Persistence of extracellular baculoviral DNA in aquatic microcosms: extraction, purification, and amplification by the polymerase chain reaction (PCR)

Genetically-modified baculoviruses have potential uses as bio-pesticides in forestry. However, the baculoviral occlusion bodies (OBs) may release genetically-modified DNA into the forest environment. In this research, outdoor aquatic microcosms, spiked with 673 microg of genomic DNA (4.4 x 10(12) target copies) from the genetically modified baculovirus Choristoneura fumiferana MNPVegt-/lacZ+, were exposed to natural summer conditions. A 530 bp DNA fragment from the genome of CfMNPVegt-/lacZ+ was detected in field microcosm water samples for about 24 h. The introduced DNA may have persisted for a longer time, but was below the detection limit of the PCR analysis (13.5 pg DNA or 8.9 x 10(4) target copies ml(-1) water). The detection limit of PCR was determined by spiking water samples with a dilution series of CfMNPVegt-/lacZ+ genomic DNA, extracting and purifying the DNA, and then PCR analysis. This study provides some of the first information on the persistence and detection limits of this viral DNA under aquatic ecological conditions, and the methods that can be used to conduct such a molecular-based field study.

Phase II study of troxacitabine in chemotherapy-naïve patients with advanced cancer of the pancreas

BACKGROUND

Troxacitabine (Troxatyl) is a novel L-enantiomer nucleoside analog with activity in pancreatic cancer xenograft models.

PATIENTS AND METHODS

Troxacitabine 1.5 mg/m(2) was administered by 30-min infusions daily x5 every 4 weeks to 54 patients with advanced pancreatic cancer. Patients were evaluated for objective tumor response, time to tumor progression (TTP), changes in tumor marker CA 19-9, survival, safety, pain, analgesic consumption, Karnofsky performance status and weight change.

RESULTS

Median TTP was 3.5 months (95% CI 2.0-3.8), median survival 5.6 months (95% CI 4.9-7.4), and the 1 year survival rate 19%. Best responses were stable disease in 24 patients with eight patients having stable disease for at least 6 months (15%). A 50% or greater decrease in CA 19-9 was seen in seven of 44 assessed patients (16%). Grade 3 and 4 neutropenia were observed in 37% and 30% of patients with one episode of febrile neutropenia. The most common drug-related non-hematological toxic effects reported were cutaneous, with 22% and 6% of patients reporting grade 2 and 3 skin rash, respectively and 4% grade 2 hand-foot syndrome.

CONCLUSION

Troxacitabine administered by a bolus daily x5 monthly regimen has modest activity in advanced pancreatic adenocarcinoma.

Initial results for urban metal distributions in house dusts of syracuse, New York, USA

A program of house dust sample collection and analysis has begun in Syracuse, New York, USA, in order to determine the feasibility of a geography-based exposure assessment for urban metals. The sampling program, and the protocols it employs, is described for two different types of wipe media, Ghost Wipes and Whatman Filters. Preliminary results show that strong spatial patterns of floor dust loading (mg dust per square foot) can be observed for data aggregated at a spatial scale of about 1600 m (approximately 2.5 km2). Floor dust metal concentrations were similar to those found in other urban environments, with some regional variation. The median floor dust Pb concentration was approximately 108 mg x kg(-1) for this initial data set of approximately 264 sampled residential locations, and varied from 50 to 1100 mg Pb x kg(-1).

Application cutanée de talc et sarcoïdose

INTRODUCTION

We report on two patients with sarcoidosis with disseminated nodes, who used talc on irritated cutaneous areas.

CASE REPORT

A histologic examination with intense polarised light showed up cristalline bi-refringent particles within vessels in contact with granulomatous areas. Microdissection followed by an electronic microscopy study and microanalysis was realised. In situ microanalysis allowed us to identify bi-refringent particles with a size of roughly 0.25microm as silica or silicate coming possibly from talc. We consequently studied a brand name talc. The diffraction spectrum showed that this product not only contained talc but also chlorite and quartz. Electron microscopy examination showed particles of all sizes even smaller than 0.25microm. These infra-microscopic particles, visible in a vessel only when agglomerated, could be invisible under optic microscopy (resolution: roughly 0.5microm) inside the granuloma even though they are responsible for it. Moreover, at this level of size of particles, they may escape mineralogic analyses which use methods involving the destruction of organic material, the mineral residue collecting on cellulose filter with a diameter generally of 0.45microm.

CONCLUSION

Two recent epidemiologic studies confirm the possible role of mineral exposure in sarcoidosis. Some sarcoidosis could be caused by mineral overload on genetically predisposed patients. Some cases could be related to mineral powder application. Among different types of mineral exposure, applications of cosmetic products may induce disseminated granulomatous reaction on genetically predisposed patients. Such applications have to be considered in epidemiologic studies.

Cytoplasmic membrane polarization in Gram-positive and Gram-negative bacteria grown in the absence and presence of tetracycline

The ability of numerous diverse compounds and ions to cross the bacterial cytoplasmic membrane by diffusion and active transport is highly dependent on cytoplasmic membrane fluidity, which can be measured using fluorescent probes to estimate membrane polarization values. However, membrane polarization data are lacking for most bacterial species. The cytoplasmic membrane polarization values for Arthrobacter sp. ATCC 21908, Bacillus cereus NRC 3045, Pseudomonas fluorescens R2F, Pseudomonas putida NRC 2986 and Escherichia coli C600 bacterial cells were spectrofluorometrically measured over a temperature range from 10 to 50 degrees C, and in the absence and presence of 1 microg/ml tetracycline, using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) to obtain new information on their membrane fluidity. At an assay temperature of 10 degrees C, E. coli cells grown in the absence of tetracycline exhibited the highest cytoplasmic membrane polarization value (least fluid membrane) of 0.446, followed by values of 0.392, 0.371, 0.344 and 0.293, respectively, for B. cereus, Arthrobacter sp., P. fluorescens and P. putida. At an assay temperature of 30 degrees C, the polarization values ranged from 0.357 to 0.288 for cells grown in the absence of tetracycline, regardless of the species. B. cereus grown in the presence of 1 microg/ml tetracycline had lower polarization values than when grown in the absence of this antibiotic at all assay temperatures. Regardless of the absence or presence of 1 microg/ml tetracycline in the growth medium, all bacterial species generally exhibited a more fluid membrane as the assay temperature increased from 10 to 50 degrees C. To our knowledge, these are some of the first cytoplasmic membrane polarization values reported for these Gram-negative and Gram-positive bacteria over a broad temperature range and also for cells grown in the presence of tetracycline.

Abrogation of protein convertase 2 activity results in delayed islet cell differentiation and maturation, increased alpha-cell proliferation, and islet neogenesis

To date, the role of pancreatic hormones in pancreatic islet growth and differentiation is poorly understood. To address this issue, we examined mice with a disruption in the gene encoding prohormone convertase 2 (PC2). These mice are unable to process proglucagon, prosomatostatin, and other neuroendocrine precursors into mature hormones. Initiation of insulin (IN) expression during development was delayed in PC2 mutant mice. Cells containing IN were first detected in knockout embryos on d 15 of development, 5 d later than in wild-type littermates. However, the IN(+) cells of d 15 PC2 mutant mice coexpressed glucagon, as did the first appearing beta-cells of controls. In addition, lack of PC2 perturbed the pattern of expression of transcription factors presumed to be involved in the determination of the mature alpha-cell phenotype. Thus, in contrast to controls, alpha-cells of mutant mice had protracted expression of Nkx 6.1 and Pdx-1, but did not express Brn-4. Islets of adult mutant mice also contained cells coexpressing insulin and somatostatin, an immature cell type found only in islets of the wild-type strain during development. In addition to the effects on islet cell differentiation, the absence of PC2 activity resulted in a 3-fold increase in the rate of proliferation of proglucagon cells during the perinatal period. This increase contributed to the development of alpha-cell hyperplasia during postnatal life. Furthermore, the total beta-cell volume was increased 2-fold in adult mutants compared with controls. This increase was due to islet neogenesis, as the number of islets per section was significantly higher in knockout mice compared with wild-type mice, whereas both strains had similar rates of IN cell proliferation. These results indicate that hormones processed by PC2 affected processes that regulate islet cell differentiation and maturation in embryos and adults.

[Markers of cardiovascular remodeling in hypertension]

Our goal was to study the relative influence of systolic blood pressure (SBP) and plasmatic markers of sympathetic and renin-aldosterone systems (RAS) activities to left atrial diameter (LAD), left ventricular posterior wall thickness (LVPWT) and pulse wave velocity (PWV), which reflect cardiovascular remodeling in hypertension.

METHODS

In 227 consecutive patients with hypertension (mean age +/- SD: 53.3 years +/- 13.4, 126 men), we measured: PWV, LAD, LVPWT, mean 24-hours SBP, plasma renin activity, and plasma aldosterone and catecholamine levels. Multiples linear regression analyses were performed to test statistical associations between hemodynamic and neurohumoral factors, and cardiovascular remodeling parameters, after adjustment for age, gender and body mass index.

RESULTS

LVPWT was positively correlated to SBP as well as to plasma aldosterone and meta-noradrenaline (p < 0.001). LAD and PWV were related to SBP but not to any of the biological variables. Moreover, LAD correlated to PWV independently of SBP (p < 0.05), whereas after SBP inclusion in the model, there was not significant correlation between LAD and LVPWT nor between LVPWT and PWV.

CONCLUSION

In hypertension, the development of cardiac hypertrophy depends on SBP and the sympathetic and renin-aldosterone systems activities. The RAS is not involved in the PWV nor LAD modifications. Strong association between LAD and PWV suggest that left atrial enlargement, that may be considered as a marker of diastolic function, may results more from arterial stiffness than from ventricular hypertrophy.

Persistence of isolated flow in the internal carotid artery in brain death

The criteria for the confirmation of brain death (BD) using transcranial Doppler ultrasonography (TCD) state that flow should not be observed in the internal carotid artery (ICA). In 94 brain-dead patients examined by TCD, 19 (20%) had flow in the ICA despite cerebral circulatory arrest. There was no difference in the clinical characteristics of patients with or without isolated flow in the ICA. Shunting of blood from the ICA into the external carotid system or the arrest of blood flow at a higher level than the carotid siphon may explain our findings. Our results show that the current TCD criteria can result in a high rate of false negatives. We suggest that the TCD criteria for the diagnosis of brain death should be reviewed.

[Clinical implications of blood pressure variability]

There are many variations in blood pressure, ranging from that observed between systole and diastole (pulse pressure) to slower daily or seasonal variations. This variability has many facets, for example the simple concept of variation around the mean blood pressure and the more complex spectral, chaos or fractal analysis... Some of these concepts are still the subject of fundamental research and have no current clinical applications. Others, however, are already part of our evaluation of hypertensive patients or used as prognostic factors in cardiac failure or myocardial infarction. Blood pressure variability, either the pulse pressure or 24 hour variability, is associated with a higher incidence of cardiovascular complications. Although the causality of the relationship is uncertain, patients with the greatest variability seem to be at higher risk. In addition to this prognostic impact, the study of changes in blood pressure by spectral analysis may also provide indices of adrenergic tone or sympathovagal equilibrium which may be useful clinically. Finally, the combined study of blood pressure variability and heart rate lead to the baroreflex, the sensitivity of which integrates major risk factors such as blood pressure, age, heart rate and serum cholesterol. This baroreflex could be a useful parameter for stratification of cardiovascular risk. This has already been demonstrated in patients at high risk, such as those with cardiac failure or myocardial infarction.

New large solar photocatalytic plant: set-up and preliminary results

A European industrial consortium called SOLARDETOX has been created as the result of an EC-DGXII BRITE-EURAM-III-financed project on solar photocatalytic detoxification of water. The project objective was to develop a simple, efficient and commercially competitive water-treatment technology, based on compound parabolic collectors (CPCs) solar collectors and TiO2 photocatalysis, to make possible easy design and installation. The design, set-up and preliminary results of the main project deliverable, the first European industrial solar detoxification treatment plant, is presented. This plant has been designed for the batch treatment of 2 m3 of water with a 100 m2 collector-aperture area and aqueous aerated suspensions of polycrystalline TiO2 irradiated by sunlight. Fully automatic control reduces operation and maintenance manpower. Plant behaviour has been compared (using dichloroacetic acid and cyanide at 50 mg l(-1) initial concentration as model compounds) with the small CPC pilot plants installed at the Plataforma Solar de Almería several years ago. The first results with high-content cyanide (1 g l(-1)) waste water are presented and plant treatment capacity is calculated.

Efficacy, tolerability and management of raltitrexed (Tomudex) monotherapy in patients with advanced colorectal cancer. a review of phase II/III trials

Raltitrexed (Tomudex), a thymidylate synthase inhibitor, is an alternative to 5-fluorouracil (5-FU)/leucovorin (LV) for the first-line treatment of advanced colorectal cancer. Following the completion of four phase III studies with raltitrexed at the recommended dose of 3.0 mg/m(2), it is opportune to review the efficacy and tolerability data of raltitrexed and suggest guidelines for appropriate patient management. Data are analysed from four phase III and five phase II studies including over 1300 patients with advanced colorectal cancer, some of whom were elderly or received higher doses of raltitrexed. Median survival with raltitrexed was comparable to that of bolus or infusional 5-FU/LV in three of the four randomised studies and objective response rates in the four trials were similar for the two agents. Response rates were at least comparable in elderly patients in phase II studies. For the majority of patients, treatment with raltitrexed was well tolerated even at doses higher than that recommended or in the elderly. As with other cytotoxic agents, serious and potentially life-threatening side-effects can occur; nevertheless, adherence to simple patient guidelines should minimise the incidence of serious side-effects with raltitrexed; these include the assessment of renal function before each and every treatment, dosage adjustment in the presence of renal impairment and close monitoring with prompt treatment of toxicities, particularly diarrhoea and neutropenia.

Dynamics and orientation of amphipathic peptides in solution and bound to membranes: a steady-state and time-resolved fluorescence study of staphylococcal delta-toxin and its synthetic analogues

The environment of both the hydrophilic and hydrophobic sides of alpha-helical delta-toxin are probed by tryptophanyl (Trp) fluorescence, when self-association occurs in solution and on binding to membranes. The fluorescence parameters of staphylococcal delta-toxin (Trp15 on the polar side of the amphipathic helix) and synthetic analogues with single Trp at position 5 or 16 (on the apolar side) were studied. The time-resolved fluorescence decays of the peptides in solution show that the local environment of their single Trp is always heterogeneous. Although the self-association degree increases with concentration, as shown by fluorescence anisotropy decays, the lifetimes (and their statistical weight) of Trp16 do not change, contrary to what is observed for Trp15. The first step of self-association is then driven by hydrophobic interactions between apolar sides of alpha-helices, whilst further oligomerization involves their polar side (Trp15) via electrostatic interactions. This is supported by dissociation induced by salt. For all self-associated peptides, the polarity of the Trp microenvironment was not significantly modified upon binding to phospholipid vesicles, as indicated by the small shifts of the fluorescence emission spectra and lifetime values. However, the relative populations of the lifetime classes vary with bound-peptide density similar to the rates of their global motions in bilayers or smaller particles. Quenching experiments by water or lipid-soluble compounds show changes of the orientation of membrane-inserted peptides, from probably dimers lying flat at the interface at low peptide density, to oligomers spanning the membrane and inducing membrane fragmentation at high peptide density.

The hemicrania continua diagnosis

More than 16 years after the first description of hemicrania continua (HC), its aetiology and pathogenesis remain obscure. Clinically, HC is considered a syndrome with two pivotal characteristics: (i) strictly unilateral (moderate, fluctuating, relatively long-lasting) headache; and (ii) absolute response to indomethacin. HC is further characterized by some ancillary, but mostly "negative", features such as: (iii) relative paucity of accompaniments; and (iv) lack of precipitating factors. The female preponderance is also remarkable, although not diagnostic in the solitary case. Finally, a non-specific, but remarkable feature is the temporal pattern. HC may present as a remitting or chronic (continuous) headache. In HC, unilaterality and absolute response to indomethacin are considered crucial diagnostically. Existing controversy, such as regarding atypical features, particularly the so-called "HC resistant to indomethacin", is discussed. The nature of hemicrania with negative indomethacin response remains most unclear; it may not belong to the HC cycle at all. Accordingly, we propose that the typical clinical picture of HC, including an absolute response to indomethacin, be termed Hemicrania continua vera. More or less analogous, but indomethacin-resistant, clinical pictures can provisionally be termed Hemicrania generis incerti (of undetermined nature), provided other diagnostic possibilities have been ruled out. The differential diagnosis of HC vs. other unilateral headaches is commented on. Previous attempts at classification of HC into the group chronic daily headache (CDH) are discussed. The only acceptable "link" of HC with the other headaches classified as CDH is the temporal pattern (which is a non-specific feature). HC is probably pathophysiologically different from the others disorders classified under CDH. Conversely, HC and chronic paroxysmal hemicrania share many common features, including the absolute response to indomethacin. HC should probably be included in the IHS group 3.

Thymidylate synthase expression in stage II and III colon cancer: a retrospective review

This study is a retrospective analysis of thymidylate synthase (TS) levels in patients with stage II (T3 or T4) and III colon cancer. Two groups of patients were identified: one undergoing surgery alone (98 patients) and the second receiving adjuvant 5-fluorouracil chemotherapy (112 patients). TS analyses were carried out using the 106 monoclonal antibody and a published grading system dividing staining into high and low intensity. The distribution of patients with low versus high TS levels was similar in the two groups. There was no association between TS staining intensity and grade, stage or location of primary. Seventy-nine patients have relapsed: 46 (48%) in the surgery only group, 33 (30%) in the adjuvant therapy group (median follow-up: 51 and 61 months). Similar proportions relapsed when analyzed according to TS: in the surgery only group, 41% of patients with low TS, 48% with high TS; in the adjuvant group, 31% with low TS, 30% with high TS. In the surgery only group, a trend toward improved disease-free survival (DFS) was seen in the low TS group (84 versus 63% at 2 years, p = 0.08). No difference was seen in overall survival. There were no differences in DFS or overall survival in patients receiving adjuvant therapy according to TS intensity. The trend for worse outcome in patients with high TS is consistent with previous reports. The lack of difference in outcome for patients with low and high TS receiving chemotherapy suggests that high TS levels may predict greater benefit from adjuvant treatment.

[Creutzfeldt-Jakob disease: case report with spinal cord involvement]

Creutzfeldt-Jakob disease (CJD) is the most common subacute transmissible spongiform encephalopathy. Approximately 85% of the cases are sporadic. The remaining 15% consist of genetic and iatrogenic forms. We report a sporadic form of CJD with spinal cord involvement and a clinical manifestation characterized by dementia and cerebellar syndrome, myofasciculation with absent reflexes and seizures. The two last manifestations are rare. The clinical hypothesis was probable CJD which was confirmed with autopsy and immunohistochemistry. We conclude that CJD should always be suspected when rapidly progressive dementia occurs and the absence of pyramidal or extrapyramidal signs suggest a spinal cord and/or peripheral nerve involvement.

Hemicrania continua: diagnostic criteria and nosologic status

Proposals for the diagnostic criteria for hemicrania continua (HC) and also for the nosological status of HC are set forth. The clinical constellation of symptoms and signs making up HC consists of: unilaterality without side shift; absolute indomethacin effect; and long-lasting repetitive attacks of varying duration, eventually with a chronic pattern, the pain being mild to severe. For the typical clinical picture of HC, including a positive 'indotest', we propose the term hemicrania continua vera. More or less analogous, but 'indotest-negative' clinical pictures have provisionally been termed hemicrania generis incerti (of undetermined nature). At the present level of knowledge, the diagnosis of hemicrania generis incerti should be made mostly by exclusion. HC may possibly best be classified along with chronic paroxysmal hemicrania (CPH) as this is the only other headache absolutely responsive to indomethacin. The bond between these two headaches on the one hand and cluster headache on the other should, at most, be a loose one. Interrelationships of these four classifiable headaches are briefly discussed.

Molecular polymorphism of the intermediate filament protein transitin

Transitin is an avian intermediate filament protein whose transient expression in the progenitor cells of the muscle and nerve tissues is similar to that of mammalian nestin. Both proteins contain an alpha-helical core domain flanked by a short N-terminal head and a long C-terminal extremity. However, the tail region of transitin is significantly different from that of nestin in that it harbors a unique motif containing more than 50 leucine zipper-like heptad repeats which is not found in any other intermediate filament protein. Despite the absence of introns in this region of the transitin gene, it was reported that different isoforms of the protein were produced by exclusion or inclusion of a number of repeats generated by an unusual splicing mechanism recognizing consensus 5' and 3' splice sites contained within the coding sequence of the heptad repeat domain [Napier et al. (1999) J Mol Neurosci 12:11-22]. Two monoclonal antibodies (mAbs) reacting with repeated epitopes of this motif were used to monitor transitin expression during in vitro myogenesis of the quail myogenic cell line QM7. Confocal microscopy revealed that the subcellular domains decorated with mAbs A2B11 and VAP-5 were mutually exclusive: the intermediate filament network visualized with mAb VAP-5 appeared to abut on a submembranous domain defined by mAb A2B11. When QM7 cells were induced to differentiate by switching to medium containing low serum components, an early effect was the local loss of A2B11 cortical staining at the points of cell-cell contacts. The A2B11 signal also disappeared before that of VAP-5 in newly formed myotubes. Unexpectedly, the mutually exclusive staining pattern of the mAbs could not be explained by alternative splicing since both epitopes mapped to a repeated element preceding the consensus 5' splice sites of the heptad repeat domain. An alternative explanation would be that the central repeat domain of transitin is a polymorphic structure from which different conformations exist depending on the local context. This hypothesis is strengthened by the observation that in cultured neural crest cells, the A2B11 antigen is preferentially expressed by freely migrating crest cells whose intracellular pH and calcium concentrations are different from those of non-migrating cells.

Phase II study of carboplatin and liposomal doxorubicin in patients with recurrent squamous cell carcinoma of the cervix

BACKGROUND

The activity of the combination of carboplatin and liposomal doxorubicin was tested in a Phase II study of patients with recurrent cervical carcinoma.

METHODS

The combination of carboplatin (area under the concentration curve [AUC], 5) and liposomal doxorubicin (Doxil; starting dose, 40 mg/m(2)) was administered intravenously every 28 days to 37 patients with recurrent squamous cell cervical carcinoma to determine antitumor activity and toxicity profile.

RESULTS

Twenty-nine patients were assessable for response, and 35 patients were assessable for toxicity. The overall response rate was 38%, the median time to response was 10 weeks, the median duration of response was 26 weeks, and the median survival was 37 weeks. The main toxic effect was myelosuppression, with Grade 3 and 4 neutropenia in 16 patients, anemia in 12 patients, thrombocytopenia in 11 patients, and neutropenic fever in 3 patients. Four patients had five infusion-related reactions during the infusion of liposomal doxorubicin, leading to treatment discontinuation in three patients. Grade > or = 2 nonhematologic toxicity included nausea in 17 patients, emesis in 14 patients, fatigue in 9 patients, mucositis and/or stomatitis in 8 patients, constipation in 6 patients, weight loss in 5 patients, hand-foot syndrome in 2 patients, and skin reactions in 3 patients.

CONCLUSIONS

The combination of carboplatin and liposomal doxorubicin has modest activity in patients with recurrent cervical carcinoma.

Dopamine and glutamate induce distinct striatal splice forms of Ania-6, an RNA polymerase II-associated cyclin

Control of neuronal gene expression by drugs or neurotransmitters is a critical step in long-term neural plasticity. Here, we show that a gene induced in the striatum by cocaine or direct dopamine stimulation, ania-6, is a member of a novel family of cyclins with homology to cyclins K/T/H/C. Further, different types of neurotransmitter stimulation cause selective induction of distinct ania-6 isoforms, through alternative splicing. The longer Ania-6 protein colocalizes with nuclear speckles and is associated with key elements of the RNA elongation/processing complex, including the hyperphosphorylated form of RNA polymerase II, the splicing factor SC-35, and the p110 PITSLRE cyclin-dependent kinase. Distinct types of neuronal stimulation may therefore differentially modulate nuclear RNA processing, through altered transcription and splicing of ania-6.

Glucose-induced insulin hypersecretion in lipid-infused healthy subjects is associated with a decrease in plasma norepinephrine concentration and urinary excretion

We investigated the effect of a 48 h triglyceride infusion on the subsequent insulin secretion in response to glucose in healthy men. We measured the variations in plasma concentration and urinary excretion of catecholamines as an indirect estimation of sympathetic tone. For 48 h, 20 volunteers received a triglyceride/heparin or a saline solution, separated by a 1-month interval. At time 48 h, insulin secretion in response to glucose was investigated by a single iv glucose injection (0.5 g/kg(-1)) followed by an hyperglycemic clamp (10 mg.kg(-1).min(-1), during 50 min). The triglyceride infusion resulted in a 3-fold elevation in plasma free fatty acids and an increase in insulin and C-peptide plasma concentrations (1.5- and 2.5-fold, respectively, P < 0.05), compared with saline. At time 48 h of lipid infusion, plasma norepinephrine (NE) concentration and urinary excretion levels were lowered compared with saline (plasma NE: 0.65 +/- 0.08 vs. 0.42 +/- 0.06 ng/ml, P < 0.05; urinary excretion: 800 +/- 70 vs. 620 +/- 25 nmol/24 h, P < 0.05). In response to glucose loading, insulin and C-peptide plasma concentrations were higher in lipid compared with saline infusion (plasma insulin: 600 +/- 98 vs. 310 +/- 45 pM, P < 0.05; plasma C-peptide 3.5 +/- 0.2 vs. 1.7 +/- 0.2 nM, P < 0.05). In conclusion, in healthy subjects, a 48-h lipid infusion induces basal hyperinsulinemia and exaggerated insulin secretion in response to glucose which may be partly related to a decrease in sympathetic tone.

The peptidyl-prolyl isomerase Pin1 interacts with hSpt5 phosphorylated by Cdk9

We identify and characterize several phosphorylated forms of the hSpt5 subunit of the DRB sensitivity-inducing factor (DSIF). A 175-kDa phosphorylated form of hSpt5 is bound to nuclei of interphase HeLa cells. This form is rapidly dephosphorylated when cultured cells are exposed to various drugs belonging to distinct chemical families. All these compounds are known to inhibit the protein kinase Cdk9, which phosphorylates in vitro hSpt5 and Rpb1, the largest subunit of RNA polymerase II. The efficiency to promote the dephosphorylation of both proteins matches their capacity to inhibit purified Cdk9 kinase, suggesting that Cdk9 is the major kinase phosphorylating hSpt5 and Rpb1 in vivo. We show that Cdk9 phosphorylates both the CTR1 and the CTR2 domains of recombinant hSpt5. These domains contain numerous serine-proline and threonine-proline residues similar to those found in the carboxyl-terminal domain (CTD) of Rpb1. The structural homology between hSpt5 CTRs and the Rpb1 CTD is further highlighted by the presence on both proteins of a phosphoepitope recognized by the monoclonal antibody CC-3. Of particular interest, the peptidyl-prolyl isomerase Pin1 interacts with Cdk9-phosphorylated hSpt5. Cdk9 dependent phosphorylation of Rpb1 and hSpt5 followed by Pin1 interaction might thus contribute to the regulation of transcription, pre-mRNA maturation, and the dynamics of these proteins in interphase and mitosis.

The polar headgroup of the detergent governs the accessibility to water of tryptophan octyl ester in host micelles

Many attempts have been made to rationalize the use of detergents for membrane protein studies [J. Biol. Chem. 264 (1989) 4907]. The barrier properties of the detergent headgroup may be one parameter critically involved in protein protection. In this paper, we analyzed these properties using a model system, by comparing the accessibility of tryptophan octyl ester (TOE) to water-soluble collisional quenchers (iodide and acrylamide) in three detergent micelles. The detergents used differed only in the chemical nature of their polar headgroups, zwitterionic for dodecylphosphocholine (DPC) and nonionic for octa(ethylene glycol) dodecyl monoether (C(12)E(8)) and dodecylmaltoside (DM). In all cases, in phosphate buffer at pH 7.5, the binding of 5 microM TOE was complete in the presence of a slight excess of detergent micelles over TOE molecules, resulting in a significant blue shift and greater intensity of TOE fluorescence emission. The resulting quantum yield of bound TOE was between 0.08 (in DPC) and 0.12 (in DM) with an emission maximum (lambda(max)) of approximately 335 nm whatever the detergent micelle. Time-resolved fluorescence intensity decays of TOE at lambda(max) were heterogeneous in all micelles (3-4 lifetime populations), with mean lifetimes of 1.7 ns in DPC, and 2 ns in both C(12)E(8) and DM. TOE fluorescence quenching by iodide, in detergent micelles, yielded linear Stern-Volmer plots characteristic of a dynamic quenching process. The accessibility of TOE to this ion was the greatest with C(12)E(8), followed by DPC and finally DM (Stern-Volmer quenching constants K(sv) of 2 to 5.5 M(-1)). In contrast, the accessibility of TOE to acrylamide was greatest with DPC, followed by C(12)E(8) and finally DM (K(sv)=2.7-7.1 M(-1)). TOE also presents less rotational mobility in DM than in the other two detergents, as shown from anisotropy decay measurements. These results, together with previous TOE quenching measurements with brominated detergents [Biophys. J. 77 (1999) 3071] provide reference data for analyzing Trp characteristics in peptide (and more indirectly protein)-detergent complexes. The main finding of this study was that TOE was less accessible (to soluble quenchers) in DM than in DPC and C(12)E(8), the cohesion of DM headgroup region being suggested to play a role in the ability of this detergent to protect function and stability of solubilized membrane proteins.

[Anesthetic blockade of the greater occipital nerve in migraine prophylaxis]

Migraine comprises a great many encephalic structures in its pathophysiology with the trigeminal nerve (TN) type being one of the main ones. For the purpose of determining a possible influence of the greater occipital nerve (GON) on migraine behavior, 37 patients who showed this pathology were studied. Using a double blind "cross over" group and submitting those patients to a GON infiltration with bupivacaina 0.5% (BP) and physiological serum 0.9% (PS), the clinical effects were evaluated: subjectively, through a pain analytical visual scale; objectively, by determining the threshold of pain perception (algometry). The comparison between the two groups (BP-PS) and (PS-BP) has shown that the number and duration of the attacks did not show significant statistical differences during the study. The intensity of the attacks was lower in group (BP-PS) only after the second infiltration (p=0.020), in the other moments no differences have been observed between the groups. The conclusion is that the anesthetic blockage with BP on the GON does not change the number of crises and their duration, but it does provokes an intensity reduction after 60 days from the infiltration. The results shown here suggest that GON participates in the cranial nociceptive modulation during crises of migraine without aura.

[Adrenal vein catheterization in primary hyperaldosteronism: aid in surgical decision making?]

The localisation of aldosterone-producing adenomas (APA's) remains difficult. Indeed, CT scan may not detect small APA's while CT detected tumours do not necessarily produce aldosterone.

OBJECTIVE

To evaluate the value of adrenal vein catheterization (AVC) for the diagnosis of APA's and also the rates of unsuccessful procedures and complications.

PATIENTS

One-hundred-and-nine hypertensives with biological features of primary hyperaldosteronism were included. Plasma sodium, potassium, aldosterone and renin levels were obtained after one night in lying position. Aldosterone and renin levels were also measured after a one-hour walking period and after a sodium expansion with saline. All patients underwent a CT scan and AVC. For adrenal samples, the ratio of aldosterone to cortisol concentrations was calculated for both sides. Both ratios were divided by the opposite one and the higher was retained as an index of laterization (IL). For lack of a golden standard variable, we have taken as a working hypothesis that operated patients had an APA (n = 38) and the non operated ones bilateral hypereplasia (n = 71).

RESULTS

Operated patients had a shorter history of hypertension, more frequently a left ventricular hypertrophy on ECG, and lower serum creatinine and potassium levels, along with a higher sodium level. None of these features appeared discriminant, however. Presence of a 10-mm tumour on CT scan was not significantly different between the 2 groups. Operated patients had more than a five-fold higher IL compared with that of non-operated patients. Analysis using a ROC curve showed that the value of 12 for "IL" was an acceptable operational criterium of lateralization, producing a specificity of 90%, while maintaining a sensitivity of 62%. AVC appeared most useful in case of middle-range pre-test probability of an APA being present, that is when when clinical, biological, or radiological features are not fully concordant. The rate of unsuccessful procedure and the rate of complications were low (1.8% and 3.6%, respectively).

CONCLUSION

With a low iatrogenicity, AVC appears helpful in indicating surgery mostly when clinical, biological, and CT scan features are not fully concordant. A value of 12 for IL appears to allow a high specificity while retaining an acceptable sensitivity.

Tumor growth inhibition in vivo and G2/M cell cycle arrest induced by antisense oligodeoxynucleotide targeting thymidylate synthase

Chemotherapeutic agents targeting thymidylate synthase (TS) are effective against human tumors. Efficacy is limited by drug resistance, often mediated by TS overexpression. Treatment of HeLa cells in vitro with an antisense oligodeoxynucleotide (ODN 83) targeting human TS mRNA reduces TS mRNA and protein levels, inhibits cell proliferation, and sensitizes cells to TS-targeting drugs (Ferguson et al., 1999). The present study investigates the mechanism by which ODN 83 inhibits cell proliferation and examines its antitumor efficacy in vivo. ODN 83 treatment did not induce apoptosis in HeLa cells in vitro but caused accumulation of cells at G2/M. In contrast, TS-targeting chemotherapeutics arrest at G1 or S. Antisense down-regulation reduced TS mRNA levels in human colon cancer (HT29) cells by 40% in vitro, resulted in G2/M arrest, and reduced proliferation without enhanced cell death. Growth of HT29 tumors in immunocompromised mice was significantly inhibited when antisense ODN 83 treatment began promptly after tumor implantation and was accompanied by a 40% reduction in TS protein levels. Growth of tumors allowed to reach 400 mm3 prior to ODN administration was unaffected by antisense ODN 83. Radiolabeled ODNs were localized to the tumor periphery but evenly distributed in normal tissue. Thus, down-regulation of TS mRNA and protein by antisense ODN treatment exerts a novel G2/M cell cycle block without increasing cell death and inhibits HT29 tumor cell growth in vivo. Antisense ODN 83 may be an effective therapy for colon carcinoma, alone or in combination with TS-targeting cytotoxic drugs.

The role of surgery and postoperative chemoradiation therapy in patients with lymph node positive esophageal carcinoma

BACKGROUND

Patients who have undergone resection for lymph node positive esophageal carcinoma are at high risk of disease recurrence and early death. The role of postoperative adjuvant therapy in this population needs to be determined.

METHODS

A retrospective review of all patients with resected esophageal carcinoma between 1991 and 1997 was performed. Lymph node positive (N1) patients who received concurrent or sequential postoperative radiotherapy (50 grays) and chemotherapy (cisplatin, 5-fluorouracil with or without epirubicin) were compared with N1 patients who underwent surgery alone. The disease free and overall survival rates were calculated using the Kaplan-Meier method, and groups were compared with the log-rank test. Prognostic variables were entered into a Cox regression model controlling for age, weight loss, T status, Eastern Cooperative Oncology Group (ECOG) score, and treatment received.

RESULTS

A total of 165 patients were reviewed: Twenty-eight N1 patients underwent surgery alone (S group), and 38 N1 patients underwent surgery and received postoperative chemoradiation therapy (CRT group). Preoperative risk factors, tumor characteristics, ECOG scores, and lengths of hospital stay were similar. The disease free survival rates were similar (S group, 10.6 months; CRT group, 10.2 months), although the S group had more local disease recurrences (S group, 35%; CRT group, 13%; P = 0.09). The overall survival rate according to the Kaplan-Meier analysis showed a significant survival advantage with postoperative CRT radiation (log-rank test; P = 0.001). The median overall survival for the CRT group was 47.5 months, which was significantly longer than that of the S group (14.1 months). The ECOG score, T status, and treatment received all were found to influence survival significantly on univariate analysis. In the multivariate model, postoperative CRT was a predictor of survival (P = 0.007; risk ratio for mortality, 0.35; 95% confidence interval, 0.16-0.76) and was correlated with a significantly decreased risk of death in patients with lymph node positive, resected esophageal carcinoma.

CONCLUSIONS

Postoperative CRT appears to prolong survival in patients with lymph node positive, resected esophageal carcinoma.

Blood pressure and heart rate determination by radiotelemetry in mice

Mice are not commonly used in cardiovascular physiology, especially in space physiology because of methodological problems. The initial studies that have monitored arterial pressure and heart rate in mice used the tail cuff plethysmography method or classical catheterization techniques with a catheter liable to an external pressure transducer. But for long term arterial pressure measurements the studies have been facilitated by the development of radiotelemetry. This is a less constraining method as classical one allowing to monitor in continuous in freely moving animal blood pressure, heart rate and temperature. This technique allows to record these parameters thank to an implanted transmitter without physical connection with the monitoring system. The aim of this work was to valid the use of the radiotelemetry in mice to evaluate arterial blood pressure and heart rate during different stress conditions (but only control data are described in this paper).

Myofibroblast: a prognostic marker and target cell in progressive renal disease

Myofibroblasts play an important role in many tissue injuries, and particularly in renal disease. The myofibroblast differentiation is an early event in the development of fibrosis. Myofibroblast-like cells express smooth muscle (SM) cytoskeletal markers (alpha-SM actin in particular) and participate actively in the production of extracellular matrix. Identification of early risk factors, particularly histological criteria, could be useful to identify patients at risk of progressive renal failure and needing a treatment. The evaluation of myofibroblast differentiation in renal tissue may reflect the intensity of tissue injury, predict long term outcome of chronic renal disease and help physicians to select therapeutic choices. More than a disease activity indicator. myofibroblasts appear to be a pivotal target for future therapies in progressive renal disease.

Annexin A5 D226K structure and dynamics: identification of a molecular switch for the large-scale conformational change of domain III

The domain III of annexin 5 undergoes a Ca(2+)- and a pH-dependent conformational transition of large amplitude. Modeling of the transition pathway by computer simulations suggested that the interactions between D226 and T229 in the IIID-IIIE loop on the one hand and the H-bond interactions between W187 and T224 on the other hand, are important in this process [Sopkova et al. (2000) Biochemistry 39, 14065-14074]. In agreement with the modeling, we demonstrate in this work that the D226K mutation behaves as a molecular switch of the pH- and Ca(2+)-mediated conformational transition. In contrast, the hydrogen bonds between W187 and T224 seem marginal.

Gender and morals in Spanish Catholic youth culture: a case study of the Marian Congregations 1930-1936

Jesuit-run Marian Congregations proliferated in 1930s Spain. Drawing on literature produced for their members, this article demonstrates how gendered understandings were fundamental to the congregations' symbolic delineation of an uncontaminated Catholic space. Visions of an incorrupt male elite abound, reinforcing the Jesuits' educational mission among future leaders and opinion-formers. In contrast, the purity of women and children was seen as a sign of society's moral health. Modesty was the quintessential female virtue. Yet, the cult of the Virgin Mary suggested that the virginal female body was both tool and symbol in the struggle against a fallen world. Girls were, therefore, charged with the task of moral guardianship. Such campaigns were emblematic of Spanish Catholicism's tendency to proffer religious solutions to social problems.

Origin of laurdan sensitivity to the vesicle-to-micelle transition of phospholipid-octylglucoside system: a time-resolved fluorescence study

The fluorescent probe laurdan has been shown to be sensitive to the vesicle-to-micelle transition of phosphatidylcholine/octylglucoside (M. Paternostre, O. Meyer, C. Grabielle-Madelmont, S. Lesieur, and, Biophys. J. 69:2476-2488). On the other hand, a study on the photophysics of laurdan in organic solvents has shown that the complex de-excitation pathway of the probe can be described by two successive processes, i.e., an intramolecular charge transfer followed by dielectric relaxation of the solvent if polar. These two excited-state reactions lead to three emitting states, i.e., a locally excited state, a charge transfer state, and a solvent relaxed state (M. Viard, J. Gallay, M. Vincent, B. Robert and, Biophys. J. 73:2221-2234). Experiments have been performed using time-resolved fluorescence on the probe inserted in amphiphile aggregates (mixed liposomes, mixed micelles) different in detergent-to-lipid ratios. The results have been compared with those obtained for laurdan inserted in dipalmitoyl phosphatidylcholine liposomes in the gel and in the fluid lamellar phase. Except for laurdan in dipalmitoyl phosphatidylcholine liposomes in the gel lamellar phase, the red part of the emission spectra originates from the de-excitation of the relaxed excited state of laurdan, indicating that indeed the dielectric relaxation process is an important phenomena in the ground-state return pathway of this probe. On the other hand, the maximization entropy method (MEM) analysis of the fluorescence decay recorded in the blue part of the emission spectra indicates that the dielectric relaxation is not the only reaction occurring to the excited state of laurdan. Moreover, the analysis of the fluorescence decays of laurdan inserted in gel lamellar dipalmitoylphosphatidylcholine (DPPC) liposomes indicates excited-state reactions, although dielectric relaxation is impossible. These results are in agreement with the de-excitation pathway determined from laurdan behavior in organic solvent even if, in most of the aggregates studied in this work, the major phenomenon is the dielectric relaxation of the solvent. All along the vesicle-to-micelle transition, we have observed that the lifetime of the relaxed excited state of laurdan continuously decreases probably due to a dynamic quenching process by water molecules. On the other hand, the time constant of the dielectric relaxation process remains almost unchanged in the lamellar part of the transition but abruptly decreases as soon as the first mixed micelle is formed. This decrease is continuous all over the rest of the transition even if it is more pronounced in the mixed liposomes' and mixed micelles' coexistence. The increase of the octylglucoside-to-lipid ratio of the mixed micelles via the change of the size and the shape of the aggregates may facilitate the penetration and the mobility of water molecules. Therefore, during the vesicle-to-micelle transition, laurdan probes the evolution of both the amphiphile packing in the aggregates and the increase of the interface polarity. This study finally shows that the detergent-to-lipid ratio of the mixed micelles is an important parameter to control to limit the penetration and the mobility of water within the amphiphile aggregates and that laurdan is a nice tool to monitor this phenomenon.

[Concomitant treatment of psychosis and drug addiction.]

The high prevalence of addiction problems of people with psychosis and the lack of resources to respond to their complex reality has lead a multidisciplinary team at the Centre de santé mentale communautaire (CSMC) to establish a group allowing interventions on drug addiction and psychosis in a concomitant way. Following a brief presentation of problems and intervention models proposed in the literature, this article aims at summarizing the experience of the CSMC and their strategy in order to respond to the needs of these patients. Thus, this article presents the reasons for modifications made over the years, the relevance of the motivational approach with these patients who are often unmotivated in changing their behaviour regarding substance abuse and the strengths and limits of this approach. The objectives of the therapeutic group, the framework, content and clientele are then discussed. Finally the authors examine various perspectives.

Substrate-induced fit of the ATP binding site of cytidine monophosphate kinase from Escherichia coli: time-resolved fluorescence of 3'-anthraniloyl-2'-deoxy-ADP and molecular modeling

The conformation and dynamics of the ATP binding site of cytidine monophosphate kinase from Escherichia coli (CMPK(coli)), which catalyzes specifically the phosphate exchange between ATP and CMP, was studied using the fluorescence properties of 3'-anthraniloyl-2'-deoxy-ADP, a specific ligand of the enzyme. The spectroscopic properties of the bound fluorescent nucleotide change strongly with respect to those in aqueous solution. These changes (red shift of the absorption and excitation spectra, large increase of the excited state lifetime) are compared to those observed in different solvents. These data, as well as acrylamide quenching experiments, suggest that the anthraniloyl moiety is protected from the aqueous solvent upon binding to the ATP binding site, irrespective of the presence of CMP or CDP. The protein-bound ADP analogue exhibits a restricted fast subnanosecond rotational motion, completely blocked by CMP binding. The energy-minimized models of CMPK(coli) complexed with 3'-anthraniloyl-2'-deoxy-ADP using the crystal structures of the ligand-free protein and of its complex with CDP (PDB codes and, respectively) were compared to the crystal structure of UMP/CMP kinase from Dictyostelium discoideum complexed with substrates (PDB code ). The key residues for ATP/ADP binding to CMPK(coli) were identified as R157 and I209, their side chains sandwiching the adenine ring. Moreover, the residues involved in the fixation of the phosphate groups are conserved in both proteins. In the model, the accessibility of the fluorescent ring to the solvent should be substantial if the LID conformation remained unchanged, by contrast to the fluorescence data. These results provide the first experimental arguments about an ATP-mediated induced-fit of the LID in CMPK(coli) modulated by CMP, leading to a closed conformation of the active site, protected from water.

Modulation by Ca(2+) and by membrane binding of the dynamics of domain III of annexin 2 (p36) and the annexin 2-p11 complex (p90): implications for their biochemical properties

The modulation of the local structure and dynamics of domain III of annexin 2 (Anx2), in both the monomeric (p36) and heterotetrameric forms (p90), by calcium and by membrane binding was studied by time-resolved fluorescence intensity and anisotropy measurements of the single tryptophan residue (W212). The results yield the same dominant excited-state lifetime (1.4 ns) in both p36 and p90, suggesting that the conformation and environment of W212 are very similar. The fluorescence anisotropy decay data were analyzed by associative (two-dimensional) as well as nonassociative (one-dimensional) models. Although no statistical criterion is decisive for one model versus the other, only the associative model allows recovery of a physically relevant value of the Brownian rotational correlation of the protein. Using the associative model, a nanosecond flexibility is detectable in p90 but not in p36. When Ca(2+) binds in the millimolar concentration range to both forms of Anx2, a conformational change takes place leading to an increase of the major excited-state lifetime (2.6 ns) and to a suppression of the W212 local flexibility of p90. Binding to membranes of either p36 or p90 in the presence of Ca(2+) does not induce any conformational change other than that provoked by Ca(2+) binding alone. The W212 local flexibility in both proteins increases significantly, however, in their membrane-bound forms. In the presence of membranes, the conformation change of domain III in p90 displays a sensitivity to Ca(2+) 2 orders of magnitude higher than that of p36, reaching intracellular sub-micromolar concentration ranges. This higher Ca(2+) sensitivity correlates with the Ca(2+)-dependent membrane aggregation but not with their Ca(2+)-dependent binding to membranes. The significance of these structural and dynamical changes for the function of the protein is discussed.

Molecular recognition of human CD1b antigen complexes: evidence for a common pattern of interaction with alpha beta TCRs

Ag-specific T cell recognition is mediated through direct interaction of clonotypic TCRs with complexes formed between Ag-presenting molecules and their bound ligands. Although characterized in substantial detail for class I and class II MHC encoded molecules, the molecular interactions responsible for TCR recognition of the CD1 lipid and glycolipid Ag-presenting molecules are not yet well understood. Using a panel of epitope-specific Abs and site-specific mutants of the CD1b molecule, we showed that TCR interactions occur on the membrane distal aspects of the CD1b molecule over the alpha1 and alpha2 domain helices. The location of residues on CD1b important for this interaction suggested that TCRs bind in a diagonal orientation relative to the longitudinal axes of the alpha helices. The data point to a model in which TCR interaction extends over the opening of the putative Ag-binding groove, making multiple direct contacts with both alpha helices and bound Ag. Although reminiscent of TCR interaction with MHC class I, our data also pointed to significant differences between the TCR interactions with CD1 and MHC encoded Ag-presenting molecules, indicating that Ag receptor binding must be modified to accommodate the unique molecular structure of the CD1b molecule and the unusual Ags it presents.

Better preservation of endothelial function and decreased activation of the fetal renin-angiotensin pathway with the use of pulsatile flow during experimental fetal bypass

OBJECTIVE

Pulsatile flow was shown to overcome the progressive rise in peripheral and placental vascular resistances observed during steady-flow bypass, this rise being counteracted by inhibition of nitric oxide synthase. This study quantifies the release of endothelial vasoactive substances during a 60-minute in utero model of fetal bypass.

METHODS

Fetuses were randomly allocated into 1 of 2 groups (steady flow, n = 8, or pulsatile flow, n = 13) and subjected to bypass through central cannulation and perfusion with either a centrifugal or pulsatile (125 beats x min(-1)) blood pump.

RESULTS

Lactate concentration was high, starting at fetal exteriorization and increasing during fetal preparation in the 2 groups. Once bypass was established, the rise was significant only in the steady-flow group. Plasma nitric oxide metabolites, similar before bypass, reached higher levels during pulsatile flow at the end of bypass (99+/-9 vs. 82+/-23 micromol x L(-1); P =.037). Levels of urinary nitric oxide metabolites were significantly higher in the pulsatile-flow than in the steady-flow group (764+/-143 vs. 508+/-240 micromol x L(-1); P =.005). Plasma cyclic guanosine monophosphate levels increased after 30 minutes of bypass in the pulsatile-flow group (25+/-18 vs. 12+/-8 pmol x mL(-1); P =.004), and urinary cyclic guanosine monophosphate excretion was higher in the pulsatile-flow group (517+/-450 vs. 118+/-78 pmol x mL(-1); P =.024). Plasma endothelin-1 levels increased in the 2 groups and were higher in the steady-flow group at 30 minutes (27+/-5 vs. 23+/-2 pg x mL(-1); P =.04) and 60 minutes of bypass (39+/-7 vs 32 +/- 6 pg x mL(-1); P =.04). Plasma renin concentration increased significantly during bypass only in the steady-flow group (26+/-10 vs. 57+/-42 in ng A1 x mL(-1) x h(-1); P =.04).

CONCLUSIONS

Improved placental and peripheral perfusion during fetal pulsatile-flow bypass may be mediated by preservation of fetal/maternal endothelial nitric oxide biosynthetic mechanisms and/or decreased activation of the fetal renin-angiotensin pathway.

Unusual 1H NMR chemical shifts support (His) C(epsilon) 1...O==C H-bond: proposal for reaction-driven ring flip mechanism in serine protease catalysis

13C-selective NMR, combined with inhibitor perturbation experiments, shows that the C(epsilon)(1)H proton of the catalytic histidine in resting alpha-lytic protease and subtilisin BPN' resonates, when protonated, at 9.22 ppm and 9.18 ppm, respectively, which is outside the normal range for such protons and approximately 0.6 to 0.8 ppm further downfield than previously reported. They also show that the previous alpha-lytic protease assignments [Markley, J. L., Neves, D. E., Westler, W. M., Ibanez, I. B., Porubcan, M. A. & Baillargeon, M. W. (1980) Front. Protein Chem. 10, 31-61] were to signals from inactive or denatured protein. Simulations of linewidth vs. pH demonstrate that the true signal is more difficult to detect than corresponding signals from inactive derivatives, owing to higher imidazole pK(a) values and larger chemical shift differences between protonated and neutral forms. A compilation and analysis of available NMR data indicates that the true C(epsilon)(1)H signals from other serine proteases are similarly displaced downfield, with past assignments to more upfield signals probably in error. The downfield displacement of these proton resonances is shown to be consistent with an H-bond involving the histidine C(epsilon)(1)H as donor, confirming the original hypothesis of Derewenda et al. [Derewenda, Z. S., Derewenda, U. & Kobos, P. M. (1994) J. Mol. Biol. 241, 83-93], which was based on an analysis of literature x-ray crystal structures of serine hydrolases. The invariability of this H-bond among enzymes containing Asp-His-Ser triads indicates functional importance. Here, we propose that it enables a reaction-driven imidazole ring flip mechanism, overcoming a major dilemma inherent in all previous mechanisms, namely how these enzymes catalyze both the formation and productive breakdown of tetrahedral intermediates.