Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Single-cell analysis of chromatin accessibility in the adult mouse brain

Recent advances in single-cell technologies have led to the discovery of thousands of brain cell types; however, our understanding of the gene regulatory programs in these cell types is far from complete1-4. Here we report a comprehensive atlas of candidate cis-regulatory DNA elements (cCREs) in the adult mouse brain, generated by analysing chromatin accessibility in 2.3 million individual brain cells from 117 anatomical dissections. The atlas includes approximately 1 million cCREs and their chromatin accessibility across 1,482 distinct brain cell populations, adding over 446,000 cCREs to the most recent such annotation in the mouse genome. The mouse brain cCREs are moderately conserved in the human brain. The mouse-specific cCREs-specifically, those identified from a subset of cortical excitatory neurons-are strongly enriched for transposable elements, suggesting a potential role for transposable elements in the emergence of new regulatory programs and neuronal diversity. Finally, we infer the gene regulatory networks in over 260 subclasses of mouse brain cells and develop deep-learning models to predict the activities of gene regulatory elements in different brain cell types from the DNA sequence alone. Our results provide a resource for the analysis of cell-type-specific gene regulation programs in both mouse and human brains.

Single-cell DNA methylome and 3D multi-omic atlas of the adult mouse brain

Cytosine DNA methylation is essential in brain development and is implicated in various neurological disorders. Understanding DNA methylation diversity across the entire brain in a spatial context is fundamental for a complete molecular atlas of brain cell types and their gene regulatory landscapes. Here we used single-nucleus methylome sequencing (snmC-seq3) and multi-omic sequencing (snm3C-seq)1 technologies to generate 301,626 methylomes and 176,003 chromatin conformation-methylome joint profiles from 117 dissected regions throughout the adult mouse brain. Using iterative clustering and integrating with companion whole-brain transcriptome and chromatin accessibility datasets, we constructed a methylation-based cell taxonomy with 4,673 cell groups and 274 cross-modality-annotated subclasses. We identified 2.6 million differentially methylated regions across the genome that represent potential gene regulation elements. Notably, we observed spatial cytosine methylation patterns on both genes and regulatory elements in cell types within and across brain regions. Brain-wide spatial transcriptomics data validated the association of spatial epigenetic diversity with transcription and improved the anatomical mapping of our epigenetic datasets. Furthermore, chromatin conformation diversities occurred in important neuronal genes and were highly associated with DNA methylation and transcription changes. Brain-wide cell-type comparisons enabled the construction of regulatory networks that incorporate transcription factors, regulatory elements and their potential downstream gene targets. Finally, intragenic DNA methylation and chromatin conformation patterns predicted alternative gene isoform expression observed in a whole-brain SMART-seq2 dataset. Our study establishes a brain-wide, single-cell DNA methylome and 3D multi-omic atlas and provides a valuable resource for comprehending the cellular-spatial and regulatory genome diversity of the mouse brain.

Single-cell DNA Methylome and 3D Multi-omic Atlas of the Adult Mouse Brain

Cytosine DNA methylation is essential in brain development and has been implicated in various neurological disorders. A comprehensive understanding of DNA methylation diversity across the entire brain in the context of the brain's 3D spatial organization is essential for building a complete molecular atlas of brain cell types and understanding their gene regulatory landscapes. To this end, we employed optimized single-nucleus methylome (snmC-seq3) and multi-omic (snm3C-seq1) sequencing technologies to generate 301,626 methylomes and 176,003 chromatin conformation/methylome joint profiles from 117 dissected regions throughout the adult mouse brain. Using iterative clustering and integrating with companion whole-brain transcriptome and chromatin accessibility datasets, we constructed a methylation-based cell type taxonomy that contains 4,673 cell groups and 261 cross-modality-annotated subclasses. We identified millions of differentially methylated regions (DMRs) across the genome, representing potential gene regulation elements. Notably, we observed spatial cytosine methylation patterns on both genes and regulatory elements in cell types within and across brain regions. Brain-wide multiplexed error-robust fluorescence in situ hybridization (MERFISH2) data validated the association of this spatial epigenetic diversity with transcription and allowed the mapping of the DNA methylation and topology information into anatomical structures more precisely than our dissections. Furthermore, multi-scale chromatin conformation diversities occur in important neuronal genes, highly associated with DNA methylation and transcription changes. Brain-wide cell type comparison allowed us to build a regulatory model for each gene, linking transcription factors, DMRs, chromatin contacts, and downstream genes to establish regulatory networks. Finally, intragenic DNA methylation and chromatin conformation patterns predicted alternative gene isoform expression observed in a companion whole-brain SMART-seq3 dataset. Our study establishes the first brain-wide, single-cell resolution DNA methylome and 3D multi-omic atlas, providing an unparalleled resource for comprehending the mouse brain's cellular-spatial and regulatory genome diversity.

An atlas of gene regulatory elements in adult mouse cerebrum

The mammalian cerebrum performs high-level sensory perception, motor control and cognitive functions through highly specialized cortical and subcortical structures1. Recent surveys of mouse and human brains with single-cell transcriptomics2-6 and high-throughput imaging technologies7,8 have uncovered hundreds of neural cell types distributed in different brain regions, but the transcriptional regulatory programs that are responsible for the unique identity and function of each cell type remain unknown. Here we probe the accessible chromatin in more than 800,000 individual nuclei from 45 regions that span the adult mouse isocortex, olfactory bulb, hippocampus and cerebral nuclei, and use the resulting data to map the state of 491,818 candidate cis-regulatory DNA elements in 160 distinct cell types. We find high specificity of spatial distribution for not only excitatory neurons, but also most classes of inhibitory neurons and a subset of glial cell types. We characterize the gene regulatory sequences associated with the regional specificity within these cell types. We further link a considerable fraction of the cis-regulatory elements to putative target genes expressed in diverse cerebral cell types and predict transcriptional regulators that are involved in a broad spectrum of molecular and cellular pathways in different neuronal and glial cell populations. Our results provide a foundation for comprehensive analysis of gene regulatory programs of the mammalian brain and assist in the interpretation of noncoding risk variants associated with various neurological diseases and traits in humans.

DNA methylation atlas of the mouse brain at single-cell resolution

Mammalian brain cells show remarkable diversity in gene expression, anatomy and function, yet the regulatory DNA landscape underlying this extensive heterogeneity is poorly understood. Here we carry out a comprehensive assessment of the epigenomes of mouse brain cell types by applying single-nucleus DNA methylation sequencing1,2 to profile 103,982 nuclei (including 95,815 neurons and 8,167 non-neuronal cells) from 45 regions of the mouse cortex, hippocampus, striatum, pallidum and olfactory areas. We identified 161 cell clusters with distinct spatial locations and projection targets. We constructed taxonomies of these epigenetic types, annotated with signature genes, regulatory elements and transcription factors. These features indicate the potential regulatory landscape supporting the assignment of putative cell types and reveal repetitive usage of regulators in excitatory and inhibitory cells for determining subtypes. The DNA methylation landscape of excitatory neurons in the cortex and hippocampus varied continuously along spatial gradients. Using this deep dataset, we constructed an artificial neural network model that precisely predicts single neuron cell-type identity and brain area spatial location. Integration of high-resolution DNA methylomes with single-nucleus chromatin accessibility data3 enabled prediction of high-confidence enhancer-gene interactions for all identified cell types, which were subsequently validated by cell-type-specific chromatin conformation capture experiments4. By combining multi-omic datasets (DNA methylation, chromatin contacts, and open chromatin) from single nuclei and annotating the regulatory genome of hundreds of cell types in the mouse brain, our DNA methylation atlas establishes the epigenetic basis for neuronal diversity and spatial organization throughout the mouse cerebrum.

A multimodal cell census and atlas of the mammalian primary motor cortex

Here we report the generation of a multimodal cell census and atlas of the mammalian primary motor cortex as the initial product of the BRAIN Initiative Cell Census Network (BICCN). This was achieved by coordinated large-scale analyses of single-cell transcriptomes, chromatin accessibility, DNA methylomes, spatially resolved single-cell transcriptomes, morphological and electrophysiological properties and cellular resolution input-output mapping, integrated through cross-modal computational analysis. Our results advance the collective knowledge and understanding of brain cell-type organization1-5. First, our study reveals a unified molecular genetic landscape of cortical cell types that integrates their transcriptome, open chromatin and DNA methylation maps. Second, cross-species analysis achieves a consensus taxonomy of transcriptomic types and their hierarchical organization that is conserved from mouse to marmoset and human. Third, in situ single-cell transcriptomics provides a spatially resolved cell-type atlas of the motor cortex. Fourth, cross-modal analysis provides compelling evidence for the transcriptomic, epigenomic and gene regulatory basis of neuronal phenotypes such as their physiological and anatomical properties, demonstrating the biological validity and genomic underpinning of neuron types. We further present an extensive genetic toolset for targeting glutamatergic neuron types towards linking their molecular and developmental identity to their circuit function. Together, our results establish a unifying and mechanistic framework of neuronal cell-type organization that integrates multi-layered molecular genetic and spatial information with multi-faceted phenotypic properties.

Advancing Planetary Health in Australia: focus on emerging infections and antimicrobial resistance

With rising population numbers, anthropogenic changes to our environment and unprecedented global connectivity, the World Economic Forum ranks the spread of infectious diseases second only to water crises in terms of potential global impact. Addressing the diverse challenges to human health and well-being in the 21st century requires an overarching focus on ‘Planetary Health’, with input from all sectors of government, non-governmental organisations, academic institutions and industry. To clarify and advance the Planetary Health agenda within Australia, specifically in relation to emerging infectious diseases (EID) and antimicrobial resistance (AMR), national experts and key stakeholders were invited to a facilitated workshop. EID themes identified included animal reservoirs, targeted surveillance, mechanisms of emergence and the role of unrecognised human vectors (the ‘invisible man’) in the spread of infection. Themes related to AMR included antimicrobial use in production and companion animals, antimicrobial stewardship, novel treatment approaches and education of professionals, politicians and the general public. Effective infection control strategies are important in both EID and AMR. We provide an overview of key discussion points, as well as important barriers identified and solutions proposed.

Changes in body weight and adiposity predict periodontitis progression in men

Most studies linking obesity and periodontal disease have been cross-sectional in design. We examined whether gains in body weight, waist circumference, and arm fat area are associated with periodontitis progression in 893 non-diabetic men followed for up to four decades in the prospective VA Dental Longitudinal Study. Probing pocket depth (PPD) was measured by calibrated examiners. Repeated-measures generalized linear models estimated the mean cumulative numbers of teeth with PPD events (PPD > 3 mm) at each dental examination and the slopes associated with increasing numbers of affected teeth over time. Means were adjusted for baseline PPD, education, and cigarette pack-years, and time-dependent values of age, mean plaque score, cigarette packs/day, brushing, and flossing. Men who were overweight at baseline and gained weight most rapidly (> 0.19 kg/yr or ~15 lb during follow-up) had significantly more PPD events than men in the lowest tertile of weight gain (≤ -0.05 kg/yr). Overweight men whose waist circumference increased > 0.14-0.39 or > 0.39 cm/yr experienced more PPD events than men in the lowest tertile (≤ 0.14 cm/yr). Increase in arm fat area was associated with disease progression in normal-weight men. These results suggest that tracking adiposity changes with easily obtained anthropometric measures may help predict risk of periodontitis progression.

Good governance in 'one health' approaches

The authors discuss 'One Health' approaches for controlling newly recognised and re-emerging diseases of animal origin and contributions towards pandemic preparedness based on enhanced collaboration between Veterinary Services, Human Health Services and Environmental Services. Improved veterinary governance and cooperation with public health managers, social scientists, ecologists and many other stakeholders are important for reducing the risks of potential zoonoses--including foodborne diseases--at their source. Two case studies are presented to illustrate how One Health approaches can make a difference--Hendra disease incidents in Australia and rabies management on the African continent. This article also includes an overview of collaboration at the international level between the Food and Agriculture Organization of the United Natiorfs, the World Organisation for Animal Health, and the World Health Organization. Environmental determinants for disease emergence, anthropogenic climate change and human encroachment on shrinking wildlife habitats are considered, using highly pathogenic avian influenza A (H5N1) and Nipah virus as examples. Finally, the authors discuss the effects of livestock production on environmental change--in the light of global population growth and increasing demand for livestock and aquaculture products--with the need for future policy decisions to be based on a multidisciplinary One Health approach.

NeuroAIDS in the Asia Pacific Region

Over 8.3 million people living in the Asia Pacific region are human immunodeficiency virus (HIV) positive and up to 40% of these individuals have had prior acquired immunodeficiency syndrome (AIDS) illnesses. Recently endeavors have been made to better characterize the burden of HIV-related neurological disease within the Asia Pacific region and, with this in mind, the NeuroAIDS in Asia and the Pacific Rim workshop was held in Sydney, Australia, as an affiliated event of the 4th IAS Conference on HIV Pathogenesis, Treatment and Prevention. The workshop was supported by the National Institute of Neurological Disorders and Stroke (NINDS) and the National Institute of Mental Health (NIMH) of the United States National Institutes of Health and the Australian Government overseas AID program, AusAID. HIV neurologists, infectious disease physicians, pediatricians, psychiatrists, immunologists, virologists,and researchers from 12 countries of the Asia Pacific region (including Australia), the United States, and the United Kingdom attended the meeting. A broad range of topics were addressed, including common HIV neurological disorders, the lack of diagnostic, management, and research infrastructure, central nervous system (CNS) immune restoration disease, pediatric neuroAIDS, and current clinical and laboratory research projects being undertaken within the Asia Pacific region.

Establishment of public health security in Saudi Arabia for the 2009 Hajj in response to pandemic influenza A H1N1

Mass gatherings of people challenge public health capacities at host locations and the visitors' places of origin. Hajj--the yearly pilgrimage by Muslims to Saudi Arabia--is one of the largest, most culturally and geographically diverse mass gatherings in the world. With the 2009 pandemic influenza A H1N1 and upcoming Hajj, the Saudi Arabian Ministry of Health (MoH) convened a preparedness consultation in June, 2009. Consultants from global public health agencies met in their official capacities with their Saudi Arabian counterparts. The MoH aimed to pool and share public health knowledge about mass gatherings, and review the country's preparedness plans, focusing on the prevention and control of pandemic influenza. This process resulted in several practical recommendations, many to be put into practice before the start of Hajj and the rest during Hajj. These preparedness plans should ensure the optimum provision of health services for pilgrims to Saudi Arabia, and minimum disease transmission on their return home. Review of the implementation of these recommendations and their effect will not only inform future mass gatherings in Saudi Arabia, but will also strengthen preparedness efforts in other settings.

Updated research nosology for HIV-associated neurocognitive disorders

In 1991, the AIDS Task Force of the American Academy of Neurology published nomenclature and research case definitions to guide the diagnosis of neurologic manifestations of HIV-1 infection. Now, 16 years later, the National Institute of Mental Health and the National Institute of Neurological Diseases and Stroke have charged a working group to critically review the adequacy and utility of these definitional criteria and to identify aspects that require updating. This report represents a majority view, and unanimity was not reached on all points. It reviews our collective experience with HIV-associated neurocognitive disorders (HAND), particularly since the advent of highly active antiretroviral treatment, and their definitional criteria; discusses the impact of comorbidities; and suggests inclusion of the term asymptomatic neurocognitive impairment to categorize individuals with subclinical impairment. An algorithm is proposed to assist in standardized diagnostic classification of HAND.

Reduction in caries rate among patients with xerostomia using a power toothbrush

The purpose of this study was to evaluate whether the use of a Sonicare toothbrush could be beneficial in reducing coronal and/or root caries among patients with medication-induced xerostomia. Eighty subjects with drug-induced xerostomia using either a Sonicare toothbrush (SC) or a manual toothbrush (MTB) were included in the study. Control subjects using a MTB were frequency-matched to 40 subjects using a SC, based on age, gender, number of teeth at baseline, and salivary flow rates. Subjects were individually matched according to the type of xerostomic medication they were taking. Caries were assessed at baseline, and subjects were instructed to have carious teeth restored. Summary statistics were assessed and computed by treatment group for incipient and frank coronal and root caries after one year. Statistical comparisons of the number of frank and incipient coronal and root caries between treatment groups were conducted using paired t-tests. After one year of use, the numbers of incipient and frank root caries were significantly lower among subjects using SC compared to subjects using MTB. Subjects using SC also exhibited somewhat lower incipient and frank coronal caries than subjects using MTB, although their differences were not statistically significant. The authors concluded that the Sonicare toothbrush may be beneficial in reducing root caries among older adults with medication-induced xerostomia.

Stimulation of salivary flow with a powered toothbrush in a xerostomic population

The purpose of this study was to determine if using a Sonicare toothbrush was a beneficial treatment of xerostomia. Sixty-one subjects with medication-induced xerostomia were randomly assigned a Sonicare (SC) or manual toothbrush (MTB). Subjects were followed for four visits (one month apart); after two months, the MTB group crossed over to using a SC. At each visit, saliva flow was measured by subjects expectorating for five minutes at four collection periods. For the first sample subjects were asked to spit while brushing for three minutes and for two minutes after brushing. Five-minute saliva collections were taken at 15-, 30- and 45-minute intervals. Questionnaires were administered at the end of the study period and three years later. Paired analysis on the MTB group that crossed over to SC showed significant increase in salivary flow at all post-brushing collections (p < 0.01). The end-of-study questionnaire showed that 96.4% of subjects found the SC comfortable to use, 98.2% had enhanced salivary flow, and 92.7% would use it to increase salivary flow. After three years, subjects rated the cleaning effect of the SC more than 4.5 (where 5 = excellent). The Sonicare toothbrush may help in the treatment of xerostomia. The use of a Sonicare resulted in a statistically significant increase in post-brushing salivary flow rates in persons with medcation-induced xerostomia.

Reliability of sprint test indices in well-trained cyclists

The study aim was to assess reliability of repeated laboratory sprint tests in well-trained endurance cyclists. Eleven male cyclists (mean +/- standard deviation: 27 +/- 6 yr, 1.79 +/- 0.04 m, 70.1 +/- 3.3 kg) performed a maximal 30-second sprint test on four separate occasions using their own bicycle fitted with an SRM powermeter on a Kingcycle air-braked ergometer. Peak power output (W (peak)), mean power (W (mean)) and an index of fatigue (FI) were calculated. Three minutes post sprint, capillarised blood lactate measurements were taken and analysed. No significant differences (p > 0.05) were found between trials for W (peak), W (mean), FI and blood lactate concentration. Repeatability of W (peak), W (mean), and fatigue index improved across trials 2 and 3 when compared to trials 1 and 2. The highest CV for these variables was recorded between trials 3 and 4. The CV for W (peak) was 4.5 +/- 1.6 %, W (mean) 2.4 +/- 1.2 %, and FI 17.2 +/- 7.1 %. Intraclass reliability coefficients were 0.93 (95 % CI 0.84 - 0.98), 0.94 (95 % CI 0.86 - 0.98) and 0.89 (95 % CI 0.69 - 0.95) respectively. Blood lactate concentration ranged between 5.35 and 14.52 mmol.l(-1), with a mean CV of 12.1 +/- 4.2 %. The CV for trials 2 and 3 revealed the highest CV for blood lactate concentration (15.1 %). The lowest CV for this variable (10.2 %) was recorded between trials 3 and 4. The intraclass reliability coefficient for blood lactate concentration was 0.79 (95 % CI 0.58 - 0.93). The results of this study indicate that there is no improvement in the reliability of sprint test indices when assessing well-trained, experienced cyclists, riding on their own cycle equipment.

Calcification of the interclinoid and petroclinoid ligaments of sella turcica: a radiographic study of the prevalence

OBJECTIVES

The purpose of this study was to evaluate the prevalence of calcifications of the sella turcica, in particular, calcification of the interclinoid and petroclinoid ligaments (PCL).

DESIGN

Radiographic analysis of preoperative cephalometric film images.

SETTING AND SAMPLE POPULATION

Lateral cephlometric radiographs of 255 subjects presenting for orthodontic evaluation were reviewed. The number of subjects selected for this study was determined by power analysis.

EXPERIMENTAL VARIABLE

Two calibrated raters reviewed cephalometric projections and scored the films using a standardized rating scale.

OUTCOME MEASURE

The rating scale classified interclinoid ligaments (ICL) into one of four categories depending on the degree of calcification and PCLs as either, no calcification, partial or complete calcification.

RESULTS

Of all subjects, calcification of the ICL ranged from 39% rated as more than half calcified to 8% completely calcified. Petroclinoid analysis revealed 67% with no calcification, 23% with partial calcification and 9% completely calcified. Spearman's correlations were computed between age and the degree of calcification and between the degree of calcification for these two ligaments with a significant association between age and degree of calcification in the PCL, r = 0.185 (p = 0.003) and a significant association between the degree of calcification in the petroclinoid and ICLs, r = 0.186 (p = 0.003). In addition, chi-squared tests demonstrated statistically significant associations between the presence of calcification in the PCL to the distribution of age (p = 0.041) and between the presence of calcification in the ICL to the distribution of age (p = 0.045).

CONCLUSION

As calcification of these ligaments has suggestive associations with disease entities, their recognition as a variant of normal anatomy should be evaluated when assessing cephalometric radiographs.

Striatal size and relative glucose metabolic rate in schizotypal personality disorder and schizophrenia

BACKGROUND

Schizotypal personality disorder (SPD) shares social deficits and cognitive impairment with schizophrenia, but is not typically characterized by frank psychosis. Because striatal size and functional activity have both been shown to be associated with psychotic symptoms, we carried out the first study of SPD to assess the caudate and putamen for comparison with findings in schizophrenia.

METHODS

Patients with SPD (n = 16), schizophrenic patients (n = 42), and age- and sex-matched normal control subjects (n = 47) were assessed with magnetic resonance imaging. All of the patients with SPD and subsamples of the schizophrenic patients (n = 27) and control subjects (n = 32) were also assessed with positron emission tomography using fluorodeoxyglucose F-18.

RESULTS

The relative size of the putamen in controls was significantly larger than in patients with SPD and significantly smaller than in schizophrenic patients, while the relative size of the caudate was similar in all 3 groups. Compared with control values, relative glucose metabolic rate in the ventral putamen was significantly elevated in patients with SPD and reduced in schizophrenic patients. When subsamples of schizophrenic patients (n = 10) and patients with SPD (n = 10) both of whom never received medication were compared, this pattern was more marked, with the highest value for the putamen being found in patients with SPD for the ventral slice and the lowest value for the right dorsal putamen.

CONCLUSIONS

Patients with SPD showed reduced volume and elevated relative glucose metabolic rate of the putamen compared with both schizophrenic patients and controls. These alterations in volume and activity may be related to the sparing of patients with SPD from frank psychosis.

Temporal lobe volume determined by magnetic resonance imaging in schizotypal personality disorder and schizophrenia

The volumes of the whole temporal lobe, the superior temporal gyrus and the corpus callosum were measured on magnetic resonance images from 13 patients with schizotypal personality disorder (SPD), 27 patients with schizophrenia, and 31 age- and sex-matched controls. Temporal lobe structures were traced on consecutive 1.2mm thick SPGR images. Both patient groups had smaller temporal lobes than normal volunteers, a difference that was more marked for the area outside the superior temporal gyrus than for the STG. Correcting for brain volume diminished differences between normal subjects and schizophrenia patients, but the differences between normal subjects and SPD patients remained. Normal volunteers and SPD patients showed significant correlations between the sagittal section area of the posterior portion of the corpus callosum, which carries temporal interhemispheric connections, and the white matter volume of the temporal lobe. While the sample size is modest, taken together, these results suggest that the psychopathological symptoms of SPD may be related to temporal gray matter loss with relatively intact white matter connectivity, while the cognitive and psychotic symptoms of schizophrenia may be related to temporal gray loss combined with disruption of normal patterns of white matter development.

Physostigmine and cognition in schizotypal personality disorder

There is evidence that reduced cholinergic activity may play a role in the pathophysiology of cognitive impairment in the schizophrenia spectrum. We tested the effects of physostigmine, an anticholinesterase inhibitor, on visuospatial working memory as evaluated by the Dot test, and on verbal learning and recall as measured by a serial learning task in patients with schizotypal personality disorder. Physostigmine tended to improve the Dot test, but not serial verbal learning performance in these patients.

Influenza surveillance in England and Wales: October 1999 to May 2000

The period of increased influenza activity in England and Wales in the winter of 1999/2000 was associated with considerable morbidity and mortality and well-publicized pressure on hospital services. The influenza activity coincided with the regular annual increase in respiratory syncytial virus infections and the Christmas and New Year holiday period. Consultation rates with general practitioners for influenza-like illness did not reach 'epidemic' levels but were higher than seen in many winters and comparable with those seen in two out of the previous three winters. In common with those winters, attack rates for influenza-like illness and acute bronchitis were especially high in elderly people among whom complications of acute infection and hospital admissions increased. Excess mortality due to influenza during this period appeared to be substantial but was not as high as seen in the last epidemic (1989/90).

Assessment of blood lactate: practical evaluation of the Biosen 5030 lactate analyzer

PURPOSE

The aim of this study was to assess the validity and reliability of the Biosen 5030 lactate analyzer compared with a YSI 2300 lactate analyzer and a Kodak Ektachem DTII in a practical laboratory study context.

METHODS

To assess validity, 144 triplicate capillarized blood samples, across a range of values, were analyzed using the three analyzers. To assess reliability a further 665 samples were repeat analyzed. Temporal stability was determined by the reanalysis of resting and maximal exercise blood samples, after a period of storage ranging from 7 to 20 h, at room temperature. To measure inter- and intra-investigator reliability, 20 resting samples were taken from three different subjects by different investigators and a coefficient of variation was determined.

RESULTS

There were strong relationships between the Biosen, the YSI (r2 = 0.97), and the Kodak Ektachem (r2 = 0.91). An analysis of Biosen compared with YSI revealed a positive bias of 0.37 mmol x L(-1) (95% limits of agreement, -0.85 to 1.59 mmol x L(-1)). The test-retest reliability correlation was significant (r2 = 0.99, P < 0.05), but a paired t-test revealed a small (0.03 mmol x L(-1), P < 0.05) significant difference. The coefficient of variation from the three investigators across the 20 samples ranged from 1.3 to 3%. Blood lactate concentration in resting blood samples did significantly increase in value (0.2 mmol x L(-1), P < 0.05) after 7-h exposure to the air, whereas there was no change in maximal exercise blood lactate values after 20-h exposure to the air.

CONCLUSIONS

In a practical context, the Biosen 5030 lactate analyzer was comparable to the other analyzers giving fast reliable measures of blood lactate concentrations over the full range of values, which remained stable over extended periods at room temperature.

Effects of amphetamine on visuospatial working memory performance in schizophrenia spectrum personality disorder

Our objective was to determine if amphetamine improves visuospatial working memory, which is impaired in the schizophrenia spectrum and may be modulated by dopamine in prefrontal cortex. To this end, oral amphetamine (30 mg) was administered to 12 patients with schizophrenia spectrum personality disorders and 13 patients with other, nonschizophrenia-related personality disorders. Visuospatial working memory was assessed using the Dot test; a test in which subjects are asked to memorize and reproduce the position of a dot on a sheet of paper. Patients with schizophrenia spectrum personality disorders performed significantly worse than the comparison group in the placebo condition and showed significantly greater improvement after amphetamine, as compared to a nonschizophrenia-related personality disorder comparison group. Patients with greatest impairment at baseline improved most. Amphetamine tended to improve negative symptoms; whereas, positive symptoms remained unchanged. Amphetamine may improve visuospatial working memory in schizophrenia spectrum patients.

Influenza activity in England and Wales: October 1998 to June 1999

Influenza activity in England and Wales in the winter of 1998/1999 reached the highest weekly levels seen since the epidemic of 1989/1990. Activity peaked at Christmas and the New Year, adding to the winter pressures on general practitioner and hospital services. Adults aged 65 years and over consulted with general practitioners at the highest rates. Outbreaks of influenza or flu-like illness occurred in several schools and nursing homes and, in June 1999, on a British cruise ship in the Mediterranean. Deaths from all causes reached a higher peak in week 1 of 1999 than occurred in the peak week of the influenza epidemic of 1989/90.

Association between periodontitis and hyperlipidemia: cause or effect?

BACKGROUND

Epidemiological studies suggest a relationship between periodontitis and coronary artery disease, but the mechanism has not been established. Recent studies in animals indicate that low dose endotoxin, as in a gram-negative infection, can induce hyperlipidemia and myeloid cell hyperactivity. The association between periodontitis, systemic exposure to Porphyromonas gingivalis, lipopolysaccharides (LPS), and hyperlipidemia has not been examined in humans.

METHODS

Sera were obtained from 26 adult periodontitis patients and 25 healthy control (C) subjects selected from patients and staff. Serum antibodies against Porphyromonas gingivalis and its LPS were analyzed by enzyme-linked immunosorbent assay (ELISA) and Western blotting, respectively. Serum triglycerides (TG) and cholesterol (CHOL) were assayed by a commercial laboratory. The associations between AP and blood levels of TG, CHOL, and anti-P. gingivalis whole cells and LPS were examined by logistic regression analysis. Peripheral blood polymorphonuclear leukocytes (PMNs) from 6 healthy fasted donors were incubated with purified TG (0.1 mg/ml) for 2 hours at 37 degrees C, stimulated with 100 ng/ml P. gingivalis LPS, and the release of IL-1beta measured by ELISA.

RESULTS

The presence of periodontitis was significantly associated with age (odds ratio = 3.5, P = 0.04), elevated TG levels (odds ratio = 8.6, P = 0.0009), elevated CHOL levels (odds ratio = 7, P = 0.004), elevated ELISA titer (odds ratio = 35, P = 0.003) and reactivity with P. gingivalis LPS (odds ratio = 41, P = 0.001). PMNs from all 6 healthy patients released modest levels of IL-1beta (10 to 60 pg/ml) when stimulated with 100 ng/ml P. gingivalis LPS. Addition of TG resulted in a significant increase (P <0.05) in IL- 1beta secreted that ranged from 7 to 150% over LPS alone. No IL-1beta was elicited by TG or vehicle alone.

CONCLUSIONS

The results of this study indicate the presence of a significant relationship between periodontitis, hyperlipidemia, and serum antibodies against P. gingivalis LPS that warrants further examination in a larger patient population. Furthermore, these studies indicate that elevated triglycerides are able to modulate IL-1beta production by PMNs stimulated with P. gingivalis LPS.

The relationship between the interleukin-1 periodontal genotype and implant loss. Initial data

BACKGROUND

This study investigated the relationship of the interleukin-1 (IL-1) genotype, smoking status, and the patient's age to the survival of osseointegrated dental implants.

METHODS

Twenty-seven patients with 33 implants that had been lost or who had at least 50% bone loss on radiographs were compared to a group of 38 patients who had experienced no bone or implant loss. All lost implants in a private practice were included in the data, except those that had fractured with no previous bone loss.

RESULTS

Smoking was demonstrated to increase the risk of implant failure by a factor of almost 2.5.

CONCLUSIONS

Statistical testing failed to provide evidence of an increased risk for implant failure for patients who are positive for the IL-1 genotype. There was no apparent relationship between the patient's age at the time of placement and implant loss. This study raises several questions concerning the etiology of implant loss and the comparative biology of tissues surrounding implants when compared to those surrounding natural teeth.

d,l-fenfluramine response in impulsive personality disorder assessed with [18F]fluorodeoxyglucose positron emission tomography

Reduced serotonergic activity has been associated with impulsive aggression in personality disordered patients in metabolite and pharmacologic challenge studies. This study used positron emission tomography to explore whether reduced serotonergic function occurs in critical brain regions such as orbital frontal and cingulate cortex that, may play a role in modulating aggression. Six impulsive-aggressive patients and five healthy volunteers were evaluated for changes in regional glucose metabolism after administration of the serotonergic releasing agent d,l-fenfluramine (60 mg, p.o.) or placebo. Volunteers demonstrated increases in orbital frontal and adjacent ventral medial frontal cortex, cingulate, and inferior parietal cortex, whereas impulsive-aggressive patients showed no significant increases in glucose metabolism after fenfluramine in any region. Compared with volunteers, patients showed significantly blunted metabolic responses in orbital frontal, adjacent ventral medial and cingulate cortex, but not in inferior parietal lobe. These results are consistent with reduced serotonergic modulation of orbital frontal, ventral medial frontal, and cingulate cortex in patients with impulsive-aggressive personality disorders.

Effectiveness of a sonic toothbrush in maintenance of dental implants. A prospective study

This study assessed the efficacy of a sonic and a manual toothbrush in reducing plaque and gingivitis around dental implants. Subjects were randomly assigned to either sonic (n = 16) or manual (n = 15) study groups. Groups were balanced according to baseline levels of plaque and gingivitis. The plaque (PI), gingival (GI), and bleeding (BI) indices as well as probing depths were determined at baseline, and at 4, 8, 12, and 24 week follow-up visits. Mean scores per person were calculated for each clinical parameter. Oral hygiene habits, compliance and acceptance were also evaluated over the study period. Within group comparisons from baseline throughout the study, as well as between group comparisons (i.e., sonic versus manual), were determined. Overall, plaque, gingival, and bleeding indices in both groups were lower at each follow-up visit when compared to the baseline. Within group comparisons demonstrated that both the sonic toothbrush subjects and the manual toothbrush subjects had significantly lower PI, GI, and BI scores at each post-baseline visit (4, 8, 12, and 24 weeks) than at baseline (p<0.005). In addition, the sonic toothbrush subjects also had significantly lower probing depths at each post-baseline visit than at baseline (p < 0.005). Between group comparisons demonstrated that the sonic toothbrush subjects over time had significantly lower PI and BI scores around dental implants than the manual toothbrush subjects (Repeated measures MANOVA; PI, p = 0.01; BI, p = 0.017). The sonic toothbrush subjects had lower GI scores and reduced probing depths over time when compared to manual toothbrush subjects but these scores were not statistically significant (GI; probing depth, p > 0.05). No implant problems (e.g., loose screws) were attributable to the sonic toothbrush. Relevant to oral hygiene habits, subjects in both groups demonstrated a high level of compliance with their assigned toothbrush. Overall, the results of this study demonstrated that sonic toothbrushing significantly reduced plaque, gingival inflammation and bleeding, and probing pocket depths around implants over the 6-month trial period. It is concluded that sonic brushing is an effective means of dental implant maintenance.

Tetracycline fibers plus scaling and root planing versus scaling and root planing alone: similar results after 5 years

This paper presents 5-year data pertaining to a subgroup of patients from a previous investigation who were treated with scaling and root planing plus tetracycline fibers. The parent study demonstrated that 6 months after therapy, scaling and root planing plus tetracycline fiber therapy was significantly better at reducing probing depth and gaining clinical attachment than scaling and root planing alone. However, the long-term data presented here show a regression from the original gains in clinical attachment levels in the fiber group. Ultimately, the use of fibers provided no significant advantage with regards to probing depth reduction or clinical attachment gain. Within the power of this study, which would have required 1.78 mm of change in clinical attachment to show a difference, there was no significant difference between the treatments at 5 years. This study underscores the need for additional long-term evaluation of this mode of therapy.

The effect of directly observed therapy on the rates of drug resistance and relapse in tuberculosis

BACKGROUND

Tuberculosis has reemerged as an important public health problem, and the frequency of drug resistance is increasing. A major reason for the development of resistant infections and relapse is poor compliance with medical regimens. In Tarrant County, Texas, we initiated a program of universal directly observed treatment for tuberculosis. We report the effect of the program on the rates of primary and acquired drug resistance and relapse among patients with tuberculosis.

METHODS

We collected information on all patients with positive cultures for Mycobacterium tuberculosis in Tarrant County from January 1, 1980, through December 31, 1992. Through October 1986, patients received a traditional, unsupervised drug regimen. Beginning in November 1986, nearly all patients received therapy under direct observation by health care personnel.

RESULTS

A total of 407 episodes in which patients received traditional treatment for tuberculosis (January 1980 through October 1986) were compared with 581 episodes in which therapy was directly observed (November 1986 through December 1992). Despite higher rates of intravenous drug use and homelessness and an increasing rate of tuberculosis during this 13-year period, the frequency of primary drug resistance decreased from 13.0 percent to 6.7 percent (P < 0.001) after the institution of direct observation of therapy, and the frequency of acquired resistance declined from 14.0 percent to 2.1 percent (P < 0.001). The relapse rate decreased from 20.9 percent to 5.5 percent (P < 0.001), and the number of relapses with multidrug-resistant organisms decreased from 25 to 5 (P < 0.001).

CONCLUSIONS

The administration of therapy for M. tuberculosis infection under direct observation leads to significant reductions in the frequency of primary drug resistance, acquired drug resistance, and relapse.

Detection of amplified HTLV-I/-II viral sequences using time-resolved fluorometry

Since its discovery, the polymerase chain reaction (PCR) has been used for different purposes in the field of DNA research. We tested the PCR for the diagnosis of HTLV-I/-II infections. PCR was used to amplify 141- and 149-base pair regions from the HTLV-I and HTLV-II virus genomes, respectively. The annealing temperature in the PCR amplification was optimized using 20% polyacrylamide gels and silver staining. Even a slight change (3 degrees C) in the annealing temperature had an effect on the specificity of the reaction. The PCR products were detected with biotin and Eu-labeled oligonucleotide probes in a solution hybridization format. The linearity of the assay was tested with serial dilutions of purified chromosomal DNA containing integrated HTLV-II sequences. The linearity was found to be dependent on the number of cycles used in the PCR amplification. The best linearity, at a target level of a few copies, was achieved using a low number of cycles. The specificity of the assay was tested using HTLV-I and HTLV-II-infected lymphocytes from the cell lines Hut102 and MO480, respectively. No cross reactivity between these analytes was observed.

Nucleotide sequence and expression of the human gene encoding apolipoprotein H (beta 2-glycoprotein I)

Human apolipoprotein H (ApoH), also called beta 2-glycoprotein I, is a 50-kDa serum glycoprotein whose function is not clearly defined. We have cloned and sequenced ApoH cDNAs both from human liver and from a human hepatoma cell line (HepG2). Both cDNA sequences predict a protein 345 amino acids (aa) in length. This sequence includes a 19-aa hydrophobic, N-terminal signal sequence which is not present in the mature protein [Lozier et al., Proc. Natl. Acad. Sci. USA 81 (1984) 3640-3644]. It differs from this previously reported aa sequence at two positions, both of which strengthen the conservation among the four short consensus repeats within the ApoH molecule. COS-1 cells transiently transfected with the ApoH cDNA in a eukaryotic expression vector produced a single species of ApoH mRNA and secreted in the ApoH protein. The level of ApoH mRNA expressed by HepG2 cells is downregulated by incubation with inflammatory mediators, implying that ApoH is a negative acute-phase protein.

New sensitive and specific assay for human immunodeficiency virus antibodies using labeled recombinant fusion protein and time-resolved fluoroimmunoassay

A new, rapid method for the detection of human immunodeficiency virus type 1 (HIV-1) antibody by time-resolved fluoroimmunoassay (TR-FIA) was developed. In this assay format, microtitration strips were coated with a recombinant fusion protein, and the same protein was labeled with europium and added into the wells simultaneously with the test specimens. The recombinant fusion protein contained the HIV-1 p24 gag protein sequence that carried an insertion, near the carboxyl terminus, of a 23-amino-acid sequence from a highly conserved region of the HIV-1 gp41 envelope protein. This recombinant antigen enabled the detection of antibodies to both gag and env gene products. When this assay was compared with a commercially available recombinant enzyme-linked immunoabsorbent assay (ELISA) by using four quality-control panels, the TR-FIA detected all 20 positive specimens, while the recombinant ELISA detected only 16 of them. This increased sensitivity could be demonstrated directly by the assay of dilution series of HIV-1-positive sera. The analysis of two seroconversion panels by TR-FIA and six ELISAs showed that TR-FIA allowed detection of antibody in infected individuals 16 days earlier than the other assays did. In addition to being highly sensitive, the assay was highly specific; of the 57 samples shown to be repeatedly positive by ELISA but known to be HIV-1 negative by Western immunoblot analysis, only 1 sample reacted positively in this assay. The specificity of the assay was 99.9% when 1.054 random serum specimens were tested.

Peptide mapping on HIV polypeptides expressed in Escherichia coli. Quality control of different batches and identification of tryptic fragments containing residues of aromatic amino acids or cysteine

Peptide mapping was used for the quality control of different batches of the recombinant HIV proteins p24 core and p24-gp41, expressed in Escherichia coli. These proteins comprise gag and env region polypeptides of the virus and may serve as suitable components in the diagnosis of HIV infections. The proteins were digested with trypsin and the mixtures were subjected to peptide mapping to prove batch equivalence of p24-gp41 and to isolate fragments of the p24-gp41 digest that differ from those of the p24 core digest. The proteins were reduced with dithiothreitol and the cysteine residues were derivatized by addition of 4-vinylpyridine. Peptide mapping was performed by means of reversed-phase high-performance liquid chromatography. Batch equivalence was proved by comparison of the maps. Peaks present in one map but not in the other were considered to be due to sequence differences or variability in digestion.

Avian erythroblastosis virus E26: nucleotide sequence of the tripartite onc gene and of the LTR, and analysis of the cellular prototype of the viral ets sequence

An intact 5.7-kb provirus of the avian erythroblastosis virus E26 has been molecularly cloned for comparisons with avian myeloblastosis virus (AMV) and other avian tumor viruses. E26 and AMV transform hemopoietic cells exclusively. Both cause myeloblastosis, but E26 also causes erythroblastosis. Sequence analysis of the proviral DNA showed that: The tripartite transforming gene of E26 forms a contiguous reading frame of 1046 codons, including 272 gag, 283 mybE, and 491 ets codons. No subgenomic ets-specific mRNA was detected in E26-infected cells. By contrast, the onc gene of AMV consists almost entirely of a mybA sequence expressed via subgenomic mRNA that extends over the 5' and 3' ends of mybE. mybE is only slightly diverged from the mybA homolog of AMV and even less from the cellular proto-myb sequence with no characteristic mutation that sets apart the two viruses from proto-myb. The U5 region of the long terminal repeat (LTR) of E26 and AMV are colinear and differ only in scattered point mutations. The U3 region of the E26 LTR is different from that of AMV but is colinear and closely related with that of avian carcinoma virus MH2 and also with that of Prague Rous sarcoma virus (RSV), except for an unexpected 16-nucleotide substitution of 22 RSV nucleotides. Upstream of the 3' LTR, the c region of E26 appears to be the same as that of RSV for 70 nucleotides and very similar to those of AMV and MH2 for about 20 to 30 nucleotides. Since the U3s of E26, MH2 and RSV are very closely related and neither MH2 nor RSV show a particular erythroblast tropism, it is possible that the U3 does not play a critical role in the erythroblast tropism of E26. Electrophoretic size analyses of chicken DNA digested with restriction enzymes indicate that DNA fragments totaling over 50 kb hybridize with viral ets DNA.

Complete env gene deletions of three replication-defective strains of Rous sarcoma virus and a model for the origin of their genetic structures

Replication-defective deletion mutants of Rous sarcoma virus (RSV) have been described which transform cells in culture and elaborate envelope (-) defective particles. The env deletions of two clonal variants of the Bryan strain of RSV, RSV(-)3, and RSV(-)16, and of a replication-defective variant of Schmidt-Ruppin RSV (SRN8) were analyzed by fingerprinting oligonucleotides hybridized by a molecularly cloned env DNA probe that spans from near the 3' end of pol to the 3' end of env. It was observed that all three replication-defective RSV strains are essentially complete env deletions but retain the 3' end of pol. Based on a common pol-src junction oligonucleotide that may reflect a homologous sequence repeated at both ends of env in nondefective RSV, the env deletions of RSV(-)3 and 16 appear to be isogenic. The original deletion may have involved recombination between these sequences. The absence of this oligonucleotide in SRN8 indicates that the env deletion of SRN8 has different borders and represents an independent env deletion of nondefective RSV. All three defective RSVs have the genetic structure gag-pol-src. This genetic structure is consistent with the need for a complete gag to make a particle and with the assumption that an independent src gene rather than a gag- or gag-pol-src hybrid gene functions in transformation. It is suggested that a complete pol is not necessary for, but may assist, virus particle formation.