PubMed Health⌕ Search

Biomedical subjects

A S Watanabe

Publications and source records attributed to A S Watanabe.

At least 19 recordsLinked to original sources
PubMed1992

Flow dynamics of cerebrospinal fluid: assessment with phase-contrast velocity MR imaging performed with retrospective cardiac gating.

To visualize the flow of cerebrospinal fluid (CSF) throughout the ventricles and subarachnoid space, measure mean and maximum CSF velocities, and quantitate CSF flow through the aqueduct of Sylvius, magnetic resonance (MR) imaging was performed with a sagittal technique that is flow-sensitive in the craniocaudal direction (along the readout axis) and a high-resolution axial technique sensitive to through-plane flow in three healthy subjects and 19 patients with known or suspected disorders of the CSF circulation. In both techniques, retrospective cardiac gating was used to cover the complete cardiac cycle. The sagittal technique was superior in overall assessment of CSF flow dynamics, including the motion of adjacent brain parenchyma. The high-resolution axial technique provided an accurate measurement of the rate of CSF flow through the aqueduct; only this technique provided sufficient accuracy to enable distinction between normal and hyperdynamic CSF flow. It is concluded that assessment of CSF flow dynamics is a useful adjunct to routine MR imaging in communicating and obstructive hydrocephalus.

Adult↗
PubMed1991

Marked cerebrospinal fluid void: indicator of successful shunt in patients with suspected normal-pressure hydrocephalus.

The authors blindly reviewed the charts of 20 patients with normal-pressure hydrocephalus (a disease of unknown cause characterized radiologically as chronic communicating hydrocephalus and clinically by gait apraxia, dementia, and incontinence) who had undergone creation of a ventriculoperitoneal shunt. The initial clinical response to surgery was graded excellent, good, fair, or poor; 5-year follow-up was available in 55% of cases. The magnetic resonance (MR) images obtained in these patients were also blindly reviewed for the magnitude of cerebrospinal fluid (CSF) flow void (graded on the basis of extent rather than degree of signal loss) in the cerebral aqueduct. A significant (P less than .003) correlation existed between good or excellent response to surgery and an increased CSF flow void. The presence of associated deep white matter infarction on MR images did not correlate with a poor response to surgery. On the basis of these findings, it is suggested that patients who fulfill the clinical criteria of NPH and have an increased CSF flow void undergo creation of a shunt.

Aged↗
PubMed1990

Retropharyngeal space: evaluation of normal anatomy and diseases with CT and MR imaging.

A retrospective analysis of computed tomographic (CT) and magnetic resonance (MR) images and clinical records of 39 patients with retropharyngeal space (RPS) lesions was completed. The review was undertaken to answer the following questions: (a) what is the spectrum of lesions of the RPS? (b) what imaging features mark a lesion as originating in the RPS? and (c) is there a difference between the radiologic pattern of the suprahyoid and infrahyoid portions of the neck? Of the 39 patients in the study, nine had RPS infections, 17 had RPS malignancies, two had benign tumors, seven had RPS pseudotumors, and four had hematoma or air in the RPS after trauma. RPS lesions demonstrated two distinct radiologic patterns: a nodal pattern and a nonnodal pattern. The nodal pattern, found only in the suprahyoid neck, occurs when infection or tumor begins in the lymph nodes of the RPS. The lesions may be unilateral or bilateral, but the middle part of the RPS is spared. The nonnodal pattern, found primarily in the infrahyoid RPS, results when the infection or tumor directly invades the RPS or goes beyond the nodes of the RPS. The nonnodal lesion appears rectangular and spans the RPS from side to side.

Carcinoma, Squamous Cell↗
PubMed1986

Systemic absorption of gallbladder sclerosing agents in the rabbit. A preliminary study.

The absorbed levels of ethanol or tetracycline, used as gallbladder sclerosing agents, were measured in the systemic blood circulation of 16 rabbits. The maximal systemic level of ethanol was 46 mg/dl and of tetracycline was 4.6 micrograms/ml after 30 minutes of gallbladder exposure. Comparable serum levels would be considered nontoxic in humans. As a gallbladder sclerosing agent, tetracycline (50 mg/cc) was slightly more effective than 95% ethanol exposed for either 15 or 30 minutes.

Animals↗
PubMed1985

Detection of low levels of urinary mutagen excretion by chemotherapy workers which was not related to occupational drug exposures.

Urine specimens from a total of 26 subjects who were either nurses, pharmacists, or pharmacy technicians engaged in the preparation, handling, or administration of cancer chemotherapeutic agents were analyzed for the presence of mutagenic substances. Assays were performed using bacterial strains TA98 and TA100 in the Salmonella/mammalian microsomal mutagenicity assay developed by Ames et al. (Mutat. Res., 31: 347-364, 1975). Findings were compared with results from similar assays of urine specimens for 38 hospital personnel not exposed to cancer chemotherapeutic agents. There was no evidence of an association between occupational exposure to chemotherapy drugs and the presence of mutagenic substances that could be detected by this assay procedure in either specimens of filter-sterilized urine or extracts of urine concentrated with XAD-2 resins. An association was observed, however, between smoking and increased urinary excretion of mutagens. None of the observed associations was changed substantially by statistical adjustment for the occupational category of the subject (nurse or pharmacist), hospital of employment, or values of concurrent solvent controls for the mutagenesis assays. Associations with occupational exposures were not changed by controlling for smoking history. In addition to the large increases for smokers, testing of extracts of urine from nonsmokers with bacterial strain TA98 yielded mutagenicity values that averaged about 50% higher than values for solvent controls. Similar small increases were observed in previous published reports of human urine mutagenicity assays using tester strains TA1538 and TA98. We found little evidence to suggest that the small increases observed for nonsmokers were associated with technical factors such as the presence in the extracts of histidine or other substances promoting bacterial growth or contamination of the specimens during collection or extraction procedures. Since it appears that technical factors can be excluded, we believe that the increases were associated with urinary excretion of low levels of mutagen by a high proportion of subjects tested. The lack of an association of mutagenicity with occupational exposure to chemotherapeutic drugs may have been due to protective measures at the hospitals surveyed and suggests that, with appropriate procedures, these agents can be administered in a manner such that human exposure cannot be detected using this approach.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibiotics, Antineoplastic↗
PubMed1980

Podophyllum: suspected teratogenicity from topical application.

A case demonstrating suspected teratogenic effects of topical podophylium is presented. Podophyllum resin was applied five times for a duration of 4 hr from the 23rd to the 29th week of pregnancy. At birth a simian crease on the left hand and a preauricular skin tag were noted. It is suggested that podophyllum be avoided during pregnancy. Alternative treatment for warts of the vaginal, perineal, or anal area are presented.

Abnormalities, Drug-Induced↗
PubMed1979

Phenothiazine-induced ventricular tachycardia following acute overdose.

The chronic use of phenothiazine is known to result in ventricular arrhythmias in certain patients. The occurrence of cardiac abnormalities following acute phenothiazine overdose is less well documented. Phenothiazine-induced ventricular tachycardia, when it occurs in the overdose situation, may be refractory to conventional antiarrhythmic drugs. We present a case in which the usual therapy was unsuccessful. Only after a transvenous pacemaker was inserted was the patient's condition reversed.

Adult↗
PubMed1979

Drug information--the problems and some solutions.

Several problems evident in the drug information delivery process and some solutions are presented. Major problems with current sources of drug information are accessibility of data, completeness of data, validity of information, appropriateness in the clinical setting, and currency. Better drug information sources are needed to provide rapid answers to patient-related questions routinely occurring in the clinical setting. Currently available mechanisms described to solve existing drug information problems are clinical pharmacologists and specialists, clinical pharmacists, drug information centers, and a computer-output microfiche drug information system (DRUGDEX).

Anticoagulants↗
PubMed1979

Clonidine overdose: a review.

The pharmacology and pharmacokinetics of clonidine and the symptoms and treatment of acute clinidine overdosage are reviewed. Clonidine, a relatively safe and effective antihypertensive agent when used at therapeutic dosages, reduces blood pressure through a centrally mediated reduction in vasomotor tone. The primary symptoms of clonidine overdosage are central nervous system depression, bradycardia, hypotension, miosis, hypotonia, respiratory depression and possibly seizures. Gastric lavage followed by administration of activated charcoal is used to decrease absorption following acute oral ingestion. Intravenous fluid therapy and dopamine infusion are recommended for severe hypotension, and atropine sulfate is used to manage persistent bradycardia. Treatment of hypotension with alpha-adrenergic blocking agents (e.g., tolazoline) is not recommended unless patients fail to respond to dopamine infusion and administration of i.v. fluids.

Adolescent↗
PubMed1978

Acute digoxin poisonings: review of therapy.

Acute digoxin poisoning, its recognition and management, are reviewed. The uses of syrup of ipecac, gastric lavage, activated charcoal, cholestyramine, colestipol, edetate sodium and cathartics as measures to terminate the drug exposure are discussed. Measures to hasten digoxin elimination, such as the use of furosemide, hemodialysis and digoxin-specific antibodies are reviewed. Supportive management may include treatment with atropine, phenytoin, lidocaine, propranolol, glucose, insulin and sodium polystyrene sulfonate. Proper management of digoxin poisoning involves the use of standard decontamination procedures (emesis or gastric lavage). Activated charcoal is strongly recommended, followed by rapidly acting cathartics. Antiarrhythmic therapy usually involves atropine sulfate and phenytoin sodium.

Acute Disease↗
PubMed1975

Systematic approach to drug information requests.

A five-step systematic technique used for answering drug information requests is described. Step 1 is classification of the request. Step II involves determination of exactly what information is being requested and why, and ensuring that all pertinent background data are obtained. Step III is a systematic search of the literature, beginning with general references and progressing through secondary sources to primary articles. Step IV is formulation of the accumulated data into an appropriate writtern of verbal response. Step V involves reclassification of the request which may be necessary if there is a change in its scope.

Information Services↗
PubMedDate not supplied

Common-source community and industrial exposure to trichloroethylene.

In July 1979, 1,900 gallons of trichloroethylene (TCE) were released into ground and surface water from a pipe manufacturing plant in Montgomery County, Pennsylvania. To evaluate community and occupational exposure to TCE, we conducted environmental and medical surveys. In well water samples obtained in August 1979 within 1 km of the factory, TCE concentrations ranged to 183,000 parts per billion (ppb); EPA's proposed guideline for TCE in drinking water is 5 ppb. Levels of TCE declined with distance from the plant and decreased in the months following the spill. However, lower level TCE contamination was widespread and persistent, suggesting multiple releases. Within the plant, mean time-weighted occupational exposure to TCE of degreaser operators was 205 mg/m3; the recommended time-weighted exposure limit is 135 mg/m3. Mean short-term exposure was 1,084 mg/m3; the recommended short-term limit is 535 mg/m3. Seven of 9 exposed workers reported drowsiness, dizziness, or mental confusion. In exposed workers, mean urinary excretion of TCE metabolites rose from 298 micrograms/L pre-shift to 480 micrograms/L post-shift. On re-evaluation of the factory following improvements in ventilation and work practices, mean time-weighted occupational exposure to TCE had decreased to 84 mg/m3 and short-term exposure to 400 mg/m3; symptom frequency and concentrations of urinary TCE metabolites also were reduced. This episode demonstrates that community and occupational exposure to chemical toxins may share a common origin.

Environmental Exposure↗
PubMedDate not supplied

Computed tomography and angiographic findings in metastatic choriocarcinoma.

We report a patient with metastatic gestational choriocarcinoma who presented with headaches, speech difficulties, motor aphasia, facial weakness, hemiparesis, and a large intraparenchymal hematoma. She subsequently developed a total of five intraparenchymal hemorrhages. Her clinical presentation posed a diagnostic dilemma and emphasizes the importance of a complete differential diagnosis of multiple intracranial hemorrhages. The features of CNS choriocarcinoma are reviewed.

Adult↗