Search PubMed⌕ Search

Biomedical subjects

M Heinrich

Publications and source records attributed to M Heinrich.

At least 91 records · Page 5Linked to original sources
PubMed1995

Inhibition of intestinal chloride secretion by proanthocyanidins from Guazuma ulmifolia.

The antisecretory activity of Guazuma ulmifolia bark was examined in rabbit distal colon mounted in an Ussing chamber. Chloride secretion was stimulated by cholera toxin and prostaglandin E2 (PGE2). Guazuma ulmifolia extract (GUE) completely inhibited cholera toxin-induced secretion if the extract was added to the mucosal bath prior to the toxin. Adding the extract after administration of the toxin had no effect on secretion. GUE did not inhibit PGE2-induced chloride secretion. These results indicate an indirect antisecretory mechanism. SDS-PAGE analysis of cholera toxin treated with GUE confirmed this presumption. GUE specifically interacted with the A subunit of the toxin. Preliminary phytochemical examinations showed that the most active fraction contains procyanidins with a degree of polymerisation higher than 8.

Animals↗
PubMed1995

Biological and pharmacological activities and further constituents of Hyptis verticillata.

Several extracts of Hyptis verticillata and isolated compounds were evaluated for their anti-inflammatory, antibacterial, antisecretory, and cytotoxic properties. The aerial parts yielded (R)-5-hydroxypyrrolidin-2-one and essential oil with the main components alpha-pinene, beta-pinene, and thymol. Spectroscopic methods (UV, IR, 1H-NMR, 13C-NMR, mass, CD) fully characterized (R)-5-hydroxypyrrolidin-2-one, as it was isolated by a bioassay guided fractionation. The essential oil, (R)-5-hydroxypyrrolidin-2-one, as well as the previously isolated rosmarinic acid and dehydropodophyllotoxine contributed to the antibacterial effects of H. verticillata. Furthermore, rosmarinic acid showed significant capillary stabilizing effects. Sideritoflavone inhibited prostaglandin synthase to a significant extent and had antisecretory effects comparable to those of NPPB. The cytotoxicity of the aqueous extract, as demonstrated using KB and HT 29 cell lines, may be of toxicological relevance in cases of internal application.

Animals↗
PubMed1994

Chemical investigation of Titan and Triton tholins.

We report chromatographic and spectroscopic analyses of both Titan and Triton tholins, organic solids made from the plasma irradiation of 0.9:0.1 and 0.999:0.001 N2/CH4 gas mixtures, respectively. The lower CH4 mixing ratio leads to a nitrogen-richer tholin (N/C > 1), probably including nitrogen heterocyclic compounds. Unlike Titan tholin, bulk Triton tholin is poor in nitriles. From high-pressure liquid chromatography, ultraviolet and infrared spectroscopy, and molecular weight estimation by gel filtration chromatography, we conclude that (1) several H2O-soluble fractions, each with distinct UV and IR spectral signatures, are present, (2) these fractions are not identical in the two tholins, (3) the H2O-soluble fractions of Titan tholins do not contain significant amounts of nitriles, despite the major role of nitriles in bulk Titan tholin, and (4) the H2O-soluble fractions of both tholins are mainly molecules containing about 10 to 50 (C + N) atoms. We report yields of amino acids upon hydrolysis of Titan and Triton tholins. Titan tholin is largely insoluble in the putative hydrocarbon lakes or oceans on Titan, but can yield the H2O-soluble species investigated here upon contact with transient (e.g., impact-generated) liquid water.

Amino Acids↗
PubMed1994

Screening Tanzanian medicinal plants for antimalarial activity.

Forty-three different plant species commonly used in traditional medicine for the treatment of malaria were selected and screened for their antimalarial activity against Plasmodium falciparum in vitro. Thirteen of the 43 species were obtained directly from traditional healers who use these plants for the treatment of malaria. The other plant species were collected on the basis of ethnomedicinal information in the literature. The plant material was collected from Morogoro, Dar es Salaam and Kagera regions in Tanzania. Fifty-eight plant samples from these 43 plant species, including leaves, roots and stem bark, were investigated. Apart from the crude EtOH extracts, petroleum ether (PE), ethyl acetate (EtAc) and H2O fractions of these extracts were also tested. The in vitro testing revealed that 37% of the investigated plants showed strong antimalarial activity with IC50 values below 10 micrograms/ml. The four most active plants included Cissampelos mucronata, Maytenus senegalensis, Salacia madagascariensis and Zanthoxylum chalybeum.

Animals↗
PubMed1994

Caffeoylquinic acids and some biological activities of Pluchea symphytifolia.

From the aerial parts of Pluchea symphytifolia, four known and two new caffeoylquinic acids, 1,3,4,5-tetra-O-caffeoylquinic acid and 1,3-di-O-[3,4,-bis-(3,4-dihydroxyphenyl)-cyclobutane-1,2-dicarbonyl]- 4,5-di-O-caffeoylquinic acid, and two flavonols were isolated and their structures elucidated by mass and NMR spectroscopy and by chemical degradation. The aqueous extract had weak antibacterial and weak antisecretory effects; the lipophilic extract showed a modest anthelmintic activity. The higher caffeoylated quinic acids participated in the antibacterial and anthelmintic effect of the extracts.

Animals↗
PubMed1992

Indigenous phytotherapy of gastrointestinal disorders in a lowland Mixe community (Oaxaca, Mexico): ethnopharmacologic evaluation.

Gastrointestinal disorders are one of the major health problems in developing countries. Sixty-five plants used popularly in the treatment of such disorders in a Mixe Indian community in Oaxaca (Mexico) and collected during a fieldstudy of 15 months are described. According to indigenous criteria a plant is used in the treatment of a certain illness because of the plant's characteristic smell and taste. Plants with astringent properties are particularly valued to treat diarrhoea and dysentery. Bitter, aromatic and bitter-aromatic plants are especially employed to treat gastrointestinal cramps and pain. Additionally, the efficacy of these plants was evaluated using ethnobotanical, phytochemical and pharmacologic information on the plants. The majority of the plants contain chemicals that may produce the effects desired by the Mixe. Frequently tannin-containing drugs are used to treat diarrhoea and dysentery. A large number of the plants used by the Mixe in the treatment of gastrointestinal pain contain essential oil or bitter principles. As a result of this evaluation, plants were selected which should be studied phytochemically and pharmacologically with priority, to evaluate further their potential in the treatment of gastrointestinal disorders.

Diarrhea↗
PubMed1992

Parasitological and microbiological evaluation of Mixe Indian medicinal plants (Mexico).

Medicinal plants are an important health resource in many regions of the Americas and are of particular importance to many Indian communities. Based on a recent ethnobotanical study in Mexico, we investigated the activity of 29 plant extracts against Entamoeba histolytica, three bacteria (Bacillus subtilis, Escherichia coli, and Micrococcus luteus) and two fungi (Cladosporium cucumerinum and Penicillium oxalicum). After separation of these extracts between CH2Cl2 and H2O the resulting phases were also evaluated.

Amebicides↗
PubMed1992

Amelioration of ischemic acute renal failure by dietary fish oil administration in conscious dogs.

The hypothesis that dietary fish oil would protect dogs from ischemic acute renal failure was tested. Fish oil (eicosapentaenoic acid, 55 mg/kg per day, and docosahexaenoic acid, 40 mg/kg per day was given to eight instrumented, female, beagle dogs for 6 wk, while seven control dogs received vehicle. After 3 wk, unilateral nephrectomy was performed and a pneumatic cuff with flow probe was placed around the remaining renal artery of each dog. Three weeks thereafter, the cuff was inflated for 120 min. Renal function, RBF, and prostanoid excretion were measured 24 and 72 h after ischemia. In dogs receiving fish oil, blood pressure, GFR, RBF, renal vascular resistance (RVR), cholesterol, triglycerides, and prostanoid excretion were measured weekly for 6 wk. Further, cytosolic calcium was measured before and five times after fish oil. Blood pressure decreased, serum cholesterol and triglycerides decreased, and the cytosolic calcium within platelets decreased. The urinary excretion (expressed as picograms per milligram of creatinine) of the thromboxane (TX) metabolite TXB2 and the excretion of prostaglandin (PG)E2, as well as the excretion of the PGI2 metabolite 6-keto PGF1 alpha were decreased. GFR, RBF (Cl inulin and Cl para-aminohippuric acid), and RVR were not influenced by fish oil. Unilateral nephrectomy decreased GFR and RBF and increased RVR as expected, whereas it further decreased prostanoid excretion. Acute renal ischemia caused a significant, reversible decrease in GFR and urine volume in vehicle-treated animals, whereas no significant effect on renal function or urine volume was observed in animals pretreated with fish oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1991

Endogenous dopamine (DA) modulates [3H]spiperone binding in vivo in rat brain.

[3H]spiperone (SPI) binding in vivo, biochemical parameters and behavior were measured after modulating DA levels by various drug treatments. DA releasers and uptake inhibitors increased SPI binding in rat striatum. In other brain areas, the effects were variable, but only the pituitary remained unaffected. Surprisingly, nomifensine decreased SPI binding in frontal cortex. The effects of these drugs were monitored by measuring DA, serotonin (5-HT) and their metabolites in the same rats. The increased SPI binding in striatum was parallel to the locomotor stimulation with the following rank order: amfonelic acid greater than nomifensine greater than D-amphetamine greater than or equal to methylphenidate greater than amineptine greater than bupropion. Decreasing DA levels with reserpine or alpha-methyl-para-tyrosine reduced SPI binding by 45% in striatum only when both drugs were combined. In contrast, reserpine enhanced SPI binding in pituitary. Thus, the amount of releasable DA seems to modulate SPI binding characteristics. It is suggested that in vivo, DA receptors are submitted to dynamic regulation in response to changes in intrasynaptic concentrations of DA.

Animals↗
PubMed1991

[Fasciocutaneous flap--a simple alternative to the musculocutaneous or free, microvascular flap of the lower extremity?].

Fasciocutaneous flaps demonstrate, in comparison to subcutaneous transposition flaps, far better local hemodynamic circulation and the length to width ratio can be increased to 3:1 or 5:1 so that they provide a simple method of closure in soft tissue defects. Fasciocutaneous flaps can be prepared rapidly and simply, due to the subfascial dissection, so that traumatic soft tissue defects can be closed directly. The donor site is closed with a split skin graft. Free musculocutaneous flaps and regional musculocutaneous island flaps are far more useful in large muscular defects, degloving injuries and osteomyelitis.

Fractures, Open↗
PubMed1990

Effects of selective dopamine D1 and D2 receptor agonists on the rate of GABA synthesis in mouse brain.

The effects of dopamine D1 and D2 receptor agonists and antagonists on the rate of GABA synthesis in four regions of mouse brain (corpus striatum, cerebellum, cortex and hippocampus) were examined after irreversible inhibition of 4-aminobutyrate: 2-oxoglutarate aminotransferase (EC 2.6.1.19; GABA-T) by gabaculine. The dopamine D2 receptor agonists PPHT, LY 171555 and RU 24213 exerted a dose-related inhibitory effect on GABA synthesis in these four regions. The decreases in the rate of GABA formation were prevented by the dopamine D2 receptor antagonist S(-)-sulpiride. The dopamine D1 receptor agonists SKF 77434 and SKF 38393 augmented gabaculine-induced GABA accumulation in the corpus striatum only, and this effect was blocked by the dopamine D1 receptor antagonist SCH 23390. However, SKF 81297 and SKF 82958, two other dopamine D1 receptor agonists, did not affect or only marginally altered the rate of GABA synthesis. Stimulation of D2 receptors thus induces a decrease in the rate of GABA formation in the four brain areas examined, whereas stimulation of D1 receptors either increases GABA synthesis in the corpus striatum or does not alter it. This effect appears to be independent of the degree of receptor occupancy.

Animals↗
PubMed1989

The fidelity of DNA polymerases during in vitro replication of a template containing 5-bromouracil at a specific site.

The miscoding properties of a 5-bromodeoxyuridine (dB) containing DNA template during in vitro replication have been investigated. 5-bromodeoxyuridine was introduced site-specifically into the amber 16 codon of a 25-mer oligodeoxynucleotide representing part of the sequence of phi x174am16(+)DNA. The dB containing oligodeoxynucleotide served as a template for in vitro replication by DNA polymerase alpha, DNA polymerase I (Escherichia coli) and AMV reverse transcriptase. The amber 16 revertant assay was used to detect the presence of misincorporated bases in the replication products. For all three DNA polymerases, the presence of dB does not constitute a significant barrier to replication. Errors at the position of dB substitution were found to originate exclusively from dGTP:dB mispairing during in vitro replication thus inducing A-T----G-C transitions. The dGTP:dB mismatches are formed at a 2-4-fold higher frequency as compared to dGTP:T mismatches. Our results indicate that the miscoding potential of dB-substituted DNA templates during replication is only weak at the specific site observed.

Avian Myeloblastosis Virus↗
PubMed1988

Interaction of the D1 receptor antagonist SCH 23390 with the central 5-HT system: radioligand binding studies, measurements of biochemical parameters and effects on L-5-HTP syndrome.

The interaction of SCH 23390 with dopamine (DA) and serotonin (5-HT) systems has been examined in vivo and in vitro. Like selective 5-HT2 blockers, SCH 23390 inhibited in vivo [3H]spiperone binding in the rat frontal cortex (ID50: 1.5 mg/kg) without interacting at D2 sites. SCH 23390 was equipotent to cinanserin and methysergide. In vitro, SCH 23390 inhibited [3H]ketanserin binding to 5-HT2 sites (IC50 = 30 nM). Biochemical parameters linked to DA and 5-HT were not changed excepted in striatum where SCH 23390 increased HVA and DOPAC. In the L-5-HTP syndrome model, SCH 23390 clearly showed antagonism of 5-HT2 receptors. SCH 23390 had weak affinity for 5-HT1B (IC50 = 0.5 microM), 5-HT1A (IC50 = 2.6 microM) and alpha 1-adrenergic receptors (IC50 = 4.4 microM).

5-Hydroxytryptophan↗
PubMed1986

The D-1 dopamine receptor antagonist SCH 23390 also interacts potently with brain serotonin (5-HT2) receptors.

The interaction of SCH 23390 with central serotonin 5-HT2 receptors was studied in vivo on [3H]spiperone binding and in vitro on [3H]ketanserin binding. SCH 23390 inhibited [3H]spiperone binding in rat frontal cortex with an ID50 of 1.5 mg/kg i.p., thus being equipotent to the two 5-HT2 antagonists cinanserin and methysergide. In vitro, SCH 23390 competed with [3H]ketanserin with an IC50 of 30 nM. These data indicate that SCH 23390 also binds with high affinity to 5-HT2 receptors in rat brain.

Animals↗
PubMed1985

Discrimination of neuroleptics by means of their interaction with amfonelic acid: an attempt to characterize the test.

The non-amphetamine stimulant amfonelic acid (AFA) is known to enhance the effects of haloperidol, trifluoperazine and spiperone but not those of the atypical neuroleptics clozapine, thioridazine, and sulpiride, on the striatal levels of 3,4-dihydroxyphenylacetic acid. Consequently, the interaction between neuroleptics and AFA has been proposed as a test to discriminate typical and atypical neuroleptics. In this study, these findings were confirmed. Essentially the same results were obtained when the levels of homovanillic acid were measured. However, striatal dopamine levels were decreased similarly by combinations of AFA with typical and atypical neuroleptics. A comparison of the results with 17 neuroleptics with their reported clinical liability to cause extrapyramidal symptoms supported the idea that the test may discriminate drugs with a better ratio of therapeutic vs side effects. A series of antidepressants and alpha-noradrenergic antagonists possessing antidopaminergic properties was found to perform like atypical neuroleptics, i.e. their effects on dopamine metabolites were not enhanced by AFA.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

Peri-operative infection prophylaxis with ornidazole and gentamicin in elective colonic surgery.

In a study of 60 patients undergoing elective colonic surgery peri-operative infection prophylaxis by the "one-shot' method was compared with that of 48-hour duration. The antibacterial agents used were ornidazole and gentamicin. Considering the patient population as a whole, no significant differences were found in the results. All the infectious complications which occurred post-operatively were due to bacterial contamination by aerobic pathogens. No anaerobic pathogens were detected in any of the cases.

Aged↗
PubMed1982

[Systemic mezlocillin prophylaxis in elective colon surgery].

A prospective randomized, controlled study comprising 100 patients was performed to evaluate the effect of mezlocillin given prophylactically in elective colon surgery. Fifty-two patients were treated and 48 served as controls. Both groups were well-matched for age, sex, disease and surgical procedure. 2 g of mezlocillin were given intravenously before surgery and then every eight hours until the fifth postoperative day. The concentrations of mezlocillin in serum and tissues were determined in 20 patients and related to the MICs of the contaminants and the bacteria isolated postoperatively. A significantly lower incidence of intra-abdominal complications, peritonitis, urinary tract infections and wound infections was found in the mezlocillin group (10%) than in the controls (46%). The average number of postoperative hospital days decreased significantly from 23 days in the control group to 19 days in the mezlocillin group. The analysis of the bacteriological results gave no indication of a selection of resistant strains due to the prophylactic use of mezlocillin. No side-effects were found in connection with mezlocillin prophylaxis.

Adult↗