A selective sweep in a microsporidian parasite Nosema-tolerant honeybee population, Apis mellifera.

Nosema is a microsporidian parasite of the honeybee, which infects the epithelial cells of the gut. In Denmark, honeybee colonies have been selectively bred for the absence of Nosema over decades, resulting in a breeding line that is tolerant toward Nosema infections. As the tolerance toward the Nosema infection is a result of artificial selection, we screened chromosome 14 for a selective sweep with microsatellite markers, where a major quantitative trait locus (QTL) had been identified to be involved in the reduction in Nosema spores in the honeybees. By comparing the genetic variability of 10 colonies of the selected honeybee strain with a population sample from 22 unselected colonies, a selective sweep was revealed within the previously identified QTL region. The genetic variability of the swept loci was not only reduced in relation to the flanking markers on chromosome 14 within the selected strain but also significantly reduced compared with the same region in the unselected honeybees. This confirmed the results of the previous QTL mapping for reduced Nosema infections. The success of the selective breeding may have driven the selective sweep found in our study.

Reproductive division of labour and thelytoky result in sympatric barriers to gene flow in honeybees (Apis mellifera L.).

Determining the extent and causes of barriers to gene flow is essential for understanding sympatric speciation, but the practical difficulties of quantifying reproductive isolation remain an obstacle to analysing this process. Social parasites are common in eusocial insects and tend to be close phylogenetic relatives of their hosts (= Emery's rule). Sympatric speciation caused by reproductive isolation between host and parasite is a possible evolutionary pathway. Socially parasitic workers of the Cape honeybee, Apis mellifera capensis, produce female clonal offspring parthenogenetically and invade colonies of the neighbouring subspecies A. m. scutellata. In the host colony, socially parasitic workers can become pseudoqueens, an intermediate caste with queenlike pheromone secretion. Here, we show that over an area of approximately 275.000 km², all parasitic workers bear the genetic signature of a clone founded by a single ancestral worker genotype. Any gene flow from the host to the parasite is impossible because honeybee workers cannot mate. Gene flow from the parasite to the host is possible, as parasitic larvae can develop into queens. However, we show that despite sympatric coexistence for more than a decade, gene flow between host and social parasite (F(st) = 0.32) and hybridizations (0.71%) are rare, resulting in reproductive isolation. Our data suggest a new barrier to gene flow in sympatry, which is not based on assortative matings but on thelytoky and reproductive division of labour in eusocial insects, thereby suggesting a new potential pathway to Emery's rule.

Outbreeding and possibly inbreeding depression in a pollinating fig wasp with a mixed mating system.

Mixed mating systems are somewhat of an enigma as most models predict that organisms should either inbreed when inbreeding depression is low, or outbreed when inbreeding depression is high. Many wasps mix routine inbreeding with a little random mating. This random mating is most common when all local sibmating opportunities are exhausted and dispersal is the only way males can further increase their fitness. The males of the pollinating fig wasp, Platyscapa awekei, are slightly different in that they disperse before all sibmating opportunities have been exhausted. To see if this is a response to inbreeding depression we quantify inbreeding depression by comparing females' life time reproductive success to their heterozygosity at multiple microsatellite loci. We find that a female wasp's heterozygosity is an accurate predictor of her inbreeding coefficient and that P. awekei females actually seem to suffer from outbreeding depression and possibly from a little inbreeding depression. Male dispersal is thus not a means to effect the optimal mating system, but more likely a mechanism to reduce competition among brothers. The number of mature offspring a female produces depends on her own heterozygosity and not on that of the offspring, and may be determined by egg and gall quality.

Liver histopathology of the hepatitis A virus infection: a comparison with hepatitis type B and non-a, non-b.

Liver biopsies from 86 patients with serologically established acute hepatitis A were evaluated for quantitative and qualitative light microscopic features together with biopsies from 78 patients with acute hepatitis type B and 76 patients with acute hepatitis type non-A, non-B. Hepatitis A was characterised by more pronounced portal inflammation than hepatitis non-A, non-B (p less than 0.01) but less conspicuous parenchymal changes (focal necrosis, Kupffer cell proliferation, acidophil bodies, ballooning) than found in hepatitis type B (p less than 0.01). Steatosis occurred in 10% of the hepatitis A biopsies compared with 26% (p less 0.01) and 6% (not significant) in the hepatitis non-A, non-B and B groups, respectively. A comparison between the histological findings in women and men revealed that iron deposits occurred in more than half of the men compared to less than 20% of the women (p less than 0.01) irrespective of hepatitis type. Histological and biochemical follow-up was available in 36 patients with hepatitis A. For the majority of these patients the bilirubin concentration reached normal values within one month of the initial biopsy. The activity of serum transaminases showed good correlation with the degree of histological resolution. Non-specific reactive hepatitis with slightly raised serum transaminases were often seen during recovery from hepatitis A. These patients may be misinterpreted as cases of acute non-A, non-B hepatitis.

Hepatitis A, B, and non-A, non-B in Danish hospital nursing staff.

A stratified age matched sample of 564 general hospital nurses, assistant nurses, and porters was studied for antibody to hepatitis A virus (anti-HAV), hepatitis B surface antigen (HBsAg), and antibody to hepatitis B surface antigen (anti-HBs), and these data were compared with serum aspartate aminotransferase (AST) and identified episodes of hepatitis. The overall prevalence of anti-HBs was increased twofold compared with blood donors, while no evidence of increased exposure to hepatitis A virus was found. The serological survey showed porters to have a significantly higher prevalence of hepatitis A virus (52%) as well as hepatitis B virus (10.2%) markers compared with the nurses and assistant nurses (39% and 5.3% respectively). In contrast, the clinical data showed the incidence of hepatitis to be four times higher in nurses than in the two other groups during hospital employment. The serological survey may reflect differences in social background of the groups, while the clinical data identified nurses as having the highest occupational hepatitis risk. A number of episodes of hepatitis in nurses appeared to be due to non-A, non-B agents. AST values, however, did not show any case of liver inflammation not attributable to alcohol. Thus chronic non-A, non-B infections could not be shown in this population group.

Hepatitis B and A virus antibodies in alcoholic steatosis and cirrhosis.

Sera from 74 alcoholics with cirrhosis and 63 alcoholics with steatosis were tested for antibody to hepatitis B surface antigen, to hepatitis B core antigen, and to hepatitis A virus by radioimmunoassay or enzyme-linked immunosorbent assay. No significant difference between the two groups of alcoholics could be found concerning the prevalence of these antibodies. The total group of patients had antibody to hepatitis B surface antigen or hepatitis B core antigen, or both, significantly (p less than 0.001) more often (26%) than sex- and age-matched controls (4%). No significant difference was found between patients and controls concerning the prevalence of antibody to hepatitis A virus (46% v 40%). In patients with cirrhosis, no correlation between wedged hepatic vein pressure or wedged-to-free hepatic vein pressure and any of the viral antibodies could be established. The present results suggest that hepatitis B virus does not play a major role in the progression of alcoholic liver disease, but longitudinal studies are needed to solve this problem. The reason for the increased prevalence of antibodies to hepatitis B virus in these patients is unknown.

Significance of anti-HBc IgM in the differential diagnosis of viral hepatitis.

IgM antibody to hepatitis B core antigen (anti-HBc IgM) as determined by IgM capture immunoassay is generally present in high titer during acute hepatitis B infection. A strong positive reaction for anti-HBc IgM during acute hepatitis is indicative of an acute HBV infection even in hepatitis B surface antigens (HBsAg)-negative patients. With the help of anti-HBc IgM otherwise unidentified HBV infection can be diagnosed in HBsAg-negative patients and an optimal combination of diagnostic tests for acute hepatitis B infection would therefore include assays for both HBsAg and anti-HBc IgM. In the HBsAg carrier with or without chronic liver disease the presence and meaning of anti-HBc IgM is still a matter for discussion. Detection of a weak positive result for anti-HBc IgM in HBsAg-positive patients without a recent history of acute hepatitis cannot always be regarded as a definite marker of recent hepatitis B infection. However, quantitation of the anti-HBc IgM results seems to improve the clinical value of the test. Comparison of the available anti-HBc IgM assays is needed and may well establish a reliable cut-off level that would differentiate acute from chronic hepatitis B and ongoing from resolving hepatitis B in HBsAg-positive patients.

Supervised endurance exercise training compared to home training after first lumbar diskectomy: a clinical trial.

OBJECTIVE: We performed a randomised trial to evaluate if intensive supervised training of the back should be offered to all patients after a first lumbar diskectomy. METHODS: Forty consecutive patients were, after a first lumbar diskectomy, randomly allocated to 2 groups undergoing "supervised training" twice a week for 3 months in an outpatient clinic or "home training" after 2 hours of instruction. RESULTS: The two rehabilitation models both showed a significant effect on spinal mobility, isokinetic trunk flexion strength, isokinetic trunk extension strength and daily function. These improvements were unchanged at follow up 3 months later. The pain score remained unchanged, however, throughout the trial in both groups. No differences in effect between the two rehabilitation models could be found for any of the assessed parameters. Thirteen patients did not complete the trial, including 9 from the supervised endurance trained group, mainly because of increased pain and reprolaps (n = 4). Four patients dropped out of the home trained group, only one because of increased pain. The differences in drop-out rate and training side effects were, however, not statistically significant. CONCLUSION: We conclude that it is not worthwhile to implement 3 months of supervised intensive endurance training as opposed to home training in all cases of first lumbar diskectomy, although a beneficial effect and better compliance might be found for a selected group of such patients.

The influence of previous low back trouble, general health, and working conditions on future sick-listing because of low back trouble. A 15-year follow-up study of risk indicators for self-reported sick-listing caused by low back trouble.

STUDY DESIGN: A 15-year follow-up study. OBJECTIVE: To find risk indicators for self-reported sick-listing because of low back trouble and to evaluate which variables were the most important indicators of work incapacity resulting from low back trouble during the follow-up period of 15 years. SUMMARY OF BACKGROUND DATA: The initial data were obtained from a health survey conducted in a general population from the Municipality of Glostrup, Denmark. The follow-up data included information from the Central Person Register, the Early Retirement Pension Register, and a postal questionnaire regarding self-reported sick-listing because of low back trouble. METHODS: An epidemiologic study, in which logistic regression analyses were used for evaluation of the data. The model used consisted of the variable in question, age, gender, and previous experience of low back trouble, along with interactions. RESULTS: It was found that 22 of 37 variables were risk indicators for later self-reported sick-listing because of low back trouble during the preceding year or the 7 years before the date of follow-up evaluation. In analyzing the most significant variables simultaneously, it was found that information from the initial investigation about sick-listing in general during the previous 10 years, sciatic pain, use of analgesics for low back trouble, previous sick-listing because of low back trouble, and occupation were the most important risk indicators for self-reported work incapacity resulting from low back trouble during the follow-up period of 15 years. CONCLUSION: Findings showed that the strongest prognostic indicators of later sick-listing because of low back trouble involve information from the person about previous sick-listing behavior in general and previous experience of low back trouble episodes, especially if these had been accompanied by sciatic pain, use of analgesics, or previous low back trouble sick-listing.

Exercises for chronic low back pain: a clinical trial.

Different training models are effective for the treatment of chronic low back pain, but no consensus has been found. Earlier studies have emphasized training of spinal mobility and back strength. To evaluate if other physiological parameters, such as coordination, are of equal importance, we performed a randomized trial on 40 consecutive patients with chronic low back pain. Two training models were compared: 1) intensive training of muscle endurance and 2) muscle training, including coordination. In both groups, training was performed 1 hour twice a week for 3 months. Pain score, disability score, and spinal mobility improved in both training groups without differences between the two groups. Only intensive training of muscle endurance improved isokinetic back muscle strength. At study entry, we found a significant correlation between spinal mobility and dysfunction, but after the training, no correlation was found between improvement of spinal mobility or isokinetic back extension strength and improvement of function or pain level. We conclude that coordination training for patients with chronic low back pain is as equally effective as endurance training.

Double blind placebo controlled trial of pulse treatment with methylprednisolone combined with disease modifying drugs in rheumatoid arthritis.

OBJECTIVE: To assess whether monthly treatment with intravenous methylprednisolone enhances or accelerates the effect of disease modifying drugs in patients with rheumatoid arthritis. DESIGN: A 12 month double blind, placebo controlled, multicentre trial in which patients with active rheumatoid arthritis were randomly allocated to receive pulses of either methylprednisolone or saline every four weeks for six months. At the start of the pulse treatment all patients were started on penicillamine or azathioprine. SETTING: Four rheumatology departments in Denmark. PATIENTS: 97 Patients (71 women, 26 men) aged 23-84 (mean 60) who had active rheumatoid arthritis of at least four weeks' duration despite treatment with non-steroidal anti-inflammatory drugs. MAIN OUTCOME MEASURES: Monthly clinical recording of morning stiffness, number of tender and swollen joints, blinded observers' evaluation of therapeutic effect, and patients' self assessed condition. Concomitant laboratory measurements of erythrocyte sedimentation rate and concentrations of C reactive protein and haemoglobin. Radiography to determine the number of erosions at the start of treatment and after 12 months. RESULTS: 57 Patients completed the trial, taking the same disease modifying drug throughout. Evaluation four weeks after each pulse treatment and at 12 month follow up showed no significant differences between the methylprednisolone and placebo groups in any of the clinical or laboratory variables. Radiography showed the same degree of progression of erosions in both groups. Evaluation of the total data on 97 patients and on the 57 who completed the trial showed the same lack of significance between the treatment groups. CONCLUSIONS: Intravenous pulse treatment with steroids can be recommended only for rapid temporary relief of flares of disease in patients with rheumatoid arthritis. The response is short lived. Repeated pulses of methylprednisolone at four week intervals do not improve the results of treatment with drugs that induce remission such as penicillamine and azathioprine.

[Risk factors for development of low back pain]. / Risikofaktorer for udvikling af laenderygsmerter.

The incidence, severity and potential disability of low back pain are related, in particular, to previous back complaints, heavy lifting and the general psychosocial environment and to the physical constitution of the individual, viz the endurance of his back muscles. Recommendations for approach to the problem in future are discussed.

[Alternative treatment of patients with rheumatism. The extent, effect and utilization of resources]. / Alternativ behandling af reumatologiske patienter. Udbredelse, effekt og ressourceforburg.

An anonymous questionnaire investigation involving 393 rheumatological patients showed that 185 patients (47%) had tried alternative treatment (52% of the women and 33% of the men). The three forms of treatment most commonly employed were chiropractor treatment, zone therapy and acupuncture. The 185 patients had, on an average, tried 2.2 types of treatment and 30% had tried more than two forms of treatment. One third of the patients had tried alternative treatment before or simultaneously with medical treatment while the remaining 2/3 had received medical treatment from weeks up to several years. The sources of information about alternative treatment were, most frequently, friends and relatives (70%) while in 16%, the general practitioner was the source. Only 58% replied to the question about the effect of the alternative treatment. Out of these, 56% had experienced improvement, 41% stated that there was no effect and 2% stated that deterioration had occurred. On an average, the patients had employed 2,444 Danish crows (approximately 200 pounds) for the alternative treatment. In addition, 6% stated that had spent more than 10,000 Danish crowns (approximately 833 pounds). It is concluded that alternative treatment frequently constitutes a considerable economical stress for the patients. Greater frankness and a increased level of information about the alternative forms of treatment are necessary.

[Osteoporotic fractures of the spine in elderly women. Risk factors, inducing factors and course]. / Osteoporotisk fraktur i columna hos aeldre kvinder. Risikofaktorer, udløsende faktorer og forløb.

Forty-seven women with osteoporotic fractures of the spine were examined consecutively. The age range was 64-91 years with a median of 77 years. Risk factors for osteoporosis such as induced menopause or gastric resection were not present. Four patients had had rheumatoid arthritis. 19% had been treated with glucocorticoid. Only one patient had received long-term oestrogen treatment. The patients had been physically very active at a younger age and 91% had been occupationally employed. The symptoms frequently commenced with a fall or strain by lifting at home. The average period of hospitalization was 22 days. Thirty-four patients were followed-up after 6-12 months. All of them experienced pain and 74% still took analgesics. Fifteen out of the 19 patients who had been fitted with a supportive corset still employed this.

[Epidural glucocorticoid injection in lumbago sciatica]. / Epidural glukokortikoidinjektion ved lumbago-iskias.

Within the past decades, epidural steroid injections have been used in the treatment of severe low back pain and sciatica. In reviewing papers for this article an effort is made to concentrate on those that meet commonly accepted research design criteria, such as being blinded, randomized and prospective. The risks and the advantages of the procedure are discussed. Some of the studies report an efficient reduction in low back pain and sciatica for a longer period. Risks of more serious complications are low using the right technique. However, the results are to some extent conflicting. Future correctly designed studies are necessary to clarify whether the injection should be a supplement to the established treatment of low back pain and sciatica.

[Back problems during military service--significance for later back problems. A 12-year follow-up study]. / Rygbesvaer under aftjening af vaernepligt--betydning for senere rygproblemer. En 12-års followup-undersøgelse.

One thousand and fifty-eight conscripts participating in an investigation of back problems among conscripts in 1979-80 were re-examined 12 years later with an identical questionnaire concerning back problems. The questionnaire was answered by seven hundred and eighty-four persons (74%). The lifetime prevalence for low-back trouble was 73%, the one-year prevalence 53% and the point prevalence 26%. At the time of follow-up the incidence of low-back trouble depended on ever having had back pains and on having an X-ray made because of back problems. The probability for sick leave from work caused by lowback trouble was increased when back troubles had been reported at the time of the initial investigation. A significant amount of the conscripts that had been rejected due to back problems (60%) had been unfit for work because of low-back trouble in the follow-up period, and 95% of them had had low-back trouble in the year before follow-up, compared to 51% of the other conscripts. Previous back trouble increases the risk of getting back trouble once again. The risk of sick leave from work caused by low-back trouble increases with the incidence of back trouble up to the investigation in 1979-80. Rejection from service due to back problems increases the risk of later low-back trouble and sick leave from work caused by low-back troubles.