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Biomedical subjects

M Meier

Publications and source records attributed to M Meier.

At least 109 records · Page 6Linked to original sources
PubMed1986

Lysostaphin-based assay of human granulocyte functions: a reevaluation.

Lysostaphin, a staphylococcus-derived staphylocidal substance, has widely been used in assays of granulocyte phagocytic and bactericidal capability. It rapidly kills extracellular bacteria. Thus, a separate determination of intracellular surviving bacteria can be performed. One prerequisite for this approach is the safe inactivation of lysostaphin (usually brought about by trypsin) before the intracellular bacteria are externalized for plating. This inactivation has been found by others to be incomplete. Data are presented demonstrating a safe inactivation of lysostaphin by trypsin, if the pH value is maintained within the alkaline range. A low variation of results is obtained by plotting the total number of bacteria killed per incubate vs the logarithm of initial bacterial inoculum or of the intracellular surviving bacteria, leading to linear regression lines. The variation of the results increases greatly for initial bacteria/granulocyte proportions of greater than 5/1. The results obtained for two different St. aureus strains are significantly different. Dexamethasone pretreatment (12 mg p.o. within 8 h) had no detectable influence, when fresh blood was assayed, while blood storage at room temperature for 12 h (without dexamethasone pretreatment) led to a significant functional impairment, mainly of bactericidal capability when analyzed in a pairwise fashion. A major limitation of this kind of assays is that killed bacteria cannot be determined directly.

Bacteriological Techniques↗
PubMed1986

Origin of small beta-lactamase-specifying plasmids in Haemophilus species and Neisseria gonorrhoeae.

Fifty-nine percent of unselected strains of Haemophilus parainfluenzae were found to carry small, phenotypically cryptic plasmid DNA species. Using filter blot hybridization, we found several plasmids which were homologous to the small beta-lactamase-specifying plasmids pJB1 and pFA7, which were originally isolated from Haemophilus ducreyi and Neisseria gonorrhoeae, respectively. Detailed filter hybridization studies combined with electron microscope heteroduplex analysis suggested that three cryptic plasmids are completely homologous to the non-TnA sequences of pJB1. One cryptic plasmid was found to be highly homologous to pJB603, a small beta-lactamase plasmid previously found in two isolates of H. influenzae. A second group of plasmids were found to carry sequences homologous to pJB1 and other sequences homologous to pJB603. These results strongly suggest that small beta-lactamase plasmids found in Haemophilus species and N. gonorrhoeae may have arisen by insertion of the transposable beta-lactamase-specifying element TnA into small, phenotypically cryptic replicons resident in H. parainfluenzae. Attempts to reproduce such a recombination event in the laboratory were not successful.

DNA Transposable Elements↗
PubMed1985

In vitro comparative studies of the calcium-entry activators YC-170, CGP 28392, and BAY K 8644.

Recently, the novel dihydropyridine derivates YC-170, CGP 28392, and BAY K 8644 have been reported to act in the opposite way to Ca2+-entry blockers. We have found that these compounds inhibit the binding of [3H]nitrendipine on guinea pig heart membranes (Ki: 6 nM BAY K 8644, 115 nM CGP 28392 and 690 nM YC-170). Like those of nifedipine (Ki 1 nM), the curves had slopes close to unity, and, unlike those of some nondihydropryridine Ca2+ antagonists, were not altered in the presence of diltiazem, indicating a competitive interaction at dihydropyridine-sensitive sites. In isolated guinea pig atria, these agents exerted positively inotropic effects similar in their potency ratio to those observed in the binding experiments (BAY K 8644 1, CGP 28392 1:17, YC-170 1:600). The maximum inotropic effects of BAY K 8644 and CGP 28392, and of YC-170 corresponded respectively to two-thirds and one-third of those induced by isoprenaline or extracellular Ca2+. In the isolated rat mesenteric artery, perfused with a depolarizing solution, vasoconstrictor Ca2+ dose-response curves are shifted to the right by nifedipine. By contrast, BAY K 8644 and CGP 28392 caused a distinct leftward shift of the Ca2+ dose-response curves, at concentrations of 3-300 nM and 30-300 nM, respectively, and YC-170 a marginal shift at concentrations of 200-2000 nM, i.e., similar ranges to their inhibitory effects on [3H]nitrendipine binding. At higher concentrations, all three compounds produced Ca2+-antagonistic effects. These results indicate that the compounds act at dihydropyridine-sensitive sites and exert partial agonistic activities in vascular and myocardial tissue.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1985

Biologic activities of recombinant human interleukin 2 on murine lymphocytes.

Recombinant human IL-2, produced by yeast cells, was tested in a number of in vitro responses with murine lymphocytes. The responses studied included proliferation of a cloned murine T lymphocyte line, generation of cytotoxic responses, recall of cytotoxic memory, and restoration of responses in spleen cells taken from cyclophosphamide-treated mice. In all cases, the recombinant human IL-2 had the same activity as purified murine IL-2. The recombinant material represents a source of IL-2 free of other lymphokines. The responses described in this work can therefore be ascribed to the direct effects of human IL-2, of known sequence, on the cells of interest.

Animals↗
PubMed1985

[Parasitologic studies, diagnosis and clinical aspects of cercarial dermatitis--public health significance for bathing waters in temperate zones].

Swimmer's dermatitides occurring in natural--accordingly polluted--waters are most probably of chemical nature. In clean waters, however, they are primarily caused by larvae of duck-flukes, the so called cercariae. In a natural pool near Biberach undetermined cases of swimmers' dermatitis have appeared. Hence a cercarial dermatitis was suspected and specific examinations were carried out. At the biological examination of the pool, many watersnails of the species Radix ovata have been found near the shore. Out of 180 collected snails 8 produced cercariae of different trematode species. Hence an infective cycle between duck and snail could be ascertained here. However, the special cercariae, producing dermatitis, could not be found. Having taken that into account the author was standing in the snail biotop without protective clothes for about 1 hour to provoke cercarial dermatitis. A few minutes later the corresponding clinical picture with an extremely strong itching developed. Papules were to be seen 12 h later, the symptoms lasted 2 weeks altogether. By different serological methods (Cercarienhuellenreaction) indirect immunofluorescent test with complete cercariae and cercarial sections antibodies against cercariae could be demonstrated in the serum of the author 14 days later. As a therapy only the symptomatic treatment of the itching is possible. In principle etiologic measures against cercarial dermatitides are possible by chemical snail control. But as a rule this is to be refused because of the severe ecological damages. However, in case of swimmers' dermatitis it is nonetheless indispensible to clarify eventual parasitogenic reasons because of the specific hygienic consequences.

Animals↗
PubMed1984

Enhancement of calcium influx in human platelets by CGP 28392, a novel dihydropyridine.

CGP 28392, a novel compound structurally related to the dihydropyridine Ca2+-entry blockers, causes a dose-dependent increase in intracellular free Ca2+ in human platelets, as measured with the Quin-2 Ca2+ indicator, with a semimaximal effective concentration of 2.2 X 10(-7) M. This effect occurs in a concentration range in which CGP 28392 competes for specific [3H]nitrendipine binding in guinea pig heart membranes. It can be inhibited by nitrendipine. The data presented furnish direct evidence of the Ca2+-entry-stimulating properties of CGP 28392 and indicate the presence of dihydropyridine-susceptible structures in human platelets.

Animals↗
PubMed1984

Beta-adrenergic blocking agents: substituted phenylalkanolamines. Effect of side-chain length on beta-blocking potency in vitro.

The synthesis of a group of potential beta-blockers bearing a new 5-ethoxysalicylamide substituent on nitrogen is described. These compounds were tested for beta-adrenergic blocking potency in vitro and compared with analogous compounds bearing a tert-butyl group on nitrogen. The new N-substituent increased the beta-blocking potency substantially. In a series of five homologous compounds of the type Ar(CH2)nCHOHCH2NHR (R = 5-ethoxysalicylamide; n = 0-4), two maxima of beta-blocking potency were found for n = 0 and 2. Moreover, the carbon isostere of the corresponding (aryloxy)propanolamine still proved to be a very potent beta-blocker. The ether oxygen in the side chain is therefore not an absolute requirement for activity. Structure-activity relationships are discussed.

Adrenergic beta-Antagonists↗
PubMed1982

Molecular epidemiology of beta-lactamase-specifying plasmids of Haemophilus ducreyi.

We have studied the genetic basis of beta-lactamase production in eight strains of Haemophilus ducreyi isolated in diverse areas of the world. Beta-lactamase production in all strains was mediated by plasmids having a molecular mass of either 5.7 or 7.0 megadaltons. Plasmids of 5.7 megadaltons were shown to carry the entire sequence of pFA7, the beta-lactamase specifying plasmid found in isolates of Neisseria gonorrhoeae epidemiologically linked to West Africa. Plasmids of 7.0 megadaltons were shown to carry the entire sequence of pFA3, the beta-lactamase specifying plasmid found in Far Eastern isolates of N. gonorrhoeae. Both groups of H. ducreyi plasmids were shown to carry physically complete and functional TnA sequences. Thus we have identified two types of H. ducreyi beta-lactamase plasmid which are identical to the two types of N. gonorrhoeae beta-lactamase plasmid, except that they carry complete TnA sequences.

Base Sequence↗
PubMed1982

Haemophilus influenzae: comparison of respiratory tract isolates with genitourinary tract isolates.

Haemophilus influenzae isolates recovered from the genitourinary (GU) tract were shown to have a significantly different biotype distribution compared with respiratory tract isolates. Biotype IV strains were recovered more commonly from the GU tract, and most strains were non-serotypable. Antibiotic-susceptible strains isolated from the GU tract more frequently harbored plasmids of less than 10 megadaltons than did antibiotic-susceptible respiratory tract strains. One 2.8-megadalton plasmid resident in a GU tract isolate and one 1.8-megadalton plasmid resident in a respiratory tract isolate were shown to be related to the small ampicillin resistance plasmids previously described in H. influenzae, Haemophilus parainfluenzae, Haemophilus ducreyi, and Neisseria gonorrhoeae. This supports the suggestion that these ampicillin resistance plasmids originated by transposition or recombination of the ampicillin transposon (TnA) with cryptic endogenous Haemophilus plasmids.

Anti-Bacterial Agents↗
PubMed1981

[Effect of a fibrin-antibiotic compound in bone and soft tissue infections].

It is reported on experimental experiences in the use of a biological adhesive system--highly concentrated native fibrinogen, thrombin and clotting factor XIII--in conjunction with local antibiotics. The results in animals are: Antibiotics in conjunction with the mentioned adhesive system give a high local concentration for a short time. The activity of the antibiotics decreases quickly within some activity of the antibiotics decreases quickly within some hours, there is no more antibiotic effect after 36 hours.

Animals↗
PubMed1981

Schistosoma mansoni: effect on growth, fertility, and development of distal male organs in Biomphalaria glabrata exposed to miracidia at different ages.

Growth, egg laying rate, and mortality of Biomphalaria glabrata (Portorican strain), maintained in groups of two, after exposure at different ages (1, 2, 4, 6, 8 weeks) to three miracidia each of Schistosoma mansoni (Liberian strain) were determined. The findings in infected snails were compared with those in exposed but uninfected (negative) and in unexposed snails. Younger snails were infected at higher rates, and these showed a significantly increased mortality. Young infected snails grew much slower than negative or unexposed snails; older infected snails grew at about the same rate as negative or control snails. A growth acceleration was not observed in parasitized animals. When prepatency to a high extent passed before sexual maturity, infected snails did not lay any eggs. In later infections the numbers of eggs dropped below those in healthy snails by the second week after exposure. Snails were dissected 15 weeks after exposure. Development of male reproductive organs (prostate gland, preputium plus penis sheath), in relation to shell diameter, was retarded particularly in animals infected before sexual maturity and highly retarded in growth. In larger animals the organs reached approximately their definitive size. Parasitized snails were partially deformed by an enlargement of their shell apertures on the right side.

Aging↗
PubMed1981

Lack of beta-adrenoreceptor hypersensitivity after abrupt withdrawal of long-term therapy with oxprenolol.

The possibility of beta-adrenoreceptor hypersensitivity after abrupt withdrawal of long-term therapy (8-18 months) with the slow-release (SR) formulation of oxprenolol (160-320 mg/day) was assessed in six patients with uncomplicated essential hypertension. The chronotropic dose 25 of isoproterenol (the dose that increases the resting heart rate by 25 beats/min), plasma concentration of catecholamines, triiodothyronin and thyroxin, plasma renin activity and aldosterone, hemoglobin, hematocrit and oxyhemoglobin dissociation were measured on the last day of oxprenolol SR intake and 1, 2, 3, 6 and 13 days after abrupt replacement by identical placebo tablets. The chronotropic dose 25 of isoproterenol (microgram/m2), which was greater than 25.6 in all patients on the last day of oxprenolol SR, fell to 4.83 +/- 2.03 on the second day and to 3.50 on the third day after its abrupt withdrawal and reached a minimal value on the thirteenth day (2.78 +/- 0.30). Throughout the study, plasma concentrations of catecholamines, triiodothyronin and thyroxin and oxyhemoglobin dissociation remained unchanged. Plasma renin activity and plasma aldosterone, which were suppressed during oxprenolol administration, rose significantly during placebo, coinciding with a significant fall in hematocrit and hemoglobin. No major subjective symptoms were reported by the patients. Thus, hypersensitivity of beta-adrenoreceptor-mediated responses was not demonstrated after sudden withdrawal of oxprenolol SR.

Adrenergic beta-Antagonists↗