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Biomedical subjects

S M Ansell

Publications and source records attributed to S M Ansell.

36 records · Page 2Linked to original sources

Primary laryngeal lymphoma.

Primary laryngeal lymphoma is a very rare entity, with fewer than 50 cases reported in the English literature in the past 60 years. Close scrutiny of some of these case reports reveals that the larynx was not always the only site of involvement, thereby diminishing the total number of patients with primary laryngeal lymphoma to fewer than 35. The authors report a series of six patients, who were seen and evaluated at the Mayo Clinic between 1952 and 1995, with stage IAE non-Hodgkin's lymphoma of the larynx. Three patients had large-cell lymphomas according to the REAL (Revised European-American Lymphoid) classification. The other three had a small lymphocytic lymphoma, follicular small cleaved lymphoma, and follicular mixed lymphoma. All patients received radiation therapy alone as initial therapy for their disease and all patients had a complete remission to initial therapy. Four patients subsequently relapsed and the histology at relapse was the same as the initial histology in all four patients. Five patients have died, three of lymphoma, with a median survival of 67 months (range, 40 to 228 months). In view of the heterogeneity of histologies in this group of lymphomas, the variability in duration of response, and the significant number of patients who died of their disease, it is more likely that primary laryngeal lymphoma is an unusual presentation of non-Hodgkin's lymphoma than a separate disease entity. Despite the small number of patients in this study, the data would suggest that patients are best treated according to the histology of the lymphoma, rather than the limited stage and location of the disease.

Adult↗

Predictive capacity of the International Prognostic Factor Index in patients with peripheral T-cell lymphoma.

PURPOSE: The International Prognostic Factor Index has been shown to predict the outcome of patients with predominantly B-cell lymphomas classified using traditional classifications, including the Working Formulation, but its prognostic importance has not been tested in a cohort of patients with exclusively T-cell lymphomas. This study was conducted to evaluate the prognostic significance of the International Prognostic Factor Index in patients with peripheral T-cell lymphoma (PTCL). PATIENTS AND METHODS: Seventy-eight patients (48 men and 30 women) with PTCL seen at a single institution between 1985 and 1995 were included in the analysis. The morphology and immunocytochemistry of all the original biopsy specimens were reviewed by a single pathologist and classified using the Revised European-American Lymphoma (REAL) classification. The International Prognostic Factor Index, as well as clinical and biochemical parameters, were evaluated by univariate and multivariate analyses to determine their association with patient outcome. RESULTS: The International Prognostic Factor Index strongly predicted survival when all patients were included in the analysis (P < .001). For patients < or = 60 years, the age-adjusted International Index significantly predicted long-term survival (P = .0218). For patients older than 60 years, the age-adjusted International Index also significantly predicted survival (P = .002). Liver involvement (P = .006) and bone marrow involvement (P = .014) were also significant prognostic factors in the univariate analysis, but only the International Index remained significant in the multivariate analysis (P = .001). CONCLUSION: The International Prognostic Factor Index, which significantly predicts outcome in patients with aggressive/intermediate-grade B-cell lymphomas, has similar prognostic importance in patients with PTCL.

Adolescent↗

Illicit intravenous drug use in Johannesburg--medical complications and prevalence of HIV infection.

OBJECTIVE: To describe the magnitude of the problem of abuse by self-injection of dipianone HCl/cyclizine HCl (Wellconal) and to document the associated morbidity, mortality and prevalence of HIV infection. DESIGN: We conducted a retrospective analysis of 121 admissions of 86 patients who were current intravenous Wellconal abusers and presented to Johannesburg and J G Strijdom Hospitals over an 18-month period. Case records were analysed in respect of age, sex, median hospital stay, complications, HIV antibody status and eventual outcome. MAIN OUTCOME MEASURES: Age, sex, median hospital stay, complications, HIV antibody status and eventual outcome. RESULTS: Complications of Wellconal abuse occurred in young adults (median age 24 years) with an approximately equal gender distribution. Opiate overdose was the most frequent presenting diagnosis (32%), followed by right-sided endocarditis (20%) and deep-vein thrombosis (12%). A wide variety of complications accounted for the remaining 36%. A 2% HIV antibody positivity rate was found, which is substantially lower than that encountered in intravenous drug abusers in other parts of the world. Seventy-eight per cent of patients completed therapy successfully, but 19% left hospital prematurely against medical advice. There was a mortality rate of 3%. CONCLUSIONS: While the prevalence of Wellconal abuse in the broader South African community is unknown, our study draws attention to the extent of the problem in Johannesburg.

Adolescent↗

Study of critically ill patients with systemic lupus erythematosus.

OBJECTIVES: To determine the presenting features, prognostic factors, course, and outcome of critically ill patients with systemic lupus erythematosus admitted to the intensive care unit (ICU). DESIGN: Retrospective patient record review. SETTING: Two academic teaching hospitals. PATIENTS: All patients with systemic lupus erythematosus admitted to the ICUs between January 1982 and July 1993. MEASUREMENTS AND MAIN RESULTS: There were 28 female and two male patients. Fifteen patients were white, 11 patients were black, and four patients were Asian. The median age was 29 yrs. The reasons for admission to the ICU were multifactorial. However, most patients were admitted for infective, renal, cardiac, or coagulation complications. Despite aggressive management, 16 (53%) patients died in the ICU or shortly after discharge. The median ICU survival rate (admission to death) was 22 days. The only pretreatment factor that predicted a poor outcome was the presence of renal involvement due to systemic lupus erythematosus. CONCLUSIONS: Our study suggests that patients with systemic lupus erythematosus admitted to an ICU often have florid disease manifestations with multifactorial reasons precipitating the admission. The prognosis for such patients is poor, particularly in the presence of renal involvement.

APACHE↗

Factors influencing the retention and chemical stability of poly(ethylene glycol)-lipid conjugates incorporated into large unilamellar vesicles.

Poly(ethylene glycol)(PEG)-lipid anchor conjugates can prolong the circulation lifetimes of liposomes following intravenous injection. In this work we investigate the influence of the lipid anchor and the nature of the chemical link between the PEG and lipid moieties on circulation lifetime. It is shown that incorporation of N-(monomethoxypoly(ethylene glycol)2000-succinyl)-1-palmitoyl-2-oleoylphosphatidylethanolamide (MePEG2000-S-POPE) into large unilamellar vesicles (LUVs) composed of distearoylphosphatidylcholine (DSPC) and cholesterol (DSPC/cholesterol/MePEG2000-S-POPE, 50:45:5, mol/mol) results in only small increases in the circulation lifetimes as observed in mice. This is shown to be due to rapid removal of the hydrophilic coating in vivo, which likely arises from exchange of the entire PEG-lipid conjugate from the liposomal membrane, although chemical breakdown of the PEG-lipid conjugate is also possible. The chemical stability of four different linkages was tested, including succinate, carbamate and amide linkages between MePEG derivatives and the amino head group of PE, as well as a direct link to the phosphate head group of phosphatidic acid (PA). The succinate linkage was found to be the most labile. The anchoring capability of DSPE as compared to POPE in PEG-PE conjugates was also examined. It is shown that incorporation of MePEG2000-S-DSPE conjugates into DSPC/cholesterol LUVs results in little loss of the PEG coating in vivo, long circulation lifetimes and reduced chemical breakdown of the PEG-lipid conjugate. This work establishes that DSPE is a considerably more effective anchor for PEG2000 than POPE and that the chemical stability of PEG-PE conjugates is sensitive to the nature of the linkage and exchangeability of the PEG-PE complex. We suggest that retention of the PEG coating is of paramount importance for prolonged circulation lifetimes.

Animals↗

Polyethylene glycol modified phospholipids stabilize emulsions prepared from triacylglycerol.

A stable lipid-based carrier system containing a triacylglycerol core has been developed. This has been achieved by homogenization of corn oil (primarily triacylglycerol) in the presence of phosphatidylcholine (PC), preformed 100 nm liposomes prepared from PC/cholesterol (55: 45; mol:mol) and polyethylene glycol modified phosphatidylethanolamine (PEG2000-PE). The lipid/liposome mixtures were emulsified using a microfluidizer, and the resulting particles could, depending on the phospholipids used and the addition of cholesterol, be designed to exhibit a uniform mean particle size of less than 100 nm (as measured by quasielastic light scattering). The presence of an oil core within the emulsified lipid preparation was confirmed by freeze-fracture and cryoelectron microscopy. Stability of the resulting PEG2000-PE-coated triacylglycerol emulsion was determined by several techniques including (1) time dependent changes in light scatter determined by measuring changes in absorbance at 600 nm (decreases in absorbance are indicative of unstable oil emulsions), (2) column chromatography procedures evaluating the migration of incorporated lipids, specifically PEG2000-PE and triolein, after emulsions were incubated at 37 degrees C in the presence and absence of serum, and (3) in vivo plasma clearance data demonstrating that the lipid mixtures were maintained at ratios specified prior to i.v. administration. This emulsion technology has been used to prepare formulations of several water insoluble compounds, such as the drugs taxol and dibucaine and the lipophilic dye sudan IV.

Animals↗

Survival determinants in patients with advanced ovarian cancer.

An analysis was performed on 127 consecutive women with advanced measurable ovarian cancer to evaluate factors predicting for survival. All patients received cis-platinum-based chemotherapy as treatment for stage IIIB to stage IV disease. Eighteen clinical, radiological, and biochemical parameters were subjected to univariate and multivariate analyses. Recursive partitioning and amalgamation (RPA) was used to define prognostic subsets with different survival potentials. In the univariate analysis, factors that predicted for survival were weight loss, histology, stage, number of metastases, presence of ascites, size of the residual tumor, and rate of tumor response. When these significant variables were included in a Cox model, advanced stage of disease, histology other than adenoserous carcinoma, the presence of tumor bulk, and a slow rate of tumor response independently predicted a poorer survival. Using the three disease-related prognostic variables, a RPA model was derived and three groups were identified with median survival times of 76, 28, and 21 months, respectively (P = 0.001). The best survival time of 76 months was seen in patients with stage III, nonbulky, adenoserous ovarian carcinoma. It is concluded that the rate of tumor response is important in predicting the outcome of patients with ovarian cancer. Furthermore, the interactions between prognostic factors are emphasized by the RPA model and a subgroup of patients with a projected 10-year survival of 50% is identified.

Analysis of Variance↗

Chronological age is a multifactorial prognostic variable in patients with non-Hodgkin's lymphoma.

In order to assess the predictive capacity of chronological age for survival, an analysis of prognostic variables was performed on 277 patients with Non-Hodgkin's Lymphoma, 84 of whom were older than 65 years. All patients were seen at a single institution, and elderly patients, who might otherwise have been excluded from study analysis, were included. Seventeen clinical, radiological and laboratory parameters were evaluated and subjected to univariate and multivariate analyses. Patients older than 65 years had a significantly poorer survival than those younger than 65 years. When the whole group was considered in a multivariate (Cox) model, the factors that independently predicted a longer survival were a good performance status, age less than 65 years and a low grade histological subtype. When patients older and younger than 65 years were analyzed separately the prognostic variables in the elderly were found to be similar to those in younger patients. The predictive capacity of chronological age was found to be influenced by a poor performance status, the presence of concomitant disease, the dose intensity and tolerance of the treatment given, as well as the physiological reserve of the patient. It is concluded that chronological age is a multifactorial prognostic parameter encompassing a number of patient and treatment factors, all of which must be considered when evaluating the capacity of chronological age to predict survival in patients with Non-Hodgkin's Lymphoma.

Aged↗

Trisomy 5 in Ph+ chronic myeloid leukemia in association with megakaryocytosis.

A patient with a megakaryocytosis associated with a Philadelphia chromosome-positive chronic myeloid leukemia (CML) was found to have a trisomy of chromosome five. To our knowledge, this is the first case of trisomy 5 associated with a Ph + CML, particularly one with a megakaryocytosis. The trisomy 5 may be associated with the resistance to cytostatic drugs found in this patient.

Chromosomes, Human, Pair 5↗

Sister chromatid exchanges in lymphocyte cultures of patients previously treated with dibromodulcitol.

Acute non-lymphatic leukaemia and myelodysplasia occur in a larger percentage of patients treated with dibromodulcitol (DBD) than in patients treated with other cytostatics. Sister chromatid exchanges (SCE) in the lymphocytes in peripheral blood as well as other haematological parameters were measured in women with breast cancer to investigate whether women who had previously been treated with DBD as a part of their treatment regime had an increased frequency of SCE or another haematological abnormality attributable to DBD. SCE levels were elevated in women treated with DBD as well as in those treated with other cytostatics compared to the untreated control group. All other haematological parameters were normal. There was no significant difference in the number of SCEs between the patients who received DBD and those treated with other cytostatics. The increased frequencies of SCE in the treated patients are attributable to various cytostatic agents, and there is no significant permanent increase in the frequency of SCE after exposure to DBD.

Breast Neoplasms↗

Ifosfamide in advanced carcinoma of the esophagus: a phase II trial with severe toxicity.

Seventeen patients with advanced epidermoid carcinoma of the esophagus were treated with ifosfamide (IFOS) 1.5 mg/m2/day intravenously on days 1-5 every 28 days. Mesna was given concurrently at 20% of the IFOS dose prior to and 4 and 8 h after IFOS for uroprotection. Toxicity in this trial was severe since life-threatening leukopenia occurred in one patient, Grade 3 nausea and vomiting (necessitating termination of treatment) in two patients, and Grade 3 neurotoxicity (cerebellar dysfunction) in two patients. Two patients developed severe infections (Grade 3). Only four patients experienced no toxicity. One patient had a partial response with a response duration of 8 weeks. The median survival of all patients is 10 weeks. It is concluded that IFOS as given in this trial has limited activity in esophagus carcinoma with severe toxicity.

Carcinoma, Squamous Cell↗

Poly(ethylene glycol)-modified phospholipids prevent aggregation during covalent conjugation of proteins to liposomes.

Liposome aggregation is a major problem associated with the covalent attachment of proteins to liposomes. This report describes a procedure for coupling proteins to liposomes that results in little or no change in liposome size. This is achieved by incorporating appropriate levels of poly(ethylene glycol)-modified lipids into the liposomes. The studies employed thiolated avidin-D coupled to liposomes containing the thio-reactive lipid N-(4-(p-maleimidophenyl)butyryl)dipalmitoyl phosphatidylethanolamine (1 mol % of total lipid) and various amounts of MePEG-S-POPE (monomethoxypoly(ethylene glycol) linked to phosphatidylethanolamine via a succinate linkage). The influence of PEG chain length and density was also assessed. The presence of PEG on the surface of liposomes is shown to provide an effective method of inhibiting aggregation and the corresponding increase in liposome size during the covalent coupling of avidin-D. A balance between the size of the PEG used and the amount of PEG-lipid incorporated into the liposome had to be achieved in order to maintain efficient coupling. Optimal coupling efficiencies in combination with minimal aggregation effects were achieved using 2 mol % MePEG2000-S-POPE (PEG of 2000 MW) or 0.8 mol % MePEG5000-S-POPE (PEG of 5000 MW). At these levels, the presence of PEG did not affect the biotin binding activity of the covalently attached avidin. The ability of the resulting liposomes to specifically target to biotinylated cells is demonstrated.

Animals↗

3-(2-pyridyldithio)propionic acid hydrazide as a cross-linker in the formation of liposome-antibody conjugates.

Liposome antibody conjugates are potentially useful as a means of targeting drugs to specific tissues. A new protocol for the conjugation of IgG to maleimide-containing liposomes was developed using 3-(2-pyridyldithio)propionic acid hydrazide (PDPH) as a cross-linker. Periodate-oxidized antibody was treated with PDPH to yield a hydrazone derivative. Deprotection with DTT produced a thiolated antibody which was then conjugated to liposomes containing N-[4-(p-maleidophenyl)butyryl]-1,2-sn-distearoylphosphatidyleth anolamine. The liposome-antibody conjugates were found to have in vitro properties similar to those of conjugates formed by the traditional 3-(2-pyridyldithio)propionic acid N-hydroxysuccinimide ester (SPDP) protocol but were cleared less rapidly in circulation. The PDPH protocol presents a viable alternative to SPDP, particularly for antibodies sensitive to amine modification.

Animals↗

Synthesis of polyamide oligomers based on 14-amino-3,6,9, 12-tetraoxatetradecanoic acid.

A series of oligomers of polyamides based on 14-amino-3,6,9, 12-tetraoxatetradecanoic acid monomers (ATTAn) was synthesized. These materials were designed as monodisperse analogues of poly(ethylene glycol) for use in biomedical applications where reproducible behavior is important. Synthesis of the monomer was evaluated using two routes. For small-scale preparations, tetraethylene glycol (TEG) was monoprotected with dihydropyran, converted to an alkoxide, and alkylated with ethyl bromoacetate. On larger scales, TEG was alkylated directly by treatment with sodium, followed by ethyl bromoacetate. The amine function was introduced by mesylation followed by treatment with sodium azide. Reduction of the azide to amino groups was performed over Pd/C using either hydrogen or formic acid as proton sources. Assembly of the oligomers was accomplished using standard DCC/NHS chemistry and an iterative dimerization sequence after appropriate deprotection of a pair of monomers. The amino group was protected by retaining the azido group as a latent amine. A series of ATTAn oligomers was prepared (n = 1-8). A lipid conjugate of the octamer, ATTA8-DSPE, was synthesized.

Biocompatible Materials↗

Application of oligo-(14-amino-3,6,9,12-tetraoxatetradecanoic acid) lipid conjugates as steric barrier molecules in liposomal formulations.

Lipid conjugates of oligo-(14-amino-3,6,9,12-tetraoxatetradecanoic acid) (ATTAn) were synthesized as monodisperse analogues of poly(ethylene glycol) (PEG) derivatives used in liposomal drug delivery systems. The new lipids were shown to be at least equivalent to MePEGA-2000-DSPE in assays designed to evaluate the effectiveness of polymers as steric barrier molecules in liposomes. Liposomes containing 1-5% of ATTA8-DSPE (octamer) showed comparable long circulation behavior relative to PEG-2000-DSPE analogues. Surprisingly, the shorter ATTA4-DSPE (tetramer) appeared to be quite effective in reducing clearance. Liver enzyme levels and systemic single dose tolerability of ATTA8-DSPE liposomes were comparable to controls, suggesting that the new materials are nontoxic. Prolonged exposure of ATTA8-DSPE liposomes to splenocytes in vitro showed no evidence of mitogenicity relative to controls or MePEGA-2000-DSPE liposomes. ATTA8-DSPE was as effective as MePEGC-2000-DSPE in preventing complement activation by cationic liposome systems. Repeat dosage in vivo regimes in ICR mice using DSPC/cholesterol liposomes, with and without 5% ATTA8-DSPE and MePEGC-2000-DSPE, showed no evidence of enhanced clearance on successive doses. Splenocytes recovered after repeat doses showed no significant evidence of mitogenicity on restimulation with liposomes. Cellular differentiation and activation marker levels in splenocytes recovered after the fourth in vivo administration were at normal levels. These results suggest that ATTAn oligomers do not induce an immune response in isolation. It was demonstrated that ATTA8-DSPE could be used to replace PEG-lipids in the formulation of doxorubicin, plasmid DNA and oligonucleotides using a variety of formulation techniques. The study demonstrates that ATTAn oligomers can be safely and effectively used in place of poly(ethylene glycol) as well-defined biomaterials in liposomal applications where reproducible behavior is critical.

Animals↗

Rituximab toxicity in patients with peripheral blood malignant B-cell lymphocytosis.

Infusion related adverse events (AE) with day 1 rituximab in patients with B-cell non-Hodgkin's lymphoma (NHL) are common. The purpose of this study was to evaluate the AE occurring in patients with malignant B-cell lymphocytosis who received rituximab. Patients with a > or = 3 x 10(9)/L absolute lymphocyte count (ALC) receiving rituximab from 1998 to 1999 or participating in a phase I study of rituximab and interleukin-12 were reviewed. The AE occurring on the day of rituximab, the treatment provided (including hospitalization), and the subsequent ALC responses were recorded. Twenty-seven patients were identified; 14 had NHL, one Waldenstrom's macroglobulinemia, and 12 patients had chronic lymphocytic leukemia. The baseline median ALC was 9.58 x 10(9)/L (mean, 49.31; range, 3.56-380.95). All patients received rituximab as an outpatient. There were only two AE > or = grade 3. One patient was hospitalized for 1 day for i.v. fluids to treat an increase in creatinine that occurred with tumor lysis. A second patient developed a pulmonary syndrome five days after day 1 rituximab and required mechanical ventilation, but had no long-term lung toxicity. This study demonstrates that patients with high numbers of circulating blood B-lymphocytes can usually safely receive rituximab as outpatients. Patients who experience a rapid drop in ALC should be monitored closely for tumor lysis and the pulmonary syndrome.

Adult↗