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Biomedical subjects

D Miller

Publications and source records attributed to D Miller.

At least 883 records · Page 49Linked to original sources
PubMedDate not supplied

Conservation of a DPP/BMP signaling pathway in the nonbilateral cnidarian Acropora millepora.

Members of the TGF-beta superfamily of signaling molecules are widespread in metazoans, but the evolutionary origin of particular subclasses of signaling mechanisms is poorly defined. The DPP/BMP class, for example, is implicated in dorsal-ventral patterning, neural patterning, and limb development. Here we report the presence of several components of a DPP/BMP-specific signal transduction cascade in a nonbilateral animal, the coral Acropora millepora. The discovery of these components, a putative type I receptor and two putative receptor-activated Smads, suggests that DPP/BMP signaling predates both dorsal-ventral pattern formation and limb development. We postulate that an ancestral role in neuroepithelial patterning may account for the high level of conservation between DPP/BMP signaling components found in this nonbilateral animal and the more complex triploblastic organisms of the arthropod and chordate phyla.

Amino Acid Sequence↗
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Influence of residential fungal contamination on peripheral blood lymphocyte populations in children.

Reported residential fungal contamination has been associated consistently with increased symptoms among occupants; however, an objective measure of a health effect is lacking, and a pathophysiologic mechanism has not been established. Our objective was to determine if exposure to indoor fungal contamination influenced T-cell differentiation. In this study, we contrasted lymphocyte populations, measured by flow cytometry, between a group of children who lived in homes with considerable fungal contamination (n = 39) and a group in less-contaminated homes (n = 20). Indicators of fungal biomass were viable fungi in house dust and air ergosterol in the child's bedroom. Living in a more-contaminated home versus a less-contaminated home was associated with a larger number of CD3+ T cells expressing CD45RO (1.5 x 10(9)/I versus 1.1 x 10(9)/I, respectively; p = .05, two-tailed t testing) and a reduced CD4/CD8 ratio (1.6 versus 1.8, respectively; p = .04). The differences persisted over a 12-mo period, and they were not explained by the child's age or total serum IgE, dust mite antigens, and the presence of furry or feathered pets or a humidifier. The results suggest that residential fungal contamination leads to chronic stimulation of children's lymphocytes.

Air Microbiology↗
PubMedDate not supplied

Healthcare workers and bloodborne pathogens: knowledge, concerns, and practices.

Occupational exposure of healthcare workers to bloodborne pathogens and the transmission of human immunodeficiency virus and hepatitis B virus warrant study. This study examined issues related to the transmission of bloodborne pathogens in practice. Findings provide information regarding knowledge level, practices of staff in applying universal precautions, and availability of supplies and equipment. The concerns of nurses along with content for educational programs and suggested approaches to education are outlined.

Blood-Borne Pathogens↗
PubMedDate not supplied

Calcium carbonate powder as a phosphate binder.

With increasing recognition of problems regarding the use of aluminum hydroxide as a phosphate binder, calcium carbonate has become the medication of choice. Use of calcium has, however, frequently been associated with development of hypercalcemia. At this institution, calcium carbonate powder as a phosphate binder, examination of its efficacy, and the frequency of hypercalcemia with its use were of great interest. Calcium carbonate powder (CalCarb-HD, 2.4 gms elemental calcium/packet) (CalCarb-HD, Lafayette Pharmacal Inc., Fort Worth, TX) was used in the study. Twenty-one end-stage renal disease (ESRD) patients (17 hemodialysis and 4 chronic ambulatory peritoneal dialysis) were chosen and converted from their previous binder (primarily, calcium carbonate tablets) to calcium powder. The dosage was adjusted to keep phosphorus levels at 3.5 to 5.5 mg/dl and calcium less than 11.5 mg/dl. At 2 months, the average calcium level in the 16 patients remaining in the study was 9.2 mg/dl, and the average phosphorus level was 5.2 mg/dl with an average calcium dose of 1.4 packets/day. By 7 months, the 8 patients remaining in the study had an average calcium level of 9.9 mg/dl with an average phosphorus level of 5.5 mg/dl; average calcium dose was 1.8 packets/day. Total episodes of hypercalcemia (calcium greater than 11.5 mg/dl) were two. Calcium carbonate powder appears to be an effective phosphate binder in the ESRD population. The relatively few episodes of hypercalcemia may be related to possible enhanced bioavailability of the compound secondary to its powdered form.

Adult↗
PubMedDate not supplied

Slow response induced in canine Purkinje fiber by contrast medium.

Cardiac toxicity of angiographic contrast medium has been documented at the cellular level by using the methods of micro-electrode electrophysiology. Canine Purkinje fibers exposed to contrast medium exhibit a "slow response." The increased automaticity and slowed conduction inherent in this "slow response" may cause the serious arrhythmias and other adverse effects recorded by electrocardiograms during coronary angiography. Hyperosmolarity plays only a minor role in the observed cellular toxicity. The unphysiologic concentrations of sodium, potassium, and calcium in the tested contrast medium were not responsible for the changes observed. Toxicity is probably an inherent chemical property of iodinated diatrizoate or meglumine ions.

Angiocardiography↗
PubMedDate not supplied

Differences in fatty acid composition of human milk in vegetarian and nonvegetarian women: long-term effect of diet.

The purpose of the current study was to determine whether there were differences in the fatty acid composition of milk from vegetarian mothers compared to nonvegetarian mothers and whether fatty acid composition was related to length of time on a vegetarian diet. Median time on a vegetarian diet was 81 months (range 36-132 months). Milk fat and fatty acids produced de novo in the mammary gland did not differ between diet groups. Milk from vegetarian women (n = 12) contained higher percentages of the precursors of arachidonic acid compared to nonvegetarian women (n = 7). Although there was no difference between diet group in the amount of arachidonic acid present (percent of total), a lower percentage was observed in women the longer they were on a vegetarian diet (r = -0.724, p = 0.008), with a corresponding higher percentage of the sum of precursors of arachidonic acid (r = 0.563, p = 0.056). The percentage of docosahexenoic acid was similar in the milk of vegetarian women compared to nonvegetarian women. The length of time on a vegetarian diet had no effect on these two fatty acids. In summary, differences in fatty acid content were apparent between the two dietary groups and changes with time on a vegetarian diet suggest that not only does current maternal diet affect fatty acid milk composition, but long-term dietary habits may as well.

Adult↗
PubMedDate not supplied

The effect of structured training on breast self-examination search behaviors as measured using biomedical instrumentation.

BACKGROUND: Although breast self-examination (BSE) has long been recommended by health care practitioners as a complement to mammography and clinical breast examination, only a small percentage of U.S. women report doing monthly BSE, and an even smaller number of women perform this procedure proficiently. OBJECTIVES: To measure the effect of a structured training protocol on improving two dimensions of BSE technique (depth of palpation and search time) in each of two search patterns (vertical strip and concentric circle) using biomedical instrumentation. METHODS: For this study, 41 young women participated in a structured training protocol for BSE instruction. The dependent variable was thoroughness of search, for which there were two measures: depth of palpation (displacement of the sensors) and duration of the examination. An instrumented breast model designed by the investigator provided quantitative measurements of examination behaviors and was used to test outcomes of the instruction. RESULTS: Multivariate analyses demonstrated an overall difference across examinations (F = 28.03; p = 0.0001). Univariate tests showed treatment effects for both dependent variables: depth of palpation and duration of examination. CONCLUSIONS: Individual training in BSE with guided practice improved two measures of thoroughness of search: depth of palpation and duration of search time. Biomedical instrumentation represented a novel approach to the collection of quantitative performance data.

Adult↗
PubMedDate not supplied

The generic strategy trap.

Management experts claim that for a company to thrive, it must concentrate on a single generic strategy--on one thing it does better than its rivals. But specialization also has its disadvantages. The author suggests that a broader, mixed approach may be preferable.

Canada↗
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A pilot phase 2 study of oregovomab murine monoclonal antibody to CA125 as an immunotherapeutic agent for recurrent ovarian cancer.

This prospective, open-label, pilot phase 2 study examined the clinical and immunologic effects of oregovomab (OvaRex) in heavily pretreated patients with recurrent ovarian cancer (OC). Thirteen women were administered intravenous oregovomab (2 mg) at weeks 0, 2, 4, 8, and 12, followed by quarterly doses for up to 2 years or disease progression. Concomitant chemotherapy was not permitted. Eligibility criteria included recurrence after one or more platinum-based chemotherapy regimens, CA125 >35 U/mL, evaluable or measurable disease. Tumor burden was evaluated by physical or radiologic methods pretreatment, weeks 12, 24, and every 24 weeks thereafter. Immune responses, including antibodies and T cells to oregovomab and CA125, were demonstrated in over half the patients. Stabilization of disease and survival >2 years was observed in 3 of 13 patients and coincided with robust immune responses. Shrinkage of marker lesions was not observed; however, four patients showed decreases in CA125 levels. Treatment was well tolerated without serious adverse events or discontinuations due to therapy. This pilot study supports immunologic activity and safety of oregovomab in recurrent OC. Further study of this agent in the consolidation and adjuvant setting is ongoing to establish its clinical utility.

Adenocarcinoma↗
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Total quality improvement: an example of an effective team.

Total quality improvement (TQI) advocates that all staff members in an organization develop their own ideas on job improvement about their own specific jobs. This process helps to improve staff performance and to build continually on those improvements. This article will describe how the TQI process was used successfully by quality management staff members at a federal medical center to investigate a problem with linen.

Arizona↗
PubMedDate not supplied

A prototype beam delivery system for the proton medical accelerator at Loma Linda.

A variable energy proton accelerator was commissioned at Fermi National Accelerator Laboratory for use in cancer treatment at the Loma Linda University Medical Center. The advantages of precise dose localization by proton therapy, while sparing nearby healthy tissue, are well documented [R. R. Wilson, Radiology 47, 487 (1946); M. Wagner, Med. Phys. 9, 749 (1982); M. Goitein and F. Chen, Med. Phys. 10, 831 (1983)]. One of the components of the proton therapy facility is a beam delivery system capable of delivering precise dose distributions to the target volume in the patient. To this end, a prototype beam delivery system was tested during the accelerator's commissioning period. The beam delivery system consisted of a beam spreading device to produce a large, uniform field, a range modulator to generate a spread out Bragg peak (SOBP), and various beam detectors to measure intensity, beam centering, and dose distributions. The beam delivery system provided a uniform proton dose distribution in a cylindrical volume of 20-cm-diam area and 9-cm depth. The dose variations throughout the target volume were found to be less than +/- 5%. Modifications in the range modulator should reduce this considerably. The central axis dose rate in the region of the SOBP was found to be 0.4 cGy/spill with an incident beam intensity of 6.7 x 10(9) protons/spill. With an accelerator repetition rate of 30 spills/min and expected intensity of 2.5 x 10(10) protons/spill for patient treatment, this system can provide 50 cGy/min for a 20-cm-diam field and 9-cm range modulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Equipment Design↗
PubMedDate not supplied

A beam intensity monitor for the Loma Linda cancer therapy proton accelerator.

A beam intensity monitor was tested in a 230-MeV proton beam at the Loma Linda Proton Therapy Accelerator during its commissioning at Fermi National Accelerator Laboratory. The intensity monitor was designed to regulate the beam intensity extracted from the proton synchrotron. The proton beam is tunable between 70 and 250 MeV with an adjustable intensity between 10(10) and 10(11) protons per spill. A beam spill is typically 1 s long with a 2-s repetition period. The intensity monitor must be radiation hard, expose minimum mass to the beam, and measure intensity to 1% in 1-ms time intervals. To this end, a 5-cm-thick xenon gas scintillator optically coupled to a photomultiplier tube (PMT) was tested to measure its response to the proton beam. The gas cell was operated at 1.2 atm of pressure and has 12.7-microns-thick titanium entrance and exit foils. The total mass exposed to the beam is 0.14 g/cm2 and is dominated by the titanium windows. This mass corresponds to a range attenuation equal to 1.4 mm of water. The energy lost to the xenon gas is about 70 keV per proton. Each passing proton will produce approximately 2000 photons. With a detection efficiency on the order of 0.05% for this UV light, one would anticipate over 10(10) photoelectrons per second. In a 1-ms time bin there will be approximately 10(7) photoelectrons. This yields a resolution limited by systematics. For unregulated 0.4-s proton spills, we observe a response bandwidth in excess of 10(4) Hz. While signal-to-noise and linearity were not easily measured, we estimate as few as 10(3) protons can be observed suggesting a dynamic range in excess of 10(5) is available.

Humans↗
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Effect of Fluosol on oxygen availability, regional cerebral blood flow, and infarct size in a model of temporary focal cerebral ischemia.

Twenty-four cats had an intravenous infusion of either Fluosol or saline and then were subjected to 2 hours of middle cerebral artery occlusion. All the animals infused with Fluosol and one-half the animals infused with saline were ventilated with 100% O2. Tissue oxygen availability and regional cerebral blood flow were measured by platinum electrodes using direct voltage recordings for oxygen measurements and hydrogen clearance curves for measurements of cerebral blood flow. With 100% oxygenation tissue oxygen availability increased significantly in the Fluosol treated animals, however, during the time of ischemia oxygen availability decreased below baseline values to about an equal level whether the animals were treated with Fluosol or saline. Regional cerebral blood flow fell to a similar value in all groups during the time of occlusion. One hour after reperfusion blood flow increased considerably above baseline values in all groups and oxygen availability also increased in all groups but particularly in the Fluosol treated animals. Overall mortality and the size of infarction 1 week after the ischemic insult were not significantly different in the three groups. Mortality was directly related to the size of the infarct which, in turn, was related to the degree of ischemia during the time of occlusion.

Animals↗
PubMedDate not supplied

Management of the dying patient with head and neck cancer.

The management of a patient with head and neck cancer and the psychological effect on the patient and his or her family is a subject frequently avoided in scientific assemblies. Yet, it is a fact that many physicians silently look for better understanding in themselves to be better able to understand the possible responses in patients and their respective families so that confrontations between all parties may be more comfortable for all concerned. I have tried to verbalize in this presentation such processes that affect the patient, his family and the physician himself so that we, as physicians, may better manage those unpleasant situations associated with the care of a patient with incurable head and neck cancer.

Communication↗
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Role of chemotherapy in the multidisciplinary approach to advanced head and neck cancer: potentials and problems.

Chemotherapy as initial treatment for advanced squamous carcinoma has received much recent attention. Despite sparse experimental data supporting its usefulness, such chemotherapy is now used for a variety of advanced malignancies. This experience is conceptually reviewed, with special emphasis on squamous carcinoma of the head and neck. Factors which influence treatment results, such as drug dosage, radiation treatment planning, and surgical resection, will require careful analysis in the evolution of the multidisciplinary approach to advanced head and neck cancer.

Antineoplastic Agents↗
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Chemical modulation of the hypoxic fraction in the treatment of head and neck cancer.

Treatment of large squamous carcinomas of the head and neck often requires intensive of multidisciplinary treatment. Despite such aggressive measures, local recurrence is common. Possible reasons for such local failure are numerous. Hypoxic but viable tumor cells may be one means of resistance to radiotherapy and chemotherapy. If surgical removal cannot eliminate these cells, tumor regrowth may occur. Modulation of the hypoxic fraction is one means of potentially altering resistance to radiotherapy. Misonidazole, a radiosensitizer, has been thought to increase free radical formation in hypoxic cells in vitro thus increasing the radiosensitivity. This observation is discussed with reference to advanced head and neck cancer.

Animals↗