Efficacy of paroxetine in the treatment of adolescent major depression: a randomized, controlled trial

OBJECTIVE

To compare paroxetine with placebo and imipramine with placebo for the treatment of adolescent depression.

METHOD

After a 7- to 14-day screening period, 275 adolescents with major depression began 8 weeks of double-blind paroxetine (20-40 mg), imipramine (gradual upward titration to 200-300 mg), or placebo. The two primary outcome measures were endpoint response (Hamilton Rating Scale for Depression [HAM-D] score < or = 8 or > or = 50% reduction in baseline HAM-D) and change from baseline HAM-D score. Other depression-related variables were (1) HAM-D depressed mood item; (2) depression item of the Schedule for Affective Disorders and Schizophrenia for Adolescents-Lifetime version (K-SADS-L); (3) Clinical Global Impression (CGI) improvement scores of 1 or 2; (4) nine-item depression subscale of K-SADS-L; and (5) mean CGI improvement scores.

RESULTS

Paroxetine demonstrated significantly greater improvement compared with placebo in HAM-D total score < or = 8, HAM-D depressed mood item, K-SADS-L depressed mood item, and CGI score of 1 or 2. The response to imipramine was not significantly different from placebo for any measure. Neither paroxetine nor imipramine differed significantly from placebo on parent- or self-rating measures. Withdrawal rates for adverse effects were 9.7% and 6.9% for paroxetine and placebo, respectively. Of 31.5% of subjects stopping imipramine therapy because of adverse effects, nearly one third did so because of adverse cardiovascular effects.

CONCLUSIONS

Paroxetine is generally well tolerated and effective for major depression in adolescents.

Upregulated TRP and enhanced capacitative Ca(2+) entry in human pulmonary artery myocytes during proliferation

A rise in cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) due to Ca(2+) release from intracellular Ca(2+) stores and Ca(2+) influx through plasmalemmal Ca(2+) channels plays a critical role in mitogen-mediated cell growth. Depletion of intracellular Ca(2+) stores triggers capacitative Ca(2+) entry (CCE), a mechanism involved in maintaining Ca(2+) influx and refilling intracellular Ca(2+) stores. Transient receptor potential (TRP) genes have been demonstrated to encode the store-operated Ca(2+) channels that are activated by Ca(2+) store depletion. In this study, we examined whether CCE, activity of store-operated Ca(2+) channels, and human TRP1 (hTRP1) expression are essential in human pulmonary arterial smooth muscle cell (PASMC) proliferation. Chelation of extracellular Ca(2+) and depletion of intracellularly stored Ca(2+) inhibited PASMC growth in media containing serum and growth factors. Resting [Ca(2+)](cyt) as well as the increases in [Ca(2+)](cyt) due to Ca(2+) release and CCE were all significantly greater in proliferating PASMC than in growth-arrested cells. Consistently, whole cell inward currents activated by depletion of intracellular Ca(2+) stores and the mRNA level of hTRP1 were much greater in proliferating PASMC than in growth-arrested cells. These results suggest that elevated [Ca(2+)](cyt) and intracellularly stored [Ca(2+)] play an important role in pulmonary vascular smooth muscle cell growth. CCE, potentially via hTRP1-encoded Ca(2+)-permeable channels, may be an important mechanism required to maintain the elevated [Ca(2+)](cyt) and stored [Ca(2+)] in human PASMC during proliferation.

Improved low energy defibrillation efficacy in man with the use of a biphasic truncated exponential waveform

The standard implantable defibrillator waveform is a truncated exponential of approximately 6 msec duration. This study compares the defibrillation efficacy of a standard monophasic truncated exponential to a biphasic 12 msec truncated exponential waveform in 21 patients undergoing automatic implantable cardioverter defibrillator (AICD) surgery. For the biphasic waveform, the polarity was reversed and remaining capacitor voltage was attenuated by 75% after 6 msec. Two hundred thirty episodes of VF were induced with 115 "matched pairs" of monophasic and biphasic waveforms of identical initial capacitor voltages given over a range from 70 to 600 V (0.35 to 25.7 joules). The biphasic waveform was superior to the monophasic waveform (p less than 0.006), especially for "low energy" defibrillation. For initial voltages less than 200 V, the percent successful defibrillation was 28% for the monophasic waveform versus 64% for the biphasic waveform and from 200 to 290 V (energies less than 6.4 joules) it was 45% versus 69%. There was no difference in the two waveforms in time to the first QRS complex or in the blood pressure following defibrillation. This study shows that a 12 msec biphasic truncated exponential is superior to a 6 msec monophasic waveform for defibrillation in man, especially at energies less than 6.4 joules. The waveform can be achieved in an implanted device without any increase in capacitor size or in battery energy consumption.

Enhanced tumor growth of both primary and established human and murine tumor cells in athymic mice after coinjection with Matrigel

Previously we found that the reconstituted basement membrane matrix Matrigel, when premixed with human small-cell lung carcinoma cells and injected subcutaneously into athymic mice, permitted tumor growth, whereas cells injected in the absence of Matrigel did not form tumors. In the present study, we examined additional cell types and determined some of the underlying mechanisms involved in the promotion of tumor formation by Matrigel. The tumor cell lines that we studied included transformed mouse Englebreth-Holm-Swarm tumor cells (T-EHS), human submandibular carcinoma A253 cells, mouse melanoma B16F10 cells, human epidermoid carcinoma KB cells, and human primary renal cell carcinoma cells. When coinjected subcutaneously with Matrigel, these cell lines formed rapidly proliferating tumors. Primary biopsy specimens of human colon carcinoma, when dispersed and coinjected with Matrigel, also formed tumors. Only A253, KB, and B16F10 cells formed small tumors in the absence of Martrigel, but a fivefold to tenfold increase in tumor size was observed in the presence of Matrigel. These data demonstrate a useful method for improving the growth of human tumors in athymic mice.

Efficacy and safety of sildenafil citrate in the treatment of erectile dysfunction in patients with ischemic heart disease

Erectile dysfunction is a common condition in men with cardiovascular disease, probably as a result of shared factors that impair hemodynamic mechanisms in the penile and ischemic vasculature. Sildenafil citrate, an orally active, selective inhibitor of phosphodiesterase type 5 (PDE5), has demonstrated excellent efficacy and safety profiles in men with erectile dysfunction of various etiologies. Sildenafil administration is contraindicated in patients who are taking nitrates or nitric oxide donors. This retrospective subanalysis of data from double-blind, placebo-controlled studies assessed the efficacy (9 studies) and safety (11 studies) of sildenafil in patients with erectile dysfunction and ischemic heart disease who were not taking nitrates. Of 3,672 patients randomized to receive sildenafil (5-200 mg) or placebo for 4-24 weeks in 11 double-blind, placebo-controlled studies, 357 (10%) reported a history (past or present) of ischemic heart disease and were not taking nitrates. Efficacy was assessed using end-of-treatment responses to Question 3 (ability to achieve an erection) and Question 4 (ability to maintain an erection) of the International Index of Erectile Function (IIEF), scores for the 5 domains of male sexual function assessed by the IIEF (erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction), and responses to a global efficacy question ("Did the treatment improve your erections?"). The responses to the 2 IIEF questions were graded on a scale of 1 (almost never or never) to 5 (almost always or always), with a score of 0 indicating no attempt at sexual intercourse. At the end of treatment, the mean scores for Question 3 and Question 4 of the IIEF for patients with erectile dysfunction and ischemic heart disease were significantly higher for the sildenafil group than for the placebo group (p <0.0001). Mean end-of-treatment scores for the IIEF domains also demonstrated significant increases for sildenafil-treated patients compared with those receiving placebo (p <0.05). At the end of treatment, improved erections were reported by 70% of patients who received sildenafil and by 20% of those in the placebo group p <0.0001). For the sildenafil group, the incidences of the most common adverse events (headache 25%, flushing 14%, and dyspepsia 12%) for patients with ischemic heart disease were similar to those in patients without this concomitant illness (21%, 15%, and 10%, respectively). Moreover, the overall incidence of cardiovascular adverse events other than flushing was comparable in patients with and without ischemic heart disease for both treatment groups. Since there is a degree of cardiac risk associated with sexual activity, clinicians should consider the patient's cardiovascular status before initiating any treatment for erectile dysfunction. Physicians should be aware that patients with underlying cardiovascular disease could be adversely affected by the vasodilator effects of sildenafil, especially in combination with sexual activity. The results of the present subanalysis indicate that oral sildenafil significantly improves erectile function and is well tolerated in patients with erectile dysfunction and ischemic heart disease who are not taking nitrate therapy.

Sildenafil citrate for the treatment of erectile dysfunction in men with Type II diabetes mellitus

AIMS/HYPOTHESIS

Ninety percent of all men with diabetes have Type II (non-insulin-dependent) diabetes mellitus, and erectile dysfunction (ED) is common in this patient group. This study evaluated the effects of sildenafil on men with erectile dysfunction and Type II diabetes and compared the results with glycated haemoglobin concentrations and chronic diabetic complications.

METHODS

Patients (mean age, 59 years) in this double-blind, placebo-controlled trial were randomised to sildenafil (25-100 mg; n = 110) or matching placebo (n = 109) for 12 weeks. Primary criteria for efficacy included questions 3 (achieving an erection) and 4 (maintaining an erection) from the International Index of Erectile Function (IIEF, score range, 0-5). Secondary outcome measures included a global efficacy question (GEQ), patient event logs, a life satisfaction checklist, and the remaining IIEF questions.

RESULTS

After 12 weeks, the mean scores for questions 3 and 4 had improved significantly in patients receiving sildenafil (3.42 +/- 0.23 and 3.35 +/- 0.24) compared with placebo (1.86 +/- 0.22 and 1.84 +/- 0.23; p < 0.0001). Similarly, the GEQ score was higher in the sildenafil (64.6 %) than the placebo group (10.5 %). Even when correlating efficacy with glycated haemoglobin concentrations ( < or = 8.3 % or > 8.3 %, the median concentration found in this study) or the number of diabetic complications (0 or > or = 1), the mean scores for the GEQ and questions 3 and 4 from the IIEF remained higher for all the sildenafil groups compared with the placebo groups (p < 0.0001).

CONCLUSION/INTERPRETATION

Sildenafil was well-tolerated and effective in improving erectile dysfunction in men with Type II diabetes, even in patients with poor glycaemic control and chronic complications.

Capacitative Ca(2+) entry in agonist-induced pulmonary vasoconstriction

Agonist-induced increases in cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) in pulmonary artery (PA) smooth muscle cells (SMCs) consist of a transient Ca(2+) release from intracellular stores followed by a sustained Ca(2+) influx. Depletion of intracellular Ca(2+) stores triggers capacitative Ca(2+) entry (CCE), which contributes to the sustained increase in [Ca(2+)](cyt) and the refilling of Ca(2+) into the stores. In isolated PAs superfused with Ca(2+)-free solution, phenylephrine induced a transient contraction, apparently by a rise in [Ca(2+)](cyt) due to Ca(2+) release from the intracellular stores. The transient contraction lasted for 3-4 min until the Ca(2+) store was depleted. Restoration of extracellular Ca(2+) in the presence of phentolamine produced a contraction potentially due to a rise in [Ca(2+)](cyt) via CCE. The store-operated Ca(2+) channel blocker Ni(2+) reduced the store depletion-activated Ca(2+) currents, decreased CCE, and inhibited the CCE-mediated contraction. In single PASMCs, we identified, using RT-PCR, five transient receptor potential gene transcripts. These results suggest that CCE, potentially through transient receptor potential-encoded Ca(2+) channels, plays an important role in agonist-mediated PA contraction.

Activation of K+ channels induces apoptosis in vascular smooth muscle cells

Intracellular K+ plays an important role in controlling the cytoplasmic ion homeostasis for maintaining cell volume and inhibiting apoptotic enzymes in the cytosol and nucleus. Cytoplasmic K+ concentration is mainly regulated by K+ uptake via Na+-K+-ATPase and K+ efflux through K+ channels in the plasma membrane. Carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), a protonophore that dissipates the H+ gradient across the inner membrane of mitochondria, induces apoptosis in many cell types. In rat and human pulmonary artery smooth muscle cells (PASMC), FCCP opened the large-conductance, voltage- and Ca2+-sensitive KK+ (maxi-K) channels, increased K+ currents through maxi-K channels [I(K(Ca))], and induced apoptosis. Tetraethylammonia (1 mM) and iberiotoxin (100 nM) decreased I(K(Ca)) by blocking the sarcolemmal maxi-K channels and inhibited the FCCP-induced apoptosis in PASMC cultured in media containing serum and growth factors. Furthermore, inhibition of K+ efflux by raising extracellular K+ concentration from 5 to 40 mM also attenuated PASMC apoptosis induced by FCCP and the K+ ionophore valinomycin. These results suggest that FCCP-mediated apoptosis in PASMC is partially due to an increase of maxi-K channel activity. The resultant K+ loss through opened maxi-K channels may serve as a trigger for cell shrinkage and caspase activation, which are major characteristics of apoptosis in pulmonary vascular smooth muscle cells.

Evaluation of standard and active compression-decompression CPR in an acute human model of ventricular fibrillation

BACKGROUND

The mechanisms that underlie cardiopulmonary resuscitation (CPR) in humans remain controversial and difficult to study. This report describes a new human model to evaluate CPR during the first 1 to 2 minutes after the onset of ventricular fibrillation (VF). With this model, standard CPR was compared with active compression-decompression (ACD) CPR, a method that uses a handheld suction device to actively compress and actively decompress the chest.

METHODS AND RESULTS

During routine inductions of VF as part of a transvenous lead cardioverter/defibrillator implantation procedure, CPR was performed in 21 patients if the first defibrillation shock failed and until a successful rescue shock was delivered. Compressions during CPR were performed according to American Heart Association guidelines. For ACD CPR, decompression was performed with up to -30 lbs. Radial arterial and right atrial pressures were measured in all patients. Esophageal pressures, intratracheal pressures, or minute ventilation was measured in the last 13 patients. Application of both CPR techniques increased arterial and right atrial pressures. The mean coronary perfusion pressure was increased throughout the entire CPR cycle with ACD CPR (compression, 21.5 +/- 9.0 mm Hg; decompression, 21.9 +/- 8.7 mm Hg) compared with standard CPR (compression, 17.9 +/- 8.2 mm Hg; decompression, 18.5 +/- 6.9 mm Hg; P < .02 and P < .02, respectively). Ventilation per compression-decompression cycle was 97.3 +/- 65.6 mL with standard CPR and 168.4 +/- 68.6 mL with ACD CPR (n = 7, P < .001). Negative inspiratory pressure was -0.8 +/- 4.8 mm Hg with standard CPR and -11.4 +/- 6.3 mm Hg with ACD CPR (n = 6, P < .04).

CONCLUSIONS

Patients undergoing multiple inductions of VF during cardioverter/defibrillator implantation with transvenous leads provide a well-controlled and reproducible model to study the mechanisms of CPR. Using this model, ACD CPR significantly increased arterial blood pressure, coronary perfusion pressure, minute ventilation, and negative inspiratory pressure compared with standard CPR.

The mode selection trial (MOST) in sinus node dysfunction: design, rationale, and baseline characteristics of the first 1000 patients

BACKGROUND

More than 200,000 permanent pacemakers will be implanted in the United States in 2000 at a cost of more than $2 billion. Sick sinus syndrome (SSS) will likely account for approximately half of all cases necessitating implantation. Pacemaker technology permits the selection of ventricular (single-chamber) or dual-chamber devices. However, clinical and outcomes data are inadequate to support a clear recommendation that one or the other type of device be used.

METHODS

The Mode Selection Trial (MOST) is a single-blind study supported by the National Heart, Lung, and Blood Institute designed to enroll 2000 patients with SSS. All patients will receive a DDDR pacemaker programmed to VVIR or DDDR before implantation. The average time of follow-up will be 3 years. MOST has a >90% power to detect a 25% reduction in the primary end point-nonfatal stroke or total (all cause) mortality-in the DDDR-treated group. Secondary end points will include health-related quality of life and cost effectiveness, atrial fibrillation, and development of pacemaker syndrome. Prespecified subgroups for analysis will include women and the elderly. Enrollment was completed in October 1999, with a total of 2010 patients.

RESULTS

The median age of the first 1000 enrolled patients is 74 years, with 25% of patients 80 years or older. Women comprise 49%, and 17% are nonwhite, predominantly black (13%). Before pacemaker implantation, 22% of patients reported a history of congestive heart failure, 11% coronary angioplasty, and 25% coronary bypass surgery. Supraventricular tachycardia including atrial fibrillation was present in 53% of patients. A prior stroke was reported by 12%. Antiarrhythmic therapy was in use in 18% of patients.

CONCLUSIONS

MOST will fill the clinical need for carefully designed prospective studies to define the benefits of dual-chamber versus single-chamber ventricular pacing in patients with SSS. The MOST population is typical of the overall pacemaker population in the United States. Thus the final results of MOST should be clinically generalizable.

Clinical pharmacokinetics of doxazosin in a controlled-release gastrointestinal therapeutic system (GITS) formulation

AIMS

A controlled-release gastrointestinal therapeutic system (GITS) formulation of doxazosin mesylate, a long-acting selective alpha1-adrenoceptor antagonist, was developed to enhance the pharmacokinetic profile and simplify the titration schedule by precisely controlling drug delivery rate, permitting an initial dose of 4 mg once daily, compared with standard doxazosin, which is initiated at 1 mg day-1 and titrated to a higher therapeutically effective dose. The aim of the present work was to evaluate the pharmacokinetics and bioavailability of doxazosin GITS with respect to the effect of food, age and gender, and multiple dosing. In addition, in vitro performance was assessed in conditions simulating the gastrointestinal environment.

METHODS

A three-way crossover study in 24 subjects assessed the comparative bioavailability of doxazosin GITS under fed and fasting conditions and doxazosin standard under fasting condition. A multiple-dose, two-way crossover study in 35 subjects assessed the comparative pharmacokinetics and bioavailability of doxazosin GITS and doxazosin standard 4 and 8 mg upon multiple dosing. A multiple-dose, four-parallel-group study was conducted to determine the steady-state pharmacokinetics and bioavailability of doxazosin GITS 4 mg in 41 young and elderly male and female subjects. The release-rate profiles of doxazosin GITS were determined in artificial gastric fluid (pH=1.2), intestinal fluid (pH=7.5), and water. The effect of agitation on the dissolution characteristics of doxazosin GITS in artificial gastric fluid was studied at stirring rates of 50, 75, and 100 rev min-1.

RESULTS

In vitro studies demonstrated that release rates for the GITS tablet are independent of pH in the range of 1.2 (gastric) to 7. 5 (intestinal), and of stirring rates simulating gastrointestinal motility. Clinical pharmacology studies showed that doxazosin GITS had a lower maximum plasma concentration, prolonged time to reach maximum plasma concentration, and a higher minimum plasma concentration compared with doxazosin standard. Thus, the GITS formulation results in a more gradual absorption of doxazosin, and a reduced plasma doxazosin concentration peak-to-trough fluctuation ratio. The relative bioavailability of doxazosin GITS is approximately 60%. With a high-fat meal, the maximum plasma concentration and area under the concentration-time curve were 31% and 18% higher, respectively (P<0.05). Bioequivalence was established between the dose strengths of two 4 mg doxazosin GITS tablets and one 8 mg doxazosin GITS tablet. For both young adult and elderly subjects, and males and females, the pharmacokinetics of doxazosin GITS once daily for 7 days were comparable. Doxazosin GITS was well tolerated in the subjects studied, including young and elderly males and females.

CONCLUSIONS

The GITS formulation of doxazosin enhances the pharmacokinetic profile compared with doxazosin standard, allowing more gradual absorption of doxazosin, and a reduced plasma doxazosin peak-to-trough concentration ratio. Thus, doxazosin GITS therapy can be initiated at a therapeutic dose of 4 mg with reduced haemodynamic side-effects.

Neocentromere-mediated chromosome movement in maize

Neocentromere activity is a classic example of nonkinetochore chromosome movement. In maize, neocentromeres are induced by a gene or genes on Abnormal chromosome 10 (Ab10) which causes heterochromatic knobs to move poleward at meiotic anaphase. Here we describe experiments that test how neocentromere activity affects the function of linked centromere/kinetochores (kinetochores) and whether neocentromeres and kinetochores are mobilized on the spindle by the same mechanism. Using a newly developed system for observing meiotic chromosome congression and segregation in living maize cells, we show that neocentromeres are active from prometaphase through anaphase. During mid-anaphase, normal chromosomes move on the spindle at an average rate of 0.79 micron/min. The presence of Ab10 does not affect the rate of normal chromosome movement but propels neocentromeres poleward at rates as high as 1.4 micron/min. Kinetochore-mediated chromosome movement is only marginally affected by the activity of a linked neocentromere. Combined in situ hybridization/immunocytochemistry is used to demonstrate that unlike kinetochores, neocentromeres associate laterally with microtubules and that neocentromere movement is correlated with knob size. These data suggest that microtubule depolymerization is not required for neocentromere motility. We argue that neocentromeres are mobilized on microtubules by the activity of minus end-directed motor proteins that interact either directly or indirectly with knob DNA sequences.

Hypoxic pulmonary vasoconstriction: role of voltage-gated potassium channels

Activity of voltage-gated potassium (Kv) channels controls membrane potential, which subsequently regulates cytoplasmic free calcium concentration ([Ca2+]cyt) in pulmonary artery smooth muscle cells (PASMCs). Acute hypoxia inhibits Kv channel function in PASMCs, inducing membrane depolarization and a rise in [Ca2+ ]cyt that triggers vasoconstriction. Prolonged hypoxia inhibits expression of Kv channels and reduces Kv channel currents in PASMCs. The consequent membrane depolarization raises [Ca2+]cyt, thus stimulating PASMC proliferation. The present review discusses recent evidence for the involvement of Kv channels in initiation of hypoxic pulmonary vasoconstriction and in chronic hypoxia-induced pulmonary hypertension.

Mitochondrial DNA analysis in Parkinson's disease

The reduced form of nicotinamide adenine dinucleotide coenzyme Q reductase (complex I) activity has recently been shown to be deficient in the substantia nigra of patients dying with Parkinson's disease. This biochemical defect is identical to that produced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which also produces parkinsonism in humans. Complex I comprises 25 polypeptides, seven of which are encoded by mitochondrial DNA. Restriction fragment analysis of substantia nigra DNA from six patients with Parkinson's disease did not show any major deletion. In two cases, there were different novel polymorphisms that were not observed in control brain (n = 6) or blood (n = 34) samples.

A double blind, randomised study of sildenafil citrate for erectile dysfunction in men with multiple sclerosis

OBJECTIVE

Identifying and effectively treating erectile dysfunction (ED) can result in an improvement of the quality of life (QoL) in men with multiple sclerosis (MS).

METHODS

This randomised, double blind (DB), placebo controlled, flexible dose study with an open label extension (OLE) assessed efficacy, QoL, and safety of sildenafil citrate in men with MS and ED. Overall, 217 men received sildenafil (25-100 mg; n = 104) or placebo (n = 113) for 12 weeks. Efficacy was assessed by the International Index of Erectile Function (IIEF) questionnaire that includes questions on achieving (Q3) and maintaining (Q4) an erection as well as a global efficacy question (GEQ). QoL was also assessed.

RESULTS

After 12 weeks, patients receiving sildenafil had higher mean scores for IIEF Q3 and Q4 compared with those receiving placebo (p<0.0001), and 89% (92/103) reported improved erections compared with 24% (27/112) of patients receiving placebo (p<0.0001). At the end of the OLE phase, 95% of men reported improved erections. Patients receiving placebo during the DB phase showed a nearly fourfold increase in improved erections (97% v 26%). Men receiving sildenafil also showed improvements in five of the eight general QoL questions compared with men receiving placebo (p<0.05). The total mean score for the QoL questionnaire improved by 43% for the sildenafil group versus 13% for the placebo group (p<0.0001). Treatment related AEs were predominantly mild in nature, and no patient discontinued due to an AE.

CONCLUSION

Sildenafil treatment for ED in men with MS was effective and well tolerated, and resulted in significant improvements in both general and disease specific QoL variables.

Modulation of osteogenic cell ultrastructure by RS-23581, an analog of human parathyroid hormone (PTH)-related peptide-(1-34), and bovine PTH-(1-34)

RS-23581, a synthetic analog of human PTH-related protein-(1-34), and the amino-terminal 34 amino acids of bovine PTH [bPTH-(1-34)] increase bone mineral density. We wished to determine how quickly the ultrastructure of the osteogenic cells, i.e. osteoblasts and lining cells, of the cancellous bone of the second lumbar vertebra of ovariectomized rats was altered in response to the initiation and cessation of treatment. Ovariectomized rats were injected daily with 80 micrograms/kg RS-23581, bPTH-(1-34), or vehicle for 19 days. Animals were killed throughout the treatment period and during the ensuing 10 days. By 5 days after the initiation of treatment with either peptide, the cells on the trabecular surface were predominantly (> 90%) osteoblasts, with only a small increase in the total cell number. Throughout the dosing period, the relative area of the cytoplasm of osteogenic cells from rats treated with RS-23581 or bPTH-(1-34) was greater than that of cells from the ovariectomized control group, suggesting a relationship between bone formation and cytoplasmic mass. By 7 days after the cessation of treatment, the trabecular surface was covered predominantly by lining cells without a change in cell number. Thus, these peptides apparently promote the osteoblast phenotype; the osteoblasts revert to lining cells after the peptides are withdrawn.

Minimal time to successful intercourse after sildenafil citrate: results of a randomized, double-blind, placebo-controlled trial

OBJECTIVES

To determine the minimal time to successful intercourse after taking sildenafil citrate for erectile dysfunction (ED).

METHODS

Male patients with ED (mean age 60 years; mean ED duration 7.0 years) who were successfully treated with sildenafil (100 mg) for 2 months or longer were randomized to sildenafil (n = 115) or placebo (n = 113) for 4 weeks of double-blind treatment. Using a stopwatch, patients recorded the time needed to obtain an erection hard enough for sexual intercourse after taking the study drug at least 2 hours after eating.

RESULTS

Within 14 and 20 minutes of sildenafil dosing, 35% and 51% of sildenafil-treated patients, respectively, versus 22% and 30% of placebo-treated patients, respectively, had an erection that led to successful intercourse (P <0.05 for both). The median time to erection leading to successful intercourse after sildenafil dosing was 36 minutes compared with 141 minutes for placebo.

CONCLUSIONS

In this study, slightly more than one half of a population of prior sildenafil responders achieved an erection that led to successful sexual intercourse within 20 minutes of sildenafil administration, suggesting that the onset of action of sildenafil can be less than 30 minutes in men with ED.

Chronic hypercapnia inhibits hypoxic pulmonary vascular remodeling

Chronic hypercapnia is commonly found in patients with severe hypoxic lung disease and is associated with a greater elevation of pulmonary arterial pressure than that due to hypoxia alone. We hypothesized that hypercapnia worsens hypoxic pulmonary hypertension by augmenting pulmonary vascular remodeling and hypoxic pulmonary vasoconstriction (HPV). Rats were exposed to chronic hypoxia [inspiratory O(2) fraction (FI(O(2))) = 0.10], chronic hypercapnia (inspiratory CO(2) fraction = 0.10), hypoxia-hypercapnia (FI(O(2)) = 0.10, inspiratory CO(2) fraction = 0.10), or room air. After 1 and 3 wk of exposure, muscularization of resistance blood vessels and hypoxia-induced hematocrit elevation were significantly inhibited in hypoxia-hypercapnia compared with hypoxia alone (P < 0.001, ANOVA). Right ventricular hypertrophy was reduced in hypoxia-hypercapnia compared with hypoxia at 3 wk (P < 0.001, ANOVA). In isolated, ventilated, blood-perfused lungs, basal pulmonary arterial pressure after 1 wk of exposure to hypoxia (20.1 +/- 1.8 mmHg) was significantly (P < 0.01, ANOVA) elevated compared with control conditions (12.1 +/- 0.1 mmHg) but was not altered in hypoxia-hypercapnia (13.5 +/- 0.9 mmHg) or hypercapnia (11.8 +/- 1.3 mmHg). HPV (FI(O(2)) = 0.03) was attenuated in hypoxia, hypoxia-hypercapnia, and hypercapnia compared with control (P < 0.05, ANOVA). Addition of N(omega)-nitro-L-arginine methyl ester (10(-4) M), which augmented HPV in control, hypoxia, and hypercapnia, significantly reduced HPV in hypoxia-hypercapnia. Chronic hypoxia caused impaired endothelium-dependent relaxation in isolated pulmonary arteries, but coexistent hypercapnia partially protected against this effect. These findings suggest that coexistent hypercapnia inhibits hypoxia-induced pulmonary vascular remodeling and right ventricular hypertrophy, reduces HPV, and protects against hypoxia-induced impairment of endothelial function.

In vivo skeletal muscle mitochondrial function in Leber's hereditary optic neuropathy assessed by 31P magnetic resonance spectroscopy

We used 31P magnetic resonance spectroscopy (31P-MRS) to assess in vivo skeletal muscle mitochondrial function in 10 Leber's hereditary optic neuropathy patients/carriers with a mitochondrial DNA (mtDNA) mutation at one of three nucleotide positions, 11,778, 14,484, and 3,460. We studied one affected patient for each mutation and two unaffected carriers with the 11,778 or 3,460 mutation and three carriers with 14,484. All subjects were homoplasmic except the two 3,460 carriers, who showed 80% and 15% of mutated mtDNA. 31P-MRS at rest disclosed some abnormalities in all subjects. In particular, the phosphorylation potential was below the normal range in all cases. During recovery from exercise, the maximum rate of mitochondrial ATP production (Vmax) was reduced to 27% of normal in the 11,778 mutation and to 53% in the 14,484 mutation patient/carrier groups. Mitochondrial Vmax was within the normal range in all subjects with the 3,460 mutation but correlated inversely with the percentage of mutated mtDNA. This in vivo study shows that the 11,778 mutation causes a mitochondrial impairment more severe than the 14,484 and that the 3,460 mutation results in only a mild depression of muscle mitochondrial function.

Differences in Chlorophyll Loss at 13 degrees C for Two Broccoli (Brassica oleracea L.) Cultivars Associated with Antioxidant Enzyme Activities

Two broccoli cultivars which have been previously found to have large differences in yellowing susceptibility were studied to determine if there was a relationship between antioxidant capability and chlorophyll loss at a simulated retail display temperature. Greenbelt cultivar retained a stable chlorophyll content over 4 days at 13 degrees C, while Emperor cultivar showed a constant decline in chlorophyll content. These differences were not related to differences in water loss. Superoxide dismutase (SOD) and peroxidase (POD) activities were approximately 30% higher in Greenbelt than in Emperor. The ratio of superoxide dismutase to peroxidase activity was also lower in Greenbelt. The susceptibility of Emperor to oxygen radical damage and lipid peroxidation is expected to be higher since an excessive SOD activity, with respect to POD activity, can potentially lead to enhanced hydroxyl radical formation. Catalase (CAT) activity was higher in Emperor, suggesting that catalase is not important in providing resistance to chlorophyll loss in broccoli. Water soluble, nonenzymatic antioxidant activity was similar for both cultivars. These results support the hypothesis that antioxidant protection offered by superoxide dismutase and peroxidase is important to retention of green color in broccoli.

Fluency versus conscious recollection in the word completion performance of amnesic patients

To examine the relative contribution of fluency and recollection to the word completion performance of amnesics, we administered a task in which patients were told specifically not to utilize previously presented words during stem completion (an Exclusion condition). This condition was contrasted with a standard word completion task in which patients were encouraged simply to complete the stem with the first word that came to mind (an Inclusion condition). Since the exclusion condition necessitated controlled respecification of the initial presentation, it was hypothesized that amnesics would be less able than controls to exclude study list items. Consistent with this hypothesis, the results indicated that the amnesics' performance, unlike that of the alcoholic controls, did not significantly differ as a function of task condition. To examine whether amnesics' conscious recollection could be enhanced, Experiment 2 presented the study list five times. The amnesics now were able to exclude a significant number of items from the study list; however, they still did so considerably less frequently than alcoholic controls. For the alcoholic controls, increasing the number of study trials had little additional effect on their exclusion performance, but it significantly enhanced their inclusion performance. Taken together, these findings suggest that for control subjects, word completion performance is likely mediated by a combination of fluency and recollection, while for amnesic patients, performance is almost exclusively based on the fluency with which an item comes to mind.

Familial dopa-responsive cervical dystonia

The authors present four cases from two unrelated families with young-onset predominant cervical dystonia with a dramatic sustained response to levodopa. Onset age was 12 years (range 9 to 15). Additional symptoms included postural hand tremor and laryngeal dystonia. Genetic testing for GTP cyclohydrolase I, tyrosine hydroxylase, and sepiapterin reductase was negative. These cases may represent new forms of dopa-responsive dystonia. Levodopa is advisable in all patients with young-onset cervical dystonia.

The management of paroxysmal tachycardias using the Cybertach-60

The Cybertach-60 is a bipolar multiprogrammable pacemaker designed for the automatic detection and termination of reentrant tachycardias using bursts of rapid pacing. From August 1979 to March 1984 in the U.S.A., 143 patients received the device; 91 for supraventricular and 52 for ventricular tachycardia. After a mean follow-up period of 1.8 years, 82% of patients with supraventricular tachycardia remain alive with the implanted pacemaker providing the principal therapy for the arrhythmia. Of those patients with ventricular tachycardia, 30 (58%) remain alive (mean follow-up 1.1 years) and use the device for tachycardia termination. In this group there were 18 patient deaths: 14 documented and not sudden; 4 sudden and not documented. None of the 14 documented deaths were a result of arrhythmia or pacemaker activity. The Cybertach-60 has proved to be effective in the long-term management of patients with reentrant rhythms, particularly supraventricular tachycardia.

Phenotypic homogeneity of the Huntington disease-like presentation in a SCA17 family

We describe clinical and genetic analysis of a family with spinocerebellar ataxia 17 (SCA17) presenting with a Huntington disease-like (HDL) syndrome. Clinically diagnosed, HD is genetically heterogeneous. Differential diagnosis includes SCA17. However, SCA17 HDL presentation has been observed only sporadically or in solitary individuals within a family. HDL phenotypic homogeneity in SCA17 has not been described. SCA17 can present with a HDL syndrome in multiple family members.