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Biomedical subjects

D L Jones

Publications and source records attributed to D L Jones.

At least 37 records · Page 2Linked to original sources
PubMed2001

A two-microphone dual delay-line approach for extraction of a speech sound in the presence of multiple interferers.

This paper describes algorithms for signal extraction for use as a front-end of telecommunication devices, speech recognition systems, as well as hearing aids that operate in noisy environments. The development was based on some independent, hypothesized theories of the computational mechanics of biological systems in which directional hearing is enabled mainly by binaural processing of interaural directional cues. Our system uses two microphones as input devices and a signal processing method based on the two input channels. The signal processing procedure comprises two major stages: (i) source localization, and (ii) cancellation of noise sources based on knowledge of the locations of all sound sources. The source localization, detailed in our previous paper [Liu et al., J. Acoust. Soc. Am. 108, 1888 (2000)], was based on a well-recognized biological architecture comprising a dual delay-line and a coincidence detection mechanism. This paper focuses on description of the noise cancellation stage. We designed a simple subtraction method which, when strategically employed over the dual delay-line structure in the broadband manner, can effectively cancel multiple interfering sound sources and consequently enhance the desired signal. We obtained an 8-10 dB enhancement for the desired speech in the situations of four talkers in the anechoic acoustic test (or 7-10 dB enhancement in the situations of six talkers in the computer simulation) when all the sounds were equally intense and temporally aligned.

Algorithms↗
PubMed2001

Lipid-lowering efficacy, safety, and costs of a large-scale therapeutic statin formulary conversion program.

STUDY OBJECTIVE: To assess the lipid-lowering efficacy, safety, and costs of a large-scale statin formulary conversion program. DESIGN: Prospective, observational study. SETTING: Tertiary academic medical center. PATIENTS: A total of 980 patients consented to participate; 942 patients completed the study. INTERVENTION: Patients were converted from their current statin therapy to either cerivastatin 0.4 or 0.8 mg/day, or simvastatin 80 mg/day, using a conversion algorithm. MEASUREMENTS AND MAIN RESULTS: Efficacy and safety were evaluated at baseline and after 6 weeks of therapy; costs were also measured. Overall attainment of the National Cholesterol Education Program (NCEP) goal for low-density lipoprotein cholesterol (LDL) increased from 64.8% to 74.5% of patients (p<0.001); mean LDL decreased from 115+/-30 mg/dl to 106+/-25 mg/dl (p<0.001). Adverse events occurred in 3% of patients, and included myositis (0.6%) and increased hepatic transaminases (0.1%). Overall costs were reduced by $115/patient treatment-year. CONCLUSION: Statin therapeutic interchange can improve lipid control at reduced costs. The possibility of uncommon but potentially serious adverse effects suggests that these programs require appropriate monitoring.

Aged↗
PubMed2001

The use of modularity in revision total hip replacement.

A study was undertaken to establish the pattern of components revised in recent years during total hip revision to establish how often a modular feature of a retained component was used. All total hip revisions performed by the total joint service of the University Hospital between 1991 and 1995 were reviewed. Revisions involving a surface replacement, endoprosthesis, bipolar stem, or infection were excluded because retention of components is not an option in these cases. This left 158 cases for review. If a modular femoral or acetabular component was retained, it was determined whether a different length of modular head or different liner type was replanted, thus using a modular feature of the component. The most common pattern of component revision was to revise all components, which was done in 77 of 158 cases (48.7%). The second most common pattern was to revise a socket and leave the stem in place (53/158, 33.5%). The third most common was to revise the stem and leave the socket in place (22/158, 13.9%). The least common was to retain both the stem and socket and exchange the head and liner (6/158, 3.8%). Of the 59 cases in which the stem was retained, a modular head of a different length was used in 52 (88%). Of the 28 cases in which a socket was retained, a different liner type was used in 14 (50%). The modular aspect of the retained component was a valuable asset at the time of revision in a high percentage of cases (66/158, 41.8%).

Arthroplasty, Replacement, Hip↗
PubMed2000

Lack of correlation between psychological factors and subclinical coronary artery disease.

BACKGROUND: The relation between psychological variables and clinically evident coronary artery disease has been studied extensively, although the potential mechanisms of such a relation remain speculative. We studied the relation between multiple psychological variables and subclinical coronary artery disease to assess the possible role of such variables in atherogenesis. METHODS: We conducted a prospective study of 630 consecutive consenting, active-duty U.S. Army personnel, 39 to 45 years of age, without known coronary artery disease. Each participant was assessed for depression, anxiety, somatization, hostility, and stress. Subclinical coronary artery disease was identified by electron-beam computed tomography. RESULTS: The mean (+/-SD) age of the subjects was 42+/-2 years; 82 percent were male, and 72 percent were white. The prevalence of coronary-artery calcification was 17.6 percent (mean calcification score, 10+/-49). The prevalence of prior or current psychiatric disorders was 12.7 percent. There was no correlation between the coronary-calcification score and the scores measuring depression (r= -0.07, P=0.08), anxiety (r=-0.07, P=0.10), hostility (r=-0.07, P=0.10), or stress (r=-0.002, P=0.96). Somatization (the number and severity of durable physical symptoms) was inversely correlated with calcification scores (r=-0.12, P=0.003), even after we controlled for age and sex. In multivariate logistic-regression models, a somatization score greater than 4 (out of a possible 26) was independently associated with the absence of any coronary-artery calcification (odds ratio, 0.49; 95 percent confidence interval, 0.25 to 0.96). CONCLUSIONS: Our data suggest that depression, anxiety, hostility, and stress are not related to coronary-artery calcification and that somatization is associated with the absence of calcification.

Adult↗
PubMed2000

Clinical crown length changes from age 12-19 years: a longitudinal study.

OBJECTIVE: The objective of this study was to investigate the relationship between age, gender and clinical crown length using a longitudinal study design. METHOD: Four hundred and fifty-six sets of study models initially obtained for a large prospective longitudinal cohort study of orthodontic needs were examined. Each set of models corresponded to subjects at three different ages: 11-12, 14-15 and 18-19years old. The clinical crown height of the maxillary right central incisor (11), maxillary right canine (13), maxillary left lateral incisor (22) and mandibular left central incisor (31) was measured from gingival crest to the incisal edge using digital calipers. RESULTS: Analysis revealed a significant (p<0.0001) age effect on crown length for all four teeth investigated. A significant gender effect was found in relation to the maxillary right canine, maxillary right central incisor and maxillary left lateral incisor. Pairwise comparisons of the means for each age group for the maxillary right canine, maxillary right central incisor and maxillary left lateral incisor revealed significant (p<0. 0001) increases in clinical crown length between each assessment period. CONCLUSION: The findings of the present study indicate that, the process of passive eruption, resulting in increased clinical crown length appears to continue throughout the teenage years. This finding is considered to be of importance to the clinician making treatment decisions for teenagers and young adults requiring treatment in the anterior segments of the mouth.

Adolescent↗
PubMed2000

Through form to function: root hair development and nutrient uptake.

Root hairs project from the surface of the root to aid nutrient and water uptake and to anchor the plant in the soil. Their formation involves the precise control of cell fate and localized cell growth. We are now beginning to unravel the complexities of the molecular interactions that underlie this developmental regulation. In addition, after years of speculation, nutrient transport by root hairs has been demonstrated clearly at the physiological and molecular level, with evidence for root hairs being intense sites of H(+)-ATPase activity and involved in the uptake of Ca(2+), K(+), NH(4)(+), NO(3)(-), Mn(2+), Zn(2+), Cl(-) and H(2)PO(4)(-).

Nitrogen↗
PubMed2000

Enhancing adherence to combination antiretroviral therapy in non-adherent HIV-positive men.

This paper describes a preliminary study aimed at testing the efficacy of a brief medication counselling and behavioural intervention in improving adherence to combination antiretroviral medication therapy and prophylactic treatment among non-adherent men living with HIV. Twenty-one non-adherent HIV-positive men obtaining primary care clinical services at a Veterans Affairs Medical Center were recruited by health care providers. Intervention participants were primarily African-Americans with histories of intravenous drug use. During a period of five months, participants were provided with monthly medication counselling and a weekly medication pill organizer. Participants were compared with 21 non-adherent matched controls receiving standard pharmacy care including review of medications. Intervention and control subjects were compared on several variables: medication refill timeliness, appointment attendance, hospitalizations and opportunistic infections. Medical information was obtained from hospital and pharmacy records at baseline and post-intervention. Pre- to post-intervention rates of adherence to medication refills and clinic appointments increased significantly among intervention participants. Relative to matched controls, intervention participants also significantly increased drop-in visits and showed fewer hospitalizations. Intervention participants also showed significant decreases in the number of opportunistic infections. Results suggest that exposure to medication counselling and behavioural interventions increase adherence, with associated reductions in negative clinical outcomes.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Use of female controlled microbicidal products for HIV risk reduction.

Many over-the-counter microbicidal contraceptive methods reduce the risk of acquiring sexually transmitted diseases. This pilot project compared the use of female controlled barrier methods in an extremely high-risk population of low-income drug abusing women following an intervention designed to promote HIV risk reduction and barrier use. An HIV transmission risk reduction interactive intervention emphasizing self-esteem, assertiveness and sexual negotiation was offered to 41 drug dependent women. Participants were randomly assigned to one of two conditions, a male and female condom condition or a male and female condom plus N-9 products (vaginal suppositories, film, gel) condition. Results from the three-month follow-up period suggest that there may be a synergistic effect of availability of multiple protective methods on the overall rate of protective behaviours. The use of the male condom for penile/vaginal sex increased from 19% at study entry to 27% during the three-month follow-up period. The total protected sexual episode rate, calculated to include use of the other protective barriers distributed, was 60%. Thus, the condom use rate was not found to decrease because of the availability of alternative methods of protection. Future research should address the use of microbicidal products to empower women to prevent STD/HIV transmission.

Adult↗
PubMed2000

The relationship between temporal aspects of oral-nasal balance and classification of velopharyngeal status in speakers with cleft palate.

OBJECTIVE: The purpose of this investigation was to determine whether temporal patterns of oral-nasal balance differentiate speakers with cleft palate who exhibit adequate and inadequate velopharyngeal function. DESIGN: The Nasal Accelerometric Vibrational Index (NAVI) was used to measure the time course and amplitude of oral-nasal balance during the productions of syllables, words, and sentences. The measures obtained include mean amplitude, time integral (area under the curve), absolute duration, relative duration, rise time, and fall time. PARTICIPANTS: The subjects for this study were 20 children with repaired cleft palates with or without cleft lip. Ten children (aged 5 through 18 years) were assigned to the velopharyngeal competence (VPC) group (normal oral-nasal resonance, no nasal emission of air). Ten children (aged 3 through 19) were assigned to the velopharyngeal insufficiency (VPI) group (hypernasal speech, velopharyngeal gap observed via nasal endoscopy). RESULTS: Both mean amplitude and time integral of NAVI were greater in the VPI group than in the VPC group (p < .01). Absolute duration and relative duration of the NAVI signal were greater in the VPI group (p < .01). NAVI rise time was shorter in the VPI group (p < .01), and NAVI fall time was longer in the VPI group (p < .01). The amplitude measures contributed the most to discrimination of speaker group, but the durational measures become increasingly influential as a function of a speech task. CONCLUSIONS: Although amplitude of nasalization may have the strongest perceptual salience in classification of velopharyngeal status, the temporal component may exert greater influence during more complex speech tasks.

Acceleration↗
PubMed2000

Age- and myopathy-dependent changes in connexins of normal and cardiomyopathic Syrian hamster ventricular myocardium.

The conduction of cardiac action potentials depends on the flow of excitation through gap junctions, which are hexameric protein associations of connexins (Cxs). The major Cx reported in the heart is Cx43, although some Cx40 and Cx45 are also present. There is some evidence for altered Cx content in heart failure. In heart failure, conduction is depressed and slowed conduction may contribute to arrhythmogenesis and (or) the maintenance of arrhythmia. Cx content and distribution were determined in ventricular tissues from normal and cardiomyopathic Syrian hamsters, an animal model of heart failure which has reproducible age-specific cardiomyopathy resulting in heart failure and age-matched controls in three groups: young (3-5 weeks), adult (13-18 weeks), and old (>45 weeks). Frozen, unfixed sections of ventricular tissues were immunofluorescently stained using antibodies against Cx43, Cx40, and Cx45. Cx43 was the predominant Cx detected in all samples. In normal hamsters, Cx43 was localized predominantly at the intercalated disc region, while in myopathic myocytes, it was scattered. In Western blots, Cx43 content of normal hamster hearts was highest in the adult hearts compared with young and old hamster hearts. In contrast, Cx43 content was significantly lower in adult cardiomyopathic hamster hearts compared with all other groups. The alterations of content and distribution of gap junction Cx43 may contribute to diminished conduction, pump function, and arrhythmogenesis in heart failure.

Age Factors↗
PubMed2000

Treatment of nicotine addiction.

The best available data show smoking to be by far the most important cause of disease and death in our society, contributing to an average of 1000 deaths every day. Although a large majority of current smokers express a desire to quit, the majority of "self-help" attempts to quit are not successful. Further, most smokers indicate never having received advice on cessation from healthcare providers. The combination of pharmacotherapy and behavioral interventions, even on a minimal level, have been shown to be effective in cessation. Such strategies are certainly highly cost-effective, given the enormous costs to society of smoking-related illnesses. Therefore, it is important that all healthcare providers provide at least some form of smoking cessation programs for their patients.

Administration, Cutaneous↗
PubMed1999

Serine phosphorylation of the sarcoplasmic reticulum Ca(2+)-ATPase in the intact beating rabbit heart.

Recent studies have demonstrated that Ca(2+)/calmodulin-dependent protein kinase phosphorylates the Ca(2+)-pumping ATPase of cardiac sarcoplasmic reticulum (SR) in vitro. Also, evidence from in vitro studies suggested that this phosphorylation, occurring at Ser(38), results in stimulation of Ca(2+) transport. In the present study, we investigated whether serine phosphorylation of the SR Ca(2+)-ATPase occurs in the intact functioning heart. Hearts removed from anesthetized rabbits were subjected to retrograde aortic perfusion of the coronary arteries with oxygenated mammalian Ringer solution containing (32)P(i) and contractions were monitored by recording systolic left ventricular pressure development. Following 45-50 min of (32)P perfusion, the hearts were freeze-clamped, SR isolated, and analyzed for protein phosphorylation. SDS-polyacrylamide gel electrophoresis and autoradiography showed phosphorylation of several peptides including the Ca(2+)-ATPase and Ca(2+) release channel (ryanodine receptor). The identity of Ca(2+)-ATPase as a phosphorylated substrate was confirmed by Western immunoblotting as well as immunoprecipitation using a cardiac SR Ca(2+)-ATPase-specific monoclonal antibody. The Ca(2+)-ATPase showed immunoreactivity with a phosphoserine monoclonal antibody indicating that the in situ phosphorylation occurred at the serine residue. Quantification of Ca(2+)-ATPase phosphorylation in situ yielded a value of 208 +/- 12 pmol (32)P/mg SR protein which corresponded to the phosphorylation of approximately 20% of the Ca(2+) pump units in the SR membrane. Since this phosphorylation occurred under basal conditions (i.e., in the absence of any inotropic intervention), a considerable steady-state pool of serine-phosphorylated Ca(2+)-ATPase likely exists in the normally beating heart. These findings demonstrate that serine phosphorylation of the Ca(2+)-ATPase is a physiological event which may be important in the regulation of SR function.

Animals↗
PubMed1999

Expression of the HPV E7 oncoprotein mimics but does not evoke a p53-dependent cellular DNA damage response pathway.

Acute expression of the human papillomavirus E7 oncoprotein in preimmortal human fibroblasts induces changes in the abundances of multiple cellular regulatory proteins. These alterations include a destabilization of the retinoblastoma tumor suppressor protein pRB, stabilization of the tumor suppressor protein p53, and increases in the level of the cyclin-dependent kinase inhibitor p21(cip1). Since the HPV E7 oncoproteins can interfere with several cell cycle checkpoints and similar alterations in the levels of pRB, p53, and p21(cip1) are also observed in a p53-dependent response to DNA damage, we investigated whether E7 expression triggers this signal transduction pathway. The results demonstrate that E7-mediated destabilization of pRB does not require p53 activity and is independent of the ability of E7 to induce apoptosis. Moreover, E7-mediated increases in p21(cip1) levels are largely p53-independent and involve stabilization of the p21(cip1) protein. In contrast the decreases in pRB expression in response to DNA damage involve transcriptional downregulation of RB gene expression.

Apoptosis↗
PubMed1999

Rationale and design of the Prospective Army Coronary Calcium (PACC) Study: utility of electron beam computed tomography as a screening test for coronary artery disease and as an intervention for risk factor modification among young, asymptomatic, active-duty United States Army Personnel.

BACKGROUND: Screening for coronary artery calcium with electron beam computed tomography (EBCT) has potential diagnostic and prognostic implications. Most prior research on this technology has been done on selected, high-risk populations. The goal of the Prospective Army Coronary Calcium (PACC) study is to determine the utility of EBCT for the detection of coronary calcium as a screening test for coronary artery disease and as an intervention for risk factor modification among young, asymptomatic, active-duty personnel undergoing the United States Army's Cardiovascular Screening Program. METHODS AND RESULTS: Three study designs will be used to address the objectives of this investigation: (1) a cross-sectional study of 2000 unselected, consecutive participants to determine the prevalence and extent of coronary calcification in the 40- to 45-year-old Army population, (2) a randomized, controlled trial with a 2 x 2 factorial design involving 1000 participants to assess the impact of EBCT information on several dimensions of patient behavior, with and without intensive risk factor case management, and (3) a prospective cohort study of 2000 participants followed for at least 5 years to establish the relation between coronary calcification and cardiovascular events in an unselected, "low-risk" (by conventional standards) Army population. CONCLUSIONS: We present a review of the literature on the clinical utility of EBCT, with a focus on the limited research in young, asymptomatic populations. The details of the PACC study (begun in October1998) are presented. The results of the PACC study will determine the clinical utility of EBCT in young, asymptomatic patients.

Adult↗
PubMed1999

Time-scale detection of microemboli in flowing blood with Doppler ultrasound.

Small formed elements and gas bubbles in flowing blood, called microemboli, can be detected using Doppler ultrasound. In this application, a pulsed constant-frequency ultrasound signal insonates a volume of blood in the middle cerebral artery, and microemboli moving through its sample volume produce a Doppler-shifted transient reflection. Current detection methods include searching for these transients in a short-time Fourier transform (STFT) of the reflected signal. However, since the embolus transit time through the Doppler sample volume is inversely proportional to the embolus velocity (Doppler-shift frequency), a matched-filter detector should in principle use a wavelet transform, rather than a short-time Fourier transform, for optimal results. Closer examination of the Doppler shift signals usually shows a chirping behavior apparently due to acceleration or deceleration of the emboli during their transit through the Doppler sample volume. These variations imply that a linear wavelet detector is not optimal. We apply linear and quadratic time-frequency and time-scale detectors to a set of noise-corrupted embolus data. Our results show improvements of about 1 dB using the time-scale detectors versus an STFT-based detector signifying that embolus detection is best approached as a time-scale problem. A time-scale-chirp detector is also applied and is found to have the overall best performance by about 0.5-0.7 dB while coming fairly close (about 0.75 dB) to a theoretical upper bound.

Cerebral Arteries↗
PubMed1999

Detection of lines and boundaries in speckle images--application to medical ultrasound.

This paper describes an approach to boundary detection in ultrasound speckle based on an image enhancement technique. The enhancement algorithm works by filtering the image with "sticks," short line segments which are varied in orientation to achieve the maximum projected value at each point. The statistical properties of this approach have been described in an earlier paper; in this work we present three significant extensions to improve the performance of the basic method. First, we investigate the effect of varying the size and shape of the sticks. We show that these variations affect the performance of the algorithm in very fundamental ways, for example by making it more or less sensitive to thinner or more tightly curving boundaries. Second, we present a means of improving the performance of this technique by estimating the distribution function of the orientation of the line passing through each point. Finally, we show that images can be "stained" for easier visual interpretation by applying to each pixel a false color whose hue is related to the orientation of the most prominent line segment at that point. Examples are given to illustrate the performance of the different settings on a single image.

Algorithms↗
PubMed1999

Comparison of discharge diagnoses and inpatient procedures between military and civilian health care systems.

BACKGROUND: Our goal was to compare the demographics and discharge diagnoses between civilian and military health care systems. METHODS: One year (1997) of data from the Retrospective Case Mix Adjustment System from the Military Health Services System were compared with the most recent (1994) civilian National Hospital Discharge Survey data. RESULTS: Military and civilian inpatient age (52.5 and 52.9 years), gender (54% and 59% female), and ethnic distributions (military: 71% white, 16% African American, 3% Asian American, 10% other; civilian: 65% white, 12% African American, 2.6% Asian American, 1.2% Native American, 18% unclassified) were similar. There were similar rank orderings of diagnosis-related groupings (Spearman's rank correlation = 0.72) and procedures performed during hospitalization (Spearman's rho = 0.74), although the military inpatients yielded a higher proportion associated with pregnancy and strenuous activity (traumatic joint disorders and hernias) than their civilian counterparts. CONCLUSION: The practice content of military and civilian inpatients appear to be more similar than different.

Diagnosis-Related Groups↗