Driver exposure to particulate matter in Bangkok.

The aims of this study were to determine the particulate matter with aerodynamic diameters > or = 2.5 microm (PM2.5) and 2.5-10 microm (PM10-2.5) exposure levels of drivers and to analyze the proportion of elemental carbon (EC) and organic carbon (OC) in PM2.5 in Bangkok, Thailand. Four bus routes were selected. Measurements were conducted over 10 days in August (rainy season) 2008 and 8 days in January (dry season) 2009. The mean PM2.5 exposure level of the Tuk-tuk drivers was 86 microg/m3 in August and 198 microg/m3 in January. The mean for the non-air-conditioned bus drivers was 63 microg/m3 in August and 125 microg/m3 in January. The PM2.5 and PM10-2.5 exposure levels of the drivers in January were approximately twice as high as those in August. The proportion of total carbon (TC) in PM2.5 to the PM2.5 level in August (0.97 +/- 0.28 microg/m3) was higher than in January (0.65 +/- 0.13 microg/m3). The proportion of OC in the TC of the PM2.5 in August (0.51 +/- 0.08 microg/m3) was similar to that in January (0.65 +/- 0.07 microg/m3). The TC exposure by PM25 in January (81 +/- 30 microg/m3) remained higher than in August (56-21 microg/m3). The mean level of OC in the PM2.5 was 29 +/- 13 microg/m3 in August and 50 +/- 24 microg/m3 in January. In conclusion, the PM exposure level in Bangkok drivers was higher than that in the general environment, which was already high, and it varied with the seasons and vehicle type. This study also demonstrated that the major component of the PM was carbon, likely derived from vehicles.

Blood lead and erythrocyte protoporphyrin levels in association with smoking and personal hygienic behaviour among lead exposed workers.

AIMS: To investigate the effects of smoking and personal hygienic behaviour on blood lead (BPb) and free erythrocyte protoporphyrin levels (FEP) in lead exposed workers. METHODS: Subjects were 105 lead exposed male workers in a battery recycling plant during the years 2000-03. BPb and FEP were measured as part of the ongoing occupational surveillance. Each worker completed a questionnaire for assessment of smoking and four measures of personal hygienic behaviour (glove and mask use, hand and face washing before meals during working hours). RESULTS: Statistically significant decreases in mean BPb and FEP occurred during the three years. The proportion of BPb reduction in the non-smoking workers was significantly higher (mean 24.3%) than in the smoking workers (15.3%). When the workers were classified into three groups (excellent, good, and poor) based on the four personal hygienic behavioural indicators, the greatest decreases of BPb and FEP were observed in the non-smoking workers of the excellent group. CONCLUSIONS: The consistent use of protection devices and cleanliness at work appeared to contribute to the lowering of BPb and FEP. Cessation of smoking in the workplace was also of importance.

Effect of sample thickness on bite force studied with a multiple-point sheet sensor.

The aim of this study was to investigate the relationship between thickness of sample food and bite force. We designed a new sensor that can detect the pressure distribution between the incisor and molar teeth on one side, and the contact area between the food samples and the teeth. The force and contact area were directly measured in real time using the multiple-point sheet sensor, which is a very thin and flexible pressure-sensing device. Silicone rubber blocks were used as a sample food and were chewed with incisors and molars by 10 healthy women. The peak force, contact area, duration and impulse were greater between the incisors for a thicker specimen. The active pressure, defined as the ratio of the force to contact area, at peak was similar for different thicknesses. In contrast, with a 2 mm thick sample, the peak force and force related parameters were greatest in molar chewing. The force, contact area and duration were greater for molar chewing cycles than incisor ones. We verified that the thickness of samples influenced the chewing force of humans and the effects differed between incisors and molars.

Centrally mediated reflex vasodilation in the gingiva induced by painful tooth-pulp stimulation in sympathectomized human subjects.

This study was designed to determine whether painful electrical stimulation of the tooth pulp induces centrally mediated reflex vasomotor changes in human gingiva and whether the sympathetic nervous system is involved in the vasomotor responses. Dynamic changes in maxillary gingival blood flow (GBF) following painful electrical stimulation of the mandibular lateral incisor were investigated, by means of laser-Doppler flowmetry, in both healthy volunteers and patients undergoing sympathetic blockade for hyperhidrosis. Increases in GBF were observed in both healthy volunteers and patients on the ipsilateral side without an increase in systemic blood pressure, but the evoked GBF increase disappeared when pain sensation was abolished by local anesthetization with 2% xylocaine solution. The vasodilator responses did not differ in amplitude between before and after the sympathectomy. These results suggest that painful tooth stimulation evokes centrally mediated reflex vasodilation, presumably via parasympathetic efferent fibers, in the human gingiva and that sympathetic vasomotor mechanisms are not involved in these responses.

Dependence of pulpal blood-flow responses on baseline blood-flow in the cat.

It has been shown earlier that electrical stimulation of the distal cut end of the inferior alveolar nerve (IAN) in the cat evokes three different patterns of pulpal blood-flow (PBF) response in the ipsilateral mandibular canine tooth (a decrease, a biphasic response, or an increase). The response to a given stimulus sometimes changed to another pattern even in one and the same experimental animal during the course of the experiment. It is known that the evoked decrease is due to activation of the sympathetics and that the increase is due to antidromic activation of sensory fibres; but, it is unknown why the response varies so much. It is hypothesised that the baseline blood-flow (BBF) modulates vasomotor responses in the dental pulp. To test this hypothesis, the effects of BBF on PBF responses elicited by the IAN stimulation mentioned above were investigated. Dynamic changes in PBF in cat mandibular canine teeth were elicited by electrical stimulation of the distal cut end of the IAN, at various BBF, with blood-flow monitored by laser Doppler flowmetry. The amplitude of the PBF vasodilator response increased as BBF was adjusted downwards (by cooling the tooth). In contrast, the amplitude of the PBF vasoconstrictor response increased as the BBF rose. Vasodilator responses could be transformed into vasoconstrictor responses, and vice versa, by alterations in the BBF. No systemic blood-pressure changes were elicited throughout the experiment. These results indicate that a consideration of baseline vascular tone is important, whenever the size of PBF responses to various stimuli is discussed or calculated.

Comparison of selenium status between Japanese living in Tokyo and Japanese brazilians in São Paulo, Brazil.

Selenium (Se) concentrations were determined in human serum, rice and wheat flour sampled in the city of São Paulo, Brazil, and compared with those sampled in Tokyo. Japan. Serum levels of Se were significantly lower in Japanese Brazilians than Japanese living in Tokyo. The samples of rice consumed by Japanese Brazilians in São Paulo contained 22.7 ng Se/g on average, which was about half the selenium level in rice consumed in Tokyo. Rice commonly consumed in São Paulo might be one of the factors to lower the serum level of Se.

A search for calcium, magnesium and zinc levels in fingernails of 135 patients with osteogenesis imperfecta.

Calcium (Ca), magnesium (Mg) and zinc (Zn) levels of fingernails were measured in 135 patients with osteogenesis imperfecta (OI) and compared with the sex- and age-matched healthy controls. Zinc levels in OI nails were significantly higher than that in normal subjects, but in cases and controls Ca and Mg levels were not significantly different. The ratios of Ca/Zn and Mg/Zn in OI nails differed significantly from those in controls, but a similar Ca/Mg ratio was found in nails of both groups. These results suggest that Zn levels in fingernails may reflect abnormal Zn metabolism in OI. To determine Zn metabolism changes in OI, further studies are needed.

Differences in parasympathetic vasodilator and salivary responses in the cat submandibular gland between lingual and chorda-lingual nerve stimulation.

Experimental activation of parasympathetic vasodilatation and salivation in the submandibular gland by a "pseudoreflex" method has definite advantages over other commonly used methods. However, it is unclear which stimulation sites allow for avoidance of direct activation of the parasympathetic efferents to this gland. We examined this question in heavily anesthetized (alpha-chloralose and urethane), artificially ventilated, cervically vago-sympathectomized cats, using the intersection of the chorda-lingual nerve and the submandibular gland duct ("the intersection") as our reference point. Both vasodilatation and salivation evoked by electrical stimulation of the lingual nerve were abolished by section of the chorda-lingual nerve (10 mm proximal to the intersection), provided the stimulation site was distal to the intersection by 4 mm or more. This salivation was abolished by the muscarinic receptor antagonist, scopolamine. Thus, by careful choice of stimulation site, submandibular gland responses mediated solely by reflex parasympathetic mechanisms can be evoked by lingual nerve stimulation in this preparation.

Respiratory symptoms and pulmonary function among traffic police in Bangkok, Thailand.

The authors undertook a cross-sectional study of the potential adverse health effects of air pollution in Bangkok, Thailand. During 1998 and 1999, the authors administered lung function spirometry tests and a Thai version of the American Thoracic Society's Division of Lung Diseases (ATS-DLD) respiratory questionnaire to 78 male traffic police and 60 male nontraffic police in Bangkok, as well as to 68 male general police in Ayutthaya province, a rural area in Thailand. No consistent trend of decreased pulmonary function was observed in traffic police. The authors controlled for age, height, and smoking index, after which mean levels of forced expiratory volume in 1 sec and maximal expiratory flow rate in 25% of vital capacity (V25) were significantly lower in Bangkok police than in Ayutthaya police. The prevalence of respiratory symptoms among Bangkok police was slightly higher than among Ayutthaya police. Multiple regression analysis identified age and workplace as statistically significant factors that contributed to the values of forced expiratory volume in 1 sec and V25. This study provided some evidence of an increase in prevalence of obstructive changes in the peripheral airways among traffic police in Bangkok.

Effects of a beta-adrenergic blocking agent timolol on intra ocular pressure responses induced by stimulation of cervical sympathetic nerve in the cat.

We clarified whether the intraocular pressure (IOP) response elicited by stimulation of the cervical sympathetic nerve (CSN) is influenced by changes in the baseline of IOP level and by beta-adrenergic blockade. The CSN was stimulated electrically for 30 seconds (10 V, 0.1-100 Hz, 2 milliseconds pulse duration) in urethane (100 mg/kg i.v.)-chloralose (50 mg/kg i.v.)-anesthetized, paralyzed cats. The IOP was monitored manometrically, and a controlled saline infusion was delivered into the anterior chamber to gradually increase IOP. CSN stimulation was delivered at the various baseline IOP levels so obtained. When required, a beta-adrenergic blocker timolol (2%) was delivered into the conjunctival cul-de-sac. The normal IOP in our cats was 25+/-3 mmHg. This value decreased transiently on CSN stimulation. The amplitude of this IOP response depended on stimulus frequency and the pre-stimulus baseline IOP level. Topical administration of timolol increased the IOP response to CSN stimulation at a given baseline level. These results suggest that beta-adrenergic blockade increases the alpha-adrenergic mediated-IOP reduction elicited by CSN stimulation at given baseline IOP level.

Involvement of nitric oxide in parasympathetic and antidromic vasodilatations in cat lower lip.

The involvement of nitric oxide (NO) in the lower lip vasodilatations mediated via parasympathetic and antidromic mechanisms was examined in alpha-chloralose/urethane-anesthetized cats, with the two types of blood flow responses being recorded separately (by laser Doppler flowmeter) from the two sides of the lower lip. The central cut end of the lingual nerve (LN) or the peripheral cut end of the inferior alveolar nerve (IAN) was electrically stimulated to elicit parasympathetic or antidromic vasodilatation, respectively, in the lower lip. N(G)-nitro-L-arginine methyl ester (L-NAME), but not N(G)-nitro-D-arginine methyl ester (D-NAME) (each at 30 mg/kg), markedly reduced the increases in lip blood flow evoked by stimulation, the reduction being to a similar degree irrespective of whether LN or IAN was stimulated. Pretreatment with L-arginine did not prevent the L-NAME-induced attenuation of either type of vasodilatation. In conclusion, these results suggest that synthesized NO may have a common site of action in antidromic and parasympathetic vasodilator pathways to the cat lower lip.

Parasympathetic reflex vasodilatation in rat submandibular gland.

The present study was designed to investigate 1) whether parasympathetic reflex vasodilatation occurs in the submandibular gland (SMG) in deeply urethan-anesthetized, cervically vagotomized, and sympathectomized rats when the central cut end of the lingual nerve (LN) is electrically stimulated and 2) to what extent the neural mechanisms underlying such responses are the same as those involved in the response to direct stimulation of the chorda-LN (CLN). Stimulation of each nerve separately elicited a marked blood flow increase in SMG. Section of the chorda tympani abolished the SMG blood flow response but had no effect on the lip blood flow increase evoked by LN stimulation. Section of the CLN abolished the SMG blood flow increases evoked by stimulation of either nerve. The SMG blood flow increases (regardless of whether they were evoked by LN or CLN stimulation) were markedly reduced by the autonomic cholinergic ganglion blocker hexamethonium. The present study demonstrates that a parasympathetic reflex vasodilator mechanism is present in the rat SMG and that it can express its effects under deep general anesthesia.

Blood lead levels in copper smelter workers in Japan.

Lead exposure of workers in a Japanese copper smelter was assessed by determining lead levels in blood, air and flue cinder at the copper smelting processes. All the samples were analyzed for lead by atomic absorption spectrometry. Mean lead levels of air were highest at the anode department followed by the converter, smelter and blend departments. The mean level of blood lead of the workers in the anode department was also the highest among the four smelting departments. The mean blood lead levels of the workers in each department were positively correlated with their air lead levels (r = 0.99, p < 0.01). This study indicates therefore that workers in copper smelters have been exposed to lead in their workplace. Though this finding has already been reported in preceding studies, the Ordinance on Prevention of Lead Poisoning in Japan has not included copper smelter into its target job categories if their lead concentration in the raw material is less than 3%. The limitation of the present Ordinance which defines the targets by the types of job and not by the actual exposure, is discussed.

Escape of parasympathetic vasodilatation from sympathetic attenuation in oro-facial areas in the cat.

We examined the effects of concurrent repetitive stimulation of the cervical sympathetic trunk (CST) on the parasympathetically mediated reflex blood flow increase in the orofacial area of cats. In urethane plus alpha-chloralose anaesthetized cats, parasympathetic reflex vasodilatation in the ipsilateral lower lip was elicited by electrical stimulation of the central cut end of the lingual nerve (LN). This blood flow increase was attenuated in a frequency-dependent manner when CST was stimulated concurrently at 0.5-10 Hz for 10 minutes. When we applied repeated LN stimulation (using identical parameters, each time) at intervals during a 30-minutes period of 10 Hz CST stimulation, the attenuation of the blood flow increase gradually weakened in a time-dependent manner even though the direct vasoconstrictor effect of CST stimulation showed no such decline.

Calbindin and calmodulin localization in the developing vestibular organ of the musk shrew (Suncus murinus).

The distribution of the Ca(2+)-binding proteins, calbindin and calmodulin, in the adult inner ear has been described previously. We undertook immunohistochemical investigation of developmental changes in the distribution of calbindin and calmodulin in the vestibular organ of the musk shrew (Suncus murinus). Expression of calbindin was seen first in the hair cells and the vestibular ganglion on gestational day (GD) 19, in nerve fibres on GD23 and in the otoconia on GD26. On GD19 calmodulin was demonstrable only in the hair cells. On GD26 both Ca(2+)-binding proteins showed a distribution of immunoreactivity in hair cells similar to that seen in adults. The developmental differences in distribution of these binding proteins may suggest different roles in the vestibule. Additionally, Ca(2+)-binding proteins may be a useful index of hair cell maturity.

Surgical management and its post-operative complications in congenital aural atresia.

The post-operative complications and hearing results of surgical intervention for congenital aural atresia were investigated. Seventy-five ears with congenital aural atresia were operated on for hearing loss from 1982 to 1996. Tympanoplasty was performed on 37 ears and canaloplasty on the remaining 38. Hearing improvement rates were 70.3% and 31.6%, respectively. The post-operative complications included stenosis of the created auditory canal (29.3%), deterioration of the improved hearing (21.3%) and infection (12.0%). Reoperations were performed on 6 cases for restoring hearing, 16 for stenosis and 6 for infection. Reoperative findings demonstrated that scar formation in the canal caused the stenosis of the newly formed external canal and that lateralization of the new tympanic membrane and subsequent detachment from the ossicles caused the deterioration of improved hearing. Using cartilage and pedicled skin flap prevented stenosis at the orifice of the newly formed external canal. Maintaining hearing improvement requires creating a wide ear canal using as many pedicle flaps as possible and attaching a new tympanic membrane firmly to the ossicles.

Selection effects on an estimation of long-term changes in pulmonary function.

To reveal the association of initial pulmonary function level with subsequent mortality and participation in a follow-up reexamination, a prospective cohort study was performed. Female residents in a volcanic area of southern Kyushu, Japan, were followed up for their vital status and the pulmonary function 15 years after they received the first pulmonary function test. A cohort of 512 Japanese female residents who were examined for pulmonary function as indicated by forced expiratory volume and forced expiratory volume in one second was measured in a baseline examination in 1980. After 15 years, 35 females were lost to follow-up. Of the remaining 477 females, 340 and 137 females provided good and poor levels of pulmonary function tests (PFT) at baseline, respectively. Mortality by 1995 in the poor PFT group was significantly higher than that in the good PFT group (33.6% vs 9.4%). The mortality differences were still highly significant when the 35 lost cases were included as all alive. Among the 399 survivors, the nonparticipation rate in the reexamination in 1995 was significantly higher in the poor PFT group than that in the good PFT group (80.2% vs 69.5%). The results of the present study, a longitudinal study of pulmonary function, provide evidence of selection effects due to death or failure to participate in a subsequent reexamination.

Appearance and distribution of two Ca2+-binding proteins during development of the cochlea in the musk shrew.

In the developing cochlea of the musk shrew, Suncus murinus, the localization of two Ca2+-binding protein, calbindin and calmodulin, which are thought to play different roles in the nervous system, was examined during gestational and postpartum periods. Calbindin is thought to play a Ca2+ buffering role, while calmodulin activates other proteins. Cochleae from the musk shrews sacrificed from gestational day (GD) 15 to postnatal day (PP) 9 and as adults, were immunohistochemically analyzed. The localization and order of appearance of calmodulin in sensorineural elements were similar to those of calbindin, except for timing of appearance. Calmodulin-staining was recognized first in the spiral ganglion neurons on GD21, followed by the inner hair cells (IHCs) on GD23 and outer hair cells (OHCs) on GD26, while calbindin immunoreactivity in the spiral ganglion neurons on GD19, the IHCs on GD21 and the OHCs on GD23. In hair cells, during development, immunostaining of calbindin and calmodulin was initially seen in the cytoplasm, followed by the cuticular plate. Cytoplasmic staining then decreased in mature hair cells. Non-sensorineural components also showed positivity for both calbindin and calmodulin. The lateral wall of the cochlear duct was positive for calbindin, while the stria vascularis was positive for calmodulin. Immunoreactivity for calbindin was present earlier than that of calmodulin in sensorineural elements, suggesting that in the developing cochlea, calbindin and calmodulin have different functions and that Ca2+ buffering capacity, which is regulated by Ca2+ buffer proteins, such as calbindin, may be required before trigger proteins, such as calmodulin, function.

Programmed cell death in the developing epithelium of the mouse inner ear.

Programmed cell death is as essential to development as is proliferation. Thus, the objective of this study was to elucidate the spatiotemporal involvement of programmed cell death in the development of the inner ear epithelia. Programmed cell death is seen in situ as apoptosis. A time-sequence study was performed on the distribution of apoptosis during the development of the inner ear epithelia of the mouse using the TdT-mediated dUTP-biotin nick labeling (TUNEL) method to detect apoptosis histochemically. Apoptosis occurred during the early stages of development of the inner ear and took place earlier in the organs of equilibrium than in the cochlea. These periods corresponded to those of active proliferation of epithelial cells in the inner ear. Since cell-cell interactions change after the removal of neighboring cells by apoptosis, apoptosis may influence cytodifferentiation.