Biomedical subjects
M J Kennedy
Publications and source records attributed to M J Kennedy.
Differential effects of bryostatin 1 and phorbol ester on human breast cancer cell lines.
The effects of the protein kinase C (PKC) activators, phorbol ester 12-O-tetradecanoyl-13-phorbol acetate (TPA) and the marine natural product, bryostatin 1, on the growth and morphology of human breast cancer cell lines were examined. TPA (1 to 100 nM) inhibited growth of four of six cell lines by up to 75% in 5-day cultures. Bryostatin 1 inhibited growth of only MCF-7 cells and only at a high dose (100 nM). However, bryostatin 1 completely antagonized the growth inhibition and morphological changes induced by TPA in MCF-7 cells. The divergent effects of these two agents are associated with differing effects on PKC activity and isoform expression in MCF-7 cells. TPA induced rapid translocation of the PKC-alpha isozyme and PKC activity to the membrane fraction of MCF-7 cells. In contrast, bryostatin 1 treatment resulted in the loss of the PKC-alpha isozyme and PKC activity from both cytosolic and membrane compartments within 10 min of treatment. In coincubation assays the bryostatin 1 effect was dominant over that of TPA. Similar effects on PKC-alpha isozyme and PKC activity were seen in a second cell line whose growth was inhibited by TPA but not by bryostatin 1, MDA-MB-468. In contrast, in the T47D cell line, where TPA was not growth inhibitory, TPA failed to induce translocation of PKC-alpha to the cell membrane. Bryostatin, however, still caused loss of PKC-alpha isozyme and PKC activity from cytosolic and membrane fractions. Thus, differential actions of bryostatin 1 and TPA on PKC activity and alpha-isoform level in the membrane-associated fraction of MCF-7 and MDA-MB-468 cells may account for the divergent effects of these two agents on cell growth and morphology. These results suggest that the PKC-alpha isoform may specifically play a role in inhibiting growth of human breast cancer cells.
The efficacy of ivermectin against the eyeworm, Thelazia skrjabini, in experimentally infected cattle.
The anthelmintic efficacy of ivermectin (administered subcutaneously at 200 micrograms kg-1 body weight) was assessed for control of Thelazia skrjabini in experimentally infected calves. Twenty-four uninfected male Holstein calves, 1-2 weeks old, were artificially infected with Thelazia skrjabini by placing 15 third-stage larvae under the third eyelid of calves. The challenge larvae were recovered from naturally infected face flies, Musca autumnalis. The exposed calves were randomly assigned to either an ivermectin treatment group or a control group within pairs ranked by weight. Equal numbers of calves were housed in each of four indoor fly-free rooms. The calves were treated with ivermectin or saline 35 days post-infection, then slaughtered 14 days later to determine eyeworm numbers. All eyes and associated tissues (including the lacrimal glands and ducts) were removed and examined for total number, species and viability of eyeworms. Thelazia skrjabini was found in the control group of calves only. The efficacy of ivermectin against Thelazia skrjabini was thus shown to be 100%.
Virulence and adhesive properties of serotypes A and B of Candida albicans isolated from paediatric burn patients.
The virulence and adhesive properties of 50 isolates of Candida albicans serotypes A and B collected over 6 years from 48 paediatric burn patients were examined to provide more detailed information about candidal pathogenesis in burn patients and to examine the relevance of the commonly used epithelial cell adhesion assay for determining fungal virulence. The isolates represented a fair distribution of serotypes (29 isolates were serotype A and 21 isolates were serotype B) and a total of 28 serotype-biotype combinations were found; 32% of the serotype-biotype combinations appeared only once, while 44% of the isolates showed similar biotype tests for two of three digits. Adhesion of the isolates to plastic and to buccal epithelial cells (BECs) was examined and compared after growth in a chemically defined medium. There were significant differences in the adhesion of individual isolates to plastic or BECs, but no correlation was found between biotype and adhesiveness. Serotype B isolates were found to be more adhesive to BECs (p less than 0.05) but not to plastic. There was no apparent correlation between candidal adhesiveness and site of isolation from these patients (autografts, blood, faeces, throat swabs, tracheal aspirates, wounds and intravenous catheters), although isolates from catheters were generally less adhesive to epithelial cells. Virulence in a systemic infection mouse model revealed that there were significant differences in virulence between isolates, but no correlation was found between virulence and the biotype, serotype or site of isolation. Similarly, no correlation was found between virulence and adhesiveness or cell-surface hydrophobicity.(ABSTRACT TRUNCATED AT 250 WORDS)
Dose intensive therapy in breast cancer.
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GMO regulations in New Zealand for large scale fermentations.
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Molecular basis of Candida albicans adhesion.
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High-dose chemotherapy with reinfusion of purged autologous bone marrow following dose-intense induction as initial therapy for metastatic breast cancer.
We assessed the toxicity and efficacy of high-dose chemotherapy consolidation with reinfusion of purged autologous bone marrow in women with metastatic breast cancer responding to a dose-intense outpatient regimen. Thirty women with hormone-unresponsive metastatic breast cancer, previously untreated with adjuvant doxorubicin or with any chemotherapy for metastatic disease, were treated with cyclophosphamide, methotrexate, doxorubicin, fluorouracil, vincristine, and leucovorin for 16 weeks. Twenty-four patients responded to therapy; 8 showed a complete response, and 16 showed a partial response. These patients proceeded to the next phase of the protocol, ie, marrow harvest and treatment with 6000 mg/m2 cyclophosphamide and 800 mg/m2 thiotepa given over 4 days. Harvested marrow was purged with 100 micrograms/mL 4-hydroperoxycyclophosphamide, and all patients engrafted satisfactorily. The predominant side effects were myelosuppressive and gastrointestinal, and there were no deaths from toxic effects. Three of the 16 patients who showed a partial response after the outpatient phase of treatment achieved a complete response after high-dose therapy. The partial response seen in two more patients converted to a complete response at all sites except bone. The median time to disease progression for all patients in this study was 13 months, and the median survival was 22 months. Four of the original 30 patients remained without disease progression a median of 27 months from entry into the study. This study indicates that this dose-intense regimen can be safely administered, even with the use of purged marrow, with an acceptable toxicity profile. This approach results in a high response rate in women with metastatic breast cancer and could form the basis for a regimen to be tested in the high-risk adjuvant setting.
Exogenous C1q reconstitutes a secondary deficiency of C5-deficient AKR mouse macrophages for FcR-dependent cellular cytotoxicity and phagocytosis.
Studies originally designed to assess the putative role of endogenous C5 in macrophage activation for antibody-dependent cellular cytotoxicity (ADCC) yielded unanticipated results. Resident and inflammatory peritoneal macrophages from C5-deficient AKR mice were found to have significantly lower capacity for FcR-dependent ADCC activation and phagocytosis of IgG-opsonized SRBC targets than did C5-competent C3HeB/FeJ (C3H) mice. Reconstitution of the ADCC response of AKR macrophages was accomplished initially with C5-sufficient C3H mouse serum, which suggested that endogenous C5 may be required for ADCC activation. However, further investigation largely eliminated C5 involvement in that a heat-labile component of C5-deficient AKR serum was shown to be active in the reconstitution of ADCC activation of AKR macrophages. Macrophages from AKR mice were found to have significantly lower levels of C1q mRNA synthesis, endogenous C1q levels, and C1q secretion than did C3H mouse macrophages as determined by Northern blot, Western blot, and presynthetic radiolabeling analysis, respectively. The addition of purified exogenous C1q to IgG-opsonized SRBC targets fully reconstituted ADCC activation for AKR inflammatory peritoneal macrophages to levels of normally FcR-responsive C3H macrophages. Similarly, exogenous C1q augmented FcR-dependent phagocytosis of AKR macrophages but had no effect on macrophages from responsive C3H mice. Our results indicate that AKR mice have a deficiency for FcR-dependent cellular cytotoxicity and phagocytosis that is related to their low potential for C1q synthesis and secretion rather than to their established genetic deficiency for C5 synthesis. We tentatively conclude that endogenous C1q is required as an accessory molecule for macrophage FcR-dependent effector functions and that C5 is not a prerequisite for ADCC activation.
The evolution of the word 'biotechnology'.
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An environmental assessment of biotechnological processes.
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Staphylococcal exotoxins stimulate nitric oxide-dependent murine macrophage tumoricidal activity.
The staphylococcal exotoxins toxic shock syndrome toxin 1 (TSST-1) and enterotoxin B were tested for their ability to stimulate murine peritoneal macrophages (PM) for tumoricidal activity. Both toxins were found to stimulate oil-elicited, gamma interferon-primed PM monolayers to kill nonadherent P815 tumor targets. The mechanism of killing of toxin-stimulated tumoricidal activity involved the production of nitric oxide, as nitrite could be demonstrated in culture fluids, and NG-monomethyl-L-arginine, an inhibitor of nitric oxide production, abrogated toxin-stimulated tumoricidal activity. TSST-1 stimulated the secretion of tumor necrosis factor by PM monolayers in the presence and absence of gamma interferon. The mechanism of toxin-stimulated tumoricidal activity was also determined to be independent of the production of reactive oxygen intermediates in that TSST-1 failed to stimulate H2O2 production by PM. These results demonstrate that the staphylococcal exotoxins are capable of stimulating macrophage production of nitric oxide for tumor cytotoxicity and suggest that the nitric oxide thus produced may subsequently play a role in the pathogenesis of the diseases caused by these toxins.
Opportunities in New Zealand for biotechnology process development and contract research. The Biotechnology Group of DSIR Industrial Development, New Zealand.
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Development of the nematode eyeworm, Thelazia skrjabini (Nematoda: Thelazioidea), in experimentally infected face flies, Musca autumnalis (Diptera: Muscidae).
The development of Thelazia skrjabini Erschow, 1928, was studied in experimentally infected laboratory-reared Musca autumnalis De Geer. Thelazia skrjabini developed to the infective third stage in a minimum of 9 days in M. autumnalis maintained at 27 +/- 2 C. First-stage larvae were not observed postinoculation, but second-stage larvae were first observed 3 days postinoculation. Development was asynchronous. Second- and third-stage larvae occur in capsules, occasionally in the head but primarily in the abdomen attached to fat bodies. First-stage larvae have anteriorly 1 ventral and 2 dorsal hooks, directed posteriorly. Second-stage larvae have 4 submedian cephalic papillae and faint annular striations. Third-stage larvae have 6 labial papillae, 4 submedian cephalic papillae and pronounced annulations. Morphometric studies of each larval stage were performed with specimens in glycerine.
Phase II trial of menogaril as initial chemotherapy for metastatic breast cancer.
Eighteen women with metastatic breast cancer previously untreated with chemotherapy were entered on a phase II trial of intravenous menogaril, a new anthracycline derivative. Treatment was given at 140 mg/m2 on days 1 and 8 of each 28 day cycle. The most common toxicities were leukopenia in all patients and burning and phlebitis at infusion sites in 72%. Serial assessment of cardiac function by resting and stress gated blood pool scans showed temporary decrements in ejection fraction in only 2 patients (11%). The response rate to the therapy was 19% [95% CI 0-38%] including 1 complete and 2 partial responses. The median time to relapse among responders was 6.5 months. Mean survival in all patients entered was 15.8 months from date of entry. Menogaril at this dose and schedule has modest activity as first line therapy for metastatic breast cancer but also has significant marrow and local toxicity.
Models for studying the role of fungal attachment in colonization and pathogenesis.
Fungal adhesion and aggregation is considered an important event in human, animal and plant disease as well as in the ecology of fungi in nature (e.g., in mating reactions and the dispersion of fungal propagules). Because of this, numerous models have been developed to study fungal adhesion and aggregation mechanisms over the last decade. Unfortunately, however, nearly all of the work in this area has been carried out in simple in vitro models and has focused its attention on that of the attachment process alone, while realitively little effort has been made toward understanding the role adhesion and aggregation plays in colonization or pathogenesis. The emphasis on adhesion and aggregation mechanisms appears, therefore, to have somewhat obscured the study of the interaction of adhesion with other factors that may be of equal or greater importance in these processes and to the development of more complex adhesion models to explore the relationship between adhesion and colonization. Moreover, because it has not generally been appreciated that several methodologic pitfalls accompany the use of simple in vitro adhesion models, there is now emerging a confused literature base with regard to: (i) the nature of the cell wall component(s) of Candida albicans that mediates its attachment to, for example, epithelial cells; (ii) the mechanism(s) of invasion of mucosal and endothelial surfaces; and (iii) the role certain adhesive reactions observed in vitro play in colonization and pathogenesis by this fungus. Therefore, with an emphasis on C. albicans, this paper will attempt to put into perspective the uses and limitations of models for studying the role of fungal attachment in colonization and pathogenesis. In addition, factors that can modify fungal adhesion data will be discussed and the beginnings of a standardized assay to study the adhesion of C. albicans to buccal epithelial cells will be described.
Uptake and distribution of lidocaine in fetal lambs.
The fetal uptake of lidocaine was measured continually and quantitatively during and after a constant rate intravenous (iv) maternal infusion into five chronically prepared pregnant ewes. Lidocaine, 6 mg/kg (base), was infused at a constant rate for 1 h and measurements continued to 5 h. Rate of fetal uptake was determined from the product of the umbilical venous (UV) and fetal aortic (FA) concentration difference and umbilical blood flow (Qu). Total fetal uptake was determined by integrating fetal uptake rate with respect to time. Maternal and fetal protein binding was determined, and its effect on fetal blood concentrations was evaluated. Mean total fetal uptake as it related to time and infused dose increased linearly (r = 0.998, P less than 0.001) with a constant, weight-normalized fetal-maternal dose fraction of 0.45 during the infusion. Despite rapidly declining blood concentrations after the infusion, uptake increased an additional 17%. The sevenfold variation in uptake appeared to be inversely related to the biodegradation rate of lidocaine. Fetal-maternal concentration ratios (F/M) increased during declining blood concentrations. Protein binding determinations for maternal and fetal blood were 43.6 +/- 2.48% and 26.9 +/- 1.59%, respectively. These values were used to calculate the F/M in conjunction with the maternal and fetal pH. At maternal-fetal equilibrium the calculated F/M, 1.0 +/- 0.05, closely approximated the observed, 1.0 +/- 0.03. Variations in lidocaine concentrations among the vital organs 4 h after the infusion were small, but high concentrations of metabolites were found in the lungs and kidneys. The results challenge the validity of placental transfer estimates commonly based on the F/M and umbilical cord blood concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
A study on the prevalence and intensity of occurrence of Thelazia skrjabini (Nematoda: Thelazioidea) in cattle in central Alberta, Canada.
The distribution of Thelazia skrjabini in the eyes of cattle was examined from necropsies on 297 animals. Although the overall prevalence in beef cattle (21.5%) was similar to that in dairy cattle (25.7%), in general worms were more abundant in beef than in dairy animals. The worm prevalence was lowest in the months from March to June and highest in September among beef and dairy animals. Thelazia skrjabini was found in 76 (16.8%) eyes from beef, and 23 (16.4%) eyes from dairy cattle. Infections were not randomly distributed among the eyes of cattle. Significantly more dairy and beef cattle contained T. skrjabini in both eyes than expected based on the observed prevalences. Based on chi-square probabilities, significantly more cattle more than 2 yr of age and less than 10 mo of age were infected with T. skrjabini. Although all age groups were infected, more worms were observed in cattle more than 2 yr of age. More female worms than males were collected from cattle. The male-to-female ratio of 1:2 was consistent regardless of cattle age, season, or type.