Stochasticity and bistability in horizontal transfer control of a genomic island in Pseudomonas

Genomic islands (GEI) comprise a recently recognized large family of potentially mobile DNA elements and play an important role in the rapid differentiation and adaptation of bacteria. Most importantly, GEIs have been implicated in the acquisition of virulence factors, antibiotic resistances or toxic compound metabolism. Despite detailed information on coding capacities of GEIs, little is known about the regulatory decisions in individual cells controlling GEI transfer. Here, we show how self-transfer of ICEclc, a GEI in Pseudomonas knackmussii B13 is controlled by a series of stochastic processes, the result of which is that only a few percent of cells in a population will excise ICEclc and launch transfer. Stochastic processes have been implicated before in producing bistable phenotypic transitions, such as sporulation and competence development, but never before in horizontal gene transfer (HGT). Bistability is instigated during stationary phase at the level of expression of an activator protein InrR that lays encoded on ICEclc, and then faithfully propagated to a bistable expression of the IntB13 integrase, the enzyme responsible for excision and integration of the ICEclc. Our results demonstrate how GEI of a very widespread family are likely to control their transfer rates. Furthermore, they help to explain why HGT is typically confined to few members within a population of cells. The finding that, despite apparent stochasticity, HGT rates can be modulated by external environmental conditions provides an explanation as to why selective conditions can promote DNA exchange.     

Induction of immune tolerance with recombinant factor VIII in haemophilia A patients with inhibitors

We report on 11 patients (nine unrelated and a brother pair) with severe haemophilia A and factor VIII (FVIII) inhibitor, in whom immune tolerance (IIT) was induced with recombinant FVIII (r-FVIII). Their age ranged from 11 months to 47 years. The number of exposure days (ED) at inhibitor detection varied from 11 to 130. Nine of the 11 patients were high responders [>10 Bethesda units (BU)] with peak inhibitor levels ranging from 10 to 566 BU. The other two were low responders with peak levels between 0.7 and 2 BU. Before inhibitor detection, the patients had been receiving products of various purities. The IIT regimens were very heterogeneous, and the treatment schedule varied from a short period with 50 IU kg^–1 every 2 days, followed by 100 IU kg^–1 every 2 days and then 220 IU kg^–1 daily. The outcome was considered successful when the inhibitor level fell to 0.6 BU or lower after IIT treatment. The outcome overall was successful in nine out of 11 patients (81.8%), with the nine successful cases comprising seven of the nine high responders (77.8%) and the two low responders. Definite failure of IIT was observed in one high responder after two different IIT regimens. A second high responder is still on IIT treatment. All patients in whom IIT was successful are currently receiving r-FVIII on demand or prophylactically at various dosages. Despite the variability of the patient characteristics and the IIT schedules, this study demonstrates that r-FVIII represents an effective alternative for the eradication of inhibitors through IIT.     

Atheroablation with the Kensey catheter: a pathologic study

The mode of action of the Kensey catheter, a new atheroablation device, was investigated. Fresh above-the-knee amputated legs were used for recanalization of the superficial femoral artery. The variables used were identical to those of clinical trials, including a rotational speed of 50,000 rpm and an injection rate of 40 mL/min. The debris produced by the catheter was studied cytologically, and the arterial segments were examined histologically. The particle size in the debris ranged from 1 to 2,000 microns. The softer plaques produced a fine fibrin dust background with long strips of intima ranging from 10 to 2,000 microns. Complicated calcified plaques produced larger background material (10-120 microns) but smaller strips of intima (50-800 microns). Dissections and perforations occurred. Some of the debris produced by the atheroablation process was used to embolize a canine heart and kidney. Small focal infarctions were found in the heart, and large and multiple infarcts were seen in the kidney. In clinical studies the debris appears to be tolerated in the lower extremities. Its safety in the kidney and heart are questioned.     

Intra-operative antibiotic prophylaxis in neurosurgery. A prospective,randomized, controlled study on cefotiam

Summary In this prospective, randomized and controlled study the effect of cefotiam for the prevention of wound infections following trepanations was investigated. The main interest was centered on the rate of post-operative bone flap infections requiring operative revision. Administration of cefotiam was randomized for patients undergoing major craniotomies. The antibiotic was administered intravenously in a single dose of 2 g with induction of anaesthesia.Only clean or clean contaminated cases were included. Excluded were contaminated cases, operations with a transnasal-transsphenoidal approach, shunt-operations and patients with any other preoperative infection or antibiotic therapy. Outpatients were excluded due to difficulties in obtaining sufficient clinical information.From originally 918 consecutive patients operated on 711 fulfilled the entry criteria. With regard to age, sex, diagnosis and the site of the trepanation, control patients (n=355) and cefotiam treated patients (n=356) were shown to be comparable. In the various subgroups formed for different primary diagnoses, concomitant steroidal therapy and concomitant severe internal medical diseases cefotiam treated patients and controls were comparable as well.A highly significant difference for bone flap infection could be shown with 0.3% in the cefotiam group versus 5.1% in the control group (p<0.001). The overall rate of post-operative deep wound infections including meningitis and abscesses was also significantly (p<0.005) different with 3.1% in the cefotiam versus 9.0% in the control group.Thus it was concluded that a single dose of cefotiam significantly reduces post-operative deep wound infection.     

Plasma MHPG and AMDP depression relations,evolution and drug effect in a follow-up study of depressed patients

Plasma MHPG levels and AMDP rating score were measured in depressed patients before treatment, and a follow-up study was performed during the next 3 months of drug therapy to detect possible relationships between the parameters. Before treatment, MHPG levels were moderately lower in depressed than in age- and sex-matched normal subjects. Bipolar depressed patients presented the lowest values. In the three diagnostic groups (DSM-III), antidepressant treatment resulted in a significant decrease of mean levels in unipolar and dysthymic depressed, but not in bipolar depressed patients. When the type of antidepressant was considered, imipramine (IMI)- or desipramine (DMI)-treated patients, but not fluvoxamine (FLU)-treated, also decreased their mean values of MHPG, with minor difference between improved and non-improved patients. However, when patients were grouped according to their pattern groups (low (LL), high (HL), or normal (NL) baseline MHPG levels), interesting information emerged: improvement of clinical state of patient (i.e. 60 per cent of AMDP baseline reduction) resulted in ‘normalization’ of erratic values (HL and NL) whatever the treatment, while in non-improved patients such evolution was not observed. In the latter group, change in MHPG levels was only drug-related (decrease in IMI–DMI-treated and no change in FLU-treated values). Results suggest that mechanisms of buffering NA activity were lost in endogenous depression and restored in patients responding to treatment.     

Hypocalcaemia in severe meningococcal infections

AIM: To determine the incidence of hypocalcaemia in critically ill children with meningococcal disease. METHODS: In a prospective cohort study, 70 of 80 patients admitted consecutively with a clinical diagnosis of meningococcal disease to intensive care had measurements of total and ionised calcium on admission. Parathormone and calcitonin were measured in a proportion of the children. RESULTS: Total and ionised calcium concentrations were low in 70% of the children. There was a weak relation of calcium concentration to the volume of blood derived colloid which had been given, but a good relation to disease severity, where sicker children had lower calcium concentrations. Although the parathormone concentration was higher in children with lower calcium concentrations, some children had low ionised calcium concentrations, without an increase of parathormone concentration. Serum calcitonin concentration was not related to calcium concentrations. CONCLUSION: Hypocalcaemia is common in meningococcal disease.