A novel phage-displayed MilA ELISA for detection of antibodies against Myc. bovis in bovine milk

AIMS

The aim of this study was to assess a phage-displayed MilA protein of Myc. bovis in an indirect ELISA for the detection of Myc. bovis antibodies in milk samples.

METHODS AND RESULTS

The desired sequence of milA gene was synthesized and cloned into pCANTAB-F12 phagemid vector. The expression of the MilA on the phage surface was confirmed by Western blotting. The recombinant phage was used in the development of an indirect ELISA to detect Myc. bovis antibodies in milk samples. There was a significant agreement between the results of phage-based ELISA and recombinant GST-MilA ELISA for the detection of Myc. bovis antibodies in milk samples.

CONCLUSIONS

The inexpensive and convenient phage-based ELISA can be used instead of recombinant protein/peptide ELISA as an initial screening of Myc. bovis-associated mastitis.

SIGNIFICANCE AND IMPACT OF STUDY

Mastitis associated with Myc. bovis is a continuous and serious problem in the dairy industry. Sero-monitoring of Myc. bovis infection cases are one of the key factors for surveillance of the infections in dairy farms. Despite the existence of some commercially serological assays for Myc. bovis antibodies, they have some limitations regarding their sensitivity and availability. The development of accurate diagnosis tools could contribute to control programmes of Myc. bovis-associated mastitis in the dairy herds.

Remediation of zearalenone mycotoxin contamination in rumen fluid by phytochemical compounds of Zataria multiflora

Background

Zearalenone (ZEA), which is one of the most prevalent wheat and corn seeds mycotoxins causes acute and chronic toxicities in ruminants, poultry, and aquatic animals. Among commercial toxin binders, only a few active charcoals have the significant ability to adsorb ZEA contamination; nevertheless, active charcoal is not considered a sound additive by the feed industry.

Aims

This study aimed to screen and identify the ZEA-degradation compounds of the Zataria multiflora (Shirazi thyme) in the cattle rumen fluid.

Methods

In this investigation, essential oil and different extracts (n-hexane, ethyl acetate, and methanol) of the aerial part of Shirazi thyme (at three concentrations of 0.5, 1, and 2 mg/ml) were screened to reduce ZEA contamination conditions (2 µg/ml) in rumen fluid. ZEA-content was analyzed by high-performance liquid chromatography (HPLC) with a fluorescence detector. In addition, Shirazi thyme phytochemical compounds responsible for eliminating ZEA were localized by HPLC-based activity profiling and then identified by mass spectrometry (LC-MS).

Results

Both n-hexane and methanol extracts of Z. multiflora, considerably remediated ZEA (63-78%) from rumen fluid. According to HPLC-based activity profiling of Z. multiflora extract and LC-MS analysis, two triterpene compounds, including ursolic and oleanolic acids were introduced as ZEA degradation agents.

Conclusion

Z. multiflora could be recommended as a new botanical source, and ursolic and oleanolic acids could be introduced as new phytochemical compounds that degrade ZEA.

Introducing Alternaria tenuissima SBUp1, as an endophytic fungus of Ferula assa-foetida from Iran, which is a rich source of rosmarinic acid

Endophytic fungi are the endogenous micro-organisms to interacting with the plant cells, which do not exhibit any symptoms on the host plant and may produce some of the main secondary metabolites of the host plant cells. Ferula assa-foetida is a perennial and endemic medicinal plant of Iran, which is a rich source of sesquiterpene, coumarins, polysulfides and phenolic acids. In this study, 28 endophytic fungi isolates including Fusarium (60·7%), Aspergillus (7·1%), Alternaria (17·9%) and Plectosphaerella (7·1%) were isolated from F. assa-foetida root (57·1%), stem (32·1%) and leaf (10·8%) collected from Parvand protected area. Subsequently, their ability to produce phenolic acids was evaluated. The high amounts of total phenol (326·09 mg g-1 of dry weight, DW), total flavonoid (901·11 mg g-1 DW) and antioxidant activity (247·96 mg l-1 ) were found in the supernatant fluid of SBUp1 isolate. The high-performance liquid chromatography analysis of 14 phenolic acids showed that rosmarinic acid (RA) is the main phenolic acid in the supernatant fluid of SBUp1 by 64·11 mg g-1 DW confirmed by the liquid chromatography coupled with mass spectrometric analysis. According to morphological identification followed by phylogenetic study based on internal transcribed spacer (ITS) sequencing (ITS1-5.8S-ITS2) analysis, the SBUp1 isolate was identified as Alternaria tenuissima. Eventually, to our knowledge, it is the first document confirming A. tenuissima as an endophytic fungus of F. assa-foetida, which is a rich source of RA.

Interleukin-8 gene expression and apoptosis induced by Salmonella Typhimurium in the presence of Bacillus probiotics in the epithelial cell

AIMS

This study aimed to evaluate the effects of three Bacillus probiotics on Salmonella Typhimurium, and interleukin-8 (IL-8) gene expression in the co-culture of the Bacillus and the pathogen in vitro.

METHODS AND RESULTS

Bacillus subtilis, Bacillus indicus and Bacillus coagulans were initially turned to spore and heat-inactivated forms. The cellular damages of the probiotics on the HT-29 cells were investigated individually and in combination with S. Typhimurium using 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and fluorescence assays. To extract cell free supernatants (CFS) of the probiotics, they were cultured in selective media. The inhibitory activity of CFSs were then assayed against the pathogen. The gene expression of IL-8 of the HT-29 cells was evaluated by real-time PCR in all the groups. The results showed that the CFSs of three probiotics could inhibit the growth of S. Typhimurium by more than 50%. Inhibitory effects of B. indicus and B. subtilis CFSs were related to the production of pepsin-sensitive compounds, except B. coagulans in which the high inhibitory effect was due to organic acids. The spores of the three probiotics and the heat-inactivated forms of B. subtilis and B. coagulans could reduce the cytotoxicity of S. Typhimurium. The cell viability also increased applying both forms probiotics against the pathogen. In all co-culture groups, the IL-8 gene expression induced by S. Typhimurium was reduced.

CONCLUSIONS

The three Bacillus probiotics can be considered as proper candidates for the prevention and treatment of S. Typhimurium food poisoning.

SIGNIFICANCE AND IMPACT OF THE STUDY

Applying probiotics as live bacteria is universally noted in foods. This study tried to discover the effects of Bacillus probiotics in the form of spore or even heat-killed bacteria against S. Typhimurium and evaluate ratio of IL-8 gene expression in cell culture. The most effective Bacillus probiotic will be recommended. This approach will help to use probiotics as nonvegetative cells in foods to fight gastrointestinal pathogens.

The effect of Bacillus coagulans on cytotoxicity and apoptosis induced by Salmonella Typhimurium in HT-29 cell culture

BACKGROUND AND OBJECTIVES

Human epithelial cells have been widely used to study the interaction between intestinal cells and pathogens, in vitro. In this study, the effect of probiotic bacteria Bacillus coagulans and its supernatant on the growth inhibition, cytotoxicity and induction of apoptosis caused by Salmonella Typhimurium and its adhesion to HT-29 cells were investigated.

MATERIALS AND METHODS

B. coagulans supernatant was used to obtain the minimum inhibitory concentration. To evaluate the cytotoxicity and percent of apoptotic cells, B. coagulans and its supernatant (2, 4, 6 and 8% concentrations) with S. Typhimurium was added to HT-29 cells. The MTT assay was used in order to evaluate the cytotoxicity. Percent of apoptotic cells was reported using a fluorescence staining method. Additionally, the adhesion of S. Typhimurium to HT-29 cells was investigated. The effect of B. coagulans on the level of adhesion was also studied.

RESULTS

The most inhibitory effect was shown at the concentration of 80000 μg/ml supernatant of B. coagulans (54.77% ± 1.43). The simultaneous culture of S. Typhimurium with B. coagulans had the lowest amount of cytotoxicity and induced apoptosis among the all co-culture groups of S. Typhimurium with B. coagulans or its supernatant. The determined cytotoxicity and induced apoptosis were 26.06 % ± 3.79 and 17.63 % ± 2.14 respectively. In the adhesion test, it was observed that B. coagulans can significantly prevent adhesion of S. Typhimurium to HT-29 cell.

CONCLUSION

B. coagulans can reduce the adhesion, cytotoxicity and induction of apoptosis caused by S. Typhimurium in HT-29 cells in vitro.

The effects of probiotic Bacillus coagulans on the cytotoxicity and expression of alpha toxin gene of Clostridium perfringens type A

Around the world, Clostridium perfringens type A is known to be a common foodborne pathogen. Therefore, the control and treatment of food poisoning caused by this pathogen are important. This study investigated, in vitro, the effects of Bacillus coagulans and its culture extracts on alpha toxin gene expression, growth inhibition, cytotoxicity, and apoptosis induced by C. perfringens spore, germinated spore and its enterotoxin. Flow cytometry was used to evaluate the apoptosis rate, and MTT test was used to evaluate cytotoxicity. Minimum inhibitory concentration was also used to measure the percentage of inhibition in the broth medium. Finally, RT-qPCR was used to evaluate alpha toxin gene expression. The results showed that the B. coagulans culture extract was able to inhibit the growth of the germinated spore of C. perfringens. Moreover, treating the extract with pepsin can reduce growth in the broth medium. MTT and flow cytometry showed that both B. coagulans and its extract can significantly reduce the cytotoxicity and apoptosis rate induced by C. perfringens type A. In addition, it was shown that the co-culture of B. coagulans and C. perfringens decreases alpha toxin gene expression. The findings of this study indicate that B. coagulans, with growth inhibition and reduced expression of alpha toxin in C. perfringens, can reduce the cytotoxicity and apoptosis rate induced on HT-29 cells.

The evolution of chicken stem cell culture methods

1. The avian embryo is an excellent model for studying embryology and the production of pharmaceutical proteins in transgenic chickens. Furthermore, chicken stem cells have the potential for proliferation and differentiation and emerged as an attractive tool for various cell-based technologies. 2. The objective of these studies is the derivation and culture of these stem cells is the production of transgenic birds for recombinant biomaterials and vaccine manufacture, drug and cytotoxicity testing, as well as to gain insight into basic science, including cell tracking. 3. Despite similarities among the established chicken stem cell lines, fundamental differences have been reported between their culture conditions and applications. Recent conventional protocols used for expansion and culture of chicken stem cells mostly depend on feeder cells, serum-containing media and static culture. 4. Utilising chicken stem cells for generation of cell-based transgenic birds and a variety of vaccines requires large-scale cell production. However, scaling up the conventional adherent chicken stem cells is challenging and labour intensive. Development of a suspension cell culture process for chicken embryonic stem cells (cESCs), chicken primordial germ cells (PGCs) and chicken induced pluripotent stem cells (ciPSCs) will be an important advance for increasing the growth kinetics of these cells. 6. This review describes various approaches and suggestions to achieve optimal cell growth for defined chicken stem cells cultures and use in future manufacturing applications.

How wetting hysteresis influences ice adhesion strength on superhydrophobic surfaces

In this work, we measured the adhesion strength of artificially created glaze ice (similar to accreted in nature) on rough fluoropolymer-based hydrophobic surfaces with different contact angle (CA) and wetting hysteresis. The previously reported direct correlation between ice repellency and CA on superhydrophobic surfaces is shown to be only valid for surfaces with low wetting hysteresis. Another correlation was found between wetting hysteresis and ice adhesion strength on rough surfaces with similar chemistry.

Effect of essential oils in control of plant diseases

In this study, antifungal activity of some essential oils, extracted from Syzygium aromoticum, Foeniculum vulgare, Cuminum cyminum and Mentha piperita were investigated against grey mould of apple. The essential oils of S. aromaticum and F. vulgare showed considerable antifungal activities on PDA medium against Botrytis cinerea. Results indicated that the increasing of dosage of the essential oils caused to the more antifungal activity against B. cinerea in vitro condition. After 10 days, results showed that the essential oil of F. vulgare in both of the concentrations (750 and 1000 microL/L) was more effective than the essential oil of S. aromaticum against grey mould of apple and decrease the disease up to 15.5% in comparison with the check treatment (100%). After 20 days, biocontrol potential of the essential oils of S. aromaticum and F. vulgare at 1000 microL/L were more effective than the other treatments and the percentage of disease was evaluated 41.6% and 50.8%, respectively, in comparison with the check treatment (100%).

Biocontrol of Phytophthora cactorum the causal agent of root and crown rot on apple (Malus domestica) by formulated Pseudomonas fluorescens

In this study 284 isolates were isolated of apple trees' rhizosphere from Iran and 128 isolates were obtained from the collection of Research Department of Biological Control of University of Tehran. Four strains (P60, P61, P96, and P97) of Pseudomonas fluorescens were selected for greenhouse trials. The results of greenhouse trials showed dipping the crown and root of apple seedlings (MM106) combined with soil drench was more effective than dipping the crown and root on reducing the disease. After 6 weeks, strain P60 in dipping method combined with soil drench with 70% control, exhibited greatest effect on reducing the crown and root rot and was more effective than the fungicide metalaxyl-mancozeb. After 12 weeks, strains P60 and P96 in dipping method combined with soil drench with 55.6% and 44.5% control respectively, exhibited greatest effects on reducing the diseases Study of media on growth rate populations of effective strains exhibited that the beet molasses yeast extract (1:1) had more effect than nutrient broth(NB) medium. The initial high populations of powder formulations of strains P60 and P96 decreased during the storage at 4 and 25 degrees C over a 150-day period. In addition, formulations of strains stored at 4 degrees C had longer shelf life than those stored at 25 degrees C. In glasshouse trials, after 6 weeks, formulation of strain P60 and unformulated P60, obtained from NB medium and formulated P60, obtained from molasses yeast extract medium, and metalaxyl-mancozeb had highest effect on reducing the disease on apple rootstocks. After 12 weeks, formulation of strain P60 and unformulated bacteria obtained from both media, and metalaxyl-mancozeb with 57.1% control showed greatest effect on reducing the disease.

Biological control of Sclerotinia sclerotiorum (Lib.) de Bary, the causal agent of white mold, by Pseudomonas species on canola petals

Sclerotinia sclerotiorum is an important pathogen on canola. Due to the public concern over pesticide use, alternative methods of disease control, such as biological control, should be considered. Several bacterial strains were isolated from canola and soja plants. Inhibition of S. sclerotiorum by bacterial strains in vitro was assayed on PDA medium in dual culture test. Eight Pseudomonas sp. strains (PB-3, PB-4, PB-5, PB-6, PB-7, PB-8, PB-10 and PB-11) caused inhibition zone against 5. sclerotiorum hyphal growth. The biocontrol potential of the bacteria was tested in a plant assay. Disease suppression was investigated using a petal inoculation technique. Canola petals were pretreated with bacteria, and then inoculated with 5. sclerotiorum ascospores 24 h later. Greenhouse experiment showed that application of Pseudomonas sp. strains (1 x 10(8) cfu ml(-1)) effectively suppressed S. sclerotiorum (1 x 10(5) ascospores ml(-1)) on petals and all of them achieved significant (P<0.01) disease suppression. Fourteen days after inoculation, strain PB-3 had 88/7% disease control and strain PB-4 had 69/9% disease control. Result from all studies indicates PB-3 to be effective biocontrol against S. sclerotiorum of canola. PB-3, PB-4, PB-7, PB-8, PB-10 and PB-11 were identified as Pseudomonas fluorescens biovar III. PB-5 and PB-6 was identified as Pseudomonas fluorescens biovar II. Strains PB-3, PB-4, PB-6, PB-10 and PB-11 produced protease and HCN. Strain PB-5 produce protease; no HCN.

Powder formulation of Burkholderia cepacia for control of rape seed damping-off caused by Rhizoctonia solani

Talc-based formulation of Burkholderia cepaci strain Bu1 was tested as seed and soil drenchs separately for its ability to control Rhizoctonia soloni the causal agent of rape seed damping-off in greenhouse and field trials. In general, the formulated bacteria was more effective to suppress the disease than the suspension of bacteria cells in carboxymethylcellulose solution (1% w/v), in both greenhouse and field trials. The formulation of strain Bul as soil and seed treatments had the greatest effect on reducing the rape seed damping-off in greenhouse and field trials (66.7, 53.3, 64.4 and 40% respectively). The formulation of strain Bu1 as soil and seed treatments were the most effective treatments to increase the root dry weights in the infected soil in greenhouse. The formulation of strain Bul as soil drench had the greatest effect on enhancement of the fresh weight of roots and stem fresh and dry weights. The formulation of strain Bu1 stored at 4 degrees C exhibited better shelf Life and efficacy in vitro than it's counterpart stored at 25 degrees C.

Powder formulations of two strains of Bacillus subtilis for control of rape seed damping-off caused by Rhizoctonia solani

Talc-based formulations of Bacillus subtilis strains B1 and B2 were tested as seed and soil treatments separately for their ability to control Rhizoctonia solani, the causal agent of rape seed damping-off, in greenhouse and field trials. In general, the formulated bacteria was more effective to suppress the disease than the suspension of bacterial cells in carboxymethylcellulose solution (1%, w/v), in both greenhouse and field trials. The formulations of strain B1 as soil treatment and strain B2 as seed treatment in greenhouse, and the formulations of strain B2 as seed and soil treatments in field trials had the greatest effect on reducing the rape seed damping-off (66.7%, 73.3%, 41.3%, and 42.4%, respectively). The formulations of strain B1 as soil treatment and strain B2 as seed treatment were the most effective treatments to increase the root dry weights in the infected soil in greenhouse. The formulation of strain B2 as soil treatment had the greatest effect on enhancement of the fresh weight of roots and stem fresh and dry weights. The formulations of strains B1 and B2 stored at 4 degrees C exhibited better shelf life and efficacy in vitro than their counterparts stored at 25 degrees C. Long-term stability of the formulation of strain B1 was found to be better.

Composition and antifungal activity of essential oils of Mentha piperita and Lavendula angustifolia on post-harvest phytopathogens

The general antifungal activity of essential oils is well documented. The advantage of essential oils is their bioactivity in the vapor phase, a characteristic that makes them attractive as possible fumigants for stored product protection. Essential oils of aerial parts of Mentha piperita and Lavendula angustifolia were obtained with hydrodistillation and oils composition identified with GC-MS. Menthanol (36.24%) and menthone (32.42%) were the major compounds of the M. piperata essential oil. The essential oil of L. angustifolia was rich in linalool (49.2%) , linalyl acetate (12.3%), Lavendul acetate (6.5%), 4-terpineol (5.9%). Fungal toxicity of the essential oils were evaluated against three pathogenic fungi (Rhizopus stolonifer, Botrytis cinerea and Aspergillus niger) in vitro. Plate assayes showed that the different concentrations of essential oils have antifungal activity against these fungi, and the essential oil of L. angustifolia showed stronger fungistatic activity. Lavendula oil exhibited complete growth inhibition of all pathogens at 1000 ppm and minimum EC50 (311.24 ppm) resulted on B. cinerea.

Chemical composition and antifungal activity of the essential oils of three species of Artemisia on some soil-borne phytopathogens

Various species of the genus Artemisia are used for their pharmacological, antimicrobial, antioxidant activity. Three species of this genus, Artemisia scoparia, A. sieberi and A. aucheri are widely distributed in desert area of Iran. In order to identify the chemical composition, aerial parts of A. scoparia, A. sieberi and A. aucheri were collected from Bajestan (Khorasan province) at flowering stage. The essential oils were obtained by hydro-distillation of air-dried samples and their chemical composition identified by GC-MS. Oxygenated monoterpens were the major components of the oils of three species. alpha-thujone (81.7%), beta-thujone (14.5%) and 1,8-cineol (1.9%) were the major compounds in the essential oil of A. scoparia. The essential oil of A. aucheri was rich in linalool (44.1%), gernyl acetate (10.7%), (E)-citral (9.7%) and (Z)-citral (7.7%), and the essential oil of A. sieberi was rich in beta-thujone (19.8%), alpha-thujone (10.5%), camphor (19.5%), verbenol (9.7%), p-mentha-1,5-dien-8-ol (6.4) and davanone (5.8%). The essential oils of the three species were tested for their antifungal activity against some soil-borne pathogenic fungi. Results of bioassay showed that the oils of A. aucheri and A. sieberi has stronger antifungal activity. Minimum EC50 (41.406 microL/L), resulted from A. aucheri on Rhizoctonia solani. The oil of A. sieberi showed fungistatic activity against, Tiarosporella phaseolina (MIC = 1000 microL/L, EC50 = 203.419 microL/L), Fusarium moniliforme (MIC=750 microL/L, EC50 = 211.072 microL/L), Fusarium solani (MIC = 750 microL/L, EC50 = 188.134 microL/L) whereas against R. solani (MIC = 250 microL/L, EC50 = 121.798 microL/L) exhibited high fungicidal activity.

Double sine-Gordon ratchet induced by excitation of an internal mode

In a recent paper [Phys. Rev. E 69, 056612 (2004)] we showed the symmetry analysis of Flach et al. [Phys. Rev. Lett. 88, 184101 (2002)] which predicted the appearance of directed energy current in homogeneously spatially extended systems described by nonlinear field equations coupled to a heat bath in the presence of a correct choice for the time dependence of an external ac field, E(t), was due to the excitation of an internal mode. Flach applied their analysis to the sine-Gordon (SG) equation and verified the symmetry breaking numerically. In the SG case we showed the internal mode coupled to the center of the mass variable, X(t), that caused the symmetry breaking was Gamma(t) the slope of the kink. We also found that the phonon dressing of the SG kink by the ac driver, chi(t), was necessary for the occurrence of a directed energy current in the SG equation. We show in the case of the double sine-Gordon (DSG) equation that the excitation of the internal mode, R(t) (where R(t) is the separation of the two subkinks that make up the DSG soliton), combined with the phonon dressing of the DSG soliton also causes a directed energy current.

Soliton ratchets induced by excitation of internal modes

Recently Phys. Rev. Lett. 88, 184101 (2002)]] used a symmetry analysis to predict the appearance of directed energy current in homogeneously spatially extended systems coupled to a heat bath in the presence of an external ac field E (t). Their symmetry analysis allowed them to make the right choice of E (t) so as to obtain symmetry breaking which causes directed energy transport for systems with a nonzero topological charge. Their numerical simulations verified the existence of the directed energy current. They argued that the origin of their strong rectification in the underdamped limit is due to the excitation of internal modes and their interaction with the translational kink motion. The internal mode mechanism as a cause of current rectification was also proposed by Salerno and Zolotaryuk [Phys. Rev. E. 65, 056603 (2002)]]. We use a rigorous collective variable for nonlinear Klein-Gordon equations to prove that the rectification of the current is due to the excitation of an internal mode Gamma (t), which describes the oscillation of the slope of the kink, and due to a dressing of the bare kink by the ac driver. The internal mode Gamma (t) is excited by its interaction with the center of mass of the kink, X (t), which is accelerated by E (t). The external field E (t) also causes the kink to be dressed. We derive the expressions for the dressing and numerically solve the equations of motion for Gamma (t), X (t), and the momentum P (t), which enable us to obtain the explicit expressions for the directed energy current and the ac driven kink profile. We then show that the directed energy current vanishes unless the slope Gamma (t) is a dynamical variable and the kink is dressed by the ac driver.

Premarital sexual, child rearing, and family attitudes of Iranian men and women in the United States and in Iran

Sexual, child rearing, and family attitudes of 160 Iranian immigrants in the United States (61 men, 99 women) and 97 Iranians (55 men, 42 women) in Iran were compared. Iranians in the United States in general, and women in particular, compared with their counterparts in Iran, expressed more permissive attitudes toward premarital sex and sex education, more tolerance toward homosexuality, and a greater acceptance of marital dissolution. Iranians in both countries assigned a high value to the maternal role and to family loyalty but did not endorse unrestricted freedom for youngsters. Influences of attitudinal disparity on interpersonal and family relationships are discussed, and implications for marriage counseling and family therapy are suggested.

High-pressure apparatus for dielectric measurements in high frequency

The present article describes an experimental apparatus for the measurement of low-loss dielectric material under conditions of high pressures (maximum pressure 1500 bars) and high frequencies (1-15 MHz.) The measurements of these losses are based on the classical method of the Q-meter with a general Radio type 1690-A sample holder, located in a high-pressure bomb. All the manual operations made on the holder during the measurements are controlled by dc motors. The first results have shown that the dielectric losses of polyethylene (PE) vary with the pressure. This apparatus will later be used in the measurement of the dielectric losses of the insulating materials used for submarine telecommunication cables.

A useful sign in differentiation of p-a from a-p chest roentgenogram

Differentiation of antero-posterior (a-p) from postero-anterior (p-a) projections of chest roentgenograms is practical with ease and reliability by connecting the two outermost points of the junction of the first and second ribs on the plain film and observing its relation to the superior margin of the lung apex and inferior border of the posterior part of the second rib. Greater than 92 percent accuracy was obtained when this criterion was used to evaluate 500 p-a and 500 a-p chest roentgenogram, regarding the standard technical datas.