Biomedical subjects

S D Pratt

Publications and source records attributed to S D Pratt.

13 recordsLinked to original sources

PubMed2006

An analysis of the need for anesthetic interventions with differing concentrations of labor epidural bupivacaine: an observational study.

BACKGROUND: Labor epidural analgesia techniques using lower concentrations of bupivacaine are designed to maintain pain control with fewer side effects such as hypotension and motor block. However, the increase in sensation may allow breakthrough pain resulting in the need for additional interventions. We examined the number of interventions, both for analgesia and for treatment of side effects, required when using three concentrations of bupivacaine. METHODS: Retrospective observational investigation examining 4493 women who received epidural analgesia during two periods. In the first period, higher concentrations of bupivacaine were used (0.125% and 0.0625%, both with fentanyl 2 microg/mL). In the second period, a very low concentration was used (0.04% plus fentanyl 1.7 microg/mL and epinephrine 1.7 microg/mL). Outcomes were compared using univariate tests, and multivariate Poisson regression was used to identify independent factors influencing interventions. RESULTS: The frequencies of interventions were similar for women receiving bupivacaine concentrations of 0.04% (1.4+/-2.0) and 0.125% (1.5+/-2.0), while women receiving the 0.0625% solution required more interventions (1.8+/-2.3; P<0.001). Women who received 0.04% or 0.0625% bupivacaine required more treatment of breakthrough pain (P<0.002), while those receiving 0.125% bupivacaine required more treatment for hypotension and motor block (P<0.05). Multivariate Poisson regression showed that duration of treatment, maternal age and body mass index were independent factors for the number of interventions. CONCLUSIONS: Neither the total interventions nor intervention rate per hour varied significantly with the concentrations of bupivacaine used in this study. Lower concentrations produced fewer side effects including hypotension, while the higher concentration resulted in less breakthrough pain.

Adult↗

PubMed2001

Predictors of breakthrough pain during labor epidural analgesia.

UNLABELLED: Parturients who receive labor epidural analgesia may experience breakthrough pain that requires supplemental medications. We investigated the factors associated with breakthrough pain. This prospective observational study included 1963 parturients who received epidural analgesia. Subjects were categorized into two groups on the basis of the number of episodes of breakthrough pain: the Recurrent Breakthrough Pain (RBP) group experienced three or more episodes. Univariate and multivariate regression analyses were used to evaluate factors associated with the RBP group. By multivariate analysis, nulliparity, heavier fetal weight, and epidural catheter placement at an earlier cervical dilation were found to be independently associated with the RBP group. These factors may predict which parturients' analgesia may be complicated by breakthrough pain. Parturients who received a combined spinal/epidural technique were less likely to be associated with the RBP group. The combined spinal/epidural technique may be superior to conventional epidural anesthesia, because breakthrough pain occurred less often. It is interesting to note that the characteristics that are associated with the RBP group are similar to those that have been associated with increased severity of maternal pain. IMPLICATIONS: Nulliparity, heavier fetal weight, and epidural catheter placement at an early cervical dilation are predictors of breakthrough pain during epidural labor analgesia. The combined spinal/epidural technique may be associated with a decreased incidence of breakthrough pain.

Adult↗

PubMed2001

Biological response to variation of acid-volatile sulfides and metals in field-exposed spiked sediments.

Vertical and temporal variations of acid-volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediment can control biological impacts of metals. To assess the significance of these variations in field sediments, sediments spiked with cadmium, copper, lead, nickel, and zinc were deployed in Narragansett Bay for four months and recolonization by benthic organisms investigated. In surface sediments, concentrations of AVS decreased with time whenever AVS exceeded SEM but remained unchanged when AVS was less than SEM; in subsurface sediments, concentrations increased slightly. Concentrations of total SEM decreased with time only in surface sediments in which SEM exceeded AVS. Metals were not detected in interstitial waters of sediments where AVS exceeded SEM but were significant when SEM exceeded AVS and followed the order of solubilities of their sulfides. Concentrations in interstitial waters decreased with time, but exceeded U.S. Environmental Protection Agency chronic water quality criteria for 56 to 119 d. After 119 d, faunal assemblages in all treatments were similar to controls. Lack of biological response was related to vertical distributions of AVS and SEM. Biological exposure took place in near-surface sediments, where AVS exceeded SEM in even the highest treatments. Therefore, concentrations of metals in interstitial waters were low and consequently biological impacts were undetectable.

Acids↗

PubMed2000

An association between severe labor pain and cesarean delivery.

UNLABELLED: The relationship between epidural analgesia and cesarean delivery remains controversial. Several studies have documented an association, although others have not. This inconsistency may result from an association between severe labor pain and dystocia. We hypothesized that dystocia causes severe labor pain, such that more epidural medication is required to maintain comfort. We examined the relationship between labor outcome and severe pain, defined by the number of supplemental epidural boluses. We retrospectively reviewed the anesthesia records of 4493 parturients who received small-dose labor epidural analgesia. An independent association was found between operative delivery and maternal age, body mass index, nulliparity, fetal weight, induction of labor, and the number of boluses required during labor. By using multivariate analysis, the odds ratio of cesarean delivery among women who required at least three boluses was 2.3 compared with those who required two boluses or less. No association was found between the concentration of bupivacaine in the epidural infusion and operative delivery. Because women with cesarean deliveries appeared to have more pain, degree of labor pain may be a confounding factor in studies examining epidural analgesia and outcome. IMPLICATIONS: This is a retrospective observational study demonstrating an association between labor pain and cesarean delivery. Our results provide an alternative explanation of why epidural analgesia is associated with cesarean delivery.

Adult↗

PubMed1998

Homologs of the vancomycin resistance D-Ala-D-Ala dipeptidase VanX in Streptomyces toyocaensis, Escherichia coli and Synechocystis: attributes of catalytic efficiency, stereoselectivity and regulation with implications for function.

BACKGROUND: Vancomycin-resistant enterococci are pathogenic bacteria that have altered cell-wall peptidoglycan termini (D-alanyl-D-lactate [D-Ala-D-lactate] instead of D-alanyl-D-alanine [D-Ala-D-Ala]), which results in a 1000-fold decreased affinity for binding vancomycin. The metallodipeptidase VanX (EntVanX) is key enzyme in antibiotic resistance as it reduces the cellular pool of the D-Ala-D-Ala dipeptide. RESULTS: A bacterial genome search revealed vanX homologs in Streptomyces toyocaensis (StoVanX), Escherichia coli (EcoVanX), and Synechocystis sp. strain PCC6803 (SynVanX). Here, the D,D-dipeptidase catalytic activity of all three VanX homologs is validated, and the catalytic efficiencies and diastereoselectivity ratios for dipeptide cleavage are reported. The ecovanX gene is shown to have an RpoS (sigma(s))-dependent promoter typical of genes turned on in stationary phase. Expression of ecovanX and an associated cluster of dipeptide permease genes permitted growth of E. coli using D-Ala-D-Ala as the sole carbon source. CONCLUSIONS: The key residues of the EntVanX active site are strongly conserved in the VanX homologs, suggesting their active-site topologies are similar. StoVanX is a highly efficient D-Ala-D-Ala dipeptidase; its gene is located in a vanHAX operon, consistent with a vancomycin-immunity function. StoVanX is a potential source for the VanX found in gram-positive enterococci. The catalytic efficiencies of D-Ala-D-Ala hydrolysis for EcoVanX and SynVanX are 25-fold lower than for EntVanX, suggesting they have a role in cell-wall turnover. Clustered with the ecovanX gene is a putative dipeptide permease system that imports D-Ala-D-Ala into the cell. The combined action of EcoVanX and the permease could permit the use of D-Ala-D-Ala as a bacterial energy source under starvation conditions.

Amino Acid Sequence↗

PubMed1998

The structure of VanX reveals a novel amino-dipeptidase involved in mediating transposon-based vancomycin resistance.

VanX is a zinc-dependent D-alanyl-D-alanine dipeptidase that is a critical component in a system that mediates transposon-based vancomycin resistance in enterococci. It is also a key drug target in circumventing clinical vancomycin resistance. The structure of VanX from E. faecium has been solved by X-ray crystallography and reveals a Zn(2+)-dipeptidase with a unique overall fold and a well-defined active site confined within a cavity of limited size. The crystal structures of VanX, the VanX:D-alanyl-D-alanine complex, the VanX:D-alanine complex, and VanX in complex with phosphonate and phosphinate transition-state analog inhibitors, are also presented at high resolution. Structural homology searches of known structures revealed that the fold of VanX is similar to those of two proteins: the N-terminal fragment of murine Sonic hedgehog and the Zn(2+)-dependent N-acyl-D-alanyl-D-alanine carboxypeptidase of S. albus G.

Alanine↗

PubMed1997

Controversies in third molar surgery--the national view on review strategies.

A national survey was conducted to establish the current practice of postoperative review of third molar surgery by the 255 fellows of the British Association of Oral and Maxillofacial Surgeons. Of the 216 complete responses, 134 say that they routinely reviewed all patients, while 67 did not. A further 15 fellows (7%) are currently considering their practice. Five (2%) stated that routine review should be compulsory and failure to do so was medically negligent. We conclude that a policy of selective rather than routine review is safe for most patients, but if a patient is under age, mentally retarded, taking psychoactive drugs, or has any other associated condition, then routine follow-up should be undertaken.

Age Factors↗

PubMed1997

Isolation, cloning, and expression of a 70-kilodalton plasminogen binding protein of Borrelia burgdorferi.

Surface receptors for plasminogen are expressed by many gram-positive and gram-negative bacteria and may play a role in the dissemination of organisms by binding plasminogen, which upon conversion to plasmin can digest extracellular matrix proteins. Two plasminogen binding proteins have been identified for Borrelia burgdorferi, outer surface protein A and a 70-kDa protein (BPBP). We purified BPBP by plasminogen affinity chromatography and obtained its amino acid sequence by Edman degradation of a tryptic digest. The gene coding for BPBP was isolated from a lambda-ZAP II genomic library with probes developed from sequenced portions of the protein. This gene was expressed in Escherichia coli; the recombinant product was seen by antibody raised against native BPBP and also bound 125I-labeled plasminogen. The experimentally derived amino acid sequences corresponded to the predicted sequence encoded by the BPBP gene. The deduced amino acid sequence for BPBP revealed significant similarity to p30, a 30-kDa protein of B. burgdorferi (54% identity and 65% similarity), to a 60-kDa protein in Borrelia coriaceae (66% identity and 80% similarity), to oligopeptide binding protein A of E. coli (34% identity and 57% similarity), and, more generally, to the periplasmic oligopeptide binding family of proteins.

Amino Acid Sequence↗

PubMed1995

Substrate requirements for ErmC' methyltransferase activity.

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.

Bacillus subtilis↗

PubMed1993

High-level synthesis of the 12-kDa human FK506-binding protein in Escherichia coli using translational coupling.

The gene encoding the 12-kDa cytosolic form of human FK506-binding protein (hFKBP-12) was isolated from a Jurkat T-cell cDNA library and expressed in three different non-fusion systems in Escherichia coli. Expression of recombinant hFKBP-12 (re-hFKBP-12) from the trc promoter vector, pKK233-2, yielded low levels of protein. A second system, which utilized a modified lac promoter and a stronger ribosome-binding site, showed greatly improved expression. A third system, utilizing translational coupling to an upstream segment of kdsB under the control of this modified lac promoter, produced re-hFKPB-12 at a very high level. The re-hFKBP-12 produced via translational coupling was soluble and was shown to have the authentic N terminus. The level of active re-hFKBP-12 produced from this vector was estimated to be 50% of total soluble protein, based on competition with the fusion protein, CKS::re-hFKBP-12, for binding to ascomycin-C22-carboxymethyloxime-alkaline phosphatase.

Alkaline Phosphatase↗

PubMed1993

Analysis of the humoral response to the flagellin protein of Borrelia burgdorferi: cloning of regions capable of differentiating Lyme disease from syphilis.

Selected regions of the Borrelia burgdorferi flagellin gene (fla) that exhibit high or low homology with related genes from other bacterial species were amplified by the polymerase chain reaction and expressed as fusion proteins in Escherichia coli. Purified fusion proteins were assayed for antibody reactivity in a microtiter plate enzyme-linked immunosorbent assay with sera from Lyme disease patients as well as syphilitic and normal sera. Immunoglobulin G antibody from Lyme disease patient sera reacted predominantly with the central portion of the protein. The region of the flagellin protein encompassing amino acids 64 to 311 detected nearly all of the immunoglobulin G-positive Lyme sera and only reacted with 1 of 26 syphilis patient serum samples. In contrast, 12 of 26 syphilis patient serum samples and 2 of 47 normal serum samples reacted with the amino terminus of the flagellin protein, whereas 4 of 26 syphilis patient serum samples and 7 of 47 normal serum samples reacted with the carboxyl terminus. The central region containing amino acids 64 to 311 may be employed diagnostically to differentiate antibodies to B. burgdorferi from antibodies to Treponema pallidum. In addition, this region also was recognized by immunoglobulin M in the Lyme patient sera, indicating its potential usefulness as a marker for early Lyme disease.

Antibodies, Bacterial↗

PubMed1992

High-level expression of recombinant human FK-binding protein from a fusion precursor.

The human peptidyl-prolyl isomerase FK-binding protein (FKBP) was cloned as a fusion partner with CMP-KDO synthetase (CKS), and the resultant construct was characterized as an improved high-expression source for FKBP. The CKS-FKBP fusion was expressed as a soluble protein at levels approaching 1 gm/L in Escherichia coli fermentations. The fusion protein was purified to near homogeneity by a one-step ammonium sulfate fractionation of whole cell lysate. After selective cleavage, the fusion precursor produced yields approaching 300 mg of purified FKBP per liter of harvested culture, a approximately 30 to 60-fold increase over that observed for a nonfusion construct. Selective cleavage of the fusion partners was accomplished using either hydroxylamine or specific, limited proteolysis. Once separated from the CKS fusion partner, the FKBP was isolated in a single step by either reversed-phase HPLC or chromatography on Q-Sepharose. For comparison of physical and chemical properties, a nonfusion construct of recombinant human FKBP was expressed in E. coli and isolated. The purified FKBPs exhibited expected SDS-PAGE molecular weights and N-terminal sequences. The proteins had similar proton NMR spectra and binding to [3H]FK-506. The fusion construct, CKS-FKBP, was also found to bind [3H]FK-506. These data indicate that FKBP fused to the C-terminus of CKS folds independently of the fusion partner and suggests the fused FKBP adopts a conformation resembling that of the native protein.

Amino Acid Isomerases↗

PubMedDate not supplied

Low dose intrathecal ropivacaine with or without sufentanil provides effective analgesia and does not impair motor strength during labour: a pilot study.

PURPOSE: Although ropivacaine has been used to provide spinal anesthesia in the surgical population, its intrathecal administration for labour analgesia has only recently been described. We evaluated the effects of low dose intrathecal ropivacaine with or without sufentanil for labour analgesia. METHODS: Thirty-six term parturients in active labour were randomly assigned to receive 3 mg of intrathecal ropivacaine (group R) or 3 mg ropivacaine with 10 microg of sufentanil (group RS). Patients were evaluated by a blinded observer for hypotension, linear analogue score (VAS 0-100) for labour pain, motor power in the lower limbs, onset of analgesia, sensation to cold and pin prick, duration of analgesia, and neonatal Apgar scores. The following day patients were assessed for satisfaction, headache and neurologic deficit. RESULTS: The mean duration of analgesia in the R group was 41.4 +/- 4.9 min and 95.0 +/- 6.1 min in the RS group (mean +/- SEM, P=0.0001). All subjects had satisfactory analgesia at five minutes, although analgesia from the ropivacaine- sufentanil combination was superior to that provided by ropivacaine alone. Total duration of labour was no different between the groups (R- 306 +/- 34, RS- 384 +/- 44 min, P=0.17). No patient showed evidence of motor block. All patients were satisfied with the labour analgesia. No neurological complications were observed. CONCLUSIONS: Low dose ropivacaine provides effective analgesia during labour via the intrathecal route. It can be mixed with sufentanil in the above-mentioned concentrations to improve both the quality and duration of analgesia. Fetal outcome remains favourable. It may provide minimal or no motor block, to facilitate ambulation.

Adjuvants, Anesthesia↗