Association between Reduction of Muscle Mass and Faster Declines in Global Cognition among Older People: A 4-Year Prospective Cohort Study.

OBJECTIVES: A few studies reported that both decrease and increase in body mass index (BMI) were associated with the development of dementia in later life. However, it is unclear what changes in body composition are associated with cognitive decline. This study investigated the longitudinal influences of changes in body composition on cognitive function among community-dwelling adults. DESIGN, SETTING AND PARTICIPANTS: This longitudinal study included older adults aged ≥60 years without cognitive impairment who participated in National Institute for Longevity Sciences - Longitudinal Study of Aging. MEASUREMENTS: Cognitive function was assessed using the MMSE. Body composition was measured by a dual-energy X-ray absorptiometry system. Then, BMI, fat mass index (FMI), fat-free mass index (FFMI), and muscle mass index (MMI) were calculated. The changes in body composition over 6 years (second wave to fifth wave) were calculated, and three groups were created: decreased group, decrease of >5%; stable group, change within 5%, and increased group, increase of >5%. In statistical analysis, a linear mixed model was applied by sex to investigate the influences of body composition changes on cognitive function over 4 years (fifth wave to seventh wave). RESULTS: This study analyzed 515 participants (mean age, 67.05 years; 53.4% men). Men with decreased group in FFMI and MMI exhibited faster declines in MMSE scores than those with stable group (ß [95% CI]: FFMI, -0.293 [-0.719 to -0.020]; MMI, -0.472 [-0.884 to -0.059]). In women, there was no significant association between body composition changes and cognitive functions. CONCLUSIONS: Decrease in fat-free mass and muscle mass is associated with faster cognitive declines in men. These results suggest the importance of continuous monitoring of muscle mass to prevent cognitive decline in later life.

Cross-Sectional Associations of Sarcopenia and Its Components with Neuropsychological Performance among Memory Clinic Patients with Mild Cognitive Impairment and Alzheimer's Disease.

BACKGROUND: The association of sarcopenia with cognitive function in its specific domains remains poorly understood. OBJECTIVES: To investigate the association of sarcopenia and its components with neuropsychological performance among patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). DESIGN: Cross-sectional design. SETTING: A memory clinic in Japan. PARTICIPANTS: The study included 497 MCI/684 AD patients aged 65-89 years. MEASUREMENTS: Patients were assessed for muscle mass by bioelectrical impedance analysis, muscle strength by hand grip strength (HGS), and physical performance by timed up and go test (TUG). Sarcopenia was defined as presence of both low muscle strength and low muscle mass. The patients underwent neuropsychological tests, including logical memory, frontal lobe assessment battery, word fluency test, Raven's colored progressive matrices, digit span, and the Alzheimer's disease assessment scale-cognitive subscale (ADAS-cog). RESULTS: The prevalence of sarcopenia in men and women was 24.1% and 19.5%, respectively. In multiple regression analyses adjusting for confounders, unlike in men, sarcopenia was associated with memory function in women (ADAS-cog, memory domain, coefficient = 1.08, standard error (SE) = 0.36), which was thought likely due to the relationship between HGS and memory function (immediate recall of logical memory, coefficient = 0.07, SE = 0.03; ADAS-cog, memory domain, coefficient = -0.10, SE = 0.03). Of the components of sarcopenia in both sexes, HGS and TUG were associated with visuospatial function and frontal lobe function, respectively. CONCLUSIONS: The specific association of sarcopenia and its components with cognitive domains may provide the key to elucidating the muscle-brain interactions in AD.

Pulmonary surfactant is a potential endogenous inhibitor of proteolytic activation of Sendai virus and influenza A virus.

The pathogenicities of influenza viruses and paramyxoviruses have been proposed to be primarily determined by a host cell protease(s) that activates viral infectivity by proteolytic cleavage of the envelope glycoproteins. We recently isolated a trypsin-type endoprotease, named tryptase Clara, from rat bronchial and bronchiolar epithelial Clara cells, which is secreted into the airway lumen and activates Sendai virus and influenza A virus proteolytically. We report here that surfactant in the bronchial fluid inhibited tryptase Clara specifically, having a Ki value of 0.13 microM, and inhibited the proteolytic activations by tryptase Clara in vitro and in organ cultures of rat lung. Intranasal infection of rats with Sendai virus was shown to stimulate secretion of tryptase Clara without changing the amount of surfactant in the bronchial lumen, resulting in a preferable condition for proteolytic viral activation and multiplication.

Electron immunohistochemical localization in rat bronchiolar epithelial cells of tryptase Clara, which determines the pneumotropism and pathogenicity of Sendai virus and influenza virus.

The intracellular localization in rat bronchiolar epithelial cells of a novel trypsin-like protease named tryptase Clara, a possible activator of inactive viral fusion glycoprotein of influenza A and wild-type Sendai virus in the respiratory tract, was examined by electron microscopy. In thin sections embedded in LR White, gold particles indicating immunoreactivity of tryptase Clara were detected specifically in secretory granules of Clara cells. No immunoreactivity was detected in bronchiolar ciliated cells, alveolar cells including epithelial Type I and II cells, or alveolar macrophages. Some granules enveloped in a thin membrane and labeled intensely with immunogold particles were seen protruding from peripheral and submembrane regions and a few were observed free in the airway lumen. Scanning electron microscopy also revealed smooth droplets along the main body of Clara cells. These data suggest that tryptase Clara is secreted into the bronchiolar lumen. These findings are the first to show the subcellular localization of tryptase Clara in rat bronchioles and suggest the site of proteolytic activation of the progeny of enveloped pneumotropic viruses, such as Sendai virus and influenza virus.

Specific assay method for the activities of cathepsin L-type cysteine proteinases.

We have established a new differential assay method for cathepsin L-type proteinases using specific inhibitors, E-64 for all cysteine proteinases, CA-074 for cathepsin B, and PLCPI for cathepsin L-type proteinases with Z-Phe-Arg-MCA as the substrate. The value of cathepsin B calculated by this method did not coincide with value assayed directly in terms of the hydrolysis of Z-Arg-Arg-MCA, a specific substrate for cathepsin B. The activities of cathepsin L-type proteinases, cathepsins B and J in rat liver and kidney were assayed at the same time using this new assay method as a representative example.

Anorexigenic substance isolated from feces of rat and mouse.

A substance was isolated from the feces of conventional rats and mice which were fed laboratory diets. Marked reduction in food intake occurred for a few hours after intraperitoneal administration of this substance, while water intake also decreased. Two hr after the injection, when the anorectic effect appeared to be the strongest, no change was found in body temperature or blood glucose, but free amino acids in plasma were decreased. A comparative study using germfree and conventional mice indicated that the anorexigenic substance was produced by gastrointestinal microflora, since the yields of the anorexigenic substance from germfree mice was less than one tenth of that from conventional mice. A partially purified form of the substance, with large molecular weight, was isolated by Sephadex G-150 fractionation. It contained protein but the anorexigenic activity was not diminished by protein digestion.

Effect of amino acid mixtures on nasal allergic responses induced by toluene diisocyanate in mice.

We studied the effect of various amino acid mixtures on nasal allergy induced by the intranasal application of toluene diisocyanate (TDI) in mice. In Experiment 1 (Exp. 1), mice were fed a 25% casein, soy protein isolate (SPI), egg white protein (EW) or gluten diet. In Experiment 2 (Exp. 2), mice were fed a 25% amino acid mixture diets patterned after casein (AA-casein), SPI (AA-SPI), EW protein (AA-EW) or gluten (AA-gluten). In Experiment 3 3 (Exp. 3) we modified the glutamine/glutamic acid (Gln/Glu) concentrations in the amino acid mixtures. Mice were fed a 25% AA-SPI, low Gln/Glu AA-SPI (LG-AA-SPI), AA-EW or high Gln/Glu AA-EW (HG-AA-EW) diet. At the 5th week, mice were divided into sensitized (sen-) and non-sensitized (ns-) groups. The mice in sensitized groups were treated with two courses of intranasal application of toluene diisocyanate (TDI) in ethyl acetate for 5 consecutive days, separated by 9 days rest. The non-sensitized groups of mice were treated with a vehicle. Nine days after the second sensitization, all mice were provoked by TDI. Nasal responses and serum IgE concentration were studied. The findings of Exp. 1 showed that the sen-EW group exhibited a lower body weight gain, higher nasal symptom score and higher IgE concentration than the other sensitized groups. The findings dings of Exp. 2 showed that the sen-EW group had a lower body weight gain, higher nasal symptom score and higher IgE concentration than the other sensitized groups. In Exp. 3, the AA-EW group showed a higher total nasal score and IgE concentration than the HG-AA-EW group, however, the findings of LG-AA-SPI and AA-SPI were similar. These findings demonstrated that amino acid mixtures affect nasal allergy induced by the intranasal application of TDI in mice.

Arginine-enriched solution induces a marked increase in muscle glutamine concentration and enhances muscle protein synthesis in tumor-bearing rats.

Using a transplantable Yoshida sarcoma in a rat model of total parenteral nutrition (TPN), we measured the effectiveness of an arginine-enriched amino acid solution (AI-82) on muscle glutamine concentration and muscle protein synthesis compared with that of a conventional amino acid solution (Proteamin12). After tumor-bearing rats had been given one of two isocaloric TPN regimens for 6 days, [15N]glycine (99 atom %) containing TPN solution was infused into animals at a constant rate of 8 mg of [15N]glycine per hour for 18 hours, after which the liver, skeletal muscle (gastrocnemius muscle), and tumor protein synthesis rates were measured. A significantly increased whole muscle protein synthesis rate was observed in the AI-82 group; there was no difference in the whole liver and tumor protein synthesis rates between the two groups. When each TPN solution was administered for 1 week, muscle concentrations of arginine, ornithine, glutamine, and glutamate were considerably higher in the AI-82 group than in the Proteamin12 group, and these differences were also accompanied by a decrease in the plasma branched-chain amino acid (BCAA) (leucine, isoleucine, and valine) levels in the AI-82 group. The high levels of muscle glutamine concentration in the AI-82 group were investigated in connection with the high use of exogenous branched-chain amino acids.

Evaluation of the effect of arginine-enriched amino acid solution on tumor growth.

To investigate the effect of arginine-enriched solution on tumor growth and metastasis, rats were infused with solutions containing 5.5 and 0.66% arginine for 8 days. Infusions were started at the same time of subcutaneous transplant of Yoshida sarcoma. Arginine-rich solution suppressed tumor growth at an early stage and prevented metastases to the liver and kidney. In addition, arginine supplements enhanced the phagocytic activity of alveolar macrophages. It also resulted in maintenance of a positive nitrogen balance and prevented the increases in the levels of several amino acids observed in the control group. The suppressive effect of arginine-enriched solution on tumor growth may be due to its activation of the immunologic system, in which the phagocytic activity of macrophages probably participates.

Phagocytosis of alveolar macrophages after conagenin injection to rats.

Phagocytic functions of rat alveolar macrophages (AM) following intraperitoneal injection of conagenin (CNG) and of AM sub-populations fractionated by Percoll discontinuous gradient centrifugation were investigated. Phagocytosis of opsonized-sheep red blood cells (SRBC) following in vitro incubation with CNG showed a significant increase in a higher density of AM (fraction IV). In addition, phagocytosis was also increased in lower density ones (fractions I and II) by macrophage-activating factor (MAF) co-cultivation. CNG-injected rats for 5 consecutive days showed a dose-dependent increase in phagocytosis of AM compared to the control rats. Although the distribution of AM sub-population in rats injected CNG was not significantly different compared to the control rats, phagocytosis was significantly increased in AM of a lower density fraction (fraction II). These results suggest that CNG directly increases phagocytosis of AM in a higher density fraction, and indirectly enhances phagocytosis in AM of a lower density fraction via increasing MAF-like material production.

Lysosomal changes in fatty liver induced in rats by high protein pyridoxine-deficient diet.

The effect of high-protein pyridoxine-deficient diet on the localization of lysosomes and acid phosphatase activity in the rat liver was studied using light and electron microscopy. Numerous lysosomes containing lipid droplets appeared to arise directly from GERI (Golgi apparatus, endoplasmic reticulum and lysosomes) near bile canaliculi and thereafter large crystal clefts were frequently found in these lysosomes. The increase appearance of lysosomes in hepatocytes was compatible with increased lipid droplets and represented an indication of breakdown of stored lipids. Acid phosphatase activity was localized almost exclusively in lysosomes with or without lipid droplets. We postulated that one of the causes of accumulation of lipid in hepatocytes, including that of triglyceride and cholesteryl ester, might be associated with a relative deficiency of intralysosomal digestion in these conditions.

Effects of choline deficiency and phosphatidylcholine on fat absorption in rats.

Transfer of lipid to the lymph by the intestine was studied in rats fed on choline-deficient or choline-supplemented diet for 2 weeks. In choline-deficient rats, lymph output was reduced. Choline deficiency impaired the incorporation of glycerol tri[1-14C]oleate into triglyceride in the lymph. The triglyceride level in lymph lipoproteins was lower in choline-deficient rats than in controls. Ultrastructural studies suggested that impaired release of lipoproteins was responsible for accumulation of fat in intestinal absorptive cells. These defects are probably related to changes in the membrane system of the intestine and to a failure in lipid droplet movement within absorptive cells, resulting from alterations in the microfilaments. Oral administration of phosphatidylcholine to rats on choline-deficient diet rapidly improved the decreased lymph output and the impaired incorporation of glycerol tri[1-14C]oleate into triglyceride and reduced fat deposition in intestinal epithelial cells. In conclusion, phospholipids such as choline are confirmed as being extremely important in the absorption of fat by the possible mechanism of fat transport across the membrane.

Glutamine supplementation prevents the decrease of mitogen response after a treadmill exercise in rats.

The effect of glutamine (Gln)-supplemented diet on mitogen response decreased immediately after a treadmill exercise was examined by measuring the proliferations of peripheral blood lymphocytes (PBL) with phytohemagglutinin (PHA) and concanavalin A (ConA) in male Fisher rats. Although the plasma Gln concentration was significantly decreased in the control group immediately after a treadmill exercise (20 m/min, 60 min) compared to rested rats, plasma Gln concentration of rats fed Gln-supplemented diet for 3 weeks was significantly higher than that of control group in resting and was not significantly decreased even immediately after a treadmill exercise. In addition, proliferation of PBL with PHA or ConA and interleukin 2 (IL2) production were also significantly decreased immediately after a treadmill exercise in control group. On the contrary, their functions were almost maintained in Gln-supplemented group even immediately after a treadmill exercise. PBL from rats fed Gln-supplemented diet showed a higher response to mitogens such as PHA and ConA compared to the control group. Furthermore, their PBL showed higher incorporation of [3H]Gln compared to that of the control group irrespective of treadmill exercise. These results indicate that the preventive effect of Gln-supplemented diet on mitogen response decreased after a treadmill exercise is due to an increased response to mitogen and increased uptake of Gln as sources of fuel and nucleotides to the immune cells.

Enhanced phagocytosis of rat alveolar macrophages by intravenous infusion of an arginine-enriched solution.

Phagocytosis of rat alveolar macrophages (AM) was enhanced by the infusion of arginine-rich solution for 7 days. The enhancement of phagocytosis by arginine-rich solution was due to not the difference in the distribution of AM subpopulations (I to IV) but the difference in phagocytic activity of AM in fraction IV. In the process of phagocytosis, there were no significant differences in the stages of migration, attachment, and digestion between control and arginine-rich solutions, although AM from fraction IV of rats infused with arginine-rich solution showed significantly higher ingestion of opsonized sheep red blood cells (SRBC) compared to that of control group. Furthermore, the production of macrophage-activating factor (MAF) from rat splenocytes was higher in arginine-rich group than that of control group. AM from fraction IV of rats fed a stock diet had a higher arginase activity and showed a significant increase of phagocytosis following in vitro incubation with L-arginine (25 and 50 mM) for 24 h. From these results, the enhanced phagocytosis of AM by arginine-rich solution may be due to the increased phagocytosis of AM from fraction IV, in which the higher sensitivity of AM from fraction IV to arginine and the higher production of MAF from splenocytes following the infusion of arginine-rich solution participate.

The role of macrophages in increased mitogen response of rat splenic lymphocytes following in vitro incubation with vitamin E.

The role of macrophages (M phi) in the enhancement of lymphocyte proliferation by alpha-tocopherol (VE) was investigated using rat splenocytes. The proliferation of whole splenocytes was significantly higher than that of M phi-depleted splenocytes at all concentrations of concanavalin A (Con A; 0.5-10 micrograms/ml). When whole and M phi-depleted splenocytes were preincubated with VE (2 micrograms/ml) for 24 h, the proliferation of whole splenocytes was significantly enhanced compared to that of whole splenocytes preincubated with medium alone. In contrast, M phi-depleted splenocytes did not show any increase of proliferation following in vitro pretreatment with VE. When the splenic: M phi pretreated with both VE (2 micrograms/ml) and Con A (10 micrograms/ml) for 24 h were further incubated with splenic lymphocytes, their proliferation was significantly enhanced compared to that of splenic lymphocytes cultured with splenic M phi pretreated with Con A. In this experiment, the medium containing 2-mercaptoethanol (2-ME) had the ability to enhance splenic lymphocyte proliferation, which masked the enhanced effect of VE on splenic: lymphocyte proliferation. Furthermore, in vitro treatment of VE could not decrease the production of prostaglandin E2, but could enhance the production of interleukin 1 from splenic M phi. These results suggest that M phi play an important role in the proliferation of splenic lymphocytes following in vitro incubation with VE, which is closely associated with the action of VE as an immunomodulator rather than antioxidant.

Effects of vitamin E deficiency on the functions of splenic lymphocytes and alveolar macrophages.

This study has been done to determine the effect of vitamin E deficiency on the functions of splenic lymphocytes and alveolar macrophages (AM) in rats. Vitamin E deficiency did not cause any changes of body weight, spleen and thymus weights, and numbers of splenocytes and AM compared with those of control rats. And also, we could not find any significant changes of lymphocyte responses to mitogens (PHA, Con A, and LPS) and natural killer cell (NK) activity except for AM function in vitamin E-deficient rats. In vitamin E-deficient rats, AM showed a higher phagocytosis than that of control rats. After in vitro treatment with a macrophage-activating factor (MAF) for 4 h at 37 degrees C, AM from control rats showed a greater enhancement (167%) of phagocytic activity compared with that of AM from vitamin E-deficient rats. When the effect of MAF prepared from splenic lymphocytes of rats from control or vitamin E-deficient rats on phagocytosis of AM was studied, MAF from control rats showed an about 150% increase of phagocytic activity in a 1/250 dilution of MAF. However, MAF from vitamin E-deficient group had almost no effect on phagocytosis of AM in the same dilution of MAF as control rats. These results may suggest that vitamin E deficiency induces the higher phagocytic function of AM responsible for host defense in the lung, but their enhancement is not due to the activation by MAF from lymphocytes.

Effects of dietary restriction on cellular immunity in rats.

Phagocytosis of opsonized sheep red blood cells (SRBC) by alveolar macrophages (AM) was measured in rats fasted for 1 to 9 days or fed on diets restricted 20 to 95% compared to control group for 2 and 8 weeks. In rats fasted for 1 to 6 days, AM showed an increased phagocytosis at 2 days after fasting, but their phagocytic activity remarkably decreased afterwards. Furthermore, phagocytic activity of AM per rat revealed much more decrease at 3 to 6 days after fasting. Then the production of interleukin-1 (IL-1) by AM increased with prolonged fasting, but the production of prostaglandin E2 (PGE2) by AM cultured with lipopolysaccharide (LPS) conversely decreased in rats fasted for 2 days or longer. The proliferation of splenocytes increased with prolonged fasting. On the other hand, 20 to 95% restricted diets induced the increased phagocytosis of AM with prolonged experimental period. However, phagocytic activity of AM per rat showed significant increase only in rats on a 40% restricted diet. The findings suggest that differences in both duration and degree of dietary restriction modulate phagocytic function of AM, and may contribute to explaining, in part, conflicting observations which have been obtained on the immunologic state in malnourished animals.

Levels of pulmonary surfactant protein A in fetal lung and amniotic fluid from protein-malnourished pregnant rats.

Surfactant protein A (SP-A) is a major apo-protein of pulmonary surfactant, which lines the alveolar walls, lowering the surface tension to prevent lung collapse. Pregnant rats were divided into two groups which received a diet with either 5% or 20% protein from gestational day 9. By a sensitive immunoassay, SP-A levels in the fetal lungs and the amniotic fluid showed a dramatic increase with advancing gestation after the initial appearance on gestational day 18 in both diet groups. Significantly lower levels of SP-A in pregnant rats fed 5% protein diet than those in pregnant rats fed 20% protein diet were observed in the fetal lungs on gestational day 21 and in the amniotic fluid on gestational days 20 and 21. The profiles of increased SP-A levels in the amniotic fluid reflected those in the fetal lungs during gestation. Immunohistochemical examination with anti-rat SP-A antibody at 21 days of gestation showed that the immunoreactive staining of bronchiolar epithelial Clara cells and alveolar type II cells were weaker in the fetal lung sections from pregnant rats fed 5% protein diet than in those from pregnant rats fed 20% protein diet. It is concluded that protein malnutrition in pregnant rats affects the biosynthesis of SP-A in the fetal lungs, which may have important consequences for prematurity and decreased respiratory functions in the neonatal lungs at birth.

Ultrastructural changes of alveolar macrophages of protein-deficient rats.

Enhancement of phagocytosis of alveolar macrophages (AM) was examined by cytochemical and electron microscopic studies on macrophages from protein-deficient rats. The macrophages from rats fed on 5% casein diet had longer microvilli, more phagocytic vacuoles and more lysosomes with acid phosphatase activity than those from control rats. Many phagocytic vacuoles were seen close to the site of attachment of opsonized sheep red blood cells (SRBC) and were mainly located in the subplasmalemmal layer which was rich in microfilaments but contained few cytoplasmic organelles. After attachment, opsonized SRBC were engulfed through a hemispherical crater into the phagocytic vacuoles. The phagocytic vacuoles seemed to be formed by invagination of the cell surface because they had membrane ATPase activity continuous with that of the outer surface of the plasma membrane. In the cell, the vacuoles fused with the numerous preexisting lysosomes in the interior of the cell receiving the contents of the latter. The mechanism of enhancement of phagocytosis in protein-deficiency is discussed.

Vitamin E is an important factor in T cell differentiation in thymus of F344 rats.

The effect of vitamin E (dl-alpha-tocopheryl acetate) on T cell differentiation in thymus of F344 rats was examined in this study. The rats were divided into three groups: vitamin E-free, regular and high vitamin E groups and fed a diet containing various levels of vitamin E (0, 50, and 585 mg/kg diet) for 7 weeks. The number of thymocytes was significantly lower in the vitamin E-free group relative to the regular group. Although the proportions of both CD4+CD8- and CD4-CD8+ T cells in thymocytes were significantly greater in the high vitamin E group, the proportion of CD4+CD8- T cells inversely decreased in vitamin E-free group compared to that of the regular group. The ratio of CD4+CD8-/CD4-CD8+ T cells increased in the high vitamin E group (p < 0.01) and significantly decreased in the vitamin E-free group (p < 0.001) compared to that of the regular group. Although the marked changes of T cell subsets were not seen in peripheral blood lymphocytes (PBL), the ratio of CD4+CD8-/CD4-CD8+ T cells was significantly lower in the vitamin E-free group and significantly greater in the high vitamin E group compared to that of the regular group. Production of interleukin (IL) 2 by thymocytes following the stimulation with Con A for 48 h increased about threefold in the high vitamin E group compared to the regular group. Conversely, thymocytes from rats fed the vitamin E-free diet showed a significant decrease of IL2 production compared to that of the regular group. Prostaglandin E2 (PGE2) production from thymocytes was significantly lower in the high vitamin E group compared to that of the regular group, whereas thymocytes of rats fed the vitamin E-free diet showed a significant increase of PGE2 production compared to that of rats fed the regular diet. Furthermore, in vitro addition of indomethacin provided a restoration of IL2 production from thymocytes of rats fed the vitamin E-free diet to the level of rats fed the regular diet. These results suggest that vitamin E plays an important role in T cell differentiation in thymus, which may be related to the action of vitamin E as antioxidant.