Molecular Cytogenetic Characterization of Drug-resistant Leukemia Cell Lines by Comparative Genomic Hybridization and Fluorescence in situ Hybridization

Resistance to chemotherapeutic drugs is one of the major difficulties encountered during cancer chemotherapy. To detect genomic aberrations underlying the acquired drug resistance, we examined three cultured human myelomonocytic leukemia cell sublines each resistant to adriamycin (ADR), 1-β–1- d -arabinofuranosylcytosine (ara-C), or vincristine (VCR), using comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH), RT-PCR, and western blot techniques. Chromosomes 7, 10 and 16 most conspicuously showed frequent aberrations among the resistant sublines as compared to the parental KY–821 cell line. In ADR-resistant cells, gains at 7q21, 16p12, 16p13.1–13.3, 16q11.1–q12.1, and losses at 7p22–pter, 7q36–qter, 10p12, 10p11.2–pter, 10q21–q25, 10q26–qter were notable. In ara-C-resistant cells, no remarkable gain or loss on chromosome 7, but losses at 10p14–pter, 10q26–qter and 16p11.2–p11.3 were observed. In VCR-resistant cells, gain at 7q21 and losses at 10p11–p13, 10p15 and 16p11.2–p13.3 were found. FISH identified amplified signals for the MDR–1 gene located at 7q21.1 in ADR-and VCR-but not ara-C-resistant cells, and for the MRP–1 gene located at 16pl3.1 in ADR-resistant cells. These findings were validated at the mRNA and protein levels. Overlapping of the amplified MRP–1 gene with MDR–1 gene may play a critical part in the acquisition of resistance to ADR. Resistance to ara-C excluded MDR–1 gene involvement and highlighted other key genes such as MXR gene. Several other genes putatively involved in the development of drug resistance might lie in other aberrated chromosomal regions.     

Regional coupling of blood flow and methionine uptake in an experimental tumor assessed with autoradiography

Regional distribution of L-[methyl-¹⁴C] methionine (¹⁴C-MET) and 4-[¹⁸F] fluoro-antipyrine was compared using experimental rat tumors (AH109A) and a computerized autoradiogram image processor. Tissue distributions of the two tracers were found to be inhomogeneous in the tumor with nearly identical image patterns. Analysis of tissue radioactivities revealed that 82% of ¹⁴C-MET was derived from the acid insoluble fraction at 60 min after injection. The present study showed that ¹⁴C-MET uptake closely relates to tissue blood flow and may depend on its blood to tissue transport. Rapid incorporation of MET in the acid insoluble fraction implies that it is rapidly metabolized after transport into tumor tissue.     

Absorption of drugs from the nasal mucosa of rat

Absorption of drugs through the nasal mucosa was studied to find out the suitability of the nasal mucosa as a new site of administration. The in situ recirculation test with the nasal cavity of rat showed that absorption of weak electrolytes such as salicylic acid and aminopyrine was highly dependent on the amount of undissociated molecules following the pH partition theory. The in vivo studies on absorption through the nasal mucosa showed that an orally well-absorbed drug such as salicylic acid and bucolome was absorbed comparably to that by injection, while poorly absorbed drugs such as phenol red, sulbenicillin, cefazolin, cephacetrile and insulin, were also absorbed well through the nasal mucosa. These results suggest that the nasal route of administration would be useful as a new route of administration of drugs, to enhance the drug bioavailability.     

Quantitative as well as qualitative changes of serum albumin in patients with malnutrition

Many clinical and statistical studies have shown that hypoalbuminemia is the strong predictor of mortality in various chronic diseases. Serum albumin may play an important protective role in serum antioxidant activity against reactive free radicals in extracellular fluids. Persistent hypoalbuminemia worsens the serum-scavenging activity in patients with malnutrition, and contributes to the development of cardiovascular complications. An important physiological function of serum albumin is in the maintenance of redox state of the extracellular milieu via the intermolecular sulfhydryl-disulfide exchange reaction.