bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-invasive measurement of pulmonary blood flow during prone positioning in patients with early acute respiratory distress syndrome
Authors: REUTERSHAN Jörg , SCHMITT Andre , DIETZ Klaus , FRETSCHNER Reinhold
Published: January 2004

In the daily clinical routine at the bedside, information on effective pulmonary blood flow (PBF) is limited and requires invasive monitoring, including a pulmonary artery catheter, to determine both cardiac output and intrapulmonary shunt. Therefore we evaluated a non-invasive method for the measurement of PBF in a clinical setting, including 12 patients with acute respiratory failure (acute respiratory distress syndrome) undergoing prone positioning. PBF was determined before (baseline), during and after prone positioning, by using a foreign gas rebreathing method with a new photoacoustic gas analyser. Values were compared with the cardiac output corrected for intrapulmonary shunt (COeff). Responders to prone positioning were defined according to the improvement of arterial oxygenation. A total of 84 measurements were performed. PBF values correlated well with COeff (R2=0.96; P<0.0001). Bias and limits of agreement (±2 S.D.) for all measurements were -0.11±0.76 litre/min. At baseline, responders showed significantly lower PBF levels than non-responders (4.8±1.0 compared with. 6.4±1.2 litre/min; P=0.03). During prone positioning, PBF increased continuously in responders and remained high after patients had been returned to the supine position. PBF was unaffected in non-responders. Mean total increase in PBF was 1.2±0.2 litre/min in responders compared with -0.4±0.2 litre/min in non-responders (P<0.0001). In conclusion, the investigated rebreathing system allows for a non-invasive determination of PBF at the bedside. The accuracy of the measurements is comparable with the thermodilution method. It is able to reliably reflect changes in PBF induced by prone positioning. Moreover, measuring PBF might be a promising tool to identify responders to prone therapy.
The role of carotid chemoreceptors in the sympathetic activation by adenosine in humans
Authors: TIMMERS Henri J. L. M. , RONGEN Gerard A. , KAREMAKER John M. , WIELING Wouter , MARRES Henri A. M. , LENDERS Jacques W. M.
Published: January 2004

The direct vasodilatory and negative chronotropic effects of adenosine in humans are counterbalanced by a reflex increase in sympathetic nerve traffic. A suggested mechanism for this reflex includes peripheral chemoreceptor activation. We, therefore, assessed the contribution of carotid chemoreceptors to sympatho-excitation by adenosine. Muscle sympathetic nerve activity was recorded during adenosine infusion (140 µg·kg-1·min-1 for 5 min) in five patients lacking carotid chemoreceptors after bilateral carotid body tumour resection (one male and four female, mean age 51±11 years) and in six healthy controls (two male and four female, mean age 50±7 years). Sympathetic responses to sodium nitroprusside injections were assessed to measure baroreceptor-mediated sympathetic activation. In response to adenosine, controls showed no change in blood pressure, an increase in heart rate (+48.2±13.2%; P<0.003) and an increase in sympathetic nerve activity (+195±103%; P<0.022). In contrast, patients showed a decrease in blood pressure (-14.6±4.9/-17.6±6.0%; P<0.05), an increase in heart rate (+25.3±8.4%; P<0.032) and no significant change in sympathetic activity. Adenosine-induced hypotension in individual patients elicited less sympathetic activation than equihypotensive sodium nitroprusside injections. In humans lacking carotid chemoreceptors, adenosine infusion elicits hypotension due to the absence of significant sympatho-excitation. Chemoreceptor activation is essential for counterbalancing the direct vasodilation by adenosine. In addition, blunting of the baroreflex sympathetic response to adenosine-induced hypotension may indicate a direct sympatho-inhibitory effect of adenosine.
Changes in plasma lipids and markers of oxidative stress in normal pregnancy and pregnancies complicated by diabetes
Authors: TOESCU V. , NUTTALL S. L. , MARTIN U. , NIGHTINGALE P. , KENDALL M. J. , BRYDON P. , DUNNE F.
Published: January 2004

The purpose of the present study was to determine changes in plasma lipids and markers of oxidative stress longitudinally in pregnancy complicated by diabetes compared with non-diabetic pregnancy. This was carried out by following a group of normal pregnant women (n=17) and groups of pregnant women with Type I diabetes (n=19), Type II diabetes (n=12) and gestational diabetes mellitus (n=12) throughout pregnancy, with sampling carried out at the end of each trimester. Serum total cholesterol and triacylglycerols (triglycerides) were determined using standard colorimetric techniques and low-density lipoprotein (LDL) subfraction profile by disc PAGE. Total antioxidant capacity (TAC) was determined by enhanced chemiluminescence and lipid hydroperoxides by the ferrous oxidation of Xylenol Orange method. Total cholesterol and triacylglycerols increased significantly throughout pregnancy in all groups, but there were no significant differences between normal and diabetic women with respect to either. The LDL score was significantly higher (P<0.001) in diabetic women compared with normal women at each point throughout pregnancy, although there were no significant differences between the diabetic groups. There was evidence of greater oxidative stress in diabetic compared with normal women throughout. Corrected TAC was significantly lower (P<0.001) in all diabetic women throughout pregnancy. In addition, lipid hydroperoxides were higher in all diabetic compared with normal women, particularly so in those with Type II diabetes (P<0.05). These changes may have important implications for diabetic women during pregnancy, as an elevated risk of pre-eclampsia is thought to reflect an oxidative stress-related mechanism. In addition, these changes may have important implications for the development of atherosclerosis and the long-term cardiovascular health of women with diabetes.
C-reactive protein, cardiovascular risk, and renal disease in a remote Australian Aboriginal community
Authors: McDONALD Stephen , MAGUIRE Graeme , DUARTE Natalia , WANG Xing Li , HOY Wendy
Published: January 2004

Rates of cardiovascular and renal disease in Australian Aboriginal communities are high, but we do not know the contribution of inflammation to these diseases in this setting. In the present study, we sought to examine the distribution of C-reactive protein (CRP) and other markers of inflammation and their relationships with cardiovascular risk markers and renal disease in a remote Australian Aboriginal community. The study included 237 adults (58% of the adult population) in a remote Aboriginal community in the Northern Territory of Australia. Main outcome measures were CRP, fibrinogen and IgG concentrations, blood pressure (BP), presence of diabetes, lipids, albuminuria, seropositivity to three common micro-organisms, as well as carotid intima-media thickness (IMT). Serum concentrations of CRP [7 (5–13) mg/l; median (inter-quartile range)] were markedly increased and were significantly correlated with fibrinogen and IgG concentrations and inversely correlated with serum albumin concentration. Higher CRP concentrations were associated with IgG seropositivity to Helicobacter pylori and Chlamydia pneumoniae and higher IgG titre for cytomegalovirus. Higher CRP concentrations were associated with the following: the 45–54-year age group, female subjects, the presence of skin sores, higher body mass index, waist circumference, BP, glycated haemoglobin and greater albuminuria. CRP concentrations increased with the number of cardiovascular risk factors, carotid IMT and albuminuria independently of other risk factors. These CRP concentrations were markedly higher than described in other community settings and are probably related, in a large part, to chronic and repeated infections. Their association with markers of cardiovascular risk and renal disease are compatible with the high rates of cardiovascular and renal disease in this community, and provide more evidence of strong links between these conditions, through a shared background of infection/inflammation. This suggests that a strong focus on prevention and management of infections will be important in reducing these conditions, in addition to interventions directed at more traditional risk factors.
Moderate hyperalphalipoproteinaemia in a Brazilian population is related to lipoprotein lipase activity, apolipoprotein A-I concentration, age and body mass index
Authors: ALARCON Samira B. K. , OLIVEIRA Helena C. F. , HARADA Lila M. , NUNES Valéria S. , KAPLAN Denise , QUINTÃO Eder C. R. , DE FARIA Eliana C.
Published: January 2004

We investigated 95 Brazilian adults, aged 21–79 years, who were divided into two groups defined as having high-density lipoprotein (HDL)-cholesterol concentrations above [hyperalphalipoproteinaemia (HALP); n=48] or below (controls; n=47) the 90th percentile of a local population. The activities of lipid transfer proteins and enzymes involved in the plasma reverse cholesterol transport and the prevalence of factors that modulate HDL metabolism (alcohol consumption, ponderosity, physical exercise, menopause and use of hormone replacement treatment in women and smoking) were measured, as well as the prevalence of cardiovascular disease and of its various risk factors. The two groups showed no differences in their frequencies of cardiovascular disease. The HDL2/HDL3-cholesterol and triacylglycerol (triglyceride) ratios and the activities of the phospholipid transfer protein (PLTP) and cholesteryl ester transfer protein (CETP) were similar in both groups. Lipoprotein lipase (LPL) and hepatic lipase (HL) activities were 35% higher (P=0.0002) and 40% lower (P=0.0006) respectively, in HALP compared with control subjects. In a multivariate analysis, HDL-cholesterol and its subfractions were influenced by LPL, apolipoprotein A-I, age (negative relationship) and body mass index (negative relationship). Use of alcohol and ponderosity, as well as the interaction of these factors, explained the LPL activity. HL activity was modulated by smoking, and hormone-replacement therapy influenced the apolipoprotein A-I concentration. CETP activity was influenced by race and PLTP by age. The unique phenotype found in this Brazilian HALP population, namely low HL and high LPL activities, could be determined mostly by genetic components, on which future work will focus.
Influence of controlled breathing patterns on cerebrovascular autoregulation and cardiac baroreceptor sensitivity
Authors: EAMES Penelope J. , POTTER John F. , PANERAI Ronney B.
Published: January 2004

Transfer function analysis has become one of the main techniques to study the dynamic relationship between cerebral blood flow and arterial blood pressure, but the influence of different respiratory rates on cerebral blood flow has not been fully investigated. In 14 healthy volunteers, middle cerebral artery blood flow velocity, recorded using transcranial Doppler ultrasound, non-invasive beat-to-beat Finapres blood pressure, ECG and end-tidal CO2 (PETCO2) levels were recorded with subjects resting supine and breathing spontaneously or at controlled rates of 6, 10 and 15 breaths/min. Transfer function analysis and impulse and step responses were computed at each respiratory rate. PETCO2 levels tended to fall slightly during paced respiration, especially at 15 breaths/min. Controlled breathing rates did not alter transfer function analysis in the frequency range below 0.08 Hz but, above this frequency, the coherence function contained significant peaks corresponding to the respiratory frequencies. The impulse response was similar at all breathing rates, but the step response was characteristic of more efficient autoregulation with reduced PETCO2 levels associated with increasing respiratory rate. The effects of breathing rate and rhythmicity and PETCO2 must be considered in studies of cerebral autoregulation.
Haemodynamic insights into the effects of ischaemia and cycle length on tissue Doppler-derived mitral annulus diastolic velocities
Authors: NAGUEH Sherif F. , RAO Liyun , SOTO Julia , MIDDLETON Katherine J. , KHOURY Dirar S.
Published: January 2004

In the present study, we performed simultaneous epicardial echocardiography and left heart catheterization on ten adult dogs to investigate the effects of ischaemia and tachycardia on the mitral annulus early (Ea) and late (Aa) diastolic velocities and the haemodynamic mechanisms involved. Left atrial pressure and left ventricular (LV) volumes and pressures were measured with 5 French Millar catheters. In each dog, inferior vena cava occlusion was used to alter preload and circumflex coronary artery occlusion was applied to induce ischaemia at two different cycle lengths: 450 and 550 ms. At both cycle lengths, ischaemia resulted in a reduction in LV relaxation, LV global and ipsilateral systolic function, transmitral pressure gradient (TMG), Ea and Aa (P<0.05). The shorter cycle length was associated with a shorter tau (time constant of LV relaxation), reduced TMG and reduced septal and lateral Ea (P<0.05 for all variables). Both septal and lateral Aa were significantly increased (P<0.05). Ischaemia influences Ea through changes in LV relaxation, global and regional systolic function and TMG. An increase in heart rate reduces Ea, but increases Aa.
Influence of experimental reduction of media/lumen ratio on arterial myogenic properties of spontaneously hypertensive and Wistar–Kyoto rats
Authors: HUGHES Jennifer M. , BUND Stuart J.
Published: January 2004

In the present study, myogenic properties of femoral arteries from control hindlimbs and those distal to external iliac artery partial ligation of spontaneously hypertensive rats (SHRs) and normotensive Wistar–Kyoto (WKY) rats were assessed. Arterial pressure was reduced distal to the ligature in both strains. Media thickness/lumen diameter (M/L) ratios of control (unligatured) SHRs were greater than in unligatured WKY rats and were reduced in arteries distal to the ligature (ligatured) within each strain. In none of the comparisons was a greater M/L ratio associated with greater maximal myogenic contractions, but increased M/L ratios were associated with a shift of myogenic activity to a higher pressure range in all comparisons. SHR ligatured arteries produced greater pressure-dependent contractile responses than WKY rat unligatured arteries, although arterial structures were not significantly different. Wall stress was similar in all arteries within the 60–120 mmHg pressure range with myogenic tone in spite of large differences in arterial structure. The utilization of arteries with experimentally altered structure provides further evidence that increased M/L ratios are not associated with greater peak pressure-dependent contractile responses and that arterial wall stress is maintained within a narrow range through an interaction between arterial wall geometry and smooth muscle contractile function.
Diagnosis of heart failure using urinary natriuretic peptides
Authors: NG L. L. , GEERANAVAR S. , JENNINGS S. C. , LOKE I. , O'BRIEN R. J.
Published: January 2004

In the present study, we assessed the use of urinary natriuretic peptides [N-terminal proatrial natriuretic peptide (N-ANP) and N-terminal pro-brain natriuretic peptide (N-BNP) and C-type natriuretic peptide (CNP)] in the diagnosis of heart failure. Thirty-four consecutive hospitalized heart failure patients (median age, 75.5 years; 14 female) were compared with 82 age- and gender-matched echocardiographically normal controls. All subjects provided plasma and urine specimens. Plasma was assayed for N-BNP, and urine was assayed for N-ANP, N-BNP and CNP. The diagnostic efficiency of peptides was assessed using receiver operating characteristic (ROC) curve analysis. All three urinary natriuretic peptides were significantly elevated in heart failure patients (P<0.001). Urine N-BNP was correlated with plasma N-BNP (rs=0.53, P<0.0005). Areas under the ROC curves for urinary N-ANP, N-BNP and CNP were 0.86, 0.93 and 0.70 and for plasma N-BNP was 0.96. Correcting urinary peptide levels using urine creatinine produced ROC areas of 0.89, 0.93 and 0.76 respectively. A urine N-BNP level cut-off point of 11.6 fmol/ml had a sensitivity and specificity for heart failure detection of 97% and 78% respectively, with positive and negative predictive values of 64.7 and 98%. In conclusion, although all three natriuretic peptides were elevated in urine in heart failure, urinary N-BNP had diagnostic accuracy comparable with plasma N-BNP. Use of urinary N-BNP for heart failure diagnosis may be suitable for high-throughput screening, especially in subjects reluctant to provide blood samples.
Arachidonic acid, palmitic acid and glucose are important for the modulation of clonal pancreatic β-cell insulin secretion, growth and functional integrity
Authors: DIXON Gordon , NOLAN John , McCLENAGHAN Neville H. , FLATT Peter R. , NEWSHOLME Philip
Published: January 2004

Insulin-resistant states such as obesity can result in an increase in the function and mass of pancreatic β-cells, so that insulin secretion is up-regulated and Type II diabetes does not develop. However, expansion of β-cell mass is not indefinite and may well decrease with time. Changes in circulating concentrations of nutritional factors, such as fatty acids and/or glucose, may lead to a reduction in β-cell mass in vivo. Few previous studies have attempted to explore the interplay between glucose, amino acids and fatty acids with respect to β-cell mass and functional integrity. In the present study, we demonstrate that culture of clonal BRIN-BD11 cells for 24 h with the polyunsaturated fatty acid arachidonic acid (AA) increased β-cell proliferation and enhanced alanine-stimulated insulin secretion. These effects of AA were associated with significant decreases in the cellular consumption of D-glucose and L-alanine as well as decreased rates of production of nitric oxide and ammonia. Conversely 24 h exposure to the saturated fatty acid palmitic acid (PA) was found to decrease β-cell viability (by increasing apoptosis), increase the intracellular concentration of triacylglycerol (triglyceride), while inhibiting alanine-stimulated insulin secretion. These effects of PA were associated with significant increases in D-glucose and L-glutamine consumption as well as nitric oxide and ammonia production. However, L-alanine consumption was decreased in the presence of PA. The effects of AA, but not PA, were additionally dependent on glucose concentration. These studies indicate that AA may have a critical role in maintaining the appropriate mass and function of islet β-cells by influencing rates of cell proliferation and insulin secretion. This regulatory effect may be compromised by high circulating levels of glucose and/or PA, both of which are elevated in Type II diabetes and may impact upon dysfunctional and apoptotic intracellular events in the β-cell.
Genetic risk markers for post-angioplasty restenosis: what should we expect?
Authors: GREEN Fiona R.
Published: January 2004

Genetic risk markers for coronary artery disease and associated phenotypes, such as restenosis after angioplasty, have the potential to be valuable to the individual, but even more so in facilitating an understanding of causal factors in the disease, and thereby the development of novel preventative and therapeutic strategies. In this issue of Clinical Science, Völzke and co-workers were unable to show association of a panel of candidate polymorphisms with restenosis, but their study has highlighted the need for even larger studies, as well as the potential benefits of finding causal genetic variation.
Statins reduce oxidized low-density lipoprotein levels, but do not alter soluble intercellular cell-adhesion molecule-1 and vascular cell-adhesion molecule-1 levels in subjects with hypercholesterolaemia
Authors: ROSENSON Robert S. , WOLFF David , TANGNEY Christine C.
Published: January 2004

ICAM-1 (intercellular cell-adhesion molecule-1) and VCAM-1 (vascular cell-adhesion molecule-1) are cell-adhesion molecules that have an essential role in monocyte recruitment. In the present study we have investigated (i) whether statins reduce soluble levels of ICAM-1 (sICAM-1) and VCAM-1 (sVCAM-1), and the relationship between resistance of LDL (low-density lipoprotein) to in vitro oxidation and sICAM-1 and sVCAM-1 levels. Whole blood samples were obtained from 55 healthy non-smoking adults (aged 35–65 years) with moderate (LDL-cholesterol, 3.4–4.9 mmol/l) hypercholesterolaemia participating in a randomized double-blinded, 8-week trial comparing pravastatin (40 mg), simvastatin (20 and 80 mg) and placebo. sICAM-1 levels (means±S.D.) increased slightly from 12.2±4.2 to 13.6±4.2 ng/ml with statin therapy, whereas, among placebo-assigned subjects, levels were unchanged (11.8±5.0 and 11.8±3.9 ng/ml). sVCAM-1 increased from 18.9±10.1 to 21.1±7.4 ng/ml among those on active therapy and slightly declined with placebo assignment (19.8±8.8 to 19.4±6.4 ng/ml). Lag times increased with statin therapy from 74.3±39.8 min to 98.3±57.8 min (P=0.003), and were unchanged in the placebo group (from 103.1±61.1 to 90.8±65.9 min; P=0.48). There were no significant changes between statin and placebo therapy for sICAM-1, sVCAM-1 or lag times (P=0.09, 0.16 and 0.067 respectively). Changes in sICAM-1 and sVCAM-1 were not correlated with the change in lag times. In contrast with the known effects of oxidized LDL on gene activation of ICAM-1 and VCAM-1, lag times did not correlate with sICAM-1 and sVCAM-1. Statin therapy improved lag times, but has no effect on sICAM-1 or sVCAM-1 levels.
A feeling in the waters: diagnosis of heart failure using urinary natriuretic peptides
Authors: KRUM Henry , LIEW Danny
Published: January 2004

Plasma levels of brain natriuretic peptide (BNP) and N-terminal pro-BNP (N-BNP) are highly sensitive markers of ventricular dysfunction and/or hypertrophy and, in established disease, offer prognostic value and may be useful for guidance of therapy. Ng and co-workers report in this issue of Clinical Science that urinary levels of N-BNP may be as useful as plasma levels for the discrimination of patients with and without heart failure. This raises the potential for a relatively simple urine test that could be used for the diagnosis of heart failure. Roles in prognostication and the guidance of therapy may also be possible but, perhaps of most significance, measurement of urinary N-BNP may be applied to screening of patients at high risk of heart failure. The main limitations of the study were that the sample of heart failure patients comprised only 34 individuals with New York Heart Association functional Class IV and that the observed correlation between levels of urinary N-BNP and plasma creatinine seemed counter-intuitive. The latter issue needs clarification, as renal impairment is a frequent co-morbidity among patients with heart failure and will potentially confound any observed association between ventricular dysfunction and urinary N-BNP levels. Another caveat is that it is unclear if testing for urinary N-BNP can be cheaply and conveniently administered on a large scale. Nevertheless, this first demonstration of elevated N-BNP in the urine of patients with heart failure raises a number of exciting possibilities with regard to the management of patients with established or possible heart failure. Further investigation is required and eagerly awaited.
An Update on Cystic Ovarian Degeneration in Cattle
Authors: Peter AT
Published: January 2004

Contents

Cystic ovarian degeneration (COD) is considered to be one of the most important causes of reproductive failure in cattle. There is a severe economic loss to dairy industry because COD increases days‐open in the postpartum period and the culling rates. The disease process is a consequence of a mature follicle that fails to ovulate at the appointed time of ovulation in the oestrous cycle. This anovulatory follicular structure either regresses or persists as a follicular or luteal cyst depending upon its structural/functional characteristics. The cells lining the follicular cyst synthesize oestrogen that, in certain instances, forces the animal to exhibit clinical signs of nymphomania. Besides oestrogen production, as per recent findings, they are also capable of secreting varying amount of progesterone which may dictate their fate. The animals that carry a luteal cyst may tend to be in anoestrus as the higher amount of progesterone secreted by this luteinized structure may change the pattern of gonadotrophins’ secretion. Present findings suggest that perturbation of the hypothalamo‐hypophyseal‐ovarian (HHO) axis, due to many exogenous and endogenous factors, as the cause for anovulation. For example, it has been suggested that lack of hypothalamic or hypophyseal response to the positive feedback effect of oestrogens that are secreted by the dominant follicle as one of the many causes. The non‐physiological changes that occur in the receptor expression of the HHO axis for the hormones involved in maturation, deviation, dominance and ovulation of the follicle may be yet another cause. The changes that occur at the cellular and molecular level in the ovary (in response to the factors mentioned above) that contribute to anovulation remain to be documented. This approach would allow us to completely understand the disease process. Hitherto, hormonal preparations that release luteinizing hormone from the anterior pituitary or have luteinizing hormone‐like action are used to treat follicular cysts. GnRH belongs to the former group and human chorionic gonadotrophin (hCG) hormone forms the latter group. Treatment with a luteolytic agent, prostaglandin F2α(PGF2α), is successful if a luteal cyst is diagnosed properly. Many agents may be developed in the future if the cellular and molecular pathways of the disease process are delineated. This article will review recent advances in our understanding of the pathogenesis of COD and suggest direction for future studies to completely understand the disease mechanism. This review will also discuss the existing method of treatments for cysts and methods proposed for treatment of cysts that tend to be refractory in nature.
DNA immunization encoding the secreted nonstructural protein 3 (NS3) of hepatitis C virus and enhancing the Th1 type immune response*
Authors: Jiao X. , Wang R. Y.‐H. , Feng Z. , Hu G. , Alter H. J. , W.‐K. Shih J.
Published: January 2004

Summary.  To induce a sustained and specific cellular immune response to hepatitis C virus (HCV), DNA immunization of mice was performed using plasmids containing the HCV nonstructural gene 3 (HCV/NS3). Plasmids were constructed such that the NS3 gene was expressed in a secreted form, a nonsecreted form or as a membrane‐bound antigen. The plasmid encoding the secreted antigen induced the strongest humoral and cellular immunity and favoured the T‐helper type 1 (Th1) pathway as shown by cytokine profiles and switching of antibody subclasses. Our study indicates that DNA immunization with a secreted form of HCV/NS3 is an effective means of inducing primary Th1 immune responses in the murine model.
Subtype mutations in the envelope 2 region including phosphorylation homology domain of Hepatitis C virus do not predict effectiveness of antiviral therapy
Authors: Quer J. , Murillo P. , Martell M. , Gómez J. , Esteban J. I. , Esteban R. , Guardia J.
Published: January 2004

Summary.  The aim of this study was to determine whether specific sequences of the phosphorylation homology domain (PePHD) region could be correlated with differences in response to antiviral therapy in patients infected with hepatitis C virus subtypes 1b, 2c, 3a and 4c/d. We included 43 patients (22 sustained responders and 21 nonresponders or relapsers) in the study, who were classified according to early viral decline during the first weeks of antiviral treatment and response at end of follow up. Type of mutations, mutation frequency, genetic diversity and phylogenetic relationships were compared at the PePHD and flanking regions. Phylogenetic trees showed that each sequence clustered together with those of the same subtype. Sequences from subtypes 1b and 4c/d resembled more closely the phosphorylation sites of protein kinase R and eIF2α than sequences from genotypes 2c and 3a, the latter with higher response rates to interferon‐α (IFNα) treatment. However, within specific subtypes, no separate clusters of responders and nonresponders were observed either at the beginning or at the end of follow up. We were not able to find any particular sequence or mutation in the PePHD region or in any other subregion of the fragment studied that allowed prediction of treatment response.
High hepatitis B virus (HBV) DNA viral load is an important risk factor for HBV reactivation in breast cancer patients undergoing cytotoxic chemotherapy
Authors: Zhong S. , Yeo W. , Schroder C. , Chan P. K. S. , Wong W.‐L. , Ho W. M. , Mo F. , Zee B. , Johnson P. J.
Published: January 2004

Summary.  Hepatitis B virus (HBV) reactivation during cytotoxic chemotherapy for cancer may complicate treatment and cause liver damage. The complication has been reported to occur in 10% to over 50% of HBV carriers, but the factors that determine which patients will develop reactivation remain unclear. The objective of the study is to test the hypothesis that the prechemotherapy HBV DNA level is a risk factor for the development of HBV reactivation. We studied 41 women undergoing cytotoxic chemotherapy for breast cancer, 17 of whom developed reactivation and 24 who did not. We developed a novel, ultra‐sensitive, real‐time polymerase chain reaction assay for the measurement of HBV DNA. The sera of 37 patients (16 who developed reactivation and 21 who did not) were available for measurement of HBV DNA using this technique. The results showed that patients in the reactivation group had a significantly higher median HBV DNA load (1.03 × 106 copies/mL; range <2.9 × 103 to 8.723 × 107) than did the nonreactivation group (<2.9 × 103 copies/ml; range <2.9 × 103 to 6.331 × 107) (P < 0.001). The optimal cut‐off between the two groups was found to be at serum HBV DNA level of 3 × 105, which gave a sensitivity of 81.0% and a specificity of 85.0%. In conclusion, for breast cancer patients receiving standard cytotoxic chemotherapy, a high HBV viral load prior to the administration of cytotoxic chemotherapy is a significant predictive factor for the development of HBV reactivation. Such information may be useful in determining which patients would benefit most from prophylactic antiviral therapy during cytotoxic chemotherapy.
Evolution of hepatitis B viral load and viral genome sequence during adefovir dipivoxil therapy
Authors: Werle B. , Cinquin K. , Marcellin P. , Pol S. , Maynard M. , Trépo C. , Zoulim F.
Published: January 2004

Summary.  Phase II and III clinical trials of adefovir dipivoxil (ADV) for the treatment of chronic hepatitis B have shown that this hepadnavirus polymerase inhibitor is well tolerated and effectively suppresses hepatitis B virus (HBV) replication. We therefore analysed the evolution of viral load and the emergence of HBV polymerase mutants in a 22‐patient subgroup from a phase III clinical trial of ADV for the treatment of HBeAg‐positive chronic hepatitis B. HBV DNA serum titres were quantified using a real‐time polymerase chain reaction (PCR) assay with molecular hybridization probes. Emergence of polymerase mutants was assessed by direct sequencing of the viral reverse transcriptase domain after PCR amplification of HBV DNA isolated from serum. Our results indicated that ADV therapy effectively suppressed HBV replication in these patients (median serum HBV decrease at week 48 of treatment = 4.3 log10 copies/mL). The initial drop of HBV DNA titres in serum at week 12 of ADV therapy seemed to be predictive of subsequent HBe seroconversion (P = 0.059). Neither viral breakthrough nor the selection of drug resistant mutants were observed during the study period. Our results showed that ADV administration for 48–72 weeks effectively suppresses HBV replication without the emergence of resistant viral mutants.
Hepatitis B surface antigenaemia following vaccination with a combined vaccine against hepatitis A and B
Authors: De Schryver A. , De Gendt K. , François G. , Van Damme P. , Meheus A.
Published: January 2004

Summary.  We report a case of transient hepatitis B surface antigenaemia (HBsAg) following vaccination with a combined vaccine against hepatitis A and B in healthy adults. This phenomenon has been observed following administration of recombinant hepatitis B (monovalent) vaccine, mainly in newborns or dialysis patients. Reports on healthy adults are much less frequent and mostly concern blood donors. The frequency of its occurrence is largely unknown but its duration does not exceed 28 days. It is not detected by all available assays. It is caused by a passive tranfer of antigen by vaccination, and not by viral replication; hence there is no risk for vaccination‐induced infection. An important implication resulting from our findings is that the results of HBsAg assays should be interpreted according to the time elapsed since the last administration of a recombinant monovalent vaccine against hepatitis B or a combined vaccine against hepatitis A and B.
The severity of liver fibrosis is associated with high leptin levels in chronic Hepatitis C
Authors: Piche T. , Vandenbos F. , Abakar‐Mahamat A. , Vanbiervliet G. , Barjoan E. M. , Calle G. , Giudicelli J. , Ferrua B. , Laffont C. , Benzaken S. , Tran A.
Published: January 2004

Summary.  Recent attention has focused on the liver profibrogenic role of leptin in animal models. The purpose of this study was to evaluate the role of leptin and TNF‐α in the severity of liver fibrosis in patients with chronic hepatitis C (CHC). We used a radioimmunoassay to determine serum leptin concentrations in 77 consecutive patients with CHC and 22 healthy controls. Leptin was correlated with liver histological (METAVIR) and metabolic indices. Sixty five patients had none to moderate liver fibrosis (F0‐F2) and twelve severe fibrosis (F3‐F4). Steatosis was observed in all but 27 patients. Leptin was significantly increased in patients compared with controls and was significantly more elevated in females both in patients and controls. The age, age at infection, prothrombin index, body mass index (BMI), triglycerides, glycaemia, ferritin, leptin and TNF‐α, were associated with severe fibrosis. Steatosis was significantly more pronounced in patients with severe than those without or moderate fibrosis (P = 0.04). Only leptin was significantly and independently associated with severe fibrosis (OR = 1.2, CI 95%: 1.1–1.4, P = 0.03). Leptin was significantly associated with BMI (r = 0.64, P < 0.001) and glycaemia (r = 0.43, P < 0.001). Significant correlations were found between steatosis and BMI (r = 0.30, P < 0.01) and glycaemia (r = 0.30, P < 0.01). In patients with CHC and higher BMI and glycaemia levels, the severity of liver fibrosis is associated with serum leptin. TNF‐α is a putative candidate involved in the mechanism.
The Legionella pneumophila LidA protein: a translocated substrate of the Dot/Icm system associated with maintenance of bacterial integrity
Authors: Conover Gloria M. , Derré Isabelle , Vogel Joseph P. , Isberg Ralph R.
Published: January 2004

Legionella pneumophila
establishes a replication vacuole within phagocytes that requires the bacterial Dot/Icm apparatus for its formation. This apparatus is predicted to translocate effectors into host cells. We hypothesized that some translocated proteins also function to maintain the integrity of the Dot/Icm translocator. Mutations that destroy this function are predicted to result in a Dot/Icm complex that poisons the bacterium, resulting in reduced viability. To identify such mutants, strains were isolated (called
lid
–
) that showed reduced viability on bacteriological medium in the presence of an intact Dot/Icm apparatus, but which had high viability in the absence of the translocator. Several such mutants were analysed in detail to identify candidate strains that may have lost the ability to synthesize a translocated substrate of Dot/Icm. Two such strains had mutations in the
lidA
gene. The LidA protein exhibits properties expected for a translocated substrate of Dot/Icm that is important for maintenance of bacterial cell integrity: it associates with the phagosomal surface, promotes replication vacuole formation, and is important for both efficient intracellular growth and high viability on bacteriological media after introduction of a plasmid that allows high level expression of the
dotA gene.
Neisseria meningitidis App, a new adhesin with autocatalytic serine protease activity
Authors: Serruto Davide , Adu‐Bobie Jeannette , Scarselli Maria , Veggi Daniele , Pizza Mariagrazia , Rappuoli Rino , Aricò Beatrice
Published: January 2004

Neisseria meningitidis
is a Gram‐negative bacterium which colonizes the human upper respiratory tract. Occasionally, it translocates to the bloodstream causing sepsis and from there it can cross the blood–brain barrier and cause meningitis. Many of the molecules, which mediate the interaction of
N. meningitidis
to host cells, are still unknown. Recently, App (
A
dhesion and
p
enetration
p
rotein) was described as a member of the autotransporter family and a homologue to the Hap (
H
aemophilus
a
dhesion and
p
enetration) protein of
Haemophilus influenzae
, a molecule that plays a role in the interaction with human epithelial cells. In this study we expressed
app
in
Escherichia coli
in order to analyse the functional properties of the protein. We show that the protein is exported to the
E. coli
surface, processed by an endogenous serine‐protease activity and released in the culture supernatant.
Escherichia coli
expressing
app
adhere to Chang epithelial cells, showing that App is able to mediate bacterial adhesion to host cells. The serine protease activity is localized at the amino‐terminal domain, whereas the binding domain is in the carboxy‐terminal region. The role of App in adhesion was confirmed also in
N. meningitidis .
Turnover of FlhD and FlhC, master regulator proteins for Salmonella flagellum biogenesis, by the ATP‐dependent ClpXP protease
Authors: Tomoyasu Toshifumi , Takaya Akiko , Isogai Emiko , Yamamoto Tomoko
Published: January 2004

In enterobacteria such as Salmonella, flagellar biogenesis is dependent upon the master operon flhDC at the apex of the flagellar gene hierarchy, which is divided into three classes 1, 2 and 3. Previously we reported that depletion of the ClpXP ATP‐dependent protease results in dramatic enhancement of class 2 and class 3 gene transcription, whereas the transcription level of the flhDC operon remains normal in Salmonella enterica serovar Typhimurium. This suggests that the ClpXP protease may be responsible for the turnover of the FlhD and FlhC master regulators (Tomoyasu, T., Ohkishi, T., Ukyo, Y., Tokumitsu, A., Takaya, A., Suzuki, M. et al., 2002, J Bacteriol 184:645–653). In this study, to establish the role of the ClpXP protease in the turnover of FlhD and FlhC proteins, we analysed levels of the FlhD and FlhC proteins in wild‐type and ClpXP mutant cells using anti‐FlhD and anti‐FlhC antibodies. The results show that both FlhD and FlhC proteins are markedly accumulated in ClpXP mutant cells and the half‐life of FlhC is approximately fivefold longer in the ClpXP mutant, suggesting that the ClpXP protease is responsible for the degradation of FlhD and FlhC. The results also show that the ClpXP protease degrades both proteins in FlhD2FlhC2 complex but does not seem to recognize the respective subunits synthesized individually. Taken together, it is suggested that the cellular concentration of the FlhD2FlhC2 master regulator is tightly controlled at the post‐translational level by the ClpXP protease. We also examined the role of other members of the ATP‐dependent protease family in the regulation of flagellar biogenesis and concluded that only ClpXP in this family functions as a negative regulator for flagellar biogenesis in Salmonella.
The Lrp family of transcriptional regulators
Authors: Brinkman Arie B. , Ettema Thijs J. G. , De Vos Willem M. , Van Der Oost John
Published: January 2004

Genome analysis has revealed that members of the Lrp family of transcriptional regulators are widely distributed among prokaryotes, both bacteria and archaea. The archetype Leucine‐responsive Regulatory Protein from Escherichia coli is a global regulator involved in modulating a variety of metabolic functions, including the catabolism and anabolism of amino acids as well as pili synthesis. Most Lrp homologues, however, appear to act as specific regulators of amino acid metabolism‐related genes. Like most prokaryotic transcriptional regulators, Lrp‐like regulators consist of a DNA‐binding domain and a ligand‐binding domain. The crystal structure of the Pyrococcus furiosus LrpA revealed an N‐terminal domain with a common helix–turn–helix fold, and a C‐terminal domain with a typical αβ‐sandwich fold. The latter regulatory domain constitutes a novel ligand‐binding site and has been designated RAM. Database analysis reveals that the RAM domain is present in many prokaryotic genomes, potentially encoding (1) Lrp‐homologues, when fused to a DNA‐binding domain (2) enzymes, when fused as a potential regulatory domain to a catalytic domain, and (3) stand‐alone RAM modules with unknown function. The architecture of Lrp regulators with two distinct domains that harbour the regulatory (effector‐binding) site and the active (DNA‐binding) site, and their separation by a flexible hinge region, suggests a general allosteric switch of Lrp‐like regulators.
The uncoupling of oxygen sensing, phosphorylation signalling and transcriptional activation in oxygen sensor FixL and FixJ mutants
Authors: Saito Ken , Ito Eiichi , Hosono Kaito , Nakamura Kayako , Imai Kiyohiro , Iizuka Tetsutaro , Shiro Yoshitsugu , Nakamura Hiro
Published: January 2004

The rhizobial FixL/FixJ system, a member of the superfamily of bacterial two‐component signal transducing systems, regulates the expression of nitrogen fixation‐related genes by sensing environmental oxygen tension. Oxygen‐free (deoxy) FixL is autophosphorylated at an invariant histidine residue with ATP, and the phosphoryl group is transferred to FixJ, leading to an enhancement in transcriptional activity at low oxygen tensions, but the histidine kinase activity of the oxygen‐bound (oxy) form is inhibited. To investigate the mechanism of oxygen sensing, we established a FixL/FixJ‐mediated PfixK‐lacZ reporter system in Escherichia coli, and isolated FixL and FixJ mutations conferring an upregulation of lacZ gene expression on the reporter cells even under aerobic conditions. FixL mutant proteins, which contain single amino acid changes near the autophosphorylation site, showed elevated levels of autophosphorylation and a concomitant phosphoryl transfer to FixJ in the presence of oxygen, although their oxygen‐binding affinities were unimpaired. These mutational analyses suggest that the autophosphorylation domain plays a crucial role in regulatory coupling between oxygen binding and kinase activity. FixJ mutants in helix α1 and strand β5 of the N‐terminal half exhibited the formation of a stable acyl phosphate bond. In contrast, those in helices α4 and α5 constitutively bound to the fixK promoter in a monomeric form, suggesting that the α4 and α5 helices may be involved in the post‐phosphorylation/dimerization signal transfer to liberate the DNA‐binding activity of the C‐terminal domain, not only serving as a dimerization interface.
Protein–peptidoglycan interactions modulate the assembly of the needle complex in the Salmonella invasion‐associated type III secretion system
Authors: Pucciarelli M. Graciela , García‐del Portillo Francisco
Published: January 2004

The invasion‐associated type III secretion system of Salmonella enterica assembles as a supra‐molecular structure, termed needle complex, which spans the bacterial envelope. Here, we present evidence for protein–peptidoglycan interactions that modulate the assembly of this organelle. The presence of major membrane components of the needle complex (PrgH, PrgK and InvG) and InvH, required for efficient assembly of the organelle, was examined in peptidoglycan purified by extensive boiling of bacteria in 4% SDS. InvH, PrgH and PrgK, but not InvG, were detected in this purified material. InvH was present in the peptidoglycan in higher relative amounts than PrgH or PrgK, and was the only protein efficiently bound to peptidoglycan in cross‐linking experiments. Analysis in mutants defective for needle complex proteins showed that the needle proteins PrgI and PrgJ and, to a lesser extent, InvH, sustain the association of PrgH and PrgK with peptidoglycan. In contrast, the association of InvH with peptidoglycan did not necessitate other needle complex proteins. Functional analysis showed that the association of InvH, PrgH and PrgK with peptidoglycan is abolished in live bacteria carrying structural modifications in the peptidoglycan. The loss of these interactions caused a marked reduction in the number of needle complexes and, concomitantly, in protein secretion and bacterial invasion of cultured eukaryotic cells. Altogether, these data provide the first evidence for an association between proteins of the Salmonella needle complex and the peptidoglycan. In addition, we demonstrate that these protein–peptidoglycan interactions are critical for an efficient and correct assembly of this specialized organelle.
Co‐ordination of pathogenicity island expression by the BipA GTPase in enteropathogenic Escherichia coli (EPEC)
Authors: Grant Andrew J. , Farris Michele , Alefounder Peter , Williams Peter H. , Woodward Martin J. , O'Connor C. David
Published: January 2004

BipA is a novel member of the ribosome binding GTPase superfamily and is widely distributed in bacteria and plants. We report here that it regulates ­multiple cell surface‐ and virulence‐associated ­components in the enteropathogenic Escherichia coli (EPEC) strain E2348/69. The regulated components include bacterial flagella, the espC pathogenicity island and a type III secretion system specified by the locus of enterocyte effacement (LEE). BipA positively regulated the espC and LEE gene clusters through transcriptional control of the LEE‐encoded regulator, Ler. Additionally, it affected the pattern of proteolysis of intimin, a key LEE‐encoded adhesin specified by the LEE. BipA control of the LEE operated independently of the previously characterized regulators Per, integration host factor and H‐NS. In contrast, it negatively regulated the flagella‐mediated motility of EPEC and in a Ler‐independent manner. Our results indicate that the BipA GTPase functions high up in diverse regulatory   cascades   to   co‐ordinate   the   expression of key pathogenicity islands and other virulence‐associated factors in E. coli.