Human bocavirus-the first 5 years.

Four species of human bocavirus (HBoV) have been recently discovered and classified in the Bocavirus genus (family Parvoviridae, subfamily Parvovirinae). Although detected both in respiratory and stool samples worldwide, HBoV1 is predominantly a respiratory pathogen, whereas HBoV2, HBoV3, and HBoV4 have been found mainly in stool. A variety of signs and symptoms have been described in patients with HBoV infection including rhinitis, pharyngitis, cough, dyspnea, wheezing, pneumonia, acute otitis media, fever, nausea, vomiting, and diarrhea. Many of these potential manifestations have not been systematically explored, and they have been questioned because of high HBoV co-infection rates in symptomatic subjects and high HBoV detection rates in asymptomatic subjects. However, evidence is mounting to show that HBoV1 is an important cause of lower respiratory tract illness. The best currently available diagnostic approaches are quantitative PCR and serology. This concise review summarizes the current clinical knowledge on HBoV species.

New respiratory viral infections.

PURPOSE OF REVIEW: The first era in the discoveries of respiratory viruses occured between 1933 and 1965 when influenza virus, enteroviruses, adenovirus, respiratory syncytial virus, rhinovirus, parainfluenza virus and coronavirus (CoV) were found by virus culture. In the 1990s, the development of high throughput viral detection and diagnostics instruments increased diagnostic sensitivity and enabled the search for new viruses. This article briefly reviews the clinical significance of newly discovered respiratory viruses. RECENT FINDINGS: In 2001, the second era in the discoveries of respiratory viruses began, and several new respiratory viruses and their subgroups have been found: human metapneumovirus, CoVs NL63 and HKU1, human bocavirus and human rhinovirus C and D groups. SUMMARY: Currently, a viral cause of pediatric respiratory illness is identifiable in up to 95% of cases, but the detection rates decrease steadily by age, to 30-40% in the elderly. The new viruses cause respiratory illnesses such as common cold, bronchitis, bronchiolitis, exacerbations of asthma and chronic obstructive pulmonary disease and pneumonia. Rarely, acute respiratory failure may occur. The clinical role of other new viruses, KI and WU polyomaviruses and the torque teno virus, as respiratory pathogens is not clear.

Merkel cell polyomavirus and trichodysplasia spinulosa-associated polyomavirus DNAs and antibodies in blood among the elderly.

BACKGROUND: Merkel cell polyomavirus (MCPyV) and trichodysplasia spinulosa-associated polyomavirus (TSPyV) are recently found pathogens causing two rare skin disorders, Merkel cell carcinoma (MCC) and trichodysplasia spinulosa (TS). MCC is proportionally common in the elderly and most often is associated with immunosuppression. TS is a folliculocentric infection seen in patients in an immunocompromised state. Little or no baseline information exists, however, on the prevalences of these two viruses among the elderly. Epidemiologic data on this population could help in understanding their natural biology. We wished to determine the occurrences and blood levels of MCPyV and TSPyV DNAs among the elderly and any association between the prevalences of their corresponding antiviral IgG antibodies. METHODS: From 394 hospitalized elderly individuals (age ≥65 years) with respiratory symptoms, cardiovascular, and other diseases, we studied 621 serum samples by four different real-time quantitative (q) PCRs, two for the DNAs of MCPyV and two for TSPyV. The IgG antibodies for both viruses among 481 serum samples of 326 subjects were measured with enzyme immunoassays (EIAs), using as antigen recombinant virus-like particles (VLPs). RESULTS: Of the 394 patients, 39 (9.9%) were positive at least once for MCPyV DNA by the LT PCR, and 33 (8.4%) by the VP1 PCR, while 6 (1.5%) were positive by both PCR assays. In general, the viral DNA copy numbers were low. In sharp contrast, no TSPyV DNA was detectable with qPCRs for the corresponding genomic regions. The IgG seroprevalence of MCPyV was 59.6% and of TSPyV, 67.3%. CONCLUSIONS: MCPyV DNA, unlike TSPyV DNA, occurs in low copy number in serum samples from a notable proportion of aging individuals. Whether this reflects enhanced viral replication possibly due to waning immune surveillance, and is associated with increased MCC risk, deserves exploration.

Identification of respiratory viruses in asymptomatic subjects: asymptomatic respiratory viral infections.

The medical literature of the past 4 decades was searched regarding respiratory virus detection by polymerase chain reaction and conventional methods (culture, antigen detection, serology) in asymptomatic subjects in an attempt to determine the prevalence and clinical significance of such viruses in normal persons.

Carotid artery intima-media thickness in children with type 1 diabetes.

Postmortem studies have shown a relationship between diabetic state and atherosclerotic arterial lesions in adolescents. The aim of the present study was to determine the presence of increased subclinical atherosclerosis (measured as carotid intima-media thickness [IMT]) and its risk factors, including lipoprotein oxidation, in children with type 1 diabetes. We measured carotid IMT using high-resolution ultrasound in 85 children (mean age, 11 +/- 2 years): 50 with type 1 diabetes (mean duration, 4.4 +/- 3.0 years) and 35 healthy control subjects matched for age, sex, and body size. The susceptibility of LDL to oxidation was determined by measuring the formation of conjugated dienes induced by Cu(2+) in 42 children (21 with diabetes and 21 control subjects). The mean carotid IMT was increased in children with diabetes (0.47 +/- 0.04 vs. 0.42 +/- 0.04 mm; P < 0.0001). Total cholesterol and LDL cholesterol concentrations were similar between the groups, but the children with diabetes had increased LDL diene formation rate (0.49 +/- 0.06 vs. 0.45 +/- 0.07 micromol/min; P < 0.05), suggesting increased in vitro LDL oxidizability. In a multivariate model for all subjects, the independent correlates for IMT were the diabetic state (P < 0.001), LDL cholesterol level (P < 0.001), and systolic blood pressure (P < 0.001). In children with diabetes but not in control subjects, LDL oxidizability correlated significantly with mean IMT (r = 0.47, P < 0.05), and this relationship remained significant after controlling for LDL cholesterol level. We conclude that type 1 diabetes is an independent risk factor for increased carotid IMT in children. These data also suggest that increased oxidative modification of LDL may be related to early structural atherosclerotic vascular changes in children with diabetes.

Enhanced endothelium-dependent vasodilation in subjects with Proline7 substitution in the signal peptide of neuropeptide Y.

Neuropeptide Y (NPY) is a molecule that may have both vasoconstrictive and vasodilatory actions. A common polymorphism in the human NPY gene that results in the Leucine7 to Proline7 substitution (Leu7Pro) in the signal peptide part of the NPY was recently identified. This substitution has been associated with elevated serum cholesterol levels and with slightly accelerated progression rate of carotid intima-media thickness, thus suggesting increased risk of atherosclerosis in carriers of Pro7 substitution. Recent data also indicate that subjects with Pro7 substitution may have increased endothelial release of NPY. This study was undertaken to elucidate the effects of Leu7Pro polymorphism on arterial endothelial function. We measured flow-mediated endothelial-dependent dilatation (FMD) of the brachial artery in two separate populations: in 152 middle-aged men and in 95 prepubertal children. In both study populations, subjects with Pro7 substitution had 48-52% higher FMD compared with subjects having the wildtype (Leu7/Leu7) signal peptide sequence. We conclude that Pro7 substitution in signal peptide of the NPY is associated with enhanced endothelial-dependent vasodilation. Prospective studies are needed to determine whether Pro7 substitution is associated with increased or decreased risk of cardiovascular morbidity and mortality.

Novel human gammapapillomavirus species in a nasal swab.

A divergent human gammapapillomavirus (γ-HPV) genome in a nasal swab from an elderly Finnish patient with respiratory symptoms was genetically characterized. The L1 gene of HPV-Fin864 shared <70% nucleotide identity to other reported γ-HPV genomes, provisionally qualifying it as a new species in the Gammapapillomavirus genus.

Biotin IgM antibodies in human blood: a previously unknown factor eliciting false results in biotinylation-based immunoassays.

Biotin is an essential vitamin that binds streptavidin or avidin with high affinity and specificity. As biotin is a small molecule that can be linked to proteins without affecting their biological activity, biotinylation is applied widely in biochemical assays. In our laboratory, IgM enzyme immuno assays (EIAs) of µ-capture format have been set up against many viruses, using as antigen biotinylated virus like particles (VLPs) detected by horseradish peroxidase-conjugated streptavidin. We recently encountered one serum sample reacting with the biotinylated VLP but not with the unbiotinylated one, suggesting in human sera the occurrence of biotin-reactive antibodies. In the present study, we search the general population (612 serum samples from adults and 678 from children) for IgM antibodies reactive with biotin and develop an indirect EIA for quantification of their levels and assessment of their seroprevalence. These IgM antibodies were present in 3% adults regardless of age, but were rarely found in children. The adverse effects of the biotin IgM on biotinylation-based immunoassays were assessed, including four inhouse and one commercial virus IgM EIAs, showing that biotin IgM do cause false positivities. The biotin can not bind IgM and streptavidin or avidin simultaneously, suggesting that these biotin-interactive compounds compete for the common binding site. In competitive inhibition assays, the affinities of biotin IgM antibodies ranged from 2.1 × 10(-3) to 1.7 × 10(-4 )mol/L. This is the first report on biotin antibodies found in humans, providing new information on biotinylation-based immunoassays as well as new insights into the biomedical effects of vitamins.

New respiratory viruses and the elderly.

The diagnostics of respiratory viral infections has improved markedly during the last 15 years with the development of PCR techniques. Since 1997, several new respiratory viruses and their subgroups have been discovered: influenza A viruses H5N1 and H1N1, human metapneumovirus, coronaviruses SARS, NL63 and HKU1, human bocavirus, human rhinoviruses C and D and potential respiratory pathogens, the KI and WU polyomaviruses and the torque teno virus. The detection of previously known viruses has also improved. Currently, a viral cause of respiratory illness is almost exclusively identifiable in children, but in the elderly, the detection rates of a viral etiology are below 40%, and this holds also true for exacerbations of chronic respiratory illnesses. The new viruses cause respiratory symptoms like the common cold, cough, bronchitis, bronchiolitis, exacerbations of asthma and chronic obstructive pulmonary disease and pneumonia. Acute respiratory failure may occur. These viruses are distributed throughout the globe and affect people of all ages. Data regarding these viruses and the elderly are scarce. This review introduces these new viruses and reviews their clinical significance, especially with regard to the elderly population.

Migration and coronary heart disease: A study of Finnish twins living in Sweden and their co-twins residing in Finland.

BACKGROUND: Finland and Sweden are neighbouring countries with a substantially higher incidence and mortality from coronary heart disease (CHD) in Finland. Migration from Finland to Sweden has resulted in a population of about 187,000 Finnish immigrants, with a higher risk of CHD than Swedes. The aim of the present study was to analyse the prevalence of CHD in migrants to Sweden compared with co-twins remaining in Finland. METHODS: The study population consisted of twin pairs of the Finnish Twin Cohort Study where at least one twin had lived one year or more in Sweden, including 1,534 subjects and 251 complete twin pairs discordant regarding residency in Sweden. Emigrant twins were compared with nonmigrant co-twins regarding prevalence of CHD in 1998. CHD prevalence was assessed by self-reported questionnaires validated using information from a clinical examination. RESULTS: Self-reported CHD showed a good correspondence with clinical diagnosis. Differences in social and behavioural risk factors for CHD among men were small but emigrants were more physically active than non-migrants. Female emigrants had less overweight and better education, but were more often working class than non-migrants. Intra-pair comparisons restricted to migration discordant pairs showed a tendency towards a reduced prevalence of CHD in the migrant co-twins (0.6; 0.3-1.4). In analyses of all subjects disregarding pair status, emigrants showed a reduced prevalence of CHD compared with subjects always living in Finland (0.6; 0.4-0.9). CONCLUSION: Emigration from Finland to Sweden may be associated with a reduced prevalence of CHD. The causes are most likely multifactorial and may involve changes in dietary habits, physical activity, psychosocial factors, and inflammation.

Determinants of short-term variation in arterial flow-mediated dilatation in healthy young men.

Brachial artery FMD (flow-mediated dilatation) is widely used as a marker of systemic arterial endothelial function. FMD, however, shows considerable 25% day-to-day variation that hinders its clinical use. The reasons for this variability are poorly characterized. Therefore the present study was designed to clarify factors responsible for the hourly variation in endothelial function, including consuming a low-fat meal and circadian rhythms in endogenous hormonal levels. Brachial artery FMD, along with serum glucose, triacylglycerols (triglycerides) and levels of several hormones were measured six times per day on two separate days 1 week apart. On one day, the subjects (healthy males: n=12, mean age, 24 years) ate a light breakfast and a standardized lunch (23.5% fat, 48.7% carbohydrate and 27.8% protein). On the other day, they had a similar breakfast after which they fasted. Postprandial FMD values (both after breakfast and after lunch) were similar to baseline FMD. FMD showed a 28% hourly variation and 27% weekly variation. Variation in plasma levels of insulin (P=0.02) associated negatively and DHPG (3,4-dihydroxyphenylglycol) (P=0.001), a marker of sympathetic nervous activation, associated positively with variation in FMD. The effects of DHPG and insulin on FMD were independent of changes in baseline brachial artery diameter, although DHPG was also inversely associated with baseline diameter. Eating a regular low-fat meal does not have any measurable effects on brachial artery endothelial function. These data suggest that strict requirements for fasting conditions may be unnecessary when measuring peripheral endothelial function using the ultrasound technique. Circadian variation in serum insulin and sympathetic tone are physiological determinants of endothelial function.

Higher prevalence of Chlamydia pneumoniae seropositivity in Finnish twins compared with co-twins living in Sweden: relationships with markers of subclinical atherosclerosis.

Mortality rates from coronary heart disease are lower in Swedish men and among Finnish migrants who have lived in Sweden for over 20 years than in men living in Finland. Sero-epidemiological studies, investigations of atheromatous plaque specimens, in vitro animal models and anti-chlamydial antibiotic trials have given support to the hypothesis that Chlamydia pneumoniae (Cpn) has a role in atherosclerosis. We investigated whether men with a similar genetic background but living permanently in Finland or Sweden have differences in the prevalence of Cpn seropositivity, and whether chronic Cpn infection is associated with markers of subclinical atherosclerosis. We measured anti-Cpn antibodies and ultrasonographic markers of subclinical atherosclerosis, including carotid intima-media thickness, carotid artery compliance and brachial artery flow-mediated dilatation, in a population of 76 migrant-discordant male twin pairs (152 men). The number of men with seropositivity to Cpn infection (defined as IgA>/=1:64 and IgG>/=1:128) was greater in Finland than in Sweden (21.5% compared with 10.5%; P =0.046). Cpn seropositivity accompanied by elevated C-reactive protein (CRP) levels (>1 mg/l) was associated with attenuated brachial artery flow-mediated dilatation (3.3+/-0.3%, compared with 5.5+/-0.4% in men with no signs of Cpn infection; P <0.001).Thus, among Finnish twin brothers discordant for migration to Sweden, the prevalence of Cpn seropositivity is higher for those living in Finland, and men with Cpn seropositivity combined with elevated CRP levels had attenuated endothelial function. These findings offer insight into the mechanism whereby chronic Cpn infection may increase the risk of coronary heart disease.

Deletion polymorphism in the alpha2B-adrenergic receptor gene is associated with flow-mediated dilatation of the brachial artery.

A deletion variant of the alpha(2B)-adrenergic receptor (alpha(2B)-AR) has been associated with an increased risk of acute cardiac events in middle-aged men. Our aim was to determine the possible associations between the alpha(2B)-AR gene deletion variant and indicators of subclinical atherosclerosis in the brachial and carotid arteries. A total of 148 middle-aged men participating in an epidemiological twin study on risk factors for subclinical coronary heart disease were genotyped using PCR. Flow-mediated dilatation (FMD) of the brachial artery, carotid artery compliance and carotid intima-media thickness were measured using high-resolution ultrasound. FMD was 6.2+/-5.0% in subjects with the I/I (insertion/insertion) genotype, 5.5+/-4.1% in the I/D (insertion/deletion) group and 4.1+/-3.8% in the D/D (deletion/deletion) group ( P =0.03 for trend). In multivariate regression analysis controlling for age, presence of hypertension, smoking, use of angiotensin-converting enzyme inhibitors and plasma levels of low-density lipoprotein cholesterol and lipoprotein (a), the association between the alpha(2B)-AR genotype and FMD remained significant ( P =0.04 for trend). The alpha(2B)-AR genotype was not associated with intima-media thickness or carotid artery compliance. These findings indicate that subjects homozygous for the deletion allele of alpha(2B)-AR appear to have an increased risk of impaired endothelial function, which may provide an explanation for the previously observed increased risk of myocardial infarction in male subjects with this genotype. It is not known whether the association of the alpha(2B)-AR polymorphism with endothelial function is direct, or is mediated via altered sympathetic activation.

Increased carotid intima-media thickness in men born in east Finland: a twin study of the effects of birthplace and migration to Sweden on subclinical atherosclerosis.

BACKGROUND: There is a clear east-west difference in coronary heart disease (CHD) mortality and incidence in Finland, people living in east Finland having higher CHD rate. A study of Finnish immigrants to Sweden has suggested that a long stay in Sweden would be associated with reduced CHD risk. AIM: To determine whether structural and functional markers of subclinical atherosclerosis differ between men originating from east and west Finland, and whether migration to Sweden influences subclinical atherosclerosis. METHOD: Carotid intima-media thickness (IMT) and brachial artery flow-mediated dilatation (FMD) with high-resolution ultrasound and a set of cardiovascular risk factors were measured in 76 middle-aged male twin pairs (55 pairs from east and 21 pairs from west Finland) discordant for migration to Sweden. RESULTS: Among men living in Finland, IMT was significantly higher in men originating from east Finland compared to those from west Finland (0.796 +/- 0.212 versus 0.704 +/- 0.123 mm, P = 0.02). A similar east-west difference was observed in men who had migrated to Sweden (0.766 +/- 0.220 versus 0.686 +/- 0.089 mm, P = 0.03). The east-west difference in IMT persisted after adjustment for the major traditional cardiovascular risk factors. No east-west difference was seen in FMD. Smoking, Framingham risk score and physical activity had a greater impact on IMT in men originating from east compared to west Finland. CONCLUSIONS: Men originating from east Finland, irrespective of their current residence, have a greater degree of subclinical atherosclerosis and they may be more susceptible to the impact of conventional cardiovascular risk factors than men originating from west Finland.