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Biomedical subjects

A Berry

Publications and source records attributed to A Berry.

At least 73 records · Page 4Linked to original sources
PubMed1998

The cuffed oropharyngeal airway for spontaneous ventilation anaesthesia. Clinical appraisal in 100 patients.

The cuffed oropharyngeal airway is a modified Guedel airway with a distal inflatable cuff and a proximal connector for attachment to an anaesthesia circuit. The purpose of this study was to evaluate this device for spontaneous ventilation anaesthesia in 100 adult patients. Anaesthesia was induced with fentanyl and propofol and maintained with nitrous oxide and isoflurane in oxygen. The device was inserted when anaesthetic depth was judged to be adequate. Adverse airway events and interventions (i.e., manoeuvres performed in order to provide a clear airway) were analysed from video recordings and detailed notes. The position of the device was assessed fibreoptically during spontaneous ventilation. The device provided a clear airway in 98% of patients during manually assisted ventilation, in 100% during spontaneous ventilation and in 100% during emergence. However, 91% of patients required at least one airway intervention at some time. Jaw life was required for 33% of the time during manually assisted ventilation and 21% of the time during spontaneous ventilation. Most interventions occurred during the first 3 min of either manually assisted or spontaneous ventilation. The incidence of adverse airway events during manually assisted ventilation was 8%, during spontaneous ventilation was 5% and during emergence was 5%. Oxygen saturation briefly fell to between 87 and 89% on six occasions. On fibreoptic assessment, the vocal cords were visible in 29% of patients on fibreoptic assessment and the epiglottis was visible in 90%. Mild sore throat occurred in 4% of patient. We conclude that the cuffed oropharyngeal airway is suitable for spontaneous ventilation anaesthesia and has a low complication rate but that most patients require one or more interventions to provide a clear airway.

Adolescent↗
PubMed1998

A randomized controlled trial comparing the cuffed oropharyngeal airway and the laryngeal mask airway in spontaneously breathing anesthetized adults.

BACKGROUND: The cuffed oropharyngeal airway (COPA), a modified Guedel airway, was compared with the laryngeal mask airway (LMA) during spontaneous breathing anesthesia. Specifically examined were ease of use, physiologic tolerance, and the frequency of problems. METHODS: Adult patients consented to random (2:1) assignment to either COPA (n = 302) or LMA (n = 151) for airway management during anesthesia with propofol, nitrous oxide, and oxygen. RESULTS: Ease of insertion was similar, but the first-time successful insertion rate was higher with the LMA (COPA, 81% compared with LMA, 89%; P = 0.05). More brief manipulations (head tilt, chin lift, jaw thrust) were reported in the COPA group (average total number of manipulations: COPA, 1.1 +/- 1.6 compared with LMA, 0.1 +/- 0.2; P < 0.001). Continuous airway support was used more frequently in the COPA group (COPA, 30% compared with LMA, 0%; P < 0.0005). The incidences of aspiration, regurgitation, laryngospasm, wheezing, succinylcholine administration, oxygen saturation (SpO2) < 92%, failed use, and minor intraoperative problems were similar. When the airways were removed, blood was detected on the COPA less frequently than on the LMA (COPA, 5.8% compared with LMA, 15.3%; P = 0.001). The incidence of early and late sore throat was greater with the LMA (early: COPA, 4.7% compared with LMA, 21.9% [P = 0.001]; late: COPA, 8.4% compared with LMA, 16.1%; P = 0.01). The LMA did better than the COPA when anesthetists analyzed the technical aspects of the two devices. CONCLUSIONS: Although the COPA and LMA are equivalent devices in terms of physiologic alterations and overall clinical problems associated with their use, the LMA was associated with a higher first-time insertion rate and fewer manipulations, suggesting that it is easier to use. The COPA was associated with less blood on the device and fewer sore throats, suggesting it may cause less pharyngeal trauma. Ultimately, both devices were similar in establishing a safe and effective airway for spontaneously breathing anesthetized adults.

Adult↗
PubMed1998

Changes in membrane fluidity induced by binding of immunoglobulins to sperm Fc receptors.

Receptors for Fc region of immunoglobulins (FcR) are reported to be present on spermatozoa, and also detected in seminal plasma, however their function is still not known. Since various changes in sperm membrane architecture during maturation and passage through female genital tract are reported, experiments were conducted to study the membrane fluidity changes in sperm subsequent to ligation of surface FcR with immunoglobulin and its derivatives. This paper reports that interaction with IgG restricts rotational mobility of cell surface proteins and membrane lipids as studied by EPR spectroscopy using spin probes. Decrease in fluidity was much more pronounced in the presence of aggregated IgG due to crosslinking of sperm FcR by aggregated IgG.

Animals↗
PubMed1996

The crystal structure of a class II fructose-1,6-bisphosphate aldolase shows a novel binuclear metal-binding active site embedded in a familiar fold.

BACKGROUND: [corrected] Aldolases catalyze a variety of condensation and cleavage reactions, with exquisite control on the stereochemistry. These enzymes, therefore, are attractive catalysts for synthetic chemistry. There are two classes of aldolase: class I aldolases utilize Schiff base formation with an active-site lysine whilst class II enzymes require a divalent metal ion, in particular zinc. Fructose-1,6-bisphosphate aldolase (FBP-aldolase) is used in gluconeogenesis and glycolysis; the enzyme controls the condensation of dihydroxyacetone phosphate with glyceraldehyde-3-phosphate to yield fructose-1,6-bisphosphate. Structures are available for class I FBP-aldolases but there is a paucity of detail on the class II enzymes. Characterization is sought to enable a dissection of structure/activity relationships which may assist the construction of designed aldolases for use as biocatalysts in synthetic chemistry. RESULTS: The structure of the dimeric class II FBP-aldolase from Escherichia coli has been determined using data to 2.5 A resolution. The asymmetric unit is one subunit which presents a familiar fold, the (alpha/beta)8 barrel. The active centre, at the C-terminal end of the barrel, contains a novel bimetallic-binding site with two metal ions 6.2 A apart. One ion, the identity of which is not certain, is buried and may play a structural or activating role. The other metal ion is zinc and is positioned at the surface of the barrel to participate in catalysis. CONCLUSIONS: Comparison of the structure with a class II fuculose aldolase suggests that these enzymes may share a common mechanism. Nevertheless, the class II enzymes should be subdivided into two categories on consideration of subunit size and fold, quaternary structure and metal-ion binding sites.

Amino Acid Sequence↗
PubMed1996

Proliferation of astroglia from the adult human cerebrum is inhibited by ethanol in vitro.

Chronic alcoholism is associated with atrophy of the adult brain, while fetal exposure to ethanol can cause microencephaly. Since astroglial pathology is a common feature of ethanol exposure in both humans and animal models, the direct influence of ethanol on proliferation of human astroglia from the gray and white matter of adult temporal lobe was determined and compared. Astroglial cultures were exposed to constant concentrations of ethanol at realistic social and clinical levels (0.1, 0.2 or 0.5%; w/v) for 1 to 5 days. Proliferation was quantified by bromodeoxyuridine labeling and enumeration of replicating cells. Ethanol exposure significantly inhibited proliferation of both gray and white matter astroglia in a dose and duration dependent manner. Gray matter was slightly more sensitive than white matter to inhibition by low to moderate concentrations of ethanol; in contrast, white matter was more sensitive to high ethanol concentrations. Maximum inhibition was 20% in gray matter and 25% in white matter. Human astroglial proliferation was directly inhibited in the absence of neurons, microglia, neuronal degeneration or systemic factors that have confounded in vivo studies. Restricted astroglial proliferation may underlie aspects of the astroglial pathology associated with ethanol exposure.

Adult↗
PubMed1996

Identification of arginine 331 as an important active site residue in the class II fructose-1,6-bisphosphate aldolase of Escherichia coli.

Treatment of the Class II fructose-1,6-bisphosphate aldolase of Escherichia coli with the arginine-specific alpha-dicarbonyl reagents, butanedione or phenylglyoxal, results in inactivation of the enzyme. The enzyme is protected from inactivation by the substrate, fructose 1,6-bisphosphate, or by inorganic phosphate. Modification with [7-14C] phenylglyoxal in the absence of substrate demonstrates that enzyme activity is abolished by the incorporation of approximately 2 moles of reagent per mole of enzyme. Sequence alignment of the eight known Class II FBP-aldolases shows that only one arginine residue is conserved in all the known sequences. This residue, Arg-331, was mutated to either alanine or glutamic acid. The mutant enzymes were much less susceptible to inactivation by phenylglyoxal. Measurement of the steady-state kinetic parameters revealed that mutation of Arg-331 dramatically increased the K(m) for fructose 1,6-bisphosphate. Comparatively small differences in the inhibitor constant Ki for dihydroxyacetone phosphate or its analogue, 2-phosphoglycolate, were found between the wild-type and mutant enzymes. In contrast, the mutation caused large changes in the kinetic parameters when glyceraldehyde 3-phosphate was used as an inhibitor. Kinetic analysis of the oxidation of the carbanionic aldolase-substrate intermediate of the reaction by hexacyanoferrate (III) revealed that the K(m) for dihydroxyacetone phosphate was again unaffected, whereas that for fructose 1,6-bisphosphate was dramatically increased. Taken together, these results show that Arg-331 is critically involved in the binding of fructose bisphosphate by the enzyme and demonstrate that it interacts with the C-6 phosphate group of the substrate.

Amino Acid Sequence↗
PubMed1996

A direct comparison of approaches for increasing carbon flow to aromatic biosynthesis in Escherichia coli.

Different approaches to increasing carbon commitment to aromatic amino acid biosynthesis were compared in isogenic strains of Escherichia coli. In a strain having a wild-type PEP:glucose phosphotransferase (PTS) system, inactivation of the genes encoding pyruvate kinase (pykA and pykF) resulted in a 3.4 fold increase in carbon flow to aromatic biosynthesis. In a strain already having increased carbon flow to aromatics by virtue of overexpression of the tktA gene (encoding transketolase), the pykA and/or pykf mutations had no effect. A PTS- glucose+ mutant showed a 1.6-fold increase in carbon flow to aromatics compared to the PTS+ control strain. In the PTS- glucose+ host background, overexpression of tktA caused a further 3.7-fold increase in carbon flow, while inactivation of pykA and pykF caused a 5.8-fold increase. When all of the variables tested (PTS-glucose+, pykA, pykF, and overexpressed tktA) were combined in a single strain, a 19.9-fold increase in carbon commitment to aromatic biosynthesis was achieved.

Amino Acids↗
PubMed1996

Improving production of aromatic compounds in Escherichia coli by metabolic engineering.

The efficiency of conversion of raw material to product is a major factor controlling the commercial viability of large-scale fermentation processes for the production of metabolites. Traditional approaches to developing microbial strains for metabolite overproduction have relied on amplifying only the enzymatic steps within the specific biosynthetic pathway of a desired product. While this approach has generally been successful for reaching high product concentrations and yields, further improvements (and hence reduced manufacturing cost) can only be achieved by redirecting carbon flux from central metabolism to the product-forming pathway. Such manipulation of central metabolic pathways promises to deliver a new generation of metabolite-producing microorganisms.

Amino Acids↗
PubMed1996

The laryngeal mask airway: a new technique for fiberoptic guided vocal cord biopsy.

STUDY OBJECTIVE: To describe a new technique for vocal cord biopsy involving placement of a laryngeal mask airway (LMA) during general anesthesia and fiberoptic guided biopsy. To report our early experience with this technique. DESIGN: Descriptive study. SETTING: Teaching hospital. PATIENTS: 10 patients undergoing vocal cord biopsy for minor laryngeal pathology and with no evidence of infraglottic airway obstruction. INTERVENTIONS: Patients were premedicated 1 hour preoperatively with pethidine 1 mg/kg and atropine 0.01 mg/kg. Following preoxygenation, anesthesia was induced with propofol 2.5 mg/kg and fentanyl 1 mg/kg. Once airway control was established with a facemask, vecuronium 0.1 mg was given and anesthesia established with oxygen (O2) and nitrous oxide mixture and isoflurane 1% to 2%. Gentle direct laryngoscopy was then performed to inspect the pharyngeal structures and the LMA was then inserted in the standard manner by highly experienced LMA users. A fiberoptic scope was passed via a self-sealing mount down the shaft of the LMA to the level of the vocal cords. The vocal cords were then sprayed with local anesthetic and the biopsy taken. MEASUREMENTS AND MAIN RESULTS: The age and weight range were 29 to 57 years and 65 to 85 kg, respectively. All patients were smokers or recent ex-smokers. LMA insertion was readily achieved in all patients, and an excellent view of the vocal cords was obtained. There were no problems with ventilation or obtaining tissue samples, and O2 saturation remained greater than 95% throughout the perioperative period. Tissue samples were adequate in all patients. Hypertension and other adverse cardiac events did not occur during the procedure, which lasted 10 to 20 minutes. There were no problems during emergence from anesthesia, and all patients were discharged home on the same day. CONCLUSIONS: The technique has potential advantages over suspension microlaryngoscopy in that it is relatively noninvasive, it allows good airway control with adequate views of the vocal cords, and it facilitates a smooth recovery.

Adult↗
PubMed1996

Pathway engineering for the production of aromatic compounds in Escherichia coli.

Glucose is the preferred substrate for certain fermentation processes. During its internalization and concomitant formation of glucose-6-phosphate through the glucose phosphotransferase system (PTS), one molecule of phosphoenolpyruvate (PEP) is consumed. Together with erythrose 4-phosphate (E4P), PEP is condensed to form 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP), the first intermediate of the common segment of the aromatic pathway. From this metabolic route, several commercially important aromatic compounds can be obtained. We have selected Escherichia coli mutants that can transport glucose efficiently by a non-PTS uptake system. In theory, this process should increase the availability of PEP for other biosynthetic reactions. Using these mutants, in a background where the DAHP synthase (the enzyme that catalyzes the condensation of PEP and E4P into DAHP) was amplified, we were able to show that at least some of the PEP saved during glucose transport, can be redirected into the aromatic pathway. This increased carbon commitment to the aromatic pathway was enhanced still further upon amplification of the E. coli tktA gene that encodes for a transketolase involved in the biosynthesis of E4P.

3-Deoxy-7-Phosphoheptulonate Synthase↗
PubMed1996

The laryngeal mask airway--anatomical and physiological implications.

The laryngeal mask airway (LMA) is a relatively new general purpose airway which fills a niche between the face mask and tracheal tube, both in terms of anatomical location and degree of invasiveness. It sits in the hypopharynx at the interface between the gastrointestinal and respiratory tracts, where it forms a circumferential low pressure seal around the glottis. This has advantages in terms of gas flow through the upper airway and allows direct access to the glottis without loss of airway control. LMA insertion can be considered in the context of swallowing and combines the ability to insert blindly whilst avoiding collision with highly innervated anterior pharyngeal structures. This review deals briefly with the concepts behind LMA design and insertion, and focuses on the anatomical and physiological implications of the LMA with respect to the swallowing reflex, the oesophagus, the pharyngeal mucosa, pulmonary defences, pulmonary mechanics and the cardiovascular system. The possible role of the LMA as a monitor of anaesthetic depth and areas of future research are also discussed.

Anesthesia↗