Spontaneous heterotopic pregnancy presenting with tubal rupture

We present the case of a woman who sought pregnancy termination but who, in the interval between consultation and surgical termination, presented with clinical signs of a ruptured ectopic pregnancy. This was managed as such, but post-operative follow-up soon revealed that she also carried a viable intrauterine pregnancy.      

Analysis of the transactivation domain of the androgen receptor in patients with male infertilitv

Wang Q, Ghadessy FJ, Yong EL. Analysis of the transactivation domain of the androgen receptor in patients with male infertility. Clin Genet 1998: 54: 185–192. 0 Munksgaard, 1998
Genetic defects of the human androgen receptor (AR) can cause a wide spectrum of androgen insensitivity syndromes (AIS) in XY individuals ranging from phenotypic females, to defective spermatogenesis in otherwise normal males. We screened the non-polymorphic regions of exon 1, transactivation domain (TAD), of the AR gene in 153 subjects with varying degrees of defective spermatogenesis of unknown aetiology, and compared them to 100 healthy fertile controls. Three different single-strand conformation polymorphisms were detected and sequencing of the mutant fragments revealed three G+A transitions in codons 210, 211 and 214. The first two mutations were polymorphisms and the transition in codon 211 was related to ethnic origin occurring in 10–15% of Indian or Middle-Eastern subjects, but not in the majority of Chinese. The third mutation resulted in a non-conservative glycine to arginine substitution at codon 214 (G214R) and was associated with ˜ 20% lower transactivation capacity compared to the wild-type (WT). This study, the first screening of the AR TAD for subtle mutations, in a large group of males with defective spermatogenesis, has uncovered novel polymorphisms which may be useful in ethnic studies. Although a possible pathogenic mutation was uncovered, mutations of the non-polymorphic portions of the TAD of the AR do not appear to have a major role in the aetiology of idiopathic male infertility.     

Investigating the interaction of McN-A-343 with the M1 muscarinic receptor using its nitrogen mustard derivative and ACh mustard

Background and purpose:

We investigated how McN-A-343 inhibited the alkylation of the M₁ muscarinic receptor by its nitrogen mustard derivative and that of ACh to identify whether it interacts allosterically or orthosterically.

Experimental approach:

We incubated the M₁ muscarinic receptor expressed in Chinese hamster ovary cells with ACh mustard for various periods of time in the presence of McN-A-343 or known allosteric and orthosteric ligands. After stopping the reaction and removing unreacted ligands, unalkylated receptors were measured using [³H]N-methylscopolamine. Analogous experiments were done using a nitrogen mustard analog of McN-A-343. Affinity constants, cooperativity values for allosteric interactions and rate constants for receptor alkylation were estimated using a mathematical model.

Key results:

The kinetics of receptor alkylation by the nitrogen mustard derivatives of ACh and McN-A-343 were consistent with a two-step model in which the aziridinium ion rapidly forms a reversible receptor complex, which converts to a covalent complex at a slower rate. The inhibition of receptor alkylation by acetycholine, N-methylscopolamine and McN-A-343 was consistent with competitive inhibition, whereas that caused by gallamine was consistent with allosterism. Affinity constants estimated from alkylation kinetics agreed with those measured by displacement of [³H]N-methylscopolamine binding.

Conclusions and implications:

Our results suggest that McN-A-343 and its nitrogen mustard derivative interact competitively with ACh and N-methylscopolamine at the orthosteric site on the M₁ muscarinic receptor. Measuring how drugs modulate the kinetics of receptor alkylation by an irreversible ligand is a powerful approach for distinguishing between negative allosteric modulators and competitive inhibitors.     

Venous segmentation of the spleen

Summary The authors conducted a study of the human splenic venous system by corrosion cast. The existence of two main venous territories or lobes separated by an avascular plane is confirmed. Smaller territories or segments, drained systematically by segmentary veins, and also separated by avascular planes, are defined in them. Their number ranged from four to eight, the mean being five segments. Four different ways of confluence of intrasplenic vessels forming the splenic vein are described.

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Segmentation veineuse de la rate

Résumé Les auteurs ont mené une étude du système veineux de la rate chez l'homme par injection-corrosion. Ils confirment l'existence de deux principaux territories ou lobes séparés par un plan avasculaire ; des territories plus petits, ou segments, drainés de manière systématique par des veines segmentaires, et également séparés par des plans avasculaires sont définis à l'intérieur de ces lobes. Leur nombre se situe entre quatre et huit, la moyenne est de cinq segments. Quatre modes différents de confluence des vaisseaux intra-spléniques à l'origine de la v. splénique sont décrits.

     

Altered folate and vitamin B12 metabolism in families with spina bifida offspring

Folic acid intake reduces the risk of neural tube defects (NTDs). Although the 677C-->T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene is a risk factor for NTDs, it only partly explains the elevated homocysteine levels in mothers of children with NTDs. We measured vitamin B12, folate and homocysteine in patients with spina bifida (SB), their parents, and in controls, to investigate which other enzymes of homocysteine metabolism might be defective. Because homozygosity for the 677C-->T mutation causes decreased plasma folate and increased red-cell folate (RCF) and plasma homocysteine levels, we excluded individuals homozygous for that mutation. The remaining SB patients and their parents still had lowered plasma folate and elevated total homocysteine levels, and a small subset had decreased vitamin B12 levels. Red-cell folate was the same in all groups, suggesting that dietary folate intake and its uptake was normal. Risk of SB was increased at the 25th percentile of plasma folate and at the 75th percentile of homocysteine values in SB patients and their parents, and at the 5th and 25th percentiles of vitamin B12 in mothers with SB- affected offspring. This underlines the functional importance of homocysteine remethylation to methionine. There was no correlation between vitamin B12 and homocysteine or RCF. In combination with the lowered plasma folate (80-90% 5-methyltetrahydrofolate), our data do not support a major involvement of methionine synthase in the aetiology of SB. Our data rather favour the involvement of genetic variation at loci coding for the formation of 5-methyltetrahydrofolate, such as MTHFR, methylenetetrahydrofolate dehydrogenase or serine hydroxymethyltransferase.