A pilot study comparing hearing thresholds of soldiers at induction and after completion of one year in high altitude area.

BACKGROUND: Despite so much research in high altitude area, our existing knowledge is still lacking on otological effects of long-term stay in high altitude. This pilot study was conducted to compare the hearing thresholds of army soldiers at induction and after completion of one year in high altitude area (HAA). METHODS: Hearing thresholds of 433 soldiers posted in HAA were recorded using pure tone audiometry at the time of induction and second thresholds after one year of stay in high altitude for frequencies of 500Hz, 1KHzs, 2 KHzs and 4 KHzs. The two sets of hearing thresholds for air conduction were compared using paired "t" test for any statistical significance. RESULTS: The mean Pure Tone Audiometry (PTA) thresholds for 433 left ears worsened from 9.43dB to 9.65dB at 500 HZs ; 14.02dB to 14.32dB at 1 KHZs ; 15.04dB to 16.09dB at 2KHzs and 18.63dB to 22.59dB at 4 KHZs. Similarly for right ear, PTA thresholds worsened from 9.43dB to 9.69dB at 500HZs; 13.95dB to 14.34dB at 1 KHZs; 15.38dB to 17.26dB at 2 KHZs and from 18.59dB to 23.06dB at 4KHZs. These results are found to be statistically significant (p<0.05) for all frequencies. CONCLUSION: This pilot study shows deterioration of hearing thresholds in tested frequencies in both ears after a long stay (one year) in high altitude area. We recommend further structured research on otologic effect of long term stay in high altitude.

Twelve tips for establishing a new medical school.

Many new medical programs have been established during the last 20 years, and this trend seems set to continue as the health care needs of the world's populations become more complex and demand increases for more physicians to provide the necessary health care. In this paper, we address how best to establish a new medical school, based on our experiences in new ventures in several countries. Success requires a combination of boldness of vision, support from many stakeholder groups, adequate financial and human resources, educational expertise, confidence, patience, and persistence.

p28, a first in class peptide inhibitor of cop1 binding to p53.

BACKGROUND: A 28 amino-acid (aa) cell-penetrating peptide (p28) derived from azurin, a redox protein secreted from the opportunistic pathogen Pseudomonas aeruginosa, produces a post-translational increase in p53 in cancer cells by inhibiting its ubiquitination. METHODS: In silico computational simulations were used to predict motifs within the p53 DNA-binding domain (DBD) as potential sites for p28 binding. In vitro direct and competitive pull-down studies as well as western blot and RT-PCR analyses were used to validate predictions. RESULTS: The L1 loop (aa 112-124), a region within the S7-S8 loop (aa 214-236) and T140, P142, Q144, W146, R282 and L289 of the p53DBD were identified as potential sites for p28 binding. p28 decreased the level of the E3 ligase COP1 >80%, in p53wt and p53mut cells with no decrease in COP1 in p53dom/neg or p53null cells. Brief increases in the expression of the E3 ligases, TOPORS, Pirh2 and HDM2 (human double minute 2) in p53wt and p53mut cells were in response to sustained increases in p53. CONCLUSION: These data identify the specific motifs within the DBD of p53 that bind p28 and suggest that p28 inhibition of COP1 binding results in the sustained, post-translational increase in p53 levels and subsequent inhibition of cancer cell growth independent of an HDM2 pathway.

A first-in-class, first-in-human, phase I trial of p28, a non-HDM2-mediated peptide inhibitor of p53 ubiquitination in patients with advanced solid tumours.

BACKGROUND: This first-in-human, phase I clinical trial of p28 (NSC745104), a 28-amino-acid fragment of the cupredoxin azurin, investigated the safety, tolerability, pharmacokinetics and preliminary activity of p28 in patients with p53(+) metastatic solid tumours. METHODS: A total of 15 patients were administered p28 i.v. as a short infusion three times per week for 4 weeks followed by a 2-week rest under an accelerated titration 3+3 dose escalation design until either a grade 3-related adverse event occurred or the maximum tolerated dose (MTD) was reached. Single-dose and steady-state serum pharmacokinetics were characterised. Assessments included toxicity, best objective response by RECIST 1.1 Criteria, and overall survival. RESULTS: No patients exhibited any dose-limiting toxicities (DLTs), significant adverse events or exhibited an immune response (IgG) to the peptide. The No Observed Adverse Effect Level (NOAEL) and MTD were not reached. Seven patients demonstrated stable disease for 7-61 weeks, three a partial response for 44-125 weeks, and one a complete response for 139 weeks. Three patients are still alive at 158, 140, and 110 weeks post therapy completion. CONCLUSION: p28 was tolerated with no significant adverse events. An MTD was not reached. Evidence of anti-tumour activity indicates a highly favourable therapeutic index and demonstrates proof of concept for this new class of non-HDM2-mediated peptide inhibitors of p53 ubiquitination.

Are medical student results affected by allocation to different sites in a dispersed rural medical school?

INTRODUCTION: As medical education becomes more decentralised, and greater use is made of rural clinical schools and other dispersed sites, attention is being paid to the quality of the learning experiences across these sites. This article explores this issue by analysing the performance data of 4 cohorts of students in a dispersed clinical school model across 4 sites. The study is set in a newly established medical school in a regional area with a model of dispersed education, using data from the second to fifth cohorts to graduate from this school. METHODS: Summative assessment results of 4 graduating cohorts were examined over the final 2 years of the course. Two analyses were conducted: an analysis of variance of mean scores in both years across the 4 sites; and an analysis of the effect of moving to different clinical schools on the students' rank order of performance by use of the Kruskal-Wallis test. RESULTS: Analysis revealed no significant difference in the mean scores of the students studying at each site, and no significant differences overall in the median ranking across the years. Some small changes in the relative ranking of students were noticed, and workplace-based assessment scores in the final year were higher than the examination-based scores in the previous year. CONCLUSIONS: The choice of clinical school site for the final 2 years of an undergraduate rural medical school appears to have no effect on mean assessment scores and only a minor effect on the rank order of student scores. Workplace-based assessment produces higher scores but also has little effect on student rank order. Further studies are necessary to replicate these findings in other settings and demonstrate that student learning experiences in rural sites, while popular with students, translate into required learning outcomes, as measured by summative assessments.

Rural internships for final year students: clinical experience, education and workforce.

INTRODUCTION: The James Cook University School of Medicine is the only complete medical school in northern Australia, and it has a mission to prepare graduates to meet the unique needs of the region with a particular emphasis on rural, remote, Indigenous and tropical health. Eight-week 'rural internships' have been undertaken by all sixth-year medical students at James Cook University since 2005. Each student had previously completed at least 12 weeks of structured rural placements in years 2 and 4, as well as other core teaching in rural health including the year 2 subject, 'Rural, Remote, Indigenous and Tropical Health'. Students worked in rural hospitals across northern Australia developing and practising clinical skills under the supervision of senior staff. Students undertook full-time inpatient and outpatient responsibilities under supervision, being rostered for after-hours work with appropriate support. Assessment involved a learning portfolio, including multi-source feedback from peers, supervisors and patients, and a population health project and a telephone referral exercise. METHODS: This article describes the development, implementation and assessment of the first years of the program, from 2005 to 2007. Evaluation included student questionnaires, site visits and interviews, and follow-up teleconferences with preceptors. RESULTS: The rural internship provides senior medical students with valuable experience by active participation in the healthcare team. Students reported a rich and varied clinical experience. Students accept limited supervised responsibility and further their ability and confidence to undertake the role of the intern. Importantly, they proved not to be a burden to the system. This rotation therefore appears to meet educational needs without compromising the local workforce (and indeed may add to it). Students felt welcomed by their communities and enjoyed the social and cultural aspects of their attachment, as well as the clinical aspects and the opportunity to further their understanding of rural communities, rural health care and the healthcare team. Preparation of the students, the preceptors and the communities emerged as a key element of success. CONCLUSION: This model extends and enhances the traditional apprenticeship model by its rural focus and distributed nature, and involvement of the entire student cohort. In addition, the contribution to patient care by senior students and junior doctors enables a consultant-registrar-resident model, in which experienced rural doctors function as consultants providing advice, support and tuition rather than predominantly face-to-face patient care. This approach also provides a means to address an emerging paradox: rural preceptors and communities want to teach students, appreciating the long-term workforce implications, but are increasingly constrained by resources, particularly time. Similar innovative approaches should be explored in other settings.

Concurrent infection of Bluetongue and Peste-des-petits-ruminants virus in small ruminants in Haryana State of India.

Bluetongue (BT) and peste-des-petits-ruminants (PPR) are major transboundary diseases of small ruminant, which are endemic in India. Testing of bluetongue virus (BTV) and peste-des-petits-ruminants virus (PPRV) from recent outbreaks (2015-2016) in different regions of Haryana State of India revealed that 27.5% of the samples showed the presence of dual infection of BTV and PPRV. Analysis of Seg-2 of BTV (the serotype-determining protein) showed the presence of BTV-12w in several isolates. However, analysis of N gene fragment amplicons showed that viruses belong to lineage IV were most closely related to a pathogenic strain of PPRV from Delhi. This is the first report of co-circulation of PPRV lineage IV and bluetongue virus serotype 12 in the state.

Localization of radiolabeled monoclonal antibody in a human soft tissue sarcoma xenograft.

125I-labeled monoclonal antibody 19-24 (mouse isotype IgG1) was evaluated for its potential usefulness in the clinical radioimmunodetection of sarcoma. The antibody reacts with a cell surface antigen preferentially expressed in many human soft tissue and bone sarcomas. Chromatographic and electrophoretic analyses indicated that the labeled preparation was relatively pure. Binding studies in vitro demonstrated that specificity for antigen was retained after iodination and indicated that the labeled antibody possessed an immunoreactivity in excess of 90% and a binding constant of 8.1 X 10(9) M-1. When administered to athymic NCr-nu/nu mice bearing 1-cm diameter human fibrosarcoma HT-1080 xenografts, the labeled antibody preferentially localized in tumor deposits. Maximum tumor-to-blood radioactivity ratios (2.2-3.4) were obtained 7 days after antibody injection. Specificity of the localization was confirmed with a control mouse IgG1 antibody and by using a nonreactive xenograft. Distinct tumor images were obtained by gamma camera without the use of subtraction techniques, demonstrating the possible clinical utility of the labeled antibody.

The use of daunomycin-antibody immunoconjugates in managing soft tissue sarcomas: nude mouse xenograft model.

Analysis of human fibrosarcoma cells exposed to radiolabeled monoclonal antibody 19-24, which recognizes sarcoma-associated antigen p102, revealed that over 54% of the cell surface-bound radioactivity was internalized. No modulation of cell surface p102 antigen by monoclonal antibody 19-24 was observed in human fibrosarcoma cells. Monoclonal antibody 19-24 coupled to daunomycin via a dextran bridge was found to be most effective. In different preparations, the daunomycin:total protein molar ratio ranged from 1.9 to 6.1. In vitro cytotoxicity studies using human fibrosarcoma cells showed that, at 10 micrograms/ml concentration, this immunoconjugate was 79.4% as efficient as free daunomycin and, at 1 microgram/ml concentration, 36.8% as efficient. Control nonspecific murine monoclonal antibody P3 immunoconjugates were relatively ineffective. The distribution of 14C-Adriamycin, 125I-labeled monoclonal antibody 19-24, and 125I-labeled 19-24 immunoconjugate was also evaluated over a 24-h period in tumor and normal tissues of athymic mice bearing a human fibrosarcoma xenograft. Poor uptake of radiolabeled Adriamycin by the tumor tissue was observed. The level of 14C radioactivity in the tumor tissue never exceeded 1% of the total injected dose and was 24.8-fold lower than the radioactivity found in the spleen tissue. Tumor tissue uptake of radiolabeled monoclonal antibody 19-24 was characterized by the high tumor tissue:blood ratio of 1.62 +/- 0.28 (SD). However, for monoclonal antibody 19-24 immunoconjugates, this ratio decreased to 0.66 +/- 0.05, which was still higher than normal (liver, 0.48 +/- 0.02; lung, 0.48 +/- 0.07; spleen, 0.28 +/- 0.01) or nonspecific monoclonal antibody P3 immunoconjugates (0.22 +/- 0.03). Thus, it appears that, compared to free daunomycin, monoclonal antibody 19-24 immunoconjugates may be more efficient and less cytotoxic to normal tissues.

Effects of glucocorticoids on the growth of human fibrosarcoma cell line HT-1080.

The human fibrosarcoma cell line HT-1080 exhibits rapid growth following s.c. inoculation in 4-6-week-old male athymic mice. Cytosols from tumors carried in athymic mice bind glucocorticoid (Kd, 1.8 +/- 0.48 X 10(-8) M; Bmax, 240.5 +/- 35.3 fmol/mg cytosol protein, mean +/- SEM). Receptor sediments primarily in the 8-9S region on 5-20% sucrose gradients and is specific for the glucocorticoids. HT-1080 growth in vitro (as measured by cell count) was inhibited over a range of 10(-6)-10(-8) M after 7 days of incubation with dexamethasone and triamcinolone acetonide. Progesterone, estradiol, and dihydrotestosterone had no effect on HT-1080 growth in vitro. Preincubation with a 100-fold excess of progesterone reversed the growth inhibition observed with triamcinolone acetonide but not dexamethasone acetate. HT-1080 tumor cell growth responded biphasically to dexamethasone in vivo. Athymic mice given s.c. injections every other day with 5 or 25 micrograms dexamethasone showed an increase in tumor size inversely proportional to dose. In contrast, 200 micrograms of dexamethasone significantly inhibited tumor growth. Adrenalectomy did not significantly alter HT-1080 growth or glucocorticoid binding to tumor cytosols (Kd, 3.4 X 10(-8) +/- 1.1, Bmax, 236.9 +/- 9.9 fmol/mg cytosol protein, mean +/- SEM) although tumor incidence was decreased in sham adrenalectomized mice. Glucocorticoid binding in tumors grown in vivo was decreased by increasing amounts of dexamethasone. High pharmacological doses of glucocorticoids inhibit the growth of human fibrosarcomas in vivo and in vitro.

Biological behavior of MM1 hamster melanoma.

We have reported evidence recently for a high-affinity receptor for glucocorticoid Malignant Melanoma No. 1 hamster melanoma and suggested that tumor growth was facilitated by adrenal steroids. This report characterizes the behavior of Malignant Melanoma No. 1 following manipulation of the pituitary-adrenal axis in vivo. Bilateral adrenalectomy significantly retarded tumor growth. Hypophysectomy also significantly reduced tumor growth. Silastic implants of hydrocortisone in intact hamsters produced a dose (7 to 28 micrograms/day)-related increase in tumor growth. Implants releasing a low dose (3 micrograms/day) of dexamethasone also increased tumor growth. Chronic exposure of adrenalectomized and intact hamsters to a high dose (125 micrograms/day) of desoxycorticosterone acetate also produced a significant increase over adrenalectomized and sham-adrenalectomized controls. In contrast, chronic administration of adrenocorticotropic hormone and alpha-melanocyte-stimulating hormone to intact hamsters did not significantly alter melanoma growth. These observations support the suggestion that adrenocorticosteroids influence the growth of Malignant Melanoma No. 1 hamster melanoma and provide a model for studying the regulation of growth of a glucocorticoid-positive neoplasm originating outside the reticuloendothelial system.

Influence of the estrous cycle during carcinogen exposure on nitrosomethylurea-induced rat mammary carcinoma.

The influence of individual stages of the rat estrous cycle during exposure to I-nitroso-I-methylurea (NMU) on mammary tumor incidence, latency, number, and cytosol receptor dynamics for estrogen and progesterone was determined. Virgin female Buffalo rats were separated into three groups on Day 53 according to their vaginal smear pattern. NMU (5 mg/100 g body weight, i.v.) was administered in three monthly doses beginning at 53 to 55 days of age on diestrus, proestrus, or estrus between 9:00 and 11:00 a.m. Groups of rats had their second and third injections of NMU on the same day of the estrous cycle as their initial injection. All animals were killed during the morning on a diestrus day. Receptors for estrogen and progesterone were determined by a modified dextran-coated charcoal method and by sucrose density gradient analysis. Mean latencies to first tumor appearance in diestrus, proestrus, and estrus groups were 104.4, 83.6, and 91.4 days, respectively (p less than 0.05, diestrus versus estrus and proestrus) following the first NMU injection. The mean number of tumors per rat was significantly higher in rats injected on proestrus (4.5) or estrus (4.3) than on diestrus (2.0). Estradiol bound to receptor sedimented at 8 and 4 s and was suppressed by diethylstilbestrol and estradiol. Progesterone receptor migrated to 7.8 and 4 s regions. Estrogen receptor incidence (100%) and content (16.7 fmol/mg cytosol protein) was highest in rats injected on diestrus. In the proestrus and estrus injected groups, estrogen receptor incidence was 95 and 63% and content was 10.2 and 11.2 fmol/mg protein, respectively. The affinity of estradiol for its receptor was not significantly altered in any group. Although there were no statistically significant difference in progesterone receptor incidence or affinity between groups, progesterone receptor content (74.6 fmol/mg cytosol protein) was significantly higher in tumors from rats injected on proestrus than on diestrus. These data suggest that the prevailing hormonal milieu of the estrous cycle during NMU exposure may be critically important to the subsequent biological behavior and steroid receptor status of carcinogen-induced rat mammary tumors.

Histochemical and ultrastructural study of lactic dehydrogenase in chemically induced lung cancer.

Light and electron microscopy studies of lactic dehydrogenase activity were carried out in embryonic, neonatal, and adult mouse lungs and in lungs undergoing chemically induced carcinogenesis. Embryonic mouse lungs were collected on the 6th, 12th, and 18th days of gestation; 1-day-old lungs were used for the neonatal model. These were compared with adult normal mouse lung and lungs of the animals treated with 4-nitroquinoline 1-oxide at a monthly interval until cancer developed. Enzymatic activity was seen in the embryonic, precancerous, and malignant lung tissues and was found diffusely in the cytoplasm of the epithelial cells.

Monoclonal antibody identification and characterization of two human sarcoma-associated antigens.

Two murine monoclonal antibodies, 29-13 (IgG1) and 29-2 (IgG2a), generated against malignant fibrous histiocytoma plasma membranes immunoprecipitated a Mr 200,000 protein (p200), with an isoelectric point between 6.3 and 7.5. Two additional antibodies, 35-16 (IgG1) and 30-40 (IgG2a), generated against Ewing's sarcoma membranes, immunoprecipitated an acidic protein of Mr 160,000 (p160), with an isoelectric point between 5.8 and 6.7. Monoclonal antibodies 29-13 and 29-2 recognize a similar determinant(s) on p200 while 35-16 and 30-40 recognize different determinants on p160. Monoclonal antibody 29-13 exhibited significant binding to membranes isolated from fibrosarcoma and aggressive fibromatosis; moderate binding to osteosarcoma, hemangiopericytoma, and malignant fibrous histiocytoma; and minimal to no binding to other soft tissue sarcoma plasma membranes. The p200 protein was not expressed in 16 other malignant tumors and in only 3 of 35 normal human tissue specimens. High levels of p200 were selectively expressed by leiomyosarcoma, Ewing's sarcoma, and fibrosarcoma cells as well as neonatal fibroblasts in vitro, but not by other carcinoma cell lines or B-lymphoblasts. The p160 protein appeared to be selectively expressed by Ewing's sarcoma with little or no expression on other sarcomas, carcinomas, or normal tissues. However, the p160 antigen was expressed in Ewing's sarcoma, leiomyosarcoma, melanoma, 4 of 9 carcinomas, and neonatal fibroblasts in vitro. The affinity of MoAbs 29-13, 29-2, 35-16, and 30-40 ranged from 5.3 x 10(8) to 4.7 x 10(9) M-1 for sarcoma membranes with approximately 5 x 10(4) binding sites/sarcoma cell.

Effect of 17 beta-estradiol on the growth of estrogen receptor-positive human melanoma in vitro and in athymic mice.

Physiochemical properties of an estrogen binding protein were characterized in three human melanoma cell lines, UISO-MEL-1, UISO-MEL-2, and UISO-MEL-4. Estrogen binding to melanoma cytosol was saturable, specific for estrogens, and represented by a single class of high-affinity, limited-capacity binding sites (Kd 5.5 x 10(-10) M, 2.7 +/- 0.5 fmol/mg of cytosol protein, UISO-MEL-2; 2.2 x 10(-10) M, 7.8 +/- 3.3, UISO-MEL-4) (SEM). UISO-MEL-1 cytosols did not bind estradiol. The binding protein in UISO-MEL-2 and -4 sedimented at 8.5S and 9.2S, respectively, in the presence of 10 mM sodium molybdate. Solid-phase radioimmunoassay with a monoclonal antibody specific for human estrogen receptor (H222 sp lambda) showed good correlation (r = 0.84) with a hydroxyapatite biochemical assay of identical melanoma cytosols. Exposure of UISO-MEL-2 to estradiol produced a time- and temperature-dependent increase in total nuclear receptor for estrogen in vitro. Estradiol treatment of athymic mice also significantly increased cytosol progesterone receptor content in UISO-MEL-2 and UISO-MEL-4 xenografts. Estradiol had no effect on the plating efficiency or growth of any melanoma cell line or normal melanocytes in vitro. Tamoxifen also had no effect on melanoma growth in vitro. In contrast, chronic exposure of athymic mice carrying estrogen receptor-positive UISO-MEL-2 to estradiol resulted in a sex-dependent increase in tumor latency and overall inhibition of tumor growth. Taken together, these observations suggest that a subset of human melanomas contains limited amounts of an estrogen binding protein similar to that observed in other estrogen-responsive tissues. The lack of effect of estradiol on melanocyte and melanoma growth in vitro, coupled with a decrease in tumor growth in athymic mice, suggests that, while inhibition may be receptor mediated, possible indirect actions of estradiol must also be considered.

Micropthalmia transcription factor: a new prognostic marker in intermediate-thickness cutaneous malignant melanoma.

Micropthalmia transcription factor (Mitf) is involved in melanocyte development and differentiation. The current study was undertaken to determine whether there is a relationship between Mitf expression and survival in patients with intermediate-thickness (1.0-4.0 mm) melanoma. Original paraffin blocks or slides of the primary tumor were accessible in 63 such patients. Mitf expression was evaluated by immunocytochemistry and analyzed visually. Slides were graded as follows according to the percentage of cells whose nuclei stained positive for Mitf: (a) 0, 0%; (b) +1, 1-25%; (c) +2, 26-50%; (d) +3, 51-75%; and (e) +4, > 75%. Median follow-up was 50 months. Mean thickness was 2.2 +/- 0.7 mm. Mean overall survival was 171.90 +/- 13.12 months. Mean disease-free survival was 168.53 +/- 13.96 months. Fifty-two melanomas (82.5%) stained positive for Mitf. By univariate analysis, mean overall survival and disease-free survival in patients whose melanomas did not express Mitf were 80.89 +/- 17.98 months (median, 51 months) and 71.36 +/- 19.87 months (median, 40 months), respectively. This compares with 187.90 +/- 13.41 months (median, not reached) and 186.78 +/- 13.84 months (median, not reached), respectively, for patients whose melanomas expressed Mitf (P = 0.0086 and P = 0.0054). These findings persisted in multivariate analysis. In addition, patients with > 50% Mitf expression had significantly fewer nodal metastases after node dissection than patients with < or = 50% Mitf expression (P = 0.04). Our data suggest that Mitf may be a new molecular prognostic marker in patients with intermediate-thickness melanoma.

Presence of steroid receptors in human soft tissue sarcomas of diverse histological origin.

The incidence of cytosol receptors for androgen, estrogen, glucocorticoid, and progesterone was determined in a series of histologically diverse soft tissue sarcomas. Receptor binding was characterized in tumor specimens from 29 adult patients (14 female, 15 male) obtained during surgery. Nineteen (66%) tumor cytosols bound at least one steroid. Seven (24%) had more than one receptor. Ten of 23 (43%) cytosols assayed for androgen binding were positive (Kd 0.97 +/- 0.23 X 10(-9) M; 60.6 +/- 25.9 fmol/mg protein), 7 of 29 (24%) for estrogen (Kd 1.00 +/- 0.19 X 10(-9) M; 33.2 +/- 10.9 fmol/mg protein), 9 of 26 (35%) bound glucocorticoid (Kd 4.22 +/- 1.77 X 10(-9) M; 231.0 +/- 155.0 fmol/mg protein), and 1 of 28 (4%) bound progesterone (Kd 0.41 X 10(-9) M; 18.7 fmol/mg protein). Density gradient analysis suggested that androgen and estrogen binding was located predominantly in the 6S and 7 to 8S regions, respectively, whereas receptor for glucocorticoid sedimented at 8S. Steroid binding was not related to patient age. Estrogen-positive (71%) and glucocorticoid-positive (78%) cytosols appeared predominantly in tumors from female patients. Receptor distribution also appeared to be correlated to tumor histogenetic origin.

Pharmacokinetics of melphalan in clinical isolation perfusion of the extremities.

The pharmacokinetics of melphalan in clinical hyperthermic isolation perfusion was studied in 16 patients with malignant melanoma. Analysis by computer-generated lines of best fit showed that the loss of melphalan from perfusate conforms best to a biexponential equation. The initial loss with a half-life (t1/2) of approximately 5 to 10 min is interpreted as rapid uptake of melphalan by the tissue of the perfused extremity. The terminal portion of the curve with a half-life of approximately 35 to 50 min is interpreted as due predominantly to the hydrolysis of melphalan, with a lesser component of loss due to absorption of melphalan to the filters and tubing of the perfusion apparatus. Determination of the area under the curve suggests that there is no appreciable uptake of melphalan by the tissue of the perfused extremity after 30 min.

Differential proliferative response to linoleate in cultures of epithelial cells from normal human breast and fibroadenomas.

Human breast epithelial cells isolated from normal breast tissues of premenopausal women demonstrated direct evidence of a proliferative effect by linoleate (18:2 omega 6) or prostaglandin E2 (PGE2) in the presence of insulin and epidermal growth factor in serum-free cultures within a collagen gel matrix. Neither epidermal growth factor nor 18:2 omega 6 by itself was capable of stimulating growth but together they stimulated proliferation synergistically. Epithelial cells isolated from fibroadenomas on the other hand failed to exhibit any growth stimulation due to 18:2 omega 6 or PGE2. The linoleate-stimulated growth in normal breast epithelial cells was inhibited by indomethacin, a cyclooxygenase inhibitor, which however could be reversed by PGE2. The proliferative response of normal breast epithelial cells to 18:2 omega 6 was accompanied by a greater conversion of [14C]18:2 omega 6 to arachidonic acid and [14C]20:4 omega 6 to prostaglandins than that seen in epithelial cells from fibroadenomas. The turnover of [14C]18:2 omega 6 in the phospholipids of normal cells was higher than in fibroadenomas indicating a possible role of phospholipids in mediating the 18:2 omega 6 effect in normal cells. Both normal and fibroadenoma cells can proliferate in response to cholera toxin and glucocorticoids when supplemented to the insulin- and epidermal growth factor-containing medium. From the results it appears that, unlike normal cells, fibroadenoma cells may have a specific defect in the PGE2-responsive cyclic AMP-generating mechanism whereas cholera toxin-induced mechanism is operative in both types of cells.