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Biomedical subjects

O Svensson

Publications and source records attributed to O Svensson.

At least 37 records · Page 2Linked to original sources
PubMed2000

The synthesis of metoprolol monitored using Raman spectroscopy and chemometrics.

The synthesis of Metoprolol base was studied using Raman spectroscopy with a 785-nm laser, optical fibres, a holographic transmission grating, confocal optics and a charge-coupled device (CCD) detector. The reaction mixture was heated according to a temperature gradient and spectra of the reaction mixture were obtained by focusing the laser beam through ordinary reaction flasks. Because of overlapping bands, multivariate techniques such as principal components analysis (PCA) and partial least-squares projections to latent structures (PLS) were used in the evaluation of the obtained spectra. The use of PCA or PLS against time does not require any calibration samples and a quantitative calibration is not necessary in order to monitor the reaction. A method for reaction endpoint determination, based on euclidean distances in the score space, is presented. The use of multivariate batch control charts have been demonstrated and a number of problems and solutions regarding the sample presentation have been discussed. The effect of spectral pretreatment on the multivariate results is shown and discussed. The monitoring results show that the time to produce Metoprolol base could be reduced.

Antihypertensive Agents↗
PubMed2000

Revision total hip arthroplasty using third-generation cementing technique.

A total of 83 consecutive first-revision total hip arthroplasties were performed in 83 patients using pressurized vacuum-mixed cement, a third-generation cementing technique. At a median follow-up of 3.6 years (range, 1.5-6.3 years), the overall failure rates (radiographic loosening, re-revision, or both) were 39% for the femoral components and 30% for the acetabular components. With definite radiographic loosening as an endpoint, the cement-bone interface achieved was the only significant factor to predict stem durability, with an adjusted odds ratio of 1.8 (95% confidence interval, 1.1-3.0). On the acetabular side, bone stock was the only significant factor, with an adjusted odds ratio of 5.3 (95% confidence interval, 4.0-27.7). In this retrospective cohort study, femoral cement pressurization per se did not appear to improve the results over those of other studies using second-generation techniques.

Adult↗
PubMed2000

Pain and orthopaedic and neurologic signs after lumbar discectomy: a 2-year followup.

In a prospective study of 161 consecutive patients with lumbar discectomy, pain, lumbar mobility, and neurologic and root tension signs were followed up for at least 2 years. Sciatica and root tension signs decreased promptly after surgery and remained largely unchanged during followup, which was not the case for neurologic signs. Similarly, pain relief was not associated with neurologic signs but was associated with lumbar mobility and root tension signs. Patients without neurologic symptoms before surgery did not report more sciatica after 2 years than did those with positive neurologic signs before surgery. Positive crossed Lasegue sign and restricted lumbar mobility before surgery predicted better chances for postoperative pain relief. Patients with a ruptured anulus fibrosus at surgery had less sciatica and back pain after surgery than did patients with an intact anulus fibrosus.

Adult↗
PubMed1999

Association of the aggrecan keratan sulfate-rich region with collagen in bovine articular cartilage.

Aggrecan, the predominant large proteoglycan of cartilage, is a multidomain macromolecule with each domain contributing specific functional properties. One of the domains contains the majority of the keratan sulfate (KS) chain substituents and a protein segment with a proline-rich hexapeptide repeat sequence. The function of this domain is unknown but the primary structure suggests a potential for binding to collagen fibrils. We have examined binding of aggrecan fragments encompassing the KS-rich region in a solid-phase assay. A moderate affinity (apparent Kd = 1.1 microM) for isolated collagen II, as well as collagen I, was demonstrated. Enzymatic digestion of the KS chains did not alter the capacity of the peptide to bind to collagen, whereas cleavage of the protein core abolished the interaction. The distribution of the aggrecan KS-rich region in bovine tarsometatarsal joint cartilage was investigated using immunoelectron microscopy. Immunoreactivity was relatively low in the superficial zone and higher in the intermediate and deep zones of the uncalcified cartilage. Within the pericellular and territorial matrix compartments the epitopes representing the aggrecan KS-rich region were detected preferentially near or at collagen fibrils. Along the fibrils, epitope reactivity was non-randomly distributed, showing preference for the gap region within the D-period. Our data suggest that collagen fibrils interact with the KS-rich regions of several aggrecan monomers aligned within a proteoglycan aggregate. The fibril could therefore serve as a backbone in at least some of the aggrecan complexes.

Aggrecans↗
PubMed1999

Material and design in haematogenous implant-associated infections in a rabbit model.

We used 111 rabbits to study the susceptibility to intravenously injected bacteria of conventional stainless steel plates, and titanium plates of either traditional design or of the PC-FIX concept, that is less traumatic to bone. After plating, the animals were given between 1 x 10(8) and 2 x 10(9) colony forming units of Staphylococcus aureus Wood 46 intravenously. Significant differences in infection rates (positive cultures) were found between conventional stainless steel plates (36-67% infected, depending on inoculum size) and titanium PC-FIX plates (6-7% infected). In fact, the infection rate at the PC-FIX plate did not differ from sham operated animals. Since conventionally designed titanium plates had an intermediate infection rate, it appears that design and material both are important for the risk of infection.

Animals↗
PubMed1999

Local plate infections in a rabbit model.

We used 30 New Zealand white rabbits to compare the susceptibility to bacterial challenge of two different orthopaedic implants: a standard-design stainless steel plate, or a PC-FIX titanium plate applied on the right tibia were compared with sham operated animals. Directly after surgery Staphylococcus aureus (10(8)-10(9) colony forming units) were inoculated close to the plate. The infection rate in the group of plated animals was 11/20 (stainless steel plates 6/10, PC-FIX titanium plates 5/10) and in sham operated animals only 1/10. Thus, a foreign body increased the risk for infection (p = 0.02). However, the implant type did not appear to be of major importance when the bacteria were inoculated locally. In experimental haematogenous infections, by contrast, implant design and material are considered to be important. This may either indicate different pathogenic mechanisms in locally and haematogenously induced infections, or simply that the large number of microorganisms in local inoculation 'overload' the normal defence systems.

Animals↗
PubMed1999

Diagnosis and prognosis in lumbar disc herniation.

In a prospective 2-year followup study of 160 consecutive patients undergoing primary surgery for suspected lumbar disc herniation, the authors studied the diagnostic and prognostic factors by using stepwise logistic regression analysis. When the different factors were entered in the same order as presented clinically, history and pain analysis contained most of the predictive information available. When all factors were entered simultaneously in the computations, the following factors (in order of relative importance) predicted relief of sciatica after 2 years: rupture of the anulus (as opposed to bulging disc or negative exploration), no preoperative comorbidity, and male gender. The following factors predicted return to work at 2 years: no preoperative comorbidity, duration of sciatica less than 7 months, education or vocational training in addition to compulsory school, age younger than 41 years, male gender, and no previous nonspinal surgery. Return to work does not seem to be a valid result parameter in lumbar disc surgery. The most important physical signs were root tension tests and lumbar range of motion, whereas neurologic signs were of secondary importance. Many people have asymptomatic herniations, and today supersensitive diagnostic imaging is widely available. Thus, the importance of clinical evaluation has increased, and most of the relevant information can be obtained by listening to the patient. A simple anamnesis apparently is a good alternative to psychologic tests in surgical triage.

Absenteeism↗
PubMed1999

Tympanic pressure gradients and otoacoustic emissions.

OBJECTIVE: The purpose of this study was to investigate the immediate effects of tympanic over- and under-pressure, induced by variations in ambient pressure on click-evoked otoacoustic emissions (CEOAEs) in healthy individuals. It was of particular interest to elucidate whether changes in the CEOAE response in both spectral and time domains could be attributed not only to tympanic, but also to cochlear influence. DESIGN: Nine healthy subjects with normal hearing and middle ear pressure were exposed to ambient pressure changes in a pressure chamber. The pressure was progressively changed in 100 daPa steps to accomplish an increase and a decrease in tympanic pressure. Pressure equilibration of the middle ear was avoided. The relative tympanic over- and under-pressure (+/- 320daPa) was monitored by tympanometry and the CEOAEs recorded at every step of tympanic pressure change. RESULTS: There was a statistically significant reduction of the otoacoustic emission (OAE) response levels and reproducibility already at 100 daPa of ambient pressure change. The OAE response was progressively reduced by increased pressure gradients. The CEOAEs recorded during progressive tympanic over- and under-pressure also had increasingly shorter latencies. These changes of the OAE response characteristics were most pronounced in the 750 to 3000 Hz frequency bands. CONCLUSIONS: The progressive attenuation of the OAE response and the concomitant shortening of the OAE response latencies were observed during a combination of altered middle and inner ear pressure. Although the middle and inner ear influence cannot be separated we suggest, based on our findings, that the shortening of latencies may partly be caused by inner ear pressure changes and stiffening of the labyrinthine membranes. Further studies are needed to more specifically clarify the relative contribution of the tympanic and labyrinthine influence, respectively, for the various aspects of pressure influence on the OAE response.

Acoustic Impedance Tests↗
PubMed1999

Postoperative mental impairment in hip fracture patients. A randomized study of reorientation measures in 223 patients.

Mental impairment is a common and serious complication in geriatric surgery. We studied 223 hip fracture patients. They were over 64 years of age (mean 81), with no history of mental deterioration and acutely admitted to hospital from independent living conditions. They were randomized into two groups. One of these was subjected to reorientation measures during the perioperative phase, i.e., presurgery admission to the orthopedic ward, accompanied home visits during the hospital stay and access to reorientation devices--they received a large clock, calendar, radio, TV-set, telephone and were encouraged to wear their own clothing. Otherwise, there were no differences in the treatment given to the two groups. We used monitoring of cognitive function with the Short Portable Mental Status Questionnaire (SPMSQ) and a feedback program for evaluation of the treatment results. There was a low incidence of postoperative cognitive deterioration in both groups, compared with historical controls. However, no difference in mental status was noted when we compared the two groups. The conclusion is that attributes were less important than the psychological environment for postoperative mental deterioration. The mean total continuous hospitalization (transfers between departments and hospitals included) in the reorientation group was 22 (95% CI: 17-43) days, the corresponding figures for the controls were 30 (14-29) days.

Aftercare↗
PubMed1999

Continuity, assessment and feedback in orthopaedic nursing care practice is cost-effective.

Hip fracture treatment and rehabilitation are often considered as separate issues and generally performed in different locations. The rapidly increasing proportion of patients that is old and very old now calls for a new approach. This is a prospective study of 909 consecutive hip fracture patients, over 64 years old, admitted to hospital from an independent living situation. In a specialized hip fracture unit, 256 patients were given an early and intense rehabilitation program. It focused on continuity, feedback, reorientation and continuous monitoring of cognitive function and activities of daily living (ADL). Eighty-five percent of the patients could return directly to their own home after the initial treatment period. The mean total utilization of health care resources during the first 4 months after the injury was lower (28 institutional days) than in 286 historical controls given conventional rehabilitation (39 days, p < 0.05). At 4 months, 81% of the patients still lived in their own home vs. 72% of the controls and the 1-year mortality was 14% (21% in the controls, p < 0.05). After the project had been completed 297 patients formed an additional control group. In this group the proportion discharged to their own home decreased to 44% and the number of bed-days during the first 4 months returned to the pre-study level (39 days). It thus appears to be cost-effective to allocate sufficient rehabilitation resources early in the treatment of elderly patients with hip fractures. Annual savings in the catchment area due to the intervention were calculated to approximately 5,000,000 SEK. Continuous assessment and adequate continuity gives the staff emotional feedback, which promotes their personal commitment.

Activities of Daily Living↗
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

Proteoglycan turnover during development of spontaneous osteoarthrosis in guinea pigs.

OBJECTIVE: The study was performed to clarify the metabolic background of the variations in proteoglycan concentrations, relating to ageing and the spontaneous development of osteoarthrosis in guinea pigs. METHODS: Six-, 9- and 12-month-old Hartley guinea pigs were injected intraperitoneally with Na2(35)SO4. The incorporation and degradation of various proteoglycans were analyzed in different areas of tibial articular cartilage during the development of osteoarthrosis. RESULTS: Proteoglycan synthesis was most active in the uncalcified cartilage of 6-month animals and highest in the medial compartment with its presumably higher load. The breakdown of proteoglycans decreased with age. The onset of osteoarthrosis was associated with decreased synthesis of large and small proteoglycans, while the rate of degradation remained unchanged. CONCLUSION: During onset of osteoarthrosis the synthesis of large proteoglycans gradually becomes insufficient to compensate for the simultaneous degradation. This differs from findings in more rapidly progressing, experimental secondary osteoarthrosis, where a substantial increase in the rate of degradation is more conspicuous.

Aging↗
PubMed1998

Effect of an inhibitor of matrix metalloproteinases on spontaneous osteoarthritis in guinea pigs.

Recently discovered chemically modified tetracyclines have been found to be effective inhibitors of matrix metalloproteinase (MMP)-mediated connective tissue destruction in a variety of pathologic processes, including rheumatoid arthritis and osteoarthritis (OA). Since the histologic techniques used in our laboratory have been validated in Hartley guinea pigs, which have a high incidence of OA-like changes in the proximal tibia, we have used two tetracyclines which have potent inhibitory capacity against various MMPs, doxycycline (Dox) and a compound known as chemically modified tetracyclines (CMT-7). These were given by mouth to a group of guinea pigs for 4 to 8 months, and we assessed the effect of the compound on morphologic and biochemical aspects of OA. We found that prophylactic CMT-7 given orally decreases OA changes in the knee joints both in vitro and in vivo in the guinea pig OA model. Cartilage fibrillation and destruction, in addition to subchondral bone sclerosis and cyst formation, were all decreased in the central compartment of the medial condyle, which is most affected by OA compared with controls. Also collagen, hyaluronan and proteoglycancontent in cartilage was higher in the CMT-7 treated group compared with controls. In contrast, OA changes were not decreased in the Dox group. Our results confirm that various tetracyclines have reduced the severity of OA in animal models, indicating the therapeutic potential of this class of compounds in the future.

Animals↗
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↗