Biomedical subjects
Publications and source records attributed to D Marton.
The interactions of tributyllead with lysosomes from rat liver have been studied. It results that the organometal compound induces a fast alkalinization in energized lysosomes. The interpretation is that the compound is a potent proton carrier. This function could explain the toxicity, in particular at neurological level of the compound.
The composition of a commercial dehydroascorbic acid (DA) solution at pH 2 was investigated by liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) to establish the nature of its different forms and its decomposition products. In freshly prepared solutions, dimeric forms of DA and the hydrated bicyclic hemiketal of DA are the species mainly present in solution. In the presence of light, the initial dimeric species disappears over time to give other dehydrated dimers some of which decompose to the monomer. The comparison of these data with similar data obtained for ascorbic acid (AA) solutions under the same experimental conditions revealed that, in the presence of light, the aging of such AA solutions gives rise to only the hemiketal form of DA, and that no dimeric species of DA were formed. The presence of the hemiketal form of DA was not revealed by analysis of the same AA solutions using the conventional LC/UV technique. The natural form of DA from the oxidation of AA is the hydrated bicyclic form.
The static headspace gas chromatographic technique can be conveniently employed to check the presence and amount of the odorous side-products, 2-R-1,3-dioxanes (R = H, CH3, C2H5, i-C3H7, n-C3H7), directly from the wastewaters flowing from the reactors during the synthesis of polyester resins. By the optimisation of a simple and direct analytical method, the amounts of these compounds may be continuously monitored and controlled. This method is characterized by good repeatability (3-4%) and does not seem to suffer from matrix effects. The detection limits for the determination of the five dioxanes fall in the range 400-700 micrograms dm-3 (alpha = beta = 0.05).
Interactions of two trialkyltin compounds with the lysosomes from a rat liver have been studied. It is shown that these compounds induce a fast alkalinisation in the matrix of energised lysosomes. The fast alkalinisation rate is similar to the one obtained with uncouplers of the oxidative phosphorylation. An identical effect has been obtained with lysosomes energised in a chloride-free medium. This supports the hypothesis that trialkyltin compounds behave not only as Cl-/OH- exchangers, but also as proton carriers in biological membranes. This result could explain the toxicity and in particular the neurotoxicity of trialkyltin compounds.
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The interactions of two trialkyllead (TAL) compounds, (trimethyl)Pb-Cl and (tributyl)Pb-Cl, with mitochodria from rat liver have been studied. A stimulation of the respiratory rate induced by the trialkyllead compounds added at low doses was observed which was not dependent on the presence of chloride in the medium. In contrast with the major current view, we propose that trialkyllead compounds behave as uncouplers of the oxidative phosphorylation and not (or not only) as Cl-/OH- exchangers. In fact the present results suggest that the TAL compounds enter the mitochondria as (alkyl)3Pb+ cations and are extruded as electroneutral (alkyl)3 Pb-OH compounds, the overall result being the transport of a proton through the membrane as in the case of classical uncouplers. The uncoupling effect could explain the toxicity of the compounds as a result of the decrease in the energy level of the cell. Furthermore, such a mechanism, in which the uptake of TAL compounds is supposed to be driven by a negative potential, could explain their preferential toxicity for neuronal cells, which maintain a higher negative-inside potential than most other cell types.
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Between 1977 and 1992, we performed ninety-two synoviortheses (destruction of synovial tissue by intra-articular injection of a radioactive agent) on forty-eight patients who had a severe congenital disorder of hemostasis and chronic hemophilic synovitis that was resistant to conventional treatment. Colloidal 32P chromic phosphate was injected intra-articularly: 1.0 millicurie for knees and 0.5 millicurie for other joints. The duration of follow-up ranged from one to fifteen years. The frequency and importance of bleeding decreased in most of the patients. The range of motion of half of the joints remained stable or improved and that of the other half continued to decrease. Radiographic scores worsened progressively despite the decreased frequency of hemarthrosis. In most patients, the extra-articular leakage of the radioactive agent was slight. Chromosome breakages were observed almost exclusively in patients who were seropositive for human immunodeficiency virus and in whom the CD4-lymphocyte count was decreased from normal. The patients' level of satisfaction with the results was high.
Blackfan-Diamond anemia, a chronic, pure red cell aplasia, is rare. Malignant fibrous histiocytoma is also uncommon; it can arise in pre-existing bone lesions. The authors describe a 23-year-old man with Blackfan-Diamond anemia complicated by hemochromatosis in whom malignant fibrous histiocytoma developed in the distal femur.
OBJECTIVE: To determine if computed tomography of the patellofemoral joint has any advantage over standard radiologic techniques in the evaluation of recurrent patellar subluxation. DESIGN: A case series. SETTING: A tertiary children's hospital out-patient clinic. PARTICIPANTS: Forty consecutive adolescents with a clinical diagnosis of recurrent patellar subluxation (study group) and 14 volunteers with normal knees (control group). INTERVENTIONS: A standardized radiologic protocol, including axial views of the patella at 30 degrees of knee flexion, with and without external torsion of the tibia, and computed tomography (CT) of the patella at 15 degrees of knee flexion. MAIN OUTCOME MEASURES: The lateral patellofemoral angle on the axial views and on the CT scan and patellar centralization on the CT scan. RESULTS: In the control group, no radiologic evidence of recurrent patellar subluxation was found. In the study group, an abnormal lateral patellofemoral angle was found in 25% of axial views; this rate increased to 42% with external rotation and 86% on the CT scan. Patellar centralization was abnormal in 79% of cases. CONCLUSIONS: CT of the patellofemoral joint is more sensitive than standard radiographs for the diagnosis of recurrent patellar subluxation. The use of CT is recommended when standard radiographs appear normal.
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We reviewed the clinical, radiographic, and computed tomographic (CT) findings in eight children with a histologically proven diagnosis of epiphyseal or apophyseal osteomyelitis. In all cases the femur was involved: in five the osteomyelitis was localized in the femoral condyle, in two it was in the greater trochanter, and in one it was in the femoral head epiphysis. In four of the six cases of epiphyseal involvement there was associated joint effusion or septic arthritis. CT examination may demonstrate a serpentine tract, a sequestrum, cortical destruction or adjacent soft tissue swelling and can differentiate osteomyelitis from other epiphyseal lucent lesions, particularly chondroblastoma and osteoid osteoma. CT yielded important new diagnostic information in seven of the eight patients, failing to do so in only one. In one case, CT showed a wooden splinter in an abscess cavity, which had been mistaken for a sequestrum. When combined with accurate clinical and laboratory information and good quality plain radiographs, CT can lead to an early diagnosis of epiphyseal infection. Early diagnosis helps avoid delays in initiating antibiotic or surgical treatment caused by the unusual (epiphyseal or apophyseal) location of the bone abscess.
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We report five cases of children born with forearm wounds associated with motor and sensory losses to the hand and forearm. Their evolution toward muscle retraction is very similar to the classic description of Volkmann's ischemic contracture. These cases should not be confused with upper extremity gangrene of the newborn or aplasia cutis congenita. Two cases of neonatal Volkmann's ischemia have already been reported in the literature and identified as such. Another very similar case has been reported as upper extremity gangrene of the newborn, and three more cases of a forearm wound with neuromuscular involvement have been reported as aplasia cutis congenita. We believe that neonatal Volkmann's ischemic contracture of the forearm should be recognized as a separate entity. Its early diagnosis may improve treatment, especially for children with recent injury, in whom intracompartmental pressures may still be elevated. Early hand therapy and splinting are mandatory to minimize late sequelae.