[Dissection technique--is ultrasound the best method?]

Preventive hemostasis is extremely important in endoscopic surgery. Ultrasonic dissectors are used very often. We tested the occlusion safety of bipolar forceps and ultrasonic dissector for porcine vessels. Thermographic videos showed maximum temperature up to 200 degrees C when using one ultrasonic dissector. The lateral damage zone in vivo and in vitro measured between 2 and 6 mm.

[Gene therapy in diabetic foot]

In gene therapy nucleic acids are used for therapy. There are three different concepts in gene therapy for chronic wounds. (1) Synthesis of human recombinant growth factors by gene therapy techniques, (2) Ex-vivo transfection of cell cultures (fibroblasts, keratinocytes) with growth factor DNA and subsequent transplantation of transfected cells on chronic wounds. (3) In-vivo transfection with growth factor DNA, e.g., gene gun, liposomes, viral vector. Clinical studies on gene therapy for diabetic foot ulcers are only available for the local application of human recombinant PDGF-BB growth factor. Meta-analysis shows there is a low but significant effect of PDGF-BB on neuropathic diabetic ulcers, leading to an increase of healing by 10-15% within 20 weeks of treatment.

Human duodenal spheroids for noninvasive intracellular pH measurement and quantification of regulation mechanisms under physiological conditions

Three-dimensional cell cultures (spheroids) of biopsies of human duodenum were used to develop a new noninvasive method for studying intercellular and intracellular mechanisms. Through examinations of intracellular pH regulation, high functional similarity to native tissue could be shown, as already evidenced morphologically. A special microperfusion chamber was developed to fix individual spheroids physically to a nylon net, via laminar perfusion flow through the chamber. A significant improvement over current fixation methods was shown by the increase of cell viability almost up to 100%. Viability of the spheroids was confirmed by trypan blue exclusion, by a LIVE/DEAD viability/cytotoxicity kit, and by BCECF distribution. Intracellular pH was measured by use of the pH-sensitive fluorescence dye BCECF. To investigate the intracellular pH regulation, spheroid-like vesicles were acidified by NH4Cl prepulse technique. The subsequent active intracellular pH recovery was blocked with Na+-free Krebs Henseleit (KH) solution, with amiloride KH (inhibitor of the Na+-H+-exchanger), or with H2DIDS KH (inhibitor of the HCO3(-)-Cl(-)-exchanger and Na+-HCO3(-)-cotransporter). The intracellular pH of the spheroids was 7.31 +/- 0.05. pH-backregulation after acidification was prevented by sodium-free buffer, amiloride, and H2DIDS. These experiments indicated the presence of a Na+-H+-exchanger and a Na+-HCO3(-)-cotransporter. In conclusion, the human duodenal spheroid is an excellent physiological system for in vitro studies of the human duodenum.

A single amidotransferase forms asparaginyl-tRNA and glutaminyl-tRNA in Chlamydia trachomatis

Aminoacyl-tRNA is generally formed by aminoacyl-tRNA synthetases, a family of 20 enzymes essential for accurate protein synthesis. However, most bacteria generate one of the two amide aminoacyl-tRNAs, Asn-tRNA or Gln-tRNA, by transamidation of mischarged Asp-tRNA(Asn) or Glu-tRNA(Gln) catalyzed by a heterotrimeric amidotransferase (encoded by the gatA, gatB, and gatC genes). The Chlamydia trachomatis genome sequence reveals genes for 18 synthetases, whereas those for asparaginyl-tRNA synthetase and glutaminyl-tRNA synthetase are absent. Yet the genome harbors three gat genes in an operon-like arrangement (gatCAB). We reasoned that Chlamydia uses the gatCAB-encoded amidotransferase to generate both Asn-tRNA and Gln-tRNA. C. trachomatis aspartyl-tRNA synthetase and glutamyl-tRNA synthetase were shown to be non-discriminating synthetases that form the misacylated tRNA(Asn) and tRNA(Gln) species. A preparation of pure heterotrimeric recombinant C. trachomatis amidotransferase converted Asp-tRNA(Asn) and Glu-tRNA(Gln) into Asn-tRNA and Gln-tRNA, respectively. The enzyme used glutamine, asparagine, or ammonia as amide donors in the presence of either ATP or GTP. These results suggest that C. trachomatis employs the dual specificity gatCAB-encoded amidotransferase and 18 aminoacyl-tRNA synthetases to create the complete set of 20 aminoacyl-tRNAs.

Endobronchial ultrasound

Endobronchial ultrasound (EBUS) is a new diagnostic tool, which has expanded the view of the bronchoscopist beyond the confinements of the airways. It has great potential for diagnosis of mediastinal processes and staging of lung cancer. These will be discussed and illustrated. EBUS will become a superior tool for staging of lung cancer, and several comparative studies on EBUS as compared with standard techniques in order to assess its role in the staging procedure are just on their way or already completed.

[Network of surgical wound centers using a new electronic data processing documentation system]

Care of chronic wounds is of enormous medical, social and economic importance. Nevertheless there is a lack of epidemiological and economical data. A network of ten wound care centers was created and data were documented in a new computerized wound documentation system.

METHODS

Treatment was performed according to a comprehensive and standardized wound care protocol. The new documentation system is a network-capable solution. Digital images and planimetry as well as patient and wound related data are recorded.

RESULTS

During the first year the ten centers treated and documented already 3281 wounds. There is a wide spectrum of different chronic wounds treated in the participating centers. Despite of long wound duration of several wounds with a median of 5 weeks (range 0-62 years), the healing rate was 80% within 455 days.

CONCLUSION

Large amounts of data can be collected and scientifically evaluated in the wound net. This is realized by a new computerized documentation system, which was integrated into the clinical routine and enables clear and standardized documentation. Therefore even large multicenter therapy studies may be performed easily in the wound net and economical data could be collected.

In vitro test of new biomaterials for the development of a bioartificial pancreas

The implantation of macroencapsulated islets has the potential to restore endogenous insulin secretion in type 1 diabetics, with no need for lifetime immunosuppression. To match the physiological fluctuations of blood glucose concentrations with appropriate insulin release, the macroencapsulation material must combine immunoprotection with optimal diffusion properties for glucose and insulin. The impact of chemical modifications of polysulphone (PSU) capillary polymers with a cutoff of 50 kD on glucose-induced insulin secretion of macroencapsulated rat islets was studied in perifusion experiments. The insulin release of free-floating islets showed the typical rapid response to glucose stimulation. Total insulin release (AUC between minute 30 and 120 of perifusion) reached 117+/-22 ng/ml. Blending PSU with polyvinylpyrrolidone or sodium-dodecyl-sulfate was not suitable for islet macroencapsulation, since glucose-induced insulin release was absent or disturbed. Hydroxy-methylation (CH2OH) of PSU improved the secretory behavior of macroencapsulated islets depending on the degree of PSU substitution (DS 0.8, AUC 62+/-15 ng/ml; DS 1.8, 111+/-24 ng/ml). In highly substituted PSU-capillaries the kinetics of glucose-induced insulin release was very similar to that observed in free-floating islets. Two consecutive glucose stimulations potentiated insulin release of free-floating islets during the second period of stimulation. Furthermore, freshly isolated macroencapsulated islets responded with more efficient insulin secretion after the initial priming. In conclusion, in vitro membrane screening identified highly substituted hydroxy-methylated PSU as the material of choice for islet encapsulation in a bioartificial pancreas.

Long-term outcome and lung cancer incidence in patients with hemoptysis of unknown origin

STUDY OBJECTIVE

To provide current data on the long-term outcome and incidence of lung cancer in a large cohort of patients with hemoptysis of unknown origin.

DESIGN

A retrospective chart review followed by a telephone interview for follow-up.

SETTING

A university-affiliated tertiary referral center for pulmonary diseases.

PATIENTS

Seven hundred twenty-two patients who presented with hemoptysis from January 1990 to December 1993. One hundred thirty-five patients were identified as having hemoptysis of unknown origin.

RESULTS

One hundred thirty-five patients (19%) had hemoptysis of unknown origin; follow-up data were obtained in 115 patients, of whom 100 were still alive. The mean time of observation was 6.6 years after initial presentation. Lung cancer developed in 7 of 115 patients (6%) and was unresectable once detected; all of these patients were smokers > 40 years old, and malignancy developed within 3 years after first presentation.

CONCLUSIONS

Hemoptysis of unknown origin is present in a minority of patients presenting with hemoptysis if evaluated at a referral center for pulmonary diseases. Lung cancer seems to be increasing in these patients compared to previous studies, and closer follow-up or additional testing may be indicated in the defined population at risk.

Ethics and triage

A disaster is characterized by an imbalance between needs and supplies. In circumstances in which there occur mass casualties, it is not possible to provide care for all of the victims. Thus, it may be necessary to triage the casualties according to pre-established priorities. The performance of triage is associated with many ethical issues. Currently, no Europe-wide agreement on triage and ethics exists. One system based on a categorization into four groups is proposed. Triage should be avoided whenever possible, but, when it is required, there is an obligation to respect human rights and the humanitarian laws, especially with reference to the Geneva Convention of 1864 and the Universal Declaration of Human Rights of 1948. The condition of informed consent must be followed, even in mass casualty situations. Triage always must follow established medical criteria and cannot be based on any other principles. Triage implies constant re-evaluation of victims as conditions of the victims and of available resources change continuously. In order to facilitate international coordination and cooperation, a universal classification system must be adopted.

Neostigmine increases postoperative colonic motility in patients undergoing colorectal surgery

BACKGROUND

Gastrointestinal motility is frequently impaired after abdominal surgery. We investigated the effects of neostigmine on colonic motility in patients after colorectal surgery and in healthy volunteers.

METHODS

Colonic motility was recorded by a manometry/barostat system in 12 patients after left colonic or rectal resection during baseline and after the intravenous administration of increasing doses of neostigmine on postoperative days 1, 2, and 3. In addition, colonic motility was recorded in 7 healthy volunteers.

RESULTS

Neostigmine increased the colonic motility index. This increase was from 135 +/- 28 mm Hg/min at baseline to 574 +/- 219 mm Hg/min after administration of 5 microg/kg neostigmine on day 3 after surgery (mean +/- SEM, P <.05). In healthy volunteers, neostigmine at a dose of 5 microg/kg increased the colonic motility index from 184 +/- 73 to 446 +/- 114 mm Hg/min (P <.05). Barostat bag volumes decreased dose-dependently after neostigmine administration in patients as well as in volunteers, indicating an increase in colonic tone.

CONCLUSIONS

Colonic motility and tone increased after neostigmine administration at a dose of 5 microg/kg in postoperative patients and in healthy volunteers. Neostigmine can be used to stimulate colonic motility after colorectal surgery and has a similar effect postoperatively as in healthy volunteers.

Insulin-like growth factor I accelerates gastric ulcer healing by stimulating cell proliferation and by inhibiting gastric acid secretion

BACKGROUND

Given the importance of Insulin-Like Growth Factor I (IGF-I) to intestinal maintenance and the presence of IGF-I in salivary glands, we hypothesized that IGF-I participates in the healing of gastric ulcers. The aim of the study was to determine: 1) whether IGF-I applied locally would support gastric ulcer healing by increasing cell proliferation and 2) the effect of IGF-I on gastric acid secretion.

METHODS

Gastric ulcers were induced with a cryoprobe. Immediately thereafter, IGF-I (0.4, 4.0 and 40 microg) or vehicle was infiltrated perifocally. In another group, animals received a daily dose of 40 micromol omeprazole subcutaneously. Ulcer healing was evaluated by ulcer size and histological examination at 7 days. Pentagastrin-stimulated gastric acid secretion was evaluated in conscious rats with gastric fistula, after IGF-I (400 microg) had been injected intravenously.

RESULTS

IGF-I significantly reduced ulcer size, but only at low doses (0.4 microg/kg body weight (BW), P = 0.008; 4 microg/kg BW, P = 0.001). This effect was similar to omeprazole treatment. Histological examination after IGF-I administration showed increased cell proliferation, increased IGF-I content and down-regulated IGF-I receptors. The secretory studies demonstrated a significant decrease in gastric acid secretion 30 min after IGF-I bolus injection (IGF-I: 53 +/- 11 microEq; vehicle: 116 +/- 5 microEq; P=0.001), which lasted for more than 1 h.

CONCLUSION

IGF-I stimulates gastric ulcer healing, stimulating cell proliferation and inhibiting gastric acid secretion.

[Proliferation rate of small cell lung carcinoma. A cytomorphometric parameter with prognostic significance]

AIM

Evaluation of prognosis-associated parameters in patients with small cell lung carcinoma.

MATERIAL AND METHODS

Biopsies of 46 patients suffering from a non-treated small cell lung carcinoma were stained with Feulgen and immunohistochemically with Ki-67 antibody. The integrated optical density (IOD) and proliferation rate was measured by syntactic structure analysis and correlated with survival.

RESULTS

About 85% of patients had a smoking history (46 pack years on average). The median survival time was 13.5 months, the proliferation rate (Ki-67 positive tumor cell nuclei) 68.2% and S-phase percentage 9.2%. Ot average, 25 proliferating tumor cell nuclei formed clusters (mean diameter 95 microns). The prognosis was associated with the proliferation rate (p < 0.04), tumor stage (stage I versus lib, p < 0.05), at threshold limits with S-phase rate (p < 0.07) and serum levels of LDH and NSE (p < 0.06 and p < 0.07 respectively).

CONCLUSIONS

Immune histochemical determination of the Ki-67 protein is a useful method to estimate the prognosis of patients with small cell lung carcinoma.

Preoperative intraluminal application of capsaicin increases postoperative gastric and colonic motility in rats

In a model to investigate postoperative gastrointestinal motility with strain gauge transducers in awake rats, we tested the effects of intraluminal capsaicin infusion into the cecum 2 days or 14 days prior to abdominal surgery. Acute infusion of capsaicin into the cecum for 30 minutes increased the gastric, small intestinal, and colonic motility index by up to 115%, 34%, and 59%, respectively, compared to vehicle infusion. Intraluminal capsaicin infusion 2 days prior to abdominal surgery significantly increased the intraoperative gastric and colonic motility index by 166% and 100%, respectively, compared to vehicle, but had no effect on small intestinal motility. The postoperative decrease in gastric or colonic motility was completely prevented by capsaicin pretreatment, representing a 73% and a 72% increase in the motility index during the first postoperative hour and a 40% and a 29% increase in the motility index during the second postoperative hour compared to vehicle, whereas the postoperative decrease in small intestinal motility was not altered by capsaicin pretreatment. In contrast, intraluminal capsaicin infusion 14 days prior to abdominal surgery had no effect on postoperative inhibition of gastrointestinal motility. Our results suggest that capsaicin-sensitive visceral afferent C-fibers, presumably of the submucosa, play an important role in mediating postoperative ileus. Intraluminal capsaicin does probably ablate these nerve fibers temporarily, with no systemic side effects observed with the use of the tail flick test as a measure of skin nociception.

[Usefulness of stress echocardiography for early diagnosis of anthracycline-induced cardiomyopathy]

BACKGROUND

Early evidence of drug induced cardiomyopathy is of great importance in oncological treatment, especially for application of Anthrazyklines. Stress echocar-diography (SE) has been proven to be of value in determining left ventricular function at rest and under stress. This study was performed to investigate the cardiac function under Anthrazykline-chemotherapy (aCT).

PATIENTS AND METHODS

Patients with malignant thoracic tumors and indication for aCT underwent pharmacological SE (infusion of increasing dobutamin-doses, 5 microgram/kg/bw in 3 minute-steps) before starting aCT. Left ventricular ejection fraction (LVEF) and wall motion were measured. If the tumor decreased and the patients underwent 4 or more cycles of CT, at the end of the last CT another SE investigation was performed.

RESULTS

30 patients (20 men, 15 women; mean age 52, range 28 - 71) were included and the data were compared. Before aCT the mean LVEF was 59 % at rest and 71 % at maximum load, no disturbances of wall motion could be observed. After the end of aCT (mean dose 408 mg, range 256 - 549; mean 4.4 cycles, range 4 - 7) the LVEF was 58 at rest and 68 at maximum load (not significant) and there were also no disturbances of motion.

CONCLUSION

SE is an alternative to echocardiography at rest in assessment of left ventricular function in patients receiving Anthrazykline-CT. With the doses applied no patient developed cardiomyopathy. So we consider SE a cost-effective method and safe for patients.

Genomics and the evolution of aminoacyl-tRNA synthesis

Translation is the process by which ribosomes direct protein synthesis using the genetic information contained in messenger RNA (mRNA). Transfer RNAs (tRNAs) are charged with an amino acid and brought to the ribosome, where they are paired with the corresponding trinucleotide codon in mRNA. The amino acid is attached to the nascent polypeptide and the ribosome moves on to the next codon. Thus, the sequential pairing of codons in mRNA with tRNA anticodons determines the order of amino acids in a protein. It is therefore imperative for accurate translation that tRNAs are only coupled to amino acids corresponding to the RNA anticodon. This is mostly, but not exclusively, achieved by the direct attachment of the appropriate amino acid to the 3'-end of the corresponding tRNA by the aminoacyl-tRNA synthetases. To ensure the accurate translation of genetic information, the aminoacyl-tRNA synthetases must display an extremely high level of substrate specificity. Despite this highly conserved function, recent studies arising from the analysis of whole genomes have shown a significant degree of evolutionary diversity in aminoacyl-tRNA synthesis. For example, non-canonical routes have been identified for the synthesis of Asn-tRNA, Cys-tRNA, Gln-tRNA and Lys-tRNA. Characterization of non-canonical aminoacyl-tRNA synthesis has revealed an unexpected level of evolutionary divergence and has also provided new insights into the possible precursors of contemporary aminoacyl-tRNA synthetases.

RANTES in the postoperative course after liver transplantation

RANTES (regulated upon activation, normal T-cell expressed and secreted), an inflammatory cytokine, promotes accumulation and activation of leukocytes. In 67 liver transplantations, systemic concentrations of RANTES were correlated to graft survival and incidence of rejection. RANTES levels either increased to highly elevated levels at day 14 (84 +/- 64 ng/ml; group 1; n = 43) or remained within the limit of healthy controls (19 +/- 11 ng/ml at day 14; group 2; n = 24). The 100-day graft function rate was 0.91 in group 1 and 0.63 in group 2 (P = 0.002). The risk ratio for rejection during the first 100 days was increased 2.2-fold in group 2 compared to group 1 (P = 0.02). High postoperative release of RANTES after liver transplantation, a beneficial factor, may reflect a general systemic immunological activation. It can be concluded that high early systemic RANTES levels may play a role in immunological recognition leading to a tolerance of the liver graft.

Documentation in bronchology

With the performance of more endoscopic procedures and newly developed diagnostic and therapeutic modalities, a wealth of information around the actual procedure is created. To date, accepted guidelines for standardized documentation are lacking. The authors present recommendations for minimal guidelines that may help to facilitate good documentation and also address future developments that will be possible with the help of computer-assisted approaches.

Bronchoscopy. Year 2001 and beyond

The current revolution in technology, imaging, and information processing will be of major influence on bronchoscopy within the next two decades. Clinicians will be able to visualize structures in vivo that up to now only the pathologist could see. Clinicians will reach anatomic structures that are inaccessible by the bronchoscope, yet treat diseases that are still the domain of surgeons, medical oncologists, and radiotherapists. Clinicians will be able to communicate online worldwide, improving standards of patient care, teaching, and finally even perform interventional procedures by way of networks. Because of the exponential growth of sciences like nanotechnology and biotechnology, these changes will come very rapidly. The new quality of these intelligent instruments will demand a new ideological and ethical discourse on the future of science in general.

Successful bronchoscopic placement of tracheobronchial stents without fluoroscopy

BACKGROUND

Tracheobronchial stenting is performed increasingly often. Fluoroscopic control, which leads to significant radiation exposure for patients and staff, is recommended for the placement of metal stents.

METHODS

All consecutive patients referred to two airway centers in need of airway stenting who received stents (Ultraflex; Boston Scientific, Natick, MA) underwent placement using endoscopic guidance only. All data were collected in an ongoing continuous database.

RESULTS

One hundred stents were placed in 96 patients for central airway obstruction, and the data were reviewed. Stents were placed in all locations within the central airways for a variety of indications but mainly for malignant obstruction. No complications occurred, and all stents were placed satisfactorily.

CONCLUSION

At centers with dedicated airway teams, Ultraflex stents can be quickly and safely inserted without the need for fluoroscopy. This saves radiation exposure to patients and to staff and may lead to a more cost-effective procedure.

Functional T lymphocytes infiltrate implanted polyvinyl alcohol foams during surgical wound closure therapy

Vacuum-assisted closure involving the implantation of polyvinyl alcohol foam is a technique recently developed for the treatment of patients suffering from either wound infection or chronic wounds. This method has been shown to improve and accelerate wound healing. However, little is known about the cell populations that infiltrate the foam, and their potential role in resolving the infection and promoting granulation tissue formation. Our study demonstrates that wound-implanted foams are mainly infiltrated with granulocytes, but that mononuclear cells, including macrophages and minor populations of T, B and natural killer lymphocytes, are also present. We show that foam-infiltrating T cells, especially CD4(+) T cells, constitute a phenotypically and functionally heterogeneous population influenced by wound-infecting bacteria. Thus, T lymphocytes could play a role in wound cleansing. In addition, our data indicate that implanted polyvinyl alcohol foams might be suitable microenvironments for manipulating T cell-mediated immune responses in patients.

Molecular genetic abnormalities in premalignant lung lesions: biological and clinical implications

Lung cancer is a leading cause of cancer death worldwide; however, despite major advances in cancer treatment during the past two decades, the prognostic outcome of lung cancer patients has improved only minimally. This is largely due to the inadequacy of the traditional screening approach, which detects only well-established overt cancers and fails to identify precursor lesions in premalignant conditions of the bronchial tree. In recent years this situation has fundamentally changed with the identification of molecular abnormalities characteristic of premalignant changes; these concern tumour suppressor genes, loss of heterozygosity at crucial sites and activation of oncogenes. After considering the morphological modifications that occur in premalignant lesions of the bronchial tree, we analyse the alterations occurring in a series of relevant genes: p53 and its functional regulation by MDM2 and p14ARF, p16INK4, p15INK4b, FHIT, as well as LOH at important sites such as 3p, 8p, 9p and 5q. Activation of oncogenes is considered for K-ras, the cyclin D1, the heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2/B1), and finally the c-myc oncogene. The expression of c-myc is influenced strongly by the presence of growth factors (GFs), among which EGF is of prime importance, as well as its receptor coded for by the c-erbB-2 oncogene. Basic knowledge at the molecular level has extremely important clinical implications with regard to early diagnosis, risk assessment and prevention, and therapeutic targets. The novel techniques for early diagnosis and screening of premalignant lung lesions, such as fluorescence bronchoscopy, endobronchial ultrasound, spiral computed tomography combined with precise spatial localization techniques, should basically change the approach to the problems raised by this disease and allow for an increased discovery rate of incipient lesions. Sequential applications will lead to the identification of individuals/populations at high risk, while the availability of accurate 'intermediate end points' will enable the effects of preventive trials to be monitored. Finally, the same molecular abnormalities may serve as 'starting points' for innovative treatments designed to restore the altered functions to normality. Recent developments in our knowledge and understanding of the molecular genetic abnormalities in premalignant lung lesions open an era of hope.

[Endobronchial juvenile hemangioma in infancy--removal by main bronchus cuff resection. Case report]

The rare case of a 3.5 month-old infant diagnosed with a endobronchial haemangioma is presented and discussed against a background of reference literary material. A main-bronchus sleeve resection with end-to-end anastomosis was performed without reduction of lung parenchyma. No complications were documented during the period of observation. The results of repeated bronchoscopy showed the post-operative period to be of a non-problematic nature.

MHC antigen presentation on the surface of hepatocytes: modulation during and after hypoxic stress

Presentation and recognition of MHC antigen on the surface of cells is the basic process of initiating rejection and distinguishing "self and not self". This is considered to begin when a transplanted organ is reperfused with the blood of the recipient. In this study, the modulation of MHC I antigen presentation during preservation was investigated in a cell culture model using primary hepatocyte cultures of male Wistar rats. By incubation with different preservation solutions used in clinical transplantation, expression of the MHC antigen was observed during cold hypoxia. Primary hepatocyte cultures were isolated from male Wistar rats by a modified Seglen technique and seeded to glass slides, thus obtaining monolayer cultures. After 1 day of resting the cultures were incubated under different conditions using Krebs Henseleit solution (KH), Euro-Collins solution (EC), HTK solution of Bretschneider (HTK) and University of Wisconsin solution (UW) as incubation media. The conditions of incubation were warm normoxia (37 degrees C, pO2 100 mm Hg) and cold hypoxia (4 degrees C, pO2 < 0.1 mm Hg), which is the main condition of organ preservation. Incubation time was 6 h. Before starting the incubation reference cultures were fixed and every 60 min several cultures were withdrawn from the experiment and fixed also. MHC expression was studied by staining the cultures with monoclonal antibodies against rat MHC class I and class II. As expected, MHC class II was not present on the surface of hepatocytes, while MHC class I was demonstrated on the controls as well as on the cultures that were incubated using KH and EC independent of temperature and hypoxia or normoxia. At the end of the incubation they were still positive but not as strong as in the beginning. During incubation using HTK and UW, MHC I was not detectable at all phases of the experiment. In conclusion, hypoxic stress did not completely eradicate MHC I expression in rat hepatocytes, while the composition of the preservation medium may result in a hepatocyte surface negative for MHC I. Hydroxyethylstarch may be the substance in UW that covers the MHC antigen, while in HTK, mannitol or the histidine complex may play the same role. MHC negativity of the cells of a preserved transplant is another reason for the benefit of UW or HTK.

Intraperitoneal capsaicin treatment reduces postoperative gastric ileus in awake rats

INTRODUCTION

Postoperative gastric ileus interferes with postoperative recovery of the patients. Previous studies suggest that capsaicin-sensitive afferent neurons are involved in the mediation of postoperative gastric ileus.

METHODS

A group of rats were equipped with a strain gauge transducer sutured to the gastric wall. Gastric motility was recorded after intraperitoneal injection of capsaicin (0.1 micromol/kg and 1 micromol/kg) or vehicle. The rats were given 2 days of recovery before gastric motility was investigated in a postoperative ileus model.

RESULTS

Pretreatment with capsaicin 2 days prior to abdominal surgery significantly increased postoperative gastric motility, with complete recovery of gastric motility at 30 min postoperatively (with the baseline motility index set at 100+/-4%, the gastric motility index 30-45 min postoperatively was 64+/-4% for the vehicle, 138+/-20% for capsaicin 0.1 micromol/kg, and 110+/-12% for capsaicin 1 micromol/kg: P=0.0008 vehicle vs capsaicin). In contrast, capsaicin treatment 2 h prior to abdominal surgery did not increase postoperative gastric motility (gastric motility index 30-45 min postoperatively was 64+/-4% for the vehicle and 51+/-8% for capsaicin 0.1 micromol/kg). The acute intraperitoneal injection of capsaicin decreased gastric motility by about 50-60%, the response lasting for 15-30 min.

CONCLUSIONS

Intraperitoneal capsaicin treatment 2 days prior to abdominal surgery resulted in immediate recovery of postoperative gastric motility, indicating an important role for serosal visceral afferent nerve fibers in the mediation of postoperative gastric ileus. Possibly, capsaicin or vanilloid (capsaicin) receptor agonists can be used to treat postoperative ileus in the future.

Endobronchial ultrasound (EBUS)--assessment of a new diagnostic tool in bronchoscopy for staging of lung cancer

BACKGROUND AND OBJECTIVE

Conventional imaging procedures proved to be insufficient for staging of lung cancer, especially with respect to N-stage, infiltration of mediastinal structures, and early lung cancer. As also the view of the endoscopist is restricted, we developed the new method of endobronchial ultrasonography (EBUS) as an adjunct to conventional bronchoscopy. The initial technical problems were solved by development of a balloon catheter for application of miniaturized 20-MHz probes.

PATIENTS AND METHODS

Between January and December, 1999 all patients with an indication for bronchoscopy and additional EBUS were documented prospectively.

RESULTS

In 648 patients we used additional EBUS. Of these, 242 (37%) were female and 406 (63%) were male. The mean age was 49.2 (range 0-83) years. The mean procedure time for the bronchoscopies was 18.9 (range 5.7-38.9) min, and the mean time for EBUS was 6.3 (range 3.1-14.4) min. Side effects were comparatively rare. 34 patients (5%) needed supplementary oxygen during the examination, the others tolerated EBUS without any desaturation.

CONCLUSION

EBUS is a new technology that can be easily applied and is well tolerated. It improves the results of bronchoscopy in addition to conventional diagnostic procedures. Further developments will be made in future to improve the application of ultrasound in chest medicine.

Sensitive detection of rare cancer cells in sputum and peripheral blood samples of patients with lung cancer by preproGRP-specific RT-PCR

RT-PCR-based amplification of transcripts expressed in cancer but not in normal non-neoplastic cells is increasingly used for the sensitive detection of rare disseminated or exfoliated cancer cells to improve cancer staging and early detection protocols. However, these assays are frequently hampered by false-positive test results due to low-level transcription of the marker genes in normal cells. To overcome these limitations, target transcripts have to be identified that are tightly suppressed in normal non-neoplastic tissues, whereas they should be actively transcribed in the respective cancer cells. Here, we tested RT-PCR assays for 7 neuroendocrine marker transcripts including NCAM, PGP 9.5, gastrin, gastrin receptor, synaptophysin, preprogastrin-releasing peptide (preproGRP) and GRP-receptor to detect rare exfoliated tumor cells in peripheral venous blood and sputum samples from patients with lung cancer. Among these preproGRP RT-PCR was the only assay with which illegitimate transcription in blood or sputum samples from healthy donors or patients with unrelated diseases did not interfere. However, it reproducibly detected up to 10 small-cell lung cancer cells diluted in either 10 ml blood or 5 ml sputum samples. Single blood and sputum samples were collected directly before diagnostic bronchoscopy from 175 patients suspected to have lung cancer. Twenty-six of these had small-cell lung cancer (SCLC). Thereof, 13 patients (50%) tested positive in the blood sample and 5 of 23 patients (22%) tested positive in the sputum sample. Moreover, among 92 patients with non-small-cell lung cancer (NSCLC) 25 patients (27%) had disseminated cancer cells in peripheral blood. Amplification of preproGRP transcripts from clinical samples is a sensitive and specific assay to detect disseminated or exfoliated lung cancer cells either in peripheral blood or sputum samples.

Methanococcus jannaschii prolyl-cysteinyl-tRNA synthetase possesses overlapping amino acid binding sites

The protein translation apparatus of Methanococcus jannaschii possesses the unusual enzyme prolyl-cysteinyl-tRNA synthetase (ProCysRS), a single enzyme that attaches two different amino acids, proline and cysteine, to their cognate tRNA species. Measurement of the ATP-PP(i) exchange reaction revealed that amino acid activation, the first reaction step, differs for the two amino acids. While Pro-AMP can be formed in the absence of tRNA, Cys-AMP synthesis is tRNA-dependent. Studies with purified tRNAs indicate that tRNA(Cys) promotes cysteine activation. The k(cat) values of wild-type ProCysRS for tRNA prolylation (0.09 s(-1)) and cysteinylation (0.02 s(-1)) demonstrate that both aminoacyl-tRNAs are synthesized with comparable rates, the cysteinyl-tRNA synthetase activity being only 4.5-fold lower than prolyl-tRNA synthetase activity. Kinetic analysis of ProCysRS mutant enzymes, generated by site-directed mutagenesis, shows glutamate at position 103 to be critical for proline binding, and proline at position 100 to be involved in cysteine binding. The proximity in ProCysRS of amino acid residues affecting binding of either cysteine or proline strongly suggests that structural elements of the two amino acid binding sites overlap.

Contemporary role of modern brachytherapy techniques in the management of malignant thoracic tumors

Sole brachytherapy for carcinoma of the lung is most often performed using high-dose-rate (HDR) remote afterloading equipment, which delivers the treatment within the tracheobronchial tree in an outpatient setting. It provides excellent, rapid palliation in advanced stages, and can also be used selectively for curative intent in early stages. In better-performance patients, fractionated external beam radiation therapy (EBRT) is preferred to brachytherapy as an initial treatment because it appears to provide a modest gain in survival, and more sustained palliation. In patients with centrally located tumors and limited extent of disease, the combination of external and endoluminal irradiation enables curative treatment options. Intraoperative brachytherapy may complement standard adjuvant treatment in incompletely resected, unresectable, or medically inoperable patients, and has the potential to improve local control in selected cases. Due to the rarity of the disease, the role of endoluminal brachytherapy in the treatment regimen of tracheal neoplasms is not yet clearly defined. The risk of fatal bleeding after endoluminal brachytherapy appears to be correlated with tumor localization and fraction size, but in the majority of cases fatal bleeds are caused by progression of local disease. The use of a distanceable applicator provides a central positioning of the source, prevents the delivery of high-contact doses to the mucosa, and may reduce toxicity. The standard technique for interstitial brachytherapy after breast-conserving surgery and adjuvant EBRT is the use of low-dose-rate (LDR) brachytherapy, but it may also be applied by means of pulsed-dose-rate (PDR) or HDR techniques. Prospective trials comparing different boost techniques and indications are needed to define more precisely the subgroup of patients who are most suitable for interstitial brachytherapy. Reirradiation of chest wall local recurrences using brachytherapy molds is effective and provides a high local control rate with acceptable toxicity.

Context-dependent anticodon recognition by class I lysyl-tRNA synthetases

Lysyl-tRNA synthesis is catalyzed by two unrelated families of aminoacyl-tRNA synthetases. In most bacteria and all eukarya, the known lysyl-tRNA synthetases (LysRSs) are subclass IIb-type aminoacyl-tRNA synthetases, whereas many archaea and a scattering of bacteria contain an unrelated class I-type LysRS. Examination of the recognition of partially modified tRNA(Lys) anticodon variants by a bacterial (from Borrelia burgdorferi) and an archaeal (from Methanococcus maripaludis) class I lysyl-tRNA synthetase revealed differences in the pattern of anticodon recognition between the two enzymes. U35 and U36 were both important for recognition by the B. burgdorferi enzyme, whereas only U36 played a role in recognition by M. maripaludis LysRS. Examination of the phylogenetic distribution of class I LysRSs suggested a correlation between recognition of U35 and U36 and the presence of asparaginyl-tRNA synthetase (AsnRS), which also recognizes U35 and U36 in the anticodon of tRNA(Asn). However, the class II LysRS of Helicobacter pylori, an organism that lacks AsnRS, also recognizes both U35 and U36, indicating that the presence of AsnRS has solely influenced the phylogenetic distribution of class I LysRSs. These data suggest that competition between unrelated aminoacyl-tRNA synthetases for overlapping anticodon sequences is a determinant of the phylogenetic distribution of extant synthetase families. Such patterns of competition also provide a basis for the two separate horizontal gene transfer events hypothesized in the evolution of the class I lysyl-tRNA synthetases.

Sphincter-saving treatment in epidermoid anal cancer: cooperative analysis of 142 patients in five German university surgical centers

Five southern German university centers cooperated in comparing the effect of surgical vs. nonsurgical therapy strategies on survival and sphincter preservation in the treatment of anal cancer. A standardized questionnaire was used to evaluate retrospectively (mean follow-up 30 months) treatment strategy and outcome (survival, colostomy rate, colostomy-free survival) in patients treated between 1987 and 1996. Of the 142 patients 65% had squamous cell, 20% basaloid, 6% adeno-, and 1% undifferentiated carcinoma (8% histology not recorded); 9% were classified in UICC stage I, 37% in stage II, 25% in stage III, and 4% in stage IV (25% not recorded). Primary treatment consisted of local excision (10%), excision plus radio- and/or chemotherapy (17%), radiotherapy (20%), radiochemotherapy (28%), or colostomy with or without resection, radiotherapy, and chemotherapy (23%). We observed no difference between these treatment groups in overall (P = 0.43) or colostomy-free survival (P = 0.14, log-rank). Primary colostomy was prevented in 77% of cases and decreased over the years. Mean overall survival (in months) was 42 in stage I, 38 in stage II, and 25 in stage III (P = 0.0013); mean colostomy-free survival was 36 in stage I, 26 in stage II, and 16 in stage III (P = 0.0021, log-rank). Outcome was not significantly related to therapeutic strategy (surgery or radio-chemotherapy. Primary surgical and nonsurgical strategies in treating anal cancer thus produced similar results, although radiochemotherapy is usually recommended for sphincter-endangering anal cancer. Challenges to be met in the future include the prevention of metastasis and long-term preservation of anal sphincter function.

The postoperative course of gamma-glutamyl transpeptidase--a marker of cytomegalovirus (CMV) replication risk?

Cytomegalovirus (CMV) infection is a common complication in the postoperative course of liver transplantation. In order to start early prophylactic therapy, but to avoid unnecessary treatment, or expensive screening, a desirable goal in post-transplant monitoring is to find appropriate markers in standard laboratory diagnostics. In the present study, the results of a 6-week CMV replication monitoring schedule by the pp65 antigenemia assay in 100 liver graft recipients were included. The activities of transaminases, glutamate dehydrogenase and gamma-glutamyl transpeptidase (gamma-GT) were measured by routine laboratory methods. In contrast to the transaminases, the serum activity of gamma-GT increased during the first postoperative week. The maximum levels were 246 +/- 211 U/l in patients without (n = 46) and 140 +/- 89 U/l in patients with early CMV replication (n = 54; p = 0.02). Patients with gamma-GT levels below 200 U/l on the 5th postoperative day (n = 72) had a CMV replication risk of 65%, whereas those patients with gamma-GT levels above this threshold had a risk of 30% (n = 28; p = 0.0007; relative risk = 2.9). These findings provide a routinely usable marker for the identification of patients at an increased risk of CMV replication. It can be considered that these phenomena may be caused by an additional immunosuppressive effect of the CMV virus.

Functional results after laparoscopic rectopexy for rectal prolapse

We investigated the functional results after laparoscopic rectopexy for rectal prolapse in 29 patients at least 12 months postoperatively. Twenty patients were evaluated completely pre- and postoperatively (median 22 months postoperatively, range 12 to 54 months). Six patients were interviewed by telephone, two patients were lost to follow-up, and one patient died of causes unrelated to rectal prolapse. Patients underwent a proctologic examination, anoscopy, rigid sigmoidoscopy, fluoroscopic defecography, and anorectal manometry pre- and postoperatively, and an additional standardized interview postoperatively. Anorectal manometry showed a significant increase in maximum anal resting and squeeze pressures postoperatively (resting pressure 72 +/- 8 vs. 95 +/- 13 mm Hg, pre- vs. postoperatively; P = 0.046; squeeze pressure 105 +/- 17 vs. 142 +/- 19 mm Hg, pre- vs. postoperatively; P = 0.035), and continence improved postoperatively (Wexner incontinence score 6.0 +/- 1.0 vs. 3.9 +/- 0.8 pre- vs. postoperatively, P = 0.02). Twenty (77%) of 26 patients were satisfied with the operative result, but functional morbidity was observed in four patients, with two patients complaining of severe evacuation problems. Rectal prolapse recurred in one patient 42 months postoperatively (recurrence rate 1 [3.8%] of 26 patients). Functional results were very similar to those obtained after open rectopexy, with symptoms of prolapse and incontinence improved in the great majority of patients.

[Possibilities of demonstration of growth factors in chronic wounds. Demonstration of RNA and protein in wound tissue]

Growth factors are important modulators of wound healing. So far, there is little clinical data showing that healing defects in chronic wounds are attribute to deficiency of growth factor expression. Characterization of growth factor expression is necessary to provide new directions toward developing therapies in treating wounds. Present available molecular and immunological techniques allow the analysis of mRNA and protein expression in small amounts of wound material. We analyzed growth factor expression in wound tissue and wound fluid from acute and secondary healing wounds. Wound tissue of secondary healing wounds reveals a higher mRNA growth factor expression compared to acute wound tissue. Secondary healing wounds from our studies demonstrated no deficiency of growth factor expression however, functional analysis may be necessary to determine their activity.

Identification of tumor-associated MHC class I ligands by a novel T cell-independent approach

Specific immunotherapy of cancer utilizes tumor-directed cytotoxic T lymphocytes (CTL) that lyse tumor cells presenting MHC class I-associated peptides derived from tumor-associated proteins. Many tumor-associated gene products are known, but corresponding T cell epitopes are only known for relatively few of these. The most commonly used approaches to identify such antigens require pre-existing CTL lines or clones. By using a CTL-independent high performance liquid chromatography mass spectrometry (HPLC MS)-based approach we identified HLA-A2-presented peptides from carcinoembryonic antigen and wild-type p53 with a copy number as low as eight molecules per cell. Potential epitopes were predicted from the sequences of known tumor antigens and the corresponding synthetic peptides were analyzed by nanocapillary HPLC MS. In parallel, peptides were extracted from fresh, solid tumor tissue or tumor cell lines and analyzed in the same way. Upon co-elution of a natural peptide with a predicted peptide of the same mass, the peptide sequence was confirmed by on-line tandem MS. This approach allows rapid screening of large numbers of tumor-associated gene products for naturally processed peptides presented by different MHC class I molecules as a prerequisite for efficient epitope identification and rapid transfer to therapeutic vaccine trials.

Domain-specific recruitment of amide amino acids for protein synthesis

The formation of aminoacyl-transfer RNA is a crucial step in ensuring the accuracy of protein synthesis. Despite the central importance of this process in all living organisms, it remains unknown how archaea and some bacteria synthesize Asn-tRNA and Gln-tRNA. These amide aminoacyl-tRNAs can be formed by the direct acylation of tRNA, catalysed by asparaginyl-tRNA synthetase and glutaminyl-tRNA synthetase, respectively. A separate, indirect pathway involves the formation of mis-acylated Asp-tRNA(Asn) or Glu-tRNA(Gln), and the subsequent amidation of these amino acids while they are bound to tRNA, which is catalysed by amidotransferases. Here we show that all archaea possess an archaea-specific heterodimeric amidotransferase (encoded by gatD and gatE) for Gln-tRNA formation. However, Asn-tRNA synthesis in archaea is divergent: some archaea use asparaginyl-tRNA synthetase, whereas others use a heterotrimeric amidotransferase (encoded by the gatA, gatB and gatC genes). Because bacteria primarily use transamidation, and the eukaryal cytoplasm uses glutaminyl-tRNA synthetase, it appears that the three domains use different mechanisms for Gln-tRNA synthesis; as such, this is the only known step in protein synthesis where all three domains have diverged. Closer inspection of the two amidotransferases reveals that each of them recruited a metabolic enzyme to aid its function; this provides direct evidence for a relationship between amino-acid metabolism and protein biosynthesis.

Influence of airway-occluding instruments on airway pressure during jet ventilation for rigid bronchoscopy

We measured changes in airway pressure (Paw) caused by microsurgical instruments introduced into a rigid bronchoscope during high frequency jet ventilation (HFJV). With approval of the institutional Ethics Committee, 10 adults undergoing elective tracheobronchial endoscopy and endosonography during general anaesthesia were investigated. Inflation of an endosonography probe balloon in the left main stem bronchus caused airway obstruction. Pressure measurements proximal and distal to the obstruction were compared after three degrees of obstruction (0%, 50% and 90%) and with two different driving pressure settings. Airway obstruction increased the mean (SD) peak inspiratory pressure (PIP) from 7.5 (2.6) to 9.5 (3.5) mm Hg for 2 atm (P = 0.0008) and from 9.7 (3.7) to 13.0 (5.1) mm Hg for 3 atm (P = 0.0001). Airway obstruction did not alter peripheral PIP (7.2 (4.1) to 7.1 (3.7) mm Hg for 2 atm and 8.8 (4.3) to 9.4 (5.2) mm for 3 atm), but resulted in an end-expiratory pressure (EEP) beyond the narrowing being significantly greater than in the unobstructed airway (2.5 (3.4) to 5.5 (3.7) mm Hg for 2 atm; P = 0.0005) and 3.2 (3.6) to 8.0 (4.3) mm for 3 atm; P < 0.0001). Severe airway narrowing increases inspiratory pressure proximal and expiratory pressure distal to the obstruction in relation to the applied driving pressure. Since the distal EEP never exceeded PIP, even near-total airway obstruction should not cause severe lung distension or barotrauma in subjects with normal lungs.

Identification of tumor-associated MHC class I ligands by a novel T cell-independent approach

Specific immunotherapy of cancer utilizes tumor-directed cytotoxic T lymphocytes (CTL) that lyse tumor cells presenting MHC class I-associated peptides derived from tumor-associated proteins. Many tumor-associated gene products are known, but corresponding T cell epitopes are only known for relatively few of these. The most commonly used approaches to identify such antigens require pre-existing CTL lines or clones. By using a CTL-independent high performance liquid chromatography mass spectrometry (HPLC MS)-based approach we identified HLA-A2-presented peptides from carcinoembryonic antigen and wild-type p53 with a copy number as low as eight molecules per cell. Potential epitopes were predicted from the sequences of known tumor antigens and the corresponding synthetic peptides were analyzed by nanocapillary HPLC MS. In parallel, peptides were extracted from fresh, solid tumor tissue or tumor cell lines and analyzed in the same way. Upon co-elution of a natural peptide with a predicted peptide of the same mass, the peptide sequence was confirmed by on-line tandem MS. This approach allows rapid screening of large numbers of tumor-associated gene products for naturally processed peptides presented by different MHC class I molecules as a prerequisite for efficient epitope identification and rapid transfer to therapeutic vaccine trials.

The heterotrimeric Thermus thermophilus Asp-tRNA(Asn) amidotransferase can also generate Gln-tRNA(Gln)

Thermus thermophilus strain HB8 is known to have a heterodimeric aspartyl-tRNA(Asn) amidotransferase (Asp-AdT) capable of forming Asn-tRNA(Asn) [Becker, H.D. and Kern, D. (1998) Proc. Natl. Acad. Sci. USA 95, 12832-12837]. Here we show that, like other bacteria, T. thermophilus possesses the canonical set of amidotransferase (AdT) genes (gatA, gatB and gatC). We cloned and sequenced these genes, and constructed an artificial operon for overexpression in Escherichia coli of the thermophilic holoenzyme. The overproduced T. thermophilus AdT can generate Gln-tRNA(Gln) as well as Asn-tRNA(Asn). Thus, the T. thermophilus tRNA-dependent AdT is a dual-specific Asp/Glu-AdT resembling other bacterial AdTs. In addition, we observed that removal of the 44 carboxy-terminal amino acids of the GatA subunit only inhibits the Asp-AdT activity, leaving the Glu-AdT activity of the mutant AdT unaltered; this shows that Asp-AdT and Glu-AdT activities can be mechanistically separated.

Postoperative colonic motility and tone in patients after colorectal surgery

PURPOSE

Colonic motility is crucial for the resolution of postoperative ileus. However, few data are available on postoperative colonic motility and no data on postoperative colonic tone. We aimed to characterize postoperative colonic tone and motility in patients.

METHODS

Nineteen patients were investigated with combined barostat and manometry recordings after left colonic surgery. During surgery a combined recording catheter was placed in the colon with two barostat bags and four manometry channels cephalad to the anastomosis. Recordings were performed twice daily from Day 1 to Day 3 after surgery.

RESULTS

Manometry showed an increasing colonic motility index, which was a mean (+/- standard error of the mean) of 37 +/- 5 mmHg/minute on Day 1, 87 +/- 19 mmHg/minute on Day 2, and 102 +/- 13 mmHg/minute on Day 3 (P < 0.05 for Day 1 vs. Day 2 and Day 2 vs. Day 3). Low barostat bag volumes indicating a high colonic tone were observed on Day 1 after surgery and increased subsequently (barostat bag I was 19 +/- 4, 32 +/- 6, and 32 +/- 6 ml; barostat bag II was 13 +/- 1, 19 +/- 3, and 22 +/- 5 ml on Days 1, 2, and 3, respectively; for both barostat bags P < 0.05 for Day 1 vs. Day 2 but not Day 2 vs. Day 3).

CONCLUSIONS

Colonic motility increased during the postoperative course. The low barostat bag volumes indicated a high colonic tone postoperatively which would correspond to a contracted rather than to a distended colon. High colonic tone postoperatively may be relevant for pharmacologic treatment of postoperative ileus.

The adaptor hypothesis revisited

As originally postulated in Crick's Adaptor hypothesis, the faithful synthesis of proteins from messenger RNA is dependent on the presence of perfectly acylated tRNAs. The hypothesis also suggested that each aminoacyl-tRNA would be made by a unique enzyme. Recent data have now forced a revision of this latter point, with an increasingly diverse array of enzymes and pathways being implicated in aminoacyl-tRNA synthesis. These unexpected findings have far-reaching implications for our understanding of protein synthesis and its origins.

[Inguinal hernia: accident sequela?]

The evaluation of an inguinal hernia as a result of an accident has to be newly discussed because of new radiologic tools like US, CT and MRI. Therefore an injury of the abdominal wall after an adequate trauma has to be proved. This can also be achieved by radiology, in which signs of injury, as contusion and hematoma, can be detected. Moreover the histological signs of injury and bleeding, i.e. fibrinexudation, capillary granulation tissue, round cells, siderophages, fibrocytes and fibroblast proliferation must be proved.

Intermittent capnography during high-frequency jet ventilation for prolonged rigid bronchoscopy

BACKGROUND

Gas exchange during high-frequency jet ventilation (HFJV) for prolonged rigid bronchoscopy (RBS) is usually monitored by arterial blood gas analysis. Capnography of expired gases during brief HFJV discontinuation may be a reliable and noninvasive supplemental method. Capnography can be performed either for single breaths or with respiratory rate (RR) reduced to 10 x min(-1). The aim of this study was to demonstrate that capnography during short periods of HFJV discontinuation represents a reliable measure of PaCO2 during prolonged RBS.

METHODS

We prospectively investigated 100 consecutive patients (75 male and 25 female) undergoing HFJV for RBS. HFJV was delivered through the rigid bronchoscope at the following settings: working pressure 1.2 bar, rate 100 x min(-1), FIO2 0.99, t(i)/t(tot)0.6. The light guiding channel ending at the distal tip of the rigid bronchoscope was used for gas sampling. Capnograms were assessed at 5 min intervals and compared to PaCO2 from arterial blood samples drawn simultaneously. The accuracy of single breath CO2 sampling was compared with sampling at RR=10 x min(-1).

RESULTS

Mean duration of RBS was 30+/-21 min. A significant correlation between capnography (PetCO2) and arterial blood gas analysis (PaCO2) was observed, being r=0.90 for the RR= 10 x min(-1) method and r=0.91 for the single breath method. Mean difference between PaCO2 and PetCO2 was 0.37+/-0.2 kPa throughout the entire study period. No significant differences between single breath sampling or sampling at RR=10 x min(-1) were observed.

CONCLUSION

Capnography performed during short periods of HFJV discontinuation reliably and noninvasively reflects PaCO2 during prolonged endoscopic procedures. Capnography during HFJV for RBS may reduce the frequency of arterial blood gas sampling, the duration of unmonitored intervals and costs.

Thermus thermophilus contains an eubacterial and an archaebacterial aspartyl-tRNA synthetase

Thermus thermophilus possesses two aspartyl-tRNA synthetases (AspRSs), AspRS1 and AspRS2, encoded by distinct genes. Alignment of the protein sequences with AspRSs of other origins reveals that AspRS1 possesses the structural features of eubacterial AspRSs, whereas AspRS2 is structurally related to the archaebacterial AspRSs. The structural dissimilarity between the two thermophilic AspRSs is correlated with functional divergences. AspRS1 aspartylates tRNA(Asp) whereas AspRS2 aspartylates tRNA(Asp), and tRNA(Asn) with similar efficiencies. Since Asp bound on tRNA(Asn) is converted into Asn by a tRNA-dependent aspartate amidotransferase, AspRS2 is involved in Asn-tRNA(Asn) formation. These properties relate functionally AspRS2 to archaebacterial AspRSs. The structural basis of the dual specificity of T. thermophilus tRNA(Asn) was investigated by comparing its sequence with those of tRNA(Asp) and tRNA(Asn) of strict specificity. It is shown that the thermophilic tRNA(Asn) contains the elements defining asparagine identity in Escherichia coli, part of which being also the major elements of aspartate identity, whereas minor elements of this identity are missing. The structural context that permits expression of aspartate and asparagine identities by tRNA(Asn) and how AspRS2 accommodates tRNA(Asp) and tRNA(Asn) will be discussed. This work establishes a distinct structure-function relationship of eubacterial and archaebacterial AspRSs. The structural and functional properties of the two thermophilic AspRSs will be discussed in the context of the modern and primitive pathways of tRNA aspartylation and asparaginylation and related to the phylogenetic connexion of T. thermophilus to eubacteria and archaebacteria.