No sex and age influence on the expression pattern and activities of human gastric alcohol and aldehyde dehydrogenases

Vasodilatory effect of nitroglycerin in Japanese subjects with different aldehyde dehydrogenase 2 (ALDH2) genotypes

The functional genetic polymorphism of aldehyde dehydrogenase 2 (ALDH2) influences the enzymatic activities of its wild type (Glu504 encoded by ALDH2*1) and mutant type (Lys504 encoded by ALDH2*2) proteins. The enzymatic activities of mutant-type ALDH2 are limited compared with those of the wild type. ALDH2 has been suggested as a critical factor for nitroglycerin-mediated vasodilation by some human studies and in vitro studies. Currently, there is no research on direct observations of the vasodilatory effect of nitroglycerin sublingual tablets, which is the generally used dosage form. In the present study, the contribution of ALDH2 to the vasodilatory effect of nitroglycerin sublingual tablets was investigated among three genotype groups (ALDH2*1/*1, ALDH2*1/*2, and ALDH2*2/*2) in Japanese. The results by direct assessments of in vivo nitroglycerin-mediated dilation showed no apparent difference in vasodilation among all genotypes of ALDH2. Furthermore, to analyze the effect of other factors (age and flow-mediated dilation), multiple regression analysis and Pearson's correlation coefficient analysis were carried out. These analyses also indicated that the genotypes of ALDH2 were not related to the degree of vasodilation. These results suggest the existence of other predominant pathway(s) for nitroglycerin biotransformation, at least with regard to clinical nitroglycerin (e.g., a sublingual tablet) in Japanese subjects.

Ethanol-metabolizing activities and isozyme protein contents of alcohol and aldehyde dehydrogenases in human liver: phenotypic traits of the ADH1B*2 and ALDH2*2 variant gene alleles

OBJECTIVE

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are principal enzymes responsible for the metabolism of ethanol. East Asian populations are unique in that they carry both a prevalent ADH1B*2 and a dominant-negative ALDH2*2 allele. A systematic investigation of ethanol-metabolizing activities in normal livers correlated with the corresponding functional allelic variations and protein contents of the relevant isozymes in respective enzyme families has been lacking.

MATERIALS AND METHODS

To obtain a reasonable sample size encompassing all possible genetic allelotypes of the ADH1B and ALDH2, 141 surgical liver specimens from adult Han Chinese were studied. Expression patterns and activities of ADH and ALDH were determined with stratification of the genetic phenotypes. Absolute protein contents as well as cellular localization of the activity and protein of ADH/ALDH isozymes were also investigated.

RESULTS

The activities of ADH1B*1/*2 and ADH1B*2/*2 allelic phenotypes were 5-6-fold those of the ADH1B*1/*1, suggesting that ADH1B*2 allele-encoded subunits are dominant over expression of hepatic ADH activity. The activities of the ALDH2-active phenotype were 90% higher than those of the ALDH2-inactive phenotype. Sex and age did not significantly influence the hepatic ADH and ALDH activities with specified genetic phenotypes. The isozyme protein contents were as follows in decreasing order: ADH1, ADH2, ALDH1A1, ALDH2, and ADH3. Both ADH1, but not ADH2/3, and ALDH1A1/2 showed a preferential expression in perivenular hepatocytes.

CONCLUSION

Functional correlations of ADH1B*2 and ALDH2*2 variant alleles in the liver provide a biochemical genetic basis suggesting their contribution toward variability in ethanol metabolism as well as susceptibility to alcoholism and alcohol-related diseases in East Asians.

Focus on alcoholic liver disease: from nosography to treatment

Abusive alcohol intake currently ranks as a major cause of liver disease, and is associated with significant mortality worldwide. Alcoholic liver disease (ALD) generically defines liver abnormalities ranging from liver steatosis to the end-stages of disease such as liver cirrhosis. Information regarding the precise incidence and prevalence of ALD is still limited by a lack of large population-based studies and by the absence of large systematic reviews of all epidemiological data available. However, existing collected data show an overall increase in the number of alcohol abusers and alcohol-related liver disease. The burden exerted on medical systems worldwide is significant, with hospitalization and management costs rising constantly over the years. A great number of all cirrhosis-related deaths in Europe and a significant percentage worldwide are associated with alcohol consumption. The main possible risk factors for ALD are the amount and duration of alcohol abuse, patterns of drinking and the type of alcoholic beverage consumed. However, ALD does not progress to cirrhosis in all patients, therefore a series of additional factors are implicated. Even though insufficiently studied, genetic factors are generally regarded as highly important, and the presence of comorbidities and dietary habits seem to play a role in disease onset and progression. This lack of clear pathophysiological data further translates in the absence of definite treatment for ALD and shall prove challenging in the coming years. In this article, we aimed to briefly review epidemiologic data on the burden of ALD, risk factors, clinical and nosographic as well as therapeutic aspects of this disease. Without attempting to be exhaustive, this short topic highlight emphasizes each point and may serve as a general guidance tool in the complicated literature related to ALD.

Genders and the concurrent use of cocaine and alcohol: Pharmacological aspects

AIMS

Gender-related differences in the pharmacological effects of addictive drug are an emerging issue. This review examines gender differences in both pharmacokinetic and pharmacodynamic aspects of alcohol and cocaine intake since they cause complex pharmacological interactions, not least the formation of the active metabolite cocaethylene.

METHODS

The MEDLINE database was searched from 1990 to 2014 in order to find articles related to gender differences in alcohol, cocaine and cocaethylene pharmacokinetics and pharmacodynamics.

RESULTS

Besides the well known gender differences in alcohol pharmacokinetics, women appear more susceptible to alcohol-mediated brain damage and seem to suffer more than men the acute effects of alcohol on hepatic and gonadal hormones. No significant gender differences have been found in the pharmacokinetics of cocaine taken alone; yet, in women pharmacological sensitivity to the drug seems to vary in relation to menstrual cycle; moreover, progesterone attenuates subjective effects of cocaine in women. Higher ratings at a subjective measure of mental/physical well-being have been observed in women when given cocaine and alcohol, alone or in combination. Finally, among subjects dependent on both alcohol and cocaine, men only benefit from naltrexone, whereas women used more cocaine during the trial and were less compliant to therapy than men.

CONCLUSIONS

The observed subtle gender differences in the pharmacokinetics and pharmacodynamics of both alcohol and cocaine may have no subtle influence on the natural history of the co-abuse of the two drugs by women.

Targeting aldehyde dehydrogenase 2: new therapeutic opportunities

A family of detoxifying enzymes called aldehyde dehydrogenases (ALDHs) has been a subject of recent interest, as its role in detoxifying aldehydes that accumulate through metabolism and to which we are exposed from the environment has been elucidated. Although the human genome has 19 ALDH genes, one ALDH emerges as a particularly important enzyme in a variety of human pathologies. This ALDH, ALDH2, is located in the mitochondrial matrix with much known about its role in ethanol metabolism. Less known is a new body of research to be discussed in this review, suggesting that ALDH2 dysfunction may contribute to a variety of human diseases including cardiovascular diseases, diabetes, neurodegenerative diseases, stroke, and cancer. Recent studies suggest that ALDH2 dysfunction is also associated with Fanconi anemia, pain, osteoporosis, and the process of aging. Furthermore, an ALDH2 inactivating mutation (termed ALDH2*2) is the most common single point mutation in humans, and epidemiological studies suggest a correlation between this inactivating mutation and increased propensity for common human pathologies. These data together with studies in animal models and the use of new pharmacological tools that activate ALDH2 depict a new picture related to ALDH2 as a critical health-promoting enzyme.

Inhibition of human alcohol and aldehyde dehydrogenases by cimetidine and assessment of its effects on ethanol metabolism

Previous studies have reported that cimetidine, an H2-receptor antagonist used to treat gastric and duodenal ulcers, can inhibit alcohol dehydrogenases (ADHs) and ethanol metabolism. Human alcohol dehydrogenases and aldehyde dehydrogenases (ALDHs), the principal enzymes responsible for metabolism of ethanol, are complex enzyme families that exhibit functional polymorphisms among ethnic groups and distinct tissue distributions. We investigated the inhibition by cimetidine of alcohol oxidation by recombinant human ADH1A, ADH1B1, ADH1B2, ADH1B3, ADH1C1, ADH1C2, ADH2, and ADH4, and aldehyde oxidation by ALDH1A1 and ALDH2 at pH 7.5 and a cytosolic NAD(+) concentration. Cimetidine acted as competitive or noncompetitive inhibitors for the ADH and ALDH isozymes/allozymes with near mM inhibition constants. The metabolic interactions between cimetidine and ethanol/acetaldehyde were assessed by computer simulation using the inhibition equations and the determined kinetic constants. At therapeutic drug levels (0.015 mM) and physiologically relevant concentrations of ethanol (10 mM) and acetaldehyde (10 μM) in target tissues, cimetidine could weakly inhibit (<5%) the activities of ADH1B2 and ADH1B3 in liver, ADH2 in liver and small intestine, ADH4 in stomach, and ALDH1A1 in the three tissues, but not significantly affect ADH1A, ADH1B1, ADH1C1/2, or ALDH2. At higher drug levels, which may accumulate in cells (0.2 mM), the activities of the weakly-inhibited enzymes may be decreased more significantly. The quantitative effects of cimetidine on metabolism of ethanol and other physiological substrates of ADHs need further investigation.

Expression pattern, ethanol-metabolizing activities, and cellular localization of alcohol and aldehyde dehydrogenases in human large bowel: association of the functional polymorphisms of ADH and ALDH genes with hemorrhoids and colorectal cancer

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are principal enzymes responsible for metabolism of ethanol. Functional polymorphisms of ADH1B, ADH1C, and ALDH2 genes occur among racial populations. The goal of this study was to systematically determine the functional expressions and cellular localization of ADHs and ALDHs in human rectal mucosa, the lesions of adenocarcinoma and hemorrhoid, and the genetic association of allelic variations of ADH and ALDH with large bowel disorders. Twenty-one surgical specimens of rectal adenocarcinoma and the adjacent normal mucosa, including 16 paired tissues of rectal tumor, normal mucosae of rectum and sigmoid colon from the same individuals, and 18 surgical mixed hemorrhoid specimens and leukocyte DNA samples from 103 colorectal cancer patients, 67 hemorrhoid patients, and 545 control subjects recruited in previous study, were investigated. The isozyme/allozyme expression patterns of ADH and ALDH were identified by isoelectric focusing and the activities were assayed spectrophotometrically. The protein contents of ADH/ALDH isozymes were determined by immunoblotting using the corresponding purified class-specific antibodies; the cellular activity and protein localizations were detected by immunohistochemistry and histochemistry, respectively. Genotypes of ADH1B, ADH1C, and ALDH2 were determined by polymerase chain reaction-restriction fragment length polymorphisms. At 33mM ethanol, pH 7.5, the activity of ADH1C*1/1 phenotypes exhibited 87% higher than that of the ADH1C*1/*2 phenotypes in normal rectal mucosa. The activity of ALDH2-active phenotypes of rectal mucosa was 33% greater than ALDH2-inactive phenotypes at 200μM acetaldehyde. The protein contents in normal rectal mucosa were in the following order: ADH1>ALDH2>ADH3≈ALDH1A1, whereas those of ADH2, ADH4, and ALDH3A1 were fairly low. Both activity and content of ADH1 were significantly decreased in rectal tumors, whereas the ALDH activity remained unchanged. The ADH activity was also significantly reduced in hemorrhoids. ADH4 and ALDH3A1 were uniquely expressed in the squamous epithelium of anus at anorectal junctions. The allele frequencies of ADH1C*1 and ALDH2*2 were significantly higher in colorectal cancer and that of ALDH2*2 also significantly greater in hemorrhoids. In conclusion, ADH and ALDH isozymes are differentially expressed in mucosal cells of rectum and anus. The results suggest that acetaldehyde, an immediate metabolite of ethanol, may play an etiological role in pathogenesis of large bowel diseases.

Ethanol elimination rates in men and women in consideration of the calculated liver weight

The purpose of the study was to examine gender differences on the pharmacokinetics of ethanol. Sixty-eight healthy men and 64 healthy women with normal body mass indexes received between 0.79 and 0.95 g ethanol/kg body weight in the form of their choice after they had eaten a "typical" breakfast. The aimed concentration for both genders was a blood alcohol concentration C(0) of 0.104 g/dl. Blood samples in the elimination phase were taken in 10- to 20-min intervals beginning after completion of absorption. The maximum blood ethanol concentration was 0.0819+/-0.0184 g/dl for women and 0.0841+/-0.0155 g/dl for men. The hourly ethanol elimination rate, calculated over a linear function, in blood of 0.0179+/-0.0030 g/dl/h in women was significantly higher than the 0.0159+/-0.0029 g/dl/h for men (P<.0001). In relation to the liver weight, the hourly elimination rates were 5.008+/-0.678 g/kg liver/h for women and 4.854+/-0.659 g/kg liver/h for men, and were not statistically significant. The different liver masses as calculated in relation to the distribution volume account for the differing ethanol elimination rates between men and women.

Rates of ethanol metabolism decrease in sons of alcoholics following a priming dose of ethanol

Rapid changes in rates of ethanol metabolism in response to acute ethanol administration have been observed in animals and humans. To examine whether this phenomenon might vary by risk for alcoholism, 23 young men with a positive family history of alcoholism (family history positive [FHP]) were compared to 15 young men without a family history of alcoholism (family history negative [FHN]). Rates of ethanol metabolism were measured in all subjects first after an initial ethanol dose (0.85 g/kg) and then, several hours later, a second dose (0.3 g/kg), and the two rates were compared. The two groups of subjects were similar in their histories of ethanol consumption. FHP subjects demonstrated faster initial rates of ethanol metabolism, 148+/-36 mg/kg/h, compared to FHN subjects, 124+/-18 mg/kg/h, P=.01. However, FHN subjects increased their rate of metabolism by 10+/-27% compared to a decrease of -15+/-24% in FHP subjects, P=.007. Fifty-two percent of the FHP and none of the FHN subjects exhibited a decline in metabolic rate of 20% or more, P=.0008. Since a significant proportion of FHP subjects exhibited a decrease in the second rate of ethanol metabolism, these preliminary data might help to partly explain why FHP individuals differ in their sensitivity to ethanol and are more likely to develop alcohol dependence.

Review article: alcoholic liver disease--pathophysiological aspects and risk factors

BACKGROUND

Alcoholic liver disease has a known aetiology but a complex and incompletely known pathogenesis. It is an extremely common disease with significant morbidity and mortality, but the reason why only a relatively small proportion of heavy drinkers progress to advanced disease remains elusive.

AIM

To recognize the factors responsible for the development and progression of alcoholic liver disease, in the light of current knowledge on this matter.

METHODS

We performed a structured literature review identifying studies focusing on the complex pathogenetic pathway and risk factors of alcoholic liver disease. Results In addition to the cumulative amount of alcohol intake and alcohol consumption patterns, factors such as gender and ethnicity, genetic background, nutritional factors, energy metabolism abnormalities, oxidative stress, immunological mechanisms and hepatic co-morbid conditions play a key role in the genesis and progression of alcoholic liver injury.

CONCLUSIONS

Understanding the pathogenesis and risk factors of alcoholic liver disease should provide insight into the development of therapeutic strategies.

Functional Assessment of Human Alcohol Dehydrogenase Family in Ethanol Metabolism: Significance of First-Pass Metabolism

BACKGROUND

Alcohol dehydrogenase (ADH) is the principal enzyme responsible for ethanol metabolism in mammals. Human ADH constitutes a unique complex enzyme family with no equivalent counterpart in experimental rodents. This study was undertaken to quantitatively assess relative contributions of human ADH isozymes and allozymes to hepatic versus gastric metabolism of ethanol in the context of the entire family.

METHODS

Kinetic parameters for ethanol oxidation for recombinant human class I ADH1A, ADH1B1, ADH1B2, ADH1B3, ADH1C1, and ADH1C2; class II ADH2; class III ADH3; and class IV ADH4 were determined in 0.1 M sodium phosphate at pH 7.5 over a wide range of substrate concentrations in the presence of 0.5 mM NAD+. The composite numerical formulations for organ steady-state ethanol clearance were established by summing up the kinetic equations of constituent isozymes/allozymes with the assessed contents in livers and gastric mucosae with different genotypes.

RESULTS

In ADH1B*1 individuals, ADH1B1 and ADH1C allozymes were found to be the major contributors to hepatic-alcohol clearance; ADH2 made a significant contribution only at high ethanol levels (> 20 mM). ADH1B2 was the major hepatic contributor in ADH1B*2 individuals. ADH1C allozymes were the major contributor at low ethanol (< 2 mM), whereas ADH1B3 the major form at higher levels (> 10 mM) in ADH1B*3 individuals. For gastric mucosal-alcohol clearance, the relative contributions of ADH1C allozymes and ADH4 were converse as ethanol concentration increased. It was assessed that livers with ADH1B*1 may eliminate approximately 95% or more of single-passed ethanol as inflow sinusoidal alcohol reaches approximately 1 mM and that stomachs with different ADH1C genotypes may remove 20% to 30% of single-passed alcohol at the similar level in mucosal cells.

CONCLUSIONS

This work provides just a model, but a strong one, for quantitative assessments of ethanol metabolism in the human liver and stomach. The results indicate that the hepatic-alcohol clearance of ADH1B*2 individuals is higher than that of the ADH1B*1 and those of the ADH1B*3 versus the ADH1B*1 vary depending on sinusoidal ethanol levels. The maximal capacity for potential alcohol first-pass metabolism in the liver is greater than in the stomach.

Retinoic acid formation from retinol in the human gastric mucosa: role of class IV alcohol dehydrogenase and its relevance to morphological changes

Alcohol dehydrogenase (ADH) participates in the formation of retinoic acid from retinol in various organs including the gastric mucosa. However, its clinical significance still remains to be clarified. In this study, we identified the ADH isoforms responsible for the retinoic acid formation among various ADH isoforms and examined associations among the ADH activities, the retinoic acid formation level, and morphological changes in the human gastric mucosa. Human gastric samples were endoscopically obtained from 67 male subjects. Morphological changes were assessed by the Sydney system and activities of class I, III, and IV ADH isoforms were determined in each specimen. In 26 cases, levels of all-trans retinoic acid (ATRA) formation from all-trans retinol were examined. Among activities of the three ADH isoforms, class IV ADH activity was solely associated with the ATRA formation level. This association was found even when subjects' age and Helicobacter pylori infection status were adjusted. As the degrees of inflammation, atrophy, and intestinal metaplasia increased, the class IV ADH activity as well as the potential for the ATRA formation decreased. Class IV ADH is a major enzyme in the retinoic acid supply in the human gastric mucosa, and the reduction of its activity was associated with decreasing retinoic acid supply and progression of inflammation, atrophy, and intestinal metaplasia in the gastric mucosa. In that retinoic acid is a key molecule for maintaining normal morphology, the reduction of class IV ADH activity may be involved in the pathogenesis of these morphological changes in the human gastric mucosa.

Ethanol and acetaldehyde in alcoholic cardiomyopathy: from bad to ugly en route to oxidative stress

Alcoholic cardiomyopathy is characterized by cardiomegaly, disruptions of myofibrillary architecture, reduced myocardial contractility, decreased ejection fraction, and enhanced risk of stroke and hypertension. Although several mechanisms have been postulated for alcoholic cardiomyopathy, including oxidative damage, accumulation of triglycerides, altered fatty acid extraction, decreased myofilament Ca(2+) sensitivity, and impaired protein synthesis, neither the mechanism nor the ultimate toxin has been unveiled. Primary candidates acting as specific toxins of myocardial tissue are ethanol; its first and major metabolic product, acetaldehyde; and fatty acid ethyl esters. Acetaldehyde has been demonstrated to impair directly cardiac contractile function, disrupt cardiac excitation-contractile coupling, and contribute to oxidative damage and lipid peroxidation. Acetaldehyde-elicited cardiac dysfunction may be mediated through cytochrome P450 oxidase, xanthine oxidase, and the stress-signaling cascade. Unfortunately, the most direct approach that can be used to examine toxicity is hampered by the fact that direct intake of acetaldehyde is highly toxic and unsuitable for long-term study. To overcome this obstacle, transgenic mice have been used to alter artificially ethanol/acetaldehyde metabolism, resulting in elevated acetaldehyde concentrations after ethanol ingestion. In this review, we summarize results obtained with the use of transgenic animal models to elucidate the role of acetaldehyde in the mechanism of action in alcoholic cardiomyopathy.

The metabolic role of human ADH3 functioning as ethanol dehydrogenase

Human class III alcohol dehydrogenase (ADH3), also known as glutathione-dependent formaldehyde dehydrogenase, exhibited non-hyperbolic kinetics with ethanol at a near physiological pH 7.5. The S(0.5) and k(cat) were determined to be 3.4+/-0.3 M and 33+/-3 min(-1), and the Hill coefficient (h) 2.21+/-0.09, indicating positive cooperativity. Strikingly, the S(0.5) for ethanol was found to be 5.4 x 10(6)-fold higher than the K(m) for S-(hydroxymethyl)glutathione, a classic substrate for the enzyme, whereas the k(cat) for the former was 41% lower than that for the latter. Isotope effects on enzyme activity suggest that hydride transfer may be rate-limiting in the oxidation of ethanol. Kinetic simulations using the experimentally determined Hill constant suggest that gastric ADH3 may highly effectively contribute to the first-pass metabolism at 0.5-3 M ethanol, an attainable range in the gastric lumen during alcohol consumption. The positive cooperativity mainly accounts for this metabolic role of ADH3.

Human class IV alcohol dehydrogenase: kinetic mechanism, functional roles and medical relevance

Human alcohol dehydrogenase (ADH) constitutes a complex family. Class IV ADH (ADH4) is characteristic in its epithelial expression in the aerodigestive tract and high V(max) and K(m) for oxidation of ethanol. ADH4 exhibits the highest catalytic efficiency for retinol oxidation in human ADH family. Initial velocity, product inhibition, and dead-end inhibition studies indicate that ADH4, when functioning as ethanol dehydrogenase, conforms to an ordered sequential mechanism with coenzyme binding first and releasing last in catalytic cycle. When functioning as retinol dehydrogenase, the mechanism of ADH4 deduced from steady-state kinetic and equilibrium-binding studies is best described as a rapid equilibrium random mechanism with two dead-end ternary complex for retinol oxidation and a rapid equilibrium ordered mechanism with one dead-end ternary complex for retinal reduction, a unique mechanistic form for zinc-containing ADHs in the medium chain dehydrogenase/reductase superfamily. Kinetic and genetic studies support the proposal that ADH4 may play two important physiological roles, i.e., as a major contributor to first-pass metabolism of ethanol in stomach as well as involvement in the synthesis of retinoic acid, a hormonal ligand controlling a nuclear receptor signaling pathway that regulates growth, development, and epithelial maintenance. Quantitative simulation studies indicate that retinol metabolism through ADH pathway can be inhibited to a significant extent during alcohol consumption. The perturbation of retinoic acid synthesis by ethanol may underlie the pathogenesis of fetal alcohol syndrome and alcohol-related upper digestive tract cancer.

Effects of aldehyde dehydrogenase-2 genetic polymorphisms on metabolism of structurally different aldehydes in human liver

Genotype analysis of the aldehyde dehydrogenase (ALDH)-2 gene was performed using an improved simplified method, and effects of the genotype on the metabolism of a variety of aldehydes in different fractions of human liver cells were investigated. The effects of sex, aging, smoking, drinking alcohol, liver function, and various drugs on ALDH activity were also analyzed. Of the 39 subjects, eight were heterozygotes of the wild (ALDH2*1) and mutant (ALDH2*2) alleles, and the others were homozygotes of the wild allele. ALDH activity toward acetaldehyde in liver mitochondria from subjects with a mutant allele was less than 10% of that with two alleles of wild-type, and the activities toward formaldehyde, propionaldehyde, n-butyraldehyde, capronaldehyde, and heptaldehyde were also significantly lower in the ALDH2*1/*2 rather than ALDH2*1/*1 group. However, the metabolism of octylaldehyde, decylaldehyde, retinaldehyde, benzaldehyde, 3-hydroxybenzaldehyde, and 2,5-dihydroxybenzaldehyde was similar in the two genotypes. Changes in activity in the cytosolic fraction were similar to those in mitochondria. There was no significant difference in ALDH activity in microsomes between the two groups. Total activities of ALDH toward acetaldehyde and other short-chain aliphatic aldehydes in supernatant fractions of homogenized liver were affected in a manner similar to that in mitochondria. Our results suggest that the single nucleotide polymorphisms of the ALDH2 gene only alter the metabolism of aldehydes with a short aliphatic chain. Furthermore, sex, drinking alcohol, and smoking had little effect on ALDH activity, although the activity in elderly individuals tended to be lower albeit statistically insignificant.