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Biomedical subjects

J Olson

Publications and source records attributed to J Olson.

At least 19 recordsLinked to original sources
PubMed2005

Packing fractions and maximum angles of stability of granular materials.

In two-dimensional rotating drum experiments, we find two separate influences of the packing fraction of a granular heap on its stability. For a fixed grain shape, the stability increases with packing fraction. However, in determining the relative stability of different grain shapes, those with the lowest average packing fractions tend to form the most stable heaps. We also show that only the configuration close to the surface of the pile figures prominently.

Journal Article↗
PubMed2003

A national retinal screening programme for diabetes in Scotland.

The Health Technology Board Scotland (HTBS) have issued recommendations for eye screening in patients with diabetes. These are based on evidence-based clinical studies. Evidence-based studies do not answer all the practical issues, and some conclusions have thus been extrapolated from the known evidence base. Other factors such as patient issues, organizational issues and cost effectiveness have also been incorporated into the recommendations. HTBS recommend single-field digital retinal photography. Retinal photography best addresses the issues of adequate sensitivity and accountable quality assurance. Non-mydriatic photography is recommended, followed by immediate use of dilating eye drops if it is unsuccessful, followed by slit-lamp examination if both of these approaches fail. An independent grading scheme has been established, which is similar to the 'Global', and compatible with the National Screening Committee (NSC) grading scheme. The rationale for these recommendations, and debate behind some of the decisions, is laid out in this article.

Diabetic Retinopathy↗
PubMed2003

The value of digital imaging in diabetic retinopathy.

OBJECTIVES: To assess the performance of digital imaging, compared with other modalities, in screening for and monitoring the development of diabetic retinopathy. DESIGN: All imaging was acquired at a hospital assessment clinic. Subsequently, study optometrists examined the patients in their own premises. A subset of patients also had fluorescein angiography performed every 6 months. SETTING: Research clinic at the hospital eye clinic and optometrists' own premises. PARTICIPANTS: Study comprised 103 patients who had type 1 diabetes mellitus, 481 had type 2 diabetes mellitus and two had secondary diabetes mellitus; 157 (26.8%) had some form of retinopathy ('any') and 58 (9.9%) had referable retinopathy. INTERVENTIONS: A repeat assessment was carried out of all patients 1 year after their initial assessment. Patients who had more severe forms of retinopathy were monitored more frequently for evidence of progression. MAIN OUTCOME MEASURES: Detection of retinopathy, progression of retinopathy and determination of when treatment is required. RESULTS: Manual grading of 35-mm colour slides produced the highest sensitivity and specificity figures, with optometrist examination recording most false negatives. Manual and automated analysis of digital images had intermediate sensitivity. Both manual grading of 35-mm colour slides and digital images gave sensitivities of over 90% with few false positives. Digital imaging produced 50% fewer ungradable images than colour slides. This part of the study was limited as patients with the more severe levels of retinopathy opted for treatment. There was an increase in the number of microaneurysms in those patients who developed from mild to moderate. There was no difference between the turnover rate of either new or regressed microaneurysms for patients with mild or with sight-threatening retinopathy. It was not possible in this study to ascertain whether digital imaging systems determine when treatment is warranted. CONCLUSIONS: In the context of a national screening programme for referable retinopathy, digital imaging is an effective method. In addition, technical failure rates are lower with digital imaging than conventional photography. Digital imaging is also a more sensitive technique than slit-lamp examination by optometrists. Automated grading can improve efficiency by correctly identifying just under half the population as having no retinopathy. Recommendations for future research include: investigating whether the nasal field is required for grading; a large screening programme is required to ascertain if automated grading can safely perform as a first-level grader; if colour improves the performance of grading digital images; investigating methods to ensure effective uptake in a diabetic retinopathy screening programme.

Diabetes Mellitus, Type 1↗
PubMed2001

Multilocation trial of ceftiofur for treatment of postpartum cows with fever.

OBJECTIVE: To evaluate the effect of ceftiofur for treatment of postpartum cows with fever. DESIGN: Multilocation randomized complete block design trial. ANIMALS: 330 cows. PROCEDURE: Cows with rectal temperature > or = 39.5 C (103.1 F) during the first 10 postpartum days were randomly assigned to a treatment (ceftiofur; 1 mg/kg [0.45 mg/lb] of body weight daily for 3 days) or untreated control group. Cure (no additional or alternative antimicrobial treatment used, rectal temperature < 39.5 C, and no other concurrent clinical signs of disease when evaluated at 9 or 10 days after enrollment), milk production, and rectal temperature were evaluated. RESULTS: Ceftiofur-treated cows were significantly more likely to be cured than control cows (56.0 vs 28.9%, respectively), with an odds ratio of 3.14 when vaginal discharge (a factor with moderate interaction with treatment) was present at enrollment. Among cows that had an abnormal calving (a significant interaction factor), treated cows had first milking yield 2.27 kg (5 lb) greater than control cows. Treated cows had a significantly greater reduction in rectal temperature (1.19 C [2.14 Fl), compared with control cows (1.04 C [1.87 F]). CONCLUSIONS AND CLINICAL RELEVANCE: Parenteral administration of ceftiofur significantly improved cure rate, milk yield, and rectal temperature in postpartum cows with fever and vaginal discharge or dystocia. These findings provide information to determine appropriate treatment for postpartum cows, which for years has been debated in the dairy industry.

Animals↗
PubMed2001

Intake of dioxins and related compounds from food in the U.S. population.

The first U.S. nationwide food sampling with measurement of dioxins, dibenzofurans, and coplanar, mono-ortho and di-ortho polychlorinated biphenyls (PCBs) is reported in this study. Twelve separate analyses were conducted on 110 food samples divided into pooled lots by category. The samples were purchased in 1995 in supermarkets in Atlanta, GA, Binghamton, NY, Chicago, IL, Louisville, KY, and San Diego, CA. Human milk also was collected to estimate nursing infants' consumption. The food category with highest World Health Organization (WHO) dioxin toxic equivalent (TEQ) concentration was farm-grown freshwater fish fillet with 1.7 pg/g, or parts per trillion (ppt), wet, or whole, weight. The category with the lowest TEQ level was a simulated vegandiet, with 0.09 ppt. TEQ concentrations in ocean fish, beef, chicken, pork, sandwich meat, eggs, cheese, and ice cream, as well as human milk, were in the range O.33 to 0.51 ppt, wet weight. In whole dairy milk TEQ was 0.16 ppt, and in butter 1.1 ppt. Mean daily intake of TEQ for U.S. breast-fed infants during the first year of life was estimated at 42 pg/kg body weight. For children aged 1-11 yr the estimated daily TEQ intake was 6.2 pg/kg body weight. For males and females aged 12-19 yr, the estimated TEQ intake was 3.5 and 2.7 pg/kg body weight, respectively. For adult men and women aged 20-79 yr, estimated mean daily TEQ intakes were 2.4 and 2.2 pg/kg body weight, respectively. Estimated mean daily intake of TEQ declined with age to a low of 1.9 pg/kg body weight at age 80 yr and older. For all ages except 80 yr and over, estimates were higher for males than females. For adults, dioxins, dibenzofurans, and PCBs contributed 42%, 30%, and 28% of dietary TEQ intake, respectively. DDE was also analyzed in the pooled food samples.

Adolescent↗
PubMed2001

Clinical investigation of a true color scanning laser ophthalmoscope.

OBJECTIVE: To show true color scanning laser ophthalmoscope (SLO) images produced by simultaneously imaging the retina with red, green, and blue lasers. METHODS: Low-power red, green, and blue lasers were combined using fiber optics. By rapidly pulsing the lasers, each point on the fundus is illuminated by the 3 colors in quick succession, with the total power level being similar to that from a single laser. The reflected light is then decoded to extract the red, green, and blue color information and the true color fundus image is displayed live on a computer monitor. RESULTS: Comparison was made between the color SLO images from 5 patients and their digitized fundus photographs. The background fundus and retinal vasculature showed a similar appearance. The SLO gave better quality information in patients with ocular histoplasmosis, macular dystrophy, and optic disc drusen. By operating the color SLO in the indirect mode, macular edema could be clearly seen as lines and ridges surrounding the fovea. CONCLUSION: The color SLO offers all the advantages of the present commercially available monochromatic device, with the added advantage of true color representation of the fundus without increasing either imaging time or the level of exposure.

Adult↗
PubMed2001

Synthesis of quinolinyl chalcones and evaluation of their antimalarial activity.

Quinolinyl chalcones were synthesized and evaluated for their inhibition of the Plasmodium falciparum cystein protease falcipain and their activity against cultured P. falciparum parasites. They were also tested for in vivo efficacy in a rodent P. berghei model. Their activity against falcipain and as antimalarials was moderate, but antimalarial activity was probably not due to the inhibition of falcipain and may follow a different mechanism. 1-(2,4-Dichlorophenyl)-3-[3-(2-chloro-6,7-dimethoxiquinolinyl)]-2-propen-1-one 3j was the most promising compound among those here reported (IC50 19.0 microM).

Animals↗
PubMed2001

The presence of Nipah virus in respiratory secretions and urine of patients during an outbreak of Nipah virus encephalitis in Malaysia.

OBJECTIVES: To study the excretion of Nipah virus in the upper respiratory secretions and urine of infected patients in relation to other clinical features. METHODS: Isolation of Nipah virus from the respiratory secretions and urine was made in Vero cells and identified by indirect immunofluorescence assay using anti-Hendra specific hyperimmune mouse ascitic fluid and FITC-conjugated goat anti-mouse IgG. RESULTS: During the peak outbreak of Nipah virus encephalitis in Malaysia, Nipah virus was isolated from the upper respiratory secretions and urine in eight of 20 patients who were virologically and/or serologically confirmed to be infected with the virus. From these eight patients, Nipah virus was isolated from six throat swab specimens, three urine specimens and only one nasal swab specimen. The positive virus isolation rate was related to the collection of these specimens during the early phase of the illness (P = 0.068). The presence of serum anti-Nipah specific IgM appeared to reduce the chance of isolating the virus (P = 0.049). There was no significant difference in the isolation rate with respect to the age, gender, ethnic group and clinical features associated with grave prognosis and mortality outcome of the patients. CONCLUSION: This study shows that it is possible to be infected from secretions of infected patients, but epidemiological survey on close contacts so far did not suggest that human-to-human transmission is common.

Adolescent↗
PubMed2001

Sinonasal undifferentiated carcinoma with orbital invasion: report of three cases.

PURPOSE: To report three patients with sinonasal undifferentiated carcinoma (SNUC) that invaded the orbit. METHODS: Retrospective small case series. The clinical, radiographic, and pathologic features of three patients with SNUC were reviewed. RESULTS: Three patients with SNUC that invaded the orbit were evaluated. A biopsy was performed on the tumors, which were composed of small, hyperchromatic cells with numerous mitoses and areas of necrosis. Immunohistochemical staining was positive for cytokeratins AE1.3, epithelial membrane antigen, and neuron-specific enolase in all three tumors. Electron microscopic examination showed absence of neurosecretory granules and presence of basement membrane production. Two patients were treated with surgical resection and postoperative chemotherapy and/or radiation. One patient was treated with preoperative radiation and chemotherapy. CONCLUSIONS: Sinonasal undifferentiated carcinoma is a high-grade tumor that arises in the nasal and paranasal sinuses and may invade the orbit. SNUC should be distinguished from other small, round, blue cell tumors, in particular, esthesioneuroblastoma.

Adult↗
PubMed2001

Evaluation of missed diagnoses for patients admitted from the emergency department.

OBJECTIVE: To define a quality assurance instrument to evaluate errors in diagnostic processes made by physicians in the emergency department (ED). METHODS: This was a retrospective clinical investigation of inpatient ED records. Over a six-year period, 5,000 medical records of admitted patients were randomly selected for evaluation. Each record was initially examined by one of five physician evaluators. If the primary ED diagnosis differed from the primary discharge diagnosis, the ED record was inspected to determine reasons for the misdiagnosis. The authors considered several aspects of the diagnostic process, including patient history, tests ordered, interpretation of clinical data, choice and performance of procedures, injury pattern recognition, reasoning, and evaluation. Records that demonstrated errors in the diagnostic process were reevaluated for the same diagnostic process errors by a sixth physician. Disagreements regarding suspected errors in the diagnostic process were settled by discussion. Finally, to determine potential medical consequences of the misdiagnosis, one individual reviewed the complete medical records of patients whose ED medical records were scored with errors by both evaluators. Interevaluator reliability was assessed using Cochran's Q-test with a selected series of medical records. RESULTS: Twenty-eight records (0.6%) were found to contain one or more errors in the diagnostic process that contributed to misdiagnosis. For these patients appropriate diagnosis was not made until one to 16 days after admission. Three patients of 18 whose records were available for detailed review may have suffered complications that resulted, in part, from the delay in diagnosis and subsequent treatment. Significant interevaluator reliability for identification of errors in the diagnostic process was obtained (p > 0.1). CONCLUSIONS: A two-tiered evaluation of ED records selected by inconsistent initial and final diagnoses can be used reliably to screen for errors in the diagnostic process made by emergency physicians (EPs). The rate of physician error contributing to a misdiagnosis is very low, suggesting that EPs are delivering quality patient care.

Diagnostic Errors↗
PubMed2001

Parish nurses influencing determinants of health.

How are the concepts health, health promotion, faith community, and health determinants connected? How can a nurse draw on the unique features of a faith community to promote health? In this article, we explore the relations among these concepts and consider the answers to these questions. Parish nurses provide a concrete example of the interactions among these concepts. They are often hired by faith communities to intentionally promote health within and beyond the faith community. Increasingly, faith communities are being used as settings for health promotion interventions. We describe examples of how a parish nurse can influence 2 determinants of health: social support and healthy child development.

Adult↗
PubMed2001

Multiple maltreatment, attribution of blame, and adjustment among adolescents.

The study examined the predictive utility of blame attributions for maltreatment. Integrating theory and research on blame attribution, it was predicted that self-blame would mediate or moderate internalizing problems, whereas other-blame would mediate or moderate externalizing problems. Mediator and moderator models were tested separately. Adolescents (N = 160, ages 11-17 years) were randomly selected from the open caseload of a child protection agency. Participants made global maltreatment severity ratings for each of physical abuse, psychological abuse, neglect. sexual abuse, and exposure to family violence. Participants also completed the Attribution for Maltreatment Interview (AFMI), a structured clinical interview that assessed self- and perpetrator blame for each type of maltreatment they experienced. The AFMI yielded five subscales: self-blaming cognition, self-blaming affect, self-excusing. perpetrator blame, and perpetrator excusing. Caretaker-reported (Child Behavior Checklist) and self-reported (Youth Self Report) internalizing and externalizing were the adjustment criteria. Controlling for maltreatment severity, the AFMI subscales explained significant variance in self-reported adjustment. Self-blaming affect was the most potent attribution, particularly among females. Attributions mediated maltreatment severity for self-reported adjustment but moderated it for caretaker-reported adjustment. The sophistication and relevance of blame attributions to adjustment are discussed, and implications for research and clinical practice are identified.

Adaptation, Psychological↗
PubMed2001

All prompts are created equal, but some prompts are more equal than others.

Scores assigned to college placement essays by a computer program (PEG) showed high agreement with the evaluations of human readers (r =.82). Further, both types of graders tended to assign higher or lower scores to essays written about particular topics. Content analyses by a second program (MCCA) indicated that themes in essays varied in terms of emphasis on "analytic," "emotional," or "practical" dimensions. Human and machine readers tended to give higher scores for analytic and practical themes, and lower scores for those involving emotion. The ranks of mean prompt-related grades were concordant with the ranks of mean analytic and practical content across topics. Such findings call for the refined standardization of prompts for future testing, and the need for care in the evaluation of existing essays.

Adolescent↗
PubMed2000

Automated crystal mounting and data collection for protein crystallography.

To increase the efficiency of diffraction data collection for protein crystallographic studies, an automated system designed to store frozen protein crystals, mount them sequentially, align them to the X-ray beam, collect complete data sets, and return the crystals to storage has been developed. Advances in X-ray data collection technology including more brilliant X-ray sources, improved focusing optics, and faster-readout detectors have reduced diffraction data acquisition times from days to hours at a typical protein crystallography laboratory [1,2]. In addition, the number of high-brilliance synchrotron X-ray beam lines dedicated to macromolecular crystallography has increased significantly, and data collection times at these facilities can be routinely less than an hour per crystal. Because the number of protein crystals that may be collected in a 24 hr period has substantially increased, unattended X-ray data acquisition, including automated crystal mounting and alignment, is a desirable goal for protein crystallography. The ability to complete X-ray data collection more efficiently should impact a number of fields, including the emerging structural genomics field [3], structure-directed drug design, and the newly developed screening by X-ray crystallography [4], as well as small molecule applications.

Crystallization↗
PubMed2000

Review of the Bethesda System atlas does not improve reproducibility or accuracy in the classification of atypical squamous cells of undetermined significance smears.

BACKGROUND: The Bethesda System (TBS) and its accompanying atlas were developed to promote uniform diagnosis and reporting of cervical and vaginal cytology, especially with respect to borderline abnormal smears. The authors assessed whether group study of TBS atlas improves the reproducibility and accuracy of the cytopathologic diagnosis of equivocal Papanicolaou smears. METHODS: One hundred "atypical" smears were divided into pretest and posttest sets containing equal numbers of negative, atypical squamous cells of undetermined significance (ASCUS), and squamous intraepithelial lesion (SIL) diagnoses based on a five-member panel review. Two comparable teams of four pathologists from George Washington University Medical Center (Washington, DC) and Kaiser Permanente (Portland, OR), each comprised of two more experienced cytopathologists and two less experienced pathologists, independently reviewed the 50 pretest slides and classified the slides according to TBS as negative, ASCUS, or SIL. The teams then conducted group study sessions using TBS atlas. After the review, the pathologists independently classified the 50 posttest slides in a similar manner. RESULTS: Pretest, pair-wise interobserver agreement ranged from 30% to 66% compared with 34-62% for posttest agreement. Absolute percent agreement of reviewers' diagnoses with a previously developed consensus diagnosis based on opinions of a five-expert panel (cytopathologic certainty scale) ranged from 44% to 62% for the pretest set and from 40% to 60% for the posttest set. Comparison of the detection of oncogenic human papilloma virus (HPV) DNA by hybrid capture tube test with smears classified as negative, ASCUS, or SIL revealed that seven of eight reviewers did not demonstrate a stronger association between HPV detection and cytologic diagnosis in the posttest set. CONCLUSIONS: Review of TBS atlas by itself does not appear to improve the reproducibility or accuracy of cytologic diagnoses. The lack of improvement was similar among the pathologists involved regardless of experience level or whether they had a close working relation. Cancer (Cancer Cytopathol)

Cervix Uteri↗
PubMed2000

Nipah virus: a recently emergent deadly paramyxovirus.

A paramyxovirus virus termed Nipah virus has been identified as the etiologic agent of an outbreak of severe encephalitis in people with close contact exposure to pigs in Malaysia and Singapore. The outbreak was first noted in late September 1998 and by mid-June 1999, more than 265 encephalitis cases, including 105 deaths, had been reported in Malaysia, and 11 cases of encephalitis or respiratory illness with one death had been reported in Singapore. Electron microscopic, serologic, and genetic studies indicate that this virus belongs to the family Paramyxoviridae and is most closely related to the recently discovered Hendra virus. We suggest that these two viruses are representative of a new genus within the family Paramyxoviridae. Like Hendra virus, Nipah virus is unusual among the paramyxoviruses in its ability to infect and cause potentially fatal disease in a number of host species, including humans.

Animals↗