A randomised trial comparing real-time double-lumen endobronchial tube placement with the Disposcope® with conventional blind placement

Double-lumen endobronchial tube placement is challenging. This study compared double-lumen tube placement with the Disposcope^® , a wireless videostylet allowing real-time visualisation, with conventional blind placement. Patients undergoing elective thoracic surgery with normal airways requiring one-lung ventilation were randomly allocated into two groups (27 patients in each group). The Disposcope was used to assist left-sided double-lumen tube placement in one group, and conventional blind placement was performed in the control group. Placement in both groups was checked with fibreoptic bronchoscopy. The Disposcope-assisted group had a shorter total mean (SD) placement time (18.6 (2.5) s vs. 21.4 (2.9) s, p < 0.001), laryngoscopy to end of auscultation time (83.4 (3.0) s vs. 93.9 (5.7) s, p < 0.001) and total operation time (130.7 (6.1) s vs. 154.5 (6.3) s, p < 0.001). In the Disposcope-assisted group, the double-lumen tube was inserted in the correct side in all patients (100.0%), whereas in the conventional group, the double-lumen tube was placed in the correct side in 25 (92.6%) patients and in the wrong side in 2 (7.4%) patients; the difference was not significant (p = 0.150). In the Disposcope-assisted group, the double-lumen tube was inserted to the optimal depth in 24 (88.9%) patients, whereas in the conventional group it was inserted to the optimal depth in one (4.0%) patient. The Disposcope increased the success rate of double-lumen tube placement, and shortened the total operation time when compared with standard placement with confirmation using fibreoptic bronchoscopy, and may replace the conventional method.

An interprofessional training program for intrahospital transport of critically ill patients: model build-up and assessment

Intrahospital transport of critically ill patients for diagnostic or therapeutic procedures can be compromised by patient instability, equipment problems or inexperienced teamworking. This quasi-experimental study aimed to assess the effectiveness of an in-situ interprofessional simulation-based training (IIST) model for junior member transport teams. Newly registered postgraduate physicians, nurses and respiratory therapists underwent the IIST. The technical skills (TS) of each participant and non-technical skills (NTS) of each interprofessional team were assessed using well-validated checklists. Thirty-six participants enrolled and were randomly assigned to six experimental and six control teams. Most participants achieved a significantly higher level of both TS and NTS. Both the control and experimental teams overvalued their NTS in the pretest, while the posttest self-assessment scores among the experimental groups more closely matched the expert assessments. Despite challenges in scheduling and the setting, the IIST was successfully conducted in a crowded hospital, which enabled trainees to optimize their learning in a real-life environment. In conclusion, the IIST model can facilitate the development of both TS and NTS for transport team members. Transport teams made up of newly registered staff from different disciplines may lack insight into their NTS in critical patient transfer management, but simulation training may cause improvements.

Validated Simulation: The Preliminary Experience of Anesthesiologist Board Examination in Taiwan

High fidelity simulation-based teaching has played an important role in medical education, especially in anesthesiology and emergency. But there is not any currently validated scoring system or prediction model for high fidelity simulation. We will develop a validated prediction model to enhance the efficiency and validation of clinical training with high fidelity simulation.

A desflurane and fentanyl dosing regimen for wake-up testing during scoliosis surgery: Implications for the time-course of emergence from anesthesia

BACKGROUND/PURPOSE

The Stagnara wake-up test assesses neurological deficits during scoliosis surgery, and response surface interaction models for opioids and inhaled agents predicts anesthetic drug effects. We hypothesized that there is an optimal desflurane-fentanyl dosing regimen that can provide a faster and more predictable wake-up time, while also ensuring adequate analgesia during wake-up testing.

METHODS

Twenty-three American Society of Anesthesiologists Class I-II scoliosis patients who received desflurane-fentanyl anesthetic regimens were enrolled in this posthoc study, and their intraoperative drug administration data were collected retrospectively. Desflurane and fentanyl effect site concentrations were calculated using pharmacokinetic models, and converted to equivalent remifentanil-sevoflurane concentrations.

RESULTS

Results were fitted into Greco models for predicting the probability of an Observers Assessment of Alertness/Sedation score of <2. At time of wake-up, the models correctly predicted the probability that patients would respond to voice prompts and prodding was approximately 50%. The probability of pain intensity was distributed between 50% and 95%, indicating a low degree of pain at emergence. When comparing subgroups defined by calculated effect-site fentanyl concentrations, the wake-up time in the intermediate concentration group was significantly shorter than that in the high concentration group (p = 0.024).

CONCLUSION

This study provides evidence that desflurane-fentanyl-based anesthesia is conducive to rapid emergence followed by an immediate neurological evaluation. Intermediate fentanyl effect-site concentrations (1-2 ng/mL) at time of wake-up were associated with good balance between rapid emergence and adequate analgesia. Furthermore, we believe that generalizing response surface models to a variety of inhalation agent-opioid combinations using simple relative potency relationships is possible and practical.

Application of an ultrasound-guided low-approach insertion technique in three types of totally implantable access port

BACKGROUND

Totally implantable access ports (TIAPs) are alternatives to central venous catheters for patients requiring chemotherapy. Since January 2003, we have used a central approach two-point incision technique to insert TIAPs. Following advances in ultrasound technique and clinical experience for tunneled dialysis catheter placement, we modified the central approach to a low-approach technique.

METHODS

From January 2009 to June 2010, patients consulted for TIAP insertion in our department were enrolled in our study. Different brands and materials of central venous catheters of TIAPs were inserted by the low-approach two-point incision technique (Phase I) or the low-approach one-point incision technique (Phase II). The insertion time, failure rate, procedural and late complications, degree of satisfaction, and cosmetic scores were recorded.

RESULTS

Ninety-seven patients and 107 patients were implanted via the two-point and one-point low-approach techniques, respectively, with different kinds of TIAP. No matter which type of TIAP was used, the success rate in both phases was 100% without procedural complications using the low-approach technique. The average time for device insertion was 30 minutes for the two-point incision technique used during Phase I and 26-28 minutes for the one-point incision technique used during Phase II. Satisfaction and cosmetic scores were high.

CONCLUSION

Our study highlights a revised technique for placement of TIAP systems of differing types of material or size. Not only was the curvature of the device catheter smooth, but patients were satisfied with the cosmetic appearance.

Successful percutaneous tracheostomy via puncture through the thyroid isthmus

Tracheostomy is one of the most frequently performed procedures in intensive care units. Bedside percutaneous tracheostomy has become an increasingly popular option to standard open tracheostomy. Several contraindications for percutaneous tracheostomy, including an enlarged thyroid isthmus, have been described. However, as experience with this technique has increased, most of the described contraindications appear to be relative rather than absolute, provided the procedure is performed by an experienced practitioner. Herein we present a case of an unavoidable direct puncture of the thyroid isthmus during a percutaneous tracheostomy. The procedure was performed smoothly, and no complications occurred.

No enlargement of the right internal jugular vein of the dialysis patients in the Trendelenburg position

BACKGROUND

The Trendelenburg position has been suggested for right internal jugular vein (RIJV) catheterization. However, this position can sometimes be functionally intolerable for chronic kidney disease patients. We conducted an ultrasound study to further investigate the efficacy of the use of the Trendelenburg position during tunneled dialysis catheter insertion via the RIJV in chronic kidney disease patients.

METHODS

We recruited into our study patients without a history of prior tunneled dialysis catheter insertion or neck surgery. Those patients with stenosis or thrombus in the RIJV were excluded. Serial ultrasound images were acquired with patients in the supine position, with the head rotated 30° to the left: Stage 0, table flat; Stage T, Trendelenburg tilt. Then, measurements of patient RIJV transverse diameter, anteroposterior (AP) diameter, and cross-sectional area (CSA) were obtained.

RESULTS

Fifty dialysis patients and 40 healthy volunteers completed the study. There were no significant differences in the lateral diameter, AP diameter, or AP/lateral diameter ratio between the dialysis patients and healthy volunteers, whether in the supine or the Trendelenburg position. However, the CSA of the RIJV of the healthy volunteers in the Trendelenburg position was significantly larger than that in dialysis patients. The change in CSA from the supine to the Trendelenburg position was also significantly different between the two groups.

CONCLUSION

In contrast to healthy volunteers, there was no enlargement of the RIJV when dialysis patients were in the Trendelenburg position. The reason for this phenomenon may be multifactorial, with diastolic dysfunction being the most likely cause, and further investigation is required to clarify the cause. Our investigation suggests that the supine position for central venous catheterization in dialysis patients is superior to the Trendelenburg position.

Diagnosis and insertion of Hickman catheter for a patient with persistent left superior vena cava

A vascular access with good function for drug delivery is the basis of chemotherapy. If there is any congenital or acquired vascular abnormality, procedurally related and late complications such as vessel rupture, malposition, and dysfunction of the catheter with ensuing thrombosis may occur, especially when it is undiagnosed or ignored. We describe a case of implantable central venous catheter (CVC) malposition and subsequent insertion of a Hickman catheter for stem cell transplantation after the diagnosis of persistent left superior vena cava (PLSVC) by radiologic image studies. The case is about a 60-year-old male who suffered from mantle cell lymphoma. He complained of discomfort when chemotherapeutic drugs were delivered through an implanted subcutaneous port system. Malposition of the CVC with aberrant path venous catheter, which led to its migration to the right internal jugular vein (RIJV) was noted on the chest X-ray. In addition, results of ultrasound imaging revealed total occlusion of the RIJV, and a subsequent three-dimensional (3D) computed tomography (CT) reconstruction image revealed a PLSVC with an atretic right SVC. Ultrasound-guided venous puncture of the left internal jugular vein and intraoperative fluoroscopy for confirming the correct guide-wire path were used for successful insertion of Hickman catheter without any complication. When unexpected occurrence of migration or malposition of the long-term CVC is detected, early removal of the catheter is vital for preventing further complications. Proper and advanced image studies including ultrasound, contrast-enhanced venography, CT, and magnetic resonance imaging may be necessary for understanding the potential vascular abnormality and guiding the following treatment.

Neonatal nociception elevated baseline blood pressure and attenuated cardiovascular responsiveness to noxious stress in adult rats

Neonatal nociception has significant long-term effects on sensory perception in adult animals. Although neonatal adverse experience affect future responsiveness to stressors is documented, little is known about the involvement of early nociceptive experiences in the susceptibility to subsequent nociceptive stress exposure during adulthood. The aim of this study is to explore the developmental change in cardiovascular regulating activity in adult rats that had been subjected to neonatal nociceptive insults. To address this question, we treated neonatal rats with an intraplantar injection of saline (control) or carrageenan at postnatal day 1. The carrageenan-treated rats exhibited generalized hypoalgesia at basal state, and localized hyperalgesia after re-nociceptive challenge induced by intraplantar injections of complete Freund's adjuvant (CFA) as adults. Then we recorded baseline cardiovascular variables and 24-h responsiveness to an injection of CFA in the free-moving adult rats with telemetric technique. The carrageenan-treated rats showed significantly higher basal blood pressures (110.3±3.16 vs. control 97.0±4.28 mmHg). In control animals, baroreceptor reflex sensitivity (BRS) decreased, sympathetic vasomotor activity increased, and parasympathetic activity was inhibited after CFA injection. Blood pressure elevation was evident (107.0±2.75 vs. pre-injection 97.0±4.28 mmHg). Comparatively, the carrageenan-treated rats showed a higher BRS (BrrLF 1.03±0.09 vs. control 0.70±0.06 ms/mmHg) and higher parasympathetic activity [0.93±0.17 vs. control 0.32±0.02 ln(ms²)] after CFA injection. The change in blood pressure is negligible (111.9±4.05 vs. pre-injection 110.3±3.16 mmHg). Our research has shown that neonatal nociception alters future pain sensation, raises basal blood pressure level, and attenuates cardiovascular responsiveness to nociceptive stress in adult rats.

Discriminant analysis for anaesthetic decision-making: an intelligent recognition system for epidural needle insertion

BACKGROUND

Incorrect placement of epidural catheters causes medical complications. We used linear discriminant analysis (LDA) to develop an intelligent recognition system (i-RS) in order to guide epidural placement and reduce physician error.

METHODS

We analysed real-time dual-wavelength fibreoptic data recorded from the end of an epidural needle in a live porcine model. Two categories of tissue layers were necessary for correct placement of catheter: epidural space and ligamentum flavum. The data were tested using linear, quadratic and logistic parametric analysis to identify which method could distinguish the two anatomical structures.

RESULTS

LDA was the best fit for our model. There was ∼80% sensitivity and specificity for correct anatomical identification. Error rates based on cross-validation were 17.0% for the epidural space and 18.6% for ligamentum flavum. Error rates were greater with the 532 nm compared with 650 nm wavelength.

CONCLUSIONS

The sensitivity and specificity of LDA for identifying the correct anatomical structure was similar to a physician who is an expert in epidural placement. Overall performance of an i-RS could be improved by expanding the database for decision-making and adding a category of uncertainty. This would reduce complications caused by incorrect epidural placement.

Prevention of dental damage and improvement of difficult intubation using a paraglossal technique with a straight Miller blade

Patients with diseased teeth, or those who are difficult to intubate, have a higher risk of dental injury during laryngoscopy. We report 3 cases of smooth endotracheal intubation using a paraglossal technique with a straight Miller blade in patients with poor dentition. Three patients with poor dentition were scheduled to undergo surgery under general anesthesia. All patients presented with extremely loose upper central incisors and had lost the other right upper teeth, while micrognathia and prominent, loose upper incisors were noted in 1 case. We elected to use a straight Miller blade using a paraglossal approach. A nasopharyngeal airway was inserted after induction of general anesthesia to facilitate mask ventilation and prevent air leakage from the mask. The Miller blade was then inserted from the right corner of the mouth, avoiding contact with the vulnerable incisors, and advanced along the groove between the tongue and tonsil. The endotracheal tube was subsequently smoothly inserted after obtaining a grade 1 Cormack and Lehane view without dental trauma in all 3 cases. Direct laryngoscopy using the paraglossal straight blade technique avoids dental damage in patients with mobile upper incisors and no right maxillary molars. It is a practical alternative method that differs from the traditional Macintosh laryngoscope in patients with a high risk of dental injury during the procedure. This technique, which provides an improved view of the larynx, might also be helpful with patients in whom intubation is difficult.

Prophylactic antibiotic administration induced bronchospasm as increased airway pressure during general anesthesia

BACKGROUND

Anaphylactic reaction induced bronchospasm as wheezing and severe elevation of airway pressure was observed in a succession of patients during general anesthesia at our institute in November 2007. The aim of this survey was to investigate the suspected causes and risk factors of these anaphylactic reactions and the degree of correlation.

METHODS

All patients who received general anesthesia between November 1 and November 10, 2007 were enrolled. Underlying diseases, substances including intravenous and inhalational anesthetics, antibiotics, and the degree of increase in airway pressure were recorded. Enrolled patients were divided into a significant-airway-pressure-elevation group (Group P) and a no-airway-pressure-elevation group (Group N).

RESULTS

A new brand of cephalexin (Roles) used as a prophylactic antibiotic was identified as the most likely causative substance of this succession of suspected anaphylactic reactions (28 in 185 patients, 15.14%), and rapid administration was a contributor to these anaphylactic reactions.

CONCLUSION

In this study, we found that rapid administration of Roles was the main cause of suspected anaphylactic reaction presenting as bronchospasm with severe elevated airway pressure. Using Roles as the prophylactic antibiotic is not recommended in patients receiving general anesthesia.

New simulation-based airway management training program for junior physicians: Advanced Airway Life Support

BACKGROUND

All junior physicians in Taiwan were enrolled into a 3-month post-graduate year 1 (PGY1) course after Severe Acute Respiratory Syndrome (SARS) attack in 2003.

AIMS

To develop and evaluate a new airway management training protocol by using an integrated course of lectures, technical workshops and medical simulations.

METHODS

In each PGY1 course, the trainees participated in the Advanced Airway Life Support (AALS) program. After 2 h lecture, the trainees were divided into three groups for 4 h technical workshop, including 10 skill stations and medical simulation at the Clinical Skills Resources Center of the hospital at different times. Video-based debriefing and feedback were performed after each simulation. The same scenario was re-simulated after debriefing. Participants' performance was assessed by single global rating and a 5 key actions scoring.

RESULTS

A total of 266 junior physicians have been trained with this AALS programs in 2 years. They learned the techniques of airway management, passed the performance checklist of technical workshop, and received higher scores during re-simulation regardless of scoring methods.

CONCLUSIONS

The AALS training program can provide methodical and systematic training for junior residents to mature with specialized technical skills and higher-order cognitive skills, behaviors and leadership in airway management.

Instructor-based real-time multimedia medical simulation to update concepts of difficult airway management for experienced airway practitioners

BACKGROUND

We integrated lecture, real-time multimedia display and medical simulation into a new renewal airway management training protocol for experienced nurse anesthetists.

METHODS

Trainees of the Taiwan Association of Nurse Anesthetists from northern Taiwan and junior residents from our department were enrolled into the training program. A 4-hour renewal curriculum in the management of airway emergencies was developed, which consisted of a 2-hour general lecture (including 4 divided sections) and a 2-hour instructor-based real-time multimedia medical simulation of 4 specific techniques. After detailed explanation of each specific instrument at the beginning of each simulation, the instructors demonstrated accurate and successful management of 4 airway crises from clinical experience by using a standardized human patient simulator situated on the stage of the conference room. Meanwhile, real-time display of instructors' performance, responsive physical parameters and images from specific instruments were conducted by video camera and video processor, and projected on a 3-frame screen. Brief summary and feedback were performed after each simulation. Trainees completed a questionnaire 6 months after they participated in the training program.

RESULTS

Two hundred and forty-two nurse anesthetists and 13 young residents were trained with this protocol. The questionnaire revealed that the renewal training program was useful. Participants updated their knowledge of difficult airway management, gained more confidence, improved performance, and provided effective assistance in handling airway crises.

CONCLUSION

Renewing practice guidelines and teaching airway management skills, especially for difficult airway crises and protection of personnel, continues to be an important issue. Instructor-based real-time multimedia simulation is a fast, useful and systematic renewal educational method for many participants with extensive experience of airway management to update their knowledge about difficult airway management, and acquire improved decision-making and communication capabilities, skills of specific airway management.

Successful management of severe upper airway obstruction during emergence of anesthesia in consequence of fracture of deflated laryngeal mask airway due to biting--a case report

Biting the laryngeal mask airway during general anesthesia in the absence of a bite block as a forestallment is a common but usually uncomplicated event. We report a young healthy adult female patient who underwent removal of fixation implant in the right elbow under general anesthesia, during the emergence of which she bit and severed the airway tube of the laryngeal mask airway (LMA) after cuff deflation and developed upper airway obstruction in consequence of air blockade by the displaced deflated LMA cuff remaining inside the mouth. Removal of residual part of the LMA in the mouth was successful with propofol re-anesthetization without molestation of 02 saturation. We discuss the management of this critical airway condition resulting from fracture of deflated LMA in the closed mouth.

Experience with removing Palmaz stents with a rigid bronchoscope

BACKGROUND

The Palmaz stent can relieve congenital malacia or stenosis of airway, but reports on the indications and results of stent removal are rare. The authors report their experience in removing Palmaz stents and discuss the indications for removal.

METHODS

Thirteen stents in 12 patients were removed by a rigid bronchoscope for various reasons. The indications were expected recovery (n = 5), severe granulations and expected recovery (n = 2), stent collapse (n = 2), and stent migration and/or fracture (n = 4).

RESULTS

The course after removal was smooth in 9 patients and complicated in 3. The indications for stent removal in these 3 complicated cases were all expected recovery. One of the 3 complicated cases needed emergent cardiopulmonary bypass and tracheostomy for a collapsed stent that occluded airway, 1 failed for intractable bleeding, and 1 failed for intense vagal reflex causing cardiac arrest. At 6 months of follow-up, satisfactory results were seen in all but one case that needed further procedures for an iatrogenic tracheoesophageal fistula.

CONCLUSIONS

Most Palmaz stents can be removed smoothly with a rigid bronchoscope; however, lethal complications can happen. The authors suggest that indications for stent removal should be intractable airway symptoms caused by the stent rather than expected recovery. Muscle relaxants should be avoided during anesthesia to maintain spontaneous breathing, and cardiopulmonary bypass should be on standby.

Anesthetic management of a patient undergoing segmental resection of trachea with an endotracheal neurofibroma and nearly total occlusion of trachea

We report a case of endotracheal (ET) neurofibroma with resultant severe airway obstruction undergoing segmental resection of the trachea. After the extracorporeal membrane oxygenation system (ECMO) was set up handily for use and comprehensive monitoring system was established, ET intubation under fiberoptic bronchoscopy (FOB) was performed under mild sedation. Surgery and anesthesia proceeded uneventfully and she was discharged uneventfully. Thorough preoperative evaluation, comprehensively anesthetic planning, FOB-assisted ET intubation before induction of anesthesia were mandatory to achieve a safe and delicate anesthesia for such a patient. In critical situation, conduction of anesthesia after establishment of ECMO support would be another choice.

High production of heterologous proteins in Escherichia coli using the thermo-regulated T7 expression system

The exclusive use of isopropyl beta-D-thiogalactopyranoside to activate the T7 promoter for protein production has limited the general use of the expression system. We have sought an alternative by constructing a recombinant Escherichia coli strain, BL21 (G2), to carry a chromosomal copy of T7 gene 1 fused to the lambdaPL and lambdaP(R) tandem promoter. As a result, the recombinant strain harboring the carbamoylase gene from Agrobacterium radiobacter NRRL B11291 was shown to display various levels of.protein production in response to different degrees of heat shock. In particular, the system remained inactive at 30 degrees C and exhibited high sensitivity to heat such that a detectable carbamoylase activity could be measured after exposure to 33 degrees C. Moreover, heating in two steps - elevating the temperature from 30 degrees C to 39 degrees C and holding for a brief period, followed by reducing to 37 degrees C--was found to be the most potent method for protein production in this case. Using this approach, the recombinant protein accounted for 20% of total protein content of the cell. These results reveal the advantages of this expression system: responsiveness to thermal modulation and high-level production capability. In an attempt to enhance the total protein yield, a fed-batch fermentation process was carried out to control the cell growth rate by adjusting the substrate inflow. By applying the two-step temperature change. a carbamoylase yield with enzyme activity corresponding to 14,256 units was obtained. This production yield is a 10-fold increase in comparison with that at the batch-fermentation scale and 2,000-fold higher than that achieved at the shake-flask scale. Overall, it illustrates the promise of the newly constructed T7 system based on heat inducibility for industrial scale production of recombinant proteins.

Early epileptic encephalopathy with suppression burst electroencephalographic pattern--an analysis of eight Taiwanese patients

Early epileptic encephalopathy with suppression burst (SB) comprises two distinct epileptic syndromes, early infantile epileptic encephalopathy (EIEE) and early myoclonic encephalopathy (EME). We reviewed etiologies, neurological outcome and clinico-electroencephalographic features of EIEE and EME. Chart records of early epileptic encephalopathy with SB from January 1997 to December 2000 were reviewed. These cases fulfilled the diagnostic criteria of EIEE and EME. Totally eight patients (four females, four males) were enrolled. They consisted of three cases of EIEE and five cases of EME. The follow-up periods ranged from 6 to 30 months. For EIEE, two cases had migrational disorders, and one was cryptogenic; for EME, three cases had non-ketotic hyperglycinemia (NKH), one was pyridoxine dependency and one was cryptogenic. The main initial seizure patterns were tonic spasms in EIEE, and were erratic myoclonus in EME. The age of seizure onset ranged from 26 h to 5 days after birth for EIEE, and 2 h to 7 days of life for EME. The SB pattern in the electroencephalography (EEG) was noted mainly during sleep state in EME, but in both awake and sleep states in EIEE. Asymmetric SB pattern and background activities in EEG were found in migrational disorders. The EEG in all cases of EIEE changed to hypsarrhythmia at 4-6 months of age. In EME, only the EEG in cases of NKH evolved to hypsarrhythmia. Response to anti-convulsants was generally poor. All had severe psychomotor retardation. Although EIEE and EME share several common features, differences in terms of seizure seminology and evolution, EEG patterns and etiologies still exist.

Otogenic brain abscess--a case report

Brain abscess is one of the life-threatening complications of otitis media. Mortality and morbidity have decreased with the advent of antibiotic therapy. More frequently encountered in cases of acute otitis media in the preantibiotic era, in recent years otogenic brain abscess was noticed almost only in patients of chronic otitis media with cholesteatoma. A case of brain abscess in a 49-year-old female was initially diagnosed as a headache. A high resolution computed tomography (HRCT) scan of the temporal bones later revealed that there were two abscesses over the right side temporal lobe. A modified radical mastoidectomy was performed. Cultures of the middle ear cholesteatoma later grew Pseudomonas aeruginosa and Strenotrophomonas maltophilia. Antibiotic therapy was carried on for three months postoperatively. The patient improved but retained a conductive hearing loss.

One-step production of D-p-hydroxyphenylglycine by recombinant Escherichia coli strains

The gene encoding D-hydantoinase from Agrobacterium radiobacter NRRL B11291 was successfully cloned by use of polymerase chain reaction. A positive clone was scored, and its nucleotide sequence was further analyzed. The analysis by deleting various lengths of nucleotides from the amino terminus of the open reading frame revealed the putative regions for promoter and RBS site. By highly expressing both D-hydantoinase and carbamoylase, recombinant Escherichia coli strains were able to convert DL-hydroxyphenyl hydantoin (DL-HPH) to D-p-hydroxyphenylglycine (D-HPG) with a conversion yield of 97%, accounting for productivity 5 times higher than that obtained by A. radiobacter NRRL B11291. Immobilizing the recombinant cells with kappa-carrageenan could also achieve a conversion of 93%, while A. radiobacter NRRL B11291 attained 20% within the same period of reaction time. These results illustrate the feasibility in employing recombinant E. coli to accomplish one-step conversion of DL-HPH to D-HPG. In the process of improving D-HPG production, D-hydantoinase activity was increased 2.57-fold but carbamoylase activity remained constant, which resulted in only a 30% increase in the reaction rate. It suggests that carbamoylase is the step setting the pace of the reaction. Since the reaction substrate is highly insoluble, achieving sufficient agitation appears to be an important issue in this heterogeneous system. This view is further supported by the study on repeated use of cells, which shows that to reach a conversion of more than 90% free cells can be recycled six times, whereas immobilized cells can be used only twice. In conclusion, the poor reusability of immobilized cells is due to the fouling on the gel surface.

Characterization of a human immunodeficiency virus type 1 variant with reduced sensitivity to an aminodiol protease inhibitor

Development of viral resistance to the aminodiol human immunodeficiency virus (HIV) protease inhibitor BMS 186,318 was studied by serial passage of HIV type 1 RF in MT-2 cells in the presence of increasing concentrations of compound. After 11 passages, an HIV variant that showed a 15-fold increase in 50% effective dose emerged. This HIV variant displays low-level cross-resistance to the C2 symmetric inhibitor A-77003 but remains sensitive to the protease inhibitors Ro 31-8959 and SC52151. Genetic analysis of the protease gene from a drug-resistant variant revealed an Ala-to-Thr change at amino acid residue 71 (A71T) and a Val-to-Ala change at residue 82 (V82A). To determine the effects of these mutations on protease and virus drug susceptibility, recombinant protease and proviral HIV type 1 clones containing the single mutations A71T and V82A or double mutation A71T/V82A were constructed. Subsequent drug sensitivity assays on the mutant proteases and viruses indicated that the V82A substitution was responsible for most of the resistance observed. Further genotypic analysis of the protease genes from earlier passages of virus indicated that the A71T mutation emerged prior to the V82A change. Finally, the level of resistance did not increase following continued passage in increasing concentrations of drug, and the resistant virus retained its drug susceptibility phenotype 34 days after drug withdrawal.

Inhibition of human cytomegalovirus replication by 9-(1,3-dihydroxy-2-propoxymethyl)guanine alone and in combination with human interferons

The inhibitory action of 9-(1,3-dihydroxy-2-propoxymethyl)guanine on the replication of human cytomegalovirus was studied. Three laboratory strains (AD-169, Towne, and Davis) and three early passage (less than 10) clinical isolates were all inhibited in yield inhibition assays. In cultures infected with AD-169, virus yields could be inhibited if the drug was added as late as 3 days after the replication cycle had begun. The effects of the drug were fully reversible during the first 4 days of the viral replication cycle. Viral infectivity and viral DNA synthesis were reduced more than viral protein synthesis. Synergistic antiviral effects were observed with beta-cysteine, and to a lesser extent, with beta-serine recombinant interferons, but only over a narrow range of dose combinations.

Comparison of antiviral activities of cloned and native human interferons against herpes simplex virus types 1 and 2 and human cytomegalovirus

Five recombinant alpha interferons and two recombinant beta interferons have been tested for their ability to inhibit yields of herpes simplex virus types 1 and 2 and human cytomegalovirus in human embryonic lung cells. All of the alpha species and both of the beta forms (cysteine and serine) were active against the herpesviruses tested in this study. Neither the recombinant alpha nor the recombinant beta interferons exceeded the activity of the native species against herpes simplex viruses types 1 and 2. However, the recombinant beta interferons inhibited cytomegalovirus more than either the native beta or the alpha interferon species with the exception of interferon alpha K (alpha 6).

Surgical treatment of esophageal carcinoma

Recent progress in the surgical treatment of carcinoma of the esophagus has changed the pessimistic outlook for this malignancy. With reasonably early diagnosis, it is feasible to achieve a resectability rate of 75 to 85 percent, an operative mortality of about 5 percent and a 5 year survival rate of about 30 percent. With careful selection of patients for operation and proper use of radiation and other adjunctive therapy, even more encouraging results are possible. Efforts for further improvement may be directed toward early diagnosis, refinement in operative technique and better pre- and postoperative care. The use of microsurgery and the development of mechanical suture apparatus in esophageal reconstruction after resection may further improve surgical treatment of cancer of the esophagus. Thoracic surgeons still have the responsibility to improve the management of the nonresectable cases of carcinoma of the esophagus.