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PubMed2001

The distribution of refractory periods influences the dynamics of ventricular fibrillation.

The spatial and dynamic properties of ventricular fibrillation (VF) may be random or related to cellular electrical properties of the normal heart. Local activation intervals (AIs) in VF may depend on the local refractory period (RP), and sustained VF may require a steep action potential (AP) restitution curve. In guinea pig hearts, AP durations (APDs) and RPs on the epicardium are shorter at the apex and progressively longer toward the base, producing gradients of RPs that may influence the spatial organization of VF. In the present study, the influence of APDs on VF dynamics is investigated in perfused guinea pig hearts stained with a voltage-sensitive dye by comparing APD gradients to the dynamics of VF elicited by burst pacing. In VF, AIs had no clear periodicity, but average AIs were shorter at the apex (57.5+/-8.1 ms) than the base (76.1+/-1.5 ms, n=6, P<0.05) and had gradients similar to APD gradients (correlation coefficient 0.71+/-0.04). Analysis of local velocity vectors showed no preferential directions, and fast Fourier transform (FFT) power spectra were broad (10 to 24 Hz) with multiple peaks (n=6). However, the selective inhibition of delayed K(+) rectifying currents, I(Kr) (E4031; 0.5 micromol/L, n=3), shifted FFT spectra from complex to a lower dominant frequency (10 Hz) and altered repolarization but retained the correlation between mean AIs and RPs. Thus, VF dynamics are consistent with a multiple wave-make and wave-break mechanism, and the local RP influences VF dynamics by limiting the range of VF frequencies and AIs at each site. The full text of this article is available at http://www.circresaha.org.

Action Potentials↗
PubMed2006

Novel concepts for the chemoprevention of breast cancer through aromatase inhibition.

Aromatase inhibitors (AIs) have a proven role in the treatment of early and metastatic breast cancer. The success of tamoxifen in reducing the relative risk of developing hormone-sensitive breast cancer in chemoprevention trials has been hampered by their long-term toxicity profile. AIs have the potential to further reduce rates of breast cancer in high-risk postmenopausal women. This article reviews the evidence to support the potential efficacy of AIs in the chemoprevention setting. It particularly focuses on a discussion of novel concepts of utilising AIs, so that they reduce breast cancer risk while minimising systemic toxicity, and highlights the importance of accurately developing risk prediction algorithms.

Anticarcinogenic Agents↗
PubMed1993

Hemodynamic effects of amlodipine and benazeprilat in spontaneously hypertensive rats.

We wished to assess the hemodynamic effects of administration of the combination of the calcium channel blocking agent amlodipine and the angiotensin-converting enzyme (ACE) inhibitor benazeprilat in conscious spontaneously hypertensive rats (SHR). In SHR previously instrumented for measurement of mean arterial blood pressure (MAP) and heart rate (HR), intravenous (i.v.) injection of amlodipine (0.25-4 mg/kg) produced dose-dependent decreases in blood pressure (BP). Administration of benazeprilat (0.1-10 mg/kg i.v.) decreased arterial MAP, and benazeprilat (10 mg/kg) effectively blocked the effects of exogenously administered angiotensin I (AI). In animals surgically prepared for measurement of BP, HR, and hindquarter, renal, and mesenteric blood flows, administration (i.v.) of the combination of amlodipine (0.5 mg/kg) with benazeprilat (10 mg/kg) evoked a decrease in BP that was greater than that elicited by monotherapy. The tachycardic response observed after administration of the combination was no different from that observed after monotherapy with amlodipine. Simultaneous administration of amlodipine and benazeprilat produced reductions in vascular resistance in the hindquarter, renal and mesenteric beds that were greater than the responses evoked by injection of either agent. The major finding of these studies was that dual therapy with amlodipine and benazeprilat produced an additive hypotensive effect in conscious SHR. Regional vasodilation accompanied the large degree of hypotension evoked by the combination.

Amlodipine↗
PubMed2005

Mechanisms of endocrine resistance and novel therapeutic strategies in breast cancer.

Tamoxifen has been the mainstay of hormonal therapy in both early and advanced breast cancer patients for approximately three decades. The availability of novel compounds such as aromatase inhibitors (AIs) and fulvestrant, with different mechanism of action, is changing the scenario of endocrine treatment of postmenopausal breast cancer patients. In this review article, we have summarized the current knowledge of the mechanisms of resistance to endocrine therapy, in order to derive information that might be useful for therapeutic intervention. We propose that resistance to endocrine therapy is a progressive, step-wise phenomenon induced by the selective pressure of hormonal agents, which leads breast cancer cells from an estrogen-dependent, responsive to endocrine manipulation phenotype to a non-responsive phenotype, and eventually to an estrogen-independent phenotype. In particular, evidence suggests for each 'action' introduced to block estrogen stimulation of breast cancer cells (i.e. treatment with anti-estrogen), there are one or more corresponding 'reactions' that tumor cells can use to escape our attempts to block their growth: estrogen hypersensitivity associated with increased transcriptional activity of estrogen receptor alpha (ERalpha) and/or increased non-genomic activity of ERalpha, estrogen supersensitivity, increased growth factor signaling, suppression of ERalpha expression and finally estrogen independence. Activation of growth factor signaling is involved in each step of this phenomenon, and might ultimately substitute estrogen in sustaining the growth and the survival of breast cancer cells. In this respect, results of pre-clinical and clinical studies with AIs, fulvestrant and signaling inhibitors sustain this hypothesis. More importantly, the knowledge of the mechanisms involved in the resistance of breast cancer cells to endocrine therapy offers potential for novel therapeutic strategies.

Antineoplastic Agents, Hormonal↗
PubMed1986

A comparison of different formulations and dosage administrations of gemfibrozil.

To assess the lipid-regulating effects of 2 new gemfibrozil formulations, a nonblind parallel group comparison was performed using Finnish industrial workers with types IIA and IIB primary hyperlipoproteinemia. In all, 670 subjects were evaluated; 416 had total low density lipoprotein (LDL) cholesterol (serum total cholesterol--high density lipoprotein [HDL] cholesterol) levels greater than or equal to 200 mg/dl and thus qualified for the screening period of the trial. During this 2-month period, the subjects were placed on an optimal diet according to their Fredrickson phenotype. Those whose total LDL levels remained greater than or equal to 200 mg/dl until the end of the 2-month period (n = 321) were admitted to the active drug phase of the trial and randomized to 1 of 3 treatment groups. Group 1 received the standard gemfibrozil dosage of two 300-mg capsules 2 times a day, for a total daily dosage equal to 1,200 mg. Group 2 also received a 1,200-mg daily dose, given as a 600-mg tablet of gemfibrozil 2 times a day. Group 3 received a once-a-day dose of two 450-mg tablets in the evening. Preliminary results show that the alternate gemfibrozil formulations are thus far equal to the standard gemfibrozil dosage in their effects on blood lipids. Substantial decreases have been noted in serum cholesterol, serum triglycerides, LDL cholesterol and serum apolipoprotein B. The 3 formulations also produced similar increases in HDL cholesterol and its subfractions HDL2 and HDL3, as well as in serum apolipoproteins AI and AII.

Administration, Oral↗
PubMed2004

Rapid oligosaccharide synthesis using a fluorous protective group.

The Bfp-OH, a novel fluorous protecting reagent, was able to be easily prepared. The Bfp group was readily introduced to a carbohydrate, removed in high yield, and recyclable after cleavage. The use of the Bfp group made it possible to synthesize a pentasaccharide by minimal column chromatography purification. Each synthetic intermediate was able to be easily purified only by simple fluorous-organic solvent extraction and monitored by TLC, NMR, and MS.

Catalysis↗
PubMed2004

Intravenous vitamin D therapy reduces PTH-(1-84)/large C fragments ratio in chronic hemodialysis patients.

BACKGROUND: Renal osteodystrophy is one of the major complications in patients with chronic renal failure. Large C-PTH fragments are secreted from the parathyroid glands and exert antagonistic actions against PTH-(1-84). The PTH-(1-84)/large C-PTH fragments ratio reflects both biosynthesis and processing of PTH; however the alteration of the ratio under vitamin D therapy has not been investigated. METHODS: Seventeen hemodialysis patients with intact PTH levels of >300 pg/ml were enrolled. Calcitriol or maxacalcitol were administered intravenously for 78 weeks. Intact PTH, PTH-(1-84), and the PTH-(1-84)/large C-PTH fragments ratio were measured at 0, 13, 26, 52 and 78 weeks. RESULTS: Intact PTH and PTH-(1-84) levels, which were 492.0 +/- 115.7 and 303.4 +/- 105.4 pg/ml, respectively, at baseline, significantly decreased at the end of the study to 268.9 +/- 121.9 (p < 0.0001) and 190.7 +/- 106.9 pg/ml (p = 0.0008), respectively. In contrast, large C-PTH fragments, which were 152.7 +/- 53.5 pg/ml at baseline, did not significantly change at 78 weeks (144.5 +/- 72.2 pg/ml, p = 0.7612). Consequently, the PTH-(1-84)/large C-PTH fragments ratio was significantly reduced from 2.25 +/- 1.31 to 1.47 +/- 0.89 (p = 0.0004). CONCLUSION: The PTH-(1-84)/large C-PTH fragments ratio reflects the change of PTH biosynthesis, processing and secretion from the parathyroid glands, and it may be a beneficial marker to evaluate the overall biological PTH action and predict bone turnover status in hemodialysis patients under intravenous vitamin D therapy.

Acid Phosphatase↗
PubMed2005

Premorbid antiplatelet use and ischemic stroke outcomes.

OBJECTIVE: To evaluate the independent effect of premorbid antiplatelet use on incident ischemic stroke severity and outcome at discharge. METHODS: The authors studied consecutive patients presenting within 24 hours of ischemic stroke over a 1-year period. National Institutes of Health Stroke Scale (NIHSS) score at presentation was used as index of stroke severity and a modified Rankin scale of 0 to 1 at discharge as index of good functional outcome. Patients were categorized according to their premorbid antiplatelet use as antiplatelet-inclusive (AI) and no antiplatelet (NA). Demographic data, risk factors, pertinent laboratory tests, other medications, and stroke mechanisms were controlled for across the two groups using multivariate logistic regression. RESULTS: A total of 260 individuals met study criteria: 92 patients were on antiplatelet agents prior to admission, 168 were on no antiplatelets. Pretreatment with antiplatelet was associated with lower presenting median NIHSS (4.5 vs 7, p = 0.005). Antiplatelet use was associated with less severe stroke at presentation in those having no history of stroke or TIA (4.8 vs 8.0, p = 0.03) but not in those with a prior history of stroke or TIA (4.9 vs 4.9, p = 0.987). The likelihood of a good outcome was increased in those on antiplatelets after adjusting for other variables (OR 2.105, p = 0.0073). CONCLUSIONS: Prestroke use of antiplatelet may be associated with reduced severity of incident ischemic strokes in those with no prior history of stroke or TIA, and with an increased likelihood of a good discharge outcome regardless of prior cerebrovascular event history.

Aged↗
PubMed2005

[Clinical study of teicoplanin in the treatment of patients with gram-positive cocci: the Chinese experience].

OBJECTIVE: To evaluate the efficacy and safety of Teicoplanin (TEC) in the treatment of Chinese patients with moderate and severe Gram positive (G(+)) coccus infections. METHODS: A prospective, multicenter, non-comparator control, open-label drug clinical trial of phase IV was conducted. RESULTS: Totally 156 cases with established and highly suspected G(+) coccus infections are enrolled. Mean age was 53.6 +/- 20.9 (9-93). The infections included: lower respiratory tract infections (66.0%), sepsis (9.0%), catheters-associated infections (5.1%), endocarditis (1.9%), leucopenia with fever (14.1%), bone-joint infections (1.3%), skin-soft tissue infections (7.7%), and other infections (10.9%). Eighty seven point eight percent of the patients suffered from severe underlying diseases, 28.2% (44/156) had immunocompromised conditions. 69.2% had received antibiotics previously (57.4% with cephalosporins and 28.7% with carbapenem, respectively). One hundred and thirty strains of G(+) cocci were isolated from 123 patients (78.8%). Among them methicillin-resistant Staphylococcus aureus (MRSA) accounted for 90.7% (49/54) and methicillin-resistant coagulase-negative Staphylococcus (MRCNS) 88.2% (30/34). The TEC susceptibility test for 105 strains showed that all of the Staphylococci and Enterococci were susceptible. In 121 strains tested for vancomycin, all of the Staphylococci but only 78.3% (18/23) of the Enterococci were susceptible. There were 18 strains of Gram negative bacilli and 1 strain of Candida A. isolated concomitantly with G(+) cocci from 17 cases. The total clinical effectiveness was 82.1% by ITT (156 cases) analysis and 85.2% by PP (135 cases) analysis, respectively. Bacteriologic eradication rate was 87.7%. Thirty three patients with negative culture result were empirically treated with TEC and had 96.8% of clinical effectiveness. The efficacy of TEC to different infections was similar. The total adverse effects, such as decrease in blood cells and transient abnormal liver functions, accounted only for 1.28%. CONCLUSIONS: Teicoplanin was a very effective antibiotic for G(+) coccus infections and safe for patients. In highly suspected infections with methicillin-resistant Staphylococci or Enterococci, TEC may be a choice for initial empirical treatment.

Adolescent↗
PubMed2006

[Liangge san effects the expression of CD14 and scaverger receptor in the Kupffer cells of liver of endotoxemia mice].

OBJECTIVE: To study the effects of Liangge San to the expression of CD14 and scaverger receptor(SR) in the kupffer cells of liver and the pathological changes of liver tissue of endotoxemia-mice. METHOD: The model was established with intravenous injection of lipopolysaccharide (LPS) and at the same time different dose Liangge San were given. The expression of CD14 and scaverger receptor were detected with immunohigtochemistry at the 2nd, 4th, 8th hour ofter injury and analyzed with computer image system, and the pathological changes of liver tissue were also observed. RESULT: At the three different hours, the expression of CD14 and scaverger receptor in macrophages of liver of LPS-injury group showed significant increase and significant decrease respectively, compared with that of the blank-control group (P < 0.01). The expression in dexamethasone group and Liangge San different dose groups were intermediate between those in injury group and those in control group. Compared with expression of LPS-injury group, those of dexamethasone group and Liangge San different dose groups showed significant differences (P < 0.01), especially that of Liangge San high dose group. Liver cells showed vacuole change. Changes of CD14 and SR expression were paralleled with the severity of liver damages of the mice. CONCLUSION: Liangge San can inhibite the up-regulation of CD14 expression and down-regulation of scaverger receptor expression in a dosage-dependent manner and also alleviate the damages of liver induced by LPS.

Animals↗
PubMed1977

Efficiency of praziquantel, a new cesticide, against Taenia hydatigena in the dog.

Praziquantel (2 - cyclohexylcarbonyl - 1,3,4,6,7,11b - hexahydro - 2H - pyrazino (2,1 - a) isoquinolin - 4 - one) was tested against artificially established infections of Taenia hydatigena in 39 dogs. The formulation used was a 660 mg tablet containing 50 mg of active ingredient (ai). A single oral dose at 1 mg/kg ai completely removed 14-day-old infections in all dogs. 2.5 mg/kg ai praziquantel was completely effective against 7, 14 and 28-day-old worms. 5 mg/kg ai completely removed two-day-old infestations. No side effects were seen in any treated dog.

Animals↗
PubMed1996

Role of enterobactin and intracellular iron in cell lethality during near-UV irradiation in Escherichia coli.

In Escherichia coli, fur mutants that constitutively express their native iron chelating agent, enterobactin, are significantly more sensitive to near-UV radiation (NUV) than wild type, An entA mutant, which is incapable of synthesizing enterobactin, is equal to wild type in resistance to NUV irradiation. However, the addition of Fe+3 enterobactin but not AI+3 enterobactin to entA cell suspensions just prior to irradiation results in an increased sensitivity to NUV irradiation. A fes mutant, which is unable to reduce and release iron from enterobactin, is significantly more sensitive to NUV irradiation than wild type. The addition of nontoxic levels of H2O2 (5 microM) just prior to irradiation significantly increases sensitivity of both fur and fes mutants. These results suggest that one mechanism by which NUV irradiation leads to cell lethality is by creating a transient iron overload, producing very favorable conditions for the production of highly deleterious free radicals through a variety of mechanisms that lead to oxidative stress and DNA damage including lethal and mutagenic lesions. These results are consistent with the hypothesis that enterobactin is an endogenous chromophore for NUV and contributes to cell lethality via the destruction of its ligand, releasing Fe+2 into the cytoplasm to catalyze the production of highly reactive hydroxyl radicals and other toxic oxygen species via the Haber-Weiss reaction.

Enterobactin↗
PubMed2005

Vaginal contraceptive activity of a chelated vanadocene.

Bis(cyclopentadienyl) complexes of vanadium (IV) or vanadocenes are rapid and potent inhibitors of human sperm motility with potential as a new class of contraceptive agents. This study sought to determine the vaginal contraceptive activity of vanadocene dithiocarbamate (VDDTC), a stable vanadocene (IV)-chelated complex, using the standard rabbit model as well as the domestic pig as a physiologically relevant animal model for contraception. In experiment I, ovulating New Zealand White does in subgroups of eight were artificially inseminated (AI) with semen mixed with VDDTC (0.01-1 mM) or vehicle. In experiment II, ovulating does in subgroups of 18 were AI at 5 and 60 min after intravaginal application of a gel with and without 0.1% VDDTC or 2% nonoxynol-9 (N-9) (Gynol II, Ortho Pharmaceutical, Raritan, NJ), and allowed to complete term pregnancy. In experiment III, seven sexually mature Duroc gilts in standing estrus were AI with and without intravaginal application of 0.1% VDDTC gel microemulsion. Exposure of rabbit semen to VDDTC at the time of artificial insemination resulted in a dose-dependent reduction in fertility. Exposure of semen to 1 mM VDDTC led to complete inhibition of fertility as assessed by the number of embryos (control 49/94 vs. VDDTC-treated 0/117, p<.0001) or the percent embryos (52% vs. 0%, respectively) based on number of embryos to corpora lutea. Intravaginal administration of 0.1% VDDTC gel microemulsion or Gynol II prior to artificial insemination significantly inhibited term pregnancy rates (88% and 62% inhibition, respectively) when compared to control gel alone. Vanadocene dithiocarbamate gel microemulsion provided 80% inhibition of fertility even when insemination was delayed until 60 min after intravaginal application of VDDTC gel microemulsion. Rabbits that delivered litters despite intravaginal exposure of semen to VDDTC via gel microemulsion had healthy offsprings with no apparent perinatal repercussions. In domestic pigs, intravaginal applications of 0.1% VDDTC gel microemulsion prior to artificial insemination led to complete inhibition of fertility as assessed by the number of embryos (control 29/52 vs. VDDTC-treated 0/44, p<.0001) or the percent embryos (56% vs. 0%, respectively) based on the number of embryos to corpora lutea. These results suggest that VDDTC is a potent contraceptive agent in vivo. Intravaginal use of VDDTC via a gel microemulsion has clinical potential as a safe alternative to currently used detergent-type contraceptives.

Administration, Intravaginal↗
PubMed2003

Evaluation of an antibiotic-impregnated shunt system for the treatment of hydrocephalus.

OBJECT: Staphylococcus species are the most common organisms responsible for infection following implantable cerebrospinal fluid (CSF) diversionary procedures. The role of an antibiotic-impregnated shunt (AIS) system in the prevention of shunt infection has remained unclear because no human clinical trial has been reported on thus far. In this study, the authors assess an AIS system with respect to its prevention of shunt infection. METHODS: Patients were prospectively randomized into groups to evaluate the efficacy of an AIS system against an identical control shunt system. The data accrued were subjected to a detailed statistical analysis. Logistic regression analysis was performed to determine the independent association between outcome and predictor variables. Shunt function analysis was also performed to compare the average time to infection between the two groups. One hundred ten patients were recruited; 60 received control shunt systems and 50 received AIS systems. Thirteen shunt infections were recorded (10 in the control group and three in the AIS group). Nine (69%) of 13 infections occurred within 2 months after shunt implantation (eight of 10 in the control group and one of three in the AIS group). Apart from one patient in whom no organism was identified, a total of 14 organisms (12 patients) were cultured from either the CSF (nine) or the shunt apparatus (three). Staphylococcus species accounted for the majority of shunt infections (83%): all 10 control shunts were found to have a positive culture of staphylococci, whereas none of the AISs had any staphylococci (p = 0.038). CONCLUSIONS: The AIS afforded antistaphylococcal protection, especially during the early postoperative period when most shunt infections are known to occur and throughout the follow-up period (median 9 months). The AIS system represents another important tool to enable the neurosurgeon to prevent shunt infections.

Adolescent↗
PubMed2006

Cytotoxicity and antigenicity of antimicrobial synthesized peptides derived from the beetle Allomyrina dichotoma defensin in mice.

Synthetic peptides, peptides A (Arg-Leu-Tyr-Leu-Arg-Ile-Gly-Arg-Arg-NH(2)) and B (Arg-Leu-Arg-Leu-Arg-Ile-Gly-Arg-Arg-NH(2)), derived from the beetle Allomyrina dichotoma defensin, have antimicrobial activities. Immunotoxicological effect of these peptides was evaluated by cytotoxicity of mouse peritoneal macrophages. In addition, antigenicity of these peptides was studied by evaluating antibody responses in mice immunized with these peptides. The toxicity of peptide A toward mouse peritoneal cells was less than that of polymyxin B, when morphologically evaluated in a cytotoxicity test. Almost all of mice injected intraperitoneally (i.p.) with either peptide A or B at 50-150 mg/kg survived, whereas all mice injected i.p. with polymyxin B at the doses of more than 25 mg/kg died within 24 h. Interestingly, almost all of mice injected intravenously with these peptides at the doses of 10 and 25 mg/kg also survived. Furthermore, mice immunized with these peptides conjugated with keyhole limpet hemocyanin (KLH) showed little or negligible anti-peptide A or B antibody production, although anti-KLH antibody was significantly produced. The results indicated that peptides A and B were less cytotoxic than polymyxin B and also had poor antigenicity to produce specific antibody in mice.

Animals↗
PubMed2003

Cytotoxic constituents of Isodon rubescens var. lushiensis.

Five new ent-kaurane diterpenoids, ludongnins F-J (1-5), along with 10 known compounds, guidongnins A-C (6-8), angustifolin (9), 6-epiangustifolin (10), sculponeatin J (11), gardenin D, 5,3',4'-trihydroxy-6,7,8-trimethoxyflavone, pedalitin, and quercetin, were isolated from the leaves of Isodon rubescens var. lushiensis. The structures of 1-5 were determined by spectroscopic analysis, as well as X-ray crystallographic analysis of 1. Compounds 1-11 were evaluated against K562 leukemia cells for their cytotoxic effects.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Neo-adjuvant chemotherapy for operable breast cancer induces apoptosis.

The use of neo-adjuvant chemotherapy (often referred to as pre-operative or primary chemotherapy) represents a major change in the management of breast cancer as a systemic disease. Laboratory studies have shown that many anti-cancer agents with differing modes of action achieve cytotoxic effects by inducing apoptosis. In this study, we investigated the induction of apoptosis by neo-adjuvant chemotherapy in human breast cancer. The aim was to determine whether a correlation existed between post chemotherapy apoptotic index (AI) and clinical response and patients' survival. Our results indicate that apoptosis is induced by neo-adjuvant chemotherapy and that the response is variable. Our data show that post chemotherapy AI correlated with clinical response and increased patient survival, including both relapse (disease) free survival and overall survival. Post-neo-adjuvant chemotherapy AI levels in primary breast cancer may possibly predict an individual patient's overall response.

Adult↗