[Advances in molecular mechanism and treatment of chronic mucus hypersecretion].

Chronic obstructive pulmonary disease (COPD) is one of the chronic diseases with high morbidity and mortality in China, which imposes heavy economic burden on society. Research has shown that chronic mucus hypersecretion (CMH) is an independent risk factor for persistent clinical symptoms, poor quality of life, rapid decline in lung function, acute exacerbation and increased hospitalization rate in COPD patients. CMH is a clinical phenotype of COPD with specific pathological and physiological changes. At present, the formation mechanism of CMH is not clear. There is a lack of specific and effective targeted treatments. This article aimed to review the latest research findings on CMH at home and abroad from the overview, impact on COPD patients, molecular mechanisms of formation, current treatment status and progress, and discuss potential targets for CMH treatment, to provide new ideas and directions for improving CMH and treating COPD.

[Advances in oncolytic virotherapy for glioma].

In recent years, there has been significant progress in the research of oncolytic viruses for the therapy of gliomas. The latest clinical trial results related to the modification, effectiveness, and safety of oncolytic viruses have brought hope for the development of glioblastoma treatments. Modified oncolytic viruses, particularly those based on the herpes simplex virus, have gained approval in Japan. Clinical trials involving recombinant poliovirus have shown better-than-expected survival outcomes with a strong safety profile. Notably, the first-time report of adenovirus in combination with immune checkpoint inhibitors for glioblastoma has demonstrated promising survival benefits and safety. However, challenges remain, including the selection of administration routes and the sustainability of treatment effects during oncolytic virus therapy. Therefore, further preclinical and clinical studies are required to improve the effectiveness and optimize treatment strategy for glioblastoma using oncolytic viruses.

Tirofiban in the treatment of cancer-associated ischemic stroke.

OBJECTIVE: It is still unknown whether early tirofiban treatment improves prognosis in patients with cancer-related ischemic stroke without intravenous thrombolytic therapy. The purpose of this study was to assess the safety and efficacy of tirofiban in patients with cancer-associated ischemic stroke. PATIENTS AND METHODS: A retrospective analysis was performed on 75 patients with cancer and mild to moderate ischemic stroke, 34 of whom received tirofiban treatment and 41 aspirin treatment. The aspirin group received aspirin 100 mg QD, while the tirofiban group received continuous intravenous administration of tirofiban at a dosage of 0.1 µg/kg/min for 48 hours before switching to oral aspirin. RESULTS: The 24-hour and 7-day National Institute of Health Stroke Scale (NIHSS) scores for the tirofiban group were lower than those for the aspirin group (p=0.017 and p=0.035, respectively). The proportion of intracerebral hemorrhage occurring within 7 days did not differ significantly between the two groups (p>0.05), and neither did the 90-day Modified Rankin Scale (mRS) scores nor the incidence of ischemic stroke. CONCLUSIONS: Early administration of tirofiban in the treatment of mild to moderate ischemic stroke is safe, which can reduce 24-hour and 7-day NIHSS scores and has potential value.

[A prospective cohort study on BMI levels and risk of acute pancreatitis].

Objective: To investigate the effects of body mass index (BMI) levels at different baseline on the risk of new-onset acute pancreatitis (AP). Methods: The subjects were from the Kailuan Study Cohort and divided into 3 groups according to baseline BMI levels: BMI<24 kg/m2, normal weight; BMI 24-28 kg/m2, overweight; BMI≥28 kg/m2, obesity. The incidence of new-onset AP in these three groups was analyzed. The survival curve was plotted by Kaplan-Meier method, the cumulative incidence was calculated and tested by log-rank method. Multivariate Cox proportional hazards regression model was used to calculate HR of baseline BMI levels for AP. Results: A total of 123 841 subjects were included and followed up for (11.94±2.13) years, during which, 395 cases were found with AP. The incidence of AP was 2.67 per 10 000 person years in total population, and the incidences of AP were 2.20, 2.72 and 3.58 per 10 000 person-years in the normal, overweight and obesity groups, respectively. The cumulative incidences of AP was 0.32%, 0.40% and 0.49% in normal, overweight and obesity groups, respectively, which showed a significant inter-group difference by log-rank test (χ 2=13.17,P<0.01). The results of multivariable adjusted Cox proportional hazards regression model analysis indicated that obesity group (HR=1.45, 95%CI: 1.10-1.92) had a higher risk for AP compared with the normal BMI group. The subgroup analyses by age and sex showed that compared with the normal weight group,the HRs for AP in the obesity group was 1.58(95%CI:1.14-2.19) and 1.40(95%CI:1.03-1.90) among subjects younger than 60 years old and male subjects, respectively. After excluded onset AP within two years from baseline,with a control group from normal weight,the results of multivariate Cox proportional hazards regression model analysis indicated that the AP in the obesity group was 1.60 (95%CI: 1.18-2.15). Conclusion: Obesity may increase the risk of developing AP, particularly among young and middle-aged men.

Actin filaments altered distribution in wheat (Triticum aestivum) "Bending Root" to respond to enhanced Ultraviolet-B radiation / Distribuição alterada dos filamentos de actina no trigo (Triticum aestivum) "Raiz dobrada" para responder à radiação ultravioleta B aprimorada

Abstract Plants adjust their shoot growth to acclimate to changing environmental factors, such as to enhanced Ultraviolet-B (UV-B) radiation. However, people have ignored that plant roots can also respond to UV-B light. Here, we find the morphology curled wheat roots under UV-B radiation, that we call, "bending roots." The curly region is the transition zone of the root after observed at the cellular level. After exposed to enhanced UV-B radiation for 2 d (10.08 KJ/m2/d), cell size decreased and actin filaments gathered in wheat roots. We also find that H2O2 production increased and that content of the indole-3-acetic acid (IAA) increased remarkably. The pharmacological experiment revealed that actin filaments gathered and polymerized into bundles in the wheat root cells after irrigated H2O2 and IAA. These results indicated that actin filaments changed their distribution and formed the "bending root," which was related to H2O2 production and increase in IAA. Overall, actin filaments in wheat root cells could be a subcellular target of UV-B radiation, and its disruption determines root morphology.

Resumo As plantas ajustam o crescimento da parte aérea para se adaptarem a fatores ambientais variáveis, como o aumento da radiação ultravioleta B (UVB). No entanto, as pessoas ignoram que as raízes das plantas também podem responder à luz UVB. Neste estudo, verificamos a morfologia das raízes enroladas de trigo sob radiação UVB, o que chamamos de "raízes dobradas". A região encaracolada é a zona de transição da raiz no nível celular. Depois de exposição à radiação UVB aprimorada por 2 dias (10,08 KJ/m2/d), o tamanho das células diminuiu, e os filamentos de actina se reuniram. Também constatamos que a produção de H2O2 aumentou e que o conteúdo do ácido indol-3-acético (IAA) aumentou notavelmente. O experimento farmacológico revelou que os filamentos de actina se reuniram e polimerizaram em feixes nas células da raiz de trigo após irrigação com H2O2 e IAA. Esses resultados indicam que os filamentos de actina alteraram sua distribuição e formaram a "raiz dobrada", relacionada à produção de H2O2 e ao aumento do IAA. No geral, os filamentos de actina nas células da raiz de trigo podem ser um alvo subcelular da radiação UVB, e sua interrupção determina a morfologia da raiz.

Actin filaments altered distribution in wheat (Triticum aestivum) "Bending Root" to respond to enhanced Ultraviolet-B radiation.

Plants adjust their shoot growth to acclimate to changing environmental factors, such as to enhanced Ultraviolet-B (UV-B) radiation. However, people have ignored that plant roots can also respond to UV-B light. Here, we find the morphology curled wheat roots under UV-B radiation, that we call, "bending roots." The curly region is the transition zone of the root after observed at the cellular level. After exposed to enhanced UV-B radiation for 2 d (10.08 KJ/m2/d), cell size decreased and actin filaments gathered in wheat roots. We also find that H2O2 production increased and that content of the indole-3-acetic acid (IAA) increased remarkably. The pharmacological experiment revealed that actin filaments gathered and polymerized into bundles in the wheat root cells after irrigated H2O2 and IAA. These results indicated that actin filaments changed their distribution and formed the "bending root," which was related to H2O2 production and increase in IAA. Overall, actin filaments in wheat root cells could be a subcellular target of UV-B radiation, and its disruption determines root morphology.

[A cohort study on the correlation between body mass index trajectories and new-onset non-alcoholic fatty liver disease].

Objective: To explore the correlation between the body mass index (BMI) trajectories and new-onset non-alcoholic fatty liver disease (NAFLD) so as to provide a scientific basis for the prevention and treatment of NAFLD. Methods: A total of 16388 observation subjects that met the inclusion criteria in the Kailuan study were used to form a cohort study. According to the BMI values of the observed subjects during annual physical examinations from 2006 to 2007, 2008 to 2009 and 2010 to 2011, SAS Proc Traj was used to determine four different BMI trajectories groups, namely, the low-stable medium-stable, medium-high and high-stable group. NAFLD incidence in each group was followed up during annual physical examinations from 2012 to 2013, 2014-2015 and 2016-2017. A total of 14998 observation subjects were finally included in the statistical analysis. The cumulative incidences of NAFLD differences in the four groups were compared. The Cox's proportional hazards regression model was used to analyze the correlation between different BMI trajectories and new-onset NAFLD. One-way analysis of variance was used to compare the intergroup difference of measurement data, and pairwise comparisons were conducted. LSD test was used for the homogeneity of variance. Dunnett's T3 test was used for heterogeneity of variances. χ (2) test was used to compare the count data, and the difference of NAFLD cumulative incidence rate between the different BMI trajectories groups was compared by log-rank test. Results: (1) the cumulative incidence of NAFLD was increased with the increase of BMI trajectories, which were 31%, 47%, 63%, 77%, respectively, and the difference was statistically significant (P < 0.01). (2) after adjusting for multiple confounding factors such as age and gender with the Cox's proportional hazards regression model, the risk of NAFLD in the BMI medium stable, medium-high, and high stable group was still 1.757 times [95% confidence interval (CI): 1.589 ~ 1.942], 2.612 (95%CI: 2.353 ~ 2.900), 3.566 (95%CI: 3.129 ~ 4.064) of the low-stable group (P < 0.01). Conclusion: The risk of NAFLD increases with increase of BMI trajectories, and long-term high levels of BMI are independent risk factors for the onset of NAFLD.

[Effect of high glucose-based peritoneal dialysis fluids on NLRP3-IL-1ß in human peritoneal mesothelial cells].

OBJECTIVE: To explore the effect of high glucose-based peritoneal dialysis fluids on NLRP3-IL-1ß in human peritoneal mesothelial cells. METHODS: HMrSV5 cells (SV40 immortalized human peritoneal mesothelial cell line) were grown in type I collagen-coated dishes in DMEM/F12 containing 10% fetal calf serum (FCS). All experiments on HMrSV5 cells were performed between passages 5 and 10. The cells were divided into 7 groups: control, 1.5% dextrose, 2.5% dextrose, 4.25% dextrose, rotenone, thenoyltrifluoroacetone (TTFA), and antimycin A. Immunoblotting was used to evaluate the expression of IL-1ß. Small interfering RNA (siRNA) targeting NLRP3 was used to downregulate the expression of NLRP3 and Western blot was used to evaluate the expression of IL-1ß in human peritoneal mesothelial cells exposed to 4.25% dextrose. In the meanwhile, resveratrol (RSV) was used to induce autophagy, 3-methyladenine (3-MA) and siRNA against Beclin 1 or ATG5 were used to block auto-phagy, flow cytometric was used to analyze the respiring (mitotracker deep red), total (mitotracker green) and reactive oxygen species (ROS)-generating mitochondria (mitoSOX); Western blot was used to evaluate the expression of IL-1ß. RESULTS: The IL-1ß relative expressions were 0, 0.175±0.082, 0.418±0.163, 2.357±0.288, 2.642±0.358, 3.271±0.462, and 0.123±0.091, indicating that the cells exposed to high glucose-based peritoneal dialysis fluids and cells treated with mitochondria respiratory chain key enzyme complex I, and complex III inhibitors increased the IL-1ß expression. And we found that NLRP3 knock-down significantly blocked the upregulation of IL-1ß. In addition, the fluorescence intensity of total mitochondria and ROS-generating mitochondria in the following groups: control, negative control, RSV, 3-MA, ATG5 siRNA, Beclin1 siRNA were 1.76±0.42, 1.83±0.55, 1.85±0.62, 7.36±0.92, 5.35±0.77, 5.06±0.62 and 821.68±95.12, 868.15±102.82, 723.39±92.56, 1 660.08±113.65, 1 433.01±107.24, 1 562.36±112.88 respectively. The increased concentrations of mitochondrial ROS and IL-1ß upregulation were confirmed in the inhibition but not the induction of auto-phagy. We also found that downregulation of ATG5 and Beclin1 sensitized cells for the release of IL-1ß induced by MSU (monosodium urate) or nigericin which was the NLRP3 inflammasome activator. RSV treatment attentuated this effect. CONCLUSION: Long-term application of high glucose-based peritoneal dialysis fluids can trigger the consistent activation of NLRP3-IL-1ß in peritoneal mesothelial cells. Timely initiation of autophagy may block the NLRP3-IL-1ß activation and provide a basis for the further development of a potential therapeutic strategy for delay of chronic inflammation and peritoneal fibrosis associated with peritoneal dialysis.

[Sivelestat alleviates nonalcoholic steatohepatitis in mice through inhibiting activation of Kupffer cells].

Objective: To investigate the role of neutrophil elastase inhibitor, sivelestat, in preventing and treating nonalcoholic steatohepatitis (NASH) and its underling mechanisms. Methods: A total of forty 4-week-old male C57BL/6J ApoE-/-mice were equally divided into the following four groups: standard chow (SC)+isotonic saline; SC+sivelestat; high-fat, high-cholesterol (HFHC) diet+isotonic saline; and HFHC+sivelestat. These mice were treated with above methods for 12 weeks. Blood and liver tissue samples were collected to measure biochemical parameters, hepatic steatosis and non-alcoholic fatty liver disease (NAFLD) activity score (inflammation) were evaluated by oil red O staining and HE staining, respectively. The mRNA and protein expression levels of hepatic inflammatory cytokines, CD68, and F4/80 were determined by quantitative RT-PCR and immunohistochemistry, respectively. Comparison of means between the four groups was made by one-way analysis of variance, and comparison between any two groups was made by the LSD or SNK method (for data with homogeneity of variance) or the Tamhane or Dunnett method (for data with heterogeneity of variance). Results: Mice fed with an HFHC diet for 12 weeks developed typical pathological features of NASH compared with those fed with SC. Compared with mice fed with HFHC diet without sivelestat, those treated with HFHC and sivelestat exhibited the following features: (1) significantly reduced fast blood glucose, blood cholesterol, and hepatic biochemical parameters, as well as increased insulin sensitivity; (2) significantly reduced NAFLD activity score (5.71±1.11 vs 3.16±1.16, P < 0.05); (3) reduced monocyte chemoattractant protein-1 and tumor necrosis factor -α; (4) significantly reduced mRNA levels of CD68 and F4/80; and (5) reduced expression of CD68 in the liver. Conclusion: Sivelestat alleviates the hepatic steatosis and inflammation of NASH in mice by inhibiting the activation of Kupffer cells.

Actin filaments altered distribution in wheat (Triticum aestivum) Bending Root to respond to enhanced Ultraviolet-B radiation

Abstract Plants adjust their shoot growth to acclimate to changing environmental factors, such as to enhanced Ultraviolet-B (UV-B) radiation. However, people have ignored that plant roots can also respond to UV-B light. Here, we find the morphology curled wheat roots under UV-B radiation, that we call, bending roots. The curly region is the transition zone of the root after observed at the cellular level. After exposed to enhanced UV-B radiation for 2 d (10.08 KJ/m2/d), cell size decreased and actin filaments gathered in wheat roots. We also find that H2O2 production increased and that content of the indole-3-acetic acid (IAA) increased remarkably. The pharmacological experiment revealed that actin filaments gathered and polymerized into bundles in the wheat root cells after irrigated H2O2 and IAA. These results indicated that actin filaments changed their distribution and formed the bending root, which was related to H2O2 production and increase in IAA. Overall, actin filaments in wheat root cells could be a subcellular target of UV-B radiation, and its disruption determines root morphology.

Resumo As plantas ajustam o crescimento da parte aérea para se adaptarem a fatores ambientais variáveis, como o aumento da radiação ultravioleta B (UVB). No entanto, as pessoas ignoram que as raízes das plantas também podem responder à luz UVB. Neste estudo, verificamos a morfologia das raízes enroladas de trigo sob radiação UVB, o que chamamos de raízes dobradas. A região encaracolada é a zona de transição da raiz no nível celular. Depois de exposição à radiação UVB aprimorada por 2 dias (10,08 KJ/m2/d), o tamanho das células diminuiu, e os filamentos de actina se reuniram. Também constatamos que a produção de H2O2 aumentou e que o conteúdo do ácido indol-3-acético (IAA) aumentou notavelmente. O experimento farmacológico revelou que os filamentos de actina se reuniram e polimerizaram em feixes nas células da raiz de trigo após irrigação com H2O2 e IAA. Esses resultados indicam que os filamentos de actina alteraram sua distribuição e formaram a raiz dobrada, relacionada à produção de H2O2 e ao aumento do IAA. No geral, os filamentos de actina nas células da raiz de trigo podem ser um alvo subcelular da radiação UVB, e sua interrupção determina a morfologia da raiz.

[Analysis of the Injury-disease Relationship between Spondylolysis and Trauma in 26 Forensic Identifications].

OBJECTIVES: To expound the injury-disease relationship between spondylolysis and trauma for the points of forensic identification. METHODS: Total 26 cases of spondylolysis were collected and the characteristics of this disease such as age, accompanied symptoms, treatment and injury manner were discussed. RESULTS: The causal relationship existed between trauma and injury consequence in 2 appraised individuals and both of them aged less than 50 years old. The injury manners of both were high-energy injury with combined injury and these 2 patients were treated by operation. CONCLUSIONS: The analysis of injury-disease relationship between spondylolysis and trauma should be paid attention in the middle-young age under 50 years old. More importantly, the injury-disease relationship should be analyzed in the patients who chose operative treatment.

Chemical composition and antioxidant, antimicrobial activities of the essential oils of Thymus marschallianus Will. and Thymus proximus Serg.

UNLABELLED: Chemical composition and antioxidant, antimicrobial activities of the essential oils from Thymus marschallianus Will. and Thymus proximus Serg. growing in the wild in Xinjiang were studied. Samples were collected from the aerial parts of the plants with simultaneous distillation-extraction apparatus. The yields ranged between 1.22%+/- 0.01 and 0.16%+/- 0.01 (weight/dry weight), respectively, 53 and 60 kinds of volatiles, representing 99.6% and 99.7% of the essential oils, respectively, were identified in extracts from T. marschallianus and T. proximus by GC/MS analysis. The main components were Thymol (28.0% to 32.9%), p-Cymene (7.7% to 25.4%), and gamma-Terpinene (18.0% to 22.4%). Antioxidant activities of the oils were evaluated using metal chelating, reductive potential, 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, and modified thiobarbituric acid reactive substances assay. Antimicrobial activities of the oils were investigated on Escherichia coli, Staphylococcus aureus, Bacillus subtilis, yeast, Rhizopus, and Penicillium. The inhibition zones (IZ) and minimum inhibitory concentration (MIC) values were 5.0 to 35.7 mm in diameter and 1.81 to 4.52 microL/mL, respectively. PRACTICAL APPLICATION: Due to the economical impacts of spoiled foods and the consumer's concerns over the safety of foods, a lot of attention has been paid to naturally derived compounds. Fresh and dried Thymus species as well as their processed products have been widely used as flavorings since ancient times; however, during the last few decades, they also have become a subject for a search of natural antioxidants and antimicrobial agents. Biological activities of Thymus essential oils depend on their chemical composition, which is determined by the genotype and influenced by environmental conditions. Recent studies have showed that Thymus species have strong antimicrobial and antioxidant activities. To the best of our knowledge, the properties of Thymus species growing wild in the Xinjiang have not been reported before.

The impact of N-ratio in minimizing stage migration phenomenon in gastric cancer patients with insufficient number or level of lymph node retrieved: results from a Chinese mono-institutional study in 2159 patients.

BACKGROUND: Previous studies indicate that N-ratio has significant superiority in minimizing 'stage migration' for patients with >15 lymph nodes retrieved. Whether the result is applicable to patients with < or =15 lymph nodes retrieved is still in question. PATIENTS AND METHODS: Overall survival rates of 2159 gastric cancer patients who underwent radical resection were compared between patients with different number and level of lymph nodes retrieved according to pN [International Union Against Cancer (Union Internationale Contre le Cancer)/AJCC N stage], n (JGCA N stage) and rN (N-ratio) staging system. RESULTS: Patient number was significantly different between insufficient and sufficient number or level retrieved group in pN and n system, respectively, but not in rN system, while overall survival rates were not significantly different between those groups. The 5-year survival rates of patients with insufficient nodes retrieved were significantly lower than those with sufficient nodes retrieved in pN and n system, but not in rN system. The hazard risk for patients with insufficient nodes retrieved was significantly higher than that for patients with sufficient nodes retrieved in pN and n system, but not in rN system. CONCLUSION: The rN stage has more potential advantages in minimizing stage migration phenomenon for patients with insufficient number or level of lymph nodes retrieved.

[Control system for rotational gamma knife].

The features and composition of Rotational Gamma Knife are mainly introduced in this paper. The open architecture double PLCs and motion controller are used to fit special requirements of the Rotational Gamma Knife and thus to ensure its high reliability. In the end, safety measures which should be taken for patients, doctors and equipments are discussed.

Turgor, temperature and the growth of plant cells: using Chara corallina as a model system.

Rapid changes in turgor pressure (P:) and temperature (T:) are giving new information about the mechanisms of plant growth. In the present work, single internode cells of the large-celled alga Chara corallina were used as a model for plant growth. P was changed without altering the chemical environment of the wall while observing growth without elastic changes. When P: was measured before any changes, the original growth rate bore no relationship to the original P. However, if P of growing cells was decreased, growth responded immediately without evidence for rapid changes in wall physical properties. Growth occurred only above a 0.3 MPa threshold, and increasing P caused small increases in growth that became progressively larger as P rose, resulting in a curvilinear response overall. The small changes in growth close to the threshold may explain early failures to detect these responses. When T was lowered, the elastic properties of the cell were unaffected, but growth was immediately inhibited. The lower T caused P to decrease, but returning P to its original value did not return growth to its original rate. The decreased P at low T occurred because of T effects on the osmotic potential of the cell. At above-normal P, growth partially resumed at low T Therefore, growth required a P-sensitive process that was also T-sensitive. Because elastic properties were little affected by T, but growth was markedly affected, the process is likely to involve metabolism. The rapidity of its response to P and T probably excludes the participation of changes in gene expression.

[Comparative analysis of several treatment methods for severe congestive heart failure].

UNLABELLED: Western medicines (WM) and the combining WM-TCM were used to treat congestive heart failure (CHF). The three groups of WM were: Digoxin with dihydro-chlorothiazide, captopril with nifedipium, and dobutamine. The three groups of combining WM-TCM were: the above-mentioned three groups of WM with Jisen Shenqi Pill (JSSQ) respectively. The result observed: Total effective rate was 82%, marked effective rate was 43%, the rates of the WM groups were 77% and 36% respectively, and the groups of combining WM-TCM were 88% and 53%. Total mortality was 8.66% (the WM groups was 11.76%, the groups of combining WM-TCM 5%). Cardio-function indexes observed in the groups of combining WM-TCM were obviously improved, including HR, SV, CI, EF, FS and A/E (P < 0.01). HR, CI and SV in the groups of WM were also significantly improved (P < 0.05) except for EF, FS and A/E (P > 0.05). CONCLUSIONS: (1) The treatment of CHF should depend on various conditions and different symptoms in selecting medicines, so that individual treatment could reach the optimal effects. (2) The treatment method of combining WM-TCM could significantly promote effective rate, reduce toxic and side-effects and lower the rate of mortality. (3) JSSQ could obviously improve the function of ventricular diastole and its mechanism might be that the reduced density of beta-receptor was increased.

Enlargement in chara studied with a turgor clamp : growth rate is not determined by turgor.

A new method, the turgor clamp, was developed to test the effects of turgor on cell enlargement. The method used a pressure probe to remove or inject cell solution and change the turgor without altering the external environment of the cell walls. After the injections, the cells were permanently at the new turgor and required no further manipulation. Internode cells of Chara corallina grew rapidly with the pressure probe in place when growth was monitored with a position transducer. Growth-induced water potentials were negligible and turgor effects could be studied simply. As turgor was decreased, there was a threshold below which no growth occurred, and only reversible elastic/viscoelastic changes could be seen. Above the threshold, growth was superimposed on the elastic/viscoelastic effects. The rate of growth did not depend on turgor. Instead, the rate was highly dependent on energy metabolism as shown by inhibitors that rapidly abolished growth without changing the turgor. However, turgors could be driven above the maximum normally attainable by the cell, and these caused growth to respond as though plastic deformation of the walls was beginning, but the deformation caused wounding. Growth was inhibited when turgor was changed with osmotica but not inhibited when similar changes were made with the turgor clamp. It was concluded that osmotica caused side effects that could be mistaken for turgor effects. The presence of a turgor threshold indicates that turgor was required for growth. However, because turgor did not control the rate, it appears incorrect to consider the rate to be determined by a turgor-dependent plastic deformation of wall polymers. Instead, above the turgor threshold, the rapid response to energy inhibitors suggests a control by metabolic reactions causing synthesis and/or extension of wall polymers.

Water Transport across Maize Roots : Simultaneous Measurement of Flows at the Cell and Root Level by Double Pressure Probe Technique.

A double pressure probe technique was used to measure simultaneously water flows and hydraulic parameters of individual cells and of excised roots of young seedlings of maize (Zea mays L.) in osmotic experiments. By following initial flows of water at the cell and root level and by estimating the profiles of driving forces (water potentials) across the root, the hydraulic conductivity of individual cell layers was evaluated. Since the hydraulic conductivity of the cell-to-cell path was determined separately, the hydraulic conductivity of the cell wall material could be evaluated as well (Lp(cw) = 0.3 to 6.10(-9) per meter per second per megapascal). Although, for radial water flow across the cortex and rhizodermis, the apoplasmic path was predominant, the contribution of the hydraulic conductance of the cell-to-cell path to the overall conductance increased significantly from the first layer of the cortex toward the inner layers from 2% to 23%. This change was mainly due to an increase of the hydraulic conductivity of the cell membranes which was Lp = 1.9.10(-7) per meter per second per megapascal in the first layer and Lp = 14 to 9.10(-7) per meter per second per megapascal in the inner layers of the cortex. The hydraulic conductivity of entire roots depended on whether hydrostatic or osmotic forces were used to induce water flows. Hydrostatic Lp(r) was 1.2 to 2.3.10(-7) per meter per second per megapascal and osmotic Lp(r) = 1.6 to 2.8.10(-8) per meter per second per megapascal. The apparent reflection coefficients of root cells (sigma(s)) of nonpermeating solutes (KCI, PEG 6000) decreased from values close to unity in the rhizodermis to about 0.7 to 0.8 in the cortex. In all cases, however, sigma(s) was significantly larger than the reflection coefficient of entire roots (sigma(sr)). For KCI and PEG 6000, sigma(sr) was 0.53 and 0.64, respectively. The results are discussed in terms of a composite membrane model of the root.