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Biomedical subjects

T R Miller

Publications and source records attributed to T R Miller.

At least 73 records · Page 4Linked to original sources
PubMed1997

Relationship between passive tissue strain and collagen uncoiling during healing of infarcted myocardium.

OBJECTIVE: The structure of the collagen scar during healing of a myocardial infarction is a determinant of the function of the remodeled tissue. We hypothesize that the passive deformations of both scar and normal tissue are related to the underlying collagen uncoiling as the tissue stretches, and that the unloaded tortuosity of the collagen may be a determinant of tissue stiffness at low ventricular pressure. Hence collagen uncoiling and tissue strain were measured during passive loading in normal tissue, and in healing infarct tissue. METHODS: Left ventricles of rats were infarcted by ligation of the left anterior descending artery for 2 weeks. Surface strains were measured during passive inflation in the scar region in one set of excised hearts, and other arrested hearts were fixed at different ventricular pressures, after which collagen tortuosity was measured in the infarcted and normal tissue. RESULTS: Passive loading strains were smaller in the scar in both the fiber and cross-fiber directions. Tortuosity decreased with load in normal and infarcted tissue, with fibrils tending to straighten more in the scar tissue at higher pressures (1.056 +/- 0.009 vs. 1.024 +/- 0.009 at P = 20 mmHg) with similar tortuosities at zero pressure (1.110 +/- 0.012 vs. 1.098 +/- 0.019). The decrease in tortuosity with strain was greater for the infarcted tissue. CONCLUSIONS: The greater stiffness of infarcted tissue at low pressure is not due to 'straightened' collagen fibers, and there may be a different three-dimensional structure of infarct vs. normal coiled collagen fibers which can affect the material properties of these tissues.

Animals↗
PubMed1997

Costs of poisoning in the United States and savings from poison control centers: a benefit-cost analysis.

Data on incidence, medical spending, and payment sources for poisoning were taken from the 1987 National Medical Expenditure Survey, 1991 US Vital Statistics, the 1992 National Hospital Discharge Survey, and 1992 poison control center surveillance data. Benefits, measured as percentage reductions in medical spending attributable to use of poison control centers, were calculated from analyses of published and unpublished studies of jurisdictions in which services became unavailable. Medical spending (payments) for poisoning treatment totaled $3 billion in 1992. Spending averaged $925 per case. Poison control center services were available for 86% of poisonings As used, they reduced the number of patients who were medically treated but not hospitalized for poisoning by an estimated 350,000 (24%) and the number of hospitalizations by 40,000 (12%) in 1992. The average public call to a poison control center for aid prevented $175 in other medical spending. Poison control centers offer a large return on investment. Despite their proven benefits, many poison control centers are unstably funded and financially strapped, in part because the federal government pays far less than its fair share of center costs.

Cost-Benefit Analysis↗
PubMed1997

Ranking occupations based upon the costs of job-related injuries and diseases.

In this article, we construct a ranking of occupations based upon the costs of job-related injuries and illnesses. Data are drawn from large nationally representative Bureau of Labor (BLS) data sets. Information is obtained on occupation and workers' compensation (WC) category of the injury or illness, which are then matched to information on costs. Six broad occupations and 413 specific (3-digit) occupations are ranked by total costs. Six broad and 223 specific occupations are ranked by costs per worker (average cost). Operators and laborers is the broad occupation category that contributes both the highest total and average cost. Specific occupations that contributed the most to total costs include heavy truck drivers, non-construction laborers, machine operators (not specified), occupations not classified, janitors, nursing orderlies, construction laborers, assemblers, retail sales workers (not elsewhere specified), miscellaneous machine operators, and carpenters. Occupations high on the average cost list include not-specified mechanics, general and construction laborers, press apprentices, welders, stone cutters, and warehouse workers. Although the BLS data are limited, they can be used to provide a preliminary look at which occupations are contributing the most and the least to the overall economic costs of occupational injuries and illnesses.

Accidents, Occupational↗
PubMed1997

An optimal rotator for iterative reconstruction.

For implementations of iterative reconstruction algorithms that rotate the image matrix, the characteristics of the rotator may affect the reconstruction quality. Desirable qualities for the rotator include: 1) preservation of global and local image counts; 2) accurate count positioning; 3) a uniform and predictable amount of blurring due to the rotation. A new rotation method for iterative reconstruction is proposed which employs. Gaussian interpolation. This method was compared to standard rotation techniques and is shown to be superior to standard techniques when measured by these qualities. The computational cost was demonstrated to be only slightly more than bilinear interpolation.

Algorithms↗
PubMed1997

Pathological tumor-node-metastasis (pTNM) staging for papillary and follicular thyroid carcinomas: a retrospective analysis of 700 patients.

The TNM classification (tumor-node-metastasis) was adopted by the American Joint Committee on Cancer and the International Union against Cancer a decade ago to avoid heterogeneity of prognostic classification schemes used for differentiated thyroid cancers. To date, however, clinical data based on this classification are lacking. We retrospectively evaluate the prognosis of 700 patients (208 men and 492 women) with papillary (89%) and follicular (11%) thyroid cancers according to the pathological TNM (pTNM) staging system, treated over a 25-yr period (1970-1995). Patients who received primary treatment at our center constituted 87.4% of the cases; the majority underwent total thyroidectomy, followed by 131I ablative therapy in high risk groups, as standard treatment. Clinical and follow-up data were obtained from the medical records and our cancer registry. Disease-free and cancer-specific survival data were analyzed by Kaplan-Meier product limit estimates and Cox proportional hazard models. Patient distribution by the pTNM system were: stage I, 516 patients; stage II, 57 patients; stage III, 104 patients; and stage IV, 23 patients. Over a mean +/- SE follow-up of 11.3 +/- 0.3 yr, the overall cancer recurrence and mortality rates were 20.5% and 8.4%, respectively. However, the respective cancer recurrence and mortality rates were distinctly different in the various pTNM stages: 15.4% and 1.7% in stage I, 22% and 15.8% in stage II, 46.4% and 30% in stage III, and 66.7% and 60.9% in stage IV tumors. Using actuarial survival plots, a clear separation in both disease-free survival and cancer-specific survival was noted among all the stages (P < 0.0001). Risk factors analyses showed a significant association between all the prognostic variables used in TNM staging (age, tumor size, extent of primary tumor, and presence of nodal or distant metastases) and the observed end points of recurrence or death from thyroid cancer. After correcting for TNM stages, the risk of cancer recurrence was halved in female compared to male patients, whereas this was 1.7-fold higher in multifocal than unifocal tumors. Conversely, cancer mortality was 3.4-fold higher in follicular than papillary thyroid cancer. In the analysis of effect of primary treatment among 492 patients with tumor more advanced than the T1N0M0 category, patients who underwent less extensive surgery (lobectomy or subtotal thyroidectomy) had a 2.5-fold risk of cancer recurrence (P < 0.0001) and a 2.2-fold risk of death (P < 0.01) compared to those who underwent total or near-total thyroidectomy. Patients not treated with 131I ablation had a 2.1-fold greater risk of cancer recurrence (P < 0.0001) than those given 131I ablation, although no difference was noted in deaths from thyroid cancer. Based on our data, the pTNM classification is useful in distinguishing patients with different prognostic outcomes. However, the small patient numbers in pTNM stages other than stages I precludes us from evaluating its usefulness as a guide for therapy. Until prospective data could be accrued from controlled treatment trials, we support the standard practice of total thyroidectomy followed by 131I ablative therapy (if focal iodide uptake was noted) in patients with papillary thyroid cancer more advanced than the T1N0M0 category or of multicentric nature and in the majority of patients with follicular thyroid cancer.

Adenocarcinoma, Follicular↗
PubMed1997

Microglandular adenocarcinoma of the endometrium: a form of mucinous adenocarcinoma that may be confused with microglandular hyperplasia of the cervix.

Microglandular adenocarcinoma of the endometrium may cause diagnostic problems because of its bland cytologic appearance and its histologic similarity to benign microglandular hyperplasia of the cervix. We present two cases of microglandular adenocarcinoma and discuss the clinical, pathologic, and immunohistochemical findings. Both patients were postmenopausal women, one of whom was taking exogenous hormones. Endometrial biopsy specimens contained polypoid tissue fragments, within which were microcystic spaces lined by flattened, cuboidal, or columnar cells. Solid nests or sheets of tumor cells surrounded glands in some tissue fragments. The nuclei were uniform and bland, and mitotic figures, although readily identifiable, were infrequent (1 per 10 high-power fields). A majority of tumor cells contained intracytoplasmic mucin. Numerous neutrophils were present in gland lumens and tissues. Immunohistochemical stains for carcinoembryonic antigen and TAG72 (B72.3) revealed focal moderate to intense apical and cytoplasmic staining; immunostains for p53 protein were negative. One carcinoma was confined to the endometrium, whereas the other invaded into the inner one-third of the myometrium. Both patients were well after a limited follow-up of 1 year. Microglandular adenocarcinoma is a distinctive variant of endometrial carcinoma that is most likely a form of mucinous adenocarcinoma.

Adenocarcinoma, Mucinous↗
PubMed1997

Familial papillary thyroid cancer: a case report.

Familial occurrence of medullary thyroid cancer is well known in families as an isolated malignancy or in association with multiple endocrine neoplasia syndrome type II. Conversely, papillary thyroid cancer almost always presents sporadically except for reports of familial clustering in individuals with radiation exposure, inherited syndromes of colonic polyposis or multiple harmatomas, and rarely in monozygotic twins. We report a case of papillary thyroid cancer diagnosed incidentally in a 53-year-old woman who underwent surgery for excision of an adenomatous nodule. It was noted that her mother suffered from a similar thyroid malignancy some 33 years ago, and several of her maternal relatives had either Graves' disease or hypothyroidism. The possible existence of this familial entity and its likely genetic basis is discussed.

Biopsy, Needle↗
PubMed1996

Gender-related differences in left ventricular filling dynamics in older subjects after endurance exercise training.

The present study was designed to determine if gender affects the adaptive response to endurance exercise training of left ventricular filling dynamics in older individuals. Recently, it was shown that gender influences the cardiovascular responses to endurance exercise training in older subjects. Older men improve left ventricular systolic performance and increase maximal cardiac output in response to endurance exercise training, whereas older women do not. Twelve men (65 +/- 1 years old; mean +/- SE) and 10 women (64 +/- 1) were studied before and after 9 months of endurance exercise training. Maximal O2 uptake was determined during treadmill exercise. Left ventricular filling dynamics and ejection fraction (EF) at rest and during supine exercise were assessed by Tc-99m radionuclide ventriculography. When expressed relative to body weight, maximal O2 uptake (VO2 max) was increased by 24% (27.3 +/- 1.5 to 34.0 +/- 1.5 ml/kg/min; p < .01) in men and 27% (21.9 +/- 1.0 to 27.8 +/- 1.0 ml/kg/min; p < .01) in women in response to endurance exercise training. In men, the time-to-peak filling rate (TPFR) decreased (-19.8 +/- 6.7 ms; p < .05) during exercise at a comparable heart rate in response to training. In contrast, the change in TPFR in women (+2.7 +/- 6.0 ms) was small and insignificant. Peak filling rate (PFR) at rest and during exercise was similar before and after training in men and women. The change in left ventricular systolic reserve at a comparable heart rate from pre-to posttraining improved in men (delta EF 4 +/- 3%; p < .05), but not in women (-2 +/- 3%). The results indicate that the adaptive response of left ventricular filling dynamics to endurance exercise training is influenced by gender in older subjects. Older men show improvement in left ventricular filling dynamics, whereas older women do not.

Aged↗
PubMed1996

The AAPM/RSNA physics tutorial for residents. Clinical aspects of emission tomography.

Characteristics of single-photon emission computed tomography (SPECT) and positron emission tomography (PET) that have an important impact on clinical interpretation include increased image contrast compared with that in planar imaging and enhanced three-dimensional perception of spatial relationships. Negative factors of tomographic imaging compared with planar imaging include generally inferior spatial resolution and noise and the increased complexity of performing high-quality studies. Areas in which tomography is of value include assessment of recurrent tumors and seizure foci in the brain, myocardial perfusion imaging, and bone scintigraphy, especially in the spine. SPECT studies performed with labeled red blood cells are useful in the diagnosis of cavernous hemangiomas of the liver. SPECT is a valuable adjunct to planar imaging in assessment of infections and tumors. PET studies performed with fluorine-18 fluorodeoxyglucose are currently generating great interest in oncology. Areas of research that have potential clinical impact include development of improved tomographic reconstruction algorithms, correction for nonuniform attenuation of gamma rays, and multimodality image registration.

Animals↗
PubMed1996

Patterns in US medical expenditures and utilization for injury, 1987.

This article is based on data released in 1991/93 from the 1987. National Medical Expenditure Survey. Medical spending and utilization patterns are analyzed for 13 major categories of injury. Medical spending on injury in 1987 was $64.7 billion in 1993 dollars. Nonhospitalized medically treated injuries averaged $571 in medical spending per case, $181 per visit, and 3.2 visits per injury. The prevalence-based survey estimate of medical spending on injuries during 1987 is 10% lower than the incidence-based estimates of lifetime medical spending resulting from injuries in 1985.

Adolescent↗
PubMed1996

Structuring networks for maximum performance under managed care.

Healthcare providers interested in forming delivery networks to secure managed care contracts must decide how to structure their networks. Two basic structural models are available: the noncorporate model and the corporate model. The noncorporate model delivery network typically has a single governing body and management infrastructure to oversee only managed care contracting and related business. The corporate model delivery system has a unified governance management infrastructure that handles all of the network's business. While either structure can work, corporate model networks usually are better able to enforce provider behavior that is in the best interest of a network as a whole.

Community Networks↗
PubMed1996

Persistent activation of the dopamine D1 receptor contributes to prolonged receptor desensitization: studies with A-77636.

A-77636 is a dopamine (DA) D1 receptor-selective agonist that was previously shown to elicit beneficial responses in animal models of Parkinson's disease (PD) (Kebabian et al.: Eur. J. Pharmacol. 229: 203, 1992). However, A-77636 is of limited potential for PD therapy because it induces rapid tolerance in vivo. To understand the basis of rapid onset of tolerance to the compound, we conducted studies to compare the in vitro properties of A-77636 and A-81686; the latter is a structurally related D1 agonist that did not induce significant tolerance in vivo under similar experimental conditions. With SK-N-MC, a neuroblastoma cell line, as an in vitro model for the D1 receptor, significant differences in D1 receptor function were noted after pretreatment with the two compounds. Specifically, 1-hr pretreatment with A-77636 resulted in significant residual cAMP production, even after the drug solution was removed and the cells were washed. The residual cAMP activity was selectively inhibited by SCH 23390, a selective D1 antagonist. The residual cAMP activity declined with pretreatment time, and after 4-hr pretreatment, little residual cAMP production was observed. Cotreatment of SK-N-MC cells with SCH 23390 and A-77636 did not prevent residual cAMP production by A-77636. In contrast, A-81686 did not elicit residual cAMP production is SK-N-MC cells. Although A-77636 treated cells were devoid of agonist response 4 hr after drug removal, A-81686-treated cells exhibited significant cAMP response after drug removal. Preincubation of rat striatal membranes with A-77636 resulted in a large decrease in D1 receptor binding, despite repeated washings, whereas A-81686 pretreatment caused only a small reduction in D1 receptor binding. On the basis of the present data, we conclude that A-77636 dissociates slowly from the D1 receptor. The continued activation of the D1 receptor by A-77636 leads to inability of the receptor to recover its responsivity, which may explain its long duration of action and its ability to induce rapid behavioral tolerance in vivo.

Adamantane↗
PubMed1996

Fine-needle aspiration cytology of the thyroid.

Fine-needle aspiration of the thyroid, in experienced hands, is an extremely specific and sensitive tool. The authors provide an in-depth discussion of FNA for both benign and malignant lesions of the thyroid, and they offer a flow chart with diagnostic indicators that also clarifies areas of overlap between lesions.

Biopsy, Needle↗
PubMed1995

Costs associated with gunshot wounds in Canada in 1991.

OBJECTIVE: To estimate the costs (in 1993 dollars) associated with gunshot wounds in Canada in 1991. DESIGN: Cost analysis using separate estimates of gunshot incidence rates and costs per incident for victims who died, those who survived and were admitted to hospital and those who survived and were treated and released from emergency departments. Estimates were based on costs for medical care, mental health care, public services (i.e., police investigation), productivity losses, funeral expenses, and individual and family pain, suffering and lost quality of life. SETTING: Canada. OUTCOME MEASURES: Costs per case, costs by type of incident (e.g., assault, suicide or unintentional shooting) and costs per capita. RESULTS: The total estimated cost associated with gunshot wounds was $6.6 billion. Of this, approximately $63 million was spent on medical and mental health care and $10 million on public services. Productivity losses exceeded $1.5 billion. The remaining cost represented the value attributed to pain, suffering and lost quality of life. Suicides and attempted suicides accounted for the bulk of the costs ($4.7 billion); homicides and assaults were the next most costly ($1.1 billion). The cost per survivor admitted to hospital was approximately $300,000; this amount included just over $29,000 for medical and mental health care. CONCLUSION: Costs associated with gunshot wounds were $235 per capita in Canada in 1991, as compared with $595 in the United States in 1992. The differences in these costs may be due to differences in gun availability in the two countries. This suggests that increased gun control may reduce Canada's costs, especially those related to suicide.

Canada↗
PubMed1995

Patterns of childhood medical spending.

OBJECTIVE: To provide data on childhood medical spending. METHODS: This article is based on data released in 1991 through 1993 from the 1987 National Medical Expenditure Survey. The data were analyzed for 14 diagnostic categories. They excluded spending on nursing home and dental care. We inflated the National Medical Expenditure Survey expenditures to December 1993 dollars by means of annual medical spending per capita as a price index. RESULTS: Medical spending on children aged 0 to 21 years totaled $86 billion per year, 15% of all US medical care spending. The largest source of child medical spending was on live birth and pregnancy, at $19 billion, followed by injury, at $12 billion, and respiratory conditions, at $10 billion. Live birth and pregnancy were the largest contributor of hospital inpatient spending for children 0 to 21 years old. Injury accounted for more than half of the spending in emergency departments. One quarter of prescription spending was the result of respiratory conditions. CONCLUSIONS: Childhood medical spending for the three largest categories can be reduced through proved preventive measures. These analyses also show that prevention priorities differ by age group.

Adolescent↗
PubMed1995

The effect of regional trauma care systems on costs.

OBJECTIVE: To assess cost savings from regional trauma care systems. DESIGN: Multivariate regression analysis is used to isolate the effects of regional trauma care systems on medical costs while controlling for personal and injury characteristics and other factors likely to influence medical costs. Percentage reductions in costs are translated into dollar cost savings with corrections for excluded costs and losses from premature death. SETTING: Injuries to workers filing workers' compensation lost workday claims. PARTICIPANTS: Randomly sampled workers' compensation claims from 17 states filed between 1979 and 1988 (N = 217,000). MAIN OUTCOME MEASURE: Medical payments per episode of four injury groups: lower-extremity fractures and dislocations, upper-extremity fractures and dislocations, other upper-extremity injuries, and back strains and sprains. We distinguish hospitalized from nonhospitalized claims. RESULTS: Statistical analyses reveal that states with trauma care systems have 15.5% lower costs per hospitalized injury episode. Savings average $1025 per case in 1988 dollars. Costs per episode for disabling nonhospitalized injury are 10% lower in states with trauma care systems, with savings averaging $75 per case. The largest savings are for back injuries. CONCLUSIONS: Extending trauma care systems nationwide could lower annual medical care payments by $3.2 billion. Including productivity losses due to premature death, the savings could total $10.3 billion, 5.9% of national injury costs.

Arm Injuries↗