Characterization of Colorado residents and radon reduction behaviors through latent class analysis and path models

Radon is a naturally occurring radioactive gas that enters homes through cracks in the foundation where accumulated levels can cause lung cancer. Within the United States (U.S.), state level radon reduction strategies rely on education and outreach to motivate people to test and mitigate their home. Only about 5% of the housing units in Colorado, U.S. have been tested for radon. This study looks at the 2012 Behavioral Risk Factors Surveillance System (BRFSS) in Colorado to identify distinct groups of people using Latent Class Analysis, and compares radon awareness, testing, and mitigation to understand underlying differences of radon reduction behaviors using path models. Five classes were identified: 1) Wealthy Young Families, 2) Older Singles, 3) Empty Nesters, 4) Smokers, and 5) Struggling Young Families. Significant differences in responses to radon survey questions existed across groups in which Struggling Young Families were the least likely to be aware of radon, have tested their home for radon, and have their home mitigated. Average radon awareness, testing, and mitigation appeared to be influenced by financial stress. Results from this study can be used to tailor future radon interventions and policy initiatives to enhance equity of radon reduction behaviors including legal framework to ensure radon mitigation takes place in rental properties.

Sugar is not always sweet: exploring the relationship between hyperglycemia and COVID-19 in a predominantly African American population

INTRODUCTION

The purpose of this study is to examine the effect of admission glucose in patients hospitalized with COVID-19 with and without diabetes mellitus in a largely African American cohort.

DESIGN AND METHODS

This study included 708 adults (89% non-Hispanic Black) admitted with COVID-19 to an urban hospital between 1 March and 15 May 2020. Patients with diabetes were compared with those without and were stratified based on admission glucose of 140 and 180 mg/dL. Adjusted ORs were calculated for outcomes of mortality, intubation, intensive care unit (ICU) admission, acute kidney injury (AKI), and length of stay based on admission glucose levels.

RESULTS

Patients with diabetes with admission glucose >140 mg/dL (vs <140 g/dL) had 2.4-fold increased odds of intubation (95% CI 1.2 to 4.6) and 2.1-fold increased odds of ICU admission (95% CI 1.0 to 4.3). Patients with diabetes with admission glucose >180 mg/dL (vs <180 g/dL) had a 1.9-fold increased mortality (95% CI 1.2 to 3.1). Patients without diabetes with admission glucose >140 mg/dL had a 2.3-fold increased mortality (95% CI 1.3 to 4.3), 2.7-fold increased odds of ICU admission (95% CI 1.3 to 5.4), 1.9-fold increased odds of intubation (95% CI 1.0 to 3.7) and 2.2-fold odds of AKI (95% CI 1.1 to 3.8). Patients without diabetes with glucose >180 mg/dL had 4.4-fold increased odds of mortality (95% CI 1.9 to 10.4), 2.7-fold increased odds of intubation (95% CI 1.2 to 5.8) and 3-fold increased odds of ICU admission (95% CI 1.3 to 6.6).

CONCLUSION

Our results show hyperglycemia portends worse outcomes in patients with COVID-19 with and without diabetes. While our study was limited by its retrospective design, our findings suggest that patients presenting with hyperglycemia require closer observation and more aggressive therapies.

The impact of family physicians in rural maternity care

BACKGROUND

Reduced access to maternity care in rural areas of the United States presents a significant burden to pregnant persons and infants. The objective of this study was to estimate the impact of family physicians (FPs) on access to maternity care in rural United States hospitals, especially where other providers may not be available.

METHODS

We administered a survey to 216 rural hospitals in 10 US states inquiring about the number of babies delivered from 2013 to 2017, the types of delivering physicians, and the maternity services offered. We calculated the percentage of rural hospitals in our sample where FPs performed vaginal deliveries, cesareans, and vaginal births after cesarean (VBACs), and the percentage of all babies delivered by FPs. We estimated the distance patients would have to travel for care if FPs were not providing care locally.

RESULTS

The final study population consisted of 185 rural hospitals. FPs delivered babies in 67% of these hospitals and were the only physicians who delivered babies in 27% of these hospitals. FPs provided VBAC at 18% and cesarean birth services at 46% of the rural hospitals, but with wide geographic differences. Many patients would have to drive an average of 86 miles round-trip to access care if those FPs were to stop delivering.

CONCLUSIONS

Family physicians are essential providers of maternity care in the rural United States. Family Medicine residency programs should ensure that trainees who intend to practice in rural locations have adequate maternity care training to maintain and expand access to maternity care for rural patients and their families.

Body Mass Index and Leptin Are Related to Cognitive Performance Over 10 Years in Women With and Without HIV Infection

CONTEXT

It is not yet understood whether people living with HIV infection have an increased risk of Alzheimers Disease and Related Dementias due to enhanced survivorship with highly effective antiretroviral therapies and/or increasing adiposity with aging.

OBJECTIVE

This work aimed to determine whether body mass index (BMI) and leptin were longitudinally associated over 10 years with neuropsychological performance (NP) among middle-aged women with HIV (WWH) vs without HIV.

METHODS

Women's Interagency HIV Study (WIHS) participants (301 WWH, 113 women without HIV from Brooklyn, New York City, and Chicago had baseline and 10-year BMI and fasting plasma leptin levels using commercial enzyme-linked immunosorbent assay (ng/mL); and demographically adjusted NP T scores (attention/working memory, executive function [EF], processing speed, memory, learning, verbal fluency, motor function, global) at 10-year follow-up. Multivariable linear regression analyses, stratified by HIV serostatus, examined associations between BMI, leptin, and NP.

RESULTS

Over 10 years, women (baseline age 39.8 ± 9.2 years, 73% Black, 73% WWH) transitioned from average overweight (29.1 ± 7.9) to obese (30.5 ± 7.9) BMI. Leptin increased 11.4 ± 26.4 ng/mL (P < .001). Higher baseline BMI and leptin predicted poorer 10-year EF among all women (BMI β = -6.97, 95% CI (-11.5 to -2.45) P = .003; leptin β = -1.90, 95% CI (-3.03 to -0.76), P = .001); higher baseline BMI predicted better memory performance (β = 6.35, 95% CI (1.96-10.7), P = .005). Greater 10-year leptin increase predicted poorer EF (P = .004), speed (P = .03), and verbal (P = .02) and global (P = 0.005) performance among all women, and WWH. Greater 10-year BMI increase predicted slower processing speed (P = .043) among all women; and among WWH, poorer EF (P = .01) and global (P = .04) performance.

CONCLUSION

In middle-aged WIHS participants, 10-year increases in BMI and leptin were associated with poorer performance across multiple NP domains among all women and WWH. Trajectories of adiposity measures over time may provide insight into the role of adipose tissue in brain health with aging.

Epistasis, aneuploidy, and functional mutations underlie evolution of resistance to induced microtubule depolymerization

Cells with blocked microtubule polymerization are delayed in mitosis, but eventually manage to proliferate despite substantial chromosome missegregation. While several studies have analyzed the first cell division after microtubule depolymerization, we have asked how cells cope long-term with microtubule impairment. We allowed 24 clonal populations of yeast cells with beta-tubulin mutations preventing proper microtubule polymerization, to evolve for ˜150 generations. At the end of the laboratory evolution experiment, cells had regained the ability to form microtubules and were less sensitive to microtubule-depolymerizing drugs. Whole-genome sequencing identified recurrently mutated genes, in particular for tubulins and kinesins, as well as pervasive duplication of chromosome VIII. Recreating these mutations and chromosome VIII disomy prior to evolution confirmed that they allow cells to compensate for the original mutation in beta-tubulin. Most of the identified mutations did not abolish function, but rather restored microtubule functionality. Analysis of the temporal order of resistance development in independent populations repeatedly revealed the same series of events: disomy of chromosome VIII followed by a single additional adaptive mutation in either tubulins or kinesins. Since tubulins are highly conserved among eukaryotes, our results have implications for understanding resistance to microtubule-targeting drugs widely used in cancer therapy.

Sugar Is Not Always Sweet: Exploring the Relationship Between Hyperglycemia and COVID-19 in a Predominantly African American Population

Introduction: A relationship between hyperglycemia and outcomes in patients with COVID-19 has been proposed, however there is a paucity of literature on this. In this study, we examined the effect of admission glucose in diabetics and non-diabetics on outcomes in patients hospitalized with COVID-19. Our study uniquely examines this association in a largely African American cohort, a population disproportionately affected by COVID-19.

Methods: In this retrospective cohort study, we analyzed all adults admitted with COVID-19 to a designated COVID hospital in Brooklyn, NY from March 1 to May 15, 2020. Diabetics were compared to non-diabetics, and were further stratified based on admission glucoses of 140 and 180 mg/dL. Diagnosis of diabetes was based on history and/or Hba1c > 6.5%. Univariate, multiple and logistic regressions were used for analyses, examining outcomes of mortality, intubation, ICU admission, acute kidney injury (AKI), and length of stay based on admission glucose levels, while controlling for age, gender, lab values (serum creatinine and WBC), and comorbidities including hypertension, cardiovascular disease, and obesity. Outcomes are presented as an adjusted odds ratio (OR) with 95% confidence interval (95% CI).

Results: 708 patients were analyzed; 54% diabetics, 83.5% non-Hispanic Blacks, 51% male with a mean age of 68, BMI of 29 kg/m² and crude mortality rate of 40%. The length of hospital stay was greater in diabetics than non-diabetics, (13±26 days vs 9.5±18.5 days, p<0.05). Diabetics with an admission glucose > 140 mg/dL (vs<140 g/dL) had a 2.4-fold increased odds of both intubation and ICU admission (95% CI: 1.2, 4.5; 1.3, 4.6). Diabetics with admission glucoses > 180 mg/dL (vs <180 g/dL) had a 1.8-fold increased mortality (95% CI: 1.2, 2.9). Non-diabetics with admission glucoses >140 mg/dL (vs<140 g/dL) had a two-fold increased mortality (95% CI: 1.2, 3.5), 3.5-fold increased odds of ICU admission (95% CI: 1.8,6.6) and a 2.3-fold increased odds of both intubation and AKI (95% CI: 1.3, 4.2; 1.3,4.2). Non-diabetics with a glucose >180 mg/dL (vs <180 g/dL) had a four-fold increased mortality (95% CI: 1.8, 8.8), 2.7-fold increased odds of intubation (95% CI: 1.3, 5.6) and 2.9-fold increased odds of ICU admission (95% CI: 1.3, 6.2).

Conclusion: Our results show hyperglycemia portends worse outcomes in diabetics and non-diabetics with COVID-19. Elevated admitting glucoses >180 mg/dL increased odds of mortality four-fold in non-diabetics and 1.8- fold in diabetics. In COVID-19, diabetic patients had a 37% greater length of hospital stay than non-diabetics. Whether hyperglycemia is a marker or a cause of more severe COVID-19 is unknown. These findings suggest that patients presenting with hyperglycemia require closer observation and more aggressive therapies. This raises the testable hypothesis that intensive glucose control may improve outcomes in patients with COVID-19.

Urine tungsten and chronic kidney disease in rural Colorado

BACKGROUND

Chronic kidney disease (CKD) is a cause of global morbidity and mortality in agricultural communities. The San Luis Valley (SLV) is a rural agricultural community in southern Colorado with geographic and sociodemographic risk factors for CKD, including a water supply contaminated by heavy metals.

METHODS

We obtained pre-existing sociodemographic, clinical, and urine trace metal data for 1659 subjects from the San Luis Valley Diabetes Study, a prospective cohort study. We assessed prospective associations between urine tungsten (W) and time-to-CKD using accelerated failure time models (n = 1659). Additionally, logistic models were used to assess relationships between urine W and renal injury markers (NGAL, KIM1) using Tobit regression (n = 816), as well as epidemiologically-defined CKD of unknown origin (CKDu) using multiple logistic regression (n = 620).

RESULTS

Elevated urine W was strongly associated with decreased time-to-CKD, even after controlling for hypertension and diabetes. Depending on how CKD was defined, a doubling of urine W was associated with a 27% (95% CI 11%, 46%) to 31% (14%, 51%) higher odds of developing CKD within 5 years. The relationship between urine W and select renal injury markers was not significant, although urine NGAL was modified by diabetes status. Elevated (>95%ile) urinary W was significantly associated with CKDu (OR 5.93, 1.83, 19.21) while adjusting for known CKD risk factors.

CONCLUSIONS

Our data suggest that increased exposure to W is associated with decreased time-to-CKD and may be associated with CKDu. Given persistence of associations after controlling for diabetes and hypertension, W may exert a primary effect on the kidney, although this needs to be evaluated further in future studies.

The psychosocial work environment, musculoskeletal disorders and their functional consequences among pediatric healthcare providers

OBJECTIVE

The goal of this study was to examine the association between aspects of the psychosocial work environment and prevalence of musculoskeletal disorders (MSDs) and associated functional consequences among pediatric healthcare providers.

BACKGROUND

The psychosocial work demands make pediatric care providers susceptible to MSDs and subsequent functional consequences, but research on this at-risk group is lacking.

METHODS

Randomly selected pediatric registered nurses, behavioral health specialists, and patient care assistants (N = 569) completed a survey assessing psychosocial factors, MSDs, and functional consequences (e.g., missing work). Logistic regression was used to assess associations between psychosocial factors and outcomes.

RESULTS

The analysis yielded moderate-to-strong, significant associations between psychosocial environment factors and MSDs and their functional consequences. The odds of MSDs increased nearly three-fold in the highest quartile of the psychosocial summary score vs. the lowest (OR: 2.7, 95% CI: 1.6-4.5). The highest quartiles of the psychosocial environment measures were significantly associated with functional consequences of MSDs.

CONCLUSION

Results confirm knowledge about the association between the psychosocial environment and MSDs and demonstrates the association also exists among pediatric providers. Our study highlights the importance of studying the functional consequences of MSDs, which characterize the impact of MSD burden at work and elsewhere.

Convenience and corner store fruit and vegetable access: attitudes and intentions among Colorado adults, 2014

Aim

The term food desert generally refers to areas where healthy food options, such as fresh fruits and vegetables, are unavailable within a certain number of miles. However, other factors besides distance may affect the ability to purchase healthier foods. The goal of this study was to understand Colorado adults' perceptions of their access to healthy food options and to assess how other structural and socio-demographic factors may affect that access.

Subject and methods

Colorado adults were asked questions about self-reported access to healthy food, likelihood of buying fresh fruits and vegetables from convenience/corner stores if available, perceived characteristics of fruits and vegetables available for purchase near respondents' residence, and demographics.

Results

A majority of Colorado adults in 2013-14 reported wanting fresh fruits and vegetables to be more available, more varied, higher quality, and/or less expensive. Socioeconomic status, race/ethnicity, and regular shopping habits were significantly associated with reported likelihood of purchasing fruits and vegetables from a convenience/corner store if available.

Conclusion

Factors other than proximity to a grocery store affect Colorado adults' perceived access to healthy food options and should be considered in the development and implementation of public health programs and policies geared toward improving healthy food access.

Contributions of US Medical Schools to Primary Care (2003-2014): Determining and Predicting Who Really Goes Into Primary Care

BACKGROUND AND OBJECTIVES

Schools of medicine in the United States may overstate the placement of their graduates in primary care. The purpose of this project was to determine the magnitude by which primary care output is overestimated by commonly used metrics and identify a more accurate method for predicting actual primary care output.

METHODS

We used a retrospective cohort study with a convenience sample of graduates from US medical schools granting the MD degree. We determined the actual practicing specialty of those graduates considered primary care based on the Residency Match Method by using a variety of online sources. Analyses compared the percentage of graduates actually practicing primary care between the Residency Match Method and the Intent to Practice Primary Care Method.

RESULTS

The final study population included 17,509 graduates from 20 campuses across 14 university systems widely distributed across the United States and widely varying in published ranking for producing primary care graduates. The commonly used Residency Match Method predicted a 41.2% primary care output rate. The actual primary care output rate was 22.3%. The proposed new method, the Intent to Practice Primary Care Method, predicted a 17.1% primary care output rate, which was closer to the actual primary care rate.

CONCLUSIONS

A valid, reliable method of predicting primary care output is essential for workforce training and planning. Medical schools, administrators, policy makers, and popular press should adopt this new, more reliable primary care reporting method.

The Nutrition Benefits Participation Gap: Barriers to Uptake of SNAP and WIC Among Latinx American Immigrant Families

To examine nutrition benefit under-enrollment in Latinx American immigrant families, we administered a survey to 100 adults attending a NY Latinx American community serving organization. We used a logistic regression approach to analyze misinformation impact on enrollment, and examined non-enrollment explanations, among participants in whose families a child or pregnant or breastfeeding woman appeared SNAP- or WIC-eligible. Among households (N = 51) with ≥ 1 SNAP-eligible child, 49% had no child enrolled. Reasons included repercussion fears (e.g. payback obligation, military conscription, college aid ineligibility, child removal, non-citizen family member penalties), and logistical barriers. In multivariable regression models, having heard the rumor that SNAP/WIC participation makes unauthorized status family members vulnerable to being reported to the government was associated with an 85% lower enrollment rate (OR 0.15, CI 0.03, 0.94). Misinformation impedes nutrition benefit participation. A multi-level intervention is necessary to inform potential applicants and providers regarding eligibility criteria and erroneous rumors, along with an informed discussion of the risks versus benefits of using resources, especially as public charge criteria change.

An Ultrastructural Study of the Extruded Polar Tube of Anncaliia algerae (Microsporidia)

All microsporidia share a unique, extracellular spore stage, containing the infective sporoplasm and the apparatus for initiating infection. The polar filament/polar tube when exiting the spore transports the sporoplasm through it into a host cell. While universal, these structures and processes have been enigmatic. This study utilized several types of microscopy, describing and extending our understanding of these structures and their functions. Cryogenically preserved polar tubes vary in diameter from 155 to over 200 nm, noticeably larger than fixed-sectioned or negatively stained samples. The polar tube surface is pleated and covered with fine fibrillar material that projects from the surface and is organized in clusters or tufts. These fibrils may be the sites of glycoproteins providing protection and aiding infectivity. The polar tube surface is ridged with 5-6 nm spacing between ridges, enabling the polar tube to rapidly increase its diameter to facilitate the passage of the various cargo including cylinders, sacs or vesicles filled with particulate material and the intact sporoplasm containing a diplokaryon. The lumen of the tube is lined with a membrane that facilitates this passage. Careful examination of the terminus of the tube indicates that it has a closed tip where the membranes for the terminal sac are located.

Histopathology of the gut in rheumatic diseases

The gastrointestinal tract regulates the trafficking of macromolecules between the environment and the host through an epithelial barrier mechanism and is an important part of the immune system controlling the equilibrium between tolerance and immunity to non-self-antigens. Various evidence indicates that intestinal inflammation occurs in patients with rheumatic diseases. In many rheumatic diseases intestinal inflammation appears to be linked to dysbiosis and possibly represents the common denominator in the pathogenesis of different rheumatic diseases. The continuative interaction between dysbiosis and the intestinal immune system may lead to the aberrant activation of immune cells that can re-circulate from the gut to the sites of extraintestinal inflammation as observed in patients with ankylosing spondylitis. The exact contribution of genetic factors in the development of intestinal inflammation in rheumatic diseases needs to be clarified.

Pathogenesis of polymyalgia rheumatica

Polymyalgia rheumatica (PMR) is a chronic, inflammatory disorder of unknown cause, almost exclusively occurring in people aged over 50 and often associated with giant cell arteritis. The evidence that PMR occurs almost exclusively in individuals aged over 50 may indicate that age-related immune alterations in genetically predisposed subjects contribute to development of the disease. Several infectious agents have been investigated as possible triggers of PMR even though the results are inconclusive. Activation of the innate and adaptive immune systems has been proved in PMR patients as demonstrated by the activation of dendritic cells and monocytes/macrophages and the altered balance between Th17 and Treg cells. Disturbed B cell distribution and function have been also demonstrated in PMR patients suggesting a pathogenesis more complex than previously imagined. In this review we will discuss the recent findings regarding the pathogenesis of PMR.

Citron kinase-dependent F-actin maintenance at midbody secondary ingression sites mediates abscission

Abscission is the final step of cytokinesis whereby the intercellular bridge (ICB) linking the two daughter cells is cut. The ICB contains a structure called the midbody, required for the recruitment and organization of the abscission machinery. Final midbody severing is mediated by formation of secondary midbody ingression sites, where ESCRT III component CHMP4B is recruited and may mediate membrane fusion. It is presently unknown how cytoskeletal elements cooperate with CHMP4B to mediate abscission. In this report, we show that F-actin is associated with midbody secondary sites and is necessary for abscission. F-actin localization at secondary sites depends on the activity of RhoA and on the abscission regulator CITK. CITK depletion accelerates F-actin loss at the midbody and cytokinesis defects produced by CITK loss are reverted by restoring actin polymerization. Conversely, midbody hyperstabilization produced by CITK and ANLN overexpression is reverted by actin depolymerization. CITK is required for F-actin and ANLN localization at the abscission sites, as well as for CHMP4B recruitment. These results indicate that control of actin dynamics downstream of CITK prepares abscission site for final cut.

Acute change of titin at mid-sarcomere remains despite 8 wk of plyometric training

The purpose of this study was to investigate skeletal muscle changes induced by an acute bout of plyometric exercise (PlyEx) both before and after PlyEx training, to understand if titin is affected differently after PlyEx training. Healthy untrained individuals ( N = 11) completed the 1stPlyEx (10 × 10 squat-jumps, 1-min rest). Thereafter, six subjects completed 8 wk of PlyEx, while five controls abstained from any jumping activity. Seven days after the last training session, all subjects completed the 2ndPlyEx. Blood samples were collected before and 6 h and 1, 2, 3, and 4 days after each acute bout of PlyEx, and muscle biopsies 4 days before and 3 days after each acute bout of PlyEx. The 1stPlyEx induced an increase in circulating myoglobin concentration. Muscle sample analysis revealed Z-disk streaming, a stretch or a fragmentation of titin (immunogold), and increased calpain-3 autolysis. After training, 2ndPlyEx did not induce Z-disk streaming or calpain-3 activation. The previously observed post-1stPlyEx positional change of the titin COOH terminus was still present pre-2ndPlyEx, in all trained and all control subjects. Only two controls presented with Z-disk streaming after 2ndPlyEx, while calpain-3 activation was absent in all controls. Eccentric explosive exercise induced a stretch or fragmentation of titin, which presented as a positional change of the COOH terminus. Calpain-3 activation does not occur when titin is already stretched before explosive jumping. Enzymatic digestion results in titin fragmentation, but since an increase in calpain-3 autolysis was visible only after the 1stPlyEx acute bout, fragmentation cannot explain the prolonged positional change.

Recovery of damaged skeletal muscle in mdx mice through low-intensity endurance exercise

The lack of dystrophin in mdx mice leads to cycles of muscle degeneration and regeneration processes. Various strategies have been proposed in order to reduce the muscle-wasting component of muscular dystrophy, including implementation of an exercise programme. The aim of this study was to examine how low-intensity endurance exercise affects the degeneration-regeneration process in dystrophic muscle of male mdx mice. Mice were subjected to low-intensity endurance exercise by running on a motorized Rota-Rod for 5 days/week for 6 weeks. Histomorphological analysis showed a significant reduction of measured inflammatory-necrotic areas in both gastrocnemius and quadriceps muscle of exercised mdx mice as compared to matched sedentary mdx mice. The degenerative-regenerative process was also evaluated by examining the protein levels of connexin 39 (Cx39), a specific gene expressed in injured muscles. Cx39 was not detected in sedentary wild type mice, whereas it was found markedly increased in sedentary mdx mice, revealing active muscle degeneration-regeneration process. These Cx39 protein levels were significantly reduced in muscles of mdx mice exercised for 30 and 40 days, revealing together with histomorphological analysis a strong reduction of degeneration process in mice subjected to low-intensity endurance exercise. Muscles of exercised mdx mice did not show significant changes in force and fatigue resistance as compared to sedentary mdx mice. Overall in this study we found that specific low-intensity endurance exercise induces a beneficial effect probably by reducing the degeneration of dystrophic muscle.

Satellite cell count, VO(2max) , and p38 MAPK in inactive to moderately active young men

Satellite cells (SCs) are responsible for muscle repair following strenuous exercise or injury. SC responses to intervention have been studied, but most studies do not discuss or take into account the substantial variability in SC number among young individuals. We hypothesized that an active lifestyle reflected in higher VO(2max) may be associated with greater SC number. As training alters basal p38-mitogen-activated protein kinase (MAPK) activity, which is associated with SC proliferation, SC count may also correlate with this stress signaling kinase. Muscle biopsies from vastus lateralis of eight male participants were analyzed for fiber type, myogenin, and p38/phospho-p38 MAPK using SDS-PAGE and Western blotting. Immunofluorescence was used to detect Pax7(+) SCs. Two weeks following the biopsy, subjects underwent an incremental treadmill test to determine VO(2max) . A strong positive correlation (P = 0.0087) was found between the number of Pax7(+) nuclei and VO(2max) . Pax7(+) cell number correlated negatively with phospho-p38/p38 MAPK (P = 0.0006), but had no correlation with fiber type or myogenin. SC number is proportional to VO(2max) , and hence it can be postulated that higher levels of physical activity activate SC proliferation but not fusion, underlining the relevance of exercise in stimulating SC pool size even without injury.

Increased Cx43 and Angiogenesis in Exercised Mouse Hearts

Several studies focused on the macroscopic architecture of increased cardiac wall induced by exercise training. Our goal was to evaluate myocardiocyte, interstitial and vascular component, and connexin-43 expression in endurance-trained mouse hearts. Sixty-three 10-week-old male Swiss mice were divided into four sedentary groups (C0, C15, C30 and C45) and three groups exercised respectively for 15 (T15-D; running intensity [RI]: 3.18 m/min; running duration [RD]: 75 min/first week and 150 min/second week), 30 (T30-D; RI: 3.96 m/min; RD: 150 min/third week and 225 min/fourth week) and 45 days (T45-D; RI: 3.96 m/min and 4.8 m/min, respectively for the fifth and sixth week; RD: 300 min) on a treadmill. Morphometric analyses were performed to quantify myocardiocyte size and number, and the capillary and interstitial connective tissue (ICT) area. We assessed the expression of ventricle myosin light chain-II, vimentin and connexin-43 by western blot analyses. Our results showed a hypertrophy of the interventricular septum and left ventricle in T30-D and T45-D mice that was not due to variations in myofibrillar content, myocardiocyte size and number, or ICT quantity but to a significant increase in the capillary area. The microvascular remodeling was associated with vimentin increased expression in ICT cells and connexin-43 upregulation. The first phenomenon might be related to an enhanced request of remodeling and growth factors; the second suggests a new role of connexin-43 in cardiac angiogenesis.

Increased expression of titin in mouse gastrocnemius muscle in response to an endurance-training program

Titin, a sarcomeric giant protein, plays crucial roles in muscle assembly, elasticity and stability. Little is known about titin adaptation to endurance exercise. We studied the effects of endurance training on titin expression in mouse gastrocnemius muscles (MGM). Sixty-three ten-week-old male Swiss mice were divided into seven groups. Four groups were composed of untrained control animals (C0, C15, C30, C45) instead the other three included mice trained for 15 (T15), 30 (T30) and 45 (T45) days by treadmill. The training protocol was mainly aerobic, characterized by moderate-intensity, rhythmic and continuous exercises. Titin expression was determined by immunohistochemistry on MGM sections. Results revealed a significant reduction in body weight of the T45 mice and a significant increase in titin expression (% titin immunoreactivity median [range] = 41.11 [20-60] vs. 30.00 [10-50]). It is postulated that the up-regulation of titin expression is an adaptative mechanism to increase muscle elasticity and stability in response to the high number of stretch-shorten cycles during endurance training. Such a mechanism may be important for minimizing muscle energy consumption and improving performance during running.

Real time magnetic resonance guided endomyocardial local delivery

OBJECTIVE

To investigate the feasibility of targeting various areas of left ventricle myocardium under real time magnetic resonance (MR) imaging with a customised injection catheter equipped with a miniaturised coil.

DESIGN

A needle injection catheter with a mounted resonant solenoid circuit (coil) at its tip was designed and constructed. A 1.5 T MR scanner with customised real time sequence combined with in-room scan running capabilities was used. With this system, various myocardial areas within the left ventricle were targeted and injected with a gadolinium-diethylenetriaminepentaacetic acid (DTPA) and Indian ink mixture.

RESULTS

Real time sequencing at 10 frames/s allowed clear visualisation of the moving catheter and its transit through the aorta into the ventricle, as well as targeting of all ventricle wall segments without further image enhancement techniques. All injections were visualised by real time MR imaging and verified by gross pathology.

CONCLUSION

The tracking device allowed real time in vivo visualisation of catheters in the aorta and left ventricle as well as precise targeting of myocardial areas. The use of this real time catheter tracking may enable precise and adequate delivery of agents for tissue regeneration.

Caveolin-1 null mice are viable but show evidence of hyperproliferative and vascular abnormalities

Caveolin-1 is the principal structural protein of caveolae membranes in fibroblasts and endothelia. Recently, we have shown that the human CAV-1 gene is localized to a suspected tumor suppressor locus, and mutations in Cav-1 have been implicated in human cancer. Here, we created a caveolin-1 null (CAV-1 -/-) mouse model, using standard homologous recombination techniques, to assess the role of caveolin-1 in caveolae biogenesis, endocytosis, cell proliferation, and endothelial nitric-oxide synthase (eNOS) signaling. Surprisingly, Cav-1 null mice are viable. We show that these mice lack caveolin-1 protein expression and plasmalemmal caveolae. In addition, analysis of cultured fibroblasts from Cav-1 null embryos reveals the following: (i) a loss of caveolin-2 protein expression; (ii) defects in the endocytosis of a known caveolar ligand, i.e. fluorescein isothiocyanate-albumin; and (iii) a hyperproliferative phenotype. Importantly, these phenotypic changes are reversed by recombinant expression of the caveolin-1 cDNA. Furthermore, examination of the lung parenchyma (an endothelial-rich tissue) shows hypercellularity with thickened alveolar septa and an increase in the number of vascular endothelial growth factor receptor (Flk-1)-positive endothelial cells. As predicted, endothelial cells from Cav-1 null mice lack caveolae membranes. Finally, we examined eNOS signaling by measuring the physiological response of aortic rings to various stimuli. Our results indicate that eNOS activity is up-regulated in Cav-1 null animals, and this activity can be blunted by using a specific NOS inhibitor, nitro-l-arginine methyl ester. These findings are in accordance with previous in vitro studies showing that caveolin-1 is an endogenous inhibitor of eNOS. Thus, caveolin-1 expression is required to stabilize the caveolin-2 protein product, to mediate the caveolar endocytosis of specific ligands, to negatively regulate the proliferation of certain cell types, and to provide tonic inhibition of eNOS activity in endothelial cells.

Isoform-specific localization of A-RAF in mitochondria

RAF kinase is a family of isoforms including A-RAF, B-RAF, and C-RAF. Despite the important role of RAF in cell growth and proliferation, little evidence exists for isoform-specific function of RAF family members. Using Western analysis and immunogold labeling, A-RAF was selectively localized in highly purified rat liver mitochondria. Two novel human proteins, which interact specifically with A-RAF, were identified, and the full-length sequences are reported. These proteins, referred to as hTOM and hTIM, are similar to components of mitochondrial outer and inner membrane protein-import receptors from lower organisms, implicating their involvement in the mitochondrial transport of A-RAF. hTOM contains multiple tetratricopeptide repeat (TPR) domains, which function in protein-protein interactions. TPR domains are frequently present in proteins involved in cellular transport systems. In contrast, protein 14-3-3, an abundant cytosolic protein that participates in many facets of signal transduction, was found to interact with C-RAF but not with A-RAF N-terminal domain. This information is discussed in view of the important role of mitochondria in cellular functions involving energy balance, proliferation, and apoptosis and the potential role of A-RAF in regulating these systems.

The M cell as a portal of entry to the lung for the bacterial pathogen Mycobacterium tuberculosis

M. tuberculosis accesses the terminal lung and is phagocytosed by alveolar macrophages. Utilizing a mouse intratracheal challenge model, we demonstrate that M. tuberculosis rapidly enters through M cells as well. From there, bacilli are deposited within associated intraepithelial leukocytes and subsequently conveyed to the draining lymph nodes early after infection. Osteopetrotic (Csfm(op)/Csfm(op)) mice, null mutants for macrophage colony-stimulating factor, possess diminished numbers of circulating monocytes and tissue macrophages. Csfm(op)/Csfm(op) mice were highly susceptible to challenge with M. tuberculosis. In contrast to controls, tubercle bacilli were not conveyed to draining lymph nodes early after infection but were instead retained within the mucosa. These results indicate that M cells represent an alternate portal of entry for M. tuberculosis, which may contribute to the rapid development of protective lung immune responses.

Relationship between Arp2/3 complex and the barbed ends of actin filaments at the leading edge of carcinoma cells after epidermal growth factor stimulation

Using both light and high resolution electron microscopy, we analyzed the spatial and temporal relationships between the Arp2/3 complex and the nucleation activity that is required for lamellipod extension in mammary carcinoma cells after epidermal growth factor stimulation. A rapid two- to fourfold increase in filament barbed end number occurs transiently after stimulation and remains confined almost exclusively to the extreme outer edge of the extending lamellipod (within 100-200 nm of the plasma membrane). This is accompanied by an increase in filament density at the leading edge and a general decrease in filament length, with a specific loss of long filaments. Concomitantly, the Arp2/3 complex is recruited with a 1.5-fold increase throughout the entire cortical filament network extending 1-1.5 microm in depth from the membrane at the leading edge. The recruitment of the Arp2/3 complex at the membrane of the extending lamellipod indicates that Arp2/3 may be involved in initial generation of growing filaments. However, only a small subset of the complex present in the cortical network colocalizes near free barbed ends. This suggests that the 100-200-nm submembraneous compartment at the leading edge of the extending lamellipod constitutes a special biochemical microenvironment that favors the generation and maintenance of free barbed ends, possibly through the locally active Arp2/3 complex, severing or decreasing the on-rate of capping protein. Our results are inconsistent with the hypothesis suggesting uncapping is the dominant mechanism responsible for the generation of nucleation activity. However, they support the hypothesis of an Arp2/3-mediated capture of actin oligomers that formed close to the membrane by other mechanisms such as severing. They also support pointed-end capping by the Arp2/3 complex, accounting for its wide distribution at the leading edge.

Water channel-carrying vesicles in the rat IMCD contain cellubrevin

Antidiuretic hormone (arginine vasopressin) induces a cyclic process of docking, fusion, and endocytosis of water channel-containing vesicles in the collecting duct. There is now evidence that docking and endocytosis are mediated by an array of proteins associated with vesicles and target membranes. In recent studies, we have shown that cellubrevin, a member of the vesicle-associated membrane protein family, as well as other docking proteins, are expressed in the rat inner medullary collecting duct. We now show by immunogold electron microscopy that cellubrevin is present on vesicles containing water channels, that it is associated with both coated and uncoated vesicles, and that it is present on the apical membrane. Cellubrevin, therefore, is in a position to mediate one or more steps in arginine vasopressin-induced water channel cycling.

Vesicle fusion proteins in rat inner medullary collecting duct and amphibian bladder

The delivery of water channels to the apical membrane in response to antidiuretic hormone (ADH) requires the targeting of channel-containing vesicles to specific sites in the membrane, followed by fusion and exocytosis. A complex array of proteins is now believed to mediate targeting and fusion in eukaryotic cells. They include N-ethylmaleimide-sensitive fusion protein (NSF), soluble NSF attachment proteins (SNAP), and cellubrevin, a vesicle-associated protein present in the nerve terminal. We asked whether these proteins are in epithelial cells of rat inner medullary collecting duct (IMCD) and amphibian bladder. Immunoblots on both tissues showed the presence of NSF and alpha-SNAP. Cellubrevin was present in immunoblots of the IMCD, but not the bladder. Immunogold electron microscopy showed NSF, alpha-SNAP, and cellubrevin in rat IMCD cells, with vesicular labeling. In the bladder, NSF was seen on vesicles and aggrephores. We conclude that components of the vesicle-targeting and fusion systems are present in kidney and amphibian bladder and may mediate a wide variety of fusion events, including those initiated by ADH.

Immunochemical features of a macromolecule of Treponema denticola

In this study the extraction and the immunochemical features of a lipopolysaccharide-like (LPSL) macromolecule of T. denticola strains 35405, 35404, 33521 and 11 were investigated. The yield of LPSL molecule ranged between 0.5-0.9% of the cell dry weight, it possessed Limulus amebocyte lysate clotting activity, and it contained glucosamine, phosphate, heptose, glucose, small amounts of KDO, myristic and beta hydroxy myristic acid. Sera obtained from healthy individuals (ADA type I) periodontitis, from 3-8 month old infants, or the mouse monoclonal antibody, diluted 1:2, against T. pallidum did not react with the LPSL antigens of T. denticola strains 35405, 35404, 33521, and 11. Sera from patients with ADA type III-IV periodontitis were reactive with two 8-14 kDa bands even at serum dilutions of 1:2000. Sera from patients with ADA type II periodontitis showed good antibody response to the 8-14 kDa band at a dilution of 1:50, but were weekly reactive, or nonreactive at serum dilutions of 1:200. This study indicates that extraction of a lipopolysaccharide-like macromolecule is feasible from the assay spirochetes, and this macromolecule may be used as an antigen for the diagnosis of ADA types II-IV periodontitis.

Observation of unique cross-linked lattices between multiantennary carbohydrates and soybean lectin. Presence of pseudo-2-fold axes of symmetry in complex type carbohydrates

The tetrameric lectin from Glycine max (soybean) (SBA) has been shown to cross-link and precipitate with N-linked multiantennary complex type oligosaccharides containing nonreducing terminal Gal residues (Bhattacharyya, L., Haraldsson, M., & Brewer, C. F. (1988) Biochemistry 27, 1034-1041). In the present study, negative stain electron micrographs of the precipitates of SBA with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal Gal or GalNAc residues show the presence of highly ordered cross-linked lattices for many of the complexes. The precipitates of SBA with a "bisected" and "nonbisected" N-linked biantennary complex type oligosaccharide containing Gal residues at the nonreducing termini show similar two-dimensional patterns. However, the pattern observed for the precipitates of a tetraantennary complex type oligosaccharide with SBA is distinct from those of the two biantennary carbohydrates. Furthermore, the precipitates formed between the lectin and a synthetic O-linked biantennary ("cluster") glycoside with terminal GalNAc residues show a pattern that is different from those above. Four biantennary pentasaccharide analogs of the blood group I antigen containing beta-LacNAc moieties at the 2,3-, 2,4-, 2,6-, and 3,6-positions of the core Gal also showed ordered patterns in their precipitates with SBA. X-ray crystallographic data and mixed quantitative precipitation profiles of binary mixtures of the four analogs demonstrate that each analog possesses a unique cross-linked lattice with the protein. A common structural feature of the naturally occurring and synthetic carbohydrates that show highly organized cross-linked lattices with SBA is the presence of a pseudo-2-fold axis of symmetry in each oligosaccharide relating the terminal binding epitopes on each arm. This suggests that the symmetry features of certain naturally occurring branch chain oligosaccharides facilitate formation of highly ordered, homogeneous cross-linked complexes with specific lectins.

Observation of unique cross-linked lattices between multiantennary carbohydrates and soybean lectin. Presence of pseudo-2-fold axes of symmetry in complex type carbohydrates

The tetrameric lectin from Glycine max (soybean) (SBA) has been shown to cross-link and precipitate with N-linked multiantennary complex type oligosaccharides containing nonreducing terminal Gal residues (Bhattacharyya, L., Haraldsson, M., & Brewer, C. F. (1988) Biochemistry 27, 1034-1041). In the present study, negative stain electron micrographs of the precipitates of SBA with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal Gal or GalNAc residues show the presence of highly ordered cross-linked lattices for many of the complexes. The precipitates of SBA with a "bisected" and "nonbisected" N-linked biantennary complex type oligosaccharide containing Gal residues at the nonreducing termini show similar two-dimensional patterns. However, the pattern observed for the precipitates of a tetraantennary complex type oligosaccharide with SBA is distinct from those of the two biantennary carbohydrates. Furthermore, the precipitates formed between the lectin and a synthetic O-linked biantennary ("cluster") glycoside with terminal GalNAc residues show a pattern that is different from those above. Four biantennary pentasaccharide analogs of the blood group I antigen containing beta-LacNAc moieties at the 2.3-, 2.4-, 2.6-, and 3.6-positions of the core Gal also showed ordered patterns in their precipitates with SBA. X-ray crystallographic data and mixed quantitative precipitation profiles of binary mixtures of the four analogs demonstrate that each analog possesses a unique cross-linked lattice with the protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous host endothelial growth on bioprosthetic valves and its relation to calcification

We studied host endothelial growth and calcification of bovine pericardial valve prostheses treated with: (A) 0.625% glutaraldehyde + 4% formaldehyde, (B) 99.5% glycerol or (C) 99.5% glycerol + 4% formaldehyde. Twenty-three stentless chordally supported bileaflet pericardial mitral valves with treatments A (n = 6), B (n = 6) or C (n = 11) were implanted in juvenile sheep for 125-273 days. After sacrifice, the anterior cusp from the annulus to papillary muscle of each valve was examined by scanning electron microscopy for the presence of endothelial cells, and the intrinsic calcification of each valve was determined by measuring calcium (micrograms/mg dry weight) from another 1 cm2 piece of grossly normal cusp. Sixty pieces of 1 cm2 pericardium with treatment A, B or C (n = 20 in each group) were implanted in 30 rats for 70 days. Calcium analysis and histology study of the implants were performed. In sheep, within a similar range of implantation periods, the endothelial growth rate of the valves was the highest in group B, 100% (6/6); group C was 45.5% (5/11) and A 16.7% (1/6). There were no significant differences in calcium among groups A, B and C. In rat implants, the calcium of group B was much lower than that of A or C (B = 6.92 +/- 4.46 vs A = 144.52 +/- 27.66 or C = 240.54 +/- 13.47, P < 0.05) although its histology showed more severe degeneration and inflammatory changes. Pericardial mitral valves treated with glycerol show satisfactory biocompatibility with regard to host endothelial growth and prevention of calcification; however, these tissues show evidence of rapid degeneration.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous host endothelial growth on bioprostheses. Influence of fixation

BACKGROUND

Neither homografts nor bioprostheses have previously been seen to acquire a host endothelium. We previously reported a direct relation between aldehyde tanning and bioprosthesis calcification and the absence of calcification in the absence of aldehyde.

METHODS AND RESULTS

Bovine pericardium was 1) treated with 0.625% glutaraldehyde and stored in 4% formaldehyde, 2) treated with 99.5% glycerol, and 3) treated with 99.5% glycerol and stored in formaldehyde (0.25-4%). The treated pericardium was used to construct stentless mitral valve prostheses (of a single pattern) that were implanted in weanling sheep. After the animals were killed, a strip of anterior cusp from annulus to papillary muscle was processed and examined by scanning electron microscopy for the presence of host endothelial growth. Avoidance of aldehyde allowed host endothelial growth in all cases (six of six), and pure aldehyde treatment inhibited growth in five of six animals. Exposure to aldehyde after glycerol treatment interfered with endothelialization significantly; after longer periods of implantation, however, endothelial growth occurred almost invariably in this group (12 of 13 implanted longer than 200 days). For this group, there was a statistically significant difference for duration of implantation between the valves that grew endothelium and those that did not (218.4 +/- 61.9 versus 128.5 +/- 65.4 days).

CONCLUSIONS

Aldehyde treatment inhibits endothelial growth. With glycerol treatment, growth is uniformly present. Limited exposure to aldehydes after glycerol treatment inhibits endothelial growth, but this effect was ameliorated by prolonged implantation. The possibility of host endothelium-covered, noncalcifying bioprostheses is now real.

Vasopressin decreases immunogold labeling of apical actin in the toad bladder granular cell

Studies with the confocal microscope have shown that arginine vasopressin (AVP) depolymerizes F-actin in the apical region of the toad bladder granular cell. However, the resolution of the fluorescence microscope is not great enough to reveal the exact pattern of depolymerization or the relative extent to which microvillar and subapical membrane actin pools contribute to overall depolymerization. We have developed an electron microscopic immunogold method that shows a significant decrease in immunogold labeling of actin in the region just below the apical membrane, with the decrease most pronounced in regions adjacent to the microvilli. There was no significant change of immunogold labeling within the microvilli themselves. Our studies show a reorganization of the actin cytoskeleton in the region of the granular cell, where water channel-carrying vesicles are positioned and fuse in response to AVP.

Two-dimensional mechanical and ultrastructural correlates of bovine pericardium for prosthetic valves

Scanning electron microscopy of bovine pericardium (BP) shows anisotropic collagen fiber orientation (CFO). We studied the effect of CFO on the breaking strength of longitudinal (L) and transverse (T) strips cut from six pieces of fresh (Fr), glutaraldehyde (Glu)-, or formaldehyde (For)-fixed BP loaded at constant rate until rupture. Maximum tensile stress (Stmax) and strain (Snmax) were measured. The Stmax of L strips were larger than T ones in all groups, and Snmax was the same. Similar results were also observed in 10 pieces of Glu fixed normal canine mitral valves (MV). Maximum tensile stress is obtained when the load is parallel to CFO in both canine MV and BP.

Membrane knobs are required for the microcirculatory obstruction induced by Plasmodium falciparum-infected erythrocytes

We have studied the pathophysiology of the vascular obstruction induced by Plasmodium falciparum-parasitized erythrocytes with the use of an ex vivo microcirculatory preparation perfused with red cells infected with knobless and knobby clones of the FCR-3 strain. We find that parasitized erythrocyte membrane knobs are indispensable for the generation of the circulatory obstruction. Uninfected erythrocytes incubated in culture and erythrocytes infected with early or late forms of the knobless clones or the early forms of the knobby clone all failed to obstruct the microcirculation, although exhibiting various effects on bulk viscosity and peripheral resistance during flow. In contrast, late forms of the knobby clone produced significantly higher peripheral resistance during flow and significant obstruction as detected by changes in time of pressure flow recovery as well as by direct videorecorded microscopic observation. Optical and electron microscopy showed that the adherence of parasitized cells to the endothelium was limited to the venules and involved the knobs in junctions. In addition, we were able to follow the sequence of events during obstruction: initial red-cell adherence to the venular endothelium (sometimes only transitory) followed by progressive recruitment at the venule surface, finally leading to total obstruction that involved parasitized and nonparasitized erythrocytes. Sometimes, retrograde aggregation would extend the obstruction to the capillaries or even precapillary arterioles. These results show that knobs are necessary and sufficient to produce vascular obstruction and that other factors (spleen, immunological, etc.) can only have a modulating role. These results also exclude the possibility that the exclusive adherence to venules is the consequence of "plasma factors" found in the malaric patients.