Peptide-Based Cancer Vaccine Delivery via the STINGΔTM-cGAMP Complex

With the advent of bioinformatic tools in efficiently predicting neo-antigens, peptide vaccines have gained tremendous attention in cancer immunotherapy. However, the delivery of peptide vaccines remains a major challenge, primarily due to ineffective transport to lymph nodes and low immunogenicity. Here, a strategy for peptide vaccine delivery is reported by first fusing the peptide to the cytosolic domain of the stimulator of interferon genes protein (STINGΔTM), then complexing the peptide-STINGΔTM protein with STING agonist 2'3' cyclic guanosine monophosphate-adenosine monophosphate (cGAMP). The process results in the formation of self-assembled cGAMP-peptide-STINGΔTM tetramers, which enables efficient lymphatic trafficking of the peptide. Moreover, the cGAMP-STINGΔTM complex acts not only as a protein carrier for the peptide, but also as a potent adjuvant capable of triggering STING signaling independent of endogenous STING protein-an especially important attribute considering that certain cancer cells epigenetically silence their endogenous STING expression. With model antigen SIINFEKL, it is demonstrated that the platform elicits effective STING signaling in vitro, draining lymph node targeting in vivo, effective T cell priming in vivo as well as antitumoral immune response in a mouse colon carcinoma model, providing a versatile solution to the challenges faced in peptide vaccine delivery.

Self-assembled cGAMP-STINGΔTM signaling complex as a bioinspired platform for cGAMP delivery

The stimulator of interferon (IFN) genes (STING) pathway constitutes a highly important part of immune responses against various cancers and infections. Consequently, administration of STING agonists such as cyclic GMP-AMP (cGAMP) has been identified as a promising approach to target these diseases. In cancer cells, STING signaling is frequently impaired by epigenetic silencing of STING; hence, conventional delivery of only its agonist cGAMP may be insufficient to trigger STING signaling. In this work, while expression of STING lacking the transmembrane (TM) domain is known to be unresponsive to STING agonists and is dominant negative when coexpressed with the full-length STING inside cells, we observed that the recombinant TM-deficient STING protein complexed with cGAMP could effectively trigger STING signaling when delivered in vitro and in vivo, including in STING-deficient cell lines. Thus, this bioinspired method using TM-deficient STING may present a universally applicable platform for cGAMP delivery.

Perioperative metabolic acidosis: The Bradford Anaesthetic Department Acidosis Study

Metabolic acidosis is considered deleterious but is common in post-surgical patients admitted to intensive care unit. We evaluated the prevalence and time course of metabolic acidosis in elective major surgery, and generated hypotheses about causes, by hourly arterial blood sampling in 92 patients. Metabolic acidosis began before incision and most had occurred by the next hour. Seventy-eight per cent of patients had a significant metabolic acidosis post-operatively. Two overlapping phases were observed. The early phase started before incision, characterised by a rising chloride and falling anion gap, unrelated to saline use. The late phase was partly associated with lactate, related to surgery type, and early fluids appeared protective. There was a trend towards longer intensive care unit (+1.3 days) and hospital (+3.2 days) stay with metabolic acidosis. This is the first large study of the evolution of this common finding, demonstrating a pre-incision component. The early phase appears unavoidable or unpredictable, but the late phase might be modified by early fluid administration. It remains unclear whether acidosis of this type should be avoided.

Randomized clinical trial of fluid and salt restriction compared with a controlled liberal regimen in elective gastrointestinal surgery

Background

Excessive intravenous fluid prescription may play a causal role in postoperative complications following major gastrointestinal resectional surgery. The aim of this study was to investigate whether fluid and salt restriction would decrease postoperative complications compared with a more modern controlled liberal regimen.

Methods

In this observer-blinded single-site randomized clinical trial consecutive patients undergoing major gastrointestinal resectional surgery were randomized to receive either a liberal control fluid regimen or a restricted fluid and salt regimen. The primary outcome was postoperative complications of grade II and above (moderate to severe).

Results

Some 240 patients (194 colorectal resections and 46 oesophagogastric resections) were enrolled in the study; 121 patients were randomized to the restricted regimen and 119 to the control (liberal) regimen. During surgery the control group received a median (interquartile range) fluid volume of 2033 (1576–2500) ml and sodium input of 282 (213–339) mmol, compared with 1000 (690–1500) ml and 142 (93–218) mmol respectively in the restricted group. There was no significant difference in major complication rate between groups (38·0 and 39·0 per cent respectively). Median (range) hospital stay was 8 (3–101) days in the controls and 8 (range 3–76) days among those who received restricted fluids. There were four in-hospital deaths in the control group and two in the restricted group. Substantial differences in weight change, serum sodium, osmolality and urine : serum osmolality ratio were observed between the groups.

Conclusion

There were no significant differences in major complication rates, length of stay and in-hospital deaths when fluid restriction was used compared with a more liberal regimen. Registration number: ISRCTN39295230 (http://www.controlled-trials.com).

Assessing the performance of the Whisperflow continuous positive airway pressure generator: a bench study

BACKGROUND

There are few data describing the performance of the Whisperflow continuous positive airway pressure (CPAP) generator.

METHODS

(i) (a) A static test of 11 Whisperflow devices examining maximum flow generation with no load and with 2.5, 5, 7.5, 10, 15, and 20 cm H2O valve loading, at varying Fi(O2). (b) CPAP valves (Accu-peep(R), Vital Signs, Totowa, NJ, USA) were tested by measuring mean upstream pressure at varying flows in five valves (2.5, 5, 7.5, 10, 15, and 20 cm H2O). (ii) We measured the mean and minimum inspiratory mask pressure generated by a representative Whisperflow device in a model of spontaneous respiration. Measurements were made with combinations of Fi(O2), ventilatory frequency, tidal volume, and valve loading similar to those encountered in clinical practice.

RESULTS

(i) (a) The flow generated by the Whisperflow valves decreases with increasing valve load and increasing Fi(O2) (from 140 to 20 litre min(-1)). (b) The CPAP valves maintain the required pressure within acceptable limits against varying flow. (ii) At all permutations, the mean inspiratory mask pressure was significantly lower than that required. At high inspiratory flow rates, the minimum inspiratory pressure approached atmospheric pressure.

CONCLUSIONS

The Whisperflow may not perform as expected. Clinicians should be cautious when using this device, particularly with high Fi(O2) and CPAP valve load. The flow setting should be set at maximum. Failure of CPAP therapy may be due to failure of the generator. Further in vivo data are required.

Heritability of serum TSH, free T4 and free T3 concentrations: a study of a large UK twin cohort

OBJECTIVE

Thyroid hormone action influences many metabolic and synthetic processes, but the degree of regulation attributed to genes and environmental factors affecting normal variation remains controversial.

DESIGN

We investigated the magnitude of the genetic and environmental determination of serum concentrations of free (f) T3, fT4, TSH and the fT4 x TSH product and their variation, in a large cohort of twin pairs. Female dizygous and monozygous twins (849 and 213 pairs, respectively) from the TwinsUK registry (mean age 45.5, range 18-80 years) were studied.

RESULTS

Comparison of thyroid parameters within various groups showed no differences between smoking categories, and higher serum TSH and lower fT3 in subjects with positive thyroid antibodies. Using structural equation modelling, we estimated the heritable contribution to serum thyroid parameters (with 95% confidence intervals) to be 65% (58%-71%) for TSH, 65% (58%-71%) for the fT4 x TSH product, 39% (20%-55%) for fT4 and 23% (3%-41%) for fT3.

CONCLUSIONS

We conclude that genetic regulation is a particularly important determinant of TSH and the fT4 x TSH product, and is a less important determinant of fT4 and fT3 concentrations in Caucasian women. These data from a large well-characterized cohort suggest that while there is a strong heritable contribution to serum TSH, variation in fT4 and fT3 concentrations may be less explained by genetic factors and more driven by environmental effects than previously thought.

Integrated approaches to academic anaesthesia - the Cambridge experience

There is mounting concern about the pressures experienced by University Departments of Anaesthesia, which, if lost, could threaten undergraduate peri-operative medicine teaching, development of critical appraisal skills among anaesthetists, and the future of coherent research programs. We have addressed these problems by establishing a foundation course in scientific methods and research techniques (the Cambridge SMART Course), complemented by competitive, fully funded, 12-month academic trainee attachments. Research conducted during academic attachments has been published and used to underpin substantive grant applications allowing work towards higher degrees. Following the attachment, a flexible scheme ensures safe reintroduction to clinical training. Research at consultant level is facilitated by encouraging applications for Clinician Scientist Fellowships, and by ensuring that the University Department champions, legitimises and validates the allocation of research time within the new consultant contract. We believe that these are important steps in safeguarding research and teaching in anaesthesia, critical care and peri-operative medicine.

Use of prone ventilation in neurogenic pulmonary oedema

We present a case of neurogenic pulmonary oedema (NPO) due to subarachnoid haemorrhage that resulted in hypoxia refractory to conventional mechanical ventilation. Prone positioning was employed, resulting in rapid and sustained improvement in oxygenation. We discuss the pathogenesis of NPO and the mechanism of action of prone ventilation. Prone ventilation may be of value in the management of NPO, both in treating life-threatening hypoxia and in optimizing neurological recovery. Further data are required on its effect on intracranial pressure after subarachnoid haemorrhage.

Amniotic fluid embolism: a case report and review

A 41-year old primigravida underwent caesarean section because of foetal distress following prostin induction of labour. Intraoperative coagulopathy, haemorrhage and hypotension necessitated a hysterectomy. Subsequently, she developed respiratory and renal failure, requiring mechanical ventilation and haemodialysis. She made a full recovery. The likely diagnosis was amniotic fluid embolism (AFE), a rare complication of pregnancy with a variable presentation, ranging from cardiac arrest and death through to mild degrees of organ system dysfunction with or without coagulopathy. The differential diagnosis includes pre-eclamptic toxaemia/pregnancy-induced hypertension, anaphylaxis and pulmonary embolism. There is no diagnostic test for AFE; the finding of foetal elements in the maternal circulation is non-specific. Historically, AFE was thought to induce cardiovascular collapse by mechanical obstruction of the pulmonary circulation. It is now thought that a combination of left ventricular dysfunction and acute lung injury occur, with activation of several of the clotting factors. An immunological basis for these effects is postulated. There is no specific therapy and treatment is supportive. The mortality of the condition remains high.

Urine colour as an index of hydration in critically ill patients

In order to test the hypothesis that urine colour can be used as an index of hydration in critically ill patients, we selected 40 intensive care and high-dependency patients and correlated urine colour (scored on an eight-point scale) with various indices of hydration: urine:plasma sodium, osmolality and urea ratios, urine output and central venous pressure. In addition, we compared the colour-chart score with scores made by intensive care nurses (without the benefit of a colour chart) in order to test subjective assessment of urine colour. There were weak but statistically significant correlations between urine colour and urine output (Spearman's r = - 0.555) and between urine colour and urine:plasma sodium ratio (Spearman's r = - 0.459). Subjective assessment of urine colour appeared to be reliable. Thus, although urine colour does vary with hydration in the critically ill, assessment of urine colour adds little to the overall assessment of hydration in this group of patients.

Fracture of the cricoid cartilage after Sellick's manoeuvre

We report a case of fracture of the cricoid cartilage associated with cricoid pressure during rapid sequence tracheal intubation in a patient with status asthmaticus. This patient had a history of laryngeal trauma 48 yr previously. Fracture of the cricoid cartilage has not been reported previously after cricoid pressure.

A "cysteineless" GLUT1 glucose transporter has normal function when expressed in Xenopus oocytes

To test the role of cysteines in the function of GLUT1 glucose transporter, site-directed mutagenesis was used to replace all six GLUT1 cysteines with serine residues. When the individual and combined Cys-->Ser mutants were expressed in Xenopus laevis oocytes, zero-trans uptake of 3-O-methylglucose was comparable to that seen in native GLUT1. The "cysteineless" construct also retained the kinetic features of GLUT1, including an asymmetric transport mechanism and similar substrate and inhibitor affinities. Whereas GLUT1 transport was inhibited by sulfhydryl reagents, that of the "cysteineless" construct was not. These results show that cysteines are not required for GLUT1 function or oligomer formation. The "cysteineless" construct may therefore serve as a template for reintroducing cysteines back into GLUT1 at sites useful for testing transporter structure and function.

Spinal anesthesia using a 1:1 mixture of bupivacaine and tetracaine for peripheral vascular surgery

STUDY OBJECTIVE

To present our preliminary experience using three doses of an equimilligram mixture of 1% tetracaine and 0.75% bupivacaine in 8.25% dextrose for spinal anesthesia in patients undergoing peripheral vascular surgery.

SETTING

Operating and recovery rooms at a university medical center.

PATIENTS

60 patients who received femoral popliteal or femoral distal bypass with spinal anesthesia.

INTERVENTIONS

All patients had intravenous cannulae inserted and received lactated Ringer's solution. There were no bolus infusions of fluid preanesthesia. Fluid administration occurred at a rate of 8 to 15 ml/kg/hr, with additional fluid and inotropic drugs administered to treat hypotension. Oxygen (O2) was delivered by nasal cannula, and peripheral O2 saturation was monitored. Blood pressure (BP) was monitored every 1 to 5 minutes using an automatic BP device, and ECG was displayed continually.

MEASUREMENTS AND MAIN RESULTS

Initially, 8 patients received a dose of 15 mg of each drug combined with 0.2 mg of epinephrine injected in a 20-degree head-up tilt. Because the duration of anesthesia was prolonged, subsequent patients received 12 mg of each drug mixed with 0.2 mg of epinephrine for cases in which an extended duration was predicted and 10 mg of each drug plus epinephrine for proximal first-time bypasses. With mixtures of 15 mg, 12 mg, and 10 mg of each drug plus epinephrine, a mean duration of approximately 300 minutes of surgically acceptable anesthesia was obtained. As the dose was decreased, the SD increased. There was a 0% failure rate for the spinal anesthetics at doses of 15 mg and 12 mg of each drug and a 19.5% failure rate at a dose of 10 mg of each drug. In each case, the rapid onset of a sensory blockade regressed in a standard and predictable fashion. The decline in BP and the use of inotropic and vasoconstrictive drugs were comparable to those in previously published reports of spinal anesthetics using single drug techniques with smaller doses. In none of the patients were there any untoward cerebrovascular or neurologic events, nor were there any clinically evident episodes of coronary insufficiency.

CONCLUSION

Spinal anesthesia using bupivacaine and tetracaine mixed in a single-injection technique can last 5 hours at the T12 level without added untoward effects when compared with lower-dose spinal anesthetics.

Effect of posture on lung and regional chest wall mechanics

BACKGROUND

Little is known about the extent to which changes in postures in clinical situations affect respiratory mechanics, even in humans with healthy respiratory systems. This study tested the hypothesis that posture has only small effects on overall respiratory system mechanics in healthy subjects, despite changes in parts of the respiratory system in some postures.

METHODS

Measurements were made of airway flow, airway and esophageal pressures, and rib cage and abdominal volume displacements (with inductance plethysmography) of awake, healthy subjects, relaxed at functional residual capacity, during external forcing at 0.2 Hz with a tidal volume of 8-10 ml/kg. From these measurements, discrete Fourier transform was used to calculate elastances (E) and resistances (R) of the total respiratory system, lungs, total chest wall, and compartments of the chest wall (rib cage, diaphragm-abdomen, and belly wall). Measurements were made while the subjects were in nine different postures: in six of these, the torso was straight; in three, the torso was bent or twisted.

RESULTS

Although changes in mechanics of parts of the respiratory system were evident in certain postures, overall respiratory mechanics were not greatly affected by posture. Changing from sitting to supine decreased E and R of the diaphragm-abdomen about 50% (P < .05), but total chest wall E and R changed only slightly. Lung E increased 24% (P < .05), but total respiratory E did not change (P < .05). Lung and total respiratory R increased 40-50% (P < .05) with this same change in posture. As long as the torso was straight, however, changes in orientation of 30 degrees from the horizontal or a shift to lateral posture resulted in only minor changes in the variables measured. Postures in which the torso was twisted or bent increased E of the total chest wall 20-30% compared to supine (P < .05), due to increases in E of one or more compartments. Respiratory system E also increased, at most 14%. Although lung R decreased 30-45% (P < .05) in these postures compared to supine with a straight torso, chest wall and total respiratory R generally were unchanged.

CONCLUSIONS

Changes in respiratory system mechanics over a wide range of postures that may be encountered clinically are relatively small in healthy awake subjects due to adaptability of total chest wall mechanical behavior.

Effects of cardiac oscillations on acinar gas mixing during pulmonary edema

We used a previously reported technique (Mackenzie et al., J. Appl. Physiol. 68: 2013-2018, 1990) to measure the effects of severe pulmonary edema on acinar cardiogenic gas mixing in anesthetized dogs. We also tested how increases in lung volume affected gas mixing in healthy lungs and during pulmonary edema. Cardiogenic gas mixing was evaluated by measurement of the rate of washout of xenon133 injected into an occluded pulmonary artery during apnea. The rate constant of xenon133 washout was 0.40 min-1 (+/- 0.06 SE) in the healthy lung at functional residual capacity. It decreased (P < 0.05) to 0.08 min-1 (+/- 0.03) when lung volume was raised 500 ml. Pulmonary edema was induced by injection of oleic acid (0.06 mg.kg-1) into the right atrium over a 4-min period; clinical signs of severe pulmonary edema were present after 90 min. The rate constant for xenon133 washout (0.07 +/- 0.03 min-1) was less than in the healthy lung (P < 0.05), and was not changed after lung volume was increased (P > 0.05). We conclude that, in the presence of severe pulmonary edema: (1) acinar resistance is increased and/or magnitude of cardiogenic oscillations is decreased; and (2) salutary effects of increased lung volume are not due to enhancement of cardiogenic gas mixing.

Effect of tidal volume on respiratory system elastance and resistance during anesthesia and paralysis

Recent studies have shown that the mechanical properties of the respiratory system at normal breathing frequency in awake humans depend on tidal volume. Few measurements of respiratory system properties during anesthesia have accounted for this dependence. From measurements of airway pressure, flow and esophageal pressure, we calculated elastances and resistances of the total respiratory system (Ers and Rrs), chest wall (Ecw and Rcw), and lungs (El and Rl) in supine human volunteers during quasisinusoidal volume forcing in a normal range of breathing (250 to 800 ml) at normal breathing frequency (0.2 Hz). Measurements were made (1) with subjects awake and voluntarily relaxed; (2) after isoflurane-N2O anesthesia (end-tidal isoflurane concentration 0.3 to 0.5%); and (3) after complete muscle paralysis with vecuronium. In all conditions, Ers, Ecw, El, Rrs, and Rcw decreased at 800 ml tidal volume compared with 250 ml; Rl showed a similar decrease in awake measurements only. Compared with awake measurements, each elastance tended to increase after anesthesia, but only the increase in Ers was significant. Compared with anesthesia, there was no effect of paralysis on any measurement. We conclude that (1) tidal volume dependence of respiratory system properties in the normal range of breathing occurs in the absence of muscle activity; (2) anesthesia increases Ers and (3) respiratory muscle activity appears to be inhibited by isoflurane-N2O anesthesia at end-tidal isoflurane concentration of 0.3 to 0.5% during normocapnia.

A simple improved method for the measurement of cyclosporin by liquid-liquid extraction of whole blood and isocratic HPLC

The current HPLC methods of cyclosporin measurement have been reviewed and all aspects assessed. A simple isocratic C-18 reverse phase HPLC method with improved efficiency is described for the routine measurement of cyclosporin in whole blood. An alkaline ether extraction is followed by an acid wash, solvent evaporation and two hexane washes of the reconstituted extract. The turn-round time for a single sample is 1 h. Daily batches of up to 40 patient samples can be easily measured with this method. The results are compared with those from the Sandoz radioimmunoassay (RIA) method.

Energetics of triosephosphate isomerase: the appearance of solvent tritium in substrate glyceraldehyde 3-phosphate and in product

When the isomerization of D-glyceraldehyde 3-phosphate to dihydroxyacetone phosphate is catalyzed by triosephosphate isomerase in tritiated water, both the substrate and the product become labeled. The specific radioactivity of the product is only about 13% that of the solvent, which shows that the protonation of the enediol intermediate at C-1 (to form the enzyme-bound product dihydroxyacetone phosphate) is a kinetically significant step, and that the rate of loss of dihydroxyacetone phosphate from the enzyme is relatively fast. The specific radioactivity of the remaining substrate after partial reaction rises as the reaction proceeds and shows that the reaction intermediate that exchanges protons with the medium returns to D-glyceraldehyde 3-phosphate about one-third as often as it is converted to dihydroxyacetone phosphate. These results confirm the qualitative description of the relative heights of the energy barriers in this reaction and further contribute to the quantitative analysis of the free-energy profile.