Hypergravity: Its effect on the estrous cycle of rats

Summary Hypergravity affects the estrous cycle of rats. It is prolonged by a force of 1.39G–1.65G, and shows irregularities between 1.02 and 1.19G. Rats centrifuged for 40 days and returned to normal gravity presented a normal estrous pattern.     

TRAIL promotes the survival,migration and proliferation of vascular smooth muscle cells

Human and rat primary sub-cultured vascular smooth muscle cells (VSMCs) showed clear expression of the death receptors TRAIL-R1 and TRAIL-R2; however, recombinant soluble TRAIL did not induce cell death when added to these cells. TRAIL tended to protect rat VSMCs from apoptosis induced either by inflammatory cytokines tumor necrosis factor- + interleukin-1 + interferon- or by prolonged serum withdrawal, and promoted a significant increase in VSMC proliferation and migration. Of note, all the biological effects induced by TRAIL were significantly inhibited by pharmacological inhibitors of the ERK pathway. Western blot analysis consistently showed that TRAIL induced a significant activation of ERK1/2, and a much weaker phosphorylation of Akt, while it did not affect the p38/MAPK pathway. Taken together, these data strengthen the notion that the TRAIL/TRAIL-R system likely plays a role in the biology of the vascular system by affecting the survival, migration and proliferation of VSMCs.Received 6 May 2004; received after revision 7 June 2004; accepted 8 June 2004     

Inhibitory effect of direct current on cell division and cell proliferation

Summary Direct current (0.1 to 0.2 mA) fully inhibited cell division and cell proliferation at the site of the non-polarizing anode, probably due to electrolysis and electro-osmotic processes affecting the chromatin of the cell nucleus. It resulted in cessation of the growth of the root-germs of the onion. Plant germs lost their ability to germinate 18–20 h after the application of the weak direct current.     

Acceleration of crypt cell proliferation by acoustic stimuli

Summary Cell proliferation rates in the bases of the crypts of Lieberkuhn in the jejunum of rat were measured using a stathmokinetic technique. In rats subjected to recurring loud noise cell proliferation was more rapid than in rats not subjected to the noise.     

Antizyme inhibitor: mysterious modulator of cell proliferation

In contrast to the considerable interest in the oncogene ornithine decarboxylase (ODC) and in the family of antizymes with regard to cell proliferation and tumorigenesis, the endogenous antizyme inhibitor (AZI) has been less well studied. AZI is highly homologous to the enzyme ODC but does not possess any decarboxylase activity. Elevated ODC activity is associated with most forms of human malignancies. Antizymes bind ODC, inhibit ODC activity and promote the ubiquitin-independent degradation of ODC. Consequently they are proposed as tumor suppressors. In particular, the most studied member of the antizyme family, antizyme 1, has been demonstrated to play a role in tumor suppression. AZI inactivates all members of the antizyme family, reactivates ODC and prevents the proteolytic degradation of ODC, which may suggest a role for AZI in tumor progression. Received 9 December 2005; received after revision 13 April 2006; accepted 1 June 2006     

How retinoids regulate breast cancer cell proliferation and apoptosis

Breast cancer still remains a major problem in its incidence, morbidity and mortality; therefore, more effective strategies for its prevention are urgently needed. Retinoids, natural and synthetic derivatives of vitamin A, possess antiproliferative and proapoptotic properties, making them a promising class of chemopreventive agents against breast cancer. The efficacy of all-trans retinoic acid, 9-cis-retinoic acid, LGD1069 (Targretin, bexarotene), and N-(4-hydroxyphenyl)retinamide (fenretinide) as breast cancer chemopreventive agents is being studied. A better understanding of the molecular mechanisms of action of these agents should lead to improvements in their clinical application. In this review, we discuss the mechanisms by which retinoids exert their antiproliferative and apoptotic effects in breast cancer cells.Received 5 January 2004; received after revision 9 February 2004; accepted 12 February 2004     

Recombinant expression of perchloric acid-soluble protein reduces cell proliferation

Perchloric acid-soluble protein (PSP) may play an important role in the regulation of cellular physiological functions because it has been highly conserved throughout evolution; however, this role has not been well elucidated. In previous reports, we suggested that PSP regulates cell proliferation. In this study, we examined the effect of PSP expression on proliferation of the normal rat kidney cell line NRK-52E, the rat hepatocyte cell line RLN-10, and the rat hepatoma cell line dRLh-84. Cells transfected with pcDNA-sense-PSP (pcDNA-S-PSP) over-expressed PSP mRNA and protein, and cell proliferation of the transfected cells was suppressed compared with that of cells transfected with pcDNA-empty (pcDNA-E). Cell viability of pcDNA-S-PSP-transfected cells was similar to that of pcDNA-E-transfected cells. Thus, over-expression of PSP suppresses cell proliferation without any influence on cell viability. These findings are the first to report an inhibitory activity of PSP on cell proliferation. Received 27 April 2001; received after revision 8 June 2001; accepted 8 June 2001     

Inhibition of cell proliferation caused by oncogenic DNA-polyoma virus

Zusammenfassung Eine eindrucksvolle, über 30 Tage beobachtete Hemmung der Zellproliferation in Niere und Leber wird verursacht durch Infektion neugeborener Ratten mit unserem PV-Stamm. Dieses Phänomen ist bei adult infizierten Ratten nur im Nierenmark nachweisbar und fehlt bei Mäusen ganz.

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This investigation was supported in part by grants from the Deutsche Forschungsgemeinschaft (Grant No. Ge 121/10).     

A unifying model of the cell proliferation emphasizing plasma membrane fluxes

The regulation of cellular growth and proliferation is perhaps the most investigated and elusive problem in cell biology and seems to be possible to solve from almost any angle of study chosen. Among the non-systemic factors that have been discussed are genetic damage, genomic control, regulation by stimulatory and inhibitory peptide factors such as EGF, chalones, and fibronectin, protein kinase activation with tyrosine phosphorylation, adenylylcyclase and cAMP, cGMP, membrane perturbations and specifically in tumours the failure of the Pasteur effect in control of glycolysis, excessive membrane ATPase activity, and excessive hydrolytic and proteolytic activities at the cell surface. This article focuses on the central role of fluxes within the plasma membrane and re-examines the possibility that changes of flux of metabolites, ions, and reducing equivalents may be the common denominator regulating cellular proliferation.     

Tissue-specific inhibition of embryonic neural cell proliferation by rat brain extract

Summary The effect of rat brain tissue extract on the proliferative activity of chicken embryonic neural tube and other tissues was studied. Only tissue-specific inhibitory action was found to be similar to substances of the chalone group.     

Small lymphocyte production and lymphoid cell proliferation in mouse bone marrow

In mice given 3H-thymidine systemically during temporary circulatory occlusion of one hind limb, comparison of the labeling of rapidly-renewing small lymphocytes in the tibial marrows demonstrated that these cells were locally produced. Labeling by 3H-thymidine infusion revealed that many marrow large lymphoid cells, presumptive small lymphocyte progenitors, had a marked proliferative activity and rapid turnover which varied according to cell size, was maximal in young mice and declined with increasing age.     

A unifying model of the cell proliferation emphasizing plasma membrane fluxes

Summary The regulation of cellular growth and proliferation is perhaps the most investigated and elusive problem in cell biology and seems to be possible to solve from almost any angle of study chosen. Among the non-systemic factors that have been discussed are genetic damage, genomic control, regulation by stimulatory and inhibitory peptide factors such as EGF, chalones, and fibronectin, protein kinase activition with tyrosine phosphorylation, adenylylcyclase and cAMP, cGMP, membrane perturbations and specifically in tumours the failure of the Pasteur effect in control of glycolysis, excessive membrane ATPase activity, and excessive hydrolytic and proteolytic activities at the cell surface. This article focusses on the central role of fluxes within the plasma membrane and re-examines the possibility that changes of flux of metabolites, ions, and reducing equivalents may be the common denominator regulating cellular proliferation.