The role of enzymes in the angiogenic activity of Hancornia speciosa latex

The Hancornia speciosa latex has shown angiogenic activity. Angiogenesis plays a major role in wound healing, and materials that stimulate this process could be used to develop drugs. This study aimed to explain the role of proteins in the H. speciosa serum fraction latex in angiogenesis. Hence, this material was treated with proteinase K and the proteins were inactivated. After protein inactivation, angiogenic activity was assessed with the chick chorioallantoic membrane assay. The result showed that the proteins in the serum fraction are responsible for angiogenic activity. Then, the total protein content in the serum fraction and its enzymatic activity were investigated. The low protein content observed in the H. speciosa serum fraction latex suggests that this biomaterial could be used to develop new drugs with a hypoallergenic response. Despite the low protein content, there was a significant enzymatic activity of at least three enzymes in the serum fraction latex: ß-1,3 glucanase, ß-glucosidase, and proteases. These enzymes seem to influence the healing process, assisting debridement, extracellular matrix remodeling, and collagen deposition, and decreasing the chances of contamination by microorganisms. In conclusion, the enzymes in the H. speciosa serum latex are associated with the angiogenic activity of this biomaterial and may be used to assist the wound healing process.

D-RADA16-RGD-Reinforced Nano-Hydroxyapatite/Polyamide 66 Ternary Biomaterial for Bone Formation

BACKGROUND: Nano-hydroxyapatite/polyamide 66 (nHA/PA66) is a composite used widely in the repair of bone defects. However, this material is insufficient bioactivity. In contrast, D-RADA16-RGD self-assembling peptide (D-RADA16-RGD sequence containing all D-amino acids is Ac-RADARADARADARADARGDS-CONH2) shows admirable bioactivity for both cell culture and bone regeneration. Here, we describe the fabrication of a favorable biomaterial material (nHA/PA66/D-RADA16-RGD). METHODS: Proteinase K and circular dichroism spectroscopy were employed to test the stability and secondary structural properties of peptide D-RADA16-RGD respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the surface of these materials. Confocal laser scanning (CLS), cell counting kit-8 tests (CCK-8), alizarin red S staining, cell immunofluorescence analysis and Western blotting were involved in vitro. Also biosafety and bioactivity of them have been evaluated in vivo. RESULTS: Proteinase K and circular dichroism spectroscopy demonstrated that D-RADA16-RGD in nHA/PA66 was able to form stable-sheet secondary structure. SEM and TEM showed that the D-RADA16-RGD material was 7–33 nm in width and 130–600 nm in length, and the interwoven pore size ranged from 40 to 200 nm. CLS suggests that cells in nHA/PA66/D-RADA16-RGD group were linked to adjacent cells with more actin filaments. CCK-8 analysis showed that nHA/PA66/D-RADA16-RGD revealed good biocompatibility. The results of Alizarin-red S staining and Western blotting as well as vivo osteogenesis suggest nHA/PA66/D-RADA16-RGD exhibits better bioactivity. CONCLUSION: This study demonstrates that our nHA/PA66/D-RADA16-RGD composite exhibits reasonable mechanical properties, biocompatibility and bioactivity with promotion of bone formation.

An Alternative Method for Extracting Plasmodium DNA from EDTA Whole Blood for Malaria Diagnosis

Molecular techniques have been introduced for malaria diagnosis because they offer greater sensitivity and specificity than microscopic examinations. Therefore, DNA isolation methods have been developed for easy preparation and cost effectiveness. The present study described a simple protocol for Plasmodium DNA isolation from EDTA-whole blood. This study demonstrated that after heating infected blood samples with Tris–EDTA buffer and proteinase K solution, without isolation and purification steps, the supernatant can be used as a DNA template for amplification by PCR. The sensitivity of the extracted DNA of Plasmodium falciparum and Plasmodium vivax was separately analyzed by both PCR and semi-nested PCR (Sn-PCR). The results revealed that for PCR the limit of detection was 40 parasites/μl for P. falciparum and 35.2 parasites/μl for P. vivax, whereas for Sn-PCR the limit of detection was 1.6 parasites/μl for P. falciparum and 1.4 parasites/μl for P. vivax. This new method was then verified by DNA extraction of whole blood from 11 asymptomatic Myanmar migrant workers and analyzed by Sn-PCR. The results revealed that DNA can be extracted from all samples, and there were 2 positive samples for Plasmodium (P. falciparum and P. vivax). Therefore, the protocol can be an alternative method for DNA extraction in laboratories with limited resources and a lack of trained technicians for malaria diagnosis. In addition, this protocol can be applied for subclinical cases, and this will be helpful for epidemiology and control.

The use of Proteinase K to access genitalia morphology, vouchering and DNA extraction in minute wasps

ABSTRACT Genitalia are rich source of characters in insect taxonomy. Usually, they are examined after dissection and cleaning with potassium hydroxide (KOH), procedure that may damage both genital morphological structures and intracellular molecular contents. Enzymatic procedure with Proteinase K has been used to clean muscle off the genitalia while extract DNA, but its damage to the genital structures has not been evaluated. Herein, we qualitatively compare the use of KOH and Proteinase K to prepare genital structures in minute insects (Hymenoptera: Bethylidae). We show that Proteinase K is better to preserve the genital structure and provides quality DNA.

Amplification of distinct α-synuclein fibril conformers through protein misfolding cyclic amplification

Amyloid fibril formation has been implicated in the pathogenesis of neurodegenerative diseases. Fibrillation generates numerous conformers. Presumably, the conformers may possess specific biological properties, thus providing a biochemical framework for strains of prions. However, the precise relationship between various fibril conformers and their pathogenic functions has not been determined because of limited accessibility to adequate amounts of fibrils from tissue samples. α-Synuclein is one such protein, and it has been implicated in Parkinson disease. Using a technique known as protein misfolding cyclic amplification, originally developed for amplifying prions, we established a procedure through which the amplification of α-synuclein fibrils is possible. With a trace amount of seeds, we succeeded in amplifying α-synuclein fibrils. The replication of the seeds was faithful in terms of conformation even after multiple rounds of cyclic amplification. Moreover, two transgenic mouse strains each representing a distinct synucleinopathy were used to investigate different conformers by using this technique. The amplified α-synuclein fibrils derived from the tissue extracts of these two strains led to the production of two different fibril conformers with distinct proteinase K digestion profiles. Together, our results demonstrated that a trace amount of α-synuclein fibrils in tissue extracts could be amplified with their conformations conserved. This procedure should be useful in amplifying α-synuclein fibrils from the brains and body fluids of patients afflicted with synucleinopathies and may serve as a potential diagnostic tool for Parkinson disease and other synucleinopathies.

Comparative Evaluation of Three Homogenization Methods for Isolating Middle East Respiratory Syndrome Coronavirus Nucleic Acids From Sputum Samples for Real-Time Reverse Transcription PCR

BACKGROUND: Real-time reverse transcription PCR (rRT-PCR) of sputum samples is commonly used to diagnose Middle East respiratory syndrome coronavirus (MERS-CoV) infection. Owing to the difficulty of extracting RNA from sputum containing mucus, sputum homogenization is desirable prior to nucleic acid isolation. We determined optimal homogenization methods for isolating viral nucleic acids from sputum. METHODS: We evaluated the following three sputum-homogenization methods: proteinase K and DNase I (PK-DNase) treatment, phosphate-buffered saline (PBS) treatment, and N-acetyl-L-cysteine and sodium citrate (NALC) treatment. Sputum samples were spiked with inactivated MERS-CoV culture isolates. RNA was extracted from pretreated, spiked samples using the easyMAG system (bioMérieux, France). Extracted RNAs were then subjected to rRT-PCR for MERS-CoV diagnosis (DiaPlex Q MERS-coronavirus, SolGent, Korea). RESULTS: While analyzing 15 spiked sputum samples prepared in technical duplicate, false-negative results were obtained with five (16.7%) and four samples (13.3%), respectively, by using the PBS and NALC methods. The range of threshold cycle (Ct) values observed when detecting upE in sputum samples was 31.1-35.4 with the PK-DNase method, 34.7-39.0 with the PBS method, and 33.9-38.6 with the NALC method. Compared with the control, which were prepared by adding a one-tenth volume of 1:1,000 diluted viral culture to PBS solution, the ranges of Ct values obtained by the PBS and NALC methods differed significantly from the mean control Ct of 33.2 (both P<0.0001). CONCLUSIONS: The PK-DNase method is suitable for homogenizing sputum samples prior to RNA extraction.

Modified Method of Multilocus Sequence Typing (MLST) for Serotyping in Salmonella Species

Multilocus sequence typing (MLST) of Salmonella is useful method for replacing serotyping using antisera but is limited by difficulties associated with in polymerase chain reaction (PCR). We optimized the PCR reaction, especially annealing temperature and extension time (94degrees C for 2 min; 40 cycles at 94degrees C for 30 sec, 56.8degrees C for 1 min, 72degrees C for 2 min; and 72degrees C for 10 min). The degradation of PCR product by thermostable nucleases was inhibited by using template DNAs treated proteinase K or purified by a commercialized preparation kit. The resulting modified MLST was used as accurate and fast typing method.

Evaluación de un método de extracción y purificación de DNA a partir de tejido muscular fijado en formaldehido de cadáveres no identificados / Evaluation of a method of extracting and purifying DNA from muscle tissue fixed in formaldehyde unidentified bodies / Avaliação de um método de extracção e purificação de ADN a partir de tecido muscular fixado em formaldeído corpos não identificados

La obtención de DNA humano en buena cantidad y alta pureza a partir de tejido muscular fijado en Formaldehido no tamponado es de suma importancia en la amplificación por la Reacción en Cadena de la Polimerasa (PCR) para su aplicación en estudios de identificación y filiación genética. En este estudio se evaluó la eficiencia del Kit QIAampR DNA FFPE TISSUE y una modificación del mismo basado en lavados con PBS y el tiempo de digestión con proteinasa K, frente a la cantidad y calidad de este ácido nucléico. Las diferencias fueron significativas entre los tiempos de acción con la proteinasa K (PK) en relación a la cantidad y en la pureza producto de los lavados del tejido muscular previa extracción. Estos resultados proporcionan una pauta para el diseño de experimentos de acuerdo con el efecto de la fijación, optimizando recursos humanos e insumos.

Obtaining human DNA in large quantity and high purity from muscle tissue fixed in formaldehyde unbuffered is of utmost importance in amplification by Chain Reaction (PCR) for application in identification studies and genetic affiliation. In this study, the efficiency of DNA FFPE TISSUE QIAampR Kit and a modification thereof based washes with PBS and the time of digestion with proteinase K, compared to the amount and quality of the nucleic acid were evaluated. Differences were significant between the exposure times with proteinase K (PK) in relation to the quantity and purity of the product prior washings muscle tissue extraction. These results provide a guideline for the design of experiments according to the effect of fixing, optimizing human resources and inputs.

A obtenção de DNA humano em grande quantidade e de alta pureza a partir de tecido muscular fixado em formol não tamponado é de extrema importância para a amplificação por Reacção em Cadeia (PCR), para sua aplicação em estudos de identificação e filiação genética. Neste estudo, a eficácia do kit QIAampR DNA FFPE TISSUE e uma modificação do processo por lavagens com PBS e o tempo de digestão com proteinase K, em comparação com a quantidade e a qualidade do ácido nucléico desta base. As diferenças foram significativas entre os tempos de exposição com proteinase K em relação à quantidade e pureza produto das lavagens do tecido muscular extraída previamente. Estes resultados fornecem uma diretriz para o desenho de experimentos de acordo com o efeito de fixação, otimizando recursos humanos e insumos.

Fermentation of Bacillus subtilis ge25 strain and preliminary study on its antagonistic substances / 中国中药杂志

Panax ginseng is one of the most important traditional Chinese herbal medicine, soil borne diseases influenced the yield and quality severely. In our previous work, endophytic Bacillus subtilis ge25 strain was isolated from ginseng root, and which showed significant antagonistic activity against several most destructive ginseng phytopathogens. In the present work, crude protein and lipopeptid extracts were prepared from LB and Landy supernate by salting out, acid precipitation methods respectively. The antagonistic activity of crude extracts and stability to temperature and protease digestion were examined by ginseng phytopathogen Alternaria panax. Results showed that, the antagonistic activity of crude protein extracts from LB culture was complete and partially lost when treated by high temperature and proteinase K. However, crude lipopeptid from Landy culture showed significant stabile antagonistic activity to them. Acid-hydrolyzation and TLC-bioautography analysis showed, that the crude lipopeptide contained at least one cyclic lipopeptide. In consideration of the stability and perfect antagonistic activity of ge25, further researches will promote the biocontrol of ginseng diseases in the field.

The Analysis of Reclaiming Ratio for 3 Diatom Species from Experimentally Drowned Animal Organs / 대한법의학회지

Drowning is one of the most common causes accidental death worldwide, but its diagnosis remains a challenging task in forensic pathology. Several authors have suggested that diatom analysis be conducted via an enzymatic digestion method that uses proteinase K to provide objective evidence for drowning; we employed this method in our study because of its superior applicability as compared to the conventional disorganization methods. The purpose of this study was to examine the reclaiming ratio of diatoms from experimentally drowned animal organs, which could be influenced by diatom morphology. The authors injected 3 diatoms species (Cyclotella striata, Navicula incerta, and Pleurosigma angulatum) into a rat's airway and compared the detection rate to investigate the factors that influence the sensitivity of diatom analysis. The results are as follows: (1) Average reclaiming ratio in the lungs was 81.07 for Navicula incerta, 48.26 for Cyclotella striata, and 5.35 for Pleurosigma angulatum. (2) The detection rates from the closed organs in 15 experimental animals were highest in the kidney (73%, 11/15), followed by the heart (67%, 10/15), brain (60%, 9/15), and liver (53%, 8/15). (3) Two Cyclotella striata was detected in the kidney of postmortem control group which suggest the possibility of contamination during laboratory procedure. In conclusion, the authors propose that diatom size could be a significant influencing factor for diatom extraction from the organs of drowned bodies; therefore, the results of diatom analysis must be interpreted after considering the diatom population of the drowning medium at the scene and the possibility of contamination during the laboratory procedure.

Low volume amplification in single cell separation and inspection / 法医学杂志

OBJECTIVE@#To establish optimal amplification conditions with the application of 0.2 mL test tube in single cell separation and inspection.@*METHODS@#Oral epithelium cell suspension was prepared. Five or ten cells were collected with 0.2 mL test tube. Then DNA were amplified with Identifiler Plus kit in three different conditions in which the proteinase K addition, gold enzyme concentration in PCR reaction, and PCR reaction cycles were adjusted separately. Finally the detection rate, allelic dropout rate and artificial alleles were compared among the groups.@*RESULTS@#In these 3 different conditions: addition of proteinase K, addition of 0.4 microL gold enzyme in PCR reaction, and use of 32 cycles, the detection rate was higher and allelic dropout rate was lower than the other conditions.@*CONCLUSION@#In single cell separation and inspection, the usage of 0.2 mL test tube could be an effective supplement to chip-low volume amplification.

The Comparison of Plankton Detection by Two Analysis Methods in the Seawater of Gageo Island / 대한법의학회지

The acid digestion method for extracting diatoms has been widely used to confirm death by drowning, but its reliability is still disputed because some diatoms can be destroyed during the extraction process due to treatment with strong acid and heat. There is a need to develop an efficient and reliable digestive method to overcome the limitation of the present analytical procedure. In this study, the reliability and efficacy of quantitative and qualitative diatom analysis from seawater by an enzymatic digestion method was evaluated. We confirmed the merit of the enzymatic method that used proteinase K instead of nitric acid in the conventional method. As a result, the enzymatic method showed a higher recovery ratio and better preservation of the diatom structure, which is essential for quantitative (diatom density) and qualitative (species) interpretation of diatom analysis. This result indicates that the enzymatic method can replace the conventional acid digestion method to confirm cases of death by drowning since it is more reliable and yields conclusive results.

A redox process of ethanethiol group increases formation of beta-sheet structure and amyloid fibrils of wild type human prion protein / 病毒学报

In order to explore the potential influences of the disulfide bridge on the physical and chemical properties of PrP protein, the expressed recombinant human wild-type PrP protein was purified for using in an established redox process for the reduction and oxidation of the ethanethiol group within PrP. Sedimentation tests illustrated that redox process remarkably promoted the aggregation of recombinant PrP. Thioflavin T binding assay revealed an enhanced fibrillization of the recombinant human PrP after redox process. Far-UV circular dichroism demonstrated that the PrP treated with redox process showed a significant p-sheet rich structure. Furthermore, PrP-specific Western blot identified that the recombinant PrP after redox possessed stronger proteinase K-resistance. Those data indicates that the formation of the disulfide bridge induces the alteration of the secondary structure and enhances the progresses of aggregation and fibrillization of PrP protein.

Protective Effects of Immunization with Proteinase, Phospholipase and Cell Wall Proteins of Candida albicans in Mice Candidosis / 대한의진균학회지

BACKGROUND: The opportunistic fungus Candida albicans is a major pathogen especially to immunocompromised patients. OBJECTIVES: We examined the protective effect of the active and passive immunizations to evaluate the applicability for the treatment of candidosis in Candida-infected mice model. METHODS: Candida cell wall components were obtained by treatment of lyticase, proteinase K, and dithiothreitol. The proteinase was purified from the culture filtrates of C. albicans using a series of chromatographic steps consisting of DEAE-Sepharose FF, Sephacryl S-200 HR and size-exclusion high performance liquid chromatography. The phospholipase was purified from the culture supernatant of C. albicans with DEAE column chromatography, reverse phase column chromatography, revere phase HPLC and size-exclusion HPLC. Antibodies to cell wall protein components, proteinase and phospholipase were produced by immunization into mice of same strain. RESULTS: The mean survival times of active and passive immunized mice groups were longer than those of non-immunized groups. CONCLUSION: These results showed that immunization with proteinase and its antibody were the most effective to prolong survival time in Candida-infected mice.

Expression of cytosolic PrP and analysis of its cytotoxic activities / 病毒学报

In order to study the physicochemical characteristics of cytosolic PrP (CytoPrP) and evaluate its possible influence on cell viability, a recombinant plasmid expressing human CytoPrP eukaryoticly was constructed and transfected into human neuroblastoma cell line SH-SY5Y transiently. Proteinase-resistant activities of CytoPrP were evaluated by a proteinase K (PK) digestion and cytotoxic effects of CytoPrP were tested by MTT assay and Trypan Blue cell-counting. The presence of CytoPrP in cytoplasm after transfection was controlled by the presence of protease inhibitor. Compared with wild-type PrP, CytoPrP possessed relatively stronger PK-resistant activities. Obvious cytotoxic effects were observed in the cells after inducement of CytoPrP in cytoplasm by protease inhibitor, showing a dose-dependent manner. The results provide useful scientific evidences for further studies of potential role of CytoPrP in pathological mechanism of prion disease.

Identification of the Proteinase K-resistant Antigen of Orientia tsutsugamushi by Monoclonal Antibodies

Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular bacterium that replicates in the cytosol of host cells. Although several protein antigens have been characterized and cloned, little information exists regarding the polysaccharide antigen of this bacterium. In this study, we characterized two monoclonal antibodies, NT19 and WT14, against the proteinase K-resistant antigen of O. tsutsugamushi. Western blot analysis showed that MAb NT19 and WT14 strongly recognized two antigenic bands with molecular masses of 20 kDa and 24 kDa, which were resistant to proteinase K digestion. We suggest that the proteinase-resistant antigen might be polysaccharide. One patient serum reacted with a 24 kDa band that was similar to a band observed by WT14, suggesting the possibility of the role of this proteinase-resistant antigen as an antigenic molecule in human infection.

Comparative research of the influence factors of DNA extraction of bloodstain on the filter paper with Chelex-100 method / 法医学杂志

OBJECTIVE@#To improve DNA extraction from bloodstain on the filter paper and to establish a rapid, simple, and cost-effective method for DNA extraction suitable for database construction.@*METHODS@#Seven hundred and fifty two aged bloodstains on filter paper were randomly divided into four groups. The four different DNA extraction methods were compared with each other, and two DNA extraction methods used for 63 fresh bloodstains on filter paper were also compared with each other.@*RESULTS@#There were no statistically significant differences observed among the four DNA extraction methods (P > 0.05) for aged bloodstains on filter paper; But the difference between the two DNA extraction methods for fresh bloodstains on filter paper was obviously (P < 0.05).@*CONCLUSION@#Extraction of DNA samples from aged bloodstains on filter paper can be accomplished by using Chlex-100 methodology directly with no need to wash the bloodstains.

Dynamics of in vitro amyloid fiber formation of yeast prion protein Sup35NM / 中华实验和临床病毒学杂志

<p><b>BACKGROUND</b>To investigate the dynamics of amyloid fiber formation of yeast (Saccharomyces cerevisiae) prion protein Sup35NM under the native condition to provide materials and clues for the elucidation of amyloid fiber formation.</p><p><b>METHODS</b>The Sup35NM gene was cloned and expressed in E. coli. The recombinant Sup35NM protein was purified under denaturing conditions through Nickel-Sepharose chromatography. Aliquots were removed at designated time points for transmission electron microscopy (TEM), circular dichroism (CD) spectra, protease K resistance assay, as well as thioflavin T (ThT) binding assay.</p><p><b>RESULTS</b>The Sup35NM expressed and purified under denaturing conditions. The morphological alteration of the Sup35NM in PBS (pH7.4) during the protein aggregation and amyloid fiber formation was visualized by TEM. The CD assay showed that the course of amyloid fiber formation underwent a conformational shift from alpha-helix to beta-sheet. The fibers had higher capacity of resistance to protease K digestion compared to the monomers. ThT fluorescence assay displayed a rapid growth phase before reaching a final equilibrium phase during the fiber formation, and the higher concentration of Sup35NM could greatly accelerate the fiber formation in vitro.</p><p><b>CONCLUSION</b>Yeast prion protein Sup35NM forms amyloid readily under native conditions in vitro. The dynamics of Sup35NM amyloid formation may provide supporting evidences for the nucleating polymerization models of amyloid fiber formation.</p>

Genomic gain and loss of cervical cancer using BAC Chip / 대한산부인과학회지

OBJECTIVE: Cervical cancer has long been linked to the sexually transmitted human papillomavirus (HPV), and the oncoproteins E6 and E7 disrupt the functions of tumour suppressor genes, resulting in genetic alteration. It was shown that loss of heterozygosity at 6p is a common genetic alteration in cervical cancer. However, the molecular genetics of cancer have only recently been understood, and for the development of cervical cancer additional genetic alterations in host cell genes are required. The present study has identified the differential changes of the cervical cancer-associated genetic alterations by a genome-wide array based comparative genomic hybridization (array-CGH). METHODS: We analyzed 15 cases of cervical cancer from St. Mary's hospital of The paraffin-fixed tissue samples were microdissected under microscope and DNA was extracted by the procedures of proteinase K digestion and chloroform extraction. Array-based CGH and genomic PCR were carried out with statistical analyses such as hierarchical clustering and Gene Ontology. The BAC array used in this study consisted of 1,440 human BACs, the space among the clones were approximately 2.08 megabase (Macrogen, Seoul, Korea). RESULTS: All of 15 cases of cervical cancer showed specific gains and losses. The analysis limit of average gains and losses was 53%. A significant positive correlation was found between 1p36.32, 3p14.2, 3q27.1, 7p21.1, 8q24.3 and 11q13.1 changes through the cervical carcinogenesis. The high-level of gain regions, BAC clones encoded GSDMDC1, RECQL4, TP73, ABCF3, ALG3, HDAC9, ESRRA and RPS6KA4 genes. Frequently gained BAC clones encoded genes were PRSS8, FUS, COL18A1, PCOLN3, MAFG and ASPSCR1. The genes encoded by frequently lost BAC clones were PTPRG, GRM7, ZDHHC3, EXOSC7, LRP1B and NR3C2. Also, hierarchical clustering of the expression data readily distinguished genomic alterations in cervical cancer. A subset of cellular processes from each gene was clustered by Gene Ontology database. CONCLUSION: Using Array-CGH, genomic alterations related to cervical cancer were identified to determine whether induction of chromosomal imbalances occurs prior to carcinogenesis. The high resolution of array-CGH combined with human genome database would give a chance to find out possible target genes present in the gained or lost clones.

Evaluation of a 16S rDNA PCR Assay for Detection of Bacterial Pathogens in Blood Culture Broth / 대한임상미생물학회지

BACKGROUND: Rapid detection of pathogens in blood is important in patient management, because the mortality rate associated with bloodstream infections is very high. We evaluated the efficiency of a 16S rDNA PCR assay for the detection of various pathogens in blood culture broth in METHODS: 16S rDNA PCR was performed on 221 blood culture bottles consisting of 99 culturepositive and 122 culture-negative samples. The results were compared with conventional culture methods. We also compared the efficiency of three DNA extraction and purification methods using proteinase K, triton X-100, and benzyl alcohol-guanidine DNA extraction of blood culture broths. RESULTS: The 16S rDNA PCR method detected 95 (12 Staphylococcus aureus, 27 coagulase negative staphylococci, 10 enterococci, 5 streptococci, 37 gram negative bacilli, 4 corynebacteria) of 99 positive culture bottles. Four false-negative results were obtained for bottles containing 2 Corynebacterium, 1 Escherichia coli, and 1 S. aureus species. All 122 bottles that showed no blood culture growth were negative by 16S rDNA PCR. Overall, the sensitivity, specificity, positive predictive values and negative predictive values of 16S rDNA PCR relative to the culture results were 96.0%, 100%, 100%, and 96.8%, respectively. Among the three DNA extraction methods, the benzyl alcohol-guanidine method was most effective. CONCLUSION: The 16S rDNA PCR assay is a rapid and efficient means of detecting various pathogens in the blood and has great potential for use in the clinical microbiology laboratory.