Epidemiological study of pap genes among diarrheagenic or septicemic Escherichia coli strains producing CS31A and F17 adhesins and characterization of Pap(31A) fimbriae

The association of the pap operon with the CS31A and F17 adhesins was studied with 255 Escherichia coli strains isolated from calves, lambs, or humans with diarrhea. The three classes of PapG adhesin with different receptor binding preferences were also screened. The pap operon was associated with 50 and 36% of human strains that produced CS31A and ovine strains that produced F17, respectively. Among the bovine isolates, the pap operon was detected in 61% of the CS31A-positive isolates and 72% of the strains that produce both CS31A and F17. The class II adhesin gene was present in bovine (20%) and ovine (71%) isolates. Both class II and III adhesins were genetically associated with 36% of the human strains. The highest prevalence of the pap operon was observed among E. coli strains that produce additional adhesins involved in the binding of bacteria to intestinal cells. Among the bovine isolates, the reference strain for CS31A and F17c was found to be positive for the pap operon. Phenotypic and genotypic characterizations were undertaken. Pap(31A) appeared as fine and flexible fimbriae surrounding the bacteria but did not mediate adhesion to calf intestinal villi. Pap(31A) production was optimal with bacteria cultured on minimal growth media and repressed by addition of exogenous leucine. The deduced amino acid sequence of the PapA(31A) structural subunit showed 57 to 97% identity with the different P-related structural subunits produced by E. coli strains isolated from pigs with septicemia or humans with urinary tract infections. None of the three papG allelic variants was detected, but a homologous papG gene was present in the chromosome of strain 31A.

Toxic factors of Vibrio strains pathogenic to shrimp

Vibriosis is a major disease problem in shrimp aquaculture. 'Syndrome 93' is a seasonal juvenile vibriosis caused by Vibrio penaeicida which affects Litopenaeus stylirostris in grow-out ponds in New Caledonia. This study assessed the toxic activities of extracellular products (ECPs) from V. penaeicida, V. alginolyticus and V. nigripulchritudo using in vivo injections in healthy juvenile L. stylirostris (= Penaeus stylirostris) and in vitro assays on shrimp primary cell cultures and the fish cell line epithelioma papulosum cyprini (EPC). Toxic effects of ECPs were demonstrated for all pathogenic Vibrio strains tested both in vivo and in vitro, but for shrimp only; no effect was observed on the fish cell line. ECP toxicity for New Caledonian V. penaeicida was found only after cultivation at low temperature (20 degrees C) and not at higher temperature (30 degrees C). This points to the fact that 'Syndrome 93' episodes are triggered by temperature drops. The assays used here demonstrate the usefulness of primary shrimp cell cultures to study virulence mechanisms of shrimp pathogenic bacteria.

[Glycopeptides]

OBJECTIVES

To review pharmacology, pharmacokinetic and therapeutic use of glycopeptides in intensive care units.

DATA SOURCES

Extraction from Medline database of French and English articles on glycopeptides and search along with major review articles.

DATA SELECTION

The collected articles were reviewed and selected according to their quality and originality. The more recent data were selected.

DATA SYNTHESIS

Glycopeptides are bactericidal antibiotics which are only active against Gram positive species acting by inhibiting peptidoglycan synthesis. They had been in clinical use for almost 30 years without high-level resistance underlining. For ten years, there have been disturbing reports of first, resistance to vancomycin in enterococcal species and more recently in strains of Staphylococcus aureus by complex and large mechanisms of action. This new resistances may lead to a therapeutic impasse and a fatal issue for infected patients. The only response to this situation is the respect of prescription rules and the careful use of antibiotics.

CONCLUSION

Considering their spectrum, glycopeptides are an antibiotic family which importance is fundamental to treat infected patients of intensive care units. Staff members of intensive care units are responsible for their good use.

[How to read a scientific paper. Committee for Clinical References of the French Anesthesia and Resuscitation Society]

Every scientific article has to undergo a critical reading before its conclusions can be accepted. This article discusses the tools for assessing the scientific value of a study. A sequence of methodological criteria allows quality evaluation of an article and its classification in a scale of level of proof.

[Evaluating the quality of life of 42 heart transplant patients and candidates: a cross-sectional study]

OBJECTIVE

Although evaluation of heart transplant candidates and recipients is usually based on objective clinical variables, self-assessment has been proved to be an important component of treatment evaluation. Quality of life is a multidimensional concept, a mix of objective and subjective measures, that could reflect the adjustment to the illness and its treatment. Few studies have reported on quality of life in heart transplantation candidates. This exploratory study, conducted in Bordeaux (France), was designed to assess both objectively and subjectively the quality of life in heart transplant candidates and recipients and to determine the relationships between subjective and objective variables.

METHOD

The assessment was cross-sectional; 21 candidates evaluated at an average of 10 (Sd 21.4) months into the waiting period, were matched with 21 recipients at 29.5 months post operative. Subjective evaluation of the quality of life was self-assessed by the Tableau d'évaluation assistée de la qualité de la vie (TEAQV) and the Nottingham Health Profile (NHP). A semi structured psychiatric interview, and the NYHA (New York Heart Association) cardiac insufficiency score provided objective measurements.

RESULTS

The NHP and TEAQV mean scores were not not significantly different between the two groups: candidates (C) and recipients (R) reported similar subjective data regarding positive quality of life experience. The objective data indicated significant disadvantages for the candidate group: the cardiac insufficiency score was worse in the candidates [(NYHA mean score: (C) = 2.7 Sd 0.56 vs (R) = 0.7 Sd 0.8, t de Student p < 0.01)] and the DSM III-R axis 1 diagnoses were more frequent in the candidates [(C) = 16/21 vs (R) = 9/21 Chi2 p < 0.05)]. There was a prevalence of adjustment disorders in the candidates. Significant correlations were found between NYHA and NHP mean scores (r = 0.6, p < 0.01) and NYHA and physical and psychological dimensions of the TEAQV (r = -0.65 and r = -0.55, p < 0.01) in the recipient group. In the candidate group, no correlation was found between these scores.

CONCLUSION

In the recipient group, objective and subjective assessment showed greater concordance than in the candidate group. Despite more objective physical and moderate yet frequent psychiatric complications, the candidate group reported as positively as did the recipients upon the quality of their life experience. This could be the result of psychological adaptation to the stressful situation. These data were in accordance to several earlier reports. However, the literature has remained controversial upon the evaluation of the quality of life of the candidates. The results of this study, limited by some methodological bias (the small number of patients assessed), need to be confirmed in a prospective study.

Parasitology and immunology of mice vaccinated with irradiated Litomosoides sigmodontis larvae

This study was performed with Litomosoides sigmodontis, the only filarial species which can develop from the infective larvae to the patent phase in immunocompetent laboratory BALB/c mice. Parasitological features and immune responses were analysed up to 3 months before and after challenge inoculation, by comparing 4 groups of mice: vaccinated challenged, challenged only, vaccinated only, and naive mice. Male larvae were very susceptible to irradiation and only female irradiated larvae survived in vivo. Protection, assessed by a lower recovery rate, was confirmed and was established within the first 2 days of challenge. This early reduction of the recovery rate in vaccinated challenged mice was determined by their immune status prior to the challenge inoculation. This was characterized by high specific IgM and IgG subclass (IgG1, IgG2a and IgG3) levels, high specific IL-5 secretion from spleen cells in vitro and a high density of eosinophils in the subcutaneous connective tissue. Six h after the challenge inoculation, most tissue eosinophils were degranulated in vaccinated challenged mice. Thus, in the protocol of vaccination described, protection appeared mainly to result from the stimulation of a Th2 type response and eosinophils seemed to be the main effectors for the increased killing of infective larvae in vaccinated challenged mice. Two months after challenge inoculation, the percentage of microfilaraemic mice was lower in vaccinated challenged mice as a consequence of this overall reduction in the worm load. In both vaccinated challenged and challenged only groups, the in vitro splenocyte proliferative capacity was reduced in microfilaraemic mice.

Functional MR imaging using a visually guided saccade paradigm for comparing activation patterns in patients with probable Alzheimer's disease and in cognitively able elderly volunteers

BACKGROUND AND PURPOSE

Alzheimer's disease is associated with progressive visuospatial dysfunction. This study used functional MR (fMR) imaging with an eye movement paradigm to investigate differences in visuospatial cognition between patients with probable Alzheimer's disease (pAD) and cognitively able elderly volunteers.

METHODS

Using established, although imperfect, clinical criteria, patients with pAD (n = 18) and cognitively able elderly volunteers (n = 10) were selected for study. All patients underwent echo-planar fMR imaging at 1.5 T. The visually guided saccade paradigm consisted of alternating periods (30 s) of central fixation and visually guided saccades to a target appearing randomly along the horizontal meridian. Activation maps were derived using a voxelwise t test, comparing the signal intensities between the two steady-state conditions. The activation patterns were characterized by Talairach coordinates, activation volumes, and laterality ratios (LRs).

RESULTS

Statistically significant differences existed between the activation patterns of the patients with pAD and those of the volunteers. In contrast to the control group, a left-dominant parietal activation pattern and enhanced prefrontal cortical activation were observed in most patients with pAD.

CONCLUSION

Within the limitations of the imperfect clinical standard of reference, the reduction in right parietal activation producing the left-dominant LR for the intraparietal sulcus may reflect the progressive dysfunction in spatial attention associated with Alzheimer's disease, considering the known parietal lobe involvement in this function and the disease. The high specificity of a positive intraparietal sulcal LR measured by fMR imaging may have a role in detecting and monitoring Alzheimer's disease.

Changing heat and moisture exchangers after 96 hours rather than after 24 hours: a clinical and microbiological evaluation

OBJECTIVE

The aim of this study was to determine whether changing heat and moisture exchangers (HMEs) every 96 hrs rather than 24 hrs would affect their efficacy to preserve the heat and moisture of inspiratory gases. The impact of a prolonged use of the HME on its microbial colonization was also assessed.

DESIGN

Prospective cohort observational study.

SETTING

Intensive care unit of a university hospital.

PATIENTS

Thirteen consecutive patients with no previous history of respiratory disease requiring controlled mechanical ventilation with an HME for >4 days were evaluated.

INTERVENTIONS

The same HME was used for 96 hrs in each patient.

MEASUREMENTS AND MAIN RESULTS

In each patient, during the inspiration phase, the following measurements were performed: peak and mean airway pressures, mean values of temperature, and relative and absolute humidity of inspired gases. In each patient, measurements were performed after 1 hr of HME use and then daily up to the fourth day. On days 1 and 4, microbiological samples were obtained from the patients' bronchial secretions and the ventilator side of the HME. After 96 hrs of ventilation with the same HME, tracheal tube occlusion was never observed. Using the same HME for 96 hrs rather than 24 hrs did not affect its technical performances: temperature at 24 hrs: 32.2 +/- 1.5 degrees C (90.0 +/- 34.7 degrees F), at 96 hrs: 32.1 +/- 1.6 degrees C (89.8 +/- 34.9 degrees F); relative humidity at 24 hrs: 97.9 +/- 2%, at 96 hrs: 98.1 +/- 1.7%; absolute humidity at 24 hrs: 33.1 +/- 2.4 mg H2O/L, at 96 hrs: 33.0 +/- 2.5 mg H2O/L. This analysis was based on a total of 312 measurements performed on the 13 patients. Peak and mean airway pressures did not change during the 96-hr study period, with identical tidal and minute volumes in the study patients. On day 1, ten patients had a positive culture of their tracheal secretions at a colony count of > or = 10(3) colony forming units/mL. After 96 hrs of use with the same HME, only seven patients had a positive culture of their tracheal secretions. Cultures from the ventilator sides of the HMEs were all sterile (13/13) after 96 hrs of use.

CONCLUSIONS

In patients free from previous chronic respiratory disorder and ventilated for neurologic reasons, changing the HME after 96 hrs rather than 24 hrs did not affect its technical performance in terms of heat and water preservation of ventilatory gases. There is also some indirect evidence of very little, if any, changes in the HME resistance. No bacterial colonization of the ventilator sides of the HMEs was observed after 96 hrs of use. However, other large clinical trials should be undertaken to confirm the safety of extending the time between HME changes.

Localisation of HHV-8 in AIDS related lymphadenopathy

BACKGROUND

Many lymph node abnormalities have been described in AIDS. These include opportunistic infections that sometimes result in spindle cell pseudotumours, Kaposi's sarcoma (KS), malignant lymphoma (Hodgkin's and non-Hodgkin's), and florid reactive hyperplasia. Among these, reactive hyperplasia is the most common manifestation of AIDS related lymphadenopathy.

AIM

To examine whether human herpesvirus 8 (HHV-8), the aetiological agent of KS, can be localised in AIDS related lymphadenopathy and whether its appearance in such nodes is predictive of Kaposi's sarcoma development.

METHODS

A series of human immunodeficiency virus (HIV) positive men (n = 21) with AIDS related lymphadenopathy who at the time of presentation had KS or subsequently developed KS (n = 5) were examined. The prevalence of HHV-8 was assessed in these patients using solution phase polymerase chain reaction (PCR), real time TaqMan quantitative PCR, and in cell amplification techniques (PCR in situ hybridisation (PCR-ISH) and labelled primer driven in cell amplification).

RESULTS

Using standard solution phase PCR in a nested format, only two of the 21 patients with AIDS related lymphadenopathy were positive for HHV-8. The lymph node of one of these patients contained KS lesions. Three HHV-8 positive patients were identified using TaqMan PCR (the original two positive patients and one additional patient). All of the positive patients either subsequently developed KS (n = 2) or had KS at the time of diagnosis (n = 1). Two additional patients subsequently developed KS, but were negative for HHV-8 by solution phase PCR and TaqMan PCR. Using PCR-ISH, HHV-8 amplicons were identified in some lymphoid cells (in one patient) and in spindle cells of the KS lesion in another. The positive lymphoid cells were predominantly concentrated in B cell areas of the affected lymph nodes, confirming the B cell tropism exhibited by HHV-8.

CONCLUSIONS

The presence of HHV-8 in AIDS related lymphadenopathy is predictive of KS development and probably represents seeding of HHV-8 infected B cells from the peripheral blood. These findings support a role for HHV-8 in the pathobiology of KS.

Prevalence of vancomycin-resistant enterococci in fecal samples from hospitalized patients and nonhospitalized controls in a cattle-rearing area of France

Vancomycin-resistant enterococci (VRE) have emerged as nosocomial pathogens over the last decade, but little is known about their epidemiology. We report on the prevalence of VRE fecal colonization on the basis of a prospective study among patients hospitalized in a hematology intensive care unit and among nonhospitalized subjects living in the local community. A total of 243 rectal swabs from hematology patients and 169 stool samples from the control group were inoculated onto bile-esculin agar plates with and without 6 mg of vancomycin per liter and into an enrichment bile-esculin broth supplemented with 4 mg of vancomycin per liter. A total of 37% of the hospitalized patients and 11.8% of the subjects from the community were found to be VRE carriers. A total of 65 VRE strains were isolated: 12 (18.5%) E. faecium, 46 (70.7%) E. gallinarum, and 7 (10.8%) E. casseliflavus strains. No E. faecalis strains were detected. All the E. faecium strains were of the vanA genotype. Molecular typing by pulsed-field gel electrophoresis revealed a different pattern for each vanA VRE strain that originated from an individual subject. To our knowledge, this is the first study to be carried out in a cattle-rearing region of France. It reports a higher VRE prevalence than that reported in previous European or U.S. studies. A partial explanation is the use of an enrichment broth step which enabled detection of strains which would otherwise have been missed, but the fact that subjects and patients were recruited from a predominantly agricultural area where vancomycin-related antibiotics have recently been used in animal husbandry could also contribute to the high levels of VRE in patients and subjects alike.

Improved in situ detection method for telomeric tandem repeats in metaphase spreads and interphase nuclei

Peptide nucleic acid technology (PNA) has become an extremely useful tool and promises to impact on molecular biology and diagnostics. These synthetic DNA analogues pair with DNA and RNA molecules according to Watson and Crick base pairing rules. This paper describes a sensitive and quick fluorescent in situ hybridisation (ISH) technique to determine DNA telomere repeat sequences (TTA GGG)n using epifluorescence microscopy. Telomeres are special, repeated structures at the end of each eukaryotic chromosome and serve as protective caps to prevent DNA rearrangements and fusion of chromosomes. A model system has been developed, using stimulated peripheral blood lymphocytes, which facilitates simultaneous detection of telomeres in metaphase as well as in interphase nuclei. A fluorescein isothiocyanate labelled PNA probe (18 mer) directed against complementary telomeric sequences at the end of each chromosome is used. In addition, a simple, easy to perform PNA-ISH protocol is described that overcomes common hybridisation problems encountered using DNA and RNA oligoprobes. Furthermore, the usefulness of a chromogenic immunocytochemical detection system is shown for PNA-ISH.

[Catheter-related nosocomial urinary infections in intensive care: physiopathology, epidemiology and prevention]

OBJECTIVES

Nosocomial urinary tract infections associated with bladders catheters are common and poorly understood. Data on the prevention of urinary tract infections are numerous and heterogenous. This update article aimed at analysing mechanisms, epidemiology and prevention of these infections.

DATA SOURCES

We searched in the Medline database for articles in English or French, without limiting date of publication, using the following key words separely or in combination: urinary tract infection, nosocomial, catheter, infection urinaire, sonde urinaire.

STUDY SELECTION

We considered all categories of articles.

DATA EXTRACTION

Data on prevention of nosocomial urinary tract infections were analysed in depth.

DATA SYNTHESIS

The data on pathogenesis of nosocomial urinary tract infections are still controversial. Various means for preventing urinary tract infections have been recommended: addition of antibacterial agents to urinary drainage system, inclusion of antimicrobial components into the catheter itself, antibiotic prophylaxis or closed sterile drainage system. Their efficiency in intensive therapy unit has not yet been fully assessed. The therapy of these infections is still under debate and requires additional prospective studies to establish the optimal management.

CONCLUSION

Catheter-associated urinary tract infections reflect the general hygiene policy, starting with nurse practice patterns at catheter insertion, and ending with antibio-therapy prescriptions by medical staff.

Using a geographical information system to plan a malaria control programme in South Africa

INTRODUCTION

Sustainable control of malaria in sub-Saharan Africa is jeopardized by dwindling public health resources resulting from competing health priorities that include an overwhelming acquired immunodeficiency syndrome (AIDS) epidemic. In Mpumalanga province, South Africa, rational planning has historically been hampered by a case surveillance system for malaria that only provided estimates of risk at the magisterial district level (a subdivision of a province).

METHODS

To better map control programme activities to their geographical location, the malaria notification system was overhauled and a geographical information system implemented. The introduction of a simplified notification form used only for malaria and a carefully monitored notification system provided the good quality data necessary to support an effective geographical information system.

RESULTS

The geographical information system displays data on malaria cases at a village or town level and has proved valuable in stratifying malaria risk within those magisterial districts at highest risk, Barberton and Nkomazi. The conspicuous west-to-east gradient, in which the risk rises sharply towards the Mozambican border (relative risk = 4.12, 95% confidence interval = 3.88-4.46 when the malaria risk within 5 km of the border was compared with the remaining areas in these two districts), allowed development of a targeted approach to control.

DISCUSSION

The geographical information system for malaria was enormously valuable in enabling malaria risk at town and village level to be shown. Matching malaria control measures to specific strata of endemic malaria has provided the opportunity for more efficient malaria control in Mpumalanga province.

General surgery and fellowship training: opinions of surgical intern applicants and fellowship directors

BACKGROUND

Given the pressures that exist today to modify surgical training programs, this study was undertaken to ascertain the opinions of surgical intern applicants and fellowship program directors with regard to the length of surgical training.

METHODS

Surveys were sent to fourth-year medical students who were applying for categorical surgical training during a 2-year period at a single university medical center and to fellowship program directors in 6 surgical subspecialties.

RESULTS

Ninety-three percent of the applicants planned to pursue fellowship training. Sixty-eight percent of the applicants did not feel that 5 years of general surgery are necessary before beginning a fellowship. Seventy-one percent of the applicants indicated that they would be willing to "short track" into a subspecialty to reduce training time. Virtually all fellowship directors in pediatric surgery (94%), transplantation surgery (94%), and oncologic surgery (100%) felt that 5 years of general surgery training are necessary before entering a fellowship. Significantly fewer fellowship directors in vascular surgery (53%), cardiothoracic surgery (30%), and plastic surgery (17%) felt that 5 years of general surgery are essential before beginning a fellowship (P < or = .001).

CONCLUSIONS

For some general surgery subspecialties, a shortened, integrated training program may be desirable from the point of view of both trainees and fellowship directors. Vascular, cardiothoracic, and plastic surgery appear to be those subspecialties that are most amenable to such programs.

Ifosfamide in non-small-cell lung cancer

Ifosfamide has been used in combination with several drugs including cisplatin, giving rise to multiple doublets and triplets including the ifosfamide-cisplatin-mitomycin regimen (Cullen's MIC regimen) that has been commonly used in Europe. However, new combinations are challenging the activity of the old chemotherapy regimens, especially in terms of objective response rate and time to progressive disease, as has been shown in several phase III randomized trials. Among these new combinations, ifosfamide-vinorelbine and ifosfamide-gemcitabine-cisplatin are especially promising. In this paper, several ifosfamide doublets and triplets are reviewed.

Different ventilation strategies affect lung function but do not increase tumor necrosis factor-alpha and prostacyclin production in lavaged rat lungs in vivo

BACKGROUND

Using an in vivo animal model of surfactant deficiency, the authors compared the effect of different ventilation strategies on oxygenation and inflammatory mediator release from the lung parenchyma.

METHODS

In adult rats that were mechanically ventilated with 100% oxygen, acute lung injury was induced by repeated lung lavage to obtain an arterial oxygen partial pressure < 85 mmHg (peak pressure/positive end-expiratory pressure [PEEP] = 26/6 cm H2O). Animals were then randomly assigned to receive either exogenous surfactant therapy, partial liquid ventilation, ventilation with high PEEP (16 cm H2O), ventilation with low PEEP (8 cm H2O), or ventilation with an increase in peak inspiratory pressure (to 32 cm H2O; PEEP = 6 cm H2O). Two groups of healthy nonlavaged rats were ventilated at a peak pressure/PEEP of 32/6 and 32/0 cm H2O, respectively. Blood gases were measured. Prostacyclin (PGI2) and tumor necrosis factor-alpha (TNF-alpha) concentrations in serum and bronchoalveolar lavage fluid (BALF) as well as protein concentration in BALF were determined after 90 and 240 min and compared with mechanically ventilated and spontaneously breathing controls.

RESULTS

Surfactant, partial liquid ventilation, and high PEEP improved oxygenation and reduced BALF protein levels. Ventilation with high PEEP at high mean airway pressure levels increased BALF PGI2 levels, whereas there was no difference in BALF TNF-alpha levels between groups. Serum PGI2 and TNF-alpha levels did not increase as a result of mechanical ventilation when compared with those of spontaneously breathing controls.

CONCLUSIONS

Although alveolar protein concentration and oxygenation markedly differed with different ventilation strategies in this model of acute lung injury, there were no indications of ventilation-induced systemic PGI2 and TNF-alpha release, nor of pulmonary TNF-alpha release. Mechanical ventilation at high mean airway pressure levels increased PGI2 levels in the bronchoalveolar lavage-accessible space.

Upper-extremity deep vein thrombosis after central venous catheterization via the axillary vein

OBJECTIVE

To determine the frequency of central venous catheter-induced thrombosis of the axillary vein.

DESIGN

Prospective, controlled study.

SETTING

Tertiary care university center.

PATIENTS

Sixty patients in a medical-surgical intensive care unit who required central venous catheterization via the axillary vein.

INTERVENTIONS

Single-lumen, silicone elastomer or polyurethane catheters were inserted for a mean duration of 14.7+/-7.4 days (range, 4-33 days). On catheter removal, bilateral upper-extremity phlebographic examination was performed in each patient. The incidence of deep vein thrombosis in catheterized arms was compared with that in uncatheterized arms.

MEASUREMENTS AND MAIN RESULTS

Of the 60 patients who underwent axillary vein cannulation, one patient had clinical signs of arm vein thrombosis, but no patient had clinical sign of pulmonary embolism. There were 35 patients (58.3%) who developed positive phlebographic examinations homolateral to the catheter. Fibrin sleeves that developed around the catheters were observed in 28 patients (47%). Five patients (8.3%) had phlebographic signs of partial axillary vein thrombosis: nonobstructive clots adherent to the vessel wall and/or the catheter. Two patients (3.3%) had phlebographic signs of complete axillary vein thrombosis. No thrombosis was observed in patients with catheterizations lasting < or =6 days, two cases were observed for duration of 7-14 days, and five cases were observed for duration of > or =15 days (p < .01). In the seven patients with axillary vein thrombosis, the vessel was cannulated with fewer than three puncture attempts, and the mean duration for catheter insertion (10+/-2.5 min) was not different from that of patients with no axillary vein thrombosis (14+/-9 min).

CONCLUSIONS

Based on the data from the present study, we conclude that axillary vein catheterization is associated with a 11.6% frequency of upper-extremity deep vein thrombosis. This rate of vein thrombosis is similar to that observed after internal jugular or subclavian vein cannulation. Given the acceptable rate of this clinically important complication, axillary vein cannulation offers an attractive alternative site for catheter insertion to the internal jugular or subclavian vein in the critically ill. Because thrombosis is rare or absent in catheterizations lasting <15 days, it seems wise to withdraw axillary catheters after a maximum of 2 wks.

Specificity of starch synthase isoforms from potato

In higher plants several isoforms of starch synthase contribute to the extension of glucan chains in the synthesis of starch. Different isoforms are responsible for the synthesis of essentially linear amylose chains and branched, amylopectin chains. The activity of granule-bound starch synthase I from potato has been compared with that of starch synthase II from potato following expression of both isoforms in Escherichia coli. Significant differences in their activities are apparent which may be important in determining their specificities in vivo. These differences include affinities for ADPglucose and glucan substrates, activation by amylopectin, response to citrate, thermosensitivity and the processivity of glucan chain extension. To define regions of the isoforms determining these characteristic traits, chimeric proteins have been produced by expression in E. coli. These experiments reveal that the C-terminal region of granule-bound starch synthase I confers most of the specific properties of this isoform, except its processive elongation of glucan chains. This region of granule-bound starch synthase I is distinct from the C-terminal region of other starch synthases. The specific properties it confers may be important in defining the specificity of granule-bound starch synthase I in producing amylose in vivo.

Changing a hydrophobic heat and moisture exchanger after 48 hours rather than 24 hours: a clinical and microbiological evaluation

OBJECTIVE

Complications following ventilation with dry and cold gases may be prevented by the use of artificial noses or heat and moisture exchangers, which are a solution to both the problems of humidification and heat preservation. The aim of the present study was to determine whether changing hydrophobic heat and moisture exchangers (HMEs) every 48 h rather than 24 h would affect their efficacy to preserve the heat and moisture of inspiratory gases. The impact of a prolonged use of the HME on its microbial colonization was also assessed.

DESIGN

Prospective observational study.

SETTING

ICU of a university hospital.

PATIENTS

Twelve patients requiring controlled mechanical ventilation for more than 2 days were evaluated.

INTERVENTIONS

The patients were ventilated with a heat and moisture exchanger (HME) (Maxipleat Filter, Europe Medical, France). The hydrophobic HME was placed between the Y-piece and the connecting tube and changed after 48 h of continuous use. Temperature (degree C), relative humidity (%) and absolute humidity (mgH2O/l) were obtained using the capacitive sensor principle. Bacterial colonization (tracheal secretions and ventilator side of the HME) were obtained on days 1 and 2.

MEASUREMENTS AND RESULTS

After 48 h of ventilation with the same HME, tracheal tube occlusion was never observed. Using the same hydrophobic HME for 48 h rather than 24 h did not affect its technical performance: temperature at 24 h: 32.5 +/- 1.3 degrees C, at 48 h: 32.7 +/- 1.8 degrees C; relative humidity (RH) at 24 h: 99.0 +/- 1.4%, at 48 h: 99.0 +/- 1.4%; absolute humidity (AH) at 24 h: 34.0 +/- 2.4 mgH2O/l, at 48 h: 34.4 +/- 3.5 mgH2O/l. Peak and mean airway pressures did not change over the 48-h study period, with identical tidal and minute volumes in the study patients. Total respiratory heat losses were not modified during the 48-h study period (at 24 h: 152 +/- 47 cal/min, at 48 h: 149 +/- 65 cal/min). Evaporative and convective heat losses were not modified either. On day 1, eight patients had positive cultures of their tracheal secretions at a colony count of 10(3) or higher cfu/ml. After 48 h of use of the same HME, only six patients had a positive culture of their tracheal secretions. Cultures from the ventilator sides of the HMEs were all sterile (12/12) after 48 h of use.

CONCLUSIONS

Changing the hydrophobic HME after 48 h rather than 24 h did not affect its technical performance in terms of heat and water preservation of ventilatory gases. There is also some indirect evidence of very little, if any, change in HME resistance. No bacterial colonization of the ventilator sides of the HMEs was observed after 48 h of use. However, other large clinical trials should be undertaken to confirm the safety of extending the time between HME changes.

Multifunctionality and diversity within the plant MYB-gene family

MYB proteins constitute a diverse class of DNA-binding proteins of particular importance in transcriptional regulation in plants. Members are characterised by having a structurally conserved DNA-binding domain, the MYB domain. Different categories of MYB proteins can be identified depending on the number of imperfect repeats of the MYB domain they contain. It is likely that single MYB-domain proteins, a class of expanding importance in plants, bind DNA in a different way than two-repeat or three-repeat MYB proteins, and these groups are therefore likely to have different functions. The two-repeat (R2R3) MYB family is the largest family characterised in plants, and there are estimated to be over 100 members in Arabidopsis. Functions of MYB proteins in plants include regulation of secondary metabolism, control of cellular morphogenesis and regulation of meristem formation and the cell cycle. Although functional similarities exist between R2R3 MYB proteins that are closely related structurally, there are significant differences in the ways very similar proteins function in different species and also within the same organism. Therefore, despite the large number of R2R3 MYB proteins in plants, it is unlikely that many are precisely redundant in their functions, but more likely that they share overlapping functions.