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Biomedical subjects

S Bergström

Publications and source records attributed to S Bergström.

At least 19 recordsLinked to original sources

Testicular damage by microcirculatory disruption and colonization of an immune-privileged site during Borrelia crocidurae infection.

The agent of African relapsing fever, Borrelia crocidurae, causes reversible multiple organ damage. We hypothesize that this damage is caused when the spirochete forms aggregate with erythrocytes in vivo, creating rosettes that plug the microcirculatory system. To test this hypothesis, we compared testicular microcirculation over an extended time period in two groups of rats: one experimentally inoculated with B. crocidurae, the other with the nonerythrocyte rosette-forming Borrelia hermsii. In the B. crocidurae group, erythrocyte rosettes formed during spiro-chetemia blocked precapillary blood vessels and reduced the normal pattern of microcirculatory blood flow. After spirochetemia, erythrocyte rosettes disappeared and flow was normalized. Decreased blood flow and focal vascular damage with increased permeability and interstitial bleeding adjacent to the erythrocyte microemboli induced cell death in seminiferous tubules. Interestingly, we found that B. crocidurae could penetrate the tubules and remain in the testis long after the end of spirochetemia, suggesting that the testis can serve as a reservoir for this bacteria in subsequent relapses. The group infected with B. hermsii displayed normal testicular blood flow and vasomotion at all selected time points, and suffered no testicular damage. These results confirmed our hypothesis that the erythrocyte rosettes produce vascular obstruction and are the main cause of histopathology seen in model animal and human infections.

Animals↗

A community based study on the change of practice of female genital mutilation in a Sudanese village.

OBJECTIVE: To investigate the practice of female genital mutilation (FGM), among young and old parents. METHODS: One hundred and twenty young parents and grandparents in a rural area in central Sudan were randomly selected for interviews carried out according to structured questionnaires with open answer possibilities. RESULTS: All female respondents had undergone FGM. Of the young respondents, 44% had decided not to let their daughters undergo FGM. Young fathers were more involved in the decision process than previously known, especially when decisions were taken not to perform FGM. Tradition and social pressure were the main motives for performing FGM. Sexuality was an important aspect, mentioned both as motives for and against FGM. Religious belief and education level significantly affected to what extent FGM was practiced. CONCLUSION: This is the first community based study of FGM indicating a significant shift in practice between generations, young parents starting to question the value of FGM.

Adult↗

Adolescent maternal mortality in Mozambique.

PURPOSE: To describe adolescent maternal mortality and analyze its avoidability. METHODS: An audit approach was used to clarify the presence of avoidable factors in 239 maternal deaths, of which 22% were among adolescents. RESULTS: The main causes of adolescent death were malaria, pregnancy-induced hypertension, puerperal sepsis, and septic abortion. The audit classified as avoidable 75% of all maternal deaths. CONCLUSION: Adequate strategies addressing the special needs of adolescents are required to prevent currently high levels of maternal mortality in this age group.

Adolescent↗

Perinatal outcome in an obstetric cohort of Mozambican women.

A prospective cohort of 908 consecutively enrolled pregnant women with biparietal diameter (DBP) compatible with gestational age equal to or below 21 weeks were followed up regularly at 2-4 weeks intervals. Normal antenatal care routine was applied. The newborns were followed until 7 days postpartum. The setting was two suburban antenatal clinics in Maputo and the delivery ward at the Maputo Central Hospital. The main outcome variables were low birth weight (LBW), preterm delivery, intrauterine fetal death, perinatal death and small for gestational age (SGA). For each of these variables the odds ratio for maternal risk factors was estimated with 95 per cent confidence interval and multiple logistic regression analysis was used. LBW occurred in 16.2 per cent and low maternal weight, low weight gain during pregnancy and not having a living child were risk factors. Prevalence of preterm birth was 15.4 per cent and low weight gain during pregnancy and malaria in the perinatal period were risk factors. Four per cent of mothers delivered stillborns and syphilis serology (positive VDRL test) was a risk factor. Perinatal death occurred in 4.7 per cent. These deaths were associated with being SGA, LBW or preterm at birth. Of the cohort women, 9.7 per cent delivered SGA newborns. It was concluded that maternal constitutional factors, particularly maternal weight gain, maternal height and maternal weight as well as syphilis and malaria during pregnancy, need to be given attention concerning the adverse outcomes addressed. The establishment of an obstetric cohort, followed prospectively, was possible in a low-income setting with limited numbers lost to follow-up at delivery.

Adolescent↗

P13, an integral membrane protein of Borrelia burgdorferi, is C-terminally processed and contains surface-exposed domains.

To elucidate antigens present on the bacterial surface of Borrelia burgdorferi sensu lato that may be involved in pathogenesis, we characterized a protein, P13, with an apparent molecular mass of 13 kDa. The protein was immunogenic and was expressed in large amounts during in vitro cultivation compared to other known antigens. An immunofluorescence assay, immunoelectron microscopy, and protease sensitivity assays indicated that P13 is surface exposed. The deduced sequence of the P13 peptide revealed a possible signal peptidase type I cleavage site, and computer analysis predicted that P13 is an integral membrane protein with three transmembrane-spanning domains. Mass spectrometry, in vitro translation, and N- and C-terminal amino acid sequencing analyses indicated that P13 was posttranslationally processed at both ends and modified by an unknown mechanism. Furthermore, p13 belongs to a gene family with five additional members in B. burgdorferi sensu stricto. The p13 gene is located on the linear chromosome of the bacterium, in contrast to five paralogous genes, which are located on extrachromosomal plasmids. The size of the p13 transcript was consistent with a monocistronic transcript. This new gene family may be involved in functions that are specific for this spirochete and its pathogenesis.

Amino Acid Sequence↗

Delayed invasion of the kidney and brain by Borrelia crocidurae in plasminogen-deficient mice.

Borrelia crocidurae is an etiologic agent of relapsing fever in Africa and is transmitted to humans by the bite of soft ticks of the genus Ornithodoros. The role of the plasminogen (Plg) activation system for the pathogenicity of B. crocidurae was investigated by infection of Plg-deficient (plg(-/-)) and Plg wild-type (plg(+/+)) mice. No differences in spirochetemia were observed between the plg(-/-) and plg(+/+) mice. However, signs indicative of brain invasion, such as neurological symptoms and/or histopathological changes, were more common in plg(+/+) mice. Quantitative immunohistochemical analysis demonstrated infection of spirochetes in kidney interstitium and brain as soon as 2 days postinoculation. Lower numbers of extravascular spirochetes in plg(-/-) mice during the first days of infection suggested a less efficient invasion mechanism in these mice than in the plg(+/+) mice. The invasion of the kidneys in plg(-/-) mice produced no significant inflammation, as seen by quantitative immunohistochemistry of the CD45 common leukocyte marker. However, significant kidney inflammation was observed with infection in the plg(+/+) mice. In brain, inflammation was more severe in plg(+/+) mice than in plg(-/-) mice, and the numbers of CD45(+) cells increased significantly with duration of infection in the plg(+/+) mice. The results show that invasion of brain and kidney occurs as early as 2 days after inoculation. Also, Plg is not required for establishment of spirochetemia by the organism, whereas it is involved in the invasion of organs.

Animals↗

Characterization of Lyme borreliosis isolates from patients with erythema migrans and neuroborreliosis in southern Sweden.

Southern Sweden is an area of Lyme borreliosis (LB) endemicity, with an incidence of 69 cases per 100,000 inhabitants. The most frequent clinical manifestations are erythema migrans (77%) and neuroborreliosis (16%). There was no record of human Borrelia strains being isolated from patients in this region before the prospective study reported here. Borrelia spirochetes were isolated from skin and cerebrospinal fluid (CSF) from LB patients living in the region. A total of 39 strains were characterized by OspA serotype analysis, species-specific PCR, and signature nucleotide analysis of the 16S rRNA gene. Of 33 skin isolates, 31 (93.9%) were Borrelia afzelii strains and 2 (6.1%) were Borrelia garinii strains. Of six CSF isolates, five (83.3%) were B. garinii and one (16.7%) was B. afzelii. Neither Borrelia burgdorferi sensu stricto strains nor multiple infections were observed. The B. afzelii isolates were of OspA serotype 2. Three B. garinii strains were of OspA serotype 5, and the remaining four strains were of OspA serotype 6. All of the B. garinii strains belonged to the same 16S ribosomal DNA ribotype class. Our findings agree with earlier findings from other geographic regions in Europe where B. afzelii and B. garinii have been recovered predominantly from skin and CSF cultures, respectively. To further study the possible presence in Sweden of the genotype B. burgdorferi sensu stricto, which is known to be present in Europe and to occur predominantly in patients with Lyme arthritis, molecular detection of Borrelia-specific DNA in synovial samples from Lyme arthritis patients should be performed.

Antigens, Surface↗

Socio-economic, demographic and obstetric risk factors for late fetal death of unknown etiology in Lithuania: a case--referent study.

BACKGROUND: The purpose of this study was to evaluate the association between third trimester unexplained prelabor fetal deaths and various socio-economic, demographic and obstetric factors in Lithuania. METHODS: A case-referent study on 58 women with third trimester fetal death and 116 women with live fetus at term was carried out. Inclusion criteria for women in the first group (cases) were: prelabor fetal death of unknown etiology, singleton pregnancy >26 weeks of gestation and intact fetal membranes. For each case two referent women were recruited, admitted during the same period in active phase of labor at term (>37 weeks of gestation) with intact fetal membranes and fetus alive. Data were obtained by interview, anthropometry and by reviewing the medical records. Several potential socio-economic, demographic and obstetrical risk factors for unexplained fetal death were investigated. RESULTS: Univariate analyses determined several factors that were associated with fetal death of unknown etiology: low educational level, single marital status, low income, etc. After secondary logistic regression analysis only three independent variables remained significantly associated with otherwise unexplained stillbirth: small for gestational age fetus (OR 29.6; 95% CI 6.2-141.6), low income (OR 7.4; 95% CI 3.1-17.6), and maternal white blood cell count more than 16,000/mm3 (OR 5.4; 95% CI 1.4-21.6). Body mass index, smoking, occupation of women and other evaluated parameters were not confirmed to be significant risk factors. CONCLUSION: Small for gestational age fetus, low income and elevated maternal white blood cell count are factors significantly associated with late prelabor fetal death in Lithuania.

Adult↗

Borrelia pathogenesis research in the post-genomic and post-vaccine era.

In the two years after publication of the genome sequence of Borrelia burgdorferi and reports on human field trials of a vaccine against Lyme borreliosis, there has been further progress in understanding of host-parasite interactions during Lyme borreliosis and relapsing fever. Some mechanisms that Borrelia spirochetes use to avoid elimination and to persist in the host are novel. In addition, the recent discovery of antigenic variation in the Lyme disease agent B. burgdorferi adds to the complexity of the possible virulence properties of this human pathogen.

Animals↗

Salmonella in sub-Antarctica: low heterogeneity in Salmonella serotypes in South Georgian seals and birds.

The number of human visitors to Antarctica is increasing rapidly, and with it a risk of introducing infectious organisms to native animals. To study the occurrence of salmonella serotypes in sub-Antarctic wildlife, faecal samples were collected from gentoo penguins, macaroni penguins, gray-headed albatrosses, black-browed albatrosses and Antarctic fur seals on Bird Island in the South Georgian archipelago during the austral summer of 1996 and 1998. In 1996, S. havana, S. typhimurium and S. enteritidis were isolated from 7% of gentoo penguins and 4% of fur seals. In 1998, however, 22% of fur seals were found to be infected with S. havana, S. enteritidis and S. newport. All isolates, except one, showed identical pulsed-field gel electrophoresis-patterns within each serotype, irrespective of sampling year and animal reservoir. No significant antibiotic resistance was found. The very low heterogeneity in the salmonella isolates found could either indicate a high genetic adaptation of the bacteria to the environment or a recent introduction of salmonella into the area.

Adaptation, Physiological↗

The problem of illegally induced abortion: results from a hospital-based study conducted at district level in Dar es Salaam.

Illegal abortion is known to be a major contributor to maternal mortality. The objective of the study was firstly to identify women with illegally induced abortion, (IA) and to compare them with women admitted with a spontaneous abortion (SA) or receiving antenatal care (AC), and secondly to describe the circumstances which characterized the abortion. The population of this cross-sectional questionnaire study comprised patients from Temeke District Hospital, Dar es Salaam, Tanzania. After an in-depth confidential interview, 603 women with incomplete abortion were divided into two groups: 362 women with IA and 241 with SA. They were compared with 307 AC women. IA women were significantly younger, more often better educated, unmarried, nulliparous and students than AC women. Regarding civil-status, educational level, proportion of nullipara and proportion of students, SA patients were similar to AC women. These results lend support to the assumption that the in-depth confidential interview made it possible to distinguish IA women from SA women.

Abortion, Illegal↗

The relapsing fever spirochaete, Borrelia crocidurae, activates human endothelial cells and promotes the transendothelial migration of neutrophils.

The blood-borne, erythrocyte-aggregating Borrelia crocidurae, the causative agent of African relapsing fever, have been shown to induce severe cellular lesions in mice. In this paper, we present the first report of how the endothelium is stimulated during an African relapsing fever B. crocidurae infection. B. crocidurae co-incubated with cultured human umbilical vein endothelial cells (HUVECs) activated endothelium in such way that E-selectin and intercellular adhesion molecule 1 (ICAM-1) became upregulated in a dose- and time-dependent fashion, as determined by a whole-cell enzyme-linked immunosorbent assay (ELISA). The upregulation was reduced by treatment that killed the bacteria, suggesting that viability is important for the stimulation of HUVECs by B. crocidurae. Furthermore, conditioned medium from HUVECs stimulated with B. crocidurae contained interleukin (IL)-8, which is a chemotactic agent for neutrophils. Activation of HUVECs by B. crocidurae resulted in migration of subsequently added neutrophils across the endothelial monolayers, and this migration was inhibited by antibodies to IL-8. The activation of endothelium by B. crocidurae may constitute a key pathophysiological mechanism in B. crocidurae-induced vascular damage.

Animals↗

Is pelvic pain in pregnancy a welfare complaint?

BACKGROUND: Pelvic pain in pregnancy has been suggested to be more common in Scandinavia than in the rest of the world, to be culturally specific for the region and to reflect a change in attitude among pregnant women. Little is known of the prevalence of pelvic pain in pregnancy in low-income countries. OBJECTIVE: To explore whether perceived pelvic pain among pregnant women differs between affluent and poor societies. SUBJECTS AND METHODS: Four observational studies, comprising a total of 752 women, were carried out in circumstances ranging from wealth to poverty, focusing on the reported prevalence, location and degree of pelvic pain in pregnancy. In Uppsala, Sweden, and in Rufiji, Tanzania, the women were interviewed in late pregnancy. In Jakobstad, Finland, and in Zanzibar Town, Zanzibar, the women were approached after delivery before discharge. RESULTS: The reported prevalence of pelvic pain in pregnancy was 49% in Uppsala and 66% in Rufiji, 77% in Jakobstad and 81% in Zanzibar, with an overall similarity of location and degree of pain. CONCLUSION: No geographical differences were found in perceived pelvic pain among pregnant women, irrespective of the socio-economy of the countries.

Adult↗

Symphyseal distention in relation to serum relaxin levels and pelvic pain in pregnancy.

OBJECTIVE: To elucidate whether there is an association between symphyseal distention, circulating relaxin levels and pelvic pain in pregnancy. METHODS: Serum relaxin and symphyseal width were assessed in 19 consecutive referral cases with severe pelvic pain at 35 weeks of pregnancy and in a cohort of 49 women at 12 and 35 weeks of pregnancy. The referral cases were received over a period of two years and four months and the cohort was recruited over a period of two months. Relaxin was measured with an ELISA test and symphyseal width assessed using ultrasonography. All women with pelvic pain were clinically assessed. The women were divided into three groups; Group A (n= 38), cohort cases with no or mild pain; Group B (n= 11), cohort cases with disabling pain; and Group C (n= 19), referral cases. RESULTS: At 35 weeks of pregnancy, mean symphyseal width was 4.5 mm (s.d. 1.0 mm) in Group A, 5.7 mm (s.d. 2.6 mm) in Group B, and 7.4 mm (s.d. 3.5 mm) in Group C. The difference between Groups A and B is statistically significant (p=0.044) as is that between Groups A and C (p<0.0001). Serum relaxin levels were not associated with symphyseal distention or disabling pain. CONCLUSION: Severe pelvic pain during pregnancy was strongly associated with an increased symphyseal distention. However, the severity of pain did not predict the degree of symphyseal distention in the individual case, indicating that other mechanisms are also involved. Serum relaxin levels were not associated with the degree of symphyseal distention or with pelvic pain in pregnancy.

Adult↗

Isolation and characterization of Campylobacter jejuni subsp. jejuni from macaroni penguins (Eudyptes chrysolophus) in the subantarctic region.

On Bird Island, South Georgia, albatrosses (n = 140), penguins (n = 100), and fur seals (n = 206) were sampled for Campylobacter jejuni. C. jejuni subsp. jejuni was recovered from three macaroni penguins (Eudyptes chrysolophus). These isolates, the first reported for the subantarctic region, showed low genetic diversity and high similarity to Northern Hemisphere C. jejuni isolates, possibly suggesting recent introduction to the area.

Animals↗