Is the outcome of in-vitro fertilization and embryo transfer treatment improved by spontaneous or surgical drainage of a hydrosalpinx?

A pilot study was designed to examine whether the outcome of embryo transfer in women with a hydrosalpinx might be improved by surgical drainage of the hydrosalpinx at the time of oocyte collection for in- vitro fertilization treatment. A comparative, controlled but retrospective analysis of the results was performed of all women with infective tubal damage aged <40 years old, who had ovulatory cycles, a normal uterus and a partner with normal spermatozoa. A standardized treatment regimen was used. A maximum of three embryos were transferred. Hydrosalpinx was defined by prior hysterosalpingography and/or laparoscopy with transcervical dye injection. A total of 237 embryo transfer cycles in women with hydrosalpinges (tubal distension not visible in 151, visible but not drained in 30 and drained in 56) were compared with 705 embryo transfer cycles in women with tubal disease but no hydrosalpinx. Results were analysed in the first three cycles but also separately in the first cycle to check for bias. Success rates were higher in the first cycle, but did not significantly influence overall differences. Implantation rates were significantly reduced overall in the hydrosalpinx group (8.0 versus 13.2% for controls; P < 0.001), being 8.3% (P < 0.01) in the subgroup without evident tubal distension and 7.5% (not significant) in the drained hydrosalpinx group. This study shows that tubal damage with distal occlusion is associated with a marked reduction in embryo implantation, even in the absence of obvious fluid distension. Surgical drainage of distended hydrosalpinges appears to offer no benefit.      

Identification and characterization of aquaporin-2 water channel mutations causing nephrogenic diabetes insipidus with partial vasopressin response

Congenital nephrogenic diabetes insipidus (NDI) is a rare disease caused most often by mutations in the vasopressin V2 receptor (AVPR2). We studied a family which included a female patient with NDI with symptoms dating from infancy. The patient responded to large doses of desmopressin (dDAVP) which decreased urine volume from 10 to 4 I/day. Neither the parents nor the three sisters were polyuric. The patient was found to be a compound heterozygote for two novel recessive point mutations in the aquaporin-2 (AQP2) gene: L22V in exon 1 and C181W in exon 3. Residue Cys181 in AQP2 is the site for inhibition of water permeation by mercurial compounds and is located near to the NPA motif conserved in all aquaporins. Osmotic water permeability (Pf) in Xenopus oocytes injected with cRNA encoding C181W-AQP2 was not increased over water control, while expression of L22V cRNA increased the Pf to approximately 60% of that for wild-type AQP2. Co-injection of the mutant cRNAs with the wild-type cRNA did not affect the function of the wild-type AQP2. Immunolocalization of AQP2-transfected CHO cells showed that the C181W mutant had an endoplasmic reticulum-like intracellular distribution, whereas L22V and wild-type AQP2 showed endosome and plasma membrane staining. Water permeability assays showed a high Pf in cells expressing wild-type and L22V AQP2. This study indicates that AQP2 mutations can confer partially responsive NDI.      

The evolutionary origin of the major histocompatibility complex: Polymorphism of class II α chain genes in the cartilaginous fish

T cells recognize antigen (Ag) in the form of peptides bound to the major histocompatibility complex (MHC) molecule. One of the important issues in evolutionary immunology is to identify the stage in phylogeny when this mode of Ag recognition emerged. At present, there is a considerable controversy as to whether the cartilaginous fish have the bona fide MHC. In our previous study, we showed that the nurse shark, a member of the cartilaginous fish, has (a) gene(s) capable of encoding MHC class II a chains. In the present study, we examined the polymorphism of nurse shark MHC class II a chain genes designated Gici-DAA and Gici-DBA using the polymerase chain reaction. The Gici-DAA and Gici-DBA genes had six and five alleles, respectively, and individual alleles usually differed by multiple nucleotides. In addition, most of the nucleotide substitutions were located at the putative Ag-binding sites, where non-synonymous substitutions occurred more frequently than synonymous substitutions. The fact that the Gici-DAA and Gici-DBA genes display a polymorphism pattern essentially similar to that of mammalian MHC genes playing a major role in Ag presentation suggests that the cartilaginous fish have the bona fide MHC. Thus, the MHC-peptide-based T cell recognition system appears to have arisen at or before the emergence of the cartilaginous fish.     

The role of size, sequence and haplotype in the stability of FRAXA and FRAXE alleles during transmission

Factors involved in the stability of trinucleotide repeats during transmission were studied in 139 families in which a full mutation, premutation or intermediate allele at either FRAXA or FRAXE was segregating. The transmission of alleles at FRAXA, FRAXE and four microsatellite loci were recorded for all individuals. Instability within the minimal and common ranges (0-40 repeats for FRAXA, 0-30 repeats for FRAXE) was extremely rare; only one example was observed, an increased in size at FRAXA from 29 to 39 repeats. Four FRAXA and three FRAXE alleles in the intermediate range (41-60) repeats for FRAXA, 31-60 for FRAXE) were unstably transmitted. Instability was more frequent for FRAXA intermediate alleles that had a tract of pure CGG greater than 37 although instability only occurred in two of 13 such transmissions: the changes observed were limited to only one or two repeats. Premutation FRAXA alleles over 100 repeats expanded to a full mutation during female transmission in 100% of cases, in agreement with other published series. There was no clear correlation between haplotype and probability of expansion of FRAXA premutations. Instability at FRAXA or FRAXE was more often observed in conjunction with a second instability at an independent locus suggesting genomic instability as a possible mechanism by which at least some FRAXA and FRAXE mutations arise.      

Relationship between silicosis and rheumatoid arthritis

The relationship between rheumatoid arthritis and silicosis was studied by means of a case-control study in South African gold miners. One hundred and fifty seven miners with rheumatoid arthritis classified as "definite" (91) or "probable" (66) were individually matched by year of birth with miners who had no evidence of rheumatoid arthritis. Unmatched analysis of the case-control status for "probable" and "definite" cases yielded an odds ratio of 2.84 (p = 0.0001). Separate analyses yielded an odds ratio of 3.79 (p = 0.0006) for "definite" cases, a non-significant odds ratio for "probable" cases, and an odds ratio of 5.00 (p = 0.0003) for the presence of rheumatoid factor. These results could not be explained on the basis of cumulative dust exposure or intensity of exposure. The rate of progression of silicosis in both the "definite" and the "probable" groups was greater than for the control patients with silicosis, as was the probability of silicosis presenting at the start with larger nodules (type r).     

Emergency treatment and long-term follow-up of posterior urethral valves

Posterior urethral valves have a broad spectrum of clinical severity determined by the degree and reversibility of the long stepwise sequence of secondary pathology. Neonatal azotemia and severe bilateral reflux are particularly important negative prognostic factors. In the mild cases, valve ablation with or without delayed reconstruction is good therapy. In the very severe cases, our interpretation of all the clinical and experimental information now available suggests that the time interval and the level of decompression are extremely important. Achievement of consistent low caliceal pressure without stasis and infections should be achieved as soon as possible. We do not agree with the philosophy of "valve ablation and wait and see" for secondary reconstruction as applied to the severe cases. An analogous philosophy would be treating all respiratory infections as upper respiratory infections and applying aggressive appropriate therapy for pneumonia only if the patient does not respond clinically. However, all controversy aside, the management of neonatal infants with posterior urethral valves remains a difficult and challenging problem for us all. The real challenge will be to improve published management results to the point that the family faced with decisions regarding an in utero diagnosis of posterior urethral valves will have enough hope to continue the pregnancy.     

An underlying mechanism for improved liver preservation with a combined histidine-lactobionate-raffinose flush solution

In previous experimental liver transplant studies, it was possible to extend cold ischaemic time (CIT) by using a flush/storage solution combining histidine, lactobionate and raffinose (HLR). In this study, energy metabolism, glycolytic substrate (glucose) and anaerobic end-product (lactate) were examined in rat liver over 24 h of cold storage to determine the mechanism of action of the HLR solution. In livers subjected to simple flush and storage with the HLR solution. levels of ATP and ADP were considerably higher than livers stored with modified UW throughout 24 h of storage; at 4 h of storage, ATP and ADP levels were 1.1 and 3.1 mol/g for HLR solution versus 0.18 and 0.81 mol/g for UW solution. Total adenylate contents (TA=ATP+ADP+AMP) also remained 1–2 mol/g higher in HLR-treated livers than those preserved in UW; TA values ranged from 3.8 to 5.7 mol/g. Glucose increased to 20–35 mol/g by 10–24 h of storage (similar to the UW group). Lactate rose to almost twice that in livers stored in UW; total lactate accumulation was approximately 10.0 mol/g. This study demonstrated that the combined HLR solution is able to prolong the maximum safe CIT by increasing anaerobic metabolism and consequently preserving liver energetics. The second part of the experiment examined the effect of continuous perfusion (with/without O₂) over the 1st h of cold ischaemia. Under current methods of liver flushing and excision, the 1st h of cold storage may be the critical time of metabolic adjustment since most of the pH and ATP changes occur during this period. Therefore, we tested the hypothesis that the combination of a simple flush with an additional brief 1-h perfusion period prior to storage would enhance the maintenance of hepatic energetics. There was no beneficial effect of 1 h of perfusion without O₂ compared to simple HLR flush and storage. However, perfusion with O₂ resulted in prolonged maintenance of high energy adenylates and total adenylates; at 10 h of storage ATP was 1.0, ADP 3.3, and TA 5.7 mol/g. However, any improvement in ultimate viability following long-term storage of the livers in these two groups needs to be tested in an animal transplant model.     

The RecBC enzyme loads RecA protein onto ssDNA asymmetrically and independently of chi, resulting in constitutive recombination activation

Double-strand DNA break repair and homologous recombination in Escherichia coli proceed by the RecBCD pathway, which is regulated by cis-acting elements known as chi sites. A crucial feature of this regulation is the RecBCD enzyme-directed loading of RecA protein specifically onto the 3'-terminal, chi-containing DNA strand. Here we show that RecBC enzyme (lacking the RecD subunit) loads RecA protein constitutively onto the 3'-terminal DNA strand, with no requirement for chi. This strand is preferentially utilized in homologous pairing reactions. We propose that RecA protein loading is a latent property of the RecBCD holoenzyme, which is normally blocked by the RecD subunit and is revealed following interaction with chi.