Pharmacodynamics of Ceftolozane Combined with Tazobactam against Enterobacteriaceae in a Neutropenic Mouse Thigh Model.

Ceftolozane is a new broad-spectrum cephalosporin and is combined with tazobactam to broaden the activity of ceftolozane against strains producing extended-spectrum beta-lactamases (ESBLs). We determined the pharmacodynamics (PD) of the combination in the neutropenic mouse thigh model to determine the optimal exposure of tazobactam. Treatment of CD-1 neutropenic mice was started 2 h after infection with ceftolozane every 2 h (q2h) alone or in combination with tazobactam at different dosing frequencies for 24 h, and the number of CFU in the thighs was determined before and after treatment. The maximum effect model was fit to the dose-response and the pharmacokinetic/PD index (PDI)-response to determine the PDI values for ceftolozane alone and ceftolozane in combination with tazobactam resulting in a static effect and a 1-log kill. The effect of tazobactam was dependent on the percentage of time that the free drug concentration remained above the concentration threshold (percent [Formula: see text]), whereby dosing q2h was more efficacious than dosing every 8 h (q8h), reducing the tazobactam daily dose by a factor 6.9 to 59.0 (n = 3 strains) to obtain a static effect. Using R2 as an indicator of the best fit of the percent [Formula: see text]-response relationships, the concentration threshold best correlating with the response varied from 0.5 to 2 mg/liter, depending on the strain. A similar result was obtained when the q2h and q8h regimens were analyzed. For all isolates tested, the mean [Formula: see text] for 0.5 mg/liter tazobactam was 28.2% (range, 17.5 to 45.8%) and 44.4% (range, 26.6 to 54.7%) for a static effect and a 1-log kill, respectively, at ceftolozane exposures that produced a ceftolozane concentration of 4 mg/liter (a concentration greater than the MIC) for 33.9 to 63.3% of a 24-h period under steady-state pharmacokinetic conditions. The main PDI that correlated with the effect of tazobactam was the [Formula: see text] achieved with a CT of 0.5 mg/liter tazobactam.

Plasma and epithelial lining fluid pharmacokinetics of ceftolozane and tazobactam alone and in combination in mice.

Ceftolozane is a new cephalosporin with activity against Gram-negative and Gram-positive microorganisms. However, the compound is susceptible to degradation by extended-spectrum beta-lactamases (ESBLs). Tazobactam is an ESBL inhibitor and is combined with ceftolozane to broaden its activity. Surprisingly, although tazobactam has been available for over 20 years, few if any reliable data exist on the tazobactam pharmacokinetic (PK) properties in mice. To evaluate the PK and pharmacodynamic (PD) relationships in mice, the PK properties of tazobactam and ceftolozane were extensively investigated. Thigh-infected neutropenic CD-1 mice were injected intraperitoneally with a single 0.1-ml dose containing ceftolozane, tazobactam, or both compounds. Ceftolozane was applied in 2-fold-increasing doses of 4 mg/kg of body weight to 64 mg/kg alone or in combination. Tazobactam was combined in reverse doses (thus, 64/4 mg/kg, 32/8 mg/kg, etc.) (n = 2 per time point). In separate validation experiments, ceftolozane-tazobactam was given alone or in combination at 32/8 mg/kg and 8/32 mg/kg (n = 4 per time point). Plasma samples (one per mouse) and bronchoalveolar lavage samples were collected at up to 12 time points until 6 h after administration. There were no significant differences in the ceftolozane and tazobactam PK alone versus combined, indicating no PK interaction. The PKs were linear and dose proportional for both compounds and showed a good penetration in the epithelial lining fluid. The estimated mean (standard deviation) half-life of ceftolozane was 0.287 h (0.031 h), and that of tazobactam was 0.176 h (0.026), and the V was 0.43 liter/kg and 1.14 liter/kg, respectively. The estimates of tazobactam parameters can also be used to (re)interpret PD data.

Evaluation of the calibration parameters of radiochromic films for patient dosimetry in interventional radiology.

The study aims to analyse the effects of beam energy, dose fractionation, response homogeneity, long-term fading and response sensitivity of radiochromic films. It also investigates the effect of the scanner, ambient temperature and storage conditions on the response of the films. The radiochromic films were irradiated at various air kerma from 20 mGy to about 8 Gy. Results showed that the response of the films is not energy dependent for low doses ranging from 300 to 700 mGy (coefficient of variation = 5-12%) but starts to show a slight dependence for high doses above 2 Gy (coefficient of variation = 20%). There is no significant difference (4%) in optical densities (OD) and pixel values when doses were fractionated and when using scanner with and without warm-up lamp. The curve fitting of OD and pixel values for the sensitivity test at different kilovolt potential gave an r(2) value of 0.99.

Radiation dose profile in 125I brachytherapy: an 8-year review.

The use of episcleral plaques containing radioactive 125I seeds for brachytherapy treatment of selected retinoblastoma cases of patients is being done in Riyadh, Saudi Arabia since 1994. There are about three to four patients per year. A total of 31 patients were treated with a tumour dose in the range of 40-60 Gy using 8 seeds of 125I each from 1994 to 2002. This study determines the trend of occupational doses received by surgeons, anaesthesiologists and nurses and the dose rate profile around the eyes. Only 3% of the 275 persons monitored for Hp(10) have measurable doses with a weighted average of 4 microSv and 7% of the 175 persons monitored for Hp(0.07) have measurable doses with a weighted average of 0.3 mSv. The dose rate is maximum (110 microSv h(-1)) at the point of contact with the eye plaque and reduces to approximately 40% on the side of the other eye.

Occupational doses during the injection of contrast media in paediatric CT procedures.

The administration of intravenous contrast media by hand or power injection in paediatric computed tomography (CT) procedures is carried out at King Faisal Specialist Hospital and Research Centre for chest, abdomen and torso diagnostic examinations. Some procedures require the CT unit to commence patient scanning during the injection of the last volume of the contrast medium. During the injection, even if the nurse is wearing a 0.5 mm lead equivalent protective apron, the head region and the hand are likely to receive high doses. This study was therefore made to assess the head and extremity doses to the nurses during CT procedures where typical exposure parameters of 200 to 220 mA s and 120 kVp were used. Thermoluminescence dosemeters were deployed for three consecutive months in two CT rooms. A total of 96 procedures were performed during this period and they were included in this study. Scattered radiation measurements were done at different locations where the nurse may be positioned. Results showed that the average dose to the head region and the hands per paediatric case were 50 microSv and 80 microSv respectively. This study investigated the factors that affect the dose and found them to be the length of stay inside the room, type of CT examination. exposure parameters and location of the nurse.

Risk of heparin lock-related bleeding when using indwelling venous catheter in haemodialysis.

BACKGROUND: The indwelling venous catheter such as Dual-Cath or Twin-Cath is widely used in haemodialysis. Although the manufacturer recommends filling the catheter lumen with heparin after the dialysis session to prevent clotting, little is known about the systemic effects of such a procedure. METHODS: Twenty haemodialysis patients with Dual-Cath were studied. Dialysis anticoagulation was achieved by injecting a bolus of dalteparin. The patient/control ratio of activated partial thromboplastin time (aPTT) was determined at the end of the session immediately before and 10 min after locking with 2 ml of undiluted heparin (10,000 U/catheter). We also determined the catheter volume for each patient and measured aPTT immediately before and 10 min after heparin locking with this patient-specific volume. Catheter patency was followed over a 2-week period. RESULTS: The aPTT values determined at the end of two consecutive dialysis sessions were nearly normal, respectively 1.29 (+/-0.17) and 1.33 (+/-0.22), whereas all patients had uncoagulable blood (aPTT >3.75) 10 min after locking with 2 ml of heparin. When catheter volumes were individually calculated, they were found to be substantially lower than 2.0 ml (1.21+/-0.12 for the arterial branch and 1.27+/-0.13 for the venous branch). aPTT was only 2.42+/-0.73 10 min after locking with the estimated volumes except in one patient (aPTT >3.75). No catheter clotting was observed despite these smaller locking volumes. CONCLUSIONS: A risk of inducing serious bleeding does indeed exist with Dual-Cath heparin locking, especially in postoperative patients. This risk can be reduced by measuring catheter length at the time of placement in order to ensure an appropriate lock volume. Sodium citrate, polygeline, or urokinase are possible alternatives to heparin.

Structure of adeno-associated virus vector DNA following transduction of the skeletal muscle.

The skeletal muscle provides a very permissive physiological environment for adeno-associated virus (AAV) type 2-mediated gene transfer. We have studied the early steps leading to the establishment of permanent transgene expression, after injection of recombinant AAV (rAAV) particles in the quadriceps muscle of mice. The animals received an rAAV encoding a secreted protein, murine erythropoietin (mEpo), under the control of the human cytomegalovirus major immediate-early promoter and were sacrificed between 1 and 60 days after injection. The measurement of plasma Epo levels and of hematocrits indicated a progressive increase of transgene expression over the first 2 weeks, followed by a stabilization at maximal plateau values. The rAAV sequences were analyzed by Southern blotting following neutral or alkaline gel electrophoresis of total DNA from injected muscles. While a high number of rAAV sequences were detected during the first 5 days following the injection, only a few percent of these sequences was retained in the animals analyzed after 2 weeks, in which transgene expression was maximal. Double-stranded DNA molecules resulting from de novo second-strand synthesis were detected as early as day 1, indicating that this crucial step of AAV-mediated gene transfer is readily accomplished in the muscle. The templates driving stable gene expression at later time points are low in copy number and structured as high-molecular-weight concatemers or interlocked circles. The presence of the circular form of the rAAV genomes at early time points suggests that the molecular transformations involved in the formation of stable concatemers may involve a rolling-circle type of DNA replication.

Selective uptake and sustained expression of AAV vectors following subcutaneous delivery.

BACKGROUND: Recombinant adeno-associated viral (rAAV) vectors are capable of long-term expression of secreted and intracellular proteins following delivery to muscle, liver, and the central nervous system. In this study, we have evaluated subcutaneous injection of rAAV encoding a variety of transgenes as an alternative route of administration for the systemic delivery of therapeutic proteins. METHODS: rAAV vectors encoding the human factor IX, human interferon-alpha 2a, murine erythropoietin (epo), and Escherichia coli lacZ genes were used for subcutaneous delivery into mature immunocompetent mice. Expression of factor IX and interferon in mouse serum was measured by ELISA. Expression of Epo was monitored by an increase in hemotocrit and by RIA. The tissue tropism of AAV transduction was determined by histochemistry following administration of the lacZ vector. RESULTS: Long-term protein expression (at least one year) is demonstrated in the serum of immunocompetent mice following subcutaneous delivery of AAV vectors encoding the human factor IX and interferon genes. The murine epo gene delivered via this route resulted in levels of Epo that correlate with increased hematocrits of up to 90% for a duration of nine months. rAAV encoding the lacZ gene revealed that the panniculus carnosus, a skeletal muscle layer of the skin, was transduced upon subcutaneous administration. CONCLUSIONS: This study shows that long-term expression of secreted proteins can be achieved using rAAV vectors injected subcutaneously as a single administration. The observation that the panniculus carnosus is the primary tissue transduced by rAAV illustrates the high tropism of rAAV for skeletal muscle.

[Allogeneic bone marrow transplantation in congenital erythropoietic porphyria. Gunther's disease]. / Allogreffe de moelle osseuse dans la porphyrie érythropoiétique congénitale. Maladie de Günther.

INTRODUCTION: The congenital erythropoietic porphyria (Günther's disease) (CEP) is a rare autosomal recessively metabolic disease due to the deficit of uroporphyrinogen III cosynthetase, fourth enzyme of the porphyrin-heme biosynthesis. This disease is characterized by severe cutaneous photosensitivity with profound skin lesions, hemolytic anemia and excess of uroporphyrin I excretion. The vital prognosis is very bad and until now, no treatment seems to be efficient. Bone marrow transplantation seems to be able to correct the enzymatic deficit that causes the disease because it is located in the bone marrow. OBSERVATION: We report the case of a four and a half year old girl who received an allogeneic bone marrow transplantation (BMT) at the age of two. Despite an encouraging result, the first transplantation failed. A second allogeneic transplantation was attempted eight months later with the same HLA identical heterozygous donor and bone marrow engrafment succeeded. Twenty one months after the second bone marrow transplantation, clinical and biological results are still excellent. DISCUSSION: No classical treatment of CEP really proved its efficiency and no one was curative. CEP resulting from an homozygous deficiency in uroporphyrinogen III cosynthetase, enzyme that takes part in the porphyrin-heme biosynthesis which is principally located in the erythropoietic system of the bone marrow, substitution of this defective lineage by BMT was a very attractive treatment to correct this anomaly. The first bone marrow transplantation attempted on an affected child in 1990 in Manchester failed because the patient died of infections complications. After the failure of the first transplantation, our little patient is now healed twenty one months after the second BMT and biochemical anomalies are corrected. If a long follow up is necessary to appreciate the long-term efficiency of this treatment, allogenic bone marrow transplantation seems to cure Günther's disease and must be proposed as the treatment of this affection.

Efficient and stable adeno-associated virus-mediated transduction in the skeletal muscle of adult immunocompetent mice.

Recombinant adeno-associated virus (rAAV) vectors were evaluated for gene transfer into the skeletal muscle of adult immunocompetent mice. A study using a vector encoding nuclear localized beta-galactosidase (rAAV-nls-lacZ) examined: (i) the efficiency and duration of transgene expression; (ii) the status of the AAV genome in the transduced fibers; and (iii) the possibility of improving gene transfer by inducing muscle regeneration. In the absence of regeneration, the injection of 1.7 x 10(7) particles in the quadriceps resulted in gene transfer to 10-70% of myofibers. Histological analysis indicated that the vector was able to reach myofiber nuclei distant from the injection point. Cellular infiltrates were absent at early time points but became conspicuous in the vicinity of some positive fibers at 4-8 weeks and subsided by 26 weeks. Southern analysis indicated that one to three copies of the vector genome were present per cell genome equivalent. They were associated with high-molecular-weight DNA in the form of tandem oligomers or interlocked circles. Gene transfer was not facilitated in the regenerating muscle. Rather, an early inflammatory response resulted in the elimination of most positive fibers after 8 weeks. The presence of regenerated fibers with beta-galactosidase-positive nuclei suggested that myoblasts had been transduced and were able to fuse to form new fibers. Gene transfer in the absence of immune reactions against the transgene product was studied by injecting mice with a rAAV carrying the murine erythropoietin (mEpo) cDNA. Dose-dependent elevation in the hematocrit was measured for over 200 days and corresponded to 5- to 20-fold increases in plasma Epo levels. We conclude that AAV vectors efficiently and stably transduce post-mitotic muscle fibers and myoblasts in vivo.

[Vaccination against hepatitis B virus. Value of intradermal administration in dialysed patients non responsive to intramuscular approach]. / Vaccination contre le virus de l'hépatite B. Intérêt de l'administration intradermique chez les dialysés non répondeurs par voie intramusculaire.

OBJECTIVES: Approximately 16-27% of dialysis patients (DP) have no detectable antibodies after 5 intramuscular injections of hepatitis B vaccine and represent a group at high risk to contract hepatitis B virus. We report the efficacy of the intradermal route of a recombinant hepatitis B vaccine (r-HBV) in non-responsive dialysis patients in our dialysis unit. METHODS: Intradermal vaccinations were performed in 20 dialysis patients (mean age 62 years) non-responsive to the intramuscular injections (mean 6.8). Five micrograms of r-HBV (Engerix B, SK and F) were administered intradermally every two weeks (maximum 70 micrograms) until a level of anti-HBV antibodies (anti-HBs) arbitrarily choosen of > or = 230 mUI/ml was attained. Anti-HBs was determined after the fourth and subsequent intradermal injections (IMX, Abbott). RESULTS: Fourteen dialysis patients (70%) developed anti-HBs > 10 mUI/ml (geometric mean titers of 330 mIU/ml). Among these, 9 developed seroprotective levels before the fifth injection. Five patients developed anti-HBs > or = 1000 mUI/ml and 6 others developed anti-HBs > or = 230 mUI/ml. After the intradermal injections were discontinued, 11 patients were monthly monitored for at least 3 months, and 6 for one year. The geometric mean antibody level was at 3 months: 157 (n = 11), at 6 months: 122 (n = 8), at nine months: 117 (n = 6), and at 12 months: 66 mIU/ml (n = 6). The age and the sex, haemodialysis duration, albumin levels or treatment by erythropoietin did not seem to play a role in appearance of anti-HBs. CONCLUSIONS: Our experience in 20 dialysis patients shows that repeated low-dose intradermal injections resulted in long-term seroprotection in a substantial number of dialysis patients non-responsive to the intramuscular vaccinations.

[Peritoneal dialysis in people more than 75 years old]. / Dialyse péritonéale chez les personnes âgées de plus de 75 ans.

Over 75 years old peritoneal dialysis patients can be treated with at least as good results as those of hemodialysis. Peritoneal dialysis is the only method used to treat old patients at home with psychological profits. Regarding the lack of references on nutritional state of uremic old patients and on early death forecast factors geriatric peritoneal dialysis knowledges are not yet well established.

[Chylous ascites in 12 patients undergoing peritoneal dialysis]. / Ascite chyleuse chez douze patients traités par dialyse péritonéale.

Chylous ascites is a rare clinical entity often secondary to a lymphoma. In peritoneal dialysis even mild chylous ascites can cause cloudiness of the peritoneal effluent and thus lead to early diagnosis. Twelve cases of chylous ascites (defined by the presence of chylomicrons) among 230 patients with chronic renal failure treated in two peritoneal dialysis centers (Limoges and Saint-Pierre de la Réunion) are reported. A malignancy was encountered in only two cases (a B-cell lymphoma and an ovarian cancer). In the other cases, a precise diagnosis was difficult to establish and was only presumed. Thus chylous effusion in seven cases seemed secondary to cirrhosis, chronic pancreatitis, systemic amyloïdosis or cardiac failure. In three cases the cause was unknown, although microtrauma due to the Tenckhoff catheter was highly suspected. Chylous ascites lasted more than two years in four cases. The long-term nutritional consequences did not justify a change in the method of dialysis.

[Peritonitis in continuous ambulatory peritoneal dialysis: diagnosis and treatment]. / Les péritonites en dialyse péritonéale continue ambulatoire: diagnostic et traitement.

Several antibiotic regimens to treat CAPD related peritonitis have been published. Some of them do not have any severe side effect. But they are efficient in less than 2/3 of the cases. Other treatments (2 antibiotics, one of them is an aminoglycoside) are more frequently efficient, but they seem to have severe ototoxicity. We propose the use of cephalosporins and quinolones for first line treatment of CAPD peritonitis. This regimen seem highly efficient without severe side effect.

Subsequent development of acute non-lymphocytic leukemia in patients treated for Hodgkin's disease.

A nested case control study was carried out to investigate the association between treatment of patients with Hodgkin's disease (HD) and the risk of developing acute non-lymphocytic leukemia (ANLL). Seven Cancer Centers of the International Cancer Patient Data Exchange System of the UICC participated. A study cohort was selected consisting of 1,681 nonpretreated patients with HD, diagnosed from 1972 through 1978, and followed up through 1984. The median follow-up time was 66 months. Eighteen cases of leukemia were observed in the cohort. The risk of development of ANLL was significantly greater for male than for female patients. The treatment characteristics associated with an increased risk of developing ANLL were extensive radiotherapy, splenectomy and the chemotherapy combination of vincristine, procarbazine and mechlorethamine.