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Biomedical subjects

K Thorén

Publications and source records attributed to K Thorén.

At least 19 recordsLinked to original sources
PubMed2001

Identification of proteins from Escherichia coli using two-dimensional semi-preparative electrophoresis and mass spectrometry.

Escherichia coli is a gram-negative bacterium that causes sepsis and infections of the nervous system, and the digestive and urinary tracts. The availability of the complete nucleotide sequence encoding the E. coli K-12 genome has made this organism an excellent model for proteomic studies. Semi-preparative two-dimensional electrophoresis, including liquid phase isoelectric focusing (IEF), one-dimensional sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and gel elution, have for the first time been used in combination with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS), electrospray tandem mass spectrometry and database searching for rapid separation of proteins from a uropathogenic strain of E. coli. The identity of 30 proteins, including the membrane protein nmpC, was obtained using this approach.

Bacterial Proteins↗
PubMed2000

Ocular manifestations of incontinentia pigmenti.

PURPOSE: The study aimed to evaluate the ocular manifestations in patients with incontinentia pigmenti (IP). METHODS: Thirty patients from different parts of Sweden participated. Orthoptic and ocular examinations were performed as well as evaluation of refraction and visual acuity. RESULTS: Ocular manifestations, probably associated with IP, were found in 77% (23/30) of the patients. Thirteen had serious or vision-threatening eye manifestations in one eye, of whom 7 were totally blind in that eye from retinal detachments. Ten patients had minor retinal and/or corneal changes. CONCLUSION: Ocular lesions in patients with IP may be serious and lead to blindness because of retinal disease. Ophthalmological follow-up is essential in the neonatal period and such a programme is recommended.

Adolescent↗
PubMed2000

Suitability of the lang II random dot stereotest for detecting manifest strabismus in 3-year-old children at child health centres in Sweden.

The aim of the study is to examine the suitability of the Lang II Random Dot Stereotest for use by district nurses in primary healthcare centres. The Lang Stereotest is an inexpensive method. It is easy to apply, but the child's co-operation is required. Approximately 100 district nurses were given detailed information and instruction by an orthoptist prior to a randomized population-based community trial initiated in 1993. In the county of Uppsala in Sweden, all 4293 children born in 1990 were randomized to one of the following four study groups: intervention, control, reliability or validity. All children were followed from birth to 6.5 y of age with respect to the occurrence of strabismus. The kappa statistic for test-retest reliability among district nurses was 0.65 (95% CI, 0.51-0.80). A validation of the outcomes of district nurses' against orthoptists' examinations using the Lang Stereotest showed a sensitivity of 0.33 (95% CI, 0.09-0.65) and a specificity of 0.85 (0.80-0.89). Of 113 cases of strabismus, 53% were detected within the first 3 y of life. Examination of 1132 3-y-old children using the Lang Stereotest enabled the district nurses to detect 11 new cases of strabismus. Only one of these cases was referred to an orthoptist as a direct consequence of the screening. The Lang Stereotest showed low reliability and low validity in this community trial. It is concluded that the Lang II Random Dot Stereotest is not suitable for the screening of manifest strabismus in unselected populations of 3-y-old children in Sweden, where a large proportion of cases of strabismus is detected during the first 3 y of life.

Age Factors↗
PubMed1995

Increased bone ingrowth distance into lipid-extracted bank bone at 6 weeks. A titanium chamber study in allogeneic and syngeneic rats.

In previous rabbit chamber experiments, lipid extraction has been shown to increase bank bone incorporation, as measured by scintimetric activity at 3 weeks. In the present study, the new bone ingrowth distance was measured by histomorphometry at 6 weeks using a titanium chamber model in rats. By insertion into bilateral bone conduction chambers, frozen grafts were compared with grafts that had been processed by lipid extraction. To evaluate the effects of lipid extraction further, the group of 26 rats was divided into three subgroups according to MHC haplotype, namely a heterogeneous group (outbred Sprague-Dawley rats), a mismatched group, and a syngeneic group. In the total material, defatted grafts showed a 58% greater new bone ingrowth distance and a 31% higher scintimetric activity over controls. The effect of defatting was not shown to be due to immunologic factors. In general, rats with a lower capacity to incorporate bone grafts showed a larger positive effect of defatting.

Analysis of Variance↗
PubMed1995

Lipid extracted bank bone. Bone conductive and mechanical properties.

Lipid extraction by chloroform methanol previously has been found to increase the incorporation of frozen bone allografts. This effect may be because of a decreased immunologic response. In the present study, the ingrowth capacity into a grafted bone defect was investigated by using the bone harvest chamber model in rabbits. In a series of experiments, defatted and frozen allografts were compared at 1, 2, and 3 weeks; defatted allografts and defatted autografts were compared at 3 weeks; and frozen or defatted allografts and nongrafted defects were compared at 3 weeks. Evaluation was performed through histology, histomorphometry, and 99mTc-MDP scintimetry. The incorporation was better with defatted grafts: by histology at 1 week, mesenchymal tissue filled the intertrabecular space in defatted specimens and new bone formation started to occur. In contrast, frozen specimens showed a central soft tissue necrosis surrounded by inflammatory cells. Histomorphometry showed more new bone and more graft resorption in defatted allografts. At 2 and 3 weeks, there was no significant difference in new bone area, but at 3 weeks the scintimetric activity was higher in defatted allografts, probably caused by an increased remodeling rate. Since defatting did not cause increased scintimetric activity in previous autograft studies, these findings could indicate that there is a detrimental immunologic influence on frozen allografts. There were no differences between defatted autografts and allografts. In a second experiment, the biomechanical properties of defatted bone were investigated with a compression test on defatted and frozen bone cylinders taken from the calf femoral neck. No difference in biomechanical properties was found. It was concluded that lipid extraction produced a graft that was better incorporated than a nondefatted graft, with no loss of mechanical function.

Animals↗
PubMed1995

Ethylene oxide sterilization impairs allograft incorporation in a conduction chamber.

Bone allograft processing often includes treatment with hydrogen peroxide for protein denaturation and sterilization by irradiation or ethylene oxide. The effect of these treatments on the osteoconductive properties of the graft was tested by measuring the new bone ingrowth distance into processed cancellous bone grafts in rats. Forty graft pairs were taken from rat tibias, and were frozen, defatted in chloroform-methanol, and dried. In addition, 1 graft of each pair was treated with 2% hydrogen peroxide, 2.5 Mrad irradiation, or by a Steri-Vac hospital ethylene oxide chamber. The grafts were placed in bone conduction chambers and implanted in rat tibias. Six weeks after implantation, the chambers were emptied, and the new bone ingrowth distance and scintimetric activity were measured. Ethylene oxide treatment impaired the new bone ingrowth distance by 68% and reduced the scintimetric activity by 51%. Another 10 defatted grafts, which had been ethylene oxide treated together with the grafts for implantation, were analyzed for levels of residual ethylene oxide, ethylene chlorohydrin, and ethylene glycol. All the measured residuals were below the detection limit of 20 parts per million, which was below the level recommended by the United States Food and Drug Administration. Ethylene oxide sterilization was more deleterious for bone allografts than expected.

Animals↗
PubMed1993

Lipid extraction decreases the specific immunologic response to bone allografts in rabbits.

The immunologic response against frozen bank bone is generally considered to have no clinical importance. In a previous study, the bone formation rate in frozen allografts was measured at standardized conditions in the Bone Harvest Chamber. By defatting frozen allografts, the bone formation rate increased. In the present study, the effect of defatting was further investigated, as the specific immunologic influence was excluded by using autografts. Pairs of grafts were frozen and one graft in each pair was defatted with chloroform/methanol. With these autografts there was no difference in bone formation rate between defatted and non-defatted implants, measured with 99mTc-MDP. Combined with the previous experiments, the results indicate that the increased bone formation rate in defatted allografts is caused by the removal of specific cell surface antigens. Thus, the immunologic reaction to bank bone can be diminished by defatting.

Animals↗
PubMed1993

Effects of basic fibroblast growth factor on bone allografts. A study using bone harvest chambers in rabbits.

Bone grafts which have been supplemented with a growth factor might incorporate faster. In this study we investigated the effect of basic fibroblast growth factor (bFGF). Titanium bone harvest chambers were implanted bilaterally in the proximal tibia of rabbits. These chambers were pierced by a transverse bone ingrowth canal from which 1 x 1 x 5 mm cancellous bone rods were repeatedly harvested at 5 weeks intervals. The bone rods to be used as allografts were frozen as ordinary bank bone, and then lipid-extracted. This treatment yields a graft which elicits less of an immunologic response than allografts which are only frozen and thawed. Before implantation, the bone rods were soaked in a cellulose gel containing 0.5 microgram/ml recombinant human bFGF or gel without bFGF as a control. The grafts were then implanted pair wise (bFGF and control) in the chambers of recipient rabbits. These chambers were harvested after 2 weeks. Evaluation was made by Tc-MDP scintimetry, histomorphometry and histology. Upon histology new living tissue had filled the grafted chambers entirely and partly replaced the graft. bFGF induced an increased amount of pre-osteoblastic tissue in the bFGF-treated grafts (p < 0.02), but there was no difference in the amount of osteoid or new bone.

Animals↗
PubMed1991

Mortality pattern among pulp and paper mill workers in Sweden: a case-referent study.

The mortality pattern among Swedish pulp and paper mill workers was evaluated in a case-referent study encompassing 4,070 men decreased during the period 1950-1987. The subjects were identified from the register of deaths and burials in six parishes. A significantly increased mortality was seen for diabetes mellitus and for secondary tumors of the lung and liver among the pulp and paper mill workers. Indications of excess risks were also found for obstructive lung disorders, pulmonary emboli, accidents, and pneumonia, as well as for malignant lymphomas, leukemias, and cancer of the pancreas and stomach. In the only parish where a sulfite process was exclusively used, cancer of the digestive tract and especially of the rectum was found to be in excess. Except for this parish, the sulfate process predominated in the plants included. The mortality pattern found in this study is in reasonable agreement with findings in various studies from this type of industry.

Adult↗
PubMed1990

Lipid extraction enhances bank bone incorporation. An experiment in rabbits.

We implanted frozen allogeneic cancellous bone in rabbit skeletal defects and compared the bone-forming response with that from similar implants that had also been extracted with chloroform/methanol. The donor bone was harvested from a previously implanted titanium chamber that is spontaneously filled with reproducible amounts of cancellous bone. It was processed as frozen bank bone, then transferred to an identical, but empty, chamber in another rabbit. Extraction of lipids before implantation increased the ingrowth of new bone into the transferred bone, as measured by 45Ca and 99mTc-MDP activity. A simple treatment with fat solvents may reduce some of the drawbacks of ordinary bank bone.

Animals↗
PubMed1989

Lung function and respiratory symptoms among workers in a soft paper mill.

The aim of the present cross-sectional study was to investigate whether long-term exposure to soft paper dust causes impairment of lung function. Exposed workers (n = 287) and referents (n = 79) were investigated, using spirometry and questionnaires. Personal samplings of total dust showed that the actual mean concentrations did not exceed 3 mg/m3. The exposed subjects were divided into three categories according to historical and present exposure to paper dust; low exposure, moderate exposure and high exposure. The study did not show any lung function impairment due to exposure to paper dust. However, the exposed subjects had a significantly increased prevalence of symptoms from both the upper and lower airways as well as an increased prevalence of reported asthma. On the basis of our study, we conclude that lung function impairment does not occur among workers exposed to mean levels of soft paper dust below 5 mg/m3.

Cross-Sectional Studies↗
PubMed1989

Mortality from asthma and chronic obstructive pulmonary disease among workers in a soft paper mill: a case-referent study.

In a case-referent study encompassing 33 cases and 228 referents the potential risk for asthma and chronic obstructive pulmonary disease and respiratory cancer among workers in a soft paper mill was evaluated. The cases were selected from registers of deaths and burials in the parishes around the paper mill. Information on exposure was obtained from the personnel register of the mill but because of shortage of information the cases could only be classified as "exposed" or "non-exposed." At some places in the mill the concentrations of paper dust had previously been high, 10-30 mg/m3. Employment at the paper mill was found to be associated with an increased risk of bronchial asthma and chronic obstructive pulmonary disease (odds ratio = 3.8, p less than 0.05).

Adult↗
PubMed1988

Lung function in workers exposed to soft paper dust.

In a cross-sectional study, 13 nonsmoking men with heavy exposure to paper dust were compared with 14 unexposed men, mainly office workers, employed at the same paper mill. They were studied using questionnaires, physical examinations, pulmonary function studies, and chest radiographs. Among those exposed there was an increased lung elastic recoil pressure (Pel) compared with controls which was significant (p less than 0.05) at the maximal level of total lung capacity (100% TLC). Furthermore, among the exposed workers there was also a significantly (p less than 0.05) decreased residual volume (RV). Two of the exposed men underwent lung biopsies, one of which showed fibrotic alveolar walls. Among the exposed there was also a significant (p less than 0.05) predominance of symptoms from the lower respiratory tract. We suggest that the observed pulmonary function impairment taken together with the histological examination of the lung biopsies are signs of a nonspecific reaction to high levels of paper dust.

Adult↗
PubMed1986

Impaired production of alpha and gamma interferon in asymptomatic homosexual males.

In vitro production of alpha interferon and gamma interferon was examined in cell cultures from 90 asymptomatic homosexual males and 19 healthy heterosexual male controls. The production of alpha and gamma interferon was significantly suppressed in homosexuals as compared to that in heterosexual controls (p less than 0.005 and p less than 0.001, respectively). Forty-one of the homosexuals produced less gamma interferon than any of the heterosexual controls. Antibodies against the human immune system virus (HIV) were found in eight homosexuals, who produced significantly less alpha and gamma interferon than did the HIV-seronegative homosexuals (p less than 0.02). Neither carriage of Entamoeba histolytica or Giardia lamblia nor serological evidence of infection with cytomegalovirus, Epstein-Barr virus or hepatitis B virus was associated with a significantly lower production of interferon than that found in homosexual males seronegative for these infections. No correlation was found between number of partners or practice of passive anal intercourse and production of interferons in homosexual men. It is concluded that the significantly lower production of both alpha and gamma interferon in asymptomatic homosexual males may play an important role in susceptibility to viruses, including HIV.

Adult↗
PubMed1986

Symptomatic treatment of acute infectious diarrhoea: loperamide versus placebo in a double-blind trial.

One hundred and twelve patients with acute infectious diarrhoea were entered in a double-blind randomised study in order to compare loperamide with a placebo. Of 82 evaluable patients, 38 received loperamide and 44 placebo for a maximum of 5 days. There were no significant differences in the number of loose stools during the first day of treatment, in the total number of tablets taken or in the total duration of the period of diarrhoea between the two treatment groups. The loperamide-treated patients had significantly fewer loose stools during the observation period of 5 days than did the placebo treated patients, median five vs. seven, a difference of little clinical importance. Excretion of bacterial pathogens was followed weekly in 13 of the loperamide treated patients (median 35.5 days) and in 18 of the placebo treated patients (median 22.5 days). This difference in the duration of excretion was not significant.

Acute Disease↗
PubMed1984

Intestinal parasitic infection and other sexually transmitted diseases in asymptomatic homosexual men.

76/133 (57%) asymptomatic homosexual men harboured intestinal parasites. Of these, 40 had Entamoeba histolytica or Giardia lamblia, or both. In a control group of heterosexual men, no pathogenic protozoa were found. Stool specimen cultures for Salmonella, Shigella, and Campylobacter were negative. 7% of the homosexual men were infected with Neisseria gonorrhoeae in the pharynx or rectum, or both, and 5% with Chlamydia trachomatis in the urethra or rectum. Serological evidence of syphilis was detected in 18 men (13.5%) of whom 2 were untreated. Serological markers of hepatitis A were found in 20% and of hepatitis B in 48%. The prevalence of antibodies to cytomegalovirus was higher in homosexual than in heterosexual men (88% versus 59%).

Adolescent↗