Comparative evaluation of three new commercial immunoassays for anti-Müllerian hormone measurement.

STUDY QUESTION: How do the three new anti-Müllerian hormone (AMH) assay methods, manufactured by Beckman Coulter, Roche and Ansh Labs compare with each other and with the Gen II assay? SUMMARY ANSWER: The three new AMH assays are well correlated among themselves and with the Gen II assay, although differences in calibration do exist. WHAT IS KNOWN ALREADY: The Gen II assay has been the mainstay method for AMH measurement in the past few years. Recently, a few new AMH measurement methods have come to the market. STUDY DESIGN, SIZE, DURATION: This was a prospective assay evaluation performed on 178 human serum samples. PARTICIPANTS/MATERIALS, SETTING, METHODS: AMH concentration was measured in residual serum samples donated by female patients in a reproductive medicine centre. The three new assay methods were tested in parallel and the numerical values obtained were compared among themselves and with those obtained by the Gen II assay. The assay stability upon different sample storage conditions, intra-assay and inter-assay precision, linearity and dilution recovery, and diagnostic performance for polycystic ovary syndrome (PCOS) of the three new AMH assay methods were also compared. MAIN RESULTS AND THE ROLE OF CHANCE: AMH values measured by the Gen II kit and the three new assay methods have good correlations (R > 0.9 for all pairwise correlations). Values measured by the Ansh Labs assay were significantly higher, whereas those by the Roche assay were significantly lower, than those from the Gen II and Beckman-Coulter automated assays (P < 0.05). AMH values were significantly different when measured on the fresh and frozen-thawed serum sample (at -20oC and -80oC) for all three new methods (P < 0.05), but the magnitude of difference was very small with the Beckman-Coulter automated assay and Roche assay. The intra-assay coefficients of variation (CVs) were 0.7-2.2%, 0.5-1.4%, and 1.4-5.4% for the Beckman-Counter automated, Roche and Ansh Labs assays, respectively. Their inter-assay CVs were 0.9-2.5%, 0.7-1.9%, and 6.2-13.5%, respectively. All three new assay methods showed acceptable linearity, and provided excellent discrimination of PCOS from controls. LIMITATIONS, REASONS FOR CAUTION: The precision and dilution linearity experiments involved a small sample size, although these were not the primary outcome measures and have been properly evaluated in previous publications. The study was not designed or powered for determining diagnostic cut-off values. WIDER IMPLICATIONS OF THE FINDINGS: The results demonstrate that the three new AMH assay methods are all valid methods to be adopted in the field of reproduction and are a basis for further work on their clinical application. STUDY FUNDING/COMPETING INTERESTS: The authors have no competing interest to declare. The execution of this study was funded by the Department of Obstetrics and Gynaecology, The University of Hong Kong.

The clip and drop back technique in the management of multifocal necrotizing enterocolitis: a single centre experience.

AIM: The surgical management of multifocal necrotizing enterocolitis (NEC) remains a major challenge. The "clip-and-drop" strategy with a second-look laparotomy permits re-assessment of bowel viability after optimization, thus offering the potential of both improving survival and conserving bowel length. This study reviews the outcome of this strategy in a single regional center. METHODS: Since 2000, NEC patients undergoing emergency laparotomy selectively underwent a "clip-and-drop" operation if there was peri-operative instability and/or multifocal disease with uncertain bowel viability. Bowel with full thickness gangrene was resected and bowel-ends were temporarily tied-off; a second-look definitive procedure was performed when the patient had stabilized. For this review, in-hospital and follow-up records were studied retrospectively for demographics, 30-day mortality and long-term outcome. MAIN RESULTS: Between 2000 and 2010, 16 patients underwent a "clip-and-drop" operation. The mean post-conception age was 32.8 weeks (27.7-41.7 weeks) with a median body weight of 1.4 kg (0.76-4.4 kg) at first operation. Preoperative radiograph showed free gas in 43.8% and portal venous gas in 37.5% of patients. 2 patients did not survive to the second laparotomy. 14 patients received a second laparotomy, after a mean of 51 h (35-74 h). 2 patients were found to suffer from NEC totalis on the second laparotomy and died without further procedures. All other patients (n = 12) had stoma formation. 1 patient died 4 days after stoma formation. The 30-day mortality for NEC with the "clip-and-drop" strategy was 31.6% (5/16). Among the 11 survivors, 1 died from liver failure complicated by short bowel syndrome at 5 months post operation, 2 others died from respiratory complications of prematurity despite adequate gastrointestinal function. The median follow-up time for the 8 long-term survivors was 45 months (7-129 months). Their median time to achieving full feeds was 41 days (range 21-105 days) after the second operation. CONCLUSION: The "clip-and-drop" strategy, when used in selected patients with multifocal NEC, may help bowel conservation in survivors.

Minimal access surgery for sigmoid volvulus in children.

A 12-year-old boy presented with large-bowel obstruction due to sigmoid volvulus. Temporary relief was achieved with rectal tube decompression. Elective laparoscopic-assisted sigmoid colectomy was performed. Post-operative recovery was uneventful. The patient remained well with no recurrence after 4 years of follow-up. Laparoscopic-assisted sigmoid colectomy may be the procedure of choice for selected children with sigmoid volvulus.

Electrical stimulation and biofeedback exercise of pelvic floor muscle for children with faecal incontinence after surgery for anorectal malformation.

We report our experience of electrical stimulation and biofeedback exercise of pelvic floor muscle for children with faecal incontinence after surgery for anorectal malformation (ARM). Electrical stimulation and biofeedback exercise of pelvic floor muscle were performed on children with post-operative faecal soiling following repair of intermediate or high type ARM. Children under the age of 5 years or with learning difficulties were excluded. They had 6 months supervised programme in the Department of Physiotherapy followed by 6 months home based programme. Bowel management including toilet training, dietary advice, medications and enemas were started before the pelvic floor muscle exercise and continued throughout the programme. Soiling frequency rank, Rintala continence score, sphincter muscle electromyography (EMG) and anorectal manometry were assessed before and after the programme. Wilcoxon signed rank test was performed for statistical analysis. From March 2001 to May 2006, 17 children were referred to the programme. Twelve patients (M:F = 10:2; age = 5-17 years) completed the programme. There was a trend of improvement in Rintala score at sixth month (p = 0.206) and at the end of programme (p = 0.061). Faecal soiling was significantly improved at sixth month (p = 0.01) and at the end of the programme (p = 0.004). Mean sphincter muscle EMG before treatment was 1.699 microV. Mean EMG at sixth month and after the programme was 3.308 microV (p = 0.034) and 3.309 microV (p = 0.002) respectively. After the programme, there was a mean increase in anal sphincter squeeze pressure of 29.9 mmHg (p = 0.007). Electrical stimulation and biofeedback exercise of pelvic floor muscle is an effective adjunct for the treatment of faecal incontinence in children following surgery for anorectal malformation.

Laparoscopic mobilization of testicular vessels: an adjunctive step in orchidopexy for impalpable and redo undescended testis in children.

The testicular position after conventional inguinal orchidopexy for canalicular, "peeping" and redo undescended testes may not be satisfactory despite retroperitoneal dissection. Laparoscopy allows extensive mobilization of testicular vessels to gain additional length. We review our experience of using laparoscopic mobilization of testicular vessels (LMTV) in orchidopexy for these difficult undescended testes. From January 2003 to May 2004, LMTV was performed in 18 boys. The testicular vessels were mobilized from just proximal to the internal inguinal ring to the level of caecum and sigmoid colon respectively. Fifteen patients had clinically impalpable testes. Diagnostic laparoscopy revealed 13 "peeping" and 2 canalicular testes. LMTV was performed together with inguinal orchidopexy. There were three cases of redo orchidopexies because of unfavourable testicular position after previous surgery. LMTV was performed following inguinal dissection. The median follow-up period is 11.7 months. Sixteen testes are located at the base of scrotum, and two at mid-scrotum. The size is normal in 17 testes, whereas 1 testis is smaller than the contralateral one. LMTV is a safe and efficient adjunctive step in orchidopexy for impalpable and redo undescended testes.

Vasopressin regulates endothelin-B receptor in rat inner medullary collecting duct.

Previous studies have shown that endothelin (ET) antagonizes the actions of arginine vasopressin (AVP) in the renal collecting ducts. On the other hand, the effects of AVP on ET function within the collecting ducts of the kidney have not been investigated extensively. Using isolated inner medullary collecting ducts (IMCD), we examined the possibility that a decrease in ET(B) receptor mRNA accompanied AVP-induced downregulation of ET(B) receptors. Binding studies revealed that overnight incubation of rat IMCD cells with AVP significantly reduced the maximal binding capacity (B(max)) of ET. Activation of adenylate cyclase by forskolin decreased the total ET(B) receptor density by approximately 42% but did not affect the density of ET(A) receptors. The Rp diastereoisomer of adenosine 3', 5'-cyclic monophosphothionate, Rp-cAMPS (a specific inhibitor of protein kinase A), blocked the AVP-induced reduction in ET receptor density. Using competitive PCR method, we also observed downregulation of ET(B) receptor mRNA in IMCD treated with AVP. Additional studies were done with IMCD to determine whether AVP inhibited the ET-induced accumulation of cGMP. We saw a reduction in ET-induced cGMP accumulation when IMCD was incubated overnight with AVP. This inhibition of ET-induced accumulation of cGMP was blocked by Rp-cAMPS. These results suggest that AVP regulates ET(B) receptor expression in IMCD.

Renal hypersensitivity to vasopressin in congestive heart failure.

Plasma vasopressin (AVP) levels are often elevated in congestive heart failure (CHF). To determine the significance of AVP in CHF, we performed clearance studies on the UM-X7.1 strain of cardiomyopathic (CM) hamsters with moderate heart failure and age-matched healthy controls. Exogenous AVP or a selective V2 agonist (0.3 ng.kg-1. min-1) reduced the fractional excretion of sodium (FENa) and water (FEH2O) by 40-46% in the control group. Although the CM hamsters exhibited a blunted physiological response to the V2 agonist, their urinary cAMP levels were fivefold that of normal and reflect an altered regulation of V2 receptor signalling during CHF. Additional studies also showed that infusion of a V2 antagonist (0.3 ng.kg-1. min-1) produced natriuresis and diuresis in CM hamsters (FENa: 7.9 +/- 1.1 vs. 4.8 +/- 0.6%, p < 0.05; FEH2O: 2.2 +/- 3 vs. 1.5 +/- 0. 2%, p < 0.05) but did not decrease fluid reabsorption in the normal hamsters. In conclusion, the attenuated renal response to exogenous AVP in CM hamsters may be attributed to an enhanced endogenous AVP response during CHF.

Downregulation of endothelin B receptors in cardiomyopathic hamsters.

The mechanisms responsible for abnormal fluid retention in congestive heart failure (CHF) are unclear. Studies were conducted to elucidate how endothelin (ET) may contribute to salt and water retention. Cardiomyopathic (CM) hamsters with moderate heart failure were employed for in vivo and in vitro trials. Clearance methods were used to compare the level of renal function in CM hamsters and control animals. Radioligand binding studies were also performed to determine ET receptor distribution in the inner medullary collecting ducts. CM hamsters exhibited an attenuated response to ANF infusion (FENa: 2.7 +/- 0.5 vs. 5.9 +/- 0.8%, p < 0.01; FEH2O: 1.7 +/- 0.3 vs. 3.2 +/- 0.4%, p < 0.01; UcGMP: 11.2 +/- 2.3 vs. 16.6 +/- 2.0 pmol/min, p < 0.05) and a decrease in total ET receptor density (532 +/- 77 vs. 959 +/- 154 fmol/mg protein, p < 0.005). Particularly ETB receptors were significantly reduced (214 +/- 26 vs. 483 +/- 88 fmol/mg protein, p < 0.003). Enalapril therapy simultaneously restored the natriuretic and diuretic effects of ANF and ET receptor density in the diseased animals. These studies suggest that the renin-angiotensin-aldosterone system and ET hormonal system act together, via ETB receptor downregulation, to promote the abnormal fluid retention observed in CHF.