Search PubMed⌕ Search

Biomedical subjects

W M Klein

Publications and source records attributed to W M Klein.

10 recordsLinked to original sources
PubMed2003

MR angiography of the lower extremities with a moving-bed infusion-tracking technique.

PURPOSE: To assess the value of MR angiography (MRA) with automatic table movement in a consecutive series of patients with peripheral arterial disease. METHODS: Seventy-two patients underwent both conventional angiography (CA) and MRA for peripheral arterial occlusive disease. Both techniques were scored in a masked way. Consensus scoring for CA was compared with MRA scoring per observer. If there was a discrepancy in scoring of a segment on MRA and CA, the images were reviewed and a consensus arrived at. RESULTS: Observer A found 7.4% and observer B found 6.5% of the segments could not be analyzed on MRA. Observer A scored 11.4% dissimilar on MRA and CA, observer B 15.2%. In the aortoiliac arteries, this was mainly caused by stents and overestimation of stenoses; in the crural arteries it resulted from underestimation of the stenoses on MRA. Overall sensitivity and specificity for the aortoiliac, femoropopliteal and crural vessels were respectively 90% and 91%, 90% and 96%, 59% and 96% for observer A, and 85% and 91%, 84% and 89%, 68% and 85% for observer B. CONCLUSION: Although MRA of the lower extremities is a promising technique, improvements still need to be made. In particular, MRA below the knee is suboptimal for clinical use.

Adult↗
PubMed2001

Communicating breast cancer risks to women using different formats.

Using a pre-post test design with a baseline, laboratory, and a 6-month follow-up, we communicated women's objective breast cancer risks, based on the Gail Model, using two formats: (a) range of risks (e.g., risk of breast cancer can be as low as 1% and as high as 5%); and (b) as a point estimate (e.g., your risk of breast cancer is 3%). We examined how these presentations individually and jointly affected women's perceived lifetime breast cancer risks. Overall, providing risk estimates either as a range of risks or as a point estimate lowered women's perceived lifetime risks compared with women who did not get information presented this way shortly after receipt of this information relative to baseline. At the 6-month follow-up, perceptions of lifetime risks generally returned to their baseline values. Overall, women viewed their risk feedback, whether presented as a point estimate or as a range of risks, as equally credible, trustworthy, accurate, and personally relevant. These results suggest that women evaluate risk feedback containing either point estimates or range of risks as equally acceptable. Both formats lead to short-term reductions in perceived risk (i.e., greater accuracy).

Adult↗
PubMed1997

Objective standards are not enough: affective, self-evaluative, and behavioral responses to social comparison information.

Three studies examined affective, self-evaluative, and behavioral responses to objective and social comparison information. In the first study, 437 male and female college undergraduates imagined they had a 30% or 60% risk of experiencing a negative event and that the average person's risk was higher or lower. All types of responses were sensitive to relative but not absolute risk. In the second study, 60 male and female college undergraduates learned that they scored 40% or 60% on a task and that this score was above or below average. Subsequent behaviors whose outcomes depended largely on objective ability still reflected attention to relative standing. This effect of comparative feedback was shown to be mediated by changes in self-evaluation. A third, follow-up study demonstrated that attention to comparative feedback (in the context of objective information) hinges on its desirability. Implications for social comparison theory are discussed.

Adult↗
PubMed1997

Psychosocial barriers to health promotion in an American Indian population.

Northern Plains Indians (N = 200) completed the Indian Specific Health Risk Appraisal and measures assessing beliefs about risk factors and personal risk. Participants rated personal risk optimistically, judged their risk factor standing as superior to that of their peers, and neglected to consider risk factor standing when appraising personal risk. Moreover, participants were often not improving their standing on risk factors they considered relevant to their health. Such biases in health beliefs may prevent health interventions from being successful.

Adolescent↗
PubMed1996

Amplification of AKT2 in human pancreatic cells and inhibition of AKT2 expression and tumorigenicity by antisense RNA.

We previously demonstrated that the putative oncogene AKT2 is amplified and overexpressed in some human ovarian carcinomas. We have now identified amplification of AKT2 in approximately 10% of pancreatic carcinomas (2 of 18 cell lines and 1 of 10 primary tumor specimens). The two cell lines with altered AKT2 (PANC1 and ASPC1) exhibited 30-fold and 50-fold amplification of AKT2, respectively, and highly elevated levels of AKT2 RNA and protein. PANC1 cells were transfected with antisense AKT2, and several clones were established after G418 selection. The expression of AKT2 protein in these clones was greatly decreased by the antisense RNA. Furthermore, tumorigenicity in nude mice was markedly reduced in PANC1 cells expressing antisense AKT2 RNA. To examine further whether overexpression of AKT2 plays a significant role in pancreatic tumorigenesis, PANC1 cells and ASPC1 cells, as well as pancreatic carcinoma cells that do not overexpress AKT2 (COLO 357), were transfected with antisense AKT2, and their growth and invasiveness were characterized by a rat tracheal xenotransplant assay. ASPC1 and PANC1 cells expressing antisense AKT2 RNA remained confined to the tracheal lumen, whereas the respective parental cells invaded the tracheal wall. In contrast, no difference was seen in the growth pattern between parental and antisense-treated COLO 357 cells. These data suggest that overexpression of AKT2 contributes to the malignant phenotype of a subset of human ductal pancreatic cancers.

Animals↗
PubMed1995

High frequency of inactivating mutations in the neurofibromatosis type 2 gene (NF2) in primary malignant mesotheliomas.

Malignant mesotheliomas (MMs) are aggressive tumors that develop most frequently in the pleura of patients exposed to asbestos. In contrast to many other cancers, relatively few molecular alterations have been described in MMs. The most frequent numerical cytogenetic abnormality in MMs is loss of chromosome 22. The neurofibromatosis type 2 gene (NF2) is a tumor suppressor gene assigned to chromosome 22q which plays an important role in the development of familial and spontaneous tumors of neuroectodermal origin. Although MMs have a different histogenic derivation, the frequent abnormalities of chromosome 22 warranted an investigation of the NF2 gene in these tumors. Both cDNAs from 15 MM cell lines and genomic DNAs from 7 matched primary tumors were analyzed for mutations within the NF2 coding region. NF2 mutations predicting either interstitial in-frame deletions or truncation of the NF2-encoded protein (merlin) were detected in eight cell lines (53%), six of which were confirmed in primary tumor DNAs. In two samples that showed NF2 gene transcript alterations, no genomic DNA mutations were detected, suggesting that aberrant splicing may constitute an additional mechanism for merlin inactivation. These findings implicate NF2 in the oncogenesis of primary MMs and provide evidence that this gene can be involved in the development of tumors other than nervous system neoplasms characteristic of the NF2 disorder. In addition, unlike NF2-related tumors, MM derives from the mesoderm; malignancies of this origin have not previously been associated with frequent alterations of the NF2 gene.

Base Sequence↗
PubMed1995

Resistance of personal risk perceptions to debiasing interventions.

The tendency to believe that one's own risk is less than that of others may reduce interest in health-protective behaviors. This article describes 4 attempts to reduce such optimistic biases. In Study 1, New Jersey residents (N = 222) were provided with lists of risk factors for several health problems. This manipulation was strengthened in Study 2 by presenting risk factors in such a way that participants (164 undergraduates) might see their own standing as inferior to that of others. In Study 3, risk factors were presented one at a time, and participants (190 undergraduates) incorporated them into a mental image of a high-risk individual. Finally, 374 undergraduates in Study 4 generated lists of personal attributes that they believed increased their risk. Optimistic biases were found in each study, but none of the manipulations reduced these biases consistently. In contrast, conditions using opposite manipulations often exacerbated the biases.

Accidents, Traffic↗
PubMed1994

p16 alterations and deletion mapping of 9p21-p22 in malignant mesothelioma.

To determine whether p16 is altered in human malignant mesothelioma (MM), molecular analysis of multiple 9p loci was performed on 40 cell lines and 23 primary tumors from 42 MM patients. We identified homozygous deletions of p16 in 34 (85%) cell lines and a point mutation in 1 line. Down-regulation of p16 was observed in 4 of the remaining cell lines, 1 of which displayed a DNA rearrangement of p16. Homozygous deletions of p16 were identified in 5 of 23 (22%) primary tumors; no mutations or rearrangements were found in these specimens. Four cell lines displayed a single homozygous deletion proximal to or distal to p16; 4 others had 2 nonoverlapping deletions, one involving p16 and the other involving a region proximal to this locus. These data indicate that alterations of p16 are a common occurrence in MM cell lines and, to a lesser extent, in primary tumors. Furthermore, deletions of 9p21-p22 outside of the p16 locus may reflect the involvement of other putative tumor suppressor genes that could also contribute to the pathogenesis of some MMs.

Base Sequence↗
PubMed1980

A simple office spirometer for the pediatrician.

A comparative study of a new, simple, pneumatic, direct-recording office spirometer versus a long-accepted, water-sealed, water-filled spirometer was performed on 103 patients ranging from four to 20 years of age. Good correlation between the two spirometers was seen through a wide range of values for forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and forced expiratory flow during 25% to 75% of forced vital capacity and FEV1/FVC.

Adolescent↗