Quantitative changes in mast cell populations after left ventricular assist device implantation

Mast cells have been implicated as important in tissue remodeling and fibrosis. We investigated the effect of mechanical ventricular unloading upon myocardial fibrosis and cardiac mast cell density in patients undergoing left ventricular assist device (LVAD) implantation. Paired myocardial tissue samples were obtained from 30 patients with end-stage cardiomyopathy at the time of LVAD implantation and at the time of removal and were compared with samples taken from donor hearts. Tissue sections were stained and quantitated for mast cells and myocardial fibrosis. Mast cell density (tryptase positive cells) in cardiomyopathy was higher than that in donor hearts (33.5 +/- 3.6 SEM cells/10 fields vs.15.2 +/- 2.0 SEM cells/10 fields respectively, p = 0.04) and was lower than LVAD supported hearts (33.5 +/- 3.6 SEM cells/10 fields vs. 49.8 +/- 5.7 SEM cells/10 fields respectively, p = 0.01). Mast cells are primarily localized in areas of increased interstitial fibrosis adjacent to myocardial cells and not vessels. There was statistically significant correlation between mast cells and interstitial collagen (p = 0.03) in patients before LVAD implantation that did not persist after mechanical support (p = 0.18). These results suggest that mechanical support with left ventricular assist devices induces an increase in mast cell number in the myocardium and an associated decrease in myocardial fibrosis. We believe these data demonstrate a dual role for cardiac mast cells in the increase in fibrosis in heart failure and the decrease after LVAD and its associated cardiac improvement.     

An R-wave Simulator for Testing and Calibrating Heart Rate Amplification and Processing Systems

A simple, inexpensive device described here will produce a spike whose amplitude, shape, and output impedance are similar to those of the human QRS complex. Several reliable spike rates can be selected.     

Antitumor efficacy of regional oncolytic viral therapy for peritoneally disseminated cancer

Oncolytic viral therapy is a promising new method of cancer treatment. Peritoneal dissemination of cancer is a common and fatal clinical condition seen in many malignancies, with few effective therapies available. G207, a multimutated replication-competent herpes simplex virus type-1, effectively treats disseminated peritoneal cancer. This study evaluates viral proliferation and subsequent tumoricidal effects in vitro and in vivo after regional viral delivery. In vitro studies demonstrate that G207 efficiently kills five human gastric cancer cell lines, and that permissiveness to viral replication is correlated with cytotoxicity. In a murine xenograft model of human gastric carcinomatosis, peritoneal delivery of G207 effectively kills tumor and prolongs survival. Data from quantitative PCR characterizes peritoneal clearance of virus after intraperitoneal injection, and identifies G207 replication within tumor cells in vivo, similar to in vitro proliferation. Further analysis of various organs confirms that G207 does not replicate within normal tissue after peritoneal delivery. Wild-type KOS viral replication was also demonstrated in vivo, with significant toxicity secondary to dissemination and encephalitis. In vivo viral proliferation of G207 is restricted to tumor cells, is correlated with in vitro assays, and is an important mechanism of anticancer efficacy.     

Comparative genomic hybridization analysis of primary colorectal carcinomas and their synchronous metastases

We have analyzed 26 tumors from 12 patients with metastatic colorectal adenocarcinoma by comparative genomic hybridization (CGH). Primary tumors and their lymph node metastases from five Dukes' C patients as well as primary tumors and their liver metastases from seven Dukes' D patients were used to assess the extent of genetic differences between primary and secondary colorectal carcinomas from the same patients, to calculate the degree of clonal divergence and genetic heterogeneity in metastatic colorectal cancer, and to determine the differences in genetic imbalances between Dukes' C and D stage tumors. We show that the same genetic aberrations were frequently found in the primary tumors and their metastases. However, metastases often contained genetic aberrations not found in the corresponding primary tumors. The comparison of Dukes' stages C and D revealed genetic aberrations common to both. However, reduced copy number of chromosome arm 17p (5/5 vs. 0/7; P = 0.001) was significantly associated with Dukes' stage C and lymph node metastases, while increased copy number of chromosome arms 6p (6/7 vs. 0/5; P = 0.007) and 17q (5/7 vs. 0/5; P = 0.027) was associated more with Dukes' stage D and liver metastases. Our results established a repertoire of chromosomal alterations associated with metastatic colorectal cancer and suggest that Dukes' C (lymph node metastasis) tumors are not always simply an earlier stage of Dukes' D (liver metastasis) tumors and, thus, in some instances at least, they are distinct forms of the disease.     

Effects of affirmative action in medical schools. A study of the class of 1975

In the early 1970s, affirmative-action programs were introduced to accomplish a number of social goals, including increasing the supply of minority physicians and improving the health care of the poor. To assess the success of such programs, we analyzed data on people who graduated from U.S. medical schools in 1975 to determine how specialty choice, practice locations, patient populations served, and board-certification rates differ between minority and nonminority graduates. A larger proportion of minority graduates (55 per cent vs. 41 per cent, P less than 0.001) chose the primary-care specialties of family practice, general internal medicine, general pediatrics, and obstetrics-gynecology. Significantly more minority physicians (12 per cent vs. 6 per cent, P less than 0.01) practiced in locations designated as health-manpower shortage areas by the federal government and had more Medicaid recipients in their patient populations (31 per cent for blacks, 24 per cent for Hispanics, 14 per cent for whites; P less than 0.001). Physicians from each racial or ethnic group served disproportionately more patients of their own racial or ethnic group (P less than 0.001), but minority physicians did not serve significantly more persons from other racial or ethnic minority groups than did nonminority physicians. Many minority physicians served patient populations much like those of their nonminority colleagues, which indicates that substantial integration of the medical marketplace has taken place. Significantly fewer minority graduates had become board-certified by 1984 (48 per cent vs. 80 per cent, P less than 0.001), and most of this disparity was associated with differences in premedical-school characteristics and in the patient populations they served. Our analysis shows that minority graduates of the medical school class of 1975 are fulfilling many of the objectives of affirmative-action programs.     

Collegiate Athletic Trainers' Confidence in Helping Female Athletes With Eating Disorders

OBJECTIVE: To examine college athletic trainers' confidence in helping female athletes who have eating disorders. DESIGN AND SETTING: We mailed a 4-page, 53-item survey to head certified athletic trainers at all National Collegiate Athletic Association Division IA and IAA institutions (N = 236). A 2- wave mailing design was used to increase response rate. SUBJECTS: A total of 171 athletic trainers returned completed surveys for a response rate of 77%. Eleven institutions either did not identify their head athletic trainer or did not have an identifiable mailing address. Two surveys were undeliverable because of incorrect mailing addresses. MEASUREMENTS: The survey consisted of 4 subscales: (1) efficacy expectation, (2) outcome expectation, (3) outcome value, and (4) experience in dealing with eating disorders. Content validity was established by review from a national panel of experts. Reliability ranged from.66 to.73 for the subscales. RESULTS: Although virtually all athletic trainers (91%) had dealt with a female athlete with an eating disorder, only 1 in 4 (27%) felt confident identifying a female athlete with an eating disorder, and only 1 in 3 (38%) felt confident asking an athlete if she had an eating disorder. One in 4 athletic trainers (25%) worked at an institution that did not have a policy on handling eating disorders. Almost all athletic trainers (93%) felt that increased attention needs to be paid to preventing eating disorders among collegiate female athletes. CONCLUSIONS: Collegiate athletic programs are encouraged to develop and implement eating-disorder policies. Continuing education on the prevention of eating disorders among athletes is also strongly recommended.     

Differential effects of growth factors on tissue-engineered cartilage

The effects of four regulatory factors on tissue-engineered cartilage were examined with specific focus on the ability to increase construct growth rate and concentrations of glycosaminoglycans (GAG) and collagen, the major extracellular matrix (ECM) components. Bovine calf articular chondrocytes were seeded onto biodegradable polyglycolic acid (PGA) scaffolds and cultured in medium with or without supplemental insulin-like growth factor (IGF-I), interleukin-4 (IL-4), transforming growth factor-beta1 (TGF-beta1) or platelet-derived growth factor (PDGF). IGF-I, IL-4, and TGF-beta1 increased construct wet weights by 1.5-2.9-fold over 4 weeks of culture and increased amounts of cartilaginous ECM components. IGF-I (10-300 ng/mL) maintained wet weight fractions of GAG in constructs seeded at high cell density and increased by up to fivefold GAG fractions in constructs seeded at lower cell density. TGF-beta1 (30 ng/mL) increased wet weight fractions of total collagen by up to 1.4-fold while maintaining a high fraction of type II collagen (79 plus minus 11% of the total collagen). IL-4 (1-100 ng/mL) minimized the thickness of the GAG-depleted region at the construct surfaces. PDGF (1-100 ng/mL) decreased construct growth rate and ECM fractions. Different regulatory factors thus elicit significantly different chondrogenic responses and can be used to selectively control the growth rate and improve the composition of engineered cartilage.     

HLA-B*35-Restricted CD8+-T-Cell Epitope in Mycobacterium tuberculosis Rv2903c

Few human CD8(+) T-cell epitopes in mycobacterial antigens have been described to date. Here we have identified a novel HLA-B*35-restricted CD8(+) T-cell epitope in Mycobacterium tuberculosis Rv2903c based on a reverse immunogenetics approach. Peptide-specific CD8 T cells were able to kill M. tuberculosis-infected macrophages and produce gamma interferon and tumor necrosis factor alpha.     

Molecular Cloning of a 32-Kilodalton Lipoprotein Component of a Novel Iron-Regulated Staphylococcus epidermidis ABC Transporter

Our previous studies identified two iron-regulated cytoplasmic membrane proteins of 32 and 36 kDa expressed by both Staphylococcus epidermidis and Staphylococcus aureus. In this study we show by Triton X-114 phase partitioning and tritiated palmitic acid labelling that these proteins are lipoproteins which are anchored into the cytoplasmic membrane by their lipid-modified N termini. In common with those of some other gram-positive bacteria, these highly immunogenic lipoproteins were released from the bacterial cell into the culture supernatants, with release being promoted by growth of the bacteria under iron-restricted conditions. Immunoelectron microscopy with a monospecific rabbit antiserum to the 32-kDa S. epidermidis lipoprotein showed that the majority of the antigen was distributed throughout the staphylococcal cell wall. Only minor quantities were detected in the cytoplasmic membrane, and exposure of the lipoprotein on the bacterial surface was minimal. A monoclonal antibody raised to the 32-kDa lipoprotein of S. aureus was used in immunoblotting studies to investigate the conservation of this antigen among a variety of staphylococci. The monoclonal antibody reacted with polypeptides of 32 kDa in S. epidermidis and S. aureus and of 40 kDa in Staphylococcus hominis. No reactivity was detected with Staphylococcus lugdunensis, Staphylococcus cohni, or Staphylococcus haemolyticus. The gene encoding the 32-kDa lipoprotein from S. epidermidis has been isolated from a Lambda Zap II genomic DNA library and found to be a component of an iron-regulated operon encoding a novel ABC-type transporter. The operon contains three genes, designated sitA, -B, and -C, encoding an ATPase, a cytoplasmic membrane protein, and the 32-kDa lipoprotein, respectively. SitC shows significant homology both with a number of bacterial adhesins, including FimA of Streptococcus parasanguis and ScaA of Streptococcus gordonii, and with lipoproteins of a recently described family of ABC transporters with proven or putative metal ion transport functions. Although the solute specificity of this novel transporter has not yet been determined, we speculate that it may be involved in either siderophore- or transferrin-mediated iron uptake in S. epidermidis.     

Mechanisms underlying variations in excitation–contraction coupling across the mouse left ventricular free wall

Ca²⁺ release during excitation–contraction (EC) coupling varies across the left ventricular free wall. Here, we investigated the mechanisms underlying EC coupling differences between mouse left ventricular epicardial (Epi) and endocardial (Endo) myocytes. We found that diastolic and systolic [Ca²⁺]_i was higher in paced Endo than in Epi myocytes. Our data indicated that differences in action potential (AP) waveform between Epi and Endo cells only partially accounted for differences in [Ca²⁺]_i. Rather, we found that the amplitude of the [Ca²⁺]_i transient, but not its trigger – the Ca²⁺ current – was larger in Endo than in Epi cells. We also found that spontaneous Ca²⁺ spark activity was about 2.8-fold higher in Endo than in Epi cells. Interestingly, ryanodine receptor type 2 (RyR2) protein expression was nearly 2-fold higher in Endo than in Epi myocytes. Finally, we observed less Na⁺–Ca²⁺ exchanger function in Endo than in Epi cells, which was associated with decreased Ca²⁺ efflux during the AP; this contributed to higher diastolic [Ca²⁺]_i and SR Ca²⁺ in Endo than in Epi cells during pacing. We propose that transmural differences in AP waveform, SR Ca²⁺ release, and Na⁺–Ca²⁺ exchanger function underlie differences in [Ca²⁺]_i and EC coupling across the left ventricular free wall.