Effect of sampling site, repeated sampling, pH, and PCO2 on plasma lactate concentration in healthy dogs

OBJECTIVE

To characterize the variation in plasma lactate concentration among samples from commonly used blood sampling sites in conscious, healthy dogs.

ANIMALS

60 healthy dogs.

PROCEDURE

Cross-sectional study using a replicated Latin square design. Each dog was assigned to 1 of 6 groups (n = 10) representing all possible orders for 3 sites (cephalic vein, jugular vein, and femoral artery) used to obtain blood. Samples were analyzed immediately, by use of direct amperometry for pH, PO2, Pco2, glucose, and lactate concentration.

RESULTS

Significant differences in plasma lactate concentrations were detected among blood samples from the cephalic vein (highest), femoral artery, and jugular vein (lowest). Mean plasma lactate concentration in the first sample obtained, irrespective of sampling site, was lower than in subsequent samples. Covariation was identified among plasma lactate concentration, pH, and PCO2, but correlation coefficients were low.

CONCLUSIONS AND CLINICAL RELEVANCE

Plasma lactate concentrations differed among blood samples from various sites. A reference range for plasma lactate concentration was 0.3 to 2.5 mmol/L. Differences in plasma lactate concentrations among samples from various sites and with repeated sampling, in healthy dogs, are small. Use of the reference range may facilitate the clinical use of plasma lactate concentration in dogs.

An immunoluminometric assay for N-terminal pro-brain natriuretic peptide: development of a test for left ventricular dysfunction

Measurement of plasma levels of brain natriuretic peptide (BNP) has been used to assess left ventricular dysfunction and prognosis. Levels of the N-terminus of the precursor of BNP (NT-proBNP) have been reported to be elevated to a greater extent than BNP in left ventricular dysfunction. We have devised a non-radioactive sensitive and specific assay for NT-proBNP based on a competitive ligand binding principle. The chemiluminescent label 4-(2-succinimidyloxycarbonylethyl)phenyl-10-methylacridinium 9-carboxylate fluorosulphonate was used to label peptides representing domains in the middle and C-terminal sections of NT-proBNP. Assay of the C-terminal section of NT-proBNP (amino acids 65-76) in patients with proven left ventricular dysfunction [left ventricular wall motion index median 0.9 (range 0.3-1.4)] revealed elevated values [median 639 (386-911) fmol/ml] compared with normal controls [left ventricular wall motion index of 2 in all, NT-proBNP median 159 (120-245) fmol/ml, P<0.001]. Measurement of the middle section of NT-proBNP (amino acids 37-49) was not a discriminating test. It is thus possible to derivatize small peptides with a methyl acridinium label and preserve immunodetection with specific antibodies. Such methodology may allow non-radioactive immunoluminometric assays to be devised.

Synthesis and biological evaluation of novel 2-deoxy-4-thio-imidazole nucleosides

A study on the use of 3'-directing groups for the synthesis of imidazole 2'-deoxy-4'-thionucleosides led to varying alpha:beta ratios in the glycosylation reaction. The para-nitrobenzoyl group gave the optimum result in the glycosylation step; therefore, this protected thiosugar 10b was used for the synthesis of a series of novel 2'-deoxy-4'-thio-imidazole nucleosides which have been evaluated for antiviral activity in vitro.

Comparison of sevoflurane and propofol with rocuronium for modified rapid-sequence induction of anaesthesia

We compared the use of sevoflurane and propofol with three different doses of rocuronium for modified rapid-sequence induction of anaesthesia. One hundred and forty adult patients were randomly allocated to have a rapid-sequence intravenous induction with propofol 2-3 mg.kg-1 (group P) or an inhalational induction with sevoflurane 8% in oxygen, using a vital capacity technique (group S). Following loss of the eyelash reflex, cricoid pressure was applied and 20 patients in each group were administered rocuronium 0.3 (groups P/0.3 and S/0.3), 0.45 (groups P/0.45 and S/0.45) or 0.6 (groups P/0.6 and S/0.6) mg.kg-1. An additional 10 patients in each group received only saline placebo in place of the muscle relaxant (groups P/Saline and S/Saline). Laryngoscopy was started 60 s later and intubating conditions evaluated by a blinded anaesthetist according to a standard scoring system. Intubating conditions were acceptable in one patient and no patient, respectively, following induction with sevoflurane and propofol without the muscle relaxant. The conditions were acceptable in 30, 55 and 90% of subjects with sevoflurane induction, and in 45, 80 and 90% of subjects with propofol induction following 0.3, 0.45 and 0.6 mg.kg-1 of rocuronium, respectively (no significant difference for each dose of rocuronium). The present study shows that intubating conditions during a rapid-sequence induction using rocuronium 0.6 mg.kg-1 following induction of anaesthesia with sevoflurane or propofol are similar.

Bolus dose remifentanil for control of haemodynamic response to tracheal intubation during rapid sequence induction of anaesthesia

The effect of three bolus doses of remifentanil on the pressor response to laryngoscopy and tracheal intubation during rapid sequence induction of anaesthesia was assessed in a randomized, double-blind, placebo-controlled study in four groups of 20 patients each. After preoxygenation, anaesthesia was induced with thiopental 5-7 mg kg-1 followed immediately by saline (placebo) or remifentanil 0.5, 1.0 or 1.25 micrograms kg-1 given as a bolus over 30 s. Cricoid pressure was applied just after loss of consciousness. Succinylcholine 1 mg kg-1 was given for neuromuscular block. Laryngoscopy and tracheal intubation were performed 1 min later. Arterial pressure and heart rate were recorded at intervals until 5 min after intubation. Remifentanil 0.5 microgram kg-1 was ineffective in controlling the increase in heart rate and arterial pressure after intubation but the 1.0 and 1.25 micrograms kg-1 doses were effective in controlling the response. The use of the 1.25 micrograms kg-1 dose was however, associated with a decrease in systolic arterial pressure to less than 90 mm Hg in seven of 20 patients.

Novel ribosomal mutations affecting translational accuracy, antibiotic resistance and virulence of Salmonella typhimurium

Many mutations in rpsL cause resistance to, or dependence on, streptomycin and are restrictive (hyperaccurate) in translation. Dependence on streptomycin and hyperaccuracy can each be reversed phenotypically by mutations in either rpsD or rpsE. Such compensatory mutations have been shown to have a ram phenotype (ribosomal ambiguity), increasing the level of translational errors. We have shown recently that restrictive rpsL alleles are also associated with a loss of virulence in Salmonella typhimurium. To test whether ram mutants could reverse this loss of virulence, we have isolated a set of rpsD alleles in Salmonella typhimurium. We found that the rpsD alleles restore the virulence of strains carrying restrictive rpsL alleles to a level close to that of the wild type. Unexpectedly, three out of seven mutant rpsD alleles tested have phenotypes typical of restrictive alleles of rpsL, being resistant to streptomycin and restrictive (hyperaccurate) in translation. These phenotypes have not been previously associated with the ribosomal protein S4. Furthermore, all seven rpsD alleles (four ram and three restrictive) can phenotypically reverse the hyperaccuracy associated with restrictive alleles of rpsL. This is the first demonstration that such compensations do not require that the compensating rpsD allele has a ribosomal ambiguity (ram) phenotype.

Evaluation of remifentanil for control of haemodynamic response to tracheal intubation

We have studied the effect of three bolus doses of remifentanil on the haemodynamic response to laryngoscopy and tracheal intubation. Using a double-blind design, 80 ASA 1 or 2 patients presenting for elective surgery received saline placebo or remifentanil 0.25, 0.5 or 1.0 microgram.kg-1 by random allocation. Anaesthesia was induced with thiopentone 5-7 mg.kg-1 and followed immediately by the study medication given as a bolus over 30s. Muscle relaxation was provided with rocuronium 0.75 mg.kg-1. The patients' tracheas were intubated under direct laryngoscopy 1 min later. Noninvasive arterial blood pressure and heart rate were recorded immediately before induction of anaesthesia and then at intervals until 5 min after tracheal intubation. There was a significant increase in heart rate (p < 0.01) and systolic arterial pressure (p < 0.01) in all groups after tracheal intubation. However, this was short-lived and of a smaller magnitude in the remifentanil 1 microgram.kg-1 group in which the increase was significantly lower than in the control group (p < 0.01).

Comparison of the traditional paper visual analogue scale questionnaire with an Apple Newton electronic appetite rating system (EARS) in free living subjects feeding ad libitum

OBJECTIVE

Assessing the value of a newly developed electronic visual analogue scale questionnaire (Apple Newton Message Pad) with the traditional paper method for appetite rating.

DESIGN

In a random, crossover design, subjects completed both electronic and paper questionnaires to compare results obtained by the two methods; individual methods were completed consecutively to assess test-retest reliability; preference was established using a questionnaire.

SETTING/SUBJECTS

Healthy, free-living adults were studied for comparison of methods (n = 12), test-retest reliability (n = 8) and preference (n = 13).

INTERVENTION

Visual analogue scales were completed each waking hour to assess appetite. Preference was assessed after both methods were completed.

RESULTS

There was no significant difference in the hourly results obtained by the paper and electronic methods for 'desire to eat', 'how much can you eat now', 'urge to eat' and 'preoccupation with thoughts of food'. Small differences in 'hunger' and 'fullness' ratings were noted (approximately 5% mean difference between methods, P < 0.05), but patterns of change and sensitivity for these and all other parameters remained similar for both methods across the visual analogue scale. Test-retest reliability demonstrated was similar for both methods. Seven (54%) subjects preferred to use the paper questionnaire, five (38%) the electronic method and one (8%) had no preference.

CONCLUSIONS

The electronic Apple Newton questionnaire is as sensitive and reliable as the paper method, has the advantage that it automatically records the time of data acquisition and data collection and processing are more efficient for the researcher. The two methods should not be used interchangeably.

The natural history of fetomaternal alloimmunization to the platelet-specific antigen HPA-1a (PlA1, Zwa) as determined by antenatal screening

Immunization against the human platelet antigen (HPA)-1 alloantigen is the most common cause of severe fetal and neonatal thrombocytopenia. Fetal therapy has substantial risks and its indications need better definition. Of 24,417 consecutive pregnant women, 618 (2.5%) were HPA-1a negative of whom 385 entered an observational study. All were HLA-DRB3*0101 genotyped and screened for anti-HPA-1a. Their partners and neonates were HPA-1 genotyped and the latter were assessed by cord blood platelet counts and cerebral ultrasound scans. Anti-HPA-1a was detected in 46 of 387 pregnancies (12.0%; 95% CI 8.7%-15.2%). All but one were HLA-DRB3*0101 positive (odds ratio 140; 95% CI 19-1035; P< .00001). One baby died in utero, and of 26 HPA-1a-positive babies born to women with persistent antenatal antibodies, 9 were severely thrombocytopenic (8 with a count <10 x 10(9)/L, 1 with a large porencephalic cyst), 10 were mildly thrombocytopenic, whereas 7 had normal platelet counts. Severe thrombocytopenia was significantly associated with a third trimester anti-HPA-1a titer >/= 1:32 (P = . 004), but was not observed in babies of women with either transient or postnatal-only antibodies. HPA-1a alloimmunization complicates 1 in 350 unselected pregnancies, resulting in severe thrombocytopenia in 1:1,200. HPA-1a and HLA-DRB3*0101 typing combined with anti-HPA-1a titration allows selection of the majority of pregnancies at risk of severe thrombocytopenia.

[Antibiotic resistance here to stay? Compensatory mutations restore virulence of resistant bacteria]

Bacterial antibiotic resistance has increased alarmingly because of overuse of antibiotics both in humans and animals. One way of reversing this development is to reduce the use of antibiotics, thus promoting the disappearance of the resistant bacteria already present in humans and the environment. This approach is based on the assumption that resistance is conferred at the cost of impaired survival fitness in the absence of antibiotics, as compared with sensitive strains. It seems to be generally true that resistant bacteria are less fit than the respective sensitive strains, which suggests that resistance may be reversible. However, a complicating factor is the frequent finding in resistant strains of various types of compensatory mutations that restore fitness without concomitant loss of resistance. Thus, second-site compensatory mutations may allow resistant strains to persist and compete successfully with sensitive strains even in an environment depleted of antibiotics. It is concluded in the article that, if compensatory mutations are as common in clinical settings as they are in the laboratory, many types of resistance will be irreversible.

The direct costs to the NHS of discontinuing and switching prescriptions for hypertension

There is much evidence to suggest that the treatment of hypertension reduces the risk of cardiovascular diseases and that it is cost-effective in most patients. However, the effectiveness of treatment relies on compliance and maintenance of treatment. Each pharmacological agent differs in terms of side effects. The existence of side effects can result in poor compliance and switching between treatments. A number of studies have reported high discontinuation rates for anti-hypertensive therapies. This potentially imposes costs on the health service. The aim of this study is to use the MEDIPLUS data set to consider the cost arising from switching and discontinuation of therapy. The analysis will assess the resource costs in terms of extra GP visits and hospitalisations arising from individuals switching and discontinuing treatments. The total costs of hypertension were estimated to be around 76.5 m pound sterling per annum, of which 26.9 m pound sterling can be attributed to patients who switch or discontinue therapy.

In-vitro activity of piperacillin/tazobactam relative to other antibiotics against blood culture isolates

Resistance of bacteria to antibiotics is an increasing problem in many countries. Accurate locally relevant information is essential for detection and control of emerging resistance and to facilitate choice of empirical antibiotic therapy in the immediate management of seriously ill patients. We have determined the minimum inhibitory concentration of piperacillin/tazobactam for 97 strains of bacteria (55 Enterobacteriaceae, 13 non-fermentative Gram-negative bacilli, 22 Staphylococcus aureus, 6 Enterococcus faecalis and 1 Bacillus cereus) isolated from blood cultures and compared its activity to that of amoxycillin, co-amoxiclav, cephalothin, cefotaxime, ceftazidime, ciprofloxacin, gentamicin, piperacillin, cefotaxime. The strains were consecutive non-fastidious isolates with the following qualifications: coagulase negative staphylococci and diphtheroids were excluded and the number of Staphylococcus aureus isolates was limited to 12 methicillin-resistant and 10 methicillin-sensitive strains. Multiple isolates of the same species from individual patients were not included. The minimum inhibition concentrations of methicillin, penicillin, teichoplanin and vancomycin were also determined for specific groups of organisms. MICs were determined by the Etest method (AB Biodisk, Solna, Sweden) on Mueller Hinton agar. The MICs of appropriate American Type Culture Collection control strains were determined. Based on the interpretative criteria of the National Committee for Clinical Laboratory Standards (USA), 87 per cent of Gram-negative bacilli were susceptible to piperacillin/tazobactam compared with amoxycillin 26 per cent, cephalothin 35 per cent, co-amoxiclav 54 per cent, piperacillin 56 per cent, cefotaxime 69 per cent, ceftazidime 84 per cent, gentamicin 85 per cent and ciprofloxacin 91 per cent. Of all isolates 75 per cent were sensitive to piperacillin/tazobactam, compared with amoxycillin 22 per cent, cephalothin 35 per cent, piperacillin 41 per cent, co-amoxiclav 52 per cent, cefotaxime 59 per cent, ceftazidime 60 per cent, gentamicin 74 per cent and ciprofloxacin 77 per cent. Two isolates (1 E. coli and 1 Klebsiella pneumoniae) with antibiograms consistent with the relatively new resistance phenomenon of extended spectrum beta-lactamase production were identified. The spectrum of activity of piperacillin-tazobactam for empirical antibiotic therapy is significantly greater than that of piperacillin alone and is similar to that of ciprofloxacin and gentamicin.

Community health monitoring: taking the pulse of America's children

OBJECTIVE

To describe the development, content, enablers/barriers, and impact of child health reports in nine communities participating in the Robert Wood Johnson Foundation funded Child Health Initiative (1991-1996).

METHODS

A qualitative, prospective, multiyear, longitudinal evaluation using a multiple case-study methodology. Three waves of structured in-person and telephone interviews of the project staff, community leaders, and key participants tracked the development of child health reports in all nine communities. A mailed survey of project directors was administered to assess accomplishments at the completion of the project. Content analysis of each community health report was conducted using different conceptual frameworks for health measurement and reporting.

RESULTS

All communities succeeded in creating a report that contained a broad set of outcome indicators reflecting children's health and well-being. The process of creating these reports, their content, level of analysis, presentation formats, and dissemination varied across sites based on available resources, data and analysis capacity, and other political considerations. While commonly accepted outcome measures were used in most reports (e.g., infant mortality, teen births, immunization rates), process indicators, important for quality monitoring and community health improvement, were notably lacking. In each community the reports were credited with providing a more comprehensive and integrated view of the health needs of children.

CONCLUSIONS

Additional conceptual and technical work is needed to improve the ability of community health reports to capture key indicators of interest. Community reports can serve an important role in building the consensus needed to create program and policy changes. Community reports may have additional utility in monitoring the impact of health systems change on population health. Community reports can also facilitate a shared learning process for the participants and the community, and can be a useful tool to advance a children's health policy agenda.

Using bioscience knowledge in nursing: actions, interactions and reactions

This paper draws on empirical data from a study undertaken to explore the outcomes of the applied physiology component of a post-registration diploma in nursing (DN). Most students completing the DN were utilizing their new bioscience knowledge in clinical practice, and reported increased participation in interprofessional discussions and team decisions. Respondents found themselves better able to monitor and evaluate doctors' decisions and this led to friction with some medical colleagues. However, the strongest resistance came from senior nurses, very few of whom had completed advanced nursing courses in bioscience and who were generally unwilling to allow respondents to develop new roles. General managers were also perceived as a major barrier to change. There is little evidence of tangible benefits to the nurses themselves: most saw the DN qualification as a way of protecting their status as professional nurses in the face of managerially driven organizational change, rather than as a route to occupational advancement.

Virulence of antibiotic-resistant Salmonella typhimurium

We show that most Salmonella typhimurium mutants resistant to streptomycin, rifampicin, and nalidixic acid are avirulent in mice. Of seven resistant mutants examined, six were avirulent and one was similar to the wild type in competition experiments in mice. The avirulent-resistant mutants rapidly accumulated various types of compensatory mutations that restored virulence without concomitant loss of resistance. Such second-site compensatory mutations were more common then reversion to the sensitive wild type. We infer from these results that a reduction in the use of antibiotics might not result in the disappearance of the resistant bacteria already present in human and environmental reservoirs. Thus, second-site compensatory mutations could increase the fitness of resistant bacteria and allow them to persist and compete successfully with sensitive strains even in an antibiotic-free environment.

Concentration of ionized calcium in plasma from cats with urethral obstruction

OBJECTIVE

To measure ionized calcium concentration in plasma from cats with urethral obstruction and to correlate these values with results of clinical biochemical analyses and physical examinations.

DESIGN

Prospective study.

ANIMALS

24 male cats.

PROCEDURE

Blood samples were obtained from each cat on admission, and PCV, pH, and concentrations of ionized calcium, total calcium, glucose, total solids, sodium, potassium, BUN, creatinine, chloride, magnesium, albumin, and phosphorus were determined. Mentation, tissue perfusion, and ECG recordings were also assessed.

RESULTS

18 (75%) cats had low ionized calcium concentrations (reference range, 2.4 to 2.8 mEq/L). Hypocalcemia was considered mild (2.0 to 2.36 mEq/L) in 9 (37.5%) cats, moderate (1.6 to 1.98 mEq/L) in 6 (25%), and severe (< 1.6 mEq/L) in 3 (12.5%). Significant positive correlations were found between ionized calcium concentration and heart rate, pH, and concentrations of sodium, chloride, and total calcium. Significant negative correlations were found between ionized calcium concentration and concentrations of potassium, BUN, creatinine, and phosphorus.

CLINICAL IMPLICATIONS

Most cats with urethral obstruction had a low concentration of ionized calcium. This may contribute to cardiac electrical and mechanical dysfunction in some severely affected cats. Although effects of i.v. administration of calcium were not evaluated, results of this study strengthen the rationale for its use in cats with urethral obstruction.

Late-onset preemptive analgesia associated with preincisional large-dose alfentanil

Few studies using systemic opioids have been adequately designed to demonstrate a preemptive effect. We investigated the preemptive effect of intraoperative large-dose intravenous (I.V.) opioids over a 72-h period after lower abdominal surgery. Thirty-eight ASA physical status I or II patients undergoing abdominal hysterectomy were studied in a prospective, randomized, double-blind design. Group PRE received alfentanil 70 microg/kg over 10 min before surgical incision; Group POST received alfentanil 70 microg/kg over 10 min after incision. Patients received no other intraoperative opioid. Pain was treated in the recovery room with 2-mg I.V. boluses of morphine and was subsequently managed via patient-controlled analgesia (PCA) using morphine sulfate. Visual analog scale pain scores at rest (VAS-R) and on movement (VAS-M) and PCA morphine consumption were recorded for 72 hours. VAS-M and VAS-R scores did not differ at any point, and morphine consumption was similar in both groups over the initial 48 h. Group PRE used significantly less morphine from 48 to 72 h postoperatively (P < 0.02). We conclude that presurgical incisional (i.e., compared with postincisional) large-dose opioid exposure results in a modest, late decrease in postoperative morphine consumption, with no clinical impact on early postoperative pain. Timing of the observed reduction coincides with maximal output of substances implicated in experimental hyperalgesia.

IMPLICATIONS

When given before surgical incision, alfentanil, a short-acting narcotic, was associated with a reduction in morphine requirements 48-72 h after surgery. Brief interventions may have a delayed and sustained impact on pain perception, possibly by reducing mechanisms of sensitization.

The macrophage scavenger receptor type A is expressed by activated macrophages and protects the host against lethal endotoxic shock

During gram-negative bacterial infections, lipopolysaccharide (LPS) stimulates primed macrophages (Mphi) to release inflammatory mediators such as tumor necrosis factor (TNF)-alpha, which can cause hypotension, organ failure, and often death. Several different receptors on Mphi have been shown to bind LPS, including the type A scavenger receptor (SR-A). This receptor is able to bind a broad range of polyanionic ligands such as modified lipoproteins and lipoteichoic acid of gram-positive bacteria, which suggests that SR-A plays a role in host defense. In this study, we used mice lacking the SR-A (SRKO) to investigate the role of SR-A in acquired immunity using a viable bacillus Calmette Guérin (BCG) infection model. We show that activated Mphi express SR-A and that this molecule is functional in assays of adhesion and endocytic uptake. After BCG infection, SRKO mice are able to recruit Mphi to sites of granuloma formation where they become activated and restrict BCG replication. However, infected mice lacking the SR-A are more susceptible to endotoxic shock and produce more TNF-alpha and interleukin-6 in response to LPS. In addition, we show that an antibody which blocks TNF-alpha activity reduces LPS-induced mortality in these mice. Thus SR-A, expressed by activated Mphi, plays a protective role in host defense by scavenging LPS as well as by reducing the release by activated Mphi of proinflammatory cytokines. Modulation of SR-A may provide a novel therapeutic approach to control endotoxic shock.

Carbon starvation of Salmonella typhimurium does not cause a general increase of mutation rates

Mutation rates in bacteria can vary depending on the genetic target studied and the specific growth conditions of the cells. Here, two different methods were used to determine how rates of mutation to antibiotic resistance, auxotrophy, and prototrophy were influenced by carbon starvation on agar plates. The rate of mutation to rifampin resistance was increased by starvation as measured by fluctuation tests, similar to what has been reported previously for Escherichia coli. In contrast, the rates of mutation to various types of auxotrophy were unaffected or decreased as measured by both fluctuation tests and a repeated-streaking procedure. Similarly, the rates of reversion to prototrophy of his and lac nonsense and missense mutations were unaffected by starvation. Thus, mutation rates of different genetic targets can be affected differently by starvation and we conclude that carbon starvation is not generally mutagenic in Salmonella typhimurium.