strong opacity. This material may possibly account for the high diffusion resistance of Drosophila and Chironomus nuclear envelopes, where the resistance is far too great to allow free diffusion through the gaps. But material of this kind is also present in the more permeable nuclear envelopes of Xenopus and Triturus oocytes, and there are no convincing structural differences discernible with the techniques employed.

Animals↗
PubMedDate not supplied

Effects of aging on atrial and ventricular human myosin.

Enzymatic and structural studies of human cardiac myosin from young and old subjects have been investigated to determine possible changes in myosin properties in aging hearts. Human ventricular myosin from old subjects (47-70 years old) has lower actin-activated ATPase activity than and increased alkaline sensitivity as compared to myosin from young subjects (1-132 months old). Ca2+-and K+(EDTA)-ATPase activities, pyrophosphate gel patterns and one-dimensional peptide mapping of heavy chains of ventricular myosin from old subjects are similar to those observed for myosin from young subjects. Atrial myosin from human hearts differs significantly from ventricular myosin in that the Ca2+-, Mg2+- and actin-activated myosin Mg2+-ATPase activities of atrial myosin are significantly higher than those of ventricular myosin. Pyrophosphate gel electrophoresis patterns and peptide mapping of heavy chains of atrial myosin are also different from those of ventricular myosin. Unlike ventricular myosin, atrial myosin from young hearts is similar to that of atrial myosin from old hearts in its enzymatic and structural properties.

Adenosine Triphosphatases↗
PubMedDate not supplied

Axis selection in transverse magnetic resonance imaging of the brain: electronic angulation techniques.

The cylindrical design of most head coils utilized with current magnetic resonance (MR) imaging units and the necessity of close approximation of the coil to the head to maximize signal-to-noise ratio precludes flexion or extension of the head to any significant degree during of imaging of the brain. For this reason, the canthomeatal line is approximately parallel to the standard transverse magnetic axis. Standard computed tomography (CT) scans in the transverse plane are usually obtained at an approximately 25 degrees angle to Reid's baseline (RBL). This leads to projection differences in viewing and comparing standard transverse MR and CT studies. High convexity lesions which may present anteriorly on a given CT section may present posteriorly on an MR section which appears to be at a comparable level on first inspection. Secondly, one or more transverse MR sections usually display a portion of the occipital lobes behind the cerebellar hemispheres. The region of the tentorium and straight sinus can occasionally give rise to a vermiform appearance (the "AVM artifact"). Thirty patients were studied with MR at a 20-30 degrees angulation to RBL without any loss of image quality and with excellent visualization of the posterior fossa. The effect of transverse axis change on lesion position was demonstrated in five high convexity lesions and by utilizing fixed brain specimens. While clearly MR can accurately localize lesions utilizing orthogonal multiplanar techniques, it is suggested that investigators and clinicians currently performing MR studies of the brain consider potential advantages of electronic angulation techniques for comparative clinical studies and certain research applications.

Brain↗
PubMedDate not supplied

Immunohistochemical and molecular characterization of the differential response of the rat mesenteric microvasculature to angiotensin-II infusion.

The present study focuses on the differential response of three branch levels of the mesenteric resistance arterial vasculature of 450-gram Sprague-Dawley rats infused continuously with angiotensin II (A-II) for 4, 7 and 14 days at a rate of 435 ng/kg/min, with an associated period of hypertension. The three branch levels (types I, II and III) were characterized by light microscopy and immunostaining using monoclonal antibodies for proliferating cell nuclear antigen, ED-1 (specific for rat monocytes/macrophages) and alpha smooth muscle cell (SMC) actin. Cross-sectional areas of the vascular walls were determined morphometrically. In situ hybridizations were performed on paraffin sections using both sense and antisense 35S-labeled cRNA probes generated from rat SMC osteopontin and elastin cDNAs. In the type-I (penetrating) arteries from A-II-infused animals, there was massive fibrinoid necrosis, a marked fibroproliferative perivascular response, intense monocyte/macrophage infiltration, striking SMC osteopontin and elastin gene expression; SMC, fibroblast and monocyte/macrophage DNA synthesis; and significant increase in the cross-sectional areas of the vascular walls. In the same animals, DNA synthesis also occurred in the larger mesenteric arteries of types II and III where it is associated with significant enlargement of the walls by SMC hypertrophy but without overt morphologic damage. It is suggested that the monocyte/macrophage infiltration and fibroproliferative response of type-I arteries may be related to A-II-induced osteopontin gene expression. Angiotensin infusion in the rat may represent a reproducible model of microvascular injury that can be utilized to elucidate the cellular and molecular biology of a variety of disease states such as hypertension and diabetes mellitus.

Angiotensin II↗
PubMedDate not supplied

A Canadian perspective on learning disabilities.

Canadian practice and research with children and adults with learning disabilities are described and analyzed. After an examination of the historical basis for current practice, the societal and cultural factors affecting education of children with learning disabilities, services for adults, and research are discussed. It was found that policy and legislation regarding special education vary considerably from province to province, and identification practices and service delivery models vary even within provinces. The fact that Canada has two official languages (English and French), a large multicultural community, and a Native population with special needs often arising from poverty has an impact on the education of children with learning disabilities and on sample description in research. Although school-age children are relatively well served, services for preschool children and adults with learning disabilities are minimal. The positive features of Canadian service delivery are that most programs are publicly funded, decision making tends to be nonadversarial and collaborative, and the needs of the whole child are typically considered.

Adult↗