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1.
Clin Orthop Surg ; 14(1): 76-89, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35251544

ABSTRACT

BACKGROUND: Stenotic femoral intercondylar notch is considered as a risk factor for anterior cruciate ligament (ACL) injury and three-dimensional notch volume is used as a marker for the injury. The primary purpose of this study was to assess the difference in notch volume between the ACL-injured and uninjured in men and women combined or stratified by sex. The secondary purpose was to assess the difference in notch volume between the ACL-intact men and women. METHODS: A search of PubMed/Medline, Scopus, Google Scholar, and Cochrane databases from inception to December 9, 2020, was conducted without restrictions using the following terms: ACL, notch, volume, notch volume, femoral notch volume, and intercondylar notch volume. Studies that compared the ACL-injured with uninjured controls were included. Independent extraction of articles by two authors using predefined data fields including study quality indicators was done. All pooled analyses were based on the inverse-variance weighted random effects model and mean difference was chosen as the effect measure. RESULTS: Nine studies (1,169 knees) qualified for overall analysis (both sexes combined) and significant heterogeneity was observed, which disappeared after pooling studies with age-sex matched controls and those without. Notch volume in the ACL-injured was 0.75 cm3 (95% confidence interval [CI], 0.53-0.96 cm3), which was smaller than that in the age- and sex-matched controls. Six studies qualified for analysis in men. Notch volume in the ACL-injured men was smaller, especially when non-contact ACL injury was considered (1.40 cm3; 95% CI, 1.08-1.73 cm3). Five studies qualified for analysis in women and ACL-injured women had smaller notch volume irrespective of the mechanism of injury (0.38 cm3; 95% CI, 0.18-0.59 cm3). Notch volume of the uninjured men was larger than that of the uninjured women (1.86 cm3; 95% CI, 1.54-2.18 cm3). CONCLUSIONS: ACL-injured adults have smaller notch volume than the age- and sex-matched controls. Non-contact ACL-injured males have smaller notch volume compared to ACL-intact males. ACL-injured females have smaller notch volume irrespective of the nature of injury. Men have higher notch volume than women. The quality of evidence is very low to low.


Subject(s)
Anterior Cruciate Ligament Injuries , Anterior Cruciate Ligament , Adult , Anterior Cruciate Ligament Injuries/diagnostic imaging , Female , Femur/diagnostic imaging , Humans , Knee Joint , Magnetic Resonance Imaging , Male , Risk Factors
2.
Article in English | WPRIM (Western Pacific) | ID: wpr-914118

ABSTRACT

Background@#Stenotic femoral intercondylar notch is considered as a risk factor for anterior cruciate ligament (ACL) injury and three-dimensional notch volume is used as a marker for the injury. The primary purpose of this study was to assess the difference in notch volume between the ACL-injured and uninjured in men and women combined or stratified by sex. The secondary purpose was to assess the difference in notch volume between the ACL-intact men and women. @*Methods@#A search of PubMed/Medline, Scopus, Google Scholar, and Cochrane databases from inception to December 9, 2020, was conducted without restrictions using the following terms: ACL, notch, volume, notch volume, femoral notch volume, and intercondylar notch volume. Studies that compared the ACL-injured with uninjured controls were included. Independent extraction of articles by two authors using predefined data fields including study quality indicators was done. All pooled analyses were based on the inverse-variance weighted random effects model and mean difference was chosen as the effect measure. @*Results@#Nine studies (1,169 knees) qualified for overall analysis (both sexes combined) and significant heterogeneity was observed, which disappeared after pooling studies with age-sex matched controls and those without. Notch volume in the ACLinjured was 0.75 cm3 (95% confidence interval [CI], 0.53–0.96 cm3 ), which was smaller than that in the age- and sex-matched controls. Six studies qualified for analysis in men. Notch volume in the ACL-injured men was smaller, especially when non-contact ACL injury was considered (1.40 cm3 ; 95% CI, 1.08–1.73 cm3 ). Five studies qualified for analysis in women and ACL-injured women had smaller notch volume irrespective of the mechanism of injury (0.38 cm3 ; 95% CI, 0.18–0.59 cm3 ). Notch volume of the uninjured men was larger than that of the uninjured women (1.86 cm3 ; 95% CI, 1.54–2.18 cm3 ). @*Conclusions@#ACL-injured adults have smaller notch volume than the age- and sex-matched controls. Non-contact ACL-injured males have smaller notch volume compared to ACL-intact males. ACL-injured females have smaller notch volume irrespective of the nature of injury. Men have higher notch volume than women. The quality of evidence is very low to low.

3.
Indian J Otolaryngol Head Neck Surg ; 71(Suppl 3): 1805-1809, 2019 Nov.
Article in English | MEDLINE | ID: mdl-31763250

ABSTRACT

Odontogenic etiology accounts for 10-12% of cases of maxillary sinusitis. Although uncommon, direct spread of dental infections into the maxillary sinus is possible due to the close relationship of the maxillary posterior teeth to the maxillary sinus. An odontogenic infection is a polymicrobial aerobic-anaerobic infection, with anaerobes out numbering the aerobes. Diagnosis requires a thorough dental and clinical evaluation, including radiographs. Management of sinus disease of odontogenic origin often requires medical treatment with appropriate antibiotics, surgical drainage when indicated, and treatment to remove the offending dental etiology. A 35-year-old, non-smoking woman visited our clinic, with a history of 6 months of facial pain, purulent nose discharge, and a foul taste in her mouth. The patient was otherwise healthy. Nasal endoscopy showed purulent discharge coming from the left middle meatus with a congested nasal mucosa and with a past history of dental treatments. CT PNS showed fractured free floating and an impacted foreign body through the premolar tooth and a right maxillary polyp with evidence of similar dental procedure done bilaterally. Functional endoscopic sinus surgery with extraction of the affected tooth and closure of oroantral fistula was done. The association between an odontogenic condition and maxillary sinusitis requires a thorough dental examination of patients with sinusitis. Concomitant management of the dental origin and the associated sinusitis will ensure complete resolution of the infection and may prevent recurrences and complications. A combination of a medical and surgical approach is generally required for the treatment of odontogenic sinusitis. An endoscopic shaver-assisted approach to is a reliable, minimally invasive method associated with less morbidity and lower incidence of complications.

4.
Eur J Prosthodont Restor Dent ; 27(2): 66-75, 2019 May 30.
Article in English | MEDLINE | ID: mdl-31145558

ABSTRACT

INTRODUCTION: This study aimed at exploring clinical translation of additive manufacturing methods for fabrication of inlay restorations. MATERIALS AND METHODS: On a selected human premolar tooth sample an inlay cavity was prepared. A silicon impression of the tooth was recorded and ten die-casts were poured. Ten inlay wax patterns were fabricated using traditional method. An optical impression of the tooth model was obtained and 20 computeraided inlay designs were fabricated and optimised for additive manufacturing. Ten models were fabricated by micro-stereolithography and the other ten were fabricated using selective laser sintering. 30 inlay patterns were cast into cobalt chromium metal inlays. For 30 metal inlays, marginal and internal gaps were measured using a silicone-replica-technique, observed under a scanning electron microscope. RESULTS: The measured internal gaps were: Internal-gaps in Conventional lost wax technique (138 ± 8.7), micro-stereolithography (200 ± 7.4) and selective laser sintering (203 ± 11.8). The marginal gaps were: Conventional lost wax technique (162.12 ± 6.8), micro-stereolithography (198 ± 10.3) and scanning laser sintering (203 ± 6.6) Conclusions: The marginal gap and internal gap of a conventional lost wax technique were significantly improved compared with microstereolithography and selective laser sintering (P⟨0.05). However, according to previous criteria for maximum allowable discrepancy (100 - 200 µm) microstereolithography may represent a potential future alternative for indirect inlay fabrication.


Subject(s)
Computer-Aided Design , Dental Marginal Adaptation , Dental Prosthesis Design , Inlays , Dental Materials , Humans
5.
Indian J Otolaryngol Head Neck Surg ; 58(1): 63-8, 2006 Jan.
Article in English | MEDLINE | ID: mdl-23120240

ABSTRACT

Foreign body ingestion is a common problem frequently encountered in both children and adults. A total number of 152 patients (104 children and 48 adults) with ingested foreign body admitted in our hospital are reviewed. Location of foreign body was made out by radiological examination. History of having swallowed foreign body was the most common symptom in both blunt and sharp foreign bodies. Endoscopic removal of foreign body was done under general anaesthesia for all cases, except one in which foreign body was removed by open surgical method. Blunt, foreign bodies were common among children, where as meat with bone was common in adults (19/48). Most of blunt foreign bodies in children (83.5%) were impacted in post cricoid region. Where as in adutls, the foreign bodies (37.5%) were seen in upper oesophagus. Retropharyngeal abscess was seen in 2 cases, which was associated with sharp foreign bodies. In all but one, endoscopic removal was successful. In one case denture impacted in post cricoid region was removed by open surgical method. There was no mortality in our series.

6.
Indian J Pediatr ; 71(8): 689-93, 2004 Aug.
Article in English | MEDLINE | ID: mdl-15345868

ABSTRACT

OBJECTIVE: Foreign body ingestion is a common clinical problem, encountered in children. METHODS: A total number of 104 patients with ingested foreign body admitted in our hospital are reviewed. Endoscopic removal was done for all foreign objects impacted in esophagus. RESULT: In 84.6% cases, history of having swallowed the foreign body was most common symptom. Majority of patients (61.53%) presented within 24 hours after ingestion of foreign body. Coins were the most frequent offending agents in children (87.5%). Seventy six cases of coins were impacted in the postcricoid region. Complications of retropharyngeal abscess was seen in two cases (1.92%), which was associated with sharp foreign body. CONCLUSION: Early removal of these sharp foreign bodies must be considered to reduce the risk of this complication.


Subject(s)
Esophagus , Foreign Bodies/diagnosis , Foreign Bodies/therapy , Adolescent , Child , Child, Preschool , Esophagoscopy , Female , Humans , Infant , Male
7.
Indian J Pediatr ; 71(9): 849-52, 2004 Sep.
Article in English | MEDLINE | ID: mdl-15448394

ABSTRACT

Foreign body aspiration is an extremely serious problem in childhood with varied clinical presentation demanding high degree of suspicion on the part of clinician. Surgical emphysema of the neck and chest often complicates tracheostomy and sharp penetrating injuries to the neck perforating viscera of the aerodigestive tract. Rarely if follows chest injuries. But emphysema due to the neck of foreign bodies in the bronchus is quite rare. The authors hereby report four cases of surgical emphysema following foreign body aspiration into the tracheobronchial tree.


Subject(s)
Bronchi , Foreign Bodies/diagnosis , Bronchoscopy , Child , Child, Preschool , Female , Foreign Bodies/surgery , Humans , Male
9.
Indian J Pediatr ; 71(3): 271-2, 2004 Mar.
Article in English | MEDLINE | ID: mdl-15080417

ABSTRACT

Lipoma in retropharyngeal space is rare. A case of lipoma in the retropharyngeal space of a paediatric patient is reported with characteristic radiological findings along with surgical management.


Subject(s)
Lipoma , Pharyngeal Neoplasms , Child , Humans , Lipoma/diagnostic imaging , Lipoma/surgery , Male , Pharyngeal Neoplasms/diagnostic imaging , Pharyngeal Neoplasms/surgery , Radiography
10.
Indian J Pediatr ; 70(10): 793-7, 2003 Oct.
Article in English | MEDLINE | ID: mdl-14649474

ABSTRACT

OBJECTIVE: [corrected] Foreign body inhalation is an extremely serious problem in children and sometimes result in sudden death. The current mortality rate from foreign body inhalation is between 0% and 1.8% according to various studies. In spite of this, undiagnosed and unsuspected foreign bodies still occur in the airway. METHODS: Pediatric patients with documented foreign body inhalation, treated in the Department of Pediatrics, Bapuji Hospital, JJM Medical College during 1997-2000 are included in the analysis. Children with or without positive history of aspiration were examined and the diagnosis was made on the basis of history, clinical findings, radilogic evaluation and strong index of suspicion in those children where reasonable appropriate treatment failed to resolve the respiratory symptoms. Bronchoscopy was performed for a suspected foreign body on 165 children. RESULT: A review of 165 pediatric cases of suspected foreign body aspiration revealed, children between 1 and 3 years were found to be very vulnerable for aspiration. Majority of children were boys. Over 70% of the patients had positive history of inhalation. Only 60% of the patients presented immediately, that is within 24 hours after aspiration. Common symptoms were cough and respiratory distress. Physical examination showed abnormal finding in 91% of cases. Decreased air entry was the significant clinical sign. Obstructive emphysema was found in majority of the cases (49.5%). Rigid bronchoscopy under general anaesthesia was the preferred method for removal of aspirated foreign body. In 65 (61.9%) cases foreign body was lodged in the right main bronchus and majority of these were organic in nature, that is 96 (91.43%). CONCLUSION: Tracheobronchial foreign bodies should be strongly suspected in pediatric age group who present with a suggestive history, even when physical and radiographic evidence is absent. The modalities of diagnosis, management and outcome are discussed.


Subject(s)
Bronchi , Foreign Bodies/diagnostic imaging , Trachea , Child , Child, Preschool , Foreign Bodies/complications , Foreign Bodies/diagnosis , Humans , Radiography , Respiration Disorders/diagnosis , Respiration Disorders/etiology
11.
Indian J Otolaryngol Head Neck Surg ; 55(4): 268-9, 2003 Oct.
Article in English | MEDLINE | ID: mdl-23119998

ABSTRACT

A great variety of foreign bodies in the traeheohr onvhial tree have been reported, but presence of fractured tracheostomy tube as foreign body is ran1. Usually fractured pieces of outer tube are found in the bronchus or trachea near the carina, but occurence of inner tube in the upper part of the trachea is rare2 and one such case is presented here.

12.
Indian J Pediatr ; 70(11): 875-6, 2003 Nov.
Article in English | MEDLINE | ID: mdl-14703225

ABSTRACT

OBJECTIVE: This article attempts to address the controversy between, endoscopic and traditional approaches to neonatal choanal atresia. METHOD: Congenital choanal atresia has been recognized for over 200 years, first described by Roedere in 1775. This condition is uncommon, occurring in approximately 1 in 7000 live births. Unfortunately a single ideal procedure for this condition does not exist. RESULTS: Stankiewicz is credited with the first description of endoscopic techniques for choanal atresia repair. All patients diagnosed to have choanal atresia, treated between 1999 and 2000 were reviewed. Out of four patients two underwent endoscopic repair. CONCLUSION: Transnasal endoscopic technique is followed by stenting with endotracheal portex tubes for 4-6 weeks in the initial surgical procedure of choice.


Subject(s)
Choanal Atresia/surgery , Endoscopy , Endoscopy/methods , Female , Humans , Infant , Infant, Newborn , Male
13.
J Bacteriol ; 179(20): 6416-25, 1997 Oct.
Article in English | MEDLINE | ID: mdl-9335291

ABSTRACT

The methylmalonyl coenzyme A (methylmalonyl-CoA)-specific acyltransferase (AT) domains of modules 1 and 2 of the 6-deoxyerythronolide B synthase (DEBS1) of Saccharopolyspora erythraea ER720 were replaced with three heterologous AT domains that are believed, based on sequence comparisons, to be specific for malonyl-CoA. The three substituted AT domains were "Hyg" AT2 from module 2 of a type I polyketide synthase (PKS)-like gene cluster isolated from the rapamycin producer Streptomyces hygroscopicus ATCC 29253, "Ven" AT isolated from a PKS-like gene cluster of the pikromycin producer Streptomyces venezuelae ATCC 15439, and RAPS AT14 from module 14 of the rapamycin PKS gene cluster of S. hygroscopicus ATCC 29253. These changes led to the production of novel erythromycin derivatives by the engineered strains of S. erythraea ER720. Specifically, 12-desmethyl-12-deoxyerythromycin A, which lacks the methyl group at C-12 of the macrolactone ring, was produced by the strains in which the resident AT1 domain was replaced, and 10-desmethylerythromycin A and 10-desmethyl-12-deoxyerythromycin A, both of which lack the methyl group at C-10 of the macrolactone ring, were produced by the recombinant strains in which the resident AT2 domain was replaced. All of the novel erythromycin derivatives exhibited antibiotic activity against Staphylococcus aureus. The production of the erythromycin derivatives through AT replacements confirms the computer predicted substrate specificities of "Hyg" AT2 and "Ven" AT and the substrate specificity of RAPS AT14 deduced from the structure of rapamycin. Moreover, these experiments demonstrate that at least some AT domains of the complete 6-deoxyerythronolide B synthase of S. erythraea can be replaced by functionally related domains from different organisms to make novel, bioactive compounds.


Subject(s)
Acyltransferases/genetics , Acyltransferases/metabolism , Erythromycin/analogs & derivatives , Multienzyme Complexes/genetics , Multienzyme Complexes/metabolism , Saccharopolyspora/enzymology , Acyl Coenzyme A/metabolism , Acyltransferases/chemistry , Amino Acid Sequence , Cloning, Molecular , Erythromycin/biosynthesis , Erythromycin/chemistry , Genetic Vectors , Molecular Sequence Data , Molecular Structure , Multienzyme Complexes/chemistry , Plasmids , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Saccharopolyspora/genetics , Transformation, Genetic
14.
J Bacteriol ; 177(15): 4327-32, 1995 Aug.
Article in English | MEDLINE | ID: mdl-7543473

ABSTRACT

ErmC' is a methyltransferase that confers resistance to the macrolide-lincosamide-streptogramin B group of antibiotics by catalyzing the methylation of 23S rRNA at a specific adenine residue (A-2085 in Bacillus subtilis; A-2058 in Escherichia coli). The gene for ErmC' was cloned and expressed to a high level in E. coli, and the protein was purified to virtual homogeneity. Studies of substrate requirements of ErmC' have shown that a 262-nucleotide RNA fragment within domain V of B. subtilis 23S rRNA can be utilized efficiently as a substrate for methylation at A-2085. Kinetic studies of the monomethylation reaction showed that the apparent Km of this 262-nucleotide RNA oligonucleotide was 26-fold greater than the value determined for full-size and domain V 23S rRNA. In addition, the Vmax for this fragment also rose sevenfold. A model of RNA-ErmC' interaction involving multiple binding sites is proposed from the kinetic data presented.


Subject(s)
Bacillus subtilis/enzymology , Methyltransferases/metabolism , Bacillus subtilis/genetics , Base Sequence , Gene Expression Regulation, Bacterial , Kinetics , Methylation , Methyltransferases/genetics , Molecular Sequence Data , Nucleic Acid Conformation , Oligodeoxyribonucleotides/metabolism , Peptidyl Transferases/genetics , Peptidyl Transferases/metabolism , RNA, Bacterial/metabolism , RNA, Ribosomal, 23S/metabolism , Substrate Specificity
15.
Gene ; 79(1): 21-31, 1989 Jun 30.
Article in English | MEDLINE | ID: mdl-2550328

ABSTRACT

Significant differences in expression of the delta-endotoxin genes cryA1 and cryA2 of Bacillus thuringiensis subsp. kurstaki were observed in B. subtilis and B. megaterium. The cryA1 gene was expressed when present on a high-copy-number (hcn) vector in B. megaterium but not in B. subtilis. The cryA2 gene was expressed in both hosts, but at a higher level in B. megaterium. Expression of the cryA2 gene in B. megaterium was better from a hcn vector than from a low copy number vector. Inhibition of sporulation was observed when the toxin genes were present on hcn plasmids in B. subtilis while no such effect was evident in B. megaterium. In addition, there was a significant reduction in copy numbers in both B. subtilis and B. megaterium when delta-endotoxin genes or a spoVG promoter-containing fragment of DNA were cloned into hcn plasmids.


Subject(s)
Bacillus/genetics , Bacterial Proteins , Bacterial Toxins , Cloning, Molecular , Endotoxins/genetics , Gene Amplification , Gene Expression Regulation , Genes, Bacterial , Bacillus/physiology , Bacillus/ultrastructure , Bacillus megaterium/genetics , Bacillus megaterium/physiology , Bacillus megaterium/ultrastructure , Bacillus subtilis/genetics , Bacillus subtilis/physiology , Bacillus thuringiensis/genetics , Bacillus thuringiensis Toxins , Crystallization , DNA, Bacterial/genetics , Endotoxins/biosynthesis , Hemolysin Proteins , Immunoblotting , Plasmids , Promoter Regions, Genetic , Restriction Mapping , Spores, Bacterial , Transformation, Bacterial
16.
J Bacteriol ; 166(1): 194-204, 1986 Apr.
Article in English | MEDLINE | ID: mdl-3007434

ABSTRACT

Bacillus thuringiensis subsp. kurstaki total DNA was digested with BglII and cloned into the BamHI site of plasmid pUC9 in Escherichia coli. A recombinant plasmid, pHBHE, expressed a protein of 135,000 daltons that was toxic to caterpillars. A HincII-SmaI double digest of pHBHE was then ligated to BglII-cut plasmid pBD64 and introduced into Bacillus subtilis by transformation. The transformants were identified by colony hybridization and confirmed by Southern blot hybridization. A 135,000-dalton protein which bound to an antibody specific for the crystal protein of B. thuringiensis was detected from the B. subtilis clones containing the toxin gene insert in either orientation. A toxin gene insert cloned into a PvuII site distal from the two drug resistance genes of the pBD64 vector also expressed a 135,000-dalton protein. These results suggest that the toxin gene is transcribed from its own promoter. Western blotting of proteins expressed at various stages of growth revealed that the crystal protein expression in B. subtilis begins early in the vegetative phase, while in B. thuringiensis it is concomitant with the onset of sporulation. The cloned genes when transferred to a nonsporulating strain of B. subtilis also expressed a 135,000-dalton protein. These results suggest that toxin gene expression in B. subtilis is independent of sporulation. Another toxin gene encoding a 130,000- to 135,000-dalton protein was cloned in E. coli from a library of B. thuringiensis genes established in lambda 1059. This gene was then subcloned in B. subtilis. The cell extracts from both clones were toxic to caterpillars. Electron microscope studies revealed the presence of an irregular crystal inclusion in E. coli and a well-formed bipyramidal crystal in B. subtilis clones similar to the crystals found in B. thuringiensis.


Subject(s)
Bacillus subtilis/genetics , Bacillus thuringiensis/genetics , Bacterial Proteins , Bacterial Toxins , Endotoxins/genetics , Genes, Bacterial , Bacillus thuringiensis Toxins , Biological Assay , Cloning, Molecular , Endotoxins/analysis , Endotoxins/biosynthesis , Escherichia coli/genetics , Hemolysin Proteins , Plasmids , Spores, Bacterial/physiology , Transcription, Genetic
17.
Nucleic Acids Res ; 9(11): 2549-62, 1981 Jun 11.
Article in English | MEDLINE | ID: mdl-6792593

ABSTRACT

The ermC gene of plasmid pE194 specifies resistance to the macrolidelincosamide-streptogramin B antibiotics. This resistance, as well as synthesis of the 29,000 dalton protein product of ermC, has been shown to be induced by erythromycin. Weisblum and his colleagues have established that macrolide resistance is associated with a specific dimethylation of adenine in 23 S rRNA. We show that pE194 specifies an RNA methylase that can utilize either 50 S ribosomes or 23 S rRNA as substrates. Synthesis of this methylase is induced by low concentrations of erythromycin, and the enzyme is produced in elevated amounts by strains carrying a high copy number mutant of pE194. The methylase comigrates with the 29K ermC product on polyacrylamide gels. The purification and some properties of this methylase are described.


Subject(s)
Bacillus subtilis/enzymology , Erythromycin/pharmacology , Plasmids , Ribosomes/enzymology , tRNA Methyltransferases/genetics , Amino Sugars/pharmacology , Anti-Bacterial Agents/pharmacology , Bacillus subtilis/drug effects , Drug Resistance, Microbial , Mutation , Ribosomes/drug effects , Species Specificity , Virginiamycin/pharmacology , tRNA Methyltransferases/isolation & purification
18.
J Bacteriol ; 145(1): 129-37, 1981 Jan.
Article in English | MEDLINE | ID: mdl-6780509

ABSTRACT

Resistance to the macrolide-lincosamide-streptogramin B (MLS) group of antibiotics is widespread and of clinical importance. B. Weisblum and his coworkers have demonstrated that this resistance is associated with methylation of the 23S ribosomal ribonucleic acid of the large ribosomal subunit which results in a diminished affinity of this organelle for these antibiotics (Lai et al, J. Mol. Biol. 74:67-72, 1973). We report that 10 of 15 natural isolates of Bacillus licheniformis, a common soil organism, are resistant to the MLS antibiotics. The properties of this resistance (high level of tolerance for erythromycin, broad cross-resistance spectrum, and inducibility) suggest that resistance is conferred as described above. The resistance determinant from one of these strains was cloned onto a B. subtilis plasmid vector, and the resulting hybrid plasmid (pBD90) was used to prepare radioactive probe deoxyribonucleic acid for hybridization studies. All of the resistance B. licheniformis strains studied exhibited homology with the pBD90 insert. Plasmid pBD90 showed no homology to the following staphylococcal and streptococcal MLS-resistance plasmids: pE194, pE5, pAM77, pI258. Plasmids pE194 and pE5, on the other hand, carry homologous MLS genes but showed no detectable homology to one another in their replication genes. pBD90 specified a 35,000-dalton erythromycin-inducible protein, detectable in minicells, which therefore appears different from the 29,000-dalton inducible resistance protein specified by pE194. We conclude that there are at least three distinct MLS resistance determinants to be found among gram-positive bacteria.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacillus/drug effects , Genes , Bacillus/genetics , Bacterial Proteins/biosynthesis , Cloning, Molecular , Drug Resistance, Microbial , Erythromycin/pharmacology , Nucleic Acid Hybridization , Plasmids , Virginiamycin/pharmacology
19.
Proc Natl Acad Sci U S A ; 77(7): 3903-7, 1980 Jul.
Article in English | MEDLINE | ID: mdl-6159624

ABSTRACT

Induction of the synthesis of a plasmid-encoded polypeptide (E3) by erythromycin is known to be required for the inducible expression of resistance to the macrolide-lincosamide-streptogramin B group of antibiotics in Bacillus subtilis strains carrying the plasmid pE194. This resistance is mediated by a specific N6-dimethylation of adenine in the 23S rRNA of the large ribosomal subunit. We show in this report that E3 induction is regulated posttranscriptionally in the sense that it can occur when RNA synthesis is blocked and that induction is accompanied by an increase in the functional half-life of E3 mRNA but not of the mRNA species that code for the remaining four known pE194 polypeptides. The induction of E3 is subject to feedback regulation and involves the ribosome. Modification of the erythromycin binding site on the ribosome by methylation or by mutation interferes with induction.


Subject(s)
Bacillus subtilis/genetics , Drug Resistance, Microbial , Gene Expression Regulation , Plasmids , Transcription, Genetic , Erythromycin , Feedback , RNA, Bacterial/genetics , RNA, Messenger/genetics , Ribosomes/metabolism
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