Observations and properties of the first laboratory fusion experiment to exceed a target gain of unity

An indirect-drive inertial fusion experiment on the National Ignition Facility was driven using 2.05 MJ of laser light at a wavelength of 351 nm and produced 3.1±0.16 MJ of total fusion yield, producing a target gain G=1.5±0.1 exceeding unity for the first time in a laboratory experiment [Phys. Rev. E 109, 025204 (2024)10.1103/PhysRevE.109.025204]. Herein we describe the experimental evidence for the increased drive on the capsule using additional laser energy and control over known degradation mechanisms, which are critical to achieving high performance. Improved fuel compression relative to previous megajoule-yield experiments is observed. Novel signatures of the ignition and burn propagation to high yield can now be studied in the laboratory for the first time.

"They Give you a bus Ticket and They Kick you Loose": A Qualitative Analysis of Post-Release Experiences among Recently Incarcerated Women Living with HIV in Metro Vancouver, Canada

To explore the transition from correctional facilities to community among women living with HIV in Vancouver, Canada, we interviewed 19 recently incarcerated women and 6 service providers. Findings highlighted heightened risk of violence at release, a lack of immediate supports, challenges accessing safe housing and addictions treatment, and interruptions in HIV treatment and care. In the face of structural barriers, women blamed themselves for not being able to break the cycle of incarceration. There is a critical need for enhanced pre-release planning with a priority on housing and substance use services, alongside supports that are trauma-and violence-informed and culturally safe.

Pathways From Recent Incarceration to Antiretroviral Therapy Adherence: Opportunities for Interventions to Support Women Living With HIV Post Release From Correctional Facilities

ABSTRACT

Women living with HIV are increasingly incarcerated and experience suboptimal HIV health outcomes post release from incarceration. Drawing on cohort data with cisgender and trans women living with HIV (Sexual Health and HIV/AIDS: Women's Longitudinal Needs Assessment), we used path analysis to investigate pathways from recent incarceration to optimal antiretroviral therapy (ART) adherence. We tested direct effects between recent incarceration, mediating variables, and ART adherence, along with indirect effects between incarceration and ART adherence through each mediator. We assessed model fit using chi-square, root-mean-square error of approximation (RMSEA), and comparative fit index (CFI). Our hypothesized model fit well to the data (χ2(1)=1.100; p=.2943; CFI = 1.000; RMSEA = 0.007). Recent experiences of homelessness, criminalized substance use, and gender-based violence each fully mediated the pathway between recent incarceration and optimal ART adherence. Findings highlight the need for safe and supportive housing, supports for criminalized substance use, and trauma and violence-informed care and practice post release from incarceration.

Interpersonal violence and other social-structural barriers associated with needing HIV treatment support for women living with HIV

Women living with HIV (WLWH), experience disproportionate rates of violence, along with suboptimal HIV health outcomes, despite recent advancements in HIV treatment, known as antiretroviral therapy (ART). The objectives of this study were to: (a) describe different types of support needed to take ART and (b) investigate the social and structural correlates associated with needing support for ART adherence among WLWH. Data are drawn from Sexual health and HIV/AIDS: Women's Longitudinal Needs Assessment, a community-based open research cohort with cisgender and transgender WLWH, aged 14+ who live or access HIV services in Metro Vancouver, Canada (2014-present). Baseline and semi-annual questionnaires are administered by community interviewers alongside a clinical visit with a sexual health research nurse. Bivariate and multivariable logistic regression using generalized estimating equations and an exchangeable working correlation matrix was used to model factors associated with needing supports for ART adherence. Among 276 WLWH, 51% (n = 142) reported needing support for ART adherence; 95% of participants reported lifetime gender-based violence and identified many interpersonal, structural, community, and clinical supports that would facilitate and support ART adherence. In multivariable logistic regression, participants who were Indigenous (adjusted odds ratio [AOR]: 1.70, 95% confidence intervals [CI]: 1.07-2.72), or otherwise racialized (AOR: 2.36, 95% CI : 1.09-5.12) versus white, experienced recent gender-based physical violence (AOR : 1.54, 95% CI : 1.03-2.31), lifetime post-traumatic stress disorder (AOR : 1.97, 95% CI : 1.22-3.18), and recent illicit drug use (AOR : 2.15, 95% CI : 1.43-3.22), had increased odds of needing support for ART adherence. This research suggests a need for trauma-informed, culturally safe and culturally responsive practice and services for WLWH along the HIV care continuum to support ART adherence. All services should be developed by, with, and for WLWH and tailored according to gender identity, taking into account history, culture, and trauma, including the negative impacts of settler colonialism for Indigenous people.

Harms of third party criminalisation under end-demand legislation: undermining sex workers' safety and rights

After Canada's laws criminalising sex work were struck down by the Supreme Court for violating sex workers' rights and new end-demand legislation was passed in 2014. These new laws however continue to criminalise sex work third parties (i.e. venue owners/managers) who gain material benefits, despite evidence that managed in-call venues can provide important protections for sex workers. As part of a longstanding community-based study in Vancouver, this analysis drew on 25 in-depth interviews with third parties who provide services for indoor sex workers. We explored how end-demand third party criminalisation shapes indoor sex workers' working conditions, health and safety. We found that most third parties were women and current/former sex workers, problematising assumptions of third parties as exploitative male "pimps". Third parties provided client screening, security and sexual health resources for sex workers, yet end-demand laws restricted condom availability and access to police protections in case of violence, thereby undermining sex workers' health and safety. Our findings highlight that third party criminalisation under end-demand legislation reproduces the unsafe working conditions under the previous laws deemed unconstitutional by Canada's highest court. Legislative reforms to decriminalise all aspects of the sex industry, including sex workers' right to work with third parties, are urgently needed.

"They look at you like you're contaminated": how HIV-related stigma shapes access to care for incarcerated women living with HIV in a Canadian setting

OBJECTIVES

Given the gender disparities in HIV outcomes for women living with HIV (WLWH) who experience incarceration, and the impact of HIV-related stigma on HIV care, this qualitative study investigated how HIV-related stigma within prison settings shapes HIV care for WLWH.

METHODS

Drawing from SHAWNA (Sexual Health and HIV/AIDS: Women's Longitudinal Needs Assessment), a community-based research project with cisgender and transgender WLWH in Metro Vancouver, peer and community interviewers conducted 19 qualitative interviews (May 2017-February 2018) with recently incarcerated WLWH focused on factors that shape incarceration trajectories. Drawing on socio-ecological frameworks and using participatory analysis, this analysis sought to characterize how HIV-related stigma shapes experiences and access to care for incarcerated WLWH.

RESULTS

Participants' responses focused predominately on experiences in provincial correctional facilities and the ways through which HIV-related stigma within correctional settings was linked to access to HIV care. Experiences of HIV-related stigma within prisons led to isolation and discrimination for WLWH which was reinforced through institutional processes, compromised privacy, and uncertainty about confidentiality. Experiences of HIV-related stigma informed decisions for some participants to withhold HIV status from healthcare staff, compromising access to HIV treatment during incarceration.

CONCLUSION

Amid ongoing efforts to improve healthcare delivery within Canadian correctional facilities, these findings have important implications for the provision of HIV care for incarcerated WLWH. Culturally safe, trauma-informed programming focused on reducing HIV-related stigma, improved communication regarding medical privacy, and interventions to change processes that compromise privacy is critical to improve healthcare access in correctional facilities.

The perspectives of people who use drugs regarding short term involuntary substance use care for severe substance use disorders

BACKGROUND

In the Canadian Province of British Columbia (BC), the BC Mental Health Act permits involuntary care for treating mental disorders. However, the Act has also been applied to provide involuntary care to individuals with a primary substance use disorder, in the absence of specific guidelines and legislation, and with insufficient understanding of perspectives of people who use drugs (PWUD) regarding this approach.

METHODS

As part of a larger mixed-methods research project providing an overview of involuntary care for severe substance use disorders in BC, three focus groups were convened with: PWUD, families and caregivers, and Indigenous community stakeholders. This analysis examines perspectives from the focus group of PWUD, consisting of nine participants from local and regional drug user and advocacy organizations regarding involuntary care. A qualitative descriptive approach and thematic analysis were conducted, using a coding framework developed deductively and inductively, and participant perspectives were interpreted drawing on problematization theory.

RESULTS

Participants did not endorse the use of involuntary care, instead emphasizing significant changes were needed to address shortcomings of the wider voluntary care system. When asked to conceptualize what an acceptable involuntary care scenario might look like (under hypothetical and ideal conditions), participants recommended it should include: individual control and autonomy, peer advocacy in decision-making, and elimination of police and criminal justice system involvement from treatment encounters. Participants saw involuntary care to be an inappropriate approach given the shortcomings of the current system, noting also problems inherent in its use to manage severe SUDs and imminent harm, and prioritized alternate approaches to offsetting risks.

CONCLUSION

Improving voluntary care for substance use, along with addressing the social determinants of health that put individuals at risk of problematic substance use and harm, were prioritized in participant perspectives. Participant comments regarding the use of involuntary care bring forward alternate solutions in the context of the opioid overdose crisis, and a reconceptualization of the 'problem' of managing severe substance use disorders.

Short communication: Effect of glucose infusion dose and stage of lactation on glucose tolerance test kinetics in lactating dairy cows

The objective for this study was to determine the effect of glucose dose and days following peak milk yield on plasma glucose, serum insulin, and plasma nonesterified fatty acids (NEFA) kinetics during an intravenous glucose tolerance test (IVGTT) in lactating dairy cattle. Six lactating Holstein dairy cows (3 primiparous and 3 multiparous) were assigned to 2 squares and received 0.092, 0.15, or 0.3 g of glucose/kg of body weight (BW) during an IVGTT at 74 and 221 d in milk (DIM), representing early (post-peak) lactation and mid lactation, respectively. Treatments were applied in a replicated Latin square design using contiguous 7-d periods within each stage of lactation. Milk production and dry matter intake were determined daily during the first 6 d of each period. The IVGTT was performed on d 7. For the IVGTT, cows were prepared with indwelling catheters in each jugular vein, and blood samples were collected at -15, -10, 5, 10, 15, 20, 30, 45, 60, 90, and 120 min relative to the glucose infusion. Samples were analyzed for plasma glucose, serum insulin, and plasma NEFA concentrations. Increasing the glucose dose during the IVGTT increased plasma glucose area under the curve (AUC), decreased glucose half-life, and increased maximal plasma glucose concentrations in plasma during the IVGTT. Greater glucose dose during the IVGTT elevated serum insulin AUC and increased nadir NEFA concentrations. Maximal plasma glucose concentration during the IVGTT was lower, whereas maximum NEFA concentration, NEFA AUC, and NEFA clearance rate were greater at 74 than at 221 DIM. Only glucose half-life was responsive to stage of lactation × glucose dose effects during the IVGTT, and the decrease in glucose half-life with increasing glucose dose was greater at 74 than at 221 DIM. Glucose AUC was greater and NEFA AUC lower for cows at 74 than at 221 DIM. For the doses tested, a glucose dose greater than 0.092 g/kg of BW resulted in peak blood glucose concentration that exceeded the previously reported renal glucose excretion threshold of 8.3 mM. There is a need for accompanying data to determine if this is the case for the glucose doses evaluated in this experiment. Based on maximal peak glucose concentrations and effects on glucose half-life, we identify 0.092 g of glucose/kg of BW (0.46 g/kg of metabolic body weight) as the preferred dose for the IVGTT for cows at 74 and 221 DIM in this study.

Recent Incarceration as a Primary Barrier to Virologic Suppression Among Women Living with HIV: Results from a Longitudinal Community-Based Cohort in a Canadian Setting

Women living with HIV (WLWH) are disproportionately represented among incarcerated populations yet there is a paucity of research on how incarceration shapes HIV treatment outcomes for women. Data is drawn from SHAWNA (Sexual health and HIV/AIDS: Women's Longitudinal Needs Assessment), a longitudinal community-based open research cohort with cis and trans WLWH in Metro Vancouver, Canada (2010-2017). Multivariable logistic regression using generalized estimating equations (GEE) longitudinally modeled the effect of incarceration on virologic suppression (HIV plasma VL < 50 copies/mL), adjusting for potential confounders. Amongst 292 WLWH, the majority (74%) had been incarcerated in their lifetime and 17% were incarcerated over the study period. Exposure to recent incarceration was independently correlated with reduced odds of virologic suppression (AOR: 0.42, 95% CI 0.22-0.80). This study suggests critical need for research and interventions to better address factors shaping ART adherence and retention in care for WLWH, both within correctional centres and following release from prison.

Violence and other social structural factors linked to incarceration for women living with HIV in Metro Vancouver: need for trauma-informed HIV care in prisons and post-Release

Despite women living with HIV (WLWH) being disproportionately criminalized and overrepresented within correctional facilities, there remains limited longitudinal research with WLWH examining factors that make WLWH vulnerable to incarceration. Data are drawn from SHAWNA (Sexual health and HIV/AIDS: Women's Longitudinal Needs Assessment), a community-based research cohort with cisgender and transgender WLWH in Metro Vancouver, Canada. Multivariable logistic regression using generalized estimating equations (GEE) and an exchangeable working correlation matrix was used to prospectively model correlates of recent incarceration exposure over a seven-year period. Amongst 289 WLWH, 76% had been incarcerated in their lifetime, and 17% had experienced recent incarceration. In multivariable GEE analysis, younger age (AOR: 0.92 per year older, 95% CI: 0.89-0.96), recent homelessness (AOR: 2.81, 95% CI: 1.46-5.41), recent gender-based (physical and/or sexual) violence (AOR: 2.26, 95% CI: 1.20-4.22) and recent opioid use (AOR: 1.83, 95% CI: 1.00-3.36), were significantly associated with recent incarceration. Lifetime exposure to gender-based violence by police (AOR: 1.97, CI: 0.97-4.02) was marginally associated with increased odds of recent incarceration. This research suggests a critical need for trauma-informed interventions for WLWH during and following incarceration. Interventions must be gender specific, include housing and substance use supports, and address the impact of gender-based violence.

Interpersonal and structural contexts of intimate partner violence among female sex workers in conflict-affected northern Uganda

Intimate partner violence (IPV) is the most prevalent form of violence against women, yet remains under-researched among sex workers in sub-Saharan Africa. We explored the interpersonal and structural determinants of recent IPV among female sex workers in northern Uganda. This analysis drew on data from a community-based cross-sectional study (conducted May 2011-January 2012), involving 379 female sex workers in Gulu, northern Uganda. Using logistic regression and multivariable modeling, we examined the correlates of recent male-perpetrated physical or sexual IPV. Of 379 women with noncommercial partners, 59 percent reported having experienced recent moderate/severe physical or sexual IPV. Reporting recent client violence (adjusted odds ratio (AOR): 3.67; 95 percent confidence interval [CI]: 2.31-5.83), doing what their partner wanted (AOR: 2.46; 95 percent CI: 1.46-4.13), and forced sexual debut (AOR: 1.92; 95 percent CI: 1.20-3.05) were independently associated with moderate/severe IPV; recent police arrest and/or incarceration were/was marginally significantly associated with IPV (AOR: 2.25; 95 percent CI: 0.86-5.88, p = 0.097). Greater odds of IPV among sex workers were associated with recent workplace violence, forced sexual debut, and gendered power dynamics favoring male partner control. Programs and policies promoting the safety and health of marginalized women and addressing gender dynamics and violence are needed.

Incarceration and exposure to internally displaced persons camps associated with reproductive rights abuses among sex workers in northern Uganda

BACKGROUND

While female sex workers (FSWs) face a high burden of violence and criminalisation, coupled with low access to safe, non-coercive care, little is known about such experiences among FSWs in conflict-affected settings, particularly as they relate to sexual and reproductive health (SRH) and rights. We explored factors associated with lifetime abortions among FSWs in northern Uganda; and separately modelled the independent effect of lifetime exposures to incarceration and living in internally displaced persons (IDP) camps on coerced and unsafe abortions.

METHODS

Analyses are based on a community-based cross-sectional research project in Gulu District, northern Uganda (2011-2012) with The AIDS Support Organization (TASO) Gulu, FSWs, and other community organisations. We conducted questionnaires, sex worker/community-led outreach to sex work venues, and voluntary HIV testing by TASO.

RESULTS

Of 400 FSWs, 62 had ever accessed an abortion. In a multivariable model, gendered violence, both childhood mistreatment/or abuse at home [adjusted odds ratio (AOR) 1.96; 95% confidence interval (95% CI) 0.99-3.90] and workplace violence by clients (AOR 3.57; 95% CI 1.31-9.72) were linked to increased experiences of abortion. Lifetime exposure to incarceration retained an independent effect on increased odds of coerced abortion (AOR 5.16; 95% CI 1.39-19.11), and living in IDP camps was positively associated with unsafe abortion (AOR 4.71; 95% CI 1.42-15.61).

DISCUSSION AND CONCLUSIONS

These results suggest a critical need for removal of legal and social barriers to realising the SRH rights of all women, and ensuring safe, voluntary access to reproductive choice for marginalised and criminalised populations of FSWs.

Echocardiographic evaluation and N-terminal pro-brain natriuretic peptide measurement of patients hospitalized for heart failure during weaning from mechanical ventilation

BACKGROUND

Weaning patients with heart failure who have required mechanical ventilation remains challenging. We evaluated echocardiographic indexes and N-terminal pro-brain natriuretic peptide (NT-proBNP) as markers of acute cardiac dysfunction before and after spontaneous breathing trials (SBT) in such patients to assess their ability to predict subsequent successful extubation.

METHODS

Forty-four patients who underwent their first SBT were prospectively included. Plasma levels of NT-proBNP and transthoracic echocardiography indices including cardiac index, E/A ratio and E/Ea ratio were recorded immediately before commencing and just before the end of SBT.

RESULTS

Ten patients (22.7%) failed their SBT. No significant difference was observed concerning baseline echocardiographic data and NT-proBNP level between the patients who succeeded the SBT or those that failed. Cardiac index increased significantly at end-SBT in patients who passed (3.3 [3.06-3.77] vs. 3 [2.68-3.3] L/min/m(2), P<0.001), whereas it remained unchanged in those that failed. E/Ea ratio (16.8 [8.5-27.3] vs. 10.7 [6.7-20.5], P=0.006) and NT-proBNP level (8199 [3106-10949] vs. 4200 [1855-7125] pg/mL, P=0.004) increased significantly in those who failed the SBT, in contrast to the weaning success group where they remained unchanged.

CONCLUSION

Neither NT-proBNP level nor the studied echocardiographic indices before SBT were able to predict SBT outcome in patients presenting with severe heart failure. Failure to increase the cardiac index and increases in both E/Ea ratio and NT-proBNP levels were seen at end-SBT in patients who failed the SBT, and may reflect failure of myocardial reserve to cope with the stress of SBT.

Anaplasma phagocytophilum in central and western Wisconsin: a molecular survey

Anaplasma phagocytophilum is an obligate intracellular bacterium that is transmitted to humans through the bite of Ixodes spp. ticks, and causes a febrile disease known as human granulocytic anaplasmosis. The presence of A. phagocytophilum in Wisconsin white-tailed deer blood and in deer ticks was assessed using PCR and DNA sequencing. Sampling sites in the western part of the state (Buffalo County) and central region (Waushara, Waupaca, and Green Lake counties) were used. In Buffalo County, 5.6% of deer and 8.9% of ticks were infected. At Hartman Creek State Park (Waupaca County), 11.5% of ticks were infected, while the observed prevalence in deer from counties to the south of the park (Waushara and Green Lake) reached 19-26%. Based on 16S rRNA sequences, A. phagocytophilum strains associated and not associated with human infections were identified. Furthermore, two novel A. phagocytophilum variants were found in deer blood samples. Transmission of Lyme disease has been documented in both the Western and Central regions we sampled, and the presence of A. phagocytophilum in naturally occurring tick populations could present an additional risk of disease to humans that enter tick habitats.

Non-particulate (continuous bed or monolithic) acrylate-based capillary columns for reversed-phase liquid chromatography and electrochromatography

Three approaches are described to synthesize acrylic non-particulate beds (also called continuous beds or monoliths) in aqueous polymerization media for reversed-phase capillary liquid chromatography/electrochromatography. In the first, hexyl acrylate comonomer was dissolved together with water soluble polar comonomers using a non-ionic detergent. In the second, a new alkyl ammonium salt comonomer, (3-allylamino-2-hydroxypropyl)dodecyldimethylammonium chloride was used, which is water soluble and has detergent properties itself. The alkyl group of this comonomer provides hydrophobicity while the ionic groups generate electroosmosis in the non-particulate bed. In the third approach, the alkyl comonomer was used as a detergent to dissolve another hydrophobic comonomer in an aqueous polymerization medium. All three approaches were evaluated with respect to hydrophobicity, efficiency and electroosmotic properties of the beds. Hydrophobicity expressed as methylene group selectivity for the three types of the beds in 50% methanol mobile phase was 1.86, 1.16 and 1.78, electroosmotic mobility -5.14 x 10(-5), 6.89 x 10(-5) and 6.37 x 10(-5) cm2 V(-1) s(-1) and efficiency for the retained compound (methylparabene) 67,000, 93,000 and 110,000 plates m(-1) correspondingly. The columns were tested using pressure driven capillary chromatography and capillary electrochromatography. The influence of polymerization temperature on hydrodynamic permeability, separation impedance and inverse size exclusion porosimetry characteristics were used to evaluate the separation columns. The increase of the polymerization temperature resulted higher permeability of the bed, separation impedance and lower polymeric skeleton porosity. Further characterisation was provided by examining the separation efficiency observed for a series of benzoic acid esters and alkyl parabens.

Botulinum toxin A and chronic low back pain: A randomized, double-blind study

OBJECTIVES

To investigate the efficacy of botulinum toxin A in chronic low back pain and associated disabilities.

METHODS

Thirty-one consecutive patients with chronic low back pain who met the inclusion criteria were studied: 15 received 200 units of botulinum toxin type A, 40 units/site at five lumbar paravertebral levels on the side of maximum discomfort, and 16 received normal saline. Each patient's baseline level of pain and degree of disability was documented using the visual analogue scale (VAS) and the Oswestry Low Back Pain Questionnaire (OLBPQ). The authors reevaluated the patients at 3 and 8 weeks (visual analogue scale) and at 8 weeks (OLBPQ).

RESULTS

At 3 weeks, 11 of 15 patients who received botulinum toxin (73.3%) had >50% pain relief vs four of 16 (25%) in the saline group (p = 0.012). At 8 weeks, nine of 15 (60%) in the botulinum toxin group and two of 16 (12.5%) in the saline group had relief (p = 0.009). Repeat OLBPQ at 8 weeks showed improvement in 10 of 15 (66.7%) in the botulinum toxin group vs three of 16 (18.8%) in the saline group (p = 0.011). No patient experienced side effects.

CONCLUSION

Paravertebral administration of botulinum toxin A in patients with chronic low back pain relieved pain and improved function at 3 and 8 weeks after treatment.

Bilateral painful hand-moving fingers: electrophysiological assessment of the central nervous system oscillator

We describe a 35-year-old woman who presented with the syndrome of painful hand-moving fingers on the right side. Eight months later, she developed similar finger movements and hand discomfort on the left side. She had a history of hand trauma and recurrent shoulder dislocation on the right side. Kinesiologic electromyography suggested a common central oscillator for finger movements in both hands. Electrophysiological assessment of spinal alpha motor neuron excitability, reciprocal inhibition, and Renshaw cell inhibition failed to show any abnormalities. Somatosensory evoked potential test showed marked attenuation of N20 potential recorded from the left somatosensory cortex; paired transcortical magnetic stimulation of the left motor cortex suggested failure of cortical facilitation. The data suggest that the central oscillator responsible for finger movements is located above the spinal cord level in this patient.

Ultraviolet spectrophotometric characterization and bactericidal properties of electrolyzed oxidizing water as influenced by amperage and pH

To identify the primary component responsible in electrolyzed oxidizing (EO) water for inactivation, this study determined the concentrations of hypochlorous acid (HOCl) and hypochlorite ions (OCl-) and related those concentrations to the microbicidal activity of the water. The ultraviolet absorption spectra were used to determine the concentrations of HOCl and OCl- in EO water and the chemical equilibrium of these species with change in pH and amperage. EO water generated at higher amperage contained a higher chlorine concentration. The maximum concentration of HOCl was observed around pH 4 where the maximum log reduction (2.3 log10 CFU/ml) of Bacillus cereus F4431/73 vegetative cells also occurred. The high correlation (r = 0.95) between HOCl concentrations and bactericidal effectiveness of EO water supports HOCl's role as the primary inactivation agent. Caution should be taken with standard titrimetric methods for measurement of chlorine as they cannot differentiate the levels of HOCl present in EO water of varying pHs.

Respiratory changes in vasovagal syncope

INTRODUCTION

Respiratory changes accompany the cardiovascular changes during head-up, tilt test-induced vasovagal syncope.

METHODS AND RESULTS

Using the 45-minute 60 degrees head-up Westminster protocol, 29 patients were studied (mean age 53.9+/-20.0 years; 19 females). Two groups resulted: tilt-induced vasovagal syncope positive and negative. The cardiorespiratory parameters blood pressure (BP), heart rate (HR), tidal volume, and minute volume were measured. Comparisons of the cardiorespiratory parameters were made within the positive group and negative group, and then between the two groups. There were 14 in the positive group and 15 in the negative group. Baseline measurements were normalized to 1.0. Comparing the late tilt periods between the positive and negative groups, there were differences in BP (P < 0.002), HR (P < 0.002), tidal volume (P < 0.05), and minute volume (P < 0.002). In the positive group comparing early with late intervals: BP 1.11+/-0.09 versus 0.49+/-0.17, P < 0.0001; HR 1.18+/-0.12 versus 0.85+/-0.35, P < 0.009; tidal volume 1.39+/-0.34 versus 2.17+/-1.00, P < 0.015; and minute volume 1.24+/-0.26 versus 3.3+/-2.03, P < 0.0025. There were no comparable cardiorespiratory changes in the negative group.

CONCLUSION

There were significant differences in the respiratory and cardiovascular parameters measured between those who were positive and those who were negative for tilt-induced vasovagal syncope. Within the positive group, in addition to the falls in HR and BP, there were significant increases in minute volume and tidal volume during late tilt. This suggests that there may be a role for respiratory sensors in vasovagal syncope that may permit earlier and hence possibly more effective therapy for selected patients.

Sensitive method for detection of human herpesviruses 6 and 7 in saliva collected in field studies

To facilitate studies of the epidemiology and natural history of human herpesviruses 6 and 7 in infants, a practical method for collecting and quantifying the DNA of these viruses was developed. Saliva was collected using small strips of filter paper, and virus was detected using a real-time quantitative fluorescent-probe PCR assay. The sensitivity and specificity of this method even after prolonged drying of the specimens compared favorably to those of our traditional method of collecting and assaying saliva.

Contribution of head-up tilt testing and ATP testing in assessing the mechanisms of vasovagal syndrome: preliminary results and potential therapeutic implications

BACKGROUND

In patients with vasovagal syndrome, head-up tilt testing may reproduce symptoms generally associated with vasodepression. Recent research suggests ATP testing identifies patients with abnormal vagal cardiac inhibition. This preliminary study examined the joint contribution of both tests in identifying underlying mechanisms in the general population with vasovagal syndrome.

METHODS AND RESULTS

Both tests were performed in random order during 1 session and outside of predominant sympathetic periods in 72 patients hospitalized for syncope (n=56) or presyncope (n=16) for whom no cardiac or extracardiac cause was found. For passive and isoproterenol-provocative tilt testing by standard protocol, reproduction of symptoms defined a positive test. The ATP test consisted of injecting ATP 20 mg IV at bedside, continuously monitoring ECG and blood pressure; a vagal cardiac pause >10 seconds defined a positive test. For most patients (64%), >/=1 test was positive. Of the 41 patients (57%) with a positive tilt test (either passive or provoked by isoproterenol), 32% had cardiac disease; none had significant bradycardia (<50 bpm). Of the 8 patients (11%) with a positive ATP test, 62% had cardiac disease; the probability of a positive result increased with age (P=0.015). Both tests were positive in 3 patients and negative in 26 patients; the tilt and ATP test results were uncorrelated (P=0.28).

CONCLUSIONS

Results suggest tilt and ATP tests individually and jointly determine the mechanism of vasovagal symptoms in most patients and that vagal cardiac inhibition increases with age.

Reproducibility of the adenosine-5'-triphosphate test in vasovagal syndrome

INTRODUCTION

Adenosine-5'-triphosphate (ATP) provokes negative chronotropic and dromotropic vagal effects. In vasovagal syndrome, ATP test (20-mg i.v. bolus infusion) represents a promising technique for identifying patients at risk of severe cardioinhibitory response of vagal origin. The electrocardiographic and related symptom reproducibility of this descriptive test must be assessed.

METHODS AND RESULTS

In order to achieve this objective, ATP tests were performed twice in 80 patients (44 men, 36 women; mean age 72.3+/-12.2 years) by using the recently published test procedure and criteria of positivity. The second test was repeated shortly after the initial test (mean: 7 days) in 43 patients and long-term (mean: 3.7 years) in 37 patients. The initial ATP test provoked a cardiac pause > 10 seconds in 31 patients (39%) and a short cardiac pause (< or =10 sec) or no pause in 49 patients (61%). The electrocardiographic outcome was reproduced during the second ATP test in 36 patients (84%) of the short-term group and in 29 patients (78%) of the long-term group. Similarly, symptoms were reproduced in 38 patients (88%) of the short-term group and 29 patients (78%) of the long-term group, reflecting the severity of the electrocardiographic outcome.

CONCLUSION

The negative chronotropic and dromotropic vagal effect of ATP can be reproduced short term and long term in 84% and 78% of patients, respectively. Associated symptoms were related to the severity of the electrocardiographic outcome.

Thoracoscopic anterior spinal procedures in children

METHODS

From February 1996 through July 1997, 20 patients were determined to be appropriate for a thoracoscopic approach for the anterior portion of their spinal surgery. Ages ranged from 8 to 17 years of age and weight from 20 to 70 kg. The diagnosis included severe idiopathic and neurogenic scoliosis or kyphosis (n = 20) and congenital hemivertebra (n = 4). The procedures performed included diskectomy and anterior release from two to nine vertebral levels, hemivertebrectomy, and epiphysiodesis. Four patients also had an open lumbar exposure and all had a posterior fusion.

RESULTS

All procedures were completed successfully endoscopically. Surgical times for the thoracoscopic portion of the procedure averaged 106 minutes and total procedure times were comparable with the standard open technique. Three patients were extubated at the end of the procedure with the majority extubated on postoperative day 1. Average intensive care unit stay was 1.8 days, and chest tubes were removed between postoperative day 1 and 5 (average, 2.2 days). In follow-up, surgical correction was deemed to be acceptable and equivalent to open techniques in all cases.

CONCLUSION

This technique has proven to be safe and effective in children and appears to be associated with less pain and morbidity as evidenced by earlier extubation and chest tube removal and shorter ICU stay.

Right ventricular pressure, dP/dt, and preejection interval during tilt induced vasovagal syncope

This study examined the potential utility of monitoring right ventricular dP/dt as a means of detecting imminent vasovagal syncope. To assess this possibility, continuous right ventricular pressure measurements were recorded in nine patients during induction of syncope by head-up tilt testing. Findings indicated that arterial pressure tended to fall prior to drop in heart rate. RV pressure exhibited a significant, but very small, fall during tilt. DP/dt max increased by 15-20% during tilt, then fell by a median of 30% from maximum value beginning about 2 minutes prior to syncope. Thus, further investigation of dP/dt as a potential marker of impending vasovagal syncope is warranted.

Identification of a new by-product detected in metoprolol tartrate

A new impurity has been found in some batches of metoprolol tartrate. As the amount exceeded 0.1% it was of interest to deduce the structure. Techniques involved in solving the problem were LC, LC-MS and GC-MS. The LC systems showed that the impurity and metoprolol behaved differently to modifications of the mobile phase, indicating that there were differences in the functional groups. LC-MS was used to determine the molecular weight, which was 74 mass units higher than metoprolol. A hydrogen-deuterium shift technique using micro column LC-MS gave the information that three hydrogen atoms were bound to heteroatoms, i.e. one more than in metoprolol. This led to the conclusion that the impurity had three extra carbon and two extra oxygen atoms. It was supposedly a by-product in the synthesis. Knowledge of the synthesis steps for beta-receptor blocking drugs suggested three possible structures. Two were independently synthesized and one of these was found to be identical to the impurity.

Utility of an implantable right ventricular oxygen saturation-sensing pacemaker for ambulatory cardiopulmonary monitoring

Mixed venous oxygen saturation (SvO2) is a physiologic parameter reflecting cardiac output (CO) and tissue oxygen utilization. An implantable oxygen sensor incorporated in a right ventricular pacing lead has been developed to assess the feasibility of ambulatory monitoring of SvO2 to predict cardiorespiratory parameters. Eight patients with a mean age of 62 +/- 2 years and sinoatrial disease received an SvO2-driven dual-chamber rate-adaptive pacemaker capable of continuous SvO2 measurement. During graded maximal exercise with measurement of oxygen consumption (Vo2), arterial oxygen saturation (SaO2), and telemetered derived SvO2 data, CO was assessed using the Fick principle. The accuracy of the derived CO was compared with CO measured directly by continuous-wave Doppler assessment of the ascending aortic flow. The maximum changes in SvO2 and SaO2 during exercise were 25 +/- 5 and 3 +/- 1%, respectively. SvO2 was significantly correlated with Vo2 (r = 0.9 +/- 0.1, p < 0.001), work done (r = 0.8 +/- 0.1, p < 0.05), and minute ventilation (r = 0.9 +/- 0.1, p < 0.05). Doppler-derived CO was significantly correlated with CO estimated from SvO2 measured (r = 0.8 +/- 0.1, p < 0.05) and is expressed as 46x derived CO +300. Although continuous SvO2 sensing was originally developed to increase pacing rate during exercise, its use can be extended for monitoring cardiopulmonary performance on an ambulatory basis. This may be useful as a direct assessment of cardiopulmonary status in diseased states and also as an objective means to evaluate cardiac response to medical therapy in patients with heart failure.

Rate adaptive cardiac pacing using right ventricular venous oxygen saturation: quantification of chronotropic behavior during daily activities and maximal exercise

Central venous oxygen saturation (SvO2) closely reflects cardiac output and tissue oxygen consumption. In the absence of an adequate chronotropic response during exercise, SvO2 will decrease and the extent of desaturation may be used as a parameter for rate adaptive cardiac pacing. Eight patients with sinoatrial disease received a DDDR pacemaker capable of DDDR pacing by sensing either SvO2 or piezoelectric detected body movement. Both sensors were programmed to attain a rate of about 100 beats/min during walking, and with the lower and upper rates set at 50% and 90% of age predicted maximum, respectively. Chronotropic behavior of the two sensors were compared in the DDD mode with measurement of sensor responses, during everyday activities (walking, stair climbing, postural changes, and physiological stresses) and at each quartile of workload during a continuous treadmill exercise test. During walking at 2.5 mph, both sensors showed no significant difference in delay time (both react within 15 secs) or half-time (SvO2 = 36 +/- 12 sec and activity 24 +/- 3 sec; P = NS), although SvO2 driven pacing achieved 90% target rate response slower than activity sensing (124 +/- 16 sec vs 77 +/- 10 sec; P < 0.02). SvO2 pacing was associated with a more physiological rate response during walking upslope (68 +/- 12 beats/min vs 57 +/- 10 beats/min; P < 0.05), ascending stairs (59 +/- 10 beats/min vs 31 +/- 6 beats/min; P < 0.05), and standing (34 +/- 7 beats/min vs 9 +/- 2 beats/min; P < 0.05). The SvO2 sensor significantly overpaced in the first quartile of exercise (51.8 +/- 25.6% in excess of heart rate expected from workload), but the rate was within 20% of expected for the remainder of exercise. "Underpacing" was observed with the activity sensor at the higher workload. In conclusion, the SvO2 sensor demonstrated a more physiological response to activities of daily living compared with the activity sensor. Using a quantitative method, the speed of onset of rate response of the SvO2 sensor was comparable to activity sensing, and was more proportional in rate response. Significant overpacing occurs at the beginning of exercise during SvO2 driven pacing, which may be improved with the use of a curvilinear algorithm.

Hemodynamic response to the upright posture

The authors' objective was to review previous studies of immediate (first 30 seconds) and stabilized (30 seconds to 20 minutes) hemodynamic responses of healthy adults to the head-up posture, with particular reference to alteration of such responses in the elderly and the usefulness of such data in the diagnosis of orthostatic hypotension. The immediate response in healthy young adults is characterized by a prompt rise in heart rate, which peaks at about 8 to 15 seconds and then tapers; the arterial pressure and total vascular resistance decrease sharply at 5 to 10 seconds, followed by a rapid rebound and overshoot. Over the first 30 seconds there is a steady parallel decline of thoracic blood volume and stroke volume; there is also an initial surge of cardiac output followed by a steady decrease. During the stabilized response (30 seconds to 20 minutes), the hemodynamic variables are relatively steady, showing average increases in heart rate of about 15 to 30%, in diastolic pressure of 10 to 15%, and in total vascular resistance of 30 to 40%; during the 5th to 20th minutes there are also decreases in thoracic blood volume averaging about 25 to 30%, in cardiac output 15 to 30%, and in pulse pressure about 5 to 10%. It is evident that in normal human subjects, assumption of the upright posture results in profound hemodynamic changes, most of them occurring during the first 30 seconds. In elderly subjects (aged 60-69 years), there are, in the upright posture, lesser increments of heart rate and diastolic pressure, but no significant differences from younger age groups in the response of thoracic blood volume, cardiac output or total vascular resistance. However, beginning at about age 75, there is an increasing incidence of orthostatic hypotension, which averages about 14 to 20% at age 75 and older. The tendency toward orthostatic hypotension in the elderly is due (1) to the structural and functional changes in the circulation itself, (2) to a decline in autonomic function, and (3) to a probable functional deficiency of the skeletal muscle pump. The authors believe that closer hemodynamic monitoring of orthostatic hypotension patients would considerably increase our understanding and aid in the diagnosis of this condition.