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Biomedical subjects

R Knebel

Publications and source records attributed to R Knebel.

12 recordsLinked to original sources
PubMed2001

Massive lower gastrointestinal hemorrhage caused by CMV disease as a presentation of HIV in an infant.

The gastrointestinal (GI) manifestations of acquired immunodeficiency syndrome in children are related to opportunistic infections like cytomegalovirus (CMV). CMV disease of the GI tract is a major cause of morbidity and mortality in immunocompromised patients: it typically produces mucosal ulcerations that can result in pain, bleeding, diarrhea, and GI perforation, often around the cecum. Preoperative diagnosis may be difficult, plain films and barium enema are often non-specific, and endoscopic evaluation is impossible when there is massive bleeding. The patient usually needs surgery to establish the correct diagnosis and initiate appropriate treatment. The use of gancyclovir for CMV disease in the postoperative period has improved the prognosis.

Colonic Diseases↗
PubMed2001

Extramedullary fixation of 569 unstable intertrochanteric fractures: a randomized multicenter trial of the Medoff sliding plate versus three other screw-plate systems.

We compared the efficacy of the Medoff sliding plate (MSP) with 3 other screw-plate systems for fixation of unstable intertrochanteric fractures in a randomized multicenter trial of 569 elderly patients. The MSP has biaxial dynamic capacity along both the neck and the shaft of the femur unlike the other systems, which lack dynamic capacity along the shaft. 268 fractures were operated on with the MSP, and 301 with the dynamic hip screw (DHS), with or without a trochanteric stabilizing plate (DHS/TSP) or with the dynamic condylar screw (DCS). The MSP had recently been shown to the surgeons. The patients in the groups were similar as regards age, domestic situation, preinjury walking ability and type of fracture. We followed the patients clinically and radiographically for at least 1 year. There was no significant difference in walking ability at follow-up or rate of return to home. Fixation failure occurred in 18/268 fractures operated on with the MSP, in 8/238 with the DHS, in 3/49 with the DHS/TSP and in 1/14 with the DCS. The difference in the rate of fixation failure was not statistically significant when the MSP group was compared to the 3 other groups. In 14 of the 18 fixation failures in the MSP group, the biaxial dynamic capacity of the MSP had not been used due to technical errors by surgeons, unfamiliar with the new method. No selection bias was found regarding fracture types in the 2 subgroups of patients with correct or inadequate biaxial dynamization. Extramedullary fixation of unstable intertrochanteric fractures with these implants showed a low failure rate. When using the MSP, biaxial dynamization must be correctly performed.

Adult↗
PubMed2001

Blood conservation with tranexamic acid in total hip arthroplasty: a randomized, double-blind study in 40 primary operations.

We performed a randomized, double-blind study on the effect of tranexamic acid on blood loss and blood transfusions in 40 primary total hip arthroplasties. Tranexamic acid, 10 mg/kg body weight, or placebo, was given intravenously just before the operation. Blood loss during the operation and postoperatively into the drains was recorded, as also were blood hemoglobin concentrations. Ultrasound examination 1 week postoperatively was done to estimate the blood loss due to remaining hematomas. Total (operation + drain) blood loss was 0.76 (95 CI 0.63-0.89) L in the tranexamic acid group as compared to 1.0 (CI 0.81-1.2) L in the placebo group (p = 0.03). The number of blood transfusions during the day of operation was 2 vs. 10 (p = 0.07) and the total number during the hospital stay was 5 vs. 13 (p = 0.2). 1 patient in each group had a pulmonary embolism.

Aged↗
PubMed2001

A sensitive immunochemical assay for measuring the concentration of the activated protein C-protein C inhibitor complex in plasma: use of a catcher antibody specific for the complexed/cleaved form of the inhibitor.

Activated protein C (APC) is a serine proteinase that regulates blood coagulation. In plasma it is inhibited mainly by the protein C inhibitor (PCI). The plasma concentrations of APC-PCI complex is increased in hypercoagulative states such as deep venous thrombosis. Formation of the APC-PCI complex induces a drastic conformational change in PCI that exposes new epitopes (neoepitopes) on the molecule. We have devised a simple immunofluorometric sandwich assay for measurements of the concentrations of APC-PCI complex, employing as the catcher, a monoclonal antibody that has a high affinity (K(D) = 4 x 10(-11) M) for a complexation-specific neoepitope that is expressed on PCI. A monoclonal antibody against protein C is employed as the tracer. The method gives a linear dose-response curve (0.06-50 microg/l), has a low detection limit (0.06 microg/l) and no crossreactivity with native PCI at physiologic plasma concentrations. We have now determined the concentration of the APC-PCI complex in healthy individuals.

Calibration↗
PubMed1994

The effect of subcutaneous injection of unfractionated and low molecular weight heparin on thrombin generation in platelet rich plasma--a study in human volunteers.

We administered a dose of unfractionated heparin (UFH) and two doses of a low molecular weight heparin (LMWH) to healthy volunteers by SC injection. The doses given were: a) UFH, 5000 IU, which represents 8.7 mg of > 5,400 MW active heparin (ACLM) and no < 5,400 active heparin (BCLM), b) enoxaparin 40 mg (3.4 mg ACLM, 2.2 mg BCLM) and c) enoxaparin 1 mg/kg body weight (on the mean 75 mg, containing 6.4 mg ACLM and 4.1 mg BCLM). We determined the effect on thrombin generation in platelet rich plasma (PRP) between 1 and 8 h after injection. UFH administration caused only a 5-8% inhibition of the thrombin potential (i.e. the area under the thrombin generation curve). Significantly higher inhibition of the thrombin potential was seen after administration of both doses of enoxaparin. To wit 9-26% at the low dose and 29-46% at the high dose. UFH injection caused a prolongation of the lag-time before the thrombin burst. Only with the high dose of enoxaparin the lag-times were significantly more prolonged with enoxaparin than with UFH. Excess amounts of platelet factor 4 (PF4) were able to neutralize completely the anti-thrombin activity in normal plasma spiked with enoxaparin as well as in plasma samples obtained after SC enoxaparin injection. With a large excess of PF4 the anti-factor Xa activity could be inhibited to a maximum of 50%. This indicates that ACLM (above critical length material, MW > 5400) is neutralized completely by PF4 whereas BCLM (below critical length material, MW < 5400) is not.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Late-presenting congenital diaphragmatic hernia: a possible cause of sudden respiratory distress in children]

OBJECTIVE: To emphasize that congenital defects of the diaphragm should be considered in the differential diagnosis of sudden onset of respiratory distress in children. MATHOD: Two illustrative cases of children (aged 2 years) with late presenting congenital diaphragmatic hernia who developed sudden respiratory distress and were managed at the University Hospital of Santa Maria are reported. The medical literature was reviewed to identify cases reports and other articles related to late presenting congenital diaphragmatic hernia. A computerized search was performed using the MEDLINE data base to identify papers published within the last 25 years. RESULTS: In both cases the initial clinical examination and plain chest X-rays were misinterpreted as another pleuropulmonary disease like pneumothorax/pneumatoceles. One of the children underwent to emergency chest tube placement without clinical improvement. The absence of respiratory symptoms that could justify this kind of pathology motivated a more careful investigation, involving fiberoptical endoscopy and intestinal seriography. This subsequent investigation revealed that the cause was late-presenting congenital diaphragmatic hernia. CONCLUSION: Although many congenital diaphragmatic hernias that present late have a history of chronic respiratory symptoms, some of them present with acute symptoms. A higher degree of attention is required to avoid confusion with other intrathoracic conditions, such as pneumatoceles and pneumothorax, if an incorrect diagnosis is to be avoided. Misinterpretation of the radiographs is likely if the possibility of a congenital diaphragmatic hernia is not considered, and may result in increased morbidity. Gastric atony may occur in the early postoperative period.

Journal Article↗