Sequential Markov coalescent algorithms for population models with demographic structure

We analyse sequential Markov coalescent algorithms for populations with demographic structure: for a bottleneck model, a population-divergence model, and for a two-island model with migration. The sequential Markov coalescent method is an approximation to the coalescent suggested by McVean and Cardin, and by Marjoram and Wall. Within this algorithm we compute, for two individuals randomly sampled from the population, the correlation between times to the most recent common ancestor and the linkage probability corresponding to two different loci with recombination rate R between them. These quantities characterise the linkage between the two loci in question. We find that the sequential Markov coalescent method approximates the coalescent well in general in models with demographic structure. An exception is the case where individuals are sampled from populations separated by reduced gene flow. In this situation, the correlations may be significantly underestimated. We explain why this is the case.

Highly refractile myocardial echoes in familial amyloidosis with polyneuropathy. A correlative echocardiographic and histopathological study

Two-dimensional echocardiography in systemic amyloidosis has in most cases shown highly refractile myocardial echoes. The morphological basis for this finding has so far been little examined. In the present study, echocardiographic examinations were performed in vitro on autopsied hearts from ten patients with familial amyloidosis with polyneuropathy (FAP). An ultrasonically visible needle was used to localize the abnormal echoes, and samples were taken for histological analysis of the region of the echocardiographic abnormality. Our results indicate that the highly refractile myocardial echoes in FAP are due to nodules composed of collagen and amyloid.

Myeloma-associated cardiac amyloidosis. A case report

A patient with Bence-Jones myeloma and amyloidosis was treated with cytotoxic drugs and plasmapheresis, resulting in rapid improvement of myeloma-associated symptoms and signs. However, amyloidosis-associated symptoms, especially hypotension, grew worse. Echocardiographic examination demonstrated hypertrophy and a hyperrefractile appearance of the myocardium, thought to be pathognomonic of amyloid heart disease. A permanent pacemaker was inserted for treatment of Adams-Stokes attacks caused by sick sinus syndrome and atrioventricular conduction disturbances. Postmortem examination of the heart demonstrated abundant amyloid deposits corresponding to the altered acoustic qualities of the myocardium. Echocardiographic examination is a valuable non-invasive method for demonstration of amyloid deposits in the heart in multiple myeloma.

Mercaptopurine treatment should be considered in azathioprine intolerant patients with inflammatory bowel disease

BACKGROUND

Adverse drug reactions are a significant reason for therapeutic failure during thiopurine treatment of inflammatory bowel disease. Some smaller series in this patient population have shown that a switch to mercaptopurine may be successful in many cases of azathioprine intolerance.

AIM

To assess the long-term outcome of mercaptopurine treatment in a large patient population with azathioprine intolerance.

METHODS

We identified 135 patients (74 women; median age 40 years) with Crohn's disease (n = 88) or ulcerative colitis (n = 47) and reviewed their medical records.

RESULTS

A total of 70 patients (52%) tolerated mercaptopurine and were followed up for 736 (362-1080) days; 65 patients discontinued mercaptopurine due to adverse events after 25 (8-92) days. Mercaptopurine was tolerated in 71% (12/17) with hepatotoxicity and in 68% (13/19) with arthralgia/myalgia during azathioprine treatment. Previous abdominal surgery was more common in mercaptopurine intolerant patients [39/65 (60%) vs. 27/70 (39%); P = 0.02] and thiopurine methyltransferase activity was higher in mercaptopurine tolerant patients than in mercaptopurine intolerant patients [13.2 (11.4-15.3) vs. 11.8 (9.6-14.2) U/mL red blood cells; P = 0.04; n = 81].

CONCLUSIONS

A trial of mercaptopurine should be considered in azathioprine intolerance, as half of the patients tolerate a switch to mercaptopurine. Patients with hepatotoxicity or arthralgia/myalgia during azathioprine treatment might benefit more often than those with other types of adverse events.

Effect of pimobendan or benazepril hydrochloride on survival times in dogs with congestive heart failure caused by naturally occurring myxomatous mitral valve disease: the QUEST study

BACKGROUND

Myxomatous mitral valve disease (MMVD) continues to be an important cause of morbidity and mortality in geriatric dogs despite conventional therapy.

HYPOTHESIS

Pimobendan in addition to conventional therapy will extend time to sudden cardiac death, euthanasia for cardiac reasons, or treatment failure when compared with conventional therapy plus benazepril in dogs with congestive heart failure (CHF) attributable to MMVD.

ANIMALS

Two hundred and sixty client-owned dogs in CHF caused by MMVD were recruited from 28 centers in Europe, Canada, and Australia.

METHODS

A prospective single-blinded study with dogs randomized to PO receive pimobendan (0.4-0.6 mg/kg/d) or benazepril hydrochloride (0.25-1.0 mg/kg/d). The primary endpoint was a composite of cardiac death, euthanized for heart failure, or treatment failure.

RESULTS

Eight dogs were excluded from analysis. One hundred and twenty-four dogs were randomized to pimobendan and 128 to benazepril. One hundred and ninety dogs reached the primary endpoint; the median time was 188 days (267 days for pimobendan, 140 days for benazepril hazard ratio = 0.688, 95% confidence limits [CL]=0.516-0.916, P= .0099). The benefit of pimobendan persisted after adjusting for all baseline variables. A longer time to reach the endpoint was also associated with being a Cavalier King Charles Spaniel, requiring a lower furosemide dose, and having a higher creatinine concentration. Increases in several indicators of cardiac enlargement (left atrial to aortic root ratio, vertebral heart scale, and percentage increase in left ventricular internal diameter in systole) were associated with a shorter time to endpoint, as was a worse tolerance for exercise.

CONCLUSIONS AND CLINICAL IMPORTANCE

Pimobendan plus conventional therapy prolongs time to sudden death, euthanasia for cardiac reasons, or treatment failure in dogs with CHF caused by MMVD compared with benazepril plus conventional therapy.

Short-term effects of metformin in type 2 diabetes

BACKGROUND

Although metformin is widely used in the management of type 2 diabetes, its mechanism(s) of action is not fully known, and there have been remarkably few reports on short-term effects of the drug. Here, we examined the early effects on glucose and lipid metabolism and on certain adipose tissue and inflammatory markers during treatment for 28 days.

METHODS

Twenty-one patients were randomized to metformin (n = 16) or placebo (n = 5) and studied at baseline, 1, 2 and 4 weeks with blood sampling and oral glucose tolerance tests (OGTT). The active group received 500 mg metformin daily in the first week, 500 mg twice daily during week 2 and 1000 mg twice daily during weeks 3 and 4.

RESULTS

After 7 days of treatment, a reduced area under curve (AUC) for glucose at OGTT with no change in AUC for insulin levels was observed compared to baseline. Insulin sensitivity, as derived from the OGTT by Gutt's index, was increased. Reductions in fasting plasma glucose, total cholesterol and low-density lipoprotein cholesterol appeared after 14 days, and reductions in triglycerides, plasminogen activator inhibitor-1 (PAI-1) and leptin after 28 days of treatment. There were no changes in body weight, adiponectin or C-reactive protein. Compared with placebo, the changes between day 0 and day 28 differed significantly with regard to AUC for glucose at OGTT and Gutt's index, and showed strong trends for PAI-1 and leptin.

CONCLUSIONS

The data demonstrate that in type 2 diabetes, metformin rapidly affects glucose handling without changing the concentrations of insulin. Reductions in PAI-1 and leptin levels indicate that the early effects of metformin involve also the adipose tissue.

Short-term effects of metformin in type 2 diabetes

BACKGROUND

Although metformin is widely used in the management of type 2 diabetes, its mechanism(s) of action is not fully known, and there have been remarkably few reports on short-term effects of the drug. Here, we examined early effects on glucose and lipid metabolism, and on certain adipose tissue and inflammatory markers during treatment for 28 days.

METHODS

Twenty-one patients were randomized to metformin (n = 16) or placebo (n = 5) and studied at baseline, 1, 2 and 4 weeks with blood sampling and oral glucose tolerance tests (OGTT). The active group received 500 mg metformin daily in week 1, 500 mg twice daily in week 2 and 1000 mg twice daily in week 3 and 4.

RESULTS

After 7 days of treatment, a reduced area under curve (AUC) for glucose at OGTT with no change in AUC for insulin levels was observed compared with baseline. Insulin sensitivity, as derived from the OGTT by Gutt's index, was increased. Reductions in fasting plasma glucose, total and LDL-cholesterol appeared after 14 days, and reductions in triglycerides, plasminogen activator inhibitor-1 (PAI-1) and leptin after 28 days of treatment. There were no changes in body weight, adiponectin or C-reactive protein. Compared with placebo, the changes between day 0 and day 28 differed significantly with regard to AUC for glucose at OGTT and Gutt's index, and showed strong trends for PAI-1 and leptin.

CONCLUSIONS

The data demonstrate that in type 2 diabetes metformin rapidly affects glucose handling without changing the concentrations of insulin. Reductions in PAI-1 and leptin levels indicate that the early effects of metformin involve also the adipose tissue.

Gene-history correlation and population structure

Correlation of gene histories in the human genome determines the patterns of genetic variation (haplotype structure) and is crucial to understanding genetic factors in common diseases. We derive closed analytical expressions for the correlation of gene histories in established demographic models for genetic evolution and show how to extend the analysis to more realistic (but more complicated) models of demographic structure. We identify two contributions to the correlation of gene histories in divergent populations: linkage disequilibrium, and differences in the demographic history of individuals in the sample. These two factors contribute to correlations at different length scales: the former at small, and the latter at large scales. We show that recent mixing events in divergent populations limit the range of correlations and compare our findings to empirical results on the correlation of gene histories in the human genome.

On the effect of fluctuating recombination rates on the decorrelation of gene histories in the human genome

We show how to incorporate fluctuations of the recombination rate along the chromosome into standard gene-genealogical models for the decorrelation of gene histories. This enables us to determine how small-scale fluctuations (Poissonian hot-spot model) and large-scale variations (Kong et al. 2002) of the recombination rate influence this decorrelation. We find that the empirically determined large-scale variations of the recombination rate give rise to a significantly slower decay of correlations compared to the standard, unstructured gene-genealogical model assuming constant recombination rate. A model with long-range recombination-rate variations and with demographic structure (divergent population) is found to be consistent with the empirically observed slow decorrelation of gene histories. Conversely, we show that small-scale recombination-rate fluctuations do not alter the large-scale decorrelation of gene histories.

The CTA1-DD vaccine adjuvant binds to human B cells and potentiates their T cell stimulating ability

The present study demonstrates that the novel CTA1-DD-adjuvant, which combines the full enzymatic activity of the A1 subunit of cholera toxin (CT) with an immunoglobulin-binding domain of Staphylococcus aureus protein A (SpA), binds directly to human peripheral blood B lymphocytes of all classes and greatly augments B cell functions in vitro. These effects were reflected in strongly enhanced co-stimulation, resulting in augmented T cell responses to polyclonal-specific as well as Ag-specific activation in vitro. The CTA1-DD-adjuvant had pronounced effects on B cell functions with up-regulated expression of several important activation and co-stimulatory molecules, in particular CD86. Moreover, the adjuvant alone promoted cytokine and chemokine secretion by targeted B cells and in the presence of additional stimuli proliferative responses were augmented. These effects were dependent on the whole enzymatically active CTA1-DD molecule, since DD alone had no effects on the B cells. Collectively our data suggest that CTA1-DD acted via enhanced co-stimulation, which holds promise as to the use of CTA1-DD as a non-toxic adjuvant in future vaccines for human use.

Sustained cardiomyocyte apoptosis and left ventricular remodelling after myocardial infarction in experimental diabetes

AIMS/HYPOTHESIS

Diabetes is known to reduce survival after myocardial infarction. Our aim was to examine whether diabetes is associated with enhanced cardiomyocyte apoptosis and thus interferes with the post-infarction remodelling process in myocardium in rat.

METHODS

Four weeks after intravenous streptozotocin (diabetic groups) or citrate buffer (controls) injection, myocardial infarction was produced by ligation of left descending coronary artery. Level of cardiomyocyte apoptosis was quantified by TUNEL and caspase-3 methods. Collagen volume fraction and connective tissue growth factor were determined under microscope. Left ventricular dimensions were evaluated by echocardiography and planimetry.

RESULTS

The number of apoptotic cardiomyocytes was equally high in diabetic and non-diabetic rats after 1 week from infarction. At 12 weeks after infarction the number of apoptotic cells was higher in the diabetic as compared to non-diabetic rats both in the border zone of infarction and in non-infarcted area. Correspondingly, left ventricular end diastolic diameter, relative cardiac weight, connective tissue growth factor-expression and fibrosis were increased in diabetic compared with non-diabetic rats with myocardial infarction.

CONCLUSION/INTERPRETATION

Sustained cardiomyocyte apoptosis, left ventricular enlargement, increased cardiac fibrosis and enhanced profibrogenic connective tissue growth factor expression were detected after myocardial infarction in experimental diabetes. Apoptotic myocyte loss could be an important mechanism contributing to progressive dilatation of the heart and poor prognosis after myocardial infarction in diabetes.

Effect of antisecretory factor in ulcerative colitis on histological and laborative outcome: a short period clinical trial

BACKGROUND

The antisecretory factor (AF) is a 41 kD endogenously produced protein capable of mediating protection against diarrhoea diseases and intestinal inflammation. High concentrations of AF-like proteins are present in egg yolk, and AF can consequently be administrated in the form of egg yolk drinks. In this study, performed in patients suffering from acute onset of ulcerative colitis (UC), we evaluate the influence of orally administrated AF on the histological and clinical laboratory outcome.

METHODS

A total of 20 patients fulfilled this prospective, double-blind and randomized protocol. The intake of AF was used as an additive treatment to conventional UC medication. Patient registrations were extended to two outward visits, performed 2-4 and 8-12 weeks after hospital discharge.

RESULTS

During AF treatment, a reduction in the histological severity from mucosal biopsies received from the mid-rectum was found. In addition, a lowering in the inflammatory blood parameters ESR, CRP and orosomucoid was demonstrated.

CONCLUSION

In the AF-treated group a late and significant lowering of various inflammatory parameters combined with a histological recovery was demonstrated. These findings suggest that administration of AF mediates a long-lasting anti-inflammatory effect in cases of acute UC.

DNA-dependent protein kinase in leukaemia cells and correlation with drug sensitivity

We investigated whether the levels of the DNA-dependent protein kinase (DNA-PK) activity and content correlate with drug sensitivity in different tumour materials and if this can be utilised in predicting treatment outcome. DNA-PK activity and expression were investigated in tumour cells from 8 patients with chronic lymphocytic leukaemia (CLL) and 18 patients with acute myeloid leukaemia (AML), using Western blot and DNA-PK kinase activity assay. Tumour cells from the patients were investigated for their drug sensitivity to topoisomerase II inhibitors (doxorubicin and etoposide), DNA reactive agents (melphalan, 4-hydroxycyclophosphamide and cisplatinum), an antimetabolite (cytosine arabinoside) and an antimicrotubule agent (vincristine) by fluorometric microculture cytotoxicity assay (FMCA). Within each group of leukaemia there was a large variation in both DNA-PK activity and DNA-PKcs expression, while the Ku subunits were expressed more homogeneously. In CLL cells, sensitivity to topoisomerase II inhibitors correlated with DNA-PKcs protein expression (r=0.7174, p=0.0452). In AML samples, sensitivity to DNA cross-linking alkylating agents correlated with Ku86 (r=-0.7512, p=0.0031) and Ku70 (r=-0.6134, p=0.0258) expression. Unexpectedly, DNA-PK activity was found to correlate with sensitivity to vincristine in both CLL (r=0.8557, p=0.0067) and AML (r=0.5480, p=0.0228) cells. The results indicate that DNA-PK is not only involved in the recognition of DNA double-strand breaks (DSB), but also other DNA lesions.

Arterial pulse wave velocity with tissue Doppler imaging

This paper describes a new noninvasive ultrasonic method for estimating pulse wave velocity (PWV), an important physical parameter for characterizing the elastic properties of the arterial walls. The method utilizes a relatively new color Doppler modality for measuring tissue motion (tissue Doppler imaging or TDI). In contrast to previously proposed methods, the TDI modality offers multiple recording sites along the artery that improve the PWV estimation considerably. The new PWV estimation method was evaluated through an in vitro setup consisting of an elastic vessel supplied with a pulsatile pump. The study concentrated on the effect of different system parameters controlling resolution, sensitivity and the amount of acquired data. It was shown that the system parameters have a significant effect on the PWV variance, whereas the PWV mean remains unchanged. It was also established that high temporal resolution is the most vital parameter for minimizing PWV variance. Finally, the new PWV estimation method was applied to a limited set of human carotid artery data sets, with good results.

Clinical factors and clinical variation influencing the reproducibility of interocclusal recording methods

OBJECTIVE

The reproducibility of clinical records of the occlusion was assessed in three dimensions using mounted casts. Three distinct areas were examined: 1) mandibular positions (intercuspal position (IP) or retruded contact position (RCP)), 2) materials used in recording the occlusion, 3) clinical variation.

DESIGN

Interocclusal records were made in a random order of three patients: one fixed prosthodontics case, one removable partial denture case and one complete denture case, with two different types of waxes, record rims, two different brands of vinyl polysiloxanes and one irreversible hydrocolloid.

SETTING

Private practice and Karolinska Institute, Huddinge, Sweden.

SUBJECTS

One general dental practitioner and three voluntary patients.

RESULTS

Point estimation of variance components indicate that 70-93% of the variation of the positions of the mounted casts are caused by: 1) clinical variation for all three cases and in three directions, 2) the influence of recording materials 0-29%, and 3) mandibular positions (IP/RCP) 0-11%. The ranges of the positions of the mounted casts were lower for the dentate case (0.04-1.39 mm) than for the partially dentate case (0.17-2.65 mm), which in turn was lower than those for the edentulous case (1.42-5.59 mm).

CONCLUSION

Clinical variation seems to dominate the variation in positions of mounting casts when making interocclusal records, rather than mandibular position or the recording materials used. Therefore a dentist who makes one single interocclusal record cannot presume that it will reproduce the interocclusal relationship intended, which in the present study was most obvious for the edentulous case. The results showed that impression materials stabilised by a tray did not differ significantly from waxes and record rims concerning the reproducibility. Therefore the stabilised impression materials are an alternative, which also give additional advantages like reduction of appointments as well as superior accuracy.

Statistics of selectively neutral genetic variation

Random models of evolution are instrumental in extracting rates of microscopic evolutionary mechanisms from empirical observations on genetic variation in genome sequences. In this context it is necessary to know the statistical properties of empirical observables (such as the local homozygosity, for instance). Previous work relies on numerical results or assumes Gaussian approximations for the corresponding distributions. In this paper we give an analytical derivation of the statistical properties of the local homozygosity and other empirical observables assuming selective neutrality. We find that such distributions can be very non-Gaussian.

Ventriculo-vascular interaction in the normal development of the fetal circulation

OBJECTIVES

To examine cardiovascular physiology in the healthy fetus during normal development.

DESIGN

Twenty normal fetuses were studied longitudinally from 20 weeks to term. Serial echocardiography was performed, and arterial and venous diameter pulse wave characteristics and aortic pulse wave propagation velocity (PWV) were examined in the thoracic descending aorta (AoD) and inferior caval vein (IVC) using an ultrasonic phase-locked echo-tracking system. Statistical analyses included ANOVA, paired t-test and logistic regression where appropriate.

RESULTS

Aortic PWV, maximum incremental and late decremental velocities increased with gestation while the relative pulse amplitude decreased, reflecting falling distal impedance. There was a linear increase in cardiac preload and relative pulse amplitude in the IVC with gestation that correlated significantly with the presence of end-diastolic flow in the pulmonary artery and improvement in right ventricular diastolic function.

CONCLUSIONS

Non-invasive concurrent assessment of preload, ventricular function and impedance are possible in the fetus and may prove useful in the longitudinal study of fetal adaptation to pathophysiological changes.

Mobile autopsy teams in the investigation of war crimes in Kosovo 1999

On request of the International Criminal Tribunal for the former Yugoslavia (ICTY), the Danish-Swedish forensic teams worked in Kosovo during the summer and the fall of 1999. The teams worked mainly as "mobile teams" at sites with few graves. Only two larger sites were examined. Most of the bodies were buried separately. A few "multiple burial" graves were examined, but no mass graves were encountered. The main purpose of the autopsies was to establish the cause and manner of death. Identification was of less importance, but a majority of the bodies had been identified prior to the autopsy. A total of 308 bodies, mainly males, were examined. The age varied greatly with a mean age of 47 years. The most common cause of death was gun shot wounds and the most common manner of death was homicide.