Robust growth of Escherichia coli

The quantitative study of the cell growth has led to many fundamental insights in our understanding of a wide range of subjects, from the cell cycle to senescence. Of particular importance is the growth rate, whose constancy represents a physiological steady state of an organism. Recent studies, however, suggest that the rate of elongation during exponential growth of bacterial cells decreases cumulatively with replicative age for both asymmetrically and symmetrically dividing organisms, implying that a "steady-state" population consists of individual cells that are never in a steady state of growth. To resolve this seeming paradoxical observation, we studied the long-term growth and division patterns of Escherichia coli cells by employing a microfluidic device designed to follow steady-state growth and division of a large number of cells at a defined reproductive age. Our analysis of approximately 10(5) individual cells reveals a remarkable stability of growth whereby the mother cell inherits the same pole for hundreds of generations. We further show that death of E. coli is not purely stochastic but is the result of accumulating damages. We conclude that E. coli, unlike all other aging model systems studied to date, has a robust mechanism of growth that is decoupled from cell death.

Genetic, epigenetic and posttranslational mechanisms of aging

Gerontological experimentation is and was always strongly influenced by "theories". The early decades of molecular genetics inspired deterministic thinking, based on the "Central Dogma" (DNA --> RNA --> Proteins). With the progress of detailed knowledge of gene-function a much more complicated picture emerged. Regulation of gene-expression turned out to be a highly complicated process. Experimental gerontology produced over the last decades several "paradigms" incompatible with simple genetic determinism. The increasing number of such detailed experimental "facts" revealed the importance of epigenetic factors and of posttranslational modifications in the age-dependent decline of physiological functions. We shall present in this review a short but critical analysis of genetic and epigenetic processes applied to the interpretation of the more and more precisely elucidated experimental paradigms of aging followed by some of the most relevant aging-mechanisms at the post-translational level, the posttranslational modifications of proteins such as the Maillard reaction, the proteolytic production of harmful peptides and the molecular mechanisms of the aging of elastin with the role of the age-dependent uncoupling of the elastin receptor, as well as the loss of several other receptors. We insist also on the well documented influence of posttranslational modifications on gene expression and on the role of non-coding RNA-s. Altogether, these data replace the previous simplistic concepts on gene action as related to aging by a much more complicated picture, where epigenetic and posttranslational processes together with environmentally influenced genetic pathways play key-roles in aging and strongly influence gene expression.

Increased elastase and cathepsin G activity in activated lymphocytes from aged patients: role of denutrition and dementia

Elastase and cathepsin G activities in cell-lysates and in culture supernates of activated human lymphocytes (incubated for 96 h in the presence of 5 microg/ml of phytohemagglutinin with/without 2 microg/ml of elastin peptides) of 25 old, hospitalized patients (average age: 88.48+/-6.81 years), suffering from vascular-type dementia or denutrition were examined, in comparison with samples of 11 young, healthy donors. Elastase activity was found to be significantly elevated, the excreted fraction of elastase activity strongly decreased in lymphocytes of these patients as compared to young donors. The highest values of enzymatic activities in the culture supernates and also in the cell-lysates were obtained for samples of undernourished patients. Lymphocytes from young, healthy donors showed a significant increase both of excreted and intracellular elastase activity when cultured in presence of elastin peptides. The activation of elastolytic activity by elastin peptides decreased with the age of donors. The results for cathepsin G are essentially similar but the differences between age-categories are less pronounced than for elastase activity.

Receptors and aging: dedicated to the memory of Paul Ehrlich for the 100th anniversary of his Nobel Prize

The initiation and evolution of the receptor concept and its application in pharmacology can be traced back to Paul Ehrlich's original experiments. Since several decades the receptor concept is in the foreground of cell biology and pharmacology. We present here a short reminder of Ehrlich's concepts on receptor action, its evolution and modifications as a result of increasing life expectancy of human societies. Results obtained by several teams on the age-dependent modifications of receptor function are reviewed with special emphasis on the age-dependent loss of receptors and of uncoupling of receptors from their intracellular transmission pathway. As a special example we summarize our results on the elastin receptor and its age-dependent modifications. These modifications result in the loss of the physiologically helpful functions mediated by this receptor, such as vasodilation by coupling with the inducible nitric oxide synthase (iNOS)-inhibition of cellular cholesterol synthesis and modulation of free radical production by inhibition of the guanine nucleotide binding protein (Gi protein)-mediated transmission pathway. Only the harmful effects such as free radical release and up-regulation of elastase production remain in "old" cells. The age-dependent modifications of receptor function play an important role in the increasing frequency and severity of age-related diseases such as athero-arteriosclerosis and emphysema as well as the loss of hormone- and drug actions. These processes and their inhibition or correction represent a new challenge for cellular pharmacology.

Aging in the 21st century

In this introductory article, a rapid overview is presented of the recent increase of life expectancy and its limitations mainly by unhealthy living habits: overeating, fast food, lack of exercise. The strong increase of obesity worldwide with its metabolic consequences might well limit or even decrease human life expectancy. The part of the population over 65 who have access to "anti-aging medicine" represents however another challenge to experimental and clinical gerontology, further discussed in later articles of this issue.

Clinical features and outcome in primary breast sarcomas (BS): Analysis of a single-institution experience

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Background: BS are characterised by local spread and recurrence. Controversy remains about local and adjuvant treatment. The objective of this retrospective study was to analyze clinical and pathological prognostic factors influencing the outcome of BS patients. Methods: We analyzed clinicopathological variables, treatment and outcome of 33 BS patients treated at our institution from 1966 to 2007. A single pathologist reviewed pathologic diagnoses. Kaplan Meier method was used to evaluate outcome. Mean age: 44 years (20–82y. Tumor size 57 (0–230) mm. Pathology: 17 cistosarcoma phylodes (CPh), 9 angiosarcoma, 2 extraesqueletical osteosarcoma, 2 fibrosarcomas, 1 liposarcoma, 1 leiomiosarcoma, 1 malignant fibrous histiocitoma (2.9%). Low-grade in 12, high-grade in 15 pts. Mastectomy in all but 8 patients. Adjuvant chemotherapy and radiotherapy in 9 and 7 patients. Pathological stage I- 12%, II- 65%, III- 9%, IV-3% Results: Median follow-up 71 (5–239) months. Median survival 160 months. Survival was 83%, 74% and 59% at 5, 10 and 15 year. 5/8 (62.5%) local excision patients needed rescue surgery due to local progression. 8/25 (32%) mastectomy patients progressed Local recurrence in 9 pts, distant 4 pts (radical rescue surgery in 10 pts). 7 pts death only 1 phyllodes. Mean 15-year survival for CPh was 169 vs 124 months for other histologies (p 0.06). In the univariate analysis we didn't found statistical differences according to clinical & pathological factors, stage and recurrence, on OS or PFS. Conclusions: CPh have better prognosis than other BS although its stage or size tends to be higher. Radical surgery in BS should be always considered as first treatment option. High-grade non-phylodes BS types may be considered for adjuvant chemotherapy although there were non-statistical differences in OS.

No significant financial relationships to disclose.

Circulating chromogranin A as a marker for poor-prognosis hormone refractory prostate cancer without neuroendocrine features: Prospective analyses of a cohort of patients

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Background: Some patients may develop hormone refractory prostate (HRPC) cancer with neuroendocrine features, although they were not recognizable in the initial biopsy. Serum chromogranin is a marker for tumors with neuroendrocrine differentiation. Purpose: To analyze if serum levels of chromogranin A may identify poor prognosis HRPC patients in patients without neuroendocrine features in the initial biopsy. Methods: Circulating chromogranin A was prospectively analyzed in 34 patients when they were diagnosed under the standard criteria of HRPC. A patient was considered to have higher than normal levels of serum chromogranin if levels were above 100 ug/L. Patients were also assessed for serum PSA, enolase, serum alkaline phosphatase, albumin, and hemoglobin. Results were correlated with clinical prognostic factors as ECOG, PSA double time and Gleason score. We analyzed the time to hormone-refractory disease since diagnosis, and overall survival, as well as pattern of relapse (visceral vs. nonvisceral disease). Results: Median age was 63 (49–85). Median PSA was 33 (0.04–1455). At baseline, 16 patients were chromogranin-negative (46%), and 18 patients were chromogranin-positive (54). Chromogranin A did not correlate with either enolase or PSA. Patients with positive (>100 ug/L) had stadistically significant lower levels of hemoglobine (13.8 vs 12.3), and a trend to have more visceral disease vs locoregional diasease or bone metastases, a lower albumine level (39.85 vs 45.05), higher alkaline phosphatase (221 vs 111), and LDH (1,914.5 vs 415). In this group of patients, we did not find differences in PSA double time, time to hormone-refractory disease or Gleason score. Conclusions: The analysis of this cohort of patients suggests that serum chromogranine A correlates with other known adverse prognosis factors of survival in prostate cancer patients.

No significant financial relationships to disclose.

Fault-Tolerant Text Data Compression Algorithms

There has been an unparalleled explosion of textual information flow over the internet through electronic mail, web browsing, digital library and information retrieval systems, etc. Since there is a persistent increase in the amount of data that needs to be transmitted or archived, the importance of data compression is likely to increase in the near future. Virtually, all modern compression methods are adaptive models and generate variable-bit-length codes that must be decoded sequentially from beginning to end. If there is any error during transmission, the entire file cannot be retrieved safely. In this article we propose few fault-tolerant methods of text compression that facilitate decoding to begin with any part of compressed file not necessarily from the beginning. If any sequence of one or more bytes is changed during transmission of compressed file due to various reasons, the remaining data can be retrieved safely. These algorithms also support reversible decompression.

Multidrug-resistant tuberculosis: a review of the 23 cases treated by the Saint-Pierre University Hospital (Brussels)

For about fifteen years, Belgium, as other developed countries, has been confronted with multidrug-resistant tuberculosis (MDR-TB). The treatment of MDR-TB is complex, associating several antibiotics and causing multiple adverse effects. The aim of this study is to report our experience with MDR-TB at the Saint-Pierre University Hospital in Brussels.