New spectrophotometric method for the determination of proline in tissue hydrolyzates

Bergman, I.; Loxley, Roy

doi:10.1021/ac60289a036

Cited by 95 publications

(45 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Cells from 2.0-ml samples were sedimented rapidly (1 min) with an Eppendorf tabletop centrifuge. The supernatant culture fluid was decanted and used to measure the extracellular proline level by the method of Bergman and Loxley (2). For the determination of the intracellular proline levels, the cell pellets were suspended in 0.5 ml of methanol, the insoluble material was removed by centrifugation, and the supernatant fluid was decanted, evaporated under a stream of N2 gas, and analyzed for proline content by gas chromatography according to the method of Rhodes et al (18).…”

Section: Methodsmentioning

confidence: 99%

Regulation of cytoplasmic proline levels in Salmonella typhimurium: effect of osmotic stress on synthesis, degradation, and cellular retention of proline

Csonka

1988

J Bacteriol

View full text Add to dashboard Cite

I investigated the effects of osmotic stress on the synthesis and catabolism of proline in Salmonella typhimurium by measuring the intracellular and extracellular proline levels in various strains. In the wild-type strain, exposure to 0.8 M NaCl did not cause a significant change in the intracellular proline level; however, it brought about a 6.5-fold increase in the intracellular glutamate pool size. These results indicate that 'y-glutamyl kinase is inhibited by proline in wild-type cells in media of normal or elevated osmolarity. I also tested whether proline is subject to turnover in cells wild type with respect to the enzymes of the proline degradation pathway. In strains that were wild type for proline biosynthesis, the loss of the proline catabolic enzymes, due to put4 mutations, did not result in a statistically significant increase in the intracellular proline levels. Therefore, in the wild-type strain, proline turnover does not seem to be important for control of the intracellular proline levels. However, in a proline-overproducing mutant, a putA lesion caused a threefold increase in the intracellular proline level and a 6.5-fold increase in the extraceilular proline level, indicating that proline is subject to turnover in the overproducing mutant. The proline-overproducing mutants excreted large quantities of the proline into the culture medium; osmotic stress altered the partitioning of proline such that the ratio of intracellular to extracellular levels of proline increased with increased osmotic stress. The increased cellular retention of proline in media of high osmolarity is probably due to the functioning of the ProP and ProU proline transport systems, which are stimulated under conditions of osmotic stress.In bacteria, proline is synthesized from glutamate by four reactions: (i) glutamate + ATP --y-glutamyl phosphate + ADP, (ii) -y-glutamyl phosphate + NADPH --y-glutamyl semialdehyde + NADP, (iii) -y-glutamyl semialdehyde <-+ A'-pyrroline-5-carboxylate + H20, and (iv) A1-pyrroline-5-carboxylate + NADPH -* proline + NADP (7, 12). The first, second, and fourth reactions are catalyzed by the enzymes -y-glutamyl kinase, -y-glutamyl phosphate reductase, and A'-pyrroline-5-carboxylate reductase, which are specified in members of the family Enterobactericeae by the proB+, proA+, and proC+ genes, respectively. The third reaction, the cyclization of y-glutamyl semialdehyde to Al-pyrroline-5-carboxylate, is spontaneous. The catabolism of proline entails two oxidation steps to glutamate via 17). In enteric bacteria, these reactions are mediated by a bifunctional protein with proline dehydrogenase (oxidase) and A1-pyrroline-5-carboxylate dehydrogenase activities, encoded in the putA+ gene (17).

show abstract

Section: Methodsmentioning

confidence: 99%

Regulation of cytoplasmic proline levels in Salmonella typhimurium: effect of osmotic stress on synthesis, degradation, and cellular retention of proline

Csonka

1988

J Bacteriol

View full text Add to dashboard Cite

show abstract

“…LV collagen was quantified from the hydroxyproline (OH-proline) concentration by modified method, as described previously (1,13). All tissue samples (ϳ100 mg wet weight) were taken from the same area of the LV wall.…”

Section: Biochemical Analysismentioning

confidence: 99%

MicroRNAs 29 are involved in the improvement of ventricular compliance promoted by aerobic exercise training in rats

Soci

Fernandes

Hashimoto

et al. 2011

Physiological Genomics

163

131

View full text Add to dashboard Cite

MiRNAs regulate cardiac development, hypertrophy, and angiogenesis, but their role in cardiac hypertrophy (CH) induced by aerobic training has not previously been studied. Aerobic training promotes physiological CH preserving cardiac function. This study assessed involvement of miRNAs-29 in CH of trained rats. Female Wistar rats (n ϭ 7/group) were randomized into three groups: sedentary (S), training 1 (T1), training 2 (T2). T1: swimming sessions of 60 min/5 days/wk/10 wk. T2: similar to T1 until 8th wk. On the 9th wk rats swam 2ϫ/day, and on the 10th wk 3ϫ/day. MiRNAs analysis was performed by miRNA microarray and confirmed by real-time PCR. We assessed: markers of training, CH by ratio of left ventricle (LV) weight/body wt and cardiomyocytes diameter, pathological markers of CH (ANF, skeletal ␣-actin, ␣/␤-MHC), collagen I and III (COLIAI and COLIIIAI) by real-time PCR, protein collagen by hydroxyproline (OH-proline) concentration, CF and CH by echocardiography. Training improved aerobic capacity and induced CH. MiRNAs-1, 133a, and 133b were downregulated as observed in pathological CH, however, without pathological markers. MiRNA-29c expression increased in T1 (52%) and T2 (123%), correlated with a decrease in COLIAI and COLIIIAI expression in T1 (27%, 38%) and T2 (33%, 48%), respectively. MiRNA-29c was inversely correlated to OH-proline concentration (r ϭ 0.61, P Ͻ 0.05). The E/A ratio increased in T2, indicating improved LV compliance. Thus, these results show that aerobic training increase miR-29 expression and decreased collagen gene expression and concentration in the heart, which is relevant to the improved LV compliance and beneficial cardiac effects, associated with aerobic high performance training. cardiac hypertrophy; collagen; molecular markers; swimming training; physiological cardiac hypertrophy; diastolic function microRNAs (miRNAs) are recognized as a new class of gene expression regulators, consisting of short RNAs, singlestranded, that do not synthesize proteins.MiRNAs are currently potential therapeutic targets and biomarkers in cardiovascular research of various physiological and pathological processes (2,3,(33)(34)(35)(36)(37)40). The action of miRNAs occurs at the posttranscriptional level. MiRNAs negatively regulate the expression of their target genes by coupling to the 3=-untranslated regions (3=-UTR) of mRNA expressed by the target gene (direct modulation) or in the 3=-UTR of mRNA related with the expression of target gene (indirect modulation), which represses its translation into protein (18,19).There are several studies involving miRNAs in pathological cardiac hypertrophy (CH) (2, 3, 29, 35, 36). MiRNAs-1, 133a, and 133b are the best known and highly expressed in heart (36) and already have several targets genes validated, as transcription factors, proteins involved in cellular growth and division, rearrangement of myofibrils and cardiac contractility (34). Carè et al. (2) reported that the decreased expression of miRNA-1 and 133 in vivo and in vitro has a critical role in hypertro...

show abstract

“…Collagen content of the liver was determined by measurement of liver hydroxyproline as previously described (3,6), and results were expressed as g/g of wet liver tissue. In brief, liver samples were hydrolyzed in HCL at 110°C overnight.…”

Section: Methodsmentioning

confidence: 99%

Urotensin II modulates hepatic fibrosis and portal hemodynamic alterations in rats

Kemp

Kompa

Phrommintikul

et al. 2009

American Journal of Physiology-Gastrointestinal and Liver Physi

View full text Add to dashboard Cite

The influence of circulating urotensin II (UII) on liver disease and portal hypertension is unknown. We aimed to evaluate whether UII executes a pathogenetic role in the development of hepatic fibrosis and portal hypertension. UII was administered by continuous infusion over 4 wk in 20 healthy rats divided into three treatment groups, controls (saline, n = 7), low dose (UII, 1 nmol·kg−1·h−1, n = 8), and high dose (UII, 3 nmol·kg−1·h−1, n = 5). Hemodynamic parameters and morphometric quantification of fibrosis were assessed, and profibrotic cytokines and fibrosis markers were assayed in hepatic tissue. UII induced a significant dose-dependent increase in portal venous pressure (5.8 ± 0.4, 6.4 ± 0.3, and 7.6 ± 0.7, respectively, P = 0.03). High-dose UII infusion was associated with an increase in hepatic transcript for transforming growth factor-β ( P < 0.05) and platelet-derived growth factor-β ( P = 0.06). Liver tissue hydroxyproline was elevated in the high-dose group ( P < 0.05). No systemic hemodynamic alterations were noted. We concluded that UII infusion elevates portal pressure and induces hepatic fibrosis in normal rats. This response may be mediated via induction of fibrogenic cytokines. These findings have pathophysiological implications in human liver disease where increased plasma UII levels have been observed.

show abstract

New spectrophotometric method for the determination of proline in tissue hydrolyzates

Cited by 95 publications

References 3 publications

Regulation of cytoplasmic proline levels in Salmonella typhimurium: effect of osmotic stress on synthesis, degradation, and cellular retention of proline

Regulation of cytoplasmic proline levels in Salmonella typhimurium: effect of osmotic stress on synthesis, degradation, and cellular retention of proline

MicroRNAs 29 are involved in the improvement of ventricular compliance promoted by aerobic exercise training in rats

Urotensin II modulates hepatic fibrosis and portal hemodynamic alterations in rats

Contact Info

Product

Resources

About