Greater antiarrhythmic activity of acute 17beta-estradiol in female than male anaesthetized rats: correlation with Ca2+ channel blockade

BACKGROUND AND PURPOSE

Female sex hormones may protect pre-menopausal women from sudden cardiac death. We therefore investigated the effects of the main female sex hormone, 17beta-estradiol, on ischaemia-induced cardiac arrhythmias and on the L-type Ca2+ current (ICaL).

EXPERIMENTAL APPROACH

In vivo experiments were performed in pentobarbital-anaesthetized rats subjected to acute coronary artery occlusion. ICaL was measured by the whole-cell patch-clamp technique, in rat isolated ventricular myocytes.

KEY RESULTS

Acute intravenous administration of 17beta-estradiol as a bolus dose followed by a continuous infusion, commencing 10 min before coronary artery occlusion, had dose-dependent antiarrhythmic activity. In female rats 300 ng kg(-1) + 30 ng kg(-1) min(-1) 17beta-estradiol significantly reduced the number of ventricular premature beats (VPBs) and the incidence of ventricular fibrillation (VF). A ten fold higher dose of 17beta-estradiol was required to cause similar effects in male rats. In vitro 17beta-estradiol reduced peak ICaL in a concentration-dependent manner. The EC50 was ten-fold higher in male myocytes (0.66 microM) than in females (0.06 microM).

CONCLUSIONS AND IMPLICATIONS

These results indicate that 17beta-estradiol has marked dose-dependent antiarrhythmic activity that is greater in female rats than in males. A similar differential potency in blocking ICaL in myocytes from female and male rats can account for this effect. This provides an explanation for the antiarrhythmic activity of 17beta-estradiol and gender-selective protection against sudden cardiac death.

Clinical outcome of taxane-resistant (TR) hormone refractory prostate cancer (HRPC) patients (pts) treated with subsequent chemotherapy (ixabepilone (Ix) or mitoxantrone/prednisone (MP)

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Background: The clinical course of TR HRPC pts has not previously been evaluated in a large, prospective study. No standard treatment exists for this pt population, although MP is frequently used. Ix is an epothilone B analogue with activity against TR cell lines. Methods: Metastatic HRPC pts with disease progression during or within 60 days of stopping T chemotherapy were eligible. In a 2-arm, non-comparative randomized phase II study, pts were assigned to receive either: 1) M 14 mg/m2 IV q3wks and P 5 mg PO BID or 2) I × 35 mg/m2 IV q3wks. Crossover was allowed for progression or toxicity. The study’s primary endpoint was to detect a ≥ 50% PSA decline by Consensus Criteria in at least 25% of 2nd-line pts (H0 = 10%, α = 0.04, β = 0.18 for each arm). Pts were followed for survival. Results: Forty-one evaluable pts each were accrued to Ix and to MP. The median follow-up is 5.0 months (range: 0.3–19.5). The median number of cycles administered to each 2nd-line arm is 3 (range: Ix: 1–8, MP: 1–12). Median survival from protocol entry is 13.0 months with Ix and 12.5 months with MP. Confirmed 2nd-line post-therapy (rx) ≥50% PSA declines were observed in 17% of Ix pts (95% CI = 7–32) and 20% of MP pts (95% CI = 9–35). Of pts with measurable disease, partial responses were observed in 1/18 pts on 2nd-line Ix (6%; 95% CI = 0.1–27.3) and in 1/15 pts on 2nd-line MP (7%; 95% CI = 0.2–31.9). Median duration on 2nd-line Ix and MP was 2.2 months and 2.3 months, respectively. Crossover to 3rd-line rx occurred in 39% of Ix pts and 68% of MP pts. Confirmed 3rd-line post-rx ≥50% PSA declines were observed in 3/24 Ix pts and in 4/13 MP pts. The most common grade 3/4 toxicity associated with 2nd-line rx was neutropenia as previously reported (41% of Ix pts, 54% of MP pts). Conclusions: This prospective trial has characterized TR HRPC pts as having an observed median survival of approximately 1 year. This may be a useful reference for the screening of effective agents in the 2nd-line setting for TR HRPC. Both Ix and MP appear to have only modest activity as 2nd- and 3rd-line rx in this highly selected TR HRPC population. This study was supported by Bristol-Myers Squibb and the Prostate Cancer Foundation.

No significant financial relationships to disclose.

Absolute PSA value after androgen deprivation (AD) is a strong independent predictor of survival in new metastatic (D2) prostate cancer (PCa): Data from Southwest Oncology Group Trial 9346 (INT-0162)

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Background: PSA is a biomarker for monitoring disease activity in PCa. It is not well established if absolute PSA values achieved after AD is prognostic in patients (pts) with new D2 PCa. Methods: Hormone naive D2 pts with baseline PSA ≥ 5ng/mL are treated with 7 months (ms) AD induction. Pts achieving PSA-n (PSA ≤ 4.0 ng/ml that is stable or declining on ms 6 and 7) are randomized to continuous vs. intermittent AD on month 8. To be eligible for this analysis (approved by Data Safety Monitoring Committee), pts had to have a prestudy PSA with at least 2 subsequent PSAs during induction and be registered at least 1 year prior to analysis date. Survival was defined from 8 months to death due to any cause. Associations were evaluated by proportional hazards regression models. P≤0.05 was statistically significant. Results: Of the first 1,395 registered pts, 1345 were eligible for this analysis. Median age was 70 years, median baseline PSA 76.1 ng/mL, 38% had bone pain (BP) and 47 % had Gleason sum (GS) > 7. Median number of on-study PSAs during induction was 5 (range: 2 -18). Of the 1,345 pts, 1134 achieved PSA-n with 965 maintaining PSA-n at end of induction. Of those achieving PSA-n, 604 (45% of all pts) had an undetectable PSA (PSA-u, ≤ 0.2 ng/mL) at end of induction. In multivariate analysis, 4 significant independent risk factors were associated with post-induction survival: Performance status, GS, BP, and being randomized. After adjustment for these factors, pts who had a PSA-n at the end of induction but not PSA-u had less than half the risk of death (RoD) as those who did not have PSA-n (HR: 0.41; 95% CI 0.32, 0.54, p < 0.001), and pts with PSA-u had about one-quarter the RoD as pts with no PSA-n (HR: 0.26; 95% CI 0.20, 0.35, p < 0.001). After adjustment for covariates, pts with PSA-u had significantly better survival than those with only PSA-n at end of induction (p < 0.001). The median overall survival was 13 ms for the 383 not normalized (95% CI: 11 to 16 ms), 44 ms for the 360 pts normalized but not undetectable (95% CI: 39 to 55 ms), and 75 ms for the 602 pts with PSA-u (95% CI: 62, 91 ms). Conclusion: Achieving a PSA-n or PSA-u after 7 ms of AD is a strong predictor of survival and should be used to tailor future trial design in new D2 pts.

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Mobilisation into cotton and spread of a recombinant cotton leaf curl disease satellite

Analysis of a DNA beta satellite associated with a recently identified cotton leaf curl disease (CLCuD) strain indicated it to be recombinant, with most of the molecule originating from CLCuD DNA beta but with some sequence from a satellite isolated from tomato. Analysis of both archival (pre 2001) and recent cotton samples, shows the recombinant satellite is confined to a small area but was not present in cotton prior to 2001. This indicates that the recombinant DNA beta was recently mobilized into cotton, likely from tomato, and that recombination plays a role in the evolution of these satellites.

A longitudinal household study of Streptococcus pneumoniae nasopharyngeal carriage in a UK setting

A 10-month longitudinal household study of pre-school children and their families was undertaken with monthly visits collecting epidemiological data and nasopharyngeal swabs in Hertfordshire, England from 2001 to 2002. Pneumococcal culture was with standard methods. In total, 121 families (489 individuals) took part. Mean prevalence of carriage ranged from 52% for age groups 0-2 years, 45% for 3-4 years, 21% for 5-17 years and 8% for >or=18 years. Carriage occurred more than once in 86% of children aged 0-2 years compared to 36% of those aged >or=18 years. The most prevalent serotypes in the 0-2 years age group were 6B followed by 19F, 23F, 6A and 14. Young children were responsible for the majority of introductions of new serotypes into a household. Erythromycin resistance (alone or in combination) occurred in 10% of samples and penicillin non-susceptibility in 3.7%. Overall the recently licensed 7-valent conjugate vaccine (PCV) would protect against 64% of serotypes with no intra-serogroup cross protection and 82% with such protection. Nasopharyngeal carriage of S. pneumoniae is common in a UK setting in the pre-conjugate vaccine era. PCV would protect against a large proportion of carriage isolates. However, the impact of vaccination on non-vaccine serotypes will need to be monitored.

Squamous cell carcinoma and basal cell carcinoma arising in a naevus sebaceous of Jadassohn: case report and literature review

The development of a basal cell carcinoma within a naevus sebaceous of Jadassohn (NSJ) has commonly been reported. However, the development of a squamous cell carcinoma (SCC) is rare. There have been several reports of SCC arising within a NSJ but many contain little or ambiguous clinical information. A thorough review of the current English language literature has identified only three other well documented cases of SCC arising in a NSJ. Of these only one was a case of simultaneous occurrence of squamous and basal cell carcinoma. We report the second case of both malignancies arising within the same NSJ.

Recent advances in detrusor muscle function

Contractile activation of detrusor smooth muscle is initiated by the release of transmitters from motor nerves. Acetylcholine is a ubiquitous transmitter, as also is adenosine triphosphate (ATP) in many animal bladders and in people from several patient groups with pathological bladder function. In recent years there has been progress in explaining several cellular mechanisms that link transmitter release to contraction and these will be considered. The lifetime of ATP in the neuromuscular junction is finite and broken down ultimately to adenosine, which can exert modulatory control of contractile activation. Adenosine depresses nerve-mediated contractions and two sites of action have been proposed: an action on the motor nerves via A receptors to depress further transmitter release and a less well-defined depressant effect on the detrusor muscle. The Ca2+ ions that activate the contractile proteins are derived from intracellular stores, which releases their content via IP receptor activation and Ca2+-induced Ca2+ release. Filling of the stores in the rest interval is mediated via transmembrane flux of Ca2+through Ca2+ channels. Activation of the channels is regulated by the level of the intracellular [Ca2+], via activation and inactivation of Ca2+-sensitive K channels. Thus, Ca2+ store filling is regulated by intracellular [Ca2+] via a negative feedback process. The presence and physiological function of spontaneous contractions in detrusor remain contentious and little is known about their origin. One possibility is that they originate from random Ca2+ sparks, i.e. localized transient increases of [Ca2+] that may eventually progress to generate a cellular Ca2+ transient. Observations by confocal microscopy have revealed the presence of such sparks, especially near the cell membrane, and thus provide a cellular basis for spontaneous contractions. Finally, the questions arises as to whether detrusor smooth muscle is a functional syncitium. The demonstration of small gap junctions by electron microscopy and the demonstration of the gap junction protein connexin45 indicate that the muscle mass may indeed be functionally connected. The implications regarding the spread of excitation are discussed.

Serotonin syndrome:case report and current concepts

Selective serotonin reuptake inhibitors (SSRI's) are increasingly being used as the first line therapeutic agent for the depression. It is therefore not unusual to see a case of overdose with these agents. More commonly an adverse drug reaction may be seen among the older patients who are particularly vulnerable to the serotonin syndrome due to multiple co-morbidity and polypharmacy. The clinical picture of serotonin syndrome (SS) is non-specific and there is no confirmatory test. SS may go unrecognized because it is often mistaken for a viral illness, anxiety, neurological disorder or worsening psychiatric condition.

Clinical outcome and virological characteristics of hepatitis B-related acute liver failure in the United States

The role of hepatitis B virus (HBV) genotypes in the outcome of acute HBV infection is unclear. In this study, we aimed to evaluate the clinical and virological features of patients with hepatitis B-related acute liver failure (HBV-ALF) in the US. Clinical and laboratory features of consecutive patients with HBV-ALF from the US ALF Study Group were analysed. Prevalence of HBV genotypes, precore stop (G1896A) and core promoter dual (T1762A, A1764T) variants among patients with HBV-ALF were compared with a cohort of 530 patients with chronic HBV infection. Thirty-four HBV-ALF patients were studied: mean age 41 years, 56% men, 25 had detectable HBV-DNA. HBV genotypes A, B, C and D were found in 36, 24, 8 and 32% patients, respectively. Precore stop and core promoter dual variants were detected in 32 and 44% of patients, respectively. Twenty-three (68%) patients survived: 14 after liver transplant, nine without transplant. Older age was the only independent factor associated with poor outcome. Compared with patients with chronic HBV infection, patients with ALF were more likely to be non-Asians (88% vs 44%, P = 0.005) and to have genotype D (32% vs 10%, P < 0.01). A higher prevalence of HBV genotype D persisted even after matching for race and HBeAg status (32% vs 16%, P = 0.007). We concluded that HBV genotype D was more frequently found in patients with HBV-ALF than those with chronic HBV infection in the US. Further studies are needed to determine if HBV genotypes play a role in the outcome of acute HBV infection.