35457752
Nordihydroguaiaretic acid, an inhibitor of lipoxygenase, also inhibits cytochrome P-450-mediated monooxygenase activity in rat epidermal and hepatic microsomes.
Nordihydroguaiaretic acid (NDGA), a plant lignan and phenolic antioxidant, is a known lipoxygenase inhibitor. In this study, we investigated the effect of NDGA on rat epidermal and hepatic monooxygenase activity and its interaction with rat hepatic microsomal cytochrome P-450. The addition of NDGA to epidermal microsomes prepared from control and 3-methylcholanthrene (3-MC)-pretreated rats and hepatic microsomal preparations from control, 3-MC-pretreated, and phenobarbital (PB)-pretreated rats resulted in a concentration-dependent inhibition of aryl hydrocarbon hydroxylase (AHH) and 7-ethoxyresorufin O-deethylase (ERD) activities. The 50% inhibitory dose for NDGA ranged from 4.1 x 10(-5) to 13.1 x 10(-5) M for AHH and ERD activities in these microsomal preparations. The addition of NDGA to hepatic microsomes prepared from PB-pretreated rats resulted in spectral changes characterized by absorbance maxima at 380 nm and minima at 414 nm, typical of type I binding difference spectra. It also showed time- and concentration-dependent inhibition of the binding of carbon monoxide to dithionite or NADPH-reduced cytochrome P-450. We speculate that perhaps hydroxyl groups present in NDGA play an important role in inhibiting the monooxygenase activity and suggest that NDGA may have potential as an antimutagen and/or anticarcinogen. Furthermore, caution must be exercised in elucidating the role of lipoxygenase in metabolic pathways based solely on the criterion of inhibition by NDGA.
22690717
Photodynamic therapy of chemically- and ultraviolet B radiation-induced murine skin papillomas by chloroaluminum phthalocyanine tetrasulfonate.
Photodynamic therapy (PDT) of cancer combines irradiation of tumors with visible light following selective uptake of the photosensitizer by the tumor cells. PhotofrinR-II (Pf-II) is the only photosensitizer which is in clinical use in PDT, whereas chloroaluminum phthalocyanine tetrasulfonate (AlPcTS) has also shown promise in preclinical studies. In most such studies, the effectiveness of the photosensitizers has been assessed in implanted tumor model systems rather than in model systems where tumors are allowed to grow in their own connective tissue matrix. In this study the pharmacokinetics, tumor ablation capability and cutaneous photosensitization response of AlPcTS have been assessed in mice bearing chemically- and ultraviolet B radiation (UVB)-induced benign skin papillomas. When tumor-bearing animals were injected intraperitoneally with AlPcTS (5 mg/kg body wt), maximum tumor:normal skin ratio of 2.4 was observed at 48 h, at which time the mice were irradiated within the absorption spectrum of the photosensitizer. In tumor ablation studies with SENCAR mice bearing chemically-induced skin tumors, AlPcTS resulted in greater than 80% ablation in tumor volume at 20 days post-irradiation. In cutaneous photosensitization response, AlPcTS produced only transient effects (no effect after 24 h) in SENCAR mice. Pharmacokinetics data, tumor ablation effects and cutaneous photosensitization response of AlPcTS were comparable in SKH-1 hairless mice bearing UVB-induced skin tumors. Our data indicate that AlPcTS produces significant photodynamic effects towards the ablation of murine skin tumors, and that it does not produce prolonged cutaneous photosensitivity.
10815047
Metabolism of benzo[a]pyrene by human melanocytes in culture.
Benzo[a]pyrene (B[a]P) is a ubiquitous environmental pollutant and known skin carcinogen. In the present study, in vitro addition of [3H]B[a]P to normal human melanocytes in culture, isolated from adult human skin, resulted in the metabolism of [3H]B[a]P both intracellularly and extracellularly. HPLC analysis showed that [3H]B[a]P-9,10- and 7,8-diol were the major intracellular and extracellular metabolites followed by 3,6-quinone, 9-hydroxy and 3-hydroxy metabolites. Significant amounts of the [3H]B[a]P metabolites were found to be present in the sonicated cell suspension and culture medium as the glucuronide and sulfate conjugates. In total 37.3% of the [3H]B[a]P added in the culture medium was metabolized by melanocytes, of which 21.1% was quantified as the intracellular and 16.2% as the extracellular metabolites. Our data show that human melanocytes are capable of metabolizing B[a]P.
37510627
Evidence for the involvement of singlet oxygen in the photodestruction by chloroaluminum phthalocyanine tetrasulfonate.
In recent years, choloroaluminum phthalocyanine tetrasulfonate (A1PCTS) has been shown to be a promising photosensitizer for the photodynamic therapy (PDT) of cancer. Although its mechanism of photodynamic action is not well defined, A1PCTS is going to be under clinical trials of PDT. In this study, in vitro addition of A1PCTS to a suspension of rat epidermal microsomes followed by irradiation with red light (approximately 675 nm) resulted in significant destruction of cytochrome P-450 and associated monooxygenase activities. The photodestructive effect was dependent on both the dose of A1PCTS and the duration of light exposure. Studies using various quenchers of reactive oxygen species showed that only scavengers of singlet oxygen such as histidine, 2,5-dimethylfuran, beta-carotene and sodium azide afforded substantial protection against photodestruction. Our data indicate the direct involvement of singlet oxygen in the A1PCTS-mediated photodestructive process.
22757148
Involvement of singlet oxygen in chloroaluminum phthalocyanine tetrasulfonate-mediated photoenhancement of lipid peroxidation in rat epidermal microsomes.
In recent studies chloroaluminum phthalocyanine tetrasulfonate (AlPCTS) has been shown to be an effective photosensitizer for the tumor necrosis in a modality known as photodynamic therapy, but the mechanism of photodynamic effect of AlPCTS is poorly understood. In this study, in vitro incubation of rat epidermal microsomes with AlPCTS followed by exposure to red light (approximately 675 nm) resulted in an increase in ADP/iron-supported lipid peroxidation, a measure of membrane damage. This photodestructive effect was found to be dependent on both the duration of light exposure and the dose of AlPCTS. Studies employing various quenchers of reactive oxygen species revealed that scavengers of singlet oxygen (histidine, 2,5-dimethylfuran, beta-carotene and sodium azide) afforded substantial protection (up to 90%) of photoenhancement whereas the scavengers of hydrogen peroxide (catalase), superoxide anion (superoxide dismutase), and hydroxyl radical (sodium benzoate, mannitol and ethanol) were ineffective in this regard. Our data indicate that AlPCTS-mediated photodestruction mainly involves a type II reaction via singlet oxygen formation and suggest that the latter could play a significant role in the tumor necrosis evoked by AlPCTS and light.
7400359
Inhibition of mouse skin tumor-initiating activity of DMBA by chronic oral feeding of glycyrrhizin in drinking water.
Licorice (Glycyrrhiza glabra), a Mediterranean plant, has been used as an antidote, demulcent, and elixir folk medicine for generations in China. The main water-soluble constituent of licorice is glycyrrhizin (GL), which has been shown to possess several pharmacological properties. In this study, we show that oral feeding of GL to Sencar mice resulted in substantial protection against skin tumorigenesis caused by 7,12-dimethyl-benz [a]anthracene (DMBA) initiation and 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion. The latent period prior to the onset of tumor development was considerably prolonged in GL-fed animals compared with animals not fed GL and resulted in significant decrease in the number of tumors per mouse, during and at the termination of the experiment. Oral feeding of GL in drinking water also resulted in inhibition in the binding of topically applied [3H]benzo[a]pyrene and [3H]DMBA to epidermal DNA. The possible mechanism(s) of the antitumor-initiating activity may be due to the involvement of GL as inhibitor of the carcinogen metabolism followed by DNA adduct formation. Our results suggest that GL possesses considerable antitumorigenic activity and could prove useful in protecting some forms of human cancer.
41765492
Effects of magnesium taurate on the onset and progression of galactose-induced experimental cataract: in vivo and in vitro evaluation.
Cataract, a leading cause of blindness, is characterized by lenticular opacities resulting from denaturation of lens proteins due to activation of calcium-dependent enzyme, calpain. Magnesium (Mg(2+)) plays an important role not only in maintaining a low lenticular calcium (Ca(2+)) and sodium concentration but also in preserving the lens redox status. Taurine has also been shown to reduce lenticular oxidative stress. Present study evaluated the anticataract effects of magnesium taurate in vivo and in vitro. Among the five groups of 9 Sprague Dawley rats each, two groups received 30% galactose diet with topical (GDMT) or oral treatment (GDMO) with magnesium taurate. Two groups received 30% galactose diet with topical (GDT) or oral vehicle (GDO). Remaining 1 group received normal diet (ND). Weekly slit lamp examination was done during 21 days experimental period and then all rats were sacrificed; Ca/Mg ratio and antioxidant parameters including reduced glutathione (GSH), catalase and superoxide dismutase (SOD) activities were measured in the isolated lenses using ELISA. In the in vitro study, 2 groups of 10 normal rat lenses were incubated in Dulbecco's Modified Eagle's Medium (DMEM) with galactose while 1 similar group was incubated in DMEM without galactose. In one of the groups, galactose containing medium was supplemented with magnesium taurate. After 48 h of incubation, lenses were photographed and Ca(2+)/Mg(2+) ratio and antioxidant parameters were measured as for in vivo study. The in vivo study, at the end of experimental period, demonstrated delay in the development of cataract with a mean opacity index of 0.53 ± 0.04 and 0.51 ± 0.03 in GDMO (p < 0.05 versus GDO) and GDMT (p < 0.01 versus GDT) respectively. Histopathological grading showed a lower mean value in treated groups, however, the differences from corresponding controls were not significant. Lenticular Ca(2+)/Mg(2+) ratio with a mean value of 1.20 ± 0.26 and 1.05 ± 0.26 in GDMO and GDMT was significantly lower than corresponding controls (p < 0.05) and in GDMT no significant difference was observed from ND. Lenticular GSH and catalase activities were significantly lower and SOD activity was significantly higher in all galactose fed groups. However, in GDMT, GSH and catalase were significantly higher than corresponding control with mean values of 0.96 ± 0.30 μmol/gm lens weight and 56.98 ± 9.86 μmol/g lens protein respectively (p < 0.05 for GSH and p < 0.01 for catalase). SOD activity with mean values of 13.05 ± 6.35 and 13.27 ± 7.61 units/mg lens protein in GDMO and GDMT respectively was significantly lower compared to corresponding controls (p < 0.05) signifying lesser upregulation of SOD due to lesser oxidative stress in treated groups. In the in vitro study, lenses incubated in magnesium taurate containing medium showed less opacity and a lower mean Ca(2+)/Mg(2+) ratio of 1.64 ± 0.03, which was not significantly different from lenses incubated in DMEM without galactose. Lens GSH and catalase activities were restored to normal in lenses incubated in magnesium taurate containing medium. Both in vivo and in vitro studies demonstrated that treatment with magnesium taurate delays the onset and progression of cataract in galactose fed rats by restoring the lens Ca(2+)/Mg(2+) ratio and lens redox status.
28689596
Overcoming barriers that inhibit proper treatment of anemia.
Intravenous (i.v.) iron and recombinant human erythropoietin (EPO), like all other medications, are associated with the risk of adverse events. Historically, the primary concern with iron therapy has been the possibility of iron overload, which exposes the individual to the effects associated with nontransferrin-bound iron. Experience with EPO use has demonstrated an association with hypertension and with the upregulation of a number of markers of inflammation. The impact of these potential adverse effects merits careful analysis, given that both i.v. iron and EPO are designed for long-term use in a patient population at high risk for infection and cardiovascular disease. However, the incidence of iron overload and the risks associated with nontransferrin-bound iron have dramatically been reduced since the introduction of EPO therapy, and no data exist that demonstrate a definitive association between i.v. iron and an increased risk of morbidity related to infection or cardiovascular disease. On the other hand, EPO use is associated with hypertension, endothelial dysfunction, and prothrombotic and inflammatory states in hemodialysis patients. Risks associated with hypertension can be minimized by using the lowest effective EPO dose, which may be achieved through the regular use of i.v. iron. Judicious use of both i.v. iron and EPO may optimize cardiovascular outcomes.
6343189
Mechanisms of angiotensin converting enzyme inhibitor-induced IOP reduction in normotensive rats.
Angiotensin converting enzyme inhibitors (ACEIs) have been shown to lower intraocular pressure (IOP). Since, the ACEIs cause increased tissue prostaglandin levels, we hypothesized that the mechanisms of ACEI-induced IOP reduction have similarity with those of prostaglandin analogs. The present study investigated the involvement of matrix metalloproteinases (MMPs) and cytokine activity modulation as the underlying mechanisms of ACEI-induced ocular hypotension. The IOP lowering effect of single drop of enalaprilat dehydrate 1% was evaluated in rats pretreated with a broad spectrum MMP inhibitor or a cytokine inhibitor. Effect of angiotensin receptor blocker, losartan potassium 2%, was also studied to evaluate involvement of angiotensin II receptor type 1 (AT1) in IOP lowering effect of ACEI. Topical treatment with single drop of enalaprilat resulted in significant IOP reduction in treated eye with mean peak reduction 20.3% at 3h post-instillation. Treatment with losartan resulted in a peak IOP reduction of 13.3%, which was significantly lower than enalaprilat, indicating involvement of mechanisms in addition to AT1 blockade. Pretreatment with a broad spectrum MMP inhibitor or a cytokine inhibitor significantly attenuated the enalprilat-induced IOP reduction with mean peak IOP reduction of 11.2% and 13.6% respectively. The IOP-lowering effect of enalaprilat seems to be attributed to reduced angiotensin II type 1 receptor stimulation and modulation of MMP and cytokines activities.
44919999
Asymptomatic incomplete left ventricular apical rupture diagnosed by cardiac magnetic resonance imaging.
66-year-old man presented with a fever of 103 °F, cough, and dyspnea, despite 3 days' treatment of pneumonia. Chest radiography revealed a normal cardiac silhouette and a small left pleural effusion. A baseline electrocardiogram (ECG) showed normal sinus rhythm with profound ST-segment elevation in the anterolateral leads. An ECG obtained 2 months earlier was normal. An echocardiogram showed severe hypokinesis of the anterior, anteroseptal, and apical segments without evidence of a pericardial effusion. Coronary angiography revealed complete occlusion of the proximal left anterior descending coronary artery with severe distal anterior hypokinesis. 
 
Forty-eight hours after admission, the patient had recurrent fever. A repeat transthoracic echocardiogram (Fig. 1) revealed a thin, aneurysmal, left ventricular (LV) apex with pericardium apparently adherent to the apex. In addition, a moderate-to-large, echo-free pericardial effusion was noted. Out of clinical concern for a possible contained LV rupture, cardiac magnetic resonance imaging (CMR) was performed for definitive evaluation and tissue characterization. 
 
 
 
Fig. 1 Transthoracic echocardiogram (4-chamber view at end-systole) reveals an apex-sparing pericardial effusion and an aneurysmal left ventricular apex. 
 
 
 
The CMR (Figs. 2 and 3) revealed evidence of a large myocardial infarction (MI) with subsequent aneurysm formation involving the distal half of the left anterior descending artery distribution and the entire apex, with an extensive amount of thrombus in the apex. A “hinge-point” involving the lateral and anterolateral walls was noted, raising the concern of a possible contained rupture of the LV apex. A large, predominantly simple-appearing pericardial effusion was noted circumferentially, but the apex was spared. The pericardium was hyperenhanced on viability/ scar imaging in the regions of infarct, suggesting post-MI pericarditis. 
 
 
 
Fig. 2 Cine cardiac magnetic resonance imaging demonstrates a large aneurysmal area involving the distal half of the left anterior descending coronary artery distribution with an extensive amount of thrombus at the apex. A hinge-point involving the lateral ... 
 
 
 
 
 
Fig. 3 Viability/scar imaging reveals a transmural infarction of the affected area. The remainder of the left ventricular myocardium appears to be of full thickness and viable. There is also hyperenhancement of the pericardium in the infarct regions, ... 
 
 
 
A follow-up echocardiogram performed 1 week later showed a slight decrease in the size of the pericardial effusion. Repair of the LV was deferred until effective surgical suturing could be performed on the infarcted area. 
 
Eight weeks later, the patient underwent successful LV endoaneurysmorrhaphy with a Dacron patch. Intraoperatively, a 3- × 4-cm balloon-like aneurysm was found to be fused to the pericardial sac. The aneurysm was excised, and subsequent microscopic evaluation revealed necrotic myocardium and reactive connective tissue (Fig. 4). The patient had an uneventful hospital course and was discharged from the hospital in stable condition. At a follow-up visit 2 months later, he reported a substantial increase in exercise tolerance and a return to usual daily activities. 
 
 
 
Fig. 4 Photomicrograph illustrates necrotic myocardium and adjacent reactive connective tissue. (H & E, orig. ×100)
22856684
Prediction of hypertension in chronic hemodialysis patients.
BACKGROUND
There are no universally accepted criteria for the diagnosis of hypertension in hemodialysis (HD) patients. We sought to determine the clinical performance of predialysis and postdialysis systolic and diastolic blood pressure values (BPs) in diagnosing hypertension or assessing its control.


METHODS
Seventy patients [77% African American, 46% females, mean age 59 +/- 17 (SD) years, 34% diabetics] on chronic HD underwent a single 44-hour interdialytic ambulatory blood pressure monitoring (ABPM) and concomitant recording of BP by conventional syphygmomanometer in the HD unit for two weeks. Hypertension was defined as systolic BP (SBP) > or =135 mm Hg or diastolic BP (DBP) > or =85 mm Hg on an average 44-hour ABPM.


RESULTS
Average ABP was 144 +/- 22/81 +/- 11 mm Hg. Seventy-three percent of the patients had systolic hypertension; 40% had diastolic hypertension, and 24% were normotensive or had well-controlled BP. Area under the curve of receiver operating characteristic (ROC) curves exceeded 80% for all BPs, but the thresholds for best sensitivity and specificity were markedly different for predialysis and postdialysis BPs. A two-week averaged predialysis BP of > 150/85 mm Hg or a postdialysis BP of > 130/75 mm Hg had at least 80% sensitivity in diagnosing hypertension. Specificity of at least 80% was achieved if predialysis BP of > 160/90 mm Hg or postdialysis BP of > 140/80 mm Hg was used. There was poor agreement between HD unit BP and ABP values.


CONCLUSIONS
HD unit BP values can be used to identify the presence or absence of hypertension, although prediction of ambulatory BPs from HD unit BP values cannot be made reliably in individual patients.