Relationship between Occupational Electromagnetic Field Exposure and Leukemia: A Meta-Analysis / 예방의학회지

OBJECTIVES: This study uses meta-analysis methodology to examine the statistical consistency and importance of random variation among results of epidemiologic studies of occupational electromagnetic field exposure and leukemia. METHODS: Studies for this meta-analysis were identified from previous reviews and by asking researcher active in this field for recommendations. Overall, 27 studies of occupational electromagnetic field exposures and leukemia were reviewed. A variety of meta-analysis statistical methods have been used to assess combined effects, to identify heterogeneity, and to provide a single summary risk estimate based on a set of simiar epidemiologic studies. In this study, classification of exposure metircs on occupational epidemiologic studies are reported for (1) job classification (20 individual studies); (2) leukemia subtypes (13 individual studies); and (3) country (27 individual studies). RESULTS: Results of this study, an inverse-variance weighted pooling of all the data leads to a small but significant elevation in risk of 11% (OR=1.11, 95% CI : 1.06~1.16) among 27 occupational epidemiologic studies. Publication bias was assessed by the 'fail-safe n' that may be not influence for all combined results exception a few categories, ie, "power station operators" and "electric utility workers" by job classification on occupational study. And all combined odds ratio results were similar for fixed-effects models and random-effects models, with slightly higher risk estimates for the random-effects model in situations where there was significant heterogeneity, ie, Q-statistic significant (p<.05). CONCLUSIONS: We found a small elevation in risk of leukemia, but the ubiquitous nature of exposure to electromagnetic fields from workplace makes even a weak association a public health issue of substantial power to influence the present overall conclusion about relationship between electromagnetic fields exposure and leukemia.

A Case of Cerebellar Hemorrhage Associated with Hyperhomocysteinemia

Hyperhomocysteinemia has recently been identified as an important risk factor for atherosclerotic vascular disease. Genetic aberrations in methylenetetrahydrofolate reductase (MTHFR) may account for reduced enzyme activity and elevated plasma homocysteine level. A recent report revealed that a common mutation (677C to T; Alanine to Valine) in the MTHFR gene was associated with decreased specific MTHFR activity in the homozygous state (Val/Val). A case was presented of a woman who had a cerebellar hemorrhage at age 38. It was discovered that she had a diffuse narrow-ing of the left sigmoid sinus and jugular bulb. Well developed cortical vein collateralization suggested a partial recanal-ization after occlusion of sigmoid sinus. There was a severe focal stenosis in the left proximal carotid artery. Widely accepted risk factors for atherosclerotic disease including hypertension, diabetes, hypercholesterolemia, tobacco use and so on were not found. After an extensive evaluation, she was found to have a Val/Val homozygous state of the MTHFR gene as the cause of hyperhomocysteinemia.

Ictal Features Differentiating Mesial from Neocortical Temporal Lobe Epilepsies

BACKGROUND: The differentiation of mesial temporal lobe epilepsy (MTLE) from neocortical temporal lobe epilepsy (NTLE) is important in surgical planning of temporal lobe epilepsy (TLE). We tried to find clinical semiology separating one from the other. METHODS: We reviewed 136 seizures of 28 patients who had epilepsy surgery and good clinical outcome (Engel class I or II). We compared the following clinical features between MTLE and NTLE; the history of febrile convulsion, staring, automatism, head version, contralateral dystonic (CLD) and tonic (CLT) posturing, secondarily generalized tonic-clonic seizure (SGTC) frequency, the duration of partial seizures (excluding SGTC part) and time to SGTC and the type of aura (abdominl aura, vertiginous aura, visual aura, gustatory aura, and psychic aura etc.). RESULTS: Eighteen men and ten women were included. Mean age was 29.1+ 8.8 years (11-45). Abdominal aura (p = 0.04), oroalimentary (p < 0.01) and gestural automatism (p < 0.01), CLD (p < 0.01), and CLT posturing (p < 0.01) were seen significantly more often in MTLE and the duration of partial seizure (excluding SGTC) (p < 0.01) was longer in MTLE than NTLE. In NTLE, head version (p < 0.01) and SGTC (p < 0.01) occurred more frequently and the evolution time to SGTC (p = 0.04) was shorter. Duration of automatism and staring and occurrence of unilateral blinking were not different between two groups. CONCLUSION: Abdominal aura, oroalimentary and gestural automatism, CLD and CLT posturing, longer partial seizure duration were more suggesting MTLE, while rapid generalization, frequent SGTC and head version were seen more often in NTLE.

Cut-off Value of Wada Memory Score in Verbal and Visual Memory Domain

BACKGROUND: The cut-off value which determine pass or fail in Wada memory test has not been thoroughly studied, especially in regard to modality-specific memory domains. To investigate the optimal cut-off value, we tried to know what value is appropriate to forecast good postoperative memory outcome in verbal and visual memory domains. METHODS: Eighteen temporal lobe epilepsy patients underwent preoperative Wada test and pre- and postoperative neuropsychological evaluation. Corrected Wada memory score (cWMS) was calculated by ipsilateral Wada retention score divided by pre-Wada score. As a measure of postoperative memory outcome, neuropsycholgical asymmetry index (NPAI) was defined as [(postoperative memory score ? Preoperative memory score) / their mean] and analyzed in verbal and visual memory domains respectively. We made six arbitrary cut-off cWMS values (40, 50, 60, 70, 80, and 90%) and dichotomized the patients into pass or fail group at each arbitrary cut-off value. Verbal and visual NPAIs were compared statistically between two groups. RESULTS: Verbal NPAIs were significantly different between pass and fail groups at 80% cut-off value (p=0.044). Visual NPAIs were significantly different between two groups at 50% (p=0.043) and 60% (p=0.003) cut-off values. CONCLUSIONS: Higher cut-off values may be better for differentiating good and poor postoperative memory outcomes in verbal memory domain, and, in contrast, lower cut-off values may be better in visual memory domain. The verbal and visual memory in Wada test should be analyzed with different cut-off values.

Effect of Mannitol on Serum Osmolality and on Water and Electrolytes Excretion

The effect of mannitol on serum osmolality(Sosm) was studied in 13 patients with increased intracranial pressure(Group I ) and 14 normal men(GroupII ). All of the Patients in Gtoup I were given 0.5 g/kg dose of mannitol radipidly and blood samples for Sosm were taken at 30 rninutes intetvals for the first one hour and at hourly intervals for the next 5 hours after mannitol infusion. Seven of Group II(Iia) received 0.5 g /kg dose of mannitol and the other 7 ( II b) received 1.0 g / kg, Blood samples for Sosm and electrolytes were taken at the same intervals for the same duration as in Group I expept for additionai blood samples every 5 rninutes during the first 30 minutes. In Group I there was no significant rise in Sosm even 30 minutes after mannitol infusion. In Group Iia and Iib, a maximum increase of 6 mOsm / kg, 14 mOsm / kg was observed at about 5 minutes, 25 minutes after mannitol infusion respectiveiy, which returned to baseline in about 1 hour and 4 hours respectively. The 1.0g /kg dose of mannitol produced a significant and relatively persistent increase in Sosm probably enough to reduce the ICP, but at dose of 0.5 g / kg there was minimal increase in Sosm; which seemed to be insufficient to reduce the ICP significantly as claimed in previous reports that there must be a Sosm rise of at least 10 mOsm / kg to have a significant reduction in ICP. Also, to detemine the loss of water and electrolytes through urine after mannitol administration, the urine volume and electrolytes were measeured at 30 minutes intervals for the first one hour and then every hour thereafter for six hours in normal men(Group II). Water and electrolytes excretion rates and urinary sodium concentrations were calculated in each interval. The author believes that these data would be useful in estimating the amount of water and electrolytes that has to be replaced.