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Biomedical subjects

J Malpas

Publications and source records attributed to J Malpas.

10 recordsLinked to original sources
PubMed2001

Behaviour of chemical elements during weathering of pyroclastic rocks, Hong Kong.

The behaviour of whole-rock major, trace and rare earth elements (REE) during weathering under subtropical conditions is examined along a profile developed over crystal--vitric tuffs with eutaxitic texture. The intensity of weathering within the profile varies erratically, indicating weathering processes operate over different scales. Quartz, K-feldspar, plagioclase and biotite are the main primary minerals, whereas clays, sesquioxides, sericite and chlorite are the alteration products. Kaolinite, halloysite and illite-mica are the dominant clay minerals present in significantly varying proportions. Two competing processes, namely leaching and fixation, are the main regulators of variations in mostly major and some trace element concentrations along the profile. In general, as the intensity of weathering increases, Ca, Na, K, Sr +/- Si decrease, while Fe, Ti, Al and loss of ignition (LOI) increase. Likewise, the intensity of negative Eu-anomaly decreases while the intensity of negative Ce-anomaly and the La/Lu and Sm/Nd ratios increases. In detail, however, the behaviour of chemical elements cannot be solely explained in terms of the degree of weathering. This study makes it clearly evident that the type and abundance of sesquioxides and clay minerals can significantly modify the geochemical signatures of weathering processes.

Aluminum Silicates↗
PubMed1998

A randomized trial of maintenance interferon following high-dose chemotherapy in multiple myeloma: long-term follow-up results.

High-dose chemotherapy (melphalan) with autologous marrow stem cell support (AMSCS) results in high response rates in multiple myeloma (MM), with up to 50% of patients achieving complete remission. However, these remissions are generally not durable. As the cytokine interferon alpha has been shown to prolong partial response following conventional chemotherapy, this trial was conducted to evaluate its role following high-dose chemotherapy. 85 patients were randomly assigned to maintenance treatment with interferon alpha, 3 x 10(6) units/m2 subcutaneously three times weekly until relapse or no further treatment following recovery from high-dose chemotherapy (melphalan 140-200 mg/m2 or busulphan 16 mg/kg) combined with AMSCS. At 5.8 years following the accrual of the last patient in this trial, 38 patients had died, 17 in the interferon arm and 21 in the control arm. The median progression-free survival (PFS) in the 42 patients randomized to interferon alpha was 46 months versus 27 months in the controls. Both overall survival and PFS, which were highly significant at median follow-up of 52 months, have now ceased to be significant, because most patients have ultimately succumbed to their disease. Interferon was tolerated by the majority of patients with very good compliance. Toxicity consisted mainly of flu-like symptoms and malaise which were usually self-limiting. The results of such a pilot study should be carefully interpreted and the benefits of interferon should be confirmed in larger multicentre studies in the setting of minimal residual disease following autologous transplantation.

Adult↗
PubMed1995

Maintenance therapy for remission in myeloma with Intron A following high-dose melphalan and either an autologous bone marrow transplantation or peripheral stem cell rescue.

Eighty-four patients with myeloma were randomized to receive maintenance Intron A (Schering-Plough, Suffolk, UK), 3 mega units/m2 s.c. three times weekly or no treatment following induction therapy with cyclophosphomide, vincristine, doxorubicin, methyl prednisolone (C-VAMP), consolidated with high-dose melphalan (HDM) 200 mg/m2 + autologous bone marrow transplantation (ABMT). The patients have been followed up for a median of 52 months. Overall, median progression-free survival (PFS) from HDM was 27 months in the control group and 46 months in the Intron A group (< 0.025). For the 65 patients who achieved complete remission (CR) with HDM, there was a significant prolongation of remission (p = 0.02) for those who received Intron A and 49% of these patients remained in remission four years after high-dose treatment. However, for partial responders (PR) and nonresponders to HDM there was no significant prolongation of PFS. Overall, survival was also significantly better for the Intron A group, with 5 deaths versus 14 deaths in the control group (p = 0.006). Subsequently, 54 consecutive patients received the same HDM followed by rescue with peripheral blood stem cells after induction chemotherapy which included C-VAMP. Intron A was started in 45 of these patients at a median of 62 days which was comparable to the ABMT arm. The overall response rate in these patients was 79.62% (43/54-CR+PR) and the probability of survival at 18 months was 74.2% by the Kaplan Meier method.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

High-dose melphalan and autologous bone marrow transplantation as consolidation in previously untreated myeloma.

PURPOSE: We report the results of intensive chemotherapy with high-dose melphalan (HDM) following conventional-dose cytoreductive chemotherapy in previously untreated patients with myeloma. PATIENTS AND METHODS: From 1986 to 1991, 53 previously untreated patients with myeloma received HDM 200 mg/m2 plus methylprednisolone 1.5 g daily (MP) for 5 days with autologous bone marrow transplantation (ABMT) after cytoreductive chemotherapy. RESULTS: At the time of HDM administration, responses to induction therapy were complete remission (CR) in nine patients, partial remission (PR) in 38, and no response (NR) in six. Following HDM, all but one patient responded, with 40 patients achieving a CR (75%). There was one treatment-related death following HDM. The median time to reach a WBC count more than 1,000/microL and platelet count more than 25,000/microL was 19 days (range, 13 to 30) and 24 days (range, 15 to 55), respectively. The median duration of response has not been reached at 20 months, and it is significantly longer for patients in CR than for those in PR (P < .025). Currently, with a median follow-up duration of 31 months (range, 6 to 58), 12 patients are dead and 40 are alive, and the estimated probability of survival at 54 months is 63%. Multivariate analysis found hemoglobin (Hb) more than 10 g/dL (P = .012), and stage A disease (P = .001) at diagnosis to be favorable indicators for survival. CONCLUSION: Myeloma patients who are able to receive HDM plus ABMT following conventional chemotherapy achieve a high proportion of CRs, which may be associated with prolonged survival.

Adult↗
PubMed1994

High-dose melphalan for multiple myeloma: long-term follow-up data.

PURPOSE: To present long-term follow-up data of patients with myeloma treated with high-dose melphalan HDM, including an assessment of prognostic factors. PATIENTS AND METHODS: Between November 1981 and April 1986, 63 previously untreated patients with multiple myeloma received HDM 140 mg/m2 without autologous bone marrow transplantation. RESULTS: The overall response rate was 82% (51 of 62), with 32% (20 of 62) patients entering complete remission (CR). The median duration of response was 18 months, and six patients remain alive and free from disease progression at 60+ to 84+ months. Improvements in quality of life associated with remission were immediate in terms of pain grade (89% of patients) and performance status (92%), and later in terms of bone healing (29%). Currently, at a median follow-up duration of 74 months (range, 63 to 100) since HDM, 23 patients are alive with a median survival duration of 47 months, and 35% of patients are expected to be alive at 9 years. Apart from early-stage disease, no factors were found to predict long-term survival. No second malignancies or other late side effects have been recorded. CONCLUSION: Single-agent HDM without autologous bone marrow transplantation is a feasible therapeutic option in myeloma, and is associated with a high objective response rate, relatively long remission durations, and good symptom control.

Adult↗
PubMed1992

'VEEP' in children with Hodgkin's disease--a regimen to decrease late sequelae.

In an attempt to decrease the risk of second malignancies and future infertility in children with Hodgkin's disease (HD) while retaining acceptable remission rates, an anthracycline based regimen containing no alkylating agent has been devised. VEEP contains vincristine, epirubicin, etoposide and prednisolone given at 3 weekly intervals. Forty-four patients, aged 2-15 years, have been treated: ten relapsed patients and 34 previously untreated with chemotherapy (including three relapsed stage I treated initially with radiotherapy). The median follow up for all patients is 25 months (range 6-52 months). The response rate in previously treated patients was 80% (95% CI 44-97%) and five remain alive in remission. The response rate in untreated patients was 88% (95% CI 72-97%) with 62% CR + CR(u) (uncertain/unconfirmed) (95% CI 44-77%). Of four patients who had a final response of CR(u) three have relapsed at 9, 16 and 38 months. Two of the children in CR have relapsed at 6 and 16 months. The relapse free rate at 3 years is 67% (95% CI 17-82%). In this pilot study the event free survival appears somewhat poorer than conventional combinations and further follow up is required to confirm the salvagability of relapsed patients.

Adolescent↗
PubMed1977

Immunotherapy for acute myelogenous leukaemia: a controlled clinical study 2 1/2 years after entry of the last patient.

One hundred and thirty-nine untreated patients with acute myelogenous leukaemia (AML) were admitted between August 1970 and December 1973 and allocated into two remission treatment regimens: one to receive chemotherapy alone and the other chemotherapy with immunotherapy. Of the patients who attained remission. 22 were in the chemotherapy group and in September 1975 2 remained alive, the median survival time being 270 days and after relapse 75 days. Twenty-eight patients received immunotherapy during remission, and 5 remained alive; the median survival time of the group being 510 days and after relapse 165 days. Ongoing acturial analysis precisely predicted early in the study the median survival of the two groups, but it took a 2-year follow-up after entry of the last patient before it became clear that there were very few long-term survivors. The increase in survival time produced by the immunotherapy is apparently made up of two components: prolongation of the first remission and length of survival after the first relapse. It must be notted that the chemotherapy for this study was devised 6 years ago and the results of the control arm (chemotherapy alone) may be poorer than those obtained in contemporary studies.

Adolescent↗