Differences in Donor Heart Acceptance by Race and Gender of Patients on the Transplant Waiting List

Importance

Barriers to heart transplant must be overcome prior to listing. It is unclear why Black men and women remain less likely to receive a heart transplant after listing than White men and women.

Objective

To evaluate whether race or gender of a heart transplant candidate (ie, patient on the transplant waiting list) is associated with the probability of a donor heart being accepted by the transplant center team with each offer.

Design, Setting, and Participants

This cohort study used the United Network for Organ Sharing datasets to identify organ acceptance with each offer for US non-Hispanic Black (hereafter, Black) and non-Hispanic White (hereafter, White) adults listed for heart transplant from October 18, 2018, through March 31, 2023.

Exposures

Black or White race and gender (men, women) of a heart transplant candidate.

Main Outcomes and Measures

The main outcome was heart offer acceptance by the transplant center team. The number of offers to acceptance was assessed using discrete time-to-event analyses, nonparametrically (stratified by race and gender) and parametrically. The hazard probability of offer acceptance for each offer was modeled using generalized linear mixed models adjusted for candidate-, donor-, and offer-level variables.

Results

Among 159 177 heart offers with 13 760 donors, there were 14 890 candidates listed for heart transplant; 30.9% were Black, 69.1% were White, 73.6% were men, and 26.4% were women. The cumulative incidence of offer acceptance was highest for White women followed by Black women, White men, and Black men (P < .001). Odds of acceptance were less for Black candidates than for White candidates for the first offer (odds ratio [OR], 0.76; 95% CI, 0.69-0.84) through the 16th offer. Odds of acceptance were higher for women than for men for the first offer (OR, 1.53; 95% CI, 1.39-1.68) through the sixth offer and were lower for the 10th through 31st offers.

Conclusions and Relevance

The cumulative incidence of heart offer acceptance by a transplant center team was consistently lower for Black candidates than for White candidates of the same gender and higher for women than for men. These disparities persisted after adjusting for candidate-, donor-, and offer-level variables, possibly suggesting racial and gender bias in the decision-making process. Further investigation of site-level decision-making may reveal strategies for equitable donor heart acceptance.

Improving cardiovascular outcomes for patients with heart failure in sub-Saharan Africa: conference proceedings of the 2022 Nigerian Cardiovascular Symposium

The Nigerian Cardiovascular Symposium is an annual conference held in partnership with cardiologists in Nigeria and the diaspora to provide updates in cardiovascular medicine and cardiothoracic surgery with the aim of optimising cardiovascular care for the Nigerian population. This virtual conference (due to the COVID-19 pandemic) has created an opportunity for effective capacity building of the Nigerian cardiology workforce. The objective of the conference was for experts to provide updates on current trends, clinical trials and innovations in heart failure, selected cardiomyopathies such as hypertrophic cardiomyopathy and cardiac amyloidosis, pulmonary hypertension, cardiogenic shock, left ventricular assist devices and heart transplantation. Furthermore, the conference aimed to equip the Nigerian cardiovascular workforce with skills and knowledge to optimise the delivery of effective cardiovascular care, with the hope of curbing 'medical tourism' and the current 'brain drain' in Nigeria. Challenges to optimal cardiovascular care in Nigeria include workforce shortage, limited capacity of intensive care units, and availability of medications. This partnership represents a key first step in addressing these challenges. Future action items include enhanced collaboration between cardiologists in Nigeria and the diaspora, advancing participation and enrollment of African patients in global heart failure clinical trials, and the urgent need to develop heart failure clinical practice guidelines for Nigerian patients.

Comparison of droplet spread in standard and laminar flow operating theatres: SPRAY study group

BACKGROUND

Reducing COVID-19 transmission relies on controlling droplet and aerosol spread. Fluorescein staining reveals microscopic droplets.

AIM

To compare the droplet spread in non-laminar and laminar air flow operating theatres.

METHODS

A 'cough-generator' was fixed to a theatre trolley at 45°. Fluorescein-stained 'secretions' were projected on to a series of calibrated targets. These were photographed under UV light and 'source detection' software measured droplet splatter size and distance.

FINDINGS

The smallest droplet detected was ∼120 μm and the largest ∼24,000 μm. An average of 25,862 spots was detected in the non-laminar theatre, compared with 11,430 in the laminar theatre (56% reduction). The laminar air flow mainly affected the smaller droplets (<1000 μm). The surface area covered with droplets was: 6% at 50 cm, 1% at 2 m, and 0.5% at 3 m in the non-laminar air flow; and 3%, 0.5%, and 0.2% in the laminar air flow, respectively.

CONCLUSION

Accurate mapping of droplet spread in clinical environments is possible using fluorescein staining and image analysis. The laminar air flow affected the smaller droplets but had limited effect on larger droplets in our 'aerosol-generating procedure' cough model. Our results indicate that the laminar air flow theatre requires similar post-surgery cleaning to the non-laminar, and staff should consider full personal protective equipment for medium- and high-risk patients.

Advanced heart failure with reduced ejection fraction

Patients suffering advanced heart failure with reduced ejection fraction (HFrEF) account for a large portion of patients admitted to hospitals worldwide. Mortality and 30-day readmission rates for HFrEF are now a focus of value-based payment models, making management of this disease a priority for hospitals, physicians, and payers alike. Angiotensin-converting enzyme inhibitors have been the cornerstone of therapy for decades. However, with treatment, the prognosis for patients with advanced HFrEF remains poor. Fortunately, advances in medical therapy and mechanical support offer some patients improvement in both survival and quality of life. We review advances in short- and long-term mechanical support and explore changes to organ allocation for cardiac transplantation. In addition, we provide a guide to facilitate appropriate referral to an advanced heart failure team.

0112 Lucid Dreaming Associated with Positive Waking Mood

Introduction

Lucid dreaming (being aware that one is dreaming) is typically a positive experience that may enhance positive mood even after waking. There is concern, however, that lucid dreaming may interfere with sleep quality. In the current experiment, participants practiced common lucid dream induction techniques over the course of a week, and kept a daily sleep and dream diary. The study objective was to assess relationships between dream lucidity and subjective sleep quality, dream emotional content, and subsequent waking mood.

Methods

There were 32 participants aged 19–33 in this open label, single arm study (mean=22.63±3.48; 6 males, 24 females). All participants completed a sleep and dream diary for 7 days that included scaled items (1–7 scale) concerning subjective sleep quality, negative and positive emotional intensity of a dream (if recalled). Participants also completed a 19-item lucidity questionnaire, and the Positive and Negative Affect Schedule. Average scores for the week were computed for all measures and Pearson’s correlations conducted between lucidity and all other measures. Participants with no dream recall (n=5) were excluded. Within-subjects analyses were undertaken by selecting each participant’s highest and lowest lucidity night (n=22; 5 participants with only minimum lucidity excluded).

Results

Positive correlations were found between lucidity and dream positive emotion (r=.490, n=27, p=.009) and positive waking mood (r=.638, n=27, p&lt;.001); there were no other significant correlations (all p&gt;.1). Higher lucidity was associated with more positive dream content (t(21)= -3.214, p=.004) and positive waking mood (t(25)=-4.568, p&lt;.001); no other significant differences were observed.

Conclusion

These data indicate that lucidity is associated with positive dreams and waking mood, with no detriment to self-reported sleep quality. The findings provide preliminary support of lucid dreaming as an intervention to improve wellbeing and mood in the short term.

Support

N/A

Epidemiological investigation of grass seed foreign body-related disease in dogs of the Riverina District of rural Australia

OBJECTIVE

To characterise disease presentations caused by grass seed foreign body-related disease (GSFBD) in dogs, identify predisposing risk factors and suggest effective prevention strategies.

METHODS

A retrospective, case-control, telephone survey was conducted to obtain information on GSFBD in dogs from the Riverina district of New South Wales (NSW). Additionally, retrospective case records were obtained from Wagga Wagga Veterinary Hospital and Charles Sturt University Veterinary Teaching Hospital over the period July 2006 to October 2011. Signalment, history, investigative strategies, location and severity of lesion(s), cost of therapy, length of hospitalisation, recurrence rate and microbiology data were recorded.

RESULTS

Cases (473 dogs) meeting stringent inclusion criteria were identified. GSFBD comprised 2.0% of hospital presentations. Breeds with high-density coats were overrepresented. Otitis externa was the most common manifestation of GSFBD in the general practice (47%). In the referral practice pyothorax was the most common entity (34%). In both practices the range of clinical manifestations was broad, including a small number of dogs with catastrophic intracranial disease. Univariable and multivariable logistic regression analyses demonstrated dogs with GSFBD had 3-fold greater odds of having medium coats than short coats and 5-fold less odds of being groomed.

CONCLUSIONS AND CLINICAL RELEVANCE

Grass seeds are a major cause of disease in the dogs of south-west rural NSW, with presentations ranging from mild lameness to severe neurological disease. Some protection from GSFBD was achieved with frequent grooming. Clipping or coat searching without grooming was ineffective as a prevention strategy.

Chronic inactive pulmonary tuberculosis and treatment sequelae: chest radiographic features

The chest radiograph (CXR) is a key initial tool in the diagnosis of many lung conditions, including pulmonary tuberculosis (TB). With proper use of anti-tuberculosis drugs, TB can be treated effectively and many CXR changes are limited. However, anti-tuberculosis drugs have not always been available, and in some cases they have not been started early in the disease process. The infection has then been able to take hold and cause significant radiologically visible damage, such as calcification and fibrosis. Before the use of anti-tuberculosis drugs, a variety of surgical techniques were employed to control pulmonary infection, including plombage, oleothorax, phrenic nerve crush and thoracoplasty. Each of these led to distinctive CXR features. This article sets out to describe the CXR features of chronic disease and surgical treatments, as their increasing rarity with the passage of time has meant that they can be misinterpreted. However, with increasing life expectancy and the revival of surgery due to the development of anti-tuberculosis drug resistance, the correct interpretation of these CXR changes is still of importance.

Lower limb injuries caused by improvised explosive devices: proposed 'Bastion classification' and prospective validation

BACKGROUND

Complex lower limb injury caused by improvised explosive devices (IEDs) has become the signature wounding pattern of the conflict in Afghanistan. Current classifications neither describe this injury pattern well, nor correlate with management. There is need for a new classification, to aid communication between clinicians, and help evaluate interventions and outcomes. We propose such a classification, and present the results of an initial prospective evaluation.

PATIENTS AND METHODS

The classification was developed by a panel of military surgeons whilst deployed to Camp Bastion, Afghanistan. Injuries were divided into five classes, by anatomic level. Segmental injuries were recognised as a distinct entity. Associated injuries to the intraperitoneal abdomen, genitalia and perineum, pelvic ring, and upper limbs, which impact on clinical management and resources, were also accounted for.

RESULTS

Between 1 November 2010 and 20 February 2011, 179 IED-related lower limb injuries in 103 consecutive casualties were classified, and their subsequent vascular and musculoskeletal treatment recorded. 69% of the injuries were traumatic amputations, and the remainder segmental injuries. 49% of casualties suffered bilateral lower limb amputation. The most common injury was class 3 (involving proximal lower leg or thigh, permitting effective above-knee tourniquet application, 49%), but more proximal patterns (class 4 or 5, preventing effective tourniquet application) accounted for 18% of injuries. Eleven casualties had associated intraperitoneal abdominal injuries, 41 suffered genital or perineal injuries, 9 had pelvic ring fractures, and 66 had upper limb injuries. The classification was easy to apply and correlated with management.

CONCLUSIONS

The 'Bastion classification' is a pragmatic yet clinically relevant injury categorisation, which describes current injury patterns well, and should facilitate communication between clinicians, and the evaluation of interventions and outcomes. The validation cohort confirms that the injury burden from IEDs in the Helmand Province of Afghanistan remains high, with most casualties sustaining amputation through or above the knee. The rates of associated injury to the abdomen, perineum, pelvis and upper limbs are high. These findings have important implications for the training of military surgeons, staffing and resourcing of medical treatment facilities, to ensure an adequate skill mix to manage these complex and challenging injuries.

Dual bronchodilatory and pulmonary anti-inflammatory activity of RO5024118, a novel agonist at vasoactive intestinal peptide VPAC2 receptors

BACKGROUND AND PURPOSE

Vasoactive intestinal peptide is expressed in the respiratory tract and induces its effects via its receptors, VPAC(1) and VPAC(2). RO5024118 is a selective VPAC(2) receptor agonist derived via chemical modification of an earlier VPAC(2) agonist, RO0251553. In the present studies, we characterized the pharmacological activity of RO5024118.

EXPERIMENTAL APPROACH

Stability of RO5024118 to human neutrophil elastase was assessed. Bronchodilatory activity of RO5024118 was investigated in guinea pig and human isolated airway smooth muscle preparations and in a guinea pig bronchoconstriction model. Pulmonary anti-inflammatory activity of RO5024118 was investigated in a lipopolysaccharide mouse model and in a porcine pancreatic elastase (PPE) rat model.

KEY RESULTS

RO5024118 demonstrated increased stability to neutrophil elastase compared with RO0251553. In human and guinea pig isolated airway preparations, RO5024118 induced bronchodilatory effects comparable with RO0251553 and the long-acting β-agonist salmeterol and was significantly more potent than native vasoactive intestinal peptide and the short-acting β-agonist salbutamol. In 5-HT-induced bronchoconstriction in guinea pigs, RO5024118 exhibited inhibitory activity with similar efficacy as, and longer duration than, RO0251553. In a lipopolysaccharide-mouse model, RO5024118 inhibited neutrophil and CD8(+) cells and myeloperoxidase levels. In rats, intratracheal instillation of PPE induced airway neutrophilia that was resistant to dexamethasone. Pretreatment with RO5024118 significantly inhibited PPE-induced neutrophil accumulation.

CONCLUSIONS AND IMPLICATIONS

These results demonstrate that RO5024118 induces dual bronchodilatory and pulmonary anti-inflammatory activity and may be beneficial in treating airway obstructive and inflammatory diseases.

LINKED ARTICLES

This article is part of a themed section on Analytical Receptor Pharmacology in Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2010.161.issue-6.

Factors influencing infection patterns of trophically transmitted parasites among a fish community: host diet, host-parasite compatibility or both?

Parasite infection patterns were compared with the occurrence of their intermediate hosts in the diet of nine sympatric fish species in a New Zealand lake. Stomach contents and infection levels of three gastrointestinal helminth species were examined from the entire fish community. The results highlighted some links between fish host diet and the flow of trophically transmitted helminths. Stomach contents indicated that all but one fish species were exposed to these helminths through their diet. Host feeding behaviour best explained infection patterns of the trematode Coitocaecum parvum among the fish community. Infection levels of the nematode Hedruris spinigera and the acanthocephalan Acanthocephalus galaxii, however, were not correlated with host diets. Host specificity is thus likely to modulate parasite infection patterns. The data indicate that host diet and host-parasite compatibility both contribute to the distribution of helminths in the fish community. Furthermore, the relative influence of encounter (trophic interactions between prey and predator hosts) and compatibility (host suitability) filters on infection levels appeared to vary between host-parasite species associations. Therefore, understanding parasite infection patterns and their potential impacts on fish communities requires determining the relative roles of encounter and compatibility filters within and across all potential host-parasite associations.

Achalasia: an unusual cause of airway obstruction

Achalasia is a disorder of the lower oesophageal sphincter and the smooth musculature of the oesophageal body. Although oesophageal obstruction is common, concurrent airway obstruction is exceptional. A case is presented of a 79-year-old woman admitted to the emergency department requiring intubation following out-of-hospital airway obstruction and subsequent respiratory arrest.

Simple measures are as effective as invasive techniques in the diagnosis of pulmonary tuberculosis in Malawi

SETTING

Detection of smear-positive pulmonary tuberculosis (PTB) cases is vital for tuberculosis (TB) control. Methods to augment sputum collection are available, but their additional benefit is uncertain in resource-limited settings.

OBJECTIVE

To compare the diagnostic yields using five methods to obtain sputum from adults diagnosed with smear-negative PTB in Malawi.

DESIGN

Self-expectorated sputum was collected under supervision for microscopy and mycobacterial culture in the study laboratory. Confirmed smear-negative patients provided physiotherapy-assisted sputum and induced sputum, followed the next morning by gastric washing and bronchoalveolar lavage (BAL) samples.

RESULTS

A total of 150 patients diagnosed with smear-negative PTB by the hospital service were screened; 39 (26%) were smear-positive from supervised self-expectorated sputum examined in the study laboratory. The remaining 111 confirmed smear-negative patients were enrolled in the study; 89% were human immunodeficiency virus positive. Seven additional smear-positive cases were diagnosed using the augmented sputum collection techniques. No differences were observed in the numbers of cases detected using the different methods. Of the 46 smear-positive cases, 44 (95.6%) could be detected from self-expectorated and physiotherapy-assisted samples.

CONCLUSIONS

For countries such as Malawi, the best use of limited resources to detect smear-positive PTB cases would be to improve the quality of self-expectorated sputum collection and microscopy. The additional diagnostic yield using BAL after induced sputum is limited.

Which way ahead?: I want my doctor to.... The mechanics of market research for medics in the millenium: special communication

A brief description is given of the changing politico-social structure today involving medicine and especially the cosy personal doctor-patient relationship of the past which has now become triangular involving Managed Health Care Organisations in many cases. The Medical Practitioners' and Dentists' Board (the Board) appointed the Ethics Conference Committee largely composed of non-Board members to collect and collate information of what doctors, paramedics and the lay public expected from their doctors today. It is planned that the Committee's Report summarising this information would form the basis of the new guidelines to modern ethics to be published by the Board later. In this paper the mechanics, funding and production of the report are described but not the contents of the report which is still being considered by the new Board.

Identification of medication-related attendances at an A & E department

BACKGROUND

The use of medication is the most common medical intervention, but it has associated risks. These have been described as drug-related problems (DRPs). Other non-UK studies have reported DRPs to be the cause of 3-16% of hospital admissions and around 4% of attendances at emergency departments. The size of the problem in the UK has not been quantified.

AIM

The aim of this study was to identify the number of patients attending a central London accident and emergency (A & E) department with symptoms or conditions caused by DRPs.

METHOD

A 2-week retrospective, case-review study was conducted in the A & E department of St Thomas' Hospital, London, during March 1999. DRPs were identified using recognized criteria. Statistical analysis identified patient characteristics which could be associated with the incidence of DRPs. The types of DRP and the drugs involved were identified.

RESULTS

During the study period, 106 patients attended the A & E department with a DRP. This equates to 4% of the A & E population. During this period the demographics of the A & E attenders were no different to the annual A & E cohort. The most common DRPs were adverse drug reactions and overdose. The most frequently involved drugs included analgesics, antibiotics, those with narrow therapeutic indices and illegal drugs. The mean age of this patient group was 38 years (non-significant). They attended significantly more frequently during the early hours of the morning and on Saturdays than the A & E general population (chi-squared P = 0.004 and P = 0.003, respectively).

DISCUSSION

The incidence of DRP as a cause of attendance at A & E reflects that in the literature. No statistical association with a specific age group of patients could be made, but the mean age of 38 years is younger than previously reported. The demographic differences which were statistically significant can be explained by the increased incidence of DRP associated with the use of illegal drugs than reported in other studies. Other drug groups identified by this study are representative of other reports.

CONCLUSION

DRPs account for 4% of attendances at a central London A & E Department.

Developments in education and training for nursing home staff

The independent sector has always provided a proportion of the care needed for a variety of client groups in the UK. Although the vast majority of the recipients of care are older people, groups such as those with mental health problems and those suffering from various disabilities are also cared for. The sector is currently facing the need for major changes in the way it provides care. Legislation and a number of reports and strategy documents mean that these changes are necessary for the sector to survive. To drive and to respond to the new situation, education and training has a part to play. This article will examine how the new situation following the sector will impact on the education needs for nurses.

Nedocromil sodium in golfers with seasonal allergic conjunctivitis

To evaluate nedocromil sodium 2% ophthalmic solution for the treatment of seasonal allergic conjunctivitis, 24 golfers with documented ragweed-pollen allergy instilled eyedrops twice daily for 4 days prior to golf-course intervention and 15 minutes before playing a round of golf during peak ragweed season. Ocular symptoms were scored at baseline (7 days before golfing), prior to instillation on the day of golf, and 30 minutes, and 1, 4, 8, and 12 hours after tee-off. Physician assessment was performed prior to tee-off, before tee-off on the ninth hole, and at the end of the 18th hole. Itching, burning, grittiness, tearing, redness, and light sensitivity were significantly decreased after nedocromil administration, as were erythema, edema, conjunctival hyperemia, and overall findings in the conjunctiva. Symptom severity scores fell approximately 30 minutes after instillation, with improvements persisting 8 and 12 hours after treatment. Most patients (92%) rated the treatment moderately or completely effective, and 83% were willing to continue its use. Physician assessments of effectiveness agreed with those of the patients. In this open-label study, nedocromil sodium eyedrops relieved the ocular symptoms of seasonal allergic conjunctivitis for up to 12 hours, well beyond a usual round of golf.

Inhibitory and enhancing effects of IFN-gamma and IL-4 on SHIV(KU) replication in rhesus macaque macrophages: correlation between Th2 cytokines and productive infection in tissue macrophages during late-stage infection

HIV-1 is dual-tropic for CD4+ T lymphocytes and macrophages, but virus production in the macrophages becomes manifest only during late-stage infection, after CD4+ T cell functions are lost, and when opportunistic pathogens begin to flourish. In this study, the SHIV/macaque model of HIV pathogenesis was used to assess the role of cytokines in regulating virus replication in the two cell types. We injected complete Freund's adjuvant (CFA) intradermally into SHIV(KU)-infected macaques, and infused Schistosoma mansoni eggs into the liver and lungs of others. Tissues examined from these animals demonstrated that macrophages induced by CFA did not support viral replication while those induced by S. mansoni eggs had evidence of productive infection. RT-PCR analysis showed that both Th1 (IL-2 and IFN-gamma) and Th2 cytokines (IL-4 and IL-10) were present in the CFA lesions but only the Th2 cytokines were found in the S. mansoni lesions. Follow-up studies in macaque cell cultures showed that whereas IFN-gamma caused enhancement of virus replication in CD4+ T cells, it curtailed viral replication in infected macrophages. In contrast, IL-4 enhanced viral replication in infected macrophages. These studies strongly suggest that cytokines regulate the sequential phases of HIV replication in CD4 T cells and macrophages.

Efficacy and acceptability of nedocromil sodium 2% and olopatadine hydrochloride 0.1% in perennial allergic conjunctivitis

In this 2-week, randomized, crossover study, ophthalmic solutions of nedocromil sodium 2% and olopatadine hydrochloride 0.1% were compared for effectiveness and acceptability in 28 patients with perennial allergic conjunctivitis and previous olopatadine experience. Patients received nedocromil twice daily or olopatadine twice daily for 1 week, then were crossed over to the alternate medication for 1 week. Outcome measures were patient satisfaction (questionnaire), severity of ocular symptoms (daily diary scores), clinical signs (physician assessments), quality of life (questionnaire), and global assessments of effectiveness. Both medications were well accepted. Of the 28 patients, 16 (57.1%) would request a nedocromil prescription, 10 (35.7%) an olopatadine prescription (P = .157); 22 patients (78.6%) would recommend nedocromil to other allergy sufferers, while 18 (64.3%) would recommend olopatadine (P = .480). Light sensitivity scores were significantly lower with nedocromil (P = .0125); other symptom scores were comparable between medications. Both drugs significantly (P < .01) and comparably decreased erythema, conjunctival injection, and overall conjunctival signs from baseline. Comparable improvement also occurred in quality-of-life scores. Both physicians and patients judged nedocromil and olopatadine to be similarly effective in preventing signs and symptoms. Nedocromil sodium 2% is an effective treatment for perennial allergic conjunctivitis. Patients receiving olopatadine can be switched to nedocromil with no loss in efficacy or satisfaction, but with a reduction in cost.

The optimal joint angle for adductor pollicis force production in men and women

The purpose of this study was to determine the joint angle that allows for the greatest MVC and evoked twitch forces from the adductor pollicis (AP), and also whether there is a gender difference in either the above forces or the optimum thumb angle. Ten men (25.2 yrs) and 10 women (27.6 yrs) participated. The nondominant hand was placed palm-down with the thumb fixed at four angles of abduction (55, 70, 85, 100 degrees). Male MVC forces were significantly greater than female, and there was no significant effect of joint angle on MVC force in either gender. For the evoked twitch, men were significantly stronger than women when tested at the 100 and 85 degrees angles, and a significant effect was found for joint angle such that the lowest twitch force occurred at 55 degrees. Men also tended to have a greater rate of force development than women (p = 0.07). These data suggest that studies using the AP muscle in stimulated and voluntary paradigms should use a thumb angle between 70 and 100 degrees of abduction, or approximately 85 degrees, and that the same angle can be used for both men and women.

Tissue oxygenation by near-infrared spectroscopy and muscle blood flow during isometric contractions of the forearm

The relationship between tissue oxygenation measured by near-infrared spectroscopy (NIRS) and forearm muscle blood flow (FBF) measured by Doppler ultrasound was tested during isometric contractions at 10 and 30% maximal voluntary contraction (MVC) under conditions of normoxia and hypoxia (14% inspired O2). Six subjects maintained contractions at 10% MVC for 5 min and 30% for 2 min in both gas conditions. FBF was elevated during exercise at 10% MVC in hypoxia compared to normoxia, but there was no further increase in flow at 30% MVC. Median power frequency calculations from electromyographic recordings suggested progressive development of fatigue throughout both 10 and 30% MVC contractions. NIRS indicated no change in muscle oxygenation at 10% MVC, but deep venous blood O2 saturation was reduced in normoxia and more so in hypoxia. At 30% MVC, both NIRS and venous O2 saturation were reduced, with no effect of hypoxia on the NIRS signal. While NIRS might provide an indication of muscle oxygenation during isometric exercise, the conflicting findings for NIRS and direct venous blood sampling at 10 vs 30% MVC suggest caution in the application of this noninvasive technique.

Becoming ADEPT (Applying Diagnosis, Etiology, Prognosis, and Therapy Programme): delivering distance learning on evidence-based medicine for librarians

Evidence-based medicine (EBM) brings new challenges and opportunities for librarians. However, their ability to respond to this agenda is constrained by their difficulties in acquiring the requisite new skills and techniques while continuing to work in a busy information practice setting. The authors describe a joint initiative, between a specialist evidence-based healthcare information unit and a regional library network, to deliver training materials using a mixed workshop and distance learning format. The Applying Diagnosis, Etiology, Prognosis, and Therapy filters (ADEPT) Programme draws upon research conducted at McMaster University, Canada and, using techniques adapted from the teaching evidence-based medicine paradigm, seeks to equip health care librarians with the skills and techniques required to support evidence-based practice locally. The authors describe the thinking behind the programme, its main features, the extensive evaluation mechanisms incorporated into the course, the results of the evaluation and the lessons learnt. They conclude with a description of the way forward for participants on the programme who are adapting their newly acquired knowledge to their work situations. Further planned developments from the course's designers are also outlined briefly.

Increase in syntaxin 1B mRNA in hippocampal and cortical circuits during spatial learning reflects a mechanism of trans-synaptic plasticity involved in establishing a memory trace

It has long been proposed that the cellular and molecular mechanisms responsible for LTP may well involve the mechanisms that lead to the type of synaptic modification that occurs during learning. However, it is also known that a single memory trace is encoded in spatially distributed networks; implying that alterations of synaptic strength occur at multiple sites along circuits of connected cells. Recent evidence suggests that regulation of the gene encoding syntaxin 1B, a presynaptic protein involved in exocytosis, plays an important role in the mediation of trans-synaptic LTP, a candidate mechanism for the propagation of plasticity in neural circuits during learning. Using in situ hybridization to measure the mRNA levels at different time points after learning a spatial working or reference memory task, we show that expression of the gene encoding this protein in the hippocampal and corticoprefrontal circuits increases linearly with performance at a critical window of learning when rats are reaching between 75% and 100% of their maximal performance. No changes were observed during the early phases of learning or when rats where overtrained. The correlational analysis indicates that coordinated increases in syntaxin 1B expression occurs in hippocampal circuits during working memory and in more widespread hippocampocortical circuits during reference memory. These results suggest that a form of trans-synaptic plasticity mediated in part by regulation of the expression of syntaxin 1B may play an active role in configuring specific spatially distributed circuits during the laying down of memories.

Induction of long-term potentiation in vivo regulates alternate splicing to alter syntaxin 3 isoform expression in rat dentate gyrus

The regulation and specificity of the interactions between the proteins involved in neurotransmitter release are obvious targets for the cellular control of synaptic plasticity. Previous research has identified one of these proteins, syntaxin 1B, as a potential target for mediating the propagation of synaptic plasticity through neural networks. The expression of syntaxin 1B is modified in the hippocampus after the induction of long-term potentiation (LTP) and during learning. Here, we describe the identification of two other members of the syntaxin family from rat brain, syntaxins 3A and 3B, and show that they are generated from the same gene by alternate splicing. In situ hybridization and immunohistochemical staining confirm the expression of syntaxins 3A and 3B in the adult rat brain. The transcripts and proteins show a lower abundance but a similar pattern of expression as syntaxins 1A and 1 B. By using quantitative competitive PCR, we show that the mRNAs that encode syntaxins 1B and 3A are increased in dentate granule cells 6 h after the induction of LTP in vivo, whereas syntaxin 3B mRNA is decreased as rapidly as 30 min, and lasts for at least 6 h, after the induction of LTP. These findings identify coordinated changes in the expression of several syntaxin isoforms with different substrate specificities and suggest that regulation of the splicing machinery by LTP induction is one of the diverse strategies used during the long-term modification of the synapse in the vertebrate nervous system.

The effect of beta-blockade on plasma potassium concentrations and muscle excitability following static exercise

The effects of beta-blockade on plasma [K+], muscle excitability and force during fatiguing exercise were examined. Nine healthy males (mean age 22.3+/-1.7 yr) performed a 3-min fatigue protocol that consisted of a sustained submaximal contraction (30% of the maximal voluntary contraction, MVC) of the right quadriceps muscle. Subjects performed the exercise after treatment with either placebo, beta1-selective (metoprolol, 100 mg) or an equipotent dose of non-selective beta1,2-blockade (propranolol, 80 mg, n=6; 100 mg, n=2; 120 mg, n=1) twice daily for 3 days before testing according to a randomized double-blind design. Brachial arterial and femoral venous blood samples were drawn before, during, and for 15 min following the contraction, together with maximal stimulation of the right femoral nerve to evoke a twitch and a compound muscle action potential (M-wave); the M-wave amplitude being used as an index of sarcolemmal excitability. The exercise-induced rise in plasma [K+] did not differ between treatments, but K+ re-uptake during recovery was slower following propranolol. The recovery of the twitch was significantly related to the recovery of plasma [K+] in all trials, but the evoked M-waves were unaffected by either the contraction or the drug treatment. Propranolol resulted in a significantly (P<0.05) greater reduction (51.9+/-7.3%) in MVC following the 3-min contraction compared with metoprolol (40.7+/-3.6%) or placebo (38. 9+/-3.6%). These results suggest that while beta1,2-blockade may significantly affect the recovery of muscle force and K+ homeostasis after fatiguing exercise (presumably through an inhibition of the Na+,K+-ATPase), it does not appear to affect surface membrane excitability.

Increase in syntaxin 1B and glutamate release in mossy fibre terminals following induction of LTP in the dentate gyrus: a candidate molecular mechanism underlying transsynaptic plasticity

A growing body of evidence suggests that modulation of certain proteins of the exocytotic machinery is, in part, involved in the biochemical changes that underlie long-term synaptic plasticity. We have previously shown that the induction of long-term potentiation (LTP) at perforant path to dentate granule cell synapses in the rat hippocampus induces changes in the mRNA levels of syntaxin 1B and synapsin I, known to be involved in neurotransmitter release. Immunohistochemical staining suggested that concomitant changes in these proteins occurred at mossy fibre synapses, downstream of those synapses at which LTP was induced, leading us to postulate that such a mechanism might underlie a form of transsynaptic plasticity. Here we have used a specific mossy-fibre synaptosome preparation to quantify levels of proteins and measure, using a chemiluminescent glutamate assay, depolarization-induced glutamate release from these synaptosomes after induction of LTP in the dentate gyrus in vivo. We show that 5 h after the induction of LTP, there is an increase in the protein levels of syntaxin 1B and, although to a lesser extent, the synapsins I and II, associated with an increase in depolarization-induced release of glutamate within these terminals. Increases in both the protein levels and glutamate release were not observed when dentate gyrus LTP was blocked by an NMDA receptor antagonist. From these results we propose a molecular mechanism for the propagation of synaptic plasticity through hippocampal circuits.

Early functional and biochemical adaptations to low-frequency stimulation of rabbit fast-twitch muscle

To examine mechanisms underlying force reduction after the onset of chronic low-frequency (10 Hz) stimulation (CLFS), we exposed rabbit tibialis anterior muscles to various durations of CLFS. To follow changes in isometric contractile properties and electromyographic (EMG) activity, we studied stimulated and contralateral muscles during a terminal test at 10 Hz for 10 min. In addition, activities and protein amounts of the sarcoplasmic reticulum Ca(2+)-ATPase, content of Na(+)-K(+)-ATPase, and expression patterns of triad junction components were examined. Force output and EMG amplitude declined abruptly soon after the onset of stimulation, suggesting refractoriness of a large fiber population. Although twitch force and to a lesser extent EMG activity gradually recovered after stimulation for 6 days and longer, the muscles exhibited profoundly altered properties, i.e., enhanced fatigue resistance, absence of twitch potentiation, and prolonged contraction and relaxation times. These changes were associated with significant increases in Na(+)-K(+)-ATPase concentration and significant decreases in Ca(2+)-ATPase, ryanodine receptor, dihydropyridine receptor, and triadin concentrations over the course of the 20 days of stimulation. Alterations in excitability, Ca2+ handling, and excitation-contraction coupling prior to changes in myofibrillar protein isoforms may thus be responsible for early functional alterations.

Synapsin I and syntaxin 1B: key elements in the control of neurotransmitter release are regulated by neuronal activation and long-term potentiation in vivo

The messenger RNAs encoding proteins of the exocytotic machinery were measured at different times following the induction of long-term potentiation or increasing neuronal activity in the dentate gyrus of the rat in vivo. In situ hybridization revealed that from the many messenger RNAs that encode proteins involved in regulated exocytosis, only those encoding synapsin I and syntaxin 1B were specifically increased. The levels of messenger RNA encoding both synapsin I and syntaxin 1B were increased on the ipsilateral side of the dorsal dentate gyrus 2 and 5 h following the induction of long-term potentiation. Syntaxin 1B was also increased in the ventral dentate gyrus at the same time-points. On the contralateral side of the dentate gyrus there was an increase in both synapsin I and syntaxin 1B at 5 h only. All of these long-term potentiation-induced changes were prevented when the tetanus was delivered in the presence of the N-methyl-D-aspartate receptor antagonist. (D(-)-2-amino-5-phosphonopentanoic acid. Immunocytochemical staining revealed that protein levels for both synapsin I and syntaxin 1B were elevated in the mossy fibre terminal zone of CA3 5 h after the induction of long-term potentiation. In addition to these plasticity-induced changes, a transient increase in the messenger RNA encoding syntaxin 1B was observed at 2 h in conditions of high intensity stimulation of the perforant path to increase the level of cellular activation, but this change was not maintained even when high intensity stimulation was sustained for 5 h. No changes in either of the messenger RNAs were observed under low frequency stimulation and pseudotetanus at either time-points. These results show that an overall increase in neuronal excitation within a neuronal network can be differentiated from a change in synaptic strength at a specific subset of the synapses, where only synaptic plasticity leads to long-term changes in the expression of selective members of the exocytotic machinery. Altered concentrations of key vesicle proteins may thus provide the means for modulation of neurotransmitter release over long time-periods. The persistent long-term potentiation-induced postsynaptic increase in messenger RNAs encoding these presynaptic proteins has important implications for the propagation of signals downstream from the site of long-term potentiation induction in hippocampal neural networks, and highlights a candidate molecular mechanism for mediating the propagation of synaptic plasticity in such networks.

A gene map of the human genome

The human genome is thought to harbor 50,000 to 100,000 genes, of which about half have been sampled to date in the form of expressed sequence tags. An international consortium was organized to develop and map gene-based sequence tagged site markers on a set of two radiation hybrid panels and a yeast artificial chromosome library. More than 16,000 human genes have been mapped relative to a framework map that contains about 1000 polymorphic genetic markers. The gene map unifies the existing genetic and physical maps with the nucleotide and protein sequence databases in a fashion that should speed the discovery of genes underlying inherited human disease. The integrated resource is available through a site on the World Wide Web at http://www.ncbi.nlm.nih.gov/SCIENCE96/.

Brain structure and task-specific increase in expression of the gene encoding syntaxin 1B during learning in the rat: a potential molecular marker for learning-induced synaptic plasticity in neural networks

The mRNAs encoding the synaptic vesicle proteins syntaxin 1B and synapsin I were measured using in situ hybridization in several brain regions--the dentate gyrus, CA3 and CA1 of the hippocampus, the parietal, the motor and prefrontal cortices and the core and shell of the accumbens--of rats that were learning a spatial reference or working memory task on a radial arm maze. The mRNA encoding syntaxin 1B was significantly increased in all hippocampal regions in rats learning the working memory task, whereas it was increased in the prelimbic area of the prefrontal cortex and the shell of the accumbens in rats learning the spatial reference memory task. No change in mRNA encoding syntaxin 1B was observed in the motor and parietal and cortices or the core of the accumbens, and the mRNA encoding synapsin I was not significantly different from that of naive caged controls or rats running the maze for continuous reinforcement in any of the brain structures examined. These results demonstrate that the gene encoding a key member of synaptic vesicle function is up-regulated in a task- and brain-specific manner during learning. They are discussed in terms of the potential role this protein may play in trans-synaptic propagation of plasticity within specific neural networks as a function of the information required in the laying down of different types of memory.

The relationship between plasma potassium, muscle membrane excitability and force following quadriceps fatigue

To examine the simultaneous changes in plasma [K+], muscle excitability and force during fatigue, ten male adults (mean age = 22 +/- 0.5 years) held an isometric contraction of their right quadriceps muscle at an intensity of 30% maximum voluntary contraction (MVC) for 3 min. Femoral venous and brachial arterial [K+] were determined from serial samples drawn before, during, and for 15 min following the 3-min contraction. Each blood sample was synchronized with a maximal stimulation of the right femoral nerve to evoke a twitch and compound muscle action potential (M-wave). Immediately post-exercise, twitch torque was only 42% of baseline and femoral venous plasma [K+] had increased significantly from 4.02 +/- 0.08 mmol/l to 5.9 +/- 0.22 mmol/l. Femoral venous plasma lactate rose to a peak level of 10.0 +/- 0.8 mmol/l at 1 min post exercise. The recovery of the twitch torque was exponentially related to the recovery of femoral venous plasma [K+] (r2 = 0.93, P < 0.01). There was no evidence for any loss of muscle membrane excitability during the period of increased extracellular [K+], in fact, the M-waves tended to be potentiated in the early phases of the recovery period. These results suggest that muscle membrane excitability is maintained in spite of increased extracellular [K+] following fatigue induced by a sustained submaximal quadriceps contraction. However, the strong relationship between twitch torque and femoral venous plasma [K+] suggests that K+ may be exerting its effect distal to surface membrane action potential propagation, most likely in the T-tubular region.