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Biomedical subjects

H Ising

Publications and source records attributed to H Ising.

At least 19 recordsLinked to original sources
PubMed1997

Subjective work noise: a major risk factor in myocardial infarction.

The relationship between subjective work noise exposure and the risk of myocardial infarction (MI) was assessed in a population based case-control study. 395 MI patients (31-65 years) were compared to 2148 controls from a random population sample with the same agelsex distribution. The relative risk (RR) for MI-adjusted for control variables (smoking, age, social status, etc.)-was found to increase significantly and steadily with noise category. Subjective work noise exposure was the second greatest risk factor for MI after smoking. Possible bias due to overreporting of subjective noise exposure is discussed. Interdisciplinary studies on the relationship between cardiovascular diseases and work-related stressors including subjective and objective noise assessment are needed to quantify the risk of MI due to work noise.

Adult↗
PubMed1996

Dietary magnesium does not predict ischaemic heart disease in the Caerphilly cohort.

OBJECTIVES: To examine the association between dietary magnesium intake and the risk of an ischaemic heart disease (IHD) event. DESIGN: Estimates were made of dietary magnesium intake from food frequency records, supplemented by seven-day weighted intake records. The subsequent incidence of ischaemic heart disease events was recorded. The relative odds of an IHD event was related to base-line magnesium intake. SETTING: Data on dietary magnesium intakes are available for 2172 men aged 45-59 y in the Caerphilly cohort. These have now been followed for ten years since base-line dietary data were collected, and during this time a total of 269 IHD events occurred. Of these, 96 were acute deaths (ICD 410) and 136 were non-fatal myocardial infarctions. RESULTS: The overall mean dietary intake of magnesium was estimated to be 279 (s.d. 83) mg/day. The daily intake of those men who later experienced any IHD event was 266 (s.d. 84) mg/day and this differs from that in men who experienced no IHD event during this time (281 mg, P < 0.05). Men who suffered an acute IHD death had even lower intakes (mean 253 (s.d. 79); P < 0.005). Age, smoking habit, energy intake and alcohol consumption are all significantly associated with both Mg intake and IHD risk and are therefore possible confounding factors. Standardisation for these factors reduces the difference for all IHD events to 2.9 (s.e.m. 3.6) mg Mg/day, P > 0.05, and to 0.9 (s.e.m. 5.8) mg for acute IHD death. Similarly, when the men are ranked into fifths by their daily Mg intake, 70 of the 434 men with the lowest intakes went on to experience an IHD event, compared with only 41 of the 434 men with the highest Mg intakes. The relative odds (RO) for the fifth of men with the lowest intakes, compared with the fifth with the highest intakes, is 1.86 (P < 0.005), but standardisation for the confounding factors leads again to a loss of significance (RO 1.52, P > 0.05). CONCLUSION: Although trends in the data are suggestive, data from the Caerphilly cohort give no certain evidence that dietary magnesium intake is independently predictive of ischaemic heart disease in the population studied.

Alcohol Drinking↗
PubMed1995

Measurement of free magnesium in blood, serum and plasma with an ion-sensitive electrode.

The fraction of total magnesium bound to protein and other substances depends upon the pH. pH-dependency of ionized free magnesium (iMg2+) in serum is expressed by the Siggaard-Andersen equation: iMg2+ (pH) = iMg2+ (7.4) x 10x(7.4 - pH). During preparation of serum or plasma, considerable pH changes occur which have to be corrected on the basis of the above mentioned equation. For pH correction of iMg2+, x < 0.1 has so far been used. However, this is correct only for new Mg(2+)-sensitive electrodes. During the lifetime of Mg2+ electrodes used in the "Microlyte Magnesium" (Kone Instruments, Finland) x increases and x = 0.2 was found to be a suitable approximation for most of the lifetime. By instantaneous iMg2+ measurements in whole blood samples pH changes and the uncertainty of x can be avoided. Dilution of blood by intravenous infusions decreases x nearly proportionally to the decrease of protein concentration in blood. Various methodological influences such as temperature and delay time before centrifugation, storage of serum and venous occlusion were studied. The circadian rhythm of iMg2+ was found to be considerably more pronounced than that of total Mg and was negatively correlated to changes of free fatty acids. To avoid variations of iMg2+ due to circadian changes, blood collection should be carried out between 6 and 10 a.m. The normal range of iMg2+ in blood of 179 healthy subjects was found to be between 0.46 and 0.60 mmol/l and the quotient of free and total Mg between 0.59 and 0.71. The accuracy of "Microlyte Magnesium" (Kone Instruments, Finland) is sufficient in a wide range of iMg2+.

Blood Specimen Collection↗
PubMed1995

Changes of ionized magnesium and free fatty acids in serum after acute myocardial infarction.

The most feared early complications after an acute myocardial infarction are ventricular arrhythmias. These may be initiated by changed concentrations of catecholamines and electrolytes. The present study shows a reduction of total serum magnesium after acute myocardial infarction which is normalized within a few days. Further, it could be shown that a more significant decrease of ionized Mg2+ (iMg2+) takes place at the day of acute myocardial infarction in the total group of myocardial infarction patients (n = 36). A closer investigation reveals that iMg2+ was considerably decreased in one third of the patients, whereas two thirds showed minor changes of iMg2+ in both directions. The pronounced decrease of iMg2+ in the first sub-group can be explained by the time course of free fatty acids in serum. On the day of the myocardial infarction free fatty acids in serum were increased. This is probably caused by beta-adrenergic-induced lipolysis due to catecholamines released by the stressful situation of an acute myocardial infarction. The increased free fatty acids in serum bind Mg2+, thus reducing iMg2+. As long as a beneficial effect of a general Mg infusion in all acute myocardial infarction patients is controversial, iMg2+ should be measured and Mg infusion therapy should be applied only in patients with low iMg2+.

Adult↗
PubMed1995

[Empirical studies of music listening habits of adolescents. Optimizing sound threshold limits for cassette players and discoteques].

The music habits of 569 pre-teens and teenagers, between 10 and 17 years of age, were examined and exposure to music from portable music players was compared to that in discotheques. Using a questionnaire we determined the length of time spent listening to portable music players and the frequency of disco visits. The individual level of the music heard through portable music players was measured as a free-field corrected short term mean level. The total music exposure (related to 40 hours per week) was calculated from the data and different assumed disco sound levels. We estimated the risk of ear damage according to ISO 1999 standards on the basis of the total music exposure, whereby the mean disco level was varied as a parameter in the range of 95 to 110 dB(A). Taking only the portable music players into account, one can expect that even after 5 years of music, approximately 5% of the total group would have a hearing loss of 20 dB. This percentage clearly rises when additional exposure is given in discotheques having music levels above 100 dB(A). We suggest therefore that for safety reasons the following sound levels should be observed: 90 dB(A) for portable music players and 95 dB(A) for discos. Through adherence to these levels we would expect that 1% of the young people in our study would have a hearing loss > 10 dB, whereas momentary exposure would result in a hearing loss > 10 dB of 10-20%. Therefore we believe that sound level limitations should be enacted immediately for portable music players and in discotheques.

Adolescent↗
PubMed1995

[Sensorineural hearing loss in children starting school. Results of a representative hearing screening study].

Audiograms in the 0.5-6 kHz frequency range were taken, using improved audiometric screening methods, in 2032 children, 6-7 years old, who were undergoing their pre-school medical examinations. In 151 children (7.4%), the threshold for hearing was above 20 dB for at least one frequency. Of these, 82 children (4% of the overall sample) had a hearing impairment defined as a difference of > or = 10 dB between at least one frequency (3, 4 or 6 kHz) and the mean value from 1+2 kHz. This was evaluated as a sensorineural hearing loss. Unilateral losses (lateral difference > or = 10 dB) were more common than bilateral losses (2.5% vs 1.6% of the overall sample). These unilateral hearing losses in the high-frequency range are essentially regarded as the result of playing with impulse-noise producing toys, such as toy guns with caps.

Audiometry, Pure-Tone↗
PubMed1994

Comparative findings on serum IMg2+ of normal and diseased human subjects with the NOVA and KONE ISE's for Mg2+.

It is clear now that although different ionophores for ionized Mg (IMg2+) have been designed by several groups, each of these has a distinctly different KMgCa. In view of this, it is important to determine whether each of these ion selective electrodes (ISE's) yield identical results for IMg2+ in sera from healthy and diseased humans. Using such an approach, we determined, in a blinded-and random manner, IMg2+ with both the NOVA and KONE ISE's for IMg2+ in two independent laboratories. No significant differences were found either for sera from healthy human volunteers or diseased patients. We did, however, note several interesting findings: 1. randomly, selected hospitalized patients exhibit a much higher incidence of abnormalities for IMg2+ (57-71%) than that noted previously for total Mg (TMg) measurements; and 2. coronary heart disease, rectal cancer and multiple sclerosis patients exhibit extracellular deficits in ionized free Mg.

Aged↗
PubMed1994

[Risk of hearing loss caused by listening to music with head phones].

Sound levels of music played from mini-cassette players via headphones were measured in a nonrepresentative group of 681 pupils whose ages were between 10 to 19 years. Each pupil completed a questionnaire giving the total time spent listening to music each day. The pupils set the music levels (free field corrected short time Leq) between 60 dB(A) and 110 dB(A). In the age group from 12-16 years, 10% chose 110 dB(A). Nearly 50% of the total group usually listened to music less than one hour per day, and just less than 10% listened for four or more hours. The energy equivalent of continuous sound pressure level for an exposure time of 8 h per day was for 55% Leq 8 h < 66 dB(A) and for 7% Leq 8 h > 95 dB(A) while 4% had an Leq 8 h > 105 dB(A). Estimation of the expected hearing losses (HL) were based on ISO 1999: about 10% of the total group were predicted to have a HL > 10 dB at 4 kHz after 5 years. After listening to sound in this manner 0.3% were expected to develop hearing losses at age 25 years that would be severe enough to substantially impair speech intelligibility.

Adolescent↗
PubMed1993

Traffic noise as a risk factor for myocardial infarction.

The hypothesis that road traffic noise causes ischaemic heart disease (IHD) was tested in several epidemiological studies in middle-aged men. The studies carried out in Caerphilly (Wales) and Bristol-Speedwell (England) suggested the daytime (6-22 h) outdoor traffic noise level category 65-70 dB(A) as a threshold for noise effects detectable. Based on risk factors, a relative risk greater than 1 was calculated for the incidence of major IHD (RR = 1.1) in both samples for the subjects in this highest noise category, those in the quietest (51-56 dB(A)) serving as a reference using multiple models. Also the prevalence of myocardial infarction (RR = 1.2 and 1.1), ECG ischaemia (RR = 1.2 and 1.4) and any IHD disease (RR = 1.2 and 1.2) showed relative risks slightly greater than 1 in this noise group. In contradiction, the observed incidence of major IHD showed relative risks below 1 in both samples in this traffic noise group. The case-control studies carried out in Berlin revealed relative risks above 1 on the incidence (RR = 1.3 and 1.2) and the prevalence (RR = 1.2) of myocardial infarction at outdoor traffic noise levels in the range of 71-80 dB(A) serving the men in the category below 61 dB(A) as a reference. None of the findings was statistically significant. The relevance of the results is discussed.

Adult↗
PubMed1993

The influence of military low-altitude flight noise on the inner ear of the guinea pig. Part I: Hearing threshold measurements.

The auditory thresholds of about 60 anaesthetized guinea pigs were determined at 3 or 4 frequencies between 2 and 20 kHz using the acoustically evoked brain stem potentials. The animals were then exposed to electro-acoustically reproduced MLAF noise with peak levels between 120 and 130 dB(A). The exposure occurred either once or else four times within either 3 or 60 minutes. The level of noise increased at 7.5 and 75 dB/s (slow and fast increase). TTS was then determined. PTS was measured one week later. In over half the animals, exposure to rapidly increasing noise level with a peak of 126 dB(A) induced PTS > or = 30 dB for at least one frequency. Exposure to a slowly increasing noise level with the same peak provoked significantly smaller PTS. 4 exposures to a rapidly rising noise level within 3 minutes induced significantly smaller PTS than the same dosage within 60 minutes. Only in the latter case was PTS greater than TTS.

Aerospace Medicine↗
PubMed1993

The influence of military low-altitude flight noise on the inner ear of the guinea pig. Part II: Scanning electron micrographs.

Guinea pigs were exposed once to MLAF noise (126 dB(A), 75 dB/s) and 12 cochleae were prepared for scanning electron microscopy 2 to 3 weeks after exposure. Qualitative analysis of the cilia of the outer hair cells revealed the types of damage already described in literature. The spatial distribution of cilia damage, however, differed essentially from the well known pattern: the damage was more or less pancochlear, beginning in the basal turn and increasing in frequency and severeness of damage till the end of the third turn. The most severe damage was visible in the outer row of the outer hair cells. This special pattern of cilia damage indicates that MLAF noise causes a different type of damage than the types described in literature. More studies are needed.

Aerospace Medicine↗