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Biomedical subjects

A Salo

Publications and source records attributed to A Salo.

At least 19 recordsLinked to original sources
PubMed2006

A histological and immunohistochemical study of tissue reactions to solid poly(ortho ester) in rabbits.

In many cases only the temporary presence of a biomaterial is needed in tissue support, augmentation or replacement. In such cases biodegradable materials are better alternatives than biostable ones. At present, biodegradable polymers are widely used in the field of maxillofacial surgery as sutures, fracture fixation devices and as absorbable membranes. The most often used polymers are aliphatic polyesters, such as polyglycolic acid (PGA) and polylactic acid (PLA). Poly(ortho ester) is a surface eroding polymer, which has been under development since 1970, but is used mostly in drug delivery systems in semisolid form. The aim of this study was to evaluate the tissue reactions of solid poly(ortho ester) (POE), histologically and immunohistochemically. Resorption times and the effect of 2 different sterilization methods (gamma radiation and ethylene oxide) upon resorption were also evaluated. Material was implanted into the tibia and subcutaneously into the mandibular ramus area of 24 rabbits. Follow-up times were 1-10, 14 and 24 weeks. Histological studies showed that POE induces a moderate inflammation in soft tissue and in bone. At 24 week follow-up, inflammation was mild in soft tissue and moderate in bone. In immunohistochemical studies, no highly fluorescent layer of tenascin or fibronectin was found adjacent to the implant. Resorption of gamma-sterilized rods was faster than ethylene oxide-sterilized rods. The total resorption time was more than 24 weeks in both groups. Clinically the healing was uneventful and the implants the well tolerated by the living tissue. This encourages these authors to continue studies with this interesting new material to search for the ideal material for bone filling and fracture fixation.

Absorbable Implants↗
PubMed2005

Biodegradable polydioxanone and poly(l/d)lactide implants: an experimental study on peri-implant tissue response.

Several implants for orbital wall fracture treatment are available at the present, but they have drawbacks: resorption, risk for migration and foreign body reaction. Alloplastic resorbable implants would be advantageous: no removal operation and no donor side morbidity. The purpose of this study was to evaluate the foreign body reaction, capsule formation and mechanical properties of two bioresorbable implants. PDS and SR-P(L/DL)LA mesh sheet (70/30) with solid frame (96/4) implants (SR-P(L/DL)LA 70,96) were placed into subcutaneous tissue of 24 rats. Immunohistochemistry was used to evaluate reactivity for Tn-C, alpha-actin, type I and III collagens and two mononuclear cells: T-cells and monocyte/ macrophage. GPC, DSC and SEM were performed. Student's t-test or nonparametric Kruskall-Wallis test were used for statistical analysis. Histology of peri-implant capsule exhibited an inner cell-rich zone and an outer connective tissue zone around both materials. Tn-C reactivity was high in the inner and alpha-actin in the outer zone. At the end of the study, the difference of type I collagen versus type III collagen reactivity in inner zone was statistically significant (P<0.0001) as was the difference of type I collagen versus type III collagen reactivity in outer zone (P<0.0001). Immunohistochemistry did not reveal any statistical differences of T-cell and monocyte/macrophage reactivity around PDS versus SR-P(L/DL)LA 70,96 implants, nor any differences as a function of time. PDS were deformed totally after 2 months. SR-P(L/DL)LA 70,96 implants were only slightly deformed during the follow up of 7 months. PDS degraded rapidly in SEM observation. Particles were detaching from surface. SEM observation revealed that polylactide implant was degrading from the surface and the inner porous core became visible. The degradation came visible at 7 months. There were cracks in perpendicular direction towards to the long axis of the filaments. M(w) of PDS decreased fast compared to the polylactide implant. Foreign body reaction was minimal to both materials but continued throughout the whole observation period. Mechanically PDS was poor, it looses its shape totally within 2 months. It cannot be recommended for orbital wall reconstruction. New mesh sheet-frame structure (SR-P(L/DL)LA 70,96) approved to be mechanically adequate for orbital wall reconstruction. It seems not to possess intrinsic memory and retains its shape. The resorption time is significantly longer compared to PDS and is comparable to other studied P(L/DL)LA copolymers. Thus, the new polylactide copolymer implant may support the orbital contents long enough to give way to bone growth over the wall defect.

Absorbable Implants↗
PubMed2002

Radioactive contamination in the Arctic--sources, dose assessment and potential risks.

Arctic residents, whose diets comprise a large proportion of traditional terrestrial and freshwater foodstuffs, have received the highest radiation exposures to artificial radionuclides in the Arctic. Doses to members of both the average population and selected indigenous population groups in the Arctic depend on the rates of consumption of locally-derived terrestrial and freshwater foodstuffs, including reindeer/caribou meat, freshwater fish, goat cheese, berries, mushrooms and lamb. The vulnerability of arctic populations, especially indigenous peoples, to radiocaesium deposition is much greater than for temperate populations due to the importance of terrestrial, semi-natural exposure pathways where there is high radiocaesium transfer and a long ecological half-life for this radionuclide. In contrast, arctic residents with diets largely comprising marine foodstuffs have received comparatively low radiation exposures because of the lower levels of contamination of marine organisms. Using arctic-specific information, the predicted collective dose is five times higher than that estimated by UNSCEAR for temperate areas. The greatest threats to human health and the environment posed by human and industrial activities in the Arctic are associated with the potential for accidents in the civilian and military nuclear sectors. Of most concern are the consequences of potential accidents in nuclear power plant reactors, during the handling and storage of nuclear weapons, in the decommissioning of nuclear submarines and in the disposal of spent nuclear fuel from vessels. It is important to foster a close association between risk assessment and practical programmes for the purposes of improving monitoring, formulating response strategies and implementing action plans.

Agaricales↗
PubMed2001

Does apolipoprotein E influence learning and memory in the nondemented oldest old?

The objective of this study was to analyze the relationship of the apolipoprotein E (apoE) epsilon4 and epsilon2 alleles to learning and memory performances in the nondemented oldest old. Forty-six nondemented persons aged 85 years or over from a randomly selected group of 128 subjects in Vantaa, Finland, were studied. ApoE genotyping was performed using the minisequencing technique. A structured clinical examination and interview were carried out. The test variables studied were learning and memory scores (from the Fuld Object-Memory Evaluation), verbal fluency, and conceptualization (the Similarities subtest of the WAIS-R). We compared apoE-epsilon4 carriers to noncarriers and apoE-epsilon2 carriers to noncarriers. No statistically significant differences were found in any of the test variables. The results failed to confirm the hypotheses that poor cognitive performance is associated with the apoE-epsilon4 allele and good performance with the apoE-epsilon2 allele in the oldest old. This suggests that the apoE alleles do not have a detectable relationship to learning and memory in nondemented very elderly people.

Aged↗
PubMed2001

The effect of age and density of the breast on the sensitivity of breast cancer diagnostic by mammography and ultasonography.

PURPOSE: We studied which, age of the patient or density of the breast accounts for the sensitivity of mammography and ultrasonography (US). Furthermore we studied whether the overall impression on the density of the breast or the density in tumour area accounts for the sensitivity of mammography and ultrasonography. MATERIALS AND METHODS: The material consisted of 572 consecutive histologically and 5 cytologically verified breast cancer cases. Mammography and US examinations were performed immediately before breast cancer operations and information on the findings were received from the original patient files and classified as malignant or benign. The density of breast parenchyma to fatty, mixed or dense in total breast and separately in tumour area was defined by a radiologist group from the original mammograms by comparing to model mammograms. The sensitivity (Se) of mammography and US was compared in 3 age groups (26-49, 50-59 and 60-92) and in the different density classes. RESULTS: Sensitivity of mammography increased by age (density-adjusted OR = 0.2, 95%, CI 0.1-0.5) in age group 26-49 compared to age group 60-92) and with fattiness of the breast (age-adjusted OR= 0.4, 95%, CI 0.1-1.0 for dense breast parenchyma in tumour area compared to fatty breast). Sensitivity of US was inversely related to age (density-adjusted OR = 2.3, 95%, CI 1.0-5.2 in age group 26-49 compared to age group 60-92) and directly related with fattiness of breast (age-adjusted OR = 0.5, 95%, CI 0.2-0.9 by dense breast parenchyma in tumour area compared to fatty breast). Density in the tumour area compared to total breast density was related only mariginally better sensitivity both of mammography (0.4 vs. 0.6) and of US (0.5 vs. 0.6). CONCLUSION: Sensitivity of both mammography and sensitivity of US are independently related both to the age of the patient and to the density of the breast. The effect of age is inverse and that of density parallel between mammography and US on sensitivity. The effect of overall breast density was close to the effect of density at the site of the tumour on the sensitivity of both mammography and US.

Adult↗
PubMed2001

The visibility of cancer on previous mammograms in retrospective review.

AIM: To study how many tumours were visible in restrospect on mammograms originally reported as normal or benign in patients coming to surgery with proven breast cancer. The effect of making the pre--operative mammogram available was also assessed. MATERIALS AND METHODS: Three hundred and twenty initial mammograms of consecutive new breast cancer cases were analysed by a group of radiologists in the knowledge that all patients were later diagnosed with breast cancer. The films were read twice, first without and then with the later (pre-operative) mammograms available. The parenchymal density in the location of the tumour was classified as fatty, mixed or dense, and the tumours were classified as visible or not visible. The reasons for the invisibility of the tumour in the earlier examination were analysed. RESULTS: Fourteen per cent (45) of cancers were retrospectively visible in earlier mammograms without the pre-operative mammograms having been shown, and 29% (95) when pre-operative mammograms were shown. Breast parenchymal density decreased with age and the visibility of tumours increased with age. When considered simultaneously, the effect of age (over 55 vs under 55) was greater (OR = 2.9) than the effect of density (fatty vs others) (OR = 1.5). The most common reasons for non-detection were that the lesion was overlooked (55%), diagnosed as benign (33%) or was visible only in one projection (26%). Growing density was the most common (37%) feature of those lesions originally overlooked or regarded as benign. CONCLUSIONS: Tumours are commonly visible in retrospect, but few of them exhibit specific signs of cancer, and are recognized only if they grow or otherwise change. It is not possible to differentiate most of them from normal parenchymal densities. Saarenmaa, I. (2001). Clinical Radiology56, 40-43.

Adult↗
PubMed2001

Validity of radiological examinations of patients with breast cancer in different age groups in a population based study.

By studying which radiological examinations had been performed before breast cancer operations the aim was to assess, how much benefit ultrasonography (US) and fine or core needle biopsy (FNAB, CNB) gave in addition to mammography, and whether the sensitivity of these examinations varied with the age of the patient. There were 659 consecutive histologically and six cytologically verified breast cancer cases included in the study. Information on mammography, US and FNAB findings were retrieved from the original patient files and classified as malignant or benign. The sensitivity (Se) of these was compared in three age groups (26-49, 50-59 and 60-92). Seventeen (3%) tumours had operations without any radiological examination and 73 (11%) without cytological or histological verification. The sensitivity of mammography (Se=0.92) was statistically significantly higher than the sensitivity of FNAB (Se=0.85, P=0.002) or US (Se=0.86, P=0.003). The sensitivity of mammography increased with age; US sensitivity was slightly higher amongst younger than older patients; the sensitivity of FNAB did not depend on the age of the patient. The sensitivity using a cutoff level of class 5 for mammography was higher (50% typical malignant findings) than for US (45%) or FNAB (30%). Among cases with benign mammographic finding (classes 1-2), the US finding was malignant (classes 3-5) in 4% and FNAB was malignant in 7%. Mammography is a reliable method of breast examination especially for women over 50 years of age. Ultrasonography is beneficial, particularly in younger women, but it is mainly performed as a complementary examination to a mammography and therefore could not be evaluated as an independent examination. FNAB and CNB results were not related to the age of the patient.

Journal Article↗
PubMed2001

A comparative study on four screw-plate locking systems in sheep: a clinical and radiological study.

Four mandibular screw-plate locking systems were studied in sheep. Three to four centimetres angular continuity resections of the mandible were performed and the defects bridged with pre-bent angular reconstruction plates fixed with four screws in the body part and three in the ramus. Each type was used four times. Clinical and radiological examinations were carried out 1 and 2 months later. All sheep were able to eat and ruminate normally throughout the postoperative period. Radiology revealed that 6/16 plates and 5/112 screws fractured during the follow-up period. In one type, no fracture occurred. Screw fracture was confined to just one reconstruction system. Six of 16 mandibles showed slight to moderate bone resorption under the plate. The results point to the internal shortcomings of the systems tested.

Animals↗
PubMed1999

International Arctic Seas Assessment Project.

The International Atomic Energy Agency responded to the news that the former Soviet Union had dumped radioactive wastes in the shallow waters of the Arctic Seas, by launching the International Arctic Seas Assessment Project in 1993. The project had two objectives: to assess the risks to human health and to the environment associated with the radioactive wastes dumped in the Kara and Barents Seas; and to examine possible remedial actions related to the dumped wastes and to advise on whether they are necessary and justified. The current radiological situation in the Arctic waters was examined to assess whether there is any evidence for releases from the dumped waste. Potential future releases from the dumped wastes were predicted, concentrating on the high-level waste objects containing the major part of the radionuclide inventory of the wastes. Environmental transport of released radionuclides was modelled and the associated radiological impact on humans and the biota was assessed. The feasibility, costs and benefits of possible remedial measures applied to a selected high-level waste object were examined. Releases from identified dumped objects were found to be small and localised to the immediate vicinity of the dumping sites. Projected future annual doses to members of the public in typical local population groups were very small, less than 1 microSv--corresponding to a trivial risk. Projected future doses to a hypothetical group of military personnel patrolling the foreshore of the fjords in which wastes have been dumped were higher, up to 4 mSv/year, which still is of the same order as the average annual natural background dose. Moreover, since any of the proposed remedial actions were estimated to cost several million US$ to implement, remediation was not considered justified on the basis of potentially removing a collective dose of 10 man Sv. Doses calculated to marine fauna were insignificant, orders of magnitude below those at which detrimental effects on fauna populations might be expected to occur. Remediation was thus concluded not to be warranted on radiological grounds.

Animals↗
PubMed1999

Lag-screw fixation of anterior mandibular fractures using biodegradable polylactide screws: a preliminary report.

PURPOSE: The purpose of this study was to evaluate the utility of biodegradable, self-reinforced poly-L-lactide screws (SR-PLLA) for lag-screw fixation of anterior mandibular fractures. PATIENTS AND METHODS: SR-PLLA lag-screws were used to stabilize anterior mandibular fractures in 11 patients. Maxillomandibular fixation was used to treat concomitant mandibular condyle fractures for 2 weeks in four patients and for 1 and 5 weeks in two patients. Clinical and radiologic follow-up lasted for 6 months in 36% of patients and for 1 year in 64%. RESULTS: Healing of all anterior fractures was uneventful, with no displacement or delay of bony union. No adverse reactions to the biodegradable screws were seen during follow-up. CONCLUSION: Biodegradable SR-PLLA screw fixation seems to be a new and promising way of treating anterior mandibular fractures.

Absorption↗
PubMed1999

The visibility of cancer on earlier mammograms in a population-based screening programme.

The aim of this study was to examine how frequently the later-round screen-detected and interval breast cancers were visible in earlier screening mammograms by retrospective review and to compare their radiological and clinicopathological features with those diagnosed by primary screening. In a population-based mammography screening programme 63,731 women aged 50-59 years were invited and 56,158 examinations were carried out in the period 1987-1992 in the Tampere area in Finland. A total of 276 breast cancers were detected, of which 131 were diagnosed on later screening rounds or were interval cancers. A retrospective review of previous screening mammograms was carried out in 130 cases by the radiologist who diagnosed the breast cancer and thus knew the exact location of the tumour, no blinded review was carried out. 43 (33%) cancers were visible, 84 (65%) were not visible and 3 (2%) not included on the mammogram in a retrospective review. Later round screen-detected cancers were statistically significantly more often visible in earlier screening mammograms (43%) than interval cancers (19%) (P = 0.002). Tumours missed by screening mammography but which were visible on retrospective review were often histologically well-differentiated and were more often diagnosed in the subsequent screening round than by clinical diagnosis as interval cancers. If all retrospectively visible interval cancers had been diagnosed by screening 19% (10/54) of the interval cancers could have been avoided. If all retrospectively visible cancers had been diagnosed at the time of false-negative screening or assessment 65% (84/130) of all patients would have benefitted from an earlier diagnosis compared with the actual figure of 31% (41/130).

Breast Neoplasms↗
PubMed1999

Mixture of epsilon-caprolactone-lactide copolymer and tricalcium phosphate: a histological and immunohistochemical study of tissue reactions.

In cranio-maxillofacial surgery, bone transplantation is needed for treatment of bony defects. An autograft, allograft or biomaterial can be used. Autogenous bone grafts are considered to be the best materials available, but there are some disadvantages in their use including donorsite morbidity, need for a second operative site and limited graft supply. A search for new bone-graft materials therefore remains necessary. We prepared a mixture of tricalcium phosphate (TCP), which is a resorbable, non-toxic, osteoconductive ceramic material and epsilon-caprolactone-lactide copolymer P(epsilon-CL/DL-LA), a resorbable polymer, and placed it in the dermis and in mandibular bone defects in 13 rabbits. Follow-up times were two, three, seven, eight, 12, 15 and 18 weeks, tissue reactions were assessed, histologically and immunohistochemically. Times of resorption of the material from tissues were reported. We found that the mixture caused a mild inflammatory reaction when placed in bone and severe inflammation when placed in dermis. No highly fluorescent layer of tenascin or fibronectin was found surrounding the implant area. The mixture was excellent to handle and very easy to place into bone defects. The results are promising and have led us to continue development of the mixture.

Journal Article↗
PubMed1998

The 3-dimensional kinematics of the walking gait cycle of children aged between 10 and 24 months: cross sectional and repeated measures.

The purpose of this study was to examine the 3-dimensional kinematics of 'normal' walking gait in young children. A cross sectional study using nine children aged between 10 and 24 months, filmed whilst walking at natural speed, was undertaken using two gen-locked video cameras. The children were at different stages of walking development (from 0.5 to 10 months of independent walking (IW)). Repeated measures were taken from two of the children at 10 and 17 months of age and then at 18 and 24 months respectively. 3-dimensional video digitisation techniques utilising the DLT algorithm were used to obtain variables of the gait cycle. The position and movement of the arms were identified as potential motor development patterns. Ranges of movement and motion patterns observed in other variables are useful to determine 'normal' walking gait in such young children. The knees and hips were flexed throughout the gait cycle. Inter-limb asymmetries were observed for the knee angle pattern and for the stance and swing phase time. The mean stance phase time and double support time were 4 and 15% (respectively) greater than in adult's gait. The findings of this study are useful as a guide to research, teaching and clinical professions in this area of biomechanics. Copyright 1998 Elsevier Science B.V.

Journal Article↗
PubMed1998

Neuromuscular functioning of athletes and non-athletes in the drop jump.

In many sports vertical jumping is important. This study compared neuromuscular functioning of the lower extremity muscles together with some kinetic and kinematic parameters before and during ground contact in drop jumps from two heights [0.4 m (DJ40) and 0.8 m (DJ80)] in 7 highly trained triple-jumpers and 11 physically active controls. The triple-jumpers jumped 32% higher in DJ40 and 34% higher in DJ80, had shorter braking and total contact times, and greater average and peak vertical ground reaction forces than the controls. In both drop jumps in the electromyogram pre-activity of the vastus lateralis and gastrocnemius muscles started earlier in the jumpers than in the controls. For the control group the increase in dropping height was associated with a decrease in the propulsion force, and resulted in more extended knee and ankle angles at touch down and more flexed angles at the deepest position than for the jumpers. All angular displacements for DJ80 were larger than for DJ40 in the control group. The triple jumpers and control subjects differed with respect to their neuromuscular functioning in the drop jump exercise and they responded in a different way to the increase in dropping height.

Adult↗
PubMed1998

Fibrous wound repair associated with biodegradable poly-L/D-lactide copolymer implants: study of the expression of tenascin and cellular fibronectin.

Extracellular matrix (ECM) proteins are known to play a role in inflammatory and hyperplastic processes. Our aim in the present study was to study the distribution of tenascin (Tn), cellular fibronectins (cFn) and myofibroblasts around biodegradable poly-L/D-lactide (PLA) implants with monoclonal antibodies (MAb). Ethylene-oxide and gamma-irradiation sterilized PLA plate-type implants were inserted into the dorsal subcutaneous tissue of ten adult rabbits. Follow-up times were 4, 12, 16, 36 and 48 wk. Only some inflammatory cells were observed. In electron microscopy, a close coherence between the implant and the stromal tissue was seen. Immunoreactivity for Tn, cFn and alpha-actin was detected as a distinct layer bordering the implant, regardless of the sterilization method for the first 36 wk. From week 36 onwards, Tn immunoreactivity was downregulated while cFn immunoreactivity still persisted. A moderate upregulation for myofibroblasts was seen on the week 48 specimens, when hydrolysation of PLA implant had started. The persistent content of myofibroblasts, Tn and cFn suggests a prolonged wound healing produced by PLA implants. The absence of Tn at the week 48 specimens suggests that cFn, rather than Tn may be needed for alpha-actin-mediated contraction by myofibroblasts.

Journal Article↗
PubMed1997

Biocompatibility of solid poly (ortho ester).

In previous studies poly (ortho ester) (POE) has shown promise as a resorbable device, a hemostatic sealant and as a carrier for drugs in bone surgery. The aim of this study was to evaluate the tissue reactions of solid poly (ortho ester) implanted into both tibiae of 17 rabbits. One half of the rods were sterilized by gamma radiation and the other half by ethylene oxide. The follow-up times were from 1 week to 21 weeks, after which the animals were killed and the bony specimens examined histologically. The connective tissue samples were examined immunohistochemically in order to study the occurrences of two extracellular matrix glycoproteins, tenascin and fibronectin. The results showed that solid poly (ortho ester)s induce a moderate inflammatory reaction for 9 weeks. Tenascin and fibronectin were present in samples from 1 week up to 4 weeks. It was also found that gamma sterilized POE was resorbed at week 7 and ethylene oxide sterilized POE at week 13.

Journal Article↗
PubMed1997

3-D biomechanical analysis of sprint hurdles at different competitive levels.

Four different competition sessions were examined using three-dimensional video techniques to study the hurdle clearance at different levels of performance in male and female athletes. In total, 28 trials were digitized (50 Hz) using the "Kine Analysis" software package. The Direct Linear Transformation algorithm and cross-validated quintic spline were carried out for the data. This study showed that the better female group performed with a greater take-off distance (P = 0.0006), making a lower take-off angle possible. This results in a greater horizontal velocity (P = 0.0002) than the lower level female group. Relative to the horizontal displacement of the CM from take-off to landing, the CM parabola peak occurred at 54 +/- 4% and 55 +/- 6% from take-off for the two male groups and 54 +/- 7% and 51 +/- 3% for the two female groups. There were no statistically significant differences between either the male groups or the female groups or the sexes. This would indicate that the relative peaks are at a similar point in the different parabolic paths. However, in absolute terms the peak occurred at different positions in the different groups. The reason for this is unclear and will need further investigation.

Biomechanical Phenomena↗