Switching yeast from meiosis to mitosis: double-strand break repair, recombination and synaptonemal complex

Background:

When Saccharomyces cerevisiae cells that have begun meiosis are transferred to mitotic growth conditions (‘return-to-growth’, RTG), they can complete recombination at high meiotic frequencies, but undergo mitotic cell division and remain diploid. It was not known how meiotic recombination intermediates are repaired following RTG. Using molecular and cytological methods, we investigated whether the usual meiotic apparatus could repair meiotically induced DSBs during RTG, or whether other mechanisms are invoked when the developmental context changes.

Results:

Upon RTG, the rapid disappearance of meiotic features—double-strand breaks in DNA (DSBs), synaptonemal complex (SC), and SC related structures—was striking. In wild-type diploids, the repair of meiotic DSBs during RTG was quick and efficient, resulting in homologous recombination. Kinetic analysis of double-strand breakage and recombination indicated that meiotic DSB formation precedes the commitment to meiotic levels of recombination. DSBs were repaired in RTG in dmc1, but not rad51 mutants, hence repair did not occur by the usual meiotic mechanism which requires the Dmc1 gene product. In haploids, DSBs were also repaired quickly and efficiently upon RTG, showing that DSB repair did not require the presence of a homologous chromosome. In all strains examined, SC and related structures were not required for DSB repair or recombination following RTG.

Conclusions:

At least two pathways of DSB repair, which differ from the primary meiotic pathway(s), can occur during RTG: One involving interhomologue recombination, and another involving sister-chromatid exchange. DSB formation precedes commitment to recombination. SC elements appear to prevent sister chromatid exchange in meiosis.

     

A new approach to teaching Normal Human Growth and Development

A new approach to teaching Normal Growth and Development to preclinical medical students is described. By using specially constructed multidisciplinary clinical simulations as training and evaluation devices, students were gradually and simultaneously exposed to: (1) subject matter; (2) the concept of multidisciplinary health care delivery; and (3) the objectives, strategies, and techniques of problem solving and diagnostic reasoning that characterize experienced physicians. The course, designed by a child psychiatrist and medical educators, was taught by a multidisciplinary teaching team drawn from faculty and health care representatives. Student evaluations of the course were favorable.     

Adenosine bronchial provocation with computerized wheeze detection in young infants with prolonged cough: correlation with long-term follow-up

BACKGROUND: Chronic cough in babies is often associated with bronchial hyperreactivity (BHR). The objective documentation of BHR in babies is difficult, and acoustic methods have been described (provocative concentration of a substance causing wheeze) for conducting bronchial provocation tests (BPTs). We conducted a study to evaluate automatic computerized wheeze detection (CWD) in determining BHR in young infants with prolonged cough, and its correlation with the subsequent development of wheezing. METHODS: Infants aged < 24 months with prolonged cough (ie, > 2 months) underwent acoustic BPTs with the response determined by CWD and auscultation by a physician. Telephone interviews with parents were conducted after 1 month and yearly for the next 3 years. RESULTS: A total of 28 infants who were 4 to 24 months old with prolonged cough were included in the study. Twenty of these infants (71.4%) had BHR as determined by a positive acoustic BPT result. In 11 of these 20 tests, the CWD occurred earlier, and in 9 tests it occurred at the same step as auscultation by a physician. Rhonchi or whistles often preceded wheezes. Seventeen of the 20 patients with BHR completed 3 years of follow-up. Of these, 14 had recurrent episodes of wheezing and shortness of breath, and 3 were well. Six of the eight adenosine-negative patients completed 3 years of follow-up and had no symptoms of BHR. CONCLUSIONS: Acoustic BPT is a technically feasible test for the detection of BHR in young infants. CWD provides an earlier detection of wheeze than stethoscope auscultation. In our group of infants, a positive acoustic BPT result had high correlation with symptoms compatible with BHR over the next 3 years.     

Nutritional Behavior as a Predictor of Early Success after Vertical Gastroplasty

Background: Patients' nutritional habits are seldom taken in account in planning surgery for clinically severe obesity. Our proposed hypothesis is that the patient's nutritional behavior may influence the outcome of bariatric surgery. Methods: The impact of nutritional behavior on the postoperative weight-loss was evaluated before and after bariatric surgery. A 6-month prospective consecutive case study was carried out on patients undergoing a Silastic ring vertical gastroplasty (SRVG). Patients were interviewed and examined before and at 1, 3 and 6 months after surgery. Demographic and clinical data were collected from the patients' medical charts. Nutritional data collected from a self-filled questionnaire included information on hunger and satiety perception, nutritional behavior (intake, eating habits and maximum consistency of consumed food) and concomitant symptoms. Results: The sample included 69 patients: 56 were women (81%); average age was 32 years (range 18 50). Average preoperative BMI was 43.4 ± 5.3 kg/m² (range 35-58). 6 months after surgery, BMI was 30.3 ± 3.8 kg/m² (range 21-42). Weight loss forecast models showed a statistically significant role of factors related to: anthropometrical preoperative data, hunger perception, prevalence of oral mucosal sore, and nutritional behavior. Conclusion: The short nutrition outcomes after gastric restrictive surgery were looked at, with their impact on weight-loss success. The Eating Status concept should be part of a systematic profiling of morbidly obese patients for preoperative nutritional behavior and postoperative nutritional education, to achieve the best comprehensive treatment in regard to weight loss and quality of life.     

The effect of early treatment in children with chronic hepatitis

BACKGROUND: The aim of this study was to compare the efficacy of interferon alpha (IFN) or IFN and ribavirin (IFN+RIB) combination therapy in children with chronic hepatitis C (CHC). Most children were infected during treatment for pediatric malignancies. PATIENTS AND METHODS: We reviewed the charts of 20 patients (11 boys and 9 girls) aged 10.6 +/- 3.7 years with CHC who were treated between 1995 and 2001. Seven patients diagnosed with CHC before 1998 were treated with 3 million units of IFN three times weekly for 6 to 12 months. Thirteen children diagnosed after 1998 were treated with 3 million units of IFN three times weekly plus 15 mg/kg of ribavirin daily for 6 months (IFN+RIB). RESULTS: Demographic and clinical characteristics were not different between the two treatment groups. A sustained complete response defined as serum alanine aminotransferase normalization and hepatitis C virus RNA clearance at 6 and 12 months after termination of treatment occurred in three of seven children (43%) treated with IFN monotherapy compared with 7 of 12 children (54%) in the group treated with IFN+RIB combination therapy (not significant). The only difference between responders and nonresponders was the duration of infection before the initiation of therapy, which was significantly shorter in responders (1 +/- 0.3 vs. 5.6 +/- 2.2; P = 0.001). CONCLUSIONS: In this small cohort of children with CHC, early initiation of antiviral treatment was associated with a sustained response rate independent of treatment type. Regular follow-up of children at risk of acquiring hepatitis C virus infection should assist in the early diagnosis. Early initiation of antiviral treatment may improve the rate of sustained response.     

Spread of Streptococcus pneumoniae and antibiotic-resistant S. pneumoniae from day-care center attendees to their younger siblings

A prospective study was conducted to determine the association between pneumococcal carriage among 36 infants and young toddlers cared for at home and carriage among their older siblings who attended 8 day-care centers (DCCs); 71 pneumococcal strains acquired by the younger siblings were compared with those present in the DCCs for 6 months. In 76% of cases, > or =1 strain identical by serotype and antibiogram was isolated in the older siblings' DCC versus 32%-63% in all other DCCs (P<.001). When phenotypically identical strains were compared by pulsed-field gel electrophoresis, the similarity between strains from older siblings' DCCs and the younger siblings' isolates was striking. This was not found when isolates from other DCCs were compared. Vaccinating DCC attendees with a 7-valent pneumococcal conjugate vaccine may play a key role in controlling the spread of antibiotic-resistant pneumococci, because the most resistant serotypes are included in the vaccine.     

Development of a food frequency questionnaire (FFQ) for an elderly population based on a population survey

Older people have different eating patterns than their younger counterparts, although in most nutritional studies of older populations, food frequency questionnaires (FFQ) that were developed and validated for the general adult population are used. In this paper, we present the advantages of developing an FFQ for an older population based on a population survey. A random sample of the Negev's (Southern Israel) Jewish population > or = 35 y old was recruited and interviewed for their dietary intake using 24-h recalls. Foods eaten were aggregated into conceptually similar groups and entered into stepwise regression models to predict variation in nutrient intake. We interviewed 796 people age 35-64 y and 377 people > or = 65 y old for the study. Significantly more items were required to reach 80% between-person variability for zinc, magnesium, vitamin E and protein for the elderly compared with the younger age group. Portion sizes of most items consumed by the elderly were smaller compared with the Israeli Ministry of Health portion sizes booklet and the younger age group's intake estimates. The nutrient values assigned for each line based on a weighted mean of the intake of the elderly were different from those using the most frequently used item. The above findings highlight some of the advantages of developing an FFQ for an older population based on a population survey. Further studies are required to compare the validity of existing tools adapted for the elderly to those developed on the basis of population surveys.     

Anti-inflammatory effects of moxifloxacin on activated human monocytic cells: inhibition of NF-kappaB and mitogen-activated protein kinase activation and of synthesis of proinflammatory cytokines

We previously showed that moxifloxacin (MXF) exerts protective anti-inflammatory effects in immunosuppressed mice infected with Candida albicans by inhibiting interleukin-8 (IL-8) and tumor necrosis factor alpha (TNF-alpha) production in the lung. Immunohistochemistry demonstrated inhibition of nuclear factor (NF)-kappaB translocation in lung epithelium and macrophages in MXF-treated mice. In the present study we investigated the effects of MXF on the production of proinflammatory cytokines (i.e., IL-8, TNF-alpha, and IL-1beta) by activated human peripheral blood monocytes and THP-1 cells and analyzed the effects of the drug on the major signal transduction pathways associated with inflammation: NF-kappaB and the mitogen-activated protein kinases ERK and c-Jun N-terminal kinase (JNK). The levels of IL-8, TNF-alpha, and IL-1beta secretion rose 20- and 6.7-fold in lipopolysaccharide (LPS)-activated monocytes and THP-1 cells, respectively. MXF (5 to 20 microg/ml) significantly inhibited cytokine production by 14 to 80% and 15 to 73% in monocytes and THP-1 cells, respectively. In THP-1 cells, the level of NF-kappaB nuclear translocation increased fourfold following stimulation with LPS-phorbol myristate acetate (PMA), and this was inhibited (38%) by 10 microg of MXF per ml. We then assayed the degradation of inhibitor (I)-kappaB by Western blotting. LPS-PMA induced degradation of I-kappaB by 73%, while addition of MXF (5 microg/ml) inhibited I-kappaB degradation by 49%. Activation of ERK1/2 and the 46-kDa p-JNK protein was enhanced by LPS and LPS-PMA and was significantly inhibited by MXF (54 and 42%, respectively, with MXF at 10 microg/ml). We conclude that MXF suppresses the secretion of proinflammatory cytokines in human monocytes and THP-1 cells and that it exerts its anti-inflammatory effects in THP-1 cells by inhibiting NF-kappaB, ERK, and JNK activation. Its anti-inflammatory properties should be further assessed in clinical settings.