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Biomedical subjects

M K Miller

Publications and source records attributed to M K Miller.

At least 19 recordsLinked to original sources
PubMed2001

Analysis conditions of an industrial Al-Mg-Si alloy by conventional and 3D atom probes.

Industrial 6016 Al-Mg-Si(Cu) alloys are presently regarded as attractive candidates for heat treatable sheet materials. Their mechanical properties can be adjusted for a given application by age hardening of the alloys. The resulting microstructural evolution takes place at the nanometer scale, making the atom probe a well suited instrument to study it. Accuracy of atom probe analysis of these aluminium alloys is a key point for the understanding of the fine scale microstructural evolution. It is known to be strongly dependent on the analysis conditions (such as specimen temperature and pulse fraction) which have been widely studied for ID atom probes. The development of the 3D instruments, as well as the increase of the evaporation pulse repetition rate have led to different analysis conditions, in particular evaporation and detection rates. The influence of various experimental parameters on the accuracy of atom probe data, in particular with regard to hydride formation sensitivity, has been reinvestigated. It is shown that hydrogen contamination is strongly dependent on the electric field at the specimen surface, and that high evaporation rates are beneficial. Conversely, detection rate must be limited to smaller than 0.02 atoms/pulse in order to prevent drastic pile-up effect.

Journal Article↗
PubMed2001

Fabrication of specimens of metamorphic magnetite crystals for field ion microscopy and atom probe microanalysis.

Field ion specimens have been successfully fabricated from samples of metamorphic magnetite crystals (Fe3O4) extracted from a polymetamorphosed, granulite-facies marble with the use of a focused ion beam. These magnetite crystals contain nanometer-scale, disk-shaped inclusions making this magnetite particularly attractive for investigating the capabilities of atom probe field ion microscopy (APFIM) for geological materials. Field ion microscope images of these magnetite crystals were obtained in which the observed size and morphology of the precipitates agree with previous results. Samples were analyzed in the energy compensated optical position-sensitive atom probe. Mass spectra were obtained in which peaks for singly ionized 16O, 56Fe and 56FeO and doubly ionized 54Fe, 56Fe and 57Fe peaks were fully resolved. Manganese and aluminum were observed in a limited analysis of a precipitate in an energy compensated position sensitive atom probe.

Journal Article↗
PubMed2001

Immunohistochemical analysis of prostate specific antigen in breast cancer.

The presence of immunoreactive prostate-specific antigen (IR-PSA) has been reported in breast cancers and has been suggested to confer a positive prognosis. However, recent large, well-controlled studies have found no significant prognostic value when IR-PSA positivity is examined as an independent variable, even when ultrasensitive immunofluorometric techniques are utilized. The present study, using indirect immunohistochemistry on 75 formalin-fixed, paraffin-embedded breast cancers shows PSA immunoreactivity in only seven of 75 cases (9%), suggesting that PSA positivity in breast carcinoma is not useful as a prognostic or tumor marker with hospital-based methods.

Adult↗
PubMed2001

Concurrent chronic lymphocytic leukemia cutis and acute myelogenous leukemia cutis in a patient with untreated CLL.

Patients who have chronic lymphocytic leukemia (CLL) are known to have a high frequency of second malignant neoplasms. However, acute myelogenous leukemia (AML) occurring concurrent with or after a diagnosis of CLL is extremely rare. In this article we report a case of AML developing in a 55-year-old male with a 6-year history of untreated CLL. The diagnosis was facilitated by touch preparation of a skin punch biopsy specimen. The patient presented with a two-week history of fever, weakness, anasarca, and a skin rash. Physical examination revealed pink to skin-colored firm papules, which coalesced into indurated plaques on his trunk, upper extremities, and face. The lesions, in combination with generalized edema, produced a leonine facies. Touch prep of the biopsy showed medium to large blasts, large monocytoid cells, and numerous small mature lymphocytes, providing the preliminary diagnosis of a second, previously undiagnosed myelomonocytic malignancy in this patient. The initial diagnosis was subsequently confirmed by histologic, cytochemical, immunohistochemical and flow cytometry studies. This is the first reported case of CLL with concurrent AML in which rapid touch prep of a skin punch biopsy facilitated diagnosis.

Humans↗
PubMed2001

Do learning style and learning environment affect learning outcome?

This study compared learning outcomes of students with different learning styles, as identified by the Kolb Learning Style Inventory indicators, in a traditional in-class environment with those taking the same course via distance education. The above-average scores were evenly distributed, 47% of the in-class group and 43% of the distance group. For three of the four learning styles, there was no relationship to learning outcome or environment. The Diverger group did show a relationship with above-average scores in the distance group (83%). The findings support that the classroom or distance environment did not influence learning outcome. Learning style did not appear to affect learning outcome in either group, except that the Diverger learning style may have a positive relationship to learning in the distance environment.

Adult↗
PubMed2001

Analysis of anesthesia practice and needs in Louisiana.

The Louisiana State University Health Sciences Center Department of Anesthesiology performed an analysis of anesthesia practice and needs within the State of Louisiana. The State of Louisiana currently has approximately 300 practicing anesthesiologists (physicians), 700 certified registered nurse anesthetists (CRNAs), and does not currently utilize anesthesiologist assistants (AAs). Approximately 500,000 anesthesia encounters occur annually in Louisiana. Although there is a recognized critical shortage of anesthesiologists nationally, this document will focus mainly on the issue of mid-level providers of anesthesia services. The overwhelming majority of surgical and obstetric procedures is performed using the anesthesia care team approach both nationally and in the State of Louisiana. Within the anesthesia care team model, the practice of certified registered nurse anesthetists and anesthesiologist assistants are interchangeable, and both would meet the need for mid-level anesthesia providers in the State of Louisiana.

Anesthesiology↗
PubMed2000

Clinical features and management of Hadronyche envenomation in man.

Using case reports and a review of the literature, the clinical features of envenomation by the genus of Australian funnel web spiders known as Hadronyche, are characterised. Five cases are reported here, including the first life-threatening envenomation by Hadronyche species 14 (the Port Macquarie funnel web). Two severe envenomations by Hadronyche cerberea (the Southern Tree funnel web) and one each by Hadronyche formidabilis (the Northern Tree funnel web) and Hadronyche infensa (the Darling Downs funnel web) are also described. The clinical experience of the authors' provided the five cases described in detail one of which has previously been reported in brief. Eight cases of Hadronyche envenomation from the literature (Medline 1966-1998 and Embase 1980-1998) were analysed in order to draw comparisons between this syndrome and the well described envenomation syndrome of Atrax robustus (the Sydney funnel web). Reports of funnel web spider antivenom use to Commonwealth Serum Laboratories (CSL) between 1995 and June 1998 were also examined. The biology of these dangerous spiders, their geographic distribution, venom characteristics and management issues are addressed. It is concluded that bites from at least six Hadronyche species have produced a life-threatening envenomation syndrome clinically indistinguishable from that of Atrax robustus. Atrax robustus derived antivenom is effective although antivenom requirements may be greater than for Atrax envenomation. Antivenom supplies are limited and sufficient stocks to treat a severe envenomation are unlikely to be found in any one institution. Pressure-immobilisation first aid is effective in delaying onset of envenomation, may enhance local inactivation of venom and early removal can result in rapid clinical deterioration.

Adult↗
PubMed2000

The effect of knee angle on the external validity of isometric measures of lower body neuromuscular function.

The aim of this study was to evaluate the effect of varying knee angle (120 degrees and 90 degrees) on the external validity of an isometric leg press test with reference to vertical jump performance. Isometric peak force (PF120 and PF90), rate of force development (RFD120 and RFD90), and maximum height reached with a squat jump and counter-movement jump were measured in 14 males. Although RFD120 was significantly correlated with squat jump and counter-movement jump performance (r = 0.71 and 0.69), and the correlations with PF120 approached statistical significance (r = 0.53 and 0.50), neither PF90 nor RFD90 was significantly related to vertical jump performance. Furthermore, although both RFD120 and PF120 were significantly different between the best five and the worst five jumpers, RFD90 and PF90 did not differentiate between individuals' vertical jump performance. We conclude that the choice of joint angle affects the external validity of isometric strength testing. Based on our results, we recommend accurate control of biomechanical specificity and assessment at different angles to find the position at which isometric strength testing is most comfortable.

Adult↗
PubMed1999

Translational control by an upstream open reading frame in the HER-2/neu transcript.

Overexpression of the HER-2 (neu, erbB-2) receptor results in cellular transformation and is associated with a variety of human cancers. Multiple mechanisms, including gene amplification and transcriptional, post-transcriptional, and translational controls contribute to the regulation of HER-2 expression. One of the components of these regulatory mechanisms is a short upstream open reading frame (uORF) in the HER-2 mRNA that represses downstream translation in a variety of cell types. Here we explore the mechanism by which this uORF exerts its inhibitory effect. As judged by comparisons of protein and mRNA abundance and by polysomal distribution analyses, the uORF represses translation of the HER-2 cistron or of a heterologous reporter gene. Despite its conservation among mammalian species, the peptide sequence of the uORF is not required for this inhibitory effect. Rather, the majority of ribosomes that load on the HER-2 mRNA most likely translate the uORF and are then unable to reinitiate at the downstream AUG codon, in part due to the short intercistronic spacing. A minority of ribosomes gain access to the HER-2 initiation codon either by leaky scanning past the upstream AUG codon or by reinitiating after having translated the uORF despite the short intercistronic region. These results suggest that the HER-2 uORF controls synthesis of this oncoprotein by limiting ribosomal access to downstream initiation sites.

Animals↗
PubMed1999

Cell type-dependent and -independent control of HER-2/neu translation.

Overexpression of the HER-2 oncogene occurs in a variety of human tumors, including 25-30% of breast carcinomas, and has been associated with an adverse prognosis. Amplification of the HER-2 gene is frequently detected in tumors, but by itself may not fully account for HER-2 overexpression since transcriptional and post-transcriptional mechanisms also regulate HER-2 protein synthesis. Our studies reveal that the efficiency of HER-2 translation differs between primary and transformed cells. In primary human fibroblasts and human mammary epithelial cells, the HER-2 mRNA is associated with monosome and small polysome fractions. In contrast, in BT474 and MCF-7 human breast cancer cell lines and in COS-7 cells the mRNA co-sedimented with larger polysomes, indicating that it is more efficiently translated in these transformed cells. Northern analysis revealed no detectable mRNA size difference, and nuclease S1 protection and sequence analyses showed no differences between the HER-2 transcript leader in primary cells compared to transformed human cells. The transcript leader in all cell types contains a short upstream open reading frame that is also conserved in other mammalian species. Transient transfection assays revealed that the HER-2 transcript leader repressed downstream translation approximately five-fold in both primary and transformed cells and mutation of the upstream initiation codon alleviated most of the inhibitory effect. These results indicate that HER2 expression is translationally controlled both by a short upstream open reading frame that represses HER-2 translation in a cell type-independent manner, and by a distinct cell type-dependent mechanism that increases translational efficiency of HER-2 in transformed cells.

Animals↗
PubMed1999

Tooth-specific and person-level predictors of 24-month tooth loss among older adults.

OBJECTIVES: To describe: (1) the 24-month incidence of tooth loss in a diverse sample of dentate adults; and (2) the clinical, attitudinal, behavioral, and sociodemographic correlates of tooth loss incidence. METHODS: The Florida Dental Care Study is a prospective longitudinal cohort study of persons who at baseline had at least one tooth, were 45 years or older, and who resided in north Florida. An in-person interview and clinical examination were conducted at baseline and 24-months after baseline, with 6-monthly telephone interviews between those times. A two-level hierarchical generalized linear regression (logit model) was used to quantify tooth-specific and person-level factors simultaneously. RESULTS: Of the 739 persons who attended for a 24-month examination, 24% lost one or more teeth during follow-up. Tooth loss was more common in persons with dental disease at baseline, incident dental signs or symptoms, those with negative attitudes toward dental care and dental health, those with limited financial resources, older adults, blacks, females, and problem-oriented users of dental care (as distinct from regular attenders). Although disease presence at baseline was a major factor associated with incident tooth loss, most diseased teeth were in fact still present 24 months after baseline. CONCLUSIONS: Other than periodontal attachment loss, severe tooth mobility, and dental caries, no single factor was a dominant predictor of tooth loss; instead, numerous factors made statistically significant but small contributions to variation in tooth loss. Tooth loss apparently is the result of complex interactions among dental disease, incident dental signs and symptoms, tendency to use dental care in response to specific dental problems, dental attitudes, and ability to afford non-extraction treatment alternatives.

Aged↗
PubMed1999

The role of medical problems and behavioral risks in explaining patterns of prenatal care use among high-risk women.

OBJECTIVE: To examine the associations between maternal medical conditions and behavioral risks and the patterns of prenatal care use among high-risk women. DATA SOURCE/STUDY DESIGN: Data on over 25,000 high-risk deliveries to African American and white women using multinomial logistic regression to predict the odds of adequate-plus care relative to three other categories of care. DATA COLLECTION/EXTRACTION METHODS: Data were extracted from records maintained by the University of Florida/Shands Hospital maternity clinic on all deliveries between 1987 and 1994; records for white and for African American women were subset to examine racial differences in medical conditions, health behaviors, and patterns of prenatal care use. PRINCIPAL FINDINGS: Net of sociodemographic and fertility-related characteristics, African American and white women with late antepartum conditions and hypertension problems had significantly higher odds of receiving adequate-plus care, as well as no care or inadequate care, relative to adequate care. White women with gynecological disease and medical/surgical problems were significantly less likely to receive no care or inadequate care, as were African American women with gynecological disease. CONCLUSIONS: Maternal medical conditions explain much but not all of the adequate-plus prenatal care use. More than 13 percent of African American women and 20 percent of white women with no reported medical problems or behavioral risks used adequate-plus care. Additional research is needed to understand this excess use and its possibilities in mediating birth outcomes.

Adolescent↗
PubMed1998

Norplant selection and satisfaction among low-income women.

OBJECTIVES: This study examined correlates of Norplant selection and satisfaction among low-income women. METHODS: Interviews were completed in family planning clinics in 4 Florida counties with 1152 Norplant users and 1268 nonusers, with follow-up interviews with a subsample up to 1 year later. Logistic regression models estimated the associations of socio-demographic and medical characteristics with Norplant selection and method satisfaction. RESULTS: Odds ratios for Norplant selection were significantly greater among women who planned to have children in 5 or more years, those who were "offered" Norplant, those who lived in Palm Beach County, those who were using drugs, and those who were Medicaid clients. Women younger than 17 and those who learned about Norplant from a friend were twice as likely as others to select Norplant. Ninety-two percent of Norplant users were satisfied with the method; women with side effects and those who felt pressure to select a method were significantly less likely than others to be satisfied. CONCLUSIONS: Norplant provides an acceptable and satisfying method of birth control for many low-income women. Proper counseling about all methods of birth control and about Norplant's side effects remains critical to the appropriate delivery of this method.

Adolescent↗
PubMed1997

The role of race and residence in determining stage at diagnosis of breast cancer.

Breast cancer kills more than 46,000 women each year. Previous research has found that minorities and those who reside in geographically remote settings are particularly vulnerable. However, virtually no research has been done on the potential "double jeopardy" faced by rural minority women. This research examines (1) the extent to which racial and residential differences contribute to differences in stage at diagnosis; (2) the existence of an interaction between race and residence, which may place black rural women at greater risk; and (3) the influence of both individual and structural characteristics on racial and residential differences. The findings indicate that rural black women are diagnosed with breast cancer much later than are black urban women or whites of either residence. A number of individual and structural variables were influential in predicting stage at diagnosis, yet none of these accounted entirely for racial differences.

Adult↗