Severity of oEsophageal Anastomotic Leak in patients after oesophagectomy: the SEAL score

Background

Anastomotic leak (AL) is a common but severe complication after oesophagectomy. It is unknown how to determine the severity of AL objectively at diagnosis. Determining leak severity may guide treatment decisions and improve future research. This study aimed to identify leak-related prognostic factors for mortality, and to develop a Severity of oEsophageal Anastomotic Leak (SEAL) score.

Methods

This international, retrospective cohort study in 71 centres worldwide included patients with AL after oesophagectomy between 2011 and 2019. The primary endpoint was 90-day mortality. Leak-related prognostic factors were identified after adjusting for confounders and were included in multivariable logistic regression to develop the SEAL score. Four classes of leak severity (mild, moderate, severe, and critical) were defined based on the risk of 90-day mortality, and the score was validated internally.

Results

Some 1509 patients with AL were included and the 90-day mortality rate was 11.7 per cent. Twelve leak-related prognostic factors were included in the SEAL score. The score showed good calibration and discrimination (c-index 0.77, 95 per cent c.i. 0.73 to 0.81). Higher classes of leak severity graded by the SEAL score were associated with a significant increase in duration of ICU stay, healing time, Comprehensive Complication Index score, and Esophagectomy Complications Consensus Group classification.

Conclusion

The SEAL score grades leak severity into four classes by combining 12 leak-related predictors and can be used to the assess severity of AL after oesophagectomy.

Clinical Relevance of the Tumor Location-Modified Laurén Classification System for Gastric Cancer in a Western Population

Background

The Tumor Location-Modified Laurén Classification (MLC) system combines Laurén histologic subtype and anatomic tumor location. It divides gastric tumors into proximal non-diffuse (PND), distal non-diffuse (DND), and diffuse (D) types. The optimum classification of patients with Laurén mixed tumors in this system is not clear due to its grouping with both diffuse and non-diffuse types in previous studies. The clinical relevance of the MLC in a Western population has not been examined.

Methods

A cohort study investigated 404 patients who underwent gastrectomy for gastric adenocarcinoma between 2005 and 2020. The classification of Laurén mixed tumors was evaluated using receiver operating characteristic (ROC) curve analysis and comparison of clinicopathologic characteristics (chi-square). Survival analysis was performed using multivariable Cox regression.

Results

The ROC curve analysis demonstrated a slightly higher area under the curve value for predicting survival when Laurén mixed tumors were grouped with intestinal-type rather than diffuse-type tumors (0.58 vs 0.57). Survival, tumor recurrence, and resection margin positivity in mixed tumors also was more similar to intestinal type. Distal non-diffuse tumors had the best 5-year survival (DND 64.7 % vs PND 56.1 % vs diffuse 45.1 %; p = 0.006) and were least likely to have recurrence (DND 27.0 % vs PND 34.3 % vs diffuse 48.3 %; p = 0.001). Multivariable analysis demonstrated that MLC was an independent prognostic factor for survival (PND: hazard ratio [HR], 1.64; 95 % confidence interval [CI], 1.16–2.32 vs diffuse: HR, 2.20; 95 % CI, 1.56–3.09)

Conclusions

The MLC was an independent prognostic marker in this Western cohort of patients with gastric adenocarcinoma. The patients with PND and D tumors had worse survival than those with DND tumors.

Supplementary Information

The online version contains supplementary material available at 10.1245/s10434-021-11252-y.

Adjuvant therapy following oesophagectomy for adenocarcinoma in patients with a positive resection margin

BACKGROUND

The role of adjuvant therapy in patients with oesophagogastric adenocarcinoma treated by neoadjuvant chemotherapy is contentious. In UK practice, surgical resection margin status is often used to classify patients for receiving adjuvant treatment. The aim of this study was to assess the survival benefit of adjuvant therapy in patients with positive (R1) resection margins.

METHODS

Two prospectively collected UK institutional databases were combined to identify eligible patients. Adjusted Cox regression analyses were used to compare overall and recurrence-free survival according to adjuvant treatment. Recurrence patterns were assessed as a secondary outcome. Propensity score-matched analysis was also performed.

RESULTS

Of 616 patients included in the combined database, 242 patients who had an R1 resection were included in the study. Of these, 112 patients (46·3 per cent) received adjuvant chemoradiotherapy, 46 (19·0 per cent) were treated with adjuvant chemotherapy and 84 (34·7 per cent) had no adjuvant treatment. In adjusted analysis, adjuvant chemoradiotherapy improved recurrence-free survival (hazard ratio (HR) 0·59, 95 per cent c.i. 0·38 to 0·94; P = 0·026), with a benefit in terms of both local (HR 0·48, 0·24 to 0·99; P = 0·047) and systemic (HR 0·56, 0·33 to 0·94; P = 0·027) recurrence. In analyses stratified by tumour response to neoadjuvant chemotherapy, non-responders (Mandard tumour regression grade 4-5) treated with adjuvant chemoradiotherapy had an overall survival benefit (HR 0·61, 0·38 to 0·97; P = 0·037). In propensity score-matched analysis, an overall survival benefit (HR 0·62, 0·39 to 0·98; P = 0·042) and recurrence-free survival benefit (HR 0·51, 0·30 to 0·87; P = 0·004) were observed for adjuvant chemoradiotherapy versus no adjuvant treatment.

CONCLUSION

Adjuvant therapy may improve overall survival and recurrence-free survival after margin-positive resection. This pattern seems most pronounced with adjuvant chemoradiotherapy in non-responders to neoadjuvant chemotherapy.

Prediction of a positive circumferential resection margin at surgery following neoadjuvant chemotherapy for adenocarcinoma of the oesophagus

Background

A positive circumferential resection margin (CRM) has been associated with higher rates of locoregional recurrence and worse survival in oesophageal cancer. The aim of this study was to establish if clinicopathological and radiological variables might predict CRM positivity in patients who received neoadjuvant chemotherapy before surgery for oesophageal adenocarcinoma.

Methods

Multivariable analysis of clinicopathological and CT imaging characteristics considered potentially predictive of CRM was performed at initial staging and following neoadjuvant chemotherapy. Prediction models were constructed. The area under the curve (AUC) with 95% confidence intervals (c.i.) from 1000 bootstrapping was assessed.

Results

A total of 223 patients were included in the study. Poor differentiation (odds ratio (OR) 2·84, 95 per cent c.i. 1·39 to 6·01) and advanced clinical tumour status (T3-4) (OR 2·93, 1·03 to 9·48) were independently associated with an increased CRM risk at diagnosis. CT-assessed lack of response (stable or progressive disease) following chemotherapy independently corresponded with an increased risk of CRM positivity (OR 3·38, 1·43 to 8·50). Additional CT evidence of local invasion and higher CT tumour volume (14 cm3) improved the performance of a prediction model, including all the above parameters, with an AUC (c-index) of 0·76 (0·67 to 0·83). Variables associated with significantly higher rates of locoregional recurrence were pN status (P = 0·020), lymphovascular invasion (P = 0·007) and poor response to chemotherapy (Mandard score 4-5) (P = 0·006). CRM positivity was associated with a higher locoregional recurrence rate, but this was not statistically significant (P = 0·092).

Conclusion

The presence of advanced cT status, poor tumour differentiation, and CT-assessed lack of response to chemotherapy, higher tumour volume and local invasion can be used to identify patients at risk of a positive CRM following neoadjuvant chemotherapy.

Lymph node regression and survival following neoadjuvant chemotherapy in oesophageal adenocarcinoma

BACKGROUND

The aim was to define the pathological response in lymph nodes following neoadjuvant chemotherapy for oesophageal adenocarcinoma and to quantify any associated survival benefit.

METHODS

Lymph nodes retrieved at oesophagectomy were examined retrospectively by two pathologists for evidence of a response to chemotherapy. Patients were classified as lymph node-negative (either negative nodes with no evidence of previous tumour involvement or negative with evidence of complete regression) or positive (allocated a lymph node regression score based on the proportion of fibrosis to residual tumour). Lymph node responders (score 1, complete response; 2, less than 10 per cent remaining tumour; 3, 10-50 per cent remaining tumour) and non-responders (score 4, more than 50 per cent viable tumour; 5, no response) were compared in survival analyses using Kaplan-Meier and Cox regression analysis.

RESULTS

Among 377 patients, 256 had neoadjuvant chemotherapy. Overall, 68 of 256 patients (26·6 per cent) had a lymph node response and 115 (44·9 per cent) did not. The remaining 73 patients (28·5 per cent) had negative lymph nodes with no evidence of regression. Some patients had a lymph node response in the absence of a response in the primary tumour (27 of 99, 27 per cent). Lymph node responders had a significant survival benefit (P < 0·001), even when stratified by patients with or without a response in the primary tumour. On multivariable analysis, lymph node responders had decreased overall (hazard ratio 0·53, 95 per cent c.i. 0·36 to 0·78) and disease-specific (HR 0·42, 0·27 to 0·66) mortality, and experienced reduced local and systemic recurrence.

CONCLUSION

Lymph node regression is a strong prognostic factor and may be more important than response in the primary tumour.

Impact of incremental circumferential resection margin distance on overall survival and recurrence in oesophageal adenocarcinoma

Background

Previous analyses of the oesophageal circumferential resection margin (CRM) have focused on the prognostic validity of two different definitions of a positive CRM, that of the College of American Pathologists (tumour at margin) and that of the Royal College of Pathologists (tumour within 1 mm). This study aimed to analyse the validity of these definitions and explore the risk of recurrence and survival with incremental tumour distances from the CRM.

Methods

This cohort study included patients who underwent resection for adenocarcinoma of the oesophagus between 2000 and 2014. Kaplan-Meier and Cox regression analyses were performed to determine the hazard ratio (HR) with 95 per cent confidence intervals for recurrence and mortality in CRM increments: tumour at the cut margin, extending to within 0·1-0·9, 1·0-1·9, 2·0-4·9 mm, and 5·0 mm or more from the margin.

Results

A total of 444 patients were included in the study. Kaplan-Meier and unadjusted analyses showed a significant incremental improvement in overall survival (P < 0·001) and recurrence (P for trend < 0·001) rates with increasing distance from the CRM. Tumour distance of 2·0 mm or more remained a significant predictor of survival on multivariable analysis (HR for risk of death 0·66, 95 per cent c.i. 0·44 to 1·00). Multivariable analysis of overall survival demonstrated a significant difference between a positive and negative CRM with the Royal College of Pathologists' definition (HR 1·37, 1·01 to 1·85), but not with the College of American Pathologists' definition (HR 1·22, 0·90 to 1·65).

Conclusion

This study demonstrated an incremental improvement in survival and recurrence rates with increasing tumour distance from the CRM.

Patterns of recurrence in oesophageal cancer following oesophagectomy in the era of neoadjuvant chemotherapy

Background

Tumour recurrence following oesophagectomy for oesophageal cancer is common despite neoadjuvant treatment. Understanding patterns of recurrence and risk factors associated with locoregional and systemic recurrence might influence future treatment strategies.

Methods

This was a cohort study involving patients undergoing resection for adenocarcinoma or squamous cell carcinoma of the oesophagus between 2000 and 2014. Clinicopathological factors associated with locoregional and systemic recurrence were analysed using multivariable logistic regression to determine odds ratios (ORs) and 95 per cent confidence intervals.

Results

Some 698 patients were identified. Lymphovascular invasion (OR 2·09, 95 per cent c.i. 1·18 to 3·71) and preoperative stenting (OR 3·70, 1·34 to 10·23) were independent risk factors for isolated locoregional recurrence. Pathological nodal disease in patients with pT1–2 (pN1: OR 2·72, 1·35 to 5·48; pN2–3: OR 5·00, 2·35 to 10·66) or pT3–4 (pN1: OR 3·03, 1·51 to 6·07; pN2–3: OR 5·75, 3·15 to 10·49) disease predisposed to systemic recurrence. Poor or no response to chemotherapy was also an independent risk factor for isolated systemic recurrence (OR 1·85, 1·05 to 3·26). A positive resection margin (R1 resection) was not associated with a significantly increased risk of isolated locoregional recurrence (OR 1·37, 0·81 to 2·33).

Conclusion

These findings confirm that oesophageal adenocarcinoma is frequently a systemic disease. Understanding the key predictors of local and systemic recurrence may facilitate the tailoring of oncological therapies to the individual patient.

A comparison of the left thoracoabdominal and Ivor-Lewis esophagectomy

The purpose of this study was to assess the oncological outcomes of a large multicenter series of left thoracoabdominal esophagectomies, and compare these to the more widely utilized Ivor-Lewis esophagectomy. With ethics approval and an established study protocol, anonymized data from five centers were merged into a structured database. The study exposure was operative approach (ILE or LTE). The primary outcome measure was time to death. Secondary outcome measures included time to tumor recurrence, positive surgical resection margins, lymph node yield, postoperative death, and hospital length of stay. Cox proportional hazards models provided hazard ratios (HR) with 95% confidence intervals (CI) adjusting for age, pathological tumor stage, tumor grade, lymphovascular invasion, and neoadjuvant treatment. Among 1228 patients (598 ILE; 630 LTE), most (86%) had adenocarcinoma (AC) and were male (81%). Comparing ILE and LTE for AC patients, no difference was seen in terms of time to death (HR 0.904 95%CI 0.749-1.1090) or time to recurrence (HR 0.973 95%CI 0.768-1.232). The risk of a positive resection margin was also similar (OR 1.022 95%CI 0.731-1.429). Median lymph node yield did not differ between approaches (LTE 21; ILE 21; P = 0.426). In-hospital mortality was 2.4%, significantly lower in the LTE group (LTE 1.3%; ILE 3.6%; P = 0.004). Median hospital stay was 11 days in the LTE group and 14 days in the ILE group (P < 0.0001). In conclusion, this is the largest series of left thoracoabdominal esophagectomies to be submitted for publication and the only one to compare two different transthoracic esophagectomy strategies. It demonstrates oncological equivalence between operative approaches but possible short- term advantages to the left thoracoabdominal esophagectomy.

Mechanistic modelling of radiotherapy-induced lung toxicity

OBJECTIVE

This work explores the biological basis of a mechanistic model of radiation-induced lung damage; uniquely, the model makes a connection between the cellular radiobiology involved in lung irradiation and the full three-dimensional distribution of radiation dose.

METHODS

Local tissue damage and loss of global organ function, in terms of radiation pneumonitis (RP), were modelled as different levels of radiation injury. Parameters relating to the former could be derived from the local dose-response function, and the latter from the volume effect of the organ. The literature was consulted to derive information on a threshold dose and volume-effect mechanisms.

RESULTS

Simulations of local tissue damage supported the alveolus as a functional subunit (FSU) which can be regenerated from a single surviving stem cell. A moderate interpatient variation in stem cell radiosensitivity (15%) resulted in a great variation in tissue response between 8 and 20 Gy. The threshold of FSU inactivation within a critical functioning volume leading to RP was found to be approximately 47% and the degree of health status variation (influencing the volume effect) in a population was estimated at 25%.

CONCLUSION

This work has shown that it is possible to make sense of the way the lung responds to radiation by modelling RP mechanistically, from cell death to tissue damage to loss of organ function.

ADVANCES IN KNOWLEDGE

Simulations were able to provide parameter values, currently not available in the literature, related to the response of the lung to irradiation.

Impact of a multidisciplinary standardized clinical pathway on perioperative outcomes in patients with oesophageal cancer

Background

Defined clinical pathways can contribute to improved outcomes in patients undergoing oesophageal cancer surgery. A standardized oesophagectomy clinical pathway (SOCP) established at the Virginia Mason Medical Center (VMMC) in Seattle, Washington, USA was introduced into the Royal Surrey County Hospital (RSCH), Guildford, UK in 2011. The aim of this study was to see whether transfer and implementation of an oesophagectomy care pathway could change postoperative outcomes significantly.

Methods

Three consecutively accrued study groups were examined at the RSCH: patients operated on immediately before the introduction of the SOCP (group 1), patients operated on after the introduction of the SOCP but not included in the pathway (group 2), and patients managed according to the SOCP (group 3). Outcomes were compared with those of patients who had surgery at the VMMC between 2009 and 2011 using the SOCP (group 4).

Results

There were 12 patients in each of the first three groups and 74 in group 4. All groups were similar with respect to body mass index, medical co-morbidities and clinical stage. The median age of patients in group 3 was significantly lower than that in group 1, and median American Society of Anesthesiologists score was significantly better in group 3 compared with group 4. Following initiation of the SOCP there was an increase in immediate extubation (8 of 12 in group 1 versus 12 of 12 in group 3) and first-day mobilization (1 of 12 versus 12 of 12 respectively), and a reduction in complications (9 of 12 versus 4 of 12), length of critical care stay (4 (range 2–20) days in group 1 versus 3 (1–5) days in group 3) and length of hospital stay (17 (12–30) to 7 (6–37) days respectively). Patients not on the pathway but who had surgery during the same interval experienced small but non-significant improvements in length of critical care and hospital stay, and in first-day mobilization.

Conclusion

The study demonstrated improvement in short-term outcomes after oesophagectomy following the adoption of an established multidisciplinary standardized postoperative pathway.

Corticosterone levels of Atlantic puffins vary with breeding stage and sex but are not elevated in poor foraging years

Corticosterone (CORT) levels in seabirds fluctuate across breeding stages and in different foraging conditions. Here we use a ten-year data set to examine whether CORT levels in Atlantic puffins differ in years with high or low availability of capelin, the preferred forage species. Female puffins had higher CORT levels than males, possibly related to cumulative costs of egg production and higher parental investment. Puffins had higher CORT levels and body mass during pre-breeding than during chick rearing. Yearly mean chick growth rates were higher in years when adults had higher body mass and in years where adults brought chicks a lower percentage of non-fish (invertebrates/larval fish) food. Unlike most results from seabird species with shorter chick-rearing periods, higher CORT levels in puffins were not associated with lower capelin abundance. Puffins may suppress CORT levels to conserve energy in case foraging conditions improve later in the prolonged chick-rearing period. Alternatively, CORT levels may be lowest both when food is very abundant (years not in our sample) or very scarce (e.g., 2009 in this study), and increase when extra foraging effort will increase foraging efficiency (most years in this study). If these data primarily represent years with medium to poor foraging, it is possible that CORT responses to variation in foraging conditions are similar for puffins and other seabirds.

Cognitive behavioural therapy as a potential treatment for vasovagal/neurocardiogenic syncope--a pilot study

Vasovagal syncope (VVS) is an exaggerated tendency to the common faint that affects any age group. Conventional treatment is non-specific and involves strategies to increase blood pressure. Patients with VVS are often unable to work or complete education due to actual, or fear of, syncopal symptoms. Here we present a series of nine patients with VVS whose symptoms had proved resistant to conventional treatments where intervention with cognitive behavioural therapy (CBT) led to significant reductions in reported syncopal episodes and consultations at our unit. All subjects post-intervention were able to return to work or schooling. CBT is an effective treatment in those with difficult to manage VVS. Randomized controlled trials are needed.

Arterial elastic properties and cardiovascular risk/event

Cardiovascular disease is a major cause of morbidity and mortality in the western world. There is convincing evidence that the elastic properties, particularly of large arteries, are impaired in the presence of cardiovascular disease and risk factors such as cigarette smoking, hypertension, diabetes and ageing. Evidence is also emerging that treatment of these risk factors is associated with an improvement in the elastic properties, mirrored by a reduction in the cardiovascular risk and events. The main problems associated with arterial elasticity are the multiple definitions and methods of measurement and the problem of obtaining reliable nearby blood pressure measurement. Nevertheless, duplex estimation appears to be a non-invasive, accurate and reliable method of defining these properties. This method is broadly used as a research tool, but there is a good case for its use in clinical practice, particularly in the screening of patients at risk of cardiovascular events.

Absorbed dose behind eye shields during kilovoltage photon radiotherapy

The absorbed dose at the position of the lens of the eye under lead or tungsten eye shields during kilovoltage photon radiotherapy is critically dependent not so much on the thickness of the eye shield itself as on the size of the treatment field and the diameter of the shield used. Whilst dose from primary photons is easily attenuated to relatively insignificant levels by a few millimetres of lead or tungsten, scattered photons from outside the shielded area can provide over 25% of the prescribed dose. Since backscatter factors do not increase monotonically with photon energy, it is not safe to assume that the highest photon energy used will provide the highest dose. A simple method to estimate the dose under an eye shield based on tabulated backscatter factors is shown. Measurements under commercially available eye shields were made to verify the expression and to determine the attenuation of primary photons. Predicted and measured absorbed dose under the eye shields were found to agree to within 1% of the prescribed dose. The relative dose due to primary photons beneath the eye shields was found to be less than 0.1% and 0.5 (+/-0.1)% for the 150 kV and 260 kV beams, respectively. This is considerably less than the dose from backscattered radiation.

How much surplus capacity is required to maintain low waiting times?

Random fluctuations in demand make it impossible to see all patients in a very short time scale unless capacity exceeds the mean demand. We describe a model to estimate the capacity levels required as a function of mean demand. Random fluctuations were assumed to follow a Poisson distribution. A Monte Carlo analysis was used to model variations in length of waiting times. To see patients without a waiting list the capacity must exceed mean demand by an amount proportional to the square root of the mean; if capacity equals mean demand, then actual demand will exceed capacity almost half the time. The smaller the mean demand, the greater the percentage increase in capacity that is required. Thus, subdivision of numbers, for subspecialization or fast-tracking, demands greater overall capacity. When multiple serial steps are required, each step must have spare capacity if a waiting list is to be avoided. When capacity is only slightly greater than mean demand, random fluctuations mean that targets can be met for long stretches of time, but these are interspersed with periods when the waiting list rises substantially. Allowing a small waiting time (2-4 weeks) considerably reduces the excess capacity required. Targets such as the 2-week wait for cancer referrals can be achieved only if resource levels are set to give considerably more patient slots per week than mean demand. The level of spare capacity required depends on the level of demand and the maximum waiting time permitted. Without surplus capacity, waiting targets cannot be met. To meet the 2-week waiting target, capacity must exceed mean demand by two patient slots per week for 99% success, or by one slot per week for 90% success.

Specificity of a new lipid mediator produced by testicular and peritoneal macrophages on steroidogenesis

Macrophage-derived factor (MDF) is a lipophilic factor produced by rat testicular and peritoneal macrophages that maximally stimulates testosterone production by rat Leydig cells through a steroidogenic acute regulatory protein independent mechanism. The purpose of the present study was to determine whether MDF is also produced by human macrophages, and/or if it acts on human steroidogenic cells. We also studied the tissue-specific functions of MDF by determining if it also acts on steroidogenic cells of the ovary and adrenal glands and, if so, does it require new protein synthesis. It was found that MDF was produced by human peritoneal macrophages, and was capable of stimulating human steroidogenic cells. In terms of tissue specificity, it was found that primary cultures of rat adrenocortical cells respond to MDF with increased secretion of aldosterone and corticosterone, as did rat granulosa cells by producing progesterone. MDF acted in the presence of cycloheximide, indicating that it does not require new protein synthesis. These results indicate that MDF may have significant therapeutic potential and provide a basis for future studies concerning its physiological role in humans. These results further suggest that MDF is not only involved in paracrine regulation of Leydig cells, but also has the potential for the local regulation of steroidogenesis in both granulosa and adrenal cortical cells.

Breast cancer treatment

Nurse practitioners must be aware of the standard treatments for breast cancer whether they are referring a symptomatic patient to a breast cancer specialist, are involved in the actual treatment process, or are providing ongoing care for patients after completion of therapy. This article reviews the major treatments for breast cancer including surgery, radiation, and chemotherapy, with greater emphasis on treatment of early-stage disease.

Bradykinin metabolism in perfused rat kidney

The purpose of this study was to assess the capacity of perfused rat kidney to inactivate bradykinin (BK), and to compare the BK degrading capacity of rat kidney with the BK degrading capacities of rat lung, liver, and skeletal muscle, which was approximated by perfusion of rat hind limbs. Radioactively labeled BK, with the Pro2 and Pro3 residues having been tritiated, in an asanguinous salt solution was perfused through the kidney of the rat, over a concentration range of .0028-33 microM. Rat kidney had a large capacity to degrade BK and the system did not appear to approach saturation until perfusate BK concentrations reached 24 microM. A least-squares linear regression analysis and extrapolation to zero concentration was used to obtain values for amounts of BK degraded and BK fragments formed. The amount of BK cleaved was 99.9% of the administered dose. The major tritiated BK fragments formed, and the amount of each expressed as a percentage of the amount of BK degraded during transrenal passage, were the amino acid proline derived from the Pro2 and/or Pro3 residues of BK (Pro2,3), 60%; Pro-Pro (BK 2-3), 12%; Arg-Pro-Pro-Gly-Phe (BK 1-5), 14%; and Arg-Pro-Pro-Gly-Phe-Ser-Pro (BK 1-7), 14%. The formation of BK 2-3 is indicative of initial aminopeptidase-P cleavage of BK to yield Arg, and des-Arg1-BK. Thus in rat kidney the aminopeptidase-P pathway is the major route for BK degradation, as is the case in rat liver.

Bradykinin metabolism in rat hind limbs

The purpose of this study was to assess the capacity of perfused rat hind limbs, the majority of which is skeletal muscle, to inactivate bradykinin (BK), and to compare the BK degrading capacity of rat hind limbs with the BK degrading capacities of rat lung and liver. BK, with tritiated Pro2 and Pro3 residues, in an asanguinous salt solution was perfused for a single passage through skeletal muscle and other tissues in the hind legs of the rat over a concentration range of .0029 to 49.3 microM. Rat hind limbs had a large capacity to degrade BK and the system did not approach saturation, even at 49.3 microM. A least-squares linear regression analysis and extrapolation to zero concentration was used to obtain values for amounts of BK degraded and BK fragments formed. The amount of BK cleaved was 95% of the administered dose. The major BK fragments formed, and the amount of each expressed as a percentage of the amount of BK degraded were Pro-Pro (BK 2-3), 8.6%; Arg-Pro-Pro-Gly-Phe (BK 1-5), 82%; and Arg-Pro-Pro-Gly-Phe-Ser-Pro (BK 1-7), 6%. The BK 1-5 yield was reduced from 82% to one-fourth of that by angiotensin converting enzyme (ACE) inhibitors. BK 2-3 formation is indicative of initial aminopeptidase-P cleavage of BK to yield Arg, and des-Arg1-BK. ACE inhibitor sensitive formation of BK 1-5 is indicative of initial kininase-II, also known as ACE, cleavage of BK. Thus in rat hind limbs, the ACE pathway is the preponderant mechanism for BK degradation, which is in contrast to our previously published reports that in rat liver the amino-peptidase-P pathway predominates, and that in rat lung both the aminopeptidase-P pathway and the ACE pathway exhibit nearly equal capacities to degrade BK.

Reconstruction of 6 MV photon spectra from measured transmission including maximum energy estimation

Photon spectra from a nominally 6 MV beam under standard clinical conditions and at higher and lower beam qualities have been derived from narrow-beam transmission measurements using a previously published three-parameter reconstruction model. Estimates of the maximum photon energy present in each spectrum were derived using a reduced number of model parameters. An estimate of the maximum contribution of background, or room, scatter to transmission measurements has been made for this study and is shown to be negligible in terms of the quality index and percentage depth-dose of the derived spectra. Percentage depth-dose data for standard beam conditions derived from the reconstructed spectrum were found to agree with direct measurements to within approximately 1% for depths of up to 25 cm in water. Quality indices expressed in terms of TPR10(20) for all spectra were found to agree with directly measured values to within 1%. The experimental procedure and reconstruction model are therefore shown to produce photon spectra whose derived quality indices and percentage depth-dose values agree with direct measurement to within expected experimental uncertainty.

Bradykinin metabolism in the liver and lung of the rat

Bradykinin (BK) in an asanguinous salt solution was perfused through intact rat liver. The perfusate was delivered through the portal vein and was collected from the inferior vena cava. BK concentrations varied from 0.0030 to 38.0 microm. The liver had a large capacity to degrade BK and the system did not approach saturation until perfusate BK concentrations reached 60 microm. The quantitatively predominant BK fragments formed and the amount of each formed, expressed as a percentage of the BK degraded during a single transhepatic passage, were Pro-Pro, 74%; Arg-Pro-Pro-Gly-Phe, 15%; and Arg-Pro-Pro-Gly-Phe-Ser-Pro, 7%; the first is indicative of initial aminopeptidase-P cleavage of BK to yield Arg and des-Arg1-BK and the latter two are indicative of initial angiotension converting enzyme (ACE) cleavage of BK. On the other hand, while the perfused rat lung also had a large capacity to degrade BK, the quantitatively predominant BK fragments formed and the amount of each formed, again expressed as a percentage of BK metabolized during a single transpulmonary passage, were Pro-Pro, 47%; Arg-Pro-Pro-Gly-Phe, 35%; and Arg-Pro-Pro-Gly-Phe-Ser-Pro, 7%. Thus in rat liver the aminopeptidase-P pathway is the major route for BK degradation, whereas in rat lung the aminopeptidase-P and the ACE pathways exhibit nearly equal capacities to degrade BK.

Reflective Learning: A Teaching Strategy for Critical Thinking

Most nurse educators claim that ability to critique one's clinical practice is a skill which must be acquired if nursing students are to continue to learn and develop as practitioners after they have graduated. This skill is of particular relevance for nurses who will be working independently in the community. The author reviews recent literature on critical thinking and reflective learning and identifies the results of one baccalaureate nursing school's use of reflective journals.

The effect of smoke inhalation on bradykinin metabolism by the perfused and ventilated rat lung

The effect of smoke inhalation on bradykinin metabolism was studied in the rat lung perfused with Ringer's bicarbonate solution. After smoke (from cotton, polyester, or seat cushion material) inhalation, tritium-labeled bradykinin was added to the Ringer's bicarbonate solution, and then the lung perfusion effluent aliquots containing bradykinin and its metabolic fragments were collected after a single transpulmonary passage. For the 20 control rats without smoke inhalation, 91% of the bradykinin dose was metabolized, with Pro-Pro (I), 49%, and Arg-Pro-Pro-Gly-Phe (II), 32%, being the predominant bradykinin cleavage fragments. For 12 rats with smoke inhalation, 89% of the bradykinin dose was metabolized, with I (28%) and II (36%) being the major bradykinin cleavage fragments. The type of smoke did not significantly alter the capacity of the rat lung to metabolize bradykinin. Exposure to smoke from seat cushion material for more than 3 minutes caused pulmonary edema and thickening, and smoke exposure for more than 5 minutes caused loss of integrity at the lung alveolar-capillary interface. In contrast, exposure to cotton or polyester smoke did not cause any observable gross changes of the lung. Electron microscopic examination of lung exposed to seat cushion material smoke revealed considerable damage, with the type I epithelium existing as patches on the alveolar surface and capillary endothelium separated from the basement lamina. Thus in our model acute, short-term inhalation of smoke did not significantly alter the amount of bradykinin metabolized by the pulmonary endothelium so long as the integrity of the lung alveolar-capillary interface was maintained, although there seemed to be a moderate shift in the amount of major cleavage fragments from I to II.

Reconstruction of megavoltage photon spectra by attenuation analysis

A simple analytical model for reconstructing photon spectra from the indirect measurement of transmission or depth-dose curves is presented, based on the Schiff expression for forward-directed bremsstrahlung differential in photon energy with added inherent filtration. Calculated transmission curves for 21 simulated and measured bremsstrahlung spectra with maximum photon energies in the range 4 to 30 MeV covering a broad range of filtration conditions were used to assess the model's ability to represent megavoltage spectra. Input data were reproduced to within 0.1 per cent in all cases, which is the same order of magnitude as the uncertainty involved in its calculation. Inclusion of a fourth parameter in the model is shown to allow the effective maximum photon energy present in the spectrum to be derived to an accuracy of approximately 3 per cent.

A comparison of Xeroform and SkinTemp dressings in the healing of skin graft donor sites

The best donor site dressing would minimize pain while it increased the rate of healing. This study compares a standard fine-mesh gauze dressing, Xeroform (Sherwood Medical Industries Ltd., Markham, Ontario, Canada), to a new collagen-based dressing, SkinTemp (BioCore Inc., Topeka, Kan.). Eight patients requiring two donor sites of equal size received Xeroform gauze on one site and SkinTemp on the other. The Xeroform was covered for 24 hours and was then allowed to air-dry. Healing was determined to be complete once the gauze peeled off and complete epithelialization was observed. The SkinTemp was covered for 7 days and inspected on days 3, 5, and 7. Pain was measured daily with a standard visual analog scale. Mean Xeroform donor site size was 224.75 cm2, and SkinTemp size was 319.87 cm2. Donor site thickness was 0.012 to 0.014 inches for both. Mean length of healing was 10.62 days for Xeroform and 7.75 days for SkinTemp. Mean pain rating was 22.28 mm for Xeroform and 15.29 mm for SkinTemp. The overall preference of the eight subjects yielded five choosing SkinTemp and three choosing Xeroform, and seven reported SkinTemp as less painful. SkinTemp dressing appears to be less painful and has a better healing rate compared with Xeroform.

Kinin metabolism in the perfused ventilated rat lung. II: Influence of ventilation, perfusion, and perfusate composition variation on bradykinin metabolism in uninjured lung

Bradykinin metabolism by peptidases of the pulmonary endothelium has been investigated in the previously uninjured, ventilated, and asanguinously perfused rat lung. The influence of short-duration (up to 20 min) abnormal ventilation and perfusion conditions on bradykinin metabolism was assessed. Neither variation of the oxygen concentration (0 to 45%) nor omission of carbon dioxide in the ventilatory gas altered bradykinin metabolism significantly. Tidal volume variation did not alter bradykinin metabolism, and exclusion of one lung from the perfusion circuit reduced the capacity to degrade bradykinin proportionately. Acidification of the perfusion medium to pH 5 did not alter bradykinin metabolism. Acetylsalicylic acid in the perfusate protected the lung from an otherwise irreversible pressure increase associated with high-dose bradykinin perfusion. Endotoxin and hydrogen peroxide in the perfusate did not alter bradykinin metabolism. However, ammonia in the ventilatory gas caused immediate pulmonary edema, diminished lung capacity to metabolize bradykinin and altered the pattern of bradykinin metabolic products. The pulmonary endothelium itself, in the absence of blood, maintains its capacity to metabolize bradykinin under an extraordinary range of conditions.

Case-mix groups for VA hospital-based home care

The purpose of this study is to group hospital-based home care (HBHC) patients homogeneously by their characteristics with respect to cost of care to develop alternative case mix methods for management and reimbursement (allocation) purposes. Six Veterans Affairs (VA) HBHC programs in Fiscal Year (FY) 1986 that maximized patient, program, and regional variation were selected, all of which agreed to participate. All HBHC patients active in each program on October 1, 1987, in addition to all new admissions through September 30, 1988 (FY88), comprised the sample of 874 unique patients. Statistical methods include the use of classification and regression trees (CART software: Statistical Software; Lafayette, CA), analysis of variance, and multiple linear regression techniques. The resulting algorithm is a three-factor model that explains 20% of the cost variance (R2 = 20%, with a cross validation R2 of 12%). Similar classifications such as the RUG-II, which is utilized for VA nursing home and intermediate care, the VA outpatient resource allocation model, and the RUG-HHC, utilized in some states for reimbursing home health care in the private sector, explained less of the cost variance and, therefore, are less adequate for VA home care resource allocation.

Kinin metabolism in the perfused ventilated rat lung. I: Bradykinin metabolism in a system modeling the normal, uninjured lung

Bradykinin (BK) in an asanguinous salt solution was perfused through intact rat lung. BK concentration varied from 0.0015 to 89 microM. Below 17 microM, the amount degraded was greater than or equal to 90% of the dose. The BK fragment distributions expressed as a percentage of the BK dose degraded were constant. The BK fragments formed and percentage yields were Pro-Pro (2-3) 49%, Arg-Pro-Pro-Gly-Phe (1-5) 32%, Pro-Pro-Gly-Phe-Ser-Pro (2-7) 6%, Arg-Pro-Pro-Gly-Phe-Ser-Pro (1-7) 6%, Arg-Pro-Pro (1-3) 3% and residual BK 4%. Above 17 microM, the amount of BK degraded was not proportional to the dose. Captopril and enalaprilat inhibited BK degradation, and their maximum inhibitions were about 50% and 30%, respectively. The percentage yield of the 1-5 fragment was greatly reduced by both inhibitors, but the percentage yields of the 2-3 and 1-8 fragments were moderately increased. It was concluded that (1) the intact rat lung itself has a very large capacity to degrade BK in the range of 2 mumoles/min/kg body weight; (2) two major and several minor enzyme pathways exist to degrade BK; (3) the relative contributions of these pathways to overall BK degradation remain essentially constant over a bradykinin concentration range from 0.0015 to 17 microM; (4) ACE/kininase-II catalyzed hydrolysis is one of the major pathways but is not the single major route for BK degradation; and (5) the other major BK degradation pathway involves enzymes cleaving the Arg1-Pro2 and Pro3-Gly4 bonds of BK.

Human lung membrane-bound neutral metallo-endopeptidase-catalyzed hydrolysis of bradykinin

Human lung membrane-bound neutral metallo-endopeptidase (NME; EC 3.4.24.11) has been purified; this enzyme occurred in two forms, NME-I and NME-II. The total NME activity was purified 2,143-fold with the final specific activities for NME-I and NME-II being 750 and 1,124, respectively. The two NME forms were resolved in the final purification step involving ion exchange; in all earlier steps including gel filtration and affinity chromatography (phenyl sepharose) both forms behaved similarly and eluted simultaneously. NME-I and NME-II both had a Mr value of 97,000, and neither form dissociated into subunits. Catalytic actions of NME-I and NME-II upon bradykinin were identical; the Gly4-Phe5 and Pro7-Phe8 bonds of bradykinin were cleaved with the final hydrolytic products for each enzyme being the tetrapeptide, Arg-Pro-Pro-Gly, the tripeptide, Phe-Ser-Pro, and the dipeptide, Phe-Arg. The intermediate products were the heptapeptide, Arg-Pro-Pro-Gly-Phe-Ser-Pro, and the pentapeptide, Phe-Ser-Pro-Phe-Arg. Neither NME-I nor NME-II were inhibited by the angiotensin-converting enzyme inhibitor, captopril. Both enzymes were inhibited by phosphoramidon, dithiothreitol and EDTA. Other peptidase inhibitors and heavy metals were not effective NME inhibitors. Both NME-I and NME-II cleaved angiotensin-I at the Pro7-Phe8 bond, and substance-P at the Glu6-Phe7 bond, with the latter being much slower than the former.

A multicatalytic high-molecular-weight neutral endopeptidase from human kidney

A multicatalytic endopeptidase (ME) with three distinct activities, chymotrypsin-like, cucumisin-like, and trypsin-like, occurred in all rat tissues examined with highest activities in kidney, testes, liver, and spleen; they were assayed with benzyloxycarbonyl-Gly-Gly-Leu-p-nitroanilide (Z-Gly-Gly-Leu-pNA), benzyloxycarbonyl-Leu-Leu-Glu-2-naphthylamide (Z-Leu-Leu-Glu-2NA), and benzyloxycarbonyl-Gly-Gly-Arg-2-naphthylamide (Z-Gly-Gly-Arg-2NA), respectively. All three activities were recovered from a single protein band on a polyacrylamide gel after electrophoresis of purified human kidney ME. The native enzyme had a Mr of 650,000, and it consisted of about 5,135 amino acid residues. After denaturation and electrophoresis on sodium dodecyl sulfate (SDS)-polyacrylamide gels kidney ME dissociated into several low Mr components ranging from 23,000 to 33,000. Kidney ME had a pH optimum of 7.6-8.1 with Z-Gly-Gly-Leu-pNA, 7.3 with Z-Leu-Leu-Glu-2NA, and 9.8 with Z-Gly-Gly-Arg-2NA. SDS enhanced chymotrypsin- and cucumisin-like activities by two to three times whereas trypsin-like activity was not enhanced. The specificity constant (kappa cat/Km) of human kidney ME for Z-Gly-Gly-Leu-pNA was 6.7 X 10(3) M-1 S-1; Z-Gly-Gly-Leu-2NA was not hydrolyzed. The specificity constant for Z-Leu-Leu-Glu-2NA was similar to, and for Z-Gly-Gly-Arg-2NA was one half of that for Z-Gly-Gly-Leu-pNA. ME cleaves only the Phe5-Ser6 bond of bradykinin (BK); however, all three ME activities were inhibited by BK. Strong inhibition of ME by albumin suggests that ME is involved in cleavage of larger polypeptides. Antipain and leupeptin almost completely inactivated the trypsin-like activity whereas they had no significant effect on the other two activities. ME is not a metal-loenzyme nor is the serine residue essential for its activities; however, thiol groups are involved. Na+ and K+ inhibited all ME activities. Trypsin-like activity was more sensitive to divalent cations than the other two.

A high-molecular-mass neutral endopeptidase-24.5 from human lung

A high-Mr neutral endopeptidase-24.5 (NE) that cleaved bradykinin at the Phe5-Ser6 bond was purified to apparent homogeneity from human lung by (NH4)2SO4 fractionation, ion-exchange chromatography and gel filtration. The final enzyme preparation produced a single enzymically active protein band after electrophoresis on a 5% polyacrylamide gel. Human lung NE had an Mr of 650,000 under non-denaturing conditions, but after denaturation and electrophoresis on an SDS/polyacrylamide gel NE dissociated into several lower-Mr components (Mr 21,000-32,000) and into two minor components (Mr approx. 66,000). The enzyme activity was routinely assayed with the artificial substrate Z-Gly-Gly-Leu-Nan (where Z- and -Nan represent benzyloxycarbonyl- and p-nitroanilide respectively). NE activity was enhanced slightly by reducing agents, greatly diminished by thiol-group inhibitors and unchanged by serine-proteinase inhibitors. Human lung NE was inhibited by the univalent cations Na+ and K+. No metal ions were essential for activity, but the heavy-metal ions Cu2+, Hg2+ and Zn2+ were potent inhibitors. With the substrate Z-Gly-Gly-Leu-Nan a broad pH optimum from pH 7.0 to pH 7.6 was observed, and a Michaelis constant value of 1.0 mM was obtained. When Z-Gly-Gly-Leu-Nap (where -Nap represents 2-naphthylamide) was substituted for the above substrate, no NE-catalysed hydrolysis occurred, but Z-Leu-Leu-Glu-Nap was readily hydrolysed by NE. In addition, NE hydrolysed Z-Gly-Gly-Arg-Nap rapidly, but at pH 9.8 rather than in the neutral range. Although human lung NE was stimulated by SDS, the extent of stimulation was not appreciable as compared with the extent of SDS stimulation of NE from other sources.

The colon in the pseudoobstructive syndrome

Colonic pseudoobstruction can occur as part of a generalized chronic intestinal pseudoobstruction syndrome or as an isolated entity. Isolated colonic pseudoobstruction can occur in two unrelated forms: the acute and chronic forms. Acute colonic pseudoobstruction is frequently a hospital-acquired disease that arises as a complication of other illnesses. The syndrome must be recognized and treated with early colonoscopic decompression to prevent cecal or colonic perforation. Chronic colonic pseudoobstruction is a syndrome of many causes. The prognosis of patients with chronic colonic pseudoobstruction is much better than that of generalized chronic intestinal pseudoobstruction, because the patients become asymptomatic with appropriate operations. The pathogenesis of acute colonic pseudoobstruction and several types of chronic colonic pseudoobstruction is not known. Further investigations should include bacteriologic study, histopathologic studies (examinations of smooth muscle and myenteric plexus), and examination of extrinsic nerves of the colon. With these approaches, a better understanding of the pathogenesis of these syndromes will be achieved.

Human lung post-proline endopeptidase: purification and action on vasoactive peptides

Post-proline endopeptidase (PPE, EC 3.4.21.26) was purified 3,450 times from human lung. PPE was routinely assayed with the artificial substrate, carbobenzoxy-glycyl-L-prolyl-p-nitroanilide (Z-Gly-Pro-pNA). The pH optimum was 7.4, and the Mr was 77,000. Thiol blocking agents were strongly inhibitory but serine blocking agents were not inhibitory. No metal ions were required for activity, but heavy metal ions such as Hg2+, Cu2+, Cd2+, and Zn2+ completely inactivated the enzyme. Both dithiothreitol (DTT) and ethylenediaminetetraacetic acid (EDTA) were required to stabilize PPE activity. Michaelis constant values for Z-Gly-Pro-pNA and carbobenzoxy-glycyl-L-prolyl-2-naphthylamide were 0.36 and 0.10 mmol/l, respectively. PPE cleaved vasoactive peptides including bradykinin (BK) and des-(Arg9)-BK (Pro3-Gly4 and Pro7-Phe8 bonds), angiotensins I and II (Pro7-Phe8 bond), substance P (Pro4-Gln5 bond), and oxytocin (Pro7-Leu8 bond). Each of these peptides inhibited PPE-catalyzed hydrolysis of Z-Gly-Pro-pNA competitively. BK had the lowest Ki value (2.35 mumol/l) and oxytocin had the highest Ki value (84.0 mumol/l). PPE was not inhibited by captopril, a potent inhibitor of angiotensin converting enzyme, which also cleaves the Pro7-Phe8 bond of BK.

Comparison of metoclopramide and metoclopramide plus dexamethasone for complete protection from cisplatinum-induced emesis

Metoclopramide was compared to a metoclopramide plus dexamethasone combination in patients receiving high-dose cisplatinum. Metoclopramide 2 mg/kg intravenously was given every 2 hours for 4 doses during two consecutive chemotherapy cycles. A randomized double-blind crossover was used with placebo or dexamethasone 20 mg given intravenously before the first metoclopramide dose. Thirty-six patients completed both study arms. There was no difference in mean vomiting episodes (1.92 for metoclopramide versus 1.33 for the combination, p = 0.20). However complete protection (no vomiting episodes) was achieved in 56% receiving the combination but only 36% receiving metoclopramide alone (p less than 0.08). No significant difference in toxicity or patient preference was noted. Late nausea or vomiting lasting 2 to 7 days appeared in 26% of cycles and was associated with but not completely explained by a greater number of acute vomiting episodes. Combination antiemetic therapy can achieve a higher incidence of complete protection from cisplatinum-induced vomiting. However, late nausea and vomiting may require modification of present regimens.

A program of evaluation and research for hospital based home care

A program of evaluation and research has been developed and initiated in a large Hospital Based Home Care Program which principally serves chronically-ill, elderly veterans. Program evaluation is based on data from an automated home care information system developed for this purpose. The information system is based on the Long-Term Health Care Minimum Data Set, a nationally-recommended data set which describes patient demographics and physical and mental health status, and health services provided. Home care and related costs per visit and per patient day have been identified. A proposed, experimental research protocol identifies health status outcomes and health care costs of home care and alternative modes of long-term health care.

The rate of membrane turnover by the hairy cells of leukemic reticuloendotheliosis: a kinetic study of a receptor for IgM

The kinetics of turnover of a surface receptor for IgM were studied in six cases of hairy cell leukemia and four cases of chronic lymphocytic leukemia and the results were used as an indicator of membrane turnover in the pathologic cells of these two chronic leukemias. Rosette formation, shedding, and reexpression with EA (IgM) by hairy cells, a process which was shown to require protein synthesis, followed a cyclical pattern with a modal peak-to-peak reexpression time of 6 hr. Membrane turnover time in the cases of chronic lymphocytic leukemia was 12 hr or more. This work indicates that a reduced membrane turnover rate is not an essential feature of chronic leukemias. The more general application of this type of approach to the study of membrane turnover in normal cells and their pathologic counterparts are discussed.

Complications and management of methods of dialysis access for renal failure

The management of dialysis access requires the awareness that any single access site is finite. A commitment to maintain access is reasonable with a planned approach. Dialysis for the end-stage renal disease patient must continue acutely during the management of access complications, and chronically. The goal of treatment is to return the patient to a routine dialysis regimen as soon as possible. Suspected infections should be treated immediately with systemic antibiotics specific for resistant Staphylococcus aureus. Systemic infection should be controlled before a new foreign body is implanted. My personal philosophy of access includes the following principles. (1) distal is good, (2) preserve all possible sites, (3) arm is better than leg, and (4) everything is relative.