Biomedical subjects

J Powers

Publications and source records attributed to J Powers.

At least 19 recordsLinked to original sources

PubMed2006

A phase II study of bortezomib in mantle cell lymphoma: the National Cancer Institute of Canada Clinical Trials Group trial IND.150.

BACKGROUND: We evaluated the activity and toxic effects of bortezomib in patients with mantle cell lymphoma. PATIENTS AND METHODS: Thirty patients, including 29 eligible patients, were enrolled; 13 had received no prior chemotherapy. The dose of bortezomib was 1.3 mg/m2 given on days 1, 4, 8 and 11 every 21 days. Response was assessed according to the International Workshop Criteria for non-Hodgkin's lymphoma and toxicity graded using the National Cancer Institute Common Toxicity Criteria version 2.0. RESULTS: There were 13 responding patients (46.4%; 95% confidence interval=27.5% to 66.1%), including one unconfirmed complete remission. The median response duration was 10 months. Response rates were similar in previously untreated (46.2%) and treated (46.7%) patients. Neurological toxicity and myalgia led to treatment discontinuation in 10 patients after two to seven treatment cycles. Five serious adverse events (including two deaths) associated with fluid retention were observed in the first 12 patients. We subsequently excluded patients with baseline effusions, dyspnea or edema; no further events were seen. CONCLUSIONS: Bortezomib is active in treating patients with mantle cell lymphoma. While cumulative neuromuscular toxic effects limited therapy duration and specific issues related to fluid retention require further evaluation, continued study of this drug in combination regimens is warranted.

Aged↗

PubMed2006

A phase I, first in man study of OSI-7836 in patients with advanced refractory solid tumors: IND.147, a study of the Investigational New Drug Program of the National Cancer Institute of Canada Clinical Trials Group.

PURPOSE: To determine the maximum tolerated dose (MTD), recommended phase II dose (RP2D), safety, tolerability, toxicity profile, dose-limiting toxicities (DLTs), anti-tumor activity and pharmacokinetics of OSI-7836 given IV on day 1 and day 8 every 3 weeks in patients with advanced incurable cancer. METHODS: Twenty-seven previously treated patients with advanced or metastatic solid tumors were enrolled in this phase I study conducted by the National Cancer Institute of Canada Clinical Trial Group (NCIC CTG). OSI-7836 was administered IV on day 1 and day 8 every 3 weeks. The dose was initially escalated from 100 to 600 mg/m2 and finally de-escalated to 200 mg/m2 in seven cohorts of patients. Patients were evaluated every other cycle of treatment for radiological response. Pharmacokinetics were performed on day 1 and day 8 of cycle 1 for all patients. RESULTS: Twenty-six patients were evaluable for toxicity. All patients experienced reversible Grade 3 lymphopenia beginning at cycle 1. The maximal delivered dose was 600 mg/m2. MTD was reached at 400 mg/m2. DLTs included fever, fatigue, rash, herpes simplex infection, nausea and vomiting. The RP2D was 200 mg/m2. No objective responses were seen in 21 evaluable patients. Pharmacokinetics were dose proportional, with a mean half-life of 46.0 min and a clearance of 34 l/(h.m2). CONCLUSION: OSI-7836 given at 200 mg/m2 on day 1 and day 8 every 3 weekly is associated with manageable toxicity and is recommended for further study. While no objective responses were seen, the significant treatment related lymphopenia suggests that hematologic malignancies may warrant further investigation.

Adult↗

PubMed2003

Role of ALDP (ABCD1) and mitochondria in X-linked adrenoleukodystrophy.

Peroxisomal disorders have been associated with malfunction of peroxisomal metabolic pathways, but the pathogenesis of these disorders is largely unknown. X-linked adrenoleukodystrophy (X-ALD) is associated with elevated levels of very-long-chain fatty acids (VLCFA; C(>22:0)) that have been attributed to reduced peroxisomal VLCFA beta-oxidation activity. Previously, our laboratory and others have reported elevated VLCFA levels and reduced peroxisomal VLCFA beta-oxidation in human and mouse X-ALD fibroblasts. In this study, we found normal levels of peroxisomal VLCFA beta-oxidation in tissues from ALD mice with elevated VLCFA levels. Treatment of ALD mice with pharmacological agents resulted in decreased VLCFA levels without a change in VLCFA beta-oxidation activity. These data indicate that ALDP does not determine the rate of VLCFA beta-oxidation and that VLCFA levels are not determined by the rate of VLCFA beta-oxidation. The rate of peroxisomal VLCFA beta-oxidation in human and mouse fibroblasts in vitro is affected by the rate of mitochondrial long-chain fatty acid beta-oxidation. We hypothesize that ALDP facilitates the interaction between peroxisomes and mitochondria, resulting, when ALDP is deficient in X-ALD, in increased VLCFA accumulation despite normal peroxisomal VLCFA beta-oxidation in ALD mouse tissues. In support of this hypothesis, mitochondrial structural abnormalities were observed in adrenal cortical cells of ALD mice.

ATP Binding Cassette Transporter, Subfamily D, Mem↗

PubMed2001

Bioequivalent or nonbioequivalent?

The current tests for bioequivalence are based on assumptions that are not valid in general; this paper shows why it is necessary to use a method that does not depend upon assumptions that cannot, and need not, be proved in general.

Area Under Curve↗

PubMed2001

Intrapartum management of nonvertex second-born twins: a critical analysis.

OBJECTIVE: Our purpose was to assess the impact of the mode of delivery--vaginal delivery versus cesarean section--on the perinatal outcomes of the second-born breech twins. STUDY DESIGN: This study was a retrospective analysis of second-born breech twins with a gestational age of > or =24 weeks at the onset of labor. The patients are divided into three groups: cesarean section without labor (group I), cesarean section after labor (group II), and vaginal breech delivery (group III). RESULTS: There were 141 patients: 40 in group I, 66 in group II, and 35 in group III. There was no birth injury or neonatal death. Group II had one fetus with grade II intraventricular hemorrhage. There was no significant difference among the groups with regard to gestational age, birth weight, hyaline membrane disease, Apgar scores at 1 and 5 minutes, and cord blood gas indices, except venous pH in infants with birth weights <1500 g. CONCLUSIONS: Vaginal delivery of breech second-born twins, with gestational ages of at least 24 weeks, especially those with birth weights of > or =1500 g, appears to be a safe alternative to cesarean section.

Birth Weight↗

PubMed2001

Spindle dynamics and the role of gamma-tubulin in early Caenorhabditis elegans embryos.

gamma-Tubulin is a ubiquitous and highly conserved component of centrosomes in eukaryotic cells. Genetic and biochemical studies have demonstrated that gamma-tubulin functions as part of a complex to nucleate microtubule polymerization from centrosomes. We show that, as in other organisms, Caenorhabditis elegans gamma-tubulin is concentrated in centrosomes. To study centrosome dynamics in embryos, we generated transgenic worms that express GFP::gamma-tubulin or GFP::beta-tubulin in the maternal germ line and early embryos. Multiphoton microscopy of embryos produced by these worms revealed the time course of daughter centrosome appearance and growth and the differential behavior of centrosomes destined for germ line and somatic blastomeres. To study the role of gamma-tubulin in nucleation and organization of spindle microtubules, we used RNA interference (RNAi) to deplete C. elegans embryos of gamma-tubulin. gamma-Tubulin (RNAi) embryos failed in chromosome segregation, but surprisingly, they contained extensive microtubule arrays. Moderately affected embryos contained bipolar spindles with dense and long astral microtubule arrays but with poorly organized kinetochore and interpolar microtubules. Severely affected embryos contained collapsed spindles with numerous long astral microtubules. Our results suggest that gamma-tubulin is not absolutely required for microtubule nucleation in C. elegans but is required for the normal organization and function of kinetochore and interpolar microtubules.

Amino Acid Sequence↗

PubMed2001

Memory for memory.

Participants read short passages and 1 day later they answered questions via telephone about the passages (text facts) and about the experimental session (event facts). They were telephoned again 6 weeks later and answered the same questions about text and event facts. They also answered new questions about whether they remembered the answers they had given in the initial telephone interview (recall for prior memory performance). Although participants accurately remembered the majority of past memory successes, they were poor at remembering past memory failures. After being provided with the correct answer and tested again, the participants' performance improved somewhat, especially for memory failures. This suggests that some errors in recalling past forgetting might have been due to correctly remembering the answer previously given, but failing to realize that it had been wrong. These findings have implications for a variety of situations in which people are queried about past memory performance.

Adolescent↗

PubMed2001

Child maltreatment and the early onset of problem behaviors: can a program of nurse home visitation break the link?

This study investigated the relationship between child maltreatment and the early onset of problem behaviors in the Elmira Nurse Home Visitation Program. Participants were predominantly low-income and unmarried mothers and their first-born children who were randomized either to receive over 2 years of home-visitation services by nurses or to be placed in a comparison group. Data were drawn from a follow-up study that took place when the children were 15 years of age. Results demonstrated that, in the comparison group. child maltreatment was associated with significant increases in the number of early onset problem behaviors reported by the youth. For the youth in the nurse-visited group there was no relationship between maltreatment and early onset problem behaviors. We suggest that this finding was due to the effects of the intervention in reducing the number as well as the developmental timing of the maltreatment incidents. Results suggest that prenatal and infancy home visiting by nurses can moderate the risk of child maltreatment as a predictor of conduct problems and antisocial behavior among children and youth born into at-risk families.

Adolescent↗

PubMed2000

Preventing child abuse and neglect with a program of nurse home visitation: the limiting effects of domestic violence.

CONTEXT: Home visitation to families with young children has been promoted as an effective way to prevent child maltreatment, but few studies have examined the conditions under which such programs meet this goal. OBJECTIVE: To investigate whether the presence of domestic violence limits the effects of nurse home visitation interventions in reducing substantiated reports of child abuse and neglect. DESIGN: Fifteen-year follow-up study of a randomized trial. SETTING: Semirural community in upstate New York. PARTICIPANTS: Of 400 socially disadvantaged pregnant women with no previous live births enrolled consecutively between April 1978 and September 1980, 324 mothers and their children participated in the follow-up study. INTERVENTIONS: Families were randomly assigned to receive routine perinatal care (control group; n = 184 participated in follow-up), routine care plus nurse home visits during pregnancy only (n = 100), or routine care plus nurse home visits during pregnancy and through the child's second birthday (n = 116). MAIN OUTCOME MEASURES: Number of substantiated reports over the entire 15-year period involving the study child as subject regardless of the identity of the perpetrator or involving the mother as perpetrator regardless of the identity of the child abstracted from state records and analyzed by treatment group and level of domestic violence in the home as measured by the Conflict Tactics Scale. RESULTS: Families receiving home visitation during pregnancy and infancy had significantly fewer child maltreatment reports involving the mother as perpetrator (P =. 01) or the study child as subject (P =.04) than families not receiving home visitation. The number of maltreatment reports for mothers who received home visitation during pregnancy only was not different from the control group. For mothers who received visits through the child's second birthday, the treatment effect decreased as the level of domestic violence increased. Of women who reported 28 or fewer incidents of domestic violence (79% of sample), home-visited mothers had significantly fewer child maltreatment reports during the 15-year period than mothers not receiving the longer-term intervention (P =.01). However, this intervention did not significantly reduce child maltreatment among mothers reporting more than 28 incidents of domestic violence (21% of sample). CONCLUSIONS: The presence of domestic violence may limit the effectiveness of interventions to reduce incidence of child abuse and neglect. JAMA. 2000;284:1385-1391.

Child Abuse↗

PubMed2000

Forms facilitating primary care documentation.

Documentation is a time-consuming but vital component of patient care. As health care providers function under increasing time constraints, well-designed forms can help simplify and improve the documentation process. Patient record forms can help clinicians identify essential points of the history and physical examination and can provide anticipatory guidance. One classification system frequently used by primary care providers is the evaluation and management (E/M) code system. E/M codes are a subset of the Current Procedural Terminology codes developed by the American Medical Association to standardize the terminology used to describe medical and surgical services. This article presents one documentation system that primary care providers may find effective in their documentation efforts.

Abstracting and Indexing↗

PubMed2000

Effectiveness of the National Death Index for establishing the vital status of older women in the Australian Longitudinal Study on Women's Health.

OBJECTIVE: To assess the effectiveness of the National Death Index (NDI) in identifying participants in the oldest cohort of the Australian Longitudinal Study on Women's Health (ALSWH) who had died between 1996 and 1998. METHODS: Identifying information for each woman was matched with the NDI using a probabilistic algorithm and clerical review. Differences in full name, date of birth, State of residence and date of last contact were used to assess the probability of a true match. RESULTS: NDI identified 410 matches of death records for 409 women; 386 were categorised as true matches and 23 were doubtful matches. Responses to the follow-up survey confirmed that for six of the doubtful matches the women had died, 16 were alive and the vital status of one woman remained unconfirmed at 30 June 1998. Twelve deaths, known to have occurred before July 1998, were not identified through NDI. The sensitivity of the NDI for identifying known deaths was 95%. Detailed identifying information, particularly the middle name, was important for accurate identification of the vital status. CONCLUSIONS: Using surname, all given names, gender, date of birth, State of residence and age at last contact as matching variables, the NDI was an effective tool for identifying women who had died. IMPLICATIONS: Routinely collected mortality data in the NDI are useful for the practice of epidemiology.

Aged↗

PubMed2000

Vehicle and driver attributes affecting distance from the steering wheel in motor vehicles.

The current study was designed to confirm that female drivers sit closer to the steering wheel than do male drivers and to investigate whether this expected difference in sitting position is attributable to differences in the physical dimensions of men and women. Driver body dimensions and multiple measures of sitting distance from the steering wheel were collected from a sample of 150 men and 150 women. The results confirmed that on average, women sit closer to the steering wheel than men do and that this difference is accounted for by variations in body dimensions, especially height. This result suggests that driver height may provide a good surrogate for sitting distance from the steering wheel when investigating the role of driver position in real-world crash outcomes. The potential applications of this research include change to vehicle design that allows independent adjustment of the relative distance among the driver's seat, the steering wheel, and the floor pedals.

Adolescent↗

PubMed1999

Women drivers' behaviour, socio-demographic characteristics and accidents.

The purpose of this study was to examine factors which affect driving behaviour and accident rates in women in Australia. Two groups of women (aged 18-23 and 45-50 years) participating in the Australian Longitudinal Study on Women's Health, completed a mailed questionnaire on driver behaviour and road accidents. Self reported accident rates in the last 3 years were 1.87 per 100,000 km for the young drivers (n = 1199) and 0.59 per 100,000 km for the mid-age drivers (n = 1564); most accidents involved damage only, not injury. Mean scores for lapses obtained using the Driver Behaviour Questionnaire, were similar in the two age groups and similar to those found in other studies. In contrast, scores for errors and violations for the young women were higher than for the mid-age group and previous reports using the same instruments. Riskier driving behaviour among young women was associated with stress and habitual alcohol consumption. In the mid-age group, poorer driver behaviour scores were related to higher levels of education, feeling rushed, higher habitual alcohol consumption and lower life satisfaction scores. Accident rates in both groups were significantly related to lapses. Women born in non-English speaking countries had significantly higher risk of accidents compared to Australian-born women: relative risk = 3.40, 95% confidence interval (1.93, 5.98) for the young drivers; relative risk = 1.77, 95% confidence interval (1.11, 2.83) for mid-age drivers. These findings support the need for road safety campaigns targeted at young women to reduce dangerous driving practices, such as speeding, 'tail gating' and overtaking on the inside. There is also a need for further research to understand how lifestyle characteristics are associated with higher risk of accidents and to explore factors which might account for the higher risk for women drivers who were born overseas.

Accidents, Traffic↗

PubMed1999

Kaposi's sarcoma-associated herpesvirus-positive primary effusion lymphoma arising in the subarachnoid space.

Primary effusion lymphoma (PEL) is a rare and distinctive type of B-cell non-Hodgkin's lymphoma (NHL) that occurs primarily, although not exclusively, in patients with AIDS. It usually develops as a lymphomatous effusion in the absence of a tumor mass, characteristically contains the Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8), usually also contains the Epstein-Barr virus (EBV), displays a characteristic cytomorphology bridging immunoblastic and anaplastic large cell lymphoma, often expresses an indeterminate immunophenotype, and a B-cell genotype. Thus far, PEL has been limited almost entirely to the pleural, peritoneal, and pericardial cavities. We describe a NHL occurring in a gay man with AIDS that is typical of PEL in that it arose in a body cavity or space without an associated tumor mass, displays the cytomorphology typical of PEL, is a clonal B-cell neoplasm, and contains KSHV as well as EBV. This case is singularly distinctive in that it is the first case of PEL reported to arise in the subarachnoid space. This unique case further supports the strong association between KSHV and malignant lymphoma arising in body cavities and growing as an effusion.

Adult↗

PubMed1999

Acoustically stimulated transient power scattering explains enhanced detection of the very low velocities in myocardial capillaries by power Doppler imaging: an in vitro study.

BACKGROUND: Although enhanced detection of myocardial perfusion signals by power Doppler imaging during contrast echocardiography has been noted, flow velocities in the coronary microvasculature should generally be below the threshold for Doppler motion detection. It has been suggested that in this situation nonlinear scattering related to acoustically stimulated microsphere oscillation or destruction may be responsible for the detected Doppler shift. METHODS AND RESULTS: This study examined the behavior of MRX 115 (ImaRx Pharmaceuticals) microbubbles during harmonic and nonharmonic power Doppler imaging at varying power outputs (mechanical indexes 0. 3, 0.5, 0.7, and 0.9) in a perfusion tube model under zero-flow conditions. Boluses of MRX 115 0.5-mL suspension were introduced into the model, and flow was halted during each imaging period. Once power Doppler imaging was implemented, a signal was detected as unique sparkling color pixels corresponding to individual bubble destruction events, even in the absence of contrast movement. This phenomenon continued until all contrast bubbles disappeared from the region subjected to power Doppler imaging, usually within 35 to 40 seconds. Off-line videointensity measurements showed that initial power Doppler signal intensity and maximum signal decay rates increased parallel to increasing power output and were substantially greater for nonharmonic than for harmonic imaging modes. CONCLUSION: This relationship between signal intensity and decay rate and acoustic power output suggests that transient scattering related to bubble destruction is responsible for generation of the power Doppler signal in the absence of flow. This would explain the enhanced detection of the very low velocity flows in the myocardial capillaries by power Doppler contrast imaging.

Blood Flow Velocity↗

PubMed1999

The effect of decreasing digital image resolution on teledermatology diagnosis.

OBJECTIVE: To determine the effect of degraded digital image resolution (as viewed on a monitor) on the accuracy and confidence of dermatologic interpretation. MATERIALS AND METHODS: Eight dermatologists interpreted 180 clinical cases divided into three Logical Competitor Sets (LCS) (pigmented lesions, non-pigmented lesions, and inflammatory dermatoses). Each case was digitized at three different resolutions. The images were randomized and divided into (9) 60-image sessions. The physicians were completely blinded concerning the image resolution. After 60 seconds per image, the viewer recorded a diagnosis and level of confidence. The resultant ROC curves compared the effect of LCS, level of clinical difficulty, and resolution of the digital image. One-way analysis of variance (ANOVA) compared the curves. RESULTS: The areas beneath the ROC curves did not demonstrate any consistently significant difference between the digital image resolutions for all LCS and levels of difficulty. The only significant effect observed was amongst pigmented lesions (LCS-A) where the ROC curve area was significantly smaller in the easy images at high resolution compared to low and medium resolutions. For all other ROC curve comparisons within LCS-A, at all other levels of difficulty, as well as within the other LCS at all levels of difficulty, none of the differences was significant. CONCLUSION: A 720 x 500 pixel image can be considered equivalent to a 1490 x 1000 pixel image for most store-and-forward teledermatology consultations.

Analysis of Variance↗

PubMed1999

Measurement of dyspnea in patients treated with mechanical ventilation.

BACKGROUND: Dyspnea, or difficult breathing, is common in patients receiving mechanical ventilation; however, dyspnea is not routinely or systematically measured. OBJECTIVE: The primary purpose of this methodological study was to evaluate the test-retest reliability of 5 dyspnea rating scales and the criterion validity of 4 dyspnea rating scales in patients receiving mechanical ventilation. The secondary purpose was to examine the correlations between each of these 5 rating scales and physiological measures of respiratory function. METHODS: The convenience sample consisted of 28 patients on mechanical ventilation during their hospitalization in the intensive care units of a large, inner-city hospital. Patients rated their dyspnea twice at 30-minute intervals on the visual analogue scale, the vertical analogue dyspnea scale, the modified Borg scale, the numerical scale, and the faces scale. Test-retest reliability was computed by using the intraclass correlation coefficient. Criterion validity was evaluated by using the Spearman rank-order correlation coefficient. RESULTS: The 5 rating scales had acceptable test-retest reliabilities, with intraclass correlation coefficients ranging from 0.81 to 0.97. Criterion validity of the 4 scales also was acceptable, with Spearman rank-order correlation coefficients from 0.76 to 0.96. The rating scales were not correlated with most of the physiological variables. At least half of the patients reported moderate to severe dyspnea. CONCLUSION: The scales showed acceptable reliability and validity, and they will be useful in quantifying dyspnea experienced by patients receiving mechanical ventilation. Further work is needed to evaluate the extent and the severity of dyspnea in such patients in order to evaluate the effectiveness of interventions.

Adult↗

PubMed1998

Long-term effects of nurse home visitation on children's criminal and antisocial behavior: 15-year follow-up of a randomized controlled trial.

CONTEXT: A program of home visitation by nurses has been shown to affect the rates of maternal welfare dependence, criminality, problems due to use of substances, and child abuse and neglect. However, the long-term effects of this program on children's antisocial behavior have not been examined. OBJECTIVE: To examine the long-term effects of a program of prenatal and early childhood home visitation by nurses on children's antisocial behavior. DESIGN: Fifteen-year follow-up of a randomized trial. Interviews were conducted with the adolescents and their biological mothers or custodial parents. SETTING: Semirural community in New York. PARTICIPANTS: Between April 1978 and September 1980, 500 consecutive pregnant women with no previous live births were recruited, and 400 were enrolled. A total of 315 adolescent offspring participated in a follow-up study when they were 15 years old; 280 (89%) were born to white mothers, 195 (62%) to unmarried mothers, 151 (48%) to mothers younger than 19 years, and 186 (59%) to mothers from households of low socioeconomic status at the time of registration during pregnancy. INTERVENTION: Families in the groups that received home visits had an average of 9 (range, 0-16) home visits during pregnancy and 23 (range, 0-59) home visits from birth through the child's second birthday. The control groups received standard prenatal and well-child care in a clinic. MAIN OUTCOME MEASURES: Children's self-reports of running away, arrests, convictions, being sentenced to youth corrections, initiation of sexual intercourse, number of sex partners, and use of illegal substances; school records of suspensions; teachers' reports of children's disruptive behavior in school; and parents' reports of the children's arrests and behavioral problems related to the children's use of alcohol and other drugs. RESULTS: Adolescents born to women who received nurse visits during pregnancy and postnatally and who were unmarried and from households of low socioeconomic status (risk factors for antisocial behavior), in contrast with those in the comparison groups, reported fewer instances (incidence) of running away (0.24 vs 0.60; P = .003), fewer arrests (0.20 vs 0.45; P = .03), fewer convictions and violations of probation (0.09 vs 0.47; P<.001), fewer lifetime sex partners (0.92 vs 2.48; P= .003), fewer cigarettes smoked per day (1.50 vs 2.50; P= .10), and fewer days having consumed alcohol in the last 6 months (1.09 vs 2.49; P = .03). Parents of nurse-visited children reported that their children had fewer behavioral problems related to use of alcohol and other drugs (0.15 vs 0.34; P = .08). There were no program effects on other behavioral problems. CONCLUSIONS: This program of prenatal and early childhood home visitation by nurses can reduce reported serious antisocial behavior and emergent use of substances on the part of adolescents born into high-risk families.

Adolescent↗