Spatial Sequencing: A Perspective

Fluorescent spatial sequencing brings next-generation sequencing into a new realm capable of identifying nucleic acids in the cell's natural environment. For the first time, scientists are able to multiplex the assignment of specific locations to hundreds of transcriptional targets and lay the foundation for understanding how genetic changes control the fate of each cell within the tissue microenvironment. In this perspective, we discuss the capabilities of fluorescent spatial sequencing in the context of other spatial imaging technologies and describe how these new technologies offer a data-rich, multiomic solution to many research applications. Fluorescent spatial sequencing has opened options for exploring many fundamental questions in biology, helping us gain a better understanding of cell and tissue development and disease progression.

H3K27me3-mediated silencing of structural genes is required for zebrafish heart regeneration

Deciphering the genetic and epigenetic regulation of cardiomyocyte proliferation in organisms that are capable of robust cardiac renewal, such as zebrafish, represents an attractive inroad towards regenerating the human heart. Using integrated high-throughput transcriptional and chromatin analyses, we have identified a strong association between H3K27me3 deposition and reduced sarcomere and cytoskeletal gene expression in proliferative cardiomyocytes following cardiac injury in zebrafish. To move beyond an association, we generated an inducible transgenic strain expressing a mutant version of histone 3, H3.3K27M, that inhibits H3K27me3 catalysis in cardiomyocytes during the regenerative window. Hearts comprising H3.3K27M-expressing cardiomyocytes fail to regenerate, with wound edge cells showing heightened expression of structural genes and prominent sarcomeres. Although cell cycle re-entry was unperturbed, cytokinesis and wound invasion were significantly compromised. Collectively, our study identifies H3K27me3-mediated silencing of structural genes as requisite for zebrafish heart regeneration and suggests that repression of similar structural components in the border zone of an infarcted human heart might improve its regenerative capacity.

Deep learning using tumor HLA peptide mass spectrometry datasets improves neoantigen identification

Neoantigens, which are expressed on tumor cells, are one of the main targets of an effective antitumor T-cell response. Cancer immunotherapies to target neoantigens are of growing interest and are in early human trials, but methods to identify neoantigens either require invasive or difficult-to-obtain clinical specimens, require the screening of hundreds to thousands of synthetic peptides or tandem minigenes, or are only relevant to specific human leukocyte antigen (HLA) alleles. We apply deep learning to a large (N = 74 patients) HLA peptide and genomic dataset from various human tumors to create a computational model of antigen presentation for neoantigen prediction. We show that our model, named EDGE, increases the positive predictive value of HLA antigen prediction by up to ninefold. We apply EDGE to enable identification of neoantigens and neoantigen-reactive T cells using routine clinical specimens and small numbers of synthetic peptides for most common HLA alleles. EDGE could enable an improved ability to develop neoantigen-targeted immunotherapies for cancer patients.

Evidence of Ebola Virus Replication and High Concentration in Semen of a Patient During Recovery

In one patient over time, we found that concentration of Ebola virus RNA in semen during recovery is remarkably higher than blood at peak illness. Virus in semen is replication-competent with no change in viral genome over time. Presence of sense RNA suggests replication in cells present in semen.

Practitioner evaluation of an online oral health and risk assessment tool for young patients

Aim To test the validity and acceptability of an online oral health assessment and biofeedback tool for young patients (under 17) for use in general dental practice.Methods A convenience sample of thirteen practitioners were recruited to test the functionality of a novel version of the Denplan PreViser Patient Assessment tool (DEPPA) developed for young patients (YDEPPA). Dentists who had completed eight or more assessments during a one month window were sent a link to an online feedback survey, comprising eight statements about YDEPPA, with scoring options of 0-10, where a score of 10 indicated complete agreement with the relevant questions. Verbatim comments were encouraged. The clinical data submitted were held in a central database in an encrypted format so that only the user practice could identify individual patients.Results Twelve practitioners completed eight or more assessments and were included in the survey. A total of 175 patient assessments were received. Ten practitioners completed the on-line survey. The statement 'YDEPPA produces a valid measurement of each patient's oral health' received an average feedback score of 8.8. The statement 'The full YDEPPA report is a valuable communication aid' received a score of 9.6. Feedback was generally very positive with all scores >8.2. Constructive critical feedback was received for the caries risk aspect of the YDEPPA protocol, with suggestions made for improving objectivity of data inputs. Eighty-one percent of the verbatim comments received were positive.Conclusions Once the caries risk issues raised by pilot dentists have been addressed, YDEPPA appears suitable as a pragmatic analytical and biofeedback tool for use in general dental practice to assess the oral health of young patients, and to facilitate education and engagement of young patients and their parents/carers in positive health behaviours.

Abstract 629: An integrated genomic and proteomic analysis of human tumors reveals key factors in neoantigen identification and enables epitope prediction for cancer immunotherapy

Background: Immunotherapy has become essential in the treatment of advanced cancer, with the advent of drug approvals in multiple indications and functional cures for a minority of patients. However, overall survival gains from immunotherapy have been limited and substantial progress remains. The discovery of tumor-specific neoantigens as principal targets of T cells unleashed by immune checkpoint blockade was a key breakthrough in immunotherapy research. Although example neoantigens have been reported, the impact of genomic features on HLA presentation and neoantigen identification has not been comprehensively assessed. Moreover, in silico methods for predicting which mutations lead to neoantigens are currently inadequate for most therapeutic applications, with a false positive rate of >95%.

Methods: We performed deep tumor/normal exome sequencing (Illumina-based, average unique depth 557x/149x), tumor transcriptome sequencing (avg. 111M unique reads), and mass spec HLA class I peptide sequencing (Thermo Lumos, avg. 3,482 peptides) on fresh-frozen primary tumor specimens from 23 patients (22 NSCLC, 1 OC). Somatic mutations were called with a custom GATK-based pipeline, gene expression assessed with RSEM, and peptides matched to mass spectra using COMET/Percolator. We examined the effect of NGS parameters on neoantigen identification, analyzed HLA presentation as a function of genomic features, and created a novel deep learning model for epitope prediction.

Results: We identified 6,252 nonsynonymous somatic mutations across the cohort (avg. 272 per patient) and found 3,874 (62%) transcribed in mRNA. Down-sampling tumor DNA NGS data to a more typical average unique coverage of ~200x and RNA to ~60M reads revealed 3,275 transcribed mutations, an overall 15% loss of candidate neoantigens and >25% loss in low tumor content samples, demonstrating the importance of sequencing depth. Gene expression measurement at the RNA level predicted HLA presentation more strongly than expected, with peptides from genes detected in RNA found presented >20X more often than peptides from non-detected genes. With this and public datasets we trained a model to predict HLA presentation and compared it to standard binding affinity prediction (e.g., NetMHC or MHCflurry) at the strong-binder 50nM threshold for well-characterized alleles. Whereas binding affinity-based prediction gave a positive predictive value (PPV) of only 3%, our integrated deep learning approach showed a PPV of >25% at equivalent recall, a near ten-fold gain.

Conclusions: A novel genomic and proteomic analysis of human tumors establishes NGS requirements for neoantigen identification, characterizes key correlates of HLA presentation, and enables prediction for personalized cancer immunotherapy research.

Citation Format: Brendan Bulik-Sullivan, Jennifer Busby, Matthew Davis, Andrew Clark, Tyler Murphy, Michele Busby, Fujiko Duke, Jessica Smith, Jason Hudak, Adnan Derti, Josh Francis, Roman Yelensky. An integrated genomic and proteomic analysis of human tumors reveals key factors in neoantigen identification and enables epitope prediction for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 629. doi:10.1158/1538-7445.AM2017-629

Is any particular aspect of perceived quality associated with patients tending to promote a dental practice to their friends and colleagues?

AIMS

To investigate the relationship between perceived quality and patients' tendencies to recommend a practice to friends and colleagues.

METHODS

Data from 64 practices using the Denplan Excel Patient Survey (DEPS) were analysed. The Net Promoter Score (NPS max score 100), developed by Reichheld, is reported to each practice using DEPS. It is claimed that the NPS measures the likelihood that patients will recommend the practice to friends and colleagues. A Patient Perception Index (PPI max score 100) is also reported to practices. The PPI is calculated from the responses to the ten core questions of DEPS on perceived quality. The 64 practices were placed into three groups for data analysis according to their NPS result: group one practices receiving an NPS of less than 80, group two practices receiving an NPS of 80-89 and group three practices receiving an NPS of greater than 89. These groups represented practices scoring statistically significantly (to 90% confidence) below the mean NPS (group one), practices close to the mean NPS (group two) and practices statistically significantly (to 90% confidence) above the mean NPS.

RESULTS

Group one practices scored a mean PPI of 73, group two scored a mean PPI of 76 and group three a mean PPI of 80. These differences in values of PPI between the groups are statistically significant (to 90% confidence). Of the ten constituent issues which contribute to PPI, the greatest difference in scoring between group one and group three was found to be around perceived value for money.

CONCLUSION

The probability of patients recommending a dental practice seems to rise in direct proportion to favourable perceptions of quality. A perception of 'ideal' value for money is the most highly correlated aspect with a high NPS.

Systematic comparison of monoclonal versus polyclonal antibodies for mapping histone modifications by ChIP-seq

Background

The robustness of ChIP-seq datasets is highly dependent upon the antibodies used. Currently, polyclonal antibodies are the standard despite several limitations: They are non-renewable, vary in performance between lots and need to be validated with each new lot. In contrast, monoclonal antibody lots are renewable and provide consistent performance. To increase ChIP-seq standardization, we investigated whether monoclonal antibodies could replace polyclonal antibodies. We compared monoclonal antibodies that target five key histone modifications (H3K4me1, H3K4me3, H3K9me3, H3K27ac and H3K27me3) to their polyclonal counterparts in both human and mouse cells.

Results

Overall performance was highly similar for four monoclonal/polyclonal pairs, including when we used two distinct lots of the same monoclonal antibody. In contrast, the binding patterns for H3K27ac differed substantially between polyclonal and monoclonal antibodies. However, this was most likely due to the distinct immunogen used rather than the clonality of the antibody.

Conclusions

Altogether, we found that monoclonal antibodies as a class perform equivalently to polyclonal antibodies for the detection of histone post-translational modifications in both human and mouse. Accordingly, we recommend the use of monoclonal antibodies in ChIP-seq experiments.

Electronic supplementary material

The online version of this article (doi:10.1186/s13072-016-0100-6) contains supplementary material, which is available to authorized users.

Continuing development of an oral health score for clinical audit

AIM

To compare the outcomes of a contemporary oral health status (OHS) scoring system with national oral health data from the 2009 Adult Dental Health Survey, and to explore the utility of the OHS in audit and service development.

METHODS

An OHS scoring system was developed as part of a previously reported comprehensive on-line patient assessment tool. The assessment tool also measured future disease risk and indicative capitation fee grading. The modified OHS score component was developed over 20 years of research and experience from the original Oral Health Index (Burke and Wilson 1995). The online tool was piloted by 25 volunteer dentists on 640 recall patients and qualitative and quantitative feedback provided. Anonymised data from the inputs and scores generated were collected centrally and analysed using descriptive statistics.

RESULTS

The modified OHS was reported to have good validity by the pilot group. Submitted data confirmed a mean age for the recall patients examined as 53 ± 15.8 years and an average oral health status score of 79.5 ± 10.8 where a score of 100 equates to perfect oral health. A breakdown of the scores into the eight principal components provided evidence of cross validation with the Adult Dental Health Survey (2009).

CONCLUSIONS

Scoring oral health status electronically offers valuable opportunities for clinical audit. The reported benchmark oral health score of 79.5 for recall patients can be updated as increased numbers of patients enter the centralised data recording system. Audit can be facilitated by this move from a paper-based system to an on-line tool with central data collection.

Long-term validity and reliability of a patient survey instrument designed for general dental practice

AIM

To consider the extent to which the validity and reliability of the Denplan Excel Patient Survey (DEPS) has been confirmed during its development and by its use in general dental practice and to explore methods by which any survey instrument used in general dental practice might be validated and tested for reliability.

METHODS

DEPS seeks to measure perceived practice performance on those issues considered to be of greatest importance to patients. Content validity was developed by a literature review and tested in a pilot study. Criterion validity was tested by comparing patient retention in a payment plan for practices achieving the highest DEPS scores with those attaining the lowest scores over a two year period (surveys completed between 2010 and 2012). Reliability was assessed using the test/re-test method for 23 practices with approximately a three year time interval between tests. Internal consistency was tested by comparing Net Promoter Scores (NPS - which is measured in DEPS) attained by practices with their Patient Perception Index (PPI) as measured by the ten core questions in DEPS.

RESULTS

Practices in the pilot study strongly endorsed the content validity of DEPS. The 12 practices with the highest scores in the DEPS slightly increased their number of patients registered in Denplan payment plans during a two year period. The 12 lowest scoring practices saw 7% of their patients de-register during the same period. The 23 practices selected for the test/re-test study averaged more than 250 responses for both the test and re-test phases. The magnitude and pattern of their results were similar in both phases, while, on average, a modest improvement in results was observed. Internal consistency was confirmed as NPS results in DEPS closely mapped PPI results. The higher the measurement of perceived quality (PPI) the more likely patients were to recommend the practice (NPS).

CONCLUSION

Both through its development and use over the last four years The DEPS has demonstrated good validity and reliability. The authors conclude that this level of validity and reliability is adequate for the clinical/general care audit purpose of DEPS and that it is therefore likely to reliably inform practices where further development are indicated. It is important and quite straightforward to both validate and check the reliability of patient surveys used in general dental practice so that dental teams can be confident in the instrument they are using.

Enhanced methods for unbiased deep sequencing of Lassa and Ebola RNA viruses from clinical and biological samples

We have developed a robust RNA sequencing method for generating complete de novo assemblies with intra-host variant calls of Lassa and Ebola virus genomes in clinical and biological samples. Our method uses targeted RNase H-based digestion to remove contaminating poly(rA) carrier and ribosomal RNA. This depletion step improves both the quality of data and quantity of informative reads in unbiased total RNA sequencing libraries. We have also developed a hybrid-selection protocol to further enrich the viral content of sequencing libraries. These protocols have enabled rapid deep sequencing of both Lassa and Ebola virus and are broadly applicable to other viral genomics studies.

Enhanced methods for unbiased deep sequencing of Lassa and Ebola RNA viruses from clinical and biological samples

We have developed a robust RNA sequencing method for generating complete de novo assemblies with intra-host variant calls of Lassa and Ebola virus genomes in clinical and biological samples. Our method uses targeted RNase H-based digestion to remove contaminating poly(rA) carrier and ribosomal RNA. This depletion step improves both the quality of data and quantity of informative reads in unbiased total RNA sequencing libraries. We have also developed a hybrid-selection protocol to further enrich the viral content of sequencing libraries. These protocols have enabled rapid deep sequencing of both Lassa and Ebola virus and are broadly applicable to other viral genomics studies.

Simultaneous generation of many RNA-seq libraries in a single reaction

Although RNA-seq is a powerful tool, the considerable time and cost associated with library construction has limited its utilization for various applications. RNAtag-Seq, an approach to generate multiple RNA-seq libraries in a single reaction, lowers time and cost per sample, and it produces data on prokaryotic and eukaryotic samples that are comparable to those generated by traditional strand-specific RNA-seq approaches.

A comprehensive map of mobile element insertion polymorphisms in humans

As a consequence of the accumulation of insertion events over evolutionary time, mobile elements now comprise nearly half of the human genome. The Alu, L1, and SVA mobile element families are still duplicating, generating variation between individual genomes. Mobile element insertions (MEI) have been identified as causes for genetic diseases, including hemophilia, neurofibromatosis, and various cancers. Here we present a comprehensive map of 7,380 MEI polymorphisms from the 1000 Genomes Project whole-genome sequencing data of 185 samples in three major populations detected with two detection methods. This catalog enables us to systematically study mutation rates, population segregation, genomic distribution, and functional properties of MEI polymorphisms and to compare MEI to SNP variation from the same individuals. Population allele frequencies of MEI and SNPs are described, broadly, by the same neutral ancestral processes despite vastly different mutation mechanisms and rates, except in coding regions where MEI are virtually absent, presumably due to strong negative selection. A direct comparison of MEI and SNP diversity levels suggests a differential mobile element insertion rate among populations.

Holding personal information in a disease-specific register: the perspectives of people with multiple sclerosis and professionals on consent and access

OBJECTIVE

To determine the views of people with multiple sclerosis (MS) and professionals in relation to confidentiality, consent and access to data within a proposed MS register in the UK.

DESIGN

Qualitative study using focus groups (10) and interviews (13).

SETTING

England and Northern Ireland.

PARTICIPANTS

68 people with MS, neurologists, MS nurses, health services management professionals, researchers, representatives from pharmaceutical companies and social care professionals.

RESULTS

People with MS expressed open and altruistic views towards the use of their personal information to facilitate service provision and research, placing trust in responsible guardianship and legitimate use of their information. Participant's proposed that people with MS should be able to select their individual level of involvement in a register using levels of consent. It was agreed that access to the register should be governed by a guardianship committee composed of a range of stakeholders. People with MS did not wish their details to be used by marketing agencies and did not consider this a legitimate use of their data. Whilst participants were positive of the role a register could play in promoting research, participants felt that access to data by pharmaceutical industries should be administered by the guardianship committee. People with MS are concerned should their employers be able to access their personal information. Professionals were more cautious than people with MS in their approach to the use of patient personal data within a register.

CONCLUSIONS

Whilst all stakeholders were positive of the benefits of an MS register, development of such a resource must incorporate robust data security and guardianship measures in order to ensure that, whilst opportunities are maximised, risks to the privacy of individuals and legal challenges to professionals are avoided.

The reproducibility of the Denplan Oral Health Score (OHS) in general dental practitioners

OBJECTIVE

To assess the reproducibility of the Denplan Oral Health Score (OHS) and to examine whether general dental practitioners are more reproducible at measuring oral health when they use the OHS than when they use their usual method of examining patients.

DESIGN

This was a single centre study designed to compare dentists' reproducibility using the Oral Health Score with their reproducibility when using the method of examination that they normally employ in general practice.

SETTING

The study was carried out at The University of Birmingham School of Dentistry during 2001.

PARTICIPANTS

Ten local general dental practitioners were recruited by advertising. The patients were selected from various clinics in the University of Birmingham School of Dentistry to provide a broad spectrum of oral health.

MAIN OUTCOME MEASURES

The dentists scored oral health by two methods; firstly on a 10 cm linear scale after using their everyday method of examination and secondly using the structured format of the OHS examination, where the Oral Health Scores were expressed as a percentage.

RESULTS

Overall, the majority of the participating dentists demonstrated better intra-examiner reproducibility with the OHS than with their own method of examination. There was also higher inter-examiner reproducibility with the OHS than with the dentists' own method.

A practical definition of conduction block in IvIg responsive multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy with conduction block (MMN) can be mistaken for motor neurone disease or other lower motor neurone syndromes, but is treatable with intravenous immunoglobulin (IvIg). Formal electrophysiological criteria for conduction block (CB) are so stringent that substantial numbers of patients may miss out on appropriate treatment.

METHODS

Electrophysiological data were collected from 10 healthy volunteers and compared to data from 10 patients who satisfied the clinical criteria for MMN and who responded to IvIg. This produced a definition of CB in MMN patients which was compared with existing definitions to assess "miss rates".

RESULTS

Mean values for compound muscle action potential area, amplitude, and duration were calculated in normal subjects. Results beyond 3 SD of their respective means were considered abnormal. Using these criteria, CB in the context of MMN was defined as a reduction in negative peak area >23% along a distal nerve segment or >29% across a proximal segment; or a reduction in amplitude >32% across a distal segment or >33% across a proximal segment. All IvIg responsive patients had at least one nerve segment showing such CB. Employing some criteria from the literature would have denied treatment to over 30% of responsive patients.

CONCLUSION

In the clinical setting of suspected MMN, less stringent criteria for CB can improve the diagnosis of this treatable disorder. Exclusions on grounds of temporal dispersion may be over-restrictive. A little over one third of CBs occur proximally.

The effect of treatment upon temporal dispersion in IvIg responsive multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy with conduction block (MMN) is a treatable disorder that can be mistaken for other lower motor neurone syndromes. Existing electrophysiological diagnostic criteria for MMN are restrictive. In particular, many are cautious about diagnosing conduction block (CB) in the presence of abnormal temporal dispersion (TD).

OBJECTIVE

To study the significance of TD in MMN, its relationship to CB in intravenous immunoglobulin (IvIg) responsive patients, and its utility in detecting a treatment response.

METHODS

We compared pre- and post-treatment changes in CB and TD in nine patients who satisfied clinical and electrophysiological criteria for MMN and responded to IvIg.

RESULTS

TD improved in one or more nerve segments in eight of nine patients tested. There was marked improvement in 65% of all nerve segments, and 60% of those segments with CB. By comparison, significant improvement in CB occurred in only 33% of segments. Of segments with significantly better CB after treatment, all but one showed similar improvements in TD. Such changes were not related to the degree of TD before treatment, being seen in segments with abnormal as well as normal TD. There was no correlation between improvements seen in TD and CB.

CONCLUSION

We believe that TD should be considered an inherent feature of MMN. Improvement in TD is an independent marker of electrophysiological improvement in this disorder and is likely to be more useful than CB. When MMN is clinically suspected, the use of stringent criteria for CB in the presence of TD should be avoided.

The phenotype of limb-girdle muscular dystrophy type 2I

BACKGROUND

Mutations in the fukutin-related protein gene FKRP cause limb-girdle muscular dystrophy (LGMD2I) as well as a form of congenital muscular dystrophy (MDC1C).

OBJECTIVE

To define the phenotype in LGMD2I.

METHODS

The authors assessed 16 patients from 14 families with FKRP gene mutations and LGMD and collected the results of mutation analysis, protein studies, and respiratory and cardiac investigations.

RESULTS

Thirteen patients, most with adult presentation, were homozygous for the common C826A mutation in FKRP. The three other cases were compound heterozygotes for C826A and two of them presented in childhood, with more progressive disease. The pattern of muscle involvement, frequently including calf hypertrophy, was similar to dystrophinopathy. Complications in patients with LGMD2I were common and sometimes out of proportion to the skeletal muscle involvement. Six patients had cardiac involvement, and 10 had respiratory impairment: five required nocturnal respiratory support. All patients had serum creatine kinase at least 5 to 70 times normal. The most consistent protein abnormality found on muscle biopsy was a reduction of laminin alpha2 immunolabeling, either on muscle sections or immunoblotting alone.

CONCLUSIONS

LGMD2I due to FKRP mutations appears to be a relatively common cause of LGMD, with respiratory and cardiac failure as prominent complications.

Evaluation of an oral health scoring system by dentists in general dental practice

An Oral Health Index (OHX) has been designed to provide a numerical measure of the overall state of a patient's oral health by means of a series of simple clinical examinations. This has been amended to produce the Oral Health Score (OHS).

OBJECTIVE

To assess, by means of a questionnaire, the ease of use and understanding of the OHS by general dental practitioners.

METHODS

350 GDPs were asked to participate in the project, of whom 329 agreed. These dentists were given a lecture of 2 hours' duration on the OHS. The participating dentists were requested to use the OHS for a period of 1 year. At the end of this period, a questionnaire was delivered to them by post, with an explanatory letter and reply-paid envelope.

RESULTS

Completed, usable questionnaires were received from 239 GDPs, a 77% response rate. Ninety three percent of respondents considered the OHS instructions to be satisfactory. The respondents' views on the criteria on which the OHS component assessments are based indicated that over 90% of respondents agreed with the criteria for caries, adequacy of restorations, periodontal assessment, mucosal assessment and assessment of dentures. A majority of respondents agreed that the OHS provided a valid representation of oral health.

CONCLUSION

The results of the present study indicate that the OHS is considered to be an easy-to-use measure of a patient's oral health and that it provides a valid representation of a patient's oral health.

The clinical and laboratory features of chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies

The clinical and laboratory phenotype of a paraproteinaemic neuropathy syndrome termed chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies is described in a series of 18 cases. Previous single case reports have outlined some features of this syndrome. All 18 cases were defined by the presence of serum IgM antibodies which react principally with NeuAc (alpha2-8)NeuAc(alpha2-3)Gal-configured disialosyl epitopes common to many gangliosides including GDlb, GD3, GTlb and GQlb. In 17 out of 18 cases, the serum contained benign IgM paraproteins, and in four of these cases at least two IgM paraproteins were present. The IgM antibodies were also cold agglutinins in 50% of cases. The clinical picture comprised a chronic neuropathy with marked sensory ataxia and areflexia, and with relatively preserved motor function in the limbs. In addition, 16 out of 18 cases had motor weakness affecting oculomotor and bulbar muscles as fixed or as relapsing-remitting features. When present in their entirety, these clinical features have been described previously under the acronym CANOMAD: chronic ataxic neuropathy, ophthalmoplegia, IgM paraprotein, cold agglutinins and disialosyl antibodies. This distribution of clinical features is reminiscent of Miller Fisher syndrome, in which acute-phase anti-disialylated ganglioside IgG antibodies are found. Clinical electrophysiology and nerve biopsy show both demyelinating and axonal features. A partial response to intravenous immunoglobulin and other treatments is reported in some cases.

Predominant arm weakness in acute idiopathic polyneuritis: a distinct regional variant

Acute idiopathic polyneuritis is a heterogeneous disorder with a number of clearly established variants. We describe four patients who present with an acute neuropathy predominantly affecting the arms which we believe should be considered as a distinct variant of acute polyneuritis. In two cases a primary demyelinating process affecting both motor and sensory nerves is suggested whereas in the other two the features were of a pure motor axonal degeneration. The relationship between these neuropathies, other variants of acute idiopathic polyneuritis and multifocal motor neuropathy is considered.

Effects of hydroxyurea administration on the body weight, body composition and exercise performance of patients with sickle-cell anaemia

1. As an ancillary study carried out during the recently completed Multicenter Study of Hydroxyurea, we examined the effect of hydroxyurea on the body weight, body composition and exercise capacity of adult patients with sickle-cell anaemia. 2. The subjects received either hydroxyurea (six males and four females) or placebo (eight males and six females). Data for each subject were generated during four separate 24 h admissions to the General Clinical Research Center. These admissions occurred at baseline and then at 6, 12 and 18 months after the start of study drug (hydroxyurea or placebo) administration. During each admission, body composition was measured by using a dual X-ray absorptiometer, and exercise testing was performed by cycle ergometry. Anaerobic performance was assessed according to a 'Wingate' protocol (20 s at maximal intensity against a cycling resistance of 7.5% body weight). Aerobic performance was examined using a steady state submaximal exercise protocol (10 min cycling time). 3. At baseline, no significant difference in any parameter was found between the hydroxyurea- and placebo-treated groups. At 18 months, the hydroxyurea-treated subjects exhibited an average weight gain of 3.16 kg. The mean weight gain in the placebo-treated subjects was 1.82 kg. Body composition analysis showed that the additional weight in both groups involved both lean and fat body mass components. In anaerobic performance, the subjects given hydroxyurea showed an increase in peak muscle power of 104.9 W. The placebo group also showed an increase, but theirs was a more modest gain of 57.7 W. The most marked improvement in anaerobic performance was observed in the hydroxyurea-treated men (P < 0.05). In aerobic performance, the hydroxyurea-treated subjects exhibited a decrease in peak heart rate response to a standardized workload of 15.2 beats/min, as compared with a decrease of only 4.3 beats/min in the placebo-treated patients. 4. Taken together, the overall weight gain, combined with increases in both anaerobic muscular performance and aerobic cardiovascular efficiency, provides objective data to support the subjective impression that hydroxyurea administration produces an improvement in the physical capacity of patients with sickle-cell anaemia.

Microalbuminuria in obese patients with or without hypertension

OBJECTIVE

To evaluate the prevalence in obese patients of an increased urinary albumin excretion rate (UAER) and the factors involved in this parameter.

SUBJECTS

Two hundred and seven nondiabetic obese patients with BMI = 34.7 +/- 5.7 (SD) kg/m2. None had proteinuria or a history of nephropathy or uropathy. Fifty-two had moderate hypertension. A control group of 22 lean healthy subjects was also studied.

MEASUREMENTS

The UAER was determined from 24-h urine samples by means of immunonephelemetry laser method. Creatinine clearance was calculated. Glycemia and plasma C peptide at fasting and 120 mine after glucose oral administration, HbA1c, serum fructosamine, plasma total cholesterol and triglycerides, HDL and LDL cholesterol were measured. Food intakes were determined by dietary history.

RESULTS

Compared with the control group, the UAER was significantly higher in the obese patients (18.0 +/- 20.1 mg/24 h vs 3.2 +/- 2.8 mg/24 h, P < 0.0001). It was elevated (> 30 mg/24 h) in 25 obese patients (12.1%) and in particular, in 19.2% of the obese patients with hypertension. It was significantly higher in the patients with android or mixed (both android and gynoid) obesity than in those with gynoid obesity (p = 0.050). Log UAER correlated negatively with the duration of hypertension (p = 0.038) and was higher in the patients with familial hypertension than in those without (p = 0.002). Log UAER correlated strongly with log creatinine clearance (p < 0.0001) and fractional albumin clearance (p < 0.0001). It correlated significantly with fasting and 120 min after glucose plasma C peptide concentrations (p = 0.018 and p = 0.046, respectively). Creatinine clearance was significantly higher in the patients with android or mixed obesity than in those with gynoid obesity (p = 0.001). Log creatinine clearance correlated negatively with age (p = 0.046), and log LDL cholesterol (p = 0.025) and positively with log lipid caloric intake (p = 0.014).

CONCLUSION

These results show the high prevalence of microalbuminuria in nondiabetic obese patients and suggest the involvement of renal hyperfiltration. Microalbuminuria may be an indicator of familial hypertension in obese subjects. Insulin resistance may be involved in the increase in the UAER. Nutritional factors, particularly lipid intake, may contribute to this increase in the UAER via an increase in glomerular hyperfiltration.

[Microalbuminuria and hypertension in obese patients]

The present study was designed to evaluate the frequency of an increase in the urinary albumin excretion rate (UAER) and the factors involved in this parameter in non-diabetic obese patients; 122 non-diabetic obese patients were investigated. None had proteinuria or history of nephropathy or uropathy. Fourty of them had moderate hypertension. Compared with a group of 22 lean controls, UAER was significantly higher in the obese patients (19.0 +/- 2.0 (SEM) mg/24 h vs 3.2 +/- 0.6 mg/24 h, p < 0.001). UAER was elevated (> 20 mg/24 h) in 29 patients (23.7%). Prevalence of microalbuminuria was not significantly different in hypertensive than in normotensive patients. However UAER was significantly higher in the 32 patients with a family history of hypertension (29.6 +/- 6.3 mg/24 h vs 15.3 +/- 1.5 mg/24 h, p < 0.002). In patients with microalbuminuria, body weight was significantly higher (100.3 +/- 3.9 kg vs 91.8 +/- 1.9 kg, p < 0.05), plasma albumin was significantly lower (38.3 +/- 0.6 g/l vs 40.3 +/- 0.3 g/l, p < 0.005) and the estimated value of fractional albumin clearance was significantly higher. These results show the high frequency of microalbuminuria in non-diabetic obese patients. They suggest that UAER level may be an index of family hypertension in obese patients and that microalbuminuria is part of a widespread abnormality of the capillary permeability.

Pharmacokinetic interaction between theophylline and chloramphenicol in rats

The effects of chloramphenicol, a potent enzyme inhibitor, on the pharmacokinetics of theophylline were investigated in Sprague-Dawley rats. Chloramphenicol treatment, 75 mg/day intravenously for 3 days, significantly (p less than 0.05) decreased the plasma clearance of theophylline by 31% with no apparent effects on the volume of distribution (0.97 liter/kg). The elimination half-life in chloramphenicol treated rats (N = 6) was 4.8 hr, significantly (p less than 0.05) longer than the corresponding half-life, 3.4 hr, in control rats (N = 6). It appears that chloramphenicol has a marked inhibitory effect on the activity of the cytochrome P-450-dependent mixed function oxidase liver microsome system responsible for the oxidation and demethylation of theophylline.