Early non-neutralizing, afucosylated antibody responses are associated with COVID-19 severity

A damaging inflammatory response is implicated in the pathogenesis of severe coronavirus disease 2019 (COVID-19), but mechanisms contributing to this response are unclear. In two prospective cohorts, early non-neutralizing, afucosylated immunoglobulin G (IgG) antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were associated with progression from mild to more severe COVID-19. To study the biology of afucosylated IgG immune complexes, we developed an in vivo model that revealed that human IgG-Fc-gamma receptor (FcγR) interactions could regulate inflammation in the lung. Afucosylated IgG immune complexes isolated from patients with COVID-19 induced inflammatory cytokine production and robust infiltration of the lung by immune cells. In contrast to the antibody structures that were associated with disease progression, antibodies that were elicited by messenger RNA SARS-CoV-2 vaccines were highly fucosylated and enriched in sialylation, both modifications that reduce the inflammatory potential of IgG. Vaccine-elicited IgG did not promote an inflammatory lung response. These results show that human IgG-FcγR interactions regulate inflammation in the lung and define distinct lung activities mediated by the IgG that are associated with protection against, or progression to, severe COVID-19.

Vitamin D kinetics in nonpregnant and pregnant women after a single oral dose of trideuterated vitamin D3

The plasma pool of the hormone 1,25-dihydroxyvitamin D (1,25(OH)₂D) is increased throughout most of human pregnancy. Mechanisms behind this adaptation are unclear, in part due to limited data on vitamin D kinetics during pregnancy. Stable isotopes make it possible to study vitamin D kinetics in vulnerable study populations like pregnant women. We conducted a pilot study of vitamin D kinetics in nonpregnant and pregnant women. We evaluated a clinical protocol and developed analytical methods to assess the serum appearance and disappearance of trideuterated vitamin D₃ (d3-vitamin D₃) and trideuterated 25-hydroxyvitamin D₃ (d3-25(OH)D₃) after a single oral dose of 25 μg of [6,19,19-²H]-vitamin D₃ (d3-vitamin D₃). Blood was collected at baseline and 2, 4, 6, 24, 168, 264, and 456 hours post-dosing. We then described the serum kinetic profiles of d3-vitamin D₃ and d3-25(OH)D₃ in nonpregnant and pregnant women. Serum kinetic profiles of d3-vitamin D₃ and d3-25(OH)D₃ followed a time course in line with previous pharmacokinetic studies. There was marked variability between participants in the area under the concentration-time curve (AUC) of d3-25(OH)D₃ over the 20-day study period. This AUC of d3-25(OH)D₃ was positively correlated with the serum vitamin D binding protein (DBP) concentration, which was higher in pregnant compared with nonpregnant women. The mean serum half-life of 25(OH)D₃ was longer but not significantly different in pregnant women (18.8 days) compared with nonpregnant women (13.6 days). Our pilot study demonstrated that a single oral dose of 25 μg of d3-vitamin D₃ can be used to study vitamin D kinetics. Serum DBP concentration is an important predictor of vitamin D kinetics, and more research is needed to fully understand the significance of elevated DBP concentration during pregnancy.

Structurally and functionally distinct early antibody responses predict COVID-19 disease trajectory and mRNA vaccine response

A damaging inflammatory response is strongly implicated in the pathogenesis of severe COVID-19 but mechanisms contributing to this response are unclear. In two prospective cohorts, early non-neutralizing, afucosylated, anti-SARS-CoV-2 IgG predicted progression from mild, to more severe COVID-19. In contrast to the antibody structures that predicted disease progression, antibodies that were elicited by mRNA SARS-CoV-2 vaccines were low in Fc afucosylation and enriched in sialylation, both modifications that reduce the inflammatory potential of IgG. To study the biology afucosylated IgG immune complexes, we developed an in vivo model which revealed that human IgG-FcγR interactions can regulate inflammation in the lung. Afucosylated IgG immune complexes induced inflammatory cytokine production and robust infiltration of the lung by immune cells. By contrast, vaccine elicited IgG did not promote an inflammatory lung response. Here, we show that IgG-FcγR interactions can regulate inflammation in the lung and define distinct lung activities associated with the IgG that predict severe COVID-19 and protection against SARS-CoV-2.

ONE SENTENCE SUMMARY

Divergent early antibody responses predict COVID-19 disease trajectory and mRNA vaccine response and are functionally distinct in vivo .

Proinflammatory IgG Fc structures in patients with severe COVID-19

Severe acute respiratory syndrome coronavirus 2 infections can cause coronavirus disease 2019 (COVID-19), which manifests with a range of severities from mild illness to life-threatening pneumonia and multi-organ failure. Severe COVID-19 is characterized by an inflammatory signature, including high levels of inflammatory cytokines, alveolar inflammatory infiltrates and vascular microthrombi. Here we show that patients with severe COVID-19 produced a unique serologic signature, including an increased likelihood of IgG1 with afucosylated Fc glycans. This Fc modification on severe acute respiratory syndrome coronavirus 2 IgGs enhanced interactions with the activating Fcγ receptor FcγRIIIa; when incorporated into immune complexes, Fc afucosylation enhanced production of inflammatory cytokines by monocytes, including interleukin-6 and tumor necrosis factor. These results show that disease severity in COVID-19 correlates with the presence of proinflammatory IgG Fc structures, including afucosylated IgG1.

Proinflammatory IgG Fc structures in patients with severe COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can cause Coronavirus Disease 2019 (COVID-19), which manifests with a range of severities from mild illness to life threatening pneumonia and multi-organ failure. Severe COVID-19 is characterized by an inflammatory signature including high levels of inflammatory cytokines, alveolar inflammatory infiltrates and vascular microthrombi. Here we show that severe COVID-19 patients produced a unique serologic signature, including increased IgG1 with afucosylated Fc glycans. This Fc modification on SARS-CoV-2 IgGs enhanced interactions with the activating FcγR, FcγRIIIa; when incorporated into immune complexes, Fc afucosylation enhanced production of inflammatory cytokines by monocytes, including IL-6 and TNF. These results show that disease severity in COVID-19 correlates with the presence of afucosylated IgG1, a pro-inflammatory IgG Fc modification.

Maternal Anti-Dengue IgG Fucosylation Predicts Susceptibility to Dengue Disease in Infants

Infant mortality from dengue disease is a devastating global health burden that could be minimized with the ability to identify susceptibility for severe disease prior to infection. Although most primary infant dengue infections are asymptomatic, maternally derived anti-dengue immunoglobulin G (IgGs) present during infection can trigger progression to severe disease through antibody-dependent enhancement mechanisms. Importantly, specific characteristics of maternal IgGs that herald progression to severe infant dengue are unknown. Here, we define ≥10% afucosylation of maternal anti-dengue IgGs as a risk factor for susceptibility of infants to symptomatic dengue infections. Mechanistic experiments show that afucosylation of anti-dengue IgGs promotes FcγRIIIa signaling during infection, in turn enhancing dengue virus replication in FcγRIIIa+ monocytes. These studies identify a post-translational modification of anti-dengue IgGs that correlates with risk for symptomatic infant dengue infections and define a mechanism by which afucosylated antibodies and FcγRIIIa enhance dengue infections.

Serum Proteomics on the Basis of Discovery of Predictive Biomarkers of Response to Androgen Deprivation Therapy in Advanced Prostate Cancer

BACKGROUND

We investigated the serum proteome of hormone-sensitive prostate cancer patients to determine candidate biomarkers associated with androgen deprivation therapy (ADT) efficacy.

PATIENTS AND METHODS

Serum proteomes generated using isobaric mass tags for relative and absolute quantitation were analyzed using reverse-phase liquid chromatography coupled to tandem mass spectrometry. The advanced hormone-sensitive prostate cancer cohorts studied were: (1) untreated "paired" pre-ADT and 4-month post-ADT hormone-sensitive patients (n = 15); (2) "early ADT failure" patients (n = 10) in whom ADT treatment failed within a short period of time; and (3) "late ADT failure" patients (n = 10) in whom ADT treatment failed after a prolonged response time. Differential abundance was assessed, and ingenuity pathway analysis (IPA) was used to identify interaction networks in selected candidates from these comparisons.

RESULTS

Between "post-ADT" and combined "early" and "late" ADT failure groups 149 differentially detected candidates were observed, and between "early" and "late" ADT failure groups 98 candidates were observed; 47 candidates were common in both comparisons. IPA network enrichment analysis of the 47 candidates identified 3 interaction networks (P < .01) including 17-β-estradiol, nuclear factor kappa-light-chain enhancer of activated B cells complex, and P38 mitogen-activated protein kinases as pathways with potential markers of response to ADT.

CONCLUSION

A global proteomic analysis identified pathways with markers of ADT response, which will need validation in independent data sets.

Time Transfer by Laser Link (T2L2) in Noncommon View Between Europe and China

The Time Transfer by Laser Link (T2L2) project allows for the synchronization of remote ultrastable clocks over intercontinental distances. The principle is derived from the satellite laser ranging technology with a dedicated space equipment designed to record arrival times of laser pulses at the satellite. The space segment was launched in 2008 as a passenger instrument on the ocean altimetry satellite Jason 2. For the first time, we have conducted by the end of 2016 a dedicated time transfer comparison campaign between Global Positioning System and T2L2 over intercontinental distances. The campaign was carried out between two laboratories in Europe and two in China. The campaign has demonstrated a consistency of the time transfer techniques at the 1-ns level, together with the confirmation of a subnanosecond level for continental distances.

An Evaluation of a Level-One Instructional Videodisc Program

In this project, a Level 1 videodisc program called “Mastering Fractions” was evaluated. The evaluation was conducted in two parts. Part 1 was a controlled study that compared the “Mastering Fractions” program to a more traditional fractions curriculum while controlling for any novelty effect of the videodisc medium. Part 2 of the evaluation was a descriptive study that examined the use of “Mastering Fractions” in non-experimentally controlled classroom environments. The results of the evaluation indicated that the use of the “Mastering Fractions” program resulted in significant gains in fraction skills and computations. Further, it was concluded that the achievement gains found in the study were attributed to the instructional content of the “Mastering Fractions” program and not to the novelty of the videodisc medium. Finally, it was found that even though the program had a positive effect on student achievement, the effectiveness of “Mastering Fractions,” like other instructional programs, is somewhat dependent upon the commitment and quality of the teacher using the materials.

A dimeric PR-1-type pathogenesis-related protein interacts with ToxA and potentially mediates ToxA-induced necrosis in sensitive wheat

A dimeric PR-1-type pathogenesis-related protein (PR-1-5), recently identified in wheat, was found to interact with Stagonospora nodorum ToxA in both yeast two-hybrid and co-immunoprecipitation assays. Site-specific mutational analyses revealed that the RGD motif of ToxA is not targeted by PR-1-5, whereas two surface-exposed asparagine residues are essential for the interaction: the N102 residue of the turning loop between β2 and β3 in ToxA and the N141 residue of the turning loop between βC and βD in PR-1-5. Recombinant PR-1-5 and ToxA mutant proteins carrying alanine substitutions at the interacting sites were expressed in Pichia pastoris, together with the wild-type proteins. Native polyacrylamide gel electrophoresis (PAGE) confirmed that the PR-1-5-N141A mutant retains the ability to form dimers. Plant assays indicated that the ToxA-N102A mutant fails to induce necrosis, whereas the PR-1-5-N141A mutant is impaired in the 'necrosis-promoting' activity shown by the wild-type PR-1-5 when co-infiltrated with ToxA in sensitive wheat. Reverse transcriptase-polymerase chain reaction and Western blot analyses revealed that the native PR-1-5 protein is differentially expressed between ToxA-sensitive and ToxA-insensitive wheat lines in response to ToxA treatment. These results suggest that PR-1-5 is a potential target of ToxA and the site-specific interaction between PR-1-5 and ToxA may mediate ToxA-induced necrosis in sensitive wheat.

A workflow for large-scale empirical identification of cell wall N-linked glycoproteins of tomato (Solanum lycopersicum) fruit by tandem mass spectrometry

Glycosylation is a common PTM of plant proteins that impacts a large number of important biological processes. Nevertheless, the impacts of differential site occupancy and the nature of specific glycoforms are obscure. Historically, characterization of glycoproteins has been difficult due to the distinct physicochemical properties of the peptidyl and glycan moieties, the variable and dynamic nature of the glycosylation process, their heterogeneous nature, and the low relative abundance of each glycoform. In this study, we explore a new pipeline developed for large-scale empirical identification of N-linked glycoproteins of tomato fruit as part of our ongoing efforts to characterize the tomato secretome. The workflow presented involves a combination of lectin affinity, tryptic digestion, ion-pairing HILIC, and precursor ion-driven data-dependent MS/MS analysis with a script to facilitate the identification and characterization of occupied N-linked glycosylation sites. A total of 212 glycoproteins were identified in this study, in which 26 glycopeptides from 24 glycoproteins were successfully characterized in just one HILIC fraction. Further precursor ion discovery-based MS/MS and deglycosylation followed by high accuracy and resolution MS analysis were used to confirm the glycosylation sites and determine site occupancy rates. The workflow reported is robust and capable of producing large amounts of empirical data involving N-linked glycosylation sites and their associated glycoforms.

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.

Modeling low-dose mortality and disease incubation period of inhalational anthrax in the rabbit

There is a need to advance our ability to conduct credible human risk assessments for inhalational anthrax associated with exposure to a low number of bacteria. Combining animal data with computational models of disease will be central in the low-dose and cross-species extrapolations required in achieving this goal. The objective of the current work was to apply and advance the competing risks (CR) computational model of inhalational anthrax where data was collected from NZW rabbits exposed to aerosols of Ames strain Bacillus anthracis. An initial aim was to parameterize the CR model using high-dose rabbit data and then conduct a low-dose extrapolation. The CR low-dose attack rate was then compared against known low-dose rabbit data as well as the low-dose curve obtained when the entire rabbit dose-response data set was fitted to an exponential dose-response (EDR) model. The CR model predictions demonstrated excellent agreement with actual low-dose rabbit data. We next used a modified CR model (MCR) to examine disease incubation period (the time to reach a fever >40 °C). The MCR model predicted a germination period of 14.5h following exposure to a low spore dose, which was confirmed by monitoring spore germination in the rabbit lung using PCR, and predicted a low-dose disease incubation period in the rabbit between 14.7 and 16.8 days. Overall, the CR and MCR model appeared to describe rabbit inhalational anthrax well. These results are discussed in the context of conducting laboratory studies in other relevant animal models, combining the CR/MCR model with other computation models of inhalational anthrax, and using the resulting information towards extrapolating a low-dose response prediction for man.

Dimerization and protease resistance: new insight into the function of PR-1

The group 1 pathogenesis-related (PR-1) proteins have long been considered hallmarks of hypersensitive response/defense pathways in plants, but their biochemical functions are still obscure despite resolution of the NMR/X-ray structures of several PR-1-like proteins, including P14a (the prototype PR-1). We report here the characterization of two basic PR-1 proteins (PR-1-1 and PR-1-5) recently identified from hexaploid wheat (Triticum aestivum). Both proteins were expressed in Pichia pastoris as a single major species of ∼15 kDa. Sequence identity of the expressed PR-1 proteins was verified by MALDI-TOF/TOF analysis. Accumulation of the native PR-1-5 protein in pathogen-challenged wheat was confirmed by protein gel blot analysis. Low-temperature SDS-PAGE and yeast two-hybrid assays revealed that PR-1-1 exists primarily as a monomer whereas PR-1-5 forms homodimers. Both PR-1 proteins are resistant to proteases compared to bovine serum albumin, but PR-1-1 shows resistance mainly to subtilisin and protease K (serine proteases) whereas PR-1-5 shows resistance to subtilisin, protease K and papain (a cysteine protease). Site-specific mutations at the five putative active sites in the PR-1 domain all affected dimerization, with the mutations at Glu-72 and Glu-102 (in the PR-1-5 numeration) also diminishing protease resistance. Sequence analysis revealed that the Glu-72 and Glu-102 residues are located in motif-like sequences that are conserved in both PR-1 and the human apoptosis-related caspase proteins. These findings prompt us to examine the function of PR-1 for a role in protease-mediated programmed cell death pathways in plants.

Identification of ADP-ribosylation sites of CD38 mutants by precursor ion scanning mass spectrometry

Protein ADP-ribosylation, including mono- and poly-ADP-ribosylation, is increasingly recognized to play important roles in various biological pathways. Molecular understanding of the functions of ADP-ribosylation requires the identification of the sites of modification. Although tandem mass spectrometry (MS/MS) is widely recognized as an effective means for determining protein modifications, identification of ADP-ribosylation sites has been challenging due to the labile and hydrophilic nature of the modification. Here we applied precursor ion scanning-triggered MS/MS analysis on a hybrid quadrupole linear ion trap mass spectrometer for selectively detecting ADP-ribosylated peptides and determining the auto-ADP-ribosylation sites of CD38 (cluster of differentiation 38) E226D and E226Q mutants. CD38 is an enzyme that catalyzes the hydrolysis of nicotinamide adenine dinucleotide (NAD) to ADP-ribose. Here we show that NAD can covalently label CD38 E226D and E226Q mutants but not wild-type CD38. In this study, we have successfully identified the D226/Q226 and K129 residues of the two CD38 mutants being the ADP-ribosylation sites using precursor ion scanning hybrid quadrupole linear ion trap mass spectrometry. The results offer insights about the CD38 enzymatic reaction mechanism. The precursor ion scanning method should be useful for identifying the modification sites of other ADP-ribosyltransferases such as poly(ADP-ribose) polymerases.

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.

Clinical and pathologic features of cynomolgus macaques (Macaca fascicularis) infected with aerosolized Yersinia pestis

Since the anthrax attacks of 2001, the emphasis on developing animal models of aerosolized select agent pathogens has increased. Many scientists believe that nonhuman primate models are the most appropriate to evaluate pulmonary response to, vaccines for, and treatments for select agents such as Yersinia pestis (Y. pestis), the causative agent of plague. A recent symposium concluded that the cynomolgus macaque (Macaca fascicularis) plague model should be characterized more fully. To date, a well-characterized cynomolgus macaque model of pneumonic plague using reproducible bioaerosols of viable Y. pestis has not been published. In the current study, methods for creating reproducible bioaerosols of viable Y. pestis strain CO92 (YpCO92) and pneumonic plague models were evaluated in 22 Indonesian-origin cynomolgus macaques. Five macaques exposed to doses lower than 250 CFU remained free of any indication of plague infection. Fifteen macaques developed fever, lethargy, and anorexia indicative of clinical plague. The 2 remaining macaques died without overt clinical signs but were plague-positive on culture and demonstrated pathology consistent with plague. The lethal dose of plague in humans is reputedly less than 100 organisms; in this study, 66 CFU was the dose at which half of the macaques developed fever and clinical signs (ED(50)), The Indonesian cynomolgus macaque reproduces many aspects of human pneumonic plague and likely will provide an excellent model for studies that require a macaque model.

A plant-produced plague vaccine candidate confers protection to monkeys

Production of vaccine antigens in plants has received considerable attention over the last decade. However, despite many antigens being expressed in plant systems, and promising efficacy data with rodent models, few vaccine candidates have advanced into studies in non-human primates or human clinical trials. Here, we report on the transient expression of the F1 and LcrV antigens of Yersinia pestis in Nicotiana benthamiana. The antigens were expressed as fusions to the thermostable enzyme of Clostridium thermocellum. When administered to Cynomolgus Macaques the purified plant-produced antigens induced serum IgG and IgA responses specific to F1 and LcrV, and conferred complete protection against lethal challenge with Y. pestis. This study clearly demonstrates the efficacy of a plant-produced plague vaccine candidate in a primate model.

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.