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Biomedical subjects

A M Berry

Publications and source records attributed to A M Berry.

At least 19 recordsLinked to original sources
PubMed2001

Hopanoid lipids in Frankia: identification of squalene-hopene cyclase gene sequences.

In Frankia, the microsymbiont in actinorhizal root nodules, nitrogen fixation takes place in specialized structures called vesicles. The lipidic vesicle envelope forms a barrier to oxygen diffusion, an essential part of the nitrogenase oxygen protection system. We have shown previously that the vesicle envelope is composed primarily of two species of hopanoid lipids, sterol-like molecules that are synthesized in a wide range of bacteria, including Frankia, several cyanobacteria, and rhizobia. The levels of hopanoid found in Frankia are among the highest of any organism known to date. Here we report that short (328-bp) DNA sequences from several strains of Frankia spp. have been identified that are homologous to a portion of the coding region of squalene-hopene cyclase (shc) genes. The fragments and corresponding polymerase chain reaction (PCR) primers can be used in phylogenetic comparisons of Frankia, both within Frankiaceae and among bacteria that synthesize hopanoids.

Actinomycetales↗
PubMed2000

Dg93, a nodule-abundant mRNA of Datisca glomerata with homology to a soybean early nodulin gene.

We have isolated a 590-bp full-length cDNA clone designated Dg93, an mRNA that is highly expressed in symbiotic root nodules of the actinorhizal host Datisca glomerata. Dg93 mRNA encodes a deduced polypeptide of 105 amino acids with significant identity (74%) to the soybean (Glycine max) early nodulin (ENOD) gene GmENOD93 (Kouchi and Hata, 1993). Dg93 mRNA is abundant in nodules at 4 weeks post inoculation, the earliest time assayed, and steady-state mRNA levels remain elevated 11 weeks after inoculation. Spatial patterns of Dg93 mRNA expression are complex, with transcript accumulation in the nodule lobe meristem, early infection zone, periderm, and cells of the vascular cylinder, but not in the surrounding uninfected cortical cells. Dg93 is encoded by a small gene family in D. glomerata. To our knowledge, this is the first report of a gene from an actinorhizal host that is expressed in the nodule meristem and that shares sequence homology with an early nodulin gene from a legume.

Amino Acid Sequence↗
PubMed2000

Genetic characterization of vanG, a novel vancomycin resistance locus of Enterococcus faecalis.

Enterococcus faecalis strain WCH9 displays a moderate level of resistance to vancomycin (MIC = 16 microgram/ml) and full susceptibility to teicoplanin but is negative by PCR analysis using primers specific for all known enterococcal vancomycin resistance genotypes (vanA, vanB, vanC, vanD, and vanE). We have isolated and sequenced a novel putative vancomycin resistance locus (designated vanG), which contains seven open reading frames, from this strain. These are organized differently from those of all the other enterococcal van loci, and, furthermore, the individual vanG gene products exhibit less than 50% amino acid sequence identity to other van gene products.

Amino Acid Sequence↗
PubMed2000

Additive attenuation of virulence of Streptococcus pneumoniae by mutation of the genes encoding pneumolysin and other putative pneumococcal virulence proteins.

Although the polysaccharide capsule of Streptococcus pneumoniae has been recognized as a sine qua non of virulence, much recent attention has focused on the role of pneumococcal proteins in pathogenesis, particularly in view of their potential as vaccine antigens. The individual contributions of pneumolysin (Ply), the major neuraminidase (NanA), autolysin (LytA), hyaluronidase (Hyl), pneumococcal surface protein A (PspA), and choline-binding protein A (CbpA) have been examined by specifically mutagenizing the respective genes in the pneumococcal chromosome and comparing the impact on virulence in a mouse intraperitoneal challenge model. Mutagenesis of either the ply, lytA, or pspA gene in S. pneumoniae D39 significantly reduced virulence, relative to that of the wild-type strain, indicating that the respective gene products contribute to pathogenesis. On the other hand, mutations in nanA, hyl, or cbpA had no significant impact. The virulence of D39 derivatives carrying a ply deletion mutation as well as an insertion-duplication mutation in one of the other genes was also examined. Mutagenesis of either nanA or lytA did not result in an additional attenuation of virulence in the ply deletion background. However, significant additive attenuation in virulence was observed for the strains with ply-hyl, ply-pspA, and ply-cbpA double mutations.

Animals↗
PubMed1999

Symbiotic root nodules of the actinorhizal plant Datisca glomerata express Rubisco activase mRNA.

N2-fixing symbiotic root nodules of the actinorhizal host Datisca glomerata express Dgrca (D. glomerata Rubisco activase) mRNA, a transcript usually associated with photosynthetic organs or tissues. In northern blots a mature, 1700-nucleotide Dgrca mRNA was detected in green plant organs (leaves, flowers, and developing fruits) and in nodules but was not detected in roots. A second message of 3000 nucleotides was observed only in nodules. Both size classes of transcripts were polyadenylated. The larger transcript was 2- to 5-fold more abundant than the mature mRNA; it was hybridized to an intronic probe, indicating that a stable, incompletely spliced transcript was accumulating. Treatment with light on excised nodules did not alter the relative abundance of the two species. In in situ hybridizations the Dgrca message was expressed intensely in the nuclei of infected cells. The Dgrca transcripts also accumulated at lower levels in uninfected cortical cells adjacent to the periderm and the vascular cylinder. mRNA encoding the large subunit of Rubisco (DgrbcL) was abundant in mature infected cells and in the amyloplast-rich sheath of uninfected cortical cells lying between the infected cells and nodule periderm. The proteins Rubisco activase, Rubisco, and the 33-kD O2-evolving complex subunit did not accumulate to detectable levels, indicating that a functional photosynthetic apparatus was not prevalent in nodule tissue. Signals or factors required for the transcription of Dgrca appeared to be present in nodules, but efficient splicing and translation of the message were not observed in Frankia-infected tissue where transcript accumulation was highest.

Actinomycetales↗
PubMed1999

Comparative virulence of Streptococcus pneumoniae strains with insertion-duplication, point, and deletion mutations in the pneumolysin gene.

Pneumolysin is a 471-amino-acid toxin produced by Streptococcus pneumoniae which has both cytolytic and complement activation properties. We have constructed a derivative of the type 2 S. pneumoniae strain D39 in which the portion of the pneumolysin gene encoding amino acids 55 to 437 has been deleted in-frame. The virulence of this strain (DeltaPly) was compared with those of wild-type D39, a pneumolysin insertion-duplication mutant (PLN-A), and a derivative (PdT) carrying a toxin gene with three point mutations known to abolish both cytolytic activity and complement activation. PdT was intermediate in virulence between D39 and either PLN-A or DeltaPly in a mouse intraperitoneal challenge model. This provides unequivocal evidence that pneumolysin has an additional property that is not abolished by point mutations which reduce cytotoxicity and complement activation to virtually undetectable levels.

Animals↗
PubMed1998

The crystal structure of pneumococcal surface antigen PsaA reveals a metal-binding site and a novel structure for a putative ABC-type binding protein.

BACKGROUND: . The surface protein PsaA of the pathogenic bacterium Streptococcus pneumoniae plays an essential role in its virulence. PsaA is a putative ATP-binding cassette-type (ABC-type) binding protein involved in the uptake of Mn2+ and possibly Zn2+ and is considered to be both a potential drug target and and a candidate vaccine component. RESULTS: . The structure of PsaA has been determined to 2.0 A resolution using X-ray crystallography and is the first structure obtained for an ABC-type binding protein from a Gram-positive organism. The protein consists of two (beta/alpha)4 domains linked together by a single helix. A metal-binding site is formed in the domain interface by the sidechains of His67, His139, Glu205 and Asp280 and is occupied in the structure. CONCLUSIONS: . The structural topology of PsaA is fundamentally different from that of other ABC-type binding proteins determined thus far in that PsaA lacks the characteristic 'hinge peptides' involved in conformational change upon solute uptake and release. In our structure, the metal-binding site is probably occupied by Zn2+. The site seems to be well conserved amongst related receptors from both Gram-positive and Gram-negative bacteria.

ATP-Binding Cassette Transporters↗
PubMed1998

Expression, purification and preliminary X-ray crystallographic analysis of PsaA, a putative metal-transporter protein of Streptococcus pneumoniae.

The putative metal-transporter protein PsaA of Streptococcus pneumoniae is of potential interest both as a vaccine and also as a drug target. The overexpression of the protein in E. coli, and its subsequent purification and crystallization are described. The crystals are rectangular rods and diffract to beyond 2.7 A resolution. The crystal space group is P212121 with unit-cell dimensions a = 59.9, b = 66.5 and c = 69.9 A.

Adhesins, Bacterial↗
PubMed1998

Amino acid changes affecting the activity of pneumolysin alter the behaviour of pneumococci in pneumonia.

Pneumolysin is a multi-functional toxin produced by Streptococcus pneumoniae. The toxin has distinct cytotoxic activity and complement-activating activity mediated by different parts of the toxin molecule. Mice challenged intranasally with a type 2 pneumococcal strain contract bronchopneumonia and bacteremia [1]. Mice were infected intranasally with isogenic mutants of this strain in which the chromosomal pneumolysin gene carried point mutations affecting either or both properties of pneumolysin. Reduction in either cytotoxic activity or complement activation by pneumolysin decreased the virulence of the mutant pneumococci. However, it was the ability to activate complement that most affected the behaviour of pneumococci in the lungs and associated bacteremia in the first 24 h following infection.

Amino Acids↗
PubMed1998

Pneumolysin in pneumococcal adherence and colonization.

The universal and highly conserved production of pneumolysin, the major pneumococcal cytolysin, among clinical isolates of Streptococcus pneumoniae and the previously reported association of pneumolysin production with increased pneumococcal adherence to respiratory epithelium in organ cultures suggest that this toxin might be important for nasopharyngeal colonization. We confirmed that pneumolysin-deficient mutant pneumococcal strains had decreased adherence to respiratory epithelial cells in vitro compared with their isogeneic wild-type strains. However, neither early nor sustained colonization by type 14 S. pneumoniae in an established murine model was dependent on bacterial production of pneumolysin. We conclude that pneumolysin production is not a major determinant of successful nasopharyngeal colonization by pneumococci.

Animals↗
PubMed1998

An evaluation of the factors influencing selection of the optimal size of laryngeal mask airway in normal adults.

The purpose of this randomised single blinded study was to determine the optimal size of laryngeal mask airway in the normal adult population, to test the validity of the current selection criteria and to determine if any externally measured anatomical variable correlated with optimal size. In each of 30 apnoeic anaesthetised adults weighting less than 100 kg, size 3, 4 and 5 laryngeal mask airways were inserted in random order by a skilled user and the cuff inflated to a standard pressure (60 cm H2O). Optimal size was based on four criteria in order of priority: number of attempts at placement, oropharyngeal leak pressure, fiberoptic score and percentage of vocal cords seen. The size 5 laryngeal mask airway was optimal in 19/30 and the size 4 in 11/30. In no patient was the size 3 the optimal fit. Oropharyngeal leak pressure was significantly higher for each progressively large size and the fiberoptic view was significantly better for the size 4 and size 5. There was no significant predictive value in any externally measured anatomical variable, but height was the most useful. The best current selection strategy was to choose a size 5 for males and size 4 for females. Potentially useful new strategies may be to use the size 5 in all adults, or a size 5 > or = 165 cm in height and size 4 for < 165 cm. We conclude that predicting the optimal size of laryngeal mask airway for individual adult patients is complex. The best size selection strategies involve use of the size 4 and 5 laryngeal mask airways in adults.

Adolescent↗
PubMed1998

A comparison of the laryngeal mask airway and cuffed oropharyngeal airway in anesthetized adult patients.

UNLABELLED: We compared the cuffed oropharyngeal airway (COPA) with the laryngeal mask airway (LMA) in 120 anesthetized adult patients. We compared 1) placement success rates, 2) airway interventional requirements, 3) airway stability in different head/neck positions, 4) cardiorespiratory tolerance, and 5) intra- and postoperative adverse events/symptoms. A standardized anesthesia protocol was followed by four anesthesiologists experienced with both devices. Observational data were validated by independent analysis of continuous video recordings. Postoperative interviews were double-blind to the device used. The LMA had a more frequent success rate than COPA (97% vs 55%, P < 0.00001), an overall higher success rate (100% vs 83%; P = 0.001), a shorter time to achieve an effective airway (49 vs 188 s; P < 0.00001), a higher oropharyngeal leak pressure (21 vs 16 cm H2O; P = 0.003), and a fewer number of chin lift airway interventions required (0.1% vs 42%; P < 0.00001). When comparing mean tidal volumes in different head/neck positions to assess airway stability, the quality of airway was unchanged in 98% patients with the LMA and 54% with the COPA (P < 0.00001). The incidences of intraoperative adverse events were similar. On removal, blood was detected more often on the COPA (3% vs 14%; P = 0.04). In the late postoperative period, more patients complained of adverse symptoms with the COPA than with the LMA (26% vs 57%; P = 0.001). Late postoperative symptoms occurred more frequently with the COPA (0.87 vs 0.34; P = 0.003). There was more late postoperative sore throat (14% vs 36%; P = 0.0003) and more jaw/neck pain (12% vs 26%; P = 0.0008) in patients managed with the COPA. This study demonstrates that the LMA offers advantages over the COPA in most technical aspects of airway management and in terms of postoperative morbidity. IMPLICATIONS: In this randomized, prospective study, we compared the laryngeal mask airway and the cuffed oropharyngeal airway in anesthetized patients. The laryngeal mask airway offers advantages in most technical aspects of airway management and in terms of postoperative morbidity.

Adult↗
PubMed1998

The laryngeal mask airway in emergency medicine, neonatal resuscitation, and intensive care medicine.

In assessing the potential role of the LMA outside the operating room, the risks of a less secure airway must be balanced against the benefits of ease of training, success and speed of insertion, no need for direct visualization of laryngeal structures, and lesser need for ancillary equipment. The LMA has a role as an alternative to FMV in CPR when personnel skilled in tracheal intubation are not available. When skilled intubators are present, it has an important role as an alternative airway when intubation has been impossible. These roles extend to the prehospital setting, with an additional specific indication for its use when access to a patient is limited making tracheal intubation impossible. The LMA is incorporated into advanced life support training and as such should be regarded as a device providing temporary airway support, rather than a replacement for a tracheal tube. The LMA, and possibly also the ILM, should be standard equipment carried by prehospital trauma teams and by all those attending victims in the field.

Adult↗
PubMed1997

Cricoid pressure.

PURPOSE: Although cricoid pressure (CP) is a superficially simple and appropriate mechanical method to protect the patient from regurgitation and gastric insufflation, in practice it is a complex manoeuvre which is difficult to perform optimally. The purpose of this review is to examine and evaluate studies on the application of (CP). It deals with anatomical and physiological considerations, techniques employed, safety and efficacy issues and the impact of CP on airway management with special mention of the laryngeal mask airway. SOURCE OF MATERIAL: Three medical databases (48 Hours, Medline, and Reference Manager Update) were searched for citations containing key words, subject headings and text entries on CP to October 1996. PRINCIPLE FINDINGS: There have been no studies proving that CP is beneficial, yet there is evidence that it is often ineffective and that it may increase the risk of failed intubation and regurgitation. After evaluation of all available data, potential guidelines are suggested for optimal use of CP in routine and complex situations. CONCLUSIONS: If CP is to remain standard practice during induction of anaesthesia, it must be shown to be safe and effective. Meanwhile, further understanding of its advantages and limitations, improved training in its use, and guidelines on optimal force and method of application should lead to better patient care.

Cricoid Cartilage↗
PubMed1997

Molecular analysis of putative pneumococcal virulence proteins.

Although the polysaccharide capsule has been recognized as a sine qua non of virulence, recent attention has focused on the role of pneumococcal proteins in pathogenesis, particularly in view of their potential as vaccine antigens. The contribution of pneumolysin, two distinct neuraminidases, autolysin, hyaluronidase, and the 37 kDa pneumococcal surface adhesin A has been examined by specifically mutagenizing the respective genes in the pneumococcal chromosome and examining the impact on virulence in animal models. The vaccine potential of these proteins has also been assessed by immunization of mice with purified antigens, followed by challenge with virulent pneumococci.

Adhesins, Bacterial↗