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Biomedical subjects

O Svensson

Publications and source records attributed to O Svensson.

At least 19 recordsLinked to original sources
PubMed1998

Parental behaviour in relation to the occurrence of sneaking in the common goby.

To investigate whether male common gobies, Pomatoschistus microps (Pisces, Gobiidae), treat their offspring differently depending on confidence of paternity, we conducted an experiment in which randomly chosen males either spawned alone with a female, or with a sneaking male present. Males did not treat their brood differently whether they had experienced sneaking or not. Our estimates of parental care, nest defence against potential egg predators and fanning rate were the same for the two treatments. Furthermore, there was no difference in filial cannibalism (eating their own progeny) between males that had been sneaked upon and males that had not. However, nest-guarding males that ate some of their brood had a smaller original brood area than other males. This suggests either an increase in paternal expenditure with increased brood size or a threshold value (absolute brood size or proportion of nest space covered) above which males do not cannibalize eggs. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Parental behaviour in relation to food availability in the common goby.

In the common goby, Pomatoschistus microps (Pisces, Gobiidae), males build nests under mussel shells where they care for the eggs until hatching. To investigate why male common gobies cannibalize their own eggs (filial cannibalism), we conducted a feeding experiment. Males given little food ate from their eggs more often than males given food in excess. However, males given mussel meat in excess did not eat more of their eggs than males fed with both mussel meat in excess and goby eggs. This may suggest that male common gobies cannibalize their eggs to obtain energy rather than essential nutrients lacking in other diets. Moreover, males ate their whole clutch if it was exceptionally small regardless of food treatment, suggesting that males stop investing in their clutch if its reproductive value is less than the cost of guarding it. Thus, whole clutch cannibalism and partial clutch cannibalism seem to be governed by different factors. Furthermore, poorly built nests were associated with starved males, suggesting that nest concealing is costly. There was an association between how well the nest was built and partial clutch filial cannibalism, suggesting that the appearance of the nest may indicate the condition of the male, and thus the risk of filial cannibalism. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Mechanical load and primary guinea pig osteoarthrosis.

Hartley guinea pigs spontaneously develop knee osteoarthrosis. The reproducible course, the changes first appearing at the central medial condyle and then progressing peripherally and laterally, makes this animal a suitable model for intervention studies. We studied the effect of load, and randomized 9-month-old male animals into 4 groups: immediate killing, mid-femoral 30 degrees-valgus osteotomy, sham operation or below-knee amputation. After 3 months, the proximal tibia was step-sectioned and examined stereologically by light microscopy. Local load-redistribution from the medial to the lateral condyle (osteotomy) reduced cartilage fibrillation by 22% medially and increased it 27% laterally. Subchondral bone thickness decreased by 36% in the medial condyle. In contrast, general load-redistribution (amputation) did not affect the progress of fibrillation, despite pronounced bone atrophy. Cartilage thickness, however, did not change; calcified cartilage thickness remained remarkably constant, and it was always higher on the lateral side. Therefore tide-mark advancement does not appear to be an important mechanism in early guinea pig osteoarthrosis. Thus, when the natural course of guinea pig osteoarthrosis is interfered with surgically, in the early phase, changes in bone are more conspicuous than those in cartilage, which further indicates that mechanical load and stiffness gradients are important pathogenetic mechanisms.

Amputation, Surgical↗
PubMed1997

Correlation of morphologic and biochemical changes in the natural history of spontaneous osteoarthrosis in guinea pigs.

OBJECTIVE: To study how the concentrations of proteoglycans (PGs) and collagen change in various parts of tibial articular cartilage during aging, and to evaluate the development of spontaneous osteoarthrosis (OA) in guinea pigs. METHODS: PGs were extracted from guinea pig cartilage samples using 4M guanidine hydrochloride, and the amount of hydroxyproline was determined in the extraction remainder. The molecular size and aggregation of PGs were analyzed by electrophoresis, and the glycosaminoglycan composition was assessed by high-performance liquid chromatography. RESULTS: The PG concentration was proportional to the load distribution. However, when OA became histologically manifest, the PG concentration decreased by 50% (from a mean of 44 microg to 22 microg per mg fresh tissue) and the collagen level decreased by 40% (from a mean of 17 microg to 10 microg per mg fresh tissue), while the proportion of water increased by 13% (from a mean of 710 mg to 800 mg per mg fresh tissue). CONCLUSION: Unmineralized cartilage can, within physiologic load limits, respond to increased mechanical demands by increasing the PG and collagen concentrations. Beyond a certain limit, however, the cartilage can no longer compensate for further increases in stress, which results in cartilage degeneration and losses of matrix constituents. These losses seemed to appear earlier in the disease process than has been described in previous animal models of secondary OA.

Aging↗
PubMed1997

Ultrastructural immunolocalization of bone sialoprotein in guinea-pig osteoarthritis.

In diarthrodial joints, bone and cartilage are structurally and functionally inseparable as shown in osteoarthritis (OA), where subchondral bone changes are integral in the disease process. By ultrastructural immunohistochemistry using polyclonal antibodies against guinea-pig bone sialoprotein (BSP), we investigated the distribution of this matrix protein at the osteocartilaginous interface in Hartley guinea-pig knees at different stages of primary osteoarthritis. Between 6 and 12 months they developed moderate osteoarthritic changes predominantly in the medial condyle, progressing to severe OA at 30 months. In all age groups BSP labeling was concentrated to the osteocartilaginous interface at a 1 micron narrow zone at the interface. In the medial osteoarthritic condyle, BSP was increased as compared with the lateral nonosteoarthritic condyle, but only at 30 months, when cartilage fibrillation correlated to BSP. Our observations suggest that altered BSP abundance may be a potential bone marker for late stage OA, while early events in bone cannot be monitored. BSP is expressed early in osteogenesis and may have a role in biological mineralization and growth. Since a sharp zone of intense BSP labeling remains at a remarkably constant level throughout life in guinea-pigs, BSP may have an important structural and/or regulating role at the interface. The protein may act as an anchor of calcified articular cartilage to subchondral bone or by regulating mineralization at the osteocartilaginous interface.

Animals↗
PubMed1997

The appearance and disappearance of cognitive impairment in elderly patients during treatment for hip fracture.

We studied the natural course of cognitive state in 256 consecutive hip fracture patients who were admitted from an independent living situation. We employed a treatment programme that focused on preventing postoperative cognitive impairment. Cognitive function was assessed with the SPSMQ screening test. The incidence of postoperative cognitive impairment among those lucid on admission was 13%, which generally was reversed before discharge. Thirty-seven percent were cognitively impaired on admission; of those, 51% reached normal test scores while in hospital. Those who recovered within the first week had as good a prognosis during the first year as those who remained lucid throughout the hospital stay. Cognitive impairment was associated with an increased complication rate, e.g. a three-fold increase of early fracture displacement and a four-fold increase of wound infection. This increased risk was present even in patients with mild/moderate cognitive impairment and could not entirely be explained by age. Our results suggest that it is possible to decrease postoperative cognitive impairment by routine monitoring of cognitive status, a high level of continuity and a reorientation programme. The routine assessment of the cognitive function is recommended in geriatric patients who are admitted for surgery.

Activities of Daily Living↗
PubMed1997

Phylogenetic placement and characterization of a new alpha-2 proteobacterium isolated from a patient with sepsis.

An alpha-2 proteobacterium, previously unknown as determined by its phylogenetic characteristics and the DNA sequence of its 16S rRNA gene, was isolated from a patient who presented an unusual clinical picture, including high remitting fever and multiorgan involvement. The bacterium was detected in multiple plasma samples, obtained during the acute phase of the disease, after cocultivation in cell culture media. Electron microscopy of the organism showed a three-layer laminar cell wall and electron-dense granules within the cytoplasm, as well as a polar flagellum. By means of PCR followed by sequencing of amplified 16S ribosomal DNA fragments, the bacterium was found to differ from all species for which ribosomal sequence information is available. It is here provisionally named the Rasbo bacterium. At a subsequent relapse, the bacterium was identified in pericardial fluid both by PCR/sequencing and by direct electron microscopy. At a second relapse, it was again cultured from plasma. After in vitro adaptation to solid media, the MICs of various antibiotics could be determined. A transient immunoglobulin M (IgM) but no IgG response to the bacterium was found by an indirect immunofluorescence test, as well as by an immobilization test during the acute phase of the disease.

Adult↗
PubMed1997

Prospective payment systems and hip fracture treatment costs.

We studied the health care consumption and costs after a hip fracture in 1,060 and 1,178 elderly patients admitted from their own home before and after the implementation of a prospective payment system in Stockholm. The total number of bed-days was estimated by merging the inpatient database and the municipal records of living accommodations for the elderly. By using a detailed patient-related accounting system and separating cost for surgery and "hotel" cost, we could compare costs in different types of rehabilitation. After the change in reimbursement system, the orthopedic stay was almost halved from 20 to 12 days. This was achieved by earlier and increased discharge to geriatric wards, where bed-day consumption doubled (107%), so that the total cost actually increased by 12%. This is not readily apparent from the official heath care statistics, which depict a more favorable cost development, as diagnosis-related registration for a large part of the geriatric care is no longer included. In contrast, a rehabilitation program in one of the acute hospitals, emphasizing continuity in the postoperative phase, reduced the total cost for treatment and rehabilitation by 12%. A prospective reimbursement aiming at reducing the costs of acute care does not necessarily result in overall savings.

Aged↗
PubMed1997

The cost of a hip fracture. Estimates for 1,709 patients in Sweden.

We calculated the costs related to hip fractures and estimated the potential cost savings from preventing hip fractures. Subjects for this retrospective study were 1,709 hip fracture patients admitted for a primary hip fracture during 1992 in Stockholm, Sweden. Direct costs were compiled for the services of hospital orthopedics, hospital geriatrics, nursing homes, home for the elderly, group living, other acute hospital care, and municipal home help. The direct costs per patient during 1 year after a fracture amounted to about USD 40,000. The county council was responsible for 59% of the direct costs during 1 year after a hip fracture, while the remaining 41% were referred to the municipality. In the morbidity group, the potential cost savings per patient from preventing hip fractures was about USD 22,000.

Aged↗
PubMed1997

Clinical history in lumbar disc herniation. A prospective study in 160 patients.

In a prospective study of 160 consecutive patients who underwent primary surgery for lumbar disc herniation, we investigated the value of clinical history for diagnosing the degree of herniation-the main prognostic factor for the postoperative outcome. At surgery, the patients were classified into two groups: intact anulus (negative exploration or protruding disc) and ruptured anulus (subligamentary perforation or complete perforation). The strongest variables predicting the degree of herniation were duration of leg pain, progressive leg pain, educational level and whether or not the patient had previously undergone non-spinal surgery. In patients with ruptured anulus, the median durations of low back pain and sciatica were 16 and 10 weeks, respectively. The corresponding figures for the group with intact anulus were 79 and 50 weeks. 18% of those with ruptured anulus and 39% of those with intact anulus were undergoing medical or psychiatric treatment for other diagnoses; 32% and 55% had previously undergone non-spinal surgery. Thus the two groups differed not only in disc pathology but also in medical, behavioral and social factors that must be taken into account in the preoperative assessment and that may explain discrepancies between impairment and disability.

Activities of Daily Living↗
PubMed1996

Remodelling and pain after uncemented total hip replacement.

We studied 70 patients after uncemented hip replacement with the Lord prosthesis which has a relatively long, completely macrotextured stem. The mean follow up was for 9.5 years. We compared radiographs at one year after operation, at 5 years and at the last follow up. Twenty-five patients (36%) had deep or circumferential pain in the thigh. Of the 44 who were most active at 5 years those with thigh pain had less proximal cortical loss than those without (p < 0.05), most cortical bone formation distally and most often had incomplete radiolucent lines at the mid-stem level, perhaps indicating more elastic displacement of the bone relative to the prosthesis. The presence of radiolucent lines correlated with the increase in cortical width at 5 years (p < 0.01). Cortical remodelling continued after 5 years at all levels except at the tip (p < 0.01). The relative elastic displacement at the interface could cause pain and may contribute to the pattern of bone remodelling in the femur after uncemented hip replacement.

Aged↗
PubMed1996

Bone sialoprotein and osteopontin distribution at the osteocartilaginous interface.

In situ hybridization and ultrastructural immunohistochemistry were used to study the synthesis and distribution of 2 bone matrix proteins, bone sialoprotein and osteopontin, in the proximal tibial epiphysis in 21-, 32-, and 84-day-old rats. Bone sialoprotein messenger ribonucleic acid expression was restricted to cells close to the osteocartilaginous interfaces, whereas osteopontin messenger ribonucleic acid was shown also in the central epiphysis. Moreover, bone sialoprotein synthesis decreased with age, while osteopontin synthesis remained unchanged. Bone sialoprotein and osteopontin immunolabeling were concentrated to a 1-micron thick zone at the border between mineralized articular cartilage and subchondral bone. Compared with the youngest animals, total bone sialoprotein immunolabeling increased in the 32-day-old group, but did not increase further in the oldest group. In contrast, osteopontin immunolabeling increased only in the oldest rats with a decelerating rate of growth. The accumulation and localization of osteopontin at osteocartilaginous interfaces differ from previous observations in metaphyseal bone where osteopontin has been found at the mineralization front of the osteoid, possibly reflecting different roles in the mineralization process in the 2 regions. The different pattern of synthesis of the 2 proteins in the epiphysis corroborates previous indications of different biological roles.

Animals↗
PubMed1996

Ultrastructural changes in primary guinea pig osteoarthritis with special reference to collagen.

Collagen fibril distribution and surface and volume densities in proximal tibial articular cartilage were measured in 6- and 12-month-old Dunkin-Hartley guinea pigs developing primary osteoarthritis. At 12 months, gross fibrillation and ulceration of the articular cartilage were observed on the medial but not on the lateral condyle. Collagen volume density decreased with age in the interterritorial compartments in the superficial zone, medially by 16% and laterally by 8%. In the upper radial zone, collagen volume density decreased interterritorially by 10% on the medial condyle only. Despite gross osteoarthritic changes, only moderate and predominantly focal ultrastructural collagen changes were observed. Thus neither gross network disruption nor fibril thickening seems to be a general feature in early guinea pig osteoarthritis.

Animals↗
PubMed1996

Pain patterns in lumbar disc hernia Drawings compared to surgical findings in 159 patients.

We compared preoperative pain-drawing patterns of 159 patients with findings at lumbar disc surgery. Disc pathology was classified into 2 groups: intact anulus (negative exploration and protruding disc) and ruptured anulus (subligamentary perforation and sequestrated hernia). Patients with intact anulus drew fewer modalities, but more often marked pain in the trunk, neck and upper extremities, than those with ruptured anulus. Certain pain-drawing patterns--e.g., extra text, arrows and nonanatomical pain distribution--have previously been shown to correlate to unfavorable pathological traits in psychometric tests in populations of patients with chronic low back pain. In our study, most of these so-called nonorganic pain-pattern items occurred equally often in the 2 groups. In fact, one third of the patients with ruptured anulus produced pathological drawings according to the scoring system designed by Ransford et al. (1976). Although pain drawings help the investigator to obtain a rapid overview of the patient's pain pattern, the use of penalty points as a preoperative psychological screening instrument in patients with pain that is not chronic may be questioned.

Adult↗
PubMed1996

Focal destruction and remodeling in guinea pig arthrosis.

We investigated the proximal tibiae in adult, middle-aged and old (6,12, and 30 months) guinea pigs with spontaneous arthrosis by quantitative morphometry. Since the cartilage destruction develops predominantly in the medial tibial plateau, the lateral side may serve as an internal control, In established lesions, cartilage destructions were focal, surrounded by a brim of thickened cartilage that was grossly intact, but showed cell clustering, hypertrophy and increased metachromasia. Peripherally, there was a distinct transition to normal-appearing cartilage. Subjacent to the cartilage ulcerations, subchondral bone was thickened. Compared to the lateral plateau the height of the calcified cartilage increased and the surface density of the osteocartilaginous interface decreased. Marrow depletion and cysts developed below the cartilage ulcerations. Cysts seem to develop through fibrous tissue partially undergoing cartilage metaplasia in tiny noduli that subsequently coalesce, liquefy centrally and expand. Superficially, similar fibrocartilaginous proliferations result in incomplete resurfacing and small areas of subchondral resorption; in the periphery of the joint, they form osteophytes. In the guinea pig, arthrosis tissue destruction is thus accompanied by local tissue proliferation.

Animals↗
PubMed1996

Prediction of the outcome after hip fracture in elderly patients.

We report a prospective study of 232 consecutive patients with hip fractures. All were over 64 years of age and living independently before admission to a geriatric orthopaedic ward. We assessed the value, at admission, of predicting factors for independent living at one year after injury. The most important factors were: (1) preinjury function in activities of daily living (grade A or B on the Katz et al (1963) scale); (2) absence of other medical conditions which would impair rehabilitation; and (3) cognitive function better than 7 on the Pfeiffer (1975) mental questionnaire. The odds ratios (95% CI) for these three predictors were 3.5 (1.3 to 9.1), 2.9 (1.3 to 6.1) and 2.4 (1.9 to 4.9), respectively. When all predictors were positive at admission, 92% were living independently at one year; with one, two or three negative predictors, the percentages living independently were 76, 61 and 27, respectively. The median values of the total number of days in hospital, irrespective of diagnosis, during the first year were 12, 24, 29 and 149 days for the four groups. The mortality at one year was predictable on admission only by the number of medical conditions: with no other diagnosis than the fracture the mortality was 0%; with one or two additional conditions the mortality was 14%; and with three or more additional diagnoses it was 24%. These simple and robust predictors can be used to optimise resources for rehabilitation.

Activities of Daily Living↗
PubMed1996

Physical signs in lumbar disc hernia.

In a prospective study of 163 consecutive patients operated on because they were thought to have lumbar disc hernia, the authors investigated whether physical signs could predict the degree of hernia (complete hernia, incomplete hernia, protruded disc, and normal disc) found at surgery. Stepwise discriminant analysis showed that there were only 2 physical signs of diagnostic value: lumbar range of motion and crossed Lasegue sign. By these signs, 74% of the uncontained hernias and 68% of the contained hernias could be correctly classified. Discrimination also was made between intact annuli (negative exploration and protruded disc) versus ruptured annuli (incomplete hernias and complete hernias). Again, lumbar range of motion and crossed Lasègue sign were the only significant parameters, predicting 71% of the ruptured annuli and 80% of the intact annuli. These 2 physical signs are important because the degree of the hernia is the most important prognostic factor for the outcome of lumbar disc surgery. The degree of the hernia also has an impact on the choice of invasive therapy: open surgery, percutaneous surgery, or enzymatic nucleolysis. Neurologic signs often were absent, showed low correlation to the degree of the hernia, and had a limited value for predicting the level of the hernia. However, they are important for the differential diagnosis in distinguishing between radicular and referred pain.

Adolescent↗