Mechanism of adenosine 3′,5′-monophosphate (cAMP)-induced increase in Ca2+ uptake by the sarcoplasmic reticulum in functionally skinned myocardial fibers

The increased rate of Ca²⁺ uptake and ATPase activity in isolated cardiac sarcoplasmic reticulum (SR) by adenosine 3,5-monophosphate (cAMP) has been shown to be activated by a cAMP-dependent protein kinase (cAMP kinase). Functionally skinned myocardial fiber preparations were used to study the mechanisms of cAMP action on the SR at the same time that tension was monitored. cAMP effects were studied on Ca²⁺-activated tension of the contractile proteins, and on Ca²⁺ uptake and release from the SR using caffeine-induced tension transients. Neither cyclic AMP (0.1–5 M) nor the catalytic subunit of cAMP kinase (0.1–1 M) (PK-C) significantly changed either the maximal or the submaximal Ca²⁺-activated tension. The areas of the tension transients were unchanged when cAMP was present in the releasing solution (release phase), and were significantly increased up to a mean of about 80% when cAMP or PK-C was present in the Ca²⁺ loading solutions (uptake phase). The increased tension transient was blocked by the heat-stable inhibitor of cAMP kinase. We conclude that cAMP-induced increases in Ca²⁺ uptake by the SR could play an important role in the positive inotropic effect. cAMP kinase could thus play a crucial role in the regulation of myocardial contractility.     

Teaching systems-based practice to residents by using independent study projects.

The changing health care marketplace requires new graduates to be familiar with complex health systems. Since 1999 the Oregon Health & Science University internal medicine residency program has offered a seminar-based health systems curriculum, but residents lacked an opportunity to actively apply learned concepts. To achieve this goal, the authors developed a second curricular component, the Health Systems Independent Study Project (HSISP). The HSISP is a self-directed assessment of a health care system or delivery issue residents complete in their third year. The curriculum was implemented in 2001 with goals of gaining a focused understanding of a health systems concept and building related skills. Residents present their study projects to all curriculum participants. Topics addressed so far include adherence to coronary artery disease guidelines in a defined population, screening strategies for lung cancer, resident burnout, and many others. Residents have found that these projects enhance their systems knowledge, help them link systems-based-practice concepts to clinical practice, and foster opportunities for networking and early career development.     

Effects of exercise cessation on lipids and lipoproteins in distance runners and power athletes

Summary The purpose of this study was to determine the effects of short-term exercise cessation on lipid and lipoprotein profile and insulin sensitivity in highly trained runners (n=12; mean age 19.9 years) and power athletes (n=12; mean age 24.4 years). Following 14 days of exercise cessation, running time to exhaustion and maximal oxygen uptake decreased by 9.2% and 4.8% (P < 0.05) in the runners, while in the power athletes one repetition maximum squat and bench press did not change (P>0.05). No changes occurred in body composition. Data from a 2-h oral glucose tolerance test revealed an impairment of the glycemic state in all athletes (P<0.05). In contrast, exercise cessation did not significantly (P>0.05) alter plasma levels of cholesterol, triglycerides, and low density (LDL) and high density lipoprotein (HDL). No changes were observed in HDL₂, HDL_2b, and HDL₃ subfractions, LDL diameter, and qualitative LDL pattern (P>0.05). These data thus suggest that despite a decrease in insulin sensitivity, short-term exercise cessation, independent of exercise mode, was insufficient to alter plasma lipid and lipoprotein profiles in well-trained athletes.     

DNA fingerprinting of Pasteurella multocida recovered from avian sources

Repetitive sequence-based PCR (rep-PCR) and amplified fragment length polymorphism (AFLP) were used to characterize a sample of 43 field isolates and 4 attenuated vaccine strains of Pasteurella multocida recovered from multiple avian species. Both rep-PCR and AFLP assays were rapid and reproducible, with high indices of discrimination. Concordance analyses of rep-PCR and AFLP with somatic serotyping indicate that, in general, somatic serotyping is a poor indicator of genetic relatedness among isolates of P. multocida. In addition, the data provide evidence of host specificity of P. multocida clones. Overall, the results of our study indicate that the rep-PCR and AFLP techniques enable rapid fingerprinting of P. multocida isolates from multiple avian species and enhance the investigation of fowl cholera outbreaks.     

Human observer detection experiments with mammograms and power-law noise

We determined contrast thresholds for lesion detection as a function of lesion size in both mammograms and filtered noise backgrounds with the same average power spectrum, P(f)=B/f3. Experiments were done using hybrid images with digital images of tumors added to digitized normal backgrounds, displayed on a monochrome monitor. Four tumors were extracted from digitized specimen radiographs. The lesion sizes were varied by digital rescaling to cover the range from 0.5 to 16 mm. Amplitudes were varied to determine the value required for 92% correct detection in two-alternative forced-choice (2AFC) and 90% for search experiments. Three observers participated, two physicists and a radiologist. The 2AFC mammographic results demonstrated a novel contrast-detail (CD) diagram with threshold amplitudes that increased steadily (with slope of 0.3) with increasing size for lesions larger than 1 mm. The slopes for prewhitening model observers were about 0.4. Human efficiency relative to these models was as high as 90%. The CD diagram slopes for the 2AFC experiments with filtered noise were 0.44 for humans and 0.5 for models. Human efficiency relative to the ideal observer was about 40%. The difference in efficiencies for the two types of backgrounds indicates that breast structure cannot be considered to be pure random noise for 2AFC experiments. Instead, 2AFC human detection with mammographic backgrounds is limited by a combination of noise and deterministic masking effects. The search experiments also gave thresholds that increased with lesion size. However, there was no difference in human results for mammographic and filtered noise backgrounds, suggesting that breast structure can be considered to be pure random noise for this task. Our conclusion is that, in spite of the fact that mammographic backgrounds have nonstationary statistics, models based on statistical decision theory can still be applied successfully to estimate human performance.     

Genetic diagnoses and associated anomalies in fetuses prenatally diagnosed with esophageal atresia

Esophageal atresia (EA) is a congenital anomaly occurring in 2.3 per 10,000 live births. Due to advances in prenatal imaging, EA is more readily diagnosed, but data on the associated genetic diagnoses, other anomalies, and postnatal outcome for fetuses diagnosed prenatally with EA are scarce. We collected data from two academic medical centers (n = 61). Our data included fetuses with suspected EA on prenatal imaging that was confirmed postnatally and had at least one genetic test. In our cohort of 61 cases, 29 (49%) were born prematurely and 19% of those born alive died in the first 9 years of life. The most commonly associated birth defects were cardiac anomalies (67%) and spine anomalies (50%). A diagnosis was made in 61% of the cases; the most common diagnoses were vertebral defects, anal atresia, cardiac anomalies, tracheoesophageal fistula with esophageal atresia, radial or renal dysplasia, and limb anomalies association (43%, although 12% met only 2 of the criteria), trisomy 21 (5%), and CHARGE syndrome (5%). Our findings suggest that most fetuses with prenatally diagnosed EA have one or more additional major anomaly that warrants a more comprehensive clinical genetics evaluation. Fetuses diagnosed prenatally appear to represent a cohort with a worse outcome.     

Coronavirus disinfection in histopathology

ABSTRACT

The 2019 Coronavirus epidemic, provisionally called 2019-nCoV, was first identified in Wuhan, China, in persons exposed to a seafood or wet market. There is an international push to contain the virus and prevent its spread. It is feasible that potentially infectious samples may be received in histopathology laboratories for diagnosis. This technical note presents disinfection procedures and histotechnology processes that should alleviate the risk of infection to laboratory staff. Using data obtained from similar coronaviruses, e.g. severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), experts are confident that 70% ethanol and 0.1% sodium hypochlorite should inactivate the virus. Formalin fixation and heating samples to 56oC, as used in routine tissue processing, were found to inactivate several coronaviruses and it is believed that 2019-nCoV would be similarly affected.     

Developmental trajectories of adolescents' depressive symptoms: predictors of change

In a sample of 240 adolescents assessed annually in Grades 6 through 11, the developmental trajectories of their depressive symptoms were examined using latent factor growth modeling. Growth in mother-reported adolescent depressive symptoms was quadratic; growth in adolescent-reported symptoms was linear. In the model with gender and maternal depression, girls reported a greater increase in depressive symptoms over time than boys, and adolescents of mothers with histories of mood disorders had higher initial levels of depressive symptoms than offspring of never-depressed mothers. After gender and maternal depression were controlled, initial levels of negative attributions and stressors significantly predicted initial levels of adolescent- and mother-reported depressive symptoms. Attributional styles that were increasingly negative across time were associated with significantly higher initial levels (mother reported) and increasing growth (adolescent reported) of depressive symptoms. Reciprocal models in which development of depressive symptoms predicted the development of attributions and stress also were examined.     

Expression and mutation analysis of BRUNOL3, a candidate gene for heart and thymus developmental defects associated with partial monosomy 10p

Partial monosomy 10p is a rare chromosomal aberration. Patients often show symptoms of the DiGeorge/velocardiofacial syndrome spectrum. The phenotype is the result of haploinsufficiency of at least two regions on 10p, the HDR1 region associated with hypoparathyroidism, sensorineural deafness, and renal defects (HDR syndrome) and the more proximal region DGCR2 responsible for heart defects and thymus hypoplasia/aplasia. While GATA3 was identified as the disease causing gene for HDR syndrome, no genes have been identified thus far for the symptoms associated with DGCR2 haploinsufficiency. We constructed a deletion map of partial monosomy 10p patients and narrowed the critical region DGCR2 to about 300 kb. The genomic draft sequence of this region contains only one known gene, BRUNOL3 ( NAPOR, CUGBP2, ETR3). In situ hybridization of human embryos and fetuses revealed as well as in other tissues a strong expression of BRUNOL3 in thymus during different developmental stages. BRUNOL3 appears to be an important factor for thymus development and is therefore a candidate gene for the thymus hypoplasia/aplasia seen in partial monosomy 10p patients. We did not find BRUNOL3 mutations in 92 DiGeorge syndrome-like patients without chromosomal deletions and in 8 parents with congenital heart defect children.     

HIV-1感染引起组蛋白乙酰化和增加p21WAF1表达

目的：DNA甲基化和组蛋白乙酰化是基因表达调控的主要形式。人类免疫缺陷病毒（HIV-1）可引起T淋巴细胞DNA甲基化酶上调。本文旨在明确HIV-1对细胞周期依赖刺激酶抑制剂p21^WAF1表达的影响。方法：建立HIV-1感染的Hut78细胞系；以RT-PCR和Westem blotting 分析p21^WAF1表达情况；以亚硫酸氢钠修饰DNA和基因测序，研究p21^WAF1基因启动子甲基化，以Western blot-ting 和染色体免疫测定探究总组蛋白和与p21^WAF1基因启动子相关的组蛋白乙酰化水平。并以GST pull-down和免疫沉淀分析HIV-1导致乙酰化及乙酰化引起p21^WAF1过表达的可能机理。结果：HIV-1感染后，其反式激活蛋白Tat与辅助转录因子P/CAF、hGCN5结合，共同刺激组蛋白H3乙酰化。尽管p21^WAF1启动子部分区域有甲基化发生，但p21^WAF1表达仍上调。这可能与E2A对p21^WAF1的作用有关。结论：HIV-1感染可引起T淋巴细胞p21^WAF1基因的甲基化和乙酰化紊乱，导致p21^WAF1表达增强。