Organization of human histone genes.

We describe the isolation and initial characterization of seven independent lambda Charon 4A recombinant phages which contain human histone genomic sequences (designated lambda HHG). Restriction maps of these clones and localization of the genes coding for histones H2A, H2B, H3, and H4 are presented. The presence of histone encoding regions in the lambda HHG clones was demonstrated by several independent criteria including hybridization with specific DNA probes, hybrid selection/in vitro translation, and hybridization of lambda HHG DNAs to reserve Southern blots containing cytoplasmic RNAs from G1-, S-, and arabinofuranosylcytosine (cytosine arabinoside)-treated S-phase cells. In addition, the lambda HHG DNAs were shown to protect in vivo labeled H4 mRNAs from S1 nuclease digestion. Based on the analysis of the lambda HHG clones, human histone genes appear to be clustered in the genome. However, gene clusters do not seem to be present in identical tandem repeats. The lambda HHG clones described in this report fall into at least three distinct types of arrangement. One of these arrangements contains two coding regions for each of the histones H3 and H4. The arrangement of histone genes in the human genome, therefore, appears to be different from that in the sea urchin and Drosophila genomes in which each of the five histone-encoding regions (H1, H2A, H2B, H3, and H4) is present only once in each tandemly repeated cluster. At least one clone, lambda HHG 41, contains, in addition to the histone genes, a region that hybridizes with a cytoplasmic RNA approximately 330 nucleotides in length. This RNA is not similar in size to known histone-encoding RNAs and is present in the cytoplasm of HeLa cells predominantly in the G1 phase of the cell cycle.     

An alternative method of wound pain control following hepatic resection: a preliminary study

BackgroundEpidural analgesia is considered one of the optimal methods for provision of postoperative pain relief in patients recovering from major upper abdominal operations. Concerns regarding the potential risk of neurological complications prompted an evaluation of an alternative strategy using a continuous intermuscular bupivacaine (CIB) infusion combined with patient-controlled analgesia (PCA).MethodsTwo fine-bore catheters are inserted in the deep intermuscular intercostal neuronal plane during abdominal wound closure, and a continuous infusion of bupivacaine 0.25% is commenced for 72 h postoperatively. Simultaneously, patient-controlled analgesia provided intravenous morphine on demand. The study comprised 10 consecutive patients undergoing liver resection in whom CIB infusion and PCA were employed. The feasibility, safety and efficacy of the technique were investigated, analysing postoperative pain scores, morphine requirements, spirometry and oxygen saturation.ResultsThere were no postoperative deaths. Postoperative morbidity included one urinary tract infection, one minor chest infection and acute confusional episodes in two patients. Median pain scores and morphine requirements at 12, 24, 48 and 72 h postoperatively were satisfactory. Spirometry and oxygen saturation values also remained within the normal range.DiscussionPreliminary experience with CIB infusion/PCA in the aftermath of major liver resection has demonstrated its simplicity and safety as an alternative method of postoperative pain control. Further study is required to investigate the role of CIB infusion/PCA as a practical alternative to epidural analgesia or PCA alone.     

Relationship of frequent postinfarction premature ventricular complexes to the reentry circuit of scar-related ventricular tachycardia.

BACKGROUND: Postinfarction reentrant ventricular tachycardia (VT) is usually scar-related. However, the sites of origin of premature ventricular complexes (PVCs) in the setting of healed myocardial infarction have not been well characterized. OBJECTIVE: The purpose of this study was to determine the site of origin of frequent PVCs in postinfarction patients with VT and to determine the relationship to VT exit sites. METHODS: Mapping and catheter ablation were performed in 13 consecutive patients (12 men, mean age 62 +/- 8 years, mean ejection fraction 0.32 +/- 0.12) with prior myocardial infarction, sustained monomorphic VT, and >10 PVCs/h. The mean PVC burden was 12% +/- 11% on a 24-hour Holter monitor. Electroanatomical left ventricular voltage maps were constructed during sinus rhythm to identify scars. Endocardial activation maps of the PVCs were correlated with the voltage maps, and the most prevalent PVCs were ablated. The effect of PVC ablation on the inducibility of VT was determined. RESULTS: Seventeen sustained monomorphic VTs were reproducibly inducible. There were a total of 34 different PVC morphologies. The site of origin was identified for 18 of the 34 PVC morphologies in 12 of 13 patients. The 18 PVCs for which the site of origin could be identified accounted for 89% of the PVC burden in these patients. The site of PVC origin was in the infarct scar in 11 patients, the border zone in 1 patient, and unidentifiable in 1 patient. The site of PVC origin corresponded to the VT exit site for 14 of 17 reproducibly inducible VTs. The PVCs that were successfully mapped were ablated, and this rendered VT no longer inducible. CONCLUSION: Postinfarction PVCs usually arise from the infarct scar, and their site of origin often corresponds to the exit site of a reentrant VT. Therefore, catheter ablation of the PVCs often is associated with the loss of inducible VT.     

The role of allogeneic bone marrow transplantation in adult patients below the age of 55 years with acute lymphoblastic leukemia in first complete remission: a donor vs no donor comparison

The role of allogeneic bone marrow transplantation (alloBMT) in adults with acute lymphoblastic leukemia (ALL) in first complete remission (CR1) remains controversial. At our institution, the policy is to offer alloBMT to ALL patients in CR1 up to the age of 55 years if a related donor is available. In addition, unrelated donor transplants are offered to patients with Philadelphia (Ph+) ALL. We report the results on 92 patients with ALL treated according to this policy from September 1992 to October 2001. Of the 87 patients achieving CR1, the comparison of patients with (n=48) or without donors (n=39) was done using an intention-to-treat approach. Of the 48 patients with donors (39 related and nine unrelated), 35 (73%) received alloBMT in CR1. No significant difference in 3-year event-free survival (EFS) (40 vs 39%, P=0.74) or overall survival (OS) (46 vs 58%, P=0.41) was seen in 'donor' vs 'no-donor' groups. For Ph+ patients, 3-year EFS and OS in 'donor' group were 46 and 57%, respectively, none of the patients in 'no-donor' group survived beyond 3 years. With our treatment strategy, 3-year OS of Ph+ patients was equivalent to Ph-negative (Ph-) patients (51 vs 52%, P=0.77). In conclusion, our data show that the policy of performing alloBMT if a sibling donor is available has not resulted in better outcome in Ph- patients.     

Atrial tachycardia after circumferential pulmonary vein ablation of atrial fibrillation: mechanistic insights, results of catheter ablation, and risk factors for recurrence.

OBJECTIVES: The aim of this study was to determine the mechanism of atrial tachycardia (AT) that occurs after ablation of atrial fibrillation (AF). BACKGROUND: Patients who undergo catheter ablation of AF may develop AT during follow-up. METHODS: Seventy-eight patients underwent an ablation procedure for AT after circumferential pulmonary vein ablation (CPVA) for AF. The 3-dimensional maps from the AF and AT procedures were compared to determine whether AT arose from a prior ablation line. RESULTS: A total of 155 ATs were mapped, and the mechanism was re-entry in 137 (88%) and focal in 18 (12%). The most common left atrial (LA) ablation targets were the mitral isthmus, roof, and septum. The critical isthmus in 115 of the 120 LA re-entrant ATs (96%) traversed a prior ablation line, consistent with a gap-related mechanism. Catheter ablation was successful in 66 of the 78 patients (85%). After a mean follow-up of 13 +/- 10 months, 60 of the 78 patients (77%) were free of AT/AF without antiarrhythmic medications. Re-entrant septal AT was associated with recurrence (odds ratio 7.3; 95% confidence interval 1.5 to 36; p = 0.02), whereas PV isolation during the AT procedure was associated with a favorable outcome (odds ratio 0.17; 95% confidence interval 0.04 to 0.81; p = 0.03). CONCLUSIONS: Approximately 90% of ATs after CPVA are re-entrant, and nearly all are related to gaps in prior ablation lines. These findings suggest that the prevalence of these arrhythmias may be reduced by limiting the number of linear lesions, demonstration of linear block, and pulmonary vein disconnection during the initial AF procedure.     

Mortality in sickle cell patients on hydroxyurea therapy

The efficacy of hydroxyurea (HU) and its role in the reduction in mortality in sickle cell patients has been established. Nevertheless, many patients still die of complications of this disease while on HU. Of the 226 patients treated with HU at our center, 38 died (34 of sickle cell-related causes). Acute chest syndrome (ACS) was the most common (35%) cause of death. Deceased and surviving patients did not differ significantly in average HU dose, baseline fetal hemoglobin (Hb F), or maximum Hb F response. However, the deceased patients were significantly older when HU was instituted, were more anemic, and more likely to have BAN or CAM haplotypes. They also had significantly higher serum blood-urea-nitrogen (BUN) and creatinine levels. Sickle cell patients who die while on HU therapy may represent a subgroup of older patients, possibly with more severe disease and more severe organ damage. Such patients need early identification and prompt HU institution.     

Survival and growth of Shigella flexneri,Salmonella enterica serovar enteritidis,and Vibrio cholerae O1 in reconstituted infant formula

Formula feeding is an alternative method to prevent mother-to-child infection with human immunodeficiency virus through breast-feeding in developing countries. Growth of bacterial pathogens in reconstituted infant formula has become a health hazard when contaminated water is used for rehydration. This study was conducted to assess bacterial safety risk of using contaminated water to reconstitute infant formula. Survival and growth characteristics were determined for three bacterial pathogens, Vibrio cholerae O1, Shigella flexneri, and Salmonella enterica serovar Enteritidis, inoculated into sterile tap water (3.2-3.4 log10 colony-forming units [CFU]/ml) and infant formula (1.5-1.7 and 3.2-3.4 log10 CFU/ml) and incubated at 4 degrees C or 30 degrees C for up to 24 hours. Vibrio cholerae O1 was the most sensitive of the three pathogens when inoculated into water, with no viable cells detected within 2 hours at 4 degrees C or 30 degrees C. The rate of inactivation in water was greater at 30 degrees C than at 4 degrees C. Vibrio cholerae O1, Shigella flexneri, and Salmonella enterica serovar Enteritidis grew rapidly in infant formula at 30 degrees C, reaching populations of 9.2, 8.7, and 9.2 log10 CFU/ml, respectively, at 24 hours. Populations of all three pathogens did not change significantly after incubating infant formula for 24 hours at 4 degrees C, but continuously decreased in water throughout incubation for 24 hours, regardless of temperature. Results suggest that unless refrigerated, reconstituted infant formula should be consumed soon after preparation to avoid increased risk of illness associated with increases in populations of pathogenic bacteria that may be introduced by contaminated water.