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Biomedical subjects

T Ahmed

Publications and source records attributed to T Ahmed.

At least 163 records · Page 9Linked to original sources
PubMed1992

Hemopoietic stem cell processing: comparison of progenitor cell recovery using the Cobe 2991 cell washer and the Haemonetics V50 apheresis system.

Using 24 bone marrow (BM) harvests intended for cryopreservation and transplantation, we compared the use of the Cobe 2991 cell washer (2991) and the Haemonetics V50 apheresis system (HV50) for automated BM processing. Our in vitro data indicate that while the mononuclear cell (MNC) concentration of the HV50 product was significantly greater than that of the 2991, the overall MNC recovery of the two products was equivalent. In addition, although the concentration of CFU-GM and BFU-E in the products was equivalent, recovery of these progenitors in the 2991 product was significantly greater than those of the HV50 product. There was no significant difference in either the final product concentration or the overall recovery of cells bearing the primitive myeloid antigens, CD33 or CD34, between the two methods. The HV50 product volume, the red cell and the granulocyte mass were significantly lower than those of the 2991. We conclude that the advantages gained through the use of each machine should be evaluated within the context of the specific intention for the graft. Future advances in the identification and understanding of the primitive stem cell will aid in attempts to evaluate the methods used to isolate these cells.

Adolescent↗
PubMed1992

Homoharringtonine is safe and effective for patients with acute myelogenous leukemia.

Homoharringtonine (HHT) is a cephalotaxine alkaloid with reported efficacy in acute myelogenous leukemia (AML). In a phase II trial, we evaluated HHT 5 mg/m2 by continuous infusion daily for 9 days in patients with relapsed or refractory acute leukemia and blastic phase of chronic myelogenous leukemia (BLCML). Sixty-six patients were entered. There were 40 males and 26 females with a median age of 41 years (range 15-81). Of 43 patients with relapsed AML, seven achieved a complete remission (16%, 95% confidence interval 5%-27%). Although 11 patients with AML primarily resistant to an anthracycline/cytarabine combination did not respond, two of three patients primarily resistant to low-dose cytarabine achieved complete remission. No patients with acute lymphoblastic leukemia, biphenotypic leukemia, or BLCML responded. Hypotension during the administration of HHT was the most difficult toxicity encountered, requiring multiple interruptions of therapy in several patients and the administration of intravenous saline. Fluid retention and weight gain occurred in 29% of patients. Transient asymptomatic hyperglycemia was observed in 63% of patients. Other toxicity was mild and included nausea and vomiting, diarrhea, mucositis, hepatic dysfunction, and cardiac arrhythmias. As expected, severe myelosuppression occurred in all patients. HHT is well tolerated, but with unique problems associated with administration. It has demonstrable efficacy in pre-treated patients with AML, but its role in the treatment of this disease remains to be defined.

Antineoplastic Agents, Phytogenic↗
PubMed1992

Homoharringtonine in combination with cytarabine for patients with acute myelogenous leukemia.

Homoharringtonine (HHT) is one of several cephalotaxine alkaloids that has shown clinical efficacy in patients with acute myelogenous leukemia (AML). In a phase I trial we evaluated cytarabine 100 mg/m2 by continuous infusion daily for 7 days in combination with four dose levels of HHT ranging from 1.5-5 mg/m2 by continuous infusion daily for 7 days to see if an effective regimen could be developed. Twenty-two patients with relapsed and/or primary refractory AML were treated. Seventeen males and five females were treated, with a median age of 40 years (range 19-63). There were five remissions in 14 patients with relapsed AML and none of eight responders in patients with primary refractory AML. None of the three patients treated at 1.5 mg/m2 dose level of HHT responded. Of three patients treated at the 3 mg/m2 dose level, there was one complete remission. At both 4 mg/m2 and 5 mg/m2, two of eight patients achieved complete remission. Four of the five remissions occurred in patients with acute promyelocytic leukemia. Drug induced pancytopenia was universal, and hypotension and fluid retention were more common at the higher dose levels. Other toxicity was mild and included nausea, vomiting, diarrhea, and mucositis. No significant hepatic, renal, or cardiac toxicity was seen. We conclude that the dose of HHT 4 mg/m2 for 7 days by continuous infusion in combination with cytarabine is safe for patients with AML; and this combination is appropriate for a phase II evaluation.

Adult↗
PubMed1992

Humoral antimelanoma immunity: induction by mouse antiidiotypic mAb, MK2-23 and association with survival of patients with advanced melanoma.

This study has shown that a mouse antiidiotypic mAb bearing a mirror image of HMW-MAA can break tolerance to a well-defined self HMW-MAA and can induce humoral anti HMW-MAA immunity in patients with melanoma. Furthermore, the induction of an immune response to a well-defined melanoma-associated antigen has been shown to be associated with a favorable clinical response. If this association reflects a cause-effect relationship between the two parameters, the anti HMW-MAA immunity induced by mouse antiidiotypic mAb MK2-23 may effect immune destruction of melanoma cells and may interfere with the metastatic potential of those cells because of the suggested role of HMW-MAA in this phenomenon.

Animals↗
PubMed1992

Specificity of heme for hemopoietic recovery from AZT toxicity.

The toxicity of azidothymidine (AZT) was studied on normal human bone marrow hemopoietic colony growth as determined by assays of CFU-E, BFU-E, and CFU-GM. The potential sparing effect of hemin and heme analogues on AZT-suppressed bone marrow was also investigated. AZT at a lower concentration (0.1 mumol/L) inhibited CFU-E by 68%, BFU-E by 84%, and CFU-GM by 59%. AZT at a higher concentration (1.0 mumol/L) inhibited CFU-E by 88%, BFU-E by 90%, and CFU-GM by 69%. Addition of hemin (10 mumol/L) to cultures containing AZT (0.1 mumol/L) increased CFU-E growth by 279%, BFU-E by 282%, and CFU-GM by 72%. A similar concentration of heme analogues did not have an enhancing effect; in contrast, zinc protoporphyrin (ZnPP) was inhibitory to bone marrow progenitors CFU-E, BFU-E, and CFU-GM. In addition, no enhancement of colony growth was obtained when progenitor cells were cultured in the presence of 10(-2)-10(-5) M iron. These results demonstrate that exogenous hemin has a specific beneficial effect on human bone marrow hematopoietic progenitor cells which is not seen with iron or other metalloporphyrins. Furthermore, this beneficial effect includes a reversal of the cytotoxic effect of AZT on bone marrow progenitors.

Cell Division↗
PubMed1991

Leukemic dermal infiltrates at permanent indwelling central venous catheter insertion sites.

Three cases of leukemic dermal infiltrates at permanent indwelling central venous catheter insertion sites in patients with acute myelogenous leukemia are reported. Two patients had a localized soft tissue mass at the previous permanent indwelling catheter insertion site as the sole initial manifestation of relapse after achieving complete remission and undergoing bone marrow transplantation. The third patient had catheter tunnel sepsis preceding leukemic dermal infiltration. A review of the English language literature showed that this condition is rare with no specific pathogenetic mechanisms identified. Patients with unresolved catheter tunnel infections in acute leukemia and persistent chest wall masses that appear after a previous permanent indwelling catheter should have a biopsy done and be treated promptly.

Adult↗
PubMed1991

A phase II trial of interleukin-2 by continuous infusion and interferon by intramuscular injection in patients with renal cell carcinoma.

Fifteen patients with advanced, measurable renal cell carcinoma entered a Phase II clinical trial of interleukin-2 (IL-2) (Teceleukin, Hoffmann-La Roche Inc., Nutley, NJ) and interferon (IFN) (Roferon A, Hoffmann-La Roche Inc.). IL-2 was administered by continuous infusion daily for 4 days and IFN was administered by intramuscular injection daily for 4 days; therapy continued for 4 weeks. Eight men and seven women were treated in this trial (median age, 61 years). Toxicity was moderate to severe with fatigue, nausea, vomiting, hypotension, and elevated blood urea nitrogen bunion and creatinine levels seen in all patients. Two patients achieved a complete remission and two patients achieved a partial remission. The median duration of response was 18 months. IL-2 and IFN is an active combination in the treatment of renal cell carcinoma and warrants further investigation.

Adult↗
PubMed1991

Amsacrine is safe and effective therapy for patients with myocardial dysfunction and acute leukemia.

The role of amsacrine in inducing remission in patients with cardiac disease and acute leukemia was evaluated. There were 17 patients with acute myelogenous leukemia (AML), six with acute lymphocytic leukemia (ALL), and one with biphenotypic leukemia. In this series of 24 patients whose disease had relapsed and who had reduced left ventricular ejection fraction, nine had a complete remission, seven with AML and two with ALL. In addition, four of six with newly diagnosed acute leukemia and reduced left ventricular ejection fraction also responded. Among nine patients who underwent endomyocardial biopsy, none had morphologic changes of sufficient degree to account for drug-induced heart failure. Patients with preexisting arrhythmias received amsacrine without incident if their serum potassium level was higher than 4.0 mEq/l at the time of drug administration. Amsacrine is safe and effective therapy for patients with acute leukemia and cardiac disease.

Amsacrine↗
PubMed1991

Hyperoxia prevents hypoxia-induced bronchial hyperreactivity via a cyclooxygenase-independent mechanism.

We tested the hypothesis that prior exposure to alveolar hyperoxia prevents the hypoxia-induced enhancement of bronchial reactivity, possibly via a cyclooxygenase-dependent mechanism. In 15 sheep, specific lung resistance (sRL) was measured before and after 30 min of exposure to either air or a hypoxic gas mixture (13% O2). The sheep then inhaled 50 breaths of aerosolized 5% histamine solution (n = 9) or 10 breaths of 2.5% carbachol solution (n = 9), and measurements of sRL were repeated. On subsequent days the above protocols were repeated after a 30-min exposure to hyperoxia (O2 greater than or equal to 95%), without or after pretreatment with indomethacin (2 mg/kg). After air-sham exposure, carbachol and histamine increased mean sRL to 370 +/- 40 (SE) and 309 +/- 65% of baseline, respectively. Exposure to the hypoxic gas mixture had no effect on baseline sRL but enhanced the airway responsiveness to carbachol and histamine; mean sRL increased to 740 +/- 104 and 544 +/- 76% of baseline, respectively (P less than 0.05). Prior 30-min exposure to hyperoxia prevented the hypoxia-induced enhancement of bronchial reactivity to carbachol (sRL = 416 +/- 66% of baseline) and histamine (sRL = 292 +/- 41% of baseline) without affecting the airway responsiveness to these agents after air. Pretreatment with indomethacin did not reverse the protective effects of hyperoxia or the hypoxia-induced enhancement of bronchial reactivity. We conclude that 1) prior exposure to alveolar hyperoxia prevents the hypoxia-induced enhancement of bronchial reactivity and 2) neither the protective effects of hyperoxia nor the hypoxia-induced enhancement of bronchial reactivity is mediated via a cyclooxygenase-dependent mechanism.

Airway Resistance↗
PubMed1991

Further thoughts on 'cell kill' in acute leukemia.

With traditional therapy of acute myelogenous leukemia, not more than 20% of patients achieve long-term survival. Efforts at intensifying postinduction chemotherapy have resulted in minor improvements only, but this limited progress has been hampered by increasing toxic-death rates. Eradication of the leukemia burden may be achieved by the introduction of more effective induction regimes and these may be rendered more effective by the application of 'enhancers'. With a lower tumor burden, and with more appropriate timing for supralethal therapy, it may be possible to achieve cure with greater frequency. Measurement of 'minimal residual disease' permits more logical selection of postinduction therapy.

Bone Marrow Transplantation↗
PubMed1991

Marrow storage techniques: a clinical comparison of refrigeration versus cryopreservation.

Fifty-three patients were evaluated for a comparison of the efficacy, safety, and cost efficiency of bone marrow (BM) transplanted after either refrigeration or cryopreservation. Thirty-eight patients had BM stored at 4 degrees C for an average of 3 days and 15 patients had cryopreserved BM stored for an average of 56 days. The average number of cells harvested was 3.8 x 10(8)/kg. The time to WBC recovery greater than 1 x 10(9)/l was 17 days refrigerated and 23 days for cryopreserved BM. The time to platelet recovery greater than 20 x 10(9)/l was 24 days for refrigeration storage and 51 days for cryopreserved BM. Four of 38 patients with refrigerated vs. 4/15 patients with cryopreserved BM experienced delayed engraftment (p less than 0.05). Refrigeration storage requires no special equipment, is cheaper than and presents a safe and viable alternative to cryopreserved BM in reconstituting hemopoiesis following high-dose chemo-radiotherapy.

Adolescent↗
PubMed1991

A loading dose/continuous infusion schedule of fludarabine phosphate in chronic lymphocytic leukemia.

Using a loading dose/continuous infusion schedule, fludarabine phosphate was administered to 51 patients with previously treated chronic lymphocytic leukemia (CLL). All patients had evidence of active disease, and the majority had advanced Rai stages. Of the 42 patients assessable for response, 22 (52%) achieved a partial response, five (12%) had stable disease, and 15 (36%) progressed. Thirteen of the 22 responders improved their Rai stages with fludarabine therapy, including six patients who achieved stage 0. Response rates for pretreatment stages III and IV were 60% and 53%, respectively. Patients with final Rai stages 0 to II had better survival than those with stages III and IV. Patients who had undergone splenectomy before starting therapy were more likely to respond. Myelosuppression was the primary toxicity and did not appear to be cumulative. Severe leukopenia and thrombocytopenia, although infrequent, were associated with several deaths in the early cycles of treatment. Nonhematologic toxicity was mild with no serious neurotoxicity noted. Infections were common with 22 minor, 18 major, and 10 fatal episodes. Fludarabine phosphate by this alternative dosing schedule is effective in refractory advanced CLL and is well tolerated by the majority of patients.

Adult↗
PubMed1991

Short course high dose mitoxantrone with high dose cytarabine is effective therapy for adult lymphoblastic leukemia.

Mitoxantrone is effective in the treatment of acute myelogenous leukemia and, in combination with either vincristine-prednisone or cytarabine (HiDAc), it is also effective in acute lymphoblastic leukemia (ALL). As mitoxantrone exhibits a steep dose-response curve against ovarian cancer cells and acute myeloid leukemia cells in vitro, we evaluated the safety and efficacy of high dose mitoxantrone with HiDAc in the treatment of ALL. Patients received mitoxantrone 20-37.5 mg/m2 daily for 2 days or 1 dose of 40-80 mg/m2 and HiDAc 3 g/m2 over 3 h once daily for five doses. All eight of the patients with previously untreated disease and eight of ten patients with ALL in relapse achieved complete remission (CR). The untreated patients included two with Philadelphia positive ALL who also achieved CR (one after one course of mitoxantrone-HiDAc, and one after one course of mitoxantrone-HiDAc followed by one additional dose of vincristine and daily prednisone). Seven of the eight previously untreated patients who achieved CR are still in remission. The one T-cell ALL has relapsed at 2 months after CR. The toxicity was acceptable. The regimen thus induces a remission rate equivalent to that of traditional vincristine-prednisone. The 'quality of remission' may be superior, and this therapy should be explored as a primary induction therapy in patients with ALL.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Randomised double blind trial of single dose doxycycline for treating cholera in adults.

OBJECTIVE: To compare the efficacy of a single dose of doxycycline (200 or 300 mg) with the standard multiple doses of tetracycline in patients with cholera. DESIGN: Randomised double blind controlled trial. Patients were given a single 200 mg dose of doxycycline, a single 300 mg dose of doxycycline, or multiple doses of tetracycline (500 mg, six hourly intervals). SETTING: Hospital in Bangladesh treating diarrhoea. PATIENTS: 261 Patients aged over 15 admitted to the hospital with severe dehydration due to acute watery diarrhoea associated with Vibrio cholerae. All vibrios isolated from the stools and rectal swabs of patients, including those patients with prolonged excretion of vibrios, were sensitive to tetracycline. The stools of all patients at admission were negative for shigella and salmonella. INTERVENTIONS: All patients received rapid intravenous acetate solution for the first four hours after admission to hospital. They were then entered in the study and randomised. Oral rehydration was started immediately after the intravenous treatment. If signs of severe dehydration reappeared during oral treatment patients were given rapid intravenous acetate solution until dehydration was fully corrected. MAIN OUTCOME MEASURES: Stool output in first 24 hours and till diarrhoea stopped, total intake of oral rehydration fluid, duration of diarrhoea, and excretion of vibrio after receiving antibiotic treatment. RESULTS: The median stool outputs during the first 24 hours (275 ml/kg body weight) and till diarrhoea stopped (296 ml/kg body weight) were significantly higher in patients receiving 200 mg doxycycline as a single dose than in patients receiving either standard tetracycline (242 ml/kg body weight and 254 ml/kg body weight) or 300 mg doxycycline (226 ml/kg body weight and 255 ml/kg body weight). Similarly, median consumption of oral rehydration solution (18.45 l) was significantly higher in patients receiving 200 mg doxycycline than in patients receiving either 300 mg doxycycline (16.10 l) or standard tetracycline (14.80 l). Almost equal numbers of patients in each group required unscheduled intravenous acetate solution to correct dehydration during antibiotic treatment. Patients treated with doxycycline (low or high dose), however, had more prolonged excretion of bacteria. CONCLUSIONS: A single 300 mg dose of doxycycline is as effective as the standard multiple dose tetracycline treatment for cholera in terms of stool output, duration of diarrhoea, vomiting, and requirement for oral rehydration solution.

Adolescent↗
PubMed1990

Phase II trial of fludarabine phosphate (F-Ara-AMP) in patients with advanced head and neck cancer.

Thirteen patients with advanced head and neck cancer were entered into a phase II study of fludarabine phosphate. Fludarabine phosphate was given by continuous infusion for 5 days, at a starting dose of 20 mg/m2 per day for patients previously treated with one regimen and 25 mg/m2 per day for previously untreated patients; therapy was repeated every 3-4 weeks. Of the 13 patients, 3 had undergone one prior regimen and 10 patients were previously untreated by chemotherapy. No responses were observed. Myelosuppression was the most common toxicity observed. Four patients developed mild nausea, vomiting and seven developed bleeding stomatitis that resolved in one week. In addition, four patients developed headaches which resolved spontaneously. No renal, hepatic, or neurotoxicity was observed. Our study demonstrates that in previously treated and untreated patients, fludarabine phosphate given on this schedule has little activity in patients with advanced head and neck cancer.

Aged↗