Oral lichen planus in children: A systematic review

BACKGROUND

 Oral Lichen Planus is a common chronic inflammatory disease of the oral mucosa. The prevalence in adults ranges between 0.5% and 2%, while in children is reported to be about 0,03%. Clinical features of Oral Lichen Planus could be variable in both adults and children, ranging from painless white hyperkeratotic lesions to painful erythematous atrophic ones. Actually, there are no systematic reviews in the literature on OLP in children, whereby this paper aims to summarize all the pathophysiological aspects and identify all cases described in the literature of Oral Lichen Planus in children, reporting their clinical characteristics.

MATERIAL AND METHODS

 A systematic review of the literature was performed in online databases including PubMed, Scopus, Web of Science, Science Direct, EMBASE. In addition, in order to identify reports not otherwise identifiable, an analysis of the gray literature was performed on google scholar and in Open Gray.

RESULTS

 By literature analysis, it emerged that most cases were reported from India. The mean age at time of diagnosis of the disease was 11 years, ranging from 3 to 17 years. The most frequent pattern was the reticular pattern followed by plaque-like, erosive, atrophic, sclerosus, and bullous. The buccal mucosa was the most involved oral site, followed by the tongue, lips and gingiva.

CONCLUSIONS

Although Oral Lichen Planus in children is rare, it may cause oral discomfort and need to be differentiated from other oral white lesions and/or chronic ulcers.

Multiparametric correlation of laboratory biomarkers to multiorgan failure outcome in hospitalized COVID-19 patients: a retrospective observational study

OBJECTIVE

COVID-19 is an extremely contagious illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that will keep broadly circulating and evolving. Collected evidence revealed the clinical profile of COVID-19 patients as a potential predictor of their outcome. The aim of this study was to investigate the causal relationship between poor outcomes and laboratory parameters in hospitalized COVID-19 patients, in this sense observing how SARS-CoV-2 infection affects other organs.

PATIENTS AND METHODS

We retrospectively evaluated a cohort of 133 patients, positive for SARS-CoV-2, aged between 30 to 94 years, between January 12th and April 25th, 2021. Discharge from the hospital, transferral to the ordinary ward or nursing home, intensive care unit (ICU) admission, and in-hospital mortality were recorded, along with demographic, laboratory and clinical parameters. The whole sample was summarized by median (interquartile range) for quantitative data, and absolute and relative percentage frequencies for qualitative variables. Univariable logistic regression models were performed to assess the association between all the parameters of interest and COVID-19 adverse outcomes, single (in-hospital mortality) and composite (in-hospital mortality and ICU admission). Hence, a multivariable model was fitted to identify potential independent predictors of the composite outcome. The accuracy of the model was assessed through appropriate fitting indices, such as the C-statistic and Hosmer-Lemeshow test. Moreover, to detect multicollinearity, the variance inflation factor (VIF) was used.

RESULTS

Our study sample had a median age of 72 years old (59.0-83.0). The most common comorbidities were hypertension (63.7%), cardiovascular disease (41.9%), diabetes (33.6%), and cerebrovascular disease (21.5%); while as the most common symptoms, we observed dry cough (32.5%), dyspnoea (50.8%), and fatigue (29.8%). Totally, 18 patients died during hospitalization (13.5%), 10 required ICU admission (7.5%), 78 (58.6%) were discharged from the hospital, and 27 (20.3%) were transferred to either ordinary wards or nursing homes. We disclosed an association of older age with both composite [OR 1.06, 95% CI 1.02-1.09; p=0.003] and single outcome [OR 1.10, 95% CI 1.04-1.16; p=0.001]. A higher oxygen saturation (SpO2) was associated with a better outcome [OR 0.75, 95% CI 0.60-0.93; p=0.009 and OR 0.76, 95% CI 0.61-0.95, p=0.009]. Among laboratory parameters, higher levels of neutrophils increased the risk of a poor outcome [OR 1.05, 95% CI 1.00-1.10; p=0.043]; while higher levels of lymphocytes seem associated with a better outcome [OR 0.94, 95% CI 0.88-0.99; p=0.043]. Higher levels of creatinine were associated with a higher risk of both adverse outcomes [OR 6.20, 95% CI 2.16-17.81; p<0.001 and OR 19.90, 95% CI 5.07-78.06; p<0.001, respectively]. Higher levels of sodium (Na) were associated with a higher risk of adverse events [OR 1.15, 95% CI 1.03-1.28; p=0.014 and OR 1.14, 95% CI 1.01-1.27]. Similar findings were also observed for C-reactive protein (CRP) levels [OR 1.01, 95% CI 1.00-1.02; p=0.010 and OR 1.01, 95% CI 1.00-1.02; p=0.024]. Conversely, being positive to IgM and IgG decreases the risk of adverse outcomes [IgM: OR 0.33, 95% CI 0.14-0.77; p=0.011 and OR 0.23, 95% CI 0.08-0.66; p=0.006. IgG: OR 0.30 95% CI 0.13-0.72; p=0.007 and OR 0.22 95% CI 0.07-0.66; p=0.007]. Hence, a multivariable model was fitted to identify potential independent laboratory predictors of the composite outcome, with laboratory parameters that showed an association with composite outcome. The model can be considered accurate according to LH-Test and C-statistic [p>0.83, C-stat=0.90].

CONCLUSIONS

Our findings confirm that COVID-19 is a multiorgan disease. In fact, the analysis of laboratory parameters has revealed a strong relationship between poorer outcomes and multiple organ dysfunction, particularly established by higher levels of neutrophils, creatinine, sodium, and CRP. Alongside, cerebrovascular diseases, chronic kidney disease and older age supported this finding. Of note, higher levels of SpO2, and lymphocytes, as well as positivity to IgM and IgG were associated with a lower risk of a poor outcome.

Oral bisphosphonate-induced osteonecrosis complications in patients undergoing tooth extraction: a systematic review and literature updates

OBJECTIVE

Bisphosphonates, the most common anti-resorptive medications, are internalized by osteoclasts, where they inhibit the macrophage colony-stimulating factor (M-CSF) pathway, preventing their differentiation, inhibiting anchorage to the cell membrane, and inducing apoptosis. In patients undergoing oral bisphosphonate therapy, oral surgery involves a high risk of developing drug-related osteonecrosis of the jaws (BRONJ/MRONJ), among the possible complications.

MATERIALS AND METHODS

A systematic search was carried out on the PubMed, Scopus and Cochrane Library search engines, using the keywords "oral bisphosphonates AND tooth extraction", "third molar extraction AND oral bisphosphonates". In addition, we manually evaluated the articles included in references from other sources and an analysis of the Gray Literature was performed. A secondary outcome was to evaluate the assessment of pharmacological (antibiotics) use in the BRONJ/MRONJ management. The revision protocol followed the indications of the Cochrane Handbook, and was registered in the INPLASY database, while the drafting of the manuscript was based on PRISMA.

RESULTS

The results of the systematic review, after the study identification and selection process, included a total of 7 studies: 4 retrospective studies, 2 prospective studies and 1 case report. The main complication was represented by osteonecrosis of the jaws, which appears to be related to the duration of treatment with bisphosphonates; in addition, data regarding the anatomical location of post-extraction sites, the sex and age of patients, comorbidities and various systemic risk factors were extrapolated. The most frequent post-extraction complication in patients treated with oral bisphosphonates is osteonecrosis of the jaws, with a significant prevalence in the posterior region of the mandible. In some cases, delayed healing of the surgical wound was also found; moreover, the duration of exposure to oral bisphosphonates influences the onset of complications.

CONCLUSIONS

Ongoing studies continue to unravel the role of the oral environment response in alveolar bone homeostasis and how it might contribute to the induction of BRONJ/MRONJ. Approaching the problem from this perspective could provide new directions for the prevention of BRONJ/MRONJ and expand our understanding of the unique oral microenvironment.

Endoscopic stenting for colorectal cancer obstruction as a bridge-to-surgery strategy

BACKGROUND

Acute obstructive colorectal cancer requires prompt decompression commonly by emergency surgery (ES). However, self-expanding metal stents (SEMS) have been increasingly used as a bridge-to-surgery (BTS) strategy.

MATERIALS AND METHODS

In an 8-year period, consecutive patients with acute left-sided colonic obstruction, due to locally advanced colorectal cancer, underwent ES or SEMS implantation. We evaluated technical/clinical success of SEMS, adverse events, and overall (OS) and disease-free survival (DFS) of the two therapeutic options.

RESULTS

Forty-five patients underwent ES (n = 23) or SEMS (n = 22). The two groups were comparable for sex, age, ASA score and cancer site/stage. Technical and clinical successes of SEMS were 100% and 72.7%, respectively. Clinical success correlated with neutrophil-lymphocyte ratio (NLR) at baseline (OR = 0.65, 95% CI 0.43-0.98, P = .04). SEMS allowed primary anastomosis in the 45.5% of cases (0% in ES). SEMS implantation allowed a higher rate of surgery carried out by a laparoscopic approach: 36.4% vs 13.0% in ES. Performance of a definitive stoma and complications were similar. Median OS (34 in SEMS; 45 in ES, P = .33) and DFS (36 in SEMS; 35 in ES, P = .35) did not differ between the two groups. At univariate analysis, DFS was positively associated with primary anastomosis (HR = 2.44, 95% CI 1.4-16.6, P = .04) and laparoscopic surgery (HR = 8.33, 95% CI 1.08-50, P = .04), and inversely associated with a NLR > 3.6 (HR = 0.59, 95% CI 0.16-0.92, P = .03). At multivariate analysis, no feature retained an independent predictive power.

CONCLUSION

SEMS is an effective and safe procedure, equivalent to emergency surgery in terms of complications, OS and DFS, providing the chance of a primary anastomosis in the majority of patients.

Estimates of HCV-1 patients attaining RVR following dual therapy with peg-interferon and ribavirin

BACKGROUND

Given the significant side-effects and healthcare costs associated with telaprevir- or boceprevir-combination therapy, identifying patients likely to respond to dual therapy peg-interferon (Peg-IFN)/ribavirin is highly desirable. Since the perception of how large the pool of patients who may achieve rapid virologic response (RVR) is vaguely ascertained, we searched the literature for this information.

METHODS

Studies on patients treated with Peg-IFN/ribavirin were identified by searching MEDLINE and analyzed by meta-analysis. The primary end point was weighted estimates of RVR. The influence on race/ethnicity, baseline viremia, type of Peg-IFN, ribavirin dosage, and significant hepatic fibrosis on the results was evaluated.

RESULTS

Across 38 studies on 13,219 patients, the fraction of RVR patients was 19.6 %. The only baseline factor influencing RVR was race/ethnicity, with higher rates in Asian (26.7 %) and Caucasian patients (22.5 %). Of the 1,735 RVR patients, 85.1 % attained sustained virologic response (SVR). In these, SVR was influenced by ribavirin dose (86.8 vs. 72.8 % for high or low), type of Peg-IFN (91.8 % for alpha-2b vs. 82.9 % for alpha-2a), and treatment duration (91.7 % for 48 weeks vs. 79.4 % for 24 weeks).

CONCLUSIONS

One fifth to one fourth of hepatitis C virus genotype 1 (HCV-1) patients can be safely treated with dual therapy of Peg-IFN/ribavirin, and may be spared from cost and inconvenience of regimens considering the addition of HCV protease inhibitors.

Development of a non invasive NGF-based therapy for Alzheimer's disease

Nerve growth factor (NGF) deficits are linked to Alzheimer's Disease (AD), due to the role of NGF on basal forebrain cholinergic neurons (BFCN). We have further established that a disequilibrium in NGF signaling and/or processing from its precursor proNGF is also directly and causally related to the aberrant activation of an amyloidogenic route to neurodegeneration. The therapeutic potential of using human NGF to provide a long-lasting cholinergic trophic support, thereby preventing or slowing cognitive decline in AD patients, has therefore a strong rationale. However, a simple and practical means of delivering NGF to the brain in a safe and long-term manner, limiting the undesired adverse effects of NGF in activating nociceptive responses, has represented a significant challenge. For this reason, pilot clinical studies have been performed so far with invasive approaches requiring neurosurgery. We obtained a proof of principle, in neurodegeneration animal models, of an alternative, non-invasive delivery of NGF through an intranasal route, which facilitates access of NGF to the central nervous system (CNS), while minimizing the biodistribution of NGF to compartments where it activates undesired effects, such as pain. The ideal NGF product for a non invasive NGF-based therapy would be a recombinant NGF that, while exhibiting an identical biological activity to that of human NGF, can be traced, against the endogenous NGF, in order to optimize the therapeutical dose range and meet the required therapeutic window. We describe an engineered mutein of hNGF, hNGF-61, that is selectively recognized, against endogenous NGF, by a specific antibody. hNGF-61 mutein has an identical potency and bioactivity profile as hNGF, in vitro and in vivo. Moreover, hNGF-61 and hNGF are equally effective in rescuing the behavioral and neurodegenerative phenotype in adult and aged AD11 anti-NGF mice. Finally, we demonstrated that intranasally delivered hNGF-61 is significantly more effective than ocularly applied hNGF-61, to determine phenotypic rescue in AD11 mice. The development of hNGF-61 towards clinical applications in AD patients is under way.

Individualized treatment duration for hepatitis C genotype 1 patients: A randomized controlled trial

It was hypothesized that in hepatitis C virus (HCV) genotype 1 patients, variable treatment duration individualized by first undetectable HCV RNA is as effective as standard 48-week treatment. Patients (n = 696) received peginterferon alfa-2a, 180 mg/week, or peginterferon alfa-2b, 1.5 mg/kg/week, plus ribavirin, 1000-1200 mg/day, for 48 weeks (standard, n = 237) or for 24, 48, or 72 weeks if HCV-RNA-negative at weeks 4, 8, or 12, respectively (variable, n = 459). Sustained virologic response (SVR) was achieved in 45.1% [95% confidence interval (CI) 38.8-51.4] of the patients in the standard group and in 48.8% (CI 44.2-53.3) of the patients in the variable group (P = 0.37). The percentages of patients who first achieved undetectable HCV RNA at weeks 4, 8, or 12 were 26.7%, 27.8%, and 11.3%, respectively. In the standard treatment group, 87.1%, 70.3%, and 38.1% of patients who first achieved undetectable HCV RNA at 4, 8, or 12 weeks attained SVRs, respectively. In the variable group, corresponding SVR rates were 77.2%, 71.9%, and 63.5%. Low viremia levels and young age were independent predictors of response at week 4 [rapid virologic response (RVR)]. RVR patients with baseline viremia >or=400,000 IU/mL achieved higher SVR rates when treated for 48 weeks rather than 24 weeks (86.8% versus 73.1%, P = 0.14). The only predictive factor of SVR in RVR patients was advanced fibrosis.

CONCLUSION

Variable treatment duration ensures SVR rates similar to those of standard treatment duration, sparing unnecessary side effects and costs.

Incidence rates of post-ERCP complications: a systematic survey of prospective studies

OBJECTIVES

To provide health-care providers, patients, and physicians with an exhaustive assessment of prospective studies on rates of complications and fatalities associated with endoscopic retrograde cholangiopancreatography (ERCP).

METHODS

We searched MEDLINE (1977-2006) for prospective surveys on adult patients undergoing ERCP. "Grey literature" was sought by looking at cited references to identify further relevant studies. Data on postprocedural pancreatitis, bleeding, infections, perforations, and miscellaneous events as well as their associated fatalities were extracted independently by two reviewers. Sensitivity analysis was performed to test for data consistency between multicenter versus single center studies, and old (1977-1996) versus recent (1997-2005) reports.

RESULTS

In 21 selected surveys, involving 16,855 patients, ERCP-attributable complications totaled 1,154 (6.85%, CI 6.46-7.24%), with 55 fatalities (0.33%, CI 0.24-0.42%). Mild-to-moderate events occurred in 872 patients (5.17%, CI 4.83-5.51%), and severe events in 282 (1.67%, CI 1.47-1.87%). Pancreatitis occurred in 585 subjects (3.47%, CI 3.19-3.75%), infections in 242 (1.44%, CI 1.26-1.62%), bleeding in 226 (1.34%, CI 1.16-1.52%), and perforations in 101 (0.60%, CI 0.48-0.72%). Cardiovascular and/or analgesia-related complications amounted to 173 (1.33%, CI 1.13-1.53%), with 9 fatalities (0.07%, CI 0.02-0.12%). As compared with old reports, morbidity rates increased significantly in most recent studies: 6.27%versus 7.51% (P(c)= 0.029).

CONCLUSIONS

ERCP remains the endoscopic procedure that carries a high risk for morbidity and mortality. Complications continue to occur at a relatively consistent rate. The majority of events are of mild-to-moderate severity.

Nondisjunction rates of mouse chromosomes involved in heterozygous Rb rearrangements measured by chromosome painting of spermatocytes. II. The effects of trivalent combinations and genetic background

Chromosome specific nondisjunction rates were quantified by dual-colour FISH in spermatocytes II of Robertsonian heterozygous mice with different trivalent combinations or, alternatively, with different genetic backgrounds. We found that such factors do not influence the proneness to nondisjunction of specific chromosomes.

Peginterferon alfa-2b and ribavirin for 12 vs. 24 weeks in HCV genotype 2 or 3

BACKGROUND

We hypothesized that in patients with hepatitis C virus (HCV) genotype 2 or 3 in whom HCV RNA is not detectable after 4 weeks of therapy, 12 weeks of treatment is as effective as 24 weeks.

METHODS

A total of 283 patients were randomly assigned to a standard 24-week regimen of peginterferon alfa-2b at a dose of 1.0 mug per kilogram weekly plus ribavirin at a dose of 1000 mg or 1200 mg daily, on the basis of body weight. Of these, 70 patients were assigned to the 24-week regimen (standard-duration group) and 213 patients to a variable regimen (variable-duration group) of 12 or 24 weeks, depending on whether tests for HCV RNA were negative or positive at week 4. The primary end point was HCV that was not detectable by polymerase-chain-reaction (PCR) assay 24 weeks after the completion of therapy.

RESULTS

In the standard-duration group, 45 (64 percent) patients had HCV that was not detectable by PCR assay at week 4, as compared with 133 (62 percent) in the variable-duration group (difference [the rate in the standard-duration group minus that in the variable-duration group], 2 percent; 95 percent confidence interval, -11 to 15 percent). Fifty-three patients (76 percent) in the standard-duration group and 164 patients (77 percent) in the variable-duration group had a sustained virologic response (difference, -1 percent; 95 percent confidence interval, -13 to 10 percent). Fewer patients in the variable-duration group receiving the 12-week regimen had adverse events and withdrew than in the group receiving the 24-week regimen (P=0.045). The rate of relapse (defined as HCV not detectable at the end of treatment but detectable at the end of follow-up) was 3.6 percent in the standard-duration group and 8.9 percent in the variable-duration group (P=0.16). Overall, the rate of sustained virologic response was 80 percent among patients with HCV genotype 2 and 66 percent among those with genotype 3 (P<0.001).

CONCLUSIONS

A shorter course of therapy over 12 weeks with peginterferon alfa-2b and ribavirin is as effective as a 24-week course for patients with HCV genotype 2 or 3 who have a response to treatment at 4 weeks.

A randomized controlled trial of pegylated interferon alpha-2a (40 KD) or interferon alpha-2a plus ribavirin and amantadine vs interferon alpha-2a and ribavirin in treatment-naïve patients with chronic hepatitis C

We determined whether triple therapy comprising amantadine (AMA), ribavirin (RBV) and either peginterferon (PEG-IFN) alpha-2a or conventional IFN alpha-2a would improve sustained virological response (SVR) rates over dual therapy with IFN alpha-2a and RBV in patients with chronic HCV infection. A total of 362 treatment-naïve patients were randomized to 48 weeks of treatment with: PEG-IFN alpha-2a 180 microg/week (group A) or IFN alpha-2a 3 MU tiw (groups B and C). All patients received RBV 1000 or 1200 mg/day and those in groups A and B received AMA 200 mg/day. SVR was defined as an undetectable HCV RNA after 24 weeks of untreated follow-up. At the end of therapy, 74.4% (95% CI 0.66-0.82) of patients in group A were HCV RNA-negative compared with 42.5% (95% CI 0.33-0.50) of those in group B (P = 0.0001) and 48.8% (95% CI 0.40-0.56) of those in group C. SVR was achieved in a significantly greater proportion of patients in group A compared with groups B and C: 65.3% (95% CI 0.53-0.56), 33.3% (95% CI 0.25-0.41) and 44.6% (95% CI 0.36-0.53; P = 0.0001) respectively. In patients with genotype 1, SVR rates were 55.2, 22.8 and 28.8% with the three regimens respectively. Factors independently associated with SVR were HCV genotype 2 or 3, therapy with PEG-IFN, female gender and age. In treatment-naive patients with chronic hepatitis C, triple therapy with PEG-IFN alpha-2a, RBV and AMA produces higher SVR than dual or triple therapy with conventional IFN alpha-2a.

Prophylaxis of ERCP-related pancreatitis: a randomized, controlled trial of somatostatin and gabexate mesylate

BACKGROUND & AIMS

It still is debated whether post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis can be prevented by administering either somatostatin or gabexate mesylate. The aim of the study is to assess the efficacy of a 6.5-hour infusion of somatostatin or gabexate mesylate in preventing ERCP-related complications.

METHODS

In a double-blind multicenter trial, 1127 patients undergoing ERCP were randomly assigned to intravenous administration of somatostatin (750 microg; n = 351), gabexate mesylate (500 mg; n = 381), or placebo (saline; n = 395). The drug infusion started 30 minutes before and continued for 6 hours after endoscopy. Patients were evaluated clinically, and serum amylase levels were determined at 4, 24, and 48 hours after endoscopy.

RESULTS

No significant differences in incidences of pancreatitis, hyperamylasemia, or abdominal pain were observed among the placebo (4.8%, 32.6%, and 5.3%, respectively), somatostatin (6.3%, 26.8%, and 5.1%, respectively), and gabexate mesylate groups (5.8%, 31.5%, and 6.3%, respectively). Univariate analysis of patient characteristics and endoscopic maneuvers showed that a Freeman score >1 (P < 0.0001), >/=3 pancreatic injections (P < 0.00001), and precut sphincterotomy (P = 0.01) were significantly associated with post-ERCP pancreatitis. At multiple logistic regression analysis, >/=3 pancreatic injections (odds ratio [OR], 1.95; 95% confidence interval [CI], 1.45-2.63) and a Freeman score >1 (OR, 1.47; 95% CI, 1.11-1.94) retained their predictive power.

CONCLUSIONS

Long-term (6.5-hr) administration of either somatostatin or gabexate mesylate is ineffective for the prevention of post-ERCP pancreatitis. Pancreatic injury seems to be related to difficulty in common bile duct access.

Nondisjunction rates of mouse specific chromosomes involved in heterozygous Rb rearrangements measured by chromosome painting of spermatocytes II. I. The effects of the number of trivalents

Dual-colour FISH painting with alternative fluorescent chromosome-specific probes allowed us to distinguish chromosomes 1, 4, 6 and 14. The purpose was to check whether nondisjunction rates of specific chromosomes involved in heterozygous Robertsonian fusions are independent of the number of trivalents, or an epistatic effect among Rb chromosomes takes place affecting nondisjunction rates. Probes were used on DAPI-stained metaphases of spermatocytes II of laboratory strains of mice with reconstructed karyotypes heterozygous for one, two, three or four Robertsonian metacentrics in an all-acrocentric background. The existence of such epistatic interactions was not verified.

Cerebellar contribution to spatial event processing: do spatial procedures contribute to formation of spatial declarative knowledge?

Spatial knowledge of an environment involves two distinct competencies: declarative spatial knowledge, linked to where environmental cues are and where the subject is with respect to the cues, and, at the same time, procedural spatial knowledge, linked to how to move into the environment. It has been previously demonstrated that hemicerebellectomized (HCbed) rats are impaired in developing efficient exploration strategies, but not in building spatial maps or in utilizing localizing cues. The aim of the present study was to analyse the relationships between spatial procedural and declarative knowledge by using the open field test. HCbed rats have been tested in two different protocols of the open field task. The results indicate that HCbed animals succeeded in moving inside the arena, in contacting the objects and in habituating to the new environment. However, HCbed animals did not react to environmental changes, when their impaired explorative pattern was inappropriate to the environment, suggesting that they were not able to represent a new environment because they were not able to explore it appropriately. Nevertheless, when their altered procedures were favoured by object arrangement, they detected environmental changes as efficiently as did normal rats. This finding suggests that no declarative spatial learning is possible without appropriate procedural spatial learning.

Cosegregation of Robertsonian metacentric chromosomes in the first meiotic division of multiple heterozygous male mice as revealed by FISH analysis of spermatocyte II metaphases

Contrasting results (random segregation or cosegregation of isomorphic chromosomes) have been reported up to now on the segregation pattern of Robertsonian metacentric chromosomes of Mus musculus domesticus in multiple heterozygotes, using different approaches (karyotypical analysis of the progeny or of second meiotic metaphases). In the present contribution data are presented based on FISH (Fluorescence In Situ Hybridisation) analysis with telomeric probes, which allowed us to distinguish metacentric chromosomes from pairs of acrocentric chromosomes with their centromeric regions close to each other. Probes were hybridized to DAPI stained metaphases of spermatocytes II of mice heterozygous for two, three or four Robertsonian metacentrics in an all-acrocentric background, the karyotype of which has been reconstructed starting from laboratory strains. Isomorphic chromosomes tend to cosegregate (metacentrics with metacentrics, acrocentrics with acrocentrics); the values found for cosegregation have a clear even if moderate effect on the reproductive isolation caused by underdominant chromosomal rearrangements.

Antisecretory vs. antiproteasic drugs in the prevention of post-ERCP pancreatitis: the evidence-based medicine derived from a meta-analysis study

Uncertainties still exist about the clinical benefit of pharmacological prevention of post-ERCP pancreatitis by either antisecretory drugs such as somatostatin and its long-acting analogue octreotide, or protease inhibitors such as gabexate mesilate. Recent, large-scale prospective studies have reported a fourfold reduction in acute pancreatitis as compared to a placebo with the prophylactic administration of either gabexate mesilate or somatostatin, whereas octreotide was found to be ineffective. An initial meta-analysis of all available controlled trials on this topic has confirmed these findings. The indiscriminate use of these drugs in all patients is unlikely to be cost-effective, but the selective use of prophylaxis for high-risk patients might be advocated. Moreover, inasmuch as 85% of complications developed within 4 to 6 hours of completing the ERCP, it would be reasonable to infuse drugs only for this limited length of time. A recent prospective trial, carried out on high-risk patients, has surprisingly documented a higher incidence, although a non-significant one, of pancreatitis in patients who received short-term prophylaxis with somatostatin or gabexate mesilate than those given a placebo: 11.5% and 8.1% vs. 6.5%, respectively. In order to explore this discrepancy, the original meta-analysis was updated by including data of this negative trial: heterogeneity among the trials was apparent. A careful scrutiny of the most recent studies has revealed differences in patient population, protocols of drug administration, technique and operator-related risk factors for complications among the trials, which could explain, by themselves, the contrasting results reported by the interventional studies. In conclusion, current literature does not support the prophylactic use of either somatostatin or gabexate mesilate for the prevention of ERCP-related pancreatic damage, even in patients deemed to be at high risk for complications. At present, post-ERCP complications (and pancreatitis) can be prevented efficaciously by appropriate selection of patients, mastering of the technique and operator competence.

Partial deletions of long arm of chromosome 6: biologic and clinical implications in adult acute lymphoblastic leukemia

Within 285 adult acute lymphoblastic leukemias (ALL) included in the multicenter GIMEMA 0496 trial and prospectively studied by conventional cytogenetics, 18 cases (6%) with long arm deletion of chromosome 6 (6q) were identified. These cases were divided into: (i) del(6q) only (n = 6); (ii) del(6q) plus other numerical and/or structural abnormalities (n = 8); (iii) del(6q) and other 'specific' translocations (n = 4). The biologic and clinical features of the patients carrying this anomaly, as well as their outcome, were compared with those of 267 patients without del(6q). A T cell phenotype was more frequently associated with del(6q) cases in general (P = 0.001) and particularly with cases presenting del(6q) as the isolated abnormality (P = 0.0027). No significant difference with respect to multidrug resistance (MDR)/P glycoprotein expression was observed between the two groups of patients (21% vs 28% of MDR-positive cases, respectively). A BCR-ABL fusion transcript was less frequently detected in cases with del(6q) (11%) compared with those without the anomaly (29%). p15 and p16 deletions were identified by Southern blot analysis in 21% of cases with del(6q) and in 26% of cases without del(6q). In this latter group, a T cell phenotype was less frequently associated with p15 and/or p16 deletion than in the group carrying del(6q) (36% vs 100% of cases, P = 0.011). Overall, patients with ALL and del(6q) had a high complete remission (CR) rate (83%); however, they had a lower 18 month event-free survival (31% vs 41%) and a higher relapse rate (70% vs 37%, P = 0.02) compared with patients without del(6q). To date, this is the largest series of adult ALL cases reported with del(6q) homogeneously treated, which have also been prospectively studied for MDR expression and for the detection of known fusion genes. This anomaly, as an isolated change, identifies a subset of cases with hyperleukocytosis (median WBC count 52 x 10(9)/l) and a strict correlation with a T cell phenotype. Overall, del(6q) seems to be associated with an unfavorable clinical outcome, although this finding will need to be confirmed by extended FISH analysis.

High doses of interferon in combination with ribavirin are more effective than the standard regimen in patients with HCV genotype 1 chronic hepatitis

BACKGROUND/AIMS

The aim of the present, open-labelled, controlled study was to determine whether 5 MU of interferon (IFN) alpha 2b combined with a standard dose of ribavirin might increase the rate of viral clearance in all patients with chronic HCV hepatitis or at least in those with an unfavourable genotype.

METHODS

A total of 298 previously untreated patients with chronic hepatitis C were randomized to 5 or 3 MU of interferon alpha 2b 3 times per week with 1000-1200 mg of ribavirin daily (148 and 150 patients, respectively). Patients were treated for 12 months and observed for 6 months posttreatment.

RESULTS

In patients infected with HCV genotype 1, the sustained virologic response was 37.8% (95% CI 27.3-48.1) with IFN 5 MU and 19.2% (95% CI 10.1-28.2) with IFN 3 MU (P=0.008). Out of 45 sustained responders with genotype 1, 31 (69%) had received 5 MU and 14 (31.1%) the standard 3 MU dose of IFN in combination with ribavirin (P=0.01). Of the 86 responders infected with genotype non-1, 39 (45.3%) were from the 5 MU IFN group and 47 (54.6%) were from the 3 MU IFN group; these figures were not significant. At the multivariate analysis of baseline features for all patients, the variables with an independent effect for a sustained response were genotype non-1 (odds ratio (OR) 3.98, 95% CI 2.36-6.40), and the histological grading (score 0-2) (OR 2.48, 95% CI 1.12-5.51) and staging (score 0-1) (OR 1.73, 95% CI 1.02-2.95). For patients with genotype 1 only the high regimen of IFN entered the model (OR 2.39, 95% CI 1.13-5.05), whereas for patients with genotype non-1 an age of <40 years (OR 2.64, 95% CI 1.23-5.70) and staging (score 0-1) (OR 2.38, 95% CI 1.07-5.28) were independent predictors of a sustained response.

CONCLUSIONS

Our study suggests that when treating naive patients with genotype 1, there is a significant increase in the rate of sustained virologic clearance by increasing the dose of IFN given in combination with ribavirin.

Novel mutations in the LAMC2 gene in non-Herlitz junctional epidermolysis bullosa: effects on laminin-5 assembly, secretion, and deposition

Laminin-5 is the major adhesion ligand of epithelial cells. Mutations in the three genes (LAMA3, LAMB3, LAMC2) encoding the laminin-5 chains cause junctional epidermolysis bullosa, a clinically and genetically heterogeneous blistering skin disease. Here, we describe a non-Herlitz junctional epidermolysis bullosa patient, compound heterozygote for two novel mutations affecting the LAMC2 gene. The mutation in the paternal allele is a de novo splice site mutation (522-1G-->A) that results in in-frame skipping of exon 4 and synthesis of a mutated gamma2 polypeptide (gamma2Delta4) carrying a 33 amino acid deletion within the N-terminal domain V. The maternal mutation is a one base pair insertion (3511insA) in the 3' terminal exon of LAMC2 resulting in a frameshift and a premature termination codon. Mutation 3511insA is predicted to lead to the synthesis of a gamma2 polypeptide (gamma2t) disrupted in its alpha-helical C-terminal structure and truncated of the last 25 amino acids. Keratinocytes isolated from the patient's skin showed a markedly decreased level of gamma2 chain mRNA and secreted scant amounts of laminin-5, which undergoes physiologic proteolytic processing. To investigate the biologic function of the laminin-5 molecules synthesized by the patient, mutant gamma2 cDNAs were transiently expressed in gamma2-null keratinocytes. Transfection of the gamma2Delta4 cDNA resulted in restoration of laminin-5 deposition onto the culture substrate, which demonstrates that the gamma2 polypeptides carrying a deletion in domain V, upstream of the gamma2 proteolytic cleavage site, are assembled into native laminin-5 that is secreted and extracellularly processed. In contrast, transfection of a mutant cDNA expressing the gamma2t chain failed to restore laminin-5 immunoreactivity, which indicates that integrity of the gamma2 C-terminal amino acid sequences is required for laminin-5 assembly. These results correlate for the first time a functional alteration in a laminin-5 domain with a mild junctional epidermolysis bullosa phenotype.

Reduced expression of the epithelial adhesion ligand laminin 5 in the skin causes intradermal tissue separation

Laminin 5, the major keratinocyte adhesion ligand, is found in the lamina lucida subregion of the epidermal basement membrane of the skin, where it colocalizes with the anchoring filaments. Mutations in the genes encoding laminin 5 cause junctional epidermolysis bullosa, an inherited skin blistering disease characterized by abnormal hemidesmosomes and cleavage of the lamina lucida leading to epidermal detachment. In this work we describe the genetic basis of a new subtype of lethal inherited epidermolysis bullosa associated with reduced skin reactivity to laminin 5, presence of mature hemidesmosomes, and intradermal cleavage of the skin. The epidermolysis bullosa patients were heterozygous for a nonsense mutation (Q896X) and a splice site mutation (764-10T-->G) in the gene (LAMC2) for the gamma2 chain of laminin 5. The nonsense mutation causes accelerated decay of the corresponding mRNA, while the splice site mutation results in maturation of a cryptic wild-type gamma2 mRNA leading to reduced expression of wild-type laminin 5. In vitro studies using the probands' keratinocytes showed that secretion of reduced amounts of functional laminin 5 in the patient, although permitting formation of hemidesmosomes, fail to restore efficient cell adhesion. Our results provide the first evidence that laminin 5 contributes to the firm adhesion of the epithelial basement membrane to the underlying stroma. They also show that a low expression level of laminin 5 induces assembly of mature hemidesmosomes in vivo but fails to assure a stable cohesion of the dermal-epidermal junction.

Cutaneous gene transfer and therapy: the present and the future

The easy accessibility of the skin as a therapeutic target provides an exciting potential for this organ for the development of gene therapy protocols for cutaneous diseases and a variety of metabolic disorders. Thus far, full phenotypic reversion of a diseased phenotype has been achieved in vivo for junctional epidermolysis bullosa and X-linked or lamellar ichthyosis and in vitro for xeroderma pigmentosum. These recessive skin diseases are characterized by skin blistering, abnormalities in epidermal differentiation and increased development of skin cancers, respectively. Corrective gene delivery at both molecular and functional levels was achieved by transduction of cultured skin cells using retroviral vectors carrying the specific curative cDNA. These positive results should prompt clinical trials based on transplantation of artificial epithelia reconstructed ex vivo using genetically modified keratinocytes. Promising results have also been obtained in phenotypic reversion of cells isolated from patients suffering from a number of metabolic diseases such as gyrate atrophy, familial hypercholesterolemia or phenylketonuria. In these diseases transplantation of autologous artificial epithelia expressing the transgenes of interest or direct transfer of the DNA to the skin represents a potential therapeutic approach for the systemic delivery of active molecules. Successful cutaneous gene therapy trials, however, require development of protocols for efficient gene transfer to epidermal stem cells, and information about the host immune response to the recombinant polypeptides produced by the implanted keratinocytes. The availability of spontaneous animal models for genodermatoses will validate the gene therapy approach in preclinical trials.

Pharmacologic treatment can prevent pancreatic injury after ERCP: a meta-analysis

BACKGROUND

The identification of therapeutic agents that can prevent the pancreatic injury after endoscopic retrograde cholangiopancreatography (ERCP) is of considerable importance.

METHODS

We performed a meta-analysis including 28 clinical trials on the use of somatostatin (12 studies), octreotide (10 studies), and gabexate mesilate (6 studies) after ERCP. Outcome measures evaluated were the incidence of acute pancreatitis, hyperamylasemia, and pancreatic pain. Three analyses were run separately: for all available studies, for randomized trials only, and for only those studies published as complete reports.

RESULTS

When all available studies were analyzed, somatostatin and gabexate mesilate were significantly associated with improvements in all three outcomes. Odds ratios (OR) for gabexate mesilate were 0.27 (95% CI [0.13, 0. 57], p = 0.001) for acute pancreatitis, 0.66 (95% CI [0.48, -0.89], p = 0.007) for hyperamylasemia, and 0.33 (95% CI [0.18, 0.58], p = 0. 0005) for post-procedural pain. Somatostatin reduced acute pancreatitis (OR 0.38: 95% CI [0.22, 0.65], p < 0.001), pain (OR 0. 24: 95% CI [0.14, 0.42], p < 0.001), and hyperamylasemia (OR 0.65: 95% CI [0.48, 0.90], p = 0.008). Octreotide was associated only with a reduced risk of post-ERCP hyperamylasemia (OR 0.51: 95% CI [0.31, 0.83], p = 0.007) but had no effect on acute pancreatitis and pain. The statistical significance of data did not change after analyzing randomized trials only or studies published as complete reports. For each considered outcome, the publication bias assessment and the number of patients that need to be treated to prevent one adverse effect were, respectively, higher and lower for somatostatin than for gabexate mesilate.

CONCLUSIONS

The pancreatic injury after ERCP can be prevented with the administration of either somatostatin or gabexate mesilate, but the former agent is more cost-effective. Additional studies comparing the efficacy of short-term infusion of somatostatin versus gabexate mesilate in patients at high risk for post-ERCP complications seem warranted.

Aneuploidy in metaphases II of spermatocytes of wild house mice from a hybrid zone between a Robertsonian population (CD: 2n = 22) and a population with the standard karyotype (2n = 40)

Meiotic metaphases II from archival slides were studied of male house mice caught in a hybrid zone between a population monomorphic for nine centric fusions (2n = 22) and a population with the standard karyotype (2n = 40), near Rome. The frequency of aneuploidy increases, up to 50%, with increasing number of heterozygous centric fusions (1-4).

Prolonged treatment (2 years) with different doses (3 versus 6 MU) of interferon alpha-2b for chronic hepatitis type C. Results of a multicenter randomized trial

BACKGROUND/AIMS

To examine the effect of prolonged treatment with different doses of interferon alpha-2b on the relapse rate in patients with chronic hepatitis C.

METHODS

One hundred and seventy-one patients with non-cirrhotic chronic hepatitis C were enrolled in an Italian multicenter trial. All patients were treated for 3 months with 3,000,000 Units (3 MU) of interferon alpha-2b given subcutaneously three times a week (t.i.w.). Patients with abnormal alanine aminotransferase (ALT) values were given 6 MU of interferon for an additional 3 months. If ALT remained persistently abnormal, therapy was then suspended. If ALT levels were normal, therapy was continued (6 MU t.i.w.) for an additional 18 months (total=2 years). Patients with normal ALT were randomly assigned to two groups, one receiving 3 MU and the other receiving 6 MU t.i.w. for an additional 21 months (total=2 years). Follow-up continued for 2 years after therapy withdrawal.

RESULTS

Seven patients stopped treatment during the first 3 months. Of the remaining 164 patients, 76 (46%) showed abnormal ALT levels after 3 months of therapy: 11 of these (14%) normalized ALT values when given 6 MU and a sustained response was maintained in eight during the follow-up. Overall, 54 and 34 patients were allocated respectively to the groups receiving the 3 MU and 6 MU long-term treatment. At the end of therapy, 35/54 patients of the group 3 MU and 21/34 patients of the group 6 MU showed normal ALT levels (65% vs 62%, p=N.S.). After 2 years of follow-up, 24/35 (69%) patients of the group 3 MU and 16/21 (76%) of the group 6 MU were still in remission (p=N.S.). In an intention-to-treat analysis, 48/171 (28%) patients showed a long-term response (normal ALT values, HCV-RNA negative). About 65% of the sustained responders showed low baseline viremia compared with 33% of non-responders (p=0.005) while genotype 1b was more frequently found among non-responders than in long-term responders (84% vs 25%, p=0.0001).

CONCLUSIONS

About 14% of patients who do not respond to a 3-month course of 3 MU of interferon normalize ALT levels when given 6 MU. In prolonged treatment, there is no significant difference between 3 and 6 MU in inducing a sustained response. Patients with low baseline viremia and genotype 2a respond significantly better to prolonged interferon therapy than highly viremic patients with genotype 1b.

HCV genotypes in patients with liver disease of different stages and severity

AIMS/MATERIAL: Hepatitis C virus (HCV) genotyping was performed in 213 anti-HCV-positive patients with chronic liver disease ranging from minimal histological changes to hepatocellular carcinoma. One hundred and twenty-two patients had non-cirrhotic chronic active or persistent hepatitis (including 29 who were asymptomatic with persistently normal ALT levels) (chronic liver disease group). The other 91 had hepatocellular carcinoma and, in all but three cases, cirrhosis (hepatocellular carcinoma group).

RESULTS

The overall prevalence of HCV variants was: 54.9% type 1b, 37.8% type 2, 2.5% type 1a, 2.0% type 3a, 2.0% type 4a. The genotype distribution showed no relation to the stage (chronic liver disease vs. hepatocellular carcinoma) or severity (chronic active vs. chronic persistent hepatitis) of the liver disease, or to the duration of the disease (<10 years vs. >10 years). Within the hepatocellular carcinoma group, the duration of type-1b disease was similar to that of type-2 infections. Ages at the time of infection and genotype were both independently associated with progression to cirrhosis and hepatocellular carcinoma, but multivariate analysis revealed that the effect of age was much stronger than that of genotype 1b.

CONCLUSIONS

The predominance of HCV type 1b in this study reflects the higher frequency of this variant in our area. Our findings indicate that infections caused by each HCV genotype are capable of progressing to hepatocellular carcinoma.

Long-distance effect of downstream transcription on activity of the supercoiling-sensitive leu-500 promoter in a topA mutant of Salmonella typhimurium

Expression of the lacZ gene from the supercoiling-sensitive leu-500 promoter on a plasmid in topA mutant cells was stimulated by activating a divergently oriented Tac promoter, 400 bp upstream from leu-500. The stimulation was approximately threefold regardless of whether the Tac promoter drove the expression of the tet gene, whose product is membrane bound, or of the cat gene, whose product is cytosolic. Putting a second copy of the Tac promoter downstream from lacZ, approximately 3,000 bp from leu-500 in the same orientation as the latter, resulted in 30-fold increase in lacZ expression upon isopropyl-beta-D-thiogalactopyranoside induction. Again, these effects were independent of the nature of the gene upstream from leu-500 (tet or cat). With both tet- and cat-harboring constructs, activation of the two Tac promoter copies caused plasmid DNA to become hypernegatively supercoiled in topA mutant cells. Thus, neither leu-500 activation nor hypernegative plasmid DNA supercoiling appears to require membrane anchoring of DNA in this system. Replacing the downstream copy of Tac with a constitutive promoter resulted in high-level lacZ expression even when the upstream copy was repressed. Under these conditions, no hypernegative DNA supercoiling was observed, indicating that the activity of plasmid-borne leu-500 in topA mutant cells does not necessarily correlate with the linking deficit of plasmid DNA. The response of the leu-500-lacZ fusion to downstream transcription provides a sensitive assay for transcriptional supercoiling in bacteria.

Hyper-negative template DNA supercoiling during transcription of the tetracycline-resistance gene in topA mutants is largely constrained in vivo

The excess linking deficit of plasmid DNA from topoisomerase I-defective bacteria (topA mutants) results mainly from transcription and is commonly ascribed to unbalanced relaxation of transcription-induced twin-supercoiled domains. This defect is aggravated in genes for membrane-binding proteins (such as the tet gene) where anchoring of the transcription complex to the bacterial membrane is thought to enhance twin-domain partitioning. Thus, it is often assumed that the 'hyper-negative' linking difference of plasmid DNA from topA mutants reflects unconstrained, hyper-negative DNA supercoiling inside the cell. We tested the validity of this assumption in the present study. A DNA sequence that undergoes a gradual B to Z transition under increasing negative superhelical tension was used as a sensor of unconstrained negative supercoiling. Z-DNA formation was probed at a site upstream from the inducible pTac promoter fused either to the tet gene or to the gene for cytosolic chloramphenicol acetyl transferase (cat). Although plasmid DNA linking deficit increased more extensively in topA mutants following tet activation than following cat activation, no significant differences were observed in the extents to which the B to Z DNA transition is stimulated in the two cases. We infer that the excess linking deficit of the tet-containing plasmid DNA reflects constrained negative DNA supercoiling inside the cell.

A class of gyrase mutants of Salmonella typhimurium show quinolone-like lethality and require rec functions for viability

We have identified a new class of DNA gyrase mutants of Salmonella typhimurium that show chronic derepression of the SOS regulon. Thus, these mutants mimic the response of wild-type cells to gyrase inhibitors of the quinolone family. SOS induction by conditional lethal mutations gyrA208 or gyrB652, like that mediated by quinolones, is completely dependent on the function of the recB gene product. Introduction of recA or recB null mutations into these strains exacerbates their temperature-sensitive phenotype and prevents growth at the otherwise permissive temperature of 37 degrees C. Selection of suppressors that concomitantly restore growth at 37 degrees C and SOS induction in a recB- background yielded mutations that relleve the RecB requirement for homologous recombination; namely, sbcB mutations as well as mutations at a new locus that was named sbcE. Such mutations also restore SOS induction in quinolone-treated gyr+ recB- strains. These findings indicate that Rec functions are needed for growth of the gyrase mutants at 37 degrees C and suggest that recombinational repair intermediates constitute the SOS-inducing signal in the mutants as well as in quinolone-treated wild-type bacteria. Unlike quinolones, however, the gyr mutations described in this study do not cause detectable accumulation of "cleavable' gyrase-DNA complexes in plasmid or chromosomal DNA. Yet gyrA208 (the only allele tested) was found to trigger RecB-mediated reckless degradation of chromosomal DNA in recA-cells at restrictive temperatures. Indirect evidence suggests that double-stranded DNA ends, entry sites for the RecBCD enzyme, are generated in the gyr mutants by the breakage of DNA-replication forks. We discuss how this could occur and how recombinational rescue of collapsed replication forks could account for cell survival (and SOS induction) in the gyr mutants as well as in quinolone-treated bacteria.

RNA polymerase (rpoB) mutants selected for increased resistance to gyrase inhibitors in Salmonella typhimurium

Some rifampicin-resistance (RifR) mutations make bacteria slightly resistant to the gyrase inhibitors novobiocin (Nov) and nalidixic acid (Nal). This suggested that it might be possible to isolate rpoB mutants using either drug for positive selection. In an initial test, we confirmed the presence of Rif-resistant isolates among clones selected for Nov resistance. These mutants are also more resistant to Nal. In a subsequent experiment, we found that mutants selected for low-level resistance to Nal include isolates harboring mutations genetically linked to the rpoB locus; of two such mutants studied, one is temperature-sensitive for growth. These two mutants, which are only marginally affected in their response to Nov, are normally sensitive to Rif and thus might be representative of a new class of rpoB alleles. The Rif-resistant and Rif-sensitive rpoB alleles that increase resistance to gyrase inhibitors have one property in common: they all suppress, to varying degrees, the defect in his operon regulation (transcriptional deattenuation) caused by a gyrase defect or inhibition by novobiocin. To further analyse the transcription-supercoiling relationships in these mutants, we examined the ability of RNA polymerase to recruit gyrase activity during transcription. This was done by two independent approaches: (i) observing transcription-induced accumulation of hyper-negatively supercoiled plasmid DNA in a topA mutant background and (ii) measuring transcription-induced plasmid DNA cleavage in the presence of oxolinic acid. Results indicate that the rpoB alleles described in this study diminish the recruitment of gyrase activity by the transcription process. This property correlates with a decrease in the rate of transcription initiation.(ABSTRACT TRUNCATED AT 250 WORDS)

The relative contributions of transcription and translation to plasmid DNA supercoiling in Salmonella typhimurium

Mutations affecting DNA topoisomerase I (topA) in Salmonella typhimurium were isolated and graded on the basis of their ability to reverse the effects of gyrB mutations on his operon expression. Different topA and gyrB alleles (in otherwise isogenic strains) were used to gather insights into the transcription-dependent variability of plasmid DNA-linking deficit in growing bacteria. This study showed that modulation of DNA supercoiling by transcription results from the action of two components: one is highly dependent on the coupling of translation to RNA-chain elongation; and the other is unrelated to protein synthesis and entirely dependent on promoter determinants. The former greatly predominates in DNA topoisomerase I mutants (topA and topA gyrB) while the latter is the sole contributor to plasmid DNA-linking deficit in wild-type cells. Altogether, these data suggest that whereas translation acts by enhancing the formation of twin supercoiled domains during elongation, the promoter-dependent effects bear no relation to the twin-supercoiled-domain model and are better explained by a mechanism which responds to the binding/unwinding of template DNA by RNA polymerase.

The establishment of underdominant chromosomal rearrangements in multi-deme systems with local extinction and colonization

The fate of an underdominant chromosomal mutant was investigated in multideme models with high rates of local extinction and colonization. Four models with different patterns of colonization (number of colonists and place of origin of colonists) were studied by performing a large number of computer simulations with the Monte Carlo method for several sets of values of the following parameters: coefficient of selection against the heterozygote, extinction rate of each deme, deme size, and number of demes. The probability of the newly arisen rearrangement being established in the multi-deme system depends strongly on the pattern of colonization, other things being equal. In the three models in which there is absent or scarce mixing of gene pools of different demes when a new deme is founded, the fixation probability of the new chromosomal rearrangement is rather close to that calculated by R. Lande (1979, Evolution 33, 234-251; 1985, Heredity 54, 323-332), which is equal to the corresponding probability in a single deme divided by the number of demes. In the model with extensive mixing of gene pools of demes, the corresponding probability is lower (considerably in some cases). Furthermore, in the models where the fixation probability is higher, the analysis of the time of the process leads to the conclusion that in systems consisting of a large number of demes, overlapping of several different processes of fixation of chromosomal rearrangements occurs.

The exact values of the probability of fixation of underdominant chromosomal rearrangements

A numerical analysis of the probability of fixation of a chromosomal mutation with partial sterility of the heterozygote in a single population is performed. Three different genetic models are considered: the first model entails constant selection against the heterozygote and is the model almost universally used in previous works; in the other two models selection against the heterozygote depends on its frequency. The exact values of the fixation probability are found by iterating transition matrices with genotype specification. Differences in results among models are small. The exact values found in the first model are compared to estimates obtained from approximations. Solutions based on diffusion models give good approximations when selection against the heterozygote is low, especially if the population is very small. For the higher values of the selection coefficient against the heterozygote, the estimates are rather imprecise, especially when the populations are not very small.

[Peptic ulcer in liver cirrhosis]

The frequency of peptic ulcer and the role of ulcerogenic risk factors in cirrhotic patients were evaluated in a retrospective study. Peptic disease was observed in 18.2% of the cirrhotic patients examined. When compared to the prevalence of ulcerative lesions in the general population, this finding suggests that cirrhotic patients have the same probability of being affected by peptic ulcer as non-cirrhotic subjects. The analysis of ulcerogenic risk factors highlighted the importance of alcohol and smoking. The etiology of cirrhosis and portal hypertension were not found to be important. In conclusion, peptic disease is not more frequent in cirrhotic patients than in the general population.

Granular cell tumor of the esophagus

Granular cell tumor (GCT) of the esophagus is a rarely-met-with neoplasm. It is almost invariably benign in character and is of still-disputed histogenesis. Small lesions are asymptomatic. Those over 1 cm in diameter may be accompanied by painful swallowing or retrosternal discomfort. Local resection is the treatment of choice for lesions that are accompanied by symptoms, or that are larger than 1 cm. A tumor incidentally encountered in an asymptomatic patient may be safely followed endoscopically. A successful endoscopic removal of such a lesion is described.

The reduction of gene exchange due to a prezygotic isolating mechanism with monogenic inheritance

The efficiency of an incomplete prezygotic reproductive isolating mechanism in one- and two-population models is studied. The isolating mechanism studied has a monogenic hereditary basis, and depends on the fact that the various genotypes "choose" different periods or sites to perform their reproductive activity. In the one-population models, the "neutral" gene exchange between the two morphs characterized by the alternative forms of the isolating mechanism decreases drastically only when there is an extremely low frequency of individuals with different genotypes reproducing in the same sites and during the same periods. Furthermore, the reduction in gene exchange caused by the prezygotic isolation is smaller with tight linkage between the gene-determining partial reproductive isolation and the neutral gene. In the two-population models the prezygotic isolation causes a reduction in gene exchange which is smaller with low migration rates, and is negligible for very low rates.

Reduction of neutral gene flow due to the partial sterility of heterozygotes for a linked chromosome mutation

The effect of linkage between a chromosome mutation producing partially sterile heterozygotes and a neutral locus in reducing the gene flow at the neutral locus is studied using a two-population deterministic model. Chromosome mutations are more efficient in reducing gene flow with low migration rates than with high ones. The interaction between high values of partial heterozygote sterility and low recombination rates can produce, in the low migration pattern, a drastic reduction of gene flow. Nevertheless, since only chromosome mutations with low values of partial heterozygote sterility are likely to be involved in chromosomal speciation, a significant reduction of gene flow will probably occur only for a very limited part of the genome. Therefore, a single chromosome mutation is unlikely to play a primary role in speciation.

[Recording of the right atrial monophasic action potential in humans. I. Subjects not affected by arrhythmia]

Using a bipolar suction electrode technique, right atrial monophasic action potential (RA MAP) was recorded in 18 patients surely free from any kind of arrhythmia. Two morphologically different kinds of RA AMP were obtained: the former exhibiting an evident transition between phase 1-2 (plateau) and phase 3 of repolarization (FP), the latter without any appreciable palteau (FL). Electrophysiological properties of human myocardial atrial tissue have been investigated by microelectrode technique. The two types of MAP recorded by us resemble the former the action potential obtained from conducting specialized fiber, the latter the action potential of contractile fibers. A statistically significant difference in RA MAP duration measured at 90% level of repolarization (D 90%) was found between the two kinds of MAP: therefore we suggest to perform quantitative evaluations and pharmaco-ogical investigations only including MAPs of similar morphology. The intraindividual variation coefficient of D 90% may be considered an expression of the range of variability of repolarization duration in man; we suggest that only MAPs of similar configuration should be accepted for its calculation in order to avoid errors of evaluation.

The symmetry of radiation-induced chromatid exchanges in relation to the cell cycle in Chinese hamster cells in vivo and in vitro

The symmetry of radiation-induced chromatid exchanges was studied in relation to the cell cycle in Chinese hamster cells in vivo and in vitro. Both in vivo and in vitro, the ratio between symmetrical and asymmetrical chromatid exchanges was about 1 to 1 during G2 and S phase of the cell cycle.

Chromosome constitution of in vitro segregated haploid and diploid cells of the mouse

The composition in segregated haploid sets of paternal and maternal chromosomes has been studied in order to verify whether their composition is uniparental of mixed, fixed or variable. Primary cultures where prepared using kidneys from hybrids of strains of Mus musculus in which the parental chromosomes are distinguishable; the maternal set consists of 20 teleocentric chromosomes, the paternal set of 9 metacentric chromosomes, derived by Robertsonian fusion and 2 telocentrics. Applying Seabright's banding technique, an analysis of segregated haploid and diploid cells, which have originated spontaneously through polyploidisation-segregation processes was carried out. It was concluded that the haploid sets have a variable composition of paternal and maternal chromosomes.