Population based study of prevalence of islet cell autoantibodies in monozygotic and dizygotic Danish twin pairs with insulin dependent diabetes mellitus

OBJECTIVE

To study the comparative importance of environment and genes in the development of islet cell autoimmunity associated with insulin dependent diabetes mellitus.

DESIGN

Population based study of diabetic twins.

SETTING

Danish population.

SUBJECTS

18 monozygotic and 36 dizygotic twin pairs with one or both partners having insulin dependent diabetes.

MAIN OUTCOME MEASURES

Presence of islet cell antibodies, insulin autoantibodies, and autoantibodies to glutamic acid decarboxylase (GAD65) in serum samples from twin pairs 10 years (range 0-30 years) and 9.5 years (2-30 years) after onset of disease.

RESULTS

In those with diabetes the prevalence of islet cell antibodies, insulin autoantibodies, and autoantibodies to glutamic acid decarboxylase in the 26 monozygotic twins was 38%, 85%, and 92%, respectively, and in the dizygotic twins was 57%, 70%, and 57%, respectively. In those without diabetes the proportions were 20%, 50%, and 40% in the 10 monozygotic twins and 26%, 49%, and 40% in the 35 dizygotic twins.

CONCLUSION

There is no difference between the prevalence of islet cell autoantibodies in dizygotic and monozygotic twins without diabetes, suggesting that islet cell autoimmunity is environmentally rather than genetically determined. Furthermore, the prevalence of islet cell antibodies was higher in the non-diabetic twins than in other first degree relatives of patients with insulin dependent diabetes. This implies that the prenatal or early postnatal period during which twins are exposed to the same environment, in contrast with that experienced by first degree relatives, is of aetiological importance.

Relation between HLA antigens and skin cancer in renal transplant recipients in Queensland, Australia

On the basis of previous studies that showed a negative association between HLA-A11 and skin cancer in renal transplant recipients and a positive association with HLA-B27 and HLA-DR7, we performed a study in Queensland with 1098 recipients to address the question of whether the same associations could be found. The influence of HLA mismatching and HLA homozygosity on the risk of skin cancer was also studied. In contrast to earlier studies, HLA-A11 was associated with an increased risk of skin cancer. On the other hand, we confirmed that the HLA-B27 antigen was associated with the development of skin cancer, but only when the development of basal cell carcinomas alone was considered, and we confirmed that there is a weak but not statistically significant association with HLA-DR7. No association between HLA mismatching or HLA homozygosity and the development of skin cancer was observed. Environmental factors such as different levels of exposure to sunlight and infection with human papillomaviruses are factors that are most likely to be involved. We hypothesize that human papillomavirus-induced antigens prevail in the skin cancers in the recipients living in the Netherlands, whereas antigens induced by solar radiation, the so-called "photo-antigens," may be more common in the skin cancers of the recipients living in Queensland. Exposure to sunlight can also induce immunologic unresponsiveness, and excessive exposure to sunlight in Australia may, therefore, simply override the risk factors that are important in countries with a more temperate climate.

Long-term influence of insulin dependent diabetes mellitus on refraction and its components: a population based twin study

AIM

To study whether refraction of the eye, or some of its components is influenced by duration of insulin dependent diabetes mellitus.

METHODS

From the young cohort of the population based Danish Twin Register, containing 20,888 twin pairs born between 1953 and 1982, all twin pairs having one or both partners affected with IDDM were searched. Autorefraction, autokeratometry, and ultrasonic biometric measurements were carried out on 45 twin pairs: 16 monozygotic (MZ) twin pairs, 14 dizygotic twin pairs of same sex (DZss), and 15 dizygotic twin pairs of opposite sex (DZos). To obtain an estimate of the influence of duration of diabetes, the intrapair differences in duration of diabetes were correlated with intrapair differences in refraction and each of its components.

RESULTS

Refraction was statistically significantly negatively correlated with duration of diabetes in the DZss group, and axial length correspondingly positively correlated. Surprisingly, refraction and axial length in the MZ group, adjusted for confounding factors, were correlated with diabetes duration in the opposite direction than in the DZss group, although not reaching statistical significance. Lens thickness was statistically significantly positively correlated with duration of diabetes in both MZ and DZ twins. Anterior chamber depth was negatively correlated with duration of diabetes in all the zygosity groups.

CONCLUSIONS

Studies of relations between refraction and duration of diabetes show diverging results. In the MZ group, a tendency to reduced axial length and corresponding hyperopia with increasing duration of diabetes was found. However, in the DZ group of same sex the opposite tendency was found. Increasing lens thickness and decreasing anterior chamber depth with increasing duration of diabetes have been confirmed in this study.

Biphasic response of the metallothionein promoter to ultraviolet radiation in human melanoma cells

Because metallothionein (MT) is elevated and may be protective in UV-irradiated skin, we have studied the effects of UV and other agents on MT transcription using the sheep MT 1A promoter, linked to the beta-galactosidase gene and stably transfected into human cell lines. beta-galactosidase reporter activity was inducible by adding Zn2+ ions to the medium (100 microM for 2-4 h). Two differentiating agents, butyric acid and azelaic bishydroxamic acid (ABHA), significantly increased the response to Zn2+ in a melanoma cell line (MM96L-gal). UVB (280-315 nm) had two distinct, time-dependent effects. During the first 4 h after irradiation, high doses of UVB inhibited induction by Zn2+, an effect that was made more acute by simultaneous exposure to the differentiating agents. These changes in reporter activity were not due to alterations in Zn2+ transport into the cell. The UVB-depressed MT response subsequently recovered and by 24 h was double the control, yet remained sensitive to ABHA. Reporter activity in transfected HeLa cells differed from that in MM96L, being depressed 4 and 24 h after UVB and insensitive to ABHA at both times. Galactosidase reporter activity driven by non-MT promoters was not affected by these treatments. Dependence of MT transcriptional activity on UV-related DNA damage could be inferred because equitoxic UVC (254 nm) affected the response to Zn2+ in a similar fashion, whereas UVA, cisplatin and a methylating agent had no effect. The MT response was partly dependent on the PKC signal transduction pathway because it was inhibited by phorbol ester in HeLa, and by bisindolyl maleimide in HeLa and MM96L. The biphasic MT transcriptional response may model a signal transduction pathway that gives an early, depressed response to acute UV damage, with exacerbation by concurrent differentiation stimuli, but switches to a positive, cell-specific and potentially protective response at later times.

Breastfeeding, menopause, and epithelial ovarian cancer

No previous study has examined the modifying effect of menopausal status on the association between lactation and ovarian cancer risk. We recruited 824 epithelial ovarian cancer cases and 855 community controls in three Australian states, collecting reproductive and lactation histories by means of a contraceptive calendar and pregnancy and breastfeeding record. We report results in women with at least one liveborn infant for unsupplemented breastfeeding, in line with a biological model linking suppression of ovulation to reduction in ovarian cancer risk. We derived odds ratios from multiple logistic regression models including number of liveborn children, age, age at first or last birth, and other potential confounders, overall and by menopausal status. Estimates of relative risk of ovarian cancer per month of full lactation were 0.99 [95% confidence interval (CI) = 0.97-1.00] overall and 1.00 (95% CI = 0.99-1.01) and 0.98 (95% CI = 0.95-1.01) among post- and premenopausal women, respectively. We tailored a lactation variable to the incessant ovulation hypothesis by progressively discounting breastfeeding the longer after birth it occurred, finding odds ratios similar to those for the unmodified duration variable. We found no association of note among postmenopausal women. Breastfeeding seems to be somewhat protective against ovarian cancer, but only before menopause.

Population screening for the common G985 mutation causing medium-chain acyl-CoA dehydrogenase deficiency with Eu-labeled oligonucleotides and the DELFIA system

We have screened 10171 neonatal blood spots from the Trent and West Midlands regions of the UK for the common G985 mutation to more accurately establish the incidence of medium-chain acyl coenzyme (Co)A dehydrogenase (MCAD) deficiency. We have used a technique involving PCR and Eu-labeled allele-specific oligonucleotides detected by using time-resolved fluorometry on the dissociation-enhanced fluorescence immunoassay (DELFIA) system for the detection of the G985 mutation. We have also evaluated the feasibility of neonatal screening with this technique. We identified 158 G985 heterozygotes and no G985 homozygotes. The calculated incidence of MCAD deficiency in the population studied (all mutations, assuming 90% of MCAD mutations are G985) is 1 in 13426 (95% confidence limits 1 in 10070-1 in 18791). At the optimum cutoff criteria, the technique has a sensitivity of 97.5%, specificity of 99.6%, and positive predictive value of 80.2%. We conclude that this study confirms that MCAD deficiency is a common inherited metabolic disease and is a candidate for neonatal screening. The methodology used is robust and suitable for large-scale population studies such as this. The technique is also potentially suitable for screening.

[Incidence of juvenile-onset diabetes in Denmark. A prospective registration in the counties of Fyn, Ribe, Sønderjylland and Vejle]

To provide contemporary figures of the incidence of childhood onset diabetes mellitus in Denmark, a prospective routine registration system has been established. The present study covered the population of children aged 0-14 years in four Danish counties, observed during the calendar years 1989 through 1993 concerning new cases of the disease. A total of 201 cases (113 boys and 88 girls) were registered, corresponding with a sex- and age-adjusted incidence rate of 17.4 per 100,000 person-years. Based on a validation analysis the study material is considered virtually complete. Overall, the incidence among boys was slightly higher than among girls, but not statistically significantly so. The incidence rate increased with age for both boys and girls. The results confirm that the incidence of childhood onset diabetes in Denmark is relatively high. Compared with previous Danish studies there has been an increase of about 20-25% in the incidence during the last 20 years. Our study stresses the importance of a continuous registration of new cases of childhood diabetes in Denmark, thereby providing clues for further aetiological studies as well as providing reference values for the planning of the diabetes health care. Our results indicate that at least two independent ascertainment sources must be employed to ensure complete registration in studies that rely upon voluntary registration as the primary reporting source.

Acute renal failure due to postinfectious glomerulonephritis during pregnancy

Acute renal failure is a rare but potentially devastating complication of pregnancy. Among its many potential causes is acute postinfectious glomerulonephritis. We describe a case of acute renal failure during pregnancy, provide the histologic features of the renal biopsy, and discuss the differential diagnosis. Postinfectious glomerulonephritis can present rapidly after clinical infection and cause acute renal failure in pregnancy.

Ethylmalonic adipic aciduria--a treatable hepatomuscular disorder in two adult brothers

An adult male presented at 28 years of age with muscle weakness and liver dysfunction. His brother had died suddenly 2 years earlier after presenting with Reye's syndrome. Urine organic acid analysis and muscle and cultured fibroblast fatty acid oxidation studies confirmed a diagnosis of ethylmalonic/adipic aciduria-an inherited defect of fatty acid oxidation. The patient responded favourably to treatment with a low fat/high carbohydrate diet supplemented with riboflavin. This case highlights the importance of considering inborn errors of metabolism, in particular fatty acid oxidation defects, in adults with liver disease, muscle disease or Reye's syndrome.

Measurement of lactate in cerebrospinal fluid in investigation of inherited metabolic disease

Measurement of lactate concentrations in cerebrospinal fluid (CSF) has been suggested as part of the investigation of inborn errors of the electron transport chain, but little information exists regarding the reference range in children or the relationship between CSF and plasma concentrations. In 39 children without bacterial meningitis, diabetes, or recent seizures, we determined that the median (range) lactate concentrations in CSF and plasma collected concurrently were 1.4 (0.8-2.2) and 1.5 (0.6-2.3) mmol/L; the regression equation was CSF lactate = (0.38+/-0.06) plasma lactate + 0.83 (r2 = 0.14). In 8 of 11 (73%) children with electron transport chain defects, CSF lactate was > or =3.0 mmol/L; however, 2 of these 8 had a normal plasma lactate concentration. CSF lactate was also increased in 2 children with nonketotic hyperglycinemia. The finding that CSF lactate concentrations may be increased despite a normal plasma lactate value in children with electron transport chain defects is an important clue to the diagnosis of these disorders.

Inhibition of growth and induction of differentiation of metastatic melanoma cells in vitro by genistein: chemosensitivity is regulated by cellular p53

We have investigated the effect of the soybean isoflavone genistein on the growth and differentiation of human melanoma cells. Four human melanoma cell lines, either completely lacking or containing different levels of wild-type p53, were treated with genistein in vitro in culture. It has been found that genistein significantly inhibited cell growth and that the chemosensitivity might depend on cellular p53 content. Specifically, the data suggest that high levels of wild-type p53 expression make cells resistant to genistein's growth-inhibitory action. Further support for this observation came from the stable transfection studies in which p53 transfectants expressing high levels of wild-type p53 became resistant to genistein. With respect to cell differentiation, our study showed that genistein increased melanin content and tyrosinase activity and caused the cells to form dendrite-like structures. Cells lacking p53 responded more than cells with p53 to dendrite-like structure formation. We also observed that genistein-induced differentiation involved an increase in tyrosinase mRNA level; the mechanisms by which genistein increases tyrosinase transcripts remain to be elucidated. Genistein treatment of the melanoma cell lines resulted in cell cycle arrest at G2/M check point and no significant apoptosis was observed.

Dynamic imaging of functional nerve terminals and Schwann cells in presynaptic 'nerve plates' isolated from the skate electric organ

The cholinergic innervation and its glial support were isolated in a functional state from the electric organ of the skate (Raja species) using a combined enzymatic and mechanical dissociation technique. Examination using light and electron microscopy showed that this 'nerve plate' is a disc-shaped structure several hundred micrometres in diameter consisting of a dense plexus of nerve terminals attached to branching nerve fibrils with numerous associated myelinating and perisynaptic Schwann cells. In unfixed nerve plates, depolarisation and Ca2+-dependent staining of the nerve terminals was seen with RH-414, a fluorescent marker for functional motor terminals. The components of the nerve plate could be loaded with the Ca2+-sensitive dyes Fluo-3 and Fura-2. Depolarisation of nerve plates loaded with either dye leads to an immediate increase of intracellular Ca2+ levels ([Ca2+]i) in the nerve terminals. This response was blocked by certain Ca2+ channel antagonists from the -conotoxin family. Glial cell responses to depolarisation were in general minimal. However, increases of [Ca2+]i were seen in these cells, but not in nerve terminals, during applications of ATP and acetylcholine. These results show that both nerve terminal and glial elements in this 'nerve plate' preparation are functional. The ease of this preparation and its functional reliability give it considerable potential as a useful model for elucidating presynaptic mechanisms.

A medical school's plan for anti-tobacco-use education in community schools and hospitals

BACKGROUND

Tobacco use in the United States remains a significant health concern. In 1992, students at Dartmouth Medical School began a community service program that targeted the prevention of local tobacco use.

METHODS

The program combined primary prevention, through education of school-aged children, with secondary prevention, through smoking cessation clinics.

RESULTS

The program has received widespread community as well as national support for its actions. The program is in its initial stages of gathering data to determine whether there has been a significant impact on the tobacco use of the community.

CONCLUSIONS

This paper is an introduction to the program's efforts, and a potential template for other medical schools to follow.

Skin cancer in a subtropical Australian population: incidence and lack of association with occupation. The Nambour Study Group

Because it is not possible to monitor skin cancer accurately using routine methods, special surveys have been undertaken in Nambour, a typical subtropical community in Queensland, Australia. Estimates of incidence reported here are based on skin cancers medically treated between 1985 and 1992 and new cases diagnosed by dermatologists in two examination clinics in 1986 and 1992. Among men and women aged 18-69 years in 1986, age-adjusted incidence rates of basal cell carcinoma were 2,074 and 1,579 per 100,000 per year, respectively-the highest incidence rates of a specific cancer ever reported. Squamous cell carcinoma occurred at half the rate of basal cell carcinoma among men and at about one third the rate among women. Although as expected, fair skin, a history of repeated sunburns, and nonmalignant solar skin damage diagnosed by dermatologists were strongly associated with both types of skin cancer, outdoor occupation was not. Significant self-selection was observed among outdoor workers, whereby people with fair or medium complexions and a tendency to sunburn were systematically underrepresented among those in long-term outdoor occupations although they accounted for more than 80 percent of the community study sample. The mitigating effect of this selection bias may partly explain the paradox of the lack of quantitative evidence of a causal link between sun exposure and skin cancer in humans.

The Danish Conscription Registry: a resource for epidemiological research

According to the Danish constitution all Danish male citizens must appear before a Conscript Board for assessment prior to military or civil service. Conscript Board examinations have followed the same standardized procedures over many decades, and the Danish Conscript Registry represents a valuable resource for epidemiological research in Denmark. During the last two decades investigations based on information in the registry have produced significant contributions to many areas of medical science. Within the last decade new procedures and electronic data processing and storage have resulted in restricted possibilities concerning current and future utilization of the Danish Conscript Registry for epidemiological purposes. To improve this it is recommended to maintain all codes describing present illnesses and conditions together with the civic registration numbers in the computerized archive of all subjects assessed by the Conscript Board.