Hamartoma affecting ampullary electroreceptors and epitheliotropic lymphoma in a captive electric eel Electrophorus varii.

Few reports are available describing lesions in captive electric eels Electrophorus spp. This report describes 2 types of cutaneous proliferative lesions (i.e. hamartoma and neoplasm) in a captive electric eel. Ampullary electroreceptor hamartomas appeared grossly as 2 discrete, smooth, pink, spherical, cutaneous masses measuring 6 and 18 mm in diameter. Histologically, hamartomas were composed of predominately spindle cells that were separated into lobules by a peripheral rim of polygonal cells. Spindle cells were arranged in vague streams and occasionally whorls within a myxomatous matrix. Polygonal cells arranged in variably sized trabeculae and cords within a pre-existing fibrovascular stroma surrounded the streams of spindle cells. Admixed with the polygonal cell population were multiple mucous glands and alarm cells, similar to those seen in normal regions of epidermis. Histochemical stains confirmed similar components in the normal ampullary electroreceptor as in the hamartomas. Lymphoma was also present, appearing grossly as patchy pitting, erythematous, and thickened areas of the skin affecting the entire animal. Lymphoma was diffusely infiltrating and expanding the epidermis, oral mucosa, and branchial mucosa up to 1.5 mm in thickness. It was composed of an unencapsulated, well-demarcated, moderately cellular neoplasm composed of lymphocytes arranged in small dense sheets and clusters that separated and effaced epidermal cells. This is the first report of lymphoma in an electric eel, and the first report of ampullary electroreceptor hamartoma in any animal species.

Qualitative needs assessment: healthcare experiences of underserved populations in Montgomery County, Virginia, USA.

INTRODUCTION: Portions of Montgomery County, Virginia, are designated a Medically Underserved Area with a large portion of this population experiencing limited access to healthcare services. In September 2008, the Federal Bureau of Primary Care awarded the authors a planning grant to assess community need in Montgomery County and to develop a strategic plan to establish a Federally Qualified Health Center (FQHC) to best meet these needs. An FQHC is a federally funded clinic mandated to provide medical, dental and mental health services to underserved communities. As part of the planning process, the decision was made to include qualitative data to better understand the needs of underserved residents in the community. Descriptive studies of target populations can provide further insight into community priorities for effective health improvement and planning. The objective of the study was to investigate and describe the perceptions, beliefs and practices that impact healthcare utilization among underserved populations in Montgomery County, Virginia. This study was conducted as part of a comprehensive community assessment to determine the feasibility of developing a FQHC. METHODS: Community focus groups were conducted with target populations which were representative of the community. A thematic analysis of the transcribed field notes and group interviews was conducted. Qualitative data analysis was performed using the Analysis Software for Word-Based Records (AnSWR) developed by the Centers for Disease Control. RESULTS: Three important categories of beliefs which may impact healthcare utilization emerged from the discussions: (1) cultural health perceptions; (2) perceived barriers to care; and (3) coping strategies. Participants expressed a right to access quality care, preferred to spend money on basic living expenses rather than healthcare services; frequently neglected seeking care for adults while rarely neglecting to seek care for their children; valued but infrequently utilized preventative care; and had a lack of confidence in the care that was provided. Perceived barriers to healthcare services reported by participants included a lack of access to affordable care; complexities of health insurance and payer status; limited hours of clinic operation; lack of transportation and geographic distance; and the complexity of navigating the healthcare system. Finally, participants reported using various coping strategies to overcome barriers to accessing healthcare services. These strategies included delaying treatment and self-care; seeking financial and transportation assistance; and using community resources to navigate the system. CONCLUSION: Establishing care that is culturally relevant, targets perceived barriers and incorporates and enhances coping strategies is needed to increase accessibility and utilization of preventative and comprehensive healthcare services. The findings from this study will assist in creating a strategic plan for a FQHC that capitalizes on community strengths while addressing the challenges and complex needs of the community.

Endocardiosis in Tetras (Family Characiformes).

Proliferative, myxomatous change was identified in the cardiac valves (i.e. valvular endocardiosis) with extension into some cardiac walls (i.e. mural endocardiosis) of five tetras (four neon tetras [Paracheirodon innesi] and one rummynose tetra [Hemigrammus rhodostomus]). Review of cardiac sections from tetras (family Characiformes) submitted to two diagnostic laboratories revealed a prevalence of endocardiosis in tetras of 4.3% and 5.7%, respectively. In four cases, concurrent disease that could be a primary cause of death was not identified, and endocardiosis was considered the primary cause of death; in the fifth case, egg binding was present concurrently. This retrospective case series suggests that endocardiosis is a significant concern in fish of the family Characiformes.

Graft-versus-leukaemia effect post fludarabine, melphalan and alemtuzumab reduced intensity allogeneic stem cell transplantat in HIV-infected patient with acute myeloid leukaemia.

Allogeneic stem cell transplantation (Allo-HSCT) is sine qua non to cure high-risk acute myeloid leukaemia (AML). In spite the advent of highly active antiretroviral treatment, HIV-infected patients display a remarkable risk for haematological neoplasms such as non-Hodgkin lymphomas, Hodgkin lymphoma and acute leukaemia. Several case series have confirmed the efficacy of the autologous stem cell transplantation for the treatment of non-Hodgkin lymphomas in the HIV setting. Nonetheless, there is a paucity of data for the role of the Allo-HSCT in HIV-infected individuals with haematological malignancies. Herein, we presented the successful long-term outcome of a HIV-infected patient who received reduced intensity conditioned, matched unrelated donor transplant with alemtuzumab as graft-versus-host disease prophylaxis for therapy-related acute myeloid leukaemia. We propose that Allo-HSCT in HIV patients is safe and that alemtuzumab-based conditioning could further work to eradicate HIV in those whose donor is not CCR5 homozygous.

Influence of the serum levels of immunoglobulins on clinical outcomes in medical intensive-care patients.

INTRODUCTION: Endogenous immunoglobulins (Igs) are of fundamental importance in the host defense after microbial infections. However, the therapeutic administration of intravenous IgG (IVIgG) has not yet been shown to improve clinical outcomes in patients suffering from sepsis, and in the case of IgM-containing preparations (IVIgGMA) the positive evidence is only weak. Recently published studies implicate that Ig levels on admission could have an impact on the patient's response to IVIg treatment and on outcomes of critically ill patients. METHODS: In this noninterventional study, the serum levels of IgG, IgM, and IgA were determined in 340 medical patients on ICU admission, and clinical outcomes were prospectively recorded (ICU mortality, need for renal replacement therapy (RRT), need for mechanical ventilation, substitution of coagulation factors, and amount of red cell transfusions). Patients were prospectively grouped according to their main reason for ICU admission (sepsis, respiratory failure, cardiovascular diseases, acute renal failure, postoperative condition, state after cardiopulmonal resuscitation, gastrointestinal diseases, and others). RESULTS AND DISCUSSION: There was no correlation between the Ig levels on admission and ICU mortality neither in the total cohort of medical ICU patients nor in any prespecified subgroup. However, in a logistic regression model that was adjusted for APACHE II score on admission, an increase in serum IgG was associated with a reduced need for mechanical ventilation in patients suffering from cardiovascular disease. On the other hand, in patients suffering from sepsis, an increased level of IgM was linked to an increased administration of coagulation factors. CONCLUSION: Our data do not support the hypothesis that serum levels of immunoglobulins are linked to mortality in medical ICU patients.

Lung protective ventilation and hospital survival of cardiac intensive care patients.

OBJECTIVE: To detect connections between parameters of ventilation and outcomes of cardiac intensive care patients. DESIGN AND SETTING: Noninterventional study. Between 05/11 and 05/12 all patients with acute heart failure and post cardiopulmonary resuscitation were registered. Lung protective ventilation was defined as peak inspiratory pressure (PIP) < 30 mmHg and tidal volume (Vt) < = 6 ml/kg. RESULTS: In total, 129 patients were included in the study, 68.2 % male, age 67.9 ± 13.4 years, weight 71.4 ± 37.2 kg, predictive body weight 66.9 ± 8.8 kg, mortality 47.3 %. Lung protective ventilated patients at day 1: 17.3 % with a significant difference between surviving and nonsurviving patients (24.1 % vs. 9.6 %; p < 0.05). Logistic regression models showed a strong connection between PIP and survival (odds ratio 1.13; p < 0.05). Vt showed no significant influence on survival. CONCLUSION: Our data recommends a strict observance of a low PIP for cardiac intensive care patients, whereas Vt seems to be of secondary importance.

Profiles of adaptation in two similar viruses.

The related bacteriophages phiX174 and G4 were adapted to the inhibitory temperature of 44 degrees and monitored for nucleotide changes throughout the genome. Phage were evolved by serial transfer at low multiplicity of infection on rapidly dividing bacteria to select genotypes with the fastest rates of reproduction. Both phage showed overall greater fitness effects per substitution during the early stages of adaptation. The fitness of phiX174 improved from -0.7 to 5.6 doublings of phage concentration per generation. Five missense mutations were observed. The earliest two mutations accounted for 85% of the ultimate fitness gain. In contrast, G4 required adaptation to the intermediate temperature of 41.5 degrees before it could be maintained at 44 degrees. Its fitness at 44 degrees increased from -2.7 to 3.2, nearly the same net gain as in phiX174, but with three times the opportunity for adaptation. Seventeen mutations were observed in G4: 14 missense, 2 silent, and 1 intergenic. The first 3 missense substitutions accounted for over half the ultimate fitness increase. Although the expected pattern of periodic selective sweeps was the most common one for both phage, some mutations were lost after becoming frequent, and long-term polymorphism was observed. This study provides the greatest detail yet in combining fitness profiles with the underlying pattern of genetic changes, and the results support recent theories on the range of fitness effects of substitutions fixed during adaptation.

Respiratory virus infections in adult T cell-depleted transplant recipients: the role of cellular immunity.

BACKGROUND: Little is known about the role of cellular immunity in respiratory virus infections after bone marrow transplantation. METHODS: Forty allograft recipients T-cell depleted with Campath antibodies were evaluated for respiratory virus infections in an active surveillance program with early initiation of antiviral therapy. RESULTS: Eighteen episodes of respiratory virus infection were detected in nine patients (22%) at a median of 95 days, with lower respiratory involvement in 44%. Fourteen episodes were treated with antiviral therapy for 7 to 46 days, with 11% mortality. Respiratory virus infections were more common in patients receiving Campath 100 mg in vivo, but delayed CD4+ recovery was the most significant risk factor. CONCLUSIONS: Respiratory virus infections are common and often recurrent in patients with severe CD4+ T lymphopenia. However, the mortality was low, which may have been due to early institution of antiviral treatment or reduced inflammatory damage to the lungs due to severe lymphopenia.

Pre-emptive oral ribavirin therapy of paramyxovirus infections after haematopoietic stem cell transplantation: a pilot study.

Infections with the paramyxoviruses, respiratory syncytial virus (RSV) and parainfluenza virus (PIV) can result in serious morbidity and mortality after haemopoietic stem cell transplant (HSCT). Once pneumonia develops, the outcome of these infections is often poor despite anti-viral therapy. Aerosolised ribavirin has been evaluated as pre-emptive therapy for post-transplant RSV infections with some success. Due to the financial and logistic burden involved with the use of aerosolised ribavirin, we explored the efficacy and toxicity of oral ribavirin for pre-emptive therapy of post-transplant RSV and PIV infections in a dose escalating schedule (15-60 mg/kg/day). Five episodes each of RSV and PIV were treated in seven patients. Five patients were receiving treatment for GVHD and two acquired the infection in the pre-engraftment period. All the episodes of RSV infection improved with oral ribavirin with dose escalation to 30-45 mg/kg in three of them. On the other hand, only two of the five PIV infections improved with oral ribavirin. Of the three non-responders, two infections were acquired in the pre-engraftment period with one death from PIV pneumonia. Reversible anaemia was the only side-effect noted in patients treated for over 2 weeks. Thus, the use of oral ribavirin was well tolerated in the post-transplant period with no untoward toxicities. There was a trend towards better response in RSV infections, which needs to be further explored in controlled studies.

A randomised study comparing peripheral blood progenitor mobilisation using intermediate-dose cyclophosphamide plus lenograstim with lenograstim alone.

We conducted a prospective randomised study to compare the efficiency of out-patient progenitor cell mobilisation using either intermediate-dose cyclophosphamide (2 g/m(2)) and lenograstim at 5 micrograms/kg (Cyclo-G-CSF group, n=39) or lenograstim alone at 10 micrograms/kg (G-CSF group, n=40). The end points were to compare the impact of the two regimens on mobilisation efficiency, morbidity, time spent in hospital, the number of apheresis procedures required and engraftment kinetics. Successful mobilisation was achieved in 28/40 (70%) in the G-CSF group vs 22/39 (56.4%) for Cyclo-G-CSF (P=0.21). The median number of CD34+ cells mobilised was 2.3 x 10(6)/kg and 2.2 x 10(6)/kg for G-CSF and cyclo-G-CSF arms following a median of two apheresis procedures. Nausea and vomiting and total time spent in the hospital during mobilisation were significantly greater after Cyclo-G-CSF (P<0.05). Rapid neutrophil and platelet engraftment was achieved in all transplanted patients in both groups. In conclusion, G-CSF at 10 micrograms/kg was as efficient at mobilising progenitor cells as a combination of cyclophosphamide and G-CSF with reduced hospitalisation and side effects and prompt engraftment. When aggressive in-patient cytoreductive regimens are not required to both control disease and generate progenitor cells, the use of G-CSF alone appears preferable to combination with intermediate-dose cyclophosphamide.

Optimal and central-place foraging theory applied to a desert harvester ant, Pogonomyrmex californicus.

Certain predictions of optimal- and central place-foraging theory were tested on the desert harvester ant, Pogonomyrmex californicus. Colonies were offered three different sizes of oat seed and found to maximize net energy intake (ei) over time (t i ) by harvesting the seed sizes with the highest e i /t i rank. Two aspects of t i were measured that were assumed constant in previous studies. The handling components of t i (time required to manipulate the seed and travel time back to the colony with the food) were measured and found to be positively correlated with seed size. The manipulation success rate (the percentage of handled seeds successfully picked up) decreased with increased seed size. These results point out how important it is to measure all parameters of e i /t i rather than to assume constancy with both prey type and foraging distance. The relative abundance of less preferred food types was important in determining the proportion of preferred types in the diet. The food supply of eight colonies was manipulated experimentally over a 25-day period. Four "deprived" colonies were constrained within aluminum enclosures to prevented foraging. The remaining four "satiated" colonies were given food ad libitum. The niche breadths of the treated colonies were then compared to controls, but found not to differ significantly. Seed baits were offered at three distances from the colony to test whether selectivity increased with disance. Contrary to theoretical predictions, all colonies harcested about the same proportion of each seed size at each distance.

Randomised controlled trial comparing oral and intravenous paracetamol (acetaminophen) plasma levels when given as preoperative analgesia.

Gastric absorption of oral paracetamol (acetaminophen) may be unreliable perioperatively in the starved and stressed patient. We compared plasma concentrations of parenteral paracetamol given preoperatively and oral paracetamol when given as premedication. Patients scheduled for elective ear; nose and throat surgery or orthopaedic surgery were randomised to receive either oral or intravenous paracetamol as preoperative medication. The oral dose was given 30 minutes before induction of anaesthesia and the intravenous dose given pre-induction. All patients were given a standardised anaesthetic by the same specialist anaesthetist who took blood for paracetamol concentrations 30 minutes after the first dose and then at 30 minute intervals for 240 minutes. Therapeutic concentrations of paracetamol were reached in 96% of patients who had received the drug parenterally, and 67% of patients who had received it orally. Maximum median plasma concentrations were 19 mg.l(-1) (interquartile range 15 to 23 mg.l(-1)) and 13 mg.l(-1) (interquartile range 0 to 18 mg.l(-1)) for the intravenous and oral group respectively. The difference between intravenous and oral groups was less marked after 150 minutes but the intravenous preparation gave higher plasma concentrations throughout the study period. It can be concluded that paracetamol gives more reliable therapeutic plasma concentrations when given intravenously.

Endothelial NO-synthase intron 4 polymorphism is associated with disturbed in vivo nitric oxide production in individuals prone to type 2 diabetes.

Insulin resistance, as well as vascular disease, both share a relevant genetic background taking the influence of a positive family history of these disorders. On the other hand, insulin resistance is associated with a proatherosclerotic disturbance in nitric oxide dependent vasodilation, probably contributing to the link between these two disorders. We examined the association between nitric oxide dependent vasodilation (measured with high resolution ultrasound at 13 MHz) and three relevant NO-synthase (eNOS)-polymorphisms in 200 insulin resistant subjects participating in the Tuebinger Lifestyle Intervention Program (TULIP). This study revealed that carriers of the eNOS intron 4 polymorphism (aa 2.16%; ab 24.2%; bb 73.2%) show significantly worse endothelial, and thereby eNOS dependent vasodilation (p=0.03, multivariate ANOVA), as compared to wildtype carriers. The 5' UTR T-786C and the G894 T polymorphism did not show any influence on eNOS-activity. In subjects at increased risk to develop type 2 diabetes, the eNOS intron 4 polymorphism is independently associated with endothelial function as indicated by disturbed endothelial NO production. Due to the high prevalence and the relatively strong effect, this polymorphism might help to identify subjects at increased risk for atherosclerosis associated with overweight and insulin resistance.

Midazolam in conjunction with local anaesthesia is superior to Entonox in providing pain relief during bone marrow aspirate and trephine biopsy.

AIM: To compare intravenous titrated midazolam 5-10 mg and inhaled Entonox in addition to local anaesthesia in order to identify which agent provides optimum pain relief. METHODS: Randomised, controlled trial. 49 patients were recruited, of which 46 were evaluable. 24 and 22 patients were recruited into the Entonox and midazolam arms, respectively. Patient experiences as well as staff observations were recorded with questionnaires after recovery from the procedure and 24 hours later. RESULTS: 45% and 59% of the patients in the midazolam arm could recollect the procedure after 15 minutes and 24 hours, respectively, compared to 96% and 88% who received Entonox. Midazolam provided a more comfortable experience (p<0.01) and improved pain relief (p = 0.01) compared to Entonox immediately after the procedure; this further improved when recalled 24 hours later. Nausea, dizziness and hallucinations were observed with both treatments, but dizziness was significantly more frequent with Entonox (p = 0.048). Clinically relevant respiratory depression (O(2) saturation <90%) occurred in 19% of patients in the midazolam arm; sedation was reversed with flumazenil. CONCLUSION: Midazolam in conjunction with local anaesthesia provides rapid and reversible sedation as well as effective pain relief during bone marrow biopsy, and is superior to Entonox; however, care must be taken to monitor respiratory function.

Testing alternative mechanisms of evolutionary divergence in an African rain forest passerine bird.

Abstract Models of speciation in African rain forests have stressed either the role of isolation or ecological gradients. Here we contrast patterns of morphological and genetic divergence in parapatric and allopatric populations of the Little Greenbul, Andropadus virens, within different and similar habitats. We sampled 263 individuals from 18 sites and four different habitat types in Upper and Lower Guinea. We show that despite relatively high rates of gene flow among populations, A. virens has undergone significant morphological divergence across the savanna-forest ecotone and mountain-forest boundaries. These data support a central component of the divergence-with-gene-flow model of speciation by suggesting that despite large amounts of gene flow, selection is sufficiently intense to cause morphological divergence. Despite evidence of isolation based on neutral genetic markers, we find little evidence of morphological divergence in fitness-related traits between hypothesized refugial areas. Although genetic evidence suggests populations in Upper and Lower Guinea have been isolated for over 2 million years, morphological divergence appears to be driven more by habitat differences than geographic isolation and suggests that selection in parapatry may be more important than geographic isolation in causing adaptive divergence in morphology.

Glacial vicariance and historical biogeography of rock ptarmigan (Lagopus mutus) in the Bering region.

In this paper, we address alternative hypotheses for the evolution of subspecies of rock ptarmigan (Lagopus mutus) endemic to the Aleutian Archipelago. To do this we examined patterns of genetic differentiation among populations of rock ptarmigan in the Aleutian Islands and parts of both Alaska and Siberia. Variation in mitochondrial control region sequences of 105 rock ptarmigan from 10 subspecies within the Bering region revealed three major phylogenetic lineages, two of which are endemic to the Aleutian Islands. Accordingly, haplotype and nucleotide diversities of rock ptarmigan within the archipelago are much higher than within mainland Alaska or Siberia. For Aleutian rock ptarmigan, analyses of molecular variance indicated significant genetic structuring and low estimates of gene flow among populations, despite small interisland distances within the archipelago. However, isolation by distance did not describe the pattern of gene flow or differentiation at this scale. Our estimates of divergence times of lineages suggest that Aleutian rock ptarmigan became isolated prior to the most recent Pleistocene glaciation event (late Wisconsin Stade) and that current patterns of genetic variation reflect the postglacial redistribution of divergent lineages and subsequent limited gene flow. In addition, genetic divergence among lineages was concordant with the distribution of plumage types among subspecies. The patterns of genetic variation described here for rock ptarmigan provide evidence for the role of glacial vicariance in contributing to genetic diversity within this and other Bering region species.

Regional anaesthesia for circumcision. Subcutaneous ring block of the penis and subpubic penile block compared.

In this prospective study techniques for the subcutaneous ring block of the penis and subpubic block of the penis for analgesia after circumcision were compared. Forty-five boys having circumcision as day-case patients were allocated randomly to have either a subcutaneous ring block or a subpubic penile block. The blocks were inserted after induction of anaesthesia but before surgery. Pain scores at 15, 30, 45 and 60 min post-operatively were recorded. Side effects and analgesic requirements in hospital were recorded post-operatively. Analgesia (morphine, paracetamol or diclofenac) was given depending on the pain score. One patient was withdrawn from the study. Four of the 24 boys who had subpubic penile blocks and nine of the 16 boys who had subcutaneous ring blocks were given morphine for post-operative pain (P = 0.015). The surgeons complained about oedematous tissues in three patients, all of whom had had subcutaneous ring blocks. The subpubic penile block provided significantly better analgesia than the subcutaneous ring block of the penis.

A TEST OF THE GLACIAL REFUGIUM HYPOTHESIS USING PATTERNS OF MITOCHONDRIAL AND NUCLEAR DNA SEQUENCE VARIATION IN ROCK PTARMIGAN (LAGOPUS MUTUS).

The glacial refugium hypothesis (GRH) proposes that glaciers promoted differentiation and generation of intraspecific diversity by isolating populations in ice-free refugia. We tested three predictions of this hypothesis for the evolutionary divergence of rock ptarmigan (Lagopus mutus) during the Wisconsin glaciation of the late Pleistocene. To do this, we examined subspecies distributions, population genetic structure, and phylogenetic relationships in 26 populations across North America and the Bering Sea region. First, we analyzed sequence variation in the mitochondrial control region, in a nuclear intron (Gapdh), and in an internal transcribed spacer (ITS1). Control region sequences of 154 rock ptarmigan revealed strong population and phylogeographic structure. Variation in intron sequences of 114 rock ptarmigan also revealed significant population structure compatible with results for the control region. Rock ptarmigan were invariant for ITS1. Second, we show that five known Nearctic refugia and an Icelandic refugium are concordant with the current distribution of morphologically distinct subspecies; five of these six refugia are geographically concordant with the distribution of closely related control region haplotypes. Third, our estimates of the time since phylogenetic lineages diverged predated the last glacial maximum for all but two lineages. In addition, all lines of evidence suggest that two unknown refugia in the Bering Sea region supported rock ptarmigan during the Wisconsin glaciation. Overall, our results are most consistent with the hypothesis that isolated populations of rock ptarmigan diverged in multiple refugia during the Wisconsin and that geographic variation reflects patterns of recolonization of the Nearctic after the ice receded. The GRH may therefore offer the most plausible explanation for similar biogeographic patterns in a variety of Nearctic vertebrates.

Plasma bupivacaine concentrations associated with continuous extradural infusions in babies.

The maximum recommended dose for extradural infusions of bupivacaine in children older than 1 month is 0.5 mg kg-1 h-1 but there are few specific reports of the associated blood concentrations during infusions in babies. Toxic symptoms can occur in children at plasma concentrations of bupivacaine as low as 2 micrograms ml-1. We attempted to measure venous plasma concentrations of total and free bupivacaine in babies aged 3-12 months during extradural infusions given at a rate commonly used in our hospital. We studied eight babies (mean age 33 weeks; mean weight 7.8 kg). After a mean initial dose of 1.2 mg kg-1 (range 1.1-1.3 mg kg-1), bupivacaine was infused at a mean rate of 0.38 (0.36-0.39) mg kg-1 h-1 for a mean of 31 (4-44) h. Blood was obtained at 4, 8, 16, 24, 32 and 40 h after starting the infusion and plasma separated by centrifugation. Total plasma bupivacaine concentration was measured using high pressure liquid chromatography (HPLC). Plasma concentrations of total bupivacaine were mostly less than 2 micrograms ml-1. One baby had a concentration of 2.02 micrograms ml-1 at 32 h and showed clear evidence of accumulation of bupivacaine. Babies can accumulate bupivacaine and achieve plasma concentrations above the threshold for toxic side effects, despite infusion rates below the currently accepted maximum. The samples size in our study was small but we believe an extradural infusion rate of 0.375 mg kg-1 h-1 is probably an absolute maximum for babies younger than 12 months.