Modeling the interference between shear and longitudinal waves under high intensity focused ultrasound propagation in bone.

Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) is a noninvasive thermal technique that enables rapid heating of a specific area in the human body. Its clinical relevance has been proven for the treatments of soft tissue tumors, like uterine fibroids, and for the treatments of solid tumors in bone. In MR-HIFU treatment, MR-thermometry is used to monitor the temperature evolution in soft tissue. However, this technique is currently unavailable for bone tissue. Computer models can play a key role in the accurate prediction and monitoring of temperature. Here, we present a computer ray tracing model that calculates the heat production density in the focal region. This model accounts for both the propagation of shear waves and the interference between longitudinal and shear waves. The model was first compared with a finite element approach which solves the Helmholtz equation in soft tissue and the frequency-domain wave equation in bone. To obtain the temperature evolution in the focal region, the heat equation was solved using the heat production density generated by the raytracer as a heat source. Then, we investigated the role of the interaction between shear and longitudinal waves in terms of dissipated power and temperature output. The results of our model were in agreement with the results obtained by solving the Helmholtz equation and the frequency-domain wave equation, both in soft tissue and bone. Our results suggest that it is imperative to include both shear waves and their interference with longitudinal waves in the model when simulating high intensity focused ultrasound propagation in solids. In fact, when modeling HIFU treatments, omitting the interference between shear and longitudinal waves leads to an over-estimation of the temperature increase in the tissues.

Modelling the temperature evolution of bone under high intensity focused ultrasound.

Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) has been clinically shown to be effective for palliative pain management in patients suffering from skeletal metastasis. The underlying mechanism is supposed to be periosteal denervation caused by ablative temperatures reached through ultrasound heating of the cortex. The challenge is exact temperature control during sonication as MR-based thermometry approaches for bone tissue are currently not available. Thus, in contrast to the MR-HIFU ablation of soft tissue, a thermometry feedback to the HIFU is lacking, and the treatment of bone metastasis is entirely based on temperature information acquired in the soft tissue adjacent to the bone surface. However, heating of the adjacent tissue depends on the exact sonication protocol and requires extensive modelling to estimate the actual temperature of the cortex. Here we develop a computational model to calculate the spatial temperature evolution in bone and the adjacent tissue during sonication. First, a ray-tracing technique is used to compute the heat production in each spatial point serving as a source term for the second part, where the actual temperature is calculated as a function of space and time by solving the Pennes bio-heat equation. Importantly, our model includes shear waves that arise at the bone interface as well as all geometrical considerations of transducer and bone geometry. The model was compared with a theoretical approach based on the far field approximation and an MR-HIFU experiment using a bone phantom. Furthermore, we investigated the contribution of shear waves to the heat production and resulting temperatures in bone. The temperature evolution predicted by our model was in accordance with the far field approximation and agreed well with the experimental data obtained in phantoms. Our model allows the simulation of the HIFU treatments of bone metastasis in patients and can be extended to a planning tool prior to MR-HIFU treatments.

Transcription of BPV-1 genes in transfected F9 cells.

In F9 cells transformed with bovine papillomavirus type 1 (BPV-1) sequences two different phenotypes can be recognized. One cell type shows the characteristics of the parental stem cell line, whereas the other comprises cells with spindle-like morphology that do not adhere to each other, similar to retinoic acid-treated F9 embryonal carcinoma cells. The phenotypically altered cells plate more efficiently than the stem cells, grow well in soft agar and show an extended lifespan in the differentiated stage. Both types of cells contain BPV-1 DNA sequences as episomes, but only the non-stem-like cells have RNA transcripts for the unspliced E5 reading frame as well as for the spliced E6/E4.

The promoter of the H1zero histone gene contains a DNA element bound by retinoic acid receptors.

Retinoic-acid mediated differentiation of F9 cells is accompanied by an increased transcription of the histone H1zero gene. This increase is an early response after addition of retinoic acid, suggesting a direct effect of the hormone on transcription of the gene. We show now that the promoter of histone H1zero contains a DNA element, localized 531 base-pairs upstream of the cap site, that is composed of a direct repeat of the sequence PuGGTCA separated by eight base-pairs. This element confers retinoic acid responsiveness to a heterologous thymidine kinase promoter in F9 and HeLa cells. Furthermore, the element forms retarded complexes not only with bacterially expressed retinoic acid receptors (RARs) and retinoid X receptors (RXRs), but also with endogenous F9 receptors. Our results suggest therefore that retinoic acid receptors can control the expression of a chromatin structural gene the expression of which is associated with a differentiated phenotype.

The F9-EC cell line as a model for the analysis of differentiation.

The teratocarcinoma stem cell line F9 has been widely used as a model for the analysis of molecular mechanisms associated with differentiation. This cell line has been considered to be nullipotent and able to differentiate into endodermal-like derivatives upon treatment with retinoic acid. Nevertheless, under definite culture conditions, F9 cells are able to differentiate into derivatives of all three germ layers. The F9 cells express characteristics of early mouse embryonal cells and possess all repression factors known to be present in cells of the early mouse embryogenesis. Induction of differentiation can be achieved not only by adding chemical agents to the culture medium but also by transfection of several oncogenic sequences. In somatic cell genetic experiments, immortalized, differentiated F9-like cells have been shown to express dominantly genes responsible for the appearance of the differentiated phenotype.

Colocalization of a large heterodimeric proteoglycan with basement membrane proteins in cultured cells.

A novel large heterodimeric dermatan sulfate proteoglycan with core proteins of 460 and 300 kDa, respectively, had been described as a secretory product of human fetal skin fibroblasts (Breuer et al., J. Biol. Chem. 266, 13224-13232 (1991)). Pulse-chase experiments showed a preferential association of the proteoglycan with the cell membrane. Immunogold labeling indicated its localization in fibrils on the cell surface as well as in fibrillar extensions from the cell body. Immunofluorescence studies yielded a fibrillar and punctate staining pattern which was also seen in cultured human and porcine endothelial cells. Dot-like structures were observed in transformed human keratinocytes. Various immunocytochemical double-labeling experiments indicated a remarkable colocalization of the proteoglycan with fibronectin, laminin, perlecan, and type IV collagen whereas only occasionally a colocalization with chondroitin-6-sulfate was found. No evidence for an enrichment of the proteoglycan in vinculin-containing structures was obtained. These results suggest that the proteoglycan is a widely distributed macromolecule which can associate with basement membrane components. Preliminary findings in rat cornea supported this conclusion.

Cloning and characterization of the mouse histone H1(0) promoter region.

From a mouse genomic DNA library we have isolated sequences containing the entire coding region for histone H1(0) mRNA, flanked by several kb at both the 3' and 5' ends. Deletions of the 5' upstream region ligated to the chloramphenicol acetyltransferase (CAT)-encoding gene as a reporter, have shown that a region from bp -400 to -600 is necessary and sufficient for efficient transcription. We have also shown that treatment of F9 teratocarcinoma cells with retinoic acid and cyclic AMP (which differentiates F9 cells to parietal endoderm) clearly increases CAT activity several times over the level found in untreated F9 cells. This increase was observed in transient, as well as in stably transfected cells. Analysis of the deletions in differentiating cells indicates that the element responsible for the observed increase in CAT activity, is contained within the first 700 bp upstream from the H1(0) mRNA cap site.

erbB-2 and myc oncoproteins in sera and tumors of breast cancer patients.

This study compares the prevalence of elevated serological levels of erbB-2 and myc proteins in 36 breast cancer patients and 25 healthy, ambulatory female controls. The controls were frequency matched to the cases by age and ethnicity. Oncoprotein levels were determined blind to the "case-control status" of the individual from whom the specimen was derived. Corresponding tissue levels were examined in tumors of the 13 cases from whom sufficient tissue was available. Serum oncoproteins were elevated as follows: erbB-2 in one control (4%) compared with nine cases (25%; PFisher's exact = 0.03); myc in no control (0%) compared with seven cases (19%; PFisher's exact = 0.02). Elevated serum levels of erbB-2 or myc oncoproteins were detected in four of the seven cases (57.1%) of in situ cancer without evidence of infiltration. In all cases with elevated serum oncoproteins where tumor tissue was available, the corresponding protein was elevated in the tumor. The three cases who had elevated preoperative serum oncoprotein levels and from whom it was possible to procure postoperative specimens had normal postoperative serum oncoprotein levels. We conclude that (a) erbB-2 and myc oncoproteins are elevated in a proportion of breast cancer patients, (b) the tumor seems to be the source of the serum elevation, and (c) these proteins may be useful as part of a panel of biomarkers of early malignant disease.

The relationship between apolipoprotein E, dementia, and vascular illness.

The purpose of this study was to concurrently assess the relationship of Apolipoprotein E (APOE) with both dementias and vascular illnesses in the very old. Nine hundred and fifty nine subjects (mean age 85 years) in a long-term care facility were genotyped and cognitively tested with the Mini Mental State Exam. All subjects were studied for the relationship of APOE with atherosclerotic heart disease, hypertension, or stroke without concomitant dementia. Four hundred fifty individuals met criteria for inclusion into one of the following groups: Alzheimer's disease (n = 318), vascular dementia (n = 49), or not demented controls (n = 83) and were investigated for the relationship between APOE and these diagnostic categories. APOE epsilon4 was not associated with atherosclerotic heart disease, hypertension, or stroke without concomitant dementia. The APOE epsilon3 allele was more common in men with atherosclerotic heart disease. In contrast, the APOE epsilon4 allele was more common in patients with Alzheimer's disease (22%) and vascular dementia (26%) than in not demented controls (7%). APOE epsilon4 is associated with dementias in the very old, whereas its relationship with either peripheral or central nervous system vascular disease without dementia is not as robust.

Expression of matrix metalloproteinase-2 in glial and neuronal tumor cell lines: inverse correlation with proliferation rate.

The expression of matrix metalloproteinases (MMPs) has been found to be positively correlated to the degree of malignancy in gliomas, indicating that poorly differentiated brain tumor cells produce more MMPs than differentiated ones. We determined the production of active MMP-2 in five glial (U138MG, U373MG, A172, C6, GOS-3), two neuronal (SK-N-SH, SK-N-MC), and two pluripotent cell lines with facultative neuronal and glial differentiation (P19 and NT2) by gelatin zymography. The MMP-2 activity profiles were compared to the proliferative activities of the cell lines. MMP-2 expression varied from barely existent (P19 cells) to strong (U138MG and SK-N-SH). Interestingly, for the cell lines with high MMP-2 expression levels, low proliferative activities were recorded, and vice versa. Retinoic acid induced neuronal differentiation and a reduction of proliferation of P19 cells; the differentiated cells produced significantly more MMP-2 than untreated cells. Upon confluency, GOS-3 cells showed reduced proliferation, but increased MMP expression. Thus, proliferative activity was inversely correlated to MMP-2 expression in the tumor cell lines analyzed.

Differences in precision of dietary estimates among different population subgroups.

Populations vary in consistency of diets. The precision of estimates (E) of nutrient intake depends both on the ratio (R) of intraindividual to interindividual variances, as well as on the number of days of dietary intake recorded (k). We present baseline data from 872 participants in the Trial of Antihypertensive Interventions and Management (TAIM), a randomized clinical trial of diet and drug treatment for mild hypertension. There is wide variation in R among different demographic groups and for different nutrients. This has implications for the ability to estimate the correlations between the nutrient and a physiologic variable such as blood pressure, as well as for power calculations to compare group means on nutrient intake. For example, to achieve the same degree of precision (E = 0.80) in estimating the correlation between sodium intake and blood pressure for whites in New York, 7 days of food records would be required, compared to 2 days for whites in Alabama. Tables are presented indicating within- and between-person variances for different groups and different nutrients. Methods of calculating E, determining k, and calculating samples size are provided. Investigators designing nutritional epidemiologic studies should take into account ratios of intraindividual to interindividual variances of different population subgroups and different nutrients in order to determine the number of daily food records that must be obtained and the sample size for group comparisons.

Effect of tamoxifen on bone fractures in older nursing home residents.

OBJECTIVES: To evaluate the association between tamoxifen (TAM) treatment and rate of bone fractures in older, nursing home residents. PARTICIPANTS: A total of 93,031 women, aged 65 years and older, whose data were part of the 1993 New York State MDS and for whom there was documentation of treatment with at least one medication. SETTING: New York State long-term care facilities. DESIGN: Cross-sectional study via secondary analysis of 1385 matched sets of residents. Each set included one resident who was receiving TAM treatment and up to four residents who were not. MEASUREMENTS: Measurements included age, ethnicity, TAM treatment, hormone replacement therapy, vision impairment, any bone fractures, and, specifically, hip fractures. RESULTS: During the 1.5-year period for which bone fractures are documented in the 1993 MDS, the fracture rates were: 7.62% in women not treated with TAM, 3.20% in women receiving 10 mg TAM daily, and 6.73% in women receiving 20 mg TAM daily. The odds ratio (OR) for bone fractures among women receiving 20 mg TAM daily compared with nontreated women was 0.916 (95% confidence interval (CI): 0.720-1.164; P = .472), and was 0.312 (95% CI: 0.112-0.865; P = .025) for those receiving 10 mg daily. The rates of hip fracture were 4.98%, 2.40%, and 4.57% for controls and women receiving 10 mg and 20 mg TAM daily, respectively. Whereas the hip fracture rate for women receiving 20 mg daily was statistically similar to that of the controls (OR = .963; 95% CI: 0.718-1.291; P = .800), the difference between the controls and those receiving 10 mg daily approached significance (OR: 0.313; 95% CI: 0.096-1.018; P = .054). CONCLUSION: Although standard treatment of 20 mg TAM daily offers no apparent protection against bone fracture in older nursing home residents, a daily 10 mg dose seems to be protective.

Sequential outbreak of influenza A and B in a nursing home: efficacy of vaccine and amantadine.

OBJECTIVE: To describe the sequential occurrence of influenza A and B in a nursing home, and to determine the efficacy of influenza vaccine and/or amantadine treatment with respect to incidence and sequelae. SETTING: The Jewish Home and Hospital for Aged, a skilled-care nursing facility. PARTICIPANTS: Of 499 frail older nursing home residents, 139 contracted influenza during the study period (mean age 87.5 years; SD = 6.7). The residents were followed from February through April 1988. INTERVENTION: Influenza vaccine and/or amantadine. MEASUREMENTS: Episodes of influenza and their sequelae, i.e., pneumonia, hospitalization, and death. RESULTS: The vaccine had no effect on the incidence of influenza-like illness, length of illness, or the associated death rate. It reduced the rate of pneumonia secondary to influenza A and B (relative risk = .57; 95% CI: .37 to .89; P = .023). Amantadine did not affect the attack rate of influenza nor the rate of pneumonia secondary to influenza. It was associated with decreased mortality (relative risk = 0; P = .001), and shorter length of influenza A illness (PWilcoxon = .082). Although the combination of amantadine and vaccine did not affect length of influenza (A or B) illness, it was associated with a significantly lower rate of sequelae (relative risk = .58; 95% CI: .36 to .95; P = .024). CONCLUSION: In this epidemic, the combination of amantadine and vaccine was most effective in reducing the rate of influenza-associated sequelae. The possibility of a "biphasic" epidemic prompts consideration of vaccinating nonimmunized nursing home residents, even though it may be late in the influenza season.

Assessing life expectancies of older nursing home residents.

OBJECTIVE: Care of nursing home (NH) residents is often based on the usual survival of the home's residents. In order to improve our understanding of this population, and, thus, ultimately facilitate individualization of their care, we developed a mathematical model that predicts their survival. SETTING: The Jewish Home and Hospital (JHH), a nursing home. PARTICIPANTS: 1145 older residents who were at the JHH from January 1, 1986, through July 1, 1986. MEASUREMENTS: Information abstracted from medical records and JHH computerized data: clinical, demographic, and dependencies in activities of daily living (ADLs). MAIN OUTCOME MEASURE: survival from July 1, 1986. DESIGN: Retrospective cohort study via medical chart review. The study period covered admission to JHH through January 17, 1996. Accelerated failure time (AFT) models generated the life expectancy model derived from 50% of the study group and were validated on the remaining sample. We computed predicted AFT and proportional hazards (PH) life expectancies. RESULTS: Significant, independent predictors of decreased survival were male gender, increased age, increase in summary ADL index, and impairment of cardiac, respiratory, neurological, and endocrine/metabolic systems. The interaction between gender and respiratory system impairment was significant. The Spearman correlation coefficients between the observed survivals and those predicted by the Phase I model are 0.49 for Phase I residents and 0.42 for Phase II residents. Our sample life table includes NH residents with different risk profiles and their associated survival estimates as well as interquartile ranges. AFT and PH survivals were similar. CONCLUSION: This first comprehensive model that predicts survival of NH residents can help formulate public health policies and identify appropriate NH residents for clinical trials. The model is a promising step toward improving the health care of NH residents.

Restraint reduction reduces serious injuries among nursing home residents.

OBJECTIVES: To describe how removing physical restraints affected injuries in nursing home settings. DESIGN: A 2-year prospective study of an educational intervention for physical restraint reduction. SETTING: Sixteen diverse nursing homes with 2075 beds in California, Michigan, New York, and North Carolina. PARTICIPANTS: Study A: 859 residents who were physically restrained at the onset of the intervention on October 1, 1991. Study B: all residents who occupied the 2075 beds in the 16 facilities 3 months before the intervention and 3 months after its completion. INTERVENTION: Educational program for nursing home staff followed by quarterly site consultations to participating nursing homes. MAIN OUTCOME MEASURES: Rate of physical restraint use and injuries. RESULTS: Study A: Serious injuries declined significantly among the 859 residents restrained initially when restraint orders were discontinued (X2 = 6.2, P = .013). Study B: During the intervention period, physical restraint use among the 2075 residents decreased from 41% to 4%, a 90% reduction. The decrease in the percentage of injuries of moderate to serious severity was significant (i.e., 7.5% vs 4.4%, P2-tail = .0004) as was the rate of moderate and serious injuries combined (Rate Ratio = 1.580, P2-tail = .0033). CONCLUSIONS: A substantial decrease in restraint use occurred without an increase in serious injuries. Although minor injuries and falls increased, restraint-free care is safe when a comprehensive assessment is done and restraint alternatives are used.

Intraoperative cholangiography revisited.

The charts of 1351 patients undergoing cholecystectomy at our institutions from 1985 through 1989 were reviewed retrospectively to evaluate the indications for and the success of intraoperative cholangiography. A total of 800 patients underwent intraoperative cholangiography. They were divided into two groups based on the absence (CR-) or presence (CR+) of clinical and/or operative criteria suggestive of the existence of common bile duct stones. Intraoperative cholangiography in CR- patients was of limited benefit, being negative (normal) in 95.7%, true-positive (abnormal) in 3.3%, and false-positive in 1%. False-positive intraoperative cholangiography resulted in unnecessary common bile duct explorations. Intraoperative cholangiography in CR+ patients proved useful, avoiding unnecessary common bile duct exploration in 55%. In those select CR+ patients with palpable common bile duct stones or cholangitis, little additional information was gained by the intraoperative cholangiography. We conclude that routine screening intraoperative cholangiography in CR- patients be reconsidered, as should the use of intraoperative cholangiography in CR+ patients with a palpable common bile duct stone or cholangitis. Intraoperative cholangiography in the remainder of CR+ patients proved beneficial and should be continued.

Relationships of sex hormone levels to dependence in activities of daily living in the frail elderly.

OBJECTIVES: We undertook this nursing home study in order to determine the relationships between dependency in activities of daily living (ADL) and blood levels of estrone, testosterone, androstenedione, and dehydroepiandrosterone (DHEA). Little is known about this issue. METHODS: cross-sectional study of 370 nursing home residents. Hormone levels in blood specimens drawn in 1997 and 1998 were correlated with degree of ADL dependency recorded in medical charts. RESULTS: Because of multiple comparisons associations were deemed significant for P-values < or =0.017 for males and < or =0.0125 for females. In males, the following were inversely related: testosterone levels with dependency in transferring and eating; estrone with eating and a summary ADL index; and androstenedione with toileting and a summary ADL index (in all cases, r=-0.4; P=0.007-0.015). Inverse trends existed between testosterone levels and dependency in mobility and a summary ADL index; and androstenedione and eating (in all cases r=-0.3; P=0.030-0.055). Among females the following were directly related: estrone levels with dependence in mobility, toileting, transferring, and a summary ADL index; and DHEA with transferring and a summary ADL index (r=0.2-0.3, P=0.0001-0.01). Trends existed between estrone and eating, and DHEA and toileting (r=0.1-0.2, P=0.04). CONCLUSION: In male residents, higher sex hormone levels are associated with better ADL performance. Among females the opposite is true. While further studies are needed to elucidate these relationships, our results and recent findings of others suggest sex hormone actions in older women differ from those in younger populations. A possible stress-related mechanism is also presented.

Changes in bedrail prevalence during a bedrails-reduction initiative.

OBJECTIVE: To examine the prevalence of bedrails and observe whether use of bedrails can be decreased during a bedrails-reduction initiative. DESIGN: A serial, cross-sectional, observational study of bedrail use. PATIENTS AND SETTING: An 816-bed not-for-profit nursing facility with academic affiliation and closed medical staff. Median age of residents was 88.1 (range 62-108); 74% were women and 26% were men. MEASUREMENTS: Observed use of bedrails with classification of bedrail configurations into Enclosure Levels based on percentage of bedsides enclosed; serial census of bedrail use during a restraint-reduction effort. RESULTS: Bedrail configurations fell into five Enclosure Levels based on percentage of the bed enclosed. Over 9 months, total bedrail prevalence increased from 50 to 56%; however, the highest Enclosure Levels decreased from 7.7 to 3.9%. CONCLUSIONS: Bedrail configurations can be placed on a continuum of enclosure, and highest Enclosure Levels can be decreased during a bedrails-reduction program.

Separation of fatty acids or methyl esters including positional and geometric isomers by alumina argentation thin-layer chromatography.

This paper describes novel and rapid thin-layer chromatography procedures for the analysis of fatty acids and methyl esters using silver-impregnated alumina sheets. These techniques are known in most laboratories, and the equipment is readily available. The fatty acid method allows a separation of petroselinic (C18:1 delta 6c), oleic (C18:1 delta 9c), elaidic (C18:1 delta 9t), erucic (C22:1 delta 13c), and brassidic acids (C22:1 delta 13t), and the methyl ester method gives an excellent resolution with respect to the number, configuration, and position of the unsaturated centers. Sufficient separation for the subsequent ozonolysis and chromatographic quantification of isomeric C18 and C22 fatty acid methyl esters is obtained with both methods.

Old problem, different approach: alternatives to physical restraints.

Individualized care, resident assessment by a multidisciplinary team, and rehabilitation enhance functional independence in nursing home residents. Creativity in choosing alternatives to restraints was important in successful restraint reduction. Residents free of restraints had higher ADL levels, were more continent, and sustained fewer serious injuries, all of which are important quality of life indicators.