The three-dimensional structure of cocksfoot mottle virus at 2.7 A resolution

Cocksfoot mottle virus is a plant virus that belongs to the genus Sobemovirus. The structure of the virus has been determined at 2.7 A resolution. The icosahedral capsid has T = 3 quasisymmetry and 180 copies of the coat protein. Except for a couple of stacked bases, the viral RNA is not visible in the electron density map. The coat protein has a jelly-roll beta-sandwich fold and its conformation is very similar to that of other sobemoviruses and tobacco necrosis virus. The N-terminal arm of one of the three quasiequivalent subunits is partly ordered and follows the same path in the capsid as the arm in rice yellow mottle virus, another sobemovirus. In other sobemoviruses, the ordered arm follows a different path, but in both cases the arms from three subunits meet and form a similar structure at a threefold axis. A comparison of the structures and sequences of viruses in this family shows that the only conserved parts of the protein-protein interfaces are those that form binding sites for calcium ions. Still, the relative orientations and position of the subunits are maintained.     

Latvian nurses depart from Soviet ways

As their country tries to break away from the Soviet political system, Latvian nurses try to break away from a Soviet health care system that has relegated their profession to one completely dominated by physicians. Two Latvian-born American nurses provide a glimpse of the early stages of this struggle.     

Distribution of spectrin and lectin-binding materials in surface lamina of RPE cells

Explants of embryonic chick retinal pigmented epithelium (RPE) form colonies in primary cultures in which the cells occupying the center of the colony are cuboidal, pigmented, and resemble closely the differentiated RPE cells found in vivo, while those towards the periphery gradually become less differentiated, flatter, nonpigmented, and motile. In the present article we describe the distribution of alpha-spectrin in cells in different parts of the RPE colony and compare it with that of the surface lamina components that bind the lectins, concanavalin A (Con A) and wheat germ agglutinin (WGA). Spectrin is present predominantly in the cell cortex in both differentiated and undifferentiated cells and seems to be accumulated especially heavily in the differentiated RPE cells in the colony center that have acquired the in vivo morphology. The distribution of lectin-binding materials in the surface lamina of the RPE cells is similar but not identical to that of alpha-spectrin. This is particularly evident in the flatter RPE cells along the edge of the colony in which surface lamina components visualized by fluorescein isothiocyanate (FITC)-WGA are distributed in the punctate pattern that is distinctly different from the reticular pattern in which alpha-spectrin is distributed. Also, in cells of the intermediate and central zones, strong staining along the edge of the cells was seen with antibodies to alpha-spectrin but not with FITC-WGA. Thus, a codistribution similar to that reported for the spectrin-like proteins and WGA-binding material in mesenchymally derived cells is not found in RPE cells.     

Dopaminergic innervation of the human striatum in Parkinson's disease.

In Parkinson's disease (PD), dopaminergic input to the caudate nucleus and a band of putaminal tissue abutting the external globus pallidus seems well preserved on immunohistochemical staining for the dopamine transporter. Counting of dopaminergic terminals showed that terminal density in these regions in PD was the same as that in controls, which indicates that input is truly preserved and not a consequence of a compensatory upregulation of metabolism in a reduced pool of surviving terminals. When the branching pattern of dopaminergic axons coursing through the globus pallidus was examined, we found no evidence for increased axonal sprouting in PD that might have contributed to preservation of dopaminergic input to the putamen or caudate nucleus. Although terminal counting indicated that anatomic input was preserved to parts of the striatum, dopamine uptake site density in these regions was reduced significantly. This suggests that the impact of disease in these areas is more profound than was thought previously.     

Angiotensin II receptor binding associated with nigrostriatal dopaminergic neurons in human basal ganglia

In the human brain, receptor binding sites for angiotensin are found in the striatum and in the substantia nigra pars compacta overlying dopamine-containing cell bodies. In contrast, angiotensin-converting enzyme occurs in the substantia nigra pars reticulata and is enriched in the striosomes of the striatum. In this study, using quantitative in vitro autoradiography, we demonstrate decreased angiotensin receptor binding in the substantia nigra and striatum of postmortem brains from patients with Parkinson's disease. In the same brains the density of binding to angiotensin-converting enzyme shows no consistent change. We propose, from these results, that angiotensin receptors in the striatum are located presynaptically on dopaminergic terminals projecting from the substantia nigra. In contrast, the results support previous studies in rats demonstrating that angiotensin-converting enzyme is associated with striatal neurons projecting to the substantia nigra pars reticulata. These findings raise the possibility that newly emerging drugs that interact with the angiotensin system, particularly converting enzyme inhibitors and new nonpeptide angiotensin receptor blockers, may modulate the brain dopamine system.     

Cancer of distant primary site relapsing in the nasopharynx: a report of two cases and review of the literature

Cancers metastatic to the nasopharynx are rarities. We present here two more such tumors. Although the clinical features of primary and secondary tumors in the nasopharynx are indistinguishable, a past history of treatment for malignant disease is an obvious clue to the correct diagnosis.