Biomedical subjects

S Hansson

Publications and source records attributed to S Hansson.

At least 37 records · Page 2Linked to original sources

PubMed2000

Detection of urographic scars in girls with pyelonephritis followed for 13-38 years.

We report the detection and progression of renal scars in girls prospectively followed from their first recognized urinary tract infection. There were 107 infection-prone subjects with a median age of 7.1 years at the first and 21.7 years at the last urography. Of 51 females who ultimately had lesions, 38 had established scars at the first urography. In 18 subjects, new scars were found in previously undamaged kidneys, 5 already with unilateral scarring. There had been a normal urography after the 5th birthday in 8 of those with later scarring. Worsening of scarring was seen in 10 of the 38 subjects with established scars. The renal damage was in most cases slight or moderate. By stepwise logistic regression analysis, grade of reflux and number of pyelonephritic attacks correlated with scarring, and number of pyelonephritic attacks with new scars and worsening of the lesions. In summary, of the females who ultimately had renal lesions, one-third developed new scars. In most of those with established scars at the first urography, the focal character of lesions suggests that most were also acquired. Since reflux and number of pyelonephritic attacks were identified as risk factors, prevention of renal deterioration should be possible.

Adolescent↗

PubMed2000

Surface roughness parameters as predictors of anchorage strength in bone: a critical analysis.

The surface roughness of a bone implant was defined parametrically. The values of the parameters defining the surface were varied. Some traditionally used surface roughness parameters were calculated. By means of a theoretical model the bone-implant interfacial shear strength was estimated. No simple correlation between the values of the surface roughness parameters and the estimated interfacial shear strength was found. It was concluded that the value of the traditional surface roughness parameters as predictors of interfacial shear strength is limited. If however a change of the surface topography of an implant is restricted to scale a positive correlation was found between the theoretical interfacial shear strength and some surface roughness parameters. It is suggested that the bone-implant interfacial shear strength in the general case be estimated by means of strength analyses based upon a study of the size, shape and density of the individual elements constituting the rough surface.

Bone and Bones↗

PubMed2000

Primary and acquired renal scarring in boys and girls with urinary tract infection.

OBJECTIVES: To determine when pyelonephritic renal scarring was detected in children with urinary tract infection (UTI) and characterize those with primary and acquired scarring, respectively. STUDY DESIGN: A population-based cohort of 1221 children (989 girls and 232 boys) with first recognized symptomatic UTI, aged 0 to 15 years, were diagnosed and followed up prospectively at a single children's hospital; 652 had febrile UTI. Seven hundred fifty-three were evaluated by urography. Renal scarring was classified as primary or acquired, the latter without signs of scarring at the first investigation. To evaluate the frequency of recurrent UTI in those with acquired scarring, a comparison with group-matched children without scarring was performed. RESULTS: A total of 74 children without obstruction had renal scarring (acquired in 40). Primary scarring was found in 18 of 21 (86%) of the boys and 16 of 53 (30%) of the girls (P <.001). The majority of boys with scarring had dilated reflux (67%) in contrast to girls (23%). Recurrent UTI was rare in boys, whereas girls with acquired scarring had significantly more febrile recurrences than girls without scarring. CONCLUSIONS: Most boys had primary, probably congenital, reflux-associated renal damage, whereas most girls had acquired scarring related to recurrences of febrile UTI.

Adolescent↗

PubMed2000

Ambulatory blood pressure 16-26 years after the first urinary tract infection in childhood.

OBJECTIVE: To evaluate blood pressure in a population-based cohort with urographic renal scarring after childhood urinary tract infection. DESIGN: Follow-up investigation 16-26 years after the first recognized urinary tract infection. SETTING: University out-patient clinic for children with urinary infections serving the local area. PATIENTS: From the original cohort of 1221 consecutive children with first urinary tract infection diagnosed during 1970-1979, 57 of 68 with non-obstructive renal scarring participated as well as 51 matched subjects without scarring. MAIN OUTCOME MEASURE: 24 h ambulatory blood pressure. RESULTS: Acceptable blood pressure monitorings were obtained from 53 individuals with and 47 without scarring. There were no significant differences between the two groups even when only patients with the most extensive scarring (individual kidney clearance < 30 ml/min per 1.73 m2) or patients with bilateral scarring were compared with the non-scarring group. Mean systolic or diastolic blood pressure above +2 SD were found in 5/53 (9%) and 3/47 (6%) in the scarring and non-scarring group, respectively. Plasma renin activity, angiotensin II and aldosterone concentrations were not significantly different, but atrial natriuretic protein was significantly higher in the scarring group (P = 0.004). CONCLUSION: This study demonstrates a low risk of hypertension two decades after childhood urinary tract infection. It should be stressed that the patients with renal scarring were under close supervision throughout childhood. Those with scarring had higher concentrations of atrial natriuretic protein which might indicate a counter-regulation mechanism.

Adolescent↗

PubMed2000

Implant-abutment interface: biomechanical study of flat top versus conical.

BACKGROUND: Overloading has been identified as a primary factor behind dental implant failure. The peak bone stresses normally appear in the marginal bone. The anchorage strength is maximized if the implant is given a design that minimizes the peak bone stress caused by a standardized load. Clinical studies have shown that it is possible to obtain a marginal bone level close to the crest of the implant. Different implant systems make use of different designs of the implant-abutment interface. Different implant-abutment interfaces imply that the functional load is distributed in different ways upon the implant. According to Saint-Venant's principle, this will result in different stress patterns in the marginal bone when this reaches levels close to the implant crest. PURPOSE: One aim of the study was to theoretically investigate if a conical implant-abutment interface gives rise to a changed stress pattern in the marginal bone, as compared to a flat top interface, for an axially loaded mandibular titanium implant, the neck of which is provided with retention elements giving effective interlocking with the bone. Further aims were to investigate if the way in which the axial load is distributed on the flat top and on the inner conus respectively affects the stress pattern in the marginal bone. The pertinent stress was considered to be the bone-implant interfacial shear stress. It was assumed that the marginal bone reached the level of the implant-abutment interface. METHOD: The investigation was performed by means of axisymmetric finite element analysis. RESULTS: The conical implant-abutment interface of the type studied brought about a decrease in the peak bone-implant interfacial shear stress as compared to the flat top interface of the type studied. This peak interfacial shear stress was located at the top marginal bone for the flat top implant-abutment interface whereas it was located more apically in the bone for the conical implant-abutment interface. The way in which the axial load was distributed on the flat top and on the inner conus respectively affected the peak interfacial shear stress level. CONCLUSION: The design of the implant-abutment interface has a profound effect upon the stress state in the marginal bone when this reaches the level of this interface. The implant with the conical interface can theoretically resist a larger axial load than the implant with the flat top interface.

Alveolar Process↗

PubMed1999

The relation between surface roughness and interfacial shear strength for bone-anchored implants. A mathematical model.

A rough bone implant surface was conceptualized as being built up of pits of different sizes and of different shapes. Hypotheses were formulated regarding the mechanical strength of the interfacial bone based upon the present knowledge of the character of the tissues adjacent to endosseous implants and the mechanical characteristics of different bone constituents. A surface roughness parameter was derived, the pit effectivity factor (fpe), which describes how effective the individual pits of the rough surface are as retention elements with regard to shear. Another surface roughness parameter was defined, the pit density factor (fpd), the value of which depends upon how densely packed the pits are. The interfacial shear strength of a rough implant surface with known microgeometry can be estimated by means of these two surface roughness parameters. The effectiveness of pits of different sizes and of different shapes was investigated using this model.

Algorithms↗

PubMed1999

Urodynamic pattern in asymptomatic infants: siblings of children with vesicoureteral reflux.

PURPOSE: We studied the urodynamic pattern in asymptomatic infants who are siblings of children with vesicoureteral reflux. MATERIALS AND METHODS: Cystometry and perineal electromyography were performed with voiding cystourethrography in 16 male and 21 female infant siblings screened for reflux at age 0.2 to 7.3 months (median 1.1). RESULTS: Vesicoureteral reflux was present in 25% of the male and 10% of the female infants. In those without vesicoureteral reflux unstable bladder contractions were noted in 8% of the male and 16% of the female subjects. In these infants median maximum voiding detrusor pressure was 127 (range 84 to 211) and 72 cm. water (range 42 to 240), respectively, and median bladder capacity was 20 ml. (range 10 to 49 and 10 to 120, respectively). Maximum voiding detrusor pressure was significantly higher in male than in female infants (p <0.01). Perineal electromyography was interpretable in 13 of the 16 male and 16 of the 21 female infants overall. All but 1 female subject had increased activity during voiding, which was also present intermittently in all subjects. CONCLUSIONS: Our study of asymptomatic siblings of children with vesicoureteral reflux has provided results that may be used as reference data for normal urodynamics in early infancy. Instability was rare. Bladder capacity was lower than expected with a predicted capacity at birth of approximately 20 ml. Maximum voiding pressure was high, especially in male subjects. The urodynamic voiding pattern suggests physiological dyscoordination, probably due to immature detrusor-sphincter function.

Female↗

PubMed1999

The implant neck: smooth or provided with retention elements. A biomechanical approach.

A combined three-dimensional and axisymmetric finite element analysis was made of the effect upon the peak interfacial shear stress of providing an axially loaded mandibular dental implant with retention elements all the way up to the crest of the implant as opposed to a smooth neck. The effect of increased wall thickness of the implant and of using bi-cortical fixation as opposed to uni-cortical fixation was also studied. Retention elements at the implant neck were found to bring about a major decrease in the peak interfacial shear stress. Increased wall thickness and bi-cortical fixation also resulted in decreased peak interfacial shear stress but this effect was minor. The interpretation of this was that all these three measures increase the capacity of the implant to carry axial loads. Thus from a biomechanical viewpoint it appears to be advantageous to provide the neck of screw-shaped implants with retention elements, for example a rough surface of suitable micro-architecture and/or a micro-thread. It is furthermore suggested that retention elements at the implant neck will counteract marginal bone resorption in accordance with Wolff's law. This paper is a revision of: Hansson, S. (1997) Some steps to improve the capacity of dental implants to resist axial loads. In: Hansson, S., ed. Towards an optimized dental implant and implant bridge design: A biomechanical approach. Thesis. Göteborg: Chalmers University of Technology.

Alveolar Process↗

PubMed1999

Urinary tract infections in children below two years of age: a quality assurance project in Sweden. The Swedish Pediatric Nephrology Association.

The objective of this study was to evaluate the basis for diagnosis and assessment of children <2 y of age with urinary tract infections (UTI) and to describe their subsequent management as currently practised in Sweden. The study was a prospective, multicentre project as part of a programme for quality assurance. A total of 2309 children (1111M, 1198F) was studied during a 2-y period. Of the population at risk, 1.6% of both boys and girls were diagnosed with a UTI. This represents a minimum figure. Suprapubic bladder aspiration was mainly used during the first year of life, with the highest frequency in the youngest infants. Adhesive bags were used in half of the children, and the frequency increased with age. Imaging of the urinary tract was performed in 97% of the children. Vesicoureteric reflux was the most common finding, occurring in 36% of the girls and 24% of the boys. The presence of dilatation of the upper urinary tract correlated significantly to the presence and grade of reflux. Initial intravenous therapy was given to 31% of the children and long-term antibacterial prophylaxis to 20%. Major differences were found between centres in diagnostic rate, urine sampling technique and the use of parenteral therapy. In conclusion, this study showed a high diagnostic rate of urinary infections in children below 2 y of age. The urine sampling technique was optimal (suprapubic aspiration) in half of the infants, but less reliable in the children above 1 y of age. The frequency of imaging investigations of the urinary tract was high. The strategies for diagnosis and treatment varied considerably among centres.

Age Distribution↗

PubMed1999

Vesico-ureteric reflux: occurrence and long-term risks.

The prevalence of vesico-ureteric reflux in the general population is unknown, but it is increased in risk groups, such as children with symptomatic urinary tract infection, schoolgirls with asymptomatic bacteriuria, first-degree relatives of patients with reflux and children with prenatal dilatation of their upper urinary tract. Children and adults with pyelonephritic renal scarring are at risk of serious long-term complications, e.g. hypertension and renal failure. Modern paediatric care, with early detection and treatment of urinary tract infections and reflux during childhood and adolescence, may improve long-term prognosis. In the adult patient with established pyelonephritic renal scarring, careful control of hypertension may retard the rate of progression, and angiotensin converting enzyme inhibitors may have renal protective properties.

Adolescent↗

PubMed1999

Medical or surgical management for children with vesico-ureteric reflux?

A critical survey of the literature on treatment of children with vesico-ureteric reflux was carried out in order to create a basis for the new Swedish management policy. There are few studies that meet modern standards of scientific methodology and provide adequate patient numbers. The only large investigations that randomized patients to operative or non-operative treatment were the Birmingham Reflux Study and the International Reflux Study in Children. In these studies, long-term outcome of renal status and renal function, as well as the number of recurrent infections, were independent of treatment modality. Although pyelonephritic recurrences were less common in the surgically managed group, this did not influence appearance of renal damage. There is no evidence to indicate clear superiority of either medical or surgical management. Further studies are needed to address such questions as the optimal duration of antibacterial prophylaxis and the effect of a dilating reflux that persists into adulthood.

Adolescent↗

PubMed1999

Minimum incidence and diagnostic rate of first urinary tract infection.

OBJECTIVE: To study awareness of urinary tract infections (UTIs) by determining the diagnostic rate of first UTI in children <2 years of age and to estimate the minimum incidence. METHODS: Twenty-six of a total of 43 pediatric centers participated in the study. Sixty-four percent of the total childhood population <2 years of age was covered. The number of all children included in the study was used to calculate the diagnostic rate. Only UTI confirmed by either suprapubic aspiration (any growth) or midstream or bag samples with >/=100 000 bacteria/mL, together with a positive nitrite reaction, was used to estimate the minimum incidence. RESULTS: The mean diagnostic rate was 1.5% for boys (range, 0.7%-3.0%) and 1.7% for girls (range, 0.7%-2.9%). The diagnostic rate was significantly higher in June than in December. The mean incidence was 1.0% for both boys and girls (range, 0.3%-3.0% and 0.4%-2.9%, respectively). The minimum cumulative incidence at 2 years of age was estimated to be 2.2% for boys and 2.1% for girls. CONCLUSION: This study suggests a high UTI awareness in Sweden as indicated by a higher diagnostic rate and, despite stricter diagnostic criteria, a higher incidence of UTI in children <2 years of age than previously reported. It is suggested that a high UTI awareness may reduce chronic renal failure because of pyelonephritic renal scarring.

Female↗

PubMed1999

The association between nerve conduction velocity and the compound action potential amplitude during ischemic blocking.

It is not known in detail how the compound sensory nerve action potential amplitude and conduction velocity are associated in nerve ischemia or in other conditions like carpal tunnel syndrome. Ischemia was produced by inflating a tourniquet around the upper arm in five healthy subjects. When median sensory nerve conduction velocities and action potential amplitudes were recorded from the third digit, they decreased in parallel, thereby resembling the blocking process during wrist flexion in healthy subjects. The area under the action potential decreased earlier with longer distances during the ischemic blocking process. A theoretical model is presented in which the area under the compound nerve action potential is determined by the probability for the single fibre action potential to propagate through the internodal distance. This in turn is associated with the internodal conduction time.

Action Potentials↗

PubMed1999

Non-neuronal dopamine in the gastrointestinal system.

1. Dopamine (DA) is a protective agent in the gastrointestinal (GI) tract in both rats and humans. Therefore, we have studied the site of DA production in rat and human GI tract using a variety of techniques, including immunocytochemistry (ICC), in situ hybridization histochemistry, reverse transcription-polymerase chain reaction, HPLC, western blotting and immunoelectron microscopy. 2. We found very high concentrations of DA that persisted after chemical sympathectomy (CS) in the gastric juice, the stomach mucosa and in the pancreas. Both the stomach mucosa and the pancreas also had tyrosine hydroxylase (TH) activity, most of which remained after CS. Double-labelling ICC showed that acid-producing parietal cells and the exocrine pancreas must also be capable of producing DA. 3. We isolated rat stomach parietal cells by cell fractionation and found that both DA and TH activity are present in isolated (denervated) parietal cells. These cells also have other features of aminergic cells: they are immuno- (and mRNA) positive for the DA plasma membrane transporter and vesicular monoamine transporter(s). In both gastric and duodenal mucosa, we demonstrated the presence of significant amounts of the D5 receptor that could serve as a target for locally produced DA. 4. Because DA, its biosynthetic enzymes and its transporters are also found in parietal cells in the human stomach, a mucosal protective system involving DA could be important clinically.

Animals↗

PubMed1998

High tissue content of urokinase plasminogen activator (u-PA) is associated with high stromal expression of u-PA mRNA in poorly differentiated serous ovarian carcinoma.

Urokinase plasminogen activator (u-PA) plays a pivotal role in tissue degradation during tumor spread and metastasis. We have quantitated u-PA in tissue homogenates of 31 serous ovarian tumors and localized u-PA and its mRNA in tissue sections of 26 serous ovarian tumors. The content of u-PA was higher in malignant than in benign tumors, with the highest levels being found in poorly differentiated cancers. In tissue sections, the u-PA mRNA was hybridized with a radiolabeled RNA probe. Signals were almost exclusively found in the epithelium in benign and borderline tumors and in well-differentiated cancers. Poorly differentiated tumors and metastases exhibited prominent stromal expression of u-PA mRNA, whereas epithelial expression was weak or absent. Immuno-histochemical staining co-localized u-PA antigen with its mRNA in the epithelium of benign and borderline tumors and in well-differentiated cancers. Poorly differentiated malignant tumors showed extensive immunostaining in the epithelium in addition to stromal staining. The u-PA mRNA-expressing and u-PA-immunostained cells in the stroma were not tumor cells since no cells in the stroma were positive for cytokeratin. Poorly differentiated tumors had increased numbers of stromal macrophages (CD68), and they co-localized with some of the u-PA-positive cells. The presence of u-PA antigen and the absence of u-PA mRNA in tumor epithelium of poorly differentiated tumors and metastases together with the presence of u-PA mRNA in the stroma suggests production in stromal cells and subsequent binding to receptor sites in tumor cells.

Cell Transformation, Neoplastic↗

PubMed1998

Disappearance of vesicoureteral reflux in children.

OBJECTIVE: To describe the disappearance of reflux in children with vesicoureteral reflux, in whom there are presently no population-based long-term studies. DESIGN: An unselected cohort of children with reflux detected after their first known symptomatic urinary tract infection was followed up prospectively for up to 15 years. SETTING: A single children's hospital in a distinct geographical area at which most children with symptomatic urinary tract infection were treated. PATIENTS: Two hundred thirty children--173 girls and 57 boys--with unilateral (n=130) and bilateral (n=100) reflux. Dilated reflux (grades III-V) was found in 54 patients (23.5%). The frequency of reflux was 34% in girls and 31% in boys who were examined after urinary tract infection. MAIN OUTCOME MEASURE: Disappearance of reflux. RESULTS: The probability of spontaneous disappearance of reflux was estimated using Kaplan-Meier survival curves based on 164 children who underwent multiple voiding cystourethrographies. There was a marked tendency for disappearance of reflux, with 73% of children with dilated reflux having no or only grade I reflux after 10 years. Shorter persistence of reflux was found in children with undilated reflux at the initial investigation and in boys compared with girls. However, age at first investigation was not related to the rate of disappearance, and there was no difference between children with bilateral compared with unilateral reflux. CONCLUSIONS: This study of an unselected group of children with urinary tract infection shows a favorable long-term outcome concerning disappearance of reflux. In children with dilated reflux, this tendency was more pronounced than previously reported.

Child, Preschool↗

PubMed1998

Low bacterial counts in infants with urinary tract infection.

We analyzed the number of colony-forming units in urine cultures obtained by suprapubic aspiration in a group of 366 unselected infants with symptomatic urinary tract infection to relate these findings to factors such as pyuria and vesicoureteric reflux. Seventy-three (20%) of 366 infants had fewer than 100,000 colony-forming units per milliliter. Such low counts were significantly related to low numbers of leukocytes in the urine. Vesicoureteric reflux was equally distributed among children, irrespective of the number of bacteria in quantitative culture. The findings emphasize the importance of sampling technique; in infants, the method of choice is suprapubic aspiration, or catheterization, which eliminates the risk that urinary tract infection is overlooked because of low bacterial counts.

Bacterial Infections↗

PubMed1998

Expression of the CB1 and CB2 receptor messenger RNAs during embryonic development in the rat.

We mapped the distribution of CB1 and CB2 receptor messenger RNAs in the developing rat to gain insight into how cannabinoids may affect embryogenesis. In situ hybridization histochemistry studies were done using riboprobes specific for CB1 or CB2 receptor messenger RNAs. We found that CB1 and CB2 receptor messenger RNAs are expressed in the placental cone and in the smooth muscle of the maternal uterus at the earliest gestational periods studied [from eight days of gestation (E8) through E12]. In the embryo, as early as E11, CB1 receptor messenger RNA is expressed in some cells of the neural tube and, at later embryological stages (from E15 to E21), in several distinct structures within the central nervous system. In addition, high levels of CB1 receptor messenger RNA were also found in areas of the peripheral nervous system such as the sympathetic and parasympathetic ganglia, in the retina and in the enteric ganglia of the gastrointestinal tract. In addition to neural structures, high levels of the CB1 receptor messenger RNA were also present in two endocrine organs, the thyroid gland and the adrenal gland. On the other hand, CB2 receptor messenger RNA is expressed exclusively in the liver of the embryo as early as E13. The region-specific expression of CB1 and CB2 receptor messenger RNAs suggests that these receptors have a functional role during embryogenesis.

Animals↗