[Isolation of Vibrio strains in French coastal waters and infection with Vibrio cholerae non-O1/non-O139]

OBJECTIVE

Although the incidence in France of V. cholerae non-O1/non-O139 infection in man has increased since 1996, it remains low (7 cases in 1999). After the death in 1994 of an immunodepressed patient presenting a skin lesion showing superinfection by a strain of non-O1/non-O139 V. cholerae following exposure to seawater, we examined 22 samples of sea-water collected from 20 French coastal areas (Mediterranean coast).

METHODS

The sea-water samples were filtered and enriched with alkaline peptone water (APW), and the strains of Vibrio were isolated on TCBS, SS and BCP media and identified using the API 20 E system (bioMérieux, France).

RESULTS

We isolated 6 strains belonging to 3 species of Vibrio: 2 V. cholerae (non-O1/non-O139), 3 V. parahaemolyticus and 1 V. alginolyticus. One of the V. cholerae strains was isolated from sea-water sampled at the coastal town in which the patient had been staying. The seawater strains exhibited high sensitivity (MIC determined by agar dilution) to the following antibiotics: aminoglycosides, tetracyclines, azithromycin, cotrimoxazole, rifampicin and fluoroquinolones. The beta-lactams were very active against strains of V. cholerae isolated from seawater, while the strain isolated from this patient presented a new carbenicillinase (CARB-6) recently described.

CONCLUSION

The presence of Vibrio in seawater along the French coast-line constitutes a risk for immunocompromised patients, and the severity of Vibrio infections warrants improved monitoring both of these organisms and of the marine environment. In addition, awareness on the part of doctors would allow patients at risk to be warned against these dangers.

Improved renal preservation with PB-3 flush solution during 72 h of cold storage

Previously, PB-2 flush solution has been found to be superior to Collins 2 solution (C-2) in extending renal viability in the dog. To further characterize preservation mechanisms, we studied mitochondrial oxidative function during 72 h of cold storage comparing PB-3, UW-1, and C-2 flush storage solutions. Complex 1 dependent mitochondrial oxidative phosphorylation (MOP) was found to be significantly less (P < 0.001) at 5 h and 72 h of cold storage (P < 0.001) for the C-2 compared to the other flush groups. Complex 2 dependent MOP had parallel results, having significantly less function (P < 0.002) at 5 h and 72 h (P < 0.02) of cold storage in the C-2 group compared to the other groups. PB-3 and UW-1 solutions were noted to be comparable, suggesting possible equivalent preservation efficacy. Nevertheless the components of PB-3 at the level of MOP contributed significantly to better preservation compared to C-2 solution.

Pallidal and thalamic neurostimulation in severe tardive dystonia

A 70 year old woman presented with a 6 year history of medically refractory severe tardive dystonia. After informed consent, a bilateral stereotactic electrode placement targeting the ventral intermediate thalamic nucleus (VIM) and the globus pallidus internus (GPi) was performed. After bilateral stimulation of the GPi, the patient showed a clear and stable improvement of the painful dystonic syndrome within hours. Stimulation of the VIM did not improve the hyperkinetic movements and simultaneous stimulation of both the GPi and the VIM did not result in any additional benefit. The possible pathophysiological mechanisms are discussed.

Sepsis-associated purpura fulminans in adults

Sepsis-associated purpura fulminans is defined as septicemia, shock, disseminated intravascular coagulation and circulatory failure leading to multiple organ dysfunction. 40-70% of patients with sepsis-associated purpura fulminans die. Early prognostic factors in adults have not been well delineated yet. Aim of our study was 1) to evaluate currently used scoring systems for meningococcal septicemia in the setting of sepsis-associated purpura fulminans and 2) to assess if other parameters are feasible as early prognostic factors. From 1.1 1994-31.12.1998 twelve patients (female: 7; mean age: 31 (21; 43) years) were studied. Six patients (50%) died within 2 hours and 7 days after admission despite standard intensive treatment. On admission non-survivors had a more pronounced degree of disseminated intravascular coagulation compared to survivors (platelet count 18000 (15000; 45000) G/l vs. 119.000 (111000; 152000) G/l, (p = 0.03); fibrinogen 67 (50; 108) mg/dl vs. 356 (234; 483) mg/dl, (p = 0.02); PTZ 28% (20%; 30%) vs. 44% (35%; 51%), (p = 0.05); aPTT 120 (120; 128) sec vs. 46 (44; 69) sec, (p = 0.001). Severity of lactic acidosis was significantly higher in non-survivors than in survivors (pH 7.08 (6.92; 7.21) vs. pH 7.4 (7.25; 7.4), (p = 0.02); lactate 13.5 (11; 15) mval/l vs. 6.0 (4.4; 6) mval/l, (p = 0.02); data presented as median (25-75% interquartile range). In our patients the Glasgow Meningococcal Septicemia Prognostic Score (GMSPS) and the Niklasson-Score failed to distinguish between survivors and non-survivors (GMSPS 7 (6; 11) vs 7.5 (7; 9) out of 15; predicted mortality according to Niklasson-Score 73% vs 88%). There was no difference in the APACHE II Score (22 (18.5, 24) vs 22 (20.25, 26)). The severity of disseminated intravascular coagulation assessed by routine laboratory parameters and the degree of lactic acidosis on admission were the strongest predictors of outcome in patients with sepsis-associated purpura fulminans. Scoring systems developed for patients with meningococcal septicemia are of limited value in the setting of sepsis-associated purpura fulminans.

Inhibition of RANTES/CCR1-mediated chemotaxis by cosalane and related compounds

The anti-HIV agent cosalane and several of its analogues inhibited RANTES-induced migration of human monocytes, but they did not inhibit migration induced by MIP1alpha or MIP1beta. RANTES-induced migration of single receptor CCRI-HEK transfectants was also inhibited by the cosalanes. Acetylation of the reactive amino groups of RANTES abrogated the inhibitory activity of cosalane. The data suggest that cosalane and its structural analogues may interfere with the RANTES/CCR1 interaction by binding to RANTES.

The influence of pallidal deep brain stimulation on striatal dopaminergic metabolism in the rat

Deep brain stimulation of the globus pallidus internus has been recently shown to alleviate parkinsonian symptoms and levodopa-induced dyskinesias. However, its exact mechanisms of action are unclear. Pallidal neurones are connected via various pathways to the dopaminergic nigrostriatal system. In the present study we investigated the hypothesis that deep brain stimulation of the entopeduncular nucleus (corresponds to the human internal pallidum) affects striatal dopaminergic metabolism in naive and 6-hydroxydopamine (6-OHDA) lesioned rats using microdialysis. Our results show that stimulation of the entopeduncular nucleus does not significantly affect striatal dopamine metabolism (of dopamine, 3, 4-dihdroxyphenylacetic acid and homovanillic acid) in naive and 6-OHDA-lesioned animals. They contrast with our previous observations that deep brain stimulation of the subthalamic nucleus increases striatal dopamine metabolism suggesting differential effects of these nuclei on striatal dopamine metabolism.

Flow between two sites on a percolation cluster

We study the flow of fluid in porous media in dimensions d=2 and 3. The medium is modeled by bond percolation on a lattice of L(d) sites, while the flow front is modeled by tracer particles driven by a pressure difference between two fixed sites ("wells") separated by Euclidean distance r. We investigate the distribution function of the shortest path connecting the two sites, and propose a scaling ansatz that accounts for the dependence of this distribution (i) on the size of the system L and (ii) on the bond occupancy probability p. We confirm by extensive simulations that the ansatz holds for d=2 and 3. Further, we study two dynamical quantities: (i) the minimal traveling time of a tracer particle between the wells when the total flux is constant and (ii) the minimal traveling time when the pressure difference is constant. A scaling ansatz for these dynamical quantities also includes the effect of finite system size L and off-critical bond occupation probability p. We find that the scaling form for the distribution functions for these dynamical quantities for d=2 and 3 is similar to that for the shortest path, but with different critical exponents. Our results include estimates for all parameters that characterize the scaling form for the shortest path and the minimal traveling time in two and three dimensions; these parameters are the fractal dimension, the power law exponent, and the constants and exponents that characterize the exponential cutoff functions.

Optimization of contrast-enhanced MR angiography of the hands with a timing bolus and elliptically reordered 3D pulse sequence

Our objective was to optimize bolus administration and sequence setting in gadolinium-enhanced magnetic resonance (MR) angiography of the hands. Elliptically reordered three-dimensional (3D) spoiled gradient-echo sequence with non-slab-selective radio frequency excitation was optimized according to the measurements of arterial and venous time-signal curves in 21 patients. Great variations in bolus arrival time and arterio-venous transit time could be observed. In most patients high-quality arterial depiction could be obtained with minor venous contamination. Contrast-to-noise, spatial resolution, and selective arterial filling is still a challenge for 3D MR angiography of the hand but can be optimized using Gadolinium-BOPTA and a dedicated pulse sequence setting with exact bolus timing.

Further delineation of the DOOR syndrome

Two related sibships from an extended family have been observed with the features of the DOOR syndrome. These features included deafness, onychodystrophy, osteodystrophy, microcephaly, and global developmental retardation with progressive blindness. Seizures, which were associated with hypsarrhythmia, were frequent and difficult to control and ultimately were the cause of death in two patients. An MRI brain scan of case 1 showed a number of abnormalities including markedly reduced myelination. The urine organic acid analysis showed a ten-fold increase of 2-oxoglutarate. In one patient the placenta was noted to have multiple fluid filled cysts, which is a feature reported in other metabolic diseases. It is suggested that there may be genetic heterogeneity in the syndrome, and the presence of increased 2-oxoglutarate is associated with a more severe phenotype which is frequently lethal.

Comparison of heat and pressure treatments of skim milk, fortified with whey protein concentrate, for set yogurt preparation: effects on milk proteins and gel structure

Heat (85 degrees C for 20 min) and pressure (600 MPa for 15 min) treatments were applied to skim milk fortified by addition of whey protein concentrate. Both treatments caused > 90 % denaturation of beta-lactoglobulin. During heat treatment this denaturation took place in the presence of intact casein micelles; during pressure treatment it occurred while the micelles were in a highly dissociated state. As a result micelle structure and the distribution of beta-lactoglobulin were different in the two milks. Electron microscopy and immunolabelling techniques were used to examine the milks after processing and during their transition to yogurt gels. The disruption of micelles by high pressure caused a significant change in the appearance of the milk which was quantified by measurement of the colour values L*, a* and b*. Heat treatment also affected these characteristics. Casein micelles are dynamic structures, influenced by changes to their environment. This was clearly demonstrated by the transition from the clusters of small irregularly shaped micelle fragments present in cold pressure-treated milk to round, separate and compact micelles formed on warming the milk to 43 degrees C. The effect of this transition was observed as significant changes in the colour indicators. During yogurt gel formation, further changes in micelle structure, occurring in both pressure and heat-treated samples, resulted in a convergence of colour values. However, the microstructure of the gels and their rheological properties were very different. Pressure-treated milk yogurt had a much higher storage modulus but yielded more readily to large deformation than the heated milk yogurt. These changes in micelle structure during processing and yogurt preparation are discussed in terms of a recently published micelle model.

Idiopathic pulmonary haemosiderosis

Idiopathic pulmonary haemosiderosis (IPH) is a rare disorder characterized by recurrent bouts of haemoptysis, iron deficiency anaemia, and pulmonary infiltrates on chest radiograph. We present such a case and believe that it is the first report from the Middle East.

Characterization of infectious bronchitis viruses isolated from outbreaks of disease in commercial flocks in Brazil

Fifteen isolations of infectious bronchitis (IB) virus were made from a total of 126 Brazilian poultry flocks of all ages that were examined. These flocks (14 chicken and 1 quail) were experiencing a variety of IB-like conditions including respiratory disease, digestive and kidney problems, and drops in egg production. One of the isolates was of the Massachusetts serotype. The remainder were examined by means of cross-neutralization tests in tracheal organ cultures and were shown to belong to at least four antigenic groups, all different from ones described previously in other countries. Some, but not all, of the flocks from which they were isolated had been vaccinated against IB with vaccines of the Massachusetts serotype. In vivo protection studies showed that the MA5 vaccine (of the Massachusetts serotype) protected well against challenge with four of these isolates, representing the different serotypes reported in this study.

[Preoperative examination of potential kidney transplantation donors: value of gadolinium-enhanced 3D MR angiography in comparison with DSA and urography]

PURPOSE

To assess a contrast-enhanced standardized MRA protocol for the presurgical evaluation of potential renal transplant donors.

METHODS

Twenty-three potential donors for renal transplantations were examined with gadolinium-enhanced, two-phase MR angiograms (1.5 T) and DSA/urography for the number of renal arteries, the presence of aberrant arterial and venous branches, renal artery stenoses and anatomy of the renal collecting system and ureters. The diagnostic value was assessed by evaluating different image processing modalities and interobserver variability.

RESULTS

Using maximum intensity projections (MIP) together with multiplanar reformatting (MPR), accessory arteries were detected with a sensitivity/specificity of 100%/98%. Depending on diagnostic experience, exclusive evaluation of MIP yielded a sensitivity/specificity of 67-100%/95-100%. Using MIP/MPR, venous depiction was good in 80%, with MIP solely in 30-40%. At least the proximal third of the ureter was visible in 67%.

CONCLUSION

MPR/MIP evaluation of two-phase, contrast-enhanced MRA provides an excellent depiction of renal vessel anatomy for presurgical evaluation of renal transplant donors. Exclusive MIP assessment is less reliable and depends strongly on the examiner's experience. For sufficient visualization of the ureters, either additional measurements or low-dose diuretic injection have to performed.

Dependence of conductance on percolation backbone mass

We study <sigma(M(B),r)>, the average conductance of the backbone, defined by two points separated by Euclidean distance r, of mass M(B) on two-dimensional percolation clusters at the percolation threshold. We find that with increasing M(B) and for fixed r, <sigma(M(B),r)> asymptotically decreases to a constant, in contrast with the behavior of homogeneous systems and nonrandom fractals (such as the Sierpinski gasket) in which conductance increases with increasing M(B). We explain this behavior by studying the distribution of shortest paths between the two points on clusters with a given M(B). We also study the dependence of conductance on M(B) above the percolation threshold and find that (i) slightly above p(c), the conductance first decreases and then increases with increasing M(B) and (ii) further above p(c), the conductance increases monotonically for all values of M(B), as is the case for homogeneous systems.

Nucleotide sequence of the bla(RTG-2) (CARB-5) gene and phylogeny of a new group of carbenicillinases

We determined the nucleotide sequence of the bla gene for the Acinetobacter calcoaceticus beta-lactamase previously described as CARB-5. Alignment of the deduced amino acid sequence with those of known beta-lactamases revealed that CARB-5 possesses an RTG triad in box VII, as described for the Proteus mirabilis GN79 enzyme, instead of the RSG consensus characteristic of the other carbenicillinases. Phylogenetic studies showed that these RTG enzymes constitute a new, separate group, possibly ancestors of the carbenicillinase family.

A 5-year epidemiological study of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae isolates in a medium- and long-stay neurological unit

Thirty-eight different strains of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae (ESBL Kp), isolated from urine and pus samples of 38 patients hospitalized in a medium- and long-stay neurology department between 1 January 1992 and 31 December 1996, were analysed by antibiotic resistance phenotyping, DNA macrorestriction by pulsed-field electrophoresis and isoelectric focusing of beta-lactamases. An epidemiological survey was conducted to identify risk factors for infection by ESBL Kp in this setting. The 38 isolates were distributed into 13 antibiotypes, three of which predominated (13, six and six isolates). The DNA macrorestriction pattern identified 15 genotypes, four of which predominated (11, six, four and four isolates). A combination of the two typing methods revealed several epidemic clones that emerged consecutively. Two main types of ESBL (SHV-2 and CTX-1) were identified by isoelectric focusing, the former predominating. The case-control study showed that the length of hospital stay, degree of malnutrition and dependency, and urinary sphincter status were the main factors significantly associated with ESBL Kp isolation.

High frequency stimulation of the subthalamic nucleus influences striatal dopaminergic metabolism in the naive rat

High frequency stimulation (HFS) of the subthalamic nucleus (STN) can partially alleviate motor symptoms in patients with Parkinson's disease (PD). However, the mechanism of action of HFS is incompletely understood. We investigated the effect of HFS (130 Hz) and low frequency stimulation (LFS, 20 Hz) of the STN on striatal dopaminergic transmission and metabolism using in vivo microdialysis in anaesthetized and freely moving rats. While LFS had no effect, HFS of the STN produced a delayed, stable and intensity-dependent increase of extracellular dopamine metabolites. Striatal extracellular levels of dopamine and 5-HIAA were not influenced by HFS or LFS in the present experimental paradigm. We conclude that HFS of the STN influences striatal dopaminergic metabolism in naive, nonlesioned rats.

Radiological classification of meniscocapsular tears of the anterolateral portion of the lateral meniscus of the knee

In an arthroscopic-MRI correlation study of acute injuries to the knee it was found that anterolateral meniscocapsular separations of the lateral aspect of the knee were missed on MRI reporting. Eighty sports-related injuries of the knee were seen by experienced orthopaedic surgeons at the University of Malaya Medical Centre and at the National Sports Centre, Malaysia from January 1996 to July 1997. Fifty of the patients were suspected to have meniscal tears that were either lateral or medial on clinical examination and they were sent for MRI. Many of these patients were tertiary referrals. Magnetic resonance imaging examinations in 27 of the 50 patients were reported as not showing any intrasubstance or obvious meniscocapsular tears, but arthroscopy performed on them revealed anterolateral meniscocapsular tears of the lateral meniscus of varying degrees in nine of these patients. In retrospect the tears could be seen on MRI, and a pattern to the tears was noted and classified as follows. Type 0, normal; type 1, torn inferior or superior meniscocapsular attachment; type 2, both meniscofemoral and meniscotibial ligaments torn but with minimal separation of meniscus and capsule by fluid or synovitis; and type 3, marked separation of meniscus and capsule by fluid (> 3 mm). Ten patients who did not undergo arthroscopy for various personal and financial reasons underwent MRI which showed type 1 and type 2 tears, and were treated conservatively. These patients were all asymptomatic after 4-6 weeks with regard to clinical signs, suggesting a lateral meniscal tear. Magnetic resonance imaging therefore does reveal minor degrees of meniscocapsular tears anterolaterally when one understands the normal anatomy in this region.

Fatal encephalitis due to Nipah virus among pig-farmers in Malaysia

BACKGROUND

Between February and April, 1999, an outbreak of viral encephalitis occurred among pig-farmers in Malaysia. We report findings for the first three patients who died.

METHODS

Samples of tissue were taken at necropsy. Blood and cerebrospinal-fluid (CSF) samples taken before death were cultured for viruses, and tested for antibodies to viruses.

FINDINGS

The three pig-farmers presented with fever, headache, and altered level of consciousness. Myoclonus was present in two patients. There were signs of brainstem dysfunction with hypertension and tachycardia. Rapid deterioration led to irreversible hypotension and death. A virus causing syncytial formation of vero cells was cultured from the CSF of two patients after 5 days; the virus stained positively with antibodies against Hendra virus by indirect immunofluorescence. IgM capture ELISA showed that all three patients had IgM antibodies in CSF against Hendra viral antigens. Necropsy showed widespread microinfarction in the central nervous system and other organs resulting from vasculitis-induced thrombosis. There was no clinical evidence of pulmonary involvement. Inclusion bodies likely to be of viral origin were noted in neurons near vasculitic blood vessels.

INTERPRETATION

The causative agent was a previously undescribed paramyxovirus related to the Hendra virus. Close contact with infected pigs may be the source of the viral transmission. Clinically and epidemiologically the infection is distinct from infection by the Hendra virus. We propose that this Hendra-like virus was the cause of the outbreak of encephalitis in Malaysia.

Traveling time and traveling length in critical percolation clusters

We study traveling time and traveling length for tracer dispersion in two-dimensional bond percolation, modeling flow by tracer particles driven by a pressure difference between two points separated by Euclidean distance r. We find that the minimal traveling time t(min) scales as t(min) approximately r(1.33), which is different from the scaling of the most probable traveling time, t* approximately r(1.64). We also calculate the length of the path corresponding to the minimal traveling time and find l(min) approximately r(1.13) and that the most probable traveling length scales as l* approximately r(1.21). We present the relevant distribution functions and scaling relations.

Extension of the polyanionic cosalane pharmacophore as a strategy for increasing anti-HIV potency

The anti-HIV agent cosalane inhibits both the binding of gp120 to CD4 as well as an undefined postattachment event prior to reverse transcription. Several cosalane analogues having an extended polyanionic "pharmacophore" were designed based on a hypothetical model of the binding of cosalane to CD4. The analogues were synthesized, and a number of them displayed anti-HIV activity. One of the new analogues was found to possess enhanced potency as an anti-HIV agent relative to cosalane itself. Although the new analogues inhibited both HIV-1 and HIV-2, they were more potent as inhibitors of HIV-1 than HIV-2. Mechanism of action studies indicated that the most potent of the new analogues inhibited fusion of the viral envelope with the cell membrane at lower concentrations than it inhibited attachment, suggesting inhibition of fusion as the primary mechanism of action.

Coefficient scaling

We prove a remarkably simple but powerful recursion relation for the coefficients of iterated polynomials. We also prove that the recursion relation holds for the coefficients of certain functions of the iterated polynomial. Using the recursion relations, we obtain a closed-form expression for the average number of closed-loop self-avoiding walks per site on a family of fractal lattices. We describe numerical results, which exhibit log-periodic oscillations, and find good agreement between these results and the theory developed here, which predicts the existence of the log-periodic oscillations and their amplitudes. Finally, we discuss insights gained into the mathematical origins of critical phenomena.

Inhibitor-resistant TEM beta-lactamases: phenotypic, genetic and biochemical characteristics

Beta-lactamases represent the main mechanism of bacterial resistance to beta-lactam antibiotics. The recent emergence of bacterial strains producing inhibitor-resistant TEM (IRT) enzymes could be related to the frequent use of beta-lactamase inhibitors such as clavulanic acid, sulbactam and tazobactam in hospitals and in general practice. The IRT beta-lactamases differ from the parental enzymes TEM-1 or TEM-2 by one, two or three amino acid substitutions at different locations. This paper reviews the phenotypic, genetic and biochemical characteristics of IRT beta-lactamases in an attempt to shed light on the pressures that have contributed to their emergence.

Characterization and nucleotide sequence of CARB-6, a new carbenicillin-hydrolyzing beta-lactamase from Vibrio cholerae

A clinical strain of Vibrio cholerae non-O1 non-O139 isolated in France produced a new beta-lactamase with a pI of 5.35. The purified enzyme, with a molecular mass of 33,000 Da, was characterized. Its kinetic constants show it to be a carbenicillin-hydrolyzing enzyme comparable to the five previously reported CARB beta-lactamases and to SAR-1, another carbenicillin-hydrolyzing beta-lactamase that has a pI of 4.9 and that is produced by a V. cholerae strain from Tanzania. This beta-lactamase is designated CARB-6, and the gene for CARB-6 could not be transferred to Escherichia coli K-12 by conjugation. The nucleotide sequence of the structural gene was determined by direct sequencing of PCR-generated fragments from plasmid DNA with four pairs of primers covering the whole sequence of the reference CARB-3 gene. The gene encodes a 288-amino-acid protein that shares 94% homology with the CARB-1, CARB-2, and CARB-3 enzymes, 93% homology with the Proteus mirabilis N29 enzyme, and 86.5% homology with the CARB-4 enzyme. The sequence of CARB-6 differs from those of CARB-3, CARB-2, CARB-1, N29, and CARB-4 at 15, 16, 17, 19, and 37 amino acid positions, respectively. All these mutations are located in the C-terminal region of the sequence and at the surface of the molecule, according to the crystal structure of the Staphylococcus aureus PC-1 beta-lactamase.

Fatal enterovirus 71 encephalomyelitis

During an outbreak of hand-foot-mouth disease caused by enterovirus 71 (EV-71) in 1997, 4 children presented with sudden cardiopulmonary collapse and minimal neurologic features. All children received cardiopulmonary resuscitation but died within a few hours of admission. Postmortem studies showed infection by EV-71 with extensive damage to the medulla and pons. We postulate an etiologic link between EV-71 and brainstem encephalomyelitis as the cause of pulmonary edema and death.

Phenotypic study of resistance of beta-lactamase-inhibitor-resistant TEM enzymes which differ by naturally occurring variations and by site-directed substitution at Asp276

At this time an amino acid substitution at position 276 in the TEM-1 enzyme is associated with an additional substitution at position 69 in natural beta-lactamase-inhibitor-resistant (IRT) beta-lactamases. The effect of the Asn276-->Asp substitution on resistance was assessed with the Asn276Asp variant, generated by site-directed mutagenesis. The mutant was resistant to beta-lactamase inhibitors, but the MICs of amoxicillin combined with clavulanic acid or tazobactam were strikingly different for E. coli strains producing the Asn276Asp variant and those producing naturally occurring IRTs with single or double substitutions. The inhibitory effects of clavulanic acid and tazobactam were the same in IRTs with substitutions at position 69 (IRT-5 and IRT-6). The effect of clavulanic acid on the MICs of amoxicillin for the Asn276Asp variant was greater than that of tazobactam. In IRTs with double substitutions, at positions 69 plus 276 (IRT-4, IRT-7, and IRT-8) or 69 plus 275 (IRT-14), tazobactam was a more potent inhibitor than clavulanic acid. The effect of the Asn276-->Asp substitution on the values of the kinetic constants and the concentration required to inhibit by 50% the hydrolysis of benzylpenicillin confirms that this single mutation is responsible for resistance to beta-lactamase inhibitors. Molecular modeling of the Asn276Asp mutant shows that Asp276 can form two salt bonds with Arg244 close to the penicillin-binding cavity. The addition of the Asp276 mutation to that preexisting at position 69 confers a higher selective advantage to bacteria, as shown by the reduction in beta-lactamase inhibitor efficiencies of the double variants. Therefore, the emergence of multiple mutations in TEM beta-lactamases by virtue of the use of beta-lactamase inhibitors increases selection pressure resulting in the convergent evolution of resistant strains.

Response of catecholamines to manual teat stimulation or machine-milking of Lacaune and Friesen dairy ewes

Increased sympathetic activity, including peripheral release of catecholamines, has been hypothesized to inhibit the milk ejection reflex by blocking the release of oxytocin, by blocking the effect of oxytocin at the mammary gland, or both. We attempted to relate differences in milking characteristics of Lacaune and East Friesen ewes to the degree of sympathetic arousal, responses of catecholamines and oxytocin to machine-milking and to manual teat stimulation followed by milking. Peripheral concentrations of epinephrine, 67 +/- 6 pg/ml for Lacaunes and 57 +/- 5 pg/ml for Friesens, were essentially constant. Peripheral concentrations of norepinephrine averaged 682 +/- 68 pg/ml for Lacaunes and 250 +/- 54 pg/ml for Friesens. Elevated norepinephrine concentrations during the pretreatment period were associated with the inhibition of oxytocin responses. When norepinephrine concentrations during the pretreatment period exceeded 300 pg/ml for Friescens, or were rising and exceeded 700 pg/ml at initiation of the experimental period for Lacaunes, oxytocin release was inhibited. Results from this study clearly showed that basal concentrations of norepinephrine vary with breed of ewes and provided the first direct evidence that increased sympathetic activity can result in central inhibition of the milk ejection reflex.

Machine milking of Ostfriesian and Lacaune dairy sheep: udder anatomy, milk ejection and milking characteristics

Mammary cistern anatomy derived from ultrasound measurement, milk ejection in response to exogenous oxytocin and oxytocin release and milking characteristics with and without manual prestimulation in early (months 2-4) and late (months 5-8) lactation were investigated in Lacaune and Ostfriesian dairy ewes. Vertical ultrasound cisternal cross sections of the cisternal cavities did not differ in the two breeds, whereas the cisternal area fraction located lower than the exit into the teat channel was larger in Ostfriesian than in Lacaune sheep. The cisternal area enlarged within 1 min in response to i.v. oxytocin injection, indicating milk ejection. During milking, oxytocin concentrations in Lacaune generally increased dramatically within 0.5 min from the start of prestimulation or milking, whereas only slight or no oxytocin release was detected during milking without prestimulation in Ostfriesian ewes. Prestimulation induced oxytocin release in Ostfriesian sheep within 1-2 min after the start of milking, indicating delayed response to stimulation. Two peaked milk flow curves were observed when oxytocin release and milk ejection occurred only after removal of cisternal milk. This type of milk flow was more frequent in Ostfriesian than in Lacaune ewes and was reduced in both breeds by prestimulation, while the frequency of one peaked milk flow curves increased. During the course of lactation, milk yield, main milk fraction and milk flow rates decreased, while stripping yield was almost unchanged. Although milk yield was similar in both breeds, milk flow was lower and stripping yield was higher in Ostfriesian than in Lacaune ewes. We conclude that milk ejection in ewes occurred in response to elevated oxytocin concentrations. In Ostfriesian ewes reduced and delayed oxytocin response to teat stimulation resulted in milk ejection only during stripping. Therefore, and probably because a larger volume of the cistern was located below the teat exit in the Ostfriesian breed, stripping yield was higher in Ostfriesian than in Lacaune sheep.

Properties of IRT-14 (TEM-45), a newly characterized mutant of TEM-type beta-lactamases

IRT-14 (TEM-45) is a new mutant TEM-type beta-lactamase that was isolated from clinical Escherichia coli P37 and that confers resistance to broad-spectrum penicillins with reduced sensitivity to beta-lactamase inhibitors. The MICs of amoxicillin alone and of amoxicillin combined with 2 micrograms of clavulanic acid or 2 micrograms of tazobactam per ml were 4,096, 2,048, and 1,024 micrograms/ml, respectively. The strain was susceptible to cephalosporins, aztreonam, moxalactam, and imipenem. The enzyme was purified to homogeneity, and values of the kinetic parameters Kcat, Km, and Kcat/Km were determined for different substrates. This enzyme, with a pI of 5.2, was found to have reduced affinity for broad-spectrum penicillins and cephalosporins. The values of 50% inhibitory concentrations of clavulanic acid, sulbactam, tazobactam, and brobactam are correlated with the higher KmS for substrates. The resistance of E. coli P37 to mechanism-based inactivators results from a higher level of production of the TEM-derived enzyme due to the G-to-T substitution at position 162 (G-162-->T) in the promoter region of blaTEM and from the structural modifications resulting from the Met-69-->Leu and Arg-275-->Gln substitutions that characterize IRT-14 beta-lactamase.

Hemophagocytic syndrome associated with Bacteroides fragilis infection in a patient with acute monoblastic leukemia

The HS has been associated with malignant hemopathies. We report here a case of HS related to Bacteroides fragilis during the course of acute monoblastic leukemia. Evolution was fatal despite remission of the leukemia process and response of the infection to appropriate antibiotic therapy.

[Resistance to amoxicillin and amoxicillin-clavulanic acid combination of 231 clinical strains of Escherichia coli, isolated in 1992 at the Cochin Hospital]

Among 231 clinical strains of Escherichia coli tested during may 1992, 89 isolates (38.5%) were resistant to beta-lactams. The resistant strains were principally recovered from urinary and genital specimen from medicine and surgical departments. MICs of beta-lactams were determined alone or combined with clavulanic acid, and beta-lactamases were identified by isoelectric point characterization and by enzymatic inhibition tests. Among the resistant strains, 92.1% were secreting a penicillinase and 6.7% a cephalosporinase. No extended-spectrum beta-lactamase was observed. 85.5% of penicillinases were TEM-1 enzymes, 4.9% SHV-1 beta-lactamase, 1.1% OXA-1 beta-lactamase and 8.5%, 7 strains, were IRT beta-lactamases (formerly called TRI). For 24 clinical E. coli strains, the MICs values were > or = 32 mg/l for amoxicillin plus clavulanic acid. The 7 IRT beta-lactamases showed the highest MICs, 256 to 4096 mg/l. Four of them exhibited a beta-lactamase of pI 5.4 and 3 a beta-lactamase of pI 5.2. The IRT beta-lactamases represent 3% of all the Escherichia coli strains. This frequency is comparable or lower than the values reported by other studies conducted between 1992 and 1994.

Trigeminal sensory neurons require extrinsic signals to switch neurotrophin dependence during the early stages of target field innervation

Sensory neurons of the embryonic mouse trigeminal ganglion are transiently supported by brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3), and NT4/5 during the earliest stages of target field innervation before they become dependent on nerve growth factor (NGF) for survival. To determine whether the switch from BDNF/NT3/NT4/5 dependence to NGF dependence occurs autonomously in these neurons or whether extrinsic signals are required, we studied the survival of trigeminal neurons in vitro before, during, and after the switchover period. Trigeminal neurons cultured before they show any response to NGF survived with BDNF, NT3, or NT4/5 well beyond the switchover period. When these early neurons were switched from BDNF, NT3, or NT4/5 to NGF after various times in culture they died as rapidly as neuro-trophin-deprived neurons. Neurons that were switched from BDNF, NT3, or NT4/5 to NGF in cultures set up at stages throughout the switchover period exhibited an NGF survival response that improved with age. Moreover, the ability of NGF to promote long-term survival also increased with embryonic age. These results show that, unlike the onset of BDNF dependence, which is controlled by an intrinsic timing mechanism in early sensory neurons, the switch to NGF dependence relies on extrinsic signals acting on the neurons during the switchover period and that in vivo signals are also required for the maturation of the NGF survival response from a transient to a long-term response. Retinoic acid, which induces NGF dependence in early sympathetic neurons, was ineffective in promoting NGF dependence in early sensory neurons.

Tuberous sclerosis : A three-generation pedigree

This is a report of tuberous sclerosis in members of three generations originating from parents, both suffering from the disease. Out of 12 family members only two were exempted and clinical expression varied from minimum lesion like adenoma sebaceum only to severe mental retardation and epilepsy.

Assessment of dysplasia, mucosal mucins, p53 protein expression, and DNA content in ulcerative colitis patients with colectomy and ileorectal anastomosis

BACKGROUND

Patients with ileorectal anastomosis after colectomy for ulcerative colitis remain at risk of developing rectal malignancy. Detection of mucosal dysplasia has been used for regular screening but is difficult in inflammatory mucosa, prompting the search for complementary markers.

METHODS

This prospective study aimed to assess the prevalence of dysplasia, the predominance of sialomucin, DNA aneuploidy, and p53 overexpression as possible predictors of colorectal tumourigenesis, in the rectal mucosa of an unselected group of 27 patients with ileorectal anastomosis performed for ulcerative colitis. Patients had neither neoplastic nor dysplastic lesions on the colectomy specimen and the retained rectum at the time of surgery. One biopsy specimen of each lateral rectal wall was studied, using routine histology, mucin histochemistry, DNA flow cytometry, and the streptavidin-biotin complex method with D07 monoclonal antibodies directed towards the p53 protein.

RESULTS

Seventeen, seven, and three patients showed inflammatory lesions of inactive, moderate, and severe active colitis, respectively. Dysplasia, sialomucin predominance, DNA aneuploidy, and p53 overexpression were not detected.

CONCLUSIONS

The risk of malignant transformation of the rectal mucosa after ileorectal anastomosis seemed to be low in this ulcerative colitis group without high-grade dysplasia or carcinoma in the previous colectomy specimen, carefully followed up endoscopically and histologically. It remains to be evaluated which of the methods studied above will optimize the histopathologic surveillance of the rectal mucosa of ulcerative colitis patients with ileorectal anastomosis.

Molecular characterization of two strains of the avian adeno-associated virus (AAAV)

An avian adeno-associated virus (AAAV) was isolated after propagating a field isolate of the CELO virus (fowl adenovirus serotype 1 (FAV1)) in embryonated eggs. The isolated dependovirus was compared with the known AAAV obtained from the American Type Culture Collection (ATCC VR-865). The genomes were analysed by digestion with several restriction endonucleases. Although both DNAs have the same size, most restriction enzymes produced different restriction patterns. Double digests were used to construct for the first time restriction maps for avian dependoviruses. The two DNAs rendered different restriction maps in which the different restriction sites were mainly located in the middle and right part of the genomes. The effect of these differences on the structure proteins was shown by western blot analysis. In the immunoblot, the immunofluorescence and immunodiffusion test the two dependoviruses were serologically indistinguishable and therefore can be regarded as two different strains of the same virus. To differentiate between both strains we named the original one as AAAV VR-865 compared with the isolated AAAV DA-1.

Individualisation of two new genomic groups among American Borrelia burgdorferi sensu lato strains

We developed a quick typing method for Borrelia burgdorferi sensu lato strains using a fla gene-based PCR assay, followed by dot blot hybridization with non-radioactive species-specific probes. Thirty-six out of 46 strains belonged to one of the four described species (B. burgdorferi sensu stricto n = 11, B. garinii n = 11, B. afzelii n = 9 and B. japonica n = 5) and hybridized with its own species-specific probe. Among the 10 remaining American strains, two new additional genomic groups were identified. This finding was confirmed by direct sequencing of the fla gene-derived amplicons and whole DNA hybridization.

Characterization and amino acid sequence of IRT-4, a novel TEM-type enzyme with a decreased susceptibility to beta-lactamase inhibitors

The clinical isolate Escherichia coli PEY was highly resistant to amoxycillin, ticarcillin and piperacillin associated to beta-lactamase inhibitors such as clavulanic acid, sulbactam, tazobactam and brobactam but susceptible to cephalosporins, aztreonam and imipenem. The susceptibility to mecillinam indicated that this phenotype was not related to hyperproduction of the TEM-1 beta-lactamase. E. coli PEY produced a new plasmid-mediated inhibitor-resistant beta-lactamase of pI 5.2, which was named IRT-4. The determination of the amino acid sequence (Swiss-Prot accession number, P00810) of the purified protein indicated that IRT-4 differed from TEM-1 by two substitutions: Leu for Met-69 (ABL numbering) and Asp for Asn-276. A Met-69-Leu variant of TEM-1, obtained by site-directed mutagenesis, has been described as resistant to clavulanate. The Asp for Asn-276 substitution has not been reported previously. The side chains of Asp-276 and Arg-244 were expected to interact. Determinations of 50% inhibitory concentrations of beta-lactamase inhibitors and substrate profile of IRT-4 suggested that such an ionic bond was implicated in the alteration of the mechanistic process of TEM-1 beta-lactamase.

Nucleotide sequences of the genes coding for the TEM-like beta-lactamases IRT-1 and IRT-2 (formerly called TRI-1 and TRI-2)

Two blaTEM-like genes were characterized that encoded IRT beta-lactamases (previously called TRI) in clinical isolates of Escherichia coli resistant to amoxycillin alone and to combinations of amoxycillin with beta-lactamase inhibitors. Plasmids carrying this resistance were isolated from E. coli K 12 transconjugants and the genes were sequenced after amplification of defined fragments, using TEM-1-specific primers. The gene for IRT-1 beta-lactamase resembled the blaTEM-1B gene, and that for IRT-2 resembled blaTEM-2. However, both IRT enzymes have a glutamine residue at position 37, which is characteristic of TEM-1. The unique nucleotide difference with parental genes corresponding to amino acid variation was observed at nucleotide position 929. The consequence of C to T transition in the blaIRT-1 gene and C to A transversion in the blaIRT-2 gene was the substitution of arginine 241 in the native protein by cysteine and serine, respectively, in the mutants. Thus, the nature of amino acid 241 is critical in conferring resistance or susceptibility to beta-lactamase inhibitors. Furthermore, these basic to neutral amino acid replacements explain the more acidic pI (pI = 5.2) of these IRT enzymes compared to that of TEM-1 (pI = 5.4). The presence of cysteine-241 in IRT-1 also explains the selective sensitivity of this beta-lactamase to inhibition by p-chloromercuribenzoate.

Val-237 for Ala substitution in the TEM-2 beta-lactamase dramatically alters the catalytic efficiencies towards carbenicillin and ticarcillin

The mutant 554 of TEM-2 beta-lactamase was selected for a decrease in the resistance to carbenicillin of an Escherichia coli K12 carrier. The amino acid sequence of the mutant beta-lactamase was determined by manual Edman degradation analysis of proteolytic peptides. A single substitution Val for Ala was localized at position 237. The mutant exhibited only 2% of the catalytic efficiency of the wild-type enzyme towards carbenicillin and ticarcillin, whereas it retained 30-60% of the hydrolytic activity towards other penicillin and cephalosporin substrates. Carfecillin, the phenyl ester of the side-chain carboxyl group of carbenicillin, was hydrolysed as a good substrate. This suggests that the behaviour of the mutant enzyme towards carbenicillin may result from ionic rather than steric constraints. A molecular model of the Val-237 TEM-2 mutant suggests possible electrostatic interaction between Glu-171 and the carboxylic group of the side chain of carbenicillin.