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I Goldstein

Publications and source records attributed to I Goldstein.

At least 73 records · Page 4Linked to original sources
PubMed2000

Report of the international consensus development conference on female sexual dysfunction: definitions and classifications.

PURPOSE: Female sexual dysfunction is highly prevalent but not well defined or understood. We evaluated and revised existing definitions and classifications of female sexual dysfunction. MATERIALS AND METHODS: An interdisciplinary consensus conference panel consisting of 19 experts in female sexual dysfunction selected from 5 countries was convened by the Sexual Function Health Council of the American Foundation for Urologic Disease. A modified Delphi method was used to develop consensus definitions and classifications, and build on the existing framework of the International Classification of Diseases-10 and DSM-IV: Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association, which were limited to consideration of psychiatric disorders. RESULTS: Classifications were expanded to include psychogenic and organic causes of desire, arousal, orgasm and sexual pain disorders. An essential element of the new diagnostic system is the "personal distress" criterion. In particular, new definitions of sexual arousal and hypoactive sexual desire disorders were developed, and a new category of noncoital sexual pain disorder was added. In addition, a new subtyping system for clinical diagnosis was devised. Guidelines for clinical end points and outcomes were proposed, and important research goals and priorities were identified. CONCLUSIONS: We recommend use of the new female sexual dysfunction diagnostic and classification system based on physiological as well as psychological pathophysiologies, and a personal distress criterion for most diagnostic categories.

Female↗
PubMed2000

Cyclic AMP regulates mRNA expression of alpha-1d and alpha-2a adrenergic receptors in cultured human corpus cavernosum smooth muscle cells.

While the physiological effects of contractile (e.g. norepinephrine) and relaxatory (e.g. PGE1, forskolin) agents on corpus cavernosum smooth muscle tone have been characterized, the regulation of alpha adrenergic receptor mRNA expression in erectile tissue remains to be investigated. The goal of this study was to investigate the modulation of alpha-1 and alpha-2 adrenergic receptor mRNA expression in cultured human corpus cavernosum smooth muscle cells in response to increased intracellular cAMP induced by prostaglandin E1 and forskolin. Human corpus cavernosum smooth muscle cells were incubated for 24 h with or without PGE1 (5.7 microM), forskolin (10 microM) or an admixture of both. Total RNA was prepared from the cultures. Expression of alpha-1d adrenergic receptor, alpha-2a adrenergic receptor and m2 muscarinic acetylcholine receptor was determined by RNase protection assays. Loading was normalized by RNase protection of the housekeeping gene, cyclophilin A. The relative abundance of mRNAs was quantitated by scanning densitometry. Treatment of human corpus cavernosum smooth muscle cells with PGE1 or forskolin resulted in decreased mRNA expression of alpha-1d and alpha-2a adrenergic receptors and m2 muscarinic acetylcholine receptor when compared to untreated cells. Combinations of PGE1 and forskolin produced a more pronounced decrease in mRNA than either agent alone. PGE1 and forskolin increased intracellular levels of cAMP in human corpus cavernosum smooth muscle cells and combinations of both agents produced a more pronounced increase in cAMP synthesis. These results suggest that cAMP modulates the expression of alpha adrenergic receptors, one of the principal contractile receptor systems in the corpora cavernosa. These observations further support the concept that erectile function is a balance between contractile and relaxatory processes, which in turn regulate structure and function of the corpora cavernosa.

Alprostadil↗
PubMed2000

Role of alpha adrenergic receptors in erectile function.

Penile erection is a complex physiological process in which the regulation of penile hemodynamics depends on signal input from central and peripheral nervous systems, and on the balance and interplay between several local physiological mediators (neurotransmitters, vasoactive agents and endocrine factors). A role for the sympathetic nervous system in attaining or maintaining penile flaccidity and detumescence is well recognized. However, the exact mechanisms of alpha-adrenergic receptor mediated erectile function remain poorly defined. The objective of this review is to summarize data presented in the literature and from our laboratory on alpha-adrenergic receptors, and to discuss the conceptual framework by which the alpha-adrenergic receptor pathway modulates penile corpus cavernosum smooth muscle contractility. We will integrate the current state of knowledge of penile erection into one framework encompassing the biochemical and physiological pathways responsible for trabecular smooth muscle relaxation (erection) and contraction (detumescence). We will focus our discussion on local control mechanisms of alpha-adrenergic receptors and explore the following topics: (1) functional activity of alpha-1 and alpha-2 adrenergic receptors in the physiology of human penile erection; (2) identification, classification and characterization of alpha-1 and alpha-2 adrenergic receptor subtypes in human penile erectile tissue; (3) molecular mechanism of action of alpha-1 and alpha-2 adrenergic receptors in human penile erectile tissue; (4) blockade of alpha-1 and alpha-2 adrenergic receptor action by selective and non-selective alpha-1 and alpha-2 adrenergic receptor antagonists (blockers); (5) physiologic (functional) antagonism of alpha-1 and alpha-2 adrenergic receptor activity by vasodilators mediating smooth muscle relaxation; and (6) key areas of consensus, as well as critical gaps in the existing scientific knowledge concerning the rationale and the potential use of alpha-blockers in erectile function.

Adrenergic alpha-Antagonists↗
PubMed2000

Oral phentolamine: an alpha-1, alpha-2 adrenergic antagonist for the treatment of erectile dysfunction.

Phentolamine mesylate is an alpha-1 and alpha-2 selective adrenergic receptor antagonist which has undergone clinical trials for erectile dysfunction treatment. Biochemical and physiological studies in human erectile tissue have revealed a high affinity of phentolamine for alpha-1 and alpha-2 adrenergic receptors. Based on pharmacokinetic studies, it is suggested that 30-40 min following oral ingestion of 40 or 80 mg of phentolamine (Vasomax), the mean plasma phentolamine concentrations are sufficient to occupy the alpha-1 and -2 adrenergic receptors in erectile tissue and thereby result in inhibition of adrenergic-mediated physiologic activity. In large multi-center, placebo-controlled pivotal phase III clinical trials, the mean change in the erectile function domain of the International Index of Erectile Function scores (Questions 1-5 and 15) from screening to the end of treatment was significantly higher following use of active drug (40 mg and 80 mg) compared to placebo. Three to four times as many patients receiving phentolamine reported being satisfied or very satisfied compared with those receiving placebo. At doses of 40 mg and 80 mg respectively, 55% and 59% of men were able to achieve vaginal penetration with 51% and 53% achieving penetration on 75% of attempts. The correction of erectile dysfunction or improvement to a less severe category of dysfunction was experienced by 53% of men with the 80 mg dose and 40% with the 40 mg dose of phentolamine. All trends of response were the same regardless of any concomitant medication. There were no severe adverse events. At 40 mg, 7.7% experienced rhinitis and fewer than 3.1% experienced any other side effect of treatment. Phentolamine is safe, well tolerated and efficacious for the treatment of erectile dysfunction.

Administration, Oral↗
PubMed2000

Comparison of oral and intracavernosal vasoactive agents in penile erection.

This discussion summarizes the potential differences in physiologically and pharmacologically induced erections and highlights the possible differences in the pathways facilitated by oral versus intracavernosal agents in penile erection. Oral agents act in conjunction with sexual stimulation either increasing corporal smooth muscle relaxation or attenuating smooth muscle contraction. However, their efficacy is dependent on sexual stimulation. Intracavernosal administration of phosphodiesterase type 5 inhibitor (sildenafil) or short-acting alpha adrenergic receptor antagonist (phentolamine), in the absence of sexual stimulation, does not initiate penile erection. In contrast, intracavernosal administration of PGE1 or papaverine induces erection independent of sexual stimulation. Thus, oral agents are not direct mediators of smooth muscle relaxation and act to facilitate relaxation in response to sexual stimulation, while intracavernosal agents directly mediate smooth muscle relaxation, independent of sexual stimulation. Although, considerable advances have been made in elucidating the physiology and pharmacology of erectile function, details of the signal transduction pathways affected by these agents in the penile corpus cavernosum are yet to be fully investigated.

Administration, Oral↗
PubMed2000

Cyclic AMP regulates mRNA expression of alpha-1d and alpha-2a adrenergic receptors in cultured human corpus cavernosum smooth muscle cells.

While the physiological effects of contractile (e.g. norepinephrine) and relaxatory (e.g. PGE1, forskolin) agents on corpus cavernosum smooth muscle tone have been characterized, the regulation of alpha adrenergic receptor mRNA expression in erectile tissue remains to be investigated. The goal of this study was to investigate the modulation of alpha-1 and alpha-2 adrenergic receptor mRNA expression in cultured human corpus cavernosum smooth muscle cells in response to increased intracellular cAMP induced by prostaglandin E1 and forskolin. Human corpus cavernosum smooth muscle cells were incubated for 24 h with or without PGE1 (5.7 µM), forskolin (10 µM) or an admixture of both. Total RNA was prepared from the cultures. Expression of alpha-1d adrenergic receptor, alpha-2a adrenergic receptor and m2 muscarinic acetylcholine receptor was determined by RNase protection assays. Loading was normalized by RNase protection of the housekeeping gene, cyclophilin A. The relative abundance of mRNAs was quantitated by scanning densitometry. Treatment of human corpus cavernosum smooth muscle cells with PGE1 or forskolin resulted in decreased mRNA expression of alpha-1d and alpha-2a adrenergic receptors and m2 muscarinic acetylcholine receptor when compared to untreated cells. Combinations of PGE1 and forskolin produced a more pronounced decrease in mRNA than either agent alone. PGE1 and forskolin increased intracellular levels of cAMP in human corpus cavernosum smooth muscle cells and combinations of both agents produced a more pronounced increase in cAMP synthesis. These results suggest that cAMP modulates the expression of alpha adrenergic receptors, one of the principal contractile receptor systems in the corpora cavernosa. These observations further support the concept that erectile function is a balance between contractile and relaxatory processes, which in turn regulate structure and function of the corpora cavernosa. International Journal of Impotence Research (2000) 12, Suppl 1, S41-S47

Journal Article↗
PubMed2000

Role of alpha adrenergic receptors in erectile function.

Penile erection is a complex physiological process in which the regulation of penile hemodynamics depends on signal input from central and peripheral nervous systems, and on the balance and interplay between several local physiological mediators (neurotransmitters, vasoactive agents and endocrine factors). A role for the sympathetic nervous system in attaining or maintaining penile flaccidity and detumescence is well recognized. However, the exact mechanisms of alpha-adrenergic receptor mediated erectile function remain poorly defined. The objective of this review is to summarize data presented in the literature and from our laboratory on alpha-adrenergic receptors, and to discuss the conceptual framework by which the alpha-adrenergic receptor pathway modulates penile corpus cavernosum smooth muscle contractility. We will integrate the current state of knowledge of penile erection into one framework encompassing the biochemical and physiological pathways responsible for trabecular smooth muscle relaxation (erection) and contraction (detumescence). We will focus our discussion on local control mechanisms of alpha-adrenergic receptors and explore the following topics: (1) functional activity of alpha-1 and alpha-2 adrenergic receptors in the physiology of human penile erection; (2) identification, classification and characterization of alpha-1 and alpha-2 adrenergic receptor subtypes in human penile erectile tissue; (3) molecular mechanism of action of alpha-1 and alpha-2 adrenergic receptors in human penile erectile tissue; (4) blockade of alpha-1 and alpha-2 adrenergic receptor action by selective and non-selective alpha-1 and alpha-2 adrenergic receptor antagonists (blockers); (5) physiologic (functional) antagonism of alpha-1 and alpha-2 adrenergic receptor activity by vasodilators mediating smooth muscle relaxation; and (6) key areas of consensus, as well as critical gaps in the existing scientific knowledge concerning the rationale and the potential use of alpha-blockers in erectile function. International Journal of Impotence Research (2000) 12, Suppl 1, S48-63

Journal Article↗
PubMed2000

Oral phentolamine: an alpha-1, alpha-2 adrenergic antagonist for the treatment of erectile dysfunction.

Phentolamine mesylate is an alpha-1 and alpha-2 selective adrenergic receptor antagonist which has undergone clinical trials for erectile dysfunction treatment. Biochemical and physiological studies in human erectile tissue have revealed a high affinity of phentolamine for alpha-1 and alpha-2 adrenergic receptors. Based on pharmacokinetic studies, it is suggested that 30-40 min following oral ingestion of 40 or 80 mg of phentolamine (Vasomax), the mean plasma phentolamine concentrations are sufficient to occupy the alpha-1 and -2 adrenergic receptors in erectile tissue and thereby result in inhibition of adrenergic-mediated physiologic activity. In large multi-center, placebo-controlled pivotal phase III clinical trials, the mean change in the erectile function domain of the International Index of Erectile Function scores (Questions 1-5 and 15) from screening to the end of treatment was significantly higher following use of active drug (40 mg and 80 mg) compared to placebo. Three to four times as many patients receiving phentolamine reported being satisfied or very satisfied compared with those receiving placebo. At doses of 40 mg and 80 mg respectively, 55% and 59% of men were able to achieve vaginal penetration with 51% and 53% achieving penetration on 75% of attempts. The correction of erectile dysfunction or improvement to a less severe category of dysfunction was experienced by 53% of men with the 80 mg dose and 40% with the 40 mg dose of phentolamine. All trends of response were the same regardless of any concomitant medication. There were no severe adverse events. At 40 mg, 7.7% experienced rhinitis and fewer than 3.1% experienced any other side effect of treatment. Phentolamine is safe, well tolerated and efficacious for the treatment of erectile dysfunction. International Journal of Impotence Research (2000) 12, Suppl 1, S75-S80

Journal Article↗
PubMed2000

Comparison of oral and intracavernosal vasoactive agents in penile erection.

This discussion summarizes the potential differences in physiologically and pharmacologically induced erections and highlights the possible differences in the pathways facilitated by oral versus intracavernosal agents in penile erection. Oral agents act in conjunction with sexual stimulation either increasing corporal smooth muscle relaxation or attenuating smooth muscle contraction. However, their efficacy is dependent on sexual stimulation. Intracavernosal administration of phosphodiesterase type 5 inhibitor (sildenafil) or short-acting alpha adrenergic receptor antagonist (phentolamine), in the absence of sexual stimulation, does not initiate penile erection. In contrast, intracavernosal administration of PGE1 or papaverine induces erection independent of sexual stimulation. Thus, oral agents are not direct mediators of smooth muscle relaxation and act to facilitate relaxation in response to sexual stimulation, while intracavernosal agents directly mediate smooth muscle relaxation, independent of sexual stimulation. Although, considerable advances have been made in elucidating the physiology and pharmacology of erectile function, details of the signal transduction pathways affected by these agents in the penile corpus cavernosum are yet to be fully investigated. International Journal of Impotence Research (2000) 12, Suppl 1, S81-S88

Journal Article↗
PubMed1999

Development of human and rabbit vaginal smooth muscle cell cultures: effects of vasoactive agents on intracellular levels of cyclic nucleotides.

In this study, we subcultured and characterized human and rabbit vaginal smooth muscle cells and investigated the synthesis of second messenger cyclic nucleotides in response to vasodilators and determined the activity and kinetics of phosphodiesterase (PDE) type 5 (EC 3.1.4.35 3',5'-cyclic GMP phosphodiesterase). Cultured vaginal cells exhibited growth characteristics typical of smooth muscle cells and immunostained with antibodies against alpha smooth muscle actin. The cells retained functional prostaglandin E and beta-adrenergic receptors as demonstrated by increased intracellular cAMP synthesis in response to PGE1, or isoproterenol. The response to these vasoactive substances was augmented with forskolin, suggesting stabilization of G-protein-activated adenylyl cyclases. Treatment with the nitric oxide donor, sodium nitroprusside, in the presence of sildenafil, a PDE type 5 inhibitor, enhanced intracellular cGMP synthesis and accumulation. Incubation of rabbit vaginal tissue with sildenafil, sodium nitroprusside, and PGE1 or forskolin produced a marked increase in intracellular cGMP. These observations were similar to findings with cultured cells and suggest that subcultured cells retain functional characteristics exhibited in intact tissue. The cells retained phosphodiesterase type 5 expression as shown by specific cGMP hydrolytic activity. Sildenafil and zaprinast inhibited cGMP hydrolysis competitively and bound with high affinity (Ki = 7 and 250 nM, respectively). These observations suggest that cultured human and rabbit vaginal smooth muscle cells retained their metabolic functional integrity and this experimental system should prove useful in investigating the pathway of nitric oxide and PDE type 5 inhibitors in modulating vaginal smooth muscle tone.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Sildenafil Citrate, a Selective Phosphodiesterase Type 5 Inhibitor:

Under normal physiological conditions, following sexual stimulation, release of nitric oxide (NO) from penile non-adrenergic, non-cholinergic nerves and the endothelium activates guanylyl cyclase and induces intracellular cGMP synthesis in erectile tissue trabecular smooth muscle cells. Increased cGMP levels reduce intracellular Ca2+ concentrations, inhibiting smooth muscle contractility and thereby initiating the erectile response. Phosphodiesterase type 5 (PDE type 5) is the predominant enzyme responsible for cGMP hydrolysis in trabecular smooth muscle. Activation of PDE type 5 terminates NO-induced, cGMP-mediated smooth muscle relaxation, resulting ultimately in restoration of basal smooth muscle contractility and penile flaccidity. Sildenafil citrate is a potent PDE type 5 reversible and selective inhibitor that blocks cGMP hydrolysis effectively (Ki approximately 3 nM). Under conditions of excessive adrenergic tone or impaired neurovascular status, following sexual stimulation, sildenafil acts to enhance NO-mediated smooth muscle relaxation, resulting in improved penile erection in men with erectile dysfunction. In this review, we summarize the current state of knowledge of the physiology of penile erection and the pharmacology, metabolism and clinical experience with sildenafil citrate in the management of erectile dysfunction.

Journal Article↗
PubMed1999

Enhanced contractility of rabbit corpus cavernosum smooth muscle by oxidized low density lipoproteins.

We have investigated the effect of oxidatively-modified low density lipoproteins (ox-LDL) on the contractility of rabbit trabecular smooth muscle. Low density lipoproteins (LDL) were isolated from fresh human plasma pooled from multiple donors and oxidized by exposure to copper. Corpus cavernosum strips from New Zealand White rabbits were studied in organ chambers for isometric tension measurement. Corporeal strips in which moderate tone was induced by phenylephrine, contracted when exposed to ox-LDL, but not when exposed to either native LDL (nLDL) or LDL protected from oxidation by butylated hydroxytoleune (BHT-LDL). Removal of the endothelium, or treatment of the corporeal strips with N(omega)-nitro-L-arginine (nitric oxide synthase inhibitor), methylene blue of LY83583 (guanylate cyclase inhibitors/superoxide producing agents), did not prevent ox-LDL-induced contraction. ox-LDL, dose-dependently, enhanced the contractile response of corporeal strips to low and moderate concentrations by phenylephrine. nLDL had no significant effect on phenylephrine-induced contraction of corporeal strips. ox-LDL, nLDL or BHT-LDL had no effect on relaxation induced by the endothelium-dependent dilator, acetylcholine, or the nitric oxide donor, nitroprusside. In conclusion, this present study demonstrates significant pro-contractile effects of ox-LDL on corporeal smooth muscle, this effect is independent of the endothelium or the nitric oxide/cGMP pathway. The pro-contractile effect of ox-LDL may interfere with penile smooth muscle relaxation, necessary for the initiation and maintenance of penile erection.

Aminoquinolines↗
PubMed1999

Axial penile buckling forces vs Rigiscan radial rigidity as a function of intracavernosal pressure: why Rigiscan does not predict functional erections in individual patients.

AIM: An improved understanding of the relationship between radial and axial rigdity values would enable better appreciation of the clinical usefulness of RigiScantrade mark, the most widely utilized determination of erectile rigidity testing. Previous studies have shown that axial rigidity (measured by buckling forces) correlated well with radial rigidity (measured by RigiScantrade mark) for radial rigidity values below 60%. For radial rigidity exceeding 60%, there was poor correlation. Heretofore, there has been no physiologic explanation of this phenomenon. METHODS: During dynamic pharmacocavernosometry in 36 impotent patients, we investigated the relationship between axial buckling forces and RigiScan radial rigidity and, for the first time, how they both vary with pressure, (which we varied over over a wide functional range). In addition, we recorded multiple penile length and diameter values enabling us to relate, also for the first time, axial and radial rigidity to individual mechanical erectile tissue and penile geometric properties. RESULTS: Marked differences were found in the manner RigiScan radial rigidity units and axial buckling force magnitudes increased with increases in intracavernosal pressure values in each individual. The former asymptotically approached a maximum finite value while the latter increased continuously towards infinity. Based on data in this study, RigiScan radial rigidity values greater than 55% may be considered a necessary criteria for vaginal intromission capability in all partners but it is not a sufficient one. CONCLUSIONS: Axial and radial rigidity share a common dependency upon intracavernosal pressure, however, they are also dependent upon other unique physical determinants. For axial rigidity, additional dependent variables include cavernosal erectile tissue properties and penile geometry, while for radial rigidity, this may include tunical surface wall tension properties. Clinical devices which assess functional penile rigidity should utilize axial and not radial rigidity testing.

Equipment Design↗
PubMed1999

Clinical evaluation of female sexual function: effects of age and estrogen status on subjective and physiologic sexual responses.

INTRODUCTION: 30-50% of American women complain of sexual dysfunction. Aging, menopause, and a decline in circulating estrogen levels significantly increase the incidence of sexual complaints. Evaluation of physiologic components of the female sexual response has, in the past, been technically challenging and difficult to standardize. We describe methodology for evaluating physiologic and subjective components of the female sexual response in the clinical setting and determine the effects of age and estrogen status on them. METHODS: 48 women with complaints of sexual dysfunction were evaluated. Physiologic measurements include genital blood peak systolic velocity, vaginal pH, intravaginal pressure-volume changes (compliance), and genital vibratory perception thresholds. Measurements were recorded at baseline and following sexual stimulation. Baseline subjective sexual function was assessed using a Female Sexual Function Inventory. Age was then correlated with both physiologic and subjective sexual responses. RESULTS: Sexual stimulation resulted in increased mean genital blood peak systolic velocity, vaginal pressure-volume, and vaginal pH measurements (P < 0.05) in all women. Older women (ages 55-71 y) and menopausal women not on hormone replacement therapy had significantly lower physiologic response sexual complaints. Baseline subjective sexual function complaints included low arousal (67%), low desire (21%), difficulty achieving orgasm (92%), and pain or discomfort during and/or following intercourse (67%). CONCLUSIONS: Clinical evaluation of physiologic and subjective components of the female sexual response are possible using this comprehensive approach. Physiologic measurements were reproducible and easy to perform, and incidence and types of sexual complaints were assessed with the sexual function questionnaire. A comprehensive approach is necessary when evaluating female sexual dysfunction due to the significant emotional and relational factors that can contribute to the problem. This combined subjective/physiologic assessment may also prove useful when evaluating efficacy of pharmacotherapy in the future.

Adult↗
PubMed1999

Nomogram of the fetal alveolar ridge: a possible screening tool for the detection of primary cleft palate.

OBJECTIVE: The objective of this study was to obtain a nomogram of the fetal alveolar ridge development, as a basis for the diagnosis of primary cleft palate. DESIGN: A cross-sectional study of 323 normal pregnant women of 14-32 weeks' gestation. Several biometric measurements were obtained throughout pregnancy, including the width of the fetal alveolar ridge. RESULTS: A nomogram of the width of the fetal alveolar ridge during 14-32 weeks' gestation is presented. A linear growth function was observed between alveolar ridge width and gestational age, biparietal diameter, head circumference, femoral length and humeral length. The alveolar ridge width in all eight cases of cleft palate was above two standard deviations and the 90th centile of our nomogram. CONCLUSION: We provide a nomogram of the growth of the fetal alveolar ridge between 14 and 32 weeks' gestation. This will aid the detection of primary cleft palate during routine prenatal sonography.

Alveolar Process↗