Acute metabolic alkalosis enhances response of C3H mouse mammary tumors to the weak base mitoxantrone.

Uptake of weak acid and weak base chemotherapeutic drugs by tumors is greatly influenced by the tumor extracellular/interstitial pH (pH(e)), the intracellular pH (pH(i)) maintained by the tumor cells, and by the ionization properties of the drug itself. The acid-outside plasmalemmal pH gradient in tumors acts to exclude weak base drugs like the anthracyclines, anthraquinones, and vinca alkaloids from the cells, leading to a substantial degree of "physiological drug resistance" in tumors. We have induced acute metabolic alkalosis in C3H tumor-bearing C3H/hen mice, by gavage and by intraperitoneal (i.p.) administration of NaHCO(3). (31)P magnetic resonance spectroscopic measurements of 3-aminopropylphosphonate show increases of up to 0.6 pH units in tumor pH(e), and 0.2 to 0.3 pH units in hind leg tissue pH(e), within 2 hours of i.p. administration of NaHCO(3). Theoretical calculations of mitoxantrone uptake into tumor and normal (hind leg) tissue at the measured pH(e) and pH(i) values indicate that a gain in therapeutic index of up to 3.3-fold is possible with NaHCO(3) pretreatment. Treatment of C3H tumor-bearing mice with 12 mg/kg mitoxantrone resulted in a tumor growth delay of 9 days, whereas combined NaHCO(3)--mitoxantrone therapy resulted in an enhancement of the TGD to 16 days.

Enhancement of chemotherapy by manipulation of tumour pH.

The extracellular (interstitial) pH (pHe) of solid tumours is significantly more acidic compared to normal tissues. In-vitro, low pH reduces the uptake of weakly basic chemotherapeutic drugs and, hence, reduces their cytotoxicity. This phenomenon has been postulated to contribute to a 'physiological' resistance to weakly basic drugs in vivo. Doxorubicin is a weak base chemotherapeutic agent that is commonly used in combination chemotherapy to clinically treat breast cancers. This report demonstrates that MCF-7 human breast cancer cells in vitro are more susceptible to doxorubicin toxicity at pH 7.4, compared to pH 6.8. Furthermore 31P-magnetic resonance spectroscopy (MRS) has shown that the pHe of MCF-7 human breast cancer xenografts can be effectively and significantly raised with sodium bicarbonate in drinking water. The bicarbonate-induced extracellular alkalinization leads to significant improvements in the therapeutic effectiveness of doxorubicin against MCF-7 xenografts in vivo. Although physiological resistance to weakly basic chemotherapeutics is well-documented in vitro and in theory, these data represent the first in vivo demonstration of this important phenomenon.

Plasmalemmal pH-gradients in drug-sensitive and drug-resistant MCF-7 human breast carcinoma xenografts measured by 31P magnetic resonance spectroscopy.

31p Magnetic resonance spectroscopy (MRS) was employed to investigate tumor pH in xenografts of drug-sensitive and drug-resistant MCF-7 human breast carcinoma cells. Measured extracellular pH values were found to be lower than the intracellular pH in all three tumor types investigated. The magnitude of this acid-outside plasmalemmal pH gradient increased with increasing tumor size in tumors of two drug-resistant variants of MCF-7 cells, but not in tumors of the parent (drug-sensitive) cells. The partitioning of weak-base or weak-acid drug molecules across the plasma membrane of a tumor cell is dependent upon the acid-dissociation constant (pKa) of the drug as well as the plasmalemmal pH gradient. A large acid-outside pH gradient, such as those seen in MCF-7 xenografts, can exert a protective effect on the cell from weak-base drugs such as anthracyclines and Vinca alkaloids, which have pKa values of 7.5 to 9.5. The possibility of enhancing the therapeutic efficacy of weak-base drugs by dietary or metabolic manipulation of the extracellular pH, in order to reduce or reverse the plasmalemmal pH gradient, deserves investigation.

Fabrication of high-spatial-frequency gratings through computer-generated near-field holography.

We demonstrate an innovative method for fabrication of high-spatial-frequency grating structures. This technique makes use of the near-field diffraction patterns from computer-generated phase holograms for lithographic fabrication of grating structures with periods that are one half that of the phase hologram mask. Linear, rectilinear, and circular gratings were fabricated with this technique. Experimental results from gratings with periods to 0.5 mum and feature sizes to ~0.2 mum are presented.

Ankle joint dorsiflexion. Establishment of a normal range.

Various values have been proposed as the required amount of ankle joint dorsiflexion, but a normal range has not been established. The authors establish a normal range based on direct measurements and compare the standard nonweightbearing method of measuring ankle joint dorsiflexion with a weightbearing method. The normal range for ankle joint dorsiflexion was established as 0 degrees to 16.5 degrees nonweightbearing and 7.1 degrees to 34.7 degrees weightbearing. A statistically significant (p < 0.01) difference exists between the two measuring systems. In addition, the study shows poor correlation between the two measurements. This lack of correlation brings into question the clinical relevance of the standard nonweightbearing measurement.

Immunological aspects of surgically induced experimental endometriosis: variation in response to therapy.

Elevated endometrial antibody titers were detected in serum and peritoneal fluid of rabbits with experimentally induced endometriosis. Surgical extirpation of implants or suppression with gonadotropin-releasing hormone agonist resulted in decreased endometrial antibody titers, whereas the antibody titers in untreated rabbits with endometriosis increased significantly. Endometrial implants and normal endometrial tissue had similar proteins by polyacrylamide gel electrophoresis. However, the serum and peritoneal fluid from rabbits with experimentally induced endometriosis had gamma G immunoglobulin antibodies to an endometrial protein with molecular weight of approximately 40 kD. These antibodies were absent in rabbits without endometriosis. Isolation of endometrial antigens eliciting the humoral immune response in endometriosis may aid in the development of a specific antibody marker for endometriosis.

Interleukin-1: a possible role in the infertility associated with endometriosis.

Increased numbers of activated macrophages are associated with mild endometriosis. Interleukin-1 (IL-1) is a protein produced by macrophages and is believed to be a primary mediator of host responses. IL-1 induces prostaglandin and fibrinogen synthesis and stimulates fibroblast proliferation. This study was undertaken to evaluate the role of IL-1 in the infertility associated with mild endometriosis. Peritoneal fluid (PF) was obtained at laparoscopy from 11 patients with minimal or mild endometriosis and from 7 women undergoing tubal ligation. Peritoneal macrophages were isolated and cultured for 24 hours. Peritoneal and macrophage culture fluids were studied for IL-1 activity, which was measured with the EL-4 assay. IL-1 activity was present in the PF of 10 of the 11 patients with endometriosis and 11 of the 11 macrophage culture fluids and was absent in the PF and macrophage culture fluid of the tubal ligation patients. The effect of recombinant alpha-IL-1 on the in vitro growth of 2-cell mouse embryos was also studied. IL-1 in concentrations similar to those present in the PF (greater than 1 U/ml) was toxic to mouse embryo development. We conclude that the IL-1 may play a role in the infertility associated with endometriosis.

Effects of contraceptive steroids on serum lipoproteins and cardiovascular disease scrutinized at workshop in Bethesda.

PIP: A 2-day workshop was held at the National Institute of Health during May 1979 in an effort to assess the current status of the interrelationships between high density lipoprotein (HDL) levels and the incidence of ischemic heart disease and to delineate immediate needs for further research aimed at improved steroid contraceptive safety. Review of older and recent data gave little doubt as to the association between lipoprotein patterns and the incidence of heart disease. Less clear was the relationship between lipoprotein patterns and coronary heart disease (CHD) then is the relationship between oral contraceptive (OC) usage and lipoprotein patterns. Workshop participants did provide strong evidence that OC usage can modify these patterns. The final interrelationship discussed was that of OC usage and cardiovascular disease, particularly atherosclerosis. Along with considering the interactions among OCs, serum lipoproteins, and cardiovascular disease by epidemiologic approaches, workshop participants also considered the status of current studies bearing on the mechanisms by which these interactions may be mediated and the status of methodology for evaluating the interactions. During the general discussion at the end of the workshop, participants agreed that the apparent association between HDL levels and the incidence of cardiovascular disease dictates the need for vigorous research. It was agreed that at least some OC pills do lower serum HDL levels.^ieng

Uterine prostaglandin levels following stimulation of the decidual cell reaction: effects of indomethacin and tranylcypromine.

Prostaglandin E (PGE) and F (PGF) levels were measured in mouse uteri at various times after either trauma (hemostat crusing) or oil stimulation of the decidual cell reaction (DCR). The oil induced DCR led to an early increase (within 5 min) in both PGE and PGF levels. Both returned to baseline by 1 h after stimulation. A second peak in PGF levels was observed at 120 min after oil stimulation. This study demonstrates a distinct difference between the pattern of PGE and PGF changes in the uterus following oil stimulation of the DCR. Indomethacin pretreatment completely blocked the oil stimulated DCR as well as all prostaglandin increases following either stimulus. The trauma stimulated DCR was not completely blocked by indomethacin pretreatment. Pretreatment with tranylcypromine, an inhibitor of prostacyclin biosynthesis, did not block the prostaglandin E and F increases, but did block the oil stimulated DCR. These findings suggest that prostacyclin may be an early mediator of the DCR.

Chick-comb fibroblasts. A new strain of cultured cells sensitive to androgens.

An androgen-responsive cell strain of chick-comb fibroblasts has been established in culture. Cells were obtained from combs of 1--2 day old white Leghorn cockerels and cultured in Dulbecco's modified Eagle medium supplemented with 10% fetal calf serum and 6 g/l glucose. The cells required serum but not androgens for growth. In the presence of androgens, growth rate and incorporation of labeled precursors into protein and RNA were markedly increased in exponentially growing cells, but not in confluent cultures. Androgens exerted these stimulatory effects in a dose-dependent fashion. It is concluded that chick-comb fibroblasts, which respond to androgens in vivo, retain this responsiveness when cultured. They furnish a well-defined system of potential value for studies of the molecular mechanisms of androgen action.

Changes in RNA polymerase activity in isolated mouse uterine nuclei during the decidual cell reaction.

The artificially stimulated decidual cell reaction has been used as a model to study changes occurring in the uterus at the time of implantation. Activities of RNA polymerases I, II and III were measured in uterine nuclei isolated from ovariectomized non-primed mice, hormonally primed mice, and hormonally primed mice following stimulation of the decidual cell reaction. Activities of all three RNA polymerases increased following hormonal priming of ovariectomized mice. In nuclei from stimulated uterine horns, activities of RNA polymerases I and III increased 9 h after stimulation of the decidual cell reaction and remained elevated through 21 h. RNA polymerase II activity did not change following stimulation of the decidual cell reaction. These changes in RNA polymerase activities occur at the time of increased histone modifications and may result from changes in the template capacity.