Mistakes. The nexus to growth and learning

Linear parameters of corpus callosum and submucosal structures (transparent septum, cupula, thalamus, pineal body and the third ventricle choroid plexus) were measured using 80 MR tomograms and 40 craniograms of 20 patients aged 20-50. Linear parameters were compared with the cranium shape and statistically processed. The dependence of linear parameters of the structures mentioned upon the shape of the cranium was demonstrated. They were characterized morphometrically in dolychomeso- and brachiocephals. The data obtained are of interest in assessment of MR tomograms with pathological changes and individualization of surgical interventions in median structures of brain.     

Early acquisition of homozygous deletions of p16/p19 during squamous cell carcinogenesis and genetic mosaicism in bladder cancer

We looked for p16/p19 deletion and p16 promoter methylation, as well as loss of 9p21 heterozygosity in pure squamous cell carcinomas (SCC), and in transitional cell carcinomas (TCC) of the bladder with SCC components. Homozygous deletion of p16/p19 was detected in 11 of 21 (52%) cases of pure SCCs and in three of ten (30%) cases of TCC with SCC. Three cases of TCC with SCC had p16/p19 deletion, hypermethylation of the p16 promoter, or LOH on 9p21 only in the SCC components, suggesting that these molecular alterations occurred preferentially in SCC. Interestingly, homozygous deletion of p16/p19 was observed in squamous metaplasia from bladder cancer patients (five of 11, 45%), showing that this change occurred in preneoplastic cells. On the other hand, p16/p19 deletions were not found in squamous metaplasias from non cancerous patients. Hypermethylation of the p16 promoter was observed in two of 14 tumors (14%) and none of seven metaplasias examined. These data suggest that: (a) p16/p19 deletion is associated with early carcinogenesis of SCC of the bladder, and squamous metaplasia of the bladder cancer patient has already sustained genetic changes found in cancer, and (b) genetic mosaicism occurs in cases of TCC with SCC, with the SCC component showing more frequent 9p21 alterations than the TCC component.     

Molecular dynamics investigation of the structure of a fully hydrated gel-phase dipalmitoylphosphatidylcholine bilayer

We report the results of a constant pressure and temperature molecular dynamics simulation of a gel-phase dipalmitoylphosphatidylcholine bilayer with nw = 11.8 water molecules/lipid at 19 degrees C. The results of the simulation were compared in detail with a variety of x-ray and neutron diffraction data. The average positions of specific carbon atoms along the bilayer normal and the interlamellar spacing and electron density profile were in very good agreement with neutron and x-ray diffraction results. The area per lipid and the details of the in-plane hydrocarbon chain structure were in excellent agreement with wide-angle x-ray diffraction results. The only significant deviation is that the chains met in a pleated arrangement at the bilayer center, although they should be parallel. Novel discoveries made in the present work include the observation of a bimodal headgroup orientational distribution. Furthermore, we found that there are a significant number of gauche conformations near the ends of the hydrocarbon chains and, in addition to verifying a previous suggestion that there is partial rotational ordering in the hydrocarbon chains, that the two chains in a given molecule are inequivalent with respect to rotations. Finally, we have investigated the lipid/water interface and found that the water penetrates beneath the headgroups, but not as far as the carbonyl groups, that the phosphates are strongly hydrated almost exclusively at the nonesterified oxygen atoms, and that the hydration of the ammonium groups is more diffuse, with some water molecules concentrated in the grooves between the methyl groups.     

Distribution and activation of intracellular Ca2+ stores in cultured olfactory bulb neurons

The presence and distribution of intracellular Ca2+ release pathways in olfactory bulb neurons were studied in dissociated cell cultures. Histochemical techniques and imaging of Ca2+ fluxes were used to identify two major intracellular Ca2+ release mechanisms: inositol 1, 4,5-triphosphate receptor (IP3R)-mediated release, and ryanodine receptor-mediated release. Cultured neurons were identified by immunocytochemistry for the neuron-specificmarker beta-tubulin III. Morphometric analyses and immunocytochemistry for glutamic acid-decarboxylase revealed a heterogeneous population of cultured neurons with phenotypes corresponding to both projection (mitral/tufted) and intrinsic (periglomerular/granule) neurons of the in vivo olfactory bulb. Immunocytochemistry for the IP3R, and labeling with fluorescent-tagged ryanodine, revealed that, irrespective of cell type, almost all cultured neurons express IP3R and ryanodine binding sites in both somata and dendrites. Functional imaging revealed that intracellular Ca2+ fluxes can be generated in the absence of external Ca2+, using agonists specific to each of the intracellular release pathways. Local pressure application of glutamate or quisqualate evoked Ca2+ fluxes in both somata and dendrites in nominally Ca2+ free extracellular solutions, suggesting the presence of IP3-dependent Ca2+ release. These fluxes were blocked by preincubation with thapsigargin and persisted in the presence of the glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Local application of caffeine, a ryanodine receptor agonist, also evoked intracellular Ca2+ fluxes in the absence of extracellular Ca2+. These Ca2+ fluxes were suppressed by preincubation with ryanodine. In all neurons, both IP3- and ryanodine-dependent release pathways coexisted, suggesting that they interact to modulate intracellular Ca2+ concentrations.     

ED2+ macrophages increase selectively myoblast proliferation in muscle cultures

We have previously shown by coculturing myoblasts and macrophages that myotube formation is strongly increased in vitro by the presence of an acid stable, heat-labile, soluble growth factor(s) secreted by macrophages. In this paper we obtained macrophages from peritoneal washing which also contained limited amounts of other cells such as lymphocytes and mesothelial cells. We here demonstrate that an ED2-positive (ED2+) macrophage subpopulation is responsible for myoblast enhanced proliferation. ED2+ macrophages were separated by a magnetic-activated cell sorter (MACS) using a monoclonal antibody against ED2, a membrane antigen peculiar to macrophages. Both ED2+ macrophages and their conditioned medium increased myotube formation when added to primary muscle cultures. Furthermore we demonstrate that muscle growth induced by macrophages is mainly the consequence of an increased myoblast proliferation by showing the presence of an increased number of MyoD-positive (MyoD+) myonuclei.     

Management of myocardial infarction: the proper priorities

We calculated the rates for perioperative mortality and fatal pulmonary embolism (PE) after primary total hip replacement in a single UK health region, using a regional arthroplasty register and the tracing service of the Office of National Statistics. During 1990, there were 2111 consecutive primary replacements in 2090 separate procedures. Within 42 days of operation a total of 19 patients had died (0.91%, 95% CI 0.55 to 1.42). Postmortem examination showed that four deaths (0.19%, 95% CI 0.05 to 0.49) were definitely due to PE. The overall perioperative mortality and fatal PE rates are low and in our study did not appear to be altered by the use of chemical thromboprophylaxis (perioperative mortality rate: one-tailed Fisher's exact test, p = 0.39; fatal PE rate: one-tailed Fisher's exact test, p = 0.56). The routine use of chemical thromboprophylaxis for primary THR is still controversial. The issue should be addressed by an appropriate randomised, prospective study using overall mortality and fatal PE rate as the main outcome measures, but the feasibility of such a study is questioned.     

The toxicology and prevention of the risks of occupational exposure to aromatic polycyclic hydrocarbons. I. Guide lines for the prevention of the risks of occupational exposure to aromatic polycyclic hydrocarbons. Società Italiana Valori di Riferimento and Cattedra di Medicina del Lavoro, Università di Brescia]

AIM: Patients with various disorders of gastric function were studied with radiolabeled test meals of different consistency to elaborate the effect of ingested media on gastric peristalsis and emptying. METHODS: In 12 patients parameters of gastric function were intraindividually compared after ingestion of a semiliquid and a solid test meal. In addition to the standard evaluation derived from time activity curves condensed images were established from two fixed time intervals (early and late period). These images were used to evaluate the amplitude and frequency of gastric contractions using Fourier analysis. RESULTS: As expected gastric emptying was influenced by the consistency of the test meal. Mean emptying rates for the solid meal were significant lower than those for the semiliquid one (p < 0.01). The amplitude and frequency of gastric contractions, however, did not depend on the consistency of the test meal. Within the course of the examination contraction amplitudes significantly increased (p < 0.05) from the early to the late period using both, solid as well as semiliquid test meals. The frequency of gastric contractions remained unchanged. CONCLUSION: As shown by an intraindividual data comparison amplitude and frequency of gastric contractions seem to be independent of the consistency of ingested test meals whereas gastric emptying is significantly influenced by the administered media. Semiliquid meals offer advantages with respect to the shorter examination time and simpler preparation and therefore may be preferred for routine use. Since amplitudes seem to vary within the observation period standardized acquisition protocols are recommended for the evaluation of this parameter.     

Effect of exposure of guinea pigs to cigarette smoke on elastolytic activity of pulmonary macrophages

STUDY OBJECTIVE: To determine the effect of exposure to cigarette smoke on the elastolytic activity of guinea pigs' alveolar macrophages (AMs), and to compare elastolytic activity of AMs obtained by BAL with that of lung macrophages (LMs) obtained from minced lung tissue. METHODS: AMs were obtained by BAL from seven adult guinea pigs exposed to cigarette smoke for 5 d/wk during 6 weeks, as well as from age-matched control guinea pigs. From each animal, one lung was used to obtain LMs by mincing and teasing the lung, followed by enzymatic digestion and isolation of mononuclear cells by Hypaque-Ficoll separation. The other lung was inflated and fixed to quantitate emphysema by the destructive index (DI). Elastolytic activity (microgram of elastin degraded by 10(6) macrophages) was determined at 24, 48, and 72 h, by culturing AMs and LMs (1 x 10(6) cells in 1 mL of medium) in 3H-elastin-coated wells. RESULTS: In animals exposed to cigarette smoke, the total number of BAL cells (8.6+/-2.1 x 10(6)) and DI (21.8+/-8.1) were significantly higher than in nonexposed animals (6.4+/-1.8 x 10(6), p<0.05 for cells, and 12.1+/-4.1, p<0.01 for DI). Elastolytic activity of AMs from smoke-exposed guinea pigs was significantly higher at 24, 48, and 72 h than elastolytic activity of AMs from control animals (19.0+/-9.4 vs 10.0+/-5.3, p<0.05 at 72 h). Likewise, elastolytic activity of LMs was significantly higher in exposed than nonexposed guinea pigs (11.8+/-7.7 vs 7.4+/-5.0 at 72 h, p<0.05). Elastolytic activity of LMs was not significantly different from elastolytic activity of AMs, both in exposed guinea pigs (11.8+/-7.7 vs 19.0+/-9.4 at 72 h) and nonexposed animals (7.4+/-5.0 vs 10.0+/-5.3 at 72 h). CONCLUSIONS: These results indicate that elastolytic activity of both AMs and LMs of guinea pigs increases significantly after exposure to cigarette smoke and that AMs and LMs have similar elastolytic activities.     

Epidemiology of acute hepatitis B in a university hospital in S?o Paulo, Brazil: retrospective study of two five-year periods

CONTEXT: HBV infection is endemic in Brazil and acute HBV infection is still a common disease. OBJECTIVE: To analyze incidence, risk factors and evolution of acute HBV infection. SETTING: University Hospital. PATIENTS: 357 patients with acute HBV infection, comparing two periods: 1985-1989 vs. 1990-1994. RESULTS: The overall incidence declined from 50 new cases/year in 1985-89 (30% of all cases) to 25 new cases/year in 1990-94 (8% of all cases). Transmission among male homosexuals (3.9% of cases in 85-89) declined to 1.3% in 90-94 (p > 0.05). Amongst health care workers (HCW) it declined from 8.2% to 2.0% (p = 0.02). Conversely, heterosexual transmission increased from 4.8% to 10.1% (p = 0.06). Chronification of HBV infection following the acute episode was observed in 1.7%. Fulminant hepatic failure was seen in 3.4%. However, 27.2% of patients were lost to follow-up before normalization of the biochemical tests. CONCLUSIONS: The different patterns of risk factors observed is probably related to measures for preventing AIDS and to HCW vaccination programs. Chronification following acute episodes was not a common event.     

Decrease in bladder cell micronucleus prevalence after intervention to lower the concentration of arsenic in drinking water

Epidemiological studies performed in Taiwan, Argentina, and Chile suggest that ingestion of arsenic (As) may cause bladder cancer. Because of these findings, we previously investigated the relationship between As ingestion and genetic damage to the urothelium in two cross-sectional biomarker studies, one in Nevada and one in Chile. In both studies, we found that increased levels of micronucleated cells (MNCs) in exfoliated bladder cells were associated with elevated concentrations of As in drinking water, suggesting that As induces genetic damage to bladder cells. To further investigate this relationship, we conducted an intervention study in a subset of highly exposed men (n = 34) from the cross-sectional study in Chile. Subjects whose usual source of water contained about 600 micrograms/liter As were supplied with water lower in As (45 micrograms/liter) for 8 weeks, allowing ample opportunity for renewal and exfoliation of bladder epithelial cells. Mean urinary As levels decreased during the intervention from 742 to 225 micrograms/liter. Bladder MNC prevalence also decreased from 2.63 MNCs/1000 cells preintervention to 1.79 MNCs/1000 cells postintervention (P < 0.05). When the analysis was limited to individuals previously having subcytotoxic urinary As levels (< 700 micrograms/liter), the change between pre- and postintervention MNC was more pronounced: the level decreased from 3.54 to 1.47 MNCs/1000 cells, respectively (P = 0.002). Among smokers, MNC prevalences decreased from 4.45 MNCs/1000 cells preintervention to 1.44 MNCs/1000 cells postintervention (P = 0.002). Among nonsmokers, the decrease was much smaller: 2.04 MNCs/1000 cells preintervention to 1.90 MNCs/1000 cells postintervention (P = 0.25), suggesting that smoker's bladder cells could be more susceptible to genotoxic damage caused by As. The reduction in bladder MNC prevalence with reduction in As intake provides further evidence that As is genotoxic to bladder cells.