Time spent on self-management by people with diabetes: results from the population-based KORA survey in Germany

AIMS

Time needed for health-related activities in people with diabetes is assumed to be substantial, yet available data are limited. Time spent on self-management and associated factors was analysed using cross-sectional data from people with diagnosed diabetes enrolled in a population-based study.

METHODS

Mean total time spent on self-management activities was estimated using a questionnaire for all participants with diagnosed diabetes in the KORA FF4 study (n = 227, 57% men, mean age 69.7, sd 9.9 years). Multiple two-part regression models were fitted to evaluate associated factors. Multiple imputation was performed to adjust for bias due to missing values.

RESULTS

Some 86% of participants reported spending time on self-management activities during the past week. Over the entire sample, a mean of 149 (sd 241) min/week were spent on self-management-activities. People with insulin or oral anti-hyperglycaemic drug treatment, better diabetes education, HbA_1c 48 to < 58 mmol/mol (6.5% to < 7.5%) or lower quality of life, spent more time on self-management activities. For example, people without anti-hyperglycaemic medication invested 66 min/week in self-management, whereas those taking insulin and oral anti-hyperglycaemic drugs invested 269 min/week (adjusted ratio 4.34, 95% confidence interval 1.85-10.18).

CONCLUSIONS

Time spent on self-management activities by people with diabetes was substantial and varied with an individual's characteristics. Because of the small sample size and missing values, the results should be interpreted in an explorative manner. Nevertheless, time needed for self-management activities should be routinely considered because it may affect diabetes self-care and quality of life.

Molecular epidemiology suggests Venezuela as the origin of the dengue outbreak in Madeira, Portugal in 2012-2013

An explosive epidemic occurred in Madeira Island (Portugal) from October 2012 to February 2013. Published data showed that dengue virus type 1 introduced from South America was the incriminated virus. We aim to determine the origin of the strain introduced to Madeira by travellers returning to Europe. Using phylogeographic analysis and complete envelope sequences we have demonstrated that the most probable origin of the strain is Venezuela.

Health-related quality of life in women and men with type 2 diabetes: a comparison across treatment groups

AIM

This study compares health-related quality of life (HRQL) in patients with type 2 diabetes (T2DM) across treatment groups and explores gender differences.

METHODS

Four regional surveys (KORA, CARLA, SHIP, DHS) and a national survey (GNHIES98) were pooled at individual level. HRQL was assessed with the SF-12/-36v1. Linear regression models were used to assess the effect of T2DM by treatment type (no medication; oral; oral/insulin combination; insulin) on the physical (PCS-12) and mental summary score (MCS-12) and the SF-6D, controlling for age, sex, study and covariates. We also performed an explanatory analysis of single items.

RESULTS

PCS-12 scores and treatment type were associated (P-value 0.006), with lowest values for insulin treatment (-4.44 vs. oral; -4.41 vs. combination). MCS-12 scores were associated with treatment type and gender (P-value <0.012), with lower scores for women undergoing oral (-4.25 vs. men) and combination treatment (-6.99 vs. men). Similar results were observed for SF-6D utilities and single items, related to mental health, social functioning, vitality and role limitation (emotional). Comorbidities were predictors of lower PCS-12 and SF-6D scores.

CONCLUSIONS

T2DM treatment impacts differently on physical and mental HRQL and on women and men. Further studies of gender-specific perceptions of T2DM treatment regimens are needed.

Skin and soft tissue infections in intercontinental travellers and the import of multi-resistant Staphylococcus aureus to Europe

Staphylococcus aureus is emerging globally. Treatment of infections is complicated by increasing antibiotic resistance. We collected clinical data and swabs of returnees with skin and soft tissue infections (SSTI) at 13 travel-clinics in Europe (www.staphtrav.eu). Sixty-two percent (196/318) SSTI patients had S. aureus-positive lesions, of which almost two-thirds (122/196) were Panton-Valentine leukocidin (PVL) positive. PVL was associated with disease severity, including hospitalization for SSTI (OR 5.2, 95% CI 1.5-18.2). In returnees with SSTI, longer travel and more intense population contact were risk factors for nasal colonization with PVL-positive S. aureus. Imported S. aureus frequently proved resistant to trimethoprim-sulfamethoxazole (21%), erythromycin (21%), tetracycline (20%), ciprofloxacin (13%), methicillin (12%) and clindamycin (8%). Place of exposure was significantly (p < 0.05) associated with predominant resistance phenotypes and spa genotypes: Latin America (methicillin; t008/CC24/304), Africa (tetracycline, trimethoprim-sulfamethoxazole; t084/CC84, t314/singleton, t355/CC355), South Asia (trimethoprim-sulfamethoxazole, ciprofloxacin; t021/CC21/318), South-East Asia (clindamycin; t159/CC272). USA300-like isolates accounted for 30% of all methicillin-resistant S. aureus imported to Europe and were predominantly (71%) acquired in Latin America. Multi-resistance to non-β-lactams were present in 24% of imports and associated with travel to South Asia (ORcrude 5.3, 95% CI 2.4-11.8), even after adjusting for confounding by genotype (ORadjusted 3.8, 95% 1.5-9.5). Choosing randomly from compounds recommended for the empiric treatment of severe S. aureus SSTI, 15% of cases would have received ineffective antimicrobial therapy. These findings call for the development of regionally stratified guidance on the antibiotic management of severe imported S. aureus disease and put the infected and colonized traveller at the centre of interventions against the global spread of multi-resistant S. aureus.

Medication costs by glucose tolerance stage in younger and older women and men: results from the population-based KORA survey in Germany

To estimate medication costs in individuals with diagnosed diabetes, undetected diabetes, impaired glucose regulation and normal blood glucose values in a population-based sample by age and sex.Using the KORA F4 follow-up survey, conducted in 2006-2008 (n=2611, age 40-82 years), we identified individuals' glucose tolerance status by means of an oral glucose tolerance test. We assessed all medications taken regularly, calculated age-sex specific medication costs and estimated cost ratios for total, total without antihyperglycemic drugs, and cardiovascular medication, using multiple 2-part regression models.Compared to individuals with normal glucose values, costs were increased in known diabetes, undetected diabetes and impaired glucose regulation, which was more pronounced in participants aged 40-59 years than in those aged 60-82 years (cost ratios for all medications: 40-59 years: 2.85; 95%-confidence interval: 1.78-4.54, 2.00; 1.22-3.29 and 1.53; 1.12-2.09; 60-82 years: 2.04; 1.71-2.43, 1.17; 0.90-1.51 and 1.09; 0.94-1.28). Compared to individuals with diagnosed diabetes, costs were significantly lower among individuals with impaired glucose regulation across all age and sex strata, also when antihyperglycemic medication was excluded (40-59 years: 0.60; 0.36-0.98, 60-82 years: 0.74; 0.60-0.90; men: 0.72; 0.56-0.93; women: 0.72; 0.54-0.96).We could quantify age- and sex-specific medication costs and cost ratios in individuals with diagnosed diabetes, undetected diabetes and impaired glucose regulation compared to those with normal glucose values, using data of a population-based sample, with oral glucose tolerance test-based identification of diabetes states. These results may help to validly estimate cost-effectiveness of screening and early treatment or prevention of diabetes.

Patient time costs attributable to healthcare use in diabetes: results from the population-based KORA survey in Germany

AIMS

Patient time costs have been described to be substantial; however, data are highly limited. We estimated patient time costs attributable to outpatient and inpatient care in study participants with diagnosed diabetes, previously undetected diabetes, impaired glucose regulation and normal glucose tolerance.

METHODS

Using data of the population-based KORA S4 study (55-74 years, random sample of n = 350), we identified participants' stage of glucose tolerance by oral glucose tolerance test. To estimate mean patient time costs per year (crude and standardized with respect to age and sex), we used data regarding time spent with ambulatory visits including travel and waiting time and with hospital stays (time valued at a 2011 net wage rate of €20.63/h). The observation period was 24 weeks and data were extrapolated to 1 year.

RESULTS

Eighty-nine to 97% of participants in the four groups (diagnosed diabetes, undetected diabetes, impaired glucose regulation and normal glucose tolerance.) had at least one physician contact and 4-14% at least one hospital admission during the observation period. Patient time [h/year (95% CI)] was 102.0 (33.7-254.8), 53.8 (15.0-236.7), 59.3 (25.1-146.8) and 28.6 (21.1-43.7), respectively. Age-sex standardized patient time costs per year (95% CI) were €2447.1 (804.5-6143.6), €880.4 (259.1-3606.7), €1151.6 (454.6-2957.6) and €589.2 (435.8-904.8).

CONCLUSIONS

Patient time costs were substantial--even higher than medication costs in the same study population. They are higher in participants with diagnosed diabetes, but also in those with undetected diabetes and impaired glucose regulation compared with those with normal glucose tolerance. Research is needed in larger populations to receive more precise and certain estimates that can be used in health economic evaluation.

Regional differences in the prevalence of known Type 2 diabetes mellitus in 45-74 years old individuals: results from six population-based studies in Germany (DIAB-CORE Consortium)

AIM

In Germany, regional data on the prevalence of Type 2 diabetes mellitus are lacking for health-care planning and detection of risk factors associated with this disease. We analysed regional variations in the prevalence of Type 2 diabetes and treatment with antidiabetic agents.

METHODS

Data of subjects aged 45-74 years from five regional population-based studies and one nationwide study conducted between 1997 and 2006 were analysed. Information on self-reported diabetes, treatment, and diagnosis of diabetes were compared. Type 2 diabetes prevalence estimates (95% confidence interval) from regional studies were directly standardized to the German population (31 December 2007).

RESULTS

Of the 11,688 participants of the regional studies, 1008 had known Type 2 diabetes, corresponding to a prevalence of 8.6% (8.1-9.1%). For the nationwide study, a prevalence of 8.2% (7.3-9.2%) was estimated. Prevalence was higher in men (9.7%; 8.9-10.4%) than in women (7.6%; 6.9-8.3%). The regional standardized prevalence was highest in the east with 12.0% (10.3-13.7%) and lowest in the south with 5.8% (4.9-6.7%). Among persons with Type 2 diabetes, treatment with oral antidiabetic agents was more frequently reported in the south (56.9%) and less in the northeast (46.0%), whereas treatment with insulin alone was more frequently reported in the northeast (21.6%) than in the south (16.4%).

CONCLUSION

The prevalence of known Type 2 diabetes showed a southwest-to-northeast gradient within Germany, which is in accord with regional differences in the distribution of risk factors for Type 2 diabetes. Furthermore, the treatment with antidiabetic agents showed regional differences.

Health-related quality of life in subjects with and without Type 2 diabetes: pooled analysis of five population-based surveys in Germany

AIMS

To estimate population values of health-related quality of life (HRQL) in subjects with and without Type 2 diabetes mellitus across several large population-based survey studies in Germany. Systematic differences in relation to age and sex were of particular interest.

METHODS

Individual data from four population-based studies from different regions throughout Germany and the nationwide German National Health Interview and Examination Survey (GNHIES98) were included in a pooled analysis of primary data (N = 9579). HRQL was assessed using the generic index instrument SF-36 (36-item Short Form Health Survey) or its shorter version, the SF-12 (12 items). Regression analysis was carried out to examine the association between Type 2 diabetes and the two component scores derived from the SF-36/SF-12, the physical component summary score (PCS-12) and the mental component summary score (MCS-12), as well as interaction effects with age and sex.

RESULTS

The PCS-12 differed significantly by -4.1 points in subjects with Type 2 diabetes in comparison with subjects without Type 2 diabetes. Type 2 diabetes was associated with significantly lower MCS-12 in women only. Higher age was associated with lower PCS-12, but with an increase in MCS-12, for subjects with and without Type 2 diabetes.

CONCLUSIONS

Pooled analysis of population-based primary data offers HRQL values for subjects with Type 2 diabetes in Germany, stratified by age and sex. Type 2 diabetes has negative consequences for HRQL, particularly for women. This underlines the burden of disease and the importance of diabetes prevention. Factors that disadvantage women with Type 2 diabetes need to be researched more thoroughly.

Excision of pre-ulcerative forms of Buruli ulcer disease: a curative treatment?

BACKGROUND

Previous investigations have revealed that Mycobacterium ulcerans is extensively distributed spatially throughout ulcerative lesions, including in the margins of excised tissue. In contrast, bacilli in pre-ulcerative lesions are assumed to be concentrated in the center of the lesion. In order to assess the extent to which the surgical excision of pre-ulcerative lesions is capable of removing all infected tissue, we subjected the excision margins of pre-ulcerative lesions to laboratory analysis.

PATIENTS AND METHODS

Eleven patients with laboratory-confirmed pre-ulcerative lesions were included in the study. The diameter of the lesion and excised tissue and the "surgical distance" between the border of the lesion and excision margin were measured. The entire excision margin was cut into segments and subjected to IS2404 PCR.

RESULTS

The results from the PCR analysis on the samples of excision margins were highly significantly associated with the surgical distance (p < 0.001). The margin samples of nodules were significantly more often PCR positive than the plaques (p = 0.025). The size of the lesion and the size of the excised tissue did not significantly influence the PCR results. Statistically, a surgical distance of more than 9 mm was found to reduce the risk of remaining infected tissue to less than 10%, that of 13 mm to reduce the risk to less than 5%, and that of 25 mm to reduce the risk to nearly 0%.

CONCLUSION

The results of this study show that in preulcerative Buruli ulcer disease, bacilli may extend beyond the actual size of the lesion and that there is a strong correlation between the presence of M. ulcerans in the margin samples and the surgical distance. Excision with a surgical distance of 25 mm avoided the risk of remaining mycobacteria in this study. However, no recurrences occurred in the patients with M. ulcerans-positive excision margins. The need of postoperative antimycobacterial treatment in these patients remains to be determined.

Time trends in type 2 diabetes patients' disease management and outcomes: evidence from two KORA surveys in Germany

To explore time trends in diabetes management and intermediate health outcomes of people with type 2 diabetes, data from two population-based survey studies were compared. The surveys were conducted in the Augsburg region of Southern Germany in 1997/98 and in 2004/05, and included physical examinations, interviews, self-administered questionnaires and laboratory tests. Data from 334 participants aged 40-84 were analysed, including a longitudinal sub-sample of 50 persons. Results show significant time trends towards improvements over the seven year period. Controlling for age, sex, education and duration of diabetes, people felt better informed about diabetes (Odds Ratio (OR) 1.87; 95% CI: 1.12, 3.14) and stated greater adherence to the treatment plan (OR 4.42; CI: 2.62, 7.45) as well as higher participation in diabetes education programmes (OR 2.20; CI: 1.44, 3.38). Mean haemoglobin A1c levels decreased by -0.97% from 7.3% to 6.3% (CI:-0.66%, -1.28%). Physical activity (> or =1 h/week) was more frequent (OR 2.75; CI: 1.65, 4.59), although Body Mass Index increased by 1.43 kg/m (2) (CI: 0.86, 2.00). The positive changes in disease management and metabolic outcomes for type 2 diabetic patients between 1997/98 and 2004/05 indicate a shift towards greater patient involvement in diabetes care and possibly more efficient medical management practices.

Imported leishmaniasis in Germany 2001–2004: data of the SIMPID surveillance network

Leishmaniasis is a rare, non-notifiable disease in Germany. Epidemiological and clinical data, therefore, are scarce. Most infections seen in Germany are contracted outside the country. The German surveillance network for imported infectious diseases (Surveillance Importierter Infektionen in Deutschland, or SIPMID) recorded 42 cases of imported leishmaniasis (16 visceral, 23 cutaneous, and 3 mucocutaneous) from January 2001 to June 2004. Although most infections were acquired in European Mediterranean countries, the risk of infection was highest for travelers to Latin America. HIV coinfection was observed significantly more often in patients with visceral leishmaniasis than in patients with cutaneous/mucocutaneous leishmaniasis (31 vs. 4%, p=0.02). The median time to a definitive diagnosis was 85 days in cases of visceral leishmaniasis and 61 days in cases of cutaneous/mucocutaneous leishmaniasis, reflecting the unfamiliarity of German physicians with leishmanial infections. Visceral leishmaniasis was treated most frequently with amphotericin B, whereas cutaneous/mucocutaneous leishmaniasis was treated with a variety of local and systemic therapies. The findings presented here should serve to increase awareness as well as improve clinical management of leishmaniasis in Germany.

Kinetics of lactate metabolism after submaximal ergometric exercise in HIV-infected patients

OBJECTIVES

It is unknown whether high levels of lactate result from enhanced production or decreased degradation. We therefore investigated differences in the kinetics of plasma lactic acid in HIV-infected patients receiving or not receiving highly active antiretroviral therapy (HAART) and in uninfected controls after submaximal ergometric exercise.

METHODS

Ten healthy controls, 11 HIV-infected therapy-naïve patients, 15 HIV-infected patients on HAART with normal baseline lactate levels, and nine HIV-infected patients on HAART with elevated baseline lactate levels >2 mmol/L performed 10 min of ergometric exercise, with a heart rate of 200 beats/min minus age. Lactate levels were measured at baseline, at the end of exercise and 15, 30, 45, 60 and 120 min thereafter.

RESULTS

Mean baseline lactate levels were 1.4, 1.5, 1.5 and 2.8 mmol/L in the controls, the therapy-naïve patients, the patients on HAART with normal lactate levels and the patients on HAART with elevated lactate levels, respectively. Maximum lactate levels after exercise were similar in all groups (9.7, 9.4, 9.0 and 10.1 mmol/L, respectively). Significant differences were found in the slope of lactate decline between controls and untreated individuals (P=0.038) and between patients on HAART with normal baseline lactate and patients on HAART with elevated baseline lactate (P=0.028).

CONCLUSIONS

Differences in lactate metabolism do exist between healthy controls and HIV-infected therapy-naïve individuals. Thus, HIV infection in itself may influence lactate levels. Elevated baseline lactate levels are associated with a delayed decline of lactate after exercise. These results could be explained by impaired lactate clearance. Lactate production upon exercise does not seem to be affected by baseline lactate levels.

Epidemiology and clinical features of vivax malaria imported to Europe: sentinel surveillance data from TropNetEurop

BACKGROUND

Plasmodium vivax is the second most common species among malaria patients diagnosed in Europe, but epidemiological and clinical data on imported P. vivax malaria are limited. The TropNetEurop surveillance network has monitored the importation of vivax malaria into Europe since 1999.

OBJECTIVES

To present epidemiological and clinical data on imported P. vivax malaria collected at European level.

MATERIAL AND METHODS

Data of primary cases of P. vivax malaria reported between January 1999 and September 2003 were analysed, focusing on disease frequency, patient characteristics, place of infection, course of disease, treatment and differences between network-member countries.

RESULTS

Within the surveillance period 4,801 cases of imported malaria were reported. 618 (12.9%) were attributed to P. vivax. European travellers and immigrants were the largest patient groups, but their proportion varied among the reporting countries. The main regions of infection in descending order were the Indian subcontinent, Indonesia, South America and Western and Eastern Africa, as a group accounting for more than 60% of the cases. Regular use of malaria chemoprophylaxis was reported by 118 patients. With 86 (inter-quartile range 41-158) versus 31 days (inter-quartile range 4-133) the median symptom onset was significantly delayed in patients with chemoprophylaxis (p < 0.0001). Common complaints were fever, headache, fatigue, and musculo-skeletal symptoms. All patients survived and severe clinical complications were rare. Hospitalization was provided for 60% and primaquine treatment administered to 83.8% of the patients, but frequencies varied strongly among reporting countries.

CONCLUSIONS

TropNetEurop data can contribute to the harmonization of European treatment policies.

[German-speaking memory clinics: state of the art and practical recommendations]

The 7th annual meeting of the memory clinics of Germany, Switzerland and Austria in March 2002 in Göttingen, Germany was an optimal opportunity to make an inventory about the state of the art in diagnostic and therapy of dementia and mild cognitive impairment in German-speaking memory clinics. Several problems were discussed including difficulties in 1) diagnosis of patients with aphasia or foreign patients, 2) handling of demented patients without a caregiver, 3) psychological support for patients, who have been diagnosed in a very early stage, 4) misunderstandings between general practitioners, neurologists and psychiatrists in private practice on the one hand and the memory clinics on the other hand, 5) recommendations for prevention of dementia, 6) recommendations concerning dementia and car driving and 7) questions of genetic counselling. The following paper is a summary of the results of a workshop in Göttingen and gives practical recommendations based on the experiences of the memory clinics.

[One catches not only mice with bacon. An atraumatic treatment for cutaneous myiasis]

HISTORY AND ADMISSION FINDINGS

A 37 year old patient was admitted because of four prurigous furunculoid swellings on his right upper knee. The patient had a history of traveling in Brasil for 6 weeks, returning 2 weeks before admission. The nodular skin lesions, 2.5 cm in diameter, had a central opening, from where under little pressure a seropurulent fluid discharged. In the central opening moving, whitish structures were visible.

TREATMENT AND COURSE

A piece of raw bacon, serving as occlusion-material, was fixated on the affected skin for two hours. The larvae emerged due to oxygen deficiency. After retraction of the bacon it was possible to grasp the emerged end of the larvae with tweezers and pull them out completely. The larvae were identified as third instar of dermatobia hominis.

CONCLUSION

Cutaneous myiasis is a worthy differential diagnosis in patients presenting with furunculoid skin lesions after traveling to endemic areas. The treatment with bacon as an occlusion-material offers an atraumatic alternative to surgical excision.

Detection of Giardia lamblia and Entamoeba histolytica in stool samples by two enzyme immunoassays

Two commercially produced enzyme immunoassays (EIAs) to detect antigens of Giardia lamblia and Entamoeba histolytica in stool specimens were evaluated. A total of 276 stool specimens were collected from patients who presented with various medical complaints in the outpatient clinic of the Department of Infectious Diseases and Tropical Medicine, University of Munich. Every specimen was examined by conventional microscopy and tested by both EIA kits. When microscopy was used as the reference standard, the EIA kit detecting Giardia lamblia showed a sensitivity of 100% and a specificity of 99.6%. The EIA kit detecting Entamoeba histolytica had a sensitivity of 81.8% and a specificity of 99.2%. Both tests showed no cross-reactivity with other intestinal protozoa. Antigen detection by EIA has the potential to become a valuable tool capable of making stool diagnostics more effective, although it should not be considered as a replacement for microscopic examination, since other potential pathogens could otherwise escape detection.

[Arthrogenic ear canal tumor]

We report our findings in two female patients (aged 56 and 64 years) who complained about slight hearing loss that varied during jaw movements. In both cases a polypoid tumor of the external auditory meatus was found that almost completely disappeared with mouth opening. CT showed a bony defect of the anterior wall of the external auditory canal in both patients. Biopsies from the tumor-like lesions were done, revealing a chronic inflammatory hyperplasia of the connective tissue in one case and a rheumatic granuloma in the other. Review of medical histories showed that the first patient suffered from a recurrent neurodermatitis and the second had experienced a chronic polyarthritis for many years. From these findings and on the basis of a literature review, we conclude that these pseudotumors represent a chronic inflammatory hyperplasia of the periarticular tissue which herniated through a persistent "foramen of Huschke." This foramen is formed during embryological development of the two tympanic tubercles, but normally closes before the age of 5 years. However, in a few rare cases is may persist to allow herniation of synovial tissue.

Alteration of xanthine oxidase activity in sinusoidal endothelial cells and morphological changes of Kupffer cells in hypoxic and reoxygenated rat liver

In the model of the perfused rat liver, we investigated the alterations of sinusoidal cells in the pathogenesis of liver injury caused by hypoxia and reperfusion. In sinusoidal endothelial cells, the activity of xanthine oxidase (XOX), a cytoplasmic marker enzyme, was located cytochemically and determined biochemically. Kupffer cells, identified by their endogenous peroxidase staining, were studied with regard to changes in their ultrastructure. In our experiments, parenchymal cells were shown to be severely damaged in contrast to sinusoidal lining cells, which showed minor signs of injury. In comparison with the control group, XOX activity increased significantly in the sinusoidal endothelial cells after low-flow hypoxia; however, after reoxygenation of only 5 minutes, that activity was lower after hypoxia but higher after control perfusion. In Kupffer cells, hypoxia resulted in a strong suppression of phagocytic and endocytotic activity and in a disappearance of the lamellopodia. Kupffer cells were flattened, resembling sinusoidal endothelial cells. After reoxygenation phagocytic vesicles, lamellopodia, and cell volume of Kupffer cells increased markedly in comparison with the control group. In the hypoxia/reperfusion injury model, our observations revealed significant alterations of sinusoidal lining cells. It appears that sinusoidal endothelial cells respond to the hypoxic phase by producing oxygen-derived free radicals and that Kupffer cells respond to the subsequent reperfusion phase by activation followed by the release of toxic mediators.

Alterations of Na+,K(+)-ATPase activity after hypoxia and reoxygenation in the perfused rat liver: an electron microscopic cytochemical study

BACKGROUND/AIMS

Using the cerium technique for ultrastructural cytochemical studies, Na+,K(+)-ATPase activity was investigated in hypoxic and reoxygenated rat liver.

METHODS

In the control group, the livers were perfused with oxygenated hemoglobin-free Krebs-Henseleit buffer for 1 h. For hypoxia (60 min), the flow rate of the perfusate was decreased and oxygen was replaced by nitrogen. For reoxygenation, the liver was reperfused under oxygenated conditions for 5 min after 60 min of hypoxia.

RESULTS

In control livers, a strong Na+,K(+)-ATPase activity was detected at the basolateral membrane of hepatocytes while the apical membrane forming the bile canaliculi did not display any staining. In hypoxic livers, Na+,K(+)-ATPase activity had ceased in the plasma membrane of hepatocytes. In reoxygenated livers, Na+,K(+)-ATPase was rapidly reactivated in the basolateral hepatic membrane. The membrane of blebs generated during the hypoxic phase also showed enzyme activity. In addition, a striking accumulation of reaction product could be observed in about 10% of the apical membranes lining the bile canaliculi.

CONCLUSION

The results indicate a plasticity of the Na+,K(+)-ATPase in hypoxic and reoxygenated rat liver.

Cancer promotion in a mouse-skin model by a 60-Hz magnetic field: II. Tumor development and immune response

This paper describes preliminary findings on the influence of 60-Hz (2-mT) magnetic fields on tumor promotion and co-promotion in the skins of mice. The effect of magnetic fields on natural killer (NK) cell activity in spleen and blood was also examined. Groups of 32 juvenile female mice were exposed to the magnetic field as described in part I. The dorsal skin of all animals was treated with a subthreshold dose of the carcinogen 7,12-dimethyl-benz(a)anthracene (DMBA). One week after the treatment, two groups were sham exposed (group A) or field exposed at 2 mT (group B) 6 h/day for 21 weeks, to test whether the field would act as a tumor promoter. No tumors developed in these two groups of mice. To test whether the magnetic field would modify tumor development by directly affecting tumor growth or by suppressing immune surveillance, two additional groups of mice were treated weekly with the tumor promoter 12-0-tetradecanoylphorbol-13-acetate (TPA) and then either sham exposed (group C) or field exposed (group D). The time to appearance of tumors was shorter (but not statistically so) in the group exposed to magnetic fields and TPA. Some differences in NK cell activity and spleen size were observed between the sham- and field-exposed groups.