Extended apical enlargement with hand files versus rotary NiTi files. Part II.

OBJECTIVE: The objective of this study was to compare 2 preparation techniques performed under simulated clinical conditions with extended apical enlargement following determination of the optimal apical preparation size (APS). STUDY DESIGN: After preflaring 240 root canals, APS was evaluated as outlined in Part I. The apical portion was shaped to APS either with rotary NiTi Lightspeed instruments (LS) or NiTi hand instruments (HA) using the balanced force technique in a phantom head. After sectioning the apical area at 3 levels, every cross section was analyzed microscopically for circumferential removal of canal wall dentine. Loss of working length, instrument separation, and perforation were additionally recorded. RESULTS: In 70% (LS) and 69% (HA) of the root canals, 2 of 3 levels demonstrated that the root canal dentin was cut circumferentially. Neither loss of working length nor perforation occurred in both groups. Four LS instruments separated. CONCLUSIONS: APS frequently results in a nearly complete apical preparation regardless of the preparation techniques. In a few cases apical enlargement to APS does not achieve complete cutting of the canal walls. There was a rather slight risk of serious procedural errors.     

Splenic abscess and peritonitis in a continuous ambulatory peritoneal dialysis (CAPD) patient

A 26-year-old female was on continuous ambulatory peritoneal dialysis (CAPD) because of diabetic end-stage renal failure. She developed an acute peritonitis that relapsed repeatedly despite appropriate antibiotic treatment. Investigations showed the presence of a splenic abscess, and splenectomy and peritoneal cannula removal were required. The patient died of myocardial infarction two weeks postoperatively. This is the first recorded case of peritonitis secondary to splenic abscess in a CAPD patient. Autopsy findings suggest that the abscess developed from infection of a splenic infarct.     

Diagnostic significance of anti-HBcIgM prevalence related to symptoms in Canadian patients acutely or chronically infected with hepatitis B virus

A total of 362 sera from 295 Canadian patients were examined for HBsAg, anti-HBs, anti-HBc, anti-HBcIgM, HBeAg, and anti-HBe using commercial immunoassays. Serial samples from 70 acutely infected patients demonstrated that anti-HBcIgM may detect 10% more positives than HBsAg within 4 months after the onset of clinical symptoms, and all except two were negative for anti-HBcIgM after the fourth month. None of 66 asymptomatic (HBeAg rate 18.2%) and two of 14 (14.3%) symptomatic (HBeAg rate 64.3%) carriers of HBsAg were positive for anti-HBcIgM (P = 0.029). Elevated marker responses were measured in two symptomatic carriers for a 20-month period. Anti-HBcIgM was not detected in either 100 asymptomatic patients positive for total anti-HBc, negative for HBsAg and negative for or possessing low levels of anti-HBs, 25 patients with liver disorders not caused by HBV, or 20 healthy milk donors. In diagnostic laboratory practice this anti-HBcIgM test may be useful in the following situations: to supplement HBsAg testing, providing a theoretical 10% increase in positives within 4 months following onset of acute viral hepatitis; to replace testing for anti-HBc and anti-HBs in symptomatic HBsAg-negative patients; to confirm whether a patient is experiencing acute or chronic HBV infection or symptoms superimposed upon asymptomatic HBsAg carriage by another cause, such as nonA-nonB viral hepatitis.     

Development and application of a nonradioactive nucleic acid hybridization system for simultaneous detection of four potato pathogens

cDNA clones of potato virus X (PVXcp strain), potato virus Y (PVYo strain), potato leaf roll virus (PLRV) and potato spindle tuber viroid (PSTV) were used separately or combined for the detection of the corresponding RNAs in extracts of infected plants. A general method for the rapid preparation of RNA extracts without use of organic solvents (i.e. phenol) was developed for this purpose. Plant extracts from a range of field, artificially inoculated germplasm genotypes, micro-propagated and protoplast samples, as well as vector insect extracts, were dot-blotted onto nylon or nitrocellulose membranes, subjected to sandwich nucleic acid hybridization with non-labelled specific single-stranded DNA probes followed by a biotin-labelled second step hybridization probe. Each probe was virus-specific but not strain-specific. Healthy or non-related plant extracts developed very faint or no signals. Sensitivity was tested by slot-blot hybridization. Detection levels were between 1.5 to 6 pg of viral nucleic acids and between 20 to 50 times more sensitive than standard double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The assay developed was tested with material that was prepared for processing in the field (combination of fresh sap with extraction solution) and tested under simple laboratory conditions for detection. It was also successfully employed for screening of germplasm for virus resistance, detection of pathogens in vector insects, plantlets grown in vitro and in more sophisticated quantitative determinations of viral replication in artificially inoculated plants and protoplasts.     

The effect of 12-O-tetradecanoylphorbol-13-acetate on hormone-induced differentiation of rat parotid gland in organ culture

Parotid glands of 5-day-old rats were maintained in DM-153 synthetic, serum-free medium in organ culture for 24 to 48 hr. Differentiation of acinar cells in vitro, as revealed by an increase in amylase activity in the gland and in the culture fluid, as well as by the immunocytochemical demonstration of amylase in the acinar cells, was accelerated by insulin, prednisolone, and l-thyroxine added to the culture medium. The potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (10^?7M) inhibited both the unstimulated and hormone-stimulated differentiation of the gland without causing cellular degeneration or necrosis.     

Occurrence of hlyA and sheA genes in extraintestinal Escherichia coli strains

The association of a hemolytic phenotype with the carriage of the alpha-hemolysin gene (hlyA) and/or the silent hemolysin gene (sheA or clyA) among 540 extraintestinal clinical isolates of Escherichia coli and 110 fecal isolates from healthy individuals was investigated. Though HlyA is an important virulence factor in extraintestinal E. coli infection, the role of SheA is not completely clarified. Two hemolytic sheA+ E. coli strains that lacked hlyA and possessed no other hemolysin genes were identified. No hlyA+ sheA+ strains were identified, suggesting that there is possible incompatibility between hlyA and sheA in the chromosome of E. coli.     

Effects of exercise cessation on lipids and lipoproteins in distance runners and power athletes

Summary The purpose of this study was to determine the effects of short-term exercise cessation on lipid and lipoprotein profile and insulin sensitivity in highly trained runners (n=12; mean age 19.9 years) and power athletes (n=12; mean age 24.4 years). Following 14 days of exercise cessation, running time to exhaustion and maximal oxygen uptake decreased by 9.2% and 4.8% (P < 0.05) in the runners, while in the power athletes one repetition maximum squat and bench press did not change (P>0.05). No changes occurred in body composition. Data from a 2-h oral glucose tolerance test revealed an impairment of the glycemic state in all athletes (P<0.05). In contrast, exercise cessation did not significantly (P>0.05) alter plasma levels of cholesterol, triglycerides, and low density (LDL) and high density lipoprotein (HDL). No changes were observed in HDL₂, HDL_2b, and HDL₃ subfractions, LDL diameter, and qualitative LDL pattern (P>0.05). These data thus suggest that despite a decrease in insulin sensitivity, short-term exercise cessation, independent of exercise mode, was insufficient to alter plasma lipid and lipoprotein profiles in well-trained athletes.     

Zonal distribution of glomerular collapse in renal allografts: possible role of vascular changes

Collapsing glomerulopathy (CG), an aggressive variant of focal segmental glomerular sclerosis, is a renal disease with severe proteinuria and rapidly progressive renal failure. The pathogenesis of CG is unknown. It strongly resembles human immunodeficiency virus (HIV)-associated nephropathy, but the patients are HIV negative. The characteristic glomerular lesion is capillary loop collapse with prominent podocytes filling Bowman's space. Interestingly, these glomerular changes are usually associated with severe tubulointerstitial injury, including tubular epithelial degenerative changes, microcystic dilation of several tubules, and interstitial inflammatory cell infiltrate. Recently, it became evident that the morphologic pattern of CG may appear not only in native kidneys, but also de novo in renal allografts, and that the pattern of CG in renal transplants is not always associated with severe proteinuria. Studies describing CG in renal allografts are all based on biopsies. We report 3 allograft nephrectomy specimens that showed a zonal distribution of the characteristic collapsing glomerular changes with associated tubulointerstitial injury. All 3 kidneys had obliterative vascular changes. One nephrectomy specimen had chronic obliterative transplant arteriopathy, 1 had acute vascular rejection, and 1 had thrombotic microangiopathy. None of the patients had severe proteinuria. Our cases suggest that the morphologic pattern of CG in renal allografts may not represent the same disease process as CG in native kidneys and provide further evidence that collapsing glomerular changes do not define the disease entity of CG, but rather represent a pattern of renal injury. Among other factors, hemodynamic disturbance may play a role in the development of the pattern of CG in renal allografts.     

The effects of 5-bromodeoxyuridine and isoproterenol on the postnatal differentiation of rat submandibular gland

The effects of 5-bromodeoxyuridine (BrdU) on the postnatal differentiation of rat submandibular gland and on the isoproterenol-induced changes of differentiation were studied. The rats were injected with BrdU for three consecutive days, beginning at two days of age. The total dose of BrdU was 0.9 mg/g body weight. BrdU caused a severe retardation of growth up to 15 days of age. A rapid growth of the animals between 15 and 22 days indicated a recovery from the effect of BrdU. The growth of the submandibular gland was retarded similarly with a corresponding decrease in DNA, RNA and protein content. Incorporation of tritiated thymidine into the submandibular gland was not altered in the BrdU-treated animals at one and three days after the last injection of the analog. At days 15 and 22 the rate of thymidine incorporation was greater in the submandibular gland of BrdU-treated rats as compared to littermate controls. Isoproterenol stimulated thymidine incorporation into the submandibular glands of two-week-old rats. This stimulation was not observed in rats which received BrdU at age 7–9 days, prior to the administration of isoproterenol. Electron microscopic observations, including a quantitative analysis of the frequency distribution of the various cell types in the terminal tubules and developing acini, indicated a retardation of acinar cell differentiation in the glands of BrdU-treated rats. In addition, there was an increase in the number and size of the secretory granules in the terminal tubule cells. BrdU treatment, however, caused no obvious pathologic alterations in the submandibular gland. Administration of isoproterenol for five days, beginning at five days of age, caused an apparent acceleration of the differentiation of acinar cells. In the glands of isoproterenol-treated rats the acinar cells were enlarged and were filled with homogenous secretory granules. Pretreatment with BrdU partially inhibited the effects of isoproterenol on differentiation and hypertrophy of the submandibular gland. With the given dose of BrdU, approximately 5% of thymine was replaced by bromouracil in the DNA of the submandibular gland. Such a replacement would be consistent with a direct effect of BrdU on the cytodifferentiation in the submandibular gland. However, because of the severe retardation of growth of the BrdU-treated rats, indirect effects can not be excluded.