MTSS1, a novel target of DNA methyltransferase 3B, functions as a tumor suppressor in hepatocellular carcinoma

DNA methyltransferase 3B (DNMT3B) mediates gene silencing via epigenetic mechanisms during hepatocellular carcinoma (HCC) progression. We aimed to identify novel targets of DNMT3B and their potential regulatory mechanisms in HCC. Metastasis suppressor 1 (MTSS1) was one of the DNMT3B targets and selected for further study. DNMT3B overexpression was detected in 81.25% of clinical HCC specimens and was negatively associated with MTSS1 in HCC cells and clinical samples. The underlying mechanism by which DNMT3B silences MTSS1 was studied using a combination of methylation-specific polymerase chain reaction (PCR) and bisulfite genome sequencing, chromatin immunoprecipitation-PCR and luciferase reporter assays. We found that the MTSS1 promoter region was sparsely methylated, and the methylation inhibitors failed to abolish DNMT3B-mediated MTSS1 silencing. DNMT3B protein bound directly to the 5'-flanking region (-865/-645) of the MTSS1 gene to inhibit its transcription. The functional role of MTSS1 was investigated using in vitro and in vivo tumorigenicity assays. As a result, MTSS1 exerted tumor suppressor effects and arrested cells in the G2/M phase, but not the G1/S phase of the cell cycle when it was depleted or overexpressed in HCC cells. Taken together, MTSS1, a novel target of DNMT3B, is repressed by DNMT3B via a DNA methylation-independent mechanism. MTSS1 was further characterized as a novel tumor suppressor gene in HCC. These findings highlight how DNMT3B regulates MTSS1, and such data may be useful for the development of new treatment options for HCC.

Fibrinolysis during anaphylaxis, and its spontaneous resolution, as demonstrated by thromboelastography

A large and ever-growing number of agents used in anaesthesia can precipitate acute anaphylactic reactions after their administration. Anaphylaxis is a sudden onset (or rapidly progressive), severe systemic allergic reaction, affecting multiple organ systems. The number of people who suffer severe systemic allergic reactions is increasing. The incidence is about 1-3 reactions per 10 000 population per annum, although anaphylaxis is not always recognized; therefore, certain UK studies may underestimate the incidence. In this case report, we present an episode of acute fibrinolysis associated with life-threatening anaphylaxis, demonstrated by thromboelastography (TEG) and resolving spontaneously. This is despite an added fibrinolytic insult in the form of cardiopulmonary bypass. There is a paucity of literature detailing fibrinolysis occurring during anaphylaxis, most likely due to the limited availability of TEG in the acute setting and the primary clinical focus of delivering life-saving interventions.

Magnitude and time course of impaired primary haemostasis after stopping chronic low and medium dose aspirin in healthy volunteers

Aspirin ingestion within the previous 7-10 days is often considered a relative contraindication to performing invasive procedures. However, aspirin is an important component of many patients' treatment and withholding therapy for this time may be dangerous. To measure both the magnitude of the impairment in primary haemostasis induced by aspirin and how much recovery of platelet function occurs within 48 h of stopping aspirin, we studied serial changes in bleeding time (BT) in a randomized, double-blind, placebo-controlled study. Fifty-two healthy volunteers had BT performed before and at 2, 9, 24 and 48 h after a 7-day course of either aspirin 75 mg, 300 mg or placebo. The main outcome recorded was BT at each time. Nearly 25% of subjects had extended BT to more than 10 min, but no BT were greater than 10 min, 48 h after stopping aspirin. There was a small but statistically significant (P < 0.01) difference between the 48-h and baseline BT in both aspirin groups (49 and 64 s in the 75 mg and 300 mg groups, respectively). There was no difference in the magnitude or time course of effect between low and medium dose aspirin (P = 0.392 and P = 0.797, respectively). We conclude that despite considerable inter-individual variability in the magnitude of aspirin effect on primary haemostasis, the time course of effect was consistent. In healthy volunteers, the defect in primary haemostasis had largely disappeared 48 h after the last dose.

Demand on primary health care after day surgery

We have audited the frequency and nature of demands made on general practitioners, and the rate of surgical and anaesthetic complications within the first 7 days after day surgery. Semi-structured questionnaires were posted to the general practitioners of patients who attended the hospital's day care ward for a surgical procedure over a 6 month period. In all, 1798 questionnaires were sent, of which 1533 (85.3%) were returned. A total of 247 (16.7%) patients consulted their general practitioners after day surgery, the principal reason being pain (113 patients). Patients who underwent incisional intermediate surgery had the highest rate (31.5%) of general practitioner consultations. This audit has quantified the workload which day surgery places upon general practitioners. It also demonstrates the importance of categorising the various procedures performed on a day case basis when examining patient outcome. Patients who underwent non-incisional minor surgery consulted their general practitioner less often than those who underwent incisional minor surgery, who in turn consulted their practitioner less often than those who underwent incisional intermediate surgery. It seems likely that an increase in workload for general practitioners is inevitable if more complex procedures are performed on a day case basis.

Single-dose i.v. granisetron in the prevention of postoperative nausea and vomiting

In this randomized, double-blind, parallel group, placebo-controlled, dose-ranging study, we have compared three doses (0.1 mg, 1.0 mg and 3.0 mg) of the 5-HT3 receptor antagonist, granisetron (Kytril), as prophylactic therapy for the prevention of postoperative nausea and vomiting. The aims were to determine the optimal dose of granisetron and to evaluate its safety profile. We studied 527 adult patients, undergoing elective open abdominal surgery or vaginal hysterectomy during general anaesthesia. Antiemetic prophylaxis with a single dose of granisetron 1.0 mg or 3.0 mg resulted in a significant reduction (P < 0.001 compared with placebo) in the numbers of patients experiencing postoperative vomiting, or nausea, or who achieved total control during the postoperative periods 0-6 h and 0-24 h. The two higher doses of granisetron (1.0 mg and 3.0 mg) provided effective prophylaxis against vomiting, with 78% and 77% of patients, respectively, being free from vomiting in the first 6 h after surgery, and 63% and 62% in the first 24 h. This compares with 50% and 34% at 0-6 h and 0-24 h, respectively, in the placebo group. Granisetron was well tolerated and the optimum dose was 1.0 mg.

Inhalational anesthetics in the intensive care unit

Intravenous (IV) sedation is convenient, and many different IV agents are used. They are not always effective, however, and there are disadvantages to every intravenous agent used in clinical practice. Inhalational anesthetics are a useful alternative and have specific advantages. Further technologic refinements in the technique of inhalational sedation of mechanically ventilated patients may lead to wider clinical applications.

Selective decontamination of the digestive tract reduces gram-negative pulmonary colonization but not systemic endotoxemia in patients undergoing elective liver transplantation

OBJECTIVE

To examine the effect of selective antibiotic decontamination of the digestive tract in patients undergoing elective orthotopic liver transplantation.

DESIGN

Prospective, randomized, concurrent allocation to either selective decontamination or standard antibiotic prophylaxis.

SETTING

Operating theater and intensive care unit at a tertiary referral, university teaching hospital.

PATIENTS

Fifty-nine adult patients were recruited into the study and underwent liver transplantation.

INTERVENTIONS

Thirty-two patients were randomized to standard treatment (control group) and 27 patients were randomized to receive selective decontamination. After early deaths and exclusions, 31 controls and 21 decontamination patients were available for analysis.

MEASUREMENTS AND MAIN RESULTS

Portal and systemic endotoxemia, colonization and infection rates, severity of illness (organ system failures, Acute Physiology and Chronic Health Evaluation II score, Therapeutic Intervention Scoring System score), antibiotic costs, and hospital survival rates were measured. Selective decontamination significantly reduced pulmonary infections and enteric, aerobic, and Gram-negative bacillary colonization without facilitating the emergence of resistant organisms, but selective decontamination had no effect on endotoxemia or the development of organ system failures. The financial costs of the selective decontamination regimen outweighed the advantages gained from an associated reduction in antibiotic usage.

CONCLUSION

The failure of selective decontamination to enhance survival rates in many studies of the regimen in critically ill patients may, in part, be related to the inability of selective decontamination to abolish endotoxemia.

Plasma catecholamine concentration during sedation in ventilated patients requiring intensive therapy

The effects of isoflurane and midazolam sedation on the catecholamine responses of ventilated patients were studied over a 24-h period. Sixty ventilated patients admitted to our intensive therapy unit were allocated randomly to receive either isoflurane or midazolam sedation. Arterial blood samples for plasma catecholamine concentrations were taken at baseline, 6 h after starting sedation and at the end of the study period. Patients sedated with isoflurane showed a progressive reduction in both adrenaline and noradrenaline concentrations during the period of sedation which reached statistical significance for adrenaline at 6 h (p less than 0.02) and at the end of the study (p less than 0.001). Patients sedated with midazolam showed no significant changes of adrenaline or noradrenaline concentrations. Overall, a more satisfactory degree of sedation was achieved with isoflurane.

Rapid monitoring of fluoride (F-) levels in blood plasma

Evidence exists that plasma F- concentrations of 1.0 part/10(6) are nephrotoxic and that much lower levels disturb enamel mineralization. Ingested F(-)-containing gels, tablets and toothpastes all raise plasma F- levels significantly, as does prolonged exposure to fluorine-containing anaesthetic gases. There is, therefore, a continuing need to determine the total F- burden accruing in any given individual from multiple sources, as well as the average plasma F- burden which could be carried without risk to kidneys or teeth. To meet this need by facilitating fast and accurate monitoring of plasma F- levels, a new method has been devised and tested. A specific ion F- electrode in conjunction with a combination pH electrode forms a differential cell very sensitive to low concentrations of F-. When compared with the performance of a single F- electrode plus Ag/AgCl reference electrode, the differential cell is not only as consistent and accurate but also has a much shorter response time (2 vs. 20 min) and requires a much smaller sample volume (0.05 vs. 1.0 ml). In healthy subjects the mean plasma F- level was 0.044 (+/- 0.001) parts/10(6); in three patients undergoing prolonged (24 h) sedation with the fluorine-containing gas isoflurane, mean plasma F- rose to 0.275 (+/- 0.025) parts/10(6). No binding of F- to plasma components occurred at the operating pH (1.2) of the differential cell and plasma could be stored for at least 40 days at low temperature (4 degrees C) without alteration to measured F- values.

Isoflurane sedation for patients undergoing mechanical ventilation: metabolism to inorganic fluoride and renal effects

The metabolism and renal effects of isoflurane sedation were studied for 24 h in patients undergoing mechanical ventilation. Forty-six patients admitted to our intensive therapy unit were allocated randomly to receive either 0.1-0.6% isoflurane or midazolam 0.01-0.2 mg kg-1 h-1 for sedation. In 26 patients sedated with isoflurane, plasma inorganic fluoride increased from a mean concentration of 4.03 mumol litre-1 to 13.57 mumol litre-1 12 h after stopping sedation. Plasma inorganic fluoride concentrations in 20 patients sedated with midazolam were unchanged from baseline values (mean 5.32 mumol litre-1). Serum electrolyte, urea and creatinine concentrations, and urine output rates during and after sedation in patients who received isoflurane were similar to those who received midazolam. We conclude that, following isoflurane sedation for up to 24 h, metabolism to inorganic fluoride is insufficient to cause clinical renal dysfunction.

Isoflurane compared with midazolam for sedation in the intensive care unit

OBJECTIVE

To compare isoflurane with midazolam for sedation of ventilated patients.

DESIGN

Randomised control study. Setting--Intensive care unit in university teaching hospital.

PATIENTS

Sixty patients aged 18-76 who required mechanical ventilation.

INTERVENTIONS

Sedation with either 0.1-0.6% isoflurane in an air-oxygen mixture (30 patients) or a continuous intravenous infusion of midazolam 0.01-0.20 mg/kg/h (30 patients). Sedation was assessed initially and hourly thereafter on a six point scale. Incremental intravenous doses of morphine 0.05 mg/kg were given for analgesia as required. The trial sedative was stopped when the patient was judged ready for weaning from ventilatory support or at 24 hours (whichever was earlier).

END POINT

Achievement of a predetermined level of sedation for as much of the time as possible.

MAIN RESULTS

Isoflurane produced satisfactory sedation for a greater proportion of time (86%) than midazolam (64%), and patients sedated with isoflurane recovered more rapidly from sedation.

CONCLUSION

Isoflurane is a promising alternative technique for sedation of ventilated patients in the intensive care unit.

Resistance to airflow in anaesthetic breathing systems

We have examined, under reproducible conditions, the resistance to airflow of complete anaesthetic breathing systems (Magill, Coaxial Lack, Parallel Lack and Bain systems) and components of these systems. All systems had resistances within the recommended ranges at all flows likely to be experienced in normal clinical practice. The Magill system had the lowest resistance under all conditions. It is concluded that comparisons should be made only between complete breathing systems.

Recovery of neuromuscular function and postoperative morbidity following blockade by atracurium, alcuronium and vecuronium

Recovery of neuromuscular function and postoperative morbidity were studied in 51 fit female patients who had nonemergency gynaecological laparoscopy as inpatients. They were allocated randomly to one of three groups to receive either atracurium 0.31 mg/kg, alcuronium 0.25 mg/kg, or vecuronium 0.06 mg/kg as part of an otherwise standard anaesthetic technique. There were neither differences in intubation conditions nor in the occurrence of postoperative diplopia whichever muscle relaxant was used. Deficits in grip strength and expiratory force were seen at one hour after reversal with atropine 1.2 mg and neostigmine 2.5 mg in all patients, deficits which persisted for 3 hours in those who received alcuronium. The recovery of inspiratory force was slower and less complete at up to 3 hours in those who received alcuronium and there was a high incidence of minor postoperative morbidity at up to 24 hours in each of the three groups. The only statistical difference in symptomatic morbidity was an increase in muscle weakness in those who received alcuronium compared with atracurium at 3 hours after laparoscopy. Only 25%, 20% and 31% of the patients who received atracurium, alcuronium and vecuronium respectively said that they would have liked to be day stay patients.

Wavelength-discrimination behavior in the grasshopper Phlaeoba

The grasshopper Phlaeoba sp. has ocular filters that are arranged in discrete retinal bands. These filters modify the spectra of some of its photoreceptors, all of which are apparently filled with the same resident photopigment. The receptor response differences produced by the ocular filters provide a potential basis for wavelength discrimination. Behavioral tests of wavelength discrimination in Phlaeoba were therefore run; they confirmed earlier qualitative findings that indicated that Phlaeoba can discriminate between visual stimuli on the basis of wavelength cues and quantitatively showed that the behavioral preference is proportional to the receptor spectral difference. Tests of animals with indistinct retinal bands indicated that wavelength discrimination was reduced in this variant but was still quantitatively related to the receptor spectra. These data suggest that the filter-mediated color vision hypothesis applies in the case of Phlaeoba.

Filter-mediated color vision with one visual pigment

The compound eye of the grasshopper Phlaeoba has alternating bands that appear clear or brown. Electroretinograms recorded from the individual bands have different action spectra: The spectrum of the clear band peaks at 525 nanometers and that of the brown band at 545 nanometers. Spectrally selective whole-eye adaptation with light of eight long of short wavelength yields identical action spectra. This evidence suggests that this eye has only one visual pigment, whose spectrum is altered in the brown bands by a screening pigment. In behavioral tests of spontaneous choices between stimuli that appear green to the normal human and those that appear red, the green stimuli are preferred even when the relative intensity is varied by 0.9 log units around the equal-brightness level (determined by the electroretinogram). When some red light is mixed with the green light, the preference for the mixture is less than for the green light alone, even though the mixture is more intense. True color vision therefore seems to exist. Painting the bands shows that behavioral color vision requires the presence of both types. These data suggest that Phlaeoba has true color vision mediated by one visual pigment and suitable optical filters.

Temporal summation in the receptor potential of the Limulus lateral eye: comparison between retinula and eccentric cells

Temporal summation and reciprocity (Bloch's law) were studied in the receptor potential recorded from the retinula and eccentric cells of the excised Limulus lateral eye. Taking the peak of the receptor potential as the response measure yielded critical durations that ranged between 65 and 170 msec, depending on the cell type and the criterion level of response. At high but not at low response levels, the critical duration is significantly longer in eccentric cells than in retinula cells. Deviations from Bloch's law were found; these deviations were largest at intermediate response levels.

Two linear rules relate the latencies of visual responses to their critical durations

The latency of a neural response sets a limit on its critical duration since stimulation delivered after a response has already occurred can no longer affect that response. However, this tautologic upper limit does not uniquely define the critical duration. Intracellular recordings from the lateral eye of Limulus yield two linear rules which empirically relate the critical duration of a neural response to its latency: When response magnitude (peak amplitude, spike frequency) is used to construct the temporal summation function, the critical duration is equal to the latency minus a constant. When response latency is used instead, the critical duration of the response latency is equal to the latency divided by a constant.

Changing response measures alters temporal summation in the receptor and spike potentials of the Limulus lateral eye

Temporal summation and reciprocity were studied in the retinula and eccentric cells of the excised Limulus lateral eye as a function of variation in response measure: Using the latency instead of the peak of the receptor potential as a response measure produced considerably shorter critical durations. Using the area under the receptor potential as a response measure produced no critical duration up to a stimulus duration of 640 msec; instead, supersummation occurred at long durations. Similar effects were observed in the optic nerve spikes, where the response measures were first spike latency and maximum spike number sampled in time windows that ranged from 40 to 640 msec. The critical durations clearly depended on the response measure used and, when a 640-msec window was used, no critical duration occurred; supersummation again occurred. Increasing the sampling period within which maximum spike number was measured increased the critical duration and changed the formal properties from those characteristic of the receptor potential's peak to those characteristic of the receptor potential's area. The implications of the more central portions of the nervous system using different summation times for different perceptual tasks are discussed; it is suggested that the choice of response measures is crucial in studies of temporal summation.

Illusory correlation of brightness enhancement and transients in the nervous system

Short light flashes can appear brighter than longer flashes. This brightness enhancement has often been attributed to neural transients occurring shortly after stimulus onset. This attribution assumes an equivalence between the totality of the response to a stimulus of a given duration and the instantaneous response at a given time after stimulus onset. Recordings from Limulus photoreceptors indicate that this attribution is an example of illusory correlation.