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Biomedical subjects

M D Nelson

Publications and source records attributed to M D Nelson.

70 records · Page 4Linked to original sources
PubMed1987

Intracranial catecholamine secreting paragangliomas.

Three intracranial catecholamine-secreting paragangliomas are described. They involved a glomus jugulare, a sphenopalatine ganglion and the clivus and upper cervical spine respectively. The extent of the tumours was shown by CT and MRI. They were all highly vascular with a substantial blood supply from systemic arteries which was subjected to particulate embolisation, followed in two cases by surgery. The importance of studying any tumour which could possibly be a paraganglioma for hormonal and, especially, for catecholamine secretion prior to any invasive procedure, including angiography and embolisation, is emphasised: all such procedures should be covered with catecholamine blocking agents and, in addition, carefully monitored with resuscitation facilities immediately available.

Adult↗
PubMed1987

Doctors and unions: is collective bargaining the cure for physicians' labor pains?

Increasing governmental regulation, the proliferation of alternative health-care options, and a glut of physicians in some areas have substantially affected the way physicians practice medicine today. Health-care consumers are not the only people affected. Where physicians were once their own bosses, many now find themselves as employers of health-care providers. In this new role, physicians are now considering union representation as a vehicle to assert their interests and concerns. This article examines why some doctors favor unionization, why some oppose it, and the legal implications of unionized physicians.

Employment↗
PubMed1986

Paclobutrazol Inhibits Abscisic Acid Biosynthesis in Cercospora rosicola.

Three plant growth regulators, paclobutrazol, ancymidol, and decylimidazole, which are putative inhibitors of gibberellin (GA) biosynthesis, were studied to determine their effect on abscisic acid (ABA) biosynthesis in the fungus Cercospora rosicola. All three compounds inhibited ABA biosynthesis, and paclobutrazol was the most effective, inhibiting ABA 33% at 0.1 micromolar concentrations. In studies using (E,E,)-[1-(14)C] farnesyl pyrophosphate, it was shown that ancymidol blocked biosynthesis prior to farnesyl pyrophosphate (FPP), whereas paclobutrazol and decylimidazole acted after FPP. The three inhibitors did not prevent 4'-oxidation of (2Z,4E)-alpha-ionylideneacetic acid. C. rosiciola metabolized ancymidol by demethylation to alpha-cyclopropyl-alpha-(p-hydroxyphenyl)-5-pyrimidine methyl alcohol. Paclobutrazol was not metabolized by the fungus. Information that these plant growth regulators inhibit ABA as well as GA biosynthesis should prove useful in determining the full range of action of these compounds.

Journal Article↗
PubMedDate not supplied

Brain infarction in children with diabetic ketoacidosis.

During the last 10 years, five children were treated at Childrens Hospital Los Angeles for acute, persistent neurologic loss during diabetic ketoacidosis (DKA). Four were transferred from local hospitals after the neurologic crisis. Computed tomography (CT) studies showed one or more areas of brain infarction in each patient, and none had evidence of diffuse cerebral edema. As three of the five patients had been treated for cerebral edema before their CT, brain edema may have been present initially. Our findings emphasize the importance of brain infarction as a cause of persistent neurologic loss in children with DKA.

Cerebral Infarction↗
PubMedDate not supplied

Spontaneous rupture of the liver during pregnancy: a case report.

Hepatic congestion resulting in hepatic rupture during pregnancy is a rare yet catastrophic event carrying a 60 to 70% maternal mortality rate. With preeclampsia and associated epigastric pain continuing to be a major problem confronting pregnant women, hepatic congestion may be more prevalent than believed. Current etiology, treatment, and characteristics of women who experience hepatic rupture are examined. A case report and nursing protocol are presented.

Adult↗
PubMedDate not supplied

Dyke Award. The search for human telencephalic ventriculofugal arteries.

Our study traced the vascular development of the fetal telencephalon in the last two trimesters of gestation and the first 15 years of life in 60 fetal and childhood brains. We filled the macro- and microvascular beds with Microfil and made stereoscopic observations of cleared 0.5- to 1.0-cm-thick sections. Separately, we identified developing vascular structures histologically. In our youngest specimen (16-weeks gestation), transcerebral channels with walls consisting of a single layer of endothelium and varying in diameter from 10 to 50 microns originated from leptomeningeal arteries and veins at right angles to the surface and passed through the cortical plate (future cortex). They branched at varying depths within the mantle and germinal matrix surrounding the lateral ventricles. At deeper levels the channels freely anastomosed with each other. A cortical microvascular network did not appear until 22 to 24 weeks. The new endothelial channels were derived from leptomeningeal vessels and from larger transcerebral channels. Most regions of isocortex developed a microvascular plexus simultaneously, regardless of degree of maturation. Striatal channels matured earlier than extrastriatal channels, having developed a muscularis to within 100 microns of the ganglionic eminence by 22- to 24-weeks gestation. Maturation of the vascular walls of extrastriatal channels into proper arteries and veins occurred during the first postnatal year. Anastomotic channels were present throughout the leptomeningeal, striatal, and extrastriatal regions in all of our specimens from 16 weeks gestation to 15 years old. Our study does not support the existence of ventriculofugal arteries and deep white matter arterial border zones in the human fetus and neonate, which have been postulated to be the basis of "periventricular" leukomalacia.

Arteries↗
PubMedDate not supplied

Radiodense dural sinuses: new CT sign in patients at risk for hypoxemic insult.

The observation of apparent dural sinus opacification in a polycythemic patient with cerebral infarction prompted a review of 300 computed tomographic scans for the significance of dense dural sinuses. Fifteen patients including 11 neonates, were identified; each of them had dense dural sinuses and elevated hematocrit or red blood cell indices or both. With only one exception, computed tomography also showed various low attenuation parenchymal abnormalities. A typical cerebral infarction pattern was seen in six and parenchymal hemorrhage in one. Nonthrombotic dural sinus opacification is a sign of increased blood viscosity in patients with congenital heart disease, hemoconcentration states, polycythemia of the newborn, and polycythemia rubra vera. These patients are at high risk for hypoxemic cerebral insult, which can be detected by cranial computed tomography.

Aged↗