In severe alcohol-related hepatitis, acute kidney injury is prevalent, associated with mortality independent of liver disease severity, and can be predicted using IL-8 and micro-RNAs

BACKGROUND

The prevalence, prediction and impact of acute kidney injury (AKI) in alcohol-related hepatitis (AH) is uncertain.

AIMS

We aimed to determine AKI incidence; association with mortality; evaluate serum biomarkers and the modifying effects of prednisolone and pentoxifylline in the largest AH cohort to date.

METHODS

Participants in the Steroids or Pentoxifylline for Alcoholic Hepatitis trial with day zero (D0) creatinine available were included. AKI was defined by modified International Club of Ascites criteria; incident AKI as day 7 (D7) AKI without D0-AKI. Survival was compared by Kaplan-Meier; mortality associations by Cox regression; associations with AKI by binary logistic regression; biomarkers by AUROC analyses.

RESULTS

D0-AKI was present in 198/1051 (19%) participants; incident AKI developed in a further 119/571 (21%) with available data. Participants with D0-AKI had higher 90-day mortality than those without (32% vs. 25%, p = 0.008), as did participants with incident AKI compared to those without D0-AKI or incident AKI (47% vs. 25%, p < 0.001). Incident AKI was associated with D90 mortality adjusted for age and discriminant function (AHR 2.15, 1.56-2.97, p < 0.001); D0-AKI was not. Prednisolone therapy reduced incident AKI (AOR 0.55, 0.36-0.85, p = 0.007) but not mortality. D0 bilirubin and IL-8 combined, miR-6826-5p, and miR-6811-3p predicted incident AKI (AUROCs 0.726, 0.821, 0.770, p < 0.01).

CONCLUSIONS

Incident AKI is associated with 90-day mortality independent of liver function. Prednisolone therapy was associated with reduced incident AKI. IL-8 and several miRNAs are potential biomarkers to predict AKI. Novel therapies to prevent incident AKI should be evaluated in AH to reduce mortality.

Green space for public mental health: an ethnographic study of ecotherapy in Wales

AIMS

In recent years, there has been a growing interest in the ways that human health intersects with exposure to nature. This article reports the findings of a research study investigating the experiences of people in South and West Wales who were engaged in a specific type of nature and health intervention: ecotherapy.

METHODS

Ethnographic methods were used to develop a qualitative account of the experiences of participants in four specific ecotherapy projects. Data collected during fieldwork included notes from participant observations, interviews with both individuals and small groups, and documents produced by the projects.

RESULTS

Findings were reported using two themes: 'smooth and striated bureaucracy' and 'escape and getting away'. The first theme focused on how participants negotiated tasks and systems related to gatekeeping, registration, record keeping, rule compliance, and evaluation. It was argued that this was experienced differently along a spectrum between striated, in which it was disruptive to time and space, and smooth, in which it was much more discrete. The second theme reported on an axiomatic perception that natural spaces represented an escape or refuge; in terms of both reconnecting with something beneficial in nature, and also disconnecting from pathological aspects of everyday life. In bringing the two themes into dialogue, it could be seen that bureaucratic practices often undermined the therapeutic sense of escape; and that this was more acutely experienced by participants from marginalised social groups.

CONCLUSIONS

This article concludes by reasserting that the role of nature in human health is contested and arguing for a greater emphasis on inequities in access to good quality green and blue space. Specific interventions like ecotherapy need funding models that avoid striated bureaucratic processes, and the stress associated with these. Inclusive models of ecotherapy practice could contribute to public health goals related to population engagement with healthy environments.

Gender Differences in the Amount and Type of Student Participation During In-Person and Virtual Classes in Academic Medicine Learning Environments

This cohort study examines gender differences in the amount and type of student participation during in-person and virtual classes in graduate-level academic medicine learning environments.

IL-1 Signal Inhibition In Alcoholic Hepatitis (ISAIAH): a study protocol for a multicentre, randomised, placebo-controlled trial to explore the potential benefits of canakinumab in the treatment of alcoholic hepatitis

BACKGROUND

Alcohol consumption causes a spectrum of liver abnormalities and leads to over 3 million deaths per year. Alcoholic hepatitis (AH) is a florid presentation of alcoholic liver disease characterized by liver failure in the context of recent and heavy alcohol consumption. The aim of this study is to explore the potential benefits of the IL-1β antibody, canakinumab, in the treatment of AH.

METHODS

This is a multicentre, double-blind, randomised placebo-controlled trial. Participants will be diagnosed with AH using clinical criteria. Liver biopsy will then confirm that all histological features of AH are present. Up to 58 participants will be recruited into two groups from 15 centres in the UK. Patients will receive an infusion of Canakinumab or matched placebo by random 1:1 allocation. The primary outcome is the difference between groups in the proportion of patients demonstrating histological improvement and will compare histological appearances at baseline with appearances at 28 days to assign a category of "improved" or "not improved". Patients with evidence of ongoing disease activity will receive a second infusion of canakinumab or placebo. Participants will be followed up for 90 days. Secondary outcomes include mortality and change in MELD score at 90 days.

DISCUSSION

This phase II study will explore the benefits of the IL-1β antibody, canakinumab, in the treatment of AH to provide proof of concept that inhibition of IL-1β signalling may improve histology and survival for patients with AH.

TRIAL REGISTRATION

EudraCT 2017-003724-79 . Prospectively registered on 13 April 2018.

Clinical features and natural history of RASopathy-associated hypertrophic cardiomyopathy in children

Background

The RASopathies are a group of genetic disorders caused by germline mutations in genes encoding components of the RAS/MAPK signalling pathway and frequently associated with hypertrophic cardiomyopathy (HCM). The clinical features and outcomes of RASopathy-related HCM are incompletely understood and most published studies are limited by relatively small numbers and incomplete clinical characterisation.

Purpose

To describe the clinical features outcomes in a large, single-centre cohort of patients with RASopathy-associated HCM diagnosed &lt;18 years.

Methods

Data from 105 patients [68 (64.8%) males] diagnosed in childhood with RASopathy-associated HCM at a single specialist centre between 1985 and 2020 were retrospectively analysed.

Results

The RASopathy diagnosis was Noonan syndrome in 69 patients (65.7%); NSML in 10 (9.5%); CFC in 6 (5.7%); Costello in 5 (4.8%) and 15 patients (14.2%) had another Noonan-like variant. 72 patients (68.6%) had a pathogenic/likely pathogenic variant in a RAS-MAPK gene, most commonly PTPN11 [n=25 (34.7%)], followed by RAF 1 [n=13 (18.1%)]. 100 patients (95.2%) were probands, 9 (8.6%) had family history of cardiomyopathy and 2 (1.9%) family history of sudden cardiac death (SCD). 52 (49.5%) had concomitant congenital heart defects (CHD) [ASD 13 (25%), VSD 6 (11.5%), PDA 1 (1.9%), &gt;1 CHD 32 (61.5%)]. 29 (27.6%) had symptoms at baseline assessment and 56 (53.3%) were on cardiac medication. The distribution of left ventricular hypertrophy (LVH) was concentric in 47 (44.7%); 32 (30.5%) had asymmetric septal hypertrophy (ASH), and undocumented in 25 patients (23.8%). 45 patients (42.9%) had biventricular hypertrophy (BVH). Resting left ventricular outflow tract obstruction (LVOTO) was present in 39 (37.1%) with haemodynamically significant LVOTO (≥50mmHg) in 23 (21.9%). Resting right ventricular outflow tract obstruction (RVOTO) was present in 21 (20%). Over a median follow up time of 6 years, 19 patients (18.1%) died [1 (5.3%) SCD; 2 (10.5%) due to Heart Failure-related death; 1 (5.3%) due to another CVS cause; 5 (26.3%) due to a non-CVS cause and for 10 (52.6%) cause of death was unknown]. Incidence rate of death was calculated at 2.7 deaths per 100 person-years. Surgical septal myectomy was performed in 9 patients (8.6%) and 3 (2.9%) underwent cardiac transplantation. 14 patients (13.3%) suffered arrhythmic events [atrial tachycardia 6 (42.9%), Non-Sustained Ventricular Tachycardia 4 (3.8%), and Ventricular Tachycardia/Ventricular Fibrillation 4 (3.8%)].

Conclusion

To our knowledge, this is the largest cohort of RASopathy-associated HCM. The findings show a heterogeneous clinical presentation with a high prevalence of morbidity and mortality. Further work is needed to determine predictors of outcome in this population.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Onassis Foundation

Yield of Clinical Screening for Hypertrophic Cardiomyopathy in Child First-Degree Relatives

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a heritable myocardial disease with age-related penetrance. Current guidelines recommend clinical screening of relatives beginning at 10 years of age, but the clinical value of this approach has not been systematically evaluated.

METHODS

Anonymized clinical data were collected from children referred for family screening between 1994 and 2017 after diagnosis of HCM in a first-degree relative.

RESULTS

Of 1198 consecutive children (≤18 years of age) from 594 families who underwent serial evaluation (median, 3.5 years; interquartile range, 1.2-7), 32 individuals met diagnostic criteria at baseline (median maximal left ventricular wall thickness, 13 mm; interquartile range, 8-21 mm), and 25 additional patients developed HCM during follow-up. Median age at diagnosis was 10 years (interquartile range, 4-13 years); 44 (72%) were ≤12 years of age. Median age of affected patients at the last follow-up was 14 years (interquartile range, 9.5-18.2 years). A family history of childhood HCM was more common in those patients diagnosed with HCM (n=32 [56%] versus n=257 [23%]; P<0.001). Eighteen patients (32%) were started on medication for symptoms; 2 (4%) underwent a septal myectomy; 14 (25%) received an implantable cardioverter-defibrillator; 1 underwent cardiac transplantation; 2 had a resuscitated cardiac arrest; and 1 died after a cerebrovascular accident.

CONCLUSIONS

Almost 5% of first-degree child relatives undergoing screening meet diagnostic criteria for HCM at first or subsequent evaluations, with the majority presenting as preadolescents; a diagnosis in a child first-degree relative is made in 8% of families screened. The phenotype of familial HCM in childhood is varied and includes severe disease, suggesting that clinical screening should begin at a younger age.

Mutations in the Spliceosome Component CWC27 Cause Retinal Degeneration with or without Additional Developmental Anomalies

Pre-mRNA splicing factors play a fundamental role in regulating transcript diversity both temporally and spatially. Genetic defects in several spliceosome components have been linked to a set of non-overlapping spliceosomopathy phenotypes in humans, among which skeletal developmental defects and non-syndromic retinitis pigmentosa (RP) are frequent findings. Here we report that defects in spliceosome-associated protein CWC27 are associated with a spectrum of disease phenotypes ranging from isolated RP to severe syndromic forms. By whole-exome sequencing, recessive protein-truncating mutations in CWC27 were found in seven unrelated families that show a range of clinical phenotypes, including retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects. Remarkably, variable expressivity of the human phenotype can be recapitulated in Cwc27 mutant mouse models, with significant embryonic lethality and severe phenotypes in the complete knockout mice while mice with a partial loss-of-function allele mimic the isolated retinal degeneration phenotype. Our study describes a retinal dystrophy-related phenotype spectrum as well as its genetic etiology and highlights the complexity of the spliceosomal gene network.

Evaluation of HIV testing recommendations in specialty guidelines for the management of HIV indicator conditions

Objectives

European guidelines recommend HIV testing for individuals presenting with indicator conditions (ICs) including AIDS‐defining conditions (ADCs). The extent to which non‐HIV specialty guidelines recommend HIV testing in ICs and ADCs is unknown. Our aim was to pilot a methodology in the UK to review specialty guidelines and ascertain if HIV was discussed and testing recommended.

Methods

UK and European HIV testing guidelines were reviewed to produce a list of 25 ADCs and 49 ICs. UK guidelines for these conditions were identified from searches of the websites of specialist societies, the National Institute of Clinical Excellence (NICE) website, the NICE Clinical Knowledge Summaries (CKS) website, the Scottish Intercollegiate Guidance Network (SIGN) website and the British Medical Journal Best Practice database and from Google searches.

Results

We identified guidelines for 12 of 25 ADCs (48%) and 36 of 49 (73%) ICs. In total, 78 guidelines were reviewed (range 0–13 per condition). HIV testing was recommended in six of 17 ADC guidelines (35%) and 24 of 61 IC guidelines (39%). At least one guideline recommended HIV testing for six of 25 ADCs (24%) and 16 of 49 ICs (33%). There was no association between recommendation to test and publication year (P = 0.62).

Conclusions

The majority of guidelines for ICs do not recommend testing. Clinicians managing ICs may be unaware of recommendations produced by HIV societies or the prevalence of undiagnosed HIV infection among these patients. We are piloting methods to engage with guideline development groups to ensure that patients diagnosed with ICs/ADCs are tested for HIV. We then plan to apply our methodology in other European settings as part of the Optimising Testing and Linkage to Care for HIV across Europe (OptTEST) project.

Biallelic mutations in the autophagy regulator DRAM2 cause retinal dystrophy with early macular involvement

Retinal dystrophies are an overlapping group of genetically heterogeneous conditions resulting from mutations in more than 250 genes. Here we describe five families affected by an adult-onset retinal dystrophy with early macular involvement and associated central visual loss in the third or fourth decade of life. Affected individuals were found to harbor disease-causing variants in DRAM2 (DNA-damage regulated autophagy modulator protein 2). Homozygosity mapping and exome sequencing in a large, consanguineous British family of Pakistani origin revealed a homozygous frameshift variant (c.140delG [p.Gly47Valfs(∗)3]) in nine affected family members. Sanger sequencing of DRAM2 in 322 unrelated probands with retinal dystrophy revealed one European subject with compound heterozygous DRAM2 changes (c.494G>A [p.Trp165(∗)] and c.131G>A [p.Ser44Asn]). Inspection of previously generated exome sequencing data in unsolved retinal dystrophy cases identified a homozygous variant in an individual of Indian origin (c.64_66del [p.Ala22del]). Independently, a gene-based case-control association study was conducted via an exome sequencing dataset of 18 phenotypically similar case subjects and 1,917 control subjects. Using a recessive model and a binomial test for rare, presumed biallelic, variants, we found DRAM2 to be the most statistically enriched gene; one subject was a homozygote (c.362A>T [p.His121Leu]) and another a compound heterozygote (c.79T>C [p.Tyr27His] and c.217_225del [p.Val73_Tyr75del]). DRAM2 encodes a transmembrane lysosomal protein thought to play a role in the initiation of autophagy. Immunohistochemical analysis showed DRAM2 localization to photoreceptor inner segments and to the apical surface of retinal pigment epithelial cells where it might be involved in the process of photoreceptor renewal and recycling to preserve visual function.

The impact of the 2011 UK post-exposure prophylaxis for HIV following sexual exposure guidelines: a regional retrospective audit

A re-audit of prescribing of post-exposure prophylaxis for HIV following sexual exposure in the Thames Valley demonstrated that an updated proforma has led to significant improvements in clinician-led outcomes, but had no impact on completion or follow-up rates.

Effect of BMP-9 and its derived peptide on the differentiation of human white preadipocytes

Several studies have shown that bone morphogenetic proteins (BMPs) can influence adipogenic and osteogenic cell lineages. We have shown that a peptide derived from BMP-9 (pBMP-9) at 400 ng/ml inhibits the proliferation of preosteoblasts and induces differentiation. We have now determined the effects of pBMP-9 (400 ng/ml) and equimolar concentrations of BMP-2 (100 ng/ml), BMP-9 (84.6 ng/ml) and pBMP-9 (9.04 ng/ml) on human white preadipocytes (HWP). pBMP-9 dose dependently reduced the proliferation of HWP without affecting the number of apoptotic cells. Incubation of the cells for 1 h with BMP-2, BMP-9 or pBMP-9 activated the Smad1/5/8 pathway, while incubation for 7 days in adipocyte differentiation (AD) serum-free medium containing ciglitazone and equimolar concentrations of BMP-2, BMP-9 or pBMP-9 enhanced the levels of mRNA of the adipogenic markers aP2 and adipoQ and increased the number of lipid vesicles. Thus, pBMP-9, like BMP-9, can increase the AD of HWP in AD serum-free medium.

Expression of adiponectin and its receptors in swine1,2

Adiponectin is an adipocyte-derived hormone that plays an important role in lipid metabolism and glucose homeostasis. Objectives of this study were 1) to determine the presence and distribution of adiponectin and its receptors 1 and 2 (adipoR1 and adipoR2) in porcine tissues; 2) to characterize pig adiponectin, adipoR1, and adipoR2 mRNA levels in various fat depots from three different breeds of pigs; and 3) to study, in stromal-vascular cell culture, the effects of leptin and tumor necrosis factor-alpha (TNFalpha) on pig adiponectin, adipoR1, and adipoR2 gene expression. To this end, fat Chinese Upton Meishan (UM, n = 10), lean Ham Line (HL, n = 10), and Large White (LW, n = 10) gilts were used. We report the isolation of partial cDNA sequences of pig adipoR1 and adipoR2. Porcine-deduced AA sequences share 97 to 100% homology with human and murine sequences. Pig adipoR1 mRNA is abundant in skeletal muscle, visceral fat, and s.c. fat tissues, whereas adipoR2 mRNA is predominantly expressed in liver, heart, skeletal muscle, and visceral and s.c. fat tissues. Pig adiponectin mRNA levels in s.c. and visceral fat tissues were not associated with plasma insulin and glucose in fasting animals. Subcutaneous (r = -0.44, P < 0.05), visceral (r = -0.43, P < 0.05), and total body fat (r = -0.42, P < 0.05) weights were negatively correlated with adiponectin mRNA levels measured in visceral, but not s.c., fat. Pig adipoR1 and adipoR2 mRNA levels, in visceral fat, were less expressed in fat UM gilts than in the lean HL gilts (P < 0.05). Inverse associations were found between s.c. (r = -0.57, P < 0.01), visceral (r = -0.46, P < 0.05), and total body fat (r = -0.56, P < 0.01) weights and adipoR2 mRNA levels in visceral fat only. We were unable to find such associations for adipoR1 mRNA levels in the overall gilt population. The current study demonstrated that TNFalpha downregulates adiponectin and adipoR2, but not adi-poR1, mRNA levels in stromal-vascular cell culture. Moreover, leptin significantly decreased adiponectin mRNA levels, whereas there was no effect on adiponectin receptors. We conclude that adiponectin and adi-poR2 mRNA levels, but not adipoR1, are modulated in pig visceral fat tissues. Furthermore, our results indicate that TNFalpha interferes with adiponectin function by downregulation of adipoR2 but not of adipoR1 mRNA levels in pigs.

Ammonia emission, deposition and impact assessment at the field scale: a case study of sub-grid spatial variability

A local ammonia (NH3) inventory for a 5x5 km area in central England was developed, to investigate the variability of emissions, deposition and impacts of NH3 at a field scale, as well as to assess the validity of the UK 5-km grid inventory. Input data were available for the study area for 1993 and 1996 on a field by field basis, allowing NH3 emissions to be calculated for each individual field, separately for livestock grazing, livestock housing and manure storage, landspreading of manures and fertiliser N application to crops and grassland. An existing atmospheric transport model was modified and applied to model air concentrations and deposition of NH3 at a fine spatial resolution (50 m grid). From the mapped deposition estimates and land cover information, critical loads and exceedances were derived. to study the implications of local variability for regional NH3 impacts assessments. The results show that the most extreme local variability in NH3 emissions, deposition and impacts is linked to housing and storage losses. However, landspreading of manures and intensive cattle grazing are other important area sources, which vary substantially in the landscape. Overall, the range of predicted emissions from agricultural land within the study area is 0-2000 kg N ha(-1) year(-1) in 1993 and 0-8000 kg N ha(-1) year(-1) in 1996, respectively, with the peak at a poultry farm located in the study area. On average, the estimated field level NH3 emissions over the study area closely match the emission for the equivalent 5-km grid square in the national inventory for 1996. Deposition and expected impacts are highly spatially variable, with the edges of woodland and small "islands" of semi-natural vegetation in intensive agricultural areas being most at risk from enhanced deposition. Conversely the centres of larger nature reserves receive less deposition than average. As a consequence of this local variability it is concluded that national assessments at the 5 km grid level underestimate the occurrence of critical loads exceedances due to NH3 in agricultural landscapes.

Human papillomavirus virus-like particles are efficient oral immunogens when coadministered with Escherichia coli heat-labile enterotoxin mutant R192G or CpG DNA

Certain human papillomaviruses (HPVs) cause most cervical cancer, which remains a significant source of morbidity and mortality among women worldwide. HPV recombinant virus-like particles (VLPs) are promising vaccine candidates for controlling anogenital HPV disease and are now being evaluated as a parenteral vaccine modality in human subjects. Vaccines formulated for injection generally are more costly, more difficult to administer, and less acceptable to recipients than are mucosally administered vaccines. Since oral delivery represents an attractive alternative to parenteral injection for large-scale human vaccination, the oral immunogenicity of HPV type 11 (HPV-11) VLPs in mice was previously investigated; it was found that a modest systemic neutralizing antibody response was induced (R. C. Rose, C. Lane, S. Wilson, J. A. Suzich, E. Rybicki, and A. L. Williamson, Vaccine 17:2129-2135, 1999). Here we examine whether VLPs of other genotypes may also be immunogenic when administered orally and whether mucosal adjuvants can be used to enhance VLP oral immunogenicity. We show that HPV-16 and HPV-18 VLPs are immunogenic when administered orally and that oral coadministration of these antigens with Escherichia coli heat-labile enterotoxin (LT) mutant R192G (LT R192G) or CpG DNA can significantly improve anti-VLP humoral responses in peripheral blood and in genital mucosal secretions. Our results also suggest that LT R192G may be superior to CpG DNA in this ability. These findings support the concept of oral immunization against anogenital HPV disease and suggest that clinical studies involving this approach may be warranted.

Adhesion and cell movement during pollination: cherchez la femme

Pollination involves an interaction between the female tissues (stigma, style and ovary) and the male gametophyte or the pollen tube cell, which contains the sperm cells. Freezing methods now allow us to visualize the extracellular matrices that guide pollen tubes to the ovary. Adhesion of the pollen tube to these specialized extracellular matrices might be a mechanism of guidance and tube cell movement in the style. In lily, the stylar adhesion molecules are a pectin and a small, basic cysteine-rich protein, both of which are necessary to induce tube cell adhesion to an artificial, in vitro style matrix.

Immunocytochemical labelling of aerobic and hypoxic mammalian cells using a platinated derivative of EF5

The monoclonal antibody ELK3-51 was previously developed to detect adducts of the 2-nitroimidazole EF5. Direct immunofluorescence was used to detect adducts of EF5 or of a platinated derivative cis-[PtCl2(NH3)EF5] in SCCVII cells treated under aerobic or hypoxic conditions. Fluorescence measurements of these cells using both image and flow cytometric methods were compared, giving similar profiles. Platination significantly decreased immunofluorescence levels (approximately 4-fold less than EF5) after 3 h in hypoxia, but also increased levels after exposure in air (approximately 1.5 x) such that the hypoxic ratio decreased from approximately 50 to approximately 13. Platinated EF5 also showed significantly greater cytotoxicity than its parent in both aerobic and hypoxic cells. These results are consistent with targeting of EF5 to DNA, which was confirmed qualitatively by confocal microscopy.

Measurement of right and left ventricular ejection fractions by gated equilibrium scintigraphy using Fourier functional images

Left and right ventricular ejection fractions (LVEF and RVEF) were calculated by gated equilibrium scintigraphy in 28 normal controls and in 21 patients with heart disease. Regions of interest (ROIs) for the ventricles were assigned on the amplitude and phase Fourier images. Two methods of preprocessing of data were compared. In Method 1 the resolution was improved and the statistical noise was reduced, while in Method 2 only the statistical noise was reduced. There were no differences between the results of the two methods for the left ventricle. The mean LVEF for normal subjects was 0.63 +/- 0.06. For the right ventricle, Method 1 showed higher sensitivity in detecting reduced RVEF in pathological situations. The mean RVEF by Method 1 for normal controls was 0.56 +/- 0.07, which is significantly different (p less than 0.001) than that found by Method 2 (0.36 +/- 0.05), and similar to those reported by others employing the firstpass method. The results show the usefulness of the phase Fourier image and the importance of a suitable preprocessing of data for determining RVEF by gated equilibrium scintigraphy.

Measurement of Right and Left Ventricular Ejection Fractions by Gated Equilibrium Scintigraphy Using Fourier Functional Images

Left and right ventricular ejection fractions (LVEF and RVEF) were calculated by gated equilibrium scintigraphy in 28 normal controls and in 21 patients with heart disease. Regions of interest (ROIs) for the ventricles were assigned on the amplitude and phase Fourier images. Two methods of preprocessing of data were compared. In Method 1 the resolution was improved and the statistical noise was reduced, while in Method 2 only the statistical noise was reduced. There were no differences between the results of the two methods for the left ventricle. The mean LVEF for normal subjects was 0.63 ± 0.06. For the right ventricle, Method 1 showed higher sensitivity in detecting reduced RVEF in pathological situations. The mean RVEF by Method 1 for normal controls was 0.56 ± 0.07, which is significantly different (p < 0.001) than that found by Method 2 (0.36 ± 0.05), and similar to those reported by others employing the firstpass method. The results show the usefulness of the phase Fourier image and the importance of a suitable preprocessing of data for determining RVEF by gated equilibrium scintigraphy.

Analysis of the response of B cells from CBA/N-defective mice to nonspecific T cell help

We have investigated the induction of antibody responses to erythrocyte (RBC)-bound antigens in the (CBA/N x B10)F1 mouse. Male B cells, which express the CBA/N defect, were shown to be unresponsive to RBC antigens when the delivered T cell helper activity was solely nonspecific. Thus we demonstrated that defective B cells did not respond to concanavalin A supernatants or bystander helper activity, in spite of the fact that CBA/N-defective mice could produce these T cell activities. The defective B cell did not respond to RBC-bound antigen in the presence of RBC-primed T cells, although the magnitude of this response was usually twofold less than normal controls. The insensitivity of CBA/N defective B cells to nonspecific T cell helper activities seemed to involve at least the inability of RBC antigens to activate defective B cells in the absence of antigen-specific T cell help.

Diminution and enlargement of the mosquito rhabdom in light and darkness

The rhabdoms of the larval ocelli of the mosquito Aedes aegypti undergo morphological light and dark adaptation over periods of hours. The rhabdom enlarges during dark adaptation and grows smaller during light adaptation. Diminution is exponential, enlargement linear, and rates of change are proportional to log light intensity. Rhabdoms maintained at a constant intensity level off at a constant volume proportional to log intensity. We argue that changes in rhabdom volume after changes in light intensity reflect an influence of light on the turnover of photoreceptro membrane, and that the volumes at which rhabdoms level off represent equilibria between opposed processes of membrane loss and renewal.