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Am J Physiol Cell Physiol. 2000 Nov;279(5):C1345-50.
Substrate flexibility regulates growth and apoptosis of normal but not transformed cells.
Wang HB, Dembo M, Wang YL.
Department of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
One of the hallmarks of oncogenic transformation is anchorage-independent growth (27). Here we demonstrate that responses to substrate rigidity play a major role in distinguishing the growth behavior of normal cells from that of transformed cells. We cultured normal or H-ras-transformed NIH 3T3 cells on flexible collagen-coated polyacrylamide substrates with similar chemical properties but different rigidity. Compared with cells cultured on stiff substrates, nontransformed cells on flexible substrates showed a decrease in the rate of DNA synthesis and an increase in the rate of apoptosis. These responses on flexible substrates are coupled to decreases in cell spreading area and traction forces. In contrast, transformed cells maintained their growth and apoptotic characteristics regardless of substrate flexibility. The responses in cell spreading area and traction forces to substrate flexibility were similarly diminished. Our results suggest that normal cells are capable of probing substrate rigidity and that proper mechanical feedback is required for regulating cell shape, cell growth, and survival. The loss of this response can explain the unregulated growth of transformed cells.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029281&dopt=Abstract
Am J Physiol Cell Physiol. 2000 Nov;279(5):C1432-42.
Agonist-induced isometric contraction of smooth muscle cell-populated collagen gel fiber.
Oishi K, Itoh Y, Isshiki Y, Kai C, Takeda Y, Yamaura K, Takano-Ohmuro H, Uchida MK.
Department of Pharmacology, Meiji Pharmaceutical University, Tokyo 204-8588, Japan. ioshiky-pharm.ac.jp
String-shaped reconstituted smooth muscle (SM) fibers were prepared in rectangular wells by thermal gelation of a mixed solution of collagen and cultured SM cells derived from guinea pig stomach. The cells in the fiber exhibited an elongated spindle shape and were aligned along the long axis. The fiber contracted in response to KCl (140 mM), norepinephrine (NE; 10(-7) M), epinephrine (10(-7) M), phenylephrine (10(-6) M), serotonin (10(-6) M), and histamine (10(-5) M), but not acetylcholine (10(-5) M). Phentolamine (10(-7) M) produced a parallel rightward shift of the NE dose-response curve. Moreover, NE-induced contraction was partially inhibited by nifedipine and completely abolished by the intracellular Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester, the myosin light chain kinase inhibitor ML-9, the Rho kinase inhibitor Y-27632, and papaverine. A [(3)H]quinuclidinyl benzilate binding study revealed that the loss of response to acetylcholine was due to the loss of muscarinic receptor expression during culture. The expression of contractile proteins in the fibers was similar to that in cultured SM cells. These results suggest that, although the fiber is not a model for fully differentiated SM, contractile mechanisms are maintained.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029291&dopt=Abstract
Am J Respir Crit Care Med. 2000 Oct;162(4 Pt 1):1308-13.
Airway hyperresponsiveness, inflammation, and subepithelial collagen deposition in recently diagnosed versus long-standing mild asthma. Influence of inhaled corticosteroids.
Boulet LP, Turcotte H, Laviolette M, Naud F, Bernier MC, Martel S, Chakir J.
Institut de Cardiologie et de Pneumologie de L'Universite Laval, H opital Laval, Sainte-Foy, Quebec, Canada. lpbouleed.ulaval.ca
This study aimed at documenting airway inflammation and subepithelial collagen deposition in patients using only inhaled beta(2)-agonists with either recently diagnosed asthma (RDA: </= 2 yr, n = 16) or long-standing asthma (LSA: >/= 13 yr, n = 16) and at the influence of an intense inhaled corticosteroid (ICS) treatment on these parameters, in relation to changes in airway responsiveness. Patients had a methacholine inhalation test and a bronchoscopy with bronchial biopsies before and after an 8-wk treatment with inhaled fluticasone propionate (FP), 1,000 microgram/day. Baseline FEV(1) (mean +/- SEM) was normal and similar in both groups (RDA: 98.1 +/- 2.7, LSA: 94.5 +/- 4.6%). Geometric mean methacholine PC(20) was lower in LSA than in RDA (0.44 versus 3.37 mg/ml) at baseline and improved similarly by 1.85 and 1.86 double concentrations with FP treatment. PC(20) normalized (>/= 16 mg/ml) in five patients with RDA and two patients with LSA. Baseline mean bronchial cell counts (per mm(2) connective tissue surface) for CD3(+), CD4(+), CD8(+), CD25(+), EG1(+), CD45ro(+), and AA1(+) cells were similar in both groups. With FP, EG1(+) (p < 0.001), EG2(+) (p = 0.018), and AA1(+) counts (p = 0.009) decreased significantly in both groups while CD45ro(+) (p = 0.02) counts decreased only in LSA. Baseline type 1 and type 3 collagen deposition underneath the basement membrane was similar in RDA and LSA and did not change significantly after FP. This study shows that recent compared to long-standing mild asthma is associated with a similar degree of airway inflammation and subepithelial fibrosis, and a similar improvement in airway hyperresponsiveness after 8 wk on high-dose ICS. It also indicates that once asthma becomes symptomatic, airway responsiveness cannot normalize in most subjects over such a time period, even with a high dose of ICS.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029336&dopt=Abstract
Am J Respir Crit Care Med. 2000 Oct;162(4 Pt 1):1355-60.
Balance of matrix metalloprotease-9 and tissue inhibitor of metalloprotease-1 from alveolar macrophages in cigarette smokers. Regulation by interleukin-10.
Lim S, Roche N, Oliver BG, Mattos W, Barnes PJ, Fan Chung K.
National Heart and Lung Institute, Imperial College School of Medicine, London, United Kingdom.
An imbalance between proteases and antiproteases may play a role in emphysema, which is characterized by increased degradation of extracellular matrix, and in airway remodeling in chronic bronchitis and asthma, in which there is increased collagen deposition. We assessed the effect of smoking on release of matrix metalloprotease-9 (MMP-9) and of its inhibitor, tissue inhibitor of metalloprotease-1 (TIMP-1), from alveolar macrophages, and determined the effects of proinflammatory (interleukin [IL]-1beta and lipopolysaccharide [LPS]) and antiinflammatory (IL-10) stimuli on the release of MMP-9 and TIMP-1. We performed bronchoalveolar lavage in 11 smokers and 11 nonsmokers, and cultured airway macrophages in the presence of control medium, IL-1beta, and LPS. Airway macrophages from smokers released greater amounts of MMP-9 and TIMP-1 at baseline and in response to IL-1beta and LPS than did those of nonsmokers. Airway macrophages from smokers produced more TNF-alpha and IL-10. IL-10 increased TIMP-1 release without modifying that of MMP-9, leading to a decrease in the MMP-9 to TIMP-1 ratio. Anti-IL-10 antibody had no effect on MMP-9 production induced by LPS. We conclude that the release of proteases and antiproteases by airway macrophages is increased in cigarette smokers, and can be regulated by exogenous IL-10.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029344&dopt=Abstract
Am J Respir Crit Care Med. 2000 Oct;162(4 Pt 1):1569-76.
Changes in extracellular matrix and tissue viscoelasticity in bleomycin-induced lung fibrosis. Temporal aspects.
Ebihara T, Venkatesan N, Tanaka R, Ludwig MS.
Meakins-Christie Laboratories, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada.
Bleomycin-induced lung fibrosis results in changes in tissue mechanical properties due to alterations in the extracellular matrix (ECM). How oscillatory mechanics and changes in the matrix evolve over time has not been addressed. Sprague-Dawley rats were instilled with bleomycin sulfate (BM) (1.5 U) intratracheally; control animals (C) received saline. At 7, 14, and 28 d after BM, parenchymal strips (7 x 2 x 2 mm) were obtained and strips suspended in a Krebs-filled organ bath. One end of the strip was attached to a force (F) transducer and the other to a lever arm that effected sinusoidal length (L) oscillations. Strips were oscillated at varying amplitudes (1, 3, and 10% of resting L) and frequencies (f = 0.3, 1, 3, and 10 Hz) at an operating stress of 2 kPa. Resistance (R) and elastance (E) were estimated by fitting changes in F and L to the equation of motion. Hysteresivity (eta) was calculated as eta = (R/E) 2pif. Strips were then fixed for morphological study of collagen, elastic fibers, and the small proteoglycans (PGs), biglycan and fibromodulin (FM). R and E were significantly greater and eta significantly less in BM versus C strips (p < 0.001). The increase in R and E peaked at 14 d after BM; the decrement in eta was maximal at Day 7. Biglycan was increased in BM lung strips at all time points, FM and elastic fibers were increased at 14 and 28 d, and collagen was increased at 28 d only. Hence, changes in mechanics were maximal before collagen content had increased. In addition, we demonstrated a significant correlation between biglycan and all mechanical parameters. These data suggest that changes in PGs may be critical in determining changes in lung tissue viscoelastic behavior in this fibrosis model
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11029378&dopt=Abstract
Hair loss is a problem in modern soceity. Examining the factors of hair growth may
shed light on how hair loss might occur.
How long can hair grow before it stops growing eventually if it does?
Given that the hair growth rate is quite uniform and constant, somewhere between 0.3-0.5 millimeters per day, it's believed that the length of anagen, the growth phase, differs among individuals, and this is the major determinant to the maximum hair length. For some individuals, anagen may last ten years. Of course the length of the anagen is governed by genes, and the genetic background of the individuals. Non-genetic factors such as nutritional condition, weather, seasonal changes (hair may grow a bit faster during winter), taking medications, health condition may of course influence the rate of
hair growth as well as
The shape of the hair, straight or curly, is dependent on the shape of the follicle. A circular or round hair follicle would generate straight hair, while the follicle with oval or elliptical shapes (in its cross-section) would produce a curly hair.
DHEA has been suggested to provide numerous potential benefits. DHEA (or dehydroepiandrosterone) is converted into androgens (male hormones)
or estrogens (female hormones) in the cells.
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