Pathological and sonographic review of early isolated severe lower urinary tract obstruction and implications for prenatal treatment.

OBJECTIVE: To identify favorable renal histology in fetuses with early severe lower urinary tract obstruction (LUTO) and determine the best timing and selection criteria for prenatal surgery. METHODS: This multicenter, retrospective study included male fetuses with severe LUTO which died before 24 weeks of gestation during the period January 2000 to December 2018. Age-matched controls were used as reference standard for renal histology. Prenatal ultrasound features and fetal serum and/or urine ß2microglobulin level were retrieved and kidney histology slides (hematein-eosin-safran and α-smooth-muscle-actin (αSMA) immunostaining) were prepared and reviewed. αSMA-positive staining of the blastema is due to its aberrant differentiation into myofibroblastic cells. Cases were sorted into histopathologic groups (favorable or unfavorable) according to the blastema's morphology and αSMA labeling and the data of these groups were compared. RESULTS: Included in the study were 74 fetuses with a median gestational age at outcome of 17 + 6 (range, 13 + 0 to 23 + 5) weeks. Parenchymal organization was preserved in 48% of the kidneys. A blastema was present in 90% of the kidneys, but it was morphologically normal in only 9% and αSMA-negative in only 1% of them. Most (82%) fetuses had an unfavorable prognosis, and 36% of fetuses died ≤ 18 weeks and had severe renal lesions detected on histology (early unfavorable prognosis). A favorable renal prognosis was associated with an earlier gestational age (P = 0.001). Fetuses with LUTO had a significantly lower number of mature glomeruli (P < 0.001) compared with controls. However, there was no significant difference in the number of glomeruli generations between the early-unfavorable-prognosis group (≤ 18 weeks) and the group with a favorable prognosis (P = 0.19). A comparison of prenatal ultrasound features and biochemical markers between groups could not identify any prenatal selection criteria. CONCLUSIONS: Before 18 weeks, around 30% of fetuses with severe LUTO still have potential for kidney development. Identification of these cases would enable them to be targeted for prenatal therapy. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Malignancy after Augmentation Enterocystoplasty: A Nationwide Study of Natural History, Prognosis and Oncogene Panel Analysis.

PURPOSE: We report the natural history and prognosis of tumors after augmentation enterocystoplasty, with a molecular analysis using an oncogene panel to search for potential targeted therapies. MATERIALS AND METHODS: This multicenter, nationwide, retrospective study included 16 patients. A panel of 21 clinically relevant oncogenes was tested on archival tumor specimens using next-generation sequencing. Survival rate was the main clinical outcome and sequences were compared to the reference genome for the genetic outcome. RESULTS: Augmentation enterocystoplasties were performed mainly for congenital neurogenic bladder and bladder exstrophy at a median patient age of 17 years (range 4 months to 45 years). Most of the malignancies were diagnosed because of clinical manifestations, with a median latency period of 20 years. Adenocarcinomas were mainly found after gastrocystoplasty, whereas urothelial cell carcinomas were typically found after colocystoplasty. Of the 16 patients 13 were diagnosed at an advanced stage of the disease (positive lymph nodes in 7, distant metastases in 6). The overall 1-year survival rate was 56%. Only 3 patients remained disease-free at a median followup of 70 months. Of the 9 tumors with analyzable DNA 4 were wild-type and 5 harbored missense mutations (KIT-p.Pro573Ser, PDGFRA-p.Glu587Lys, KRAS-p.Gly12Asp, ERBB4p.Arg484Lys, CTNNB1-p.Ser37Phe and p.Ser47Asn). CONCLUSIONS: Malignancy after augmentation enterocystoplasty is diagnosed late with frequent metastases and a very low 1-year survival rate. More than half the tested samples harbored missense mutations in oncogenes accessible to targeted therapies. An international collaboration to enlarge the genetic panel analysis of these tumors may offer new therapeutic hope to patients.

Biometric and morphological features on magnetic resonance imaging of fetal bladder in lower urinary tract obstruction: new perspectives for fetal cystoscopy.

OBJECTIVES: Incompatibility between currently available fetoscopes and the anatomical constraints of the distended fetal bladder, with the resulting curvature around the bladder neck, account for most technical difficulties during fetal cystoscopy in lower urinary tract obstruction (LUTO). The aim of this anatomical study was to assess by magnetic resonance imaging (MRI) the variation in three bladder angles (bladder-neck angle (BNA), vesicourethral angle (VUA) and angle between bladder dome and posterior urethra (DUA)), according to gestational age (GA), bladder volume and the presence of LUTO. METHODS: From our fetal medicine database, we retrieved for review 46 MRI examinations of male fetuses between 2015 and 2019, including 17 with LUTO, examined at a mean GA of 28.1 (range, 17.3-35.0) weeks and 29 age-matched controls, examined at 29.9 (range, 21.9-35.0) weeks. We measured bladder volume, bladder-wall thickness and the three bladder angles, and used the Mann-Whitney U-test to compare values between groups. Variations according to GA and bladder volume were determined using analysis of variance (ANOVA). A reliability study was performed using the Bland-Altman method and Lin's correlation coefficient was calculated. RESULTS: Both bladder volume and bladder-wall thickness were significantly greater in the LUTO group (P < 0.01). BNA was significantly larger in LUTO compared with control fetuses: the mean (range) was 127.1° (101.6-161.6°) vs 111.2° (88.5-157.3°) (P < 0.01). DUA averaged 117° and showed no difference between the groups (P = 0.92). No statistical comparison was performed on VUA since this was not measurable in most control fetuses. ANOVA showed no variation of any angle with bladder volume in both LUTO fetuses and control fetuses. BNA in LUTO fetuses was the only angle to vary with GA, being larger after, compared with at or before, 25 weeks (P = 0.04). The reliability study showed an acceptable bias for both intra- and interobserver reproducibility for all three angles. CONCLUSION: The findings that BNA is increased by approximately 15° in fetuses with LUTO and DUA averages 117° could aid in development of a customized fetal cystoscope and help to overcome the current technical challenges of fetal cystoscopy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Review shows that using surfactant a number of times or as a vehicle for budesonide may reduce the risk of bronchopulmonary dysplasia.

AIM: Bronchopulmonary dysplasia (BPD) remains the most common respiratory morbidity in immature infants. This review describes the diagnosis of BPD has evolved and summarises the therapeutic approaches that have made it possible to limit the incidence of BPD. METHOD: We reviewed the literature from the first definition of BPD by Northway in 1967 to the surfactant treatment policies that are currently in use, drawing on more than 50 papers up to 2017. RESULTS: Our review showed that improvements in neonatal survival have been associated with an increased risk of severe BPD, significant levels of long-term morbidity and the increased use of healthcare resources. These issues have encouraged researchers to explore potential new treatments that limit the incidence of BPD. Repeated surfactant instillation and the use of surfactant as a vehicle for budesonide are promising strategies for alleviating the burden of chronic lung disease. Ongoing research on surfactant or stem cell therapy may further improve the respiratory prognosis for prematurely born children. CONCLUSION: Considerable research has been carried out into the increase in BPD, which has resulted from improvements in neonatal survival. Key areas of research include repeated surfactant administration, using surfactant as a vehicle for budesonide and stem cell therapy.

Safety and feasability of ureteroscopy for pediatric stone, in children under 5 Years (SFUPA 5): A French multicentric study.

INTRODUCTION: Ureteroscopy (URS) can be proposed as first-line therapy for the management of pelvic stones from 10 to 20 mm and for lower ureteric stones in children. However, little is known about the success and the morbidity of URS in young children. Ureteroscopic treatment may present matters in young children because of the small size of the pediatric kidney and the small size of the collecting system. OBJECTIVE: To assess safety and efficacy of URS for the treatment of urinary stones in children aged of 5 years or less. STUDY DESIGN: After the institutional ethical board approval was obtained, we conducted a retrospective, analytic, multicentric study that included all URS performed between January 2016 and April 2022 in children aged of 5 years or less. In this non-comparative case series, anonymized pooled data were collected from 7 tertiary care centers of pediatric patients. Endpoints were the one-session SFR at 3 months and per and postoperatives complications. Descriptive statistics were applied to describe the cohort. RESULTS: Eighty-three patients were included. For them, 96 procedures were performed at the median age of 3.5 years (IQR: 0.8-5) and median weight of 14 Kg (6.3-23). Median stone size was 13 mm (4-45). There were 65 (67 %) renal stones treated with flexible URS, most of which were in the renal pelvis (30 %) and in the lower calix (33 %). A ureteral access sheath was used in 91 % procedures. Preoperative ureteral stent was placed in 52 (54 %) of patients. None of patients had ureteral dilatation. The single-session SFR was 67.4 % (56.3 and 89.2 % for flexible URS and semi-rigid URS respectively) and children require 1.4 procedures to achieve complete stone clearance. The overall complication rate was 18.7 %, most of them were minor (Clavien I-II). Intraoperative perirenal extravasation (Clavien IIIb) due to forniceal rupture was documented in 6.2 % of cases, related to an increased intrapelvic pressure (IPP) performed in a closed pelvicalyceal system. DISCUSSION: Pediatric urologists should be aware of forniceal rupture based on the presence of extravasation of contrast during endourological procedures especially when they have difficulties to reach lower caliceal stone in small patient. CONCLUSION: URS in patients aged of 5 years or less, is a complex minimally invasive procedure with reasonable efficacy and low morbidity. Intrarenal stones treated by RIRS in young children carries the risk of additional procedures to complete stone clearance.

Renal transplantation in 4 patients with methylmalonic aciduria: a cell therapy for metabolic disease.

INTRODUCTION: Patients with methylmalonic acidemia (MMA) may develop many complications despite medical treatment, in particular, severe central nervous system damage and chronic kidney disease (CKD). A kidney transplant may partially correct the metabolic dysfunctions. Liver, kidney and combined liver-kidney transplantations have been advocated but no guidelines are available to identify the most suitable organ to transplant. PATIENTS AND METHODS: Four patients with MMA (mut° phenotype) received a kidney graft because of repeated metabolic decompensations, with progression to CKD in 3 patients (end-stage kidney disease in two patients and CKD stage III in one patient with an estimated glomerular filtration rate [eGFR] of 40ml/min/1.73m(2)) but normal renal function in one (eGFR of 93ml/min/1.73m(2)) before transplantation. RESULTS: The medium age at transplantation was 7.9y (5-10.2) and the median follow-up was 2.8years (1.8-4.6). Renal transplantation improved the relevant metabolic parameters in 4/4 patients and renal function in the patients with CKD. Plasma and urinary MMA levels immediately decreased and remained normal or subnormal (mean values of plasma MMA before transplantation 1530µmol/L versus 240µmol/L after transplantation, and mean values of urine MMA before transplantation 4700mmol/mol creatinine versus 2300mmol/mol creatinine after transplantation). No further acute metabolic decompensation was observed and protein-intake was increased from 0.60 to 0.83g/Kg/day. One patient transplanted at age 9.7years developed a hepatoblastoma at age 11years with subsequent neurological complications and eventually died. The three other patients are alive. Two of them remained neurologically stable. The 3rd patient who displayed choreoathetosis transiently improved his neurological condition immediately after transplantation and then remained stable. CONCLUSION: Kidney transplantation represents an interesting alternative therapeutic option in methylmalonic aciduria, for renal complications but also as a "cellular therapy" that may significantly reduce metabolic decompensations and hospitalizations. However, further neurological impairment remains possible.

Circumcision and Risk of Febrile Urinary Tract Infection in Boys with Posterior Urethral Valves: Result of the CIRCUP Randomized Trial.

BACKGROUND: Boys with posterior urethral valves (PUVs) have an increased risk of febrile urinary tract infections (fUTIs). Circumcision is believed to reduce the risk of fUTIs in boys, although there are no randomized trials demonstrating this. OBJECTIVE: To determine the effect of circumcision on the risk of fUTIs in boys with PUVs. DESIGN, SETTING, AND PARTICIPANTS: A clinical randomized trial that ran between August 2012 and July 2017 was conducted. The trial was multicentric, including 13 referral centers for pediatric urology. Male boys, aged 1-28 d, diagnosed with posterior urethral valves, confirmed by voiding cystogram, were included. The exclusion criteria included presence of a genital malformation contraindicating performing a circumcision. INTERVENTION: Participants were randomized to neonatal circumcision + antibiotic prophylaxis (CATB) or antibiotic prophylaxis alone (ATB), and followed for 2 yr. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was a risk of presenting fUTIs in each group. An fUTI was defined as fever (>38.5 °C) with evidence of pyuria and culture-proven infection on urinalysis, obtained by urethral catheterization or suprapubic aspiration. A bivariate analysis of the primary outcome was performed using the Kaplan-Meier method. RESULTS AND LIMITATIONS: In total, 91 patients were included: 49 in group CATB and 42 in group ATB. The probability of presenting an fUTI was 20% in group ATB versus 3% in group CATB. The hazard ratio of presenting an fUTI within 2 yr in the ATB group compared with that in the CATB group was 10.3 (95% confidence interval: 1.3-82.5). Sixty-four children (70.3%) had a complete follow-up at 2 yr of age. CONCLUSIONS: Circumcision significantly decreases the risk of presenting an fUTI in boys with PUVs. PATIENT SUMMARY: In this report, we compared, in a multicentric trial, the number of febrile urinary tract infections (UTIs) in boys with posterior urethral valves who had either antibiotic prophylaxis alone or antibiotic prophylaxis and circumcision. We found that those who had a circumcision had a significantly lower risk of febrile UTIs.

[Prenatal path of care following the diagnosis of a malformation for which a novel prenatal therapy is available]. / Parcours prénatal devant une malformation pour laquelle un traitement in utero émergent est disponible.

OBJECTIVES: Fetal therapy is part of the available care offer for several severe malformations. The place of these emergent prenatal interventions in the prenatal path of care is poorly known. The objective of this study is to describe the decision-making process of patients facing the option of an emergent in utero intervention. METHODS: We have conducted a retrospective monocentric descriptive study in the department of maternal-fetal medicine of Necker Hospital. We collected data regarding eligibility or not for fetal surgery and the pregnancy outcomes of patients referred for myelomeningocele, diaphragmatic hernia, aortic stenosis and low obstructive uropathies. RESULTS: All indications combined, 70% of patients opted for fetal surgery. This rate was lower in the case of myelomeningocele with 21% consent, than in the other pathologies: 69% for diaphragmatic hernias, 90% for aortic stenoses and 76% for uropathy. When fetal intervention was declined, the vast majority of patients opted for termination of pregnancy: 86%. In 14% of the considering fetal surgery, the patient was referred too far. CONCLUSION: The acceptance rate for fetal surgeries depends on condition. It offers an additional option and is an alternative for couples for which termination of pregnancy (TOP) is not an option. Timely referral to an expert center allows to discuss the place of a fetal intervention and not to deprive couples of this possibility.

Unusual presentation of a first Branchial cleft cyst associated with an abnormal bony canal -a case report.

BACKGROUND: First branchial cleft anomalies are rare, accounting for only 10% of all branchial cleft anomalies. We report an even more rare and unique case of a branchial cleft cyst with features of both first and second arch derivatives. CASE PRESENTATION: A 6-year-old boy presented to us with a left conductive hearing loss associated with pre-tympanic keratin debris and an ipsilateral painful cervical mass. He had a past medical history of left ear surgery for presumed cholesteatoma 2 years prior and left neck abscess drainage 6 months prior. CT and MRI revealed a lesion originating in the external auditory canal and extending cervically through a bony canal located medial to the facial nerve and terminating as a parapharyngeal cyst. The complete removal was accomplished in one surgical stage consisting of three distinct steps: robotic assisted transoral resection of the pharyngeal cyst, an endaural approach and a parotidectomy approach. CONCLUSION: We believe that our detailed description of this rare first branchial cleft cyst with pharyngeal extension, possibly a hybrid case between a first and second branchial cyst, can serve as a valuable tool to Otolaryngologists - Head and Neck Surgeons who come across a similar unusual presentations.

Left lateral retroperitoneoscopic total nephrectomy of a horseshoe kidney in a 3-year-old boy.

The unilateral or bilateral approach for nephrectomy in horseshoe kidney by minimally invasive surgery has been described. A total binephrectomy by a unilateral retroperitoneoscopic approach was performed for congenital nephrotic syndrome. A unilateral retroperitoneoscopic approach was planned in a 3-year-old boy (13 kg) with congenital nephrotic syndrome resistant to steroids with massive protein loss. The operative time was 160 min. The postoperative course was uneventful with continued hemodialysis until renal transplant 18 months later. The unilateral retroperitoneal approach allows total nephrectomy to be completed safely in horseshoe kidney for benign disease. The retroperitoneal access preserves the abdominal cavity, should peritoneal dialysis be required.

A penicillin- and metronidazole-resistant Clostridium botulinum strain responsible for an infant botulism case.

The clinical course of a case of infant botulism was characterized by several relapses despite therapy with amoxicillin and metronidazole. Botulism was confirmed by identification of botulinum toxin and Clostridium botulinum in stools. A C. botulinum A2 strain resistant to penicillins and with heterogeneous resistance to metronidazole was isolated from stool samples up to 110 days after onset. Antibiotic susceptibility was tested by disc agar diffusion and MICs were determined by Etest. Whole genome sequencing allowed detection of a gene cluster composed of blaCBP for a novel penicillinase, blaI for a regulator, and blaR1 for a membrane-bound penicillin receptor in the chromosome of the C. botulinum isolate. The purified recombinant penicillinase was assayed. Resistance to ß-lactams was in agreement with the kinetic parameters of the enzyme. In addition, the ß-lactamase gene cluster was found in three C. botulinum genomes in databanks and in two of 62 genomes of our collection, all the strains belonging to group I C. botulinum. This is the first report of a C. botulinum isolate resistant to penicillins. This stresses the importance of antibiotic susceptibility testing for adequate therapy of botulism.

Prophylactic ibuprofen versus placebo in very premature infants: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Patent ductus arteriosus is a common complication of prematurity that frequently requires surgical or medical treatment. The benefit of prophylactic treatment by indometacin, a cyclo-oxygenase inhibitor, remains uncertain compared with curative treatment. This benefit could be improved with ibuprofen, another cyclo-oxygenase inhibitor with fewer adverse effects than indometacin on renal, mesenteric, and cerebral perfusion. We aimed to compare prophylactic and curative ibuprofen in the treatment of this abnormality in very premature infants. METHODS: We did a randomised controlled trial in infants younger than 28 weeks of gestation, who were randomly assigned to receive either three doses of ibuprofen or placebo within 6 h of birth. After day 3, symptomatic patent ductus arteriosus was treated first by open curative ibuprofen, then back-up indometacin, surgery, or both. The primary endpoint was need for surgical ligation. Analysis was per protocol. FINDINGS: The study was stopped prematurely after 135 enrollments because of three cases of severe pulmonary hypertension in the prophylactic group. 65 infants received prophylactic ibuprofen, and 66 received placebo. Prophylaxis reduced the need for surgical ligation from six (9%) to zero (p=0.03), and decreased the rate of severe intraventricular haemorrhage from 15 (23%) to seven (11%) (p=0.10). However, survival was not improved (47 [71%] placebo vs 47 [72%] treatment, p=1.00), because of high frequency of adverse respiratory, renal, and digestive events. INTERPRETATION: In premature infants, prophylactic ibuprofen reduces the need for surgical ligation of patent ductus arteriosus, but does not reduce mortality or morbidity. Therefore, it should not be preferred to early curative ibuprofen.

[Early spontaneous ileal perforations in preterm infants: report of 4 cases]. / Perforations iléales précoces sans signes d'entérocolite ulcéronécrosante: à propos de quatre cas survenus chez des prématurés.

An ileal perforation occurred shortly after birth in 4 very premature newborns. Diagnosis was made on an abdominal distension with a pneumoperitoneum on X-ray. There were no biological, radiological nor histological signs of necrotizing enterocolitis. There were no digestive short- or long-term complications. According to the few authors who described this syndrome, there are some risk factors, but they were not clearly involved in our cases. Ileal perforation in the absence of signs of necrotizing enterocolitis is rarely reported but should be well known because of its good prognosis.

Myocardial and coronary endothelial protective effects of acetylcholine after myocardial ischaemia and reperfusion in rats: role of nitric oxide.

1. Recent experiments suggest that acetylcholine (ACh) may exert myocardial protective effects during ischaemia (I) and reperfusion (R). The present study was designed (i) to assess whether ACh limits infarct size and protects coronary endothelial cells in a rat model of I and R, (ii) to evaluate the role of ATP-sensitive potassium (KATP) channels and nitric oxide (NO) in the beneficial effect of ACh (iii) to evaluate whether the protective effect of ACh also extends to coronary endothelial cells and (iv) to assess whether ACh contributes to the beneficial effect of preconditioning. 2. Anaesthetized rats were subjected to 20 min I (left coronary artery occlusion) and 2 h of R. Infarct size was assessed by triphenyltetrazolium (TTC) staining and expressed as a % of the area at risk (India ink injection). Vascular studies were performed on 1.5-2 mm coronary segments (internal diameter 250-300 micros) removed distal to the site of occlusion and mounted in wire myographs. 3. ACh limited infarct size (from 59 +/- 3 to 26 +/- 5%, P < 0.01), and this was prevented by atropine (46 +/- 7%; P < 0.05 vs ACh), but not by the inhibitor of KATP channels, glibenclamide (29 +/- 8%). The inhibitor of NO synthesis NG-nitro L-arginine did not affect infarct size (54 +/- 5%) but abolished the beneficial effect of ACh (59 +/- 8%; P < 0.05 vs ACh), whereas the NO donor 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1 limited infarct size to the same extent as ACh (28 +/- 6%). Preconditioning also limited infarct size (5 +/- 2%, P< 0.01 vs control), and this was not affected by atropine (6 +/- 2%). I and R induced a significant decrease in the endothelium-dependent relaxations of isolated coronary arteries toACh (maximal response: sham: 58+/-4; I/R: 25+/-5%; P<0.01) and this dysfunction was prevented by prior in vivo treatment with ACh (55+/-7%; P<0.01 vs I/R) or (SIN-1 50+/-5%; P<0.05 vs I/R).4 Thus, in the rat model, ACh is able to stimulate potent endogenous protective mechanisms during I and R, which are evident both at the level of myocardial and coronary endothelial cells, and appear entirely mediated through the production of NO. Pharmacological stimulation of this endogenous protective mechanism may constitute a new approach in the treatment of acute myocaridal ischaemia.

Role of endogenous endothelin in myocardial and coronary endothelial injury after ischaemia and reperfusion in rats: studies with bosentan, a mixed ETA-ETB antagonist.

1. Previous studies suggested that endothelin-1 (ET-1) may play a role in myocardial ischaemia and reperfusion. This study was designed to test the effect of a new nonpeptide antagonist of endothelin ETA and ETB receptors, bosentan, on myocardial infarct size, ventricular arrhythmias, and coronary endothelial dysfunction after ischaemia and reperfusion. 2. Anaesthetized male Wistar rats were subjected to 20 min ischaemia (left coronary artery occlusion) followed by 1 h (for the evaluation of coronary endothelial dysfunction) or 2 h (for the evaluation of infarct size) reperfusion, or 5 min ischaemia followed by 15 min reperfusion (for the evaluation of reperfusion arrhythmias). Vascular studies were performed on 1.5-2 mm coronary segments (internal diameter 250-300 microns) removed distal to the site of occlusion and mounted in wire myographs for isometric tension recording. Area at risk and infarct size were determined by Indian ink injection and triphenyl tetrazolium staining, using computerized analysis of enlarged sections after colour video acquisition. 3. Bosentan, administered at a dose which virtually abolished the pressor response to big ET-1 (3 mg kg-1, i.v. before ischaemia) did not affect heart rate, arterial pressure or the rate pressure product before ischaemia, during ischaemia and during reperfusion. Bosentan did not affect the incidence of reperfusion-induced ventricular fibrillation (controls: 86%, n = 14; bosentan: 93%, n = 15), and did not modify infarct size (% of area at risk: controls: 63 +/- 4, n = 10; bosentan: 60 +/- 6, n = 8). Ischaemia followed by reperfusion markedly reduced the endothelium-dependent relaxations to acetylcholine(maximal response: sham: 59 +/- 4%, n = 9; ischaemia-reperfusion: 26+/- 6%, n = 8; P<0.01), characteristic of reperfusion-induced endothelial dysfunction, and this dysfunction was not prevented by bosentan (maximal response to acetylcholine: 25 +/-5%, n = 9; P<0.01 vs sham; P = NS vs ischaemia/reperfusion).4. These experiments suggest that endogenous endothelin does not contribute to myocyte or coronary endothelial injury in this rat model of ischaemia and reperfusion.

Selectivity differences for C18 and C8 reversed-phase columns as a function of temperature and gradient steepness. II. Minimizing column reproducibility problems.

The choice of T and tG as variables for controlling selectivity and resolution during reversed-phase liquid chromatography (RPLC) method development can be used to minimize problems caused by column batch-to-batch irreproducibility. When a new column fails to provide adequate separation of the sample, altered values of T and tG can be predicted that will restore the separation obtained with the previous column. Alternatively, columns from different manufacturers can be tested during method development, in order to find a common set of conditions (T and tG) that provide acceptable separation with two or more of these columns. In this way, any of several columns from different sources become usable for the method. Examples are shown of these different computer-assisted procedures for minimizing problems due to column variability.

Selectivity differences for C18 and C8 reversed-phase columns as a function of temperature and gradient steepness. I. Optimizing selectivity and resolution.

Four experimental runs where temperature T and gradient time tG are varied allow the computer-prediction of reversed-phase liquid chromatographic (RPLC) separation for different combinations of temperature and gradient time. This in turn can provide significant changes in selectivity and a resulting optimization of separation. If this procedure is repeated for different columns, additional control over selectivity and resolution becomes possible. The simultaneous variation of T and tG for columns from different sources was studied for two samples, as a means of evaluating the general advantage of this approach for RPLC method development. Changes in relative retention with T were found to be approximately constant for different values of tG and for different RPLC columns; similarly, changes in relative retention with tG were roughly independent of changes in temperature or the column. The latter relationships can be useful in matching ("tracking") peaks between runs during method development based on the present approach, as well as for other applications discussed in here and in Part II.

Study of cost by type of diagnosis in Switzerland.

Lengths of stay, for a given diagnosis, are poorly correlated between Switzerland, the USA., and Australia; and between 5 hospitals within Switzerland. Three different sets of DRG cost weightings (U.S., French A, French B) are also poorly correlated. Hospital operating efficiencies, standardized by DRG, were estimated and compared. The three sets of cost weightings used all yielded very similar estimates of hospital operating efficiency. The use of current existing systems of cost weightings may, therefore, provide a rapid and cheap means of comparing hospital operating efficiency. In the long run, more precise and detailed cost data will enable national cost weightings to be obtained. Associated issues, such as costing methodologies and perspectives on utilization, are also discussed.