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Biomedical subjects

H Nieminen

Publications and source records attributed to H Nieminen.

At least 19 recordsLinked to original sources
PubMed1995

Load-sharing patterns in the shoulder during isometric flexion tasks.

Patterns of load-sharing between the shoulder muscles during isometric flexion tasks were studied by using both a biomechanical shoulder model and electromyographic (EMG) recordings of ten subjects. The effect of changes in several model parameters and shoulder stiffness constraints on the predicted load-sharing patterns were studied, while the arm position, hand load and precision requirements of the tasks were varied. The results calculated using the model were, when compared to the EMG recordings, plausible predicting a high level of synergistic contraction of muscles of the shoulder muscles during flexion tasks. The trends of the model-predicted muscle forces corresponded well to the EMG recordings. At low hand load levels the increasing of the shoulder stiffness strongly increased the muscle force levels, thus increasing also the level of synergistic contraction of muscles. At higher load levels the increase in the muscle forces was not so high, because the model predicted a high level of simultaneous contraction of muscles already at a low level of shoulder stiffness. Cluster analysis of the EMG recordings revealed large inter-individual differences in the load distribution patterns during flexion tasks. The constraint angle of the glenohumeral joint contact force direction was found to be an important model parameter affecting both the predicted forces and the maximum force production ability of the shoulder.

Adult↗
PubMed1995

Quantification of the static load component in muscle work using nonlinear filtering of surface EMG.

Prolonged static strain on the muscles of the neck-shoulder region is believed to be linked to the development of musculoskeletal problems. To quantify the static strain on the basis of EMG, the level as well as the duration of the muscle load should be analysed on temporal basis. In this paper, some methods for the temporal analysis of EMG recordings are proposed with an aim of quantifying the long-term static strain on the muscle. The use of nonlinear median prefilters for decomposing the EMG activity according both to amplitude level and duration of the activity at different levels is proposed. The prefiltering methods were also evaluated using laboratory studies. The main aim of the studies was to compare the estimation errors between EMG and force for different types of prefilters especially when the static load component was analysed. The average estimation error for sequences having a duration longer than 1 s was found to be 8% of MVC in the case of trapezius muscle and 14% of MVC in the case of biceps brachii muscle. Linear relation was found on the basis of linear least squares curve fitting to give the largest correlation coefficients between EMG and force, when the static load component was analysed.

Adult↗
PubMed1995

Free flap reconstructions of tibial fractures complicated after internal fixation.

The cases of 15 patients are presented where microvascular soft-tissue reconstructions became necessary after internal fixation of tibial fractures. Primarily, seven of the fractures were closed. Eleven fractures had originally been treated by open reduction and internal fixation using plates and screws, and four by intramedullary nailing. All of the patients suffered from postoperative complications leading to exposure of the bone or fixation material. The internal fixation material was removed and radical revision of dead and infected tissue was carried out in all cases. Soft tissue reconstruction was performed using a free microvascular muscle flap (11 latissimus dorsi, three rectus abdominis, and one gracilis). In eight cases the nonunion of the fracture indicated external fixation. The microvascular reconstruction was successful in all 15 patients. In one case the recurrence of deep infection finally indicated a below-knee amputation. In another case, chronic infection with fistulation recurred postoperatively. After a mean follow-up of 26 months the soft tissue coverage was good in all the remaining 13 cases. All the fractures united. Microvascular free muscle flap reconstruction of the leg is regarded as a reliable method for salvaging legs with large soft-tissue defects or defects in the distal leg. If after internal fixation of the tibial fracture the osteosynthesis material or fracture is exposed, reconstruction of the soft-tissue can successfully be performed by free flap transfer. By radical revision, external fixation, bone grafting, and a free flap the healing of the fracture can be achieved.

Adult↗
PubMed1993

Normalization of electromyogram in the neck-shoulder region.

Linear and curvilinear electromyogram (EMG) normalization methods were compared among ten healthy men during a simulated work cycle demanding attention and static holding of the arm ('Solitaire test'). Maximal voluntary contractions (MVC) and gradually increasing contractions up to 70% of MVC were used for normalization in different arm postures. The test contractions studied included inward and outward rotations, abduction, shoulder elevation, and flexion in different arm positions. The shoulder load moment was calculated for the flexion tests using a simple two-dimensional model. The effect of arm posture on the EMG versus shoulder load moment relationship was studied on the following muscles: supraspinatus, infraspinatus, trapezius (three parts), deltoid (two parts) and pectoralis major. All muscles participated in the MVC tests performed, and its was not possible to suggest a single recommended test for each muscle. Differences in normalized EMG median values ranging up to 30% of MVC were found between linear and curvilinear normalization methods. Short-term repeatability of normalization based on a contraction with gradually increasing force was good. Arm posture affected the relationships between shoulder load moment and EMG activity of all muscles studied. Arm posture did not, however, have a significant effect on the estimated amplitude probability distribution functions during the simulated work task. Therefore, at least for the tasks studied, the principle of normalizing in the middle position of the range of movement was deemed acceptable.

Adult↗
PubMed1993

Autofluorescence in cataractous human lens and its relationship to light scatter.

The autofluorescence profile of the lens was measured from 84 eyes of 84 patients with cortical, nuclear, posterior subcapsular, or mixed lens opacities. Measurements were performed with a fluorometer in the blue-green autofluorescence range (495 nm/520 nm). The mean maximum autofluorescence value differed in every cataract group statistically significantly from that of the age matched controls (p < or = 0.0058). The highest autofluorescence values were measured in nuclear and mixed cataract groups (p < 0.0001) with high and narrow autofluorescence profile. In cortical cataracts the curve was low and flattened and the mean maximum autofluorescence value was lower than in the control eyes (p < 0.0001). The maximum autofluorescence was related to lens coloration as well as to visual acuity only in nuclear cataract. The regression between maximum autofluorescence and light scatter was statistically significant only in the nuclear cataract group (p = 0.0004). Since the autofluorescence profiles differed not only in height but also in width between the cataract groups, various width/maximum autofluorescence ratios were measured. In nuclear and mixed cataract groups the ratio 75% width/maximum autofluorescence was statistically significantly lower than in other groups (p < 0.0001). In cortical cataracts the ratio (50% width - 75% width)/maximum autofluorescence was statistically significantly higher than in other groups (p < 0.0001).

Adult↗
PubMed1993

[Proper study of starting point in scientific philosophy--discussion of viewpoints in scholarly nursing study].

In this article starting points and methodological issues of qualitative research will be examined. Questions of phenomenology, analytic hermeneutics and so called newer hemeneutics are handled. Methodological roots of some Finnish PhD. dissertations will be identified. The main purpose of this paper is to discuss and make some clarification to conceptual diversity in studies using qualitative research methods.

Nursing Research↗
PubMed1991

Lens autofluorescence in healthy individuals.

We measured blue-green autofluorescence (AF, 495 nm/520 nm) of the lens in 43 random eyes of 43 healthy volunteers aged 6-86 years, five in each decade, using an instrument designed by one of us (HN). The instrument generates an autofluorescence profile, which consists of anterior and posterior juxtacortical peaks and a central plateau. The height of the anterior peak was taken as a maximum autofluorescence value and the square root of the ratio between the posterior and the anterior peak was used as a lens transmission index. The coefficient of variation for the measurement technique was 3.9% for maximum autofluorescence and 2.9% for lens transmission index. Both the maximum autofluorescence and the transmission index were highly correlated with age. Statistically over 90% of the variation in maximum autofluorescence values and almost 70% of the variation in transmission could be attributed to age.

Adolescent↗
PubMed1990

Screening for glaucoma with a non-mydriatic fundus camera.

183 first-degree relatives of glaucoma patients were photographed by a technician with non-mydriatic fundus camera in order to study the suitability of wide angle black-and-white fundus photographs in screening for glaucoma. The success rate of photography was 92%. The optic disc and retinal nerve fiber layer abnormalities were evaluated from the photographs by an ophthalmologist. 31 subjects (17%) were referred to further ophthalmological examinations. We found 6 (3%) new glaucomas. In addition, in 6 patients (3%) retinal nerve fiber layer defect was the only abnormality, 5 subjects (3%) showed a hemorrhage and 2 eyes had collateral vessels as a sign of asymptomatic venous stasis change at the optic disc. Only 1 of the 6 (17%) patients with glaucoma would have been found with tonometry alone. The results of this study indicate that non-mydriatic retinal camera is a useful tool in screening for glaucoma.

Adult↗
PubMed1985

Retinal nerve fiber layer photography in glaucoma.

Retinal nerve fiber layer (RNFL) photographs can be used for detection of early glaucomatous damage and in the follow-up of patients with established glaucoma. Enlarged black-and-white paper-prints taken with a wide-angle fundus camera as well as stereophotographs of the peripapillary retina have proven quite useful. This article gives a detailed description of both the photographic and the laboratory techniques involved in the process of making good quality RNFL photographs.

Fluorescein Angiography↗
PubMed1984

Diffuse and localized nerve fiber loss in glaucoma.

To estimate the usefulness of photographs of the retinal nerve fiber layer in demonstrating glaucomatous neural tissue changes, we examined such photographs of 51 patients with glaucoma, 52 patients with ocular hypertension, and 29 normal individuals. The photographs were assessed in a masked fashion. A semiquantitative damage score was given in subsectors of the arcuate, papillomacular, and nasal nerve fiber bundle areas, separately for localized and diffuse loss of nerve fibers. The coefficients of variation of the reproducibility of retinal nerve fiber layer assessment were 0.22 for diffuse damage and 0.11 for localized damage. We detected abnormal retinal nerve fiber layer changes in 48 of the patients with glaucoma, in 27 of those with ocular hypertension, and in five of the normal control subjects. Generalized reduction of nerve fibers with or without localized defects was more common in patients with glaucoma than in those with ocular hypertension whose abnormal findings were primarily localized defects.

Glaucoma↗
PubMed1982

Optic disc drusen--a photographic study. I. Autofluorescence pictures and fluorescein angiography.

As part of an examination of 180 patients with optic disc drusen, autofluorescence pictures had been taken in 116 patients and fluorescein angiograms in 67 patients. The superficial optic disc drusen often show a very bright nodular autofluorescence, but more important is the diffuse, not so intensive autofluorescence that the buried drusen may show. Thus, a diagnosis of hidden drusen can also be made if autofluorescence can be demonstrated. Fluorescein angiography may also reveal the buried drusen that do not show autofluorescence, and it may be of help in the differential diagnosis of pseudopapilloedema from true papilloedema. It may also indicate anomalous vascular patterns that may be associated with optic disc drusen.

Adolescent↗
PubMed1982

Optic disc drusen--a photographic study. II. Retinal nerve fibre layer photography.

As part of an examination of 180 patients with optic disc drusen fundus photographs of 159 cases were evaluated. Twenty-one patients had no fundus photographs, and 12 cases had only autofluorescence pictures, positive colour transparencies or fluorescein angiograms. Peripapillary retinal nerve fibre layer (RNFL) was examined in 147 patients from black-and-white stereo-photographs of the optic disc (116) or from special RNFL pictures (4) or from both (27). Fifty-three of 147 patients had been photographed two or more times during the years from 1967 to 1981. The regional grading of the RNFL was performed separately from 6 sectors around the disc from 386 series of photographs, and the findings were later compared with the patients' visual fields. The eyes with buried drusen usually showed normal RNFL and normal fields, but the visible drusen were often associated with thinning or slits or atrophy of the peripapillary nerve fibre bundles and with visual field defects.

Adolescent↗
PubMed1982

Retinal nerve fibre layer photography with a wide angle fundus camera.

Retinal nerve fibre layer (RNFL) photographs taken with a wide-angle fundus camera (Canon CF-60Z) and its built-in blue interference filter (SE-40) of 495 nm wavelength were compared with pictures taken with the same camera and a red-free absorption filter (Wratten No. 58) as well as with photographs taken with a 30 degrees fundus camera and Wratten No. 58 filter. Comparison showed that the best visualisation of the RNFL and its defects was achieved with the 60 degrees picture angle of the Canon camera and SE-40 filter. With a smaller picture angle (30 degrees) and a filter of longer wavelength quality of reproduction deteriorated.

Glaucoma↗
PubMed1982

Changes in optic disc drusen. Demonstration by stereophotographs and electronic subtraction.

As a part of more comprehensive examination of 180 patients with optic disc drusen, fundus photographs of 159 cases were evaluated. There were 70 patients whose optic discs were photographed two or more times during the years from 1967 to 1981. Four patients were selected to present the changes which can take place in optic discs with drusen and the alterations are demonstrated by autofluorescence pictures, stereophotographs, and electronic subtraction method.

Adolescent↗
PubMed1980

Electronic subtraction method for ophthalmic photography.

A commercial electronic subtraction unit originally intended for the study of roentgenograms was used to produce subtraction pictures of fundus fluorescein angiographies. No modifications were needed to make good quality subtraction pictures. The method is fast and inexpensive in contrast to previously described photographic methods. Certain limitations of the present equipment are discussed as well as some possibilities for further development of the apparatus. The method is especially suitable for studies on dynamic processes in the eye and it should prove valuable in the long-term follow-up of chronic diseases such as glaucoma and diabetic retinopathy.

Adult↗
PubMed1980

Demonstration of glaucomatous optic disc changes by electronic subtraction.

We describe a new method, the electronic subtraction, for objective two-dimensional detection, demonstration and recording of glaucomatous optic disc changes. Siemens subtraction unit M 707 A, based on a double videochain and originally developed for the study of roentgenograms, was used. The results show that this technique is useful in demonstrating the progressive damage of neural tissue of the disc and associated alterations in the course of the vessels. Further development of the electronic subtraction method for glaucomatous optic disc evaluation is discussed.

Aged↗
PubMed1978

Fuchs's heterochromic cyclitis: a simultaneous bilateral fluorescein angiographic study of the iris.

Twelve patients with Fuchs's heterochromic cyclitis (FHC) were studied with simultaneous bilateral flucrescein angiography of the iris. The flow began a little earlier in the contralateral iris in 4 cases, and simultaneously in both irides in 8 cases. The radial iris vessels were narrow in 7 eyes with FHC and in the contralateral eyes of 2 elderly patients and 1 patient with pigmentary retinal dystrophy and FHC. An ischaemic sector of the iris was seen in 6 eyes with FHC, neovascularisation of the iris in 8 eyes, and fluorescein leakage of the iris vessels was seen in all eyes with FHC. No neovascularisation of the iris occurred in the contralateral eyes, and only minimal fluorescein leakage was seen at the pupillary border of 5 contralateral eyes. The results support the hypothesis of vascular pathomechanism in FHC.

Adolescent↗