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Biomedical subjects

K R Davis

Publications and source records attributed to K R Davis.

At least 145 records · Page 8Linked to original sources
PubMed1976

Computed tomographic evaluation of hemorrhage secondary to intracranial aneurysm.

Angiography in patients with subarachnoid hemorrhage secondary to aneurysm gives precise information on the location and size of the aneurysm and the aneurysm and the presence of spasm but gives incomplete information on ventricular size, size and location of hematoma, and extent of infarction. CT demonstrates precisely brain or intraventricular hematoma and, at times, subarachnoid hemorrhage, indicates the extent of infarction; and rapidly documents the degree of hydrocephalus. Infarction secondary to spasm, hematoma, and hydrocephalus are readily differentiated. The CT examination may be repeated as often as necessary without patient discomfort or morbidity. Serial scans allow rapid assessment of change in ventricular size, development and persistence of infarction, and change in size of hematoma.

Adult↗
PubMed1976

Metrizamide cisternography with hypocycloidal tomography: preliminary results.

Metrizamide (Amipaque), a nonionic water soluble contrast agent, has been shown to be safe and efficacious for lumbar myelography. Clinical trials of cervical, thoracic, and even intracranial examinations have produced good results. Despite an inherent neurotoxicity, significant complications have been quite rare, and patient tolerance in general is remarkably good. Preliminary results of metrizamide cisternograms using hypocycloidal tomography are presented to illustrate the anatomic detail which can be demonstrated using this technique.

Humans↗
PubMed1976

Evaluation of intracranial aneurysms by computed tomography.

Useful information has been gained by review of eight cases of intracranial aneurysm demonstrated by computed tomography (CT) and correlation with cerebral angiograms. The angiograms demonstrated one or multiple aneurysms, the precise location of the aneurysm, and presence of arterial spasm. The CT scan can delineate the full size of the aneurysm when the sac has been partially obliterated by thrombus, the presence of hematoma, infarction, hydrocephalus, and intraventricular and subarachnoid hemorrhage. These associated features are more difficult to evaluate by angiography alone.

Adolescent↗
PubMed1976

Theoretical considerations in the use of contrast media for computed cranial tomography.

The impressive results obtained by the use of iodinated contrast media, particularly when administered by drip infusion technique, led us to investigate the advantages and disadvantages of the method. An originally non-invasive examination has progressively evolved into a quasiinvasive examination in the majority of cases, and our results appear to justify such a trend.

Aged↗
PubMed1976

CSF enhancement for computerized tomography.

Metrizamide cisternography, combined with hypocycloidal tomography, has been performed in 12 patients with possible posterior fossa or parasellar mass lesions with finely detailed images of the basal cisterns resulting. Computed tomography was performed in nine of these patients and produced exceptional images of the cisternal anatomy. The technique of cerebrospinal fluid enhancement may be efficacious in identifying small basal masses not shown with conventional computed tomography, and thus may form an important complement to enhancement by intravenous injection of contrast medium.

Brain Neoplasms↗
PubMed1975

Persistence of parathion and its oxidation to paraoxon on the soil surface as related to worker reentry into treated crops.

Soil and dust samples from beneath citrus trees contained relatively high concentrations of paraoxon and parathion for at least 45 days after parathion was applied at normal rates. These data indicate that parathion dripping on dry soil from sprayed crops, or sprayed directly on the soil surface, can persist for long periods and be oxidized to the highly toxic paraoxon. The residue concentrations are much higher on the loose dust particles than in the bulk soil. The data indicate that the soil or grove floor should be considered as a possible contributing source of toxicant along with foliage, or dust on foliage, to workers reentering treated fields. In any event, the data confirmed the high rates of oxidation of parathion to paraoxon on particulate matter, whether on foliage (SPEAR et al., 1974) or at the soil surface. The particulate matter appears to contribute to the accumulation of paraoxon, either by enhancing oxidation of parathion to paraoxon or by decreasing dissipation of paraoxon.

Agricultural Workers' Diseases↗
PubMed1975

Computed tomography with the EMI scanner in the diagnosis of primary and metastatic intracranial neoplasms.

The findings and diagnostic results in 600 examinations of primary and metastatic intracranial neoplasms performed at one hospital with the EMI scanner are presented and the effectiveness of this method is compared with that of radionuclide imaging, cerebral angiography, and pneumoencephalography. The computed scan proved to be highly reliable in the diagnosis of glioma, cerebral metastases, meningioma, and acoustic neuroma.

Adenocarcinoma↗
PubMed1975

Cerebral infarction diagnosis by computerized tomography. Analysis and evaluation of findings.

CT has been found to be of value in cerbrovascular disease. In acute infarcts, the CT (before anticoagulation) excludes intracerebral hemorrhage. The CT may not exclude small petechial hemorrhagic infarctions (with negative cerebrospinal fluid). Angiography, otherwise, is more informative, disclosing ulcerative, irregular plaques, senosis, emboli, etc. In old infarcts, the CT may differentiate an old infarct from a tumor in a patient with focal seizures. Angiography and radionuclide scans are less informative. CT is a valuable investigative agent for clinico-anatomic correlation in cerebrovascular disease.

Adult↗
PubMedDate not supplied

Focal cerebral infarction in the newborn: a distinct entity.

Recent reports, which described early computed tomography findings of unsuspected cerebral arterial infarctions in term newborns who presented with seizures, prompted a review of our neonatal intensive care unit records. Seven newborns demonstrated arterial infarctions by computed tomography. Five of the 7 had focal motor seizures and 2 had generalized seizures. Electroencephalograms of 6 infants correlated with the area of infarct, mainly disclosing focal spike- and/or sharp-wave activity. All infarcts involved the territory of the middle cerebral arteries and all were evident on initial scans. Subsequent examinations at age 12 months to 9 years demonstrated 4 children with spastic hemiparesis, and 3 children with normal neurologic examinations. Neonatal cerebral arterial infarction is a distinct entity which should be recognized and should be included in the differential diagnosis of neonatal seizures, regardless of the presenting symptoms or predisposing factors.

Cerebral Infarction↗
PubMedDate not supplied

Recognition of the avirulence gene avrB from Pseudomonas syringae pv. glycinea by Arabidopsis thaliana.

The response of Arabidopsis thaliana land race Columbia to the bacterial pathogen Pseudomonas syringae pv. maculicola 4326 harboring cloned avirulence genes avrB and avrC from P. syringae pv. glycinea and avrA and avrD from P. syringae pv. tomato was examined. Only avrB was recognized by Columbia, as evidenced by attenuation of disease symptoms, slower bacterial multiplication in planta, and differentially greater induction of mRNA for several defense-related genes. This contrasts with two A. thaliana land races where P. s. pv. maculicola strains containing avrB were not recognized. These plants showed typical disease symptoms, and bacterial multiplication in planta was not reduced in response to P. s. pv. maculicola containing avrB. In addition, there was no differential induction of defense-related mRNAs in these susceptible land races after infiltration with bacteria containing or lacking avrB. These results extend previous observations that avirulence genes from pathogens of one host plant can be recognized by "nonhost" plants and provide the genetic framework for analysis of the plant-specified response to the bacterial avrB gene product in A. thaliana.

Arabidopsis↗
PubMedDate not supplied

Role of the phytotoxin coronatine in the infection of Arabidopsis thaliana by Pseudomonas syringae pv. tomato.

The role of the phytotoxin coronatine in the virulence of Pseudomonas syringae pv. tomato in Arabidopsis thaliana was evaluated by comparing symptom development, in planta bacterial multiplication, and the induction of defense-related genes in Arabidopsis plants inoculated with the coronatine-producing (Cor+) P. s. pv. tomato strain DC3000 and the coronatine-defective (Cor-) strain DC3661 by either infiltration or dipping methods. The Cor+ strain, P. s. pv. tomato DC3000, caused severe disease symptoms and multiplied by 4-6 logs after inoculation by either infiltration or dipping. P. s. pv. tomato DC3661 failed to produce any disease symptoms and multiplied by only 1-1.5 logs in dipped plants, whereas it caused mild symptoms and multiplied 6 logs over the 4-day experimental period in plants inoculated by infiltration. Parallel experiments using a natural host, tomato, yielded similar results. Analysis of the accumulation of mRNAs encoded by several distinct defense-related genes in Arabidopsis leaves infiltrated with either DC3000 or DC3661 demonstrated that the Cor- strain consistently induced higher levels of these transcripts. These results demonstrate that coronatine production is required under more natural inoculation conditions for the successful infection of Arabidopsis by DC3000, and that coronatine may play a critical role during the early stages of infection by suppressing the activation of defense-related genes.

Amino Acids↗
PubMedDate not supplied

Metastatic renal cell carcinoma manifesting as a nasal mass: CT findings.

The clinical and radiological findings in a 71-year-old woman with a metastatic renal cell carcinoma to the right nasal cavity are presented. The kidney tumor manifested clinically as epistaxis. Computed tomography revealed an expansile lesion in the right nasal cavity with extension to the right antrum, right ethmoid sinus, and left nasal cavity. There was no lytic bone destruction, but there was displacement of bone caused by the expansile tumor mass.

Aged↗
PubMedDate not supplied

Susceptibility induced MR line broadening: applications to brain iron mapping.

Magnetic susceptibility variations due to the presence of iron in neural tissue can result in a shift of local resonance frequency, decreased T2 resulting from water diffusion through local field gradients, and line broadening due to field inhomogeneity within a voxel. In this study, modified spin echo phase contrast pulse sequences were used to map proton resonance line widths in phantoms and in vivo. In agar gels containing varying concentrations of Fe3O4 (magnetite), line broadening mechanisms permitted accurate spatial localization of iron deposits from measurement of local resonance line widths. Furthermore, line widths estimated from the data were strongly correlated with iron concentrations, indicating the potential quantitative applications of the method. The technique was applied clinically to map iron in subacute brain hemorrhages. These data suggest that resonance line widths may be a useful measure of brain iron content.

Adult↗
PubMedDate not supplied

Angiographic appearance of carotid occlusion in acute stroke.

The angiographic appearance of the proximal end of internal carotid artery occlusion is reported in 41 patients with acute stroke in the areas of the brain supplied by the carotid artery. All patients had angiography within 6 days of stroke onset, the majority within 24--48 hours. Three angiographic configurations of internal carotid occlusion were found, in descending order of frequency: a sharp, pointed stump; virtual absence of the artery; and a rounded, blunt stump. The results suggest that the angiographic appearance of the proximal occlusion alone may not accurately predict the age of the occlusion within the first 6 days from stroke onset.

Acute Disease↗