The effects of acute hyponatraemia on bone turnover in patients with subarachnoid haemorrhage: A preliminary report.

CONTEXT: Animal data and cross-sectional human studies have established that chronic hyponatraemia predisposes to osteoporosis; the effects of acute hyponatraemia on bone turnover have not been determined. Our objective was to test the hypothesis that acute hyponatraemia leads to dynamic effects on bone turnover. DESIGN: A prospective observational pilot study. METHODS: Bone turnover markers [C-terminal crosslinking telopeptide of type 1 collagen (CTX-1), N-propeptide of type 1 collagen (P1NP) and osteocalcin] were measured prospectively over one week in 22 eunatraemic patients with subarachnoid haemorrhage. Patients treated with glucocorticoids were excluded. RESULTS: Eight patients developed acute hyponatraemia, median nadir plasma sodium concentration 131 mmol/L (IQR 128-132), and 14 remained eunatraemic, nadir plasma sodium concentration 136 mmol/L (IQR 133-137). Significant main effects of hyponatraemia were found for P1NP (p = .02) and P1NP:CTX-1 ratio (p = .02), both fell in patients with acute hyponatraemia, with significant interaction between hyponatraemia and time from baseline for P1NP (p = .02). Significant main effects of time from baseline (p < .001) but not hyponatraemia (p = .07) were found for osteocalcin. For CTX-1, significant main effects of time from baseline (p = .001) but not hyponatraemia (p = .65) were found. There was a positive correlation between change in P1NP:CTX-1 ratio and nadir plasma sodium concentration, r = +.43, p = .04. Median serum cortisol (measured on days 1, 3 and 7) was higher in the hyponatraemia group than in those who remained eunatraemic, 545 nmol/L (IQR 373-778) versus 444 nmol/L (IQR 379-542) p = .03. CONCLUSION: These data suggest that acute mild hyponatraemia is associated with a reduction in bone formation activity.

[Effects of cortical bone trajectory screw in adjacent-segment disease after posterior lumbar interbody fusion].

Objective: To investigate the effect of the cortical bone trajectory (CBT) screw fixation combined with midline lumbar fusion (MIDLF) for adjacent spondylopathy after posterior lumbar interbody fusion. Methods: A retrospective analysis was conducted in 16 patients, including 9 males and 7 females, with a mean age of (68±6) years, who underwent revision surgery for adjacent spondylopathy after posterior lumbar fusion surgery using CBT combined with MIDLF technology in Sir Run Run Shaw Hospital, Zhejiang University from May 2013 to August 2019. The reasons for revision were radiculalgia in 4 cases, intermittent claudication in 10 cases and protrusive dissociate in 2 cases. Eleven cases had 1 segment fused in the first operation, while the other 5 cases received fusion in 2 segments. The average interval time between the first operation and the revision operation was (7.5±2.0) years. For the levels underwent revision, 1 case was L2/3, 6 cases were L3/4, 7 cases were L4/5 and 2 cases were L5/S1. Before the operation, all the patients took X-rays scans of the thoracic and lumbar spine. CT and MRI scans were also performed. The operation time, intraoperative bleeding, surgical complications, visual analog scale (VAS) of low back and leg pain before the operation and at each follow-up were all recorded. Oswestry disability index (ODI) questionnaire was used to evaluate the functional improvement of patients after the operation. Results: All operations were completed successfully. The operation time was 120-240 (170±30) mins, intraoperative bleeding was 100-280 (220±45) ml. One case had a slight split in the isthmus, and the screw was inserted smoothly after adjusting the insertion point. In one case, the cerebrospinal fluid leaked during the operation and was successfully treated with conservative methods including no pillow supine treatment and strengthened anti-infection. The average follow-up time was of (19.5±1.3) months. The VAS of low back pain was 2.9±1.7 before the operation and it was 1.8±0.5 at the last follow-up, and the difference was statistically significant (P<0.01). The VAS of leg pain was 5.9±1.5 before the operation and it was 1.5±0.4 at the last the follow-up (P<0.01). The ODI score was 34.5±3.2 preoperatively and it decreased to 12.6±4.2 at the last follow-up, the difference was statistically significant (P<0.01). Conclusion: CBT technique combined with MIDLF for the adjacent-segment disease after posterior lumbar interbody fusion is minimally invasive and convenient, with good clinical effects. This technique can be used as an option for the revision of adjacent spondylopathy.

Magnetic topology changes induced by lower hybrid waves and their profound effect on edge-localized modes in the EAST tokamak.

Strong mitigation of edge-localized modes has been observed on Experimental Advanced Superconducting Tokamak, when lower hybrid waves (LHWs) are applied to H-mode plasmas with ion cyclotron resonant heating. This has been demonstrated to be due to the formation of helical current filaments flowing along field lines in the scrape-off layer induced by LHW. This leads to the splitting of the outer divertor strike points during LHWs similar to previous observations with resonant magnetic perturbations. The change in the magnetic topology has been qualitatively modeled by considering helical current filaments in a field-line-tracing code.

GSK3ß Impairs KIF1A Transport in a Cellular Model of Alzheimer's Disease but Does Not Regulate Motor Motility at S402.

Impairment of axonal transport is an early pathologic event that precedes neurotoxicity in Alzheimer's disease (AD). Soluble amyloid-ß oligomers (AßOs), a causative agent of AD, activate intracellular signaling cascades that trigger phosphorylation of many target proteins, including tau, resulting in microtubule destabilization and transport impairment. Here, we investigated how KIF1A, a kinesin-3 family motor protein required for the transport of neurotrophic factors, is impaired in mouse hippocampal neurons treated with AßOs. By live cell imaging, we observed that AßOs inhibit transport of KIF1A-GFP similarly in wild-type and tau knock-out neurons, indicating that tau is not required for this effect. Pharmacological inhibition of glycogen synthase kinase 3ß (GSK3ß), a kinase overactivated in AD, prevented the transport defects. By mass spectrometry on KIF1A immunoprecipitated from transgenic AD mouse brain, we detected phosphorylation at S402, which conforms to a highly conserved GSK3ß consensus site. We confirmed that this site is phosphorylated by GSK3ß in vitro Finally, we tested whether a phosphomimic of S402 could modulate KIF1A motility in control and AßO-treated mouse neurons and in a Golgi dispersion assay devoid of endogenous KIF1A. In both systems, transport driven by mutant motors was similar to that of WT motors. In conclusion, GSK3ß impairs KIF1A transport but does not regulate motor motility at S402. Further studies are required to determine the specific phosphorylation sites on KIF1A that regulate its cargo binding and/or motility in physiological and disease states.

[Stress and electrochemical corrosion of titanium produced by laser rapid forming].

Objective: To investigate the stress corrosion and electrochemical corrosion resistance of titanium produced through laser rapid forming (LRF), and to provide a basis for their clinical application. Methods: Forged commercial pure titanium (CP-Ti) was used as control group and LRF pure titanium was used as LRF group. All samples were placed in acidic artificial saliva containing fluorine (pH=7), and loaded with a stress of 1.2 × σ(0.2) Pa (σ(0.2) represents the yield strength of material). Stress corrosion resistance of specimens that have been soaked for 30 days was analyzed by naked eye observation, X-ray diffraction analysis and scanning electron microscopy. For samples placed in artificial saliva, neutral fluoride solution (pH=7) and acidic fluoride solution (pH=3) (4 test pieces in each corrosive medium), and their electrochemical corrosion resistance was evaluated by free corrosion potential (Ecorr) measurements, corrosion current (Icorr), electrochemical impedance spectroscopy (EIS), and anodic polarization curves. Results: With the prolongation of immersion time, the corrosion products gradually increased. The stress corrosion of CP-Ti group was significantly more than that of LRF-Ti group, and the pit diameter was significantly larger than that of LRF-Ti group. The electrochemical corrosion results showed that the Ecorr (-469 mV) of LRF-Ti in artificial saliva was higher than that of CP-Ti (-555 mV), and the Ecorr (-925 mV) of LRF-Ti was higher than that of CP-Ti (-943 mV) in neutral fluoride solution. In acid fluoride solution, the Ecorr (-943 mV) of LRF-Ti was higher than that of CP-Ti (-956 mV). The Ecorr of the same metal was the highest in artificial saliva and the lowest in acid fluoride solution; the Icorr of the same metal was the lowest in artificial saliva and the highest in acid fluoride solution. Conclusions: Under the same corrosion conditions, LRF Ti demonstrated better stress and electrochemical corrosion resistance than CP-Ti.

[Antibacterial effectiveness of calcium silicate-based root canal sealer against Enterococcus faecalis biofilms in infected dentinal tubules in vitro].

Objective: To evaluate the antiseptic effect of combined using of 5% sodium hypochlorite and calcium silicate-based root canal sealer against Enterococcus faecalis (Ef) biofilms in infected dentinal tubules in vitro. Methods: Cells of Ef were inoculated into the dentinal tubules of single-rooted teeth (without caries, periapical lesions and malformations extracted due to periodontal disease or orthodontic reasons; collected from Department of Maxillofacial Surgery, The First Affiliated Hospital of Zhengzhou University) with centrifugation and incubated in brain-heart infusion (BHI) to form 3-week-old biofilms. The infected samples were subjected to sodium hypochlorite or sterile water bathing for 10 minutes followed by calcium silicate-based root canal sealer (iRoot SP) (calcium silicate-based group), Gutta-percha group and sterile water group placed on the root canal wall for 1, 4 and 12 weeks. There were two samples in each treatment at each point. The antiseptic effectiveness of combined use of sodium hypochlorite and calcium silicate-based root canal sealer was analyzed by laser scanning confocal microscope (LSCM), ANOVA and LSD-t test. Results: After treatment with 5% sodium hypochlorite, in calcium silicate-based group for 4 and 12 weeks more Ef biofilm cells [(75.3±3.5)% and (74.8±3.8)%] were killed than in Gutta-percha group [(65.9±4.1)% and (63.0±3.7)%] and sterile water group [(63.9±4.0)% and (64.2±3.5)%] (P<0.05). After being treated with sterile water, the proportion of dead bacterial cells in calcium silicate-based group for 1, 4 and 12 weeks [(27.5±4.6)%, (43.0±4.4)% and (40.3±6.1)%] were more than those in Gutta-percha group and sterile water group (P<0.05). After being treated with 5% sodium hypochlorite or sterile water, more biofilm bacteria were killed in calcium silicate-based group for 4 and 12 weeks than in calcium silicate-based group for 1 week (P<0.05). Conclusions: The combined use of sodium hypochlorite and calcium silicate-based root canal sealer kills more biofilm cells in infected dentinal tubules.

Experimental upper bound and theoretical expectations for parity-violating neutron spin rotation in 4He.

Neutron spin rotation is expected from quark-quark weak interactions in the standard model, which induce weak interactions among nucleons that violate parity. We present the results from an experiment searching for the effect of parity violation via the spin rotation of polarized neutrons in a liquid 4He medium. The value for the neutron spin rotation angle per unit length in 4He, d ϕ / d z = [ + 2.1 ± 8.3 (stat.) - 0.2 + 2.9 (sys.) ] × 10 - 7 rad/m, is consistent with zero. The result agrees with the best current theoretical estimates of the size of nucleon-nucleon weak amplitudes from other experiments and with the expectations from recent theoretical approaches to weak nucleon-nucleon interactions. In this paper we review the theoretical status of parity violation in the n → + 4He system and discuss details of the data analysis leading to the quoted result. Analysis tools are presented that quantify systematic uncertainties in this measurement and that are expected to be essential for future measurements.

[Killing activity of nonequilibrium plasma against young and old Enterococcus faecalis biofilms with long-term exposure in infected root canals in vitro].

Objective: To evaluate the antimicrobial activity of nonequilibrium plasma against Enterococcus faecalis (Ef) biofilms in vitro and to obtain novel evidence of root canal disinfection with nonequilibrium plasma. Methods: Sterile cover slips and single-rooted canals were filled with Ef and incubated to form 1-week-old and 3-week-old biofilms, respectively. The infected samples were subjected to nonequilibrium plasma, 2% chlorhexidine digluconate (CHX) and saline for 3, 10 and 30 minutes, respectively. After treatment, the killing effectiveness of nonequilibrium plasma was analyzed by using laser scanning confocal microscopy (LSCM) and colony forming unit (CFU) counting. Results: The 3-dimentional reconstruction LSCM images showed that about 48.3%-79.8% of 1-week-old Ef biofilm cells and 40.0%-67.4% of 3-week-old biofilm cells were killed by nonequilibrium plasma and 2% CHX compared to saline (P<0.05). The proportion of killing activity was lower after 3 minutes (40.0%-50.9% killing) than after 10 minutes (65.3%-77.8% killing) and 30 minutes (66.4%-79.8% killing) (P<0.05). And the killing of biofilm bacteria was fastest during the first 3 minutes (13.3%-17.0% killing per minute) and slow down greatly after 10 minutes. Remarkably more bacteria were killed in 1-week-old Ef biofilms (48.3%-79.8% killing) than in 3-week-old biofilms (P<0.05). Conclusions: The nonequilibrium plasma killed more Ef biofilm cells in infected root canals showed promotional as an additional approach against bacterial biofilms during root canal disinfection.

Contactless respiration rate measurement using optical method and empirical mode decomposition.

BACKGROUND: At the emergency triage center, assessment of the present of the danger signs and measurement of vital signs are measured according to the guidelines. The respiration rate is still posing a challenge to the doctor as it is impractical to use conventional devices. Attaching measurement devices to the patient will induce artificial measurements (self-awareness stress effects) besides being time-consuming. Currently, the medical officers visually count the number of times the chest movement in a minute, sometimes poses cultural challenges especially for female patients. OBJECTIVE: The main objective of this paper is to develop a robust algorithm to extract respiration rate using the contactless displacement sensor. METHODS: In this study, chest movements were used as an indicative of inspiration and expiration to measure respiratory rate using the contactless displacement sensor. The contactless optical signals were recorded from 32 healthy subjects in four different controlled breathing conditions: rest, coughing, talking and hand movement to obtain the motion artifacts that the patients may have in the emergency department. The Empirical mode decomposition (EMD) algorithm was used to derive continuous RR signal from the contactless optical signal. RESULTS: The analysis showed that there is a good correlation (0.9702) with RMSE of 0.33 breaths per minutes between the contact respiration rate and contactless respiration rate using empirical mode decomposition method. CONCLUSION: It can be concluded that the empirical mode decomposition method can extract the respiration rate of the contactless optical signal from chest movement.

Evidence-based management of patients with chest tube drainage system to reduce complications in cardiothoracic vascular surgery wards.

AIM: This evidence-based project was to implement the best practice to provide safe and effective care to patients with chest tube drainage system in cardiothoracic wards. METHODS: Best practice recommendations on monitoring and maintenance of chest drains were retrieved from the Joanna Briggs Institute COnNECT+ database. A checklist was developed based on these recommendations. Nurses in the two cardiovascular wards were taught how to use the checklist. Two post-implementation audits on the nurses' compliance to use the checklist were conducted. Data were analysed using the Joanna Briggs Institute Practical Application of Evidence System. RESULTS: Initial post-implementation audit results showed that the compliance rates of monitoring underwater seal, suction pressure and connector were 100%, checking of dressings 90%, and swinging and/or bubbling 70%. The checklist also detected 36 near-miss events. The second post-implementation audit results showed that the compliance rate of monitoring insertion site for air infiltration was 100%, checking of dressings 78%, and swinging and/or bubbling 91%. Fifty-seven near-miss events were detected. CONCLUSION: The use of the checklist prevented adverse events during the evidence implementation period. It can thus be concluded that using a systematic guide to observe and monitor patients with chest tubes enhances the effectiveness and safety of nursing care in the hospital.

Secondary triage classification using an ensemble random forest technique.

BACKGROUND: Triage of patients in the emergency department is a complex task based on several uncertainties and ambiguous information. Triage must be implemented within two to five minutes to avoid potential fatality and increased waiting time. OBJECTIVE: An intelligent triage system has been proposed for use in a triage environment to reduce human error. METHODS: This system was developed based on the objective primary triage scale (OPTS) that is currently used in the Universiti Kebangsaan Malaysia Medical Center. Both primary and secondary triage models are required to develop this system. The primary triage model has been reported previously; this work focused on secondary triage modelling using an ensemble random forest technique. The randomized resampling method was proposed to balance the data unbalance prior to model development. RESULTS: The results showed that the 300% resampling gave a low out-of-bag error of 0.02 compared to 0.37 without pre-processing. This model has a sensitivity and specificity of 0.98 and 0.89, respectively, for the unseen data. CONCLUSION: With this combination, the random forest reduces the variance, and the randomized resembling reduces the bias, leading to the reduced out-of-bag error.

A slow neutron polarimeter for the measurement of parity-odd neutron rotary power.

We present the design, description, calibration procedure, and an analysis of systematic effects for an apparatus designed to measure the rotation of the plane of polarization of a transversely polarized slow neutron beam as it passes through unpolarized matter. This device is the neutron optical equivalent of a crossed polarizer/analyzer pair familiar from light optics. This apparatus has been used to search for parity violation in the interaction of polarized slow neutrons in matter. Given the brightness of existing slow neutron sources, this apparatus is capable of measuring a neutron rotary power of dϕ/dz = 1 × 10(-7) rad/m.

On the progressive enrichment of the oxygen isotopic composition of water along a leaf.

A model has been derived for the enrichment of heavy isotopes of water in leaves, including progressive enrichment along the leaf. In the model, lighter water is preferentially transpired leaving heavier water to diffuse back into the xylem and be carried further along the leaf. For this pattern to be pronounced, the ratio of advection to diffusion (Péclet number) has to be large in the longitudinal direction, and small in the radial direction. The progressive enrichment along the xylem is less than that occurring at the sites of evaporation in the mesophyll, depending on the isolation afforded by the radial Péclet number. There is an upper bound on enrichment, and effects of ground tissue associated with major veins are included. When transpiration rate is spatially nonuniform, averaging of enrichment occurs more naturally with transpiration weighting than with area-based weighting. This gives zero average enrichment of transpired water, the modified Craig-Gordon equation for average enrichment at the sites of evaporation and the Farquhar and Lloyd (In Stable Isotopes and Plant Carbon-Water Relations, pp. 47-70. Academic Press, New York, USA, 1993) prediction for mesophyll water. Earlier results on the isotopic composition of evolved oxygen and of retro-diffused carbon dioxide are preserved if these processes vary in parallel with transpiration rate. Parallel variation should be indicated approximately by uniform carbon isotope discrimination across the leaf.

In vitro dissolution profiles of enteric-coated microsphere/microtablet pancreatin preparations at different pH values.

OBJECTIVES: Enteric-coated microsphere/microtablet pancreatin should stay intact in the stomach and dissolve promptly on entering the duodenum. Postprandial intraluminal pH in the distal duodenum is 5.75 and is lower in exocrine pancreatic insufficiency. The aim of the study was to measure in vitro dissolution times in buffer solutions with pH 4.0-6.0 for five currently available enteric-coated microsphere/microtablet pancreatin preparations. METHODS: The following preparations were tested: Creon, Creon Forte, Pancrease, Pancrease HL and Panzytrat. Two capsules were placed in the buffer solution at 37 degrees C in a USP dissolution testing apparatus. Buffer solutions with pH between 4.0 and 6.0 were used. Solutions were stirred at 125 r.p.m. and the rate of dissolution was monitored by taking 2-mL samples at regular intervals and measuring extinction at 280 nm. Measurements were repeated six times. RESULTS: All preparations failed to dissolve at pH 4.0. At pH 5.0 Pancrease HL showed 43% dissolution within 30 min, all other preparations 15% or less. Panzytrat and Pancrease HL showed more than 50% dissolution within 30 min at pH 5.2. Panzytrat, Pancrease HL and Creon Forte had more than 90% dissolution within 30 min at pH 5.6, and all preparations more than 90% dissolution within 30 min at pH 5.8 and higher. CONCLUSIONS: For the treatment of exocrine pancreatic insufficiency conventional strength enteric-coated microsphere/microtablet pancreatin preparations do not have an optimal dissolution profile. The newer, high lipase preparations such as Pancrease HL perform better, although still not optimally, at pH 5.4 and lower.

Comparison of a high lipase pancreatic enzyme extract with a regular pancreatin preparation in adult cystic fibrosis patients.

BACKGROUND: Malabsorption due to exocrine pancreatic insufficiency is the main gastrointestinal problem in cystic fibrosis. Despite high doses of pancreatic enzyme supplements it is often not possible to normalize fat absorption. We compared a new high lipase pancreatic enzyme preparation (Pancrease-HL; Cilag, Brussels, Belgium), containing enteric coated microspheres with 25,000 U of lipase, 22,500 U of amylase and 1250 U of protease per capsule, with regular Pancrease capsules, containing 5000 U of lipase, 2900 U of amylase and 330 U of protease per capsule. METHODS: In a randomized double-blind crossover study, 13 cystic-fibrosis patients (6 male, 7 female, mean age 27.7 years) received either four capsules of Pancrease t.d.s. or one capsule of Pancrease-HL t.d.s. Patients took 20 mg omeprazole daily to raise intra-duodenal pH and thus optimize release of enzymes from the enteric coated microspheres. RESULTS: With four capsules of Pancrease t.d.s., mean fat excretion was 15.4% and mean nitrogen excretion was 19.9% vs. 15.5% fat and 19.9% nitrogen excretion with one capsule Pancrease-HL t.d.s. Fat and protein energy loss (as a percentage of total daily intake) was 18.3% with Pancrease and 18.2% with Pancrease-HL. The differences were not statistically significant. Pancrease-HL was well tolerated, with no difference in abdominal pain or general well-being scores. The number and average weight of stools passed remained the same. CONCLUSIONS: One capsule of Pancrease-HL appears to be equivalent to four capsules of regular Pancrease. Treatment with less capsules per day with the same efficacy may facilitate patient compliance.

Post-prandial intragastric and duodenal acidity are increased in patients with chronic pancreatitis.

OBJECTIVES: Patients with chronic pancreatitis and exocrine insufficiency have lower intraduodenal pH compared to controls. It has been assumed that abnormal low intraduodenal pH in these patients not only results from impaired pancreatic bicarbonate secretion but also from an increased gastric acid load to the duodenum. METHODS: We have tested this hypothesis by combined intragastric and intraduodenal 24 h pH monitoring in nine chronic pancreatitis patients with exocrine pancreatic insufficiency and nine healthy control subjects during standardized test conditions. Postprandial gastrin and cholecystokinin release were also determined. RESULTS: Median 24-h intraduodenal pH (5.90 vs. 6.00) and intragastric pH (1.60 vs. 1.70) were not significantly different between patients and controls. However, in the 2-h postprandial periods intraduodenal pH was below five for a significantly higher percentage of time in chronic pancreatitis patients compared to controls (lunch: 14.5% vs. 0.17%, P=0.011; dinner: 24.1% vs. 5.75%, P=0.05). The post-dinner intragastric pH was below three for a significantly higher percentage of time in chronic pancreatitis patients vs. controls (72.2 vs. 48.9%, P=0.04). Postprandial gastrin release was not significantly different between the two groups. Postprandial secretion of cholecystokinin (CCK), as enterogastrone, was significantly (P < 0.01) reduced in chronic pancreatitis patients (78 +/- 13 pmol/L, 120 min) compared to controls (155 +/- 14 pmol/L, 120 min). CONCLUSIONS: Median intraduodenal and intragastric pH are not significantly decreased in patients with chronic pancreatitis and exocrine insufficiency but the postprandial time with an acidic pH in the duodenum (pH < 5) and in the stomach (pH < 3) is significantly (P

Delayed primary repair of intrathoracic esophageal perforation: is it safe?

The management of intrathoracic esophageal perforation with delayed diagnosis is a subject of controversy. Because of the obvious advantages of primary repair as a simple single-stage operation, this technique was preferentially used to treat 18 of 22 consecutive patients with esophageal perforation. These patients were stratified into three groups according to the time interval between perforation and repair: group A, less than 6 hours, five patients (28%); group B, 6 to 24 hours, six patients (33%); and group C, more than 24 hours, seven patients (39%). Group A patients were older (p < 0.05) and group B had fewer iatrogenic perforations (B, 17%; A, 80%; C, 57%, p < 0.1). Additional tissue was used to buttress the repair site in all three groups (A, 3/5 patients, 60%; B, 4/6 patients, 67%; C, 6/7 patients, 86%; p = not significant). In seven patients (39%), a fundic wrap was used to reinforce the site of primary repair. The outcomes of the three groups were analyzed. Group A had the lowest proportion of postoperative leaks (A, 0/4 patients, 0%; B, 4/6 patients, 67%; C, 5/6 patients, 83%; p < 0.05) and postoperative morbidity (A, 2/5 patients, 40%; B, 6/6 patients, 100%; C, 6/7 patients, 86%; p < 0.1). However the increased incidence of leak and morbidity did not lead to an increase in mortality. One death occurred in each group, with an overall mortality of 17% (A, 1/5 patients, 20%; B, 1/6 patients, 17%; C, 1/7 patients, 14%; p = not significant). We conclude that in the era of advanced intensive care capabilities, primary repair of intrathoracic esophageal perforation can be safely accomplished in most patients regardless of the time interval between perforation and operation. Leakage at the suture site is common unless primary repair is carried out without delay. Postoperative leakage, however, is usually inconsequential and does not necessarily result in an adverse outcome.

Chemical synthesis, molecular cloning, and expression of the gene coding for the Trichosanthes trypsin inhibitor--a squash family inhibitor.

The gene coding for a Trichosanthes trypsin inhibitor analog (Ala-6-TTI) in which methionine at position 6 was replaced by alanine was synthesized chemically. The synthetic gene was cloned into plasmid pWR590-1 and expressed in Escherichia coli as a fusion protein composed of beta-galactosidase fragment of 590 amino acid residues and (Ala-6)-TTI, with methionine as a connecting residue. After cyanogen bromide cleavage and reduction of the fusion protein, followed by refolding with trypsin-Sepharose 4B as a matrix and affinity chromatography on the immobilized enzyme, the fully active (Ala-6)-TTI was obtained. The trypsin inhibitory activity and amino acid composition of the recombinant (Ala-6)-TTI were consistent with those of the natural one. The (Ala-6)-TTI gene was also cloned into the secretion expression vector, pVT102U/alpha, in Saccharomyces cerevisiae. In order to make the reading frame of the gene compatible with the vector, a nucleotide was inserted into the (Ala-6)-TTI gene via site-directed mutagenesis. The secreted (Ala-6)-TTI was purified and found to be correctly processed at the junction between the alpha-factor leader peptide and (Ala-6)-TTI downstream. Of the two expression systems, the latter is more advantageous in the high yield (greater than 2 mg/liter), easy purification and needlessness of disulfide refolding.

Respiratory-related heart rate variability persists during central apnea in dogs: mechanisms and implications.

The aim of this study was to determine the mechanism(s) responsible for the persistence of respiratory sinus arrhythmia (RSA) during central apnea. In five awake dogs, heart rate (HR) was recorded during constant mechanical ventilation (MV) and during central apneas produced by cessation of MV. For each of 10 control ventilator cycles before MV was stopped, instantaneous HR was plotted against the time from the onset of lung inflation; the fundamental and first harmonic of a sine wave (at the ventilator frequency) was then fitted to the HR data. For the control cycles, the mean r2 from the curve fits was 0.57 +/- 0.07, showing that a significant component of the HR variability was linked to the ventilator cycle. After MV was stopped, RSA persisted and only by the third "phantom" ventilator cycle during apnea had the degree of fit consistently decreased compared with control dogs (P < 0.02). The persistence of ventilator-linked RSA at the onset of central apnea supports the concept of a "memory" in the respiratory system. Toward the end of central apnea, HR variability reappeared and had the periodicity and rhythmic profile of RSA on 81% of occasions. The presence of RSA-like activity toward the end of central apnea suggests that subthreshold rhythmic respiratory-related activity may be present even before the onset of detectable lung volume changes.

Retrograde cerebral perfusion versus selective cerebral perfusion as evaluated by cerebral oxygen saturation during aortic arch reconstruction.

BACKGROUND: Time limits for neuroprotection by retrograde cerebral perfusion (RCP) and selective cerebral perfusion (SCP) in aortic arch aneurysm repair or dissection are undergoing definition. METHODS: Using near-infrared optical spectroscopy, changes in regional cerebrovascular oxygen saturation (rSO2) were compared between the two perfusion methods. RESULTS: Immediately before cardiopulmonary bypass, baseline rSO2 was 63.9%+/-6.9% for the RCP and 66.1%+/-5.3% for the SCP group (no significant difference). As patients were core-cooled to 20 degrees C, rSO2 increased to 73.1%+/-8.8% and 74.1%+/-7.9% in the RCP and SCP groups, respectively. With circulatory arrest, rSO2 suddenly decreased. After starting cerebral perfusion, rSO2 returned to prearrest values in the SCP group but continued decreasing steadily in the RCP group, to levels below baseline after about 25 minutes. At the end of perfusion, rSO2 was 57.4%+/-12.2% for the RCP group and 71.7%+/-6.9% for the SCP group, and the ratio of rSO2 to baseline value was 0.89 for RCP and 1.08 for SCP despite a shorter brain perfusion time for RCP (38.8+/-18.0 versus 103.3+/-43.3 minutes). Three of 5 patients whose ratios of rSO2 to baseline at the end of brain protection were 0.7 or less had neurologic deficits. CONCLUSIONS: Although SCP showed no clinically important time limitation, rSO2 continued to decrease with time during RCP. An rSO2 ratio less than 0.7 could represent a critical lower limit.