Mapping of neural pathways that influence diaphragm activity and project to the lumbar spinal cord in cats.

During breathing, the diaphragm and abdominal muscles contract out of phase. However, during other behaviors (including vomiting, postural adjustments, and locomotion) simultaneous contractions are required of the diaphragm and other muscle groups including abdominal muscles. Recent studies in cats using transneuronal tracing techniques showed that in addition to neurons in the respiratory groups, cells in the inferior and lateral vestibular nuclei (VN) and medial pontomedullary reticular formation (MRF) influence diaphragm activity. The goal of the present study was to determine whether neurons in these regions have collateralized projections to both diaphragm motoneurons and the lumbar spinal cord. For this purpose, the transneuronal tracer rabies virus was injected into the diaphragm, and the monosynaptic retrograde tracer Fluoro-Gold (FG) was injected into the Th13-L1 spinal segments. A large fraction of MRF and VN neurons (median of 72 and 91%, respectively) that were infected by rabies virus were dual-labeled by FG. These data show that many MRF and VN neurons that influence diaphragm activity also have a projection to the lumbar spinal cord and thus likely are involved in coordinating behaviors that require synchronized contractions of the diaphragm and other muscle groups.

Post-exercise heart rate recovery in HIV-positive individuals on highly active antiretroviral therapy. Early indicator of cardiovascular disease?

BACKGROUND: HIV infection and its treatment, specifically protease inhibitor (PI) therapy, have been associated with an increased risk for cardiovascular disease. Heart rate recovery (HRR) following peak exercise is predictive of future cardiovascular events and mortality in the general population. Nothing is known regarding HRR in individuals infected with HIV on highly active antiretroviral therapy (HAART). SUBJECTS AND METHODS: HIV-positive subjects on HAART that included a PI (HIV+PI, n=19), HIV-positive subjects on HAART that did not include a PI (HIV+noPI, n=19) and HIV-seronegative age, gender and body mass index (BMI) matched controls (Cntl, n=15) underwent a graded maximal exercise test on a cycle ergometer to volitional exhaustion. A continuous electrocardiogram was recorded and HRR was monitored every 30 s for 2 min post exercise. RESULTS: HRR at 1.5 and 2 min was significantly delayed in HIV-positive subjects both on and not on PI-based HAART compared with controls (P<0.01). CONCLUSION: HRR is impaired in HIV-positive individuals on HAART, whether or not the HAART includes a PI, compared with age, gender, BMI, and activity level matched HIV-seronegative controls. Abnormal HRR may reflect cardio-autonomic dysfunction and may be an independent risk factor for future cardiac events in HIV-positive individuals that receive HAART.

Improved growth factor directed vascularization into fibrin constructs through inclusion of additional extracellular molecules.

Using the chick chorioallantoic membrane assay (CAM) and a novel histological technique, we investigated the ability of blood vessels to directly invade fibrin-based scaffolds. In our initial experiments utilizing vascular endothelial growth factor (VEGF(165)), we found no direct invasion. Instead, the fibrin was completely degraded and replaced with highly vascularized new tissue. Addition of fibroblast growth factor-2 (FGF-2), bone morphogenic protein-2 (BMP-2), or platelet-derived growth factor-BB (PDGF-BB) to the fibrin construct also did not result in construct vascularization. Because natural and regenerating tissues exhibit complex extracellular matrices (ECMs), we hypothesized that a more complex scaffold may improve blood vessel invasion. Addition of fibronectin, hyaluronic acid, and collagen type I within 20 mg/mL fibrin constructs resulted in no significant improvement. However, the same additive concentrations within 10 mg/mL fibrin constructs resulted in dramatic improvements, specifically with hyaluronic acid. Overall, we believe that these results indicate the importance of structural and functional cues of not only in the initial scaffold but also as the construct is degraded and remodeled. Furthermore, the CAM assay may represent a useful model for understanding ECM interactions as well as for screening and designing tissue-engineered scaffolds.

Cardiac magnetic resonance imaging abnormalities in systemic lupus erythematosus: a preliminary report.

The purpose of this prospective, pilot study was to determine whether differences in myocardial T2 relaxivity can be identified among active systemic lupus erythematosus (SLE) patients with clinically suspected SLE myocarditis, other active SLE patients, inactive SLE patients and age and gender matched controls. Eleven consecutive female patients (six with active SLE and five with inactive SLE), and five age, gender and race matched healthy controls underwent imaging with echocardiography and cardiac magnetic resonance imaging (MRI). Echocardiographic measurements included left ventricular end diastolic (LVEDV) and end systolic volumes (LVESV), and mass (LVM) (all indexed to body mass); ejection fraction and cardiac output. The cardiac MRI measurement was the T2 relaxation time (an index of soft tissue signal, with higher levels suggestive of increased tissue water content). Patients with active SLE had significantly higher LVEDV and LVM than inactive SLE patients and healthy controls, and significantly larger LVESV than healthy controls. Myocardial T2 relaxation times were significantly higher in patients with active SLE compared to those with inactive SLE and to healthy controls, and remained higher even after excluding the two active SLE patients who had clinical myocarditis. The four active SLE patients who underwent repeat cardiac imaging studies after clinical improvement showed normalization of these myocardial abnormalities. The conclusion was that active SLE patients demonstrate abnormalities in myocardial structure manifested by high myocardial T2 relaxation times that normalized after clinical improvement in disease activity. These findings suggest that T2 relaxation values are a sensitive indicator of myocardial disease in patients with SLE and that myocardial T2 relaxation abnormality frequently occur in patients with active SLE, even in the absence of myocardial involvement by clinical criteria.

Properties of new, long-wavelength, voltage-sensitive dyes in the heart.

Membrane potential measurements using voltage-sensitive dyes (VSDs) have made important contributions to our understanding of electrophysiological properties of multi-cellular systems. Here, we report the development of long wavelength VSDs designed to record cardiac action potentials (APs) from deeper layers in the heart. The emission spectrum of styryl VSDs was red-shifted by incorporating a thienyl group in the polymethine bridge to lengthen and retain the rigidity of the chromophore. Seven dyes, Pittsburgh I to IV and VI to VIII (PGH I-VIII) were synthesized and characterized with respect to their spectral properties in organic solvents and heart muscles. PGH VSDs exhibited 2 absorption, 2 excitation and 2 voltage-sensitive emission peaks, with large Stokes shifts (> 100 nm). Hearts (rabbit, guinea pig and Rana pipiens) and neurohypophyses (CD-1 mice) were effectively stained by injecting a bolus (10-50 microl) of stock solution of VSD (2-5 mM) dissolved in in dimethylsulfoxide plus low molecular weight Pluronic (16% of L64). Other preparations were better stained with a bolus of VSD (2-5 mM) Tyrode's solution at pH 6.0. Action spectra measured with a fast CCD camera showed that PGH I exhibited an increase in fractional fluorescence, DeltaF/F = 17.5 % per AP at 720 nm with 550 nm excitation and DeltaF/F = - 6% per AP at 830 nm with 670 nm excitation. In frog hearts, PGH1 was stable with approximately 30% decrease in fluorescence and AP amplitude during 3 h of intermittent excitation or 1 h of continuous high intensity excitation (300 W Xe-Hg Arc lamp), which was attributed to a combination of dye wash out > photobleaching > dynamic damage > run down of the preparation. The long wavelengths, large Stokes shifts, high DeltaF/F and low baseline fluorescence make PGH dyes a valuable tool in optical mapping and for simultaneous mapping of APs and intracellular Ca(2+).

Tissue Doppler imaging: a useful echocardiographic method for the cardiac sonographer to assess systolic and diastolic ventricular function.

Tissue Doppler imaging (TDI) has evolved to become a useful noninvasive method that can complement other echocardiographic techniques in the assessment of left ventricular myocardial velocities in a variety of clinical conditions. Color 2-dimensional and color M-mode TDI are used for quantification of systolic myocardial velocities during myocardial ischemia at rest and with pharmacologic stress testing. Spectral pulsed TDI can provide measurements of regional systolic and diastolic myocardial velocities, and it is particularly useful in the identification of abnormalities of left ventricular diastolic relaxation. This review summarizes the clinical applications of TDI to promote understanding of its utility in the evaluation of left ventricular myocardial function.

Licensure of the cardiac sonographer: an overview of issues and activities.

The impact of echocardiography on the continuum of cardiovascular health care is well established. Ongoing concerns regarding costs, accessibility, quality, and appropriateness of services rendered by practitioners of echocardiography have prompted various legislative proposals and regulatory policies from government, medical professional groups, and health plans. Specifically, there continues to be a drive to enact law for licensure of sonographers. These activities require continuing advocacy for the profession with active leadership. As part of its mission statement, the American Society of Echocardiography (ASE) states, "ASE strives to be a leader in public policy in order to create a favorable environment for excellence in the practice of echocardiography." As such, the ASE is committed to an increase in their interaction with legislators, payers, and policy makers. This article describes the historical perspective of state, federal, and provincial sonographer licensure issues to provide an understanding of the political perspectives.

Fumonisin B(1) is hepatotoxic and nephrotoxic in milk-fed calves.

Fumonisins are a group of mycotoxins that alter sphingolipid biosynthesis and induce leukoencephalomalacia in horses and pulmonary edema in pigs. Experimental administration of fumonisin induces hepatotoxicity in all species, including cattle, as well as nephrotoxicity in rats, rabbits, and sheep. We investigated the hepatotoxicity and nephrotoxicity of fumonisin B(1) to calves. Ten milk-fed male Holstein calves aged 7 to 14 days were instrumented to obtain blood and urine. Treated calves (n = 5) were administered fumonisin B(1) at 1 mg/kg, iv, daily and controls (n = 5) 10 ml 0.9% NaCl, iv, daily until euthanized on day 7. Fumonisin B(1)-treated calves were lethargic and had decreased appetite from day 4 onward, serum biochemical evidence of severe liver and bile duct injury, and impaired hepatic function. Treated calves also had biochemical evidence of renal injury that functionally involved the proximal convoluted tubules. Sphinganine and sphingosine concentrations in liver, kidney, lung, heart, and skeletal muscle were increased in treated calves. Sphinganine, but not sphingosine, concentration was increased in brains of treated calves. In fumonisin B(1)-treated calves, hepatic lesions were characterized by disorganized hepatic cords, varying severity of hepatocyte apoptosis, hepatocyte proliferation, and proliferation of bile ductular cells. Renal lesions in treated calves consisted of vacuolar change, apoptosis, karyomegaly, and proliferation of proximal renal tubular cells, as well as dilation of proximal renal tubules, which contained cellular debris and protein. This is the first report of fumonisin B(1)-induced renal injury and organ sphingolipid alterations in cattle.

Guidelines for cardiac sonographer education: recommendations of the American Society of Echocardiography Sonographer Training and Education Committee.

In 1992, the American Society of Echocardiography published a report of the Sonographer Education and Training Committee's recommendations for education of sonographers who perform echocardiographic procedures. Since the publication of the original document, there has been continual progress in technology with the development of more sophisticated diagnostic applications that allow more information to be obtained from echocardiographic procedures. These recent changes in the clinical application of echocardiography should be included in all cardiac sonographer education programs. The American Society of Echocardiography, a professional society that currently represents approximately 2500 cardiac sonographers, provides these updated guidelines.

Optical filter sets for multiparameter flow cytometry.

One of the most important components of a fluorescence detection system, the optical filter set selects wavelengths of light for fluorophore excitation and fluorescent signal discrimination. Of the variety of optical devices available for wavelength selection, optical filters have gained wide acceptance because of their wavelength selectivity, ease of installation, and relative inexpensiveness. This unit discusses the properties, compositions, and uses of optical filters in flow cytometry. The information should allow investigators to select quality filters for modifying systems for new dyes and multicolor analyses.

Optical filtering systems for wavelength selection in light microscopy.

Because of its sensitivity and specificity, fluorescence-based detection is one of the foremost methods for microscopic imaging of biological tissues and cells. Dramatic improvements in filter system design and implementation coupled with development of an ever-widening range of sensitive fluorescent dyes have made multicolor imaging a powerful tool for structural and functional analysis. This revised and expanded unit reviews some of the main principles and developments of optical filtering.

Congestive heart failure and the role of two-dimensional Doppler echocardiography: a primer for cardiac sonographers.

Congestive heart failure (CHF) has been an increasing cause of hospitalization, particularly among the elderly population, although the clinical presentation may vary in the individual patient. Two-dimensional and pulsed Doppler echocardiography can be valuable diagnostic methods for the assessment of afflicted patients and can have an impact on patient outcome. The unique advantage of echocardiographic techniques is their ability to characterize left ventricular systolic performance and diastolic filling abnormalities that are commonly present in patients with CHF. This review provides current information the cardiac sonographer can recognize in the assessment of patients with CHF.

The profession of cardiac sonography and the status of professionalization of cardiac sonographers.

The role of the cardiac sonographer has evolved in the profession of cardiac ultrasonography to a level requiring rigorous education, training, and high standards. Although we want to consider ourselves professionals, further efforts are necessary to meet the various criteria conferring such a status. It is essential cardiac sonographers realize these necessary steps to achieve recognition as professionals.

Potential utility of left heart contrast agents in diagnosis of myocardial rupture by 2-dimensional echocardiography.

This case illustrates the use of intravenous injections of a contrast agent during 2-dimensional echocardiography in a patient with myocardial rupture after myocardial infarction. Intravenous injections of echocardiographic contrast agents may have potential use in the identification of intrapericardial hemorrhage after myocardial infarction caused by myocardial rupture or development of ventricular pseudoaneurysm.