Structural basis for constitutive activity and agonist-induced activation of the enteroendocrine fat sensor GPR119

BACKGROUND AND PURPOSE

GPR119 is a Gαs-coupled 7TM receptor activated by endogenous lipids such as oleoylethanolamide (OEA) and by the dietary triglyceride metabolite 2-monoacylglycerol. GPR119 stimulates enteroendocrine hormone and insulin secretion. But despite massive drug discovery efforts in the field, very little is known about the basic molecular pharmacology of GPR119.

EXPERIMENTAL APPROACH

GPR119 receptor signalling was studied in transfected cells. Mutational mapping (30 mutations in 23 positions) was performed on residues required for ligand-independent and agonist-induced GPR119 activation (AR231453 and OEA). Novel Rosetta-based receptor modelling was applied, using a composite template approach with segments from different X-ray structures and fully flexible ligand docking.

KEY RESULTS

The increased signalling induced by increasing the cell surface expression of GPR119 in the absence of agonist and the inhibitory effect of two synthetic inverse agonists demonstrated that GRP119 signals with a high degree of constitutive activity through the Gαs pathway. The mutational maps for AR231453 and OEA were very similar and, surprisingly, also similar to the mutational map for residues affecting the constitutive signalling - albeit with key differences. Surprisingly, almost all residues in extracellular loop-2b were important for the constitutive activity. The molecular modelling and docking demonstrated that AR231453 binds in a 'vertical' pocket in between mutational hits reaching from the centre of the receptor out to extracellular loop-2b.

CONCLUSIONS AND IMPLICATIONS

The high constitutive activity of GPR119 should be taken into account in future drug discovery efforts, which can now be guided by the detailed knowledge of the physiochemical properties of the extended ligand-binding pocket.

Mutational effects on conformational changes of the dephospho- and phospho-forms of the Na+,K+-ATPase

Gly263 of the rat kidney Na(+),K(+)-ATPase is highly conserved within the family of P-type ATPases. Mutants in which Gly263 or the juxtaposed Arg264 had been replaced by alanine were expressed at high levels in COS-1 cells and characterized functionally. Titrations of Na(+),K(+), ATP, and vanadate dependencies of Na(+),K(+)-ATPase activity showed changes in the apparent affinities relative to wild-type compatible with a displacement of the E(1)-E(2) conformational equilibrium in favor of E(1). The level of the K(+)-occluded form was reduced in the Gly263-->Ala and Arg264-->Ala mutants, and the rate constant characterizing deocclusion of K(+) or Rb(+) was increased as much as 20-fold in the Gly263-->Ala mutant. Studies of the sensitivity of the phosphoenzyme to K(+) and ADP showed a displacement of the E(1)P-E(2)P equilibrium of the phosphoenzyme in favor of E(1)P, and dephosphorylation experiments carried out at 25 degrees C on a millisecond time scale using a quenched-flow technique demonstrated a reduction of the E(1)P to E(2)P conversion rate in the mutants. Hence, the mutations displaced the conformational equilibria of dephosphoenzyme and phosphoenzyme in parallel in favor of the E(1) and E(1)P forms. The observed effects were more pronounced in the Gly263-->Ala mutant compared with the Arg264-->Ala mutant. Leu332 mutations that likewise displaced the conformational equilibria in favor of E(1) and E(1)P were also studied. Unlike the Gly263-->Ala mutant the Leu332 mutants displayed a wild-type like rate of K(+) deocclusion. Thus, the effect of the Gly263 mutation on the E(1)-E(2) conformational equilibrium seems to be caused mainly by an acceleration of the K(+)-deoccluding step, whereas in the Leu332 mutants the rate of the reverse reaction seems to be reduced.

A comprehensive genetic study of streptococcal immunoglobulin A1 proteases: evidence for recombination within and between species

An analysis of 13 immunoglobulin A1 (IgA1) protease genes (iga) of strains of Streptococcus pneumoniae, Streptococcus oralis, Streptococcus mitis, and Streptococcus sanguis was carried out to obtain information on the structure, polymorphism, and phylogeny of this specific protease, which enables bacteria to evade functions of the predominant Ig isotype on mucosal surfaces. The analysis included cloning and sequencing of iga genes from S. oralis and S. mitis biovar 1, sequencing of an additional seven iga genes from S. sanguis biovars 1 through 4, and restriction fragment length polymorphism (RFLP) analyses of iga genes of another 10 strains of S. mitis biovar 1 and 6 strains of S. oralis. All 13 genes sequenced had the potential of encoding proteins with molecular masses of approximately 200 kDa containing the sequence motif HEMTH and an E residue 20 amino acids downstream, which are characteristic of Zn metalloproteinases. In addition, all had a typical gram-positive cell wall anchor motif, LPNTG, which, in contrast to such motifs in other known streptococcal and staphylococcal proteins, was located in their N-terminal parts. Repeat structures showing variation in number and sequence were present in all strains and may be of relevance to the immunogenicities of the enzymes. Protease activities in cultures of the streptococcal strains were associated with species of different molecular masses ranging from 130 to 200 kDa, suggesting posttranslational processing possibly as a result of autoproteolysis at post-proline peptide bonds in the N-terminal parts of the molecules. Comparison of deduced amino acid sequences revealed a 94% similarity between S. oralis and S. mitis IgA1 proteases and a 75 to 79% similarity between IgA1 proteases of these species and those of S. pneumoniae and S. sanguis, respectively. Combined with the results of RFLP analyses using different iga gene fragments as probes, the results of nucleotide sequence comparisons provide evidence of horizontal transfer of iga gene sequences among individual strains of S. sanguis as well as among S. mitis and the two species S. pneumoniae and S. oralis. While iga genes of S. sanguis and S. oralis were highly homogeneous, the genes of S. pneumoniae and S. mitis showed extensive polymorphism reflected in different degrees of antigenic diversity.

Side effects associated with pneumococcal vaccination

BACKGROUND

Pneumococcal disease is a major cause of morbidity and death, especially among elders and other people at high risk. In spite of long-standing national recommendations for its use, pneumococcal vaccine is underused, with 70% or more of targeted persons as yet unimmunized. Concern about side effects is a barrier to successful vaccine delivery.

METHODS

Persons attending a walk-in pneumococcal vaccination clinic were surveyed by use of structured telephone interviews. They were asked about health characteristics and local and systemic symptoms experienced during the week after their vaccination (postvaccination period). These responses were compared with the symptoms they reported for the 7 days immediately preceding their interview (the comparison period).

RESULTS

A total of 1006 persons were interviewed a mean of 65.4 days after their vaccination. They had an average age of 69.9 years, and approximately 95% were in a high-risk group targeted for pneumococcal vaccination. For all systemic symptoms including fever, rash, myalgias, fatigue, malaise, and headache, subjects reported similar or lower rates during the postvaccination week than during the comparison week. Local reactions occurred in 28.2% of subjects. These local symptoms were mild to moderate for more than 90% of subjects and rarely resulted in the need to decrease the use of their arm.

CONCLUSION

Pneumococcal vaccination was not associated with an increase in systemic symptoms but was associated with mild to moderate local symptoms in about one fourth of vaccine recipients. These findings should help health care providers and their patients address an important barrier to pneumococcal immunization.

Influenza vaccination of healthcare workers

OBJECTIVE

To assess factors associated with influenza vaccination of healthcare workers.

DESIGN

Cross-sectional survey.

SETTING

University-affiliated Veterans' Affairs medical center.

PARTICIPANTS

Staff physicians and nurses employed by the medical center.

METHODS

A mailed, self-administered questionnaire.

RESULTS

The response rate was 38.0%. The mean age of the respondents was 43.6 years, 71.5% were females, and 26.2% were physicians. Nearly all of the practitioners had daily or weekly contact with elderly or high-risk patients. The influenza vaccination rate of the respondents was 61.2%. More than 50% of vaccine recipients indicated that avoiding illness, protecting patients, and being able to receive the vaccine conveniently and free of charge all were very important factors influencing their decisions to receive the vaccine. Avoiding illness was rated the most important factor by 58.8% of vaccine recipients. Among vaccine nonrecipients, concern about side effects was identified as a very important factor by 36.2% and as the most important factor by 30.9%. Vaccine recipients were significantly more likely than were vaccine nonrecipients to indicate that influenza and its complications are very serious for high-risk patients. They also were more likely to report that the vaccine is very effective, that influenza vaccination is uncommonly associated with side effects, that healthcare workers' risk for contracting influenza is higher than the general public's risk, and that it is very important for healthcare workers to receive the vaccine to decrease risk for transmission to high-risk patients. After stepwise logistic regression, variables independently associated with receipt of vaccine were age, prior receipt of vaccine, being a physician, considering the vaccine to be very effective, believing that systemic side effects are uncommon, and indicating that it is very important for healthcare workers to receive vaccine for the protection of their patients.

CONCLUSION

Many healthcare workers fail to receive influenza vaccine each year. Strategies to improve immunization levels should address concerns about vaccine safety and efficacy, barriers to vaccination including inconvenience and cost, and the reasons for targeting healthcare workers.

Factors associated with influenza and pneumococcal vaccination behavior among high-risk adults

OBJECTIVE

This cross-sectional survey assessed factors associated with influenza and pneumococcal vaccination behaviors among high-risk patients exposed to highly organized vaccination programs.

INTERVENTIONS

Self-administered questionnaires were mailed to 700 patients randomly selected from the outpatient roster of the medical center. Questions were asked about patient demographic and health characteristics in addition to their knowledge and attitudes regarding influenza and pneumococcal diseases and vaccines.

MAIN RESULTS

After three mailings, the response rate was 68%, and 80% of these respondents were in a high-risk ++group. Influenza and pneumococcal vaccination rates for high-risk respondents were 74.4% and 62.5%, respectively. Factors independently associated with both influenza and pneumococcal vaccination behaviors included health care providers' recommendations and having positive attitudes toward immunization. In addition, for influenza vaccination, willingness to comply with the provider's recommendation was also associated with receipt of the vaccine while cigarette smoking was associated with failure to receive the vaccine.

CONCLUSIONS

Emphasis on provider recommendations and the knowledge and attitudes of patients may enhance influenza and pneumococcal vaccination rates, even in the context of organized vaccination programs.

Side effects associated with influenza vaccination in healthy working adults. A randomized, placebo-controlled trial

BACKGROUND

Concern about side effects is a barrier to influenza vaccination. This randomized, double-blind, placebo-controlled trial assessed side effects following vaccination among healthy working adults.

METHODS

Healthy working adults were recruited during October and November 1994 and were randomized to receive influenza vaccine or placebo injections. Local and systemic symptoms during the week following the injection were evaluated through structured telephone interviews.

RESULTS

Of 849 subjects enrolled in the study, 425 received a placebo and 424 received influenza vaccine. Baseline characteristics were similar between the groups, and 99% of subjects completed interviews to assess side effects after the study injection. No differences were seen between the 2 groups for the systemic symptoms of fever, myalgias, fatigue, malaise, or headaches. Overall, 35.2% of placebo and 34.1% of vaccine recipients reported at least 1 of these systemic symptoms (P = .78, chi 2). Vaccine recipients reported a higher rate of arm soreness at the injection site than did placebo recipients (63.8% vs 24.1%, P < .001). Local reactions were mild in both groups and infrequently resulted in decreased use of the arm. After logistic regression, female sex (odds ratio [OR], 1.5;95% confidence interval [CI], 1.1-2.1), age younger than 40 years (OR, 1.6;95% CI, 1.2-2.2), and coincidental upper respiratory tract illness (OR, 4.6; 95% CI, 3.2-6.6) were independently associated with higher rates of systemic symptoms. In the multivariate model, vaccine again was not associated with systemic symptoms (OR, 0.9; 95% CI, 0.7-1.2).

CONCLUSIONS

Influenza vaccination of healthy working adults is not associated with higher rates of systemic symptoms when compared with placebo injection. These findings should be useful to physicians and other health care providers as they counsel patients to take advantage of an important opportunity for disease prevention and health protection.

Population structure of Streptococcus agalactiae reveals an association between specific evolutionary lineages and putative virulence factors but not disease

To evaluate the genetic diversity and relationships in a collection of 85 Danish strains of Streptococcus agalactiae (group B streptococcus) we have performed restriction fragment length polymorphism analysis on EcoRI- and MspI-digested whole-cell DNA using as probes rRNA, DNA fragments representing the genes encoding hyaluronidase, C5a-peptidase, alpha-antigen, and beta-antigen as well as two randomly selected genomic DNA fragments for which the coding potential is unknown. In addition, we have assayed for expression of hyaluronidase activity and beta-antigen. Combined analyses of our data and those previously obtained by multilocus enzyme electrophoresis and serotyping revealed a population separating into six major lineages that correlate with individual serotypes. The significant linkage disequilibrium of alleles indicates that the S. agalactiae population examined is predominantly clonal. Notably, strains expressing the serotype III capsule divide into two distant evolutionary lineages, of which one lacks expression of hyaluronidase activity. Six North American isolates of serotype III clustered together with multiple Danish serotype III strains, showing that the combinations of characters on which the phylogenetic tree was based are conserved worldwide. Occurrence of beta-antigen correlated with a specific version of the alpha-antigen gene and was exclusively associated with a single major phylogenetic lineage. Comparisons with the clinical history of the strains revealed no evidence of differences in pathogenic potential among the six major genetic divisions.

The effectiveness of vaccination against influenza in healthy, working adults

BACKGROUND

Although influenza causes substantial morbidity and mortality in all age groups, current recommendations emphasize annual immunization for people at high risk for complications of influenza. We conducted a double-blind, placebo-controlled trial of vaccination against influenza in healthy, working adults.

METHODS

In the fall of 1994, we recruited working adults from 18 to 64 years of age from in and around the Minneapolis-St. Paul area and randomly assigned them to receive either influenza vaccine or placebo injections. The primary study outcomes included upper respiratory illnesses, absenteeism from work because of upper respiratory illnesses, and visits to physicians' offices for upper respiratory illnesses. The economic benefits of vaccination were analyzed by estimating the direct and indirect costs associated with immunization and with upper respiratory illnesses.

RESULTS

We enrolled a total of 849 subjects. Baseline characteristics were similar in the two groups. During the follow-up period, consisting of the 1994-1995 influenza season (December 1, 1994, through March 31, 1995), those who received the vaccine reported 25 percent fewer episodes of upper respiratory illness than those who received the placebo (105 vs. 140 episodes per 100 subjects, P < 0.001), 43 percent fewer days of sick leave from work due to upper respiratory illness (70 vs. 122 days per 100 subjects, P = 0.001), and 44 percent fewer visits to physicians' offices for upper respiratory illnesses (31 vs. 55 visits per 100 subjects, P = 0.004). The cost savings were estimated to be $46.85 per person vaccinated.

CONCLUSIONS

Vaccination against influenza has substantial health-related and economic benefits for healthy, working adults.

An epidemiological study of congenital anorectal malformations: 15 Danish birth cohorts followed for 7 years

In the county of Fyn (about 500,000 inhabitants) which is a well defined and representative 10% sample of the total Danish population, 15 total birth cohorts were scrutinized for the occurrence of anorectal malformations (ARM). All the patients were followed until the age of 7 or death. In a total of 96,073 births, 29 cases were observed; one concordant monozygotic pair was counted as one case. The study showed the point prevalence at birth to be 3.0 per 10,000; almost the same frequency has been found in Sweden whereas other figures from Europe and North America are lower. Children with ARM have in general a poor prognosis, largely due to the many associated anomalies. In this material, 11 of 12 isolated ARM cases survived until age 7, but five of these had significant handicaps. Out of 17 probands with associated anomalies, only seven survived until age 7, all of them having some handicap. This group of patients spent at least 15 times more days in hospital than an age-matched group from the same region until age 7, and they underwent a considerable number of operations. The study showed an increased frequency of chromosome anomalies among children with ARM.

Evaluation of zygosity diagnosis in twin pairs below age seven by means of a mailed questionnaire

The mothers of a consecutive series of 125 same sexed pairs of twins aged 6 months to 6 1/2 years completed a mailed questionnaire concerning the physical similarity of the twin partners. Zygosity diagnoses were first determined blindly on the basis of the answers given by the mothers, who did not know the result of the blood group test when fulfilling the questionnaire. Next, the results were compared with the zygosity determination based on examination of erythrocyte-, serum- and enzyme-groups. It turned out that a few simple questions distinguished well enough between MZ and DZ pairs, with a frequency of misclassification of 4%, leaving 5% as unclassifiable. It is concluded that twin zygosity can be estimated by a simple questionnaire with sufficient accuracy even in very young twin pairs. This has relevant implications for more extensive twin studies where the use of a wide spectrum of serological characters would imply too high expenses.

Osteogenesis imperfecta: a genetic, radiological, and epidemiological study

The point prevalence at birth of osteogenesis imperfecta was estimated by a systematic search of all children born 1. I. 1970 to 31. XII. 1983 in the county of Fyn (Denmark). Additionally, the population prevalence on 31. XII. 1983 of all patients with osteogenesis imperfecta in this county was determined. The county is a well-defined, representative subregion of Denmark which demographically comprises a cross-section including about 9% of the Danish population. Altogether, the study disclosed 48 patients with osteogenesis imperfecta. Of these, 17 patients were born 1. I. 1970 to 31. XII. 1983 and 12 had type I, 2 had type II, 2 had type III, and 1 had type IV. Thus, the point prevalence at birth was 21.8/100,000 and the population prevalence was 10.6/100,000 inhabitants. There was great variation in the clinical manifestations within and between the types.

Congenital generalised bone dysplasias: a clinical, radiological, and epidemiological survey

The point prevalence at birth of generalised bone dysplasias was estimated by a study of all children born between 1 January 1970 and 31 December 1983 in the county of Fyn (Denmark). Additionally the population prevalence on 31 December 1983 of all patients with generalised bone dysplasias in this county was determined. The county is a well defined, representative subregion of Denmark which demographically comprises a cross section of about 9% of the Danish population. In total, bone dysplasias were found to be more frequent than generally assumed. Achondroplasia was, however, less common with a point prevalence at birth of 1.3 per 100,000, while osteogenesis imperfecta (21.8), multiple epiphyseal dysplasia tarda (9.0), achondrogenesis (6.4), osteopetrosis (5.1), and thanatophoric dysplasia (3.8) were found more frequently. It is striking how many bone dysplasias are still erroneously classified as achondroplasia. Correct diagnosis is important for a valid prognosis, for treatment, and for genetic counselling. The diagnosis relies almost exclusively on the radiographical findings.

Cystic fibrosis in Denmark 1945 to 1985. An analysis of incidence, mortality and influence of centralized treatment on survival

The entire population of cystic fibrosis (CF) patients in Denmark diagnosed in the period January 1, 1945, to June 30, 1985, comprised 514 persons of whom 62 were diagnosed at autopsy. Of the remaining 452 patients, 372 were probands and 80 were secondary cases. The effect of a centralized treatment on the prognosis was evaluated using a Cox's regression model. Furthermore an incidence analysis was performed using probands including autopsies. Centralized treatment had a significantly beneficial effect on the prognosis (p = 0.02), the death intensity (hazard rate) being decreased by a factor of 0.60. It was calculated that at present 1 out of 4,760 newborn Danes may be diagnosed as suffering from CF before the age of 15 years, and 3% of the Danish population are heterozygotes for CF.

Dyssegmental dysplasia in siblings: prenatal ultrasonic diagnosis

Two cases of dyssegmental dysplasia (type Silverman-Handmaker) in siblings are presented. The first-born died at the age of 3 months and the second fetus was followed during pregnancy with ultrasound examinations. In the 20th week of gestation marked shortening of the extremities was found; a female infant showing the same radiologic bony malformations as the firstborn was born by cesarean section. These cases support the autosomal recessive inheritance and demonstrate the possibility of prenatal diagnosis in this type of micromelic dwarfism.

A cohort study of neural tube defects (NTD) in Denmark covering the first seven years of life

In the County of Fyn, Denmark, which is a well-delimited region comprising a 10% representative sample of the total population, ten complete one year cohorts of newborn were scrutinized for neural tube defects (NTD). Among 66,000 births, 71 cases with NTD were observed. The total prevalence at birth was 1.08/1,000; 0.29 for anencephaly; 0.20 for encephalocele, and 0.59 for spina bifida (SB). This is at the same level as in other Scandinavian countries. Considering only neonates born alive, 57% of the total survived until the age of 7 years, disregarding anencephaly, but only 4 of 18 SB cases and 6 of 11 encephalocele cases had no handicaps at age 7. On the average, SB patients spent 9% of their life before the age of 7 years in hospitals and encephaloceles 2%. The SB cases occupied 25 times more beds per year than the comparable age group in general and many were likely to need continued medical and social care.

Prevalence of fasting hyperglycemia and known non-insulin-dependent diabetes mellitus classified by plasma C-peptide: Fredericia survey of subjects 60-74 yr old

A Danish population of 5699 individuals (60-74 yr old) was screened by fasting blood glucose (FBG) and interviewed about known diabetes. The distribution of FBG in individuals not known to have diabetes showed no sex difference or significant variation with age. Fasting hyperglycemia (FH), defined as FBG greater than or equal to mM in subjects without a history of diabetes, was found in 1.7% of men and women. Known diabetes (KD) had a prevalence of 3.9 and 5.0% in men and women, respectively. The prevalence rates of FH and KD increased significantly with age. In the two subgroups, plasma C-peptide was measured after overnight fasting and subsequently 6 min after an intravenous injection of glucagon. Based on the distribution of the C-peptide concentrations in non-insulin-treated KD subjects, lower limits for non-insulin-dependent diabetes mellitus (NIDDM) of 0.30 pmol/ml for fasting C-peptide and 0.60 pmol/ml for stimulated C-peptide were arbitrarily chosen. According to these cutoff points, only 38.5% of KD subjects treated with insulin had insulin-dependent diabetes mellitus, corresponding to 9.3% of all KD subjects. After exclusion of these patients, the prevalence of recognized NIDDM was 3.5% in men and 4.5% in women. All FH subjects except one had C-peptide values in the NIDDM interval. A close agreement between fasting and glucagon-stimulated C-peptide was seen. In epidemiological studies with an expected high prevalence of NIDDM, we propose to use fasting C-peptide for classification of patients with insulin-treated diabetes.

Facial clefts in sibs and children of epileptic patients

The prevalence of facial clefts in sibs and children of 2,072 epileptics ascertained in a defined region was determined by record linkage with a national cleft register, which also provided expected figures. Observed/expected ratios were increased only for cleft lip with or without cleft palate if the mother had manifested epilepsy: it was 4.7 when anticonvulsants were given before and during pregnancy, 2.7 in cases with no treatment, and zero in children born prior to maternal epilepsy. Children of epileptic men and sibs of epileptics showed no increase. The prevalence of isolated cleft palate was not above expectation in any group.

The incidence and prevalence of familial polyposis coli in Denmark

Based on the Danish Polyposis Register, the frequency of familial polyposis coli was estimated at the end of 1982. The mean annual incidence rate of polyposis coli has remained rather constant at approximately 1 X 10(-6) X yr-1 since the forties. The life-time risk of developing polyposis coli is about 1 X 10(-4). The point prevalence rate was 26 X 10(-6) at the end of 1982. The number of cases found in sibs and children of probands made it probable that a nation-wide prophylactic examination of first degree relatives resulted in a complete identification of affected family members. The completeness of the Danish Polyposis Register in the period 1976-82 was estimated to be 90% and the validity of the diagnosis is considered to be 100%.

Congenital heart defects in live-born children of epileptic parents

In a study of congenital heart defects (CHD) in 2,461 live-born children of an unselected group of 979 male and 1,093 female epileptics, 18 children with CHD were recorded; eight had epileptic fathers and 10 epileptic mothers. The prevalence of CHD does not differ significantly from that of the background population. Many different CHD types were recorded with no single defect being predominant. Likewise, no association with a specific type of anticonvulsant treatment was noted. The fact that the prevalence of CHD among children of male and female epileptics and of the background population was similar supports the view that antiepileptic treatment is no major factor in the etiology of CHD in the off-spring of epileptics.

An alternative sampling approach to the study of diabetes prevalence

Sampling methods hitherto used in epidemiological surveys have generally faced two major sorts of potential bias: a latent period between listing and testing of listed individuals which can cause a misrepresentation of the population under study, compared with the population basis; population migration and death during the study period, which may result in a discrepancy between the population selected for study and the part of the population examined. A Central Population Register, found in all Scandinavian countries, permits an evaluation of the size of these problems of bias and makes it possible to use an alternative sampling method based on test samples successively drawn from the actual dynamic population. The feasibility of this new approach was tested in an epidemiological survey of diabetes mellitus among individuals in the age group 60-74 years living in a Danish municipality (Fredericia). It is concluded that this alternative dynamic method produces a more representative study population with less bias, thanks to the smaller number of deaths and migration among non-responders during the study, than do the methods previously used. Furthermore, the length of the study period, the size of the test samples, as well as the intervals between selecting samples may be adjusted to the capacity available, thus reducing the resources required. By using a correction in the computer program for selecting test sample size, the sex and age profile of the whole study population may be chosen in accordance with the incidence of the disease studied. In the Scandinavian countries a unique possibility exists to carry out prevalence studies on all kinds of diseases by the method described and evaluated here.

Genetic studies of insulin-dependent diabetes mellitus: segregation and linkage analyses

The inclusion of HLA data in genetic studies of insulin-dependent diabetes mellitus (IDDM) has not led to conclusive segregation models for IDDM so far. As a new approach, we first applied complex segregation analysis, independently of HLA data, to two combined Danish family materials. Then the best fitting segregation model was entered into linkage analysis of a third material, including family as well as HLA data. The best solution obtained in the segregation analysis was a mixed model, including an intermediate gene, which on the penetrance scale acts as a recessive, together with a polygenic component. The linkage analysis showed an overall recombination fraction of 0.0417 with high coupling frequencies for the HLA-DR3 and HLA-DR4 alleles and the putative disease susceptibility gene. However, when the pedigrees were divided according to whether or not the proband had the heterozygous HLA-phenotype DR3/DR4, a maximum likelihood ratio test for heterogeneity was significant, with estimated recombination fractions of 0.0 and 0.0963 in HLA-DR3/DR4 pedigrees and the remaining pedigrees, respectively. In total, we found convincing evidence that two familial factors contribute to IDDM: a locus within HLA, which very well may be DR; and an unlinked mechanism which is unimportant for HLA-DR3/DR4 but simulates recombination. If confirmed, this conclusion has important implications for further genetic studies of IDDM and complex segregation analyses of family materials sampled according to criteria which include HLA data of the probands are highly needed.

HLA-D and -DR antigens in genetic analysis of insulin dependent diabetes mellitus

Three groups of patients with insulin-dependent diabetes mellitus, ascertained by different procedures, were investigated for HLA-A, B, C and D antigens (n = 164), and a subset (n = 93) for HLA-DR. Both HLA-D/DR3 and D/DR4 were strongly positively associated and D/DR2 was negatively associated with insulin-dependent diabetes. HLA-DR+ was found to be a better marker for insulin-dependent diabetes than Dw4. The HLA-B associations (B8, B15 and B18) were clearly secondary to the increases of HLA-D/DR3 and D/DR 4. The HLA associations did not differ between familial and isolated cases indicating that these two groups may well have a common genetic background. Based on analysis of HLA-haplotype sharing in affected sibling pairs, a simple dominant model of inheritance could be ruled out, and a simple recessive model was found unlikely. The relative risks for the HLA-Dw3,4 and HLA-DR3,4 phenotype were 21.2 and 44.4 respectively and exceeded those of both the HLA-Dw3 and HLA-DR3 (5.6 and 4.3) as well as the HLA-Dw4 and DR4 (10.1 and 10.5) phenotypes. This argues against an intermediate genetic model but further studies are needed to clarify whether there is more than one susceptibility gene for insulin-dependent diabetes mellitus within the HLA-system.

Facial clefts among epileptic patients

Anticonvulsants have been suspected of teratogenicity, with facial clefts being the malformation most frequently associated with maternal anticonvulsant therapy. Paternal epilepsy has also been suggested as a factor in the genesis of birth defects, including facial clefts. An association between epilepsy per se and facial clefts would be reflected in a higher facial cleft prevalence among epileptics, and consequently result in an increase of such malformations among their children. The prevalence of facial clefts was determined in an unselected group of 3,203 epileptic probands: their personal data were cross-matched with a complete file of Danish facial cleft patients born between 1934 and 1977. Eleven epileptic probands had a facial cleft, which is twice the expected number. The increased prevalence of cleft defects among epileptics could partly explain why more of their children have facial clefts.

Epidemiological studies of diabetes mellitus in Denmark. II. A prevalence study based on insulin prescriptions

The study aimed at tracing the population of insulin-treated diabetics living in the Funen County, Denmark (approximately 450000 inhabitants) on 1 July 1973. It was based on a recording of insulin prescriptions among all prescriptions handled by the pharmacies in Funen County during a five-month period. Through information from medical records and public registries the verification of the diagnosis and the identity of the insulin prescription holders were checked, and it is estimated that the completeness of the study material was above 98%. Age- and sex-specific prevalence rates of insulin-treated diabetes mellitus were calculated. The overall prevalence rate for males was 3.6 per 1,000 and that for females 3.3 per 1,000.

Epidemiological studies of diabetes mellitus in Denmark. I. A case finding method based on the National Service Conscript Registry

To provide unbiased material for epidemiological studies of diabetes mellitus a case finding method based on the Danish National Service Conscript Registry and death certificates is presented and discussed. Eight Danish total male birth cohorts, totalling 320 162 persons, have been observed as to the occurrence of diabetes mellitus during the first twenty years of life, and it is concluded that the conscript registry represents an ideal basis for case identification, if the individual cases are further elucidated. The material is estimated to be about 95% complete. The main source of error originates from omissions when the registries are scrutinized. The cumulative incidence rates for the birth cohorts range from 1.3 to 3.2 per thousand; in the total material 2.4 per thousand.

Etiologic factors of breast cancer elucidated by a study of unselected twins

The Danish Twin Register consists of the total population of twin pairs born in Denmark during a certain period. Within this population were found 50 monozygotic (MZ) female twins belonging to 45 MZ pairs and 81 dizygotic (DZ) twins belonging to 77 DZ female pairs, of which at least 1 twin had breast cancer (BC) and both twins were alive at the time of the first BC diagnosis. In 5 MZ and 4 DZ pairs, both partners had BC. Pairwise concordance rates were not significantly different between the 2 groups of twins but were of the same magnitude as in a previous study. The heritability, evaluated by genetic determination, was estimated to be 0.30-0.40. The observed number of BC cases developing in the co-twins after the first BC diagnosis in the twin pairs was increased by a factor of nearly 6 in MZ co-twins and by a factor of about 2 in DZ co-twins. For cancer of other sites, the observed and expected numbers were nearly identical in both MZ and DZ co-twins. In 8 of 9 pairs concordant for BC, the lesion was found on the same side. The mean age at diagnosis showed no significant difference between the concordant and discordant pairs. In the 40 MZ pairs with only 1 twin affected, she was more often unmarried and/or nulliparous than her unaffected, genetically identical co-twin, but this finding was not significant. A general tendency for the twin with BC to have the first child at a later age than her unaffected twin sister could not be demonstrated.

Renal transplantation and cancer in the Scandiatransplant material

Scandinavian material is presented, consisting of 3,875 transplanted patients and containing 128 patients in whom cancer was diagnosed. In a subgroup of 566 first-time transplanted Danish patients, there was a significantly increased incidence of tumours compared with the Danish population, a correlation between tumour frequency and mismatch in HLA-A and in HLA-B, a correlation to chronic interstitial nephritis, but no correlation to the occurrence of lymphocytotoxic antibodies or to sex difference between donor and recipient. In this material there is evidence indicating that the presence of constant stimulation by alloantigens leading to chronic immunostimulation, with possible loss of the suppressor function of lymphocytes towards the development of malignant tumours, is an important factor in the development of tumours in transplanted patients.

Prenatal diagnosis of polycystic kidneys and encephalocele (Meckel syndrome)

Two unrelated families are presented with repeated occurrences of a congenital syndrome of which the main stigmata were polycystic kidneys and occipital encephalocele (Meckel syndrome). Prenatal diagnosis, followed by interruption of pregnancy, was performed in one case. The diagnosis was based on an increase of amniotic alpha-fetoprotein (AFP), and on the mode of growth and cell types of cultured amniotic cells. In another similarly examined case the diagnosis was suspected, but the parents did not wish the pregnancy to be interrupted. The child was stillborn and malformed. AFP values are presented and discussed in relation to the observed malformations. Neural tube defects are associated with an increase of AFP in amniotic fluid, but, as in normal pregnancies, the values decrease with increasing gestational age. On the other hand, kidney malformations seem to be associated with AFP values which remain high or even increase with increasing gestational age.

Metacarpal morphometry in monozygotic dizygotic elderly twins

The relative importance of genetic factors in the pathogenesis of age related bone loss has been investigated in a study involving 17 monozygotic (MZ) and 8 dizygotic (DZ) pairs of twins aged 64 to 75 years. Radiographic morphometry was performed at the midpoints of the 2nd, 3rd and 4th metacarpals of both hands and the mean total and cortical widths were evaluated. The heritability, h2, was calculated as the difference between the intrapair variances in same sexed DZ and MZ pairs divided by the intrapair variance in DZ pairs. The mean intrapair variance of both total and cortical width was found to be four to five times higher in DZ than in MZ pairs. The differences are highly significant with an h2 value between 0.7 and 0.8, indicating a predominant genetic influence. It is stressed that this result applies only to the population from which the twin sample was drawn.

A Danish twin study of manic-depressive disorders

The existence of a nation-wide twin register and central psychiatric register has made possible a catamnestic investigation of an unselected and representative sample of twins with manic-depressive disorders. From a total population of 11,288 same-sexed twin pairs born 1870-1920 in Denmark 126 probands from 110 pairs were ascertained. Among the co-twins of 69 monozygotic probands there were found 46 with manic-depressive disorders, and a further 14 had presented other psychoses or marked affective personality disorders or had committed suicide, yielding a proband rate of strict concordance, C1 = 0-67 and of broad, partial concordance, C2 = 0-87. The corresponding direct pairwise concordance rates were 32/55 = 0-58 and 46/55 = 0-84 respectively. For the dizygotic twins the proband concordance rate of C1 was 11/54 = 0-20 and of C2 20/54 = 0-37, and the direct pairwise rates were 9/52 = 0-17 and 18/52 = 0-35 respectively. The differences between the pairwise rates for the monozygotic and dizgotic twins are significant (P less than 0-001 at X2 analysis). This finding is in accordance with previous twin studies of manic-depressive disorders and confirms the evidence of a strong genetic factor. The concordance with respect to unipolar and bipolar forms was not in contradiction to recent evidence of a genetic difference between the bipolar and unipolar form, the latter probably related to the female sex.

The value of fluorescence markers in the distinction between maternal and fetal chromosomes

Selected fluorescence markers of chromosomes were studied in 50 paired samples of cells obtained by culture of amniocentesis material and by culture of leukocytes from pregnant women. Comparative analyses showed that this method is of great value in disclosing admixture of maternal cells to material obtained by amniocentesis, as a minimum of 2 fluorescence marker differences between mother and fetus was found in the present material. The distribution of markers in mother/fetus pairs is in agreement with the assumption of genetic determination. Variation was observed between populations with respect to the frequency of the markers studied.

Renal transplantation and cancer. The Scandia transplant material

Between 1965 and 1973, 30 malignant tumours were found in patients transplanted in Scandinavia. Of these tumours, 24 were found in the 1,254 patients transplanted in Scandinavia as part of the Scandia Tranplant Programme between 1969 and 1972. Using the information recorded in the programme, 418 Danish patients who received their first and only transplant between 1969 and 1972 were selected and followed until 31/12 1973. Twelve tumours occurred in these patients. A comparison with the expected age, sex and time-specific incidence rates from the Danish Cancer Register was made and the observed tumour incidence was found to be significantly (P less than 0.001) greater than expected. Tumour incidence was found to be associated with incompatibility in the FOUR series, but was unrelated to number of rejections, the presence of HL-A antibodies and sex difference between donor and recipient. Apart from certain special forms of immunosuppression which could be oncogenic, the cause of tumour development appears to be multifactorial, both the allograft itself and immunosuppressive treatment playing a role.

Amylo-1,60glucosidase deficiency (glycogenosis type III) in the Faroe Islands

Seven cases of glycogenosis type III (amylo-1,6-glucosidase deficiency) in two probably related families from the Faroe Islands are presented. The group of patients comprised two pairs of sibs. In a total of 78 members of the two families case histories were obtained and clinical examinations, analyses of amylo-1,6-glycosidase activity in erythrocytes and leucocytes, determinations of red cell, serum and enzyme groups as well as HL-A types were performed. In addition, all patients were subjected to studies of liver function. The distribution patients in these families supports the assumption of autosomal recessive inheritance. Heterozygotes could not be diagnosed with certainty by the methods of enzyme activity analysis employed. The incidence of glycogenosis type III with amylo-1,6-glucosidase deficiency was found to be high in the Faroe Islands.

Sex-linked hereditary thrombocytopenia with immunological defects

14 cases of severe thrombocytopenia in one family are presented. Case histories, clinical examination, analyses of platelets, haemoglobin, reticulocytes, leucocytes, eosinophilocytes, differential counts of leucocytes, serum immunoglobulin IgA, IgM, IgG, IgE concentrations, complement fixing platelet antibodies, isohaemagglutinins, colour perception, determination of red cell and serum groups as well as HL-A types were obtained from a total of 59 members of the family. The in vitro blast transformation response of blood lymphocytes was studied in 6 patients and 45 relatives. The pattern of transmission of the disease was in full agreement with X-linked recessive inheritance. Investigation of the immune system revealed impaired responses to microbial antigens in the 6 patients so studied. All relatives examined had normal haematological status, whereas approximately half showed a subnormal response to one microbial extract. The low responders were evenly distributed within the family, and it was not possible to correlate low response and presumed carrier state.