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Biomedical subjects

W H Wen

Publications and source records attributed to W H Wen.

At least 19 recordsLinked to original sources
PubMed2001

Alternative and aberrant messenger RNA splicing of the mdm2 oncogene in invasive breast cancer.

mdm2 is part of a complex mechanism that regulates the expression of p53 as well as the function of Rb, p19ARF, and other genes. In humans, mdm2 dysregulation is associated with gene amplification. This study was undertaken to characterize altered mdm2 expression in a cohort of 38 invasive breast cancers and 9 normal breast specimens. Reverse-transcription PCR with primers spanning the entire open reading frame of the mdm2 gene in breast tissue RNA samples generated PCR products of full-length mdm2 (1526 bp) as well as smaller products (653, 281, 254, and 219 bp). Sequence analysis demonstrated that the 653-bp product was an alternatively spliced product (defined as splicing at the exon/intron boundary consensus sites), whereas the 281, 254, and 219 bp mdm2 products were aberrantly spliced products (splicing at sites not considered to be exon/intron boundary sites). Reverse-transcription-PCR with normal breast tissue RNA samples yielded only the 1526-bp product in five samples and the 1526-bp product and the 653-bp product in four samples. The 653-bp alternatively spliced product was expressed in 21% of breast cancers, and the smaller, aberrantly spliced mRNA products (281 bp, 254 bp, and/or 219 bp) were expressed in 16% of breast cancers. The protein products predicted by the alternatively spliced mRNAs and the aberrantly spliced mRNAs lacked either the entire binding domain for p53 or the majority of the binding domain for p53. Immunohistochemical analysis of HER2/neu (c-erbB2), estrogen receptor, progesterone receptor, epidermal growth factor receptor, and p53 protein was performed. p53 sequence alterations were identified by mismatch detection and confirmed by p53 oligonucleotide microarray technology. An association was demonstrated between the expression of aberrantly and/or alternatively spliced mdm2 mRNAs and a lack of progesterone receptor. An association was also demonstrated between mdm2 aberrantly and/or alternatively expression products and the presence of p53 tumor suppressor gene mutations. mdm2 is transcribed from two different promoters: one, p53-dependent, and the other, p53-independent. The 5' untranslated region of the transcripts was evaluated to determine the promoter usage in each breast cancer specimen. No correlation was observed between mdm2 splice products and promoter usage. The presence of aberrant expression products of mdm2 in breast cancer specimens was correlated with a shortened overall patient survival. These observations suggest that mdm2 expression is altered in invasive breast cancer and is associated with more aggressive disease.

5' Untranslated Regions↗
PubMed2001

Conditioned nutritional deficiencies in the cardiomyopathic hamster heart.

BACKGROUND: Evidence indicates that nutritional factors may be important in the maintenance of myocyte structure and energetics. The failing myocardium has been reported to exhibit a depletion of several nutrients that are important for the maintenance of intracellular calcium homeostasis and cellular energetics, and levels of oxidative stress. This nutrient depletion may contribute to the progressive deterioration in myocardial structure and function observed in heart failure. OBJECTIVE: To examine the extent to which advanced cardiomyopathy results in a depletion of nutrients and/or metabolites and antioxidants, and whether supplementation with these nutrients may influence cellular structure or function. SUBJECTS AND METHODS: Cardiomyopathic hamsters were randomly placed to one of the three following diet groups: chow; control gelled diet; or a supplemented gelled diet that provided taurine, carnitine, coenzyme Q10, selenium, vitamins E and C, creatine, thiamine and L-cysteine. After approximately three months of supplementation, one group of hamsters underwent functional testing using a modified Langendorff technique with biopsy samples taken for electron microscopy. Myocardial nutrient concentrations were determined in a second group of diseased and nondiseased hamsters of the same age. RESULTS: Cardiomyopathy resulted in a depletion of vitamin E, creatine, carnitine, taurine and coenzyme Q10. Supplementation resulted in improved cardiac ultrastructure, function and contractility compared with nonsupplemented hamsters. CONCLUSIONS: These studies suggest that heart failure results in 'condition-related nutrient deficiencies' that, once corrected, can significantly impact on heart function and structure.

Animals↗
PubMed2001

Correlation of p53 mutations with resistance to platinum-based chemotherapy and shortened survival in ovarian cancer.

PURPOSE: The p53 tumor suppressor gene plays a central role in cell cycle regulation and induction of apoptosis. We analyzed p53 alterations and their impact on response to chemotherapy and clinical outcome in ovarian cancer patients. EXPERIMENTAL DESIGN: One hundred seventy-eight ovarian carcinomas, snap frozen and stored at -80 degrees C, were analyzed for mutations of the p53 gene (exons 2-11) by single-strand conformation polymorphism and DNA sequencing and for p53 overexpression by immunohistochemistry (monoclonal antibody DO7). RESULTS: p53 mutations were found in 56% (99 of 178) of the tumors, and 62% of these were located in evolutionary highly conserved domains of the gene. Time to progression and overall survival were significantly shortened in patients with p53 mutations compared with wild-type p53 (P = 0.029 and P = 0.014) and patients with mutations in highly conserved domains as opposed to nonconserved domains or wild-type p53 (P = 0.010 and P = 0.007). p53 protein overexpression (>10% positively stained nuclei) was found in 62% (110 of 178). Time to progression and overall survival were shorter in cases with p53 overexpression (cutpoint, 10%: P = 0.071 and P = 0.056) but only marginally significant. Resistance to adjuvant cisplatin or carboplatin chemotherapy was significantly more frequent in patients with p53 overexpression (P = 0.001) or p53 missense mutations (P = 0.008) than patients with normal p53. CONCLUSIONS: p53 alterations correlate significantly with resistance to platinum-based chemotherapy, early relapse, and shortened overall survival in ovarian cancer patients in univariate analysis. In multivariable analysis though, p53 was not an independent prognostic factor.

Aged↗
PubMed2000

Effects of estrogen replacement on infarct size, cardiac remodeling, and the endothelin system after myocardial infarction in ovariectomized rats.

BACKGROUND: Estrogen may increase the long-term survival of women who have suffered from a myocardial infarction (MI). We examined the acute and chronic influence of estrogen on MI in the rat left coronary artery ligation model. METHODS AND RESULTS: Female Sprague-Dawley rats (10 to 12 weeks, n=93), divided into 3 groups (rats with intact ovaries, ovariectomized rats administered 17beta-estradiol [17beta-E(2)] replacement, and ovariectomized rats administered placebo 2 weeks before MI), were randomized to left coronary artery ligation (n=66) or sham-operated (n=27) groups. Ten to 11 weeks after MI, rats were randomly assigned to either (1) assessment of left ventricular (LV) function and morphometric analysis or (2) measurement of cardiopulmonary mRNA expression of preproendothelin-1 and endothelin A and B receptors. Acutely, estrogen was associated with a trend toward increased mortality. Infarct size was increased in the 17beta-E(2) group compared with the placebo group (42+/-2% versus 26+/-3%, respectively; P:=0.01). Chronically, wall tension was normalized through a reduction in LV cavity size with estrogen treatment (419+/-41 mm Hg/mm for 17beta-E(2) versus 946+/-300 mm Hg/mm for placebo, P:=0.039). In the LV, there was a 2.5-fold increase in endothelin B mRNA expression after MI in placebo-treated rats (P:=0.004 versus sham-operated rats) that was prevented in the 17beta-E(2) group (P:=NS versus sham-operated rats). CONCLUSIONS: These results suggest that estrogen is detrimental at the time of MI or early post-MI period, resulting in an increased size of infarct or infarct expansion, but chronically, it can normalize wall tension and inhibit LV dilatation, which may in turn lead to increased long-term survival. Regulation of the endothelin system, particularly the expression of the endothelin B receptor, may contribute to these estrogenic effects.

Animals↗
PubMed2000

Comparison of TP53 mutations identified by oligonucleotide microarray and conventional DNA sequence analysis.

As the rate of gene discovery accelerates, more efficient methods are needed to analyze genes in human tissues. To assess the efficiency, sensitivity, and specificity of different methods, alterations of TP53 were independently evaluated in 108 ovarian tumors by conventional DNA sequence analysis and oligonucleotide microarray (p53 GeneChip). All mutations identified by oligonucleotide microarray and all disagreements with conventional gel-based DNA sequence analysis were confirmed by re-analysis with manual and automated dideoxy DNA sequencing. A total of 77 ovarian cancers were identified as having TP53 mutations by one of the two approaches, 71 by microarray and 63 by gel-based DNA sequence analysis. The same mutation was identified in 57 ovarian cancers, and the same wild type TP53 sequence was observed in 31 ovarian cancers by both methods, for a concordance rate of 81%. Among the mutation analyses discordant by these methods for TP53 sequence were 14 cases identified as mutated by microarray but not by conventional DNA sequence analysis and 6 cases identified as mutated by conventional DNA sequence analysis but not by microarray. Overall, the oligonucleotide microarray demonstrated a 94% accuracy rate, a 92% sensitivity, and an 100% specificity. Conventional DNA sequence analysis demonstrated an 87% accuracy rate, 82% sensitivity, and a 100% specificity. Patients with TP53 mutations had significantly shorter overall survival than those with no mutation (P = 0.02). Women with mutations in loop2, loop3, or the loop-sheet-helix domain had shorter survival than women with other mutations or women with no mutations (P = 0.01). Although further refinement would be helpful to improve the detection of certain types of TPS3 alterations, oligonucleotide microarrays were shown to be a powerful and effective tool for TP53 mutation detection.

Female↗
PubMed2000

The tyrosine kinase p56lck is essential in coxsackievirus B3-mediated heart disease.

Infections are thought to be important in the pathogenesis of many heart diseases. Coxsackievirus B3 (CVB3) has been linked to chronic dilated cardiomyopathy, a common cause of progressive heart disease, heart failure and sudden death. We show here that the sarcoma (Src) family kinase Lck (p56lck) is required for efficient CVB3 replication in T-cell lines and for viral replication and persistence in vivo. Whereas infection of wild-type mice with human pathogenic CVB3 caused acute and very severe myocarditis, meningitis, hepatitis, pancreatitis and dilated cardiomyopathy, mice lacking the p56lck gene were completely protected from CVB3-induced acute pathogenicity and chronic heart disease. These data identify a previously unknown function of Src family kinases and indicate that p56lck is the essential host factor that controls the replication and pathogenicity of CVB3.

Animals↗
PubMed1999

Susceptibility to myocarditis is dependent on the response of alphabeta T lymphocytes to coxsackieviral infection.

Viral myocarditis is an important cause of heart failure and dilated cardiomyopathy. T lymphocytes are implicated in myocardial damage in murine models of coxsackievirus B3 (CVB3) myocarditis. We used knockout mice lacking CD4 (CD4(-/-)), CD8 (CD8(-/-)), both coreceptors (CD4(-/-)CD8(-/-)), or the T-cell receptor beta chain (TCRbeta(-/-)) to address the contribution of T-cell subpopulations to host susceptibility to CVB3 myocarditis. Severity of disease was magnified in CD8(-/-) mice but attenuated in CD4(-/-) mice, consistent with a pathogenic role for CD4(+) lymphocytes. Elimination of both CD4 and CD8 molecules from T lymphocytes by genetic knockout better protected mice from myocarditis, demonstrating that both CD4(+) and CD8(+) T cells contribute to host susceptibility. The same benefit occurred in TCRbeta(-/-) mice, with prolonged survival and minimal myocardial disease observed after CVB3 infection. Elevated interferon-gamma and decreased tumor necrosis factor-alpha expression are associated with attenuated myocardial damage in CD4(-/-)CD8(-/-) mice. These results show that the presence of TCRalphabeta(+) T cells enhances host susceptibility to myocarditis. The severity of myocardial damage and associated mortality are dependent on the predominant T-cell type available to respond to CVB3 infection. One mechanism by which CD4(+) and CD8(+) T-cell subsets influence the pathogenesis of myocarditis may involve specific cytokine expression patterns.

Animals↗
PubMed1999

Tissue expression and immunolocalization of tumor necrosis factor-alpha in postinfarction dysfunctional myocardium.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) is markedly elevated in advanced heart failure. It is not known whether tissue TNF-alpha is elevated in the common setting of myocardial infarction leading to heart failure and what the source of TNF-alpha is. To determine this, we studied the expression and protein localization of TNF-alpha and its 2 main receptors (TNF-R1/R2) in a rat model of large infarction. METHODS AND RESULTS: Male rats were randomized to proximal left anterior descending ligation. The animals were killed on days 1, 3, 10, and 35 after ligation to examine gene expression and protein production of TNF-alpha and TNF-R1/R2 from the infarct, peri-infarct, and contralateral zones of infarcted heart. There was increased TNF-alpha mRNA production throughout the myocardium at day 1, and detectable expression persisted to day 35 after myocardial infarction. The expression of this cytokine is not confined strictly to the infarct or peri-infarct zones but is expressed by cardiac myocytes within the myocardium in the contralateral normal zone. Changes in gene expression are mirrored initially by augmented protein production within the myocytes. Levels of TNF-alpha protein in the infarct and peri-infarct zones rose early to 8- to 10-fold above normal levels and rose to 4- to 5-fold in the contralateral zone. Finally, expression of the TNF-R1 mRNA transcripts was upregulated at days 3 and 10 after ligation in the infarct and peri-infarct zones, suggesting that the signal transduction pathways necessary for TNF-alpha in the heart remain intact as TNF-alpha biosynthesis increases. CONCLUSIONS: TNF-alpha is present early in a model of large myocardial infarction and is sustained into the later stage within the myocardium. Expression of this cytokine is not only confined strictly to the infarct or peri-infarct zone but is expressed by cardiac myocytes within the myocardium contralateral to the infarct. Therefore TNF-alpha production forms a part of an important intrinsic myocardial stress response system to injury.

Animals↗
PubMed1999

Cardiac function and cytotoxic aldehyde production in a murine model of chronic iron-overload.

OBJECTIVES: To determine the relationship between the total chronic dose of iron administered, ex-vivo cardiac function and the concentrations of cytotoxic aldehydes in heart tissue of a murine model. METHODS: In the first experiment, 34 male B6D2F1 mice were randomized to receive intraperitoneal injections of 5, 10 or 20 mg of iron dextran for three weeks, or a placebo control. The mice were subsequently randomized to undergo ex-vivo assessment of cardiac function. In the second experiment, free radical generation, quantified by the presence of 20 separate cytotoxic aldehydes, was assessed in heart tissue of 40 mice that were randomized to receive chronic treatment with various concentrations of iron dextran (100 mg to 300 mg total chronic dose administered), placebo treatment with saline, or no treatment at all (baseline). RESULTS: Iron-loaded groups displayed dose-dependent depressions of heart rate, systolic pressure, developed pressure, coronary pressure, -dP/dt and +dP/dt, and increases in diastolic pressure. Monotonic dose-dependent increases in total heart aldehydes were observed in the iron-treated groups (r-0.97, p < 0.0001), whereas no significant differences were observed between baseline or time-placebo control groups. CONCLUSIONS: While no single mechanism is likely to account for the complex pathophysiology of iron-induced heart failure, our findings show that chronic iron-loading in a murine model results in dose-dependent alterations to cardiac function; and results in free radical mediated damage to the heart, as measured by excess concentrations of cytotoxic aldehyde-derived peroxidation products. This is the first description of the effects of excess iron on cardiac function assessed by an ex-vivo Langendorff technique in a murine model of chronic iron-overload.

Aldehydes↗
PubMed1999

p53 mutations and expression in ovarian cancers: correlation with overall survival.

The p53 gene is altered in approximately 50% of all human malignancies. p53 overexpression, identified by immunohistochemistry, and p53 mutations, identified by single-strand conformational polymorphism (SSCP) and DNA sequencing, have been described in ovarian cancers. p53 overexpression has been correlated with poor outcome for women with ovarian cancer in some studies. With only limited data, the assumption has been made that p53 overexpression corresponds to p53 mutations. The purpose of this investigation was to assess p53 alterations in ovarian cancer to determine if p53 overexpression corresponds with mutations in the p53 gene, and to assess whether either predicts clinical outcome in ovarian carcinoma. Frozen ovarian carcinoma tumor specimens from 105 patients were analyzed by immunohistochemical staining for p53 expression. SSCP was used to screen for mutations and DNA sequencing was used to confirm the specific mutation in exons 2 to 11, encompassing the entire p53 open reading frame. Those ovarian carcinomas identified as wild-type p53 by SSCP were subjected to automated DNA sequence analysis of the entire open reading frame. Relative to DNA sequence analysis, the sensitivity of SSCP was 85% and the specificity was 98%. Immunohistochemical staining demonstrated that 72 of the 105 (69%) cases had positive immunostaining. SSCP and DNA sequencing identified and confirmed mutations in 60 of the 105 carcinomas (57%). Although there was a statistically significant association between p53 immunostaining and p53 mutations (p = 0.0002), false-negative and -positive results were identified. Tumor grade (p = 0.03), stage (p = 0.08), and overall survival (p = 0.15) were moderately associated with positive p53 immunostaining. Patients with p53 mutations and overexpression had shorter overall patient survival (p = 0.02). The findings demonstrated that, individually, p53 mutations and p53 overexpression were each related to shorter patient survival, but the strongest predictor of outcome was a combination of both mutations and overexpression. Comparisons of overall survival for women with mutations in loop 2, loop 3, and the loop-sheet-helix domains together showed a statistically significant difference in survival compared to survival of women whose ovarian cancers had other mutations (p = 0.046).

Adult↗
PubMed1998

A serine elastase inhibitor reduces inflammation and fibrosis and preserves cardiac function after experimentally-induced murine myocarditis.

In viral myocarditis, inflammation and destruction of cardiac myocytes leads to fibrosis, causing progressive impairment in cardiac function. Here we show the etiologic importance of serine elastase activity in the pathophysiology of acute viral myocarditis and the therapeutic efficacy of an elastase inhibitor. In DBA/2 mice inoculated with the encephalomyocarditis virus, a more than 150% increase in myocardial serine elastase activity is observed. This is suppressed by a selective serine elastase inhibitor, ZD0892, which is biologically effective after oral administration. Mice treated with this compound had little evidence of microvascular constriction and obstruction associated with myocarditis-induced ischemia reperfusion injury, much less inflammation and necrosis, only mild fibrosis and myocardial collagen deposition, and normal ventricular function, compared with the infected nontreated group.

Administration, Oral↗
PubMed1998

Chronic endothelin-1 blockade preserves myocardial contractility in dilated cardiomyopathy.

Endothelin-1 (ET-1) is known to have positive inotropic effects in isolated cardiac muscle strips. ET-1 levels are elevated in congestive heart failure (CHF). We investigated the effects of ET-1 on contractility and cardiac relaxation (lusitropy) of the intact healthy murine heart and myocarditic/cardiomyopathic heart by chronic oral treatment with a mixed ETA/ETB blocker SB217242. Chronic ET-1 blockade of normal hearts resulted in depression of contractility and lusitropy of the normal heart but preservation and enhancement of contractility and lusitropy in myocarditic animals, in which ET-1 cardiac content is elevated. This suggests that ET-1 is important in the basal contractility and relaxation of the normal heart but that its chronic elevation in CHF causes impairment of cardiac systolic and diastolic performance.

Animals↗
PubMed1997

WAF1/Cip1 gene polymorphism and expression in carcinomas of the breast, ovary, and endometrium.

The p53 gene is altered in approximately 50% of human cancers and is considered to be important in the pathogenesis of these malignancies. The p53 protein product regulates the transition from G1 to S phase of the cell cycle and entry to the DNA damage repair pathway. As alterations in this pathway appear to be important in a variety of human cancers, downstream effector proteins of p53 are potential sites for somatic alterations. WAF1/Cip1, also known as WAF1, Cip1, sdi1, or CAP20, codes for a 21-kd protein (p21WAF1/Cip1), which was recently described as a universal inhibitor of cyclins and is thus critical in cell cycle control. Mutations in WAF1/Cip1 are potentially important in human malignancies because they could affect the control of the cell cycle. To understand whether mutations of WAF1/Cip1 occur in cancer, we screened 53 cases of invasive breast carcinoma, 35 cases of ductal carcinoma in situ (DCIS), 53 ovarian carcinomas, and 47 endometrial carcinomas in the second exon of WAF1/Cip1 (90% of the open reading frame). p21WAF1/Cip1 expression was characterized with immunohistochemistry. Cells from the blood of 21 normal individuals were also characterized using single-strand conformational polymorphism analysis, DNA sequencing and restriction analysis. Single-strand conformational polymorphism analysis demonstrated an altered mobility pattern for exon 2 in 12 invasive breast cancers (22.6%), 5 DCIS of the breast (14%), 8 invasive ovarian carcinomas (15%), and 9 endometrial carcinomas (19%). In total, 209 samples were screened, and 38 cases (18.2%) had an altered codon 31. Each case with altered single-strand conformational polymorphism, analyzed by DNA sequencing and/or restriction analysis, showed the same alteration of codon 31, a C to A transversion encoding a change in amino acid sequence from serine to arginine (31Ser-->31Arg). DNA from the blood of 21 normal individuals showed the same alteration in WAF1/Cip1 in 4 cases (19%). Furthermore, paired normal tissue was available for 3 of 20 breast carcinomas with the Ser31Arg transversion. Normal DNA from all 3 cases showed the same 31Arg alteration as found in the tumor tissue. These results indicate that codon 31 is a polymorphic site and that the serine to arginine shift is a polymorphism. p21WAF1/Cip1 expression, identified by immunohistochemistry, was found to vary in a pattern that depended both on the tissue type and on the presence or absence of the codon 31 polymorphism. Using pair-wise comparisons in breast DCIS, we found higher protein expression in tumor nuclei as compared with benign stromal cell nuclei (P = 0.002) or normal ductal epithelium (P = 0.005). Invasive breast cancer specimens showed a trend in p21WAF1/Cip1 immunostaining similar to DCIS but did not reach statistical significance (P = 0.12). However, when cases with extensive desmoplastic reaction were excluded, a statistically significant association (P = 0.019) similar to that in DCIS was noted. In contrast to the breast tumors, ovarian carcinomas exhibited significantly greater p21WAF1/Cip1 expression in the benign stromal (fibroblast) nuclei surrounding the tumor than in the carcinoma cell nuclei (P = 0.016). Endometrial carcinoma revealed no difference in staining when comparing benign tissue with carcinoma (P = 0.99); however, unlike breast and ovarian carcinomas in which there was no correlation between p21WAF1/Cip1 expression and the presence or absence of the alteration at the 31st codon, endometrial carcinomas showed an increased percentage of immunopositive nuclei associated (P = 0.056) with 31Arg. These results demonstrate tissue-specific expression patterns of WAF1/Cip1 in different tumors which appears to be characteristic of the tumor type.

Breast Neoplasms↗
PubMed1995

Favorable left ventricular remodeling following large myocardial infarction by exercise training. Effect on ventricular morphology and gene expression.

Continued adverse remodeling of myocardium after infarction may lead to progressive ventricular dilation and heart failure. We tested the hypothesis that exercise training in a healed myocardial infarction-dysfunction rat model can favorably modify the adverse effects of ventricular remodeling including attenuation of abnormal myosin gene expression. Sprague-Dawley rats were subjected to either proximal LAD ligation or sham operation. At 5 wk after the operation, animals were randomly assigned to sedentary conditions or 6 wk of graduated swim training, creating four experimental groups: infarct sedentary (IS), infarct exercise (IE), sham sedentary (SS), and sham exercise (SE). At 11 wk all rats were sacrificed and analyzed. Compared to sedentary infarct controls, exercise training attenuated left ventricular (LV) dilation and allowed more hypertrophy of the non infarct wall. The exercise-trained hearts also showed a reduction in the estimated peak wall tension. Northern blot analysis showed an increase in beta-myosin heavy chain expression in the hearts of the sedentary infarction group soon after infarction when compared to sham controls. However, with exercise training, there was a significant attenuation of the beta-myosin heavy chain expression in the myocardium. Exercise training in a model of left ventricular dysfunction after healed myocardial infarction can improve the adverse remodeling process by attenuating ventricular dilation and reducing wall tension. The abnormal beta-myosin expression was also attenuated in the exercise trained group. This is evidence that abnormal gene expression following severe myocardial infarction dysfunction can be favorably modified by an intervention.

Animals↗
PubMed1994

Alterations in fatty acid metabolism in adriamycin cardiomyopathy.

Myocardial fatty acid metabolism may be impaired in adriamycin cardiomyopathy. In order to determine the extent of fatty acid metabolism alterations, we measured steady state [14C]palmitate oxidation and the incorporation of [14C]palmitate into the neutral lipid pool in a rat model of adriamycin cardiomyopathy. Isolated hearts from control rats and rats treated with adriamycin were perfused with 1.2 mmol/l of [14C]palmitate for 30 min to achieve steady state oxidation measured as [14C]O2 production; then perfused with 1.2 nmol/l of unlabelled palmitate. Hearts were killed early (0-5 min) or late (10-30 min) after the [14C]palmitate perfusion, to determine incorporation into the neutral lipid pool, and neutral lipid utilization. In the control group steady state oxidation was reached in 10 min ([14C]O2 production = 580 +/- 61 nmol/min/g dry wt) of perfusion. In the adriamycin treated group, mean CO2 production was significantly reduced at 10 min (329 +/- 44 nmol/min/g dry wt, P < 0.01 v control). At 30 min, [14C]O2 production in the treated group was not significantly different than controls (521 +/- 65 nmol/min/g dry wt v 617 +/- 36 nmol/min/g dry wt, P = N.S.). The incorporation of [14C]palmitate into the neutral lipid pool measured in the early subgroup was significantly reduced for adriamycin treated hearts v controls (7.2 +/- 0.6 v 12.0 +/- 1.4 mumol/g dry wt respectively, P < 0.01). In the control group 14C labelled neutral lipid reduced with time to 8.4 +/- 1.1 mumol/g dry wt (P < 0.05) in the late group. The adriamycin group demonstrated no significant change between early and late measurements. In conclusion, in adriamycin cardiomyopathy: (1) there is significant delay in achieving steady state palmitate oxidation, although the steady state rate is near normal; (2) palmitate incorporation into the neutral lipid pool is reduced; (3) neutral lipid pool utilization may also be reduced. These data suggest impaired uptake of palmitate into the cell in adriamycin cardiomyopathy, with a relatively maintained capacity for oxidative metabolism.

Animals↗
PubMed1994

Effects of oxygen free radicals and scavengers on the cardiac extracellular collagen matrix during ischemia-reperfusion.

OBJECTIVE: Collagen is lysed early during ischemia-reperfusion, but whether this is due to ischemia or reperfusion injury is not known. The effect of oxygen free radicals and free radical scavengers on left ventricular hemodynamics, myocardial morphology and collagen content were studied in an isolated, Langendorff-perfused rat heart model of regional ischemia-reperfusion. METHODS: All hearts received left anterior descending coronary artery ischemia for 20 mins. Group 1 had ischemia only; group 2 had ischemia followed by reperfusion with oxygenated Krebs-Henseleit buffer for 20 mins; group 3 had oxygen free radicals generated by hypoxanthine and xanthine oxidase during reperfusion; group 4 had free radical scavengers with superoxide dismutase plus catalase; group 5 had both oxygen free radicals and free radical scavengers during reperfusion. RESULTS: Left ventricular developed pressure decreased significantly in group 3 during ischemia followed by reperfusion (58 +/- 3.1 mmHg versus 42 +/- 2.4 mmHg, P = 0.004), but did not change significantly in any of the other groups. Necrosis score on pathology was highest in group 3; this score also was higher than that in group 5 with free radical scavengers added (3.0 +/- 0.3 versus 2.0 +/- 0.4, P = 0.07) and higher than that of group 2 with reperfusion with buffer only (3.0 +/- 0.3 versus 1.4 +/- 0.5, P < 0.05). Collagen content decreased significantly compared with control in group 3 only with ischemia followed by reperfusion with the addition of oxygen free radicals (18.4 +/- 1.5 versus 11.9 +/- 1.7 g/mg protein, P < 0.05). The addition of free radical scavengers in group 5 mainly attenuated the collagen loss. Scanning electron microscopy revealed profound structural changes of the extracellular collagen matrix in numerous regions of 'stunning' independent of tissue necrosis. CONCLUSIONS: We conclude that: first, oxygen free radicals trigger significant collagen damage and left ventricular dysfunction during reperfusion; second, these changes extend beyond the ischemic damage alone; and third, free radical scavengers can effectively limit oxygen free radical-induced collagen loss and left ventricular dysfunction.

Animals↗
PubMed1990

Are the kinetics of technetium-99m methoxyisobutyl isonitrile affected by cell metabolism and viability?

To investigate the role of cell viability and metabolism on the myocardial kinetics of a new tracer, technetium-99m-methoxyisobutyl isonitrile (Tc-99m-MIBI), 250 microCi/l Tc-99m-MIBI was infused in isolated rat hearts under constant flow conditions. The hearts were studied after inducing irreversible damage by cytochrome c oxidase inhibitor sodium cyanide (n = 8) or sarcolemmal membrane detergent Triton X-100 (n = 8). The control hearts (n = 6) received no toxins. Mean Tc-99m-MIBI peak accumulation activity was significantly reduced after cyanide (51.1 +/- 44.2% of control, p less than 0.01) and Triton (13.8 +/- 2.7% of control, p less than 0.001) administration. Kinetic studies also showed marked reduction in accumulation rates and marked increase in clearance rates for cyanide (p less than 0.01) and Triton (p less than 0.01) groups compared with controls. Potential changes in regional flow distribution were assessed using microspheres. When peak accumulation activity was corrected for these changes, there remained significant differences between the groups. In the cyanide and Triton groups, irreversible cell injury was confirmed by creatine kinase and lactate dehydrogenase release, triphenyl tetrazolium chloride staining, and electron microscopy. All the cells were viable in the control group. We conclude that the accumulation and clearance kinetics of Tc-99m-MIBI are significantly affected by cell viability. Tc-99m-MIBI kinetics appear to be dependent on sarcolemmal integrity and to a lesser extent on aerobic metabolism.

Animals↗