Reversible signal abnormalities in the hippocampus and neocortex after prolonged seizures

PURPOSE: To investigate the phenomenon of reversible increased signal intensity of medial temporal lobe structures and cerebral neocortex seen on MR images of six patients with recent prolonged seizure activity. METHODS: After excluding patients with known causes of reversible signal abnormalities (such as hypertensive encephalopathy), we retrospectively reviewed the clinical findings and MR studies of six patients whose MR studies showed reversible signal abnormalities. MR pulse sequences included T2-weighted spin-echo coronal views or conventional short-tau inversion-recovery coronal images of the temporal lobes. RESULTS: All six MR studies showed increased signal intensity within the medial temporal lobe, including the hippocampus in five studies. All follow-up MR examinations showed partial or complete resolution of the hyperintensity within the medial temporal lobe and the neocortex. In one patient, results of a brain biopsy revealed severe cerebral cortical gliosis. Temporal lobectomy performed 4 years later showed moderate cortical gliosis and nonspecific hippocampal cell loss and gliosis. CONCLUSION: Significant hyperintensity within the temporal lobe is demonstrable on MR images after prolonged seizure activity, suggestive of seizure-induced edema or gliosis. Damage to medial temporal lobe structures by prolonged seizure activity indicates a possible mechanism of epileptogenic disorders.     

Mutator genes of the yeast Saccharomyces cerevisiae. Interaction of mutations him and his with mutations blocking three principal pathways of repair of induced DNA damage

During recent years, genes controlling mutation in higher eukaryotes have been found to be involved actively in carcinoma regeneration in cells. In this respect, studying the genetic control of mutagenesis becomes a key direction of research into mechanisms responsible for cancer generation. The results of studying interaction of mutations in the HIM and HSM genes, controlling spontaneous and induced mutagenesis in yeasts, and mutations impairing three known pathways of DNA damage repair in this microorganism, are described in this work. It was shown that mutation rev3 completely blocks UV-induced mutagenesis in all mutants studied. On the other hand, mutation rad2 synergistically interacts with mutations him1, hsm1, hsm3, hsm6, and hsm2, thus enhancing the frequency of UV-induced mutagenesis in double mutants multiple times. Mutations him2 and him3 manifested epistatic interaction with mutation rad2. With mutation rad54, the interaction was epistatic for mutations him1 and hsm2 and was additive for mutations hsm1, him2, and him3. On the basis of the data obtained, we developed a scheme for the appearance of mismatch bases in the process of repair of UV-induced DNA damage.     

Emergency fluid management for hypovolemia

Emergency fluid resuscitation of hypovolemic patients begins with an accurate assessment of the degree of volume depletion as well as identification of the cause and associated abnormalities. On the basis of this information, the proper resuscitative fluid can be chosen and administered by the appropriate route, as guided by the urgency of the situation. Patients with severe volume depletion and those in shock require intravenous fluids. In other situations, oral rehydration is often appropriate. Specific fluids then can be tailored to the individual patient's needs and adjusted as warranted by ongoing monitoring.     

Improvements in anaesthetic care resulting from a critical incident reporting programme

The r?le of an anaesthetic incident reporting programme in improving anaesthetic safety was studied. The programme had been running for 4 to 5 years in three large hospitals in Hong Kong and more than 1000 incidents have been reported. The number of reports being made and frequency of the various categories of incident reported, did not alter during the study period. Sixty nine percent of incidents were considered to be preventable. Human error contributed to 76% of incidents and violations of standard practice to 30% of incidents. The programme was effective in its ability to detect latent errors in the anaesthesia system and when these were corrected, incidents did not recur. The frequency with which various contributing factors were cited did not decrease with time. With the exception of problems dealt with by specific protocol development, the study found no evidence that an increasing awareness of the problem of human error was effective in reducing this kind of problem.     

McrBs, a modulator peptide for McrBC activity

McrBC is a methylation-dependent endonuclease from Escherichia coli K-12. The enzyme recognizes DNA with modified cytosines preceded by a purine. McrBC restricts DNA that contains at least two methylated recognition sites separated by 40-80 bp. Two gene products, McrBL and McrBs, are produced from the mcrB gene and one, McrC, from the mcrC gene. DNA cleavage in vitro requires McrBL, McrC, GTP and Mg2+. We found that DNA cleavage was optimal at a ratio of 3-5 McrBL per molecule of McrC, suggesting that formation of a multisubunit complex with several molecules of McrBL is required for cleavage. To understand the role of McrBs, we have purified the protein and analyzed its role in vitro. At the optimal ratio of 3-5 McrBL per molecule of McrC, McrBs acted as an inhibitor of DNA cleavage. Inhibition was due to sequestration of McrC and required the presence of GTP, suggesting that the interaction is GTP dependent. If McrC was in excess, a condition resulting in suboptimal DNA cleavage, addition of McrBs enhanced DNA cleavage, presumably due to sequestration of excess McrC. We suggest that the role of McrBs is to modulate McrBC activity by binding to McrC.     

Nitrofurantoin prophylaxis for bacteriuria and urinary tract infection in children with neurogenic bladder on intermittent catheterization

OBJECT: This study was undertaken to determine the efficacy of preoperative erythropoietin administration in infants scheduled for craniofacial surgery and, in so doing, to minimize problems associated with blood transfusions. METHODS: Families were offered the option of having their children receive erythropoietin injections before undergoing craniofacial surgery. The children whose families accepted this option received daily iron and 300 U/kg erythropoietin three times per week for 3 weeks preoperatively. Weekly complete blood counts with reticulocyte counts were measured and transfusion requirements were noted. Blood transfusions were administered depending on the clinical condition of the child. A case-matched control population was also evaluated to compare initial hematocrit levels and transfusion requirements. Thirty patients in the erythropoietin treatment group and 30 control patients were evaluated. The dose of erythropoietin administered was shown to increase hematocrit levels from 35.4 +/- 0.9% to 43.3 +/- 0.9% during the course of therapy. The resulting hematocrit levels in patients treated with erythropoietin at the time of surgery were higher compared with baseline hematocrit levels obtained in control patients at the time of surgery (34.2 +/- 0.5%). Transfusion requirements also differed: all control patients received transfusions, whereas 64% (19 of 30) of erythropoietin-treated patients received transfusions. CONCLUSIONS: The authors conclude that treatment with erythropoietin in otherwise healthy young children will increase hematocrit levels and modify transfusion requirements. Erythropoietin therapy for elective surgery in children of this age must be individualized according to the clinical situation, family and physician beliefs, and cost effectiveness, as evaluated at the individual center.