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Biomedical subjects

S Håkansson

Publications and source records attributed to S Håkansson.

At least 19 recordsLinked to original sources
PubMed2006

Survival of the biocontrol yeast Pichia anomala after long-term storage in liquid formulations at different temperatures, assessed by flow cytometry.

AIMS: Investigate the survival of liquid formulations of the biocontrol yeast Pichia anomala J121 at different temperatures, and develop a system for comparative studies of different storage conditions and formulations. METHODS AND RESULTS: The survival of P. anomala in liquid formulations with lactose, starch and trehalose amendments was measured during prolonged storage at temperatures ranging from -20 to +30 degrees C. The relative survival of the stored cells was rapidly estimated by flow cytometry. After 4 weeks incubation at 4 and 10 degrees C, 75-90% of the cells were viable, with no significant differences between the various formulations. Supplementing the storage buffer with lactose or trehalose increased the survival after longer incubations (8 and 12 weeks) at all temperatures (-20 to 30 degrees C). Trehalose was the most effective protectant at 20 and 30 degrees C (>20% viable cells after 12 weeks at 20 degrees C). The biocontrol activity was maintained after formulation and prolonged storage of P. anomala. CONCLUSIONS: The storage potential of liquid formulated P. anomala cells can be increased by supplementation with lactose or trehalose. The combination of a custom made incubation chamber and flow cytometry was suitable to evaluate stability of P. anomala formulations. SIGNIFICANCE AND IMPACT OF THE STUDY: Liquid formulated P. anomala have a long shelf life. The developed test system can be used to study different formulations of other biocontrol agents.

Colony Count, Microbial↗
PubMed2006

Impact and risk factors for early-onset group B streptococcal morbidity: analysis of a national, population-based cohort in Sweden 1997-2001.

OBJECTIVES: To study early-onset group B streptococcal (EOGBS) morbidity, mortality, and maternal risk factors. DESIGN: Observational, population-based, retrospective. Data from national registers and medical records. SETTING: Sweden, 1997-2001. POPULATION: Cohort of 640 infants with a diagnosis of GBS infection out of 435 070 live births. METHOD: Infants with diagnoses GBS sepsis (P36.0) and/or pneumonia (P23.3) were analysed. In cases with P36.0, register data were validated against infant and maternal medical records. Odds ratios (OR) were estimated by multiple logistic regression. MAIN OUTCOME MEASURES: Incidence of EOGBS morbidity, mortality, frequency of maternal risk factors and administration of intrapartum antibiotics. RESULTS: There were 319 cases with EOGBS sepsis. Blood culture verified 174 cases. There were 145 with clinical sepsis and 180 with pneumonia only. The incidences were 0.40, 0.33, and 0.41 per 1000 live births, respectively. The mortality was 7.5, 0.7, and 2.2% in respective groups. The frequencies of established maternal risk factors were: membrane rupture > or =18 hours, 44%; prematurity, 26%; temperature during labour > or =38 degrees C, 22%. Novel maternal risk factors identified in verified cases were gestational age (GA) of 37 completed weeks (OR 3.5, 1.8-6.5) and gestational diabetes (OR 3.7, 1.8-8.5). When including clinical sepsis, also epidural anaesthesia, infant large for GA, postmaturity, and high maternal age were significant risk factors. CONCLUSION: The incidence of verified EOGBS disease was 0.4 per 1000 live births with a total burden of EOGBS morbidity approximately three times higher. GA of 37 completed weeks and gestational diabetes were identified as additional significant risk factors.

Adult↗
PubMed2004

Short-term outcome after active perinatal management at 23-25 weeks of gestation. A study from two Swedish tertiary care centres. Part 2: infant survival.

AIM: To determine neonatal survival rates based on both foetal (stillborn) and neonatal deaths among infants delivered at 23-25 wk, and to identify maternal and neonatal factors associated with survival. METHODS: The medical records of 224 infants who were delivered in two tertiary care centres in 1992-1998 were reviewed retrospectively. At these centres, policies of active perinatal and neonatal management were universally applied. Data were analysed by gestational age groups and considered in three time periods. Logistic regression models were used to identify factors associated with survival. RESULTS: The rate of foetal death was 5%. Of infants born alive, 63% survived to discharge. Survival rates including foetal deaths in the denominator at 23, 24 and 25 wk were 37%, 61% and 74%, respectively, and survival rates excluding foetal deaths were 43%, 63% and 77%, respectively. Of infants born with 1-min Apgar scores of 0-1, 43% survived. In the total cohort, survival rates including foetal deaths in the denominator increased from 52% in time period 1 to 61% in time period 2 and 74% in time period 3 (p < 0.02). On multivariate logistic regression analysis, higher birthweight (OR: 1.91 per 100 g increment; 95% CI: 1.45-2.52), female gender (OR: 3.33; 95% CI: 1.65-6.75), administration of antenatal steroids (OR: 2.95; 95% CI: 1.46-5.98) and intrauterine referral from a peripheral hospital (OR: 2.35; 95% CI: 1.18-4.68) were associated with survival. Apgar score < or = 3 at 1 min (OR: 0.46; 95% CI: 0.22-0.95) was associated with decreased survival. The use of antenatal steroids was protective at 23-24 wk (OR: 5.2; 95% CI: 2.0-13.7), but not at 25 wk. CONCLUSIONS: Active perinatal management that included universal initiation of neonatal intensive care virtually eliminated intrapartum stillbirths and delivery room deaths, and resulted in survival rates that compare favourably with those of recent studies. However, the policies of active care postponed death in non-survivors. Individual variations in outcome in relation to the infant's condition at birth as reflected by the Apgar scores preclude the making of treatment decisions in the delivery room.

Apgar Score↗
PubMed2004

Short-term outcome after active perinatal management at 23-25 weeks of gestation. A study from two Swedish perinatal centres. Part 3: neonatal morbidity.

AIM: To determine major neonatal morbidity in surviving infants born at 23-25 weeks, and to identify maternal and infant factors associated with major morbidity. METHODS: The medical records of 224 infants who were delivered at two tertiary care centres in 1992-1998 were reviewed retrospectively. At these centres, policies of active perinatal and neonatal management were universally applied. Of the 213 liveborn infants, 140 (66%) survived to discharge. Data were analysed by gestational age and considered in three time periods. Logistic regression models were used to identify factors associated with morbidity. RESULTS: Of the survivors, 6% had intraventricular haemorrhage grade > or = 3 (severe IVH) or periventricular leukomalacia (PVL), 15% retinopathy of prematurity > or = stage 3 (severe ROP) and 36% bronchopulmonary dysplasia (BPD). On logistic regression analysis, severe IVH or PVL was associated with duration of mechanical ventilation (odds ratio, OR: 1.53 per 1-wk increment in duration; 95% confidence interval, CI: 1.01-2.33). Severe ROP was associated with the presence of a patent ductus arteriosus (PDA) (OR: 3.31; 95% CI: 1.11-9.90) and birth in time period 3 versus time periods 1 and 2 combined (OR: 6.28; 95% CI: 2.10-18.74). BPD was associated with duration of mechanical ventilation (OR: 2.71 per 1-wk increment in duration; 95% CI: 1.76-4.18) and with the presence of any obstetric complication (OR: 2.67; 95% CI: 1.07-6.65). Gestational age and birthweight were not associated with major morbidity. Of all survivors, 81% were discharged home without severe IVH, PVL or severe ROP. CONCLUSIONS: Increased survival as a result of active perinatal and neonatal management was associated with favourable morbidity rates compared with those in recent studies. Among survivors born at 23-25 weeks, neither gestational age nor birthweight was a significant determinant of major morbidity.

Analysis of Variance↗
PubMed2003

Caesarean section increases the risk of hospital care in childhood for asthma and gastroenteritis.

OBJECTIVE: To investigate if caesarean section (CS) increases the risk for childhood asthma and gastroenteritis with reference made to children born with vaginal delivery (VD). METHODS: Retrospective study of data from linked Swedish medical service registers--Medical Birth Registry (MBR) and Hospital Discharge Registry (HDR). Data were obtained from women without any background/perinatal morbidity noted, and from children without any neonatal complications. Children that had reached at least 1 year of age and were found in the HDR were considered as cases, whereas children not found in the HDR or hospitalized for other causes than asthma or gastroenteritis were defined as controls. Odds ratios (OR) stratified for year of birth, maternal age, parity and smoking in early pregnancy were calculated. Investigations were made comparing the risk for in hospital treatment for asthma or gastroenteritis in CS children and in VD siblings of CS children. The overall inpatient morbidity in CS and VD children were also investigated. RESULTS: The OR for asthma in CS children was 1.31 [95% confidence interval (CI) 1.23-1.40]. The same OR, 1.31, was found for gastroenteritis (95% CI 1.24-1.38). The OR for CS children having experienced both asthma and gastroenteritis was further increased (1.74, 95% CI 1.36-2.23). The risk for asthma in VD siblings of CS children was not significantly increased, whereas VD siblings experienced a slightly increased risk for gastroenteritis. CS children had an increased overall in hospital morbidity when compared to VD children. CONCLUSION: There is a significant increase of the risk for developing symptoms of asthma and/or gastroenteritis that motivates admission for hospital care in CS children older than 1 year. It is speculated that a disturbed intestinal colonization pattern in CS children may be a common pathogenic factor.

Adult↗
PubMed2003

Actin filament polymerization regulates gliding motility by apicomplexan parasites.

Host cell entry by Toxoplasma gondii depends critically on actin filaments in the parasite, yet paradoxically, its actin is almost exclusively monomeric. In contrast to the absence of stable filaments in conventional samples, rapid-freeze electron microscopy revealed that actin filaments were formed beneath the plasma membrane of gliding parasites. To investigate the role of actin filaments in motility, we treated parasites with the filament-stabilizing drug jasplakinolide (JAS) and monitored the distribution of actin in live and fixed cells using yellow fluorescent protein (YFP)-actin. JAS treatment caused YFP-actin to redistribute to the apical and posterior ends, where filaments formed a spiral pattern subtending the plasma membrane. Although previous studies have suggested that JAS induces rigor, videomicroscopy demonstrated that JAS treatment increased the rate of parasite gliding by approximately threefold, indicating that filaments are rate limiting for motility. However, JAS also frequently reversed the normal direction of motility, disrupting forward migration and cell entry. Consistent with this alteration, subcortical filaments in JAS-treated parasites occurred in tangled plaques as opposed to the straight, roughly parallel orientation observed in control cells. These studies reveal that precisely controlled polymerization of actin filaments imparts the correct timing, duration, and directionality of gliding motility in the Apicomplexa.

Actin Cytoskeleton↗
PubMed2001

Toxoplasma evacuoles: a two-step process of secretion and fusion forms the parasitophorous vacuole.

Rapid discharge of secretory organelles called rhoptries is tightly coupled with host cell entry by the protozoan parasite Toxoplasma gondii. Rhoptry contents were deposited in clusters of vesicles within the host cell cytosol and within the parasitophorous vacuole. To examine the fate of these rhoptry-derived secretory vesicles, we utilized cytochalasin D to prevent invasion, leading to accumulation of protein-rich vesicles in the host cell cytosol. These vesicles lack an internal parasite and are hence termed evacuoles. Like the mature parasite-containing vacuole, evacuoles became intimately associated with host cell mitochondria and endoplasmic reticulum, while remaining completely resistant to fusion with host cell endosomes and lysosomes. In contrast, evacuoles were recruited to pre-existing, parasite-containing vacuoles and were capable of fusing and delivering their contents to these compartments. Our findings indicate that a two-step process involving direct rhoptry secretion into the host cell cytoplasm followed by incorporation into the vacuole generates the parasitophorous vacuole occupied by TOXOPLASMA: The characteristic properties of the mature vacuole are likely to be determined by this early delivery of rhoptry components.

Animals↗
PubMed2000

Toxoplasma gondii uses sulfated proteoglycans for substrate and host cell attachment.

Toxoplasma gondii is an obligate intracellular parasite that actively invades a wide variety of vertebrate cells, although the basis of this pervasive cell recognition is not understood. We demonstrate here that binding to the substratum and to host cells is partially mediated by interaction with sulfated glycosaminoglycans (GAGs). Addition of excess soluble GAGs blocked parasite attachment to serum-coated glass, thereby preventing gliding motility of extracellular parasites. Similarly, excess soluble GAGs decreased the attachment of parasites to human host cells from a variety of lineages, including monocytic, fibroblast, endothelial, epithelial, and macrophage cells. The inhibition of parasite attachment by GAGs was observed with heparin and heparan sulfate and also with chondroitin sulfates, indicating that the ligands for attachment are capable of recognizing a broad range of GAGs. The importance of sulfated proteoglycan recognition was further supported by the demonstration that GAG-deficient mutant host cells, and wild-type cells treated enzymatically to remove GAGs, were partially resistant to parasite invasion. Collectively, these studies reveal that sulfated proteoglycans are one determinant used for substrate and cell recognition by Toxoplasma. The widespread distribution of these receptors may contribute to the broad host and tissue ranges of this highly successful intracellular parasite.

Animals↗
PubMed2000

Genotyping of the capsule gene cluster (cps) in nontypeable group B streptococci reveals two major cps allelic variants of serotypes III and VII.

Forty group B Streptococcus (GBS) isolates obtained from Europe and the United States previously reported to be nontypeable (NT) by capsule serotype determination were subjected to buoyant density gradient centrifugation. From nearly half of the isolates capsule-expressing variants could be selected. For characterization of the remaining NT-GBS isolates, the capsule operon (cps) was amplified by the long-fragment PCR technique and compared by restriction fragment length polymorphism (RFLP) analysis. The patterns from serotype reference isolates (n = 32) were first determined and used as a comparison matrix for the NT-GBS isolates. Using two restriction enzymes, SduI and AvaII, cluster analysis revealed a high degree of similarity within serotypes but less than 88% similarity between serotypes. However, serotypes III and VII were each split in two distant RFLP clusters, which were designated III(1) and III(2) and VII(1) and VII(2), respectively. Among the isolates that remained NT after repeated Percoll gradient selections, two insertional mutants were revealed. Both were found in blood isolates and harbored insertion sequence (IS) elements within cpsD: one harbored IS1548, and the other harbored IS861. All other NT-GBS isolates could, by cluster analysis, be referred to different serotypes by comparison to the RFLP reference matrix. In pulsed-field gel electrophoresis of SmaI-restricted chromosomal DNA, patterns from allelic type 1 and 2 isolates were essentially distributed in separate clusters in serotypes III and VII. A covariation with insertion sequence IS1548 in the hylB gene was suggested for serotype III, since allelic type III(1) harboring IS1548 in hylB, clustered separately. The variation in serotype VII was not dependent on the presence of IS1548, which was not detected at any position in the type VII chromosome.

Adult↗
PubMed2000

Implementation of service screening with mammography in Sweden: from pilot study to nationwide programme.

Establishment of mammography screening in Sweden has progressed logically from pilot study through clinical trials to service screening. Screening with mammography for early detection of breast cancer has been provided by all Sweden's 26 county councils since 1997. It took 23 years from the initial pilot study through clinical trials to the establishment of mammography service screening throughout Sweden. In the screening rounds completed by 1995-96, and provided by all but one county council, 1040000 women participated, corresponding to 81% of those invited. The national average recall rate was 2.2%, and consequently 23000 women were recalled for additional investigations. Eleven county councils invited women aged 40-74, six invited women aged 50-69, the remaining eight invited women between both these age intervals. Mammography outside screening programmes-clinical mammography-is available throughout Sweden. About 100000 women a year were referred for clinical mammography and about 50% of these were either younger or older than those invited for screening. A negative relation between the use of clinical mammography and participation in the screening programmes was noticed.

Adult↗
PubMed2000

What do we really know about the cost-effectiveness of telemedicine?

Telemedicine is still in its infancy, but undergoing rapid development. It is very difficult to evaluate telemedicine. We performed a literature survey (Medline). During the period 1990-8, over 1500 articles on telemedicine were published. Of these, 246 mentioned economic aspects in the abstract (16%). We selected 29 studies although few had demonstrated cost-effectiveness. Benefits for the patients in the form of reduced travel and waiting time must often be weighed against increased provider costs. Up to now, telemedicine in general has not had any significant effect on medical practice, or the structure and organization of health-care. In order to utilize the potential of telemedicine, its integration with traditional health-care is very important. There are country-specific variations in the health systems that make it difficult to generalize the results from one country to another.

Cost-Benefit Analysis↗
PubMed1999

Toxoplasma gondii resides in a vacuole that avoids fusion with host cell endocytic and exocytic vesicular trafficking pathways.

Toxoplasma gondii actively penetrates its vertebrate host cell to establish a nonfusigenic compartment called the parasitophorous vacuole (PV) that has previously been characterized primarily in phagocytic cells. To determine the fate of this unique compartment in nonphagocytic cells, we examined the trafficking of host cell proteins and lipids in Toxoplasma-infected fibroblasts using quantitative immunofluorescence and immunoelectron microscopy. Toxoplasma-containing vacuoles remained segregated from all levels of the endocytic pathway, as shown by the absence of delivery of transferrin receptors, mannose phosphate receptors, and the lysosomal-associated protein LAMP1 to the vacuole. The PV was also inaccessible to lipids (DiIC16, and GM1) that were internalized from the plasma membrane via the endocytic system. In contrast, vacuoles containing dead parasites or zymosan sequentially acquired both endosomal and lysosomal protein markers and host lipids, reflecting the competency of fibroblasts to process phagocytic vacuoles. The mature PV often lies adjacent to the host cell Golgi, suggesting that it may intersect with vesicles from the exocytic pathway. Despite this proximity, the PV was inaccessible to nitrobenzadiazole-labeled sphingolipids exported from the Golgi and did not contain the host protein markers AP1 or beta-COP. Our results demonstrate that Toxoplasma resides in a compartment that excludes delivery of protein and lipid components from the host cell endocytic and exocytic pathways.

3T3 Cells↗
PubMed1999

Heel lancing in term new-born infants: an evaluation of pain by frequency domain analysis of heart rate variability.

The aim of the investigation was to assess pain by frequency domain analysis of heart rate variability (HRV) during a routine heel lancing procedure in term new-born infants. Beat-to-beat heart rate (HR) was recorded in 23 healthy new-born infants on the maternity ward during blood sampling for neonatal screening. A sham heel prick prior to the sharp lancing procedure was performed randomly in half of the infants. Spectral analysis of HRV was assessed for each of the following sequences: (1) baseline (2) sham heel prick (3) sharp heel prick and (4) squeezing the heel for blood sampling. The response to the sham prick did not differ significantly from the sharp prick. Compared with the baseline, sharp lancing gave rise to minor increases in HR and variability in the low frequency band of the spectral analysis. A clear stress response was provoked when the heel was squeezed for blood sampling, indicated by an increased HR and a decreased spectral power in the high frequency band (i.e. lower vagal tone). The different stress responses during the lancing and the squeezing of the heel were clearly illustrated when principal component analysis was applied and the vectors for the changes in HR and spectral pattern were indicated. In conclusion, the squeezing of the heel is the most stressful event during the heel prick procedure.

Blood Specimen Collection↗
PubMed1999

Time-lapse video microscopy of gliding motility in Toxoplasma gondii reveals a novel, biphasic mechanism of cell locomotion.

Toxoplasma gondii is a member of the phylum Apicomplexa, a diverse group of intracellular parasites that share a unique form of gliding motility. Gliding is substrate dependent and occurs without apparent changes in cell shape and in the absence of traditional locomotory organelles. Here, we demonstrate that gliding is characterized by three distinct forms of motility: circular gliding, upright twirling, and helical rotation. Circular gliding commences while the crescent-shaped parasite lies on its right side, from where it moves in a counterclockwise manner at a rate of approximately 1.5 microm/s. Twirling occurs when the parasite rights itself vertically, remaining attached to the substrate by its posterior end and spinning clockwise. Helical gliding is similar to twirling except that it occurs while the parasite is positioned horizontally, resulting in forward movement that follows the path of a corkscrew. The parasite begins lying on its left side (where the convex side is defined as dorsal) and initiates a clockwise revolution along the long axis of the crescent-shaped body. Time-lapse video analyses indicated that helical gliding is a biphasic process. During the first 180(o) of the turn, the parasite moves forward one body length at a rate of approximately 1-3 microm/s. In the second phase, the parasite flips onto its left side, in the process undergoing little net forward motion. All three forms of motility were disrupted by inhibitors of actin filaments (cytochalasin D) and myosin ATPase (butanedione monoxime), indicating that they rely on an actinomyosin motor in the parasite. Gliding motility likely provides the force for active penetration of the host cell and may participate in dissemination within the host and thus is of both fundamental and practical interest.

Animals↗
PubMed1997

A screening for BRCA1 mutations in breast and breast-ovarian cancer families from the Stockholm region.

To identify BRCA1 germ-line mutations in the breast and breast-ovarian cancer families in the Stockholm region, a total of 127 families were screened. DNA from 174 patients from these families were studied using various mutation screening techniques, followed by direct DNA sequencing. Mutations were identified in 7 of 20 families with breast and ovarian cancer and in one family with ovarian cancer only, whereas only 1 family of 106 with breast cancer showed a mutation. Thus, germ-line mutations in BRCA1 were found in one-third of the families with both breast and ovarian cancer, but in only 1% of the breast cancer families. The low frequency of germ-line mutations in the site-specific breast cancer families means that other genes are likely to segregate in these families.

Breast Neoplasms↗
PubMed1997

Assessment of acute pain in preterm infants by evaluation of facial expression and frequency domain analysis of heart rate variability.

In ten preterm infants (postconceptional age 27-35 weeks) facial expression and heart rate variability (HRV) were investigated during three situations: (a) the infant at rest in its crib or incubator, (b) provocation of the withdrawal flexor reflex by application of von Frey's hairs, and (c) lancing and squeezing for blood sampling. Video recordings of facial expressions, mixed at random, were categorised as the baby being either undisturbed, disturbed or in pain and a detailed scoring for each situation was performed. Mean heart rate (HR) was calculated and power spectral analysis was assessed on data from segments of 45-s duration from the three procedures. Flexor withdrawal did not evoke visual signs of pain or influence HRV, but caused a slight increase in HR. The lancing and squeezing of the heel evoked a facial expression of pain in all infants. The HR increased and a reduction in both total HRV and power in the low frequency band of the HRV spectrum was seen during blood sampling. The differentiation between painful and non-painful procedures was more apparent when principal component analysis of HRV was applied.

Acute Disease↗
PubMed1997

Pathogenesis of non-traumatic atlanto-axial subluxation (Grisel's syndrome).

Non-traumatic atlanto-axial subluxation (AAS) is an uncommon complication of upper neck inflammatory processes and head and neck surgery. It is also known under the eponym of Grisel's syndrome (GS). We present a case report of a 6-year-old boy with GS that resulted from a retropharyngeal abscess. A diagnosis was not made until 2 months after the occurrence of infection. Re-evaluation of repeated CT scans of the neck showed the sequential development of AAS. These findings implied that the pathogenesis of GS is a distention of the ligaments between the atlas and axis rather than loosening of the ligaments caused by the spread of an inflammatory edema from the soft tissues of the neck as has been proposed by others.

Atlanto-Axial Joint↗