An investigation into the reduction in flow rate of intravenous fluid by antireflux valves

We have investigated the extent to which antireflux (non-return) valves impede the maximum flow rate of crystalloid in intravenous infusion systems when administered either under gravity or with 300 mmHg added pressure. When used with a 16G cannula, a reduction in flow rate of 19-38% was consistently seen. With a 20G cannula, no significant reduction in flow was found. The valve tested that produced the least reduction in flow was the Westcott Sae-flo valve.

Anaesthesia with remifentanil and rocuronium for caesarean section in a patient with long-QT syndrome and an automatic implantable cardioverter-defibrillator

A 24-year-old woman with congenital long-QT syndrome (LQTS) required caesarean section at 32 weeks' gestation. Her risk of premature death from malignant ventricular tachyarrhythmias had necessitated implantation of an automatic cardioverter-defibrillator (AICD) with pacemaker capability. The patient expressed a preference for general anaesthesia. To minimise the risk of increased serum catecholamine concentrations and consequent ventricular arrhythmias, an analgesia-based regimen was chosen. With cardioversion, defibrillation, and antitachycardia pacing functions of the AICD selectively deactivated, anaesthesia was induced with bolus doses of thiopentone and remifentanil. Rocuronium was used for neuromuscular block. Anaesthesia was maintained with nitrous oxide and isoflurane, supplemented by a remifentanil infusion. We outline the pathophysiology and treatment of LQTS, and discuss the anaesthetic management of an obstetric patient with the congenital syndrome. This is the first reported case of caesarean section in a patient with an AICD, and the first description of the use of either remifentanil or rocuronium in LQTS.

Prospects for efficient detectors for fast neutron imaging

A physical model describing in detail the process of fast neutron imaging in luminescent screens is presented. The detection quantum efficiency, luminosity and inherent spatial resolution of the screen were calculated using this model. Properties of transparent and disperse screens were compared. Two imaging systems were suggested to improve the detection efficiency and spatial resolution. A stack consisting of alternating neutron converters and image plates can help in obtaining both high spatial resolution and efficiency. A system containing a screen of special form and a diaphragm can be of use especially in the case of the fan beam.

Update on animal models developed for analyses of estrogen receptor biological activity

Targeted disruption of the different ER genes has generated experimental animal models that are very useful in evaluating the distinct and cooperative roles of the two estrogen receptors, ERalpha and ERbeta, in reproductive but also non-reproductive tissues of both sexes. Phenotypic analysis has provided definitive experimental findings for estrogen receptor mediated physiological actions, involving ERalpha in uterine, mammary gland and neuroendocrine sites. ERbeta is involved most dramatically in the ovary as is ERalpha. More detailed studies in combination with tissue specific or inducible ER knock outs will be important for future research.

Stromal cell-derived factor 1, a novel target of estrogen receptor action, mediates the mitogenic effects of estradiol in ovarian and breast cancer cells

Recent clinical studies estimate that 60-70% of human ovarian and breast cancers overexpress the estrogen receptor (ER). However, despite the established mitogenic effects of estrogen in these tumors, proliferative markers of hormone action are limited. In the current study, we report that the growth stimulatory cytokine stromal cell-derived factor 1 (SDF-1) is a bona fide target of estrogen action in ERalpha-positive human ovarian and breast cancer cells. Notably, estradiol treatment of BG-1 (ovarian carcinoma) and MCF-7 (breast carcinoma) cells leads to rapid and robust induction of the SDF-1alpha and beta isoforms. This response is blocked by the pure ER antagonist ICI 182,780 and is not apparent in ER-negative ovarian cells, indicating that SDF-1 regulation is ERalpha mediated. Treatment with the protein synthesis inhibitor cycloheximide had no effect on estradiol induction of induction of SDF-1 mRNA levels mRNA levels, demonstrating that SDF-1 is a direct target of ERalpha. SDF-1 protein levels, although undetectable under basal conditions, were strikingly increased by hormone both intracellularly and in the media of cultured BG-1 and MCF-7 cells. In cell proliferation assays, the mitogenic effects of estradiol were neutralized by addition of an SDF-1 antibody and mimicked by the addition of exogenous SDF-1 protein, indicating that SDF-1 mediates the proliferative actions of hormone. Furthermore, activation of the SDF-1 receptor CXCR4 stimulated BG-1 and MCF-7 cell proliferation in a manner comparable to estradiol. Taken together, these results demonstrate a novel estrogen-mediated paracrine pathway for inducing cancer cell proliferation and suggest that SDF-1 and CXCR4 may represent novel therapeutic targets in ERalpha-positive ovarian and breast tumors.

Molecular determinants of the stereoselectivity of agonist activity of estrogen receptors (ER) alpha and beta

The two known estrogen receptors, ERalpha and ERbeta, are hormone-inducible transcription factors that have distinct roles in regulating cell proliferation and differentiation. Previously, our laboratory demonstrated that ERalpha exhibits stereoselective ligand binding and transactivation for several structural derivatives and metabolites of the synthetic estrogen diethylstilbestrol. We have previously described the properties of indenestrol A (IA) enantiomers on ERalpha. In the study presented here, the estrogenic properties of the S and R enantiomers of IA, IA-S and IA-R, respectively, were expanded to examine the activity in different cell and promoter contexts using ERalpha and ERbeta. Using human cell lines stably expressing either ERalpha or ERbeta, we found that IA-S was a more potent activator of transcription than IA-R through ERalpha in human endometrial Ishikawa and breast MDA-MB 231 (MDA) cells. Interestingly, IA-R was more potent on ERbeta when compared with ERalpha in MDA, but not in Ishikawa cells, and IA-R exhibited equally low binding affinities to ERalpha and ERbeta in vitro in contrast to its cell line-dependent preferential activation of ERbeta. Alignment of the protein structures of the ligand-binding domains of ERalpha and ERbeta revealed one mismatched residue, Leu-384 in ERalpha and Met-283 in ERbeta, which may be responsible for making contact with the methyl substituent at the chiral carbon of IA-S and IA-R. Mutagenesis and exchange of this one residue showed that the binding of IA-R and IA-S was not affected by this mutation in ERalpha and ERbeta. However, in transactivation studies, IA-R showed higher potency in activating L384M-mutated ERalpha and wild-type ERbeta compared with wild-type ERalpha and M283L-mutated ERbeta in all cell and promoter contexts examined. Furthermore, IA-R-bound ERalpha L384M and wild-type ERbeta displayed enhanced interactions with the nuclear receptor interaction domains of the coactivators SRC-1 and GRIP1. These data demonstrate that a single residue in the ligand-binding domain determines the stereoselectivity of ERalpha and ERbeta for indenestrol ligands and that IA-R shows cell type selectivity through ERbeta.

Analysis of the molecular mechanisms of human estrogen receptors alpha and beta reveals differential specificity in target promoter regulation by xenoestrogens

Most of the currently available information on the transcriptional activities of endocrine-disrupting chemicals (xenoestrogens) through estrogen receptors alpha (ERalpha) and beta (ERbeta) has been derived from transactivation studies on synthetic estrogen-responsive reporters. Thus, the ability of the xenoestrogen-liganded ERs to regulate endogenous estrogen-responsive gene expression has not been well characterized. Here, we have evaluated the activities of xenoestrogens through ERalpha and ERbeta on the vitellogenin A2 estrogen-response element (ERE) and the human pS2, lactoferrin, and complement 3 physiological target gene promoters. Using mammalian cell transient transfection assays, we found that the activities of xenoestrogens were mediated in a promoter-specific manner. For example, when bound to all ligands examined, ERalpha displayed high levels of transcription on the vitellogenin ERE and the lactoferrin promoter, but substantially lower activity on the complement 3 and pS2 promoters. However, one of the most important observations was that there were significant differences in the relative transcriptional activities of xenoestrogen-bound ERalpha and ERbeta on different promoters, suggesting that ERalpha and ERbeta make unique contributions to xenoestrogen action in target cells. When probing the molecular mechanism of the promoter-specific activities observed, we found that the transcriptional activity of the ERs correlated with the ability of each receptor to assume an active conformation on specific promoters. Taken together, the results indicate that the transcriptional activities of xenoestrogens are mediated in a promoter-specific manner and that estrogen-responsive promoters communicate differently with ERalpha and ERbeta by influencing their structures in a distinct manner that leads to diversity in their transcriptional responses.

Characterization of adenosine receptors mediating the vasodilator effects of adenosine receptor agonists in the microvasculature of the hamster cheek pouch in vivo

1 The aim of this study was to characterize the adenosine receptor mediating vasodilation in the microvasculature of the hamster cheek pouch in vivo. A range of adenosine agonists was used including N6-cyclopentyladenosine (CPA) (A1 agonist), 5'-N-ethylcarboxamidoadenosine (NECA) (non-selective), 2-chloroadenosine (2CADO) (non-selective), 2-p-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS 21680) (A2A agonist), N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IBMECA) (A3 agonist) and adenosine, as well as the adenosine antagonists 8-sulphophenyltheophylline (8-SPT) (A1/A2 antagonist), 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) (A1 antagonist) and 4-(2-[7-amino-2-(2-furyl)[1,2,4]-triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385) (A2A antagonist). 2 All the adenosine analogues used induced vasodilation at concentrations between 10 nm and 1 microm, and the potency order was NECA > CGS 21680 > 2CADO > CPA=IBMECA >> adenosine, indicating an action at A2A receptors. 8-SPT (50 microm) antagonized vasodilator responses to NECA with an apparent pKB of 5.4, consistent with an action at A1 or A2 receptors and confirming that A3 receptors are not involved in this response. 3 DPCPX (10 nm) had no effect on vasodilation evoked by NECA, suggesting that this response was not mediated via A1 receptors, while ZM 241385 (10 nm) antagonized dilator responses to NECA with an apparent pKB of 8.9 consistent with an action via A2A receptors. 4 Overall these results suggest that adenosine A2A receptors mediate vasodilation in the hamster cheek pouch in vivo.

Allosteric regulation of estrogen receptor structure, function, and coactivator recruitment by different estrogen response elements

Hormone-activated ERs (ERalpha and ERbeta) bind with high affinity to specific DNA sequences, estrogen response elements (EREs), located within the regulatory regions of target genes. Once considered to function solely as receptor tethers, there is an increasing amount of recent evidence to suggest that the sequence of the ERE can influence receptor activity. In this study, we have performed a systematic analysis of the role of different EREs in ER pharmacology. Specifically, by measuring ER activity on the vitellogenin A2, complement 3 gene, pS2, and lactoferrin EREs, we demonstrate that the activities of E2 and xenoestrogen ligands through ERalpha and ERbeta are significantly influenced by the nature of the response element. Using a series of ERalpha and ERbeta interacting peptides that contain the coactivator-binding motif LXXLL, we show that the type of ERE with which the receptor associates regulates the structure of the coactivator pocket on ER. Furthermore, using a novel ELISA developed to measure ER-coactivator interactions revealed that these different conformational states of ERalpha and ERbeta are functionally relevant, as they dictate receptor coactivator binding preference. Together, these results indicate that the DNA response element is a key regulator of receptor structure and biological activity and suggest the ERE sequence influences the recruitment of coactivators to the ER at target gene promoters. We propose that DNA-induced alteration of protein structure and coregulator recruitment may serve as a universal regulatory component for differential gene expression by other nuclear hormone receptors and unrelated transcription factors.

Conceptualizing resilience in women older than 85: overcoming adversity from illness or loss

Resilience in women older than 85 is defined as the ability to achieve, retain, or regain a level of physical or emotional health after devastating illness or loss. This concept analysis of resilience in women older than 85 is based on the strategy suggested by Meleis. Resilience in women older than 85 is symbolized by a coiled wire, enclosed within a box similar to a jack-in-the-box. Environmental factors within the jack-in-the-box include frailty, determination, previous experience with hardship in learning how to cope, access to care, culturally based health beliefs, family support, self-care activities, caring for others, and functioning like efficiently working machines. External factors that influence the ability of the wire to recoil include the structure of the box itself and stress. More study is needed regarding diverse older women's experiences of resilience to develop a workable, clinically focused theory.

Timing patterns of cluster headaches and association with symptoms of obstructive sleep apnea

Cluster headaches (CH) frequently recur at the same point in the circadian cycle, often during sleep. They may, in some cases, represent a susceptible individual's response to hypoxemia or other physiological changes induced by obstructive sleep apnea (OSA). If and when this mechanism exists, timing of CH close to the onset of sleep-and therefore OSA-might be expected. We questioned 36 subjects with CH about the times at which their CH usually occurred and about several symptoms known to be predictive of OSA, including habitual snoring, loud snoring, observed apneas and excessive daytime sleepiness. We then used logistic regression to determine whether occurrence of CH in each of six time periods was associated with OSA symptoms. The 23 subjects (64%) who reported CH in the first half of a typical night's sleep also tended to report headaches during the midday/afternoon period. Symptoms of OSA, and in particular habitual snoring, were predictive of both first-half-of-the-night and midday/afternoon CH (p<.05). Thirty-one subjects (86%) reported that their CH were sleep-related, usually occurring during any part of the night or on awakening, but symptoms of OSA were not predictive of this timing pattern. In short, several OSA symptoms showed an association with CH occurrence in the first half of the night but not with sleep-related CH in general. These findings suggest that in some patients, physiological consequences of OSA may trigger CH during the first few hours of sleep and thereby influence the timing of subsequent daytime headaches.

Sexuality and safer sex: the issues for lesbians and bisexual women

Nursing interventions to help women reduce their risk of contracting HIV must be designed from an in-depth understanding of the complex sociocultural patterns of sexuality in particular communities and among specific subgroups.

OBJECTIVE

In this data collection phase of a community-based HIV prevention project, the objective was to understand HIV risk-taking and HIV risk-reduction activities of lesbians and bisexual women.

DESIGN

Qualitative field study.

SETTING

Data were collected in women's bars and dance clubs and at selected lesbian/bisexual community events in San Francisco.

PARTICIPANTS

Interviews were conducted with 1,189 racially diverse, socially and sexually active lesbians and bisexual women.

RESULTS

Inductive content analysis produced two themes: realities of sexual behavior and sexual expressions and their meanings. Realities of sexual behavior included an assumption that women who have sex with other women cannot get HIV, a lack of familiarity with HIV prevention strategies, inconsistent practice of safer sex with men and/or women, and the negative effect of alcohol or drug use on safer sex efforts. Sexual expressions and their meaning included trust in monogamy, a sense that safer sex practices detracted from intimacy and eroticism, the difficulty of negotiating sexual behaviors with men or women, and dealing with partner resistance to safer sex practices.

CONCLUSIONS

Specific recommendations for practice are the need for nurses to understand the range and diversity of women's sexual behaviors, to develop skills in conducting inclusive sexual histories, and to develop a comprehensive approach to sexual health.

Effects of age and alcoholism on sleep: a controlled study

OBJECTIVE

Sleep problems are common, costly and potentially fatal in older adults. Sleep problems are also commonly associated with alcoholism. Yet few studies have examined the combined effects of alcoholism and aging on sleep. The purpose of this study was to investigate the main and interactive effects on sleep of diagnostic group and age group.

METHOD

Alcohol dependent patients (n = 139; 118 men) and nonalcoholic controls (n = 87; 57 men) completed full-montage polysomnography, structured psychiatric diagnostic interviews, validated rating scales and alcohol histories at the University of Michigan between 1989 and 1996. The sample was divided for analytic purposes into older (aged 55+ years) and younger (aged <55 years) subgroups.

RESULTS

After controlling for gender, race, body mass index and psychiatric-related sleep symptoms, alcoholics and older adults had significantly decreased total sleep time, and increased Stage 1 sleep percentage, respiratory distress and periodic limb movements. Older adults also had decreased delta sleep percentage and shorter rapid eye movement sleep latencies. Significant interactions were found between alcoholism and age group for Stage 1 sleep percentage, sleep-disordered breathing and periodic limb movements, with older alcoholics having the most disturbances. Older alcoholics had the highest mean values for sleep latency and the lowest mean values for sleep efficiency and delta sleep percentage when compared with the other three groups.

CONCLUSIONS

Older alcoholics have increased sleep disturbances when compared with younger alcoholics and with nonalcoholics of both age groups. Care providers should screen for sleep problems among older adults with alcohol problems.

Development of peptide antagonists that target estrogen receptor beta-coactivator interactions

The biological actions of estrogen are manifest through two genetically distinct estrogen receptors (ER alpha and ER beta) that display nonidentical expression patterns in target tissues. The phenotypic alterations in response to estrogens in mice disrupted for either or both of these receptors are not identical, suggesting that each subtype plays a unique role in ER-action. However, the lack of subtype-specific agonists and antagonists has made it difficult to define the processes that are regulated by ER alpha and/or ER beta. Previously, we have reported the identification and characterization of a series of LXXLL-containing peptide antagonists that block estrogen signaling by preventing the association of ER alpha with required coactivators. As expected, given the similarity of the coactivator binding pockets among nuclear receptors, most of the peptide antagonists identified inhibited the activity of multiple receptors. However, by altering sequences flanking the core LXXLL motif, some receptor selectivity was afforded. Building on this observation, we have screened combinatorial phage libraries, expressing peptides in the format X7LXXLLX7, for peptides that interact in a specific manner with ER beta. Using this approach, a series of highly specific, potent peptide antagonists have been identified that efficiently inhibit ER beta-mediated estrogen signaling when introduced into target cells. Interestingly, in cells where both ER subtypes were expressed, these ER beta antagonists were capable of attenuating ER action, suggesting that ER alpha and ER beta do indeed form functional heterodimeric complexes. We believe that suitably formulated versions of these peptides can be used to study ER beta action in vitro and in vivo. In addition, the unanticipated specificity of the peptides identified should serve as an impetus to investigate the use of this approach to develop peptide antagonists of other nuclear receptors and unrelated transcription factors.

Core issues for female child abuse survivors in recovery from substance misuse

Female survivors of childhood abuse have increased risk for substance misuse. Childhood abuse survivors describe current mental health and substance misuse services as not addressing central problems, the "heart of the matter." Negative core issues related to abuse events, contexts, substance use, and current problems were explored in open-ended interviews with 20 female abuse survivors. Most were marginalized because of cocaine use, poverty, and ethnic status. Narrative analysis involved within- and between-account comparisons through adequate paraphrasing of in vivo descriptions. Results include in-depth description of basic core beliefs, developmental core influences, and current core experiences. Implications for practice and policy include appreciation of the influence of negative core experiences on mental health, substance misuse recovery, and preparedness for adulthood demands.

Women survivors of childhood abuse: the impact of traumatic stress on education and work

A disempowering after-effect of childhood abuse that is not well-researched in nursing is the inability of many women abuse survivors to perform successfully in adulthood tasks such as working, managing money, and parenting. This inability often results from lack of family support, cultural impoverishment, limited formal education, and for some, illiteracy. By default, many women survivors engage in criminal, usually dangerous forms of work. A critical/feminist interview study involved 20 urban low income abuse survivors, who were mostly women of color. Participants were recovering cocaine misusers who had suffered multiple forms of childhood maltreatment. This article reports on a secondary analysis of narratives given by survivors, focused on learning and work difficulties. Findings were grouped into five broad domains: (1) school as problematic, (2) lack of adult life skills, (3) problems with academic and health literacy, (4) legitimate and illicit forms of work, and (5) means of help. In vivo quotes support these themes, and policy and practice implications are discussed.

CYP3A activity in African American and European American men: population differences and functional effect of the CYP3A4*1B5'-promoter region polymorphism

OBJECTIVE

Cytochrome P4503A (CYP3A) activity exhibits considerable interindividual variability. Possible differences in CYP3A activity were investigated in European American and African American men with the use of midazolam as an in vivo probe.

METHODS

Midazolam was simultaneously administered intravenously (1 mg, [15N3]-labeled) and orally (2 mg, unlabeled in capsule form) to 15 young healthy European American men and a similar group of men of African American descent. Plasma concentration-time curves were measured. The subjects were subsequently genotyped with respect to the CYP3A4*B1 polymorphism (A-290G) in the 5'-promoter (nifedipine-specific element) region.

RESULTS

The oral bioavailability of midazolam was about equally determined by intestinal and hepatic extraction with CYP3A activity at the former site exhibiting greater variability. Oral bioavailability was related to intestinal metabolism (r = 0.98), whereas hepatic CYP3A activity contributed little to the interindividual variability (r = 0.03). A lower systemic clearance (265+/-54 versus 310+/-56 mL/min; P = .04), but not oral clearance, was observed in African Americans. With one exception, the African Americans possessed a variant CYP3A4*1B allele (4 heterozygotes A/G and 10 homozygote G/G), whereas all of the European Americans were wild-type homozygotes (A/A). Hepatic CYP3A activity and the systemic clearance of midazolam were about 30% lower in G/G homozygotes than in A/A homozygotes (252+/-53 versus 310+/-54 mL/min; P = .02), and a gene-dose effect was present (P = .01). There was no genotype/phenotype relationship with respect to the oral clearance of midazolam.

CONCLUSION

Comparison of CYP3A activity between populations is complicated by frequency distribution differences in the regulatory CYP3A4*1B polymorphism and lower hepatic CYP3A activity associated with the variant allele. However, this reduction is modest; therefore no major and clinically important difference in CYP3A activity is present between Americans of African or European descent.

Sleep disordered breathing in patients with cluster headache

OBJECTIVE

To study subjects with active or inactive cluster headache (CH) for occult sleep disordered breathing (SDB).

BACKGROUND

CH frequently occurs during sleep. The authors previously found that symptoms of SDB predicted reported occurrence of CH in the first half of the night, which suggested that CH could be triggered in some cases by unrecognized SDB.

METHODS

The authors performed polysomnography in 25 adults (22 men) with CH. Subjects were not selected for any sleep-related complaint. In addition to standard measures, studies included monitoring of end-tidal carbon dioxide (n = 22), and esophageal pressure (n = 20).

RESULTS

The rate of apneas and hypopneas per hour of sleep was >5 in 20 subjects (80%; 95% CI, 64% to 96%), minimum oxygen saturation was <90% in 10 subjects, maximum negative esophageal pressure ranged from -13 to -65 cm H2O, and maximum end-tidal carbon dioxide was > or =50 mm Hg in eight subjects. The eight subjects with active (versus inactive) CH at the time of study had higher maximum end-tidal carbon dioxide levels (50 +/- 3 versus 44 +/- 5 mm Hg; p = 0.0007). More severe oxygen desaturation was associated with reports that CH typically occurred in the first half of the nocturnal sleep period (p = 0.008).

CONCLUSIONS

SDB occurred in the majority of patients with CH. Evaluation of a patient with CH should include consideration that SDB may be present.

Clinical trials in the genomic era: effects of protective genotypes on sample size and duration of trial

It is well known that individuals can vary widely in their disease susceptibilities. One potential source of this variation is the genetic makeup of individuals, which can confer either protection or susceptibility to disease. Here we examine the effects of protective genotypes on the sample sizes and time required to detect differences between clinical trial arms. We show that including individuals with protective genotypes in a clinical trial can increase required sample sizes and trial duration. One can deal with this issue by pregenotyping subjects and selectively enrolling them based on their genotype. Thus we also calculate the number of individuals that must be recruited and pregenotyped to fulfill sample size requirements. The benefits of genotypically screening study subjects will depend on numerous factors, including ease of patient recruitment, cost of genotyping, long-term costs of study (or long-term cost per subject), and the strength of the protective effect. We present several examples that show the potential value of incorporating information about protective genotypes into a clinical trial.