A large collar increases neck resorption in total hip replacement:204 hips evaluated during 5 years

We evaluated the effect of a prosthetic collar on the proximal femoral bone in 204 hips without any signs of loosening after 5 years. The patients were operated on at 5 centers, using different prosthetic designs, but the same cementing technique. Resorption was more often found in cases with a true and large collar (Lubinus, HD2, Scanhip) than in cases with a flanged or tapered stem (Chamley, Exeter). The resorption was also more pronounced with the former designs. It was concluded that, in spite of theoretical advantages, a large collar is not only unnecessary but may also have negative long-term effects.     

Development of host plasma cells during graft-versus-host reactions in mice

Graft-versus-host (GVH) reactions induced by thymus or spleen cells in newborn mice were found to trigger the development of plasma cells in the medullary areas of lymph nodes. No germinal centers were found. The plasma cells were found from the fourth day of the GVH reactions and increased in numbers over the next few days. On the 14th day the plasma cells were still present, although in lower numbers. Results of immunodiffusion experiments indicated that during GVH reactions induced by spleen cells, donor as well as host plasma cells develop. In contrast, induction of GVH reactions by thymus cells leads to the development of plasma cells, which probably originate exclusively from the host. Positive Coombs' reactions were detected 15–20 days after induction of GVH reactions and host immunoglobulins were found to contribute to the Coombs' positivity. The GVH reactions stimulated the formation of antibodies to sheep erythrocytes. This effect was more marked on 7 S than on 19 S antibody production.     

Tailoring Antireflux Surgery: A Randomized Clinical Trial

A hypothesis has been formulated that mandates the adjustment of antireflux surgery to either a total or a partial wrap depending on the motor function of the esophagus to avoid dysphagia and other obstructive complaints. This hypothesis has been tested in a randomized, clinical trial where 106 chronic gastroesophageal reflux patients were allocated to either a total Nissen-Rossetti (n= 53) or a Toupet partial posterior (n= 53) fundoplication, irrespective of their preoperative esophageal motor function. All patients were followed at least 3 years, during which time none had a relapse of moderate to severe reflux symptoms. Motor dysfunctions defined as peristaltic amplitude ≤ 30 mmHg in the distal third and failed primary peristalsis with or without > 20% simultaneous contractions were noted in 67 patients preoperatively, but these patients did not have a specific symptom profile (e.g., dominated by obstructive symptoms) nor did seven patients with “aperistaltic esophagus.” The incidence of dysphagia decreased from 20% preoperatively to 8% (mild) at 3 years after the operation with no difference between the surgical procedures. We were unable to demonstrate a relation between preoperative manometric findings and postoperative symptoms when assessed in the total group or when subdivided by the type of fundoplication (r < 0.3). Flatulence occurred more frequently among those with a total fundic wrap (p < 0.01). When patients representing motor dysfunction (see above) were specifically analyzed, we again observed no difference in outcome between those having a total or a partial fundic wrap. In conclusion, the concept of tailoring antireflux surgery based on the preoperative motor function of the esophagus in patients with chronic gastroesophageal reflux disease was not supported by the results of this clinical trial.     

QT correction using Bazett’s formula remains preferable in long QT syndrome type 1 and 2

BackgroundThe heart rate (HR) corrected QT interval (QTc) is crucial for diagnosis and risk stratification in the long QT syndrome (LQTS). Although its use has been questioned in some contexts, Bazett''s formula has been applied in most diagnostic and prognostic studies in LQTS patients. However, studies on which formula eliminates the inverse relation between QT and HR are lacking in LQTS patients.We therefore determined which QT correction formula is most appropriate in LQTS patients including the effect of beta blocker therapy and an evaluation of the agreement of the formulae when applying specific QTc limits for diagnostic and prognostic purposes.MethodsAutomated measurements from routine 12‐lead ECGs from 200 genetically confirmed LQTS patients from two Swedish regions were included (167 LQT1, 33 LQT2). QT correction was performed using the Bazett, Framingham, Fridericia, and Hodges formulae. Linear regression was used to compare the formulae in all patients, and before and after the initiation of beta blocking therapy in a subgroup (n = 44). Concordance analysis was performed for QTc ≥ 480 ms (diagnosis) and ≥500 ms (prognosis).ResultsThe median age was 32 years (range 0.1–78), 123 (62%) were female and 52 (26%) were children ≤16 years. Bazett''s formula was the only method resulting in a QTc without relation with HR. Initiation of beta blocking therapy did not alter the result. Concordance analyses showed clinically significant differences (Cohen''s kappa 0.629–0.469) for diagnosis and prognosis in individual patients.ConclusionBazett''s formula remains preferable for diagnosis and prognosis in LQT1 and 2 patients.     

Excision of misincorporated ribonucleotides in DNA by RNase H (type 2) and FEN-1 in cell-free extracts

Misincorporated ribonucleotides in DNA will cause DNA backbone distortion and may be targeted by DNA repair enzymes. Using double-stranded oligonucleotide probes containing a single ribose, we demonstrate a robust activity in human, yeast, and Escherichia coli cell-free extracts that nicks 5' of the ribose. The human and yeast extracts also make a subsequent cut 3' of the ribonucleotide releasing a ribonucleotide monophosphate. The resulting 1-nt gap is an ideal substrate for polymerase and ligase to complete a proposed repair sequence that effectively replaces the ribose with deoxyribose. Screening of yeast deletion mutant cells reveals that the initial nick is made by RNase H(35), a RNase H type 2 enzyme, and the second cut is made by Rad27p, the yeast homologue of human FEN-1 protein. RNase H type 2 enzymes are present in all kingdoms of life and are evolutionarily well conserved. We knocked out the corresponding rnhb gene in E. coli and show that extracts from this strain lack the nicking activity. Conversely, a highly purified archaeal RNase HII type 2 protein has a pronounced activity. To study substrate specificity, extracts were made from a yeast double mutant lacking the other main RNase H enzymes [RNase H1 and RNase H(70)], while maintaining RNase H(35). It was found that a single ribose is preferred as substrate over a stretch of riboses, further strengthening a proposed role of this enzyme in the repair of misincorporated ribonucleotides rather than (or in addition to) processing RNADNA hybrid molecules.