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Biomedical subjects

S A Schmidt

Publications and source records attributed to S A Schmidt.

At least 19 recordsLinked to original sources
PubMed2003

[Quantifying the inflammatory activity in Crohn's disease using CE dynamic MRI].

PURPOSE: Evaluation of dynamic contrast enhanced MRI in patients with Crohn's disease to assess local inflammatory activity. MATERIAL AND METHODS: Prospective study of 13 patients with histologically proven Crohn's disease. Axial and coronal slices were acquired by a 1.5 T MR (Magnetom Vision, Siemens, Germany): T1 flash 2 D (TR 72.5 ms, TE 4.1 ms), T2 (TR 2730 ms, TE 138 ms), turbo-flash sequences T1 (TR 94.2 ms, TE 4.1 ms) post contrast media fat saturated (Magnevist, 0.2 ml/kg, flow 4 ml/s). In area of maximal thickening of terminal ileal wall, axial dynamic T1 sequences (TR 11 ms, TE 4.2 ms) were acquired every 1.5 s post contrast media application for a total duration of 1 min. Contrast uptake was subjectively measured by semiquantitative score and computed assisted ROI evaluation. MR parameters were correlated with CDAI (Crohn's disease activity index) and SAI (severe activity index). RESULTS: Contrast uptake in the intestinal wall occurred after 18.5 s (range: 3.0 - 28.0), contrast upslope until plateau phase lasted for 16.1 s (range: 8.0 - 50.0). Maximum contrast enhancement into the bowel wall was 266 % (105 - 450 %) of baseline. After maximum contrast uptake, we observed a plateau phase in all cases for the total duration of measurement. A significant correlation existed for maximum contrast uptake to CDAI (r = 0.591; p = 0.033), for beginning of contrast upslope to the time until plateau phase (r = 0.822; p = 0.001), and for the time until plateau phase to CDAI (r = 0.562; p = 0.046). CDAI was on average 108, median 106; SAI was on average 114, median 115. SAI correlated significantly to CDAI (r = 0.874). Maximum contrast uptake, beginning of contrast upslope, and time until plateau phase were independent to creeping fat, local lymphadenitis, laboratory parameters, temperature, body mass index, heart frequency and systolic blood pressure. CONCLUSION: Dynamic MRI enables to quantify local inflammatory activity of bowel wall in patients with Crohn's disease. Larger studies are necessary to establish this method in clinical routine.

Adult↗
PubMed2001

Structure-function analysis of BfpB, a secretin-like protein encoded by the bundle-forming-pilus operon of enteropathogenic Escherichia coli.

Production of type IV bundle-forming pili by enteropathogenic Escherichia coli (EPEC) requires BfpB, an outer-membrane lipoprotein and member of the secretin protein superfamily. BfpB was found to compose a ring-shaped, high-molecular-weight outer-membrane complex that is stable in 4% sodium dodecyl sulfate at temperatures of < or = 65 degrees C. Chemical cross-linking and immunoprecipitation experiments disclosed that the BfpB multimeric complex interacts with BfpG, and mutational studies showed that BfpG is required for the formation and/or stability of the multimer but not for the outer-membrane localization of BfpB. Formation of the BfpB multimer also does not require BfpA, the repeating subunit of the pilus filament. Functional studies of the BfpB-BfpG complex revealed that its presence confers vancomycin sensitivity, indicating that it may form an incompletely gated channel through the outer membrane. BfpB expression is also associated with accumulation of EPEC proteins in growth medium, suggesting that it may support both pilus biogenesis and protein secretion.

Amino Acid Sequence↗
PubMed1998

Clinical magnetic resonance imaging and arthroscopic findings in knees: a comparative prospective study of meniscus anterior cruciate ligament and cartilage lesions.

We compared the diagnostic and predictive value of magnetic resonance imaging (MRI) and clinical findings with arthroscopy in 61 knees in a prospective study. In meniscal tears, the accuracy and positive predictive value of MRI was found to be nearly twice that of clinical examination. The sensitivity, specificity, and negative predictive value of MRI were comparable to the figures found in other studies. We recommend MRI as a clarifying diagnostic tool when a clinical examination indicates a lesion of the meniscus. In our study, the clinical relevance of MRI in anterior cruciate ligament lesions and especially in cartilage lesions was more doubtful. The combination of clinical and MRI findings would reduce the number of blank arthroscopies to 5%. MRI is a valuable diagnostic tool in planning the type of anesthesia and treatment, and could significantly reduce the need for a second arthroscopy.

Adult↗
PubMed1996

Interacting components of the flagellar motor of Escherichia coli revealed by the two-hybrid system in yeast.

The ability of the flagellar motor of Escherichia coli to switch between clockwise and counterclockwise modes of operation is ultimately responsible for the swimming behavior of the cell. Three motor proteins, FliG, FliM, and FliN, have been implicated in this process. Using the two-hybrid system in Saccharomyces cerevisiae, we demonstrated strong interactions between FliG/FliM,FliM/FliM, and FliM/FliN. A screen for other components that might interact with FliG revealed interactions with FliF (the MS ring protein) and H-NS (a histone-like protein). Regions of proteins important for several of these interactions were identified by mutational analysis. The implications for motor assembly and function are discussed.

Bacterial Proteins↗
PubMed1994

Lysophosphatidic acid inhibits gap-junctional communication and stimulates phosphorylation of connexin-43 in WB cells: possible involvement of the mitogen-activated protein kinase cascade.

Lysophosphatidic acid (LPA) was shown to be a powerful inhibitor of gap-junctional communication between cultured rat liver WB cells, as determined by the transfer of Lucifer Yellow, with 50% inhibition obtained at about 0.3 microM LPA. Inhibition of communication was rapid (5 min) and was maintained for at least 80 min. After incubation for 3 h with LPA, communication competence was partially restored and dye transfer was refractory to further addition of LPA. Communication in LPA-refractory cells retained sensitivity to inhibition by phorbol ester and by epidermal growth factor (EGF). LPA-induced inhibition was associated with phosphorylation of connexin-43 protein, as detected by slower migration of the protein detected on Western blots, which could be eliminated by incubation of samples with alkaline phosphatase. A close correspondence was observed between the time- and dose-dependency of LPA effects on communication and the induction of mitogen-activated protein kinase (MAP kinase). Activation of both the 42 kDa and 44 kDa subspecies were confirmed by mobility shifts on Western blots using an anti-(MAP kinase R1) (erk 1-III) antibody and by fractionation on Mono Q columns. Cells pretreated with phorbol ester for 24 h were insensitive to phorbol ester inhibition of communication or activation of MAP kinase, but retained their sensitivity to LPA. The results indicate that LPA initiates the activation of protein kinase cascades in WB cells that are probably independent of protein kinase C and identifies connexin-43 as one substrate for the activated kinases.

Animals↗
PubMed1994

Prevention of injuries in long-distance runners.

The possibility of reducing the incidence of injuries in long-distance runners was investigated in 41 recreational long-distance runners. They were divided into two matched groups according to age, sex, weight, height, experience, training and incidence of injury during the previous year. The runners in the study group were clinically investigated before the season started, and individual training programmes were drawn up. The other group served as controls. The runners receiving prevention and training programmes improved in training technique and had increased training mileage, race participation and racing mileage. In 1 year a total of 50 injuries were recorded, 29 in the study group and 21 in the controls. The injury incidence per 1000 hours of competition was significantly lower in the study group with a preventive training regimen than in the controls (30.7 versus 62.5).

Adult↗
PubMed1993

Epidermal growth factor inhibits gap junctional communication and stimulates serine-phosphorylation of connexin43 in WB cells by a protein kinase C-independent mechanism.

Epidermal growth factor (EGF) stimulated the phosphorylation of connexin43 (Cx43) in WB cells as evidenced by the formation of multiple immunoreactive Cx43 proteins of higher molecular mass which were abolished by treatment with alkaline phosphatase. Phosphorylation of Cx43 occurred within 10 min of EGF stimulation, was sustained for 1 h, and was associated with almost complete inhibition of gap junctional communication in these cells. EGF-induced phosphorylation and communication inhibition were retained in cells pretreated with phorbol 12-myristate 13-acetate (PMA) to deplete protein kinase C. These results show that the EGF inhibition of communication is tightly linked to protein kinase C-independent phosphorylation of Cx43. Further, Cx43 phosphorylated in the presence of EGF did not react with phosphotyrosine antibodies and in 32Pi incorporation experiments was shown to contain only phosphoserine indicating that the tyrosine kinase activity of the EGF receptor was not directly involved.

Animals↗
PubMed1993

Indomethacin for prevention of heterotopic ossification. A randomized controlled study in 41 hip arthroplasties.

The effect of indomethacin 25 mg 3 times daily during the first 2 postoperative weeks in preventing heterotopic bone formation after cemented total hip arthroplasty was investigated in a randomized, double-blind and placebo-controlled clinical trial on 57 patients. 16 patients were secondarily excluded, leaving 19 patients in the indomethacin group and 22 patients in the placebo group. Evaluated from the 3-month radiographs, 18/19 indomethacin patients developed either no or only the milder Grade 1 ossification. In contrast, 11/22 placebo patients developed Grade 2 or 3 ossifications. Our observations favor indomethacin prophylaxis for 2 weeks in cemented arthroplasty of the hip.

Aged↗
PubMed1991

Total hip arthroplasty. The role of antiinflammatory medications in the prevention of heterotopic ossification.

Postoperative prophylaxis with antiinflammatory medications, primarily indomethacin, is extremely effective in preventing the severest degrees of heterotopic ossification (HO) after a total hip arthroplasty (THA) and the recurrence of excised HO developed after a previous hip surgery. Prophylaxis with indomethacin should be given in 25-mg doses three times daily for at least three weeks, starting on the first postoperative morning. However, a shorter treatment period may be equally effective in preventing the severest degrees of HO, and a postoperative delay of five days before the initiation of prophylaxis does not seem to be followed by the development of severe HO. As evaluated one year after surgery, treatment with antiinflammatory medications in the immediate postoperative weeks did not increase the incidence of implant-bone interface radiolucencies, aseptic loosening, or revisions in cemented or cementless THAs when compared with cases that did not have postoperative treatment. However, although no major complications have been reported regarding the use of antiinflammatory medications in the prevention of HO after THA, orthopedic surgeons prescribing such treatment should be aware of their contraindications as well as early and late side effects. Since several antiinflammatory agents are reported to be effective in preventing HO, future reports dealing with HO after THA should always include information about the postoperative antiinflammatory treatment used.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1990

Badminton injuries.

In a one year period, from 1 January 1986 to 31 December 1986, 4303 patients with sports injuries were treated at Aarhus Amtssygehus and Aarhus Kommunehospital. The mean age was 21.6 years (range 7-72 years) and 2830 were men. Two hundred and seventeen badminton injuries occurred in 208 patients (136 men) with a mean age of 29.6 years (range 7-57 years), constituting 4.1 percent of all sport injuries in Aarhus. Joints and ligaments were injured in 58.5 percent of the patients, most frequently located in the lower limb and significantly more often among patients younger than 30 years of age. Muscle injury occurred in 19.8 percent of the patients. This type of injury was significantly more frequent among patients older than 30 years of age. Most injuries were minor. However, 6.8 percent of the patients were hospitalized and 30.9 percent received additional treatment by a physician. As the risk of injury varies with age, attempts to plan training individually and to institute prophylactic measures should be made.

Adolescent↗
PubMed1990

Combined treatment with indomethacin and low-dose heparin after total hip replacement. A double-blind placebo-controlled clinical trial.

We studied the safety of combining the postoperative use of a non-steroidal anti-inflammatory drug with low-dose heparin. In a double-blind, placebo-controlled clinical trial we reviewed the complications in 235 patients after total hip replacement, all treated with low-dose heparin and either indomethacin or a placebo. The incidence and type of complications in the two groups were nearly equal; indomethacin-treated patients had no increase in complications related to bleeding. Postoperative bleeding into drains was marginally greater in the indomethacin group, although the difference was not statistically significant. We conclude that treatment with indomethacin and low-dose heparin after hip replacement does not significantly increase the bleeding or other complications. We also found that patients receiving indomethacin were mobilised an average of one day before those on placebo.

Clinical Trials as Topic↗
PubMed1989

[Running injuries sustained in a marathon race. Registration of the occurrence and types of injuries in the 1986 Arhus Marathon].

A questionnaire investigation was undertaken in connection with the Arhus Marathon Race in 1986, with the object of registering experience, previous running injuries, amount of training, running injuries, treatment and causes. A total of 831 replies were obtained (90%). Of these, there were 731 men and 100 women with an average age of 34.6 (11-77) years, duration og training 5.5 months, training distance 47.5 km/week and tempo 10.8 km/hour. Among these, 193 injuries were registered in 161 runners (19%). Eighty-nine had to stop sports for more than one week and 26 still had injuries which limited participation in sport after eight weeks. The injuries consisted of blisters (25%) and stress injuries (66%) particularly in the knee (37%) and leg (23%). Runners who sustained injuries were found to be significantly younger than non-injured runners, their training distance was less and training tempo lower. The causes of the injuries were mainly overexertion. The significance for the types of shoes for stress injuries was investigated and a tendency to increased risk of overexertion injuries was demonstrated on employing competition shoes and cheap jogging shoes.

Adult↗
PubMed1989

Factors associated with heterotopic bone formation following total hip replacement.

In order to delineate groups of patients suitable for treatment to prevent heterotopic bone formation (HBF) following total hip replacement, 99 patients were examined to evaluate predisposing factors. One year after surgery, HBF was found in 73% of the patients. A significantly increased frequency of HBF was found among men. There was no correlation between age, severity of osteoarthritis, size of osteophytes, or preoperative hip movement and HBF. Previous ipsilateral hip surgery did not increase the risk of HBF. Although not significant, all patients who developed heterotopic bone after previous ipsi- or contralateral hip surgery showed HBF of the same or even a higher grade after the present replacement.

Adult↗
PubMed1989

Alternatives in the treatment of ipsilateral fractures of the hip and femur.

Eight cases of ipsilateral femoral neck and shaft fractures were reviewed. The diagnosis of the femoral neck fracture was delayed in two cases. Seven of the femoral shaft fractures were comminuted. In six cases, both fractures were treated with rigid internal fixation. A combination of traction and internal fixation was used in two cases. Two cases of avascular necrosis of the femoral head were observed. The fracture reduction was insufficient in both cases and the diagnosis of femoral neck fracture was delayed in one case. A radiograph of the pelvis is mandatory in high-velocity trauma victims. Ipsilateral fractures of the femoral neck and shaft should be stabilized by internal fixation as early as possible. Intramedullary locked nailing seems to be an attractive alternative in the treatment of the comminuted femoral shaft fracture.

Accidental Falls↗
PubMed1989

Early radiolucencies following cemented total hip replacement. Influence of postoperative treatment with indomethacin.

The influence of treatment with indomethacin in the first 6 postoperative weeks on the incidence of early loosening and radiolucencies following cemented total hip replacement were studied in 102 hips. Ninety-nine hips in 99 patients without postoperative antiinflammatory treatment served as control group. One year after surgery, two patients in the indomethacin group and five patients in the control group were suspected of having loosening of one or both prosthetic components. However, no patients had a revision. The lateral acetabular cement-bone interface most frequently showed a radiolucent line. Concerning the incidence of radiolucent lines in any acetabular or femoral cement-bone interface zone, no difference could be shown between the two groups. When evaluated 1 year after surgery, postoperative treatment with indomethacin does not increase the incidence of aseptic loosening or cement-bone interface radiolucencies in cemented total hip replacement.

Bone Cements↗
PubMed1989

Erythrocyte sedimentation rate and heterotopic bone formation after cemented total hip arthroplasty.

The erythrocyte sedimentation rate (ESR) was analyzed in 176 patients treated with cemented total hip arthroplasty (THA) for primary osteoarthritis and correlated with the degree of heterotopic bone formation (HBF) one year after the THA. Ninety patients were treated with indomethacin in the first six postoperative weeks, and 86 patients had no antiinflammatory treatment during that same period. The ESR was measured with the Westergren method and estimated preoperatively and six and 12 weeks after THA. Patients treated with indomethacin had no or only Grade I HBF and no significant elevation in the six- and 12-week ESR. In the placebo group, 44 patients (51%) developed Grade II or Grade III HBF, and six weeks after THA, patients with Grade III HBF had a significant elevated ESR when compared with patients without or with Grade I HBF. Moreover, in patients not treated with indomethacin in the first six postoperative weeks, an ESR above 35 mm/hour 12 weeks after THA was found to be a reliable predictor for the development of severe HBF.

Aged↗