Immunologic and nonimmunologic responsiveness in ragweed-sensitized dogs

The relationship between airway responsiveness to inhaled antigen and histamine, immunologic release of lung histamine, immunologic responsiveness of skin, and specific immunoglobulin E (IgE) antibodies were examined in 11 inbred allergic dogs immunized with extracts of ragweed and grass and 5 nonimmunized control dogs from the same colony. Airway responsiveness to antigen and histamine was characterized by the doses that increased the airflow resistance of the total respiratory system to twice the control values (ED200). Highly significant correlations were found between airway responsiveness and cutaneous responsiveness to antigen and other immunologic characteristics (e.g., IgE and histamine released from lung by inhaled antigen) in all dogs. In ragweed-sensitized dogs, there was an inverse correlation between immunologic responsiveness (reflected by the cutaneous response to antigen and histamine released from lung by inhaled antigen) and nonimmunologic responsiveness of airways (histamine ED200: r = 0.73, P less than 0.05 and r = 0.75, P less than 0.01, respectively). Antigen ED200 was also correlated with histamine release from lung after antigen inhalation (r = 0.74; P less than 0.01). We conclude that airway reactions to inhaled antigen in allergic dogs are dependent not only on immunologic factors but also on the degree of nonimmunologic airway responsiveness to histamine and that these factors are correlated inversely.     

Acetylcholine responses of identified neurons in Helix pomatia--III. Ionic composition of the depolarizing currents induced by acetylcholine

The ionic composition of the currents underlying the acetylcholine (ACh) depolarizations in the identified neurons B1 and B3 of the buccal ganglia of Helix pomatia was analysed. The equilibrium potential of the ACh responses was -2.8 +/- 0.6 mV (N = 49) and -4.0 +/- 0.7 mV (N = 79; mean +/- SEM) in the neurons B1 and B3, respectively. Replacement of NaCl in the bath solution by sucrose shifted the ACh equilibrium potential into the negative direction. A similar but less pronounced shift occurred when Ca2+ was substituted for Na+. Substitution of Cl- in the bath solution by propionate or an increase of the intracellular Cl- concentration did not affect the ACh equilibrium potential. Changes of K+ concentration in the bath between 1 and 50 mmol/l left the ACh equilibrium potential nearly unaffected when the Na+ concentration was at the control level. With a simultaneous reduction of extracellular Na+ an increase of K+ concentration shifted the ACh equilibrium potential towards more positive potentials. The findings are compatible with calculated K+ permeabilities if a K+ redistribution across the cell membrane is considered. In the neurons B1 and B3, channels operated by ACh are permeable for K+, Na+ and Ca2+, with the relative permeabilities 1.6:1.0:0.1.     

On the Structure-Bounded Growth Processes in Plant Populations

If growing cells in plants are considered to be composed of increments (ICs) an extended version of the law of mass action can be formulated. It evidences that growth of plants runs optimal if the reaction–entropy term (entropy times the absolute temperature) matches the contact energy of ICs. Since these energies are small, thermal molecular movements facilitate via relaxation the removal of structure disturbances. Stem diameter distributions exhibit extra fluctuations likely to be caused by permanent constraints. Since the signal–response system enables in principle perfect optimization only within finite-sized cell ensembles, plants comprising relatively large cell numbers form a network of size-limited subsystems. The maximal number of these constituents depends both on genetic and environmental factors. Accounting for logistical structure–dynamics interrelations, equations can be formulated to describe the bimodal growth curves of very different plants. The reproduction of the S-bended growth curves verifies that the relaxation modes with a broad structure-controlled distribution freeze successively until finally growth is fully blocked thus bringing about “continuous solidification”.     

Comparative study of the effect of L-lysine-L-oxidase from Trichoderma harzianum Rifai and Trichoderma viride on nucleic acid synthesis in human tumor cells in vitro

L-lysine-alpha-oxidase, a new fungal enzyme catalyzing oxidative deamination of L-lysine, exerts an inhibitory effect on DNA, RNA and protein synthesis in human cells of carcinoma ovarius (CaOv) in vitro.     

Catalytic properties of a human cytomegalovirus-induced protein kinase

Human cytomegalovirus, a DNA virus whose genome contains a fragment of transforming DNA, induces a threonine-serine protein kinase having a molecular mass of 68 kDa (p68). p68 was extracted from cells 96-144 h after infection, and immunoprecipitated with a monoclonal antibody (F6b). Antibody-enzyme complexes were immobilized on heat/formaldehyde-inactivated Staphylococcus aureus. The best substrates for p68 were acidic proteins, phosvitin and casein. Glycogen synthase, phosphorylase alpha and histones were phosphorylated at rates not higher than 1-4% that obtained with phosvitin as substrate. ATP and GTP were equally good substrates of p68. p68 is able to autophosphorylate at the same residues (i.e. threonine and serine) as the protein substrates. Autophosphorylation does not seem to represent an intermediate in substrate phosphorylation. The protein kinase activity of p68 was not enhanced by cAMP, calcium ions, or polyamines like spermine or spermidine. Only at low Mg2+ concentration spermine enhanced by 68% the rate of casein phosphorylation. Heparin, a potent inhibitor of casein kinase II, inhibits p68 activity too, but ten-times higher concentrations were required for the same degree of inhibition. Quercetin, a bioflavonoid, acts as a strong inhibitor of p68 protein kinase activity. The inhibitory effect of quercetin was competitive towards the nucleotide substrate (Ki = 2.8 microM), and non-competitive towards the protein substrate (Ki = 15 microM).     

Erythrocytes and age. Disintegration of erythrocytes by brilliant cresyl blue in correlation to age

The author describes changes in the disintegration of erythrocytes by brilliant cresyl blue in correlation to age, in rats aged 21, 42, 90-105, 340-360 and 690-720 days. The erythrocytes were incubated for 4 hours in an isotonic NaCl solution, in Krebs-Ringer solution and in each of these solutions plus brilliant cresyl blue. Disintegration in plain NaCl solution was found to be the greatest in the case of erythrocytes from 690- to 720-day-old rats. In the same solution plus brilliant cresyl blue, the rate of disintegration was very high in 21-day-old, 42-day-old and 690- to 720-day-old animals; at 90-105 days it was lower and at 340-360 days it was the lowest. Disintegration of erythrocytes in plain Krebs-Ringer solution was the lowest at 21 and 42 days; in the other age groups it was slightly higher. On adding brilliant cresyl blue, the rate of disintegration rose significantly in 21-, 42- and 690- to 720-day-old animals; at 90-105 days and 340-360 days it was no different from disintegration in plain Krebs-Ringer solution. It can be seen from the results that the rate of brilliant cresyl blue-induced erythrocyte disintegration is dependent on the age of the animals from which the erythrocytes are taken.     

Dissociation of inductive from differentiative signals transmitted by C8-substituted guanine ribonucleosides to B cells from SJL mice

A hitherto unknown defect in the immune responsiveness of B lymphocytes from SJL mice has enabled us to distinguish two qualitatively distinct classes of signal delivered to B cells by C8-substituted guanine ribonucleosides. This defect renders B cells from SJL mice unresponsive to the inductive (early acting) signal of 8-mercaptoguanosine (8MGuo) that culminates in mitogenesis and nonspecific secretion of immunoglobulin. Unresponsiveness is not attributable to a shift in either the dose-response or kinetic profiles, nor can the presence of suppressor cells be demonstrated. In striking contrast, however, SJL B cells exhibit normal responsiveness to the differentiative (T cell-like, or late acting) signal provided by the substituted nucleoside. This signal enables SJL B cells, depleted of T cells, to respond to T cell-dependent antigens, and synergizes with T cell-derived lymphokines. These data suggest 1) that nonspecific secretion of immunoglobulin is dependent on both inductive and differentiative signals, 2) that antigen alone can supply an effective inductive signal for antigen-specific responses, and 3) that the SJL mouse will provide a useful model for selective study of inductive vs differentiative events.     

Clinico-epidemiological characteristics of Q fever in the Carpathian region

The study of the specific epidemiological and clinical features of Q fever revealed the existence of an active focus of infection among humans due to their contacts with agricultural animals in one of the districts of the region. The focus was manifested by group morbidity among the cattle-tending personnel of a dairy farm. The source of this infection was cattle. The infection was transferred mainly through the air. The disease took a moderately severe course. The study of the rickettsial contamination of humans, animals and ticks suggested the presence of the active epidemic process and made it possible to work out concrete antiepidemic measures.     

Antimicrobial and antiviral activities of an actinomycete (Streptomyces sp.) isolated from a Brazilian tropical forest soil

A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions, obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type 1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action. This revised version was published online in August 2006 with corrections to the Cover Date.