Invitro Inhibition Research Articles

EFFECT OF MORINGA (Moringa oleifera) LEAF EXTRACT ON IN VITRO INHIBITION OF Candida albicans BIOFILM

Background: Oral candidiasis is an opportunistic infection in the oral cavity. This infection is caused by the fungus Candida albicans. The most important virulent attribute of this fungus is its ability to form biofilms, which can adhere to mucosa, epithelial lining, organs, prostheses or dentures. The formed biofilm is resistant to antifungal drugs. Objectives: The purpose of this study was to determine the effect of Moringa (Moringa oleifera) leaf extract on the inhibition of Candida albicans biofilm formation in vitro. Methods: This type of research is experimental study using post tests with control group design. Fungus used in this study was Candida albicans ATCC 10231. Determination of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were conducted by microdilution method. Inhibition test of C. albicans biofilm formation was carried out using the polystyrene microplate assay method. Concentration of extracts used in this study were 12.5%, 6.25%, 3.13% and 1.57%. Inhibitory activity of biofilm was measured using a crystal violet (CV) assay. Results: The results showed that MIC of Moringa leaf extract against the fungus C. albicans was at a concentration of 6.25%. Moringa leaf extract starting at a concentration of 3.13% already has had ability to inhibit formation of C. albicans biofilm. Conclusion: It can be concluded that Moringa leaf extract can inhibit formation of Candida albicans biofilm, so it can be developed as an alternative herbal ingredient to prevent oral candidiasis.EFFECT OF MORINGA (Moringa oleifera) LEAF EXTRACT ON IN VITRO INHIBITION OF Candida albicans BIOFILM

Evaluation of fungicidal efficacy of free and nano-encapsulated chitosan against <i>Aspergillus flavus</i> isolated from rice (<i>Oryza sativa</i>) seed

Grains are exposed to contamination by mycotoxins, both in the field and during storage. Aflatoxins produced by Aspergillus species are the most harmful and carcinogenic mycotoxins in grains. Synthetic fungicides are widely used for the control of mycotoxigenic fungi in grains. However, rising public awareness about the toxicological effects of fungicides on human health necessitates the development of non-toxic bio-fungicides. In this connection, reports have shown that chitosan synthesized from shell waste has the potential to serve as an alternative fungicide. Therefore, this study investigated the fungicidal efficacy of free and nano-encapsulated chitosan against aflatoxigenic fungus (Aspergillus flavus). High molecular weight chitosan was purchased, and the in-vitro antifungal efficacy of chitosan against A. flavus was tested using the food poisoning method. Nano-encapsulated chitosan was synthesized using the ionic gelation method, the particle size was determined, and invitro inhibition against A. flavus was investigated. The results revealed that nano-encapsulated chitosan with particle sizes of 525.4 nm, 468.3 nm, and 711.7 nm were obtained. In-vitro mycelial A. flavus growth inhibition of 100% was recorded at 1.5% and 2.0% of free chitosan, while at 0.5% and 1.0% of free chitosan, 45% and 75% inhibition were observed, respectively. Nano-encapsulated chitosan with particle size (nm) of 525.4, 468.3, and 711.7 at 0.50% recorded 61%, 84% and 87% inhibition, respectively. However, at 0.25%, the rate of inhibition was 64%, 78% and 67%, respectively. This study showed that free chitosan and nano-encapsulated chitosan are potential antifungal agents for the control of A. flavus.

In Vitro Inhibition Assessment of Acetyl Cholinesterase by Mahabhutarava Ghrta

Psychiatric disorders can make a huge negative impact not only to the patient but also to the family and his society. Schizophrenia is one among them that may lead to alteration in cognition and conation. Ayurveda considers the usage of ghrta preparations as the best strategy for the management of such psychiatric ailments. In the present study, a ghrta yoga, Mahabhutaravaghrta which had been in practise for the management of Schizophrenia and other psychiatric conditions was selected and an invitro inhibition assessment of Acetylcholinesterase has been planned. If inhibition is identified in the ghrta, it can justify the clinical efficacy of the drug in the patients.

Development of fluorine-substituted NH2-biphenyl-diarylpyrimidines as highly potent non-nucleoside reverse transcriptase inhibitors: Boosting the safety and metabolic stability.

Our recent studies for nonnucleoside reverse transcriptase inhibitors identified a highly potent compound JK-4b against WT HIV-1 (EC50=1.0nmol/L), but the poor metabolic stability in human liver microsomes (t 1/2=14.6min) and insufficient selectivity (SI=2059) with high cytotoxicity (CC50=2.08μmol/L) remained major issues associated with JK-4b. The present efforts were devoted to the introduction of fluorine into the biphenyl ring of JK-4b, leading to the discovery of a novel series of fluorine-substituted NH2-biphenyl-diarylpyrimidines with noticeable inhibitory activity toward WT HIV-1 strain (EC50=1.8-349nmol/L). The best compound 5t in this collection (EC50=1.8nmol/L, CC50=117μmol/L) was 32-fold in selectivity (SI=66,443) compared to JK-4b and showed remarkable potency toward clinically multiple mutant strains, such as L100I, K103N, E138K, and Y181C. The metabolic stability of 5t was also significantly improved (t 1/2=74.52min), approximately 5-fold higher than JK-4b in human liver microsomes (t 1/2=14.6min). Also, 5t possessed good stability in both human and monkey plasma. No significant invitro inhibition effect toward CYP enzyme and hERG was observed. The single-dose acute toxicity test did not induce mice death or obvious pathological damage. These findings pave the way for further development of 5t as a drug candidate.

Synthesis, in-silico, and in-vitro study of novel chloro methylquinazolinones as PI3K-δ inhibitors, cytotoxic agents

The PI3k-δ enzyme is of the key enzymes for cellular growth and proliferation. One of the key mechanisms for cytotoxic agents is to target the PI3k-δ enzyme. 5c and 5d were able to bind at ATP binding pocket of PI3k-δ enzyme in an inhibitory mode forming H -bond interaction with key amino acid Val828. 5c and 5d showed in-v itro inhibition of PI3k-δ enzyme(IC 50 =8.27±0.19μM), (IC 50 =1.24±0.03μM) respectively. 5c and 5d showed moderated to good in-vitro cytotoxicity against three cell lines HCT (IC 50 =8.00 ±0.12 μM), (IC 50 =47.56 ±0.67 μM), MCF-7 (IC 50 =21.22 ±0.33 μM), (IC 50 =41.07 ±0.58 μM) and HePG-2(IC 50 =58.98 ±0.33 μM), (IC 50 =17.78 ±0.58 μM), respectively. 5c and 5d showed in-vitro cytotoxicity against the WI-38 cell line (IC 50 =177.00±3.66μM), (IC 50 =148.49±1.37μM), respectively. Through a two-step procedure, 3-amino-7-chloro-2-methylquinazolin-4(3 H )-one was synthesized from 2-amino-4-chlorobenzoic acid as a starting material. The latter reacted with chloro acetylchloride, then nucleophilically substituted with various secondary amines to produce acetamide derivatives ( 5a-e ), or underwent condensation reaction with various aldehydes to produce arylidine derivatives ( 6a-e ). In-silico study of drug-likeness and ADME descriptors was conducted for all compounds. Compounds showed good oral bioavailability, as well as good gastrointestinal absorption potential and no symptoms of liver or CNS adverse effects. In-vitro cytotoxic activity of the compounds was moderate to good when compared to staurosporine in three cell lines: HCT, MCF-7, and HepG-2. Compound 5c showed the highest cytotoxic activity against the HCT cell line (IC 50 = 8.00 ± 0.33 μM), Compound 5d showed the highest cytotoxic activity against the HepG-2 cell line (IC 50 = 17.78 ± 0.58 μM). Acetamide derivatives revealed higher cytotoxic activity compared to arylidine derivatives. Compound 5d had the highest enzyme inhibition activity in the in-vitro PI3k-δ enzyme inhibition assay (IC 50 = 1.24 ± 0.03 μM) followed by 5c (IC 50 = 8.27 ± 0.19 μM). Both 5c and 5d were able to bind at the ATP binding site of the PI3k-δ enzyme in a mode similar to the native ligand where they formed H -bond interactions with the hinge region amino acid Val828 and hydrophobic interactions with other amino acids indicating an agreement between molecular docking simulation study and the biological screening.

Effective removal of biofilm formation in Acinetobacter baumannii using chitosan nanoparticles loaded plant essential oils

The current study focused on anti-biofilm property of chitosan loaded essential oils, which were obtained and evaluated against biofilm forming Acinetobacter baumannii. The results of agar well punctured method demonstrated its effeciency at 150 µg/mL concentration. The complete biofilm arrangement was demolished at 150 µg/mL concentration as suggested by quantitative invitro inhibition assay measurement. The biofilm metabolic cells lost their virulence, which was confirmed by color changes of XTT assay. Furthermore, the biofilm metabolic product inactivation was proved by congo red agar assay with the evidence of complete exopolysaccharide arrest. The interior and exterior portions of the chitosan loaded essential oils were completely damaged, as suggested by confocal laser scanning electron microscope and scanning electron microscope observations. Hence, all the invitro inhibition assays, and morphological examination confirmed that the biofilm forming Acinetobacter baumannii lost its virulence factors and its bacterial growth was eradicated efficiently.

First Report on Post-harvest management of black mold of onion by eugenol

Black mold of onion caused by Aspergillus niger is a serious and prevalent postharvest disease of onion. This problem drastically reduces the quality and marketability of onion bulbs. Conventional fungicides employed to con-trol A. niger contamination posed negative impact on human health and en-vironment and highlighted the need to discover ecofriendly management practices. In the present study we attempted to explore the use of eugenol for the management of black mold of onion. Eugenol may exhibit differ-ences in antifungal activity in liquid state and in volatile phase. Hence, we developed and validated a new method, conical flask- paper cone method to study the antifungal activity of vapour phase disinfectants. This method was found to be precise, reproducible, sensitive and accurate with inter-assay R.S.D < 10%, intra-assay R.S.D <5% and R2>0.99. Conical flask- paper cone method was further utilized to determine the minimum inhibitory concen-tration of eugenol against A. niger. We observed that 0.03355 μl / cm3 eu-genol caused invitro and invivo inhibition of A. niger. Onion bulbs that were stored by eugenol fumigation, prior inoculated by A. niger, did not develop black mold symptoms and maintained high sensory acceptability. Microscop-ic observations revealed that eugenol fumigation resulted in inhibition of spore germination, coagulation of cytoplasm, formation of large vesicles and shrinkage of A. niger mycelium. In conclusion, our study showed for the first time that eugenol fumigation significantly controlled black mold incidence during storage and maintained post harvest quality and sensory acceptance. This study also introduced a new method for evaluating antifungal activity of volatile compounds.

In vitro and in vivo inhibition of Hass avocado polyphenol oxidase enzymatic browning by paeonol, β-cyclodextrin, and paeonol:β-cyclodextrin inclusion complex

Polyphenol oxidase (PPO) was extracted from Hass avocados and its physicochemical properties were analyzed. The optimum pH and temperature of the enzyme were pH 7.5 and 20°C. This PPO showed a high thermal stability, since 26% of the initial activity was retained by the enzyme after heating at 60°C for 40min. Inhibition studies were performed using different chemical reagents, and the order in the inhibition efficiency was paeonol>4-hydroxybenzaldehyde>β-cyclodextrin (β-CD). The first two inhibitors presented a non-competitive mechanism while the inhibition by β-CD results from a mixed type mechanism. Since the aqueous solubility of paeonol (a natural compound) is very low, the inclusion complex between this drug and β-CD was obtained in solution and solid state. The stoichiometry of the paeonol:β-CD complex was 1:1 and its ΔG° of formation was-26kJ/mol. The complexation of paeonol by β-CD not only enhances the aqueous solubility and thermal stability of the drug, but also improves the invitro inhibition efficiency against PPO. Colorimetric analysis on avocados pulp (invivo) showed that the inclusion complex does not increase the inhibitory effect of paeonol, remaining practically unchanged. However, the formulation of paeonol:β-CD inclusion complex allows employing this compound as PPO inhibitor in aqueous solutions.

Fructose‑1,6‑bisphosphatase‑1 decrease may promote carcinogenesis and chemoresistance in cervical cancer.

Fructose-1,6-bisphosphatase-1 (FBP1), a gluconeogenesis rate-limiting enzyme expressed in various tissues, is important in the carcinogenesis of various cancers. To evaluate the association of FBP1 expression and carcinogenesis and chemoresistance in cervical cancer, the present study analyzed 140patients of squamous cell carcinoma of cervical cancer (CSCC) who had adjuvant concurrent chemoradiation therapy following radical surgery. By detecting FBP1 protein expression in paraffin‑embedded tumor tissues through immunohistochemistry, it was observed that 50% of the cases had a low expression of FBP1, which was associated with a shorter overall survival time (P=0.011). In addition, FBP1 mRNA level was downregulated in tumor tissues, compared with cervical normal tissues. Among the tumor‑associated prognostic factors, loss of FBP1 expression (χ2‑test, P=0.025) was significantly associated with the tumor recurrence and greater tumor stage of cervical cancer patients (2‑test, P<0.0001). In 3‑(4,5)‑dimethylthiahiazo(‑z‑y1)-3,5-diphenytetrazoliumromide (MTT) assay of primary tumor cells, the median invitro inhibition rate of cisplatin, carboplatin, nedaplatin, and oxaliplatin was 62, 47, 58 and 52%, respectively. Although there was no significant association between FBP1 expression and invitro tumor inhibition rates of primary tumor cells, overexpression of FBP1 markedly suppressed carcinogenesis and restored the chemosensitivity to cisplatin in cervical cancer cell lines of HeLa and CaSki. Overall, decreased levels of FBP1 may be used as a predictor for poor prognosis of cervical cancer patients, however the mechanism requires further investigation.

Bioactive potential of actinobacteria isolated from certain under-studied regions in India

Studies on extended beta lactamase producing, biofilm forming clinical bacterial pathogens and its invitro inhibition by Actinobacterial extractsHemachandran. K., S. Bharathi, M. Radhakrishnan, R. Balagurunathan

Degradation of cefdinir from pharmaceutical wastewater using immobilized Candida sp. SMN04 and biofilm formed on gravels

Studies on extended beta lactamase producing, biofilm forming clinical bacterial pathogens and its invitro inhibition by Actinobacterial extractsHemachandran. K., S. Bharathi, M. Radhakrishnan, R. Balagurunathan

Low molecular weight thiols: glutathione (GSH), mycothiol (MSH) potenail antioxidant compound from actinobacteria

Studies on extended beta lactamase producing, biofilm forming clinical bacterial pathogens and its invitro inhibition by Actinobacterial extractsHemachandran. K., S. Bharathi, M. Radhakrishnan, R. Balagurunathan

641 DEVELOPMENT OF IN VITRO AND CELL-BASED ASSAYS FOR ASSESSING NUCLEOTIDE BIOSYNTHESIS INHIBITION

[1] D.G. Streeter, J. T. Witkowski, G.P. Khare, R.W. Sidwell,r;j. Bauer, R.K. Robins, L. N. Simon (1973) Mechanism of Action of 1-i3-DRibofuranosyl-1,2,4-Triazole-3-Carboxamide (Virazole), A New Broad-Spectrum Antiviral Agent Proc. Nat. Acad. Sci. USA Vol. 70, No. 4, pp. 1174-1178 [2] R. C. Willis, D. A. Carson, and J. E. Seegmiller (1973) Adenosine Kinase Initiates the Major Route of Ribavirin Activation in a Cultured Human Cell Line. PNAS USA, 75: 3042-3044. [3] Wu JZ, Larson G, Walker H, Shim JH, Hong Z. Phosphorylation of ribavirin and viramidine by adenosine kinase and cytosolic 5'nucleotidase II: Implications for ribavirin metabolism in erythrocytes. (2005) Antimicrob Agents Chemother. 49(6):2164-71 References Background Numerous nucleoside analogues (NAs) are currently used to treat viral hepatitis. They are usually designed to inhibit one viral target. This remains in contrast with the observation that ribavirin (1-β-D-ribofuranosyl1,2,4-triazole-3-carboxamide), a purine nucleoside analogue currently used as a part of bi-therapy of hepatitis C infection, has multiple modes of action: (i) depletion of intracellular GTP pools by inhibition of the cellular IMPDH, (ii) inhibition of viral polymerase activity by the 5’-triphosphate metabolite of ribavirin, (iii) induction of error catastrophe as a result of accumulation of mutations in the viral genome. Even if no direct relationship between ribavirin antiviral action and IMPDH inhibition has been demonstrated, the depletion of cellular GTP should result in an increased frequency of ribavirin triphosphate incorporation by viral polymerase due to lower intracellular concentration of its natural competitor.

Biocontrol Agents Induce Disease Resistance in "Phyllanthus niruri" Linn against Damping-Off Disease Caused by "Rhizoctonia solani"

Five isolates each of Trichoderma viride and Pseudomonas fluorescens and four isolates of Bacillus subtilis were evaluated for their ability to control Rhizoctonia solani, the causal agent of damping off of Phyllanthus niruri. Among the isolates tested, TVUV10 (T. viride), PFMMP (P. fluorescens) and BSG3 (B. subtilis) showed maximum in vitro inhibition of mycelial growth of R. solani. Isolate PFMMP was also very effective in reducing disease incidence in greenhouse conditions. The effective isolates were evaluated for their ability to induce defense reactions in P. niruri plants. Earlier and increased activity of phenylalanine ammonia lyase, peroxidase, polyphenoloxidase and total phenolics were observed in the biocontrol-agent pretreated P. niruri plants challenged with R. solani. Isolate PFMMP caused early and increased synthesis of all defense related enzymes and total phenol. The present study showed that isolates TVUV10, PFMMP and BSG3 of T. viride, P. fluorescens and B. subtilis respectively are good candidates for the control of R. solani in P. niruri.

Inhibition of type A and type B monoamine oxidases by naturally occurring xanthones.

Eleven naturally occurring xanthones were tested for IN VITRO inhibition of type A and type B monoamine oxidases (MAO's), prepared by treating rat brain mitochondria with selective inhibitors. All compounds showed various potencies of inhibition for both types of MAO. 1-Hydroxy-3,8-dimethoxy-xanthone and 1,3-dihydroxy-7,8-dimethoxy-xanthone were most potent for type A MAO, while they were rather weak for type B MAO, showing that these compounds can be regarded as type A inhibitors. The xanthones bearing 1,3-dihydroxy-groups generally exhibited potent inhibition for both types. The 3-O-glucosides of xanthones were much weaker than their corresponding genuine aglycones for both types.

Degradation of DNA by 1,-10-phenanthroline

The metal chelator 1,10-phenanthroline, in the presence of a reducing agent and a copper salt, causes the degradation of double-stranded DNA to acid soluble fragments. The degradation of DNA is dependent on the presence of O2. The concentrations of 1,10-phenanthroline which are effective in degrading DNA are of the same order of magnitude as those that result in inhibition of nucleotidyl transferase reactions. The requirement for a copper salt can only be demonstrated when all reagents are treated with Chelex to remove metal contaminants. It is proposed that the degradation of DNA in the presence of 1,10-phenanthroline may account for the invitro inhibition of DNA and RNA synthesis seen with this metal chelator, rather than any effect on nucleotidyl transferases.

ChemInform Abstract: REGRESSION ANALYSIS OF THE RELATION BETWEEN PHYSICAL PROPERTIES AND THE IN VITRO INHIBITION OF MONOAMINE OXIDASE BY PROPYNYLAMINES

Chemischer InformationsdienstVolume 7, Issue 1 Isocyclic Compounds ChemInform Abstract: REGRESSION ANALYSIS OF THE RELATION BETWEEN PHYSICAL PROPERTIES AND THE IN VITRO INHIBITION OF MONOAMINE OXIDASE BY PROPYNYLAMINES Y. C. MARTIN, Y. C. MARTINSearch for more papers by this authorW. B. MARTIN, W. B. MARTINSearch for more papers by this authorJ. D. TAYLOR, J. D. TAYLORSearch for more papers by this author Y. C. MARTIN, Y. C. MARTINSearch for more papers by this authorW. B. MARTIN, W. B. MARTINSearch for more papers by this authorJ. D. TAYLOR, J. D. TAYLORSearch for more papers by this author First published: January 6, 1976 https://doi.org/10.1002/chin.197601169Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue1January 6, 1976 RelatedInformation

ChemInform Abstract: CATECHOL O‐METHYLTRANSFERASE PART 4, IN VITRO INHIBITION BY 3‐HYDROXY‐4‐PYRONES, 3‐HYDROXY‐2‐PYRIDONES AND 3‐HYDROXY‐4‐PYRIDONES

Chemischer InformationsdienstVolume 4, Issue 38 Other Subjects ChemInform Abstract: CATECHOL O-METHYLTRANSFERASE PART 4, IN VITRO INHIBITION BY 3-HYDROXY-4-PYRONES, 3-HYDROXY-2-PYRIDONES AND 3-HYDROXY-4-PYRIDONES R. T. BOCHARDT, R. T. BOCHARDTSearch for more papers by this author R. T. BOCHARDT, R. T. BOCHARDTSearch for more papers by this author First published: September 18, 1973 https://doi.org/10.1002/chin.197338409Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume4, Issue38September 18, 1973 RelatedInformation

THE IN VITRO INHIBITION OF GLUTAMIC AND GLUTAMINE DECARBOXYLANE BY AN EXOTOXIN FROM PSEUDOMONAS TABACI

Annals of the New York Academy of SciencesVolume 166, Issue 1 p. 314-322 THE IN VITRO INHIBITION OF GLUTAMIC AND GLUTAMINE DECARBOXYLANE BY AN EXOTOXIN FROM PSEUDOMONAS TABACI Carlos Lamar Jr., Carlos Lamar Jr. Department of Medicine, University of Wisconsin School of Medicine, and the Veterans Administration Hospital Madison, Wis.Search for more papers by this authorBarbara Imm, Barbara Imm Department of Medicine, University of Wisconsin School of Medicine, and the Veterans Administration Hospital Madison, Wis.Search for more papers by this author Carlos Lamar Jr., Carlos Lamar Jr. Department of Medicine, University of Wisconsin School of Medicine, and the Veterans Administration Hospital Madison, Wis.Search for more papers by this authorBarbara Imm, Barbara Imm Department of Medicine, University of Wisconsin School of Medicine, and the Veterans Administration Hospital Madison, Wis.Search for more papers by this author First published: September 1969 https://doi.org/10.1111/j.1749-6632.1969.tb54283.xCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume166, Issue1Vitamin B6 in the Metabolism of the Nervous SystemSeptember 1969Pages 314-322 RelatedInformation

CATECHOL-OMETHYL TRANSFERASE INHIBITORS. IN VITRO INHIBITION OF THE ENZYME IN MOUSE-BRAIN EXTRACT.

Acta Pharmacologica et ToxicologicaVolume 21, Issue 3 p. 205-214 Catechol-O-Methyl Transferase Inhibitors. In Vitro Inhibition of the Enzyme in Mouse-Brain Extract S. B. Ross, S. B. Ross Research Laboratories of AB Astra, Södertälje, Sweden.Search for more papers by this authorÖ. Haljasmaa, Ö. Haljasmaa Research Laboratories of AB Astra, Södertälje, Sweden.Search for more papers by this author S. B. Ross, S. B. Ross Research Laboratories of AB Astra, Södertälje, Sweden.Search for more papers by this authorÖ. Haljasmaa, Ö. Haljasmaa Research Laboratories of AB Astra, Södertälje, Sweden.Search for more papers by this author First published: September 1964 https://doi.org/10.1111/j.1600-0773.1964.tb01785.xCitations: 24AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume21, Issue3September 1964Pages 205-214 RelatedInformation