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Biomedical subjects

D L Miller

Publications and source records attributed to D L Miller.

At least 577 records · Page 32Linked to original sources
PubMedDate not supplied

Pre-operative localization and interventional treatment of parathyroid tumors: when and how?

A variety of diagnostic tests are currently used for parathyroid localization. In patients who have not had previous surgery, none of these are as sensitive or specific for the localization of abnormal parathyroid glands as an experienced surgeon. In these patients, no pre-operative localization procedures are normally needed. Patients who have had previous thyroid or parathyroid surgery require pre-operative localization. Noninvasive imaging procedures (ultrasound, scintigraphy, computed tomography, magnetic resonance imaging) should be performed until an abnormal gland is identified in the same location on at least 2 examinations. The order in which these studies are performed is not important. In the 50% to 70% of patients in whom noninvasive studies are inconclusive, suspicious lesions may be aspirated or biopsied with imaging guidance. If this cannot be done or is nondiagnostic, angiography and, if necessary, parathyroid venous sampling should be done. Intra-operative ultrasound examination of the neck is helpful during re-operations. In selected patients, parathyroid tumors may be ablated by injection of contrast material through an angiographic catheter into the artery supplying the gland, or by percutaneous injection of alcohol into the gland itself. Angiographic ablation is best used for mediastinal glands supplied by the internal thoracic artery or by a descending branch of the inferior thyroid artery. Percutaneous alcohol injection may injure the recurrent laryngeal nerve permanently and should be limited to the rare patient with a neck lesion who has a prohibitive surgical risk. Neither technique is as effective as surgery.

False Positive Reactions↗
PubMedDate not supplied

Ultrasonic gas-body activation in Drosophila.

The role of gas bodies in the interaction of Drosophila eggs and larvae with ultrasonic fields has been studied (1) by direct microscopic examination, (2) by observation of gas body activation during sonation with a special microscope, (3) by direct measurement of the volume fraction of gas in eggs and (4) through the absorption of ultrasound. All approaches provide support for the postulate that these organisms contain a rich distribution of gas bodies which play a dominant role in the acoustic properties of eggs and are the most probable site of action for ultrasonic biological effects on these organisms.

Absorption↗
PubMedDate not supplied

Further investigations of ATP release from human erythrocytes exposed to ultrasonically activated gas-filled pores.

Suspensions of human erythrocytes in a firefly-extract solution were exposed to 2.0 MHz ultrasound in the presence of 3.4 microns dia. gas-filled pores. Lysis of the cells during ultrasonic exposure resulted in the release of ATP which produced light upon interaction with the firefly extract. The response was approximately proportional to the square of the SPTA intensity I for both continuous and pulsed exposures (1 mu s pulses, 1:9 duty cycle) within the range 5-100 mW/cm2. One method of graphical data presentation yielded an apparent threshold for the effect at 0.31 bar pressure amplitude; however, a response could probably be obtained at any nonzero exposure level with a sufficiently sensitive apparatus. The response was also proportional to the exposure duration t for the range 0.03-3 s. The product I2 t may have some significance as a dosage parameter for this system in an, as yet, undefined "low-dose" range. Measurements for exposures with higher intensities, longer durations, lower duty factors and with pulses longer than 300 mu s deviated from these trends.

Adenosine Triphosphate↗
PubMedDate not supplied

A search for ultrasonic cavitation within the canine cardiovascular system.

Resonant bubble detectors (RBD) were used to search for both pre-existing bubbles and bubbles created by cavitation within the cardiovascular system of 22 dogs. No pre-existing bubbles of 3.8 micron diam or larger were found, nor were any created by exposing the left ventricle to 0.51-1.61 MHz ultrasound of up to 16 W/cm2 spatial-peak intensity. Bubbles introduced into the arterial system by high speed injection were readily detected and could be held in the heart by 1 MHz ultrasound at 1-2 W/cm2 or above. A surprising observation was that gas bubbles of resonant size injected into the left ventricle and held by ultrasound did not multiply continuously as happens in saline or water in vitro. This in vivo system was designed to assess the potential for cavitation bioeffects and the essentially negative results obtained may limit the expected or potential risk of this mechanism in regard to medical applications of ultrasound.

Animals↗
PubMedDate not supplied

Microstreaming shear as a mechanism of cell death in Elodea leaves exposed to ultrasound.

The hypothesis that ultrasonically induced membrane damage and cell death in Elodea leaves is caused by shear stress associated with microstreaming flow generated in the vicinity of oscillating gas-filled channels between the cells is investigated. Cell death thresholds as a function of frequency seem to follow a condition of constant shear stress, with minimum thresholds near the resonance frequency of a gas-filled channel. Theoretical estimates of the shear stress generated within the cells at the ultrasonic intensity of the cell death threshold are in order of magnitude agreement with measurements of the shear stress required for lysis of blood cells. Furthermore, the dependence of the cell death thresholds on exposure duration seems to correspond roughly with the dependence of critical shear stress for blood cells as a function of the duration of the stress. Membrane damage induced by microstreaming shear stress therefore appears to be a plausible mechanism of cell death in Elodea, and a valuable unifying concept for consideration of bioeffects of ultrasonic cavitation.

Cell Membrane↗
PubMedDate not supplied

Effects of dietary fat, nutrition labels, and repeated consumption on sensory-specific satiety.

This study investigated whether energy from fat, nutrition information, and/or repeated consumption of a palatable snack food affects the development of sensory-specific satiety (SSS). Participants (51 males and 44 females) ate an afternoon snack of potato chips in a laboratory for two 10-day (Monday-Friday) sessions in a repeated measures, cross-over design. In one 10-day session, participants were given regular, full-fat potato chips (22.2 kJ/g; 150 kcal/oz) and, in the other, they were given potato chips made with olestra (11.8 kJ/g; 80 kcal/oz), a non-absorbable fat replacer. Information about the fat and energy content of the chips was provided to half the participants, while the other half was not informed. In both sessions, participants were instructed to consume the potato chips ad libitum. Initial ratings of sensory properties of the two types of chips did not differ significantly. In SSS tests, participants rated sensory properties of the chips and four test foods (turkey, strawberry yogurt, cookie, and carrot) on days 1, 5, and 10 of the 10-day sessions. Following consumption, ratings of pleasantness of taste and texture and prospective consumption of both types of chips declined compared to the test foods. Further analyses showed that the development of SSS was not affected by the fat and energy content of the chips, the provision of nutrition information, or repeated consumption.

Adult↗
PubMedDate not supplied

Clinical evaluation of the efficacy and safety of an ultrasonic toothbrush system in an elderly patient population.

Twelve dentulous patients, age 65 or older, with no medical or pharmacologic predisposition to gingival hyperplasia were enrolled in a controlled clinical trial to evaluate the effect of the unaided use of an ultrasonic toothbrush on supragingival plaque and gingival bleeding. Subjects used the ultrasonic toothbrush in lieu of their conventional toothbrushes for a 30-day period. Clinical measurements of the plaque index and bleeding index were made at baseline and at 15 and 30 days. At the end of the 30-day test period, the use of the ultrasonic toothbrush resulted in significant reductions in plaque score, proportion of high plaque surfaces, and bleeding index. The reduction of the bleeding index indicates significant improvement in oral health. In this study, the use of an ultrasonic toothbrush effectively improved oral hygiene and health in a population that often exhibits decreased manual dexterity. Strategies for oral health care assessment and education for guidance of effective interventions are included in checklist form; level of care classification, cost in both time involved and equipment, and purchase instructions also are discussed. Further study is warranted to evaluate this instrument for cognitively impaired elders, who often rely on caregivers for oral hygiene procedures.

Aged↗
PubMedDate not supplied

Experimental comparison of EOE-13 and perfluoroctylbromide for the CT detection of hepatic metastases.

The relative advantages of EOE-13 and perfluoroctylbromide (PFOB) as contrast agents were evaluated using CT scanning in animals with implanted liver tumors. Three criteria were used to compare these compounds: (1)the density difference between liver and tumor, (2)the presence of opacification of intrahepatic vascular structures, and (3)the presence of ring enhancement around the tumors. All three radiographic features were superior in the scans after injection of 5 g/kg of PFOB. When a reduced dose (1.7 g/kg) of PFOB was used, however, the scans obtained with EOE-13 were of approximately equal quality. It is concluded that if toxicity problems prevent administration of PFOB in humans, then EOE-13 will probably remain the contrast agent of choice for tumor imaging in the liver.

Animals↗
PubMedDate not supplied

CT evaluation of hepatic and splenic trauma with EOE-13. An experimental study in monkeys.

EOE-13 is a liver-spleen specific CT contrast agent currently undergoing clinical trials. It is an aqueous emulsion of iodinated fatty acids. We studied eight rhesus monkeys with surgically created blunt trauma to the liver and spleen. The animals were examined using CT scans without contrast material and CT scans with EOE-13. Scans were performed at times between 3 hours and 24 hours after trauma. The presence of parenchymal injury was shown better EOE-13 (P less than 0.01). The use of EOE-13 permitted earlier diagnosis in both the liver and spleen. This contrast agent has potential for the evaluation of trauma in clinical practice, and may be particularly useful in children.

Animals↗
PubMedDate not supplied

Calcification of pseudomyxoma peritonei following intraperitoneal chemotherapy: CT demonstration.

Pseudomyxoma peritonei is essentially mucinous ascites, resulting from the intraperitoneal rupture of a malignant mucinous lesion with seeding of peritoneal surfaces. We report a case of pseudomyxoma peritonei from a perforated mucinous adenocarcinoma of the appendix in which radiographically demonstrable punctate calcifications developed during the course of intraperitoneal chemotherapy.

Adenocarcinoma, Mucinous↗
PubMedDate not supplied

Gadolinium DTPA enhanced MR imaging of ACTH-secreting microadenomas of the pituitary gland.

Gadolinium diethylenetriamine pentaacetic acid (DTPA) enhanced magnetic resonance imaging was performed in eight patients with Cushing disease and surgically proven pituitary microadenomas. A 1.5 T scanner was used with 3 mm contiguous slices. Short repetition times (TR), short echo times (TE), and long TR, long TE sequences were obtained before and serially after intravenous administration of Gd-DTPA. Three of eight (38%) microadenomas were undetectable both without and with Gd-DTPA: one post-Gd-DTPA scan was false positive on the side opposite the adenoma. Hemihypophysectomy based on a petrosal sinus adrenocorticotropic hormone (ACTH) gradient cured all three patients. Two microadenomas (25%) were visible as hypointense foci following Gd-DTPA but not on unenhanced scans. The remaining three microadenomas (38%) were seen before and after Gd-DTPA on T1-weighted images. In this small series of ACTH-producing microadenomas, one-third were seen on unenhanced 1.5 T scans, one-third were seen only after Gd-DTPA, and one-third were not imaged even with Gd-DTPA enhancement.

Adenoma↗
PubMedDate not supplied

Hepatic perfusion during hepatic artery infusion chemotherapy: evaluation with perfusion CT and perfusion scintigraphy.

The standard method for the evaluation of hepatic perfusion during hepatic artery infusion (HAI) chemotherapy is planar hepatic artery perfusion scintigraphy (HAPS). Planar HAPS was performed with 2 mCi of [99mTc] macroaggregated albumin infused at 1 ml/min and compared with single photon emission CT (SPECT) HAPS and with a new study, CT performed during the slow injection of contrast material through the HAI catheter (HAI-CT). Thirteen patients underwent 16 HAI-CT studies, 14 planar HAPS studies, and 9 SPECT HAPS studies. In 13 of 14 studies (93%) HAI-CT and planar HAPS were in complete agreement as to the perfusion pattern of intrahepatic metastases and normal liver. In nine studies where all modalities were performed, the findings identified by HAI-CT and planar HAPS agreed in all cases, whereas the results of two SPECT scans disagreed with the other studies. With respect to perfusion of individual metastases, 14 of 14 HAI-CT studies, 12 of 13 planar HAPS studies, and 9 of 9 SPECT HAPS studies correctly demonstrated the perfusion status of individual lesions as indicated by the pattern of changes in tumor size determined on CT obtained before and after the perfusion studies. Hepatic artery infusion CT was superior for delineation of individual metastases, particularly small lesions, and for the evaluation of nonperfused portions of the liver. Planar HAPS detected extrahepatic perfusion in four patients, and this was not detected by HAI-CT. We conclude that HAI-CT and scintigraphy are complementary techniques. Hepatic artery infusion CT has advantages for the evaluation of intrahepatic perfusion, and planar HAPS is superior to HAI-CT for the detection of extrahepatic perfusion.

Adult↗
PubMedDate not supplied

CT and MR imaging of massive macronodular adrenocortical disease: a rare cause of autonomous primary adrenal hypercortisolism.

We studied four patients with adrenocorticotropic hormone (ACTH)-independent hypercortisolism due to bilateral massive enlargement of the adrenal glands. The combined weight of the adrenal glands ranged from 69 to 149 g and the adrenal cortex was replaced in three of four patients by multiple nodules ranging from microscopic to 4 cm in diameter. One patient had massive diffuse enlargement. All patients had low or undetectable levels of serum ACTH, absence of petrosal sinus to peripheral gradients of ACTH in bilateral samples from the inferior petrosal sinuses before and after stimulation by corticotropin releasing hormone, and absence of an adenoma on MR imaging of the pituitary gland. The marked degree of adrenocortical enlargement and absence of ACTH dependency separates this massive macronodular disease from the more common ACTH-dependent macronodular hyperplasia encountered in older patients with pituitary-dependent Cushing disease. All patients required bilateral adrenalectomy to control hypercortisolism. We present the spectrum of nodular adrenal disease associated with hypercortisolism and a differential diagnosis based on morphologic criteria.

Adrenal Cortex Diseases↗
PubMedDate not supplied

A developmental test based on the STYCAR sequences used in the National Childhood Encephalopathy Study.

During the National Childhood Encephalopathy Study, standard neurodevelopmental assessments had to be performed on a large number of children under 3 years of age scattered throughout Great Britain. Currently available tests were reviewed but were found to be impractical for this purpose. We describe a simple test procedure, based on the STYCAR sequences, suitable for use in a clinic or at home with the minimum of special equipment. Results were reliable and provided an informative record of a child's developmental progress. It may be possible to modify the scheme for general use.

Acute Disease↗
PubMedDate not supplied

Islet cell tumors of the pancreas: clinical, radiologic, and pathologic correlation in diagnosis and localization.

Islet cell tumors are rare pancreatic or peripancreatic neoplasms that produce and secrete hormones to a variable degree. These tumors are best divided on clinical grounds into those that produce a recognizable, clinically evident endocrine syndrome (ie, functioning) and those that exhibit no clinical evidence of hormone production (ie, clinically silent). Clinically silent tumors produce symptoms due to mass effect because of their large size. They are often partially cystic or necrotic. Functioning islet cell tumors usually manifest earlier in the course of the disease because of the distinctive signs and symptoms of the associated endocrine syndrome. Clinically silent and functioning tumors cannot be histologically distinguished reliably even with the use of immunohistochemical stains. Insulinoma and gastrinoma, the two most common functioning lesions, are typically small homogeneous masses. Other functioning islet cell tumors include glucagonoma, somatostatinoma, vipoma, and adrenocorticotropic hormone-producing tumor. Larger tumors are associated with calcification, cystic degeneration and necrosis, and a more aggressive behavior (local and vascular invasion as well as distant metastases). There are many different techniques for detection and characterization of these lesions that are usually chosen according to the radiologist's experience and preference. Treatment and prognosis of these lesions depend on the hormone produced, their size, and their behavior.

Adenoma, Islet Cell↗
PubMedDate not supplied

Sexual behaviour among London GUM clinic attenders: implications for HIV education.

The aim of this study was to describe the sexual behaviour of a sample of genitourinary medicine (GUM) clinic attenders, 5 years after the launch of the UK government HIV media campaigns. A gender-specific and anonymous cross-sectional self-completion questionnaire was modified from the National Survey of Sexual Attitudes and Lifestyle and completed by 250 men and 250 women. The majority of the respondents were in their twenties, lived in London and were employed or students. Sixty-eight per cent of the men reported that one or more of their last 3 partners was not a regular partner. For those men whose last sexual encounter was with a new partner, 27% of heterosexuals and 33% of homosexuals reported using a condom. Fifty-one per cent of women reported one or more non-regular partners among their last 3 partners. For those women whose last sexual encounter was with a new partner, 43% of heterosexuals and 75% of bisexuals used a condom. Seventy-eight per cent of men and 75% of women had had a previous sexually transmitted disease (STD). These findings highlight the persistence of practices associated with the risk of contracting or transmitting HIV infection and which needs to be addressed in future educational campaigns. The GUM clinic population is an important population to monitor over time, either by longitudinal or serial cross-sectional studies. The results of this study provide a baseline against which to gauge the effects of future educational interventions.

Adult↗