Inflammatory cardiac fibroblast phenotype underlies chronic alcohol-induced cardiac atrophy and dysfunction.

AIMS: The purpose of this study was to investigate mechanisms of chronic alcohol-induced cardiac remodeling and dysfunction. We also sought to determine the role of cardiac fibroblasts, which play a dynamic role in cardiac remodeling, in mediating these effects. MAIN METHODS: Adult male Wistar rats were exposed to ethanol (EtOH) vapor inhalation for 16 weeks. Echocardiography was performed to assess terminal cardiac structure and function. Cardiac fibroblasts were isolated from the left ventricle (LV) for both ex vivo and in vitro analysis. Cultured H9C2 cells were also exposed to conditioned media from alcohol-exposed cardiac fibroblasts. Gene expression in whole LV tissue, isolated cardiac fibroblasts, or cultured H9C2 cells was determined by real-time PCR, and protein expression was determined by Western blot. KEY FINDINGS: EtOH led to LV wall thinning and impaired systolic function, and decreased contractile protein mRNA levels. EtOH increased LV inflammatory markers, JNK and Akt activation, and decreased mTOR expression. EtOH induced myofibroblast activation as assessed by flow cytometry, and increased LV collagen III expression. EtOH increased expression of several inflammatory mediators in cardiac fibroblasts both ex vivo and in vitro. Administration of conditioned media from EtOH-treated fibroblasts decreased contractile protein mRNA levels and impaired Akt and mTOR signaling in differentiated H9C2 cardiomyocytes. SIGNIFICANCE: Our results indicate that EtOH-induced cardiac atrophy and dysfunction is associated with activation of inflammatory pathways. Furthermore, EtOH may induce a pro-inflammatory cardiac fibroblast phenotype, leading to aberrant fibroblast-myocyte cross-talk. Thus, EtOH may promote cardiac muscle wasting in part by activation of pro-inflammatory fibroblasts.

Estrogen receptor antagonism exacerbates cardiac structural and functional remodeling in female rats.

We have previously demonstrated the cardioprotective effects of ovarian hormones against adverse ventricular remodeling imposed by chronic volume overload. Here, we assess the estrogen receptor dependence of this cardioprotection. Four groups of female rats were studied: sham-operated (Sham), volume overloaded [aortocaval fistula (ACF)], Sham treated with estrogen receptor antagonist ICI 182,780 (Sham + ICI), and ACF treated with ICI. Cardiac function was assessed temporally using echocardiogram, and tissue samples were collected at 5 days and 6 wk postsurgery. All rats with volume overload had significantly increased cardiac output (96 ± 32 ml/min for ACF and 108 ± 11 ml/min for ACF + ICI vs. 31 ± 2 for Sham, P < 0.05). At 6 wk, volume overload induced significant left ventricular (LV) hypertrophy in both untreated and treated ACF groups. Both ACF groups developed significantly increased LV end-diastolic diameter (LVEDD), indicating LV dilatation, with the ACF + ICI group having the greatest increase (340%, relative to Sham). Ejection fraction was significantly reduced in the ACF + ICI group (23% reduction) at 6 wk postsurgery compared with untreated ACF (P < 0.05). Interstitial collagen staining was significantly reduced by volume overload, with estrogen receptor antagonism causing greater collagen loss at both 5 days and 6 wk postsurgery. Furthermore, volume overload induced a significant increase in LV wall stress only in rats treated with estrogen antagonist. These data indicate that estrogen receptor signaling is essential for sex hormone-dependent cardioprotection against adverse remodeling. The maintenance of myocardial extracellular matrix collagen appears to play a key role in this cardioprotection. NEW & NOTEWORTHY: We assessed the estrogen receptor (ER) dependence of female-specific cardioprotection using a rat model of chronic volume-overload stress. ER antagonism worsened ventricular wall stress, ventricular dilation, and cardiac dysfunction induced by volume overload. Further, blocking ERs resulted in cardiac remodeling and functional changes similar to that previously found in ovariectomized rats.

Continuous distal oesophageal acidification decreases postprandial gastric acidity in healthy human subjects.

BACKGROUND: Previously, we hypothesized that exposing the distal oesophagus to acid signals the stomach to decrease gastric acidity. AIM: To test the hypothesis that exposing the distal oesophagus to acid signals the stomach to decrease gastric acidity. METHODS: Twenty-two healthy humans ingested a standard meal containing [(14)C]octanoic acid and [(13)C]glycine over 30 min on 2 separate occasions. Gastric pH was measured for 90 min before and 240 min after the meal. 10 mm HCl was infused continuously at 1 mL/min into either the distal oesophagus or stomach in a 2-way crossover fashion for 60 min before and 240 min after the meal. Gastric emptying of solid and liquid were determined with breath tests. RESULTS: Compared to gastric infusion, oesophageal infusion significantly decreased gastric acidity after the meal, but not before the meal and the magnitude of the decrease varied directly with gastric acidity. Gastric emptying of solid or liquid with oesophageal infusion was not significantly different from that with gastric infusion. CONCLUSIONS: These findings support the hypothesis of the existence of a physiological oesophago-gastric feedback mechanism that might contribute to regulation of postprandial gastric acidity. Oesophageal acidification might decode gastric information and signal the stomach to decrease gastric acidity. Further studies are needed to assess the characteristics of such feedback mechanism in-patients with gastro-oesophageal reflux disease (GERD).

The effects of changing temperature correction factors on measures of acidity calculated from gastric and oesophageal pH recordings.

BACKGROUND: Recently, Medtronic notified customers that new correction factors should be used for their Slimline and Zinetics24 single-use, internal-standard pH catheters. AIM AND METHODS: We selected 24-h recordings of oesophageal and gastric pH with the Zinetics24 from our archives for five healthy subjects and for five gastro-oesophageal reflux disease subjects who were studied at baseline and again after 8 days of treatment with a proton-pump inhibitor. All pH values obtained with the old correction factors were rescaled using the new correction factors. Values for median pH, integrated acidity and time pH < or = 4 were then calculated from pH values with old and new correction factors. RESULTS: The new correction factors changed values for median pH, integrated acidity and time pH < or = 4. Values for median pH and integrated acidity changed in a predictable, proportionate way, whereas values for time pH < or = 4 did not. CONCLUSIONS: The new correction factors will not change the interpretation of previously published results with median pH or integrated acidity. In contrast, values for time < or =4 cannot be converted in an obvious way with the new correction factors. Instead, the raw pH data will need to be rescaled and values for time pH < or = 4 recalculated using the rescaled pH data.

The fractal nature of human gastro-oesophageal reflux.

BACKGROUND: We are unaware of the analyses of time series data resulting from 24 h recordings of human gastric or oesophageal pH. As a result, we have no understanding of the quantitative changes in gastric or oesophageal acidity over time, the patterns that might characterize these changes, or the physiological significance of gastro-oesophageal reflux. AIM: To examine the time series for gastric and oesophageal pH. METHODS: Detrended fluctuation analysis and lag analysis were used to analyse data from 24 h recordings of oesophageal and gastric pH in five normal subjects and five subjects with gastro-oesophageal reflux disease. RESULTS: Analyses of the patterns of gastric and oesophageal pH over time in normal subjects and subjects with gastro-oesophageal reflux disease indicate that the fluctuations in pH are self-similar across different time scales and are consistent with an underlying fractal process. Furthermore, there is a significant statistical association between sequential pH values separated by as much as 2.2 h. CONCLUSIONS: We hypothesize that the self-similar, fractal pattern encodes information about gastric acidity and that the oesophagus decodes this information and, when appropriate, may signal the stomach to reduce gastric acidity. Subjects with gastro-oesophageal reflux disease might have an impaired oesophageal-gastric feedback mechanism that results in increased gastric acid, which reflux from the stomach into the oesophagus.

Oesophageal pH has a power-law distribution in control and gastro-oesophageal reflux disease subjects.

BACKGROUND: We are unaware of any solid theoretical or pathophysiological basis for selecting pH 4 or any other pH value to assess oesophageal acid exposure or to define oesophageal reflux episodes. AIM: To examine the frequency of different oesophageal pH values in control and GERD subjects. METHODS: Oesophageal pH was measured for 24 h in 57 gastro-oesophageal reflux disease subjects and 26 control subjects. Histograms were constructed using the 21,600 values from each recording and bins of 0.25 pH units. RESULTS: Compared with controls, gastro-oesophageal reflux disease subjects had significantly more low pH values and significantly fewer high pH values. In both gastro-oesophageal reflux disease and control subjects, the frequency of oesophageal pH values was characterized by a power-law distribution indicating that the same relationship that describes low pH values also describes high pH values, as well as all values in between. CONCLUSIONS: The distribution of oesophageal pH values indicates that a variety of different pH values can be used to assess oesophageal acid exposure, but raises important questions regarding how oesophageal reflux episodes are defined.

Frequency analyses of gastric pH in control and gastro-oesophageal reflux disease subjects treated with a proton-pump inhibitor.

BACKGROUND: We are unaware of any solid theoretical or pathophysiological basis for selecting pH 4 or any other pH value to assess gastric acidity. AIM: To examine the frequency of different gastric pH values in control and GERD subjects. METHODS: Gastric pH was measured for 24 h in 26 control subjects, 26 gastro-oesophageal reflux disease subjects at baseline and the same 26 gastro-oesophageal reflux disease subjects during treatment with a proton-pump inhibitor. Histograms were constructed using the 21 600 values generated from each recording and bins of 0.25 pH units. RESULTS: The distribution of gastric pH values in gastro-oesophageal reflux disease subjects was significantly different from that in controls and in some instances the distributions detected significant differences that were not detected by integrated acidity. Proton-pump inhibitor treatment significantly altered the distribution of gastric pH values and the nature of this alteration during the postprandial period was different from that during the nocturnal period. Using time pH< or =4 can significantly underestimate the magnitude of inhibition of gastric acidity caused by a proton-pump inhibitor. CONCLUSIONS: The distribution of gastric pH values provides a rationale for selecting a particular pH value to assess gastric acidity. In some instances, the distribution of gastric pH values detects significant differences between gastro-oesophageal reflux disease and normal subjects that are not detected by integrated acidity.

The basis for the decreased response to proton pump inhibitors in gastro-oesophageal reflux disease patients without erosive oesophagitis.

BACKGROUND: The reason why heartburn in gastro-oesophageal reflux disease subjects without oesophagitis is less responsive to proton pump inhibitors than heartburn in those with erosive oesophagitis is not known. METHODS: Gastric and oesophageal pH were determined in 26 subjects with gastro-oesophageal reflux disease at baseline and on days 1, 2 and 8 of treatment with 20 mg omeprazole or 20 mg rabeprazole in a randomized, two-way cross-over fashion. The presence or absence of erosive oesophagitis at baseline was documented by upper gastrointestinal endoscopy. RESULTS: At a given value of the integrated gastric acidity during treatment with a proton pump inhibitor, the probability of pathological oesophageal reflux was significantly higher in subjects with no oesophagitis than in those with erosive oesophagitis. This occurred because the post-prandial gastric acidity in subjects with no oesophagitis showed a decreased response to the antisecretory agent. CONCLUSIONS: Compared with gastro-oesophageal reflux disease subjects with erosive oesophagitis, those with no oesophagitis are relatively refractory to the pharmacodynamic effects of proton pump inhibitors on the post-prandial integrated gastric acidity.

Heartburn severity can predict pathologic oesophageal reflux in gastro-oesophageal reflux disease patients treated with a proton-pump inhibitor.

BACKGROUND: In gastro-oesophageal reflux disease (GERD) subjects treated with a gastric anti-secretory agent, it is not known whether there is a relationship between heartburn severity and oesophageal acid exposure. METHODS: Oesophageal pH and heartburn severity were determined in 27 GERD subjects at baseline and on days 1, 2 and 8 of treatment with 20 mg omeprazole or 20 mg rabeprazole in a randomized, two-way crossover fashion. RESULTS: Receiver operating characteristic (ROC) analysis was used to determine values for heartburn severity that gave optimal cut-off points for distinguishing between normal and pathologic oesophageal reflux. Using these cut-off points, we found that the probability of no pathologic oesophageal reflux (Y) could be best fitted by an exponential equation: Y = a(e-bX) + c, where a, b and c are constants and X is the value of heartburn severity. There was close agreement between predicted and observed percentages of subjects with pathologic oesophageal reflux during different days of treatment. CONCLUSIONS: In GERD subjects treated with a proton-pump inhibitor, the value of heartburn severity following a single standard meal can predict the likelihood of pathologic oesophageal reflux over the entire 24-h period.

Meal-stimulated gastric acid secretion and integrated gastric acidity in gastro-oesophageal reflux disease.

BACKGROUND: No current methods exist to determine meal-stimulated gastric acid secretion in humans under conditions that approximate those of daily living with the ingestion of breakfast, lunch and dinner. METHODS: Gastric and oesophageal pH were measured in 26 healthy subjects and in 59 subjects with gastro-oesophageal reflux disease. Meal-stimulated gastric acid secretion was calculated from the buffer capacity of the meals determined in vitro and from the time required for the gastric pH to decrease to pH 2 in vivo following ingestion of the meal. RESULTS: There was a significant correlation between gastric secretion with each meal and the corresponding post-prandial integrated gastric acidity. There was also a significant correlation between meal-stimulated gastric secretion and integrated gastric acidity from 09.00 to 22.00 h in both subjects with gastro-oesophageal reflux disease and controls. In subjects with gastro-oesophageal reflux disease, gastric secretion and integrated gastric acidity from 09.00 to 22.00 h were significantly higher than those in controls. There was a significant correlation between oesophageal acidity and integrated gastric acidity from 09.00 to 22.00 h in subjects with gastro-oesophageal reflux disease. CONCLUSIONS: As post-prandial gastric acidity is increased in subjects with gastro-oesophageal reflux disease, it seems likely that increased gastric acidity is an important aetiological factor in this disease.

Determination of the reduction in gastric acidity necessary to prevent pathological oesophageal reflux in patients with gastro-oesophageal reflux disease treated with a proton pump inhibitor.

BACKGROUND: In subjects with gastro-oesophageal reflux disease treated with a gastric antisecretory agent, the extent to which gastric acidity needs to be reduced to prevent pathological oesophageal acid exposure is not known. METHODS: Gastric and oesophageal pH were measured in 26 healthy subjects and in 59 subjects with gastro-oesophageal reflux disease. In 27 of the subjects with gastro-oesophageal reflux disease, pH was also recorded on days 1, 2 and 8 of treatment with 20 mg omeprazole and 20 mg rabeprazole in a randomized, two-way, cross-over fashion. RESULTS: Receiver operating characteristic analysis was used to determine values for the integrated oesophageal acidity and time oesophageal pH

Cisapride inhibits meal-stimulated gastric acid secretion and post-prandial gastric acidity in subjects with gastro-oesophageal reflux disease.

BACKGROUND AND AIMS: KCNQ1 potassium channels in human gastric parietal cells are thought to be involved in gastric acid secretion. As cisapride can inhibit similar channels in other tissues and is an effective treatment for nocturnal heartburn, we examined the effects of cisapride on gastric and oesophageal acidity, gastric emptying and heartburn severity in subjects with gastro-oesophageal reflux disease. METHODS: Subjects (n = 11) had suffered from heartburn four times or more per week for at least 6 months. Gastric pH and oesophageal pH were measured before, during and after a standard meal ingested over 15 min. Each subject received placebo or 10 mg cisapride orally, 30 min before the beginning of the meal. Meal-stimulated gastric acid secretion was calculated from the amount of HCl required to titrate the homogenized standard meal to pH 2 in vitro and the time required for the pH of the ingested meal to decrease to pH 2 in vivo. Heartburn severity was assessed at 15-min intervals beginning at the end of the meal. Gastric emptying of solids was measured using a [(13)C]-octanoic acid breath test. RESULTS: Cisapride significantly decreased meal-stimulated gastric acid secretion by 20%, decreased integrated gastric and oesophageal acidity by 50-60% and transiently increased the expiration of (13)CO(2). Cisapride did not significantly alter heartburn severity. CONCLUSIONS: The cisapride-induced decreases in meal-stimulated gastric acid secretion, gastric acidity and oesophageal acidity in subjects with gastro-oesophageal reflux disease can account for its beneficial clinical effects. These results also raise the possibility that gastric KCNQ1 potassium channels are important in meal-stimulated gastric acid secretion and possibly in the pathophysiology of gastro-oesophageal reflux disease.

Determination of the time of onset of action of ranitidine and famotidine on intra-gastric acidity.

BACKGROUND: No standard methods exist for determining the onset of action of gastric antisecretory agents in human subjects. METHODS: Intragastric pH was measured when placebo, ranitidine 150 mg, ranitidine 75 mg or famotidine 10 mg were administered 30 min after the end of a meal. RESULTS: When the onset of action was defined as the earliest time that mean gastric pH with active treatment was statistically significantly higher (P < 0.05) than the corresponding placebo value, the onsets of action of ranitidine 75 mg and 150 mg were 55 min, and of famotidine 10 mg, 90 min. When onset was defined in terms of a particular decrease in gastric acid concentration for the group as a whole or for individual subjects, there was an important variation in the relative times of onset of ranitidine 75 mg and famotidine 10 mg. CONCLUSIONS: When administered after a meal, the onset of action of ranitidine and famotidine on gastric pH can be determined for individual subjects as well as for the group as a whole. When onset was determined for the group using statistical significance, which does not depend on arbitrary cut-off points, ranitidine 75 mg had an earlier onset of action than did famotidine 10 mg.

Integrated acidity and rabeprazole pharmacology.

BACKGROUND: Integrated gastric and oesophageal acidity can be calculated from measurements of gastric and oesophageal pH and used to quantify gastric and oesophageal acidity over time. Rabeprazole is a new proton pump inhibitor that is effective in treating gastro-oesophageal reflux disease (GERD). AIM: To use measurement of integrated gastric and oesophageal acidity to determine the onset, duration and overall effect of rabeprazole in subjects with GERD. METHODS: Subjects with GERD were required to have oesophageal pH less-than-or-equal 4 for at least 10% of a 24-h recording. Effects of 20 mg rabeprazole on 24-h gastric and oesophageal pH were measured on days 1 and 7 of dosing. Integrated gastric and oesophageal acidity were calculated from time-weighted average hydrogen ion concentrations at each second of the 24-h record. RESULTS: At steady-state, 20 mg rabeprazole inhibited gastric acidity by 89% and oesophageal acidity by 95%. The first dose of rabeprazole inhibited gastric and oesophageal acidity by at least 70% of the steady-state effect. Oesophageal acidity could be divided into monophasic and biphasic patterns, and rabeprazole had different effects on oesophageal and gastric acidity in these two GERD subpopulations. The onset of action of the first dose of rabeprazole on gastric acidity was 4 h and on oesophageal acidity was 4 h in monophasic subjects and 7 h in biphasic subjects. Integrated acidity was more sensitive than time pH less-than-or-equal 4 in measuring the inhibitory actions of rabeprazole. CONCLUSIONS: Integrated gastric and oesophageal acidity are quantitative measurements that provide useful and novel information regarding the pathophysiology of GERD as well as the impact of antisecretory agents such as rabeprazole.

Synergy between low-dose ranitidine and antacid in decreasing gastric and oesophageal acidity and relieving meal-induced heartburn.

BACKGROUND: The pathophysiology of recurrent postprandial heartburn and the basis for the effectiveness of antacids or low doses of histamine H2-receptor antagonists have not been well studied. METHODS: The selected subjects (n=26) had heartburn more than four times a week for at least 2 months, which was responsive to antacids. Gastric pH and oesophageal pH were measured for 1 h before, during, and 4.5 h after ingestion of a meal over 0.5 h. Heartburn severity was assessed at 15-min intervals beginning at the end of the meal. Each subject randomly received placebo, 75 mg ranitidine, 420 mg calcium carbonate, and ranitidine plus calcium carbonate. Values for pH were converted to acid concentration (mM) and integrated acidity was calculated from the cumulative, time-weighted means of the acid concentrations for every second of the postprandial recording period. RESULTS: There was a close temporal relationship between heartburn and oesophageal acidity. Most oesophageal acid exposure occurred over a 90-min period that began approximately 45 min after the end of the meal. During this period the gastric acid concentration was less than 5% of maximal. Ranitidine significantly decreased gastric but not oesophageal acidity, whilst antacid significantly decreased oesophageal but not gastric acidity. Ranitidine plus antacid significantly decreased both gastric and oesophageal acidity. Antacid alone and ranitidine plus antacid significantly decreased heartburn severity. CONCLUSIONS: Determining integrated gastric and oesophageal acidity provides novel information regarding the pathophysiology of meal-induced heartburn as well as the actions of low-dose ranitidine and antacid. For subjects with meal-induced heartburn, treatment with low-dose ranitidine plus antacid is particularly effective in decreasing gastric and oesophageal acidity as well as heartburn severity.

Integrated acidity and the pathophysiology of gastroesophageal reflux disease.

OBJECTIVES: The aim of this study was to demonstrate that integrated esophageal and gastric acidity values, calculated from 24-h pH recordings, can provide more precise quantitative temporal data than the conventional pH parameters historically associated with gastroesophageal reflux disease (GERD) investigations. METHODS: Esophagogastroduodenoscopy results and pH tracings from 20 GERD subjects with > or =10% esophageal acid contact time were studied. Integrated gastric and esophageal acidity were calculated from time-weighted average hydrogen ion concentrations at each second of the 24-h recording period. RESULTS: Integrated esophageal acidity correlated with grade of esophagitis. Two quite distinct GERD subtypes were identified, with either a monophasic or biphasic pattern of integrated esophageal acidity. "Biphasic" subjects differed from "monophasic" subjects in terms of magnitude and pattern of integrated esophageal acidity. Although both groups had significant integrated nocturnal gastric acidity, only the biphasic GERD subjects had concomitant increases in nocturnal integrated esophageal acidity. Esophagitis grade was correlated with magnitude rather than pattern of integrated esophageal acidity, and it was possible to calculate a reflux coefficient that seems to provide an estimate of the quantitative motor disturbance present in GERD. CONCLUSIONS: Integrated esophageal and gastric acidity provide quantitative measures of GERD pathophysiology and, compared to conventional pH parameters, should enhance evaluation of therapeutic interventions.

Relation of childhood diet and body size to menarche and adolescent growth in girls.

Adolescent growth and development may be affected by factors such as dietary intake and body size from much earlier in childhood. In a longitudinal study of 67 Caucasian girls in Boston, Massachusetts, data were collected prospectively from birth during the 1930s and 1940s. Heights and weights were measured semiannually, and dietary history interviews were conducted with mothers. Stepwise linear regression methods were used to seek factors which best predicted age at menarche, adolescent peak height growth velocity, and the age at which peak growth velocity occurred. Girls who consumed more (energy-adjusted) animal protein and less vegetable protein at ages 3-5 years had earlier menarche, and girls aged 1-2 years with higher dietary fat intakes and girls aged 6-8 years with higher animal protein intakes became adolescents with earlier peak growth. Controlling for body size, girls who consumed more calories and animal protein 2 years before peak growth had higher peak growth velocity. These findings may have implications regarding adult diseases whose risks are associated with adolescent growth and development factors.