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Biomedical subjects

D L Miller

Publications and source records attributed to D L Miller.

At least 235 records · Page 13Linked to original sources
PubMed1992

Cardiopulmonary resuscitation: how useful? Attitudes and knowledge of an elderly population.

Two hundred forty-eight elderly outpatients completed a survey designed to assess knowledge about the procedural aspects and efficacy of in-hospital cardiopulmonary resuscitation. We found that older people overestimate the percentage survival to actual hospital discharge following in-hospital cardiopulmonary resuscitation by nearly 300%. Most older people also have definite opinions about the appropriate application of cardiopulmonary resuscitation for different clinical circumstances. Most believe that patients with advanced Alzheimer's disease or widespread cancer should not be resuscitated, while patients with depression or early Alzheimer's disease should. Inaccurate beliefs about cardiopulmonary resuscitation efficacy can adversely impact on decision making about resuscitation by older patients. Educational efforts for the elderly may lead to more informed decision making and thereby more appropriate use of this technology.

Aged↗
PubMed1992

Measurement of magnetically induced electric fields in conductive media near a 60 Hz current-carrying wire.

Electric fields induced in a conductive body by the magnetic field of a current-carrying wire were analyzed theoretically and experimentally to assess the dosimetric importance of highly nonuniform, field-exposure conditions. Experimentation revealed that a 60-Hz magnetic field was inversely proportional to the radius of a wire bundle carrying 100 A within a 0.5-m2 test area. A miniaturized electric field probe was used to measure the electric fields induced in 5-cm-deep, saline-filled models. In the theoretical analysis, numerical estimates of induced fields were made by a spreadsheet method. The theoretical calculations and the measured values of induced electric fields were generally in good agreement. The induced fields were in a plane perpendicular to a vertically incident magnetic field; the maximally induced fields were in areas nearest the wire bundle. The strength of the induced field increased with model size: from 96 microV/cm in a 10 x 10 cm model to 176 microV/cm in a 40 x 40 cm model. The strength of the field induced in a 20 x 20 cm model decreased with increasing model-to-wire spacing: from 132 microV/cm for a 1-cm spacing (2-mT maximum, incident field) to 50 microV/cm for a 6-cm spacing (0.33-mT maximum). The results indicate that increases in local values of nonuniformly incident fields produce relatively small increases in induced electric fields. This finding may be important in dosimetric consideration of circumstances, such as use of electric blankets, in which fields of low average strength are accompanied by intense local fields.

Electric Conductivity↗
PubMed1992

Videothoracoscopic wedge excision of the lung.

Recent advances in video technology and endoscopic instrumentation have expanded the use of thoracoscopy from diagnosis to treatment of pulmonary parenchymal disease. We recently performed 14 pulmonary wedge excisions using videothoracoscopic techniques in 10 patients (7 women and 3 men). Median age was 60 years (range, 21 to 82 years). Indications were small peripheral solitary pulmonary nodules in 4 patients, diffuse pulmonary infiltrates in 4, and recurrent pneumothoraces in 2. Thoracoscopic wedge excisions were accomplished using double-lumen endotracheal anesthesia and a percutaneous stapling device. Tissue diagnosis was obtained in all patients; 6 had benign disease, 3 had metastatic cancer, and 1 had diffuse bronchoalveolar cell carcinoma. Median operating time was 90 minutes (range, 40 to 140 minutes). There were no operative deaths. The single complication was a prolonged air leak. Median hospitalization was 5 days (range, 3 to 16 days). All patients returned to full activity within 10 days of discharge. Median follow-up was 6 months (range, 5 to 8 months). We conclude that videothoracoscopic wedge excision is a safe and effective procedure for selected small peripheral indeterminate pulmonary nodules, diffuse interstitial lung diseases, and recurrent spontaneous pneumothoraces. Further evaluation and prospective studies are indicated.

Adult↗
PubMed1992

Isolation and high-resolution mapping of new DNA markers from the pericentromeric region of chromosome 10.

The gene responsible for multiple endocrine neoplasia type 2A (MEN 2A) has been localized to the pericentromeric region of chromosome 10. Several markers that fail to recombine with MEN2A have been identified, including D10Z1, D10S94, D10S97, and D10S102. Meiotic mapping in the MEN2A region is limited by the paucity of critical crossovers identified and by the dramatically reduced rates of recombination in males. Additional approaches to mapping loci in the pericentromeric region of chromosome 10 are required. We have undertaken the generation of a detailed physical map by radiation hybrid mapping. Here we report the development of a radiation hybrid panel and its use in the mapping of new DNA markers in pericentromeric chromosome 10. The radiation-reduced hybrids used for mapping studies all retain small subchromosomal fragments that include both D10S94 and D10Z1. One hybrid was selected as the source of DNA for cloning. One hundred five human recombinant clones were isolated from a lambda library made with pp11A DNA. We have completed regional mapping of 22 of those clones using our radiation hybrid mapping panel. Seven markers have been identified and, when taken together with previously meiotically mapped markers, define eight radiation hybrid map intervals between D10S34 and RBP3. The identical order is found for a number of these using either the radiation hybrid mapping panel or the meiotic mapping panel. We believe that this combination cloning and mapping approach will facilitate the precise positioning of new markers in pericentromeric chromosome 10 and will help in refining further the localization of MEN2A.

Centromere↗
PubMed1992

Anaesthetic modification of regional myocardial functional adjustments during myocardial ischaemia: halothane vs fentanyl.

During myocardial ischaemia, functional compensation occurs by non-ischaemic regions of the left ventricle (LV). Anaesthetics may affect compensation by altering contractility, metabolism and perfusion. This was studied in dogs anaesthetized with fentanyl (150 micrograms kg-1 loading dose and 100 micrograms kg-1 h-1) or 0.75% and 1.5% halothane and subjected to left anterior descending artery (LAD) occlusion. After 15 min of anterior wall ischaemia, cardiac output, mean arterial pressure and LV maximum dP/dt were diminished in the 1.5% halothane but not in the 0.75% halothane or fentanyl groups. In all groups, stroke volume decreased, LV end-diastolic pressure increased and anterior wall function deteriorated (measured as systolic shortening, peak systolic intramyocardial pressure (IMP), regional wall stroke work (RSW) and slope of preload recruitable stroke work curve (Mw)) with ischaemia. Functional changes in the lateral (non-ischaemic) wall were different between groups. Regional function during occlusion in this area improved with fentanyl (mean (SEM) IMP, RSW and Mw increased by 23 (2)%, 37 (3)% and 69 (7)%, respectively), was relatively well maintained with 0.75% halothane and diminished with 1.5% halothane.

Anesthesia, Inhalation↗
PubMed1992

Results of a multidisciplinary strategy for management of mediastinal parathyroid adenoma as a cause of persistent primary hyperparathyroidism.

Persistent primary hyperparathyroidism due to mediastinal parathyroid adenoma was effectively treated by either angiographic ablation or median sternotomy in this study of 49 patients managed at the National Institutes of Health since 1977. Each patient presented here with symptomatic persistent primary hyperparathyroidism after failed initial surgical procedures done at other institutions. Each patient underwent extensive parathyroid localization procedures, including selective angiography, and most had a parathyroid adenoma localized to the mediastinum. Angiographic ablation, the deliberate injection of large doses of contrast material into the artery that selectively perfuses the adenoma, was initially successful in 22 of 30 procedures (73%) in 27 patients. Long-term control of persistent primary hyperparathyroidism was achieved in 17 of 27 patients (63%) by angiographic ablation. Each unsuccessful ablation could be easily salvaged by surgical resection. Surgical resection of the parathyroid adenoma by median sternotomy achieved immediate success in 24 of 24 procedures (p2 less than 0.02 versus ablation), and long-term cure in 23 of 23 evaluable patients (p2 less than 0.001 versus ablation). However, ablation did have benefits for the patients in whom it was successfully performed. It was associated with a significantly shorter hospital stay (median, 6 days versus 9 days for sternotomy, p2 less than 0.003), much less pain, and easier recuperation. Complications of each procedure were transient and similar in both groups. Operative resection is the most effective single means to eradicate mediastinal parathyroid adenoma; however, angiographic ablation can provide similar long-term control of hyperparathyroidism in 63% of patients with less pain and shorter convalescence than that seen in patients after median sternotomy. Our results suggest that angiographic ablation should be attempted as the initial procedure for patients with persistent primary hyperparathyroidism caused by an angiographically identified mediastinal parathyroid adenoma. Operation can be reserved for those who fail ablation.

Adenoma↗
PubMed1992

Zollinger-Ellison syndrome: technique, results, and complications of portal venous sampling.

All 95 portal venous sampling (PVS) procedures performed in patients with Zollinger-Ellison syndrome in the past 10 years at the authors' institution were reviewed. It was possible to catheterize at least one branch of the pancreaticoduodenal venous arcade in all but two procedures (98%). The highest concentration of gastrin was found in a selective sample from the pancreaticoduodenal venous arcade or the transverse pancreatic vein in 56 of 91 procedures (62%). Selective sampling of pancreatic head veins yielded a gastrin gradient sufficient for localization in 60 patients (63%). Among 55 solitary sporadic gastrinomas identified at surgery, PVS allowed correct localization of the tumor in 32 (58%); if selective samples had not been obtained, only eight (15%) would have been localized (P less than .0005). Sensitivity was the same for tumors in the gastrinoma triangle (64%) and the body or tail of the pancreas (60%). There were no false-positive results. The overall complication rate was 20%, but most complications were abdominal pain lasting 3 days or less. Six patients (6%) had serious complications.

Abdominal Pain↗
PubMed1992

Delayed reactions to contrast media after interleukin-2 immunotherapy.

A prospective study was conducted by means of a questionnaire to determine the prevalence of delayed reactions to contrast media administered intravenously (iopamidol) and orally (diatrizoate sodium) in 170 patients who had received interleukin-2 (IL-2) and in 631 patients who did not. Another control group of 100 non-IL-2 patients received only oral contrast medium. Delayed reactions (eg, fever rash, flulike symptoms, joint pain, flushing, pruritus, and dizziness) were reported in 3.9% (25 of 631) of non-IL-2 patients and in 11.8% (20 of 170) of IL-2 patients. Reactions were mild in the non-IL-2 patients but were more severe in the IL-2 patients. Two IL-2 patients required hospitalization. Only rash, flulike symptoms, and pruritus were statistically more common in IL-2 patients than in non-IL-2 patients. The prevalence of delayed reactions to nonionic contrast medium is higher in patients who have received IL-2 than in the general population. Most delayed reactions do not require therapy, but, when necessary, therapy is usually limited to relief of symptoms.

Administration, Oral↗
PubMed1992

Corticotropin-secreting carcinoid tumors of the thymus: diagnostic unreliability of thymic venous sampling.

Three patients with Cushing syndrome due to ectopic production of corticotropin underwent total thymectomy on the basis of elevated concentrations of corticotropin in selective samples from thymic veins but in the absence of a radiographically detectible thymic mass. In one patient, radiologic examination demonstrated hyperplasia of neuroendocrine cells staining positively for corticotropin throughout the thymus but no discrete mass. This patient had complete remission after total thymectomy. The other two patients had no evidence of an intrathymic source of corticotropin, and both had persistent Cushing syndrome. Elevated levels of corticotropin in thymic vein samples may reflect corticotropin production by pulmonary bronchial carcinoid tumors, mediastinal metastases, thymic carcinoids, or diffuse hyperplasia of intrathymic neuroendocrine elements. In the absence of a demonstrable intrathymic mass, corticotropin gradients in thymic veins do not reliably indicate a thymic source of corticotropin and should not necessarily be used as a basis for exploratory thoracotomy or blind thymectomy.

Adrenocorticotropic Hormone↗
PubMed1992

Distinction between hyperaldosteronism due to bilateral hyperplasia and unilateral aldosteronoma: reliability of CT.

Hyperaldosteronism due to a unilateral adenoma must be distinguished from hyperaldosteronism due to bilateral hyperplasia to enable the proper choice between surgical treatment (for adenoma) or medical treatment (for hyperplasia). To compare the efficacy of computed tomography (CT) and adrenal venous sampling, both examinations were performed in 24 patients with primary aldosteronism. All patients with a diagnosis of adenoma based on findings at venous sampling underwent adrenalectomy. The CT-based diagnosis was unilateral aldosteronoma in 17 patients and hyperplasia in seven patients. On the basis of venous sampling, unilateral adenoma was diagnosed in 22 patients; this diagnosis was confirmed by means of unilateral adrenalectomy in 21 patients. The most common error was diagnosis of hyperplasia based on the presence of bilateral nodules on CT scans: In six of seven patients with such a diagnosis, venous sampling and subsequent surgery revealed a unilateral adenoma. In hyperaldosteronism with multiple bilateral nodules, CT cannot reliably permit distinction between hyperplasia and adenoma.

Adenoma↗
PubMed1992

Neurologic complications of petrosal sinus sampling.

Petrosal sinus sampling has been described as an innocuous, essentially risk-free procedure. The authors report on two patients from two different institutions who sustained brain stem injury as a result of petrosal sinus sampling and two other patients in whom brain stem injury was avoided. Major neurologic complications have occurred in only 0.2% of procedures (one of 508) performed at the National Institutes of Health and in 0.5% of a subset of these procedures (one of 184) that were performed with a specially designed petrosal sinus catheter. The cause of these complications is unclear but is presumed to be localized venous hypertension. Tip-deflector catheter-guide-wire systems, if available, are recommended for petrosal sinus sampling. Inadequate data exist to permit recommendation of any other catheter. Brain stem injury is preventable if the catheter is withdrawn at the earliest sign of even a minor, seemingly insignificant problem. Subtle symptoms and signs that may not appear to be neurologic may herald a clinical catastrophe if not heeded.

Adult↗
PubMed1992

Nucleation and evolution of ultrasonic cavitation in a rotating exposure chamber.

The nucleation and progression of ultrasonic cavitation in a rotating exposure chamber were investigated by observing hemolysis of a 0.5% suspension of erythrocytes. Bursts of 1.6 MHz ultrasound beams of 11 W/cm2 spatial peak intensity were synchronized with the rotation to aim the bursts down the axis of a cylindrical chamber. Cavitational hemolysis always occurred in fresh phosphate buffered saline (PBS) solution, but cavitation incidence declined to 38% in 4 day old PBS. The amount of hemolysis for 11 ms or 44 ms bursts with 60 rpm rotation increased in proportion to the number of bursts. Hemolysis was found above a minimum burst duration of 5.5 to 8.3 ms in the normal 2 cm chamber. This did not appear to change for 1 cm or 4 cm chamber lengths, but it did change to about 2.2 ms and about 44 ms for over- and undersaturated gas conditions, respectively. Off-times associated with rotation speeds of 15 to 30 rpm reduced the effectiveness of the cavitation, and addition of fixed cells at only 0.01% to 0.02% greatly reduced the hemolysis. For this ultrasonic exposure system, several thousand bubbles, possibly generated from as few as one cavitation nucleus, move across the chamber at up to 10 m/s, each lysing a few hundred cells, and then are cycled back to the front of the chamber by the rotation to reinitiate the cavitation on the next burst.

Air↗
PubMed1992

Prospective study of the use of intraarterial secretin injection and portal venous sampling to localize duodenal gastrinomas.

BACKGROUND: Duodenal gastrinomas producing Zollinger-Ellison syndrome (ZES) are rarely imaged on preoperative studies. Measurement of serum gastrin levels by transhepatic portal venous sampling (PVS) or by sampling from hepatic veins after intraarterial secretin injection have been advocated as useful tests to identify these tumors before operation. METHODS: As part of a prospective study, selective intraarterial secretin injection has been performed in 36 consecutive patients with ZES, PVS has been performed in 30 of these patients, and the results have been compared. RESULTS: Gastrinomas were found at laparotomy in 33 of 36 patients (92%). Duodenal tumors were found in 18 patients (50%). The remaining patients had liver, pancreatic, or nodal disease (n = 15). Thirty-two of 36 patients (89%) had positive results with intraarterial secretin injection study, whereas 18 of 30 (60%) had a positive PVS gradient (p = 0.02, Fisher's exact test). The most common positive gradient with intraarterial secretin injection was found with injections of the gastroduodenal artery, and the most common positive gradient with PVS was found in the inferior pancreaticoduodenal (IPDV) or superior pancreaticoduodenal vein (SPDV). Fourteen of 18 (78%) patients with duodenal gastrinomas had a positive GDA injection, whereas five of 18 (28%) without duodenal tumors had a positive GDA injection (p = 0.006). Five of 16 patients with duodenal gastrinomas had a positive gradient in the IPDV or SPDV, whereas four of 14 without duodenal tumors had a positive gradient in the IPDV or SPDV (not significant). CONCLUSIONS: Intraarterial secretin injection is more sensitive than PVS at localizing duodenal gastrinomas and should replace PVS in patients with ZES and occult tumors.

Adult↗
PubMed1991

Nintendo neck.

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Child↗