Angiographic assessment of myocardial reperfusion in patients treated with primary angioplasty for acute myocardial infarction: myocardial blush grade. Zwolle Myocardial Infarction Study Group

BACKGROUND

The primary objective of reperfusion therapies for acute myocardial infarction is not only restoration of blood flow in the epicardial coronary artery but also complete and sustained reperfusion of the infarcted part of the myocardium.

METHODS AND RESULTS

We studied 777 patients who underwent primary coronary angioplasty during a 6-year period and investigated the value of angiographic evidence of myocardial reperfusion (myocardial blush grade) in relation to the extent of ST-segment elevation resolution, enzymatic infarct size, left ventricular function, and long-term mortality. The myocardial blush immediately after the angioplasty procedure was graded by two experienced investigators, who were otherwise blinded to all clinical data: 0, no myocardial blush; 1, minimal myocardial blush; 2, moderate myocardial blush; and 3, normal myocardial blush. The myocardial blush was related to the extent of the early ST-segment elevation resolution on the 12-lead ECG. Patients with blush grades 3, 2, and 0/1 had enzymatic infarct sizes of 757, 1143, and 1623 (P<0.0001), respectively, and ejection fractions of 50%, 46%, and 39%, respectively (P<0.0001). After a mean+/-SD follow-up of 1.9+/-1.7 years, mortality rates of patients with myocardial blush grades 3, 2, and 0/1 were 3%, 6%, and 23% (P<0.0001), respectively. Multivariate analysis showed that the myocardial blush grade was a predictor of long-term mortality, independent of Killip class, Thrombolysis In Myocardial Infarction grade flow, left ventricular ejection fraction (LVEF), and other clinical variables.

CONCLUSIONS

In patients after reperfusion therapy, the myocardial blush grade as seen on the coronary angiogram can be used to describe the effectiveness of myocardial reperfusion and is an independent predictor of long-term mortality.

Clinical value of 12-lead electrocardiogram after successful reperfusion therapy for acute myocardial infarction. Zwolle Myocardial infarction Study Group

BACKGROUND

A simple clinical method to stratify risk for patients who have had successful reperfusion therapy after myocardial infarction is attractive since it facilitates the tailoring of therapy.

METHODS

We investigated the clinical value of the 12-lead electrocardiogram (ECG), in 403 patients after successful reperfusion therapy by primary coronary angioplasty, in relation to infarct size measured by enzyme activity, left-ventricular function, and clinical outcome. ECGs were analysed to find the extent of the ST-segment-elevation resolution 1 h after reperfusion therapy.

FINDINGS

A normalised ST segment was seen in 51% of patients, a partly normalised ST segment in 34%, and 15% had no ST-segment-elevation resolution. Enzymatic infarct size and ejection fraction were related to the extent of the early resolution of the ST segment. The relative risk of death among patients with no resolution compared with patients with a normalised ST segment was 8.7 (95% CI 3.7-20.1), and that among patients with partial resolution compared with patients with a normalised ST segment was 3.6 (1.6-8.3).

INTERPRETATION

Our findings suggest that ECG patterns reflect the effectiveness of myocardial reperfusion. Patients for whom reperfusion therapy by primary angioplasty was successful and who had normalised ST segments had limited damage to the myocardium and an excellent outlook during follow-up. Patients with persistent ST elevation after reperfusion therapy may need additional interventions since they have more extensive myocardial damage and have a higher mortality rate.

Squamous epithelial hyperplasia and carcinoma in mice transgenic for the human papillomavirus type 16 E7 oncogene

The human papillomavirus type 16 (HPV-16) genome is commonly present in human cervical carcinoma, in which a subset of the viral genes, E6 and E7, are expressed. The HPV-16 E6 and E7 gene products can associated with and inactivate the tumor suppressor proteins p53 and Rb (the retinoblastoma susceptibility gene product), and in tissue culture cells, these viral genes display oncogenic properties. These findings have led to the hypothesis that E6 and E7 contribute to cervical carcinogenesis. This hypothesis has recently been tested by using transgenic mice as an animal model. HPV-16 E6 and E7 together were found to induce cancers in multiple tissues in which they were expressed, including squamous cell carcinoma, the cancer type most commonly associated with HPV-16 in the human cervix. We have extended these studies to investigate the in vivo activities of HPV-16 E7 when expressed in squamous epithelia of transgenic mice. Grossly, E7 transgenic mice had multiple phenotypes, including wrinkled skin that was apparent prior to the appearance of hair on neonates, thickened ears, and loss of hair in adults. In lines of mice expressing higher levels of E7, we observed stunted growth and mortality at an early age, potentially caused by an incapacity to feed. Histological analysis demonstrated that E7 causes epidermal hyperplasia in multiple transgenic lineages with high penetrance. This epithelial hyperplasia was characterized by an expansion of the proliferating compartment and an expansion of the keratin 10-positive layer of cells and was associated with hyperkeratosis. Hyperplasia was found at multiple sites in the animals in addition to the skin, including the mouth palate, esophagus, forestomach, and exocervix. In multiple transgenic lineages, adult animals developed skin tumors late in life with low penetrance. These tumors arose from the squamous epithelia and from sebaceous glands and were characterized histologically to be highly differentiated, locally invasive, and aggressive in their growth properties. On the basis of these phenotypes, we conclude that HPV-16 E7 can alter epithelial cell growth parameters sufficiently to potentiate tumorigenesis in mice.

Human papillomavirus types 16 E6 and E7 contribute differently to carcinogenesis

High-risk human papillomaviruses (HPVs) are etiologically implicated in human cervical cancer. Two viral genes, E6 and E7, are commonly found expressed in these cancer cells. We have previously shown that mice transgenic for the HPV-16 E6 gene or E7 gene, in which the E6 or E7 was expressed in the basal layer of epithelia, developed skin tumors. The spectrum of tumors derived from E6 and E7 mice differed, however; although most tumors derived from the E7-transgenic mice were benign, the majority of the tumors from the E6-transgenic mice were malignant. These findings led us to hypothesize that E6 and E7 play different roles in carcinogenesis. To assess at what stages in carcinogenesis E6 and E7 act, we treated the skin of K14E6- and K14E7-transgenic mice with chemical carcinogens known to contribute to distinct stages in carcinogenesis. Both E6 and E7 were found to synergize with chemical carcinogens in causing tumor formation. E6 was found to act weakly at the promotion stage of carcinogenesis in the formation of benign tumors but strongly at the progression stage which involves the malignant conversion of benign tumors. In contrast, E7 primarily affected the promotion stage of carcinogenesis. These results provide direct evidence that E6 and E7 contribute differently to carcinogenesis; E7 promotes the formation of benign tumors, and E6 acts primarily to accelerate progression of these benign tumors to the malignant stage. Consistent with this model, we found E6 and E7 to cooperate in inducing tumor formation in mice expressing both oncogenes.

Chemoprotective effects of capsaicin and diallyl sulfide against mutagenesis or tumorigenesis by vinyl carbamate and N-nitrosodimethylamine

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) is a major pungent and irritating ingredient of hot chilli peppers, which are frequently consumed as spices. This dietary phytochemical has been found to interact with microsomal xenobiotic metabolizing enzymes in rodents. Capsaicin and its saturated analog dihydrocapsaicin (trans-8-methyl-N-vanillyl-6-nonanamide) have been proposed to inactivate cytochrome P-450 HE1 by irreversibly binding to the active sites of the enzyme. Besides cytochrome P-450 HE1, other isoforms of the P-450 superfamily were also reported to be inhibited by capsaicin. The inhibition by capsaicin of microsomal monooxygenases involved in carcinogen activation implies its chemopreventive potential. As part of a program to investigate chemoprotective properties of capsaicin we initially determined the effect of capsaicin on vinyl carbamate (VC)- and N-nitrosodimethylamine (NDMA)-induced mutagenesis in Salmonella typhimurium TA100. Capsaicin (0.42 mM) attenuated the bacterial mutagenicity of VC and NDMA by 50% and 42% respectively. Diallyl sulfide, a thioether found in garlic with selective P-450 HE1 inhibitory activity, also lessened the mutagenicity of the above carcinogens in a concentration-dependent manner. The suppression of VC- and NDMA-induced mutagenesis by capsaicin and diallyl sulfide correlated with their inhibition of P-450 IIE1-mediated p-nitrophenol hydroxylation and NDMA N-demethylation. Pretreatment of female ICR mice with a topical dose of capsaicin lowered the average number of VC-induced skin tumors by 62% at 22 weeks after promotion. A similar degree of protection was attained with oral administration of diallyl sulfide before carcinogen treatment. The results of this study suggest that capsaicin and diallyl sulfide suppress VC- and NDMA-induced mutagenesis or tumorigenesis in part through inhibition of the cytochrome P-450 IIE1 isoform responsible for activation of these carcinogens.

5-Sulfooxymethylfurfural as a possible ultimate mutagenic and carcinogenic metabolite of the Maillard reaction product, 5-hydroxymethylfurfural

Heat treatment of foods containing reducing sugars and amino acids during cooking or sterilization triggers a sequence of non-enzymatic reactions collectively known as the Maillard reaction. 5-Hydroxymethylfurfural (HMF), one of the major intermediate products in the Maillard reaction, has been found to possess cytotoxic, genotoxic and tumorigenic activities, but the mechanisms of its toxic actions remain unclear. Formation of an electrophilic allylic ester bearing a good leaving group such as sulfate has been proposed as a possible metabolic activation pathway for HMF. In order to further test this possibility, we compared the mutagenic and carcinogenic activities of HMF and its chemically synthesized sulfuric acid ester, 5-sulfooxymethylfurfural (SMF). SMF induced dose-dependent increases in the number of His+ revertants in Salmonella typhimurium TA100. This intrinsic mutagenicity of SMF was significantly inhibited by ascorbic acid added to the assay media. In the presence of chloride ions, the bacterial mutagenicity of the highly polar sulfuric acid ester of HMF may also be mediated by formation of a lipophilic chloromethyl derivative. When topically applied to mouse skin, both sulfooxymethyl and chloromethyl derivatives of HMF exhibited higher skin tumor initiating activity than the parent hydroxymethyl compound. 5-Chloromethylfurfural was found to be a strong hepatocarcinogen in infant male B6C3F1 mice.

Epidermal cancer associated with expression of human papillomavirus type 16 E6 and E7 oncogenes in the skin of transgenic mice

Certain "high-risk" anogenital human papillomaviruses (HPVs) have been associated with the majority of human cervical carcinomas. In these cancers, two papillomaviral genes, E6 and E7, are commonly expressed. In this study we provide evidence that expression of the E6 and E7 genes from the high-risk HPV-16 in the skin of transgenic mice potentiated the development of preneoplastic lesions, and a high percentage of these epidermal lesions subsequently developed into locally invasive cancers. High levels of E6/E7 expression were found in these tumors relative to the preneoplastic lesions, and expression was localized to the proliferating, poorly differentiated epidermal cells. Also, the p53 and Rb genes were found to be intact, not mutationally inactivated, in representative skin tumors. These findings demonstrate that the E6 and E7 genes from a papillomavirus etiologically associated with human cervical cancer can contribute to the development of epidermal cancers in an animal model.

Randomized comparison of primary coronary angioplasty with thrombolytic therapy in low risk patients with acute myocardial infarction

OBJECTIVES

We sought to compare primary coronary angioplasty and thrombolysis as treatment for low risk patients with an acute myocardial infarction.

BACKGROUND

Primary coronary angioplasty is the most effective reperfusion therapy for patients with acute myocardial infarction; however, intravenous thrombolysis is easier to apply, more widely available and possibly more appropriate in low risk patients.

METHODS

We stratified 240 patients with acute myocardial infarction at admission according to risk. Low risk patients (n = 95) were randomized to primary angioplasty or thrombolytic therapy. The primary end point was death, nonfatal stroke or reinfarction during 6 months of follow-up. Left ventricular ejection fraction and medical charges were secondary end points. High risk patients (n = 145) were treated with primary angioplasty.

RESULTS

In low risk patients, the incidence of the primary clinical end point (4% vs. 20%, p < 0.02) was lower in the group with primary coronary angioplasty than in the group with thrombolysis, because of a higher rate of reinfarction in the latter group. Mortality and stroke rates were low in both treatment groups. There were no differences in left ventricular ejection fraction or total medical charges. High risk patients had a 14% incidence rate of the primary clinical end point.

CONCLUSIONS

Simple clinical data can be used to risk-stratify patients during the initial admission for myocardial infarction. Even in low risk patients, primary coronary angioplasty results in a better clinical outcome at 6 months than does thrombolysis and does not increase total medical charges.

1,N6-ethenoadenosine formation, mutagenicity and murine tumor induction as indicators of the generation of an electrophilic epoxide metabolite of the closely related carcinogens ethyl carbamate (urethane) and vinyl carbamate

Previous studies from this laboratory showed that (i) vinyl carbamate (VC) was much more carcinogenic than ethyl carbamate (EC) and that both carbamates induced the same spectrum of tumors in mice and rats, (ii) adducts of [14C]- or [3H]1,N6-ethenoadenosine and [14C]- or [3H]3,N4-ethenocytidine e were formed in the hepatic RNA of infant male B6C3F1 mice administered [1-14C]ethyl or [1,2-3H]ethyl EC and (iii) VC formed much more of the 1,N6-ethenoadenosine (epsilon Ado) adduct in the hepatic RNA and the 7-(2-oxoethyl)-guanine adduct in the hepatic DNA of mice than did EC. By analogy to the similar results of earlier studies by other investigators on the related carcinogen vinyl chloride, the above data suggested that VC epoxide was a reactive electrophilic metabolite of these carbamates. In the present studies, VC, but not EC, was found to be oxidized by 3-chloroperbenzoic acid to a derivative that reacted with adenosine to form epsilon Ado. Far more of this etheno nucleoside was formed from VC than from EC when these carbamates were metabolized by cofactor-fortified mouse liver microsomes in the presence of adenosine. Sodium diethyldithiocarbamate strongly inhibited these microsomal reactions and the formation of epsilon Ado in the hepatic RNA of mice administered either carbamate. Likewise, the i.p. preadministration of deithyldithiocarbamate markedly inhibited the induction of tumors by single i.p. doses of EC or VC in the livers of infant male B6C3F1 mice and in the livers, lungs and Harderian glands of infant female B6C3F1 mice. This inhibitor also considerably reduced lung tumor induction by VC in adult female A/Jax mice. 2-(2,4-Dichloro-6-phenyl) phenoxyethyl amine, a cytochrome P450 inhibitor, reduced the carcinogenicity of low doses of EC but appeared to increase the carcinogenicity of low doses of VC. The mutagenicity of VC for Salmonella typhimurium TA1535 in the presence of a hepatic activating system was greatly reduced by these inhibitors. The data from all these studies are consistent with the proposal that VC epoxide is an ultimate electrophilic and carcinogenic metabolite of EC and VC in the mouse.

N-sulfoöxy-2-aminofluorene is the major ultimate electrophilic and carcinogenic metabolite of N-hydroxy-2-acetylaminofluorene in the livers of infant male C57BL/6J x C3H/HeJ F1 (B6C3F1) mice

The hepatic DNA of 12-day-old male B6C3F1 (C57BL/6J X C3H/HeJ) mice given an i.p. dose of 0.06 or 0.11 mumol/g body weight of N-hydroxy-[3H]-2-acetylaminofluorene (N-hydroxy-AAF) contained at 9 h approximately 3 or 6 pmol of N-(deoxyguanosin-8-yl)-2-aminofluorene adducts per mg. Together the level of the two acetylated adducts N-(deoxyguanosin-8-yl)-2-acetylaminofluorene and 3-(deoxyguanosin-N2-yl)-2-acetylaminofluorene was less than or equal to 10% of this amount. The same doses of unlabeled carcinogen induced by 10 months a 100% incidence of hepatomas with averages of 10 and 15 hepatomas per mouse, respectively. Injection of 0.04 mumol/g body weight of pentachlorophenol (PCP) 45 min before the dose of N-hydroxy-AAF decreased the number of adducts in the DNA by 90% and the average number of hepatomas per liver by 80-90%. As compared to their normal male littermates, male brachymorphic B6C3F2 mice, which are deficient in hepatic 3'-phosphoadenosine-5'-phosphosulfate (PAPS), treated with N-hydroxy-AAF formed only 25% as many hepatic DNA adducts and developed only 10% as many hepatomas. Hepatic cytosols from 12-day-old B6C3F1 mice contained PAPS-dependent sulfotransferase activity for N-hydroxy-2-aminofluorene (N-hydroxy-AF), a previously unrecognized activity, as well as sulfotransferase activity for N-hydroxy-AAF; both activities were inhibited 60% by 1 microM and greater than or equal to 80% by 10 microM PCP. Cytosolic acetyl coenzyme A-dependent acetyltransferase activity for N-hydroxy-AF, cytosolic N,O-acyltransferase activity for N-hydroxy-AAF, and microsomal deacetylase for N-hydroxy-AAF were not significantly inhibited by PCP under these conditions. The above data strongly indicate that N-sulfoöxy-2-aminofluorene is the major ultimate electrophilic and carcinogenic metabolite of N-hydroxy-AAF in the livers of infant male B6C3F1 mice.

Vinyl carbamate epoxide, a major strong electrophilic, mutagenic and carcinogenic metabolite of vinyl carbamate and ethyl carbamate (urethane)

Vinyl carbamate epoxide (VCO) was found to possess strong electrophilic, mutagenic and carcinogenic activities. It reacted with water at 37 degrees C and pH 7.4 (phosphate buffer) to form glycolaldehyde and several related reducing compounds; none of these products were mutagenic for Salmonella typhimurium TA1535. Under these conditions VCO had a half-life (determined chemically and mutagenically) of approximately 10.5 min. This half-life was progressively lowered by increasing concentrations of chloride ion (liver, serum and isotonic levels). This ion reacted with VCO to form chloroacetaldehyde. VCO also reacted with other nucleophiles such as glutathione, DNA and its constituent guanine and adenine bases. The purine adducts formed by VCO in DNA in vitro and in vivo were released by weak acid treatment and consisted of 7-(2'-oxoethyl)guanine and N2,3-ethenoguanine as major products with 1,N6-ethenoadenine as a minor product. VCO was a strong direct mutagen in Salmonella typhimurium TA1535 and TA100 but was only weakly active in the TA98 mutant. VCO was a stronger initiator of carcinogenesis in the skin of CD-1 mice and in the liver of infant male B6C3F1 mice than its metabolic precursors vinyl carbamate (VC) and ethyl carbamate (EC). Unlike VC and EC, VCO was a strong complete carcinogen in the skin of CD-1 mice and induced papillomas and carcinomas following repetitive administration of sub-ulcerogenic doses. VCO also exhibited some carcinogenic activity in the lungs of mice and in the s.c. and mammary tissue of female Sprague-Dawley rats. These data and those from other recent studies support the conclusion that VCO is a major strong electrophilic, mutagenic and carcinogenic metabolite of EC and VC in the mouse.

Traumatic optic neuropathy: a review of 61 patients

The outcome of traumatic optic neuropathy was evaluated following penetrating and blunt injuries to assess the effect of treatment options, including high-dose steroids, surgical intervention, and observation alone. Factors that affected improvement in visual acuity were identified and quantified. Sixty-one consecutive, nonrandomized patients presenting with visual loss after facial trauma between 1984 and 1996 were assessed for outcome. Pretreatment and posttreatment visual acuities were compared using a standard ophthalmologic conversion from the values of no light perception, light perception, hand motion, finger counting, and 20/800 down to 20/15 to a logarithm of the minimum angle of resolution (log MAR). The percentage of patients showing visual improvement and the degree of improvement were calculated for each patient group and treatment method. Measurements of visual acuity are in log MAR units +/- standard error of the mean. Patients who sustained penetrating facial trauma (n = 21) had worse outcomes than patients with blunt trauma (n = 40). Improvement in visual acuity after treatment was seen in 19 percent of patients with penetrating trauma compared with 45 percent of patients with blunt trauma (p < 0.05). Furthermore, patients with penetrating trauma improved less than those with blunt trauma, with a mean improvement of 0.4 +/- 0.23 log MAR compared with 1.1 +/- 0.24 in blunt-trauma patients (p = 0.03). The patients with blunt trauma underwent further study. There was no significant difference in improvement of visual acuity in patients treated with surgical versus nonsurgical methods; however, 83 percent of patients without orbital fractures had improvement compared with 38 percent of patients with orbital fractures (p < 0.05). The mean improvement in patients without orbital fractures was 1.8 +/- 0.65 log MAR compared with 0.95 +/- 0.26 in patients with orbital fractures (p = 0.1). Twenty-seven percent of patients who had no light perception on presentation experienced improvement in visual acuity after treatment compared with 100 percent of patients who had light perception on admission (p < 0.05). The mean improvement in patients who were initially without light perception was 0.85 +/- 0.29 log MAR compared with 1.77 +/- 0.35 in patients who had light perception (p < 0.05). There were no significant differences in improvement of visual acuity when analyzing the effect of patient age and timing of surgery. Patients who sustain penetrating trauma have a worse prognosis than those with blunt trauma. The presence of no light perception and an orbital fracture are poor prognostic factors in visual loss following blunt facial trauma. It seems that clinical judgment on indication and timing of surgery, and not absolute criteria, should be used in the management of traumatic optic neuropathy.

Metabolic activation of the carcinogen 6-hydroxymethylbenzo[a]pyrene: formation of an electrophilic sulfuric acid ester and benzylic DNA adducts in rat liver in vivo and in reactions in vitro

Hydroxylation of meso-methyl groups with subsequent formation of reactive electrophilic esters has been proposed as a possible activation pathway in the metabolism, DNA binding and carcinogenicity of some methyl-substituted polycyclic aromatic hydrocarbons. Some data in vitro have been reported in support of this concept. In this study, sulfotransferase activity for 6-hydroxymethylbenzo[a]pyrene (HMBP) in rat and mouse liver cytosols was demonstrated to mediate formation of benzylic adducts from this hydrocarbon with guanosine and with deoxyguanosine and deoxyadenosine in DNA. These benzylic adducts were also obtained from reactions of synthetic 6-sulfooxymethylbenzo[a]pyrene (SMBP) with individual (deoxy)ribonucleosides or DNA. The structure of the major DNA adduct formed from HMBP and SMBP was determined from NMR spectroscopy to be N2-(benzo[a]pyrene-6-methylenyl)-deoxyguanosine. Low levels of a deoxycytidine adduct were also obtained from DNA reacted with SMBP. Covalent modification of DNA by acetyl-CoA- and ATP-dependent activation of HMBP also produced the identical benzylic adducts, but the amounts were smaller than those obtained in the sulfotransferase-mediated reaction. The i.p. administration of HMBP to rats resulted in the formation of a hepatic DNA adduct. After enzymatic hydrolysis to the nucleoside level, this DNA adduct was chromatographically identical with the deoxyguanosine adduct formed in the above in vitro reactions. This adduct accounted for approximately 20-30% of total HMBP residues bound to hepatic DNA and its formation was significantly inhibited by pretreatment of rats with dehydroepiandrosterone, an inhibitor of the sulfotransferase activity for HMBP. The i.p. administration of comparable doses of SMBP to rats led to the formation of much larger amounts of the adducts with the guanine, adenine, and cytosine bases in the liver DNA. The data indicate that the sulfotransferase activity in the rat liver for HMBP plays a major role in the benzylic DNA adduct formation from this hydrocarbon in rat liver in vivo.

High dose heparin as pretreatment for primary angioplasty in acute myocardial infarction: the Heparin in Early Patency (HEAP) randomized trial

OBJECTIVES

In the Heparin in Early Patency (HEAP) pilot study a beneficial effect of high-dose heparin on early patency in acute myocardial infarction (MI) was observed in a matched-control study.

BACKGROUND

High dose bolus intravenous injection of heparin may achieve lysis of coronary thrombi and could enhance early patency of the infarct related vessel in patients with MI scheduled for primary angioplasty.

METHODS

Before primary angioplasty, 584 patients with MI entered an open randomized trial of high dose (300 IU/kg) or low dose (0 or 5,000 IU) heparin. Of the 584 patients, 299 were randomized to high dose and 285 patients to low dose heparin.

RESULTS

Thrombolysis In Myocardial Infarction (TIMI) flow grade 2 or 3 was observed before primary angioplasty in 65 patients (22%) in the high dose group and 60 patients (21%) in the low dose heparin group (p > 0.1), whereas TIMI flow grade 3 was observed in 38 (13%) and 24 patients (9%), respectively (p = 0.11). There were no differences in the clinical end points between the two groups. There were no hemorrhagic strokes, while 10% of the patients in the high dose group required blood transfusion versus 6% in the low dose/no heparin group (p = 0.07). No subsets of patients showed beneficial effects of high dose heparin, such as patients with longer delay between heparin administration and diagnostic angiogram or patients with short delay between symptom onset and admission.

CONCLUSIONS

There is no benefit of high dose bolus heparin on early patency compared with no or low dose heparin.

Metabolic activation of 9-hydroxymethyl-10-methylanthracene and 1-hydroxymethylpyrene to electrophilic, mutagenic and tumorigenic sulfuric acid esters by rat hepatic sulfotransferase activity

Our previous studies on 7-hydroxymethyl-12-methylbenz[a]anthracene and 6-hydroxymethylbenzo[a]pyrene showed that cytosolic sulfotransferase activity plays a major role in the formation of hepatic benzylic DNA and RNA adducts by these carcinogens in rats. In the present study, we found similar sulfotransferase activity in rat liver cytosol which activates 9-hydroxymethyl-10-methylanthracene (HMA) and 1-hydroxymethylpyrene (HMP) to electrophilic sulfuric acid ester metabolites. Thus, incubation of these nonbay region hydrocarbons with calf thymus DNA in the presence of liver cytosol fortified with the sulfo-group donor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS) produced benzylic DNA adducts that were chromatographically identical to those obtained by the reactions of the corresponding sulfuric acid esters with deoxyguanosine and deoxyadenosine. These adducts were also produced in the livers of infant rats injected i.p. with 0.25 mumol/g body wt of HMA or HMP. Administration of comparable doses of 9-sulfooxymethyl-10-methylanthracene (SMA) and 1-sulfooxymethylpyrene (SMP) resulted in much higher levels of hepatic benzylic DNA adducts than did the parent hydroxymethyl hydrocarbons. Both HMA and HMP induced His+ revertants in Salmonella typhimurium TA98 when preincubated with these bacteria in the presence of rat liver cytosol and PAPS. This sulfotransferase-mediated mutagenicity of HMA and HMP was reduced by dehydroepiandrosterone, an inhibitor of hepatic sulfotransferase activity for these hydrocarbons. SMA and SMP were directly mutagenic and their intrinsic bacterial mutagenicity was inhibited by glutathione (GSH) and GSH-S-transferase activity. Chloride ion at physiological concentrations enhanced the bacterial mutagenicity of SMA through the formation of 9-chloromethyl-10-methylanthracene as previously observed for SMP by Henschler et al. In contrast to the higher mutagenicity of 1-chloromethylpyrene (CMP) than SMP in bacteria, CMP formed smaller amounts of hepatic benzylic DNA adducts in rats than the sulfuric acid ester. SMA and SMP were weak skin tumor initiators in the mouse, but they were more active than HMA and HMP in this regard.

Both conserved region 1 (CR1) and CR2 of the human papillomavirus type 16 E7 oncogene are required for induction of epidermal hyperplasia and tumor formation in transgenic mice

High-risk human papillomavirus type 16 (HPV-16) and HPV-18 are associated with the majority of human cervical carcinomas, and two viral genes, HPV E6 and E7, are commonly found to be expressed in these cancers. The presence of HPV-16 E7 is sufficient to induce epidermal hyperplasia and epithelial tumors in transgenic mice. In this study, we have performed experiments in transgenic mice to determine which domains of E7 contribute to these in vivo properties. The human keratin 14 promoter was used to direct expression of mutant E7 genes to stratified squamous epithelia in mice. The E7 mutants chosen had either an in-frame deletion in the conserved region 2 (CR2) domain, which is required for binding of the retinoblastoma tumor suppressor protein (pRb) and pRb-like proteins, or an in-frame deletion in the E7 CR1 domain. The CR1 domain contributes to cellular transformation at a level other than pRb binding. Four lines of animals transgenic for an HPV-16 E7 harboring a CR1 deletion and five lines harboring a CR2 deletion were generated and were observed for overt and histological phenotypes. A detailed time course analysis was performed to monitor acute effects of wild-type versus mutant E7 on the epidermis, a site of high-level expression. In the transgenic mice with the wild-type E7 gene, age-dependent expression of HPV-16 E7 correlated with the severity of epidermal hyperplasia. Similar age-dependent patterns of expression of the mutant E7 genes failed to result in any phenotypes. In addition, the transgenic mice with a mutant E7 gene did not develop tumors. These experiments indicate that binding and inactivation of pRb and pRb-like proteins through the CR2 domain of E7 are necessary for induction of epidermal hyperplasia and carcinogenesis in mouse skin and also suggest a role for the CR1 domain in the induction of these phenotypes through as-yet-uncharacterized mechanisms.

Single mode 4.3 kW output power from a diode-pumped Yb-doped fiber amplifier

We investigate the average power scaling of two diode-pumped Yb-doped fiber amplifiers emitting a diffraction-limited beam. The first fiber under investigation with a core diameter of 30 µm was able to amplify a 10 W narrow linewidth seed laser up to 2.8 kW average output power before the onset of transverse mode instabilities (TMI). A further power scaling was achieved using a second fiber with a smaller core size (23µm), which allowed for a narrow linewidth output power of 3.5 kW limited by stimulated Brillouin scattering (SBS). We mitigated SBS using a spectral broadening mechanism, which allowed us to further increase the output power to 4.3 kW only limited by the available pump power. Up to this power level, a high slope efficiency of 90% with diffraction-limited beam quality and without any sign of TMI or stimulated Raman scattering for a spectral dynamic range of higher than -80 dB was obtained.

Initiation of hepatocarcinogenesis in infant male B6C3F1 mice by N-hydroxy-2-aminofluorene or N-hydroxy-2-acetylaminofluorene depends primarily on metabolism to N-sulfooxy-2-aminofluorene and formation of DNA-(deoxyguanosin-8-yl)-2-aminofluorene adducts

Previous work from this laboratory provided strong evidence that N-sulfooxy-2-aminofluorene is the major ultimate electrophilic and carcinogenic metabolite of N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF) in the livers of infant male B6C3F1 (C57BL/6J X C3H/HeJ F1) mice. Over 90% of the hepatic DNA adducts in these mice consisted of N-(deoxyguanosin-8-yl)-2-aminofluorene [N-(dGuo-8-yl)-AF] and less than 10% were deoxyguanosinyl adducts containing 2-acetylaminofluorene (AAF) residues. In the present study hepatic DNA adduct formation and tumor initiation by N-hydroxy-2-aminofluorene (N-hydroxy-AF) were examined in these mice. N-(dGuo-8-yl)-AF was the only adduct detected in the hepatic DNA; the level at 9 h after a single i.p. dose of 0.04 or 0.06 mumol/g body wt of [3H]N-hydroxy-AF was 1.0 or 1.7 pmol/mg DNA. Pretreatment with a single i.p. dose (0.04 mumol/g body wt) of the sulfotransferase inhibitor pentachlorophenol (PCP) decreased the DNA adduct level by greater than 80%. Similar levels of this adduct were found by 32P-postlabeling analysis of DNA from mice treated with unlabeled N-hydroxy-AF. The liver DNA of infant male brachymorphic B6C3F2 mice [deficient in 3'-phosphoadenosine-5'-phosphosulfate (PAPS)] contained only 0.3 pmol/mg DNA of N-(dGuo-8-yl)-AF after an i.p. dose of 0.06 mumol of N-hydroxy-AF/g body wt, while their phenotypically normal (PAPS-sufficient) male littermates had 1.9 pmol/mg DNA. A single i.p. dose of 0, 0.015, 0.03, 0.06 or 0.12 mumol/g body wt of N-hydroxy-AF in infant male B6C3F1 mice induced by 10 months an average of 0.2, 2.5, 7, 11 or 14 hepatomas/mouse. Pretreatment with PCP reduced the liver tumor multiplicity at each dose level by greater than 80%. Essentially the same average tumor multiplicities and inhibitions of tumor formation by PCP pretreatment were obtained following injections of N-hydroxy-AF or N-hydroxy-AAF at the three lower dose levels. Collectively these data strongly indicated that N-sulfooxy-2-aminofluorene is the major ultimate electrophilic and carcinogenic metabolite of N-hydroxy-AF in the livers of infant male B6C3F1 mice. Furthermore, since only N-(dGuo-8-yl)-AF adducts were found in the hepatic DNA these lesions appear to be critical in the initiation of hepatocarcinogenesis in these mice by N-hydroxy-AF.

Tolerance or immunity to a tumor antigen expressed in somatic cells can be determined by systemic proinflammatory signals at the time of first antigen exposure

Mice transgenic for the E7 tumor Ag of human papillomavirus type 16, driven from a keratin 14 promoter, express E7 in keratinocytes but not dendritic cells. Grafted E7-transgenic skin is not rejected by E7-immunized mice that reject E7-transduced transplantable tumors. Rejection of recently transplanted E7-transgenic skin grafts, but not of control nontransgenic grafts or of established E7-transgenic grafts, is induced by systemic administration of live or killed Listeria monocytogenes or of endotoxin. Graft recipients that reject an E7 graft reject a subsequent E7 graft more rapidly and without further L. monocytogenes exposure, whereas recipients of an E7 graft given without L. monocytogenes do not reject a second graft, even if given with L. monocytogenes. Thus, cross-presentation of E7 from keratinocytes to the adaptive immune system occurs with or without a proinflammatory stimulus, but proinflammatory stimuli at the time of first cross-presentation of Ag can determine the nature of the immune response to the Ag. Furthermore, immune effector mechanisms responsible for rejection of epithelium expressing a tumor Ag in keratinocytes are different from those that reject an E7-expressing transplantable tumor. These observations have implications for immunotherapy for epithelial cancers.

The strong hepatocarcinogenicity of the electrophilic and mutagenic metabolite 6-sulfooxymethylbenzo[a]pyrene and its formation of benzylic DNA adducts in the livers of infant male B6C3F1 mice

6-Hydroxymethylbenzo[a]pyrene was activated to an electrophilic and mutagenic sulfuric acid ester metabolite by rat and mouse liver sulfotransferase activity. The intrinsic mutagenicity of this reactive ester, 6-sulfooxymethylbenzo[a]pyrene, was inhibited by glutathione and glutathione S-transferase. A single i.p. dose of 2.5 nmol/g body wt of 6-sulfooxymethylbenzo[a]pyrene in infant male B6C3F1 mice induced liver tumors in 35 of 36 mice at 10 months with an average multiplicity of 4.4. A comparable dose of the parent hydrocarbon, 6-hydroxymethylbenzo[a]pyrene, was only a tenth as active. The electrophilic sulfuric acid ester produced high levels of benzylic DNA adducts in the livers of these mice that accounted for about 80% of the total DNA adducts. These results strongly suggest that this sulfuric acid ester is an important ultimate electrophilic and carcinogenic metabolite in carcinogenesis by 6-hydroxymethylbenzo[a]pyrene and possibly even by 6-methylbenzo[a]pyrene and benzo[a]pyrene in mouse liver.

Sulfuric acid esters as major ultimate electrophilic and hepatocarcinogenic metabolites of 4-aminoazobenzene and its N-methyl derivatives in infant male C57BL/6J x C3H/HeJ F1 (B6C3F1) mice

Liver cytosols from 12-day-old male C57BL/6 X C3H/HeJ F1 (B6C3F1) mice contain 3'-phosphoadenosine-5'-phosphosulfate (PAPS)-dependent sulfotransferase activity for N-hydroxy-4-aminoazobenzene and N-hydroxy-N-methyl-4-aminoazobenzene. No acetyl co-enzyme A-dependent transacetylase activity for these hydroxylamines was detected in the cytosols. Pentachlorophenol (PCP) and 2,6-dichloro-4-nitrophenol were only moderately active inhibitors of the sulfotransferase activity; at a 100-microM concentration each compound inhibited the activity by only 50-80%. A single dose of 0.04 mumol/g body weight of PCP administered to 12-day-old male B6C3F1 mice 45 min prior to a single dose of 0.1 mumol/g body weight of [3H]4-aminoazobenzene ([3H]AB) or [3H]N,N-dimethyl-4-aminoazobenzene ([3H]DAB) inhibited DNA adduct formation by approximately 50%. Under identical conditions, PCP also reduced the average number of hepatomas induced per mouse at 9 months by AB and N-methyl-4-aminoazobenzene (MAB) by 52 and 36%, respectively. PCP strongly inhibited the hepatocarcinogenicity of DAB or AB when this agent was administered in the diet with either dye to female CD-1 mice over a 10- month period. Single doses of 0.15 mumol/g body weight of [3H]AB and [3H]DAB bound to hepatic DNA of 12-day-old brachymorphic B6C3F2 mice, which are deficient in the synthesis of PAPS, at levels 15 and 20%, respectively, of those found in their phenotypically normal litter mates. Under identical conditions, the incidence of hepatomas in brachymorphic mice at 9 months were 11 and 29%, with averages of 0.2 and 0.8 hepatomas/mouse for AB and MAB, respectively. Incidences of 77 and 86%, with averages of 6.6 and 5.4 hepatomas/mouse, respectively, were found in their phenotypically normal litter mates. These data strongly indicate that N-sulfoöxy-AB is a major ultimate electrophilic and hepatocarcinogenic metabolite of AB in mice. Similarly, this ester and N-sulfoöxy-N-methyl-4-aminoazobenzene appear to be critical metabolites for these activities of DAB and MAB.

New studies on trans-anethole oxide and trans-asarone oxide

The widespread use of naturally occurring alkenylbenzenes as flavoring and fragrance agents has led to a long-standing interest in their toxicity and carcinogenicity. Among them several allyl- and propenylbenzenes have been found to be mutagenic and carcinogenic. It has been shown that the carcinogenicity of several allylbenzenes can be related to the formation of electrophilic sulfuric acid esters following 1'-hydroxylation. Unlike the allylbenzenes, the mechanisms of carcinogenesis of propenylbenzenes such as anethole and asarone are not clear. It has been reported that one of the main metabolic pathways of trans-anethole is the epoxidation of the side chain 1,2-double bond, which was responsible for cytotoxicity but not for genotoxicity. However, we report here that synthetic trans-anethole oxide prepared from trans-anethole and dimethyldioxirane is not only mutagenic for Salmonella tester strains but is also carcinogenic in the induction of hepatomas in B6C3F1 mice and skin papillomas in CD-1 mice. Synthetic trans-asarone oxide was also carcinogenic in the induction of hepatomas as well as mutagenic for Salmonella strains. Further studies are needed on these side chain oxides of trans-anethole and trans-asarone as possible metabolites in the toxicity, mutagenicity and carcinogenicity of these and other propenylbenzenes.

High dose bolus heparin as initial therapy before primary angioplasty for acute myocardial infarction: results of the Heparin in Early Patency (HEAP) pilot study

OBJECTIVES

We sought to determine the effect of high dose intravenous bolus heparin on early coronary patency before primary angioplasty.

BACKGROUND

Early coronary angiography after thrombolysis for acute myocardial infarction has shown better patency when intravenous heparin is used as an adjunct. The present study explores whether heparin alone can induce reperfusion.

METHODS

In the Heparin in Early Patency (HEAP) pilot study, 108 patients with signs and symptoms of acute myocardial infarction < 6 h eligible for primary angioplasty received a single intravenous bolus of 300 U/kg of heparin together with aspirin (160 mg chewed) in the emergency room. The median dose of bolus heparin given was 27,000 U. Patency of the infarct-related artery (IRA) was assessed by coronary angiography at a median of 85 min after the heparin bolus.

RESULTS

In 55 patients (51%, 95% confidence interval 38% to 64%), Thrombolysis in Myocardial Infarction (TIMI) flow grade 2 or 3 was observed at 90 min: TIMI flow grade 3 in 33 patients (31%); TIMI flow grade 2 in 22 (20%). Thirty-two (64%) of 50 patients with symptoms < or = 2 h had TIMI flow grade 2 or 3 versus 23 (40%) of 58 patients with symptoms > 2 h (p = 0.02). No significant bleeding was seen. Two patients (2%) died in the hospital. The patency results obtained in patients treated with the high dose bolus heparin were compared with those in 108 patients from a large primary angioplasty database, who were treated with standard therapy, including aspirin but not intravenous heparin, and were matched for clinical and angiographic characteristics with the HEAP pilot study patients. They showed an 18% patency rate (p < 0.001) of the IRA (TIMI flow grade 3 in 9%, TIMI flow grade 2 in 9%) before primary angioplasty.

CONCLUSIONS

Early therapy with high dose heparin is associated with full coronary reperfusion in a considerable number of patients with acute myocardial infarction, especially in those treated early (< 2 h). This simple, inexpensive, probably safe and easily antagonizable treatment may be an attractive first treatment of acute myocardial infarction both before and during the hospital stay in conjunction with primary angioplasty.

Inhibition by pentachlorophenol of the initiating and promoting activities of 1'-hydroxysafrole for the formation of enzyme-altered foci and tumors in rat liver

The hepatocarcinogen 1'-hydroxysafrole (HOS) exhibited weak initiating activity and strong promoting activity for the induction of enzyme-altered foci and tumors in rat liver. Thus, administration of a single dose of HOS to rats 18 h after a 70% hepatectomy, followed by administration of phenobarbital (PB) in the diet for 6 months, induced a low, but statistically significant, number of foci of enzyme-altered cells. This treatment did not result in gross liver tumors, even when the PB treatment was continued for 16 months. Large numbers of enzyme-altered foci developed when HOS was administered in the diet at levels of 0.05-0.25% to rats previously administered a single dose of N,N-diethylnitrosamine (DEN) 24 h after a 70% hepatectomy. Similarly, rats given a single dose of DEN 24 h after a partial hepatectomy and then fed 0.10 or 0.25% of HOS in the diet for 10 months developed a high incidence of hepatocellular carcinomas. In the absence of pretreatment with DEN, dietary administration for at least 4 months of 0.10 or 0.25% of HOS induced significant numbers of enzyme-altered foci; these data and liver tumor induction by continuous feeding of HOS, in the absence of pretreatment with DEN, provide additional evidence for an initiating, as well as a promoting, activity of HOS in rat liver. Concurrent administration of the hepatic sulfotransferase inhibitor pentachlorophenol with HOS in each of the above assays almost completely inhibited the initiating and promoting activities of HOS for the formation of enzyme-altered foci and tumors; these data strongly suggest that both the initiating and promoting activities are mediated by the sulfuric acid ester, 1'-sulfooxysafrole. HOS also exhibited initiating activity in adult mouse liver. Thus, dietary administration of 0.25% of HOS for only 1 month, followed by administration of the hepatic tumor promoter 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene resulted in a high incidence and multiplicity of hepatomas by 10 months. In the absence of the promoter, administration of HOS for only 1 month induced no hepatomas; 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene alone induced only a low incidence. In mice not given the promoter, continuous administration of HOS for 3-6 months was required for hepatoma development by 16 months.