Mechanical evaluation of the effect of the rod to rod distance on the stiffness of uniplanar external fixator frames.

PURPOSE: To investigate the effect of the rod-to-rod distance on the mechanical stability of single-rod and double-rod external fixator frames. METHODS:  Four different constructs, one single-rod and three double-rod constructs with different rod-rod distances, were subjected to the axial, bending, and torsional forces. The stiffness of different configurations was calculated. RESULTS:  Single-rod configuration had statistically the lowest stiffness when subjected to the axial, bending, and torsional forces. Maximum stiffness against the axial and anterior-posterior bending forces was achieved when the rod-rod distance was adjusted to 50 mm (halfway between the first rod and the end of the Schanz pins). There was no statistically significant difference in lateral bending stiffness among different double-rod configurations (p value: 0.435). The maximum stiffness against torsional forces was achieved when the rod-rod distance was adjusted to 100 mm (the second rod at the end of the Schanz pins). CONCLUSION:  Double-rod uniplanar external fixator frames are significantly stiffer than the single-rod constructs, and however, the rod-rod distance can significantly affect the construct stiffness. We found that a frame with 50 mm rod-rod distance was the optimum fixator among tested configurations that allowed a balance between axial, bending, and torsional stiffness of the construct.

Live attenuated Leishmania major p27 gene knockout as a novel vaccine candidate: A study on safety, protective immunity and efficacy against canine leishmaniasis caused by Leishmania infantum.

Canine leishmaniasis (CanL) is an important parasitic e disease caused by Leishmania infantum and is transmitted by female phlebotomine sand flies primarily between canines and secondarily to humans. Recently, we showed that immunization with Leishmania major p27 gene knockout (Lmp27-/-) as a live attenuated vaccine was safe, induced immunogenicity, and protected against the development cutaneous and visceral leishmaniasis in mice. The p27 protein is a component of the COX protein complex which is responsible for ATP production. In this study, we analyzed the Lmp27-/- candidate vaccine potential with this regard to the safety and induction of immunogenicity and protection against CanL. Variables such a clinical manifestation, anti-Leishmania antibodies using direct agglutination test (DAT), lymphocyte proliferation, delayed-type hypersensitivity (DTH), bone marrow aspiration (BMA) and parasite burden using parasitological and molecular examinations were measured. The results demonstrated that the Lmp27-/- vaccinated group showed no clinical signs after inoculation with Lmp27-/- mutant during a 12-month follow-up, and had significantly higher T-cell responses (Lymphocyte proliferation and DTH), lower seroconversion and parasite burdens following a challenge inoculation with L. infantum after 6-mounth. In conclusion, vaccination with Lmp27-/- parasites would be safe and provide significant immunoprotectivity and efficacy against infection with wild type (WT) L. infantum.

The effect of attentional instructions during modeling on gaze behavior and throwing accuracy in 7 to 10 year-old children.

Research has shown the effectiveness of attentional instructions and observation on the performance and learning in children. However, there is little research on the effects of instruction that manipulates attentional focus during observation. The purpose of the study was to investigate performance following instructions that directed an individual to focus internally or externally during the viewing of a model. Eye tracking was also used to investigate the visual search strategy under different instructional groups. 24 children between the ages of 7 and 10 years were randomly divided into an internal (IFM) or external (EFM) modeling group. Children performed a 10-trial pre-test to measure throwing accuracy and quiet eye duration (QED). Following pre-test, children observed a model performing the correct overarm throw 10 times while eye movement was recorded. They then performed a 10-trial post-test. Results revealed that both groups improved accuracy from pre-test to post-test (p < .001) and increased QED from pre- to post-test (p < .001). It was also observed that EFM had greater accuracy and (p = .01) and longer QED (p < .001) than IFM during post-testing. Evidence was also observed for adherence to the attentional focus strategy as EFM and IFM looked more frequently at the specific cue provided (p < .001). Directing visual attention to the movement effects while observing a model significantly benefits motor performance and learning in children. Changing the focus of instruction to an external focus improved both throwing accuracy and increased QED.

Molecular and heterogeneous water oxidation catalysts: recent progress and joint perspectives.

The development of reliable water oxidation catalysts (WOCs) is essential for implementing artificial photosynthesis on a large technological scale. WOC research has evolved into two major branches, namely molecular and heterogeneous catalysts. Manifold design principles and plenty of mechanistic insights have been developed in these individual fields after decades of investigations. Over the past years, a growing need for knowledge transfer between both sides has emerged in order to expedite the development and optimization of next-generation WOCs. In this review, we first provide selected recent highlights in the area of molecular WOCs with different nuclearities, together with current mechanistic insight. WOCs offering molecular integrity under operational conditions are ideal platforms for elucidating reaction mechanisms and well-defined structure-function correlations at the atomic level. Next, recent mechanistic advances and design strategies for heterogeneous WOCs are illustrated for representative examples, together with a discussion of their inherent limitations in mechanistic studies. Finally, illustrative cases of knowledge transfer between molecular and heterogeneous WOCs are discussed to highlight the advantages of combining the best of both catalyst types. For the sake of conciseness, this review focuses primarily on WOCs based on the first-row transition metals, which are attracting increasing attention for both fundamental studies and economic applications.

Type 1 diabetes genetic risk score discriminates between monogenic and Type 1 diabetes in children diagnosed at the age of <5 years in the Iranian population.

AIM: To examine the extent to which discriminatory testing using antibodies and Type 1 diabetes genetic risk score, validated in European populations, is applicable in a non-European population. METHODS: We recruited 127 unrelated children with diabetes diagnosed between 9 months and 5 years from two centres in Iran. All children underwent targeted next-generation sequencing of 35 monogenic diabetes genes. We measured three islet autoantibodies (islet antigen 2, glutamic acid decarboxylase and zinc transporter 8) and generated a Type 1 diabetes genetic risk score in all children. RESULTS: We identified six children with monogenic diabetes, including four novel mutations: homozygous mutations in WFS1 (n=3), SLC19A2 and SLC29A3, and a heterozygous mutation in GCK. All clinical features were similar in children with monogenic diabetes (n=6) and in the rest of the cohort (n=121). The Type 1 diabetes genetic risk score discriminated children with monogenic from Type 1 diabetes [area under the receiver-operating characteristic curve 0.90 (95% CI 0.83-0.97)]. All children with monogenic diabetes were autoantibody-negative. In children with no mutation, 59 were positive to glutamic acid decarboxylase, 39 to islet antigen 2 and 31 to zinc transporter 8. Measuring zinc transporter 8 increased the number of autoantibody-positive individuals by eight. CONCLUSIONS: The present study provides the first evidence that Type 1 diabetes genetic risk score can be used to distinguish monogenic from Type 1 diabetes in an Iranian population with a large number of consanguineous unions. This test can be used to identify children with a higher probability of having monogenic diabetes who could then undergo genetic testing. Identification of these individuals would reduce the cost of treatment and improve the management of their clinical course.

Association of dietary patterns and risk of cardiovascular disease events in the MASHAD cohort study.

BACKGROUND: Cardiovascular disease (CVD) is the principal cause of mortality and disability in Iranian adults. We aimed to evaluate the relationship between dietary patterns and CVD incidence in a large sample of adults in northeastern Iran. METHODS: The present study comprised a prospective study of 5706 CVD-free men and women aged 35-65 years who participated in a cohort study. All of the participants were followed up for a 6-year period. Dietary patterns were derived from a 65-item validated food frequency questionnaire and the factor analysis method was used to determine dietary patterns. RESULTS: We identified two major dietary patterns: (i) a Balanced dietary pattern (a high intake of green leafy vegetables, other vegetables, fruits, dairy products, red meats, poultry, seafoods, legumes and nuts, as well as a low intake of sugar) and (ii) a Western dietary pattern (a high intake of sugar, tea, egg, snacks, fast foods, potato, carbonated beverages, pickled foods, organs meat and butter) by factor analysis. The hazard ratio (HR) and 95% confidence intervals (CIs) of total CVD in the highest versus lowest tertiles of the Balanced pattern were 1.29 (95% CI = 0.67-2.47; P = 0.44). The HR and 95% CIs of CVD in the highest versus lowest tertiles of Western pattern were 2.21 (95% CI = 1.08-4.45; P = 0.03). CONCLUSIONS: During the 6-year follow-up, we found that adherence to a Balanced dietary pattern was not significantly associated with CVD events. However, adherence to a Western dietary pattern was associated with a significantly increased risk of CVD events and its associated risk.

Essential oils improved weight gain, growth and feed efficiency of young dairy calves fed 18 or 20% crude protein starter diets.

The objective was to evaluate interactions between starter protein (180 vs. 200 g/kg, DM basis) and a mixture of essential oils (EOs; containing thymol, eugenol, vanillin, limonene and guaiacol) on growth, metabolic and ruminal functions of Holstein dairy calves. In a completely randomized 2 × 2 factorial design, 48 calves, 3 days old (averaging BW 42.7 ± 1.9 kg), were allocated into groups fed the following diets: (i) 180 g/kg CP with no EO (180P-NEO); (ii) 180 g/kg CP with EO (180P-EO); (iii) 200 g/kg CP with no EO (200P-NEO); and (iv) 200 g/kg CP with EO (200P-EO). The EO was supplemented as 1 g/kg of starter DM. Calves were fed ad libitum starter diet and were weaned at day 59 of age, but diets continued until day 80. There were no interactive effects of CP and EO on intake and growth. Pre-weaning feed efficiency tended to be increased for 200P-EO (p = .09). Average daily gain and feed efficiency during pre-weaning period as well as weaning weight were increased (p < .05) by EO, whereas wither height was increased by EO (p = .03) and tended to be increased for 200P vs. 180P (p = .06). Post-weaning blood urea nitrogen concentration tended to be lower in 180P vs. 200P (p = .08). Ruminal short-chain fatty acids concentration was greatest in 200P-EO. The EO increased both butyrate (p = .02) and propionate proportions (p = .01) and reduced acetate proportional ratio (p < .01). Ruminal ammonia-N was tended to be lower in calves-fed EO (p = .05) and was lower in those fed 180P vs. 200P (p < .01). In conclusion, supplementation of the starter diet with essential oil improved weight gain, growth and feed efficiency of dairy calves, irrespective of dietary protein content.

Expression and localisation of RXFP3 in human spermatozoa and impact of INSL7 on sperm functions.

Insulin-like peptide 7 (INSL7) or relaxin-3 is a member of the insulin superfamily that is recently discovered. This hormone interacts with relaxin family peptide receptor 3 (RXFP3). Although recent studies of INSL7 have focused on its function in the brain as a neuropeptide, spermatozoa may be a candidate target of INSL7 due to its detection in testes and contains binding sites. Therefore, this study aims to analyse the expression and localisation of RXFP3 on human spermatozoa and to assess the effect of INSL7 on human sperm motility. We have incubated normal semen samples in different doses of INSL7. Sperm motility was analysed by Computer Assisted Sperm Analysis. Moreover, localisation and expression of RXFP3 were assessed in human spermatozoa by immunofluorescence and RT-PCR respectively. This study indicated that RXFP3 mainly localised in the post-acrosomal region of sperm head and neck. However, we did not observe expression of RXFP3 mRNA in human spermatozoa. This study showed that INSL7 alleviated the natural decline in sperm motility after a 4-hr incubation period. This was particularly observed in the 1.8 pmol/L treated samples. These data suggested that most likely expression of RXFP3 arrested in spermiogenesis, but the RXFP3 peptide existed on the surface of mature spermatozoa.

Molecular detection of Chlamydophila abortus, Coxiella burnetii, and Mycoplasma agalactiae in small ruminants' aborted fetuses in southern Iran.

Abortion in sheep and goats has become increasingly important worldwide because of the significant economic losses and potential zoonotic implication of commonly involved pathogens. Therefore, this cross-sectional study was conducted in southern Iran to detect the Chlamydophila abortus and Coxiella burnetii, as zoonotic pathogens, and Mycoplasma agalactiae, as a neglected abortifacient agent in small ruminants' aborted fetuses, by using polymerase chain reaction (PCR). From a total of 300 aborted fetuses (183 sheep and 117 goats), 46 samples (15.5%) were positive by PCR, 11% for C. abortus, 2% for C. burnetii, and 3% for M. agalactiae. Also, the association of suggested risk factors with abortion due to these bacterial agents was investigated using univariable and multivariable logistic regression. Results of the statistical analysis showed significant association of C. abortus with flock size (OR = 2.82, P = 0.014), season (P < 0.05), and the number of pregnancy in the aborted dam (OR = 2.5, P = 0.05). Our results indicated that C. abortus has a relatively substantial role in small ruminant abortions, and C. burnetii and M. agalactiae are likely important abortifacient agents in our region, too. Regarding veterinary and/or public health importance of these bacterial agents, more attention from veterinary and/or human health services and, maybe, a surveillance system for control and prevention of them are recommended.

Brucellosis as a neglected disease in a neglected population: a seroepidemiological study of migratory nomads in the Fars province of Iran.

This study assessed the seroprevalence of brucellosis and its risk factors in migratory nomads in the Fars province of Iran. Active brucellosis was defined as the combination of clinical symptoms, including fever, chills, night sweats, headache, low back pain, arthralgia, or myalgia, and positive laboratory testing, including either a serum agglutination test (SAT) ⩾1:80 with a 2-mercaptoethanol (2-ME) test ⩾1:40, or a SAT <1:80 combined with a positive Coombs Wright test (CWT) at a titre of at least threefold higher than SAT titre results. For the 536 participants, the female (316, 59%) to male (220, 41%) ratio was 1·4 and the participants' mean age was 32·4 ± 18·9 (range 1-96) years. Of all participants, 325 (60·6%) showed clinical symptoms; in symptomatic participants, the Rose Bengal plate test was positive in 33 (6·1%) cases, the SAT was positive in 18 (3·3%) cases, and the 2-ME test was positive in 30 (5·5%) cases. Positive SAT and 2-ME results were seen in 18 (3·3%) cases, but a negative SAT and a positive CWT were found in 36 (6·7%) cases. As a result, active brucellosis was detected in 54 cases, indicating a prevalence of 10% (95% confidence interval 8-12). In conclusion, we determined that brucellosis is a prevalent yet neglected disease in this nomadic population. Brucellosis control is not possible as long as these high-risk populations remain neglected.

A novel rat model of Alzheimer's disease based on lentiviral-mediated expression of mutant APP.

BACKGROUND: Alzheimer's disease (AD) is characterized by progressive and irreversible cognitive and memory impairment. The discovery of familial forms of AD (fAD) in association with specific gene mutations facilitated the generation of numerous rodent models. These models in turn proved valuable for the study of molecular mechanisms underlying AD pathogenesis, and facilitated translational research and preclinical drug development. This study aimed to introduce a new rat model of AD simulating some aspects of the sporadic cases of disease. METHODS: Lentiviruses (LV) encoding human amyloid protein precursor (APP) bearing the fAD-linked Swedish and Indiana mutations (APPSw/Ind) were injected bilaterally in the hippocampus of adult rats. Passive avoidance and spatial memory performance were assessed 30 and 45 days post-injection, respectively. APP overexpression, intracellular accumulation of ß-amyloid (Aß) peptide, and astrogliosis were also evaluated using immunohistochemical procedures. RESULTS: Passive avoidance memory deficit was followed by impairments in spatial memory retrieval in LV (APPSw/Ind)-injected rats, compared to control animals. In addition, LV expression of APPSw/Ind was associated with intraneuronal accumulation of Aß, and reactive astrocytosis, two major AD hallmarks. CONCLUSION: Results from this work suggest that LV-mediated delivery of APPSw/Ind in adult rats represents a cost and time-effective animal model for the study of mechanisms underlying APP-linked fAD pathogenesis. The relevance of this animal model to the study of sporadic AD is discussed.

Distribution of virulence genes and multiple drug-resistant patterns amongst different phylogenetic groups of uropathogenic Escherichia coli isolated from patients with urinary tract infection.

A total of 85 Uropathogenic Escherichia coli (UPEC) isolates were screened against ceftiofur, oxacillin, nitrofurantoin and lincospectin using Kirby-Bauer disc diffusion method, following CLSI guidelines. Prevalence of virulent factor genes amongst the isolates was determined by PCR, using gene-specific primers against the different virulent factors. Statistical analysis of the data was performed using SPSS software. The prevalence of traT, ompT, Iss, malX and ibeA genes was 47.1%, 38.8%, 20%, 16.5% and 9.4%, respectively. The most prevalent gene in group A and D was traT, whilst in group B2 was Iss. The highest resistance has been shown against oxacillin (98.8%), followed by ceftiofur (77.6%), whilst resistance to lincospectin (2.4%) and nitrofurantoin (12.9%) had the lowest frequencies. Multidrug resistance was shown in 82.35% of the isolates, whilst this study recommend lincospectin and nitrofurantoin as choice drugs for treatment, but more investigation of the bacterial pathogenicity associated with urinary tract infection (UTI) may contribute to a better medical intervention.

Comparison of the preventive analgesic effect of rectal ketamine and rectal acetaminophen after pediatric tonsillectomy.

OBJECTIVES: There is a little data about rectal administration of Ketamine as a postoperative analgesic, so we compared the efficacy of rectal ketamine with rectal acetaminophen, which is applied routinely for analgesia after painful surgeries like tonsillectomy. METHODS: In this single-blinded comparative trial, we enrolled 70 children undergoing elective tonsillectomy, and divided them randomly in two groups. Patients received rectal ketamine (2 mg / kg) or rectal acetaminophen (20 mg / kg) at the end of surgery. The children's Hospital of Eastern Ontario Pain scale was used to estimate pain in children. Also the vital signs, Wilson sedation scale, and side effects in each group were noted and compared for 24 hours. RESULTS: The ketamine group had a lower pain score at 15 minutes and 60 minutes after surgery in Recovery (6.4 ± 0.8, 7.4 ± 1 vs. 7.1 ± 1.2, 7.8 ± 1.2 in the acetaminophen group, P < 0.05) and one hour and two hours in the ward (7.2 ± 0.7, 7 ± 0.5 vs. 7.9 ± 1.2, 7.5 ± 1.2 in the acetaminophen group, P < 0.05), with no significant differences till 24 hours. Dreams and hallucinations were not reported in the ketamine group. Systolic blood pressure was seen to be higher in the ketamine group (104.4 ± 7.9 vs. 99.8 ± 7.7 in the acetaminophen group) and nystagmus was reported only in the ketamine group (14.2%). Other side effects were equivalent in both the groups. CONCLUSIONS: With low complications, rectal ketamine has analgesic effects, especially in the first hours after surgery in comparison with acetaminophen, and it can be an alternative analgesic with easy administration in children after tonsillectomy.

Awareness, treatment and control of hypertension, dyslipidaemia and diabetes mellitus in an Iranian population: the IHHP study.

We used data from the baseline survey from the Isfahan Healthy Heart Programme to determine the prevalence of hypertension, dyslipidaemia and diabetes among a representative samples of 12,514 adults living in 3 cities in the Islamic Republic of Iran. The prevalence of hypertension, dyslipidaemia and diabetes was 17.3%, 66.3% and 5.6% respectively. Awareness, treatment and control of hypertension were 40.3%, 35.3%, and 9.1% respectively. The rates for dyslipidaemia were 14.4%, 7.1% and 6.5% respectively, and 54.6% of diabetics were aware of their disease and 46.2% were under treatment.

Awareness, treatment and control of hypertension, dyslipidaemia and diabetes mellitus in an Iranian population: the IHHP study

We used data from the baseline survey from the Isfahan Healthy Heart Programme to determine the prevalence of hypertension, dyslipidaemia and diabetes among a representative samples of 12 514 adults living in 3 cities in the Islamic Republic of Iran. The prevalence of hypertension, dyslipidaemia and diabetes was 17.3%, 66.3% and 5.6% respectively. Awareness, treatment and control of hypertension were 40.3%, 35.3%, and 9.1% respectively. The rates for dyslipidaemia were 14.4%, 7.1% and 6.5% respectively, and 54.6% of diabetics were aware of their disease and 46.2% were under treatment

The metabolic syndrome in hypertensive and normotensive subjects: the Isfahan Healthy Heart Programme.

INTRODUCTION: There are numerous correlations between hypertension and the metabolic syndrome, although this is not always the case. The objective of this study was to compare the prevalence of the metabolic syndrome and its different phenotypes among hypertensive and normotensive subjects. MATERIALS AND METHODS: This cross-sectional study was performed on a representative sample of adults living in 3 cities in Iran. Among the 12,514 subjects selected by multi-stage random sampling, 1736 (13.9%) were hypertensive. The prevalence of the metabolic syndrome [according to the Adult Treatment Panel (ATP) III criteria] was significantly higher in hypertensive than normotensive subjects (51.6% versus 12.9%, respectively; OR, 7.15; 95% CI, 6.4 to 7.9). The metabolic syndrome was more prevalent in normotensive and hypertensive subjects living in urban areas than those living in rural areas (14.2% and 53.9% versus 9.5% and 45.6%, respectively, P < 0.05). The mean age of hypertensive subjects, with or without the metabolic syndrome, was not significantly different (55.7 +/- 12 years versus 55.4 +/- 15.5 years, P = 0.6). Hypertension with the metabolic syndrome was more prevalent in women than men (72% versus 28% respectively, P < 0.000), and in subjects living in urban areas than those in rural areas (75.1% versus 24.9%, respectively, P = 0.002). CONCLUSION: The findings of this study indicate the need for metabolic screening in all hypertensive patients, and emphasise the importance of promoting primary and secondary prevention of high blood pressure and associated modifiable risk factors in order to counter the upcoming epidemic of non-communicable disease in developing countries.

Characterization of film-coated aerosol canisters using electrochemical impedance spectroscopy.

Drug adhesion to the walls of an aerosol canister can be prevented/reduced by coating the canister with a hydrophobic polymer (e.g., a fluoropolymer). In this study, three batches of fluoropolymer-coated canisters were investigated by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The EIS technique showed that only one of the batches presented as a monolithic, non-porous film. The other two batches were either partially porous or highly porous. Scanning electron micrographs showed evidence of cracks, within the films, but could not alone establish the porous nature of these defects. For the non-porous and partly porous films it was possible to use the EIS data to determine the approximate film thickness. Estimates of 2-4 microm were obtained for the mean film thickness. These values compared favorably with micrometer estimates obtained following acid dissolution of the aluminum canister. It remains to be seen whether the properties of the films (i.e., the porosity and film thickness, determined by EIS) translate to differences in drug adhesion. Nevertheless, the EIS technique was shown to be a powerful, non-destructive method that lends itself to the rapid analysis of batch-to-batch variation in film-coated canisters.

Persistence and tissue distribution of DNA in normal and immunodeficient mice inoculated with polyomavirus VP1 pseudocapsid complexes or polyomavirus.

Introduction of DNA into normal and immunodeficient mice, alone or in complex with VP1 pseudocapsids, has been compared to DNA transfer by viral infection. Similar to natural infection and in contrast to plasmid alone, VP1 pseudocapsids efficiently introduced DNA, which remained for months in normal mice and possibly longer in B- and T-cell-deficient mice.

Susceptibility to polyoma virus tumorigenesis in X-linked immunodeficient (XID) and B-cell deficient (microMT) mice is not increased.

Polyoma virus induced tumorigenesis is controlled by T-cells, while B-cells clear virus infection. In order to study if T-cells can override the tumorigenic effect of a long term disseminated viral infection, the tumorigenicity and persistence of polyoma virus in antibody deficient adult and newborn infected X-linked immunodeficient (XID) and microMT mice was followed. In newborn infected XID and CBA control mice (sensitive to tumorigenesis), the frequency of tumor development was similar, and viral DNA was persistent at least 10 months p.i. In polyoma-infected newborn and adult microMT, and control C57BL/6 mice (resistant to tumorigenesis) as well as in adult XID and CBA control mice, no polyoma tumors were observed. Nevertheless, viral DNA was detected in most tissues in all microMT mice throughout the 5-7 month observation period, whereas in the remaining groups of mice persistent viral infection was limited or not detected. We suggest that the tumorigenic potential of an extensive persistent polyoma virus infection can be overcome as long as a functional T-cell system is present.

Adult X-linked immunodeficiency (XID) mice, IGM-/- single knockout and IGM-/- CD8-/- double knockout mice do not clear polyomavirus infection.

The importance of antibodies for elimination of polyomavirus infection and the prevention of virus induced oncogenesis was studied, X-linked immunodeficiency (XID) mice, IgM-/- single knockout and IgMI-/- CD8-/- double knockout mice, all defective in antibody production, and normal control mice were infected with polyomavirus as adults. The mice were followed for presence of polyoma DNA with a polyoma specific polymerase chain reaction (PCR) over 6 weeks post infection (p.i.), a time point at which polyomavirus DNA is no longer detected in normal adult infected mice. As expected, virus DNA was not detected in normal mice 6 weeks p.i. In both IgM-/- single knockout and IgM-/- CD8-/- double knockout mice a disseminated infection was still observed by 6 weeks p.i. and the latter group of mice succumbed around two months p.i. In XID mice, only one third of the mice were still positive for viral DNA 6 weeks p.i. No polyomavirus induced tumors were observed in any of the mice during the 2-4 month observation period.