Implementation of discharge recommendations in type 1 diabetes depends on specialist nurse follow-up.

AIM: This paper presents an implementation study following previous research including a randomised controlled trial (RCT) of hospital-based home care (HBHC), referring to specialist care in a home-based setting. The aim was to evaluate whether the effects sustained when rolled out into wider practice. METHODS: In 2013-2014, 42 children newly diagnosed type 1 diabetes were included in the study at a university hospital in Sweden and followed for two years. Measurements of child safety, effects of services, resource use and service quality were included. Descriptive statistics were used to present the results and then discussed in relation to the same intervention of HBHC previously evaluated in an RCT. RESULTS: Shorter in-hospital stay was partially implemented but increased support after discharge by the diabetes nurse was not. The results indicated that the implemented HBHC was equally effective in terms of child outcomes two years from diagnosis but less effective in terms of parents' outcome. The results furthermore indicated that the quality of services decreased. CONCLUSION: The suggested overall conclusion was that the implemented HBHC services were safe but had become less effective, at least in relation to the HBHC provided under controlled circumstances.

Testis transcriptome alterations in zebrafish (Danio rerio) with reduced fertility due to developmental exposure to 17α-ethinyl estradiol.

17α-Ethinylestradiol (EE2) is a ubiquitous aquatic contaminant shown to decrease fish fertility at low concentrations, especially in fish exposed during development. The mechanisms of the decreased fertility are not fully understood. In this study, we perform transcriptome analysis by RNA sequencing of testes from zebrafish with previously reported lowered fertility due to exposure to low concentrations of EE2 during development. Fish were exposed to 1.2 and 1.6 ng/L (measured concentration; nominal concentrations 3 and 10 ng/L) of EE2 from fertilization to 80 days of age, followed by 82 days of remediation in clean water. RNA sequencing analysis revealed 249 and 16 genes to be differentially expressed after exposure to 1.2 and 1.6 ng/L, respectively; a larger inter-sample variation was noted in the latter. Expression of 11 genes were altered by both exposures and in the same direction. The coding sequences most affected could be categorized to the putative functions cell signalling, proteolysis, protein metabolic transport and lipid metabolic process. Several homeobox transcription factors involved in development and differentiation showed increased expression in response to EE2 and differential expression of genes related to cell death, differentiation and proliferation was observed. In addition, several genes related to steroid synthesis, testis development and function were differentially expressed. A number of genes associated with spermatogenesis in zebrafish and/or mouse were also found to be differentially expressed. Further, differences in non-coding sequences were observed, among them several differentially expressed miRNA that might contribute to testis gene regulation at post-transcriptional level. This study has generated insights of changes in gene expression that accompany fertility alterations in zebrafish males that persist after developmental exposure to environmental relevant concentrations of EE2 that persist followed by clean water to adulthood. Hopefully, this will generate hypotheses to test in search for mechanistic explanations.

Developmental exposure to the SSRI citalopram causes long-lasting behavioural effects in the three-spined stickleback (Gasterosteus aculeatus).

Selective Serotonin re-uptake inhibitors (SSRIs) are a class of psychotropic drugs used to treat depression in both adolescents and pregnant or breast-feeding mothers as well as in the general population. Recent research on rodents points to long-lasting behavioural effects of pre- and perinatal exposure to SSRIs which last into adulthood. In fish however, studies on effects of developmental exposure to SSRIs appears to be non-existent. In order to study effects of developmental SSRI exposure in fish, three-spine sticklebacks were exposed to 1.5 µg/l of the SSRI citalopram in the ambient water for 30 days, starting two days post-fertilisation. After approximately 100 days of remediation in clean water the fish were put through an extensive battery of behavioural tests. Feeding behaviour was tested as the number of bites against a piece of food and found to be increased in the exposed fish. Aggression levels were measured as the number of bites against a mirror image during 10 min and was also found to be significantly increased in the exposed fish. Novel tank behaviour and locomotor activity was tested in an aquarium that had a horizontal line drawn half-way between the bottom and the surface. Neither the latency to the first transition to the upper half, nor the number of transitions or the total time spent in the upper half was affected by treatment. Locomotor activity was significantly reduced in the exposed fish. The light/dark preference was tested in an aquarium where the bottom and walls were black on one side and white on the other. The number of transitions to the white side was significantly reduced in the exposed fish but there was no effect on the latency to the first transition or the total time spent in the white half. The results in the current study indicate that developmental SSRI exposure causes long-lasting behavioural effects in fish and contribute to the existing knowledge about SSRIs as environmental pollutants.

Parents' Experiences of Health and Needs When Supporting Their Adolescents With Cerebral Palsy During Transition to Adulthood.

AIMS: Parents are the primary support providers for adolescents with disabilities, their health and wellbeing is therefore of great importance when planning for youths' transition into adulthood. The aim of this study was to gain a deeper understanding of how parents of adolescents with cerebral palsy (CP) experience their own health and wellbeing and their needs for support during the adolescent's transition to adulthood. METHODS: An inductive qualitative approach was used, including interviews with 15 mothers and fathers to 10 adolescents with CP aged 17-18 years. Latent content analysis was used for analyzing the data. RESULTS: The main theme "Friction blisters chafing and healing during transition" illustrates the parents' experiences. Five sub-themes formed the parents' experiences of concerns along with sorrow and stress in life, worries about what was to come, their need for support, strategies for coping, and experiences of cohesion. CONCLUSIONS: Knowledge of parents' experiences of their health, wellbeing, and needs provide valuable information for the planning of transition for adolescents with disabilities. Help with parents' sorrow, stress, and worry in daily life might be facilitated and parental health safeguarded by a navigator who can both guide and give hands-on support.

Living in transition - experiences of health and well-being and the needs of adolescents with cerebral palsy.

BACKGROUND: Transition to adulthood for adolescents in general is a multifaceted process, and for adolescents with cerebral palsy (CP) it also involves transition from child- to adult-oriented support. CP entails a variety and combination of disabilities, which in association with external factors may make the transition to adult health services difficult. The aim of this study was to gain a deeper understanding of how adolescents with CP experience their own health, well-being and need of support during their transition to adulthood. METHODS: An inductive qualitative approach was used based on interviews with 12 adolescents with CP aged 17-18 years and living in Sweden. Manifest and latent content analysis was used for the analysis of data. RESULTS: The results are described in the main theme 'Living in transition and looking forward to being an adult, but not feeling ready yet and being in need of further support'. Five subthemes highlight the adolescents' experiences of belonging to a family, of the importance of friends and love, of managing daily activities, being surrounded by support and having hopes for the future. CONCLUSIONS: Interviews with adolescents with CP provide valuable information for the planning of transition programmes and for the support of adolescents with disabilities who are in the transition to adult living. According to the adolescents in this study, the support should be flexible and not be fixed to biological age. Personal, individualized information and support was desired by the adolescents in order to be able to manage their own transition. One option to facilitate transition is the stepping-stone of being close to parents or staff members during the first phase, after leaving the parental home.

Hospital-based home care for children with cancer: a qualitative exploration of family members' experiences in Denmark.

The study aims to describe the experiences of a hospital-based home care programme in the families of children with cancer. Fourteen parents, representing 10 families, were interviewed about their experiences of a hospital-based home care programme during a 4-month period in 2009 at a university hospital in Denmark. Five children participated in all or part of the interview. The interviews were transcribed verbatim and analysed using qualitative content analysis. The findings indicate that hospital-based home care enabled the families to remain intact throughout the course of treatment, as it decreased the strain on the family and the ill child, maintained normality and an ordinary everyday life and fulfilled the need for safety and security. According to family members of children with cancer, hospital-based home care support enhanced their quality of life during the child's cancer trajectory. Our study highlights the importance of providing hospital-based home care with consideration for the family members' need for the sense of security achieved by home care by experienced paediatric oncology nurses and regular contact with the doctor. In future studies, interviews with children and siblings could be an important source of information for planning and delivering care suited to the families' perceived needs.

Returning to a changed ordinary life--families' lived experience after completing a child's cancer treatment.

The aim of the study was to illuminate the families' lived experience after completing a child's cancer treatment. The study took place at a University Hospital in southern Sweden. Interviews were carried out with 10 mothers, eight fathers, four patients and two siblings from a total of 10 families. The interviews were analysed with a hermeneutical phenomenological approach. One essential theme emerged from their stories, 'returning to a changed ordinary life--incorporating a trying and contradictory experience'. The families felt relieved that the treatment was over yet they experienced strains in their daily life. Family members felt changed and especially the parents needed to focus on themselves in order to recover. Closeness with other people, especially their own family, was important. The previously sick children felt a loss of concern from their parents when treatment had ended, in contrast to siblings who experienced increased attention from their parents. Parents experienced being in uncharted territory and sometimes missed the security of hospital. For professionals it is important to offer the family a structured follow-up to help them in their daily life after the child's treatment is completed.

Tuberculosis along the continuum of HIV care in a cohort of adolescents living with HIV in Ethiopia.

SETTING: Eight health facilities in Ethiopia. OBJECTIVE: To determine tuberculosis (TB) incidence rates and associated factors among adolescents living with the human immunodeficiency virus (ALHIV). DESIGN: This was a retrospective cohort study. Adolescents enrolled in HIV care between January 2005 and 31 December 2013 constituted the study population. The main outcome variable was TB diagnosis during follow-up. Baseline World Health Organization (WHO) clinical stage, CD4 count, previous history of TB and use of isoniazid preventive therapy (IPT) were the main independent variables. We estimated TB incidence rates as incident cases per 100 person-years of observation (PYO). Cox regression analysis was used to control for confounders. RESULTS: Of the 1221 adolescents screened, 1072 were studied; 60.1% were girls. TB incidence rate was 16.32 per 100 PYO during pre-antiretroviral therapy (pre-ART) follow-up but declined to 2.25 per 100 PYO after initiation of ART. Advanced WHO clinical stage (adjusted hazard ratio [aHR] 2.71, 95%CI 1.69-4.33) and CD4 count <350 cells/µl (aHR 2.28, 95%CI 1.10-4.81) predicted TB incidence in the pre-ART cohort. IPT use was associated with a significant reduction in TB incidence in the ART cohort, but not in the pre-ART group. CONCLUSION: Although TB was a significant problem in ALHIV, timely administration of ART and IPT had a significant protective effect.

Effects of neonatal and adult castration and of testosterone substitution in male rats on growth of enzyme-altered hepatic foci in the resistant hepatocyte model.

Marked sex differences in the growth of enzyme-altered hepatic foci have been observed in rats treated according to the "resistant hepatocyte model." The present study was performed to investigate the effect of neonatal and adult castration of male rats, with or without testosterone substitution, on the growth rate of foci during selection of initiated cells with 2-acetylaminofluorene and partial hepatectomy. Neonatal castration of male rats decreased focal growth to the same level as in female rats. Castration of adult male rats 2 wk before initiation with diethylnitrosamine also decreased the growth rate of foci, but less markedly than in neonatally castrated rats. Testosterone substitution of male rats castrated as neonates or as adults, from 10 days after initiation with diethylnitrosamine, restored focal growth to that of sham-castrated controls. Previous investigations concerning the role of gonadal hormones in sex differentiation of various liver functions indicated a role of the hypothalamo-pituitary-liver axis in mediating the effects of androgens. It is therefore also suggested that the effects of androgens on early steps of hepatocarcinogenesis observed in the present study are mediated by similar mechanisms, possibly through an influence on the metabolism of 2-acetylaminofluorene.

Waterborne citalopram has anxiolytic effects and increases locomotor activity in the three-spine stickleback (Gasterosteus aculeatus).

Citalopram is an antidepressant drug, which acts by inhibiting the re-uptake of serotonin from the synaptic cleft into the pre-synaptic nerve ending. It is one of the most common drugs used in treatment of depression, it is highly lipophilic and frequently found in sewage treatment plant effluents and surface waters around the world. Citalopram and other selective serotonin re-uptake inhibitors have, at concentrations that occur in nature, been shown to have behavioural as well as physiological effects on fish and other animals. This study is the result of several different experiments, intended to analyse different aspects of behavioural effects of chronic citalopram exposure in fish. Our model species the three-spine stickleback is common in the entire northern hemisphere and is considered to be a good environmental sentinel species. Female three-spine sticklebacks were exposed to 0, 1.5 and 15µg/l nominal concentrations of citalopram for 21 days and subjected to the novel tank (NT) diving test. In the NT test, the fish exposed to 1.5µg/l, but not the 15µg/l fish made a significantly higher number of transitions to the upper half and stayed there for significantly longer time than the fish exposed to 0µg/l. The 15µg/l group, however, displayed a significantly lower number of freeze bouts and a shorter total freezing time. The test for locomotor activity included in the NT test showed that fish treated with 1.5 and 15µg/l displayed a significantly higher swimming activity than control fish both 5-7 and 15-17min after the start of the experiment. In the next experiment we compared fish exposed to 1.5µg/l and 0.15µg/l to pure water controls with regard to shoaling intensity and found no effect of treatment. In the final experiment the propensity of fish treated with 1.5µg/l to approach an unknown object and aggressive behaviour was investigated using the Novel Object test and a mirror test, respectively. The exposed fish ventured close to the unknown object significantly more often and stayed there for significantly longer time than unexposed fish. The aggression test yielded no statistically significant effects. It is concluded that citalopram changes the behaviour of the three-spine stickleback in a way that is likely to have ecological consequences and that it must not be considered an environmentally safe pharmaceutical.

Caring for children undergoing radiotherapy treatment: Swedish radiotherapy nurses' perceptions.

PURPOSE: The aim was to explore radiotherapy nurses' perceptions of their experiences of caring for children undergoing radiotherapy treatment for cancer. METHOD: Semi-structured interviews of 12 nurses were conducted. The interviews were analysed using a phenomenographical approach. RESULTS: All interviewees were women, and the group's mean age was 49 years. Caring for children during radiotherapy treatment was perceived as a complex task. Their perceptions included views on providing holistic care, creating a sense of security and being committed. Through holistic care the radiotherapy nurses took responsibility regarding care for the child and family, technical aspects of the radiotherapy procedure and the development of their profession. They tried to create a sense of security through individualized information and preparation, through teamwork with the child and family, and regarding anaesthetic personnel (if needed) while balancing the care they gave related to the child, to the family, to anaesthetic personnel, and to their own tasks. The radiotherapy nurses perceived themselves as committed in their care and reported being emotionally affected by sadness, but also joy. CONCLUSIONS: By clarifying radiotherapy nurses perceptions of caring for children guidelines can be developed to lessen anxiety and increase the sense of security amongst children undergoing radiotherapy treatment and their family members.

Environmentally relevant concentrations of citalopram partially inhibit feeding in the three-spine stickleback (Gasterosteus aculeatus).

Selective Serotonin Re-uptake Inhibitors (SSRI) are mood-altering, psychotropic drugs commonly used in the treatment of depression and other psychological illnesses. Many of them are poorly degraded in sewage treatment plants and enter the environment unaltered. In laboratory studies, they have been demonstrated to affect a wide range of behaviours in aquatic organisms. In this study we investigated the effect of a three-week exposure to 0.15 and 1.5 µg/l of the SSRI citalopram dissolved in the ambient water on the feeding behaviour in three-spine stickleback (Gasterosteus aculeatus). Feeding, measured as the number of attacks performed on a piece of frozen bloodworms during a 10-min period, was reduced by 30-40% in fish exposed to both 0.15 and 1.5 µg/l citalopram. The effects of the environmentally relevant concentration 0.15 µg/l on feeding, an important fitness characteristic, suggests that the ecological significance of environmental SSRI exposure may be pronounced.

Hypothalamo-pituitary regulation of the c-myc gene in rat liver.

Expression of the c-myc gene was studied in the livers of male and female Wistar rats. Furthermore, the effects on hepatic c-myc expression of neonatal and adult castration, with or without testosterone supplementation, as well as of continuous administration of GH to intact males, were analysed. Expression of c-myc was low in 6-day-old animals of both sexes, reached a maximum at 35 days of age and declined to the level of adult animals at 70 days. In prepubertal animals, expression was higher in females, but was higher in males after the onset of puberty, the postpubertal female rat liver exhibiting 50-70% of the expression in males. Treatment of adult male rats with bovine GH in osmotic minipumps for 1 week reduced c-myc expression to the level of female rats. Castration, both neonatally and of adults, also feminized hepatic c-myc expression. Testosterone supplementation of the castrated animals increased the expression towards the level in sham-operated controls. These results indicate that the c-myc gene is regulated by the hypothalamo-pituitary-liver axis via the sex-differentiated pattern of GH secretion, in analogy with other sex-differentiated hepatic functions, such as metabolism of steroids and xenobiotics. Neuroendocrine regulation of a gene such as c-myc, which is involved in the control of cell proliferation and differentiation, represents another aspect of the complex influence of GH on various somatic functions.

Expression of the c-jun, jun-B, ets-2 and liver regeneration factor-1 (LRF-1) genes during promotion and progression of rat liver carcinogenesis in the resistant hepatocyte model.

During promotion in the RH-model, the mRNA expression of c-jun and LRF-1 was 2- to 8-fold elevated in both initiated and uninitiated rats receiving 2-AAF. The increase was more pronounced in male than in female rats, and GH treatment of male rats down-regulated the expression towards the level in females. The level in uninitiated 2-AAF-treated livers was as high as in isolated early nodules. jun-B also showed 3- to 8-fold increased expression, but without sex differences. An increased nuclear transcription of the LRF-1 and jun-B genes but not of c-jun was observed. During progression, LRF-1 and ets-2 showed a 2- to 3-fold higher expression in persistent nodules and hepatocellular carcinomas than in the corresponding surrounding liver tissues, whereas the expression of the jun genes was 3- to 4-fold increased both in lesions and in surrounding livers when compared to age-matched control rats. In conclusion, while the changes during promotion might not be connected with control of early focal growth, the increased levels of LRF-1 and ets-2 in advanced lesions might indicate that these genes could contribute to the growth advantage for persistent nodules during progression.

Growth hormone administration after treatment in the resistant hepatocyte model does not affect progression of rat liver carcinogenesis.

Male and female Wistar rats were treated according to a slightly modified resistant hepatocyte model, i.e. initiation with diethylnitrosamine and selection of initiated cells with 2-acetylaminofluorene and partial hepatectomy. Two weeks after selection, rats of each sex received daily subcutaneous injections of either recombinant human growth hormone (2.5 IU/kg) or saline for 6 weeks. No effects on growth of early enzyme-altered liver lesions were recorded. The long-term part of the experiment did not show any differences due to growth hormone treatment in terms of incidence or latency time for development of either malignant liver tumors or kidney tumors. Male rats developed liver tumors more frequently than the female rats whereas a higher incidence of kidney tumors was observed in the female rats. Several different malignancies at other sites were also recorded, with no differences between the groups with or without growth hormone treatment. In conclusion, no modifying effects of human growth hormone administration during the post selection phase of the resistant hepatocyte model could be demonstrated on either tumor promotion or tumor progression.

Genetic variation in cytochrome P-450-dependent demethylation in Drosophila melanogaster.

The genetic variation in the basal capacity to N-demethylate aminopyrine, d-benzphetamine and ethylmorphine was studied in microsomes from adult Drosophila of 9 different strains. Ethylmorphine and d-benzphetamine N-demethylase activity varied about fourfold between the strains, with the highest capacity for both reactions in the Aflatoxin B1-sensitive Florida 9 and the lowest in the insecticide-resistant Hikone R. The two activities were closely correlated with each other but not with aminopyrine demethylation or any previously studied cytochrome P-450-dependent reaction, indicating a common determination by a separate cytochrome P-450 form(s). Aminopyrine N-demethylase activity was more than fourfold higher in the DDT-resistant Oregon R than in Berlin K. A genetic analysis of aminopyrine N-demethylation revealed that the high activity in the Oregon R(R) strain was inherited as an apparently semidominant second chromosome trait. The similar mode of inheritance as well as the close correlation between aminopyrine demethylase and the previously analysed biphenyl 4-hydroxylase activity suggests that these activities are under the same genetic control.

Genetic variation in cytochrome P-450 and xenobiotic metabolism in Drosophila melanogaster.

A marked genetic variation in the capacity to perform xenobiotic metabolism was observed in microsomal fractions from the seven Drosophila strains studied. A 1,5 to 2-fold variation was found in the content of cytochrome P-450 and in the NADPH-cytochrome c reductase activity. The two insecticide-resistant strains Hikone R and Oregon R differed markedly when compared to sensitive strains by having a 3 to 17-fold higher p-nitroanisole (PNA) demethylase activity and biphenyl-3-hydroxylase activity. SDS-polyacrylamide gel electrophoresis of the microsomes also revealed an increased content of a protein band with an apparent mol. wt of 54,000 in the resistant strains. The 4-hydroxylation of biphenyl was also 2-7-fold higher in the Oregon R strain, and the band with a mol. wt of 56,000 had a higher protein content compared to the other strains. The biphenyl-4-hydroxylation was several-fold lower in the strain Berlin K. 2-OH-biphenyl was formed only in trace amounts by all strains. 7-Ethoxycoumarin (EC) deethylase activity and benzo(a)pyrene (BP) monooxygenase activity was 2-6-fold lower in the Hikone R strain. An increased amount of the protein with a mol. wt of 58,000 was noted in the Canton S strain. No concomitant increase in any enzyme activity was observed. A genetic variation between the strains was observed after phenobarbital (PB) treatment in the content of cytochrome P-450 and in the various enzyme activities, varying from non-responsiveness to a 4- to 5-fold increase. Aroclor 1254 (PCB) was less efficient in enhancing the activities. It caused maximally a 3-fold increase, had often no effect and in some cases even decreased the metabolism. beta-naphthoflavone (BNF) caused only marginal increases in the activities in most strains. The only significant effects were an increased formation of 3-OH-biphenyl in Berlin K and an enhanced NADPH-cytochrome c reductase activity in Lausanne-S. In conclusion, the variations observed in this study provide a basis for further studies on the genetic regulation of the cytochrome P-450 system in Drosophila. Furthermore, similarities in the regulation when compared to mammals indicate that studies on this genetically well characterized organism might contribute to the general understanding of the genetics of xenobiotic metabolism.

Diethylnitrosamine causes pituitary damage, disturbs hormone levels, and reduces sexual dimorphism of certain liver functions in the rat.

The acute toxicity of diethylnitrosamine (DEN) to the liver has been well documented in the literature, but whether DEN also affects the endocrine parameters has been addressed in only a few studies. We thus investigated the effects of DEN on pituitary, serum hormone levels, and certain sex-differentiated liver enzymes in this study. Adult male Wister rats were intraperitoneally injected with DEN at a single dose of 200 mg/kg and were sacrificed at 1, 3, 7, and 35 days after injection; DEN-treated females were included as controls at days 7 and 35. Electron microscopic observation showed that during the first week after injection, all types of granular cells of the anterior pituitary in male animals exhibited cellular damage, including disrupted organelles and cellular structure, as well as pyknotic or lytic nuclei. Many undamaged secretory cells exhibited dilated endoplasmic reticula, hypertrophic Golgi complexes, and peripheral location of secretory granules, which usually are morphologic features of increased cellular activities. In male rats, the serum level of total testosterone decreased and the corticosterone increased 1 day after DEN treatment. The serum level of growth hormone (GH) decreased and the prolactin level increased on day 3. The hepatic expression of the male-specific cytochrome P450 2C11 (CYP2C11) decreased to 1-5% of the normal levels during the first week and was still 50% lower than the normal level on day 35, whereas the female-specific CYP2C12 expression increased only slightly. Activities of the male predominant 16alpha, 16beta, and 6beta hydroxylation of androstenedione by microsome decreased in an in vitro assay, whereas the non-sex-differentiated 7alpha hydroxylation and the female-predominant 5alpha reduction of androstenedione were unaffected. In female rats, decreased serum GH level was observed on day 7. The CYP2C12 expression in females was decreased to about 1% and 80% of the normal levels on day 7 and day 35, respectively, but the CYP2C11 expression was unchanged. These data suggest that in male rats, DEN treatment may cause pituitary damage, disturb serum hormone levels, and induce long-lasting reduction of sexual dimorphism in certain liver functions.

Genetic regulation of the cytochrome P-450 system in Drosophila melanogaster. II. Localization of some genes regulating cytochrome P-450 activity.

The localization of some genes determining the capacity for some cytochrome P-450 -dependent reactions have been studied in adult Drosophila. Strains with genetically determined high or low enzyme activities were crossed with strains carrying recessive visible markers on the chromosomes, and enzyme activities were measured in microsomes from recombinant F2 progeny. A dominantly inherited high p-nitroanisole (PNA) demethylation and biphenyl 3-hydroxylation in insecticide-resistant strains were both shown to be located around 65 cM on the second chromosome, regulated by one gene or closely linked genes. This localizes these activities to the same region as the gene responsible for the cross resistance to several classes of insecticides and a high metabolism of vinyl chloride in resistant strains. The occurrence of a regulatory gene mutation as a basis for the insecticide resistance is proposed. Hydroxylation of benzo[a]pyrene (BP) and deethylation of 7-ethoxy-coumarin seems to be determined by two third chromosome genes, at approx. 51 and 58 cM, respectively. The capacity for biphenyl 4-hydroxylation was shown to be determined by two genes on the second chromosome, one at or to the left of the gene black (48 cM) responsible for a low metabolism in strain Berlin K, and one at about 63 cM giving high formation of this metabolite in Oregon R. The latter could not be separated from the gene in insecticide-resistant strains at c:a 65 cM discussed above on the basis of the genetic localization, but observations supporting the occurrence of two closely linked genes regulating these different activities are available. In conclusion, 4-5 genes determining the capacity for several reactions, being a part of the genetic regulation of the cytochrome P-450 system in Drosophila melanogaster were indicated.

Genetic regulation of the cytochrome P-450 system in Drosophila melanogaster. I. Chromosomal determination of some cytochrome P-450-dependent reactions.

The genetic regulation of some cytochrome P-450-dependent enzyme activities has been studied in adult Drosophila. Strains having genetically determined high or low enzyme activities were crossed with a marker strain and the metabolism was analyzed in microsomes from hybrids carrying different combinations of chromosomes from the strain under test. High p-nitroanisole (PNA) N-demethylation, biphenyl 3-hydroxylation and an increased amount of a protein with an apparent mol. wt. of 54 000, after SDS-gel electrophoresis of the microsomes in insecticide-resistant Drosophila strains, are inherited as dominant second chromosome traits. A low capacity for benzo[a]pyrene (BP) hydroxylation and 7-ethoxycoumarin O-deethylation in the Hikone R strain is semidominantly inherited in both cases and determined by gene(s) on the third chromosome. A semidominantly inherited high 4-hydroxylation of biphenyl and a high amount of a protein with an apparent mol. wt. of 56 000 in the Oregon R strain are also localized to the second chromosome. The results indicate that several other cytochrome P-450-dependent activities are not regulated by the genes mentioned above. In conclusion, at least three genes regulating the cytochrome P-450 system in Drosophila have been identified.