Distinct behavior of mutant triosephosphate isomerase in hemolysate and in isolated form: molecular basis of enzyme deficiency.

In a Hungarian family with severe decrease in triosephosphate isomerase (TPI) activity, 2 germ line-identical but phenotypically differing compound heterozygote brothers inherited 2 independent (Phe240Leu and Glu145stop codon) mutations. The kinetic, thermodynamic, and associative properties of the recombinant human wild-type and Phe240Leu mutant enzymes were compared with those of TPIs in normal and deficient erythrocyte hemolysates. The specific activity of the recombinant mutant enzyme relative to the wild type was much higher (30%) than expected from the activity (3%) measured in hemolysates. Enhanced attachment of mutant TPI to erythrocyte inside-out vesicles and to microtubules of brain cells was found when the binding was measured with TPIs in hemolysate. In contrast, there was no difference between the binding of the recombinant wild-type and Phe240Leu mutant enzymes. These findings suggest that the missense mutation by itself is not enough to explain the low catalytic activity and "stickiness" of mutant TPI observed in hemolysate. The activity of the mutant TPI is further reduced by its attachment to inside-out vesicles or microtubules. Comparative studies of the hemolysate from a British patient with Glu104Asp homozygosity and with the platelet lysates from the Hungarian family suggest that the microcompartmentation of TPI is not unique for the hemolysates from the Hungarian TPI-deficient brothers. The possible role of cellular components, other than the mutant enzymes, in the distinct behavior of TPI in isolated form versus in hemolysates from the compound heterozygotes and the simple heterozygote family members is discussed.     

Does computed tomography improve patients selection for extracorporeal shock wave lithotripsy (ESWL) of radiolucent gallbladder stones?

In 97 patients with radiolucent solitary gallbladder stones, the density of the calculi was evaluated by computed tomography (CT) prior to extracorporeal shock wave lithotripsy (ESWL). Sixty-three percent of the stones were isodense to bile (mean 48 +/- SD 11 HU), and 37% could be identified on CT-sections (maximal density 105 +/- 46 HU, mean density at the largest cross-section 53 +/- 31 HU). There was a slight trend toward better stone fragmentation and higher clearance rate in patients with isodense stones. However, the probability of complete fragment clearance was not significantly different in stones with a high or low CT-density. From these data we conclude that stone selection for ESWL and adjuvant bile acid therapy in patients with radiolucent solitary stones as assessed by oral cholecystography is only marginally improved by computed tomography.     

Diminished blood levels of reduced glutathione and alpha-tocopherol in two triosephosphate isomerase-deficient brothers

The glutathione redox system and alpha-tocopherol, both of which are essential for maintaining the normal structure of biological membranes, some other lipid-soluble antioxidants (lycopene, beta-carotene, retinol), and lipid peroxidation, were investigated in the blood from two triosephosphate isomerase (TPI)-deficient brothers. Both of the genetically identical compound heterozygote brothers have congenital hemolytic anemia, but only one of them has a neurological defect, the second cardinal symptom of TPI deficiency. Whole blood reduced glutathione levels were markedly decreased in both brothers. The glutathione reductase activities as well as the NADPH contents of their erythrocytes were in the normal range or slightly enhanced. Increased ratio of oxidized/reduced glutathione, elevated glutathione S-transferase activity, and increased d-lactate level, a metabolite of the glyoxalase pathway, were detected only in the neurologically affected propositus. The plasma carotenoids (lycopene + beta-carotene), alpha-tocopherol/cholesterol + triglyceride ratios, and the erythrocyte alpha-tocopherol levels were significantly decreased in both patients. It seems conceivable that membrane alterations due to the low level of these reducing agents may contribute to the shortened life span of erythrocytes. The imbalance of the prooxidant/antioxidant homeostasis as well as the increased rate of methylglyoxal formation may also have been involved in the development of the neurological manifestations in the propositus.     

Extracorporeal lithotripsy of pancreatic stones in patients with chronic pancreatitis and pain: a prospective follow up study.

Extracorporeal shock wave lithotripsy of pancreatic duct stones (largest stone 12 (SD) 6 mm) was performed in 24 patients with abdominal pain and a dilated duct system (main pancreatic duct 10 (3) mm). The procedure was well tolerated in all but two patients, who had a mild pancreatitic attack immediately after lithotripsy. Disintegration of the stones was achieved in 21 patients. This allowed complete clearance of the duct system by an endoscopic approach in 10 (42%) patients and partial clearance in 7 (29%) patients. Within a mean follow up period of 24 (14) months half of the patients showed complete or considerable relief of pain and alleviation of symptoms was achieved in seven patients. Relief of pain occurred more often after complete ductal clearance. There were no fatalities within the follow up period. These findings underline the value of a combined non-surgical approach, using endoscopy and adjuvant shock wave lithotripsy to patients with large pancreatic calculi and pain attacks.     

Semaphorin 6D regulates the late phase of CD4+ T cell primary immune responses

The semaphorin and plexin family of ligand and receptor proteins provides important axon guidance cues required for development. Recent studies have expanded the role of semaphorins and plexins in the regulation of cardiac, circulatory and immune system function. Within the immune system, semaphorins and plexins regulate cell–cell interactions through a complex network of receptor and ligand pairs. Immune cells at different stages of development often express multiple semaphorins and plexins, leading to multivariate interactions, involving more than one ligand and receptor within each functional group. Because of this complexity, the significance of semaphorin and plexin regulation on individual immune cell types has yet to be fully appreciated. In this work, we examined the regulation of T cells by semaphorin 6D. Both in vitro and in vivo T cell stimulation enhanced semaphorin 6D expression. However, semaphorin 6D was only expressed by a majority of T cells during the late phases of activation. Consequently, the targeted disruption of semaphorin 6D receptor–ligand interactions inhibited T cell proliferation at late but not early phases of activation. This proliferation defect was associated with reduced linker of activated T cells protein phosphorylation, which may reflect semaphorin 6D regulation of c-Abl kinase activity. Semaphorin 6D disruption also inhibited expression of CD127, which is required during the multiphase antigen-presenting cell and T cell interactions leading to selection of long-lived lymphocytes. This work reveals a role for semaphorin 6D as a regulator of the late phase of primary immune responses.     

Validation of data from electronic data warehouse in diabetic ketoacidosis: Caution is needed

Aims

This study validated enterprise data warehouse (EDW) data for a cohort of hospitalized patients with a primary diagnosis of diabetic ketoacidosis (DKA).