Prehospital tranexamic acid shortens the interval to administration by half in Major Trauma Networks: a service evaluation.

INTRODUCTION: Tranexamic acid (TXA) reduces bleeding and mortality. Recent trials have demonstrated improved survival with shorter intervals to TXA administration. The aims of this service evaluation were to assess the interval from injury to TXA administration and describe the characteristics of patients who received TXA pre-hospital and in-hospital. METHODS: We reviewed Trauma and Audit Research Network records and local trauma registries to identify patients of any age that received TXA at all London Major Trauma Centres and Queen's Medical Centre, Nottingham, during 2017. We used the 2016 NICE Guidelines (NG39) which state that TXA should be given within 3 hours of injury. RESULTS: We identified 1018 patients who received TXA, of whom 661 (65%) had sufficient data to assess the time from injury to TXA administration. The median interval was 74 min (IQR: 47-116). 92% of patients received TXA within 3 hours from injury, and 59% within 1 hour. Half of the patients (54%) received prehospital TXA. The median time to TXA administration when given prehospital was 51 min (IQR: 39-72), and 112 min (IQR: 84-160) if given in-hospital (p<0.001). In-hospital TXA patients had less haemodynamic derangement and lower base deficit on admission compared with patients given prehospital TXA. CONCLUSION: Prehospital administration of TXA is associated with a shorter interval from injury to drug delivery. Identifying a proportion of patients at risk of haemorrhage remains a challenge. However, further reinforcement is needed to empower pre-hospital clinicians to administer TXA to trauma patients without overt signs of shock.

Evaluation of variation in the phosphoinositide-3-kinase catalytic subunit alpha oncogene and breast cancer risk.

BACKGROUND: Somatic mutations in phosphoinositide-3-kinase catalytic subunit alpha (PIK3CA) are frequent in breast tumours and have been associated with oestrogen receptor (ER) expression, human epidermal growth factor receptor-2 overexpression, lymph node metastasis and poor survival. The goal of this study was to evaluate the association between inherited variation in this oncogene and risk of breast cancer. METHODS: A single-nucleotide polymorphism from the PIK3CA locus that was associated with breast cancer in a study of Caucasian breast cancer cases and controls from the Mayo Clinic (MCBCS) was genotyped in 5436 cases and 5280 controls from the Cancer Genetic Markers of Susceptibility (CGEMS) study and in 30 949 cases and 29 788 controls from the Breast Cancer Association Consortium (BCAC). RESULTS: Rs1607237 was significantly associated with a decreased risk of breast cancer in MCBCS, CGEMS and all studies of white Europeans combined (odds ratio (OR)=0.97, 95% confidence interval (CI) 0.95-0.99, P=4.6 × 10(-3)), but did not reach significance in the BCAC replication study alone (OR=0.98, 95% CI 0.96-1.01, P=0.139). CONCLUSION: Common germline variation in PIK3CA does not have a strong influence on the risk of breast cancer.

ATP-sensitive potassium channels mediate contraction-induced attenuation of sympathetic vasoconstriction in rat skeletal muscle.

Sympathetic vasoconstriction is sensitive to inhibition by metabolic events in contracting rat and human skeletal muscle, but the underlying cellular mechanisms are unknown. In rats, this inhibition involves mainly alpha2-adrenergic vasoconstriction, which relies heavily on Ca2+ influx through voltage-dependent Ca2+ channels. We therefore hypothesized that contraction-induced inhibition of sympathetic vasoconstriction is mediated by ATP-sensitive potassium (KATP) channels, a hyperpolarizing vasodilator mechanism that could be activated by some metabolic product(s) of skeletal muscle contraction. We tested this hypothesis in anesthetized rats by measuring femoral artery blood flow responses to lumbar sympathetic nerve stimulation or intraarterial hindlimb infusion of the specific alpha2-adrenergic agonist UK 14,304 during KATP channel activation with diazoxide in resting hindlimb and during KATP channel block with glibenclamide in contracting hindlimb. The major new findings are twofold. First, like muscle contraction, pharmacologic activation of KATP channels with diazoxide in resting hindlimb dose dependently attenuated the vasoconstrictor responses to either sympathetic nerve stimulation or intraarterial UK 14,304. Second, the large contraction-induced attenuation in sympathetic vasoconstriction elicited by nerve stimulation or UK 14,304 was partially reversed when the physiologic activation of KATP channels produced by muscle contraction was prevented with glibenclamide. We conclude that contraction-induced activation of KATP channels is a major mechanism underlying metabolic inhibition of sympathetic vasoconstriction in exercising skeletal muscle.

Differential sympathetic neural control of oxygenation in resting and exercising human skeletal muscle.

Metabolic products of skeletal muscle contraction activate metaboreceptor muscle afferents that reflexively increase sympathetic nerve activity (SNA) targeted to both resting and exercising skeletal muscle. To determine effects of the increased sympathetic vasoconstrictor drive on muscle oxygenation, we measured changes in tissue oxygen stores and mitochondrial cytochrome a,a3 redox state in rhythmically contracting human forearm muscles with near infrared spectroscopy while simultaneously measuring muscle SNA with microelectrodes. The major new finding is that the ability of reflex-sympathetic activation to decrease muscle oxygenation is abolished when the muscle is exercised at an intensity > 10% of maximal voluntary contraction (MVC). During high intensity handgrip, (45% MVC), contraction-induced decreases in muscle oxygenation remained stable despite progressive metaboreceptor-mediated reflex increases in SNA. During mild to moderate handgrips (20-33% MVC) that do not evoke reflex-sympathetic activation, experimentally induced increases in muscle SNA had no effect on oxygenation in exercising muscles but produced robust decreases in oxygenation in resting muscles. The latter decreases were evident even during maximal metabolic vasodilation accompanying reactive hyperemia. We conclude that in humans sympathetic neural control of skeletal muscle oxygenation is sensitive to modulation by metabolic events in the contracting muscles. These events are different from those involved in either metaboreceptor muscle afferent activation or reactive hyperemia.

Impaired modulation of sympathetic vasoconstriction in contracting skeletal muscle of rats with chronic myocardial infarctions: role of oxidative stress.

Skeletal muscle perfusion during exercise is impaired in heart failure, but the underlying mechanisms are poorly understood. One possibility is that sympathetic vasoconstriction is enhanced in exercising muscle in heart failure as a result of impaired counterregulatory mechanisms that normally act to attenuate vasoconstrictor responses. In healthy animals, sympathetic vasoconstriction in contracting skeletal muscle is attenuated by endogenously produced nitric oxide (NO). Because the NO pathway may be dysfunctional in heart failure, we hypothesized that reduced NO in contracting muscle would result in enhanced sympathetic vasoconstriction. In sham rats and rats with chronic myocardial infarctions (MIs) produced by coronary artery ligation, we measured arterial pressure and femoral artery blood flow responses to sympathetic nerve stimulation (1, 2.5, and 5 Hz) in resting and contracting hindlimb. In resting hindlimb, sympathetic stimulation decreased femoral vascular conductance similarly in sham and MI rats. In contracting hindlimb, these vasoconstrictor responses were attenuated to a greater extent in sham than in MI rats. NO synthase inhibition enhanced sympathetic vasoconstriction in contracting hindlimb of sham, but not MI, rats. Conversely, infusion of L-arginine or a superoxide scavenger, tempol or tiron, attenuated sympathetic vasoconstriction in contracting hindlimb of MI rats. NO synthase expression was similar, but malondialdehyde (a marker of free radical damage) was greater in skeletal muscle from MI than from sham rats. These data suggest that impaired metabolic modulation of sympathetic vasoconstriction in contracting skeletal muscle of MI rats is a consequence of superoxide-mediated disruption of the NO pathway.

Effect of dose, molecular size, affinity, and protein binding on tumor uptake of antibody or ligand: a biomathematical model.

A mathematical model has been developed to determine the best approach to improving tumor targeting with antibody. The amount of antibody in the tumor (tumor content) and the tumor:normal tissue antibody concentration ratio (uptake ratio) were calculated over 12 days from injection, using the computer program FACSIMILE to solve the stiff nonlinear differential equations describing the system. Results indicate that success requires an optimal combination of dose, size, and binding affinity of antibody. Increasing the dose to 100 times that presently used for scanning increased both the percentage of injected antibody in the tumor and the uptake ratio by up to 2 orders of magnitude to maximal values determined by affinity. This result could be achieved by coinjecting unlabeled antibody. Increasing affinity from Keq = 10(9) to 10(13)M-1 increased the uptake ratio from 5 to 100 for whole antibody and to 550 for a small ligand, at the calculated optimal dose, but had no effect at the current scanning dose. With decreasing molecular size at average affinity, the same maximum tumor content and uptake ratio were achieved but progressively earlier. At high affinity there was a substantial advantage for a small ligand compared with whole antibody in terms of uptake ratio (550 versus 100) and tumor:normal tissue integral dose ratio (330 versus 60). The uptake of a small ligand was not increased by binding to plasma protein but with increasing time the tumor content was higher than without protein binding.

Pilot study for the development of a new campylobacter selective medium at 37 degrees C using aztreonam.

AIMS: To overcome contamination and temperature inhibition by isolating campylobacter at 37 degrees C. METHODS: The beta lactam antibiotic aztreonam was included in a selective medium because of its inhibitory activity against Gram negative organisms but not against Campylobacter jejuni. Vancomycin and amphotericin were added to inhibit Gram positive bacteria and yeasts. RESULTS: The aztreonam amphotericin vancomycin (AAV) experimental campylobacter selective medium showed growth microaerobically at 37 degrees C of C jejuni, C coli, C lari, C hyointestinalis, C fetus subsp. fetus, and C jejuni subsp. doylei after 24 to 48 hours of incubation. Six campylobacter NCTC strains demonstrated a minimum inhibitory concentration (MIC) > or = 256 mg/litre for vancomycin and aztreonam, whereas C upsaliensis and two "campylobacter-like" strains now reclassified under genus helicobacter--H cinaedi and H fennelliae--had a MIC of 4 mg/litre for vancomycin and aztreonam. In the pilot study (150 samples), AAV medium (37 degrees C) had a higher sensitivity for isolating campylobacters: 14 were isolated on AAV compared with 10 on modified CDA (43 degrees C) over three days, and nine were isolated on AAV medium compared with five on modified CDA (43 degrees C) after 24 hours of incubation. Contamination rates remained low. CONCLUSION: The medium was devised in a pilot study performed between 1990 and 1993; however, this is the first report of AAV medium used as a selective medium capable of growing six campylobacters of pathogenic importance at 37 degrees C. Further studies are indicated.

Exercise-induced attenuation of alpha-adrenoceptor mediated vasoconstriction in humans: evidence from phase-contrast MRI.

OBJECTIVE: We recently provided evidence for contraction-induced attenuation of reflex sympathetic vasoconstriction in human skeletal muscle microcirculation. We now asked whether contraction-induced modulation of alpha-adrenoceptor mediated vasoconstriction in the human forearm (a) is evident in a large artery supplying the contracting skeletal muscle and (b) implicates a post-junctional site of action. METHODS AND RESULTS: To address these questions in humans, we used phase-contrast magnetic resonance imaging to measure blood flow velocity and cross-sectional area of the brachial artery during brachial-artery infusion of the alpha-adrenoceptor agonist norepinephrine (NE) (1.1 g/min for 5 min) at rest and during mild ipsilateral rhythmic handgrip (20% of maximum). At rest, brachial artery conductance decreased progressively during the entire 5 min period of infusion (baseline to first half to second half of infusion: 0.421 +/- 0.157 to 0.255 +/- 0.187 to 0.012 +/- 0.014 ml/min/mmHg, P < 0.05). When NE was superimposed on handgrip, conductance at first decreased sharply (1.205 +/- 0.127 to 0.330 +/- 0.097 ml/min/mmHg, P < 0.05). However, during the second half of the infusion, conductance did not decrease further but rather returned progressively toward baseline (0.476 +/- 0.199 ml/min/mmHg at the end of the exercise, P < 0.05 vs. NE alone). CONCLUSION: These data provide new evidence in humans that alpha-adrenoceptor mediated vasoconstriction is sensitive to modulation by skeletal muscle contraction. Such modulation is evident at the level of a large conduit artery and it involves a post-junctional mechanism of action.

Chemical sympathectomy alters the development of hypertension in miniature swine.

To determine if the neurotoxin 6-hydroxydopamine could be used to chemically sympathectomize neonatal miniature swine, eight newborn swine were treated with 6-hydroxydopamine beginning on the first day after birth and continuing at regular intervals for the next 6 months. Six littermates served as controls and received vehicle injections. A significant reduction in the pressor response to intravenous tyramine (95%) and in the tissue norepinephrine content of the kidneys, left ventricle, and gastrocnemius muscle (more than 93%) provided evidence for an effective long-term sympathectomy in the 6-hydroxydopamine-treated animals. In addition, the blood pressure response of these young, chemically sympathectomized swine to chronic deoxycorticosterone acetate treatment was evaluated. Mean arterial pressure before deoxycorticosterone was similar in the 6-hydroxydopamine-treated (116 +/- 2 mm Hg) and control (125 +/- 5 mm Hg) groups. One week after deoxycorticosterone, mean arterial pressure had risen significantly by 20-22 mm Hg in both groups. Blood pressure continued to increase in the control group, reaching a value of 163 +/- 6 mm Hg by the third week after treatment. In contrast, mean arterial pressure in the 6-hydroxydopamine group did not increase further during weeks 2 and 3 after deoxycorticosterone. In conclusion, chronic treatment of neonatal swine with 6-hydroxydopamine produced an animal model with an effective, general, peripheral sympathectomy. The significant attenuation of the hypertensive response in these sympathectomized animals lends further support to the hypothesis that an intact sympathetic nervous system is necessary for the full expression of deoxycorticosterone hypertension in miniature swine.

Renal denervation decreases blood pressure in DOCA-treated miniature swine with established hypertension.

The role of renal sympathetic nerve activity (RSNA) in the maintenance phase of essential hypertension has not yet been clearly defined. Renal function and mean arterial pressure (MAP) were studied in four Yucatan miniature swine (YMS) with established DOCA hypertension prior to and for 3 weeks after surgical renal denervation (RDX). During the first week post-RDX, MAP decreased from 141 /+- 6 to 121 +/- 3 mm Hg (P less than .05), while sodium balance increased from 0.32 +/- 0.05 to 0.95 +/- 0.14 mEq/kg/day (P less than .05). By 3 weeks post-RDX, MAP remained below normotensive levels while sodium balance returned to the pre-RDX value. There was no significant change in potassium or water balance after RDX. Thus, in DOCA-YMS the renal nerves are important in the maintenance of hypertension. The reduction in MAP with RDX in the absence of a natriuresis suggests a role for renal afferent nerve activity.

Sympathetic neural mechanisms of cyclosporine-induced hypertension.

The immunosuppressant drug cyclosporine A (CsA) has emerged as an important new cause of hypertension in both organ transplant recipients and patients with autoimmune diseases. Despite the clinical importance of this hypertension, the underlying mechanisms have been enigmatic. This article presents a conceptual framework for understanding the pathophysiologic basis of CsA-induced hypertension and focuses on the hypothesis that a common molecular mechanism is involved in mediating the immunosuppressive and the hypertensive effects of CsA. This mechanism involves the binding of CsA to a newly discovered class of cytoplasmic receptors (termed "immunophilins") not only in T lymphocytes but also in the kidney, vascular smooth muscle, and central nervous system, which are the main target tissues mediating CsA-induced hypertension. Binding of CsA to its receptor leads to inhibition of calcineurin, the Ca2+/calmodulin-dependent protein phosphatase. Evidence is reviewed to support the hypothesis that calcineurin inhibition plays a pivotal role in mediating both CsA-induced immunosuppression and hypertension, the latter being produced at least in part by sympathetic neural activation. The elucidation of novel CsA-sensitive cellular signaling pathways has lead to the search for the ideal immunosuppressant drug, one which retains CsA's immunosuppressive efficacy but without its toxicity.

Quality assessment in cervical cytology: a pilot study.

A pilot study of an external quality assessment scheme was run between February 1985 and September 1986 to (i) assess the feasibility of running one from a district general hospital; (ii) to estimate the time required to organise and run it with a computer; (iii) to provide sound statistical results with which future schemes could be compared. Seven laboratories participated, and the 20 smears selected from each laboratory were circulated in three rounds in batches of seven, seven, and six according to a prearranged order. Results analysed using the kappa statistic showed moderate levels of interlaboratory agreement, with complete agreement emerging only on a small proportion of cases.

Observer variation in the histological grading of rectal carcinoma.

The variation between two observers in grading 100 biopsies and the corresponding main specimens of rectal carcinomas has been examined. Using kappa statistics, which take account of chance agreement, we found a highly significant level of agreement. As expected, higher levels were obtained for intraobserver agreement. However, disagreements between observers were in many instances "haphazard" and there were differences in bias between them. Fifty paired biopsies and main tumours were graded by five observers and the results analysed for bias and by kappa statistics for overall and conditional agreement. These methods revealed significant overall agreement but the levels for some observer pairs did not differ significantly from chance. Examination for observer bias indicated differing standards of grading, and haphazard disagreements reached high levels for some observer pairs. The intraobserver agreement between the grade of the biopsy and the corresponding main tumour varied from 56-69% but only 52% of the poorly differentiated tumours were diagnosed as such in the preoperative biopsy by the "specialist" observer. The poor predictive value was not improved by taking multiple biopsies. We conclude that the grade of a rectal carcinoma cannot be accurately assessed on a preoperative biopsy and that this has serious implications for the management of low rectal cancers. Furthermore the wide discrepancies in diagnostic standards between some pathologists mean that studies on the treatment and prognosis of rectal cancer which utilise histological grade for comparison purposes must be viewed with considerable skepticism.

Oxidation of lactate and acetate in rat skeletal muscle: analysis by 13C-nuclear magnetic resonance spectroscopy.

The balance between carbohydrate and fatty acid utilization in skeletal muscle previously has been studied in vivo by using a variety of methods such as arteriovenous concentration differences and radioactive isotope tracer techniques. However, these methodologies provide only indirect estimates of substrate oxidation. We used 13C-nuclear magnetic resonance (NMR) spectroscopy and non-steady-state isotopomer analysis to directly quantify the relative oxidation of two competing exogenous substrates in rat skeletal muscles. We infused [1,2-13C]acetate and [3-13C]lactate intravenously in anesthetized rats during the final 30 min of 35 (n = 10) or 95 (n = 10) min of intense, unilateral, rhythmic hindlimb contractions. 13C-NMR spectroscopy and isotopomer analysis were performed on extracts of gastrocnemius and soleus muscles from both the contracting and contralateral resting hindlimbs. We found that 1) [13C]lactate and [13C]acetate were taken up and oxidized by both resting and contracting skeletal muscles; and 2) high-intensity muscle contractions altered the pattern of substrate utilization such that the relative oxidation of acetate decreased while that of lactate remained unchanged or increased. Based on these findings, we propose that 13C-NMR spectroscopy in combination with isotopomer analysis can be used to study the general dynamics of substrate competition between carbohydrates and fats in rat skeletal muscle.

Differential modulation of cortical synaptic activity by calcineurin (phosphatase 2B) versus phosphatases 1 and 2A.

Reversible protein phosphorylation is thought to play an important regulatory role in synaptic neurotransmission. We recently have shown in cultured rat cortical neurons that inhibition of the Ca2+/calmodulin-dependent phosphatase calcineurin (phosphatase 2B) increases the frequency, but not the amplitude, of postsynaptic glutamatergic currents, implicating a presynaptic site of action for calcineurin. The specific presynaptic phosphoprotein substrates for calcineurin are unknown, however, calcineurin has been implicated in the control of the Ca2+-independent phosphatases, phosphatases 1 and 2A. To determine whether calcineurin's effects on synaptic transmission are direct or are mediated by changes in phosphatase 1 and/or 2A activities, we used whole-cell voltage clamp to record spontaneous and miniature excitatory postsynaptic currents in the presence of calyculin A (1 microM in bath solution), a membrane permeant inhibitor of phosphatases 1 and 2A which has no effect on calcineurin. Calyculin increased postsynaptic current amplitude without changing current frequency. In these same neurons, subsequent inhibition of calcineurin with cyclosporine A or FK506 had no further effect on current amplitude, but increased current frequency. The increased current amplitude seen with calyculin involved a postsynaptic mechanism, since the effect was reproduced by microcystin (10 microM in pipette solution), which is a membrane-impermeant inhibitor of phosphatases 1 and 2A. Thus, in rat cortical neurons, glutamatergic neurotransmission appears to be frequency-modulated through a presynaptic mechanism by calcineurin, and amplitude-modulated through a postsynaptic mechanism by phosphatases 1 and 2A.

Practical considerations in the exploitation of passive tumor targeting.

Specific targeting of radioisotopes or toxic drugs to tumors for cancer detection and treatment is an enticing but elusive goal. It has proved difficult to achieve adequate concentration ratios between tumor and normal tissues to improve on standard diagnostic and therapeutic methods.

Effect of dose, molecular size, and binding affinity on uptake of antibodies.

The huge molecular radius of immunoglobulins would seem to be a major drawback for the targeting of solid tumors, because of slow extravasation into tumor interstitium and along plasma half-life. The permeability of normal continuous capillary endothelia to intravascular solutes of different molecular sizes has been determined in animals, mainly for macromolecules, and different sources give data consistent with the graph in Fig. 1 (1-3). The position of whole antibodies (IgG, mol wt 150 kDa and effective molecular radius 5.5 nm) is well to the right of albumen (66 kDa and 3.5 nm), and they are therefore very slowly extravasated in normal tissues. A F(ab')2 fragment (100 kDa, 5.06 nm) should not extravasate much faster than the intact molecule on this basis and a monomeric Fab' fragment (50 kDa, 3.48 nm) still has quite a high molecular radius (4), so a much smaller molecule would be necessary to equilibrate very quickly with extracellular fluid (ECF). Fig. 1. Relationship between molecular radius and permeability/surface area product for intact capillaries.

Observer variation in the assessment of adequacy and neoplasia in cervical cytology.

OBJECTIVE: To measure variation in reporting within and between cytotechnologists in a routine cytology laboratory and to assess if attending training courses and discussing many cases alter agreement levels. STUDY DESIGN: The study involved nine cytotechnologists each screening 100 cervical smears and recording the results. The same 100 smears were given a different identity number and the process repeated about six months later. Between the two occasions, two participants attended a training course, and two others discussed many other cases with the aim of reaching agreement on diagnostic criteria. RESULTS: The number of smears judged by the participants on either occasion as adequate varied between 87 and 100, and as adequate and negative, between 36 and 65. Percentage intraobserver agreement on the first round diagnosis of a negative smear varied between 88.5 and 100, and of an abnormal smear, between 58.5 and 91.2. CONCLUSION: Attending the same training course and in-depth discussion of other cervical smears appear to have had the effect of increasing some aspects of interobserver agreement between the two pairs of individuals involved.

Developmental sites and relative abundance of immature stages of the stable fly (Diptera: Muscidae) in beef cattle feedlot pens in eastern Nebraska.

A 3-yr study was done to determine where and at what relative frequency stable fly, Stomoxys calcitrans (L.), immatures develop in beef cattle feedlot pens and the relationship of stable fly immature versus adult sample densities. Pens within feedlots were divided into five areas (the feed apron, back fence, side fences, mound, and the general lot); from each area, three core samples were randomly taken weekly. In 1986 and 1987, the feed apron yielded the most immature stable flies (62.5%). The mound and side fences yielded a significant percentage of flies (24.6 and 8.4%, respectively). There was a strong correlation (overall r = 0.86) between numbers of immatures and numbers of adults 2 wk later. In 1988, a drought year, low numbers of immatures were collected, and only one correlation between numbers of immatures and adults was significant. In all 3 yr, sample densities of stable fly immatures peaked and began to decline by midseason. Waste management along the feed apron and mound areas could significantly reduce stable fly populations. Sampling immatures from these areas could permit prediction of adult numbers.

Overwintering of the stable fly (Diptera: Muscidae) in southeastern Nebraska.

Adult stable flies, Stomoxys calcitrans (L.), were monitored during three winters at two, four, and 13 locations with Alsynite fiberglass traps and by examination of the interiors of buildings. No stable flies were found inside buildings during the winter. Adult stable flies were consistently caught on Alsynite traps at one location during two winters and at two other locations during one winter. Distribution and physiological age of these flies indicate that they emerged from pupae that had developed at or near the location where they were captured. Potential breeding sites were examined. A few third instars were found in silage in midwinter, but silage should not be considered a major source for overwintering stable flies.