Reducing errors in the accident department: a simple method using radiographers.

The assessments by radiographers of 1628 consecutive patients referred for radiography in the casualty department were analysed. The radiographers missed abnormalities in the radiographs in 68 of the cases. Casualty officers missed abnormalities in 63 cases, but only 35 patients were common to both groups. Twenty eight of the radiographs interpreted wrongly by casualty officers were interpreted correctly by radiographers; 16 of these 28 were thought by the accident and emergency consultant to be clinically important. It is suggested that a system whereby radiographers signal abnormalities should be standard practice.     

Myocardial S-adenosylhomocysteine hydrolase is important for adenosine production during normoxia

(1) The coronary vasodilator adenosine can be formed in the heart by breakdown of AMP or S-adenosylhomocysteine (SAdoHcy). The purpose of this study was to get insight into the relative importance of these routes of adenosine formation in both the normoxic and the ischemic heart. (2) A novel HPLC method was used to determine myocardial adenosine and SAdoHcy. Accumulation of SAdoHcy was induced in isolated rat hearts by perfusion with L-homocysteine thiolactone or L-homocysteine. The release of adenosine, inosine, hypoxanthine, xanthine and uric acid was determined. Additional in vitro experiments were performed to determine the kinteic parameters of S-adenosylhomocysteine hydrolase. (3) During normoxia the thiolactone caused a concentration-dependent increase in SAdoHcy. At 2000 μM of the thiolactone an SAdoHcy accumulation of 0.49 nmol/min per g wet weight was found during normoxia. L-Homocysteine (200 μM) caused an increased of 0.37 and 4.17 nmol SAdony/soc per g wet weight during normaxia and ischemia, respectively. (4) The adenosine concentration in ischemic hearts was significantly lower when homocysteine was infused (6.2 vs. 115 nmol/g; P < 0.05). Purine release was increased 4-fold during ischemia. (5) The K_m for hydrolysis of SAdoHcy was about 12 μM. At in vitro conditions favoring near-maximal SAdoHcy synthesis (72 μM adenosine, 1.8 mM homocysteine), the synthesis rate in homogenates was 10 nmol/min per g wet weight. (6) From the combined in vitro and perfusion studies, we comclude that S-adenosylhomocysteine hydrolase can contribute significantly to adenosine production in normoxic rat heart, but not during ischemia.     

Evidence for a rate-limiting role of cysteinesulfinate decarboxylase activity in taurine biosynthesis in vivo

The relationship between activities of enzymes involved in cysteine oxidation and the apparent conversion of cysteine to taurine in vivo were investigated in the rat and cat. Both hepatic cysteinesulfinate decarboxylase activity and the oxidation in vivo of cysteine to taurine were lower in the kitten than in the adult female rat and lower in the latter than in the young male rat. Our data support the hypothesis that cysteinesulfinate decarboxylase plays a rate-limiting role in taurine biosynthesis.     

Variants within the yeast Ty sequence family encode a class of structurally conserved proteins.

The Ty transposable elements of Saccharomyces cerevisiae form a heterogeneous family within which two broad structural classes (I and II) exist. The two classes differ by two large substitutions and many restriction sites. We show that, like class I elements a class II element, Tyl-17, also appears to contain at least two major protein coding regions, designated TYA and TYB, and the organisational relationship of these regions has been conserved. The TYA genes of both classes encode proteins, designated p1 proteins, with an approximate molecular weight of 50 Kd and, despite considerable variation between the TYA regions at the DNA level, the structures of these proteins are remarkably similar. These observations strongly suggest that the p1 proteins of Ty elements are functionally significant and that they have been subject to selection.     

Cytologic demonstration of differential activity of rRNA gene clusters in different human tissues

Summary rRNA gene activity was evaluated by cytologic methods in cultured human cells from two different tissues grown under controlled experimental conditions. The modal and average numbers of silver positive nucleolus organizers (NOs) per cell as well as the distribution of cells with different numbers of silver positive NOs and different combinations of D-plus G-group silver stained chromosomes, were evaluated. Statistically significant differences in the average number of silver positive NOs per cell between leukocytes and fibroblasts grown under standard experimental conditions have been demonstrated. The observed differences became sharper in cells cultured under more restrictive conditions. Also, differences in the frequency of silver positivity of specific chromosomal NOs located on individually indentified chromosomes were observed in cells from the same tissue. Furthermore, differences in the frequency of activation of rDNA clusters located on the same chromosome were also observed between cells from the two tissues. The possible biologic meanings of these findings are discussed.This paper is dedicated to Professor G. Montalenti on the occasion of his 80th birthday     

Lysosomal hydrolase activity in chorionic villi and embryonic cells in culture

Summary Fourteen lysosomal enzymes were compared in 20 cultured cell lines from chorionic biopsy and corresponding embryonic tissue after voluntary abortions. Enzymatic expression appears to be similar in cultured cells from both sources with some slightly higher levels for chorionic villi. We stress the importance of culturing chorionic villi especially in the case of enzymes (-L-iduronidase) or diseases (I cell disease) whose expression is unusual in fresh trophoblast tissue.     

Isolation of microorganisms on 3-butyn-1-ol and other acetylenic compounds

The microbial potential to degrade acetylenic compounds (alkynes) was investigated, and several fungi and bacteria were isolated on 2-propyn-1-ol, 3-butyn-1-ol, propynoic acid, and 2-butyne-1,4-diol. The results indicate that a wide variety of microorganisms may degrade alkynes in nature.     

Repair of damage in double-stranded phi X174 (RF) DNA due to radiation-induced water radicals

Experiments in which the yields of radiation-induced OH and H radicals were varied, showed that both types of water radicals inactivate phi X174 RF DNA to about the same extent as measured by transfection of the (irradiated) DNA to E. coli wild-type spheroplasts. On the other hand, using spheroplasts prepared from E. coli strains, deficient in one of the proteins involved in excision DNA repair (uvrA- or uvrC-) or in post-replication repair (recA-), clear differences between damage originating from OH or H radical attack were found. Part of the radiation damage due to H radicals appeared to be repairable by an uvrA-gene-dependent repair mechanism, whereas this repair pathway does not play an important role in the case of OH radical damage. The reverse applies to uvrC-gene-dependent repair, which only affects OH radical damage (obtained under anoxic conditions), but has no influence on damage due to H radicals. Irradiation of double-stranded phi X174 (RF) DNA in the presence of oxygen however, yields damage--due to OH radicals only--which appeared not to be sensitive to either uvrC- or uvrA-gene-dependent repair. Furthermore, post-replication repair (recA) has only very little effect on the amount of inactivation by H or OH radicals, when irradiation is carried out under anoxic conditions. We did not find significant inactivation due to hydrated electrons, whether the biological activity was determined by use of wild-type spheroplasts or of strains deficient in excision or post-replication repair proteins.