Physical characteristics of vibration in relation to vibration-induced white finger

Predicted and observed prevalences and latency periods of vibration-induced white finger (VWF) were examined among workers exposed to hand-arm vibration. The different physical characteristics of vibration--spectra and impulsiveness--were measured. The following groups of workers were included in the study: forest workers (n = 199), pedestal grinders (n = 12), stone workers (n = 16), shipyard workers (n = 171), and platers (n = 5). The exposure to vibration was measured according to the ISO 5349 method. The impulsiveness of vibration was defined as the difference between peak levels and RMS levels. A good agreement was observed between the predicted and observed data for prevalence and latency of VWF in the forest workers. For the tools with high impulsiveness used in grinding, stone works, and shipyard assembly hall, the results were nonconfirmative; and there was a poor correlation between vibration and VWF. The ISO 5349 standard does not consider the high peak values of the vibration signal which may comprise high-frequency components and cause short transients in the underlying tissue of the worker's hand. These characteristics in vibration may be hazardous in the genesis of VWF and cannot be predicted when measuring vibration by the present standard method.

Measuring method for vibration perception threshold of fingers and its application to vibration exposed workers

A measuring method for the vibration perception threshold (VPT) of fingers has been developed. The VPTs of 118 and 149 professional forest workers were measured during a compulsory annual health examination in 1979 and 1983, respectively. Also the VPTs of eight pedestal grinders, who were suffering vibration-induced white finger (VWF), were measured in 1979 and 1983. The control group consisted of 20 research workers who had no vibration exposure in the past and no symptoms in their hands. The measuring system for VPT gave repeatable results. The frequency of the most sensitive VPT of vibration exposed workers alternated between 63 and 125 Hz instead of 125 Hz of subjects without vibration exposure. The VPT of the pedestal grinders and forest workers with decreased hand grip force and with vibration-induced white finger were significantly higher than those of the controls. The VPTs of the forest workers decreased slightly and that of the grinders increased from 1979 to 1983. In spite of long vibration exposure in the past and continuing lower level vibration exposure, the increased VPT of forest workers does not seem to be permanent.

Postural stability in shooters

Ten competition shooters were tested during simulated race using the force platform technique to investigate the effect of training on postural stability. The shooters were tested at 30-min intervals during a race simulating actual race conditions. Sway velocity was calculated during 27-second periods. The postural stability was evaluated with and without competition clothing. The shooters had significantly better stability than untrained control subjects, when tested without supportive clothing. The competition clothing reduced the sway velocity further both in visual and nonvisual conditions. The Romberg quotient was higher in shooters than in normal controls, indicating that the shooters used to an increased amount proprioceptive and vestibular cues to stabilize their posture. The good postural stability of the shooters apparently results from assiduous training aimed to improve postural stability.

Extent and high frequency of a short conversion between the human A gamma and G gamma fetal globin genes

Southern blotting and DNA sequencing after polymerase chain reaction (PCR) amplification provide evidence for the frequent occurrence (in 7 out of 24 chromosomes) of a short conversion G gamma----A gamma in the 3' end of the human fetal A gamma globin gene. This short conversion is characterized by the presence, 3 nucleotides downstream from the termination codon of the A gamma gene, of the TCAC sequence that is normally present at the equivalent position at the 3' end of the G gamma gene; it is therefore identical to a conversion already described. Interestingly, we have found that this conversion is associated with the presence of the HindIII polymorphic restriction site in the A gamma IVS2, occupying an equivalent position in both the G gamma and A gamma genes. Our observations strengthen the hypothesis that the presence of the HindIII polymorphic restriction site in A gamma IVS2 and the presence of the sequence TCAC at the 3' end of the A gamma gene might be the result of a single conversion event.

Transmission of vibration from tool handle to wrist and to head

Transmission of vibration from the handle of the tool to the handarm system was investigated by measuring vibration in pairs from the source and from the wrist and head. The frequency response function was applied to describe the transmission properties. The measurements were taken at work places to evaluate the effect of different work-related factors on the transmission. Laboratory measurements were conducted to evaluate the effect of different grip forces and the use of protective gloves on the transmission. The field measurements comprised five different groups of workers whose exposure to vibration was evaluated and whose observed symptoms of vibration-induced white finger (VWF) was compared to the predicted ones based on the exposure data and on ISO 5349. The comparison of the prevalence data was in good agreement for the forest workers. The ISO method seemed to underestimate the genesis of VWF in workers who had to use high grip forces and for whom the vibration comprised high values of impulsiveness. The present results suggest that the frequency response function as independent of the input signal may thus describe factors important to the transmission of vibration.

Risk factors in the genesis of sensorineural hearing loss in Finnish forestry workers

A detailed analysis of risk factors for the development of sensorineural hearing loss (SNHL) was carried out in 199 forest workers. The hearing threshold of both ears at 4000 Hz was measured, and the effect of age, exposure to noise, blood pressure, presence of vibration induced white finger (VWF), tobacco smoking, plasma LDL-cholesterol concentration, and consumption of drugs were evaluated by multiple linear regression analysis. Aging was the major risk factor, followed by exposure to occupational noise and the presence of VWF. Plasma LDL-cholesterol concentration and the use of antihypertensive drugs also correlated significantly with SNHL. These main factors were able to explain about 28% of the SNHL variance. Additional factors in the analysis, including smoking, systolic and diastolic blood pressure, and consumption of salicylates did not significantly contribute to the genesis of SNHL.

Noise exposure during pregnancy and selected structural malformations in infants

The study tested the hypothesis of exposure to noise during pregnancy being teratogenic. It included 1,475 Finnish mothers who had given birth to a malformed child (orofacial cleft or structural defect of the central nervous system, skeleton, or heart and great vessels) and 1,475 reference mothers. A special interview soon after delivery yielded the primary information on exposure. Of the 783 mothers who reported noise exposure in the first trimester, 370 were case mothers and 413 were referents. Hygienic assessment indicated that 102 case mothers and 103 referents had been exposed in the first trimester to a sound level of around 80 dB LAeq(8 h) or higher, the overall odds ratio being 1.0 (95% confidence interval 0.7-1.3). Adjustment for potential confounders by logistic regression methods gave similar results. There was no obvious trend suggesting a hazard when different exposure categories were considered.

Hierarchy of different muscles in postural control

The effects of muscle spindle activation on different postural muscles were examined in eight volunteers, using a force platform technique. Small electrical vibrators were placed symmetrically over the muscles concerned and the effects of vibration frequencies of 20, 40, 60, 80 and 100 Hz were studied at a constant amplitude of 0.4 mm (peak-to-peak). Significant responses were observed in most muscles. The responses were observed (in maximum response order) from: the neck, triceps surae, gluteus, abdominal, hamstring, quadriceps, lumbar and tibialis anterior muscles. The response direction did not follow anatomical gonistic vis-à-vis antagonistic distribution of the muscles studied, indicating that it is the functional properties of the muscles that determine posture stabilization. The large inter-individual variability in responses, but the consistency in intra-individual muscle responses indicates that the subjects used afferent muscles to a varying extent in postural control. The vibration-induced activation of the muscles was presumably derived by activation of stretch-sensitive secondary endings of muscle spindles that control postural stability.

Expression of human G gamma globin genes carrying a T or a C at position -158 in COS and MEL cells

Increasing data strongly suggest that, in adults, the G gamma/A gamma globin chains ratio is genetically controlled by determinants linked in cis to the beta-globin gene cluster. The presence of the C----T substitution at position -158 5' to the G gamma globin gene in subjects displaying high G gamma/A gamma globin chains ratio led to the hypothesis that this substitution is involved in the determination of high G gamma globin gene expression. In order to test this hypothesis, we have compared the expression of two G gamma globin genes carrying a C or a T at position -158, upon transfection into a COS cell line or stable integration into a MEL cell line. Our results showed no significant effect of the nucleotide at position -158 on the level of human G gamma mRNA produced in these cells.

Impulse noise and hand-arm vibration in relation to sensory neural hearing loss

The present study was carried out to determine whether impulse noise and simultaneous exposure to noise and vibration can aggravate sensory neural hearing loss (SNHL) among forest (N = 199) and shipyard (N = 171) workers. The average level of exposure to noise outside the used earmuffs and the average exposure over time were nearly equal for the two groups. The impulsiveness of the noise and the average exposure level inside the earmuffs were measured with a miniature microphone. The hearing threshold of the workers was measured at 4 kHz and then estimated according to Robinson's model to compare the observed and expected hearing loss. The impulsiveness of the noise was greater both outside and inside the earmuffs in shipyard work than in forest work. The average SNHL was higher than predicted for the shipyard workers and about the same as predicted for the forest workers. The total exposure level inside the earmuffs was influenced by the total wearing time. The low frequencies of the chain-saw noise were not attenuated sufficiently by the earmuffs to protect the workers' hearing. The present study suggests that exposure to impulse noise increases the risk of SNHL, but that simultaneous exposure to hand-arm vibration and noise does not.

Genetic factors involved in human G gamma and A gamma globin gene expression

G gamma to A gamma globin ratios, haplotypes at the beta globin gene cluster and the C----T substitution at -158 5' to the G gamma globin gene were studied in three Algerian families that include SS or S-beta(0) thal patients. G gamma to A gamma ratios were found similar, within a family, in subjects displaying the same combination of chromosomes 11, the ratio observed for a given combination depending on the chromosome haplotypes. Our data can be explained by the existence of several alleles of a genetic factor closely linked to the beta globin gene cluster and involved in the determination of G gamma to A gamma globin ratio.

Forestry workers exposed to vibration: a neurological study

Neurological findings were examined in 186 forestry workers with a mean exposure to chain saw vibration of 16.6 hours. The prevalence of active vibration induced white fingers was 5%, parethaesias of the hands 53%, and muscle weakness 13%. Clinical polyneuropathy was observed in 16 forestry workers in the hands (7.5%) which did not correlate with alcohol consumption. Seventy nine forestry workers of the total population were selected for electromyographic examination. Generalised EMG based polyneuropathy in the hands was observed in only two of the 79 forestry workers (2.5%). The carpal tunnel syndrome was found in 20 of the 79 forestry workers (26%). Headache and vertigo were not linked with exposure to vibration in forestry and a significant part of the numbness reported may be due to the carpal tunnel syndrome. Sensorimotor polyneuropathy is rare among forestry workers. The rise in the vibration detection thresholds was linked to the carpal tunnel syndrome.

Evaluation of factors affecting sensory neural hearing loss

A detailed analysis of risk factors in the development of sensory-neural hearing loss (SNHL) was carried out in 199 forest workers. The mean hearing threshold of both ears at 4000 Hz was measured and the effect of age, exposure, blood pressure, presence of vibration induced white finger (VWF), tobacco smoking and plasma lipid concentrations on SNHL were evaluated by multiple linear regression analysis. A part of aging the major risk factors were presence of VWF, elevation of LDL-cholesterol level and usage of antihypertensive agents. Additional factors in the analysis, e.g. smoking and diastolic and systolic blood pressure did not significantly contribute to the genesis of SNHL.

Computerized posturography, a development of the measuring system

A computerized posturography system is composed of a custom made strain gauge force platform and it utilizes commercially available amplifiers. The body sway response signals are digitized for the calculation of the following parameters by a computer: average velocity of body sway, mean value for fore-aft and lateral body sway, and maximal amplitude of body sway. Calf muscles were exposed to vibration to disturb the postural control. The program contains appropriate filters to remove transient and quantification noise.

Human chronic myeloid leukemic cell line with positive Philadelphia chromosome exhibits megakaryocytic and erythroid characteristics

A cell line (LAMA-84) has been established from the blood of a patient with chronic myeloid leukemia in acute phase. LAMA-84 cells retained the patient's chromosome abnormalities, i.e., triplication of all chromosomes except chromosome 18, the presence of Philadelphia (Ph) chromosome in 4-5 copies, and the presence of chromosome markers. LAMA-84 cells have morphological features of undifferentiated blast cells, but analyses have indicated that they belong to the megakaryocytic lineage; platelet peroxidase (PPO) was found in 8.5% of cells; LAMA-84 cells reacted spontaneously with poly- and monoclonal antibodies against the platelet glycoproteins (GP) IIb, IIIa, and the GPIIb/IIIa complex, whose presence was confirmed by crossed immunoelectrophoresis. LAMA-84 cells lack the membrane characteristics of lymphoid and mature granulocytic cells but do, however, react with certain antibodies to immature myeloid cells. Furthermore, they are positive with an antiglycophorin antibody, and contain alpha- and gamma-globin mRNA, thus demonstrating erythroid marker expression. Thus LAMA-84 is a tripotent, megakaryocytic, erythroid, and granulocytic cell line. The megakaryocytic and erythroid markers were enhanced by the addition of DMSO, butyrate, TPA, and hemin. The LAMA-84 cell line represents an interesting tool for the study of megakaryocytic and erythroid differentiation and the mechanisms of neoplastic growth.

Sensory-neural hearing loss during combined noise and vibration exposure. An analysis of risk factors

A detailed analysis of risk factors for the development of sensory-neural hearing loss (SNHL) was carried out on 122 forest workers. These forest workers were selected from a larger group (n = 217) by restricting the age range to 30-55 years. The hearing threshold of the left ear at 4000 Hz was measured and the effect of age, exposure, systolic and diastolic blood pressure (DBP), presence of vibration-induced white finger (VWF), tobacco smoking and use of earmuffs were evaluated in multiple linear regression analysis. Robinson's nonlinear model was used to evaluate the rate of hearing loss. Aging was the major risk factor and it explained 15.4% of the variance of the SNHL. The presence of VWF was the second most important single risk factor and explained a further 5.2% of the SNHL. Elevation of DBP correlated significantly with SNHL and explained an additional 4.1% of the SNHL. These main factors were able to explain about 26% of the spread of SNHL. Additional factors in the analysis, e.g. smoking, systolic blood pressure, did not significantly contribute to the genesis of SNHL. When Robinson's model was applied to the SNHL data, on a group basis, we did not observe any exaggerated risk of hearing loss due to combination of noise and vibration. In combined exposure subjects with VWF as well as subjects with enhanced DBP will run a higher risk for SNHL.

The efficiency of earmuffs against impulse noise from firearms

Young men conscripted into the armed forces still run a risk of suffering hearing damage during their military service. This risk could be reduced by effective personal hearing protectors. The standard tests to determine the attenuation values of hearing protectors cannot be applied to high-intensity impulse noise from firearms, but the protectors should be evaluated under actual firing conditions. The attenuation values of the hearing protectors (earmuffs) most commonly used in the Finnish Army were tested for impulse noise from different weapons. The attenuation was found to be good for pistol shots, moderate for rifle shots and very poor for cannonfire. The tested earmuffs gave only minimal protection against low-frequency impulse energy.

Further evidence of a relation between noise-induced permanent threshold shift and vibration-induced digital vasospasms

The relation between noise-induced permanent threshold shift (NIPTS) and vibration-induced dysfunction in the digital circulation was examined in a longitudinal survey among forest workers. The survey was based on annual examinations done between 1972 and 1983. Thirty-two forest workers with digital vasospasms were compared with referents matched for age, exposure, and use of ear protectors. No significant differences between the groups were observed at 1,000 or 2,000 Hz. The forest workers with digital vasospasms had significantly greater NIPTS at 4,000 and 8,000 Hz than the symptom-free referents. During the follow-up period, the gap in NIPTS between the two groups did not increase. Vibration measurements from chain saws manufactured in different years indicated that chain saws manufactured after 1970 had a tenfold reduction in vibration, whereas the reduction in noise levels was only slight. The results suggest that vibration-induced activation of the autonomic nervous system, which is thought to elicit digital vasospasms, may also contribute to the development of NIPTS.

Impulsiveness of vibration as an additional factor in the hazards associated with hand-arm vibration

Impulsiveness is defined as the difference between peak and root-mean-square signals. As the difference varies in time, the cumulative distribution function has been used to describe the probability of achieving a certain value of impulsiveness. To make numerical comparison of different vibration signals possible, an impulse index has been selected from the cumulative distribution function. Symptoms of vibration-induced white finger were observed and compared to those expected on the basis of measurements taken according to guidelines of the International Organization for Standardization (ISO). Agreement was found for chain-saw vibration. In the case of pedestal grinding, the ISO draft underestimated the hazardous effects of vibration. Stone workers using pneumatic hammers were exposed to highly impulsive but asymmetrical vibration. The corresponding asymmetry was not, however, observed between the symptoms of the left and right hands, a finding which indicates that coupling between the tool and the hand is important for impulse vibration. The results suggest that the impulse character of vibration increases the risk of vibration-induced pathology. The analysis of high-impulse acceleration peaks obtained by the method presented in this study could provide additional data necessary to improve risk assessment.

Digital high-speed sampling of combined exposure to noise and vibration

The digital high-speed sampling technique was applied to simultaneous measurements of exposure to noise and vibration among workers who used hand-held power tools in a shipyard. The transducers were two accelerometers and two microphones which measured the transmission of vibration acceleration from the handle of the tool to the wrist and the attenuation of noise by the earmuffs. The measurements were taken by a microcomputer-controlled digital multichannel sampling unit. An analogue-digital converter was used with a 100-kHz scanner for multichannel signal acquisition in the 10 kHz bandwidth. The sound pressure was A-weighted, and the vibration acceleration was both unweighted and weighted according to the guidelines of the International Organization for Standardization. Impulsiveness was determined as the difference between the peak and root-mean-square levels. The noise exposure was 81 dB during grinding and 85 dB during hammering. The earmuffs provided protection against impulse noise at least when the impulses contained high frequencies. The transmission loss of vibration acceleration between the tool handle and wrist was 45 dB for grinding and 29 dB for hammering. The transmission of noise and vibration was affected by the frequency content and impulsiveness of the signals.

Hand-grip force in lumberjacks: two-year follow-up

Hand-grip force was measured in 63 professional lumberjacks in 1978 and again in 1980. Lumberjacks with vibration-induced white fingers (VWF) had lost 21% of their muscle force during the two years. Lumberjacks with no hand-arm symptoms had lost 5% of their muscle force in the same time period. Lumberjacks with subjectively diminished hand muscle force had a slight increase in muscle force during the follow-up time. These results suggest that long-term exposure to vibration causes a decrease in muscle force.

Cold provocation tests in the evaluation of vibration-induced white finger

Two types of cold provocation tests, a classical test with immersion of the hand in cold water and the evaluation of finger systolic blood pressure (FSBP) during local cooling, were administered to forest workers. Raynaud's phenomenon in the classical test correlated positively with the number of disabled phalanges, recovery time, and frequency of attacks. It did not correlate with the severity of paresthesia of the hands and arms. Repetition of the test enhanced the number of positive results. A significant reduction in the FSBP was observed in 22 and 25% of the subjects with inactive and active forms of vibration-induced white finger (VWF), respectively. In the same groups of subjects the classical cold provocation test yielded positive results in 7 and 25% of the subjects, respectively. A cold provocation test was found to produce a positive result even some years after the cessation of VWF attacks. The rather low severity of VWF among the examined subjects may explain the lack of positive test results. FSBP measurement was not superior to cold provocation by water immersion, but it is recommended because it is easier to standardize and more convenient for the test subject.

Finger peripheral resistance during local cold provocation in vasospastic disease

Finger systolic blood pressure (FSBP), finger arterial inflow (FAI), finger venous opening pressure (FVOP), and finger peripheral resistance (FPR) were evaluated in 56 workers exposed to chain-saw vibration. Twenty-one of the workers were free from vibration-induced white finger (VWF). In 17 subjects VWF had ceased; 12 of the subjects had active VWF; 6 subjects had Raynaud's disease. The subjects were examined in a supine position under thermoneutral conditions with strain-gauge plethysmography. Cold provocation of the finger caused a significant reduction in FSBP in the groups with Raynaud's disease and active VWF. The finger circulation of the subjects with active VWF and that of those with Raynaud's disease showed a significantly reduced FAI when compared with that of the symptom-free referents. Finger cooling produced a gradual reduction in the FVOP and a significantly increased FPR of the subjects with active VWF and in those with Raynaud's disease. FPR was already increased in the Raynaud's disease group at the beginning of the test, whereas it increased in the VWF group as the temperature fell. The results suggest that in Raynaud's disease the fault is in the level of activity of the sympathetic outflow and in VWF it is peripheral mechanisms controlling the vessel tone.

Vibration syndrome among Finnish forest workers, a follow-up from 1972 to 1983

A longitudinal survey on the prevalence of vibration syndrome among professional forest workers was conducted from 1972 (118 workers) to 1983 (206 workers). The prevalence of vibration-induced white finger (VWF) was 40% among the workers in 1972; it gradually declined to 5% in 1983. Three new workers developed VWF symptoms during the follow-up period. They had only used saws equipped with antivibration handles. The prevalence of VWF has decreased mainly due to the reduction of chain-saw vibration. The prevalence of paresthesias of the hands and arms declined from 78% in 1972 to 37% in 1976, and then increased to 51% in 1983. The recent increase was thought to be due to static muscle load and the ageing of the workers. No correlation was found between the severity of VWF and peripheral nerve symptoms. No significant changes in muscle fatigue occurred during the follow-up period; it was present in about 10-15% of the workers. The forest workers subjectively assessed musculoskeletal load and strain as being more harmful than the symptoms of vibration syndrome. The preventive measures aimed at reducing chain-saw vibration, implemented since 1970, have been beneficial and explain the decreased prevalence of VWF.

Vasomotor oscillation in vibration-induced white finger

Vasomotor oscillation at different ambient temperatures, with and without anesthesia of the finger nerves, was studied in six persons with vibration-induced white finger (VWF) and in 10 referents. The power spectral density (PSD) of the Fourier transform of the laser-Doppler flowmeter signal from the finger pad vessels was analyzed. In both groups, the PSD of the vasomotor oscillation in the frequency range of 0.05-0.25 Hz was more pronounced in a cold than in a hot environment. Without finger nerve anesthesia, the oscillations of the referents were significantly greater (p less than 0.01) than those of the VWF subjects (PSD -34.4 dB and -41.6 dB, respectively). With anesthesia of the finger vasomotor nerves, the PSD was reduced in both groups. In the anesthetized finger there was no statistically significant group difference. Thus the myogenic component of the vasomotor activity was the same in the referents as in the VWF subjects. The results show that the autonomic neural influence on vasomotor oscillation in skin of the finger pad is weaker in persons with VWF. This weakness may be a sign of peripheral neuropathy, which may lead to a denervation syndrome causing hypersensitivity of the adrenoceptors to cold.

Circulatory reaction to heat and cold in vibration-induced white finger with and without sympathetic blockade--an experimental study

Central nervous, sympathetic mechanisms and local factors influencing the vascular response to cold in the finger skin were studied with plethysmographic and laser-Doppler methods in a chamber with controlled temperatures from 45 to about 5 degrees C, with and without sympathetic finger blockade. Blood flow and pressure were assessed after finger occlusion, together with finger heating and cooling, in workers with vibration-induced white finger (VWF) and in healthy persons not exposed to cold or vibration. Finger blood flow at vasodilatation, as measured by finger arterial inflow (FAI) after occlusion was smaller in the VWF group than in the reference subjects both with and without anesthesia, and capillary flux in the anesthetized finger tended to be smaller. At vasoconstriction, with or without anesthesia, the VWF subjects had lower FAI values than the referents. The studied flow and pressure variables differed considerably between the groups. The peripheral resistance of the VWF subjects was higher than that of the referents. This difference was the most pronounced after finger anesthesia. A possible pathogenetic mechanism in VWF is an increase in peripheral resistance due to a local defect in the vessels, with subsequent reduction in flow and intramural pressure.

Pathophysiological and hygienic aspects of hand-arm vibration

A review of current knowledge on the pathophysiological and hygienic aspects of the hand-arm vibration syndrome is given. Hemodynamic measurements indicate that the primary factor in vibration-induced white finger is an increase in the peripheral resistance of finger circulation that is present after local and general cooling. The reason for this increase is not known, but it is postulated that an excessive affinity of vasoactive substances for the efferent receptors exists, this affinity being potentiated during local cooling of the digits. So far, the hygienic rating of hazardous vibration in individual work phases is of limited value in diagnosing possible cases, but this rating does provide guidelines for general risk assessment. A consideration of several factors, eg, intermittency of the work, duration of daily exposure, impact of vibration, individual physiological responses, climate, etc, might improve the accuracy of the rating, but the influence of these factors on the development of the vibration syndrome is still poorly understood. Of various preventive measures, only those that significantly reduce vibration will be beneficial in the long run.

Alpha-thalassemia due to the deletion of nucleotides -2 and -3 preceding the AUG initiation codon affects translation efficiency both in vitro and in vivo

We previously hypothesized that a 2 nucleotide deletion, causing a A-greater than C change at position -3 preceding the ATG initiation codon of alpha globin gene, reduced translation efficiency of alpha globin mRNA and was responsible for a form of alpha + thalassemia displayed by an Algerian patient. We presently show that this deletion leads to a 30-45% reduction in translation efficiency of synthetic alpha globin mRNA in rabbit reticulocyte lysate. In other experiments, we constructed alpha/G gamma hybrid globin genes in which the 3' end of normal or mutated alpha globin genes downstream to the ATG initiation codon was substituted by the 3' part of a G gamma globin gene. COS cells transfected with either of these 2 hybrid genes were shown to synthesize a similar amount of alpha/G gamma hybrid mRNAs but 50% less G gamma globin when transfected with the alpha/G gamma hybrid gene carrying the deletion. These results definitively establish that the 2 nucleotide deletion reduces translation efficiency by 30-50%. This contrasts with the 93% reduction induced by a similar A-greater than C change at position -3 in the different nucleotide context preceding the ATG codon of the rat preproinsulin gene.

Combined effects of noise, vibration and visual field stimulation on electrical brain activity and optomotor responses

Eye movements and electroencephalographs (EEG) were recorded in intact rabbits during an optokinetic test. The animals were exposed to pure tone noise (85 dB at 4000 Hz), impulse noise (159 dB), and vibration directed at the abdomen (amplitude 0.9 mm at frequencies of 40, 80, and 120 Hz). The velocity of optokinetic nystagmus (OKN) significantly increased with these stimuli. The increase seen with vibration was greater than the noise-induced increase. The response was strongest when noise and vibration were combined. The increase in OKN induced by vibration was successive and dependent on frequency. The increase was weakest during exposure to vibration at 40 Hz and strongest at 120 Hz. EEGs of the dorsal hippocampus, amygdaloid complex, midbrain reticular formation, and frontal motor cortex were all activated during noise and vibration exposure, but activation of the hippocampal EEG was the most closely related to the increase in OKN. Combination of the different stimuli indicated that their interaction could not be predicted on the basis of responses to single stimuli, and, in most cases, the result was indifference due to the high alerting effect of vibration alone. The findings can be related to the non-specific dizziness found in aerospace workers exposed to excessive noise and vibration.

Vibration-induced neuropathy among forestry workers

The neurological findings of 217 forestry workers were evaluated during a compulsory annual health examination. Vibration detection thresholds were determined for the left hand and foot. The handgrip forces were measured for both hands. A reduction in the vibration detection threshold or handgrip force was not associated with clinical neuropathy. Polyneuropathy was found in 4% of the lumberjacks whereas neuropathy restricted to the arms was found in 7.5% of the lumberjacks. The neuropathic findings were not linked with alcohol consumption but were associated with a history of numbness in the hands and diminished muscle force. The findings support the concept that local vibration can cause neuropathy in the arms, but the mechanism of vibration-induced neuropathy still remains uncertain.

High impulse acceleration levels in hand-held vibratory tools. An additional factor in the hazards associated with the hand-arm vibration syndrome

The measurement of the root-mean-square (rms) acceleration of vibration does does not take into consideration the short high peak values of the vibratory signal, which may be a hazard contributing to the development of vibration-induced disease. A method for evaluating the impulse character of vibratory signals is given, and impulsiveness is defined as the difference between the peak and rms signals. Measurements were taken during pedestal grinding, during chain sawing with three different generations of saws, and during chiseling with a pneumatic hammer. The measurements comprised (i) analyses done according to the International Organization for Standardization (ISO) draft, (ii) an evaluation of impulsiveness, and (iii) an analysis of the short-time history transient. The risk of vibration-induced white fingers was estimated by the ISO method, and the results were compared with those observed. It was found that the analysis of impulsiveness provided additional data and partly explained the observed symptoms of vibration-induced white fingers. The parameters for the impulsiveness of the vibration signal agreed with the short-time history analysis.

Role of the gonad cytoplasmic core during oogenesis of the nematode Caenorhabditis elegans

In order to elucidate the function of the cytoplasmic core (or rachis: a structure specific of the nematode gonads), we have carried out a cytological study of this structure in the free-living nematode Caenorhabditis elegans, in wild-type and in several mutant strains showing an abnormal gametogenesis. We also performed an ultrastructural radioautographic study of RNA synthesis during oogenesis in order to examine the part played by the rachis in the transport of nutritive substances. Our results evidence for the first time a metabolite transfer from the germ cells to the cytoplasmic core and lead us to assign to the core a trophic role linked to oogenesis. A statistical analysis of silver grain distribution has led us to conclude that there is no accumulation of RNA labelling in any part of the cytoplasmic core. In addition, our studies performed on sterile mutant strains suggest that the cytoplasmic core may have a specific function in oogenesis determination.

Vibration syndrome and vibration in pedestal grinding

At one Finnish foundry all the workers had typical symptoms of vibration induced white finger (VWF) after they began using a new type of pedestal grinding machine. The objectives of this study were to establish the severity of the symptoms and the difference in vibration exposure between the new and the old machines. Vibration detection thresholds and grip forces were measured, as well as the vibration in the casting and in the wrist simultaneously. The mean latency for VWF among the grinders was 10.3 months after the change of pedestal grinding machines. All the grinders had numbness in their hands. The vibration detection threshold was significantly higher for the grinders than for their referents. At the same circle speed, the new wheels caused vibration levels up to 12 dB more than the old wheels. The circle speed had a slight influence on the vibration. The vibration levels of light (0.5 kg) casting were up to 25 dB higher than the heavy (5 kg) casting. The use of a pneumatic pressing device decreased the vibration levels in the wrist by 5-10 dB. The increase in vibration, which occurred when the new wheels were taken into use, was too small to explain such a dramatic outbreak of VWF. This led to the conclusion that some other feature such as the impulse character of the vibration also contributed to the effects of vibration.

Frequency of rheumatic diseases in patients with acute anterior uveitis

The frequency of associated rheumatic diseases was studied in 271 patients with acute anterior uveitis (AAU). In a retrospective examination of 154 patients with AUU (mean follow-up period of 6 years) associated rheumatic symptoms were observed in 64 (41.6%). Forty-one patients (26.6%) had ankylosing spondylitis and 39 (25.3%) manifestations of Reiter's disease. Radiographic sacro-iliitis was seen in 35 (34%) of 103 consecutive x-ray examined patients with AAU. Furthermore, in another series of 38 patients, who all, in addition to having AAU, also complained of low back pain or had manifestations of Reiter's disease, 23 (60.5%) had radiographic sacro-iliitis. Classical ankylosing spondylitis was more frequent in men with AAU whereas milder forms of the disease occurred more equally in both sexes. HLA-B27 occurred in 35 (87.5%) of 40 HLA-typed patients with AAU. Associated rheumatic diseases occurred in 18 (51.4%) of the 35 HLA-B27 positive patients but in none of the HLA-B27 negative patients. The results support the hypothesis that a pleiotropic HLA-B27 associated gene may determine the susceptibility to AAU, sacro-iliitis, ankylosing spondylitis, and Reiter's disease.

Hand-arm vibration in the aetiology of hearing loss in lumberjacks

A longitudinal study of hearing loss was conducted among a group of lumberjacks in the years 1972 and 1974--8. The number of subjects increased from 72 in 1972 to 203 in 1978. They were classified according to (1) a history of vibration-induced white finger (VWF), (2) age, (3) duration of exposure, an (4) duration of ear muff usage. The hearing level at 4000 Hz was used to indicate the noise-induced permanent threshold shift (NIPTS). The lumberjacks were exposed, at their present pace of work, to noise, Leq values 96-103 dB(A), and to the vibration of a chain saw (linear acceleration 30-70 ms-2). The chain saws of the early 1960s were more hazardous, with the average noise level of 111 dB(A) and a variation acceleration of 60-180 ms-2. When classified on the basis of age, the lumberjacks with VWF had about a 10 dB greater NIPTS than subjects without VWF. NIPTS increased with the duration of exposure to chain saw noise, but with equal noise exposure the NIPTS was about 10 dB greater in lumberjacks with VWF than without VWF. With the same duration of ear protection the lumberjacks with VWF consistently had about a 10 dB greater NIPTS than those without VWF. The differences in NIPTS were statistically significant. The possible reason for more advanced NIPTS in subjects with VWF is that vibration might operate in both of these disorders through a common mechanism--that is, producing a vasoconstriction in both cochlear and digital blood vessels as a result of sympathetic nervous system activity.

Vibration-induced decrease in the muscle force in lumberjacks

Isometric maximal hand grip force was measured with a strain gauge dynamometer in 91 lumberjacks and 31 controls during a 2-min compression-relaxation task. Measurements were carried out on both hands with and without simultaneous vibration exposure. The muscle forces of older subjects were smaller than those of younger men, independent of occupational vibration exposure. The fatigue curves of lumberjacks and control subjects had the same shape. During vibration exposure in the test, the forces diminished in the left hand significantly in the lumberjacks but not in the control subjects. The force level of fatigue curves of the lumberjacks with a history of diminished grip force was lower and decreased more during vibration exposure than in the lumberjacks with a history of normal grip force. The reduction in the hand grip force during vibration exposure in the lumberjacks seemed to be linked to lesions in the peripheral nerves and to activation of a tonic vibration reflex, but probably not to circulation disturbances. The fatigue mechanism seemed to be the same in lumberjacks and control subjects.

Hand grip forces during chain saw operation and vibration white finger in lumberjacks

The hand grip forces at the front and rear handles of a chain saw were measured during work, in 89 professional lumberjacks. The symptoms caused by vibration to the upper limbs were compared with the hand grip force (HGF) during work. To allow better comparison between subjects we used the ratio of hand grip force (HGF) to the maximal voluntary compression force (MVC), HGF/MVC expressed as a percentage. The mean HGF during sawing varied from 5 to 12 N in all subjects. The variation in HGF was greater at the front handle than at the rear handle, during sawing. The lumberjacks who had vibration-induced white fingers (VWF), had a higher HGF/MVC in both hands than the lumberjacks without VWF. Those lumberjacks affected by VWF used over 12% of their MVC at work. Subjects without HGF/MVC ratio. The lumberjacks with and without numbness in their hands had equal HGF/MVC ratios.

[Autoradiographic localization of RNA synthesis in vitro during oogenesis in Parascaris equorum]

Technical elaboration of in vitro incubation of Parascaris equorum gonads with 3H-Uridine has permitted, for the first time, the study of RNA synthesis during oogenesis along the whole gonadic tube. In germ cells, oocytes in diakinesis (oviduct) and in division of maturation (uterus) show no label. On the contrary oogonia and growing oocytes in ovary are labelled. RNA synthesis is always detected in all parietal cells but is more active in oviduct and uterus where the gonadic wall is particularly developed.