Higher ratio of plasma nitric oxide to asymmetric dimethylarginine levels affects aerobic exercise training-induced reduction of arterial stiffness in middle-aged and older adults

Introduction

Regular aerobic exercise reverses aging-induced deterioration of arterial stiffness via an increased arterial nitric oxide (NO) production. Concurrently, asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthase, was decreased by aerobic exercise training. A recent study showed that the NOx/ADMA ratio reflects endothelial function and may be an index of the states of cardiovascular disease. However, whether changes in the NOx/ADMA ratio by aerobic exercise training are associated with a decrease in arterial stiffness in healthy middle-aged and older male and female adults remains unclear.

Purpose

This study aimed to clarify whether the relationship between plasma ADMA and NOx levels affected aerobic exercise training-induced reduction of arterial stiffness in middle-aged and older adults. Additionally, we examined whether the effect of AT on circulating ADMA levels differed according to sex.

Methods

Thirty-one healthy middle-aged and older male and female subjects (male = 13, female = 18, 66.4±1.3 years) participated in the study. The subjects were randomly divided into 2 groups: a training group (n=16 [male = 6 / female = 10], 64.8±2.0 years) and a control group (n=15 [male = 7 / female = 8], 68.1±1.6 years). Subjects in the training group performed the AT program, which consisted of cycling on a leg ergometer at 60–70% of peak oxygen uptake (V(·)O2peak)for 45 min/day, 3 days/week for 8 weeks. Before and after the 8-week aerobic exercise training intervention, V(·)O2peak, plasma ADMA levels and plasma NOx levels were measured in all subjects. Also, carotid β-stiffness as an index of arterial stiffness was determined with ultrasonography.

Results

Aerobic exercise training significantly increased V(·)O2peak (P<0.05) and decreased carotid b-stiffness (P<0.01). Moreover, plasma ADMA levels were significantly decreased, and plasma NOx levels and NOx/ADMA ratio were significantly increased by aerobic exercise training (P<0.01). Additionally, no sex differences in aerobic exercise training-induced changes in circulating ADMA and NOx levels, NOx/ADMA ratio, and carotid β-stiffness were observed. Furthermore, the aerobic exercise training-induced increase in circulating ADMA levels was negatively correlated with the increase in circulating NOx levels (r=−0.414, P<0.05), and aerobic exercise training induced increase in NOx/ADMA ratio was negatively correlated with the decrease in carotid β-stiffness (r=−0.514, P<0.01).

Conclusion

These results suggest that higher NOx/ADMA ratio affects aerobic exercise training-induced reduction of arterial stiffness, regardless of sex in middle-aged and older adults.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): This work was supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology of Japan

Time course of improvement in novel nitric oxide-regulated hormones in response to exercise training in middle-aged and older adults

Introduction

Cardiovascular disease risk augments with advance of age. The mechanism of the increased cardiovascular disease risk by aging is related to attenuation of arterial function via endothelium-derived relaxing factor, such as nitric oxide (NO). Recently, apelin and adropin have identified as NO-upregulated hormones, whereas augmented secretion of asymmetric dimethylarginine (ADMA) have identified as NO-downregulated hormones. However, the effects of exercise training-induced changes in NO-regulated hormones on the reduction of arterial stiffness via NO productions remain unclear.

Purpose

This study aimed to determine the time-dependent changes in NO-regulated hormones related to exercise-training effects of arterial stiffness via NO productions in healthy middle-aged and older adults.

Methods

Thirty-two Japanese healthy middle-aged and older subjects (67±1 years) were randomly divided into two groups: exercise intervention and sedentary controls. Subjects in the training group completed 8-week of aerobic exercise training (60–70% peak oxygen uptake [VO2peak] for 45 min, 3 days/week). We evaluated plasma nitrite/nitrate (NOx), apelin, and ADMA levels, serum apelin level and carotid-femoral pulse wave velocity (cfPWV) as an index of arterial stiffness, measured every 2 weeks for 8-week in the training group.

Results

cfPWV was gradually declined from baseline to 8-week and significantly decreased from baseline at weeks 6 (P<0.05) and 8 (P<0.01). Plasma NOx level was gradually elevated during exercise intervention and significantly increased from baseline at weeks 6 (P<0.05) and 8 (P<0.01). Interestingly, plasma apelin and serum adropin levels were gradually elevated during exercise intervention and significantly increased from baseline at weeks 4, 6 and 8 (each P<0.01). Additionally, plasma ADMA level was significantly decreased at 8-week intervention (P<0.01). Furthermore, the exercise training-induced increase in plasma NOx level was significantly correlated with the changes in circulating apelin (r=0.505, P<0.05), adropin (r=0.662, P<0.01), or ADMA (r=−0.483, P<0.05) levels before and after the 8-week. The exercise training-induced increase in plasma NOx level was significantly correlated with training-induced changes in circulating apelin (r=0.483, P<0.05) or adropin (r=0.556, P<0.05) before and after the 6-week.

Conclusions

These results suggest that the NO-upregulated hormones (apelin and adropin) were increased at the early stage of exercise training intervention and NO-downregulated hormone (ADMA) was decreased at the late stage of exercise training intervention, and these changes in NO-regulated hormones may be contributed to the reduction of arterial stiffness in the middle-aged and older adults.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

62 Time course of improvement in secretory unbalance of asymmetric dimethylarginine and nitric oxide productions in response to exercise training in middle-aged and older adults

Funding Acknowledgements

Supported by Grants-in-Aid for Scientific Research (#17H02182, #16K13059, M. Iemitsu; #18J01024, S. Fujie)

Introduction

Aging is well known to elevate risks of cardiovascular diseases. As a mechanism of these increased risks with aging, a reduction of nitric oxide (NO) production via augmented secretion of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthesis is related. Habitual aerobic exercise has shown to improve secretory unbalance of endothelium-derived regulating factors with aging, such as increase in NO and decrease in ADMA, resulting in the reduction of arterial stiffness. However, the time course of improvement in secretory unbalance of NO and ADMA productions in response to exercise training in middle-aged and older adults remains unclear.

Purpose

This study aimed to determine the time course of changes in plasma nitrite/nitrate (NOx) and ADMA levels related to exercise-training effects of arterial stiffness in healthy middle-aged and older adults.

Methods

Thirty-two Japanese healthy middle-aged and older subjects (67 ± 1 years) were randomly divided into two groups: exercise intervention and sedentary controls. Subjects in the training group completed 8-week of aerobic exercise training (60-70% peak oxygen uptake [VO2peak] for 45 min, 3 days/week). We evaluated plasma NOx and ADMA concentrations and carotid-femoral pulse wave velocity (cfPWV) as an index of arterial stiffness, measured every 2 weeks for 8-week in the training group.

Results

cfPWV was gradually declined from baseline to 8-week and significantly decreased from baseline at weeks 6 (P < 0.05) and 8 (P < 0.01). Plasma NOx level was gradually elevated during exercise intervention and significantly increased from baseline at weeks 6 (P < 0.05) and 8 (P < 0.01). Interestingly, plasma ADMA level was significantly decreased at 8-week intervention (P < 0.05). Furthermore, the exercise training-induced reduction in plasma ADMA level was negatively correlated with the change in plasma NOx level before and after the 8-week (r = -0.483, P < 0.05). The exercise training-induced change in plasma ADMA concentration was positively correlated with training-induced change in cfPWV before and after the 8-week (r = 0.633, P < 0.01). Additionally, there was a negative correlation between the changes in plasma NOx level and cfPWV before and after the 8-week (r = -0.642, P < 0.05).

Conclusions

These results suggest that habitual aerobic exercise can normalize the secretory unbalance of NO and ADMA productions in 6 to 8 weeks, and these balance normalizations may be contributed to the reduction of arterial stiffness in the middle-aged and older adults.

Effects of habitual aerobic exercise on the relationship between intramyocellular or extramyocellular lipid content and arterial stiffness

The accumulation of intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) is associated with arterial stiffness in middle-aged and older adults. Habitual aerobic exercise induces the improvement of arterial stiffness with reduction in fat accumulation. However, the relationship between aerobic exercise-induced changes in muscular lipids and arterial stiffness remains unclear. The purpose of this study was to investigate whether habitual aerobic exercise-induced changes in IMCL and EMCL content would lead to an improvement of arterial stiffness. First, in a cross-sectional study, we investigated whether cardiorespiratory fitness level affects the association between IMCL or EMCL content and arterial stiffness in 60 middle-aged and older subjects (61.0±1.3 years). Second, in an intervention study, we examined whether aerobic exercise training-induced changes in IMCL and EMCL content are associated with a reduction in arterial stiffness in 18 middle-aged and older subjects (67.0±1.7 years). In the cross-sectional study, IMCL content was negatively correlated with brachial-ankle pulse wave velocity (baPWV) (r=-0.47, P<0.05), whereas EMCL content was positively correlated with baPWV (r=0.48, P<0.05) in the low-fitness group, but was not correlated in the high-fitness group. Furthermore, 8-week aerobic exercise training in older adults increased IMCL content and reduced EMCL content. The training-induced change in baPWV was negatively correlated with training-induced changes in IMCL but was positively correlated with training-induced changes in EMCL. These findings suggest that aerobic exercise training-induced changes in IMCL and EMCL content may be related to a reduction in arterial stiffness in middle-aged and older adults.

Elevated pentraxin 3 level at the early stage of exercise training is associated with reduction of arterial stiffness in middle-aged and older adults

Regular exercise improves aging-induced deterioration of arterial stiffness, and is associated with elevated production of pentraxin 3 (PTX3) and anti-inflammatory as well as anti-atherosclerotic effects. However, the time-dependent effect of exercise training on arterial stiffness and PTX3 production remains unclear. The purpose of this study was to investigate the time course of the association between the effects of training on the circulating PTX3 level and arterial stiffness in middle-aged and older adults. Thirty-two healthy Japanese subjects (66.2±1.3 year) were randomly divided into two groups: training (exercise intervention) and sedentary controls. Subjects in the training group completed 8 weeks of aerobic exercise training (60-70% peak oxygen uptake (VO2peak) for 45 min, 3 days per week); during the training period, we evaluated plasma PTX3 concentration and carotid-femoral pulse wave velocity (cfPWV) every 2 wk. cfPWV gradually declined over the 8-week training period, and was significantly reduced after 6 and 8 week of exercise intervention (P<0.05). Plasma PTX3 level was significantly increased after 4 weeks of the intervention (P<0.05). In addition, the exercise training-induced reduction in cfPWV was negatively correlated with the percent change in plasma PTX3 level after 6 week (r=-0.54, P<0.05) and 8 weeks (r=-0.51, P<0.05) of the intervention, but not correlated at 4 weeks. Plasma PTX3 level was elevated at the early stage of the exercise training intervention, and was subsequently associated with training-induced alteration of arterial stiffness in middle-aged and older adults.

Adverse effects of coexistence of sarcopenia and metabolic syndrome in Japanese women

BACKGROUND/OBJECTIVES

Little information is available regarding the interactions of sarcopenia and metabolic syndrome (MetS) in the risks of these age-associated diseases in women. The present cross-sectional study was performed to investigate whether the coexistence of sarcopenia and MetS further increases the risks of lifestyle-related diseases in Japanese women.

SUBJECTS/METHODS

Healthy Japanese women (n=533) aged 30-84 participated in this study. MetS was defined as higher body mass index, fasting plasma glucose, systolic or diastolic blood pressure and blood lipid abnormalities. Appendicular muscle mass and bone mineral density (BMD) were measured using dual-energy X-ray absorptiometry. The criterion of low muscle mass and strength defined median skeletal muscle index (appendicular muscle mass/height², kg/m²) and handgrip strength.

RESULTS

Two-way ANCOVA with adjustment for age, body fat percentage and whole-body lean tissue mass indicated that sarcopenia and MetS interacted to produce a significant effect on HbA1c, systolic blood pressure, triglycerides and brachial-ankle pulse wave velocity in Japanese women. The systolic blood pressure, triglycerides and brachial-ankle pulse wave velocity were significantly higher in women with coexisting sarcopenia and MetS than in healthy controls or in those with sarcopenia or MetS alone. The HbA1c in the coexisting sarcopenia and MetS group was higher than in healthy controls and sarcopenia subjects.

CONCLUSIONS

The coexistence of sarcopenia and MetS further increases the risks of cardiovascular diseases, such as type 2 diabetes mellitus, hypertension, arterial stiffness and hyperlipidemia even adjustment of age and body composition in adult Japanese women.

Gallbladder aspiration for acute cholecystitis in average-surgical-risk patients

We conducted a retrospective case note review to assess whether or not gallbladder aspiration can be applied as a temporary measure for the treatment of acute cholecystitis in average-surgical-risk patients. Gallbladder aspiration was performed in 79 consecutive average-surgical-risk patients with acute cholecystitis, who had no indications of emergent surgery and who complained of severe colicky pain. Elective surgery became possible in 92% of patients by gallbladder aspiration. The percentage reached 97 when percutaneous cholecystostomy was added (four patients). Emergent surgery was needed in one patient suffering bile leakage following gallbladder aspiration. Colicky pain was controlled soon after the procedure in most cases. Neither major complications nor mortalities were observed in the following surgical therapies. It is suggested that gallbladder aspiration might be applied as a temporary measure for acute cholecystitis in average-surgical-risk patients, although early surgery should remain the primary choice of therapy in such patients.

Activation of WNT family expression and signaling in squamous cell carcinomas of the oral cavity

The WNT family activates an oncogenic signaling mediated through beta-catenin and is up-regulated in a variety of malignant neoplasms. The signaling translocates beta-catenin into the nucleus and stimulates carcinoma cells in the epithelial-mesenchymal transition (EMT). However, WNT expression and signaling in oral carcinomas have not been examined. The present study focused on unveiling the involvement of WNTs in oral carcinomas, and showed that carcinoma cells express 11 of 19 WNT family members by reverse-transcription/PCR. WNT-expressing carcinoma cells exhibited increased beta-catenin levels in the cytoplasmic pool and translocation to the nucleus. The activation state of signaling correlated with the expression of membrane-type 1 matrix metalloproteinase, which degrades territorial matrices in carcinoma invasion. Immunohistochemistry disclosed that WNT3 expression and nuclear localization of beta-catenin were predominant in carcinoma cells at the invasive front. These results suggest that enhanced WNT expression and signaling accelerate the progression of carcinomas via activating EMTs and local invasiveness.

The LIM-only protein, LMO4, and the LIM domain-binding protein, LDB1, expression in squamous cell carcinomas of the oral cavity

Carcinoma cells can lose their epithelial cell characteristics and dedifferentiate into a fibroblast-like cell during progression of a neoplasm. Aberrant expression of oligomeric transcriptional complexes contributes to progression of carcinomas. Although individual transcription factors initiating progression remain unknown, LIM-only protein (LMO) and LIM-domain binding protein (LDB) negatively regulate breast carcinoma cell differentiation. In this study, we investigated the expression of LMO4 and LDB in squamous cell carcinomas of the oral cavity. LMO4 mRNA was amplified in four of six carcinoma tissues and eight of 12 carcinoma cell lines, and LDB1 in three carcinoma tissues and 11 cell lines examined. Immunoprecipitation studies revealed that LMO4 and LDB1 interact with each other in the nuclear milieu of the carcinoma cells indicating the presence of an LMO4-LDB1-mediated transcription complex. Both LMO4 and LDB1 proteins were preferentially localised in the nuclei of carcinoma cells at the invasive front and the immunoreactivity was increased in less-differentiated carcinoma tissues (P<0.01). Carcinoma cells metastasised to the cervical lymph nodes with increased immunoreactivity compared to the primary site of neoplasm (P<0.05). These data suggest that the LMO4-LDB1 complexes may be involved in carcinoma progression possibly through dedifferentiation of squamous carcinoma cells of the oral cavity.

Correlation between the expression of methionine adenosyltransferase and the stages of human colorectal carcinoma

Methionine adenosyltransferase (MAT) catalyzes the synthesis of S-adenosylmethionine (AdoMet) from ATP and L-methionine. AdoMet is the major methyl donor in most transmethylation reactions in vivo, and it is also the propylamino donor in the biosynthesis of polyamines. In the present study, we assessed MAT activity in human colons with colorectal carcinoma and the values were compared with those of morphologically normal adjacent mucosa. Higher levels of MAT activity were observed in the colorectal carcinoma than in the normal colon. The ratio of MAT activity in tumor tissue versus normal tissue seemed to be correlated well will the stage of the colorectal tumor. Furthermore, immunoblot analysis showed that the high levels of MAT activity observed in colorectal carcinoma were due to the increased amounts of MAT protein. Immunohistochemical analysis revealed that MAT was most abundant in goblet cells, particularly in granules in the supranuclear area of these cells. In the colorectal carcinoma tissues, MAT was strongly stained in the cancerous cells and localized in granules in the supranuclear region. The results of this preliminary study suggest that determination of the relative ratio of MAT activity in both normal and tumor regions in human colorectal carcinoma could be a clinically useful tool for determining the stage of malignancy of colorectal carcinomas.

Circadian and photic regulation of MAP kinase by Ras- and protein phosphatase-dependent pathways in the chick pineal gland

Chick pineal mitogen-activated protein kinase (MAPK) exhibits circadian activation and light-dependent deactivation at nighttime. Here we report that, in the chick pineal gland, levels of active forms of MAPK, MEK, Raf-1 and Ras exhibited synchronous circadian rhythms with peaks during the subjective night, suggesting a sequential activation of components in the classical Ras-MAPK pathway in a circadian manner. In contrast, the light-dependent deactivation of MAPK was not accompanied by any change of MEK activity, but it was attributed to the light-dependent activation of protein phosphatase dephosphorylating MAPK. These results indicate that the photic and clock signals regulate MAPK activity via independent pathways, and suggest a pivotal role of MAPK in photic entrainment and maintenance of the circadian oscillation.

Circadian activation of bullfrog retinal mitogen-activated protein kinase associates with oscillator function

The vertebrate retina retains a circadian oscillator, and its oscillation is self-sustained with a period close to 24 h under constant environmental conditions. Here we show that bullfrog retinal mitogen-activated protein kinase (MAPK) exhibits an in vivo circadian rhythm in phosphorylation with a peak at night in a light/dark cycle. The phosphorylation rhythm of MAPK persists in constant darkness with a peak at subjective night, and this self-sustained rhythm is also observed in cultured retinas, indicating its close interaction with the retinal oscillator. The rhythmically phosphorylated MAPK is detected only in a discrete subset of amacrine cells despite ubiquitous distribution of MAPK throughout the retinal layers. Treatment of the cultured retinas with MAPK kinase (MEK) inhibitor PD98059 suppresses MAPK phosphorylation during the subjective night, and this pulse perturbation of MEK activity induces a significant phase delay (4-8 h) of the retinal circadian rhythm in MAPK and MEK phosphorylation. These observations strongly suggest that the site-specific and time-of-day-specific activation of MAPK contributes to the circadian time-keeping mechanism of the retinal clock system.

Role of circadian activation of mitogen-activated protein kinase in chick pineal clock oscillation

A circadian pacemaker generates a rhythm with a period of approximately 24 hr even in the absence of environmental time cues. Several photosensitive neuronal tissues such as the retina and pineal gland contain the autonomous circadian pacemaker together with the photic-input pathway responsible for entrainment of the pacemaker to the daily light/dark cycle. We show here that, in constant darkness, chick pineal mitogen-activated protein kinase (MAPK) exhibited an in vivo circadian rhythm in tyrosine phosphorylation and in enzymatic activity with a peak during subjective night. Phosphorylated and hence activated MAPK was rapidly dephosphorylated after light illumination during the nighttime when light induces a phase-shift of the pacemaker. The circadian rhythmicity in MAPK phosphorylation was also observed in the cultured pineal gland, and importantly, MAPK kinase inhibitor treatment during subjective night not only shifted the time-of-peak of MAPK phosphorylation but also induced a remarkable phase-delay of the circadian pacemaker. These results indicate an important role of MAPK for time keeping in circadian clock systems.

Doxorubicin preconditioning: a protection against rat hepatic ischemia-reperfusion injury

Doxorubicin produces clinically useful responses in a variety of human cancers. However, the toxicity of doxorubicin has limited its usefulness. This side effect is mainly due to the doxorubicin-mediated free radical formation. Administration of doxorubicin (10 mg/kg body weight) to rats intravenously induces heme oxygenase-1 (HO-1) in the liver. The levels of HO-1 protein were first detected at 6 hours and peaked at about 18 to 24 hours after the injection. It is known that HO-1 plays a protective role against the oxidative injury. Therefore, we have examined the protective effect of doxorubicin preconditioning against the hepatic ischemia-reperfusion injury. Partial hepatic ischemia was produced in the left and medium lobes for 45 minutes followed by 120 minutes reperfusion. When low doses of doxorubicin (1 mg/kg body weight) was intravenously administered to rats 2 days before the ischemia, the serum alanine transaminase (ALT) levels in the preconditioning rat were clearly improved compared with those in the rat without preconditioning. Under this situation, zinc-protoporphyrin IX, a specific inhibitor of HO-1, was injected subcutaneously to rats at 3 and 16 hours before the ischemia, the ALT levels were not improved by doxorubicin preconditioning. Histopathologic examination also supported these results. Although the HO-1 protein level was fairly low 2 days after the doxorubicin administration, significant amounts of HO-1 protein were detected. Our results indicated that the induction of HO-1 played a protective role against hepatic ischemia-reperfusion injury and that doxorubicin preconditioning is more clinically useful than other preconditioning methods.

Characterization of N-acylation of Go alpha purified from bovine retinas

Heterogeneous N-terminal acylation has been identified in several retinal proteins localized predominantly in the outer segments of the photoreceptor cells, but it is still unclear whether such a unique heteroacylation is determined by a photoreceptor cell-specific factor or not. Here, we characterized the N-terminal modification of bovine retinal Go alpha, which seems to be involved in the neural activities and is not detected in the photoreceptor outer segments. In the proteolytic fragments of immunoaffinity-purified retinal Go alpha, we found a single N-terminal peptide modified with myristate, and concluded that retinal Go alpha is purely myristoylated, just like brain Go alpha. This result indicates that the heteroacylation has a more restricted origin in the retina, and supports the idea that it is a photoreceptor cell-specific modification.

Cyst-like lesion of a developing tooth induced by mandibular fracture

A dentigerous cyst-like formation in the lower canine region caused by mandibular fracture in a 10-year-old boy is reported. His medical history revealed that he had been unconscious for about 2 weeks after traumatic head injuries sustained in a traffic accident, and a complicated mandibular fracture had been left untreated until his dentist diagnosed the lesion. Eleven months after trauma, a dentigerous cyst measuring 20 mm in diameter was found in the fracture area. The lesion was enucleated and the boy's postoperative recovery was uneventful. The mass completely enveloped the developing canine, and epithelial cells proliferated into the connective tissue. However, there was no distinct epithelial lining. Small round cell infiltrations and several vessels with thrombosis were noted in the cyst wall. The cause of cyst formation was considered to be infection of the canine tooth bud and the surrounding soft tissue.

[Combination therapy with 5'-DFUR, MMC and CDDP in patient with far advanced gastric cancer: report of a case]

A 48-year-old man was referred to our hospital for a Borrmann 3 type advanced gastric cancer. Endoscopic biopsy disclosed poorly differentiated adenocarcinoma. Ultrasonography and CT scan revealed left hydronephrosis. Endoscopic retrograde cholangiography detected a stenosis of common bile duct at the hepatic hilum due to lymph nodal metastasis, and laparoscopy revealed peritoneal dissemination. Because the tumor was diagnosed as not for curative resection, the patient was treated by 4 courses of combination therapy with 5'-DFUR, MMC and CDDP. No adverse effect of chemotherapy was observed. As a result, lymph nodal metastasis and peritoneal dissemination were reduced. Curative intent total gastrectomy was performed, together with pancreatico-splenectomy, left hemicolectomy, cholecystectomy, and extended lymph nodal dissection. The patient is well and alive with no sign of recurrence 2 years after operation.

Calcium-bound recoverin targets rhodopsin kinase to membranes to inhibit rhodopsin phosphorylation

In rod photoreceptor cells, Ca2+-bound recoverin associates with disk membranes and inhibits light-dependent phosphorylation of rhodopsin. However, the functional significance of Ca2+-induced membrane association of recoverin has not been fully evaluated. We found that Ca2+-bound recoverin forms a complex with rhodopsin kinase preferentially at the membrane surface. Addition of increasing amounts of membranes promoted the membrane association of recoverin, and remarkably suppressed rhodopsin kinase activity. It was concluded that the Ca2+-recoverin-rhodopsin kinase complex is stabilized by membrane association, leading to effective suppression of the kinase activity.

Role of heterogeneous N-terminal acylation of recoverin in rhodopsin phosphorylation

Recoverin, a new member of the EF-hand superfamily, plays a critical role in the light/dark adaptation of retinal rods by regulating rhodopsin phosphorylation in a Ca(2+)-dependent manner. Recoverin is composed of four isoforms, each of which is modified at its N terminus by myristate (C14:0) or its structurally related fatty acid (C12:0, C14:2, or C14:1). Although the N-fatty acylation is implicated in protein-membrane and protein-protein interactions, the functional difference among the recoverin isoforms and the significance of the heterogeneous acylation have not been defined. Here we separated the heterogeneous recoverin into three fractions, C14:0-recoverin, C14:1-recoverin, and a mixture of C14:2- and C12:0- (C14:2/C12:0-) recoverin to evaluate the individual properties. Recoverin in every fraction bound Ca2+ as assessed by fluorescence spectroscopy and inhibited the light-dependent rhodopsin phosphorylation in the same range of free Ca2+ concentration (0.3-0.8 microM). However, the magnitude of the inhibition at higher Ca2+ concentration was different among the isoforms and ranked in the same order of the hydrophobicity of the N-fatty acyl groups: C14:0 > C14:1 > C14:2/C12:0. These results indicate that the diverged hydrophobicity of the recoverin N terminus plays an important role in the interaction with the membranes and/or its target protein but not with Ca2+.

Genetic polymorphisms of the CST2 locus coding for cystatin SA

A new genetic polymorphism of cystatin SA has been identified in human submandibular-sublingual saliva by means of basic gel electrophoresis and immunoblotting with anti-cystatin S. Two proteins, SA1 and SA2, are given by two alleles of CST2, viz., CST2*1 and CST*2. Inheritance is controlled by two codominant alleles at an autosomal locus. This hypothesis is supported by studies of 16 families 32 children. Gene frequencies for CST2*1 and CST2*2 are 0.935 and 0.065, respectively (n = 341). Eighteen amino acids determined among 20 N-terminal residues of cystatin SA2 are identical with the sequence encoded by CST2. Three forms of cystatin S (mono-phosphorylated cystatin S, di-phosphorylated cystatin S, and non-phosphorylated cystatin S) are present in the 341 saliva samples tested.

Purification and characterization of three MEKA-like proteins in liver: association of a 94 kDa protein with beta gamma subunits of G-proteins

Retinal 32 kDa MEKA protein (rMEKA) exists in the photoreceptor cells and forms a complex with beta gamma subunit of transducin. Bovine liver contained three MEKA-like proteins (94 kDa, 35 kDa-a, 35 kDa-b) which reacted with a rMEKA antibody. Each protein was purified as a single band on a SDS-PAGE and used for a reconstitution experiment with alpha and beta gamma subunits of cerebral G-proteins (Go/i). The 94 kDa protein inhibited GTP-binding ability of G alpha by forming a complex with beta gamma subunit.

Biochemical and clinical factors influencing oral malodor in periodontal patients

The amounts of volatile sulfur compounds (VSC) and methyl mercaptan/hydrogen sulfide ratio in mouth air from patients with periodontal involvement were 8 times greater than those of control subjects. Our studies demonstrated that, in patients with periodontal disease: 1) the concentration of disulfide, which is converted to VSC, increased in proportion to the total pocket depth; 2) 60% of the VSC was produced from the tongue surface; 3) the amount of tongue coating was 4 times greater than in control subjects; and 4) VSC production and the methyl mercaptan/hydrogen sulfide ratio of the tongue coating were increased. 2-Ketobutyrate, which is a byproduct of the metabolism of methionine to methyl mercaptan, was higher in the saliva of patients with periodontal disease. This implies that metabolism of methionine to methyl mercaptan increases in the oral cavity of patients with periodontal pockets. Since free L-methionine, rather than protein, is the main source for methyl mercaptan, we estimated the methionine supply from the gingival fluid into the oral cavity of patients with periodontal involvement. The results showed that the ratio of methionine to whole free amino acids was significantly higher than that of cysteine. Our studies suggest that not only microorganisms, but also the tongue coating and gingival fluid are factors which enhance VSC production in patients with periodontal disease.

Volatile sulfur compounds in mouth air from clinically healthy subjects and patients with periodontal disease

Volatile sulfur compounds (VSC) in mouth air were estimated by gas chromatography. The amount of VSC and the methyl mercaptan/hydrogen sulfide ratio were significantly increased in patients with periodontal disease. These two parameters also increased in proportion to the bleeding index and probing depth. A study was also done on the effect of removal of tongue coating on VSC concentrations in mouth air from patients with periodontal involvement. VSC and the methyl mercaptan/hydrogen sulfide ratio were reduced to 49% and 35%, respectively, by removal of the tongue coating. The average amount of tongue coating removed from patients with periodontal disease was significantly higher than from controls (90.1 mg vs. 14.6 mg, p less than 0.01). Estimated production of VSC from tongue coating was 4 times higher than the control value, and the methyl mercaptan/hydrogen sulfide ratio was also markedly increased. However, a saliva putrefaction study suggested that saliva does not contribute to the elevated ratio of methyl mercaptan in mouth air. These results strongly suggest that, in addition to periodontal pockets, tongue coating has an important role in VSC production, in particular leading to an elevated concentration of methyl mercaptan, which is more pathogenic than hydrogen sulfide.

Effects of a two-phase oil-water mouthwash on halitosis

Many oral microorganisms possess hydrophobic outer surfaces. A two-phase, oil-water mouthwash has, therefore, recently been developed to remove such oral microorganisms. The oil phase consists of olive oil and other essential oils. The aqueous phase includes cetylpyridinium chloride, which is a disinfectant that promotes the adhesion of microorganisms to oil droplets. This study determined the effects of this mouthwash on the production of volatile sulfide in vivo and in vitro. Neither rinsing with water nor brushing teeth decreased the concentration of sulfide in mouth air at 3.5 h after treatment. A reduction of only 30% of sulfide was observed when a commercial mouthwash was used. However, this study demonstrated that use of the two-phase mouthwash led to approximately 80% reduction of sulfide. Furthermore, volatile sulfide and 2-ketobutyrate productions from methionine in a saliva putrefaction system were completely inhibited by the two-phase mouthwash; and consumption of methionine was decreased by 65 percent. It is concluded that the two-phase mouthwash strongly inhibits the production of volatile sulfide.

Characterization of two members (CST4 and CST5) of the cystatin gene family and molecular evolution of cystatin genes

Two members (CST4 and CST5) of the cystatin gene family have been characterized partially by DNA analysis. The CST4 clone contained the gene coding for the precursor form(141 amino acids) of cystatin S, and its exon-intron organization is the same as that of other members (the cystatin SN gene at the CST1 locus, the cystatin SA gene at the CST2 locus, the cystatin C gene at the CST3 locus and a cystatin pseudogene at the CSTP1 locus). The second cystatin pseudogene was elucidated in the clone, CST5, and it was assigned to the CSTP2 locus. Alignment of DNA sequences of cystatin genes with other genes suggested that the genes for cystatins, kininogens, and Bowman-Birk type inhibitors have evolved from an ancient ribonuclease-like gene.

Identification of full-sized forms of salivary (S-type) cystatins (cystatin SN, cystatin SA, cystatin S, and two phosphorylated forms of cystatin S) in human whole saliva and determination of phosphorylation sites of cystatin S

Our recent work on the gene structures for human salivary (S-type) cystatins [Saitoh, E. et al. (1987) Gene 61, 329-338] has suggested that the structures of cystatins which we determined previously at the protein level lack N-terminal peptide portions of the full-sized intact forms. In the present study, attempts were made to isolate full-sized S-type cystatins by introducing methanol fractionation into the purification steps to suppress the enzymatic activity present in saliva. Full-sized cystatin SN and two phosphorylated forms of full-sized cystatin S were thus isolated. Analysis of one fraction indicated that this was a mixture of full-sized cystatin SA and non-phosphorylated cystatin S. The phosphorylation sites of cystatin S were determined to be Ser-Ser-Ser1(P)-Lys-Glu-Glu- for monophosphorylated cystatin S and Ser1(P)-Ser-Ser3(P)-Lys-Glu-Glu- for diphosphorylated cystatin S. Immunoblotting analysis with anti-cystatin S antiserum revealed that tears and seminal plasma also contained S-type cystatins, but diphosphorylated cystatin S was detected neither in tears nor in seminal plasma and no cystatin SN was found in seminal plasma. These data indicate that S-type cystatins are secreted into the oral cavity without significant degradation in salivary glands or ducts and that they are expressed tissue specifically.

Cystatins of family II are harboring two domains which retain inhibitory activities against the proteinases

Two cyclic peptides, Ac-CTKSQPNLDTC-NH2 (SA-LOOP1) and Ac-CSFQIYEVPWE DRMSLVNSRC-NH2 (SA-LOOP2) were prepared. These sequences are respectively found in the second and third exons of cystatin SA and are well conserved among the cystatins of family II. In addition, these sequences are extremely homologous to the inhibitory regions of several serine-proteinase inhibitors. The peptides were assayed for their inhibiting properties towards serine- and cysteine-proteinases. SA-LOOP1 inhibited porcine pancreatic trypsin (Ki = 370 microM), but did not inhibit cysteine-proteinases. SA-LOOP2 inhibited not only porcine pancreatic alpha-chymotrypsin (Ki = 23 microM) but also papain (Ki = 24 microM) and ficin (Ki = 52 microM). These data indicate that the exon-intron organization of the cystatin genes coinside with the structural and/or functional domains of the protein, and may have significant implications for understanding the active sites of cystatins.

The human cystatin C gene (CST3) is a member of the cystatin gene family which is localized on chromosome 20

The fourth gene from the human cystatin gene family of salivary-type cysteine-proteinase inhibitors has been isolated and partially characterized by DNA analysis. The gene, which we name CST3, codes for human cystatin C, and has the same organization as the CST1 gene for cystatin SN and the CST2 gene for cystatin SA. Southern analysis of EcoR I digested DNAs from 32 independent somatic cell hybrid clones hybridized to a probe from CST1 demonstrated that all members of the cystatin gene family segregate with human chromosome 20. These results indicate that the genes for salivary-type cystatins and cystatin C are members of a multigene family--the cystatin gene family.

'Salivary peptide P-C' of human pancreatic B-cells shares only partly immunoreactivity with salivary peptide P-C indicating a new B-cell protein which is different from insulin

Salivary peptide P-C like immunoreactivity, originally isolated from human whole saliva has later been found in the human pancreatic B-cells. In the present work an indirect immunofluorescence technique using monoclonal antibodies against isolated salivary peptide P-C was applied to Bouin fixed pancreas and parotid glands to study the possible identity of the two substances. Positive P-C immunofluorescence was found in the serous cells of parotid glands but not in pancreatic B-cells, suggesting that pancreatic P-C substance is not salivary peptide P-C itself, but a substance sharing the common antigenic site with salivary peptide P-C. To examine this, an indirect immunofluorescence technique using polyclonal P-C antisera pre-absorbed with six kinds of synthetic fragments (1-22, 23-44, 23-29, 30-44, 30-38 and 38-44) of salivary peptide P-C was applied to the human pancreas. The result showed that pancreatic P-C substance was a substance which shares the common antigenic site with the 38-44 amino acid residue of salivary peptide P-C. Western blot analysis using extracts of human pancreata further showed that pancreatic P-C substance is not a precursor of insulin but a protein with molecular weight of 11,500 dalton, indicating the presence of a new protein in the insulin secretory granules of human pancreatic B-cells.

Cystatin superfamily. Evidence that family II cystatin genes are evolutionarily related to family III cystatin genes

Human saliva contains at least three molecular species of cystatin S-type cysteine proteinase inhibitor (cystatin S, cystatin SN and cystatin SA), which have similar but distinct amino-acid sequences. The nucleotide sequences of the CST 1 gene for cystatin SN and the CST 2 gene for cystatin SA are highly homologous to each other and to the corresponding regions of the cDNA for cystatin C and the EcoRI-PstI fragment from the cystatin C gene. Three cystatin-like domains in the kininogen gene and the salivary cystatin genes share the same gene organizations. These data demonstrate that family II cystatin genes are evolutionarily related to family III cystatin genes.

Characterization and amino acid sequence of a new acidic cysteine proteinase inhibitor (cystatin SA) structurally closely related to cystatin S, from human whole saliva

A cysteine proteinase inhibitor (designated as cystatin SA) was isolated from human whole saliva by procedures including chromatography on DE 32 and DEAE-Sepharose CL-6B. The amino acid sequence determined by conventional methods showed sequence homology of 90 and 87% as compared with the sequences of cystatin S and cystatin SN, respectively, both of which are salivary inhibitors characterized previously. The new inhibitor consisted of 117 residues and had a pI value of 4.3. Cystatin SA inhibited ficin and papain more strongly than cystatin S or cystatin SN did. It also exhibited inhibitory activity toward dipeptidyl peptidase I but the activity was much weaker than those toward ficin and papain.