An ex post cost-benefit analysis of the nitrogen dioxide air pollution control program in Tokyo

The benefits and costs of past nitrogen dioxide (NO2) control policies were calculated for Tokyo, Japan, using environmental, economic, political, demographic, and medical data from 1973 to 1994. The benefits of NO2 control were estimated as medical expenses and lost work time due to hypothetical no-control air concentrations of NO2. Direct costs were calculated as annualized capital expenditures and 1 year's operating costs for regulated industries plus governmental agency expenses. The major findings were as follows: (1) Using Tokyo's average medical cost of pollution-related illness, the best net estimate of the avoided medical costs due to incidence of phlegm and sputum in adults was 730 billion yen ($6.08 billion; 1 U.S. dollar = 120 yen). (2) The best net estimate of the avoided medical costs due to incidence of lower respiratory illness in children was 93 billion yen ($775 million). (3) Using Tokyo's average duration of pollution-related illness and average wages, the best net estimate of the avoided costs of lost wages in workers was 760 billion yen ($6.33 billion). (4) The best net estimate of the avoided costs of lost wages in mothers caring for their sick children was 100 billion yen ($833 million). (5) Using Tokyo-specific data, the best net costs were estimated as 280 billion yen ($2.33 billion). (6) Using human health and productivity benefits, and annualized capital cost and operating cost estimates, the best net benefits-to-costs ratio was 6:1 (upper limit 44:1; lower limit 0.3:1). Benefit calculations were sensitive to assumptions of mobile source emissions and certain health impacts that were not included. Cost calculations were highly dependent on assumptions of flue gas volume and fuel use. For comparative purposes, we identified other studies for air pollution-related illness. Assumptions that formed the basis for most of the inputs in the present study, such as duration of illness, medical treatment costs, per person illness in children, and lost wages for working mothers, were similar to those recommended in the literature. Lost wages in sick workers and per capita illness incidence in adults were higher than numbers reported elsewhere. Further advances in cost-benefit analysis (CBA) procedures to evaluate the economic effectiveness of NO2 controls in Tokyo are recommended to estimate impacts and values for additional human health benefits, ecosystem health and productivity effects, and nonliving system effects, as well as benefits of ancillary reductions in other pollutants. The present study suggests that Tokyo's past NO2 control policies in total were economically quite effective.

Effects of intracochlear factors on spiral ganglion cells and auditory brain stem response after long-term electrical stimulation in deafened kittens

Using an animal model, we have studied the response of the auditory brain stem to cochlear implantation and the effect of intracochlear factors on this response. Neonatally, pharmacologically deafened cats (100 to more than 180 days old) were implanted with a 4-electrode array in both cochleas. Then, the left cochlea of each cat was electrically stimulated for total periods of up to 1000 hours. After a terminal (14)C-2-deoxyglucose (2DG) experiment, the fraction of the right inferior colliculus with a significant accumulation of 2DG label was calculated. Using 3-dimensional computer-aided reconstruction, we examined the cochleas of these animals for spiral ganglion cell (SGC) survival and intracochlear factors such as electrode positions, degeneration of the organ of Corti, and the degree of fibrosis of the scala tympani. The distribution of each parameter was calculated along the organ of Corti from the basal end. There was a positive correlation between SGC survival and the level of fibrosis in the scala tympani, and a negative correlation between SGC survival and the degree of organ of Corti degeneration. Finally, there was a negative correlation between the 2DG-labeled inferior colliculus volume fraction and the degree of fibrosis, particularly in the 1-mm region nearest the pair of electrodes, and presumably in the basal turn.

Ethylene formation and phenotypic analysis of transgenic tobacco plants expressing a bacterial ethylene-forming enzyme

A bacterial ethylene-forming enzyme (EFE) catalyzes oxygenation of 2-oxoglutarate to produce ethylene and carbon dioxide in contrast to a plant enzyme which uses 1-aminocyclopropane-1-carboxylic acid as a substrate. We constructed several lines of transgenic tobacco plants which expressed an EFE from Pseudomonas syringae pv. phaseolicola PK2. The gene encoding a chimeric protein consisting of EFE and beta-glucuronidase (GUS) was introduced into the tobacco genome using a binary vector which directs expression of the EFE-GUS fusion protein under the control of constitutive promoter of cauliflower mosaic virus 35S RNA. Two lines of transgenic plants produced ethylene at consistently higher rates than the untransformed plant, and their GUS activities were expressed in different tissues. A significant dwarf morphology observed in the transgenic tobacco displaying the highest ethylene production resembled the phenotype of a wild-type plant exposed to excess ethylene. These results demonstrate a potential use of bacterial EFE to supply ethylene as a hormonal signal via an alternative route using an ubiquitous substrate 2-oxoglutarate in plant tissues.

Subclinical neurophysiological effects of lead: A review on peripheral, central, and autonomic nervous system effects in lead workers

BACKGROUND

The peripheral nerve conduction velocity (NCV), distribution of nerve conduction velocities (DCV), somatosensory, visual, and brainstem auditory evoked potentials (SEP, VEP, and BAEP, respectively), event-related potential (P300), computerized static posturography with spectral analysis (postural balance), and electrocardiographic R-R interval variability (CV(RR)) with spectral analysis appear to be promising techniques for assessing subclinical effects of lead on the peripheral, central and autonomic nervous systems. This article presents an overview of research addressing subclinical neurophysiological effects of lead in workers exposed to lead.

METHODS

We reviewed 102 articles to examine the effects and dose-effects relationships of lead on peripheral, central, and autonomic nervous system function together with reversibility of the effects, interaction between lead and other metals, and relative sensitivity and specificity of each technique. Background and methodology were also reviewed.

RESULTS AND CONCLUSION

Available data suggest that, on a group basis, the reduction in the NCV, together with the effects on the P300 latency, postural balance, and CV(RR), occurs at a mean blood lead concentration (BPb) as low as 30-40 microg/dL; the effects on the latencies of the short-latency SEP, VEP, and BAEP, as well as the DCV, start at a BPb as low as 40-50 microg/dL. Further cross-sectional and preferably prospective studies by using each of those methods are needed to establish more precise dose-effects (and response) relationships of lead.

Cochlear findings in the white spotting (Ws) rat

White spotting (Ws) rats possess a c-kit gene mutation at the W locus, resulting in a variety of characteristics including a lack of intermediate cells of the stria vascularis. The present study employs a light microscope (LM), scanning (SEM) and transmission electron microscopes (TEM), diaminobenzidine (DAB) staining techniques and auditory brainstem response (ABR) to investigate the structure and function of the cochlea in 26 homozygous Ws/Ws rats aged 1-6 months. A slight thinning of the stria vascularis and moderate elevation of ABR threshold were about the only defects noted in 1 month animals, while older animals displayed various defects that tended to worsen with age. At 3 months LM revealed pigment granules in the basal turn of most animals, with a loss of pigmentation in the upper turns. The stria vascularis and organ of Corti tended to be well preserved in the lower, pigmented portion, while the upper, unpigmented portion showed severe strial degeneration and some outer hair cell loss. DAB staining revealed a well developed strial capillary net throughout the pigmented portion of the cochlea, with severe degradation in the unpigmented apical portion. ABR thresholds were slightly elevated over 1 month values. At 6 months great differences in degeneration were noted between right and left ears of the same animal.

Decrease of suppressor-inducer (CD4+ CD45RA) T lymphocytes and increase of serum immunoglobulin G due to perceived job stress in Japanese nuclear electric power plant workers

To clarify the effects of perceived job stress on the immune system, a cross-sectional study was conducted in 116 male Japanese workers of a nuclear electric power plant (age, 20 to 39; mean, 31 years). Perceived job stress, i.e., psychological job demand, job control, worksite social support, and job strain, was assessed by means of the Japanese version of the Job Content Questionnaire. The job strain score was calculated as the ratio of the job demand score to the job control score. Blood samples were taken from all workers, and numbers of T and natural killer cell subpopulations, B lymphocytes, total lymphocytes and white blood cells, and serum concentrations of immunoglobulins (IgG, IgM, IgA, IgE and IgD) in their blood were measured. The workers were divided into higher and lower strain groups according to their job strain scores. The number of CD4+ CD45RA+ T lymphocytes in the higher strain group having the job strain score of 0.5 or more (41 workers) was significantly smaller than that in the lower strain group having the score of less than 0.5 (75 workers). In contrast, the serum IgG concentration in the former group was significantly higher than that in the latter group (analysis of covariance with age and smoking as covariates). Also, the numbers of total CD4+ T and total T (CD3+) lymphocytes and of white blood cells in the former group were significantly smaller than those in the latter group. After controlling for age and smoking by the partial correlation coefficient in all 116 workers, the number of CD57+ CD16+ natural killer cells was inversely correlated with job demand and with job strain; the number of CD8+ T lymphocytes was positively correlated with worksite social support; and serum IgG and IgM concentrations were positively correlated with job strain. It is suggested that higher job strain decreases the number of CD4+ CD45RA+ T lymphocytes in male Japanese workers but increases serum IgG concentrations.

[Pharmacological properties of donepezil hydrochloride (Aricept), a drug for Alzheimer's disease]

One of the most consistent changes associated with Alzheimer's disease (AD) is a deficit in central cholinergic neurotransmission. Donepezil hydrochloride (DPZ), a novel class of cholinesterase (ChE) inhibitors, inhibits degradation of acetylcholine (ACh) and activates central cholinergic system. In in vitro studies, DPZ more selectively inhibited acetylcholinesterase (IC50: 6.7 nM) than butyrylcholinesterase (IC50: 7400 nM), while tacrine inhibited both acetylcholinesterase (IC50: 77 nM) and butyrylcholinesterase (IC50: 69 nM). After oral dosing, DPZ (ID50: 2.6 mg/kg) inhibited brain ChE dose-dependently without any remarkable effect on ChE in the heart and small intestine, whereas tacrine (ID50: 9.5 mg/kg) inhibited ChE equally in the brain and peripheral tissues. Brain microdialysis revealed that DPZ (2.5 mg/kg) enhanced extracellular ACh concentrations in the cerebral cortex and hippocampus in rats. In behavioral studies, DPZ counteracted both the deficit in passive avoidance induced by lesioning of the nucleus basalis magnocellularis (0.125-1.0 mg/kg) and the impairment in acquisition of a hidden-platform water maze task after lesioning of the medial septum in rats (0.5 mg/kg). DPZ also inhibited the scopolamine-induced impairment of radial maze performance (0.5 mg/kg). Placebo-controlled clinical studies of 12- and 24-week treatments of DPZ (5 mg, 10 mg/day) clearly showed an improvement in cognitive scores of probable AD patients.

Changes in cold-induced vasodilatation, pain and cold sensation in fingers caused by repeated finger cooling in a cool environment

To examine how repeated cooling of fingers with a rest pause schedule at work affects cold-induced vasodilatation (CIVD), pain and cold sensation in fingers, six healthy men aged 21 to 23 years immersed their left index fingers six times in stirred water at 10 degrees C for 10 minutes. After each cold-water immersion of the fingers, 5-minute rest pause was taken to observe the recovery process of the indicators. This cold-water immersion/rest pause test was carried out in a range of three ambient temperature conditions: 30 degrees C (warm), 25 degrees C (thermoneutral), and 20 degrees C (cool) as experienced in daily life. At the ambient temperatures of 30 degrees C and 25 degrees C, marked CIVD response occurred and the CIVD reactivity did not significantly change upon repetition of cold-water immersion. The lowered finger skin temperature also tended to recover quickly to the pre-immersion level during each post-immersion rest period. At the ambient temperature of 20 degrees C, however, the CIVD response weakened continuously upon repetition of immersion and almost disappeared during the final immersion. The recovery of finger skin temperature during each post-immersion rest was gradually delayed upon repetition of immersion. At every ambient temperature, finger pain and cold sensation induced by each cold-water immersion significantly decreased upon repetition of immersion and completely disappeared during each post-immersion rest period. Oral temperature during the experiment showed no significant change at the ambient temperatures of 25 degrees C and 30 degrees C, but it decreased significantly at the ambient temperature of 20 degrees C. These results suggest that in a cool work environment where the body core temperature is liable to decrease, repeated finger cooling may weaken CIVD reactivity and delay the recovery of finger temperature during post-immersion rest periods. In such lower ambient temperature work conditions, subjective judgements such as the decrease in finger pain and cold sensation during repeated finger cooling and the absence of them during post-immersion rest may not be reliable indicators for monitoring the risk of progressive tissue cooling and frostbite formation.

Yields and daily consumption of cigarettes in Japan in 1969-1996

Cigarette modification trends and the relationship between nicotine yields and consumption in Japan were examined over the 27 years between 1969-1996. Data on cigarette use were obtained from reports published by the government and tobacco manufacturers. Over the study period, there has been a coherent pattern of cigarette modification in Japan. The sales-weighted average yields have declined from 20.7 mg tar and 1.64 mg nicotine/cigarette in 1969 to 8.7 mg tar and 0.72 mg nicotine/cigarette in 1996. On the other hand, the average daily consumption per smoker has continuously increased over the same period. Average nicotine yields and daily cigarette consumption have significant negative correlations among both males and females. This relationship was observed even after controlling for the price changes of cigarettes over time. It is indicated that smokers have compensated for reduced nicotine yields by increasing daily consumption. This may have offset potential benefits of the continuous decline in tar and nicotine yields to smokers' health.

Clinical efficacy of peritoneovenous shunting for the treatment of severe ovarian hyperstimulation syndrome

We investigated prospectively the clinical efficacy of a newly developed continuous autotransfusion system of ascites (CATSA) without protein supplement in patients with severe ovarian hyperstimulation syndrome (OHSS). Peritoneovenous shunting was used to recirculate ascites. The CATSA was performed for 5 h at a rate of 100-200 ml/h once a day. Eighteen patients were treated with the CATSA (CATSA group) and 36 were treated with an intravenous 37.5 g/day of albumin supplement (albumin group). Hospital stay was significantly shorter in the CATSA group than in the albumin group (10.0 +/- 5.7 versus 13.9 +/- 6.2 days, P < 0.01). Haematocrit value reached <40% significantly earlier in the CATSA group (on hospital days 3.9 +/- 3.2 versus 5.9 +/- 2.5, P < 0.01). Using a single procedure, haemoconcentration, urinary output and pulse pressure were markedly improved in the CATSA group compared with the albumin group. Discomfort due to massive ascites diminished promptly and did not recur in nine of 18 CATSA group patients, whereas it persisted in all 36 patients in the albumin group. The serum concentration of protein was maintained in the CATSA group, whereas it did not increase in the albumin group despite daily supplementation with 37. 5 g of albumin. Apparent adverse effects of each procedure were not observed in either group. The mean values of several parameters in the serum pertinent to the coagulation-fibrinolysis system did not change significantly in either group after the procedure. It was concluded that the CATSA procedure expanded circulating plasma volume without exogenous albumin and appeared to lead to a prompt recovery from severe conditions of OHSS.

Chronic electrical stimulation of the auditory nerve using non-charge-balanced stimuli

This study was designed to evaluate the pathophysiological response of the cochlea following long-term intracochlear electrical stimulation using a poorly charge-balanced stimulus regime, leading to direct current (DC) levels >0.1 microA. Four normal-hearing adult cats were bilaterally implanted with scala tympani electrode arrays and unilaterally stimulated for periods up to 2200 h. Stimuli consisted of 50 micros monophasic current pulses presented at 2000 pulses per second (pps) per channel, and resulted in DC levels of 0.4-2.8 microA. Both acoustic and electrical (EABR) evoked potentials were periodically recorded during the stimulation program. Frequency-specific stimuli indicated that an extensive and widespread hearing loss occurred over the 4-24 KHz region in all stimulated cochleae, although the 2 KHz region exhibited thresholds close to normal in some animals, despite long-term implantation and chronic stimulation. Longitudinal EABRs showed a statistically significant increase in threshold for three of the four animals. Histopathological evaluation of the cochleae revealed a highly significant reduction in ganglion cell density in stimulated cochleae compared with their controls. Spiral ganglion cell loss was significantly correlated with the degree of inflammation, duration of electrical stimulation, and the level of DC. In conclusion, the present study highlights the potential for neural damage following stimulation using poorly charge-balanced stimuli.

Chronic active desease refext cancer riski in ulcreative collitis

There is an increased risk of developing colorectal neoplasia in ulcerative colitis (UC) and surveillance colonoscopy is recommended for early detection. We investigated the precise features of UC retrospectively to identify a subgroup with longstanding extensive UC at increased risk of neoplasia. From 1985 to August 1997, we experienced eight UC patients with colorectal cancer and eight with definite dysplasia. All 16 had extensive disease of seven years or more in duration. During the same period, 61 of 334 UC patients without colorectal neoplasia were available for detailed study, allowing evaluation of non-surgical patients with extensive colitis of seven years or more in duration. Basic clinical factors including family history of cancer, expressions of disease activity and durations of pharmacotherapy were investigated. Univariate analysis revealed four significant factors: intractability (P=0.001), periods of inflammation persisting for 3 months or more (P<0.01) and total durations of diarrhea (P<0.01) and hematochezia (P<0.05). The number of admissions and the duration of systemic steroid administration were higher in the neoplasia group but without statistical significance. Multivariate analysis revealed two significant factors: duration of diarrhea (P<0.001) and age at onset (P<0.01). Chronic active disease is a risk factor for colorectal cancer or dysplasia in extensive and longstanding UC.

Psychobehavioral effects of divorced mother-headed one-child families on children in China

Owing to the national "One Child per Family" policy in China, almost all children are from one-child families. Recent economic development has led to an increase in the number of children living in single parent families. These children may suffer from more mental stress than those living in two parent families. This study aims at clarifying psychobehavioral characteristics of boys and girls from mother-headed one-child families due to divorce. Three questionnaire studies, i.e., Eysenck Personality Questionnaire for Children (EPQ), Mental Health Test (MHT), and Preliminary Problems Conduct Test (PPCT) were conducted on 465 children, aged 9 to 12 years, in three elementary schools of Chengdu, China. Twenty-one boys and 26 girls from divorced families and 186 boys and 217 girls from non-divorced families were selected as study subjects. The results of the multiple stepwise logistic regression analysis indicated that boys from divorced families suffered from neurosis, loneliness, impulsiveness, rebellious tendencies and untruthfulness, whereas girls from divorced families suffered from loneliness, horrible feelings and oppressed feelings. It is suggested that the common psychobehavioral characteristic of both boys and girls from divorced families in China is loneliness; the characteristic specific of boys is "antisocial" personality and that of girls is "anxious" personality.

Involvement of gene expressions in apoptosis of vascular endothelial cells induced by rattlesnake venom

Formation of apoptotic bodies is a typical character of apoptotic cell death, but how the processes are controlled is not known. In this study, we compared two apoptosis inducing systems in vascular endothelial cells (VEC). We found that the formation of apoptotic bodies during apoptosis induced by rattlesnake venom, which is an unique and specific apoptosis inducer to vascular endothelial cells, was much faster than that induced by deprivation of survival factors (aFGF and serum). When we blocked the synthesis of mRNAs in cells treated with rattlesnake venom by DRB (5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole), an inhibitor of transcription, the formation of apoptotic bodies was dramatically inhibited. We examined the expression of p53 gene and found that its expression was much higher in apoptosis induced by rattlesnake venom than that in apoptosis induced by deprivation of aFGF and serum. Our results suggest that gene expression is important and p53 gene may play a major role in inducing the formation of apoptotic bodies in VEC.

Immunohistochemical evaluation of the marbled state in childhood hypoxic encephalopathy

We have immunohistochemically analyzed the marbled state in 8 cases of perinatal hypoxic ischemic encephalopathy and 4 cases of infantile hypoxic encephalopathy, using antibodies against calbindin-D28k (CaBD), glial fibrillary acidic protein (GFAP), methionine-enkephalin (MEnk), myelin basic protein (MBP), neurofilament (NF), parvalbumin (PV), substance-P (SuP) and synaptophysin (SP). The marbled state was found in the thalamus in 11 cases, whose age at death was over 10 years. Four cases demonstrated the marbled state in the cerebral cortex, in addition to the striatum and/or the thalamus. The abnormally myelinated fibers in the marbled state were stained with both Kluver-Barrera and Holzer stainings; however, they were partly immunopositive for MBP and completely immunonegative for GFAP, CaBD, MEnk, PV, SuP and SP, although some of the neurons and/or fibers showed immunoreactivities for those calcium-binding proteins and/or neurotransmitters. The axons were visualized in the abnormally myelinated fibers by Bodian staining and/or anti-NF immunostainings in the cerebral cortex and striatum but not in the thalamus. GFAP-positive astrocytes did not show any continuity with the abnormally myelinated fibers. These histological features were seen in the cerebral cortex, striatum and thalamus. Difference of the etiology did not affect the histological features with the exception of anti-PV staining, in which PV-immunopositive neurons were observed only in aged subjects with infantile hypoxic encephalopathy, and seemed to be more severely affected by hypoxic stress during the perinatal period than the early infantile period. These data suggest that the site of lesion or the length of survival period after brain injury might influence the formation of the marbled state rather than the etiology. And the direct relationship between the abnormally myelinated fiber and astrocytic process was not verified.

[Multiple chemical sensitivities: case definition, etiology and relations to allergy, poisoning, psychogenic illness etc]

Multiple Chemical Sensitivities (MCS) have been defined as an acquired disorder characterized by recurrent symptoms, referable to multiple organ systems, occurring in response to demonstrable exposure to many chemically unrelated compounds at doses far below those established in the general population to cause harmful effects; no single widely accepted test of physiologic function can be shown to correlate with symptoms (Cullen MR, 1987). The etiology of MCS is hypothesized as a toxicant-induced loss of tolerance to multiple chemicals with subsequent manifestation of multiple-organ symptoms triggered by low-level exposure to such chemicals. The involvement of multiple organs might be attributed to a neurogenic switching mechanism. The final diagnosis of MCS is to rely on provocation of symptoms in a exposure chamber by a double-blind method. Relations of MCS to allergy, poisoning, psychogenic illness, chemical sensitivity, idiopathic environmental intolerances etc. are discussed in terms of case definition and etiology of these disorders.

Decavanadate inhibits the cell-free activation of neutrophil NADPH oxidase without affecting tyrosine phosphorylation

NADPH oxidase was activated by arachidonate in a cell-free system consisting of membrane and cytosol fractions prepared from guinea pig neutrophils. Vanadate apparently inhibited the NADPH oxidase activity in the cell-free system (IC50=2 microM) without phosphotyrosine accumulation. The pH dependency and stability of the inhibitory effect observed for vanadate solution indicated that decavanadate, an isopolyanion of vanadate, was responsible for the inhibition. Pervanadate (vanadyl hydroperoxide) also inhibited the oxidase activity but at a higher concentration (IC50=0.2 mM). Decavanadate lowered the Vmax but did not affect the Km value of NADPH oxidase for NADPH. Decavanadate inhibited the activation process of NADPH oxidase but not the oxidase activity itself. Decavanadate-pretreatment of membrane and cytosol fractions irreversibly decreased the abilities of both fractions to activate NADPH oxidase in the cell-free system. Translocation of p47-phox, one of the cytosolic activation factors of NADPH oxidase, from cytosol to membrane, was little affected by decavanadate. These results suggest that decavanadate inhibits the activation of NADPH oxidase in the cell-free system without affecting the phosphotyrosine phosphatase, and that decavanadate can bind to both the membrane and cytosolic activation factors when they are in a dormant state, but not to the active oxidase complex.

Convenient preparation of [Orn(Tfa)2]- and [Orn(Boc)2, Orn(Tfa)2]gramicidin S, versatile unsymmetrically protected derivatives of gramicidin S

Treatment of gramicidin S (GS) with trifluoroacetic anhydride afforded a derivative in which only one of the two Orn side chains was trifluoroacetylated in 72% yield, furnishing the first efficient method for the preparation of a monoprotected derivative of GS. The mono(Tfa) derivative [Orn(Tfa)2']GS was treated with di-tert-butyl dicarbonate to yield dually protected derivative [Orn(Boc)2,Orn(Tfa)2']GS from which another monoprotected derivative [Orn(Boc)2]GS was prepared in high yield. These unsymmetrically protected GS derivatives are versatile starting materials for the preparation of various other GS derivatives. As an example of application of the unsymmetrically protected derivatives, a dimeric GS derivative was prepared via a singly p-nitrobenzenesulfonyl(NBS)-activated derivative [Orn(Boc)2,Orn(NBS)2']GS.

Successful metaphase chromosome analysis of human elongated spermatids using mouse oocytes

Human elongated spermatids from azoospermic patients were inserted into mouse oocytes by intracytoplasmic sperm injection (ICSI). The injection resulted in survival rates of 46.5% (180 out of 387) and activation rates of 36.1% (65 out of 180). The rate of two pronuclear (2PN) formation was 35.4% (23 out of 65). Only 34.8% (eight out of 23) metaphase chromosome spreads from 2PN zygotes could be analysed; however, all were of normal karyotype. Cytogenetic analysis at the first metaphase revealed that human elongated spermatid chromosomes were able to undergo replication in a heterogeneous environment.

Optical resolution and absolute configuration of N-benzyloxycarbonyl-alpha-alkoxyglycines

Optical resolution of racemic N-benzyloxycarbonyl-protected alpha-alkoxyglycines, (+/-)-Cbz-Gly(OR)-OH (R = Et and Pr(i)), was achieved by means of fractional crystallization of diastereomeric salts with (+)-(1S,2S)-2-amino-1-phenyl-1,3-propanediol or diastereomeric esters of (+)- or (-)-menthol. The D- and L-configurations were assigned to the (+)- and (-)-Cbz-Gly(OR)-OH, respectively, based on L-enantioselective enzymatic hydrolysis of (+/-)-Cbz-Gly(OR)-OR' (R = Me, Et, and Pr(i); R' = CH(2)CF(3) and Me) using porcine pancreatic lipase and papain. Chiroptical properties and HPLC retention times of D- and L-Gly(OR)-residue (R = Me and Pr(i))-containing peptides were compared in relation to their configurational assignments. Copyright 1999 Wiley-Liss, Inc.

Evoked potentials in Faroese children prenatally exposed to methylmercury

A study of 7-year-old children from a fishing village on Madeira has suggested that latencies of evoked potentials may be delayed because of increased exposures to methylmercury during development. Data from a previously published prospective study in the Faroe Islands have therefore been reexamined. Because of changes in instrumentation, results obtained during the second year of examination were excluded. After this restriction, the results show significant mercury-associated delays of the peak III latency and the I-III interpeak latency of the auditory brainstem evoked potentials. Mercury concentrations in both maternal hair at parturition and in cord blood indicated this association, whereas no such relationship was apparent with the child's current hair-mercury concentration. Thus, in agreement with the findings from Madeira, a delay of the peak III latency of the brainstem auditory evoked potentials appears to serve as a marker of prenatal methylmercury toxicity from contaminated seafood.

Delayed evoked potentials in children exposed to methylmercury from seafood

Methylmercury poisoning may cause constriction of visual fields and deafness, especially if exposure occurs prenatally. However, the risks associated with exposure from contaminated seafood is unclear. We examined 149 children attending first grade in a Madeiran fishing community. As maternal dietary habits were relatively unchanged, current maternal hair concentrations were used as indicator of the child's prenatal exposure to methylmercury (geometric average, 9.64 microg/g [48.2 nmol/g]). After adjustment for age and sex, the mean (+/-SD) latency of peak III of the brainstem auditory evoked potentials at 40 Hz was increased by 0.128+/-0.047 ms when maternal hair-mercury concentrations exceeded 10 microg/g (50 nmol/g) (p for association, 0.002), and the increase of the N145 pattern-reversal visual evoked potential latency at 15 minutes of arc was 3.16+/-1.57 ms (p for association, 0.002). No such relationships were seen with the child's own hair-mercury concentration, and other clinical examinations revealed no mercury-associated deficits. Neurophysiological evidence of adverse effects on brain function are relatively independent of confounders, and should be considered in the risk assessment of this seafood pollutant.