Antibody targeting of CD24 efficiently retards growth and influences cytokine milieu in experimental carcinomas.

BACKGROUND: The targeting of cancer stem cells by monoclonal antibodies offers new options for therapy. CD24 is a glycosylphosphatidylinositol-anchored membrane protein with a small protein core and a high level of glycosylation. It is overexpressed in many human carcinomas and is correlated with poor prognosis. CD24 is a marker for pancreatic and ovarian cancer stem cells, whereas breast cancer stem cells are negative for CD24. In cancer cell lines, changes of CD24 expression can alter cellular properties in vitro and tumour growth in vivo. We have shown before that monotherapy with monoclonal antibody (mAb) SWA11 to CD24 effectively retarded tumour growth in xenotransplanted mice. METHODS: Here, we have investigated in more detail the molecular mechanisms of mAb SWA11 therapeutic effects in A549 lung and SKOV3ip ovarian carcinoma models in scid/beige and CD1 mice, respectively. We focused on anti-proliferative, pro-apoptotic, anti-angiogenic and microenvironmental effects of SWA11 mAb treatment. RESULTS: We find that CD24 targeting is associated with changes in tumour cell proliferation and angiogenesis. The treatment lead to increased infiltration of tumour tissues with immune cells suggesting involvement of ADCC. We found that SWA11 mAb treatment strongly altered the intratumoural cytokine microenvironment. The addition of SWA11 mAb to gemcitabine treatment strongly potentiated its anti-cancer efficacy in A549 lung cancer model. CONCLUSION: Our data demonstrate that targeting of CD24 could be beneficial for the anti-cancer treatment combined with standard chemotherapy regimes.

Citrinin produces acute adverse changes in renal function and ultrastructure in pentobarbital-anesthetized dogs without concomitant reductions in [potassium]plasma.

Citrinin's nephrotoxicity was examined in pentobarbital-anesthetized dogs under conditions that minimized or avoided significant changes in a number of its actions that could indirectly and adversely affect renal function and ultrastructure, such as, (i) major acute reductions in blood pressure and renal blood flow and, (ii) emesis and diarrhea that could lead to dehydration and electrolyte imbalances, especially hypokalemia. Slow intravenous injection of 20 mumol citrinin/kg to pentobarbital-anesthetized dogs did not induce any alterations in renal tissue ultrastructure or in any of the 23 whole blood, plasma or renal function parameters that were monitored over a 6-h post-citrinin period. On the other hand, 80 mumol citrinin/kg produced significant increases in the hematocrit and in the renal excretion rates of protein and glucose; modest reductions were noted in CIN, RBF and excretion rate of inorganic phosphorus. In addition, 80 mumol citrinin/kg induced ultrastructural lesions in the cells of the S2 proximal tubular segment, the thick ascending limb, the distal convoluted tubule and the collecting ducts. The glomeruli, S1 and S3 cells of the proximal tubule and the thin descending and ascending limbs of Henle's loop were unaffected by both citrinin doses. The location and nature of the adverse ultrastructural lesions were most likely the result of the direct actions of citrinin (or a citrinin metabolite) since the effects of citrinin that could lead to indirect adverse renal effects were totally avoided or greatly minimized.

4-Maleimidohippuric acid--a tailor-made, direct, site-specific nephrotoxin: effects on renal function and ultrastructure in pentobarbital-anesthetized dogs.

A model has been proposed to explain at least one of the possible pathways through which a xenobiotic might produce proximal tubule necrosis. The model is formulated on the idea that a compound must possess two structural features: (i) a carboxyl or amino acid moiety that would allow for selective uptake into proximal tubule cells via the strategically located antiluminal membrane-bound organic anion transport system or the luminal membrane-bound amino acid transport system(s), respectively, and (ii) a highly reactive moiety that can directly alkylate proximal tubular components, or a moiety that can be biotransformed within proximal tubular cells to such a substance. In an attempt to validate the proposed structural features as prerequisites for xenobiotic induction of proximal tubular necrosis, a novel compound, 4-maleimidohippuric acid (4-MHA), was synthesized which possesses an anionic group and a reactive moiety. Following the administration of 4-MHA directly into the renal artery of pentobarbital-anesthetized dogs, specific unilateral ultrastructural damage was noted only in the S1 and S2 cell types of the proximal tubule; the most notable renal function changes included proteinuria and glucosuria. Anionic, but non-alkylating, relatives of 4-MHA failed to alter renal function or ultrastructure. The specific proximal tubular toxicity of 4-MHA validates the proposed structural requirements for induction of proximal tubular necrosis.

Substrates for arachidonic acid co-oxidation with peroxidase/hydrogen peroxide. Further evidence for radical intermediates.

We tested the ability of a wide variety of organic compounds, including benzene and phenol derivatives, aromatic amines, pyrazoline derivatives and other non-steroidal anti-inflammatory drugs, to act as cosubstrates during the horseradish peroxidase/hydrogen peroxide-mediated oxygenation of arachidonic acid. Structural requirements for drug activation in our system proved to be an aromatic system and ring substitution by an easily oxidizable group. Complementary substituents modified drug activation. Among the phenol derivatives and aromatic amines we found the meta-substituted compounds to be significantly more effective than their ortho- and para-substituted analogues, indicating the involvement of radical intermediates in this type of reaction. The radical from 1-phenyl 3-methyl 2-pyrazolone(5) was detected by electron paramagnetic resonance spectroscopy. Kinetic studies on this radical were in good accordance with time-dependent measurement of arachidonic acid oxygenation.

The pentobarbital anesthetized dog: an animal model for assessing chemically induced changes in renal function and ultrastructure.

An experimental procedure was devised using the pentobarbital-anesthetized dog that could be used for the comprehensive evaluation of the renal effects of chemicals. After IV or renal arterial administration of 0.9% saline solution (vehicle), 12 renal function determinants were continuously monitored for periods of 2 and 6 hours. At the completion of the 2 or 6 hours of study, the kidneys of a number of dogs (usually between 1 and 7) in each vehicle-treated group were subjected to a modification of the intravascular perfusion-of-fixative technique to evaluate the ultrastructural status of the outer cortical, inner cortical, and outer medullary tissue. The remaining dogs (at least 3) in each vehicle-treated group were given a nonnephrotoxic, but maximally effective, diuretic dose of ethacrynic acid, which enabled an assessment of the functional integrity of the thick ascending limb of Henle's loop. Renal function and glomerular and tubular ultrastructure remained stable in the pentobarbital-anesthetized dog for up to 6 hours after administration of vehicle. Sustained infusion of inulin (included in the procedure to estimate glomerular filtration rate) throughout the duration of the experiments, and pentobarbital anesthesia of various durations did not alter the morphologic status of the canine nephron. The procedure used for the renal perfusion of fixative circumvented any manipulation of the kidneys before fixation and allowed for the acquisition of normal (unaltered) appearing tissue from all areas of the kidneys. The responses of pentobarbital-anesthetized dogs to ethacrynic acid administration were similar when given 2 and 6 hours after the vehicle administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute effects of alkylating agents on canine renal function and ultrastructure: high-dose ethacrynic acid vs. dihydroethacrynic acid and ticrynafen.

Ethacrynic acid (EA) is unique among diuretics in that it is both an avid alkylating agent and is actively secreted by renal proximal tubular cells. EA might therefore be expected to produce detrimental proximal tubular changes at elevated doses. Because of this possibility, we examined the renal effects of two relatively high doses of EA (i.e., 66 and 151 mumol/kg i.v.) and an equivalent high dose (i.e., 151 mumol/kg) of two nonalkylating relatives of EA [dihydro-EA (EA-H2) and ticrynafen]. Twelve renal function parameters were monitored in pentobarbital-anesthetized dogs for a period of 2 hr after administration of EA, EA-H2 and ticrynafen and renal tissue was acquired at the end of the 2 hr of study for light and electron microscopic evaluation. Both doses of EA produced a profound diuresis of similar magnitude. However, only the larger dose was associated with a concomitant reduction in the glomerular filtration rate, a downward trend in the renal blood flow, a proteinuric response in four of the seven dogs in the treatment group and a reproducible vacuolation of the initial portion of the proximal convoluted tubules (i.e., the S1 cells). EA-H2 induced a small, transient increase in the excretion rates of sodium, chloride and potassium, but failed to elicit a proteinuric response or alter proximal tubular ultrastructure. Ticrynafen, a far more efficacious diuretic agent than EA-H2, likewise failed to trigger a proteinuric response or changes in renal ultrastructure. The combination of acidic (anionic) and alkylating properties of EA is thought to be responsible for the proximal tubular effects observed in this study.

Multichannel Thomson scattering apparatus.

A Thomson scattering apparatus for measuring the electron temperature and density along a 90-cm diam of the PLT plasma has been built. A wide angle objective images the 3-mm x 900-mm ruby laser beam onto an image dissector which rearranges the 300:1 image to 20:1 forming the input slit of a spectrometer. The stigmatic spectrometer provides twenty wavelength elements of ~70 A each. A microchannel-plate image intensifier optically coupled to a cooled SIT tube provides detection with single frame linearity and 1000:1 dynamic range. Spatial profiles of N(e) and T(e) in the 10(13)-10(14)-cm(-3) range and 0.05-3 keV have an accuracy of 30 [10(13)/N(e) (cm(-3))]((1/2))% per 1.2-cm element.

Evaluation of a semi-automated blood urea nitrogen analyzer.

We compared results for urea concentrations in plasma and serum as measured with the Kimble Blood Urea Nitrogen Analyzer method as the test method with those determined by continuous-flow analysis (AutoAnalyzer 1 method) as the comparison method. We evaluated accuracy and precision for patients' samples, National Bureau of Standards Standard Reference Material, College of American Pathologists Survey Validated Reference Materials, and College of American Pathologists Quality Assurance Service control materials. We found the test method to be more accurate and precise than the comparison method.

Short-term reactions of phytochrome in Mougeotia?

Phytochrome controlled chloroplast movement in Mougeotia is induced by flashes of polarized red light. Two subsequent flashes, separated by a dark interval of a few seconds, are much more effective than two simultaneous flashes; a maximal cumulative effect is reached if the duration of the dark interval is 30 ms or longer. We propose two light reactions in series, separated by a very fast dark reaction. Preliminary evidence is given that the energy requirement for these light reactions is different. It is suggested that the two reactions are related in some way to free and bound phytochrome.

Proposed method of measuring the current distribution in a tokamak plasma.

It is shown that the current distribution in a typical Tokamak plasma can be measured by a light scattering technique. The direction of the total magnetic field is measured accurately enough that the magnitude of the small poloidal component can be found. The field direction is measured by observing the scattered frequency spectrum of CO(2) laser light. The usual Gaussian spectrum becomes modulated at the electron cyclotron frequency when the difference between the incident and scattered wave vectors is nearly perpendicular to the magnetic field. The harmonics can be superimposed with a Fabry-Perot interferometer and their collective width resolved as the scattering direction is changed. The SNR is high only when the detector is shielded against background radiation.