Comparison of Laryngeal Mask Airway Seal Between Anesthesiologists and Individuals Without Previous Airway Experience

BACKGROUND

Tracheal intubation is the gold standard for airway management in emergency medicine, but more difficult to apply for inexperienced individuals than laryngeal mask airway (LMA).

OBJECTIVE

The aim of our study was to investigate if inexperienced individuals are able to secure the airway with the help of LMA after a short introduction. A second aim was to evaluate Thiel-fixed specimens against unfixed ones.

METHODS

In a body donor model, LMA application was evaluated between medical students without previous airway experience and anesthesiologists by comparing the sealing of the larynx using a water column applied to the esophagus.

RESULTS

LMAs were successfully applied in 46 out of 55 (83.6%) attempts by medical students and in 30 out of 39 (76.9%) attempts by anesthesiologists. Among medical students, 14.1% of all LMA applications were primarily leaky, compared with 18.8% in anesthesiologists. Esophageal sealing was better in Thiel-fixed specimens (leakage 10.9%) compared with unfixed specimens (leakage 22.9%). Our data showed no significant difference between anesthesiologists and medical students in terms of sealing of LMA. Therefore, we conclude that medical students without previous airway experience can quickly learn to apply LMA sufficiently and thus, achieve aspiration protection similar to anesthesiologists.

CONCLUSION

Medical students without previous airway experience can successfully insert LMAs after a short introduction. Thiel-fixed specimens are suitable for studies as well as for training in LMA application.

Analysis of tourniquet pressure over military winter clothing and a short review of combat casualty care in cold weather warfare

Cold weather warfare is of increasing importance. Haemorrhage is the most common preventable cause of death in military conflicts. We analysed the pressure of the Combat Application Tourniquet® Generation 7 (CAT), the SAM® Extremity Tourniquet (SAMXT) and the SOF® Tactical Tourniquet Wide Generation 4 (SOFTT) over different military cold weather clothing setups with a leg tourniquet trainer. We conducted a selective PubMed search and supplemented this with own experiences in cold weather medicine. The CAT and the SAMXT both reached the cut off value of 180mmHg in almost all applications. The SOFTT was unable to reach the 180mmHg limit in less than 50% of all applications in some clothing setups. We outline the influence of cold during military operations by presenting differences between military and civilian cold exposure. We propose a classification of winter warfare and identify caveats and alterations of Tactical Combat Casualty Care in cold weather warfare, with a special focus on control of bleeding. The application of tourniquets over military winter clothing is successful in principle, but effectiveness may vary for different tourniquet models. Soldiers are more affected and impaired by cold than civilians. Military commanders must be made aware of medical alterations in cold weather warfare.

Editorial on the Research Topic of Sports Training and the Promotion of Physical Health

Sport activities are a deciding factor in maintaining or achieving physical health [...].

Initial Treatment of High-Altitude Pulmonary Edema: Comparison of Oxygen and Auto-PEEP

BACKGROUND

Improvement of oxygenation is the aim in the therapy of high-altitude pulmonary edema (HAPE). However, descent is often difficult and hyperbaric chambers, as well as bottled oxygen, are often not available. We compare Auto-PEEP (AP-Pat), a special kind of pursed lips breathing, against the application of bottled oxygen (O₂-Pat) in two patients suffering from HAPE.

METHODS

We compare the effect of these two different therapies on oxygen saturation measured by pulse oximetry (SpO₂) over time.

RESULT

In both patients SpO₂ increased significantly from 65-70% to 95%. Above 80% this increase was slower in AP-Pat compared with O₂-Pat. Therapy started immediately in AP-Pat but was delayed in O₂-Pat because of organizational and logistic reasons.

CONCLUSIONS

The well-established therapies of HAPE are always the option of choice, if available, and should be started as soon as possible. The advantage of Auto-PEEP is its all-time availability. It improves SpO₂ nearly as well as 3 L/min oxygen and furthermore has a positive effect on oxygenation lasting for approximately 120 min after stopping. Auto-PEEP treatment does not appear inferior to oxygen treatment, at least in this cross-case comparison. Its immediate application after diagnosis probably plays an important role here.

Effects of Acute Exposure and Acclimatization to High-Altitude on Oxygen Saturation and Related Cardiorespiratory Fitness in Health and Disease

Maximal values of aerobic power (VO₂max) and peripheral oxygen saturation (SpO₂max) decline in parallel with gain in altitude. Whereas this relationship has been well investigated when acutely exposed to high altitude, potential benefits of acclimatization on SpO₂ and related VO₂max in healthy and diseased individuals have been much less considered. Therefore, this narrative review was primarily aimed to identify relevant literature reporting altitude-dependent changes in determinants, in particular SpO₂, of VO₂max and effects of acclimatization in athletes, healthy non-athletes, and patients suffering from cardiovascular, respiratory and/or metabolic diseases. Moreover, focus was set on potential differences with regard to baseline exercise performance, age and sex. Main findings of this review emphasize the close association between individual SpO₂ and VO₂max, and demonstrate similar altitude effects (acute and during acclimatization) in healthy people and those suffering from cardiovascular and metabolic diseases. However, in patients with ventilatory constrains, i.e., chronic obstructive pulmonary disease, steep decline in SpO₂ and V̇O₂max and reduced potential to acclimatize stress the already low exercise performance. Finally, implications for prevention and therapy are briefly discussed.

Rapid ascents of Mt Everest: normobaric hypoxic preacclimatization

BACKGROUND

Acclimatization to high altitude is time consuming. An expedition to Mt Everest (8848 m) requires roughly 8 weeks. Therefore it seems very attractive to reach the summit within 3 weeks from home, which is currently promised by some expedition tour operators. These rapid ascent expeditions are based on two main components, normobaric hypoxic training (NHT) prior to the expedition and the use of high flow supplemental oxygen (HFSO2). We attempted to assess the relative importance of these two elements.

METHODS

We evaluated the effect of NHT on the basis of the available information of these rapid ascent expeditions and our experiences made during an expedition to Manaslu (8163 m) where we used NHT for preacclimatization. To evaluate the effect of an increased O2 flow rate we calculated its effect at various activity levels at altitudes of 8000 m and above.

RESULTS

So far rapid ascents to Mt Everest have been successful. The participants carried out 8 weeks of NHT, reaching sleeping altitudes = 7100 m and spent at least 300 h in NH. At rest a flow rate of 2 l O2/min is sufficient to keep the partial pressure of inspired oxygen (PIO2) close to 50 mm Hg even at the summit. For ativities of ~80% of the maximum rate of oxygen consumption (VO2max) at the summit 6 l O2/min are required to maintain a PIO2 above 50 mm Hg.

DISCUSSION

NHT for preacclimatization seems to be the decisive element of the offered rapid ascent expeditions. An increased O2 flow rate of 8 l/min is not mandatory for climbing Mt Everest.

CONCLUSIONS

Preacclimatization using normobaric hypoxica (NH) is far more important than the use of HFSO2. We think that NHT will be widely used in the future. The most effective regimen of preacclimatization in NH, the duration of each session and the optimal FIO2 are still unclear and require further study.

Challenges of Military Health Service Support in Mountain Warfare

INTRODUCTION

History is full of examples of the influence of the mountain environment on warfare. The aim of this article is to identify the main environmental hazards and summarize countermeasures to mitigate the impact of this unique environment.

METHODS

A selective PubMed and Internet search was conducted. Additionally, we searched bibliographies for useful supplemental literature and included the recommendations of the leading mountain medicine and wilderness medicine societies.

RESULTS

A definition of mountain warfare mainly derived from environmental influences on body functions is introduced to help identify the main environmental hazards. Cold, rugged terrain, hypoxic exposure, and often a combination and mutual aggravation of these factors are the most important environmental factors of mountain environment. Underestimating this environmental influence has decreased combat strength and caused thousands of casualties during past conflicts. Some marked differences between military and civilian mountaineering further complicate mission planning and operational sustainability.

CONCLUSIONS

To overcome the restrictions of mountain environments, proper planning and preparation, including sustained mountain mobility training, in-depth mountain medicine training with a special emphasize on prolonged field care, knowledge of acclimatization strategies, adapted time calculations, mountain-specific equipment, air rescue strategies and makeshift evacuation strategies, and thorough personnel selection, are vital to guarantee the best possible medical support. The specifics of managing risks in mountain environments are also critical for civilian rescue missions and humanitarian aid.

Oxygen saturation increases over the course of the night in mountaineers at high altitude (3050-6354 m)

BACKGROUND

Blood oxygen saturation (SpO 2 ) is frequently measured to determine acclimatization status in high-altitude travellers. However, little is known about nocturnal time course of SpO 2 (SpO 2N ), but alterations in SpO 2N might be practically relevant as well. To this end, we describe the time-course of SpO 2N in mountaineers at high altitude.

METHODS

SpO 2N was continuously measured in ten male mountaineers during a three-week expedition in Peru (3,050-6,354m). Average SpO 2N of the first (SpO 2N1 ) and second half (SpO 2N2 ) of an individual's sleep duration was calculated from 2h intervals of uninterrupted sleep. Heart rate oscillations and sleep dairies were used to exclude periods of wakefulness. SpO 2 was also measured at rest in the morning.

RESULTS

SpO 2N significantly increased from SpO 2N1 to SpO 2N2 . The magnitude of this increase (ΔSpO 2 ) was reduced with time spent at altitude. On night 1 (3,050m) SpO 2 increased from 83.4% (N1) to 86.3% (N2). At the same location on night 21, SpO 2 increased from 88.3% to 90.1%, which is a relative change of 4.7% and 2.0%, respectively. This pattern of increase in SpO 2N was perturbed when individual acclimatization was poor or altitude was extreme (5630m). SpO 2N was significantly lower than SpO 2 at rest in the morning.

CONCLUSIONS

This study is the first to demonstrate an increase of SpO 2 during the night in mountaineers at high altitude (3,050-6,354m) with high consistency between and within subjects. The magnitude of ΔSpO 2N decreased as acclimatization improved, suggesting that these changes in ΔSpO 2 between nights might be a valuable indicator of individual acclimatization. In addition, the failure of any increase in SpO 2N during the night might indicate insufficient acclimatization. Even though underlying mechanisms for the nocturnal increase remain unclear, the timing of SpO 2N measurement is obviously of utmost importance for its interpretation. Finally our study illustrates the detailed effects of ventilatory acclimatization over several weeks.

[What Surgeons Should Know about Risk Management]

Background: The fact that medical treatment is associated with errors has long been recognized. Based on the principle of "first do no harm", numerous efforts have since been made to prevent such errors or limit their impact. However, recent statistics show that these measures do not sufficiently prevent grave mistakes with serious consequences. Preventable mistakes such as wrong patient or wrong site surgery still frequently occur in error statistics. Methods: Based on insight from research on human error, in due consideration of recent legislative regulations in Germany, the authors give an overview of the clinical risk management tools needed to identify risks in surgery, analyse their causes, and determine adequate measures to manage those risks depending on their relevance. The use and limitations of critical incident reporting systems (CIRS), safety checklists and crisis resource management (CRM) are highlighted. Also the rationale for IT systems to support the risk management process is addressed. Results/Conclusion: No single tool of risk management can be effective as a standalone instrument, but unfolds its effect only when embedded in a superordinate risk management system, which integrates tailor-made elements to increase patient safety into the workflows of each organisation. Competence in choosing adequate tools, effective IT systems to support the risk management process as well as leadership and commitment to constructive handling of human error are crucial components to establish a safety culture in surgery.

Injuries, Medical Conditions, and Changes in Blood Levels in German Special Operations Forces Selection

BACKGROUND

Medical conditions often develop during military training. The aim of this study was to compile medical conditions and injuries sustained during a 5-day military exercise, compare them with incidences at similar civilian events, and subsequently identify differences between those who finished the exercise (Finishers) and those who did not (Nonfinishers) to identify preventable causes for not finishing and to reduce unnecessary health risks.

METHODS

Fifty-one soldiers had their blood parameters (creatine kinase [CK], aspartate transaminase [AST], alanine transaminase [ALT], gamma-glutamyl transferase [GGT], C-reactive protein [CRP], leukocytes, sodium), weight loss, and body temperature determined after the exercise. Additionally, the injuries and conditions that led the Nonfinishers to drop out were recorded.

RESULTS

The main reasons why Nonfinishers did not complete the exercise were physical exhaustion and minor injuries. After exercise, the Finishers showed only slightly increased incidence of hyponatremia, higher levels of CK, and significantly higher levels of AST, ALT, and CRP, and body weight loss. The Nonfinishers? results were significant for an elevated leukocyte count and lower mean temperatures.

CONCLUSION

The specifics of military training did not influence the kind or the number of exertion-related medical conditions compared to similar civilian events. Both Finishers and Nonfinishers are at risk of developing exertion-related medical conditions such as rhabdomyolysis and hyponatremia. However, plain water did not increase the risk of exertional hyponatremia. Leukocytosis found in the Nonfinisher group could have been due to acute excessive exertion and, therefore, may be an indicator of general systemic fatigue. This could be used to differ between physical and psychological reasons for not finishing.

[Neuromuscular deficits in chronic ankle instability. Frequency and significance - multicenter study]

The peroneal reaction time (PRT) is used in the assessment of neuromuscular deficits in chronic functional ankle instability. Powered by the Editorial Manager and Preprint Manager from Aries Systems Corporation the present study was conducted to determine the PRT in a large collective of patients with chronic ankle instability because it is unclear if this parameter of neuromuscular deficit is prolonged. In this study 186 patients underwent a diagnostic algorithm consisting of anamnesis, clinical examination, X-ray and determination of the PRT on a tilting platform. A prolonged PRT as a manifestation of a neuromuscular deficit could be detected in the majority of the patients (n = 143, 77%). Comparing the affected and healthy legs 77 patients (41%) showed a significant difference in talar shift (p = 0.002) and talar tilt (p = 0.04) in the radiological stress views. Of these 77 patients only 15 (8%) showed radiological evidence of a mechanical problem. As a consequence of recurring ankle sprains a post-traumatic deficit in proprioception has to be expected in most cases. In general a conservative therapy approach should be followed including specific training to improve neuromuscular and proprioceptive deficits.

Decrease of asymmetric dimethylarginine predicts acute mountain sickness

INTRODUCTION

Each year, 40 million tourists worldwide are at risk of getting acute mountain sickness (AMS), because they travel to altitudes of over 2500 m. As asymmetric dimethylarginine (ADMA) is a nitric oxide synthase (NOS) inhibitor, it should increase pulmonary artery pressure (PAP) and raise the risk of acute mountain sickness and high-altitude pulmonary edema (HAPE). With this in mind, we investigated whether changes in ADMA levels (Δ-ADMA) at an altitude of 4000 m can predict an individual's susceptibility to AMS or HAPE.

METHODS

Twelve subjects spent two nights in a hypobaric chamber, the first night without exposure to altitude conditions and the second night at a simulated altitude of 4000 m. At identical time points during both nights (after 2, 5, and 11 hours), we determined ADMA serum levels, PAP by Doppler echocardiography and estimated hypoxia related symptoms by Lake Louise Score (LLS).

RESULTS

Contrary to our initial hypothesis, subjects with a marked increase in ADMA at 4000 m showed PAP levels below the critical threshold for HAPE and were not affected by AMS. By contrast, subjects with a decrease in ADMA suffered from AMS and had PAP levels above 40 mmHg. After 2 hours of hypoxia we found a significant relationship between Δ-PAP t(2) (Spearmans ρ = 0.30, p ≤ 0.05) respectively Δ-ADMA t(2) (ρ = -0.92, p ≤ 0.05) and LLS.

CONCLUSION

After 2 hours of hypoxia, the Δ-ADMA (positive or negative) can predict an LLS of >5 with a sensitivity of 80% and a specificity of 100% and can help assess the risk of an increase in PAP to more than 40 mmHg and thus the risk of HAPE (ϕ coefficient: 0.69; p ≤ 0.05).

[Clinical relevance of a routinely performed magnetic resonance cholangiopancreatography (MRCP) prior to cholecystectomy]

BACKGROUND

A preoperative diagnostic imaging procedure is essential for therapy in cholecystolithiasis. According to the S3-Guidelines of the German Society for General and Visceral Surgery only an ultrasound scan is needed before a cholecystectomy. But an anatomic variant of the bile ducts or choledocholithiasis is poorly shown by an ultrasound. Because of this, we performed a magnetic resonance cholangiopancreatography (MRCP) routinely. This study was designed to show if the MRCP changed the treatment plan or changed the operation method. Furthermore, the sensitivity and specificity concerning abnormalities of the cystic duct, accessory bile ducts and choledocholithiasis should be determined.

PATIENTS AND METHODS

During the time between January 1st 2005 and September 30th 2009 541 patients were included in this retrospective study.

RESULTS

Among the 541 cases 98 pathologies were found. These included 51 choledocholithiasis, 20 accessory bile ducts and 13 abnormal cystic ducts. In 29 of the 51 cases of choledocholithiasis a therapeutic splitting was performed only because of the MRCP. In 22 cases the diagnosis was also possible because of the basic diagnostic procedures like ultrasound, laboratory tests and clinical appearance. So the diagnostic aimprovement due to the MRCP is 5.3 %. Four of the 20 accessory bile ducts and 6 of the abnormal cystic ducts were found during the subsequent operation. The sensitivity concerning the anatomic variants is very low (38.5 % concerning the accessory bile ducts and 50 % for the abnormal cystic ducts). But the sensitivity in detecting a choledocholithiasis is very high (94.7 %). There was no evidence in our study that MRCP prevented any complications. The operation method was not changed in any case because of the MRCP result.

CONCLUSION

A routinely performed preoperative MRCP cannot be recommended.

[Patient assessments of quality of life following bypass for chronic critical limb ischaemia]

The value of infrainguinal bypass surgery for critical limb ischaemia (CLI) in elderly patients is being scrutinised more as medical resources decline. Despite technically successful revascularisation, patient quality of life seems impaired by delayed wound healing and repeated hospitalisation for interventions and operations. Therefore it is questionable whether these frail patients benefit from bypass surgery with respect to their health-related quality of life. This review examines current evidence of patients with CLI and summarises the effect of bypass surgery on their own quality of life assessments. All in all, patients benefit from the revascularisation because ambulation status improves and independence is preserved. From a patient's perspective these improvements in quality of life justify an aggressive approach towards revascularisation for CLI.

EEG, ECG and oxygen concentration changes from sea level to a simulated altitude of 4000m and back to sea level

In order to describe how high altitude affects the body during a one night stay at 4000m experiments were performed in a hypobaric chamber and compared to a study on Dachstein (mountain in Austria, 2700m). Ten subjects had to perform a reaction time task at different altitudes. The EEG and ECG were recorded simultaneously. Additionally, the oxygen saturation of the blood was measured at different altitudes and the subjects filled out a Lake Louise questionnaire that describes the degree of altitude mountain sickness (AMS). After elevation from 134m to 4000m in the hypobaric chamber heart-rate increased from 68.9bpm to 81.6bpm, RMSSD (root mean square of squared differences of adjacent heart beat intervals) decreased from 54.3ms to 33.3ms, the LF/HF ratio increased from 2.5 to 3.9 and oxygen saturation decreased to 82.7% after 11h at 4000m altitude. The Lake Louise Score (LSS) reached 3.4 after one night at 4000m. EEG beta activity between 14Hz and 18Hz was attenuated at 4000m and also after return to 134m. The results indicate that the subjects were not able to adapt to 4000m within 12h in the hypobaric chamber. Even after 1h after the return to 134m all parameters are still affected from the night at 4000m altitude. ECG and EEG changes are in line with results obtained at 2700m height at Dachstein.

[Removal of a thoracic impaling agent without direct observation. The significance of pre-operative diagnosis]

Impalement injuries are uncommon and only occasional reports exist in the literature, resulting in non standardized approaches. Depending on the location, completely different combinations of injuries occur, making every impalement unique. Nevertheless some basic principles for dealing with impalements exist. These principles, and some controversial statements in the literature on the value of preoperative diagnostics, especially CT, are discussed using the example of a spectacular thoracic impalement by a 2 x 2 cm square metal pole. Our deviation from the principal of removing an impaling object only under direct observation in this special case is also discussed.

Oxygen saturation course and altitude symptomatology during an expedition to broad peak (8047 m)

Thirteen healthy European mountaineers (11 male, 2 female) participated in the 62-day German-Pakistani Research Expedition to Broad Peak (8047 m) in the Karakorum, Pakistan. During ascent, base camp stay and approach to the summit, oxygen saturation was measured by pulse oximetry at rest, during exercise and during sleep; in addition, questionnaires on high altitude symptomatic had to be answered. We found a dramatic decrease in oxygen saturation especially at extreme altitudes (7100 m: Median 63%, Min 59%, Max 65%) and a long time required for real acclimatization. The lowest figures at 4850 m were found during maximal exercise, 77.5% (69 - 85%) and during sleep, 81% (73 - 88%), the highest ones at rest, 86.5% (77 - 89%). There was a significant correlation (Spearman rank correlation coefficient with ties) between measured oxygen saturation during the ascent to/stay at base camp and high altitude illness (p = 0.005 - 0.05), as well as with high altitude performance (p = 0.025 - 0.01). The limiting values of "no high altitude symptomatic", "high altitude discomfort", AMS and the malignant forms could be estimated for acclimatized (>90%/>80%/>70%/<70%) and unacclimatized (>80%/>70%/>65%/<65%) condition. Pulse oximetry is an objective non-invasive method of measurement that is easy to handle. It is a suitable device besides clinical examination and questionnaire-test in the diagnosis of high altitude illness even in the hands of non-professionals. The measurement at sleep can possibly explain present high altitude symptomatic despite of (nearly) normal oxygen saturation values at rest.

[Peroneal reaction time: study of a normal sample]

Chronic functional instability is a residual problem after acute ankle sprain. Reasons may be weak ligaments and/or a deficit in the proprioceptive system. Studies have shown that peroneal reaction time (PRT) can be used to quantify proprioceptive performance. To test the influence of anthropometric data on PRT, an experimental study with 120 healthy volunteers was performed. Surface electrodes recorded the activity of the peroneal muscles after a sudden inversion on a tilting platform. It was found that PRT is not influenced by extrinsic or anthropometric data. Furthermore, the results prove a significant slackening in PRT with increasing age. Therefore, the patient's age must to be considered in judging the PRT.

Regulation of extracellular matrix synthesis by mechanical stress

The extracellular matrix (ECM) provides mechanical support to tissues and is a substrate for cell adhesion and differentiation. Cells bind to ECM via specific cell surface receptors such as integrins. When engaging with ECM ligands, these receptors can activate signal transduction pathways within the cells and may act as mechanochemical transducers. Thus, interaction of cells with ECM can modulate gene expression although the exact mechanisms are not known. Among the genes that are, in part, controlled by cell-ECM interactions are those for certain ECM components themselves. Bone cells, for example, remodel their matrix and reorient bone trabeculae in response to mechanical strain. Recently, we found that fibroblasts attached to a strained collagen matrix produce more of the ECM glycoproteins tenascin and collagen XII than cells in a relaxed matrix. In vivo, these two proteins are specifically expressed in places where mechanical strain is high. We also showed that the chick tenascin gene promoter contains a novel cis-acting, "strain-responsive" element that causes enhanced transcription in cells attached to a strained collagen matrix. Similar enhancer elements might be present in the promoters of other genes induced by mechanical stress. It can be speculated that connective tissue cells sense force vectors in their ECM environment and react to altered mechanical needs by regulating the transcription of specific ECM genes; this process is a prerequisite for matrix remodeling.

Tenascin-C expression by fibroblasts is elevated in stressed collagen gels

Chick embryo fibroblasts cultured on a collagen matrix exert tractional forces leading to the contraction of unrestrained, floating collagen gels and to the development of tension in attached, restrained gels. On a restrained, attached collagen gel the fibroblasts synthesize large quantities of tenascin-C, whereas in a floating, contracting gel tenascin-C synthesis is decreased. This regulation of tenascin-C synthesis can be observed by the secretion of metabolically labeled tenascin-C into the conditioned medium, as well as by the deposition of tenascin-C into the collagen matrix as judged by immunofluorescence. Regulation appears to occur at the transcriptional level, because when cells on attached or floating collagen gels are transfected with promoter constructs of the tenascin-C gene, luciferase expression driven by the tenascin-C promoter parallels the effects measured for endogenous tenascin-C synthesis, whereas luciferase expression under the control of the SV40 promoter does not depend on the state of the collagen gel. The promoter region responsible for tenascin-C induction on attached collagen gels is distinct from the region important for the induction of tenascin-C by serum, and may define a novel kind of response element. By joining this tenascin-C sequence to the SV40 promoter of a reporter plasmid, its activity can be transferred to the heterologous promoter. We propose that the tenascin-C promoter is directly or indirectly activated in fibroblasts generating and experiencing mechanical stress within a restrained collagen matrix. This may be an important aspect of the regulation of tenascin-C expression during embryogenesis as well as during wound healing and other regenerative and morphogenetic processes.

Identification of the murine cytomegalovirus glycoprotein B gene and its expression by recombinant vaccinia virus

The gene encoding glycoprotein B (gB) of murine cytomegalovirus (MCMV) strain Smith was identified, sequenced, and expressed by recombinant vaccinia virus. The gB gene was found adjacent to the polymerase gene, as it is in the genome of human cytomegalovirus (HCMV). The open reading frame consists of 2,784 nucleotides capable of encoding a protein of 928 amino acids. Comparison with gB homologs of other herpesviruses revealed a high degree of homology. The similarity between the MCMV gB and the HCMV gB is most prominent, since 45% of the amino acids are identical. In addition, all cysteine residues are at homologous positions, indicating a similar tertiary structure of the two proteins. In contrast to HCMV, the MCMV gB mRNA is a true late transcript. A recombinant vaccinia virus expressing the MCMV gB gene has been constructed (Vac-gB). Antibodies raised against the Vac-gB recombinant precipitated proteins of 130, 105, and 52 kDa from MCMV-infected cells. The identity of the MCMV gB with the major envelope glycoprotein of MCMV described by Loh et al. was shown (L. C. Loh, N. Balachandran, and L. F. Qualtiere, Virology 166:206-216, 1988). Immunization of mice with the Vac-gB recombinant gave rise to neutralizing antibodies.