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At least 433 records · Page 24Linked to original sources
PubMed1993

Myofilament sliding per ATP molecule in rabbit muscle fibres studied using laser flash photolysis of caged ATP.

1. To estimate the distance of myofilament sliding per ATP molecule hydrolysed during the actin-myosin interaction in muscle, single glycerinated fibres prepared from rabbit psoas muscle were made to shorten under very small external loads (< or = 0.0005 maximum isometric force (Po), at 20-22 degrees C) by the laser flash photolysis of caged ATP (P3-1-(2-nitro) phenylethyladenosine 5'-triphosphate), a biologically inert and photolabile precursor of ATP. The laser flash-induced fibre shortening was recorded with a high-speed video system at 200 frames s-1. 2. Following the photochemical release of 75-300 microM ATP, the fibres shortened uniformly along the fibre length not only at the level of fibre segments but also at the level of sarcomeres. The fibres did not shorten appreciably in response to 50 microM ATP. 3. The initial velocity of the laser flash-induced fibre shortening increased with increasing concentration of released ATP, being 0.05 +/- 0.01, 0.12 +/- 0.04, 0.23 +/- 0.04, 0.38 +/- 0.03 and 0.95 +/- 0.08 microns s-1 (half-sarcomere)-1 (means +/- S.E.M., n = 10) with 75, 100, 150, 200 and 300 microM ATP, respectively. 4. The distance of the laser flash-induced fibre shortening also increased with increasing concentration of released ATP, being 10 +/- 2, 25 +/- 5, 65 +/- 7, 100 +/- 10 and 180 +/- 20 nm (half-sarcomere)-1 (means +/- S.E.M., n = 10) with 75, 100, 150, 200 and 300 microM ATP, respectively. 5. Comparison of the initial shortening velocities of the laser flash-induced shortening with the force-velocity relation of maximally Ca(2+)-activated fibres indicated the presence of considerable internal resistance against myofilament sliding following release of ATP. The initial velocity of shortening following the release of 300, 150 and 75 microM ATP was equal to the shortening velocity of maximally Ca(2+)-activated fibres under an external load of 0.55, 0.93 and 0.98 Po respectively. 6. These results suggest that, under nearly isometric conditions, the distance of myofilament sliding per ATP molecule hydrolysed is about 10 nm in each half-sarcomere.

Actin Cytoskeleton↗
PubMed1996

S-cone pathway sensitivity in diabetes measured with threshold versus intensity curves on flashed backgrounds.

PURPOSE: To study sensitivity loss to short wavelength lights in patients with diabetes with or without retinopathy and to identify changes that cannot be attributed to preretinal screening. METHODS: Flash-on-flash thresholds were measured in 41 patients with diabetes and were compared to those in age-matched normals. A 50-ms, 1 degree blue test spot was presented simultaneously with a 500-ms, 2 degree blue flash. A bright yellow background isolated the S-cone system. RESULTS: The mean flash-on-flash threshold curve shifted up as the stage of retinopathy progressed in 16 patients with insulin-dependent diabetes mellitus (IDDM), including those without retinopathy. In 25 patients with noninsulin-dependent diabetes mellitus (NIDDM), those with preproliferative retinopathy revealed sensitivity loss; however, those with background retinopathy or without retinopathy showed no statistically significant change in sensitivity. CONCLUSIONS: The pattern of sensitivity loss in the patients with IDDM cannot be caused by changes in preretinal screening, including yellowing of the lens. Further, early functional changes in the patients with IDDM without retinopathy can be detected by this method.

Adolescent↗
PubMed2004

Commonly used types of postmenopausal estrogen for treatment of hot flashes: scientific review.

CONTEXT: Recommendations for postmenopausal hormone therapy have changed since the Women's Health Initiative indicated that estrogen was harmful for use in disease prevention; however, treatment of menopausal symptoms with low-dose estrogen remains an approved indication for use. OBJECTIVE: To compare the short-term efficacy and adverse effects of 2 commonly used estrogens, conjugated equine estrogen (CEE) and 17beta-estradiol, for reducing menopausal hot flashes by systematically reviewing randomized controlled trials. DATA SOURCES: MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews, and Cochrane Controlled Trials Registry were searched from the database start dates to July 2003 using database-specific key words. Reference lists of published articles, experts, and pharmaceutical manufacturers were also consulted. STUDY SELECTION: English-language abstracts of double-blind, randomized, placebo-controlled trials and systematic evidence reviews of oral CEE and oral and transdermal 17beta-estradiol, and treatment of menopausal hot flashes and their adverse effects. DATA EXTRACTION: Study design, population characteristics, eligibility criteria, interventions, withdrawals, adverse effects, and results for each outcome. Study quality was assessed using predefined criteria based on parameters developed with the US Preventive Services Task Force and the UK National Health Services Centre. DATA SYNTHESIS: A total of 32 trials including 4 head-to-head comparisons met inclusion criteria; 14 trials met criteria for meta-analysis. All estrogen agents significantly reduced the weekly number of hot flashes compared with placebo (CEE, 1 trial: mean change, -19.1; 95% confidence interval [CI], -33.0 to -5.1; oral 17beta-estradiol, 5 trials: pooled weighted mean difference, -16.8; 95% CI, -23.4 to -10.2; transdermal 17beta-estradiol, 6 trials: pooled weighted mean difference, -22.4; 95% CI, -35.9 to -10.4); differences between agents were not significant. Breast tenderness and atypical vaginal bleeding were the most frequently reported adverse effects among estrogen users. The influence of progestin or progesterone use, cyclic and continuous regimens, and differences in adverse effects could not be determined. CONCLUSION: Conjugated equine estrogen and 17beta-estradiol have consistent and comparable effects on treatment of menopausal hot flashes and may have similar short-term adverse effects.

Estradiol↗
PubMedDate not supplied

Moclobemide in the treatment of hot flashes in postmenopausal women.

This randomized, prospective, double-blind study evaluated the efficacy and tolerability of moclobemide, a reversible, selective inhibitor of monoamine oxidase-A, in reducing the frequency and severity of hot flashes. Thirty postmenopausal women were enrolled, and 28 were allocated to 5 weeks of treatment with moclobemide 150 mg (group 1, n = 10), moclobemide 300 mg (group 2, n = 11), or placebo (group 3, n = 9). Data on hot flashes were recorded in a daily diary. Mean reductions in the hot flash severity score were 24.4% in the placebo group, 69.8% in group 1, and 35.0% in group 2. This large difference suggests that the beneficial effects were not due to a placebo effect. Moclobemide may be a new nonhormonal option for reducing the incidence, severity, and duration of hot flashes in postmenopausal women who do not wish to take estrogen or have contraindications to its use.

Adult↗
PubMed2005

Hot flash, hot topic: conceptualizing menopausal symptoms from a cognitive-behavioral perspective.

While most healthy women report that the menopausal transition is nondistressing, a subset of women does report that symptoms significantly interfere in their lives. The most common reason that women seek treatment during this time is for vasomotor symptoms, namely, hot flashes and night sweats. Research has suggested that reports of distress during flashing are only weakly related to more objective measures of the flash, including duration and frequency and that differences in treatment-seeking during the menopausal transition may be better accounted for by differences in symptom awareness mediated by a variety of personality and stress factors. This paper discusses hot flashes and night sweats from a cognitive-behavioral perspective, taking into account individual difference variables that may also affect the experience of menopausal symptoms.

Cognitive Behavioral Therapy↗
PubMed1999

Reduced thermoregulatory null zone in postmenopausal women with hot flashes.

OBJECTIVE: Most menopausal hot flashes are preceded by small elevations in core body temperature. If the thermoneutral zone between the thresholds for sweating and shivering is reduced in women with symptoms, the triggering mechanism for hot flashes could be explained. STUDY DESIGN: We studied 12 postmenopausal women with symptoms and 8 without symptoms. We measured body temperatures with a rectal probe, an ingested telemetry pill, and a weighted average of rectal and skin temperatures. Each woman underwent 3 experimental sessions: determination of the sweating threshold by body heating, determination of the shivering threshold by body cooling, and replication of the sweating threshold with exercise. RESULTS: The women with symptoms had significantly smaller interthreshold zones than did the symptom-free women for all 3 measures of body temperature: rectal temperature, 0.0 degrees C +/- 0.06 degrees C versus 0.4 degrees C +/- 0.18 degrees C (P <.005); telemetry pill temperature, 0.0 degrees C +/- 0.11 degrees C versus 0.4 degrees C +/- 0.18 degrees C (P <.005); and mean body temperature, 0.8 degrees C +/- 0.09 degrees C versus 1.5 degrees C +/- 0.20 degrees C (P <. 0006). Sweat rates were significantly higher among the women with symptoms (0.06 +/- 0.002 mg. cm(-2). min(-1)) than among the women without symptoms (0.03 +/- 0.001 mg. cm(-2). min(-1), P <.05). Sweating thresholds during exercise did not significantly differ from those during body heating. During exercise all the women with symptoms and none of the women without symptoms had hot flashes. CONCLUSIONS: Menopausal hot flashes in women with symptoms may be triggered by small elevations in body temperature acting within a reduced thermoneutral zone.

Body Temperature↗
PubMed2001

Management of hot flashes in breast-cancer survivors.

Hot flashes can be a major problem for patients with a history of breast cancer. Although oestrogen can alleviate hot flashes to a large extent in most patients, there has been debate about the safety of oestrogen use in survivors of breast cancer. The decrease in hot flashes achieved with progestational agents is similar to that seen with oestrogen therapy but, again, there is some debate about the safety of progestational agents in patients with a history of breast cancer. Several alternative substances have therefore been investigated. These include a belladonna alkaloid preparation, clonidine, soy phyto-oestrogens, vitamin E, gabapentin, and several of the newer antidepressants, with venlafaxine being the best studied to date. Several studies in progress may provide better non-hormonal means of treating hot flashes in the future.

Antidepressive Agents↗
PubMed1999

Racial differences in menopause information and the experience of hot flashes.

OBJECTIVE: To compare the prevalence of hot flashes and health education regarding menopause in African-American and white American women in the late reproductive years. DESIGN: Cross-sectional study. SETTING: Population-based sample recruited through random digit dialing. PARTICIPANTS: The sample was 436 women between the ages of 35 and 48 years with regular menses. Half the sample was African American and half was white American. MAIN RESULTS: African-American women (53%) were more likely than white American women (29%) to have experienced hot flashes (p < .001). The difference remained after adjustment for body-mass index, education, menstrual cycle characteristics, and gynecologic and medical history. Despite the high prevalence of symptoms, few women had discussed menopausal management with their physicians. For white women the media were the primary source of menopause-related information, whereas African-American women reported that their family was the primary source of information. CONCLUSIONS: These results indicate that hot flashes occur commonly among women in their thirties and forties who have regular menstrual cycles and that the prevalence of hot flashes appears to differ by race. Studies should be designed to evaluate the hormonal and physiologic implications of these symptoms among women in their late reproductive years. Few of these women had discussed menopause with their physicians. Given the differences in sources of information about menopause, development of culture-specific health education programs should be considered.

Adult↗
PubMedDate not supplied

What we know about managing menopausal hot flashes: navigating without a compass.

Hot flashes and night sweats are frequently experienced as the cardinal symptoms of menopause. However, their physiological basis has not been explained; nor have any potential risks been explored. Current knowledge and theoretical perspectives regarding hot flashes will be presented and contrasted with evidence for an emerging hypothesis of altered brain glucose availability as the hot flash trigger. Perspectives regarding hormone therapy and alternative therapies for treatment of hot flashes will be presented and directions for future research reviewed.

Brain Chemistry↗
PubMed2004

Making sense of the evidence regarding nonhormonal treatments for hot flashes.

The demand for nonhormonal interventions for hot flashes is increasing because of the number of patients diagnosed with hormone-sensitive cancers and the results of the Women's Health Initiative indicating that hormone replacement therapy is not as beneficial as originally believed. Since 2002, numerous studies testing nonhormonal treatments for hot flashes have been conducted. Clinicians need to be able to use these research findings to help patients make treatment decisions. Because hot flashes can interfere with activities of daily living such as sleep and work, clinicians first should assess the extent to which hot flashes are disruptive to a woman's life. The evidence for nonhormonal interventions is summarized, and a decision treatment algorithm is offered for use in clinical practice. This algorithm includes nonhormonal options of the antidepressants available in addition to gabapentin, an antiseizure medication. A short review of the evidence for possible complementary therapies also is included.

Acetates↗
PubMed2005

Hot flash experience in men with prostate cancer: a concept analysis.

PURPOSE/OBJECTIVES: To provide a clear definition of the hot flash experience in men with prostate cancer receiving hormonal treatment. DATA SOURCES: Articles, book chapters, and electronic sources. DATA SYNTHESIS: The hot flash experience has not been explored previously in men with prostate cancer. The physiologic and psychological scopes of the phenomenon are described as a multidimensional experience. CONCLUSIONS: The essential attributes of hot flashes in men consist of physiologic (e.g., warmth, sweating, chills) and psychological (e.g., anxiety, impaired memory, agitation) factors. Antecedents to the experience include demographics, disease, and treatment modality. Consequences include effects on sleep, cognition, and health-related quality of life. IMPLICATIONS FOR NURSING: Evaluation of the hot flash experience in men receiving hormonal ablation should include assessment of the symptoms associated with the treatment modality and nursing interventions to help ameliorate symptoms. Future research is needed to focus on providing symptom management to decrease the severity or prevent the occurrence of multiple symptoms related to androgen ablation therapy.

Aged↗
PubMed2003

Venlafaxine hydrochloride for the treatment of hot flashes.

OBJECTIVE: To review the literature evaluating venlafaxine for the treatment of hot flashes. DATA SOURCES: Clinical literature accessed through MEDLINE (1966-August 2002), PubMed, Harrison's Online, and references of reviewed articles. Key terms used were venlafaxine, Effexor, hot flashes, and vasomotor symptoms. DATA SYNTHESIS: Not all patients experiencing hot flashes are candidates for traditional hormonal therapy. Nonhormonal alternatives have long been explored, but conflicting evidence of efficacy exists. CONCLUSIONS: Venlafaxine is an effective nonhormonal alternative for relief from uncontrolled hot flashes.

Clinical Trials as Topic↗
PubMed2006

Intravenous nutrient therapy eliminated androgen deprivation therapy-induced hot flashes in two men with prostate cancer.

Androgen deprivation therapy (ADT) is commonly used for the treatment of prostate cancer. For many undergoing ADT, hot flashes can affect and significantly reduce quality of life. Traditional medications for hot flashes are limited by both clinical effectiveness and side effects. In two case reports, ADT-induced hot flashes quickly resolved after a short course of a specific intravenous combination of vitamins and minerals. This therapeutic approach may have potential for the treatment of ADT-induced hot flashes.

Androgen Antagonists↗
PubMed2001

Estrogen improves impaired musculocutaneous vascular adrenergic reactivity in pharmacologically ovariectomized rats: a potential peripheral mechanism for hot flashes?

Hot flashes are among the most common complaints of perimenopausal women. Despite the high prevalence of the phenomenon, the background to the development of hot flashes is still not completely understood, through a hypothesized central mechanism, involving norepinephrine and luteinizing hormone-releasing hormone (LH-RH) secretion is widely accepted. We studied the influence of sex steroid deficiency and hormone replacement therapy on the biomechanical properties of musculocutaneous arterioles, to see whether a peripheral mechanism also exists in the development of hot flashes. Fifty adult, nulliparous, non-pregnant female Sprague-Dawley rats received pharmacological ovariectomy, and estradiol, medroxyprogesterone, or both hormones. After 12 weeks the saphenous artery was isolated by microdissection. Norepinephrine-induced tone (active tangential strain) was measured as a function of intraluminal pressure in an organ bath. The norepinephrine-induced arterial tone was significantly different between the control group and the ovariectomized animals in the range of 80-150 mmHg intraluminal pressure (p < 0.05). Also, significant differences were found between the ovariectomized group and the animals receiving estradiol monotherapy (p < 0.01 between 80 and 170 mmHg, and p < 0.05 between 180 and 200 mmHg intraluminal pressure). Neither medroxyprogesterone monotherapy nor combined hormone replacement therapy induced significant changes in the norepinephrine-induced vascular tone. The absence of sex steroids leads to decreased reactivity to norepinephrine in small musculocutaneous arteries, while chronic estradiol replacement therapy restores the impaired responsiveness of the vessels. Our data raise the possibility that in addition to the central mechanism, a previously unknown peripheral background mechanism for perimenopausal hot flashes may exist.

Animals↗
PubMed2004

Hot flashes and androgens: a biological rationale for clinical practice.

Hot flashes are the most prevalent symptom of menopause. Although the etiology of hot flashes has yet to be determined, it is increasingly apparent that the physiology of the underlying vasomotor instability is multifactorial. Estrogen and androgen receptors are present in the areas of the central nervous system relevant to hot flashes. Androgens are central to the synthesis of estrogen and to the bioavailability of free estrogen in peripheral tissues. In addition, androgens have direct central nervous system effects that modulate other endocrine factors associated with hot flashes. The pharmacodynamic differences of testosterone and methyltestosterone are briefly reviewed in the context of choice for individualized clinical use.

Algorithms↗
PubMed2006

Nonhormonal therapies for hot flashes in menopause.

Numerous reports in the medical literature and popular media have discussed the effectiveness of various nonhormonal agents in reducing menopausal hot flash symptoms. Data for these therapies are limited, and most of the studies have been conducted in women with a history of breast cancer. Selective serotonin reuptake inhibitors and venlafaxine have been shown to reduce hot flashes by 19 to 60 percent and were well tolerated by study participants. Soy isoflavones reduced hot flashes by 9 to 40 percent in some trials, but most trials showed no difference compared with placebo. Black cohosh and red clover also have had inconsistent results, with some trials showing benefit and some no difference compared with placebo. Soy isoflavones, black cohosh, and red clover were well tolerated in clinical trials. Other agents that have been used to alleviate hot flashes include belladonna/ergotamine tartrate/phenobarbital combination, dong quai, evening primrose oil, gabapentin, ginseng, mirtazapine, trazodone, vitamin E, and wild yam, but few data regarding their effectiveness have been published. Further randomized controlled trials are needed.

Cimicifuga↗
PubMed1999

Temperature measurement using echo-shifted FLASH at low field for interventional MRI.

We investigated the feasibility of using echo-shifted fast low-angle shot (FLASH) for temperature-monitored thermo-therapeutic procedures in a 0.2 T interventional magnetic resonance (MR) scanner. Based on the proton resonance frequency shift technique, modified echo-shifted FLASH has sufficiently high signal-to-noise ratio to provide accurate temperature maps with short scan times, i.e., 5 seconds in phantoms (TR = 20.5 msec; effective TE = 30 msec; one echo shift; NSA = 2) and ex vivo experiments (TR = 19.4 msec; effective TE = 28.9 msec; one echo shift; NSA = 2) and 3 seconds (TR = 19.4 msec; effective TE = 28.9 msec, one echo shift; NSA 1) for an in vivo case. The proton resonance frequency shifts with temperature observed in a 0.2 T MR scanner using this sequence were -0.0072 ppm/degrees C (temperature uncertainty = +/-2.5 degrees C) for polyacrylamide phantoins and -0.0086 ppm/degrees C (temperature uncertainty = +/- 1 degrees C) for ex vivo bovine liver. These experiments demonstrated that echo-shifted FLASH is a viable method for low-field temperature monitoring despite the decreased signal and decreased phase sensitivity compared with its counterpart in a 1.5 T MR imaging system. The improved temporal resolution of temperature images, now possible in low-field interventional MR systems using echo-shifted FLASH, will allow clinicians more accurate monitoring of interstitial ablation in MR-guided interventional procedures.

Animals↗
PubMed1975

Spontaneous and flash-induced multiple unit activity in the hypothalamic gonadotropic areas: effects of photoperiod and of optic nerve section in quail.

The present study was devoted to recording of spontaneous and flash-evoked multiple unit discharges in the gonadotropic areas of the quail hypothalamus and to investigate the influence of the length of the day and of bilateral optic nerve section. Blinding resulted in a marked decrease of MUA in the tuberal region which was musch less important in the dorsal part of the nuclear infundibular complex. Burst and continuous patterns of discharges subsisted in tuberal and dorsal areas of blinded quail but responses to flash were completely suppressed. Lengthening the photofraction led to a very strong reduction of firing rates in both tuberal and dorsal hypothalamic regions. Furthermore, flash stimulation was no longer effective in intact photostimulated quail (18L-6D). Flash-evoked modification of MUA in gonadotropic regions were differentiated in a clear-cut fashion from specific responses which were obtained in the visual system.

Animals↗