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Biomedical subjects

D Samson

Publications and source records attributed to D Samson.

At least 55 records · Page 3Linked to original sources
PubMed1994

Molecular detection of clonally rearranged cells in peripheral blood progenitor cell harvests from multiple myeloma patients.

Peripheral blood progenitor cells (PBPC) are increasingly used for autologous reconstitution following high-dose chemotherapy in multiple myeloma but it is unclear whether these cells are less likely to be contaminated with malignant cells than bone marrow (BM). We have investigated this using immunoglobulin heavy-chain (IgH) gene fingerprinting, a polymerase chain reaction based technique with a sensitivity of 0.1-0.01% (10(-3)-10(-4)). We have looked for patient-specific IgH rearrangements in leukapheresis samples from eight myeloma patients undergoing PBPC harvest. Seven were in first remission (six partial, one complete) and one in second complete remission. Mobilization of PBPC was accomplished using cyclophosphamide (4 or 7 mg/m2) and rhG- or GM-CSF. Between two and five leukaphereses were performed in each patient. Patient-specific IgH rearrangements were identified in diagnostic BM in all patients and bands of identical size were found in one or more leukaphereses from 6/8 patients. Overall, 14/32 leukaphereses were shown to be contaminated. Two patients who showed contamination of at least one PBPC harvest had BM harvests in which contaminating cells were not detectable, suggesting that PBPC are not necessarily less likely to be contaminated than marrow stem cells. These results indicate that PBPC harvests from the majority of myeloma patients are likely to contain contaminating cells. Further studies are needed to determine whether these cells are clonogenic and whether they contribute to relapse.

DNA Fingerprinting↗
PubMed1994

Prognostic factors in autologous stem cell transplantation for multiple myeloma: an EBMT Registry Study. European Group for Bone Marrow Transplantation.

Autologous bone marrow- and blood progenitor cell transplantation was performed in 130 patients with multiple myeloma in 16 European centers between 1986 and 1993. At the time of follow-up, 77 patients were alive and 53 were dead. Complete remission after transplantation was obtained in 47% of all patients. The actuarial survival at 65 months was 28%. The median duration of relapse-free survival among patients who were in complete remission after transplantation was 29 months. The following factors were predictive for longer survival and freedom of progression in a univariate analysis: Male sex, age less than 45 years, a low serum-beta-2-microglobulin value at diagnosis, prior administration of only one treatment regimen, response on conventional chemotherapy immediately pretransplant and the use of a preparative regimen including melphalan. The last factor, in addition to stage I disease at diagnosis, male sex and responsive disease immediately pretransplant, were also demonstrated as independent predictive variables for longer survival in a multivariate analysis. Progression-free survival was significantly better for patients who were in complete remission after transplantation, as compared to those with persisting signs of disease. We conclude that high-dose chemo-radiotherapy with autologous stem cell transplantation can induce long-term responses, primarily in younger, male patients with chemotherapy-responsive early disease. High-dose melphalan, as single drug or in combination, appeared to be superior to other regimens. The chance of being persistently disease-free seemed to be greatest for patients being in complete remission already before the transplantation.

Adult↗
PubMed1994

E2A/HLF fusion cDNAs and the use of RT-PCR for the detection of minimal residual disease in t(17;19)(q22;p13) acute lymphoblastic leukemia.

Three cases of acute lymphoblastic leukemia (ALL) with the rare t(17;19)(q22;p13) translocation were investigated for E2A/HLF fusion genes using reverse transcription coupled with polymerase chain reaction (RT-PCR). The patients had C-ALL, F/17 years (case 1) or pre-B ALL, M/11 years (case 2) and M/13 years (case 3). Case 1 had an event-free survival (EFS) of 42 months. Case 2 was ultimately refractory to treatment. Case 3 presented following EFS of 16 months in morphological remission (1% blasts), but with immunological and cytogenetic evidence of active disease, then relapsed, remitted and relapsed. Type II E2A/HLF fusion cDNA was found at diagnosis (cases 1, 2), at presentation (case 3) and in all samples tested, whether with active disease or in complete remission (CR). Case 3 showed, in addition, type I fusion E2A/HLF cDNA at presentation, through induction therapy when there was evidence of active disease, but not in CR. Cases 1 and 3 had bone marrow transplantation while in CR but with residual disease detectable by RT-PCR. All patients have died of ALL. Two cases (2 and 3) had hypercalcemia with bone lesions. No case had any evidence of disseminated intravascular coagulation. This is the first demonstration of the value of RT-PCR for the detection of minimal residual disease in t(17;19) ALL.

Adolescent↗
PubMed1994

Surgical planning using three-dimensional imaging and computer modeling.

The acquisition, processing, and use of three-dimensional (3D) imaging provide new insights into normal and abnormal craniofacial anatomy. In this article, characteristics of CT and MRI scanning are reviewed along with the methods used to delineate tissues and produce 3D patient displays, including contouring, shaded surface, and volumetric processing. The use of 3D model fabrication for surgical planning is discussed with examples of the production of a custom CT-based auricle model and the use of rapid prototyping technology to create models for custom alloplastic implant surgery. The review concludes with some speculation about the future of 3D medical imaging as it will influence surgical training and practice over the coming decades.

Diagnostic Imaging↗
PubMed1994

[Peculiarities of the emergency care in pregnant women].

Awareness of the physiological changes associated with pregnancy is essential for the management of patients during pregnancy. Cardiovascular status is characterised by hypervolemia and cardiac hyper-output with low resistance. Increased oxygen consumption and respiratory work result in an increased risk of hypoxia. Fetal well-being must also be taken into account. During cardiorespiratory arrest, aortocaval compression by the pregnant uterus may impair the efficacy of CPR and uterine displacement is a routine measure starting from 20 weeks after the LMP. The same factors are involved in hemorrhagic shock, justifying uterine displacement and the ensuring of optimal oxygen transport and utilisation.

Adult↗
PubMed1994

A clinical study of the parameters and effects of temporary arterial occlusion in the management of intracranial aneurysms.

Temporary occlusion of intracranial arteries has emerged as a valuable technical adjunct in the management of intracranial aneurysms. The current study considered 121 patients (from a group of 234 consecutive aneurysm patients treated during a 2-yr period) who underwent elective temporary arterial occlusion. Twenty-one patients were excluded from further study because of an intraoperative rupture of an aneurysm, the elective sacrifice of afferent or efferent vessels, or the performance of an extracranial-intracranial arterial bypass graft; the remaining 100 patients underwent elective temporary occlusion under a standard neuroanesthetic regimen, including etomidate-induced burst suppression, normotension, normovolemia, and normothermia. In the postoperative period, radiographic evidence of ischemic brain injury in the distribution of the arteries occluded was selected as the end point for the failure of occlusion tolerance. The parameters evaluated with respect to this end point included the duration and nature of the temporary arterial occlusion, the number of the occlusive episodes, the specific vascular territory occluded, patient age, neurological status, presence of subarachnoid hemorrhage, vasospasm, and aneurysm size. Several parameters were found to be related to the postoperative development of ischemic injury. Patients more than 61 years of age and those in poor neurological condition (Hunt and Hess Grades III to IV) did not tolerate temporary occlusion as well as patients who were younger and in better condition. Patients occluded for less than 14 minutes routinely tolerated the iatrogenic ischemia; the 95% confidence level for the toleration of occlusion without the development of infarction occurred at 19 minutes. All patients occluded for more than 31 minutes had both clinical and radiographic evidence of cerebral infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Sustained trilineage response in a patient with ALG-resistant severe aplastic anaemia after treatment with G-CSF, erythropoietin and cyclosporin A: association of recovery with marked elevation of serum alkaline phosphatase.

Aplastic anaemia is characterized by multilineage bone marrow failure resulting in pancytopenia. We have successfully treated a young woman with severe aplastic anaemia (SAA) who was resistant to antilymphocyte globulin (ALG) and corticosteroids, with a combination therapy consisting of erythropoietin, cyclosporin A and granulocyte-colony stimulating factor (G-CSF). The patient received erythropoietin and CSA for a period of 10 months without success before G-CSF treatment was started. After 6 weeks of G-CSF therapy she responded with a sustained trilineage recovery. This suggests that immunosuppression together with haemopoietic growth factors may be an effective treatment in patients with SAA who are ALG resistant and cannot be treated by BMT.

Adolescent↗
PubMed1993

Immunopharmacology of the superantigen staphylococcal enterotoxin A in T-cell receptor V beta 3 transgenic mice.

The response of mouse T cells to the superantigen staphylococcal enterotoxin A (SEA) requires 1000-fold higher concentrations compared to human T cells. In order to develop a sensitive model for SEA studies in mice, the immunopharmacology has been studied in T-cell receptor (TcR) V beta 3 transgenic (TGV beta 3) and non-transgenic (non-TG) C57Bl/6 mice. The frequency of SEA-responsive T cells in the TGV beta 3 mice exceeded 90%, whereas a 10-fold lower frequency was seen in normal C57Bl/6 mice. Nanograms of SEA injected intravenously into TGV beta 3 mice induced strong cytolytic T lymphocyte (CTL) activity against SEA-coated major histocompatibility complex (MHC) class II+ B-lymphoma cells, whereas administration of 1000-fold higher amounts of SEA to non-TG littermates or normal C57Bl/6 mice induced only a moderate response. Kinetic analysis demonstrated that the CTL activity was more rapidly detectable in TG mice, but substantial levels were seen 2 days after SEA injection in both TGV beta 3 and non-TG mice. The cytotoxic T-cell response induced by SEA in TGV beta 3 and non-TG mice was completely MHC class II dependent, as SEA-coated MHC class II-transfected syngeneic B16 melanoma cells but not untransfected B16 cells were sensitive to lysis. Large amounts of tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) accumulated in serum of TGV beta 3 mice after injection of 10 ng SEA, whereas only marginal amounts were recorded in non-TG even after injection of 100 micrograms SEA. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis demonstrated that SEA-induced TNF-alpha and IFN-gamma mRNA reached maximal levels 1 hr after SEA administration in TGV beta 3 mice, whereas peak serum levels of TNF-alpha and IFN-gamma proteins were recorded after 2 hr. Comparison of the mRNA levels of a panel of cytokines in the TGV beta 3 and non-TG mice revealed that almost similar amounts of interleukin-1 (IL-1) were induced in both strains, whereas IL-4 was only detected at significant levels in the TGV beta 3 mouse. The results suggest that TGV beta 3 mice are suitable for studying in vivo immune responses to superantigens at concentrations comparable to the potent effects elicited in humans. Moreover, this model is useful for detailed studies on the dynamic regulation of T-cell activation and anergy induced by superantigens.

Animals↗
PubMed1993

Minimal residual disease after bone marrow transplantation for multiple myeloma: evidence for cure in long-term survivors.

Allogeneic bone marrow transplantation (BMT) can induce long-term complete remission (CR) in patients with multiple myeloma but it is not yet clear whether the disease can be eradicated. We have used immunoglobulin gene fingerprinting, a PCR-based technique, to evaluate minimal residual disease in 5 patients in unmaintained CR 9-60 months after allogeneic BMT. All 5 patients were PCR-positive within the first year after BMT, suggesting that early PCR positivity is common and not predictive of relapse. Three patients were studied at > 1 year post-transplant; one had become PCR-negative at 1 year, a second at 2 years and the third at 4.5 years post-BMT. The ability of the technique to detect clonal evolution was demonstrated by serial studies in a further patient who relapsed post-BMT. The absence of any detectable disease at the molecular level in 3 patients in long-term CR post-transplant suggests that cure of multiple myeloma may be a realistic goal.

B-Lymphocytes↗
PubMed1992

The current position of allogeneic and autologous BMT in multiple myeloma.

The projected outcome of allogeneic BMT for myeloma based on the EBMT data is as follows: for patients transplanted after first line therapy there is a 30% risk of transplant related death, a 55% chance of being alive at 5 years and a 35% chance of being alive in complete remission at 5 years. If BMT is performed later in the course of the disease, the risk of transplant related death is increased and the chance of long term relapse-free survival correspondingly reduced. Conversely, ABMT has a low mortality risk, but there is currently no evidence that ABMT using unpurged marrow can produce long term cure as no series has shown any evidence of a plateau in remission duration. The early results of maintenance interferon are encouraging but longer follow-up is needed to determine whether the proportion of patients in continuing remission at 5 years will approach that seen after allogeneic BMT. Early results of peripheral blood stem cell transplantation are also encouraging but longer follow-up is required. It remains extremely important when comparing results of ABMT with chemotherapy alone to compare similar patient groups, bearing in mind that patients who have autologous transplantation in first response are by definition responders with good performance status and without significant renal failure. In order to address this problem in a prospective manner, a randomised study has been planned by the EORTC in collaboration with the EBMT. In this study, patients with adequate renal function will be randomised at diagnosis to chemotherapy followed by either autologous BMT or continuing chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Marrow Purging↗
PubMed1992

Arteriovenous malformations of the brain: choosing embolic materials to enhance safety and ease of excision.

The authors report their experience with surgical resection of 108 previously embolized arteriovenous malformations (AVM's). Embolization was performed via only transfemoral catheterization in 70 lesions and via the surgical exposure of feeding vessels in 32. The remaining six patients were referred for resection following silicone sphere embolization elsewhere. Materials used included polyvinyl alcohol (PVA) foam, platinum microcoils, detachable silicone balloons, surgical silk, a mixture of 33% ethanol and microfibrillar collagen, and isobutyl cyanoacrylate (IBCA). It is believed that proximal arterial occlusion with balloons is an inferior choice for preresection embolization, because the technical difficulty of placement is high and the nidus of the AVM is unaffected. Vascular coagulation and section and AVM retraction are more difficult with IBCA; therefore, this is also considered an inferior choice. Among the materials studied, the combination of PVA for distal occlusion and microcoils for proximal occlusion appears to be the superior choice. Fewer complications (stroke or hemorrhage) are seen when intraarterial Amytal (amobarbital) testing is used to guide the embolization. Data regarding toxicity, oncogenicity, and vascular metabolism or recanalization associated with PVA, IBCA, and n-butyl cyanoacrylate are reviewed.

Bucrylate↗