Müllerian duct cyst masquerading as chronic prostatitis: diagnosis with magnetic resonance imaging using a phased array surface coil

A retrospective study was designed to verify how often an anatomic variation caused the radial sensory nerve entrapment at the forearm (Wartenberg's syndrome). This variation, in which the superficial branch of the radial nerve emerges from under the fascia between two slips of a split brachioradialis tendon, was mentioned once in a clinical textbook as a basis for nerve entrapment but was found to occur in 5 of 150 dissected arms in 4 of 75 cadavers (3.3% of the investigated arms) in a recent anatomic study. To evaluate the incidence of this variation, 143 operative reports from patients who had Wartenberg's syndrome were reviewed. The variation was observed in seven patients. We conclude that any operation for Wartenberg's syndrome should include a thorough investigation of the site where the radial sensory nerve emerges from under the fascia and, if the nerve emerges through a split brachioradialis tendon, the anomalous tendon slip should be divided.     

Phosphoenolpyruvate carboxykinase from Trypanosoma cruzi. Purification and physicochemical and kinetic properties

Phospho enolpyruvate carboxykinase (PEPCK) has been purified to homogeneity from epimastigotes of the Tul 0 strain of Trypanosoma cruzi. The physicochemical parameters determined allowed the calculation of an average molecular mass of 120 kDa; the subunit molecular mass, about 61 kDa, is in good agreement with the value of 58.6 kDa recently determined from the sequence by Sommer et al. (FEBS Lett. 359 (1994) 125-129). The PEPCK from T. cruzi presented, in addition to its molecular mass, typical properties of other ATP-linked PEPCKs, namely strict specificity for ADP in the carboxylation reaction and lower specificity in the decarboxylation and exchange reactions, and synergistic activation by CdCl2 or MgCl2 when added in addition to MnCl2. The enzyme presented hysteretic behaviour, shown by a lag period in the carboxylation reaction, which was affected by dilution and preincubation. The decarboxylation reaction catalyzed by the T. cruzi PEPCK was not inhibited by excess of ATP-Mn. The apparent Km values for the carboxylation reaction, including the low value for PEP (0.035 mM) are compatible with an important role of PEPCK, as suggested by previous NMR experiments, on the CO2 fixation in vivo which leads to succinate excretion during aerobic fermentation of glucose.     

Ribozyme-mediated RNA degradation in nuclei suspension

Ribozymes containing 2'-fluoro- and 2'-amino-modified pyrimidine nucleosides in combination with terminal phosphorothioate linkages were targeted against HTLV-I tax RNA. In order to examine the activity of such chemically modified ribozymes in the nuclear environment, they were incubated with nuclei of a Tax-transformed mouse fibroblast cell line. Ribozyme cleavage of tax RNA was analyzed by the RNase protection assay. Comparison of the cleavage of tax RNA isolated nuclei with that of tax RNA present in nuclei suspension revealed a 30 times more efficient cleavage of the latter one. Pre-treatment with proteinase K and SDS abolished the enhancement of the ribozyme-mediated RNA cleavage. Catalytically inactive ribozymes did not yield any cleavage products. These results demonstrate an augmenting effect of nuclear proteins on the ribozyme-mediated RNA cleavage.     

Evidence for alpha-helical conformation of an essential N-terminal region in the human Bcl2 protein

A region occupying approximately 24 amino acids near the N terminus of human Bcl2 is essential for this cytoplasmic membrane protein's ability to inhibit apoptosis. Systematic mutagenesis of this N-terminal region indicates that only five hydrophobic and aromatic residues within it are specifically required for function. Computerized secondary structure prediction, together with circular dichroism spectroscopy of synthetic peptides, indicates that the region encompassing these five residues has the propensity to take on an alpha-helical conformation in the presence of SDS micelles, which presumably mimic the hydrophobic surfaces of cellular membranes or polypeptides. The five critical residues are predicted to be clustered on one face of this putative helix, where they might serve to mediate protein-protein contacts involved in the multimerization of Bcl2 or in the interaction of Bcl2 with other, as yet unidentified components of the apoptotic pathway. Apparent structural homologues of this helical motif are also present in at least some other anti-apoptotic proteins from the Bcl2 family but not in those family members that tend to potentiate, rather than inhibit, apoptosis.     

Dynamics of time discrimination: II. The effects of multiple impulses

According to a diffusion generalization model, time discrimination is determined by the frequency and recency of preceding intervals of time. A procedure for studying rapid timing was used to investigate whether pigeons' wait-time responses were sensitive to these factors. In Experiment 1 the number (two or eight) and spacing (consecutive or far apart) of 5-s interfood intervals (called impulses) intercalated in a series of 15-s interfood intervals (nonimpulses) were studied. Experiment 2 was identical to the first but the interfood intervals were increased by a factor of three. Overall, impulses shortened wait times in the next interfood interval. However, several impulses occurring in succession extended the localized effect of an impulse: Wait times following a set of eight-close impulses were slow to recover to preimpulse levels. The results show that linear waiting is only an approximation to the dynamic process, and a process that is sensitive to events in an animal's remote past, such as the diffusion generalization model, provides a better account of rapid timing effects.     

Differential expression of CD44v6 in adenocarcinoma of the pancreas: an immunohistochemical study

Alternative splicing gives rise to numerous CD44 isoforms, some of which seem to have a role in tumour metastasis. Specifically, a variant form of CD44 with sequences encoded by exon v6 (CD44v6) confers metastatic potential when transfected into a nonmetastasizing cell line of rat pancreatic adenocarcinoma. This study has investigated standard CD44 (CD44s) and CD44v6 expression immunohistochemically in 6 samples of normal pancreatic tissue, 4 of tissue affected by chronic pancreatitis, and 24 of tissue from metastasizing and nonmetastasizing pancreatic adenocarcinomas. In addition, 18 samples from lymph node or visceral metastases were included in the study. CD44s was expressed in nonneoplastic tissue and in tissue from pancreatic adenocarcinomas. In contrast, CD44v6 was not detected in any of the normal tissue or chronic pancreatitis specimens, whereas 54% of pancreatic adenocarcinomas and 55% of metastases expressed this variant exon. Although it is not clear whether CD44 isoforms containing exon v6 play a part in malignant progression in the human exocrine pancreas, it seems plausible that the expression of multiple isoforms containing this and other variant exon confers a selective advantage on pancreatic adenocarcinoma.     

Infection by hepatitis C virus through contaminated intravenous immune globulin: results of a prospective national inquiry in France

BACKGROUND: A recent hepatitis C virus (HCV) outbreak has been suspected of being caused by an infusion of intravenous immune globulin. STUDY DESIGN AND METHODS: Three laboratories were mandated by the French regulatory agency to prospectively screen on a national scale those persons having received suspected batches: 233 exposed patients were recalled and tested for HCV antibody and for HCV RNA. RESULTS: Nineteen patients (8.1%) were found positive for HCV RNA; 7 of these 19 were positive for the HCV antibody. CONCLUSION: The link between HCV infection and intravenous immune globulin was reinforced by the overrepresentation of the 2b genotype (58%), which contrasts with the low prevalence of this genotype in France (1%).     

Assembled pre-B cell receptor complexes are retained in the endoplasmic reticulum by a mechanism that is not selective for the pseudo-light chain

The pre-B cell receptor (BCR) complex, consisting of micro heavy chain, a pseudo-light chain, and the Mb-1/B29 heterodimer, directs the transition to the mature B cell stage. Plasma membrane expression of the pre-BCR is extremely low, despite its presumed signaling function. We have compared assembly and intracellular transport of the pre-BCR complex with that of the BCR complex in mature B cells. Synthesis and assembly rate of pre-BCR and BCR components are comparable. However, the pre-BCR is subject to a highly efficient retention mechanism, which only allows exit of a few percent of the complexes from the endoplasmic reticulum (ER). This small transported pool of pre-BCR complexes is significantly enriched for protein-tyrosine kinase activity, as compared with the ER-localized receptor pool. Accordingly, the Src-related tyrosine kinase Lyn was found in the transported glycoprotein fraction but not in association with ER-localized glycoproteins. Upon introduction of a conventional light chain into pre-B cells, plasma membrane receptor levels increased, but the efficiency of intracellular transport of the receptor complex was not restored to that in mature B cells. This indicates that the ER retention mechanism is not selective for the pseudo-light chain and may be inherent to pre-B cells. We propose that this retention mechanism contributes to the regulation of pre-BCR-mediated signal transduction.