Aging attenuates the association of central obesity with the accumulation of metabolic risk factors when assessed using the waist circumference measured at the umbilical level (the Japanese standard method).

OBJECTIVE: The objective of this study was to clarify the generation and gender differences in the association between central obesity and the accumulation of metabolic risk factors (RFs) in the Japanese population. MATERIAL AND METHODS: A total of 12 389 subjects (age: 18-80 years) without receiving medication for diabetes, dyslipidemia or hypertension were enrolled in this study and divided according to age and gender. In each group, we performed analyses as follows: (1) a receiver operating characteristic (ROC) analysis to evaluate the utility of the waist circumference (WC) for detecting subjects with multiple RFs of metabolic syndrome (MS); (2) a cross-sectional study to examine the relationship between the WC and the odds ratio (OR) for detecting those subjects and (3) a longitudinal study to examine how longitudinal changes (Δ) in WC over a 1-year period affected the values of each metabolic RF. RESULTS: With age, the WC cutoff values yielding the maximum Youden index for detecting subjects with multiple RFs increased only in women, and the areas under the curves of the ROC analysis of WC for detecting those subjects decreased in both genders. The positive correlation between the WC and the OR for detecting subjects with multiple RFs became weaker with age, especially in women. In the longitudinal study, the significant correlation between ΔWC and Δ each metabolic RF, except for hypertension, and between ΔWC and Δ the number of RFs became weaker with age in women, whereas the significant correlation between ΔWC and Δ the number of RFs was not affected with age in men. In women aged 60 years, none of the changes in each metabolic RF were significantly associated with ΔWC. CONCLUSIONS: Aging attenuates the association of central obesity with the accumulation of metabolic RFs, especially in women.

Expression of vascular endothelial growth factor C is a prognostic indicator in esophageal cancer.

BACKGROUND/AIMS: Vascular endothelial growth factor plays an important role in angiogenesis and vascular endothelial growth factor-C is concerned with lymphangiogenesis. METHODOLOGY: The present study employed immunostaining to investigate the relationship between expression of these factors and clinicopathologic findings in 100 patients with esophageal cancer. RESULTS: Fifty-six of the 100 tumors (56%) showed expressed vascular endothelial growth factor and 43 tumors (43%) expressed of vascular endothelial growth factor-C. Expression of the latter was correlated with the depth of tumor invasion (p=0.0095), lymphatic invasion (p=0.0065), lymph node metastasis (p=0.0l34). The prognosis was significantly worse for patients with tumors positive for vascular endothelial growth factor-C than for those with negative tumors (p=0.036). In contrast, expression of vascular endothelial growth factor was not correlated with the prognosis. Microvessel density was significantly higher in tumors expressing vascular endothelial growth factor-C compared with negative tumors (p=0.0014). Stepwise multivariate analysis with Cox's proportional hazards model identified gender (p=0.0420), age (p=0.0192), vascular endothelial growth factor-C expression (p=0.0286), and lymphatic invasion (p=0.0030) as prognostic determinants. CONCLUSIONS: Expression of vascular endothelial growth factor-C is related to lymphatic invasion and is a prognostic indicator for esophageal cancer.

Matrix metalloproteinase-7 and matrix metalloproteinase-9 are associated with unfavourable prognosis in superficial oesophageal cancer.

If oesophageal carcinoma is detected in the superficial stage, the prognosis is better than for advanced oesophageal carcinoma. But the factors which predict the prognosis and treatment policy remain unclear. Matrix metalloproteinase-7 (MMP-7) and matrix metalloproteinase-9 (MMP-9) have been reported to have close associations with tumour invasion and metastasis. In this study, we retrospectively studied the relations between MMP-7 and MMP-9 expression in immunohistochemistry, clinicopathologic factors, and prognosis in 55 superficial oesophageal carcinomas. MMP-7 and MMP-9 expression occurred in 23.6% and 47.3% of the patients, respectively. MMP-7 expression was significantly correlated with the presence of nodal metastasis (P=0.004). MMP-9 expression was significantly correlated with the depth of tumour invasion (P=0.004), lymphatic permeation (P=0.001), nodal metastasis (P=0.049), and pathologic differentiation grade (P=0.003). By the log-rank test, MMP-7 expression and MMP-9 expression on the invasive front were related to the prognosis. In multivariate analysis, MMP-9 expression on the invasive front was an independent prognostic indicator. The combined expression of MMP-7 and MMP-9 may be a good marker for the degree of malignancy of oesophageal cancer and for the presence of lymphatic metastasis.

A retrospective study of ocular toxocariasis in Japan: correlation with antibody prevalence and ophthalmological findings of patients with uveitis.

To classify the clinical characteristic of ocular toxocariasis in Japan, the prevalence of antibodies to Toxocara antigens was examined in patients with uveitis of unknown aetiology. From 1982 to 1993, serum specimens of 383 cases and intraocular fluid samples of 22 cases were serologically screened for Toxocara infection with five immunodiagnostic tests. Fifty-five sera and 11 intravitreous fluid samples were estimated to have significantly high antibody levels against larval excretory-secretory (ES) antigens of T. canis. Eight cases were positive in both serum and vitreous fluid, and three were positive only in the vitreous fluid. Among the 58 antibody positive samples, 20 cases were omitted due to a lack of detailed description of ocular findings. The remaining 38 cases are described in this study. Of these 38 cases, 34 (89%) were older than 20 years of age. Ocular lesions were located in the posterior fundus in 11 cases, in the peripheral fundus in 18 cases, and in both areas in seven cases. Of the eight cases in which papillary oedema or redness was observed, chorioretinal lesions were also present in seven of them. Tractional retinal detachment was present in five cases. These observations suggest that ocular toxocariasis in Japan has a different clinical profile compared with those in the other countries, and indicate a need for revised classification of ocular toxocariasis.

Uterine circulatory dysfunction induced by whole-body vibration and its endocrine pathogenesis in the pregnant rat.

Effects of whole-body vibration on normal pregnancy were studied in the rat. Uterine blood flow and five endocrine functions corticosterone (CS), estradiol (E2), progesterone (P), prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) concentration were measured in rats exposed to whole-body vibration with an acceleration of 10 m.s-2 at a frequency of 8 Hz. While no change in uterine blood flow was observed in control rats, uterine blood flow was significantly decreased 75 and 90 min after exposure to vibration. The uterine blood flow at 15 and 30 min was increased by pretreatment with intraperitoneal injections of angiotensin II (AII). In contrast, in AII pretreated rats exposed to the vibration, uterine blood flow was significantly reduced 90 min after exposure. The CS concentration was increased by vibration independently of the pretreatment with AII. Neither E2 nor PGF2 alpha concentration were changed by the vibration with or without AII administration. The P and PGE2 concentrations were both decreased by vibration in the absence of AII, while the decrease in PGE2 induced by the vibration was also found in AII-treated rats. The present results indicated that the pregnant rats subjected to whole-body vibration responded with changes in uterine and ovarian function. The observed decrease in uterine blood flow may have been the result of reduced PGE2 concentration resulting from an indirect effect of vibration.

Change in digital blood flow with simultaneous reduction in plasma endothelin induced by hand-arm vibration.

Involvement of endothelium-derived relaxing factor (EDRF) or endothelium-derived constricting factor (EDCF) has been proposed as the pathophysiologic mechanism of vibration-induced white finger (VWF). Recent evidence that endothelin is a potent vasoconstrictor peptide indicates that it may play a role in vasoregulation during vibration exposure through the local actions of EDRF or EDCF. Therefore, we examined the effects of grasping (50 N) and hand-arm vibration (50 m/s2 rms, 120 Hz, x-axis) on digital blood flow (DBF) and on the level of plasma endothelin in seven healthy male office workers. Grasping decreased DBF without affecting endothelin, and vibration increased DBF with a simultaneous reduction in endothelin. The grasping-induced decrease in DBF seemed to be due to mechanical compression of the vessels. The negative correlation between DBF and endothelin during vibration exposure suggests that a reduction in release of endothelin from smooth muscle into the vessel cavity during vibration leads to vasodilatation, possibly attributable to the local axon reflex.

Pathophysiological significance of plasma endothelin in peripheral circulatory disturbances.

Endothelin (ET) is produced in blood vessels and is a novel potent vasoconstrictor. Although the presence of immunoreactive ET in the circulating blood suggests that ET plays an important role in the regulation of systemic and/or local hemodynamics, the role of circulating ET has not been ascertained using human populations. We examined the values of the ET level and peripheral blood flow, including other biochemical and physiological factors, in 108 healthy adults who participated in annual health examinations of Japanese adults living in a rural community in 1992 and 1993. A small change in ET after the passage of one year showed good reproducibility of the value. ET was positively correlated with diastolic blood pressure (BP) and negatively with finger skin blood flow in healthy adults. Multiple regression analysis demonstreted that the positive relationship between ET and diastolic BP was independent of other health indicators. A detailed examination using optical spectroscopy for elderly institutionalized subjects without any trouble in the activity of daily living revealed a negative correlation of ET with saturated oxygen in blood, tissue hemoglobin volume and local blood flow and a positive one with the local oxygen extraction fraction. The present study indicated that increased ET in the elderly subjects was associated with hypoxia not only in the local finger skin region, but also possibly in the arterial tissue, suggesting that ET is involved in atherosclerosis. The negative correlation between ET and finger skin blood flow seen in the healthy adults may be induced by hypoxia. Although we recognized a positive correlation between ET and BP, the increase in ET seemed to be an outcome of elevation in BP rather than a cause of hypertension.

[Endocrine mechanism of placental circulatory disturbances induced by microwave in pregnant rats].

Effects of microwaves on fetus and female genital organs remain to be elucidated. To demonstrate the placental circulatory disturbances induced by microwaves and to clarify the endocrine pathogenesis, placental blood flow and five endocrine indicators, i.e., corticosterone (CS), estradiol (E2), progesterone (P), prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) were measured in rats exposed to whole-body microwaves with an intensity of 10 mW/cm2 at a frequency of 2,450 MHz. The placental blood flow at 45-90 min after exposure was significantly decreased in the rats exposed to the microwaves. Placental blood flow at 15 and 30 min was increased by pretreatment with intraperitoneal administration of angiotensin II (AII). In contrast, no significant change in placental blood flow was recognized in the AII pretreated rats exposed to the microwaves. An increase in CS and a decrease in E2 were induced by the microwave exposure independent of pretreatment with AII. P was increased by microwave exposure in the rats without pretreatment with AII. PGE2 was not changed by the microwave exposure in the case of either nonpretreatment or pretreatment with AII. PGF2 alpha was increased by the microwave exposure in the rats without pretreatment with AII. The present results indicate that excessive exposure to whole-body microwave disorders pregnancy in terms of placental circulatory dysfunction. The data suggest the involvement of endocrine mechanisms in the decrease in placental blood flow which is induced via a detrimental effect of microwaves on PGF2 alpha and on pituitary functions such as general emotional stress.

Involvement of endothelin in peripheral circulatory change induced by hand-arm vibration.

Physiologic mechanisms involving local vasoregulating factor, endothelium-derived relaxing factor (EDRF) and endothelium-derived constricting factors (EDCF) have been postulated to play a role in VWF. Recent evidence that endothelin is a potent vasoconstrictor peptide indicates that it may play a role in vasoregulation during vibration exposure through the local actions of EDRF or EDCF. Therefore, we examined the effects of grasping (50 N) and hand-arm vibration with an unweighted acceleration of 50 m/s2 rms at a frequency of 120 Hz in the direction of X-axis on digital blood flow (DBF) and on the level of plasma endothelin in 7 healthy male office workers. DBF was measured by an apparatus based on the thermal diffusion method where the thermal diffusion flow probe was incorporated in the Peltier's stack. In the grasping test, DBF decreased by about 40% from resting level within 1 minute after the grasping was begun, and was maintained at almost the same level during grasping, but increased immediately after cessation of grasping. In the vibration exposure test, initial decrease in DBF due to grasping was the same as that observed in the grasping test, but DBF gradually increased when exposure to vibration was performed simultaneously. No significant change in plasma endothelin level was induced by grasping. Endothelin was significantly lower after exposure to vibration than at rest and after grasping. The grasping-induced decrease in DBF seemed to be due to mechanical compression of the vessels. The negative correlation between DBF and endothelin during vibration exposure suggests that a reduction in release of endothelin from smooth muscle into the vessel cavity during vibration leads to vasodilatation, possibly attributable to the local axon reflex.

[Effects of vibration on uterine circulation in pregnant rats].

With the recent remarkable development of transportation facilities, pregnant women are frequently exposed to mechanical vibration. To experimentally demonstrate that vibration disorders normal pregnancy, uterine blood flow (UBF) and the several kinds of endocrine indicators were examined in pregnant rats exposed to vibration (10m/s2, 8Hz, 90 min). The exposure to vibration decreased UBF in the rats significantly. The UBF of the rats pretreated with peritoneal administration of angiotensin II (AII) was increased when they were not exposed to vibration. In contrast to this, in AII pretreated rats simultaneously exposed to vibration, a significant decrease in the UBF was recognized. Vibration decreased the plasma level of progesterone (PRO), but pretreatment with AII induced no difference in PRO in vibration-exposed and unexposed rats. The level of prostaglandin E2 (PGE2) was decreased in rats exposed to vibration, but not in control rats. Pretreatment with AII still decreased PGE2 in rats exposed to vibration. These results indicate that vibration may play an important role in the development of abnormal pregnancy through uterine circulatory and ovarian dysfunctions. It seems that a decrease in UBF is induced primarily via an inhibitory effect of vibration on PGE2, and secondarily via a direct action on the uterus.

Changes of cerebral vasoactive intestinal polypeptide- and somatostatin-like immunoreactivity induced by noise and whole-body vibration in the rat.

To clarify the role of vasoactive intestinal polypeptide (VIP) and somatostatin, somatotropin-release inhibiting factor, (SRIF) neurons in the response to organisms to noise or whole-body vibration stress, VIP- and SRIF-like immunoreactivity were determined in various regions of the rat brain following exposure for 90 min to noise (broad band, 102 dB) or whole-body vibration (20 Hz, 4.0 g). Both noise and whole-body vibration significantly increased VIP-like immunoreactivity in the amygdala. A significant reduction of VIP-like immunoreactivity in the hippocampus was induced only by whole-body vibration. On the other hand, SRIF-like immunoreactivity was decreased significantly in the hypothalamus and increased significantly in the amygdala by noise and whole-body vibration, respectively. The present findings would seem to indicate that the amygdalofugal VIP neural system is involved in regulating hypothalamic and pituitary hormone secretions in non-specific reactions to stress. Responses of hippocampal VIP and the amygdalofugal SRIF to whole-body vibration stress are assumed to be activated as specific reactions to the stress.

Field evaluation of an insect growth regulator, pyriproxyfen, against Anopheles punctulatus on north Guadalcanal, Solomon Islands.

Five pools containing immature stages of Anopheles punctulatus were treated with pyriproxyfen at 4 different dosages. Inhibition of adult emergence was observed in pupae collected from the test pools and/or those obtained by rearing of the 4th instar larvae. Adult emergence was inhibited completely for 2 months at a dosage of 0.1 ppm, for one month at 0.05 ppm and 0.01 ppm, and for 20 days at 0.02 ppm. Death of test insects were observed at the pupal stage and at adult emergence. The mortality rate at adult emergence increased with the duration of larval rearing and with the elapse of time after application.

Autogenous and anautogenous mosquitoes: a mathematical analysis of reproductive strategies.

A mathematical model is presented to compare the relative advantage of an anautogenous mosquito population (in which females blood feed throughout life) with an obligate autogenous population (in which females do not feed on blood for the first oviposition). The advantage is measured by the intrinsic rate of natural increase. Autogeny was more advantageous than anautogeny when host searching time (ts), the ratio of the fecundity of the first autogenous to anautogenous oviposition (p), the fecundity in one anautogenous oviposition (n), or the instantaneous death rate of the adult population (D) was large, or when the preimaginal period (xo), the instantaneous death rate during the preimaginal period (D'), or survival during blood feeding (s) was low. The parameters most sensitive to the advantage of autogeny were ts, p, and s. The value of n was insensitive, and xo, D, and D' were intermediately sensitive to autogeny. Conditions when autogeny was advantageous were equivalent to conditions conducive to high autogeny rates in facultatively autogenous species, which alter the expression of autogeny depending upon environmental stimuli. Data on several facultatively autogenous species are discussed qualitatively and quantitatively to demonstrate the utility of our model in considering the evolution of autogeny and the autogeny rate.

Scale pattern variations of Aedes aegypti in Chiang Mai, northern Thailand.

Abdominal tergal scale pattern variations of Aedes aegypti were studied in Chiang Mai, northern Thailand for specimens reared from eggs laid in ovitraps set monthly both indoors and outdoors in urban and rural areas. The populations predominantly consisted of the dark type form, regardless of macrohabitats (urban vs. rural), microhabitats (indoor vs. outdoor) or seasons (dry vs. rainy). Among 6,003 specimens, no individuals had pale-scales continuing from the tergal base to its apex on the third tergum and posteriorly.

Angiostrongylus cantonensis infection in Ampullarius canaliculatus (Lamarck) in Kyushu, Japan.

Ampullarius canaliculatus is a large fresh-water snail of which the original habitat is said to be Argentina. Recently, the snail which grew wild has propagated in various parts of Japan, and is causing damage to aquatic plants by feeding on them. The present study was performed to find out whether the snail can be a suitable intermediate host for Angiostrongylus cantonensis. Natural infection with A. cantonensis was confirmed in the snails collected from 5 different places in 4 hamlets in Okinawa and in those from Ishigaki Island. All snails experimentally infected with first-stage larvae of the parasite showed second-stage and third-stage larvae developing at the time of examination later on. Thus, A. canaliculatus is a suitable intermediate host for A. cantonensis, and, if eaten raw, it can be a potential source of human infection with eosinophilic meningoencephalitis in the endemic areas.

Laboratory bionomics of Tripteroides aranoides.

Tripteroides aranoides was colonized in the laboratory. Total duration of the immature stages was ca. 3 weeks at 28 degrees C, L:D = 15.5:8.5 with an ample food supply. Retardation of 4th instar development was observed in larvae fed on insufficient food. Females were autogenous for the first clutch of eggs and required a blood meal for maturation of the second clutch. Mating was initiated in flight and copulation occurred on the cage wall. Gravid females hovered in small oblique loops above water in bamboo cups, whereupon a white egg appeared at the abdominal tip, which was propelled by the swing of the abdomen towards water surface. The females propelled eggs in the same manner into small apertures (11 x 4 mm) bored in bamboo.

Seasonal variation in the microfilarial skin density of Onchocerca volvulus and in the biting activity of Simulium spp. in Guatemala.

The density of Onchocerca volvulus microfilariae in the skin of 11 carriers was examined by carrying out a monthly examination in a single endemic area of Guatemalan onchocerciasis. The results obtained suggested the possibility of a seasonal variation in the microfilarial skin density. Almost all of the volunteers participating had shown a peak concentration of microfilariae in September, followed by August or October. The highest biting densities of Simulium ochraceum, the principal vector of onchocerciasis in Guatemala, occurred from September to the following January. It thus appears that the seasonal variation in the microfilarial density may correspond, to some extent, with the biting activity of the vector, S. ochraceum and/or with climatic changes in the area.