Integration and differentiation of human embryonic stem cells transplanted to the chick embryo.

Human embryonic stem (ES) cells are pluripotent cells that can differentiate into a large array of cell types and, thus, hold promise for advancing our understanding of human embryology and for contributing to transplantation medicine. In this study, differentiation of human ES cells was examined in vivo by in ovo transplantation to organogenesis-stage embryos. Colonies of human ES cells were grafted into or in place of epithelial-stage somites of chick embryos of 1.5 to 2 days of development. The grafted human ES cells survived in the chick host and were identified by vital staining with carboxyfluorescein diacetate or use of a green fluorescent protein-expressing cells. Histologic analysis showed that human ES cells are easily distinguished from host cells by their larger, more intensely staining nuclei. Some grafted cells differentiated en masse into epithelia, whereas others migrated and mingled with host tissues, including the dorsal root ganglion. Colonies grafted directly adjacent to the host neural tube produced primarily structures with the morphology and molecular characteristics of neural rosettes. These structures contain differentiated neurons as shown by beta-3-tubulin and neurofilament expression in axons and cell bodies. Axons derived from the grafted cells penetrate the host nervous system, and host axons enter the structures derived from the graft. Our results show that human ES cells transplanted in ovo survive, divide, differentiate, and integrate with host tissues and that the host embryonic environment may modulate their differentiation. The chick embryo, therefore, may serve as an accessible and unique experimental system for the study of in vivo development of human ES cells.     

Intimal hyperplasia and coronary flow reserve after heart transplantation: association with big endothelin-1

BACKGROUND: Endothelin, a peptide with strong vasoconstrictive and mitogenic properties, has been found to increase after cardiac transplantation. We therefore assessed the association between its precursor peptide, big endothelin-1, and intimal hyperplasia and coronary flow reserve after heart transplantation. METHODS: Thirty-five patients without hemodynamically significant coronary artery disease after heart transplantation were investigated: Average peak flow velocity in the left anterior descending artery (LAD) was assessed by intracoronary Doppler at baseline as well as after injection of adenosine; coronary flow reserve was calculated as a ratio of both and was corrected for patient age and baseline average peak flow velocity. Lumen, intima + media and total vessel area were measured by intracoronary ultrasound. The plasma concentration of big endothelin-1 in venous blood was determined by radioimmunoassay. RESULTS: Patients with elevated big endothelin-1 levels (>2 fmol/ml) tended to have a decreased corrected coronary flow reserve (2.60 +/- 0.9 vs 3.21 +/- 1.0, p = 0.078). They also had a significantly larger intima + media area (5.82 +/- 2.9 vs 2.37 +/- 2.9 mm(2), p = 0.004) and total vessel area (18.36 +/- 5.8 vs 12.81 +/- 4.8 mm(2), p = 0.012) than those with normal plasma concentrations. CONCLUSIONS: Our study suggests an association between elevated big endothelin-1 plasma levels and the development of intimal hyperplasia and reduction of coronary flow reserve after cardiac transplantation.     

Influence of Lung Aeration on Pulmonary Concentrations of Nebulized and Intravenous Amikacin in Ventilated Piglets with Severe Bronchopneumonia

Background: Pulmonary concentrations of aminoglycosides administered intravenously are usually low in the infected lung parenchyma. Nebulization represents an alternative to increase pulmonary concentrations, although the obstruction of bronchioles by purulent plugs may impair lung deposition by decreasing lung aeration.

Methods: An experimental bronchopneumonia was induced in anesthetized piglets by inoculating lower lobes with a suspension of 106 cfu/ml Escherichia coli. After 24 h of mechanical ventilation, 7 animals received two intravenous injections of 15 mg/kg amikacin, and 11 animals received two nebulizations of 40 mg/kg amikacin at 24-h intervals. One hour following the second administration, animals were killed, and multiple lung specimens were sampled for assessing amikacin pulmonary concentrations and quantifying lung aeration on histologic sections.

Results: Thirty-eight percent of the nebulized amikacin (15 mg/kg) reached the tracheobronchial tree. Amikacin pulmonary concentrations were always higher after nebulization than after intravenous administration, decreased with the extension of parenchymal infection, and were significantly influenced by lung aeration: 197 +/- 165 versus 6 +/- 5 [mu]g/g in lung segments with focal bronchopneumonia (P = 0.03), 40 +/- 62 versus 5 +/- 3 [mu]g/g in lung segments with confluent bronchopneumonia (P = 0.001), 18 +/- 7 versus 7 +/- 4 [mu]g/g in lung segments with lung aeration of 30% or less, and 65 +/- 9 versus 2 +/- 3 [mu]g/g in lung segments with lung aeration of 50% or more.     

Acute recognition and management of congestive heart failure

The acute recognition and management of CHF is challenging. A basic understanding of the determinants of cardiac performance and myocardial O2 consumption along with the pathophysiology of CHF is essential knowledge for the physician undertaking to treat this serious disorder. The basic value of the patient history and physical examination along with assessment of noninvasive tests remains unquestioned, but in addition much relevant and sophisticated information can be gained by invasive hemodynamic monitoring. The cardiopulmonary profile generated by such monitoring allows the physician to use specific hemodynamic and circulatory data for the purpose of manipulating these variables favorably for the heart and circulation. A wide array of therapeutic options is currently available, but, in general, respiratory support and pharmacotherapy are the mainstays of treatment. The traditional agents like digitalis and diuretics have assumed a lesser role during the last decade because of the availability of potent new vasodilator and inotropic agents. In addition, certain mechanical, procedural, and surgical options can be used if circumstances are urgent. In the final analysis, physicians who manage these patients must possess strong cognitive skills but also the clinical reflexes to carry them out: for every hemodynamic and circulatory action, they must be prepared to counter quickly and decisively with a clinical reaction which utilizes these principles to optimize cardiac function. It is hoped that the strategies presented in this article will allow them to perform in such a manner.     

Complement component C5a predicts restenosis after superficial femoral artery balloon angioplasty.

PURPOSE: To investigate whether balloon angioplasty of the superficial femoral artery (SFA) increases serum levels of C5a and whether C5a predicts risk of restenosis. METHODS: C5a antigen was measured at baseline and 8 hours after intervention in 131 consecutive patients (76 women; median age 72 years) with intermittent claudication who underwent successful primary SFA balloon angioplasty. Patients were followed for a median 10 months [interquartile range (IQR) 6 to 14] for the occurrence of >50% restenosis by duplex ultrasound. RESULTS: Median C5a levels increased significantly from 39.7 ng/mL (IQR 27.8 to 55.0) at baseline to 53.8 ng/mL (IQR 35.6 to 85.1, p<0.001) 8 hours post intervention. During the follow-up period, 70 (53%) patients developed restenosis. Increasing levels of C5a (quartiles) at baseline were significantly associated with an increased risk for restenosis (p=0.0092). Adjusted hazard ratios (95% confidence intervals) for restenosis with increasing quartiles of baseline serum C5a levels were 1.24 (0.60 to 2.58), 1.93 (0.95 to 3.93), and 2.08 (1.02 to 4.21), respectively, compared to the lowest quartile. This effect was independent of nonspecific inflammation as reflected by plasma levels of C-reactive protein. CONCLUSION: Inflammatory mechanisms play a major role in the development of restenosis after angioplasty. The complement component C5a exerts strong chemotactic and proinflammatory effects. Enhanced complement activation prior to PTA, as measured by higher levels of C5a, was significantly associated with restenosis after SFA balloon angioplasty. Pathways of complement inhibition thus may be worth investigating with respect to improving patency rates.     

A method of repair for quadriceps tendon or patellar ligament (tendon) ruptures without cast immobilization. Preliminary report

The quadriceps tendon and patellar tendon (ligament) were repaired with a Dacron vascular graft used as a tension suture material. In cases of quadriceps tendon ruptures, the Dacron graft is passed transversely through the patellar ligament just below the patella and crossed transversely at the level of the musculotendinous junction with two loops applying tension to the tendon, which brings the tendon ends together by creating a solid structure. In cases of patellar ligament ruptures, the Dacron graft is passed through a hole in the tibia posteriorly to the tibial tuberosity instead of through the patellar ligament below the patella. This technique enables early mobilization on the first day after surgery. The technique was first tested on six dogs with severed quadriceps tendons and patellar ligaments that were repaired with this suture method. All of the animals recovered from surgery and walked and ran normally on the repaired legs within 27 days and with only mild limping after 17 days. The technique was then used on six patients, four with complete quadriceps tendon rupture and two with complete tear (avulsion) of the patellar ligament (tendon). In all of the patients, excellent surgical results were obtained and leg immobilization was virtually eliminated. Physical therapy was prescribed the first day after surgery. The rehabilitation period was significantly reduced.     

COSTING ACUTE MYOCARDIAL INFARCTION IN NEW SOUTH WALES,AUSTRALIA, BASED ON INCIDENCE RATHER THAN PREVALENCE METHODS

Estimating the economic costs of a disease is an important prerequisite to determining the costs and benefits of various preventive programs. For preventive programs, incidence-based costing is a more appropriate means of estimation than is prevalence-based costing. In this study the cost of acute myocardial infarction (AMI) in New South Wales has been estimated using an incidence-based approach. The calculated cost of AMI in 1979 was $301.0 million, made up of $32.3 million as direct costs and $268.7 million as indirect costs. In a sensitivity analysis, the cost was shown to be most sensitive to the incidence of AMI, the discount rate, and the assumption of a wage for housework. Both the direct costs and indirect costs per case are substantially higher in the United States than in Australia, and this reflects higher physician charges, higher hospital costs, and in the case of indirect costs, higher average weekly earnings.     

Visual acuity with reversed-contrast charts: I. Theoretical and psychophysical investigations.

When the contrast polarity of a visual acuity chart is reversed by using bright letters on a dark background instead of dark on light, the shape and height of the resolution feature in the retinal image is identical but inverted compared with the normal situation. However, the contrast is different in the two cases because the background light level, which is a dividing factor when contrast is calculated, is much less when only the letters are bright. To the extent that contrast is a limiting factor in visual acuity, reversed-contrast acuity would be expected to be better, and proportionally more so in eyes where light scatter and aberrations widen and flatten the point-spread function. In a careful psychophysical study of Landolt C resolution, the minimum angle of resolution was found to be significantly smaller for white letters on a dark background than for the traditional dark on bright situation.