Epigenetic profiling reveals key genes and cis-regulatory networks specific to human parathyroids

In all terrestrial vertebrates, the parathyroid glands are critical regulators of calcium homeostasis and the sole source of parathyroid hormone (PTH). Hyperparathyroidism and hypoparathyroidism are clinically important disorders affecting multiple organs. However, our knowledge regarding regulatory mechanisms governing the parathyroids has remained limited. Here, we present the comprehensive maps of the chromatin landscape of the human parathyroid glands, identifying active regulatory elements and chromatin interactions. These data allow us to define regulatory circuits and previously unidentified genes that play crucial roles in parathyroid biology. We experimentally validate candidate parathyroid-specific enhancers and demonstrate their integration with GWAS SNPs for parathyroid-related diseases and traits. For instance, we observe reduced activity of a parathyroid-specific enhancer of the Calcium Sensing Receptor gene, which contains a risk allele associated with higher PTH levels compared to the wildtype allele. Our datasets provide a valuable resource for unraveling the mechanisms governing parathyroid gland regulation in health and disease.

Joint, multifaceted genomic analysis enables diagnosis of diverse, ultra-rare monogenic presentations

Genomics for rare disease diagnosis has advanced at a rapid pace due to our ability to perform "N-of-1" analyses on individual patients. The increasing sizes of ultra-rare, "N-of-1" disease cohorts internationally newly enables cohort-wide analyses for new discoveries, but well-calibrated statistical genetics approaches for jointly analyzing these patients are still under development.1,2 The Undiagnosed Diseases Network (UDN) brings multiple clinical, research and experimental centers under the same umbrella across the United States to facilitate and scale N-of-1 analyses. Here, we present the first joint analysis of whole genome sequencing data of UDN patients across the network. We apply existing and introduce new, well-calibrated statistical methods for prioritizing disease genes with de novo recurrence and compound heterozygosity. We also detect pathways enriched with candidate and known diagnostic genes. Our computational analysis, coupled with a systematic clinical review, recapitulated known diagnoses and revealed new disease associations. We make our gene-level findings and variant-level information across the cohort available in a public-facing browser (https://dbmi-bgm.github.io/udn-browser/). These results show that N-of-1 efforts should be supplemented by a joint genomic analysis across cohorts.

Joint estimation and imputation of variant functional effects using high throughput assay data

Deep mutational scanning assays enable the functional assessment of variants in high throughput. Phenotypic measurements from these assays are broadly concordant with clinical outcomes but are prone to noise at the individual variant level. We develop a framework to exploit related measurements within and across experimental assays to jointly estimate variant impact. Drawing from a large corpus of deep mutational scanning data, we collectively estimate the mean functional effect per AA residue position within each gene, normalize observed functional effects by substitution type, and make estimates for individual allelic variants with a pipeline called FUSE (Functional Substitution Estimation). FUSE improves the correlation of functional screening datasets covering the same variants, better separates estimated functional impacts for known pathogenic and benign variants (ClinVar BRCA1, p=2.24×10-51), and increases the number of variants for which predictions can be made (2,741 to 10,347) by inferring additional variant effects for substitutions not experimentally screened. For UK Biobank patients who carry a rare variant in TP53, FUSE significantly improves the separation of patients who develop cancer syndromes from those without cancer (p=1.77×10-6). These approaches promise to improve estimates of variant impact and broaden the utility of screening data generated from functional assays.

Dam mutants provide improved sensitivity and spatial resolution for profiling transcription factor binding

DamID, in which a protein of interest is fused to Dam methylase, enables mapping of protein-DNA binding through readout of adenine methylation in genomic DNA. DamID offers a compelling alternative to chromatin immunoprecipitation sequencing (ChIP-Seq), particularly in cases where cell number or antibody availability is limiting. This comes at a cost, however, of high non-specific signal and a lowered spatial resolution of several kb, limiting its application to transcription factor-DNA binding. Here we show that mutations in Dam, when fused to the transcription factor Tcf7l2, greatly reduce non-specific methylation. Combined with a simplified DamID sequencing protocol, we find that these Dam mutants allow for accurate detection of transcription factor binding at a sensitivity and spatial resolution closely matching that seen in ChIP-seq.

Predicting adult facial type from mandibular landmark data at young ages

OBJECTIVES

To assess the potential of predicting adult facial types at different stages of mandibular development.

SETTING AND SAMPLE POPULATION

A total of 941 participants from the Bolton-Brush, Denver, Fels, Iowa, Michigan and Oregon growth studies with longitudinal lateral cephalograms (total of 7166) between ages 6-21 years.

MATERIAL AND METHODS

Each participant was placed into one of three facial types based on mandibular plane angle (MPA) from cephalograms taken closest to 18 years of age (range of 15-21 years): hypo-divergent (MPA < 28°), normo-divergent (28°≤ MPA ≤ 39°) and hyper-divergent (MPA > 39°). Cephalograms were categorized into 13 age groups 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18-21. Twenty-three two-dimensional anatomical landmarks were digitized on the mandible and superimposed using generalized Procrustes analysis, which projects landmarks into a common shape space. Data were analysed within age categories using stepwise discriminant analysis to identify landmarks that distinguish adult facial types and by jackknife cross-validation to test how well young individuals can be reclassified into their adult facial types.

RESULTS

Although each category has multiple best discriminating landmarks among adult types, three landmarks were common across nearly all age categories: menton, gonion and articulare. Individuals were correctly classified better than chance, even among the youngest age category. Cross-validation rates improved with age, and hyper- and hypo-divergent groups have better reclassification rates than the normo-divergent group.

CONCLUSIONS

The discovery of important indicators of adult facial type in the developing mandible helps improve our capacity to predict adult facial types at a younger age.

Long-range chromatin interactions control trophoblast-restricted HLA-G expression during pregnancy (IRM6P.657)

Human pregnancy poses an immunological paradox: at the fetal-maternal interface, semi-allogeneic fetal extravillous trophoblasts (EVT) invade the uterine mucosa without being rejected by the maternal immune system. HLA-G is a nonclassical MHC class I molecule specifically expressed on the surface of EVT and is believed to be a key to fetus-induced immune tolerance. However, the EVT-specific expression of HLA-G is still poorly understood. A novel enhancer more than 10 kb upstream of HLA-G, Enhancer L, was discovered via dissection of the HLA-G locus using a Massively Parallel Reporter Assay (MPRA). DNase I Hypersensitive Site (DHS) mapping, Chromosome Conformation Capture (3C) and reporter gene assays established Enhancer L as a cell type-specific enhancer that loops into the HLA-G classical promoter. Strikingly, deletion of Enhancer L using a CRISPR/Cas9 dual guide approach results in complete ablation of HLA-G expression. Saturation mutagenesis of Enhancer L revealed the existence of motifs for transcription factors paramount in trophoblast development. Two of them, GATA2 and CEBPB, associate with Enhancer L and the HLA-G classical promoter, and are absolutely required for HLA-G expression. Interestingly, progesterone upregulates HLA-G, as well as GATA2, via a nonclassical membrane progesterone receptor complex in trophoblasts. These findings shed light on the mechanism by which HLA-G is specifically expressed in invasive trophoblasts during pregnancy.

Infrared optical coatings for the EarthCARE Multispectral Imager

The Earth Cloud, Aerosol and Radiation Explorer mission (EarthCARE) Multispectral Imager (MSI) is a radiometric instrument designed to provide the imaging of the atmospheric cloud cover and the cloud top surface temperature from a sun-synchronous low Earth orbit. The MSI forms part of a suite of four instruments destined to support the European Space Agency Living Planet mission on-board the EarthCARE satellite payload to be launched in 2016, whose synergy will be used to construct three-dimensional scenes, textures, and temperatures of atmospheric clouds and aerosols. The MSI instrument contains seven channels: four solar channels to measure visible and short-wave infrared wavelengths, and three channels to measure infrared thermal emission. In this paper, we describe the optical layout of the infrared instrument channels, thin-film multilayer designs, the coating deposition method, and the spectral system throughput for the bandpass interference filters, dichroic beam splitters, lenses, and mirror coatings to discriminate wavelengths at 8.8, 10.8, and 12.0 μm. The rationale for the selection of thin-film materials, spectral measurement technique, and environmental testing performance are also presented.

Predicting the development of acute kidney injury in liver cirrhosis--an analysis of glomerular filtration rate, proteinuria and kidney injury biomarkers

BACKGROUND

The timely diagnosis of acute kidney injury (AKI) in liver cirrhosis is challenging.

AIM

To evaluate whether quantification of glomerular filtration rate (GFR), proteinuria and kidney injury biomarkers can accurately predict the development of AKI.

METHODS

A prospective cohort analysis of patients with cirrhosis was performed. Measures of baseline kidney function included serum creatinine, iohexol clearance and urine protein:creatinine ratio. Blood and urine samples were collected daily. A retrospective analysis of cystatin C GFR and neutrophil gelatinase-associated lipocalin (NGAL) measured 48 h prior to the diagnosis of AKI was undertaken to evaluate their ability to predict the development of AKI.

RESULTS

Eighteen of the 34 cirrhosis patients studied developed AKI. A GFR <60 mL/min/1.73 m(2) was identified in 56% with Iohexol clearance compared to 8% using the four-variable modified diet in renal disease formula (P < 0.0001). Prediction of AKI, 48 h prior to the development of AKI with cystatin C GFR and serum NGAL concentration were similar; area under the receiver operating curve (AUROC) values 0.74 (0.51-0.97), P = 0.04 and 0.72 (0.52-0.92), P = 0.02 respectively. The development of AKI was strongly predicted by urine protein:creatinine ratio above the cut-off of >30 (equivalent to 300 mg/day of proteinuria) sensitivity 82% (57-96) and specificity 80% (52-96), AUROC 0.86 (0.73-0.98), P ≤ 0.0001. [OR 21 (3-133), P ≤ 0.002].

CONCLUSIONS

In patients with liver cirrhosis a urine protein:creatinine ratio >30 predicts AKI. Iohexol clearance and cystatin C formulae identify a greater proportion of patients with a GFR <60 mL/min/1.73 m(2), which also predicts the development of AKI.

Cooled infrared filters and dichroics for the sea and land surface temperature radiometer

The sea and land surface temperature radiometer (SLSTR) is a nine-channel visible and infrared high-precision radiometer designed to provide climate data of global sea and land surface temperatures. The SLSTR payload is destined to fly on the Ocean and Medium-Resolution Land Mission for the ESA/EU global monitoring for environment and security (GMES) programme Sentinel-3 mission to measure the sea and land temperature and topography for near real-time environmental and atmospheric climate monitoring of the Earth. In this paper we describe the optical layout of infrared optics in the instrument, the spectral thin-film multilayer design, and the system channel throughput analysis for the combined interference filter and dichroic beam splitter coatings to discriminate wavelengths at 3.74, 10.85, 12.0 μm. The rationale for selection of thin-film materials, the deposition technique, and environmental testing, inclusive of humidity, thermal cycling, and ionizing radiation testing are also described.

Generation of multipotent lung and airway progenitors from mouse ESCs and patient-specific cystic fibrosis iPSCs

Deriving lung progenitors from patient-specific pluripotent cells is a key step in producing differentiated lung epithelium for disease modeling and transplantation. By mimicking the signaling events that occur during mouse lung development, we generated murine lung progenitors in a series of discrete steps. Definitive endoderm derived from mouse embryonic stem cells (ESCs) was converted into foregut endoderm, then into replicating Nkx2.1+ lung endoderm, and finally into multipotent embryonic lung progenitor and airway progenitor cells. We demonstrated that precisely-timed BMP, FGF, and WNT signaling are required for NKX2.1 induction. Mouse ESC-derived Nkx2.1+ progenitor cells formed respiratory epithelium (tracheospheres) when transplanted subcutaneously into mice. We then adapted this strategy to produce disease-specific lung progenitor cells from human Cystic Fibrosis induced pluripotent stem cells (iPSCs), creating a platform for dissecting human lung disease. These disease-specific human lung progenitors formed respiratory epithelium when subcutaneously engrafted into immunodeficient mice.

MicroRNAs are indispensable for reprogramming mouse embryonic fibroblasts into induced stem cell-like cells

MicroRNAs play a pivotal role in cellular maintenance, proliferation, and differentiation. They have also been implicated to play a key role in disease pathogenesis, and more recently, cellular reprogramming. Certain microRNA clusters can enhance or even directly induce reprogramming, while repressing key proteins involved in microRNA processing decreases reprogramming efficiency. Although microRNAs clearly play important roles in cellular reprogramming, it remains unknown whether microRNAs are absolutely necessary. We endeavored to answer this fundamental question by attempting to reprogram Dicer-null mouse embryonic fibroblasts (MEFs) that lack almost all functional microRNAs using a defined set of transcription factors. Transduction of reprogramming factors using either lentiviral or piggyBac transposon vector into two, independently derived lines of Dicer-null MEFs failed to produce cells resembling embryonic stem cells (ESCs). However, expression of human Dicer in the Dicer-null MEFs restored their reprogramming potential. Our study demonstrates for the first time that microRNAs are indispensable for dedifferentiation reprogramming.

Lineage-based identification of cellular states and expression programs

We present a method, LineageProgram, that uses the developmental lineage relationship of observed gene expression measurements to improve the learning of developmentally relevant cellular states and expression programs. We find that incorporating lineage information allows us to significantly improve both the predictive power and interpretability of expression programs that are derived from expression measurements from in vitro differentiation experiments. The lineage tree of a differentiation experiment is a tree graph whose nodes describe all of the unique expression states in the input expression measurements, and edges describe the experimental perturbations applied to cells. Our method, LineageProgram, is based on a log-linear model with parameters that reflect changes along the lineage tree. Regularization with L(1) that based methods controls the parameters in three distinct ways: the number of genes change between two cellular states, the number of unique cellular states, and the number of underlying factors responsible for changes in cell state. The model is estimated with proximal operators to quickly discover a small number of key cell states and gene sets. Comparisons with existing factorization, techniques, such as singular value decomposition and non-negative matrix factorization show that our method provides higher predictive power in held, out tests while inducing sparse and biologically relevant gene sets.

An increase in bone stability in an aripiprazole add-on or switching study

Introduction

Schizophrenia is a mental health disorder associated with high rates of osteoporosis. Studies have suggested antipsychotics as a major cause of accelerated decrease in bone mineral density.

Oestrogen deficiency contributes to osteoporosis and causes increased osteoclast numbers/osteoclastic activity. Prolactin suppresses hypothalamo-pituitary-ovarian axis activity, leading to decreased oestrogen concentrations.

Aripiprazole, an ‘atypical’ antipsychotic, is a partial agonist at dopamine D2-receptors, while other atypical antipsychotics are antagonists at these receptors. Dopamine inhibits prolactin release via these receptors at the anterior pituitary. Aripiprazole has been found to decrease prolactin concentrations in chronic schizophrenics and may be protective against osteoporosis.

Quantitation of specific markers of osteoclastic (cross-linked N-telopeptide (NTX)) and osteoblastic activity (bone alkaline phosphatase (BAP)) can be correlated with bone resorption and bone formation, respectively.

Objectives

Exploring whether aripiprazole is effective in stabilising bone turnover.

Aims

Investigate changes in urinary markers of bone turnover.

Methods

We performed 52 week, open-label, intention-to-treat study, offering either a switch to aripiprazole or aripiprazole as add-on to initial antipsychotic medication.

Serial measurements of prolactin, testosterone, 17-β-oestradiol, serum BAP, albumin, urinary creatinine, and urinary NTX concentrations were taken between 0 and 52 weeks.

Results

At the end-point of study, versus the baseline, there were significant decreases in concentrations of urinary markers of bone resorption (P = 0.002 for NTX) and bone formation (P = .026 for BAP). Additionally, a significant decrease in prolactin (P = 0.004) and significant increase in 17-β-oestradiol concentrations (P = 0.015) were found.

Conclusions

Our results show decreased overall bone turnover; and increased long-term bone stability in patients who changed medication.

The effect of estrone on thrombin generation may explain the different thrombotic risk between oral and transdermal hormone replacement therapy

BACKGROUND

The metabolism of estrogen contained within hormone replacement therapy (HRT) is influenced by the route of administration, and this may affect the risk of venous thromboembolism. Thrombin generation, a global coagulation assay, is a marker of hypercoagulability and is of potential use in determining the thrombotic risk associated with particular HRT administration routes.

OBJECTIVES

To determine whether any effect of oral and transdermal HRT on thrombin generation is related to the plasma estrogen profile.

METHODS

We investigated the effects of oral, transdermal and no HRT (controls) in 52, 39 and 52 postmenopausal women, respectively, on thrombin generation, standard markers of thrombophilia, estradiol level and estrone level.

RESULTS

All parameters of thrombin generation were altered in women using oral HRT as compared with controls (P<0.001 for all comparisons). No such differences were found in women using transdermal HRT. Estrone levels correlated with peak thrombin generation (R=0.451, P<0.001) in women using oral HRT, but there was no correlation in women using the transdermal route.

CONCLUSIONS

Thrombin generation is significantly increased in women who use HRT administered by the oral route. This is probably mediated by the hepatic first-pass metabolism of estrone, the main metabolite of oral estradiol, which is avoided by the transdermal route. The effect of estrone on thrombin generation may provide the explanation for the higher thrombotic risk seen in women using oral rather than transdermal HRT.

Postprandial plasma bile acid responses in normal weight and obese subjects

Background

Bile acids can act as signalling molecules via various receptors including the nuclear farnesoid X receptor (FXR) and pregnane X receptor (PXR), and the cell surface G-protein-coupled receptor TGR5. The signalling has been implicated in the release of peptide YY (PYY) and glucagon-like peptide 1 (GLP-1), which improves glycaemic control and energy expenditure. We investigated whether morbidly obese subjects have altered postprandial bile acid responses in comparison to normal weight subjects.

Method

Blood samples were taken every 30 min from 0 to 180 min following a 400 kcal test meal. Samples were taken from 12 normal weight subjects with a body mass index (BMI) of 23.2 (2.8) kg/m2 (median [interquartile range (IQR)]) and seven obese patients with a BMI of 47.2 (7.2) kg/m2. Fractionated bile acids were measured on these samples using high-performance liquid chromatography tandem mass spectrometry.

Results

The obese subjects showed a lower postprandial response in total bile acids compared with the normal weight subjects. An increase of 6.4 (5.0) and 2.6 (3.3) μmol/L (median [IQR]) in normal weight and obese subjects was observed, respectively ( P = 0.02). The difference was predominantly due to the glycine-conjugated fraction ( P = 0.03). There was no difference in the increase of the unconjugated or taurine-conjugated fractions.

Conclusions

The decreased postprandial bile acid response in obese subjects compared with normal weight subjects may partly explain the suboptimal GLP-1 and PYY responses and could affect appetite, glycaemic control and energy expenditure.

Regulation and function of skeletal muscle stem cells

Skeletal muscle satellite cells, which reside beneath the basal lamina of mature muscle fibers, function as myogenic precursors and are required for normal muscle growth and repair. Satellite cells share a common anatomical localization, yet they exhibit substantial phenotypic and functional heterogeneity. Recent efforts in the field of adult myogenesis have been aimed at dissecting this heterogeneity and reveal the presence of discrete cell lineages within the muscle that function independently and interactively to maintain muscle homeostasis and to determine the outcome of muscle damage. Normal developmental regulation of the frequency and function of these distinct tissue precursors, and pathological deregulation of their activity, may have an important role in age- and disease-dependent loss of muscle regenerative activity.

Chronic fatigue syndrome and related disorders in UK veterans of the Gulf War 1990-1991: results from a two-phase cohort study

BACKGROUND

The aim was to determine the prevalence of chronic fatigue syndrome (CFS), chronic fatigue and fibromyalgia in UK military personnel after the Gulf War 1990-1991.

METHOD

A two-phase cohort study was used. Three randomly selected subsamples identified from a population-based cross-sectional postal survey of over 10,000 current and ex-service UK military personnel (Gulf veterans were those deployed to the Gulf War 1990-1991; non-Gulf veterans were Bosnia peacekeepers 1992-1997 and those on active duty during the Gulf War 1990-1991 but not deployed) were recruited. Their disability status was assessed using the Short Form 36 physical functioning scale; Gulf veterans who reported physical disability (n=111) were compared with non-Gulf (n=133) veterans who reported similar levels of physical disability. Screening for known medical and psychiatric conditions was conducted to exclude medical explanations for disability and symptomatic distress. Standardised criteria for CFS, chronic fatigue and fibromyalgia were used.

RESULTS

Disabled Gulf veterans were more likely to be overweight, have elevated gamma-glutamyl transferase levels and screen positive for hypertension. There were no other clinically significant differences in clinical markers for medically explainable conditions. Disabled Gulf veterans were more likely than similarly disabled Bosnia and Era veterans (adjusted odds ratio 7.8, 95% confidence interval 2.5-24.5) to meet the criteria for CFS. Rates for other medically unexplained conditions were not significantly increased.

CONCLUSIONS

Symptoms in keeping with CFS account for a significant part of the symptomatic distress in Gulf veterans.

Cooled infrared filters and dichroics for the James Webb Space Telescope Mid-Infrared Instrument

The cooled infrared filters and dichroic beam splitters manufactured for the Mid-Infrared Instrument are key optical components for the selection and isolation of wavelengths in the study of astrophysical properties of stars, galaxies, and other planetary objects. We describe the spectral design and manufacture of the precision cooled filter coatings for the spectrometer (7 K) and imager (9 K). Details of the design methods used to achieve the spectral requirements, selection of thin film materials, deposition technique, and testing are presented together with the optical layout of the instrument.

Effect of fat distribution on endothelial-dependent and endothelial-independent vasodilatation in healthy humans

AIM

The present study aims to explore the relationship between inflammatory cytokines, plasma lipids, insulin, blood pressure (BP), total adiposity/markers of fat distribution and endothelial function in healthy people across a wide range of body fatness.

METHODS

Seventy-three healthy people (44 women; age range: 24-64 years) with body mass index (BMI) range of 18.6-73.1 kg/m2 were recruited. All participants underwent assessment of conduit artery endothelial-dependent vasodilatation by using flow-mediated vasodilatation (FMD) of the brachial artery and endothelial-independent vasodilatation to sublingual GTN. They had blood taken for measurement of plasma markers of glucose homeostasis (fasting insulin and glucose), systemic inflammation (interleukin-6 (IL-6), C-reactive protein (CRP) and tumour necrosis factor-alpha receptor 2 (TNF-alpha R2)) and lipids (low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides). Morphometric assessment (waist circumference, BMI and waist-to-hip ratio (WHR)) and systolic and diastolic arterial pressure were also measured.

RESULTS

Markers of total body fat/fat distribution (waist circumference, BMI and WHR), inflammation (IL-6, CRP and TNF-alpha R2), metabolism (fasting insulin, HDL, LDL and triglycerides) and BP (systolic and diastolic) correlated with FMD. Among these measurements, WHR was the only independent predictor of FMD (r2 = 0.30; p = 0.0001).

CONCLUSIONS

WHR is an important marker of endothelial dysfunction in healthy people across a wide range of body fatness.

Proportional assist ventilation as an aid to exercise training in severe chronic obstructive pulmonary disease

BACKGROUND

The effects of providing ventilatory assistance to patients with severe chronic obstructive pulmonary disease (COPD) during a high intensity outpatient cycle exercise programme were examined.

METHODS

Nineteen patients (17 men) with severe COPD (mean (SD) forced expiratory volume in 1 second (FEV(1)) 27 (7)% predicted) underwent a 6 week supervised outpatient cycle exercise programme. Ten patients were randomised to exercise with ventilatory assistance using proportional assist ventilation (PAV) and nine (two women) to exercise unaided. Before and after training patients performed a maximal symptom limited incremental cycle test to determine peak work rate (Wpeak) followed by a constant work rate (CWR) test at 70% of Wpeak achieved in the baseline incremental test. Minute ventilation (VE), heart rate, and arterialised venous plasma lactate concentration [La(+)] were measured before and after each test.

RESULTS

Mean training intensity (Wt/Wpeak) at 6 weeks was 15.2% (95% CI 3.2 to 27.1) higher in the group that used ventilatory assistance (p=0.016). Peak work rate after training was 18.4% (95% CI 6.4 to 30.5) higher (p=0.005) in the assisted group (p=0.09). [La(+)] at an identical workload after training was reduced by 30% (95% CI 16 to 44) in the assisted group (p=0.002 compared with baseline) and by 11% (95% CI -7 to 31) (p=0.08 compared with baseline) in the unassisted group (mean difference 18.4% (95% CI 3.3 to 40), p=0.09). A significant inverse relationship was found between reduction in plasma lactate concentration (DeltaL) at an equivalent workload after training during the CWR test and Wt/Wpeak achieved during the last week of training (r=-0.7, p=0.0006).

CONCLUSIONS

PAV enables a higher intensity of training in patients with severe COPD, leading to greater improvements in maximum exercise capacity with evidence of true physiological adaptation.

Serum S100 concentrations are not useful in predicting micrometastatic disease in cutaneous malignant melanoma

BACKGROUND

S100 protein is an acidic calcium binding protein that is expressed by melanoma cells. Elevated serum values of S100 have been described in metastatic disease and it has been suggested that it may be used as an adjunct to staging and monitoring of treatment. Micrometastatic disease in the sentinel lymph node can be demonstrated by sentinel node biopsy (SNB) and the sentinel node status is known to be the most important predictor of relapse.

OBJECTIVES

To determine whether serum S100 concentrations could predict the presence of micrometastatic disease.

METHODS

Thirty-one patients with primary cutaneous melanoma > 1 mm were recruited from referrals to the Melanoma clinic. All patients had serum S100 concentrations evaluated prior to undergoing SNB. Serum S100 concentrations were established using an immunoluminometric method. Sentinel nodes were identified using a dual technique with both radiolabelled colloid (residual from preoperative lymphoscintigraphy) and blue dye according to the MD Anderson Cancer Center protocol. Results Nine of these 31 patients had evidence of micrometastatic disease on SNB. The mean serum S100 concentration of those with positive SNBs was 0.027 microg L-1 compared with 0.045 microg x L(-1) in patients with negative SNBs (normal < 0.14 microg x L(-1)). No patient in the study demonstrated raised concentrations of serum S100.

CONCLUSIONS

We conclude that serum S100 concentrations do not predict the presence of micrometastatic melanoma in sentinel nodes in primary cutaneous melanoma.

Glucose, insulin and potassium for heart protection during cardiac surgery

BACKGROUND

Coronary artery bypass grafting with hypothermic cardiac arrest and cardiopulmonary bypass (CPB) is associated with myocardial injury. Our study investigated whether an infusion of glucose, insulin and potassium (GIK) during elective coronary artery bypass surgery decreases myocardial cell death.

METHODS

We measured cardiac troponin I (cTnI), a myofibrillar structural protein, which is a sensitive and specific indicator of myocytic injury. With ethics committee approval, 42 patients were enrolled into a randomized, prospective, double-blinded study. In the GIK group, 500 ml of 50% dextrose solution containing 100 IU insulin and potassium 80 mmol was infused at the rate of 0.75 ml kg(-1) h(-1). Patients in the non-GIK group received 5% dextrose solution at the same rate. Arterial blood samples were taken before induction of anaesthesia, after removal of the aortic clamp and 6 and 12 h after CPB.

RESULTS

In both groups there was an increase in cTnI concentration (P<0.05), which was greatest about 6 h after CPB. At no time did the cTnI concentration differ between the two groups.

CONCLUSION

The results suggest that GIK does not decrease the irreversible myocardial damage associated with routine coronary artery bypass surgery.

Acute dosage with dexrazoxane, but not doxorubicin, is associated with increased rates of hepatic protein synthesis in vivo

An investigation was carried out into the effects of dexrazoxane and doxorubicin on hepatic protein synthesis in vivo. The protocol included 8 groups of rats and involved a pretreatment stage of 30 min followed by a treatment stage of either 2.5 or 24 h. Male Wistar rats (=0.15-0.20 kg) were pretreated with either dexrazoxane (100 mg/kg; 5 ml/kg) or saline (0.15 mol/l NaCl; 5 ml/kg). At 30 min after the pretreatment, rats were again injected with either doxorubicin (5 mg/kg; 10 ml/kg) or saline (0.15 mol/l NaCl; 10 ml/kg) in the treatment phase. Rats were sacrificed at either 2.5 or 24 h after the last doxorubicin or saline injection. Rate of protein synthesis were measured 10 min prior to sacrificing rats, with a flooding dose of L-[4-3H]phenylalanine. Liver was analyzed for the protein synthetic capacity (Cs, mg RNA/g protein), the fractional rate of protein synthesis (k(s), %/d), and the RNA activity (kRNA mg protein/d/mg RNA). Complementary analysis included plasma albumin, total protein and activities of alkaline phosphatase, and aspartate aminotransferase. In the 2.5-h study, doxorubicin alone had no effect on any of the above variables. Dexrazoxane alone increased Cs, k(s) and kRNA at 2.5 h. Combined dexrazoxane + doxorubicin increased hepatic Cs and k(s) with concomitant reductions in total plasma protein. In the 24-h study, doxorubicin alone had no effect on any of the variables. Dexrazoxane alone had no effect on either Cs, k(s), or kRNA but raised plasma activities of alkaline phosphatase and aspartate aminotransferase. Combined dexrazoxane + doxorubicin increased Cs and k(s) and decreased total plasma protein and increased plasma aspartate aminotransferase activities at 24 h. In conclusion, there is no evidence that acutely doxorubicin per se has measurable effects on hepatic protein synthesis in vivo in an acute period. However, acutely dexrazoxane increases hepatic protein synthesis, which may represent its putative cytotoxic effects, as indicated by raised serum activities of liver enzymes. A combination of both dexrazoxane + doxorubicin appears to have a greater effect in increasing liver protein synthesis than dexrazoxane alone.

Faecal calprotectin and faecal occult blood tests in the diagnosis of colorectal carcinoma and adenoma

BACKGROUND AND AIMS

Testing for faecal occult blood has become an accepted technique of non-invasive screening for colorectal neoplasia but lack of sensitivity remains a problem. The aim of this study was to compare the sensitivity and specificity of faecal calprotectin and faecal occult blood in patients with colorectal cancer and colonic polyps.

METHODS

Faecal calprotectin and occult blood were assessed in 62 patients with colorectal carcinoma and 233 patients referred for colonoscopy. The range of normality for faecal calprotectin (0.5-10.5 mg/l) was determined from 96 healthy subjects.

RESULTS

Median faecal calprotectin concentration in the 62 patients with colorectal carcinoma (101 mg/l, 95% confidence interval (CI) 57-133) differed significantly from normal (2.3 mg/l, 95% CI 1.6-5.0) with 90% of patients having elevated levels (normal <10 mg/l) whereas only 36/62 (58%) had positive faecal occult bloods. There was no significant difference in faecal calprotectin levels when considering location or Dukes' staging of tumour. Percentage positivity of faecal occult bloods was significantly higher for Dukes' stage C and D cancers compared with Dukes' A and B. In the colonoscopy group, 29 patients with adenomatous polyps were detected in whom the median faecal calprotectin was 12 mg/l (95% CI 2.9-32). Sensitivity for detection of adenomatous polyps was 55% using the calprotectin method and 10% using faecal occult blood testing. The overall sensitivity and specificity of calprotectin for colorectal cancer and adenomatous polyps as a combined group was 79% and 72%, respectively, compared with a sensitivity and specificity of faecal occult blood of 43% and 92%.

CONCLUSIONS

Faecal calprotectin is a simple and sensitive non-invasive marker of colorectal cancer and adenomatous polyps. It is more sensitive than faecal occult blood tests for detection of colorectal neoplasia at the cost of a somewhat lower specificity.

The Interdisciplinary Generalist Curriculum (IGC) project: an overview of its experience and outcomes

The Interdisciplinary Generalist Curriculum (IGC) Project was a competitive, seven-year demonstration project funded by the Health Resources and Services Administration (HRSA). It was established to determine whether specific interdisciplinary innovations in preclinical medical school curricula could affect students' selection of careers in family medicine, general internal medicine, or general pediatrics. Through collaboration among the three generalist disciplines, the IGC innovation exposed all preclinical students in ten demonstration schools to a new or significantly enhanced preclinical curriculum that included a direct supervised clinical experience with a generalist physician preceptor. The project was managed by an interdisciplinary executive committee that was codirected by one representative each from family medicine, general internal medicine, and general pediatrics. A national advisory committee with representation from the academic and professional organizations of family medicine, internal medicine, pediatrics, and osteopathy provided input to the executive committee in guiding the project. The project was externally evaluated. Major outcomes of the IGC Project include sustained curricular changes in ten institutions, prompted by relatively few dollars and demonstration of models for collaboration at institutional and national levels. This supplement describes the IGC Project's experience and outcomes so that others may draw pertinent information to apply to their own efforts in medical education.

Curricular change: recommendations from a national perspective

Recommendations on future directions, funding, and organizational and curricular issues have emerged from the complexity of the Interdisciplinary Generalist Curriculum (IGC) Project. For example, future demonstration projects aimed at innovations in medical education that are funded through the contracting mechanism are recommended, and funding intended to serve as institutional leverage for demonstrating desired curricular innovations in medical education is encouraged. Funding provided to entities that can maximize influence within the institutions is recommended. Also, the period of time over which funds are provided needs to take into consideration the breadth of the impact of the funded program on the larger curriculum and the length of time needed to measure desired outcomes. Organizational findings are that multi-site projects with administrative oversight bodies should be governed by representatives of concerned disciplines who have stakes in the demonstration of the innovations in medical education, and roles of the executive and advisory committees involved in the effort need to be made explicit at the onset and revisited over time. Similarly, the role of the funder needs to be explicit. Curricular recommendations are that medical schools are encouraged to develop longitudinal generalist preceptorship experiences early in medical education for all students, regardless of their eventual career choices. Schools should anticipate that curricular innovations in the preclinical years may require modifications of the educational process in the clinical years.

In vivo protein synthetic rates of atrial, ventricular, and pulmonary tissue proteins in aortic constriction, goldblatt, and bromoethylamine models of hypertension

Changes in tissue protein synthesis in hypertension have usually been measured in vitro in heart from acutely hypertensive rats without consideration of changes in atrial or pulmonary tissue or changes occurring in long-standing hypertension. The objective of the study was to investigate the in vivo changes in cardiopulmonary protein synthesis in three different rat models of chronic hypertension. Hypertension in aortic constriction, the Goldblatt model, and the bromoethylamine model were induced in rats for 30 days. At the end of the experimental period, in vivo rates of protein synthesis were measured with a flooding dose of [3H]phenylalanine (a method which effectively considers precursor pools). Concomitant measurements included quantification of contractile protein and RNA and DNA contents. Indices of protein breakdown were also assessed by selective measurement of protease activities. At the end of 30 days, aortic constriction induced marked increases in protein contents of the left ventricle, septum, left atria, and lungs. Accompanying changes included concomitant increases in RNA and DNA contents. Left ventricular myofibrillary, sarcoplasmic, and stromal protein contents increased in the aortic constriction model. Less marked changes occurred in the Goldblatt model, though the left atria were not significantly affected. In contrast, the bromoethylamine model had no effect on the protein or RNA contents of any region. In all cardiac regions of all three models, fractional rates of protein synthesis were not significantly affected. However, protein synthesis increased in the lungs of both the Goldblatt and bromoethylamine models at 30 days. Protease activities were decreased in the left ventricles of all three models at 30 days, with lysosomal protease activities declining in the aortic constriction model and cytoplasmic protease activities declining in the other two models. The failure of chronic hypertension to increase ventricular synthesis rates may represent inherent limitations in the time frame for measuring protein synthesis in vivo. However, at earlier time points (i.e., 10 days), the aortic constriction model was characterized by marked increases in left ventricular and atrial protein contents, RNA contents, and fractional rates of protein synthesis. This was consistent with the supposition that, in acute phases of hypertrophy, rates of protein synthesis increase, whereas in established hypertrophy, synthesis rates remain unchanged or decrease. The applicability of the aortic constriction model was investigated by examining the effects of the angiotensin converting enzyme inhibitor lisinopril (5 mg/kg/day). After 30 days treatment, lisinopril impeded the increase in left ventricular mixed and myofibrillar proteins. This effect was accompanied by an apparent increase in protein synthesis. In conclusion, although all three chronic models are able to induce hypertension, varying degrees of hypertrophy develop, which are more pronounced in the aortic constriction model. Accompanying changes include hypertrophy in the atria, reduced rates of ventricular proteolytic activity, and altered rates of protein metabolism in the lungs.

Comparison of five cyclosporin immunoassays with HPLC

High performance liquid chromatography (HPLC) is the reference method for cyclosporin (CyA) measurements but therapeutic monitoring of the drug is frequently made using the more practical immunoassays. Cross-reactivity with CyA metabolites may compromise the specificity of immunoassays, particularly in liver graft recipients where metabolites may accumulate. The aim of this study was to compare with HPLC the performance of two recently introduced CyA immunoassays (the AxSYM fluorescent polarisation immunoassay (FPIA) and non-extraction CEDIA assay). The comparison was extended to the well-established TDx monoclonal FPIA (TDx mono) and the enzyme multiplied (EMIT)-specific assays and to the polyclonal FPIA (TDx poly), in which metabolite cross-reactivity is extensive. Assays were performed on 106 blood samples (taken 6 days to 118 months post-liver transplant) and results were compared by non-parametric regression analysis and difference plots. AxSYM and CEDIA showed both constant and proportional bias against HPLC (unlike EMIT) but the mean difference from HPLC was least for AxSYM (2.7 microg/l vs. 11.7, 9.4 and 54 microg/l for CEDIA, EMIT and TDx mono, respectively. (TDx poly - HPLC) values were proportional to all immunoassay results, with slopes of 0.33, 0.38 and 0.45 for EMIT, AxSYM and CEDIA, respectively. Our data suggest close agreement between AxSYM, CEDIA and EMIT results.

Infrared filters and coatings for the High Resolution Dynamics Limb Sounder (6-18 microm)

We describe the spectral design and manufacture of the narrow-bandpass filters and 6-18-microm broadband antireflection coatings for the 21-channel High Resolution Dynamics Limb Sounder. A method of combining the measured spectral characteristics of each filter and antireflection coating, together with the spectral response of the other optical elements in the instrument, to obtain a predicted system throughput response is presented. The design methods that are used to define the filter and coating spectral requirements, choice of filter materials, multilayer designs, and deposition techniques are discussed.

A simple method for assessing intestinal inflammation in Crohn's disease

BACKGROUND AND AIMS

Assessing the presence and degree of intestinal inflammation objectively, simply, and reliably is a significant problem in gastroenterology. We assessed faecal excretion of calprotectin, a stable neutrophil specific marker, as an index of intestinal inflammation and its potential use as a screening test to discriminate between patients with Crohn's disease and those with irritable bowel syndrome.

METHODS

The validity of faecal calprotectin as a marker of intestinal inflammation was assessed in 22 patients with Crohn's disease (35 studies) by comparing faecal excretions and concentrations using four day faecal excretion of (111)indium white cells. A cross sectional study assessed the sensitivity of faecal calprotectin concentration for the detection of established Crohn's disease (n=116). A prospective study assessed the value of faecal calprotectin in discriminating between patients with Crohn's disease and irritable bowel syndrome in 220 patients referred to a gastroenterology clinic.

RESULTS

Four day faecal excretion of (111)indium (median 8.7%; 95% confidence interval (CI) 7-17%; normal <1.0%) correlated significantly (p<0.0001) with daily (median ranged from 39 to 47 mg; normal <3 mg; r=0.76-0.82) and four day faecal calprotectin excretion (median 101 mg; 95% CI 45-168 mg; normal <11 mg; r=0.80) and single stool calprotectin concentrations (median 118 mg/l; 95% CI 36-175 mg/l; normal <10 mg/l; r=0.70) in patients with Crohn's disease. The cross sectional study showed a sensitivity of 96% for calprotectin in discriminating between normal subjects (2 mg/l; 95% CI 2-3 mg/l) and those with Crohn's disease (91 mg/l; 95% CI 59-105 mg/l). With a cut off point of 30 mg/l faecal calprotectin has 100% sensitivity and 97% specificity in discriminating between active Crohn's disease and irritable bowel syndrome.

CONCLUSION

The calprotectin method may be a useful adjuvant for discriminating between patients with Crohn's disease and irritable bowel syndrome.

Inspiratory pressure support prolongs exercise induced lactataemia in severe COPD

BACKGROUND

A physiological benefit from pulmonary rehabilitation in chronic obstructive pulmonary disease (COPD) is more probable if exercise is performed above the lactate threshold. This study was undertaken to investigate whether it was possible to extend the lactataemia of exercise using non-invasive inspiratory pressure support (IPS).

METHODS

Plasma lactate levels were measured in eight men with severe COPD who performed two treadmill walks at an identical constant work rate to a condition of severe dyspnoea; the second walk was supported by IPS.

RESULTS

Mean plasma lactate levels before the free and IPS assisted walks were 1.65 mmol/l and 1. 53 mmol/l, respectively (p = NS). Lactate levels increased during both walks to 2.96 mmol/l and 2.42 mmol/l, respectively (p = 0.01 for each) but the duration of the IPS assisted walk was significantly greater than the free walk (13.6 minutes versus 5.5 minutes, p = 0.01).

CONCLUSIONS

Patients with severe COPD can sustain exercise induced lactataemia for longer if assisted with IPS. This technique may prove to be a useful adjunct in pulmonary rehabilitation.

The prevalence and severity of intestinal disaccharidase deficiency in human immunodeficiency virus-infected subjects

BACKGROUND

Gastrointestinal symptoms are distressing features of human immunodeficiency virus (HIV) infection, and management is often empirical, including withdrawal of dietary lactose. We assessed the prevalence and severity of intestinal disaccharidase deficiency in vitro and in vivo.

METHODS

Fifty-four HIV-seropositive patients (19 HIV well +/- mild diarrhoea, 7 acquired immunodeficiency syndrome (AIDS) well, and 28 AIDS with diarrhoea) were studied with a combined non-invasive absorption-permeability-disaccharidase test that enables quantitative assessment of the rate of intestinal hydrolysis of lactose, sucrose, and palatinose. Thirty patients had jejunal biopsy specimens suitable for histomorphometric assessment, and 36 had in vitro disaccharidase activity measurement.

RESULTS

Patients with HIV (with mild diarrhoea) and AIDS (with and without severe diarrhoea) had frequent but mild histomorphometric changes in jejunal specimens. This was associated with frequent (21%-100%) and often severe in vitro jejunal disaccharidase deficiency. In vivo hydrolysis of lactose, sucrose, and palatinose was impaired in 25%-75% of patients, apart from HIV well patients, who were normal. The prevalence of the in vivo lactase and sucrase deficiency was significantly (P < 0.006) lower than in vitro and severe in about 30%.

CONCLUSIONS

Intestinal disaccharidase deficiency is common both in vitro and in vivo in HIV-seropositive patients but sufficiently severe to consider lactose withdrawal only in about a quarter of the patients with AIDS and diarrhoea.

A quantitative evaluation of the permeability of the blood brain barrier of portacaval shunted rats

The integrity of the blood-brain barrier (BBB) was measured in male Sprague Dawley rats subjected to 16 weeks of portacaval shunting (PCS), the optimal time required for the cerebral changes to develop, by using an in situ brain perfusion technique. The penetration of a vascular space marker 14C mannitol, and labelled amino acids 3H-phenylalanine or 3H-glutamate were measured in brain and cerebrospinal fluid (CSF) using an in situ brain perfusion technique, over 2 or 20 minutes. The patency of the surgical shunt was confirmed by measurement of significantly increased plasma ammonia (131.5 +/- 14.8 micromol x l(-1)) and AST (159.5 +/- 19.9 IU x l(-1)) concentrations compared to controls 39.9 +/- 3.7*, and 82.5 +/- 6.6* respectively. Brain and CSF 14C-mannitol space (ml x 100g(-1)), was not increased by PCS where brain space was 1.31 +/- 0.27 mL x 100g(-1) compared to control 1.19 +/- 0.49 mL x 100g(-1), and CSF was 0.14 +/- 0.06 mL x 100g(-1) compared to control 0.15 +/- 0.05 (PCS n=10, control n=8). The uptake for 3H-glutamate, which is required for cerebral ammonia detoxification, was also unchanged in both brain and CSF. However, brain uptake of 3H-phenylalanine was significantly reduced from 871 +/- 80 microL x min(-1) x g(-1) to 356 +/- 154* microl x min(-1) x g(-1) (n=4), although there was no change in CSF uptake. These data suggest that there is no generalized breakdown of the blood-brain or blood-CSF barriers during PCS as assessed by mannitol penetration. The reduction in phenylalanine uptake into the brain may help stabilize high cerebral aromatic amino acid levels. *P<0.05, Two-tailed, Student's unpaired t-test.

Effect of perfusate albumin on organ viability and vascular responses in the in vitro dual-perfused rat liver

Inclusion of albumin in the perfusate has been previously shown to be detrimental to liver function, but its effect on hepatic vascular reactivity remains unknown. The aim of this study was to determine the effects of albumin on hepatic arterial vascular reactivity and liver viability in the isolated dual-perfused rat liver. A total of 12 rat livers were perfused with Krebs-Bülbring buffer without (Group 1) and with (Group 2) addition of 1% bovine serum albumin (BSA) through the hepatic artery and portal vein for up to 5 h. Hepatic arterial responses to acetylcholine and sodium nitroprusside were studied at 30-min intervals. Liver viability was assessed by bile volume production, release of aspartate serine aminotransferase (AST) and lactic acid dehydrogenase (LDH), and histological examination. Hepatic arterial responses to acetylcholine were significantly attenuated in Group 2. No significant differences in sodium nitroprusside responses were noted. However, bile volume production in Group 2 was significantly decreased compared to Group 1. Effluent AST and LDH release increased significantly in Group 1 but not in Group 2. Histological results showed that sinusoidal endothelial cells and hepatocytes were well preserved without significant deterioration in either group, although there was a marked decrease in vasodilatation to acetylcholine in Group 2. This data suggested that the presence of albumin in the perfusate did not improve retention of smooth muscle reactivity and reduced endothelium-dependent vasodilatation and bile volume production during perfusion. However, improved liver parenchymal cell function was observed.

Trait hostility and prolactin response to tryptophan enhancement/depletion

This study investigated the relationship between trait hostility and aspects of serotonergic function by assessing the prolactin (PRL) response to acute tryptophan depletion and enhancement in 28 healthy male volunteers. Serum PRL was assessed immediately before, and 4.5 h after, administration of an amino acid drink enhanced with, or depleted of, the 5-HT precursor tryptophan. Trait hostility and DeltaPRL (value at 4.5 h minus baseline) correlated negatively following enhancement and positively following depletion, indicating that the higher the hostility the smaller the change in PRL in either direction. This is consistent with previous research reporting an association between aggression and blunted neuroendocrine responses to serotonergic agents. The results indicate the possibility that, in people high on hostility, part of the serotonergic pathway that leads to modulation of PRL release is characterised by a stage with either low capacity relative to input availability or a strong negative feedback component.

Plasma tryptophan and trait aggression

Many studies have reported correlations between measures of aggression and indices of serotonergic function, but most have studied patient or offender populations and relatively few have investigated plasma concentrations of the serotonin precursor tryptophan. This study investigates the relationship between plasma concentrations of tryptophan and trait hostility, depression and anxiety in male healthy volunteers. Sixty-seven healthy male volunteers gave blood samples and completed trait questionnaires. Plasma tryptophan was positively correlated with the Buss-Durkee Hostility Inventory Total score and Motor Aggression subscale, but not with the Attitudinal Hostility subscale or with trait anxiety or depression. In conclusion, there is evidence for an association between high concentrations of plasma tryptophan and aggressive behaviour in men, presumably mediated by some aspect of central serotonergic function, which seems unlikely to be explained by high trait anxiety or depression.

Screening for hypercholesterolaemia in 10,000 neonates in a multi-ethnic population

An immunoassay was developed for the detection of hypercholesterolaemia in dried blood spots collected from 6-day-old neonates. Blood spot samples (9,673) were subjected to immunoturbidimetric assay to determine the levels of apolipoprotein B (apoB), an index of plasma low density lipoprotein, and of apolipoprotein A-1 (apoA-1), an index of plasma high density lipoprotein. Infants with raised apoB or a reduced apoA-1/apoB ratio were recalled, retested and, if appropriate, referred to the Vascular Risk Clinic at King's College Hospital for medical management. A total of 189 were recalled for further testing; of whom 82 (45%) attended the recall clinic. A group of 16 families (24 individuals) had abnormal lipid profiles; of these, 7 families (14 individuals) had lipid profiles consistent with inherited hypercholesterolaemia.

CONCLUSION

Neonatal screening for hypercholesterolaemia using blood spot apolipoprotein measurements is feasible but ethnic variations in disease prevalence must be considered in the design of a screening programme.

Small intestinal transit, absorption, and permeability in patients with AIDS with and without diarrhoea

BACKGROUND

Diarrhoea in AIDS is associated with anorexia and weight loss. The importance of gastrointestinal transit in such symptoms has not been addressed.

AIMS

To assess jejunal to caecal transit times in subjects with AIDS related diarrhoea and weight loss and correlate these with measures of absorptive capacity and intestinal permeability.

METHODS

Jejunal to caecal transit times were assessed in 20 seronegative controls and 60 HIV seropositive subjects from serum analysis of 3-O-methyl-D-glucose and sulphapyridine after ingestion of the monosaccharide and sulphasalazine in aqueous solution. The method also allows an estimation of gastric emptying times for liquids. Intestinal absorptive capacity and permeability were assessed by a combined test using 3-O-methyl-D-glucose, D-xylose, L-rhamnose, and lactulose.

RESULTS

Gastric emptying was significantly delayed in all groups of patients with AIDS. Mean jejunal to caecal transit times were not significantly different between controls (246 (62) minutes) and patients without diarrhoea (AIDS, well: 278 (103) minutes; AIDS, wasting: 236 (68) minutes), cytomegalovirus colitis (289 (83) minutes), pathogen negative diarrhoea (192 (100) minutes), or microsporidiosis (190 (113) minutes), although 30% of patients had values below the control range. Patients with cryptosporidiosis differed significantly from controls (135 (35) minutes, p<0.0001), seven of 10 having rapid transit times. Absorptive capacity was reduced and intestinal permeability significantly increased in AIDS, but did not correlate significantly with transit times.

CONCLUSION

Small bowel transit is accelerated in many patients with AIDS, particularily in protozoal diarrhoea, but is not the sole explanation for malabsorption of monosaccharides.

Correlation of endothelium-dependent and -independent vasodilatation with liver function tests during prolonged perfusion of the rat liver

Twelve male Wistar rats were anaesthetized with pentobarbitone (3 mg 100g(-1) i.p.), the livers were excised and perfused in vitro through the hepatic artery and portal vein at constant flow rates of 0.32+/-0.01 (mean+/-S.E.) and 0.98+/-0.03 ml min(-1) g liver(-1), respectively. The tone of the preparation was raised by methoxamine (7.5 x 10(-6) M). Responses to mid-range doses of acetylcholine (-11 log mol) and sodium nitroprusside (-9 log mol) produced submaximal degrees of vasodilatation (-log mol ED50 = 12.18+/-0.08) and (-log mol ED50 = 9.95+/-0.23), respectively, which did not subside until 5.5 h of perfusion. These did not coincide with the increase in activities of lactic acid dehydrogenase (LDH) and aspartate serine transaminase (AST) activity at 2.5 h, which were indicative of hepatocellular mitochondrial and cytoplasmic damage, respectively. Vascular responses suggested that there was little deterioration in endothelial or smooth muscle function in the hepatic artery up to 5 h perfusion. This model can be reliably used to investigate endothelium-dependent and -independent vasodilators in vascular pharmacological studies of the rat liver although some minimal increases may occur in AST and LDH activity before hemodynamic changes appear at 5.5 h.

Central cooling effects in patients with hypercholesterolaemia

1. A prospective study has been carried out, and 68 patients with hypercholesterolaemia have been investigated to study the effects of central cooling on serum lipid levels. 2. Central cooling was obtained by the exposure of the whole body to cold water. All patients were trained to gradually reduce the water temperature from 22 to 14 degrees C and to increase the time of exposure from 5 to 20 min over a period of 90 days. The 33 male and 35 female patients were aged between 40 and 60 years at entry with total cholesterol of 6.0 mmol/l or greater and low-density lipoprotein (LDL)-cholesterol of 4. 0 mmol/l or greater. Thyroid-stimulating hormone, free thyroxine (FT4), total T3, total cholesterol, LDL-cholesterol, high-density lipoprotein (HDL)-cholesterol, triacylglycerols and total fat mass (determined by dual-energy X-ray absorptiometry scan) were obtained at baseline and after 3 months treatment with hydrotherapy. 3. Central cooling obtained by hydrotherapy results in a median fall in tympanic temperature from 0.2 degrees C (P<0.001) to 0.8 degrees C (P<0.001). We have observed in these patients a significant reduction in total cholesterol (-0.2 mmol/l, P=0.006) and LDL-cholesterol (-0.2 mmol/l, P=0.004). Serum FT4 level was higher than baseline results in 30 of these hypercholesterolaemic patients (15.5 pmol/l to 17.3 pmol/l) and there was no significant change in serum thyroid-stimulating hormone and total T3. 4. In conclusion, in our patients with hypercholesterolaemia we have observed a significant reduction of total cholesterol and LDL-cholesterol after body temperature regulation.