Elimination of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) from human blood in the Yusho and Yu-Cheng rice oil poisonings

The pharmacokinetics of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in humans was studied by monitoring the blood concentrations of individuals who ingested a contaminated rice oil in Japan (yusho) in 1968 and in Taiwan (yu-cheng) in 1979. Sixteen yusho patients were followed from 1982 to 1990 and three yu-cheng individuals from 1980 to 1989. From the three yucheng patients, blood lipid values for the two persistent toxic congeners, 2,3,4,7,8-pentachlorodibenzofuran (PnCDF) and 1,2,3,4,7,8-hexachlorodibenzofuran (HxCDF), varied from 50 g/kg at first sampling to about 1 g/kg at last sampling corresponding to half-lives for elimination (t_1/2) of 2-2_1/2 years. The blood lipid values for the same PCDF congeners in yusho patients varied from 5 g/kg down to 0.1 g/kg. The calculated t_1/2 were more variable with median values closer to 10 years. Planar PCBs #126 and #169 were present at lower concentrations than the PCDFs. For seven of the other PCB congeners, half-lives for elimination in the yu-cheng individuals varied from 1.2 up to 4.6 yr depending on the degree of chlorination. For the yusho patients, the elimination for the PCBs was longer. These results show that clearance of the toxic PCDFs and PCBs in humans is non-linear with faster elimination at higher exposure followed by slower decreases as background levels are approached. Such a clearance pattern can best be explained by a two compartment liver and fat pharmacokinetic model.     

Dietary and physical activity correlates of long-term weight loss

Covariations in body mass index (BMI), physical activity, macronutrient intake, and the frequency of consumption of specific foods were examined among 82 men and 75 women participating in a behavioral weight loss program over a period of 18 months. Results of repeated measures analyses of covariance showed that BMI change was inversely related to change in physical activity and change in frequency of vegetable consumption. BMI change was positively related to change in calorie intake from fat and change in frequency of consumption of beef, hot dogs, and sweets. Change in fat calories predicted BMI change better than change in total calories. In addition, change in the frequency of consumption of specific foods accounted for a larger percentage of the variance in BMI change than did change in macronutrients (10.4% vs. 5.2%). No differences were found between predictors of weight loss vs. weight maintenance.     

Missing annual external radiation dosimetry data among Hanford workers

Epidemiological studies of workers employed at the Hanford Site have been underway for nearly 30 years. Although the external radiation dosimetry program at Hanford has been fairly comprehensive, some workers included in previous epidemiological analyses have periods of employment during which there are missing annual external radiation dosimetry records. In this report, employment history records and annual external dosimetry records have been used to investigate the extent of missing annual external dosimetry records for workers at the Hanford facility. A "nearby" procedure for estimating values for missing annual external dosimetry records was evaluated. Among the 33,459 workers who were employed at least 180 days and had at least one annual external dosimetry record, annual external dosimetry records were missing for 8% of the years of employment (32,323 missing annual external dosimetry records). Missing annual external dosimetry records were more common for female Hanford workers than for male workers, and for workers employed in the early years of Hanford's operation than for workers employed in later years of operation. The nearby procedure provided reliable estimates of values for missing annual external dosimetry records. Using this procedure, 18,937.5 mSv were estimated for missing annual external dosimetry records; this was 2% of the total recorded cumulative external radiation dose for these workers. Missing annual external dosimetry records should be considered as a potential source of bias and uncertainty in investigations of radiation-cancer associations among Hanford workers.     

Bahia-Carolina Program in Environmental and Occupational Health: A North-South partnership for workplace and environmental justice.

The Bahia-Carolina Program in Environmental and Occupational Health is an interdisciplinary collaborative program in research and training linking the Institute for Collective Health (ISC), the Federal University of Bahia, Brazil, and the School of Public Health, University of North Carolina at Chapel Hill. An important goal of this Fogarty Center-funded project is to improve workplace and environmental conditions and the well-being of the general population, particularly those workers in the informal sector. Major accomplishments include training taking place in the United States, training in Brazil, and support of Brazilian institutions. Brazilians studying in the United States have researched occupational risk factors for non-Hodgkin's lymphoma, the effectiveness of an environmental sanitation program, the health of refinery workers, and statistical methods for multilevel analysis, among other topics. The program also emphasizes the opportunity for U.S. faculty and students to learn from Brazilian colleagues. Challenges encountered in the collaboration process are described.     

Resting energy expenditure in reduced-obese subjects in the National Weight Control Registry.

BACKGROUND: Weight loss in obese subjects is associated with a reduction in resting metabolic rate (RMR). Whether the reduction can be explained solely by a reduction in lean body mass remains controversial. OBJECTIVE: Our objective was to determine whether the reduction in RMR after weight loss was proportional to the decrease in lean mass alone or was greater than could be explained by body composition. DESIGN: We measured the RMR, fasting respiratory quotient (RQ), and body composition in 40 reduced-obese subjects [ie, 7 men and 33 women who had lost > or = 13.6 kg (30 lb) and maintained the loss for > or = 1 y] enrolled in the National Weight Control Registry and 46 weight-matched control subjects (9 men, 37 women). RESULTS: A stepwise multiple regression found lean mass, fat mass, age, and sex to be the best predictors of RMR in both groups. After adjusting RMR for these variables, we found no significant difference in RMR (5926 +/- 106 and 6015 +/- 104 kJ/d) between the 2 groups (P = 0.35). When we adjusted fasting RQ for percentage body fat and age, the reduced-obese group had a slightly higher (0.807 +/- 0.006) RQ than the control group (0.791 +/- 0.005, P = 0.05). This may have been due to the consumption of a diet lower in fat or to a reduced capacity for fat oxidation in the reduced-obese group. CONCLUSION: These results show that in at least some reduced-obese individuals there does not seem to be a permanent obligatory reduction in RMR beyond the expected reduction for a reduced lean mass.     

Medicine and the media: "A Lottery for Life

In a brief essay in a "Medicine and the Media" column, Dr. Wing discusses "A Lottery for Life," broadcast 2 August 1983 as part of the "First Thursday" television series. Interviews with patients, relatives, government officials, and physicians highlighted the problem of inadequate treatment facilities for end stage renal failure in Great Britain. The program made the point that patients turned down for treatment should seek second and third opinions, and that resource allocation decisions within the National Health Service should be matters for public concern and debate.     

Psychiatric morbidity and illness experience of primary care patients with chronic fatigue in Hong Kong

OBJECTIVE: The authors' goal was to examine the prevalence and experience of psychiatric morbidity among primary care patients with chronic fatigue in Hong Kong. METHOD: One hundred adult patients with medically unexplained fatigue for 6 or more months were assessed with the Explanatory Model Interview Catalogue, psychopathological rating scales, and an enhanced version of the Structured Clinical Interview for DSM-III-R. RESULTS: The lifetime prevalence of DSM-III-R depressive and anxiety disorders was 54%. Current depressive and anxiety disorders were identified in 28 patients, who exhibited more psychopathology and functional impairment than other patients. Thirty-three patients had somatoform pain disorder, and 30 had undifferentiated somatoform disorder, but most of them could also be diagnosed as having shenjing shuairuo (weakness of nerves) and, to a lesser extent, ICD-10 neurasthenia. Chronic fatigue syndrome diagnosed according to the 1988 Centers for Disease Control criteria was rare (3%) and atypical. Generally, patients mentioned fatigue if asked, but pains (36%), insomnia (20%), and worries (13%) were the most troublesome symptoms. Most patients attributed illness onset to psychosocial sources. CONCLUSIONS: Psychiatric morbidity was common among primary care patients with chronic fatigue. Subthreshold psychiatric morbidity was very common and was more validly represented by the disease construct of shenjing shuairuo or neurasthenia than somatoform disorder.     

Stopping nicotine exposure before surgery. The effect on spinal fusion in a rabbit model

STUDY DESIGN: A double-blind, prospective, randomized study using a validated rabbit model of intertransverse process fusion. OBJECTIVES: To determine the effect of stopping prolonged nicotine exposure on autogenous bone graft incorporation in a rabbit lumbar spinal fusion model. SUMMARY OF BACKGROUND DATA: There is a growing body of evidence that systemic nicotine impairs healing of spinal fusions and fractures. However, it remains to be determined whether, if nicotine increases the nonunion rate of spinal fusion surgery, stopping nicotine exposure before surgery will negate this inhibitory effect. METHODS: Forty-seven rabbits were divided into two experimental groups and one control group. The two experimental groups were exposed to systemic nicotine for 8 weeks. Nicotine exposure was stopped in one group 1 week before surgery; nicotine exposure was continued in the other group throughout the study. All rabbits underwent an L5-L6 intertransverse process fusion with autogenous iliac crest bone graft. All rabbits were killed 35 days after surgery. Forty rabbits completed the study and underwent radiographic, biomechanical, and histologic testing. RESULTS: Fusion, as determined by a blinded examiner palpating the spine, occurred in 7 of 13 control rabbits, 4 of 13 rabbits that "quit" nicotine, and none of the 14 rabbits exposed to continuous nicotine. There was a statistically significant difference between the control and continuous nicotine (P = 0.0015) and between the discontinued nicotine and continuous nicotine groups (P = 0.025). Biomechanical testing showed no significant differences between groups (P = 0.11). A blinded musculoskeletal pathologist was unable to detect a difference between groups based on histologic analysis. CONCLUSIONS: Chronic nicotine exposure was shown to decrease spinal fusion rates. Discontinuing nicotine before surgery improved fusion rates.     

Lamivudine for the prevention of hepatitis B virus reactivation in hepatitis B s-antigen seropositive cancer patients undergoing cytotoxic chemotherapy.

PURPOSE: For cancer patients receiving cytotoxic chemotherapy, hepatitis B virus (HBV) reactivation is a well described complication resulting in varying degrees of liver damage. The objectives of this study were to assess the efficacy of the antiviral agent lamivudine in reducing the incidence of HBV reactivation and diminishing morbidity and mortality of cancer patients with chronic HBV infection during chemotherapy. PATIENTS AND METHODS: Two groups were compared in this nonrandomized study. The prophylactic lamivudine group consisted of 65 patients in a phase II study who were treated with lamivudine before and until 8 weeks after discontinuing chemotherapy. The historical controls consisted of 193 consecutive patients who underwent chemotherapy without prophylactic lamivudine. Significant prognosticators for the development of HBV reactivation were determined based on data from the controls. Potential confounding factors were identified between the two groups. The outcomes were compared. RESULTS: In the controls, lymphoma and anthracycline usage were factors identified to be associated with reactivation. The two groups were comparable in most baseline characteristics, although in the prophylactic lamivudine group, there were significantly more patients with lymphoma and receiving anthracyclines. In the prophylactic lamivudine group, there was significantly less HBV reactivation (4.6% v 24.4% in the controls; P <.001), fewer incidences of hepatitis (17.5% v 44.6%; P <.0001) that were less severe (4.8% v 18.7%; P =.0005), and less disruption of chemotherapy (15.4% v 34.6%; P =.0029). The reduction in overall mortality was not statistically different. CONCLUSION: Prophylactic lamivudine significantly reduced the incidence of HBV reactivation and the overall morbidity of cancer patients undergoing chemotherapy.