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Biomedical subjects

R Seshadri

Publications and source records attributed to R Seshadri.

At least 73 records · Page 4Linked to original sources
PubMed1995

The role of autologous blood transfusion in joint replacement surgery.

The efficacy of predeposited autologous blood transfusion (PABT) with and without intra/postoperative blood salvage to reduce or eliminate the need for homologous blood transfusion (HBT) in primary total hip or knee replacement surgery was investigated by retrospective and prospective studies. Depending on the type of surgery, one to three units of PABT eliminated the need for HBT in 50 to 78% of patients, but, intra/postoperative blood salvage alone reduced the need only in 11 to 29%. In contrast, blood salvage, when combined with three units of PABT, eliminated the need for HBT in all patients undergoing primary joint replacement surgery. A cost comparison analysis showed that blood salvage was more expensive than PABT, and therefore it should be limited to patients who had predeposited fewer than three units of autologous blood.

Adult↗
PubMed1995

Simultaneous determination of N, N-di(n-butyl)doxorubicin-14-valerate and its 8 urinary metabolites by HPLC.

AIM: To develop an HPLC assay for simultaneous determination of AD202 and its metabolites and to examine metabolites of AD202 in urine of rats. METHODS: Reverse-phase HPLC with fluorescence detection and gradient elutionusing a Waters Chromatograph equipped with a 710 B WIFP autosampler, a power Mate SX plus computer, C18 Nova-pak (4 microns) 5 mm x 10 cm radial compression column connected with a guard micro-column, and a Waters 991 photodiode array detector for online observation of UV spectrum of related fraction. RESULTS: Detection limit was 1-3 ng for AD202 and 1-3 ng for its metabolites per injection. After i.v. AD202 20 mg.kg-1, only 4.9% dose as total anthracycline fluorescence signal was recovered in urine over 72 h. The predominant urinary metabolites were AD285 (desacyl AD202) and AD284 (N-mono-debutyl AD285). Six minor metabolites including aglycones and 13-keto reductive product were identified and 3 as-yet unknown metabolites were seen. Enzymatic and acid-hydrolysis failed to reveal the presence of glucuronides in urine. CONCLUSION: The sample analysis techniques developed in this study proved to be very efficient, sensitive, and specific, a total of 11 compounds achieved resolution with detection limit of 2 ng and no interference from matrix. Urine samples can be injected directly into chromatograph without any extraction, making sample analysis simple and time-saving.

Animals↗
PubMed1994

Outcome prediction in childhood acute lymphoblastic leukaemia by molecular quantification of residual disease at the end of induction.

Methods to detect and quantify minimal residual disease (MRD) after chemotherapy for acute lymphoblastic leukaemia (ALL) could improve treatment by identifying patients who need more or less intensive therapy. We have used a clone-specific polymerase chain reaction to detect rearranged immunoglobulin heavy-chain gene from the leukaemic clone, and quantified the clone by limiting dilution analysis. MRD was successfully quantified, by extracting DNA from marrow slides, from 88 of 181 children with ALL, who had total leucocyte counts below 100 x 10(9)/L at presentation and were enrolled in two clinical trials, in 1980-84 and 1985-89. Leukaemia was detected in the first remission marrow of 38 patients, in amounts between 6.7 x 10(-2) and 9.9 x 10(-7) cells; 26 of these patients relapsed. Of 50 patients with no MRD detected, despite study of 522-496,000 genomes, only 6 relapsed. The association between MRD detection and outcome was significant for patients in each trial. In the first trial, patients relapsed at all levels of detected MRD, whereas in the later trial, in which treatment was more intensive and results were better, the extent of MRD was closely related to the probability of relapse (5 of 5 patients with > 10(-3) MRD, 4 of 10 with 10(-3) to 2 x 10(-5), 0 of 3 with levels below 2 x 10(-5), and 2 of 26 with no MRD detected). Early quantification of leukaemic cells after chemotherapy may be a successful strategy for predicting outcome and hence individualizing treatment in childhood ALL, because the results indicate both in-vivo drug sensitivity of the leukaemia and the number of leukaemic cells that remain to be killed by post-induction therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

The relative prognostic significance of total cathepsin D and HER-2/neu oncogene amplification in breast cancer. The South Australian Breast Cancer Study Group.

Total tumor cathepsin D (TCD) levels were determined prospectively by a radioimmunometric assay in tumor cytosol of 858 primary breast cancer patients diagnosed between 1989-1991. In 581 of these patients, tumor HER-2/neu oncogene amplification was simultaneously determined. In a "training-set" of 313 patients, "high" TCD was associated with significantly shorter disease-free survival (DFS). For the whole group, there was no correlation between TCD and pathologic stage, number of axillary nodes with tumor deposits, tumor size, histologic type and grade, or hormone receptor levels. In the node-positive group, high TCD level was associated with HER-2/neu amplification. After a median follow-up duration of 31 months, univariate analysis indicated that high TCD level was significantly associated with shorter DFS only in node-positive patients. The shorter DFS in association with high TCD levels was observed in both estrogen-receptor-positive and -negative patients. Cox multivariate analysis of DFS confirmed that high TCD level was predictive of shorter DFS in node-positive patients only. Because of the short duration of follow-up, the significance of TCD in overall survival was not determined. We conclude that high tumor TCD in node-positive patients is predictive of shorter DFS, and is often associated with HER-2/neu amplification. The possibility exists that high tumor TCD may act in combination with HER-2/neu amplification to promote dissemination of metastases.

Adult↗
PubMed1994

Analysis of phenoxazine chemosensitizers: an electron ionization and keV-ion beam bombardment mass spectrometry study.

The mass spectral behavior of a set of eight 2- and 10-disubstituted phenoxazines putatively possessing anticancer drug enhancer properties was investigated. Both electron ionization (EI) and keV-ion beam bombardment (liquid secondary ion mass spectrometry, LSIMS) were used. As expected, EI led to extensive fragmentation to produce structurally characteristics ions. Except in one example, the molecular ions were reasonably abundant. Two different liquid matrices--sulfolane and 3-nitrobenzyl alcohol--were used to obtain LSIMS data. The use of the latter produced more stable molecular ions. Ion beam bombardment also produced several structure-specific fragments. A unique feature of the LSI spectra obtained using either of the above matrices is production of both M+. and [M + H]+ ions, with the former being more abundant in most cases. Adduct formation with the liquid matrices was also observed for many compounds.

Neoplasms↗
PubMed1994

Cytokine receptor expression in leukaemic cells.

Cytokines have been postulated to play important roles in tumour biology and in the host response to tumours, and a number of therapeutic modalities involving cytokines have been proposed. If patients are to be treated with cytokines, or cytokine inhibitors, it will be important to determine the potential for direct action of the cytokine on the tumour cells. In this study, a high-sensitivity immunofluorescence technique is used to determine the expression of a number of cytokine receptors on a total of 115 leukaemic samples. The results show that many leukaemic samples express low levels of cytokine receptors, and that malignancies of a particular type are heterogeneous with respect to receptor expression. In vitro culture experiments show, as expected, that receptor expression is a necessary but not sufficient requirement for responsiveness to cytokines. The cytokine receptor phenotype may provide useful additional clinical and prognostic information, and should be determined particularly for patients undergoing treatment with cytokines or cytokine inhibitors.

Acute Disease↗
PubMed1994

Dose-intensive cyclophosphamide with etoposide and vincristine for pediatric solid tumors: a phase I/II pilot study by the Australia and New Zealand Childhood Cancer Study Group.

PURPOSE: This pilot study of the Australia and New Zealand Childhood Cancer Study Group investigated the effectiveness and toxicity of a regimen incorporating vincristine (VCR), etoposide, and divided-dose, escalating cyclophosphamide (CPA) (VETOPEC) in 23 patients aged 1 to 20 years with solid tumors. PATIENTS AND METHODS: Seventeen patients (group A) had recurrent or refractory tumors after prior multiagent therapy, and six patients (group B) with adverse prognostic indicators were treated at initial presentation. Treatment cycles were 21 to 28 days and consisted of vincristine (0.05 mg/kg) on days 1 and 14, with etoposide (2.5 mg/kg/d) plus escalating CPA on days 1, 2, and 3. The CPA dosage was escalated from 30 mg/kg/d in cycle no. 1 by 5 mg/kg/d in each cycle to a maximum of 55 mg/kg/d in cycle no. 6. RESULTS: Of 20 patients assessable for tumor response, 19 (95%) responded after two to six cycles of VETOPEC: seven complete responses (CRs); eight very good partial responses (VGPRs); and four partial responses (PRs). In group A, 13 of 14 (93%) assessable patients responded (five CRs, four VGPRs, four PRs), and in group B, five stage IV and one stage III patient achieved two CRs and four VGPRs. The principal toxicity was myelosuppression. Grade IV neutropenia occurred after 98% of cycles, and the incidence of grade IV thrombocytopenia increased from 37% after cycle no. 1 to 91% after cycle no. 6 (P = .002). A total of 115 cycles delivered were followed by 62 febrile admissions (54%), and showed a significant rise with increasing cycles (P = .001). One patient died of septicemia. CONCLUSION: This combination and scheduling produced a high response rate in patients with recurrent, refractory, or advanced solid tumors of childhood. Further studies of this regimen and of strategies to reduce hematologic toxicity are warranted.

Adolescent↗
PubMed1993

Long-term effects of cancer treatment and consequences of cure: cancer survivors enjoy quality of life similar to their neighbours.

To assess the long-term effects of cancer treatment and consequences of cure, 102 index cancer cases were compared with 95 neighbourhood controls of similar age and sex and with 78 cardiac controls. The quality of life experienced by these three groups was examined using multiple instruments with proven psychometric properties. All the major quality of life domains (physical, psychological and social) were covered. The findings revealed that the index cases were similar to their neighbours in areas of subjective well-being. However, the index cases exhibited more sexual dysfunction, were more conscientious, determined and emotionally disciplined, and applied the defence mechanisms of displacement and reaction formation more often than the neighbourhood controls. The cardiac controls were older, more anxious, more conventional/less imaginative and used suppression as a defence mechanism to a greater degree than the index cases. In conclusion, young adult cancer survivors enjoy a quality of life similar to their neighbours, whereas coronary bypass survivors adjust less well psychosocially.

Adolescent↗
PubMed1993

Clinical significance of HER-2/neu oncogene amplification in primary breast cancer. The South Australian Breast Cancer Study Group.

PURPOSE: To determine prospectively the prognostic significance of HER-2/neu oncogene amplification in the primary tumors of breast cancer patients. METHODS: HER-2/neu amplification in tumor DNA was determined by the slot-blot technique in 1,056 patients with breast cancer (stage I to III) diagnosed between 1987 and 1990. Parameters such as estrogen receptor (ER) and progesterone receptor (PgR) levels, tumor size, axillary nodal involvement, tumor grade, and time to relapse were prospectively obtained. RESULTS: HER-2/neu oncogene amplification, > or = 2, > or = 3, and > or = 5 copy number, was detected in 21%, 11%, and 7% of patients, respectively. In a test set of 529 patients, Cox multivariate analysis showed HER-2/neu copy number > or = 3 or > or = 5 was associated with shorter disease-free survival (DFS) duration. HER-2/neu copy number > or = 3 correlated significantly with pathologic stage of disease, number of axillary nodes with tumor, histologic type, and absence of ER and PgR. For all patients, after a median follow-up duration of 39 months, Kaplan-Meier univariate analysis indicated that tumor oncogene copy number > or = 3 correlated with shorter DFS in both node-negative and node-positive patients. In Cox multivariate analysis, HER-2/neu copy number > or = 3 was associated with shorter DFS, independent of nodal status, ER level, and tumor size. CONCLUSION: Although the follow-up duration of this study is relatively short, we conclude that HER-2/neu amplification is an independent predictor of shorter DFS in both node-negative and node-positive patients.

Adult↗
PubMed1992

Synthesis and chemical characterization of N-substituted phenoxazines directed toward reversing vinca alkaloid resistance in multidrug-resistant cancer cells.

A series of 21 N-substituted phenoxazines has been synthesized in an effort to find more specific and less toxic modulators of multidrug resistance (MDR) in cancer chemotherapy. Thus, N-(omega-chloroalkyl)- and N-(chloroacyl)phenoxazines were found to undergo iodide-catalyzed nucleophilic substitution on reaction with various secondary amines, including N,N-diethylamine, N,N-diethanolamine, morpholine, piperidine, pyrrolidine and (beta-hydroxyethyl)piperazine. Products were characterized by UV, IR, 1H-, and 13C-NMR, mass spectral data, and elemental analyses. All of the compounds were examined for cytotoxicity and for their ability to increase the accumulation of the vinca alkaloids, vincristine (VCR) and vinblastine (VLB) in multidrug-resistant GC3/Cl (human colon adenocarcinoma) and KBChR-8-5 (HeLa variant) cell lines. Compounds were compared to the standard modulator verapamil (VRP). Substitutions on the phenoxazine ring at position 10 were associated with an increase in antiproliferative and anti-MDR activities. Modification of the length of the alkyl bridge and the type of amino side chain also influenced the potency of these effects. From among the compounds examined, 10 derivatives were found to increase the accumulation of VCR and VLB in GC3/Cl and KBChR-8-5 cells relative to the effect of VRP, suggesting that with the exception of pyrrolidinyl, the tertiary amine attachments to the phenoxazine nucleus linked through a three- or four-carbon alkyl chain resulted in enhanced anti-MDR activity. On the basis of their 50% growth inhibitory (IC50) values, five of the ten compounds, namely, 10-(3'-chloropropyl)phenoxazine, 10-[3'-[N-bis(hydroxyethyl)- amino]propyl]phenoxazine, 10-(3'-N-morpholinopropyl)phenoxazine, 10-(4'-N-morpholinobutyl)phenoxazine and 10-(N-piperidinoacetyl)phenoxazine were selected as relatively nontoxic chemosensitizers. These modulators, at nontoxic concentrations, potentiated the cytotoxicity of VCR and VLB in GC3/Cl and KBChR-8-5 cells. Further, two compounds 10-(3'-N-morpholinopropyl)phenoxazine, and the butyl derivative, enhanced accumulation of VLB in GC3/Cl, KBChR8-5 and highly resistant KB-V1 cells to a level significantly greater than the maximal level achieved with VRP. Additional experiments to understand the mechanism of action of these agents in modulating MDR are in progress.

Drug Resistance↗
PubMed1992

Epidermal growth factor receptor in breast cancer: storage conditions affecting measurement, and relationship to steroid receptors.

This study investigates the effect of freezing and storage of tissue and subcellular fractions on the measurement of epidermal growth factor receptors (EGF-r); compares competition binding and single saturating dose assays (SSD) for quantitating EGF-r levels; investigates several tissues as potential quality control; and examines the relationship between EGF-r and hormone receptor expression in human breast cancers. Mouse and calf uterine cell membranes were preferred sources of quality control tissue with similar levels of high affinity EGF-r to human breast cancer tissue (less than 150-200 fmol/mg membrane protein). Studies using pooled mouse uterine tissues indicated a loss of 40% in EGF-r activity following a single-20 degrees C freeze/thaw cycle, while a breast cancer tissue showed a 75% loss, independent of storage temperature (liquid nitrogen, -70 degrees C, -20 degrees C). A single freeze/thaw cycle of mouse uterine broken cell pellets (nuclei plus membrane fraction) again indicated a loss of EGF-r irrespective of storage temperature (43% loss at -70 degrees C, 52% loss at -20 degrees C). In most cases irrespective of the tissue type or tissue fraction being stored, the length of storage had little impact on the extent of the loss in activity. A second freeze/thaw cycle of intact tissue, or freezing of broken cell pellets from a previously-frozen tissue, led to a further major or total loss of the remaining EGF-r. Overall these results are commensurate with the published effects of freezing and storage on estrogen receptor measurement. In addition, our studies suggest that the most suitable procedure for assaying frozen breast cancer specimens for EGF-r levels in conjunction with steroid receptor quantitation is to prepare and assay both cytosol and membrane fractions for their respective receptor content without further storage. A concordance of 86% was found in 44 breast cancers assayed for EGF-4 by saturation analysis and SSD. Statistically significant inverse relationships were found between EGF-r and estrogen and progesterone receptor levels in the study of approximately 350 breast cancer patients. No association was found with tumor stage or diameter, axillary node involvement, or patient age.

Animals↗
PubMed1992

Effect of neonatal pineal ablation on estradiol receptors in mammary glands of rats housed under varying photoperiods.

Estradiol receptors (ER) in mammary glands of female Holtzman rats, either intact or neonatally pinealectomised and housed in 10:14 or 24:0 L:D (light:dark) schedule were studied at 30, 40, 50 +/- 5 and 65 +/- 5 days of age. Whereas ER were detectable only at the age of 60-65 days in intact rats housed in 10:14 L:D, they were present as early as 30 days onwards in the pineal ablated group. In the 24:0 L:D pinealectomised group, though mammary gland ER were maximum around 40 days of age and temporarily undetectable around day 50, they had stabilized around the age of 60-65 days. The data demonstrates for the first time, the modulation of ER in rat mammary glands in response to varying photoperiods as well as pineal ablation. Earlier reports on incidence of chemically induced mammary tumours have been compared to the receptor modulation.

Animals↗