The peritoneal absorption of insulin in diabetic man: a potential site for a mechanical insulin delivery system

The potential of the peritoneum as a site for an "artificial beta cell" was studied. Three 14-hr studies were performed in an insulin-dependent diabetic male maintained on chronic peritoneal dialysis. All studies were performed between dialyses and throughout three standard American Diabetes Association (ADA) 600 calorie meals. The degree of insulin absorption from the peritoneal space was assessed by measuring the changes in plasma-free insulin concentration during these studies. The results of this study demonstrate that normalization of plasma insulin profiles may be observed with the administration of insulin into the peritoneal space. This absorbed insulin exerts hypoglycemic activity that suppresses the meal-induced rise in plasma glucose concentration. Thus, the peritoneal space may be a feasible route into which insulin may be delivered by an artificial beta cell.

Morphology of an Escherichia coli mutant with a temperature-dependent round cell shape

Mutants of Escherichia coli capable of growing in the presence of 10 microgram of mecillinam per ml were selected after intensive mutagenesis. Of these mutants, 1.4% formed normal, rod-shaped cells at 30 degrees C but grew as spherical cells at 42 degrees C. The phenotype of one of these rod(Ts) mutants was 88% cotransducible with lip (14.3 min), and all lip+ rod(Ts) transductants of a lip recipient had the following characteristics: (i) growth was relatively sensitive to mecillinam at 30 degrees C but relatively resistant to mecillinam at 42 degrees C; (ii) penicillin-binding protein 2 was present in membranes of cells grown at 30 degrees C in reduced amounts and was undetectable in the membranes of cells grown at 42 degrees C. The mecillinam resistance, penicillin-binding protein 2 defect, and rod phenotypes all cotransduced with lip with high frequency. Thus the mutation [rodA(Ts)] is most likely in the gene for penicillin-binding protein 2 and causes the organism to grow as a sphere at 42 degrees C, although it grows with normal rodlike morphology at 30 degrees C. At 42 degrees C, cells of this strain were round with many wrinkles on their surfaces, as revealed by scanning electron microscopy. In these round cells, chromosomes were dispersed or distributed peripherally, in contrast to normal rod-shaped cells which had centrally located, more condensed chromosomes. The round cells divided asymmetrically on solid agar, and it seemed that the plane of each successive division was perpendicular to the preceding one. On temperature shift-down in liquid medium many cells with abnormal morphology appeared before normal rod-shaped cells developed. Few abnormal cells were seen when cells were placed on solid medium during temperature shift-down. These pleiotropic effects are presumably caused by one or more mutations in the rodA gene.

A differential interaction of daunomycin, adriamycin, and N-trifluoroacetyladriamycin 14-valerate with mouse peritoneal macrophages

The interaction of three anthracycline drugs, daunomycin, Adriamycin, and N-trifluoroacetyladriamycin 14-valerate, with mouse peritoneal macrophages was explored. As assessed by drug-specific cytofluorescence, Adriamycin and daunomycin accumulated slowly within macrophages, first staining the nucleus and then the cytoplasmic inclusions that were induced by the drug treatment. N-Trifluoroacetyladriamycin 14-valerate distributed rapidly into the cells, was excluded from the nucleus, and induced numerous cytoplasmic inclusions. Electron microscopy revealed that the cytoplasmic inclusions were vacuoles containing some amorphous material and not the classical autophagic vacuoles containing organelles and membrane lamellae. All the drugs induced cell shrinkage with time and brought about cell death within 24 hr. Loss of cell function and viability was dose and time dependent; i.e., a 6-hr incubation with daunomycin or Adriamycin, 2.5 microgram/ml, brought about a 50% reduction in the phagocytic capacity of the treated macrophages. The damaging potency towards macrophages (daunomycin greater than Adriamycin greater than N-trifluoroacetyladriamycin 14-valerate) is in the reverse order to the in vivo therapeutic efficiency.

A differential interaction of daunomycin, adriamycin and their derivatives with human erythrocytes and phospholipid bilayers

Drug-membrane association of daunomycin, adriamycin and three of its derivatives, adriamycin-14-octanoate (AD-14-OCTA), adriamycin-14-acetate (AD-14-ACE) and N-trifluoroacetyladriamycin-14-valerate (AD32), was studied using phospholipid bilayers and human erythrocytes. The various drugs exhibited a differential affinity to membrane-lipid domains. Lipid-incorporated drugs exhibit a marked change in the shape of the emission spectrum which was utilized for the evaluation of the apparent dielectric constant, epsilon, of the environment surrounding the anthracycline moiety, as well as for the determination ofthe partitioning constant. By measuring the fluorescence polarization and the fluorescence lifetime of the incorporated drugs, rotational relaxation times of 4--8 ns were derived. These parameters provide a supportive evidence of the association of the fluorophore of the drugs with membrane-lipid domains. The anthracycline derivatives interact to a different degree with dipalmitoyl phosphatidylcholine and phosphatidylserine as reflected by changes in their thermotropic properties assessed by differential scanning calorimetry. Daunomycin was the most effective in decreasing the temperature of the phase transition and brought about a comparable reduction in the enthalpy of melting as AD32 and AD-14-OCTA. Adariamycin was the least potent of the series. AD-14-ACE and AD32 protected erythrocytes against hypotonic lysis, adriamycin and daunomycin had no significant effect on the susceptibility to hypotonic lysis, whereas AD-14-OCTA proved to be hemolytic even at low concentration (approx. 10(-7M).

Differential scanning calorimetry and enzymic activity of rat liver microsomes in the presence and absence of delta1-tetrahydrocannabinol

The thermal transitions of rat liver microsomes and isolated lipids were investigated by using differential scanning calorimetry. Endothermic transitions at approximately-5 degrees C and between approximately18 degrees and 40 degrees C were detected in the membranes and at approximately-10 degrees C and between approximately 10 degress and 20 degrees C in the extracted lipids. Interaction with delta1-tetrahydrocannabinol of microsomal membranes and of extracted lipids influences the thermotrophic behaviour as revealed by differential scanning calorimetry and eliminates the break in the Arrhenius plot of the enzymic activity of O-demethylase.

Fluidity difference of membrane lipids in human normal and leukemic lymphocytes as controlled by serum components

Lymphocytes isolated from the peripheral blood of patients with chronic lymphatic leukemia and from normal healthy donors were analyzed for fluidity of membrane lipids. The degree of lipid fluidity in normal and leukemic lymphocytes was quantitatively monitored by a method based on fluorescence polarization analysis of a fluorescent probe that is embedded in lipid regions of cellular membrances. The present studies were performed on lymphocytes isolated from 26 blood samples from 16 patients with chronic lymphatic leukemia and 36 blood samples from 36 normal health donors. A signifcant increase in the degree of fluidity of membrane lipids was found in lymphocytes isolated from leukemic patients as compared to that found for lymphocytes isolated from healthy donors. In vitro incubation of leukemic lymphocytes in normal serum resulted in a decrease in the fluidity of cellular membranes, whereas incubation of normal lymphocytes in leukemic serum resulted in an increase in the fluidity of membrane lipids. These observations suggest that normal and leukemic lymphocytes can be quantitatively characterized by monitoring degree of fluidity of cellular membrane lipids and that the fluidity difference between normal and leukemic lymphocytes is controlled by components in the blood serum.

Maintenance hemodialysis in myeloma kidney disease

Maintenance hemodialysis and chemotherapeutic agents were used in the treatment of seven patients with end-stage myeloma kidney disease. Results indicate that with the use of such therapy life can be prolonged substantially. It appears that patients with myeloma-with or without serious extrarenal complications-are suitable candidates for maintenance hemodialysis and should not be denied the treatment even in the face of systemic neoplasm.

Effects of local anaesthetics on intracellular fusion processes. Enhancement of concanavalin A-induced macrophage vacuolation

The extensive vacuolation elecited in mouse peritoneal macrophages in response to interaction with concanavalin A is markedly enhanced by a simultaneous exposure to anaesthetics. The potency of enchancing vacuolation increases within the series of normal alcohols with chain length C10 greater than C8 greater than C7 greater than C6. From the four tertiary amine local anaesthetics tested lidocaine and procaine are by far more effective than tetracaine and dibucaine. The latter two induce extensive cell shrinkage at concentrations at which the first two exhibit optimum enhancing capacity. Of the tested compounds chlorpromazine has the highest membrane/buffer partition coefficient and it exhibits its optimum enhancing effect on concanavalin A-induced macrophage vacuolation at the lowest drug concentration. The binding of [3H] concanavalin A as well as its internalization by macrophages incubated with the lectin for 15, 45 and 90 min are not affected significantly in the presence of decanol, procaine or chlorpromazine at concentrations of maximum enhancing effect on vacuolation. Thus enhancement of vacuolation does not stem from an increase in the rate or extent of concanavalin A interiorization. The rate at which vacuoles are generated is however markedly increased in the presence of chlorpromazine and the resulting vacuoles are of a larger diameter. At 2-5 fold the concentration required for inhibition of maximum enhancing effect, the drugs lead to extensive macrophage shrinkage and to depletion of intracellular ATP. Phagocytosis of heat-killed yeast cells is reduced by tertiary amine anaesthetics at concentrations optimal for enhancement of concanavalin A-induced vacuolation. Enhanced intracellular fusion of concanavalin A-bearing pinosomes to form vacuoles is discussed in terms of current ideas on factors vacuoles is discussed in terms of current ideas on factors vacuoles is discussed in terms of current ideas on factors affecting membrane fusion and the effects of anaesthetics on membrane organization of lipids, intramembraneous particles, glycoprotein receptors and the possible control by cytoskeletal elements. The results best fit the hypothesis that enhanced fusion correlates with membrane aggregation of both intramembraneous particles and concanavalin A receptor and the formation of areas relatively deplete of these structures and enriched in phospholipids.

The effect of hashish compounds on pphospholipid phase transition

The interaction of hashish compounds, delta 1-tetrahydrocannabinol and cannabidiol, with dipalmitoyl phosphatidylcholine was investigated using differential scanning calorimetry. Both drugs affect the transition of dipalmitoyl phosphatidylcholine from the gel to liquid crystalline state, decreasing both the melting temperature and the enthalpy of melting. At a drug to dipalmitoyl phosphatidylcholine ratio of approx. 1:5, two peaks appear in the transition profile, suggesting a phase separation in the drug dipalmitoyl phosphatidylcholine mixture.