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Biomedical subjects

H Aono

Publications and source records attributed to H Aono.

At least 73 records · Page 4Linked to original sources
PubMed1988

Retinoic acid promotes proliferation and chondrogenesis in the distal mesodermal cells of chick limb bud.

Distal and proximal mesoderm of chick limb bud was respectively dissociated and cultured in the medium containing various concentrations of retinoic acid (RA). At low concentrations (5-50 ng/ml), RA promoted proliferation and chondrogenesis in the distal mesodermal cells. The distal cells of stage 20-24 limb buds were responsive to RA, although those of stages 25-27 were unresponsive. Both the cells of anterior and posterior regions of the distal mesoderm were responsive to RA, while the cells of proximal mesoderm were unresponsive. At higher concentrations, the growth-promoting effect of RA was reduced and chondrogenesis in the distal cells was rather inhibited. These results were discussed in relation to the role of RA as the morphogen in normal limb development and experimental duplicate formation.

Animals↗
PubMed1988

Determination of the distribution of nerve conduction velocities in chain saw operators.

By measuring the distribution of conduction velocities (DCV) in sensory fibres of the median nerve, the effects of local vibration on all faster and slower large myelinated nerve fibres were examined in 10 male chain saw operators (three operators had frequent attacks of white finger; the attacks were only occasional in four and negative in three). All parameters of DCV, and conventional sensory nerve conduction velocity were significantly slowed in the chain saw operators. It is suggested that local vibration affects the faster and slower nerve fibres; parameters of the DCV are sensitive indicators of both the neurological and vascular effects.

Adult↗
PubMed1988

Reversibility of psychological performance in subclinical lead absorption.

To evaluate the reversibility of the effect of lead on psychological performance, five performance scale subtests of the Wechsler Adult Intelligence Scale were conducted twice at two-yr intervals on 17 gun-metal foundry workers who had initial blood lead (BPb) concentrations of 30-64 (median 40) micrograms/dl. The results indicated that psychological performance was significantly affected by lead absorption in the first examination, resulting in a reduction in score on picture completion at the BPb level of 40-64 micrograms/dl. In the second examination, following a decrease in the BPb level, the reduced performance recovered. The two-year alteration in the picture completion subtest in all workers was significantly correlated with the corresponding change in mobilization yield of lead in urine by CaEDTA. It is suggested that the effect of lead on psychological performance is reversible at the BPb level below 65 micrograms/dl.

Humans↗
PubMed1987

Effects of lead, zinc and copper absorption on peripheral nerve conduction in metal workers.

To examine the antagonistic effects of lead, zinc and copper on the nervous system in man, we measured maximal motor and sensory conduction velocities (MCV and SCV, respectively) in the distal radial and median nerves in 20 gun metal founders with asymptomatically increased absorption of these metals [blood lead concentrations ranged from 16 to 64 micrograms/dl (mean 42)]; and analyzed metal effects on nerve conduction by multiple regression analysis. The MCVs in the radial and median nerves and the SCV in the forearm segment of the median nerve were significantly slowed; indicators of lead absorption (urinary delta-aminolevulinic acid and coproporphyrin) were inversely correlated with the SCV in the radial nerve. The SCVs in the radial nerve and in the hand segment of the median nerve, which were not significantly slowed, were positively related to indicators of copper absorption (plasma or erythrocyte copper). The SCV in the radial nerve was also positively related to the indicator of zinc absorption (plasma zinc); similarly, the MCVs in the radial and median nerves were positively related to the indicators of zinc absorption (erythrocyte or urinary zinc). These findings suggest that copper and zinc antagonize the subclinical effects of lead on peripheral nerve conduction velocities; the conduction velocity in the distal radial nerve is sensitive not only to asymptomatic lead absorption but also to zinc and copper absorption.

Absorption↗
PubMed1987

Central and peripheral nervous system dysfunction in workers exposed to lead, zinc and copper. A follow-up study of visual and somatosensory evoked potentials.

To evaluate the effects of lead, zinc and copper in the causation of physiological changes in the central and peripheral nervous systems, we measured the latencies of pattern-reversal, visually-evoked potential (VEP) and of short-latency, somatosensory-evoked potential (SSEP) twice at a 12-month interval in nineteen gun metal founders exposed to lead, zinc and copper. The workers' initial blood-lead (BPb) concentrations ranged from 16 to 64 (mean 42) micrograms/dl. BPb and plasma zinc and copper concentrations decreased significantly during the study period owing to the improvement in working environments. In the first examinations, we found that the N2 latency of VEP (conduction time from the retina to the visual cortex) and the N9-N13 latency of SSEP (conduction from the brachial plexus to the medulla oblongata) were both significantly prolonged in exposed workers. In the second examination, the N2 latency had returned to the "normal" level. These changes were correlated positively with changes in the indicators of lead absorption and inversely with changes in the indices of zinc and copper absorption. In the first examination, the N9 latency of SSEP (median nerve conduction) was also found to be significantly prolonged. This change also returned to normal over the study period in proportion to the reduction in BPb and the increase in intra-erythrocytic enzyme delta-aminolevulinic acid dehydratase activity. On the other hand, no significant prolongation of the N13-N20 latency of SSEP (central nerve conduction) was found in either of the two examinations; this latency and alteration over the study period were inversely correlated with the indicators of zinc and copper absorption. These data suggest that lead interferes with both peripheral and central nerve conduction. zinc and copper appear to antagonize strongly the lead-induced conduction delay in the upper central nervous system, but only weakly in the lower central and peripheral nervous systems.

Adult↗
PubMed1987

Assessment of central and peripheral nerve functions in chain-saw operators: a study of short-latency somatosensory evoked potential and peripheral nerve conduction.

In order to clarify the effects of local vibration on the peripheral and central nervous system, peripheral (median) nerve conduction velocities and short-latency somatosensory evoked potentials (SSEP) following stimulation of the median nerve at the wrist were measured in 15 male forest workers in 1986. They had engaged in chain-saw operation for 16-34 (mean 22) years; their working days in 1985 averaged 124 days with a range of 50-203 days. The results indicated significant delays in maximal motor and sensory nerve conduction velocities followed by prolongation of all 4 peak latencies of SSEP up to the sensory cortex of the brain (N9, N13, N20 and P23 latencies) in chain-saw operators; their N9 and P23 latencies were significantly correlated with total working days per year. On the other hand, no significant prolongation of the interpeak latencies of SSEP (i.e., cervico-spinobulbar and central conduction times) was found in the workers. It is concluded that local vibration predominantly affects peripheral nerve conduction; cervico-spinobulbar and central nerve conduction may not be significantly affected.

Adult↗
PubMed1986

Psychological performance in relation to central and peripheral nerve conduction in workers exposed to lead, zinc, and copper.

Psychological performance was examined in relation to central and peripheral nerve conduction by means of the Wechsler Adult Intelligence Scale test, short-latency somatosensory-evoked potential (SSEP), and median nerve conduction velocity in 19 male gun-metal foundry workers exposed to lead, zinc, and copper. (Their blood lead concentrations--ie, 16-64 micrograms/dl with a mean of 42--and plasma zinc and copper concentrations were significantly higher than those of control subjects). In these workers, the score of picture completion (psychological performance) was significantly low; indicators of lead absorption, but no indicators of zinc and copper absorption, were significantly correlated with this score. The score of picture completion was significantly correlated with the N11-N13 latency of SSEP (conduction time in the spinobulbar region) in the workers; their N11-N13 latency, together with the N9 and N9-N11 latencies, was significantly prolonged and was significantly correlated with indicators of lead absorption. Furthermore, their maximal motor and sensory conduction velocities of the median nerve were significantly slowed. It is concluded that both psychological performance and central and peripheral nerve conduction may be impaired in lead-exposed workers with BPb's below approximately 60 micrograms/dl.

Adult↗
PubMed1986

Subclinical cervico-spino-bulbar effects of lead: a study of short-latency somatosensory evoked potentials in workers exposed to lead, zinc, and copper.

Subclinical central and peripheral nervous system dysfunction among lead-exposed workers was studied by measuring short-latency somatosensory evoked potentials (SSEP) and maximal motor and sensory nerve conduction velocities (MCV and SCV) following stimulation of the median nerve at the wrist. The examinations were conducted in 20 gun-metal foundry workers exposed to lead, zinc, copper, and tin, with blood lead (BPb) concentrations of 16 to 64 micrograms/dl (mean, 42 micrograms/dl). The interpeak latency of SSEP in the cervico-spino-bulbar region [N9(Erb)-N13 latency] was significantly prolonged, and the MCV and SCV in the forearm were significantly slowed. Multiple regression analysis revealed that the yield of urinary lead following challenge with calcium disodium ethylenediamine tetraacetate (CaEDTA) and packed red blood cell volume were the major factors associated with the prolongation of SSEP latency in the cervico-spino-bulbar region. Similarly, the interpeak latency in the upper central nervous system (N13-N20 latency) was inversely related to the zinc concentration in erythrocytes; latency up to the Erb's point [N9(Erb) latency], which reflects conduction time in a long pathway of the sensory median nerve, was inversely related to urinary zinc level; the MCV and SCV in the palm were positively related to erythrocyte zinc concentration and plasma copper concentration, respectively. These findings suggest that the subclinical neurophysiological effects of lead occur not only in peripheral nerves but also in the central nervous system. It appears that zinc antagonizes the central and peripheral neurologic dysfunction caused by lead; similarly, copper antagonizes the peripheral sensory nerve dysfunction.

Adult↗
PubMed1986

Comparison of the effects of urinary flow on adjusted and non-adjusted excretion of heavy metals and organic substances in 'healthy' men.

The effect of variation in urinary flow rate (ml urine min-1, UF) on adjusted and non-adjusted urinary excretion of metals and organic substances was examined in ten 'healthy' men. The effect of UF was found to be eliminated when urinary concentrations of lead (Pb), hippuric acid (HA), delta-aminolevulinic acid (ALA) and coproporphyrin (CP) were adjusted to urinary specific gravity and to UF. Similarly, the effect of UF on inorganic mercury (Hg) was eliminated when the concentration was adjusted to timed excretion and to UF. The effect on zinc (Zn) and copper (Cu) was eliminated when adjusted to urinary creatinine (Cn) and to UF. The difference in the effect of UF on the adjusted urinary excretion was explained by the effect of UF on timed excretion of substance, which was ranked in the following order: Pb, HA, total urinary solutes, ALA and CP; Zn; Cu; Cn; and Hg. It was concluded that 'UF-adjusted concentration' is applicable to measurement of all substances in urine as a method of minimizing UF effects, while the other three adjustment methods have only limited uses.

Adult↗
PubMed1986

Determination of the distribution of conduction velocities in workers exposed to lead, zinc, and copper.

By measuring the distribution of conduction velocities (DCV) in sensory fibres of the median nerve, the effects of asymptomatic increased lead, zinc, and copper absorption on the conduction velocities of slower and faster nerve fibres were examined in 29 gun metal founders with blood lead (BPb) concentrations of 22-59 (mean 39) micrograms/dl (1.1-2.8 (mean 1.9) mumol/l). The results indicated that the conduction velocities of slower fibres were inversely affected by lead absorption, resulting in a significant reduction in the velocities at the BPb level of 40-59 micrograms/dl; on the other hand, the conduction velocities of faster fibres and the conventional sensory nerve conduction velocity were presumably positively affected by zinc absorption without a significant reduction in the velocities of faster fibres. It is suggested that assessment of the possible antagonistic effect of zinc is essential when conduction velocities are not decreased in lead exposed workers.

Action Potentials↗
PubMed1986

Mobilisation of heavy metals into the urine by CaEDTA: relation to erythrocyte and plasma concentrations and exposure indicators.

To investigate the effects of calcium disodium ethylenediamine tetra-acetate (CaEDTA) on the urinary excretion, erythrocyte, and plasma concentrations and exposure indicators of seven heavy metals, CaEDTA was administered by intravenous infusion to 20 workers exposed to lead, zinc, and copper. The workers' blood lead concentrations ranged from 22 to 59 micrograms/dl (mean 38 micrograms/dl (1.8 mumol/l]. The 24 hour urinary excretion of metals after CaEDTA administration (mobilisation yield) was on average 13 times the background excretion for lead, 11 times for zinc, 3.8 times for manganese, 3.4 times for cadmium, 1.3 times for copper, and 1.1 times for chromium; no significant increase was found for mercury. The mobilisation yield of lead (MPb) was significantly correlated with whole blood and erythrocyte concentrations and the urinary excretion of lead but not with its plasma concentration; similarly, the mobilisation yield of cadmium was significantly correlated with its erythrocyte concentration. In addition, MPb was significantly correlated with intra-erythrocytic enzyme delta-aminolaevulinic acid dehydratase activity and urinary coproporphyrin excretion. The relation between the mobilisation yield of heavy metals and their body burden (and toxic signs) is discussed in the light of these findings.

Adult↗