Duration of the inductive effect of sheep erythrocytes on the recruitment of lymphocytes in the rat

The serum haemolysin response was studied in rats which had been subjected to a suppressive whole-body dose of γ-irradiation followed after 24 hours by an intravenous injection of sheep erythrocytes. A standard restorative dose of syngeneic thoracic duct lymphocytes was given immediately after the antigen or after a variable delay. Delays of 12, 24, 48 and 72 hours were followed by progressively smaller haemolysin responses. These observations suggested that the recruitment of lymphocytes begins very soon after the injection of sheep erythrocytes and that the inductive influence of the antigen wanes steadily so that the effective period of recruitment probably lasts for 1–2 days.     

Progressive resistance to doxorubicin in mouse leukemia L1210 cells with multidrug resistance phenotype: reductions in drug-induced topoisomerase II-mediated DNA cleavage

Cells selected for resistance to doxorubicin (DOX) express the multidrug resistance (MDR) phenotype, and resistance has been suggested to be due primarily to enhanced cellular efflux of drug. A progressively DOX-resistant (10- and 40-fold) L1210 mouse leukemia model system, which does not exhibit enhanced DOX efflux as a primary mechanism of resistance, was found to display the MDR phenotype, based on overexpression of P-glycoprotein in western blots and cross-resistance to vinca alkaloids. Cross-resistance to another topoisomerase II inhibitor, etoposide (VP-16), was similar to that of DOX (10- and 40-fold), whereas resistance to N-[4-(9-acridinylamino)-3-methoxyphenyl]methanesulfonamide (m-AMSA) was 5-fold lower. In contrast, no cross-resistance to camptothecin, an inhibitor of topoisomerase I, was observed. Topoisomerase II decatenation activity in nuclear extracts from 10- and 40-fold DOX-resistant cells was 2- and 4-fold lower, respectively, when compared to sensitive cells. In these cells, however, marked reductions in m-AMSA- and VP-16-induced topoisomerase II mediated DNA cleavage were found to exceed decreases in the catalytic activity of the enzyme. Results from this study demonstrated that, in progressively DOX-resistant L1210 mouse leukemia cells with the MDR phenotype, a better relation existed between the degree of resistance and reduced VP-16- and m-AMSA-induced topoisomerase II mediated DNA cleavage, than between increases in P-glycoprotein and concomitant reduction in DOX accumulation.     

The yield, motility and performance in the hamster egg test of human spermatozoa prepared from cryopreserved semen by four different methods.

Different procedures were investigated for the dilution of human cryopreserved semen and the preparation of an enriched population of motile spermatozoa for assisted reproduction. The dilution of a 0.25 ml straw of cryopreserved human semen by addition of 2.0 ml Ham's F-10 buffer in one step caused a large decrease in the proportion of motile spermatozoa. This was due to osmotic stress because many of the diluted spermatozoa exhibited swollen tails. To a large extent the damage could be avoided by adding the buffer in 0.10-ml aliquots at 30-s intervals. Spermatozoa obtained after such dilution of cryopreserved human semen were subjected to the swim-up procedure, to centrifugation on two-step gradients of Nycodenz or Percoll, or to filtration through glass fibre paper and compared with respect to yield, motility parameters and penetrating ability in the hamster egg test. The swim-up procedure yielded spermatozoa with excellent motility but only 12% of the available motile spermatozoa were recovered. On both Nycodenz and Percoll gradients, greater than 40% of the available motile spermatozoa were recovered and the average velocity of the spermatozoa was not significantly less than for the swim-up technique. When A23187 was used to promote acrosome reactions in the hamster egg test, Percoll-prepared spermatozoa achieved an average of 8.6 decondensed sperm heads/egg compared to 1.9 for Nycodenz and 1.3 for the swim-up procedure. The yield from glass fibre paper filtration was only 12% and the velocity of the spermatozoa and their performance in the hamster egg test was significantly poorer than in all the other methods.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetics of propantheline bromide in normal man

1 Six normal men were administered propantheline bromide (15 mg) in single doses intravenously, and as an oral solution in a balanced random crossover study.

2 Plasma concentrations and urinary excretion of the drug were measured after each treatment, using a stable isotope dilution assay.

3 Initial plasma concentrations of propantheline bromide ranged from 494 to 1310 ng ml^-1 3 min after the intravenous dose. Plasma levels of the drug decreased rapidly to reach concentrations of 4.5 to 27.2 ng ml^-1 4 h after dosage. A total of 17.3% (range 8.73 to 23.69%) of the intravenous propantheline bromide was eliminated by excretion in urine.

4 Pharmacokinetic analysis of these data indicated mean biological half-lives of 3.2 min (range 1.2 to 4.2 min; distribution phase) 57.9 min (range 12.6 to 106.2 min; fast elimination phase) and 2.93 h (range 2.16 to 3.69 h; slow elimination phase).

5 Total plasma clearance was calculated as 79.2 l h^-1 (range 28.1 to 137.7 l h^-1) and the renal clearance was 11.5 l h^-1 (range 6.7 to 15.7 l h^-1) demonstrating the importance of extra-renal routes in the elimination of propantheline bromide.

6 Following the oral dose of propantheline bromide plasma concentrations of the drug were at or below the precision level of the assay (5 ng ml^-1) at all times after dosage. A total of 1.08% (range 0.33 to 2.05%) of the propantheline bromide administered was excreted in urine.

7 The results of this study show that propantheline bromide was rapidly distributed and eliminated in man, and that extra-renal routes (probably metabolism) were the major pathways of elimination. Comparison of the data obtained following oral and intravenous administration indicate a low systemic availability of orally administered propantheline bromide. This may reflect the importance of the extra-renal routes of elimination in a `first-pass' effect for the drug.

     

Activation by high intensity peripheral nerve stimulation of adrenergic and opioidergic inhibition of a spinal reflex in the decerebrated rabbit

The short-latency sural to gastrocnemius reflex in the decerebrated rabbit was depressed for 20-30 min following high intensity conditioning stimulation of the common peroneal nerve. This effect was observed in animals with or without spinal section, but was greater in non-spinalized preparations. Graded conditioning stimuli showed that it was necessary to activate fine myelinated common peroneal axons to inhibit the reflex. In spinalized rabbits, maximal inhibition was achieved with conditioning stimulation of fine myelinated axons and was completely reversed by the opioid antagonist naloxone. In non-spinalized rabbits, maximal inhibition was only obtained with conditioning stimuli which activated non-myelinated axons. In these preparations the effects of common peroneal nerve stimuli were only blocked by co-administration of naloxone with the alpha 2-adrenoceptor antagonist idazoxan. Thus high intensity peripheral nerve stimuli activated a segmental opioidergic and a supraspinal adrenergic suppression of the sural-gastrocnemius withdrawal reflex. Such long-lasting suppression of reflex excitability may contribute to recovery from intensely noxious stimuli.     

Detection of tumor-associated membrane proteins in prostate and bladder carcinomas by means of protein blotting

Summary Analysis of membrane proteins by Western blotting has revealed both overexpression of proteins of molecular weight 10–200 kD (in particular, of proteins of MW less than 43 kD) and increased glycosylation in a xenografted human small cell undifferentiated prostatic carcinoma, and in two xenografted human bladder tumor cell lines compared with preparations from normal human tissue. Of potential functional significance were: a) a 43 kD protein in the bladder line, UCRU-BL-13, which demonstrated increased synthesis and a marked increase in the degree of glycosylation, and b), a 28 kD ConA-binding protein in prostatic tissue which was absent in normal tissue, present in intermediate quantity in a benign hyperplasia and greatly overexpressed in small cell carcinoma. This study demonstrates the utility of the protein blotting/autoradiography technique for the investigation of tumor membrane proteins.