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Biomedical subjects

J C Jackson

Publications and source records attributed to J C Jackson.

At least 19 recordsLinked to original sources
PubMed2004

Mammographic image restoration using maximum entropy deconvolution.

An image restoration approach based on a Bayesian maximum entropy method (MEM) has been applied to a radiological image deconvolution problem, that of reduction of geometric blurring in magnification mammography. The aim of the work is to demonstrate an improvement in image spatial resolution in realistic noisy radiological images with no associated penalty in terms of reduction in the signal-to-noise ratio perceived by the observer. Images of the TORMAM mammographic image quality phantom were recorded using the standard magnification settings of 1.8 magnification/fine focus and also at 1.8 magnification/broad focus and 3.0 magnification/fine focus; the latter two arrangements would normally give rise to unacceptable geometric blurring. Measured point-spread functions were used in conjunction with the MEM image processing to de-blur these images. The results are presented as comparative images of phantom test features and as observer scores for the raw and processed images. Visualization of high resolution features and the total image scores for the test phantom were improved by the application of the MEM processing. It is argued that this successful demonstration of image de-blurring in noisy radiological images offers the possibility of weakening the link between focal spot size and geometric blurring in radiology, thus opening up new approaches to system optimization.

Algorithms↗
PubMed2004

Cultural case management of latent tuberculosis infection.

SETTING: The proportion of tuberculosis (TB) among foreign-born individuals in the United States is steadily increasing. Treatment of latent TB infection can prevent future cases of disease, although generally only 60% of patients who start a 6-month regimen of isoniazid complete therapy. OBJECTIVE: Cultural case management--employing case manager cultural mediators who serve patient-defined needs in addition to performing TB control functions--may improve results of testing and treatment in one high-risk group, new refugees. DESIGN: A cultural case management approach was established for finding and treating latent TB infection among three groups of new refugees: from the former Soviet Union (FSU), former Yugoslavia (FY), and Somalia. RESULTS: From July 1999 through December 2000, treatment was offered to 442 refugees, of whom 389 (88%) started and 319 (82%) completed therapy. The completion rate among starters from the FSU was 76%, for those from FY it was 94% and for those from Somalia it was 88%. Among all refugees to whom treatment was offered, 319/442 (72%) completed therapy. CONCLUSION: Cultural case management may be a useful tool for expanding treatment of latent TB infection among foreign-born individuals.

Antitubercular Agents↗
PubMed2001

Cervical cancer screening among Chinese immigrants in Seattle, Washington.

INTRODUCTION: Chinese American women have high rates of invasive cervical cancer, compared to the general population. However, little is known about the Pap testing behavior of ethnic Chinese immigrants. METHODS: We conducted a community-based survey of Chinese immigrants living in Seattle, Washington, during 1999. Two indicators of cervical cancer screening participation were examined: at least one previous Pap smear and Pap testing in the last 2 years. RESULTS: The overall estimated response rate was 64%, and the cooperation rate was 72%. Our study sample for this analysis included 647 women. Nearly one quarter (24%) of the respondents had never had a Pap test, and only 60% had been screened recently. Factors independently associated with cervical cancer screening use included marital status, housing type, and age at immigration. CONCLUSION: Our findings confirm low levels of cervical cancer screening among Chinese immigrants to North America. Culturally and linguistically appropriate Pap testing intervention programs for less acculturated Chinese women should be developed, implemented, and evaluated.

Journal Article↗
PubMed2001

Expression of the INO2 regulatory gene of Saccharomyces cerevisiae is controlled by positive and negative promoter elements and an upstream open reading frame.

The INO2 gene encodes a transcriptional activator of the phospholipid biosynthetic genes of Saccharomyces cerevisiae. Complete derepression of phospholipid biosynthetic gene expression in response to inositol/choline deprivation requires both INO2 and INO4. Ino2p dimerizes with Ino4p to bind the upstream activating sequence (UAS)INO element found in the promoters of the target genes. We have demonstrated previously that transcription from the INO2 promoter is autoregulated 12-fold in a manner identical to that of the target genes. Here, we show that this regulation occurs at the levels of transcription and translation. Transcription accounts for fourfold regulation, whereas translation accounts for an additional threefold regulation. Regulation of transcription requires a UAS(INO) element. Additional promoter elements include an upstream essential sequence (UES) located upstream of the UAS(INO) element and a negative regulatory element in the vicinity of the UAS(INO) element. Regulation of translation is dependent on an upstream open reading frame (uORF) in the INO2 leader. These data support the model that regulatory gene promoters may display unusual organizations and may be subject to multiple levels of regulation. We have shown previously that the UME6 gene positively regulates INO2 expression. Here, we limit the UME6-responsive region of the INO2 promoter to nucleotides -217 to -56.

Amino Acid Sequence↗
PubMed2000

Combinatorial regulation of phospholipid biosynthetic gene expression by the UME6, SIN3 and RPD3 genes.

The Ume6p-Sin3p-Rpd3p complex negatively regulates expression of genes containing a Ume6p binding site. However, these regulatory proteins also function independently to regulate gene expression both negatively and positively. The model system for this combinatorial regulation is the yeast phospholipid biosynthetic pathway. Sin3p negatively regulates the INO1, CHO1, CHO2 and OPI3 genes while Ume6p negatively regulates the INO1 gene and positively regulates the other genes. We have suggested that the positive regulation results from indirect effects on expression of the INO2 transcriptional activator gene. Here, we demonstrate that the effect of Ume6p on INO2 gene expression is also indirect. We also show that Rpd3p is a negative regulator of phospholipid biosynthetic gene expression. The ability of Ume6p, Sin3p and Rpd3p to differentially regulate expression of the phospholipid biosynthetic genes affects phospholipid composition. A sin3 mutant strain lacks detectable levels of phosphatidylethanolamine and elevated levels of phosphatidylcholine (PC) and a rpd3 mutant strain has reduced levels of PC. These alterations in membrane composition suggest that there may exist additional differences in regulation of phospholipid biosynthetic gene expression and that membrane compositions may be coordinated with other biological processes regulated by Ume6p, Sin3p and Rpd3p.

Basic Helix-Loop-Helix Proteins↗
PubMed2000

Gravitational effects on volume distribution in a model of partial and total liquid ventilation.

To estimate regional lung volume during ventilation with liquids (e. g. perfluorochemicals, PFC) we developed a multi-compartment mathematical model of a lung and thorax. The height of the fluid column and the fluid's density determine alveolar pressure (PA). The weight of thoracic contents above any given gravitational plane influences pleural pressure (PPL). Transpulmonary pressure (PTP=PA−PPL) and compliance of the lung and chest wall permit estimation of volumes. The results indicate the lung inflates almost uniformly during total liquid ventilation despite a substantial vertical PA gradient. Inflation uniformity is due to the offsetting vertical PPL gradient created by the added weight of the PFC and sustained by the relative rigidity of the chest wall. During partial liquid ventilation our model indicates that the combination of uniform PA with a large vertical gradient in PPL leads to a vertical PTP gradient and therefore relative over-inflation of the top of the lung. This effect increases with increasing PFC dose and with lung height.

Functional Residual Capacity↗
PubMed2000

Hepatitis B knowledge among Vietnamese immigrants: implications for prevention of hepatocellular carcinoma.

BACKGROUND: Vietnamese have higher liver cancer rates than any other racial/ethnic group in the United States. Approximately 80% of liver cancers are etiologically associated with hepatitis B virus (HBV) infection, which is endemic in Southeast Asia. METHODS: A telephone survey of randomly selected Vietnamese households (n = 75) was conducted during 1998 to examine HBV knowledge among Seattle's Vietnamese community. The questionnaire included items related to the transmission of HBV, the possible sequelae of infection, and disease prevention. RESULTS: The response rate was 70% among reachable and eligible households. Prior to being provided with a description of the disease, two thirds of our respondents had heard of HBV infection. Less than 60% knew that asymptomatic individuals can transmit the disease to others. Most thought that HBV infection can cause liver cancer (63%) and death (80%). However, only a minority knew that infection can be lifelong (38%) and incurable (22%). Finally, 28% had never heard of the HBV vaccine. There were significant associations between knowledge and educational level as well as home ownership. CONCLUSIONS: The findings suggest that Vietnamese immigrants have low levels of knowledge about HBV infection, and indicate a need for targeted educational interventions aimed at reducing HBV-related liver cancer mortality.

Adult↗
PubMed2000

The pediatric intern retreat: 20-year evolution of a continuing investment.

For the past 22 years the interns in pediatrics at the University of Washington and Children's Hospital and Regional Medical Center have been relieved of all clinical duties in order to participate in a five-day retreat. The retreat provides an opportunity for the interns to learn more about their classmates, build stronger bonds, and provide mutual support. This retreat has been supported by the hospital, the department of pediatrics, faculty, fellows, and community physicians. The authors describe the history of the Intern Retreat, present its goals, daily activities, and faculty, and discuss how the retreat is funded and supported by the hospital and the medical community.

Humans↗
PubMed2000

Breast cancer screening among Cambodian American women.

Our aim was to describe and identify factors associated with breast cancer screening among Cambodian American women. We conducted a cross-sectional survey of 1,365 households using bilingual and bicultural interviewers. We found that low proportions of Cambodian American women were up to date on their clinical breast examinations (CBE; 42%) and mammograms (40%). More than 80% of women with female physicians have had at least one prior screening, and 52% have had the tests recently. Women with male Asian American physicians were less likely to have had screening as compared to women with female non-Asian physicians: ever had CBE (odds ratio [OR], 0.26); recent CBE (OR, 0.39); ever had mammogram (OR, 0.36); and recent mammogram (OR, 0.22). Breast cancer screening among Cambodian American women lags behind the general U.S. population. Tailored promotion efforts should address barriers and promote cancer screening by physicians, staff, and organizations serving this population.

Adolescent↗
PubMed1999

Perfluorochemical liquid-enhanced adenoviral vector distribution and expression in lungs of spontaneously breathing rodents.

Perfluorochemical (PFC) liquids have been shown to improve gas exchange and lung compliance in models of lung injury. We reasoned they may also be useful as a vehicle for gene transfer by improving transgene distribution throughout the lung as well as increasing total transgene expression. We have developed a model for PFC liquid use in spontaneously breathing rodents that obviates the need for intubation and ventilation. Intratracheal instillation of the adenoviral vector Adlac-Z resulted in patchy distribution of beta-galactosidase (beta-gal) activity as demonstrated using X-gal histochemistry. In contrast, in rats instilled with Adlac-Z followed by instillation of PFC liquid, more uniformly distributed and increased beta-gal activity was observed. Activity in distal airway and alveolar epithelium was particularly increased. Quantitative measure of beta-gal activity in lung homogenates demonstrated a 3- to 6-fold increase in total activity in lungs of rats receiving Adlac-Z and PFC liquid compared to animals receiving Adlac-Z alone. These studies show that PFC liquids can enhance both the distribution and the total amount of transgene expressed following adenoviral-mediated vector transfer to lungs during spontaneous breathing. Use of PFC liquids may increase the efficacy of gene transfer strategies for treatment of cystic fibrosis and other lung diseases.

Adenoviridae↗
PubMed1999

Bridging cultures through the development of a cervical cancer screening video for Cambodian women in the United States.

BACKGROUND: Southeast Asian women have higher invasive cervical cancer rates than any other U.S. racial/ethnic population subgroup, and their levels of Pap testing do not even approach the year 2000 goals. Video is a particularly useful medium for cancer education in Cambodian refugee communities because of low literacy levels and high rates of VCR ownership. METHODS: The authors produced a motivational Pap-testing video for Cambodian American women. The 18-minute Khmer-language video is entitled "The Preservation of Traditions." Content, with respect to cervical cancer screening barriers and facilitators, was guided by intensive qualitative data collection. Barriers addressed were: beliefs that traditional postpartum practices protect against cervical disease, Cambodians do not get cervical cancer, and screening is unnecessary; fear of cancer as well as surgery; lack of understanding about preventive concepts and familiarity with the Pap test; concerns about embarrassment and pain; and problems with transportation and child care. Facilitators included the availability of female physicians and interpreters. A community coalition of Cambodian women and two community advisors participated in all aspects of the video development and production. Video techniques frequently used in American productions were adapted to the target audience. For example, cultural context was provided, use of biomedical terminology minimized, role modeling emphasized, and testimonial accounts avoided. CONCLUSION: The processes used to translate empirical evidence into meaningful educational messages, and to adapt American behavioral change techniques to Cambodian cultural norms, are generalizable to other less acculturated immigrant groups and cancer education topics.

Cambodia↗
PubMed1999

Cervical cancer screening among Cambodian-American women.

Southeast Asian women have higher invasive cervical cancer incidence rates and lower Pap testing frequencies than most other racial/ethnic groups in the United States. However, there is little information about the cervical cancer screening behavior of Cambodian-American women. Cambodian residents of Seattle were surveyed in person during late 1997 and early 1998. The PRECEDE model was used to guide the development of items that assessed predisposing, reinforcing, and enabling factors associated with cervical cancer screening participation. The estimated overall survey response was 72%. Four hundred thirteen women completed our questionnaire. Approximately one-quarter (24%) of the respondents had never had a Pap test, and over one-half (53%) had not been screened recently. The following variables were positively associated with a history of at least one Pap smear: younger age, greater number of years since immigration, belief about Pap testing for postmenopausal women, prenatal care in the United States, and physician recommendation. Women who believed in karma were less likely to have ever been screened for cervical cancer than those who did not. Six variables independently predicted recent screening: age; beliefs about regular checkups, cervical cancer screening for sexually inactive women, and the prolongation of life; having a female doctor; and a previous physician recommendation for Pap testing. The study findings indicate that culturally specific approaches might be effective in modifying the cervical cancer screening behavior of immigrant women. Programs targeting Cambodian-Americans are likely to be more effective if they are multifaceted and simultaneously address predisposing, reinforcing, and enabling factors.

Adolescent↗
PubMed1998

Heterologously expressed inner lipoyl domain of dihydrolipoyl acetyltransferase inhibits ATP-dependent inactivation of pyruvate dehydrogenase complex. Identification of important amino acid residues.

The activity of the pyruvate dehydrogenase multienzyme complex (PDC), which catalyses the oxidation of pyruvate to acetyl-CoA within the mitochondrion, is diminished in animal models of diabetes. Studies with purified PDC components have suggested that the kinases responsible for inactivating the decarboxylase catalytic subunits of the complex are most efficient in their regulatory role when they are bound to dihydrolipoyl acetyltransferase (E2) subunits, which form the structural core of the complex. We report that the addition of an exogenous E2 subdomain (inner lipoyl domain) to an intact PDC inhibits ATP-dependent inactivation of the complex. By combining molecular modelling, site-directed mutagenesis and biophysical characterizations, we have also identified two amino acid residues in this subdomain (Ile229 and Phe231) that largely determine the magnitude of this effect.

Acetyltransferases↗
PubMed1998

Surfactant replacement increases compliance in premature lamb lungs during partial liquid ventilation in situ.

Treatments available to improve compliance in surfactant-deficient states include exogenous surfactant (ES) and either partial (PLV) or total liquid ventilation (TLV) with perfluorochemical (PFC). Because of the additional air-lung and air-PFC interfaces introduced during PLV compared with TLV, we hypothesized that compliance would be worse during PLV than during TLV. Because surfactant is able to reduce interfacial tension between air and lung as well as between PFC and lung, we further hypothesized that compliance would improve with surfactant treatment before PLV. In excised preterm lamb lungs, we used Survanta for surfactant replacement and perflubron as the PFC. Compliance during PLV was intermediate between TLV and gas inflation, both with and without surfactant. Surfactant improved compliance during PLV, compared with PLV alone. Because of the force-balance equation governing the behavior of immiscible droplets on liquid surfaces, we predict that PFC droplets spread during PLV to cover the alveolar surface in surfactant-deficient lungs during most of lung inflation and deflation but that the PFC would retract into droplets in surfactant-sufficient lungs, except at end inspiration.

Animals↗
PubMed1997

Methamphetamine-induced decrease in tryptophan hydroxylase activity: role of 5-hydroxytryptaminergic transporters.

Methamphetamine-induced 5-hydroxytryptaminergic neuronal damage purportedly involves transport of newly released dopamine from extracellular spaces into 5-hydroxytryptaminergic terminals. This hypothesis is based primarily on findings that dopamine is required for, whereas 5-hydroxytryptamine (5-HT) uptake inhibitors prevent, methamphetamine-induced deficits in 5-hydroxytryptaminergic neuronal function. This hypothesis is not, however, supported by findings presented in this study that 5-hydroxytryptaminergic neuronal damage, induced by p-chloroamphetamine, does not decrease [3H]dopamine uptake into rat brain synaptosomes prepared from 5-HT-transporter-containing tissue. Moreover, despite having greater affinity for the 5-HT transporter, citalopram has an IC50 for [1H]dopamine transport into these synaptosomal preparations that is considerably greater than that of fluoxetine. These data suggest that 5-HT transporters may not effect dopamine uptake and thereby methamphetamine-induced 5-hydroxytryptaminergic neuronal damage. Other possible mechanisms related to 5-HT uptake inhibitor attenuation of methamphetamine-induced deficits were investigated. Fluoxetine pretreatment prevented the methamphetamine-induced decrease in tryptophan hydroxylase activity: this effect cannot be attributed to altered body temperatures or brain concentrations of methamphetamine which suggests that neither, per se, is sufficient to impair 5-hydroxytryptaminergic neuronal function.

Animals↗