Advanced diffusion MRI provides evidence for altered axonal microstructure and gradual peritumoral infiltration in GBM in comparison to brain metastases

PURPOSE

In contrast to peritumoral edema in metastases, GBM is histopathologically characterized by infiltrating tumor cells within the T2 signal alterations. We hypothesized that depending on the distance from the outline of the contrast-enhancing tumor we might reveal imaging evidence of gradual peritumoral infiltration in GBM and predominantly vasogenic edema around metastases. We thus investigated the gradual change of advanced diffusion metrics with the peritumoral zone in metastases and GBM.

METHODS

In 30 patients with GBM and 28 with brain metastases, peritumoral T2 hyperintensity was segmented in 33% partitions based on the total volume beginning at the enhancing tumor margin and divided into inner, middle and outer zones. Diffusion Tensor Imaging (DTI)-derived fractional anisotropy and mean diffusivity as well as Diffusion Microstructure Imaging (DMI)-based parameters Dax-intra, Dax-extra, V‑CSF and V-intra were employed to assess group-wise differences between inner and outer zones as well as within-group gradients between the inner and outer zones.

RESULTS

In metastases, fractional anisotropy and Dax-extra were significantly reduced in the inner zone compared to the outer zone (FA p = 0.01; Dax-extra p = 0.03). In GBM, we noted a reduced Dax-extra and significantly lower intraaxonal volume fraction (Dax-extra p = 0.008, V‑intra p = 0.006) accompanied by elevated axial intraaxonal diffusivity in the inner zone (p = 0.035). Between-group comparison of the outer to the inner zones revealed significantly higher gradients in metastases over GBM for FA (p = 0.04) as well as the axial diffusivity in the intra- (p = 0.02) and extraaxonal compartment (p < 0.001).

CONCLUSION

Our findings provide evidence of gradual alterations within the peritumoral zone of brain tumors. These are compatible with predominant (vasogenic) edema formation in metastases, whereas our findings in GBM are in line with an axonal destructive component in the immediate peritumoral area and evidence of tumor cell infiltration with accentuation in the tumor's vicinity.

Crystal structure of a covalently linked Aurora-A-MYCN complex

Formation of the Aurora-A-MYCN complex increases levels of the oncogenic transcription factor MYCN in neuroblastoma cells by abrogating its degradation through the ubiquitin proteasome system. While some small-molecule inhibitors of Aurora-A were shown to destabilize MYCN, clinical trials have not been satisfactory to date. MYCN itself is considered to be `undruggable' due to its large intrinsically disordered regions. Targeting the Aurora-A-MYCN complex rather than Aurora-A or MYCN alone will open new possibilities for drug development and screening campaigns. To overcome the challenges that a ternary system composed of Aurora-A, MYCN and a small molecule entails, a covalently cross-linked construct of the Aurora-A-MYCN complex was designed, expressed and characterized, thus enabling screening and design campaigns to identify selective binders.

Differences in circulating cardiac troponin I and T in acute and chronic cardiac disease

Background

Clinical practice and guidelines assume that cardiac troponin I (cTnI) and cTnT are interchangeable, reflecting identical pathophysiological processes. However, it is unknown if cTnI and cTnT really are equivalent measures in different pathophysiological settings.

Purpose

To highlight potential differences in the release of cTnI and cTnT.

Methods

Large pooled cohort analysis including extensively characterized individuals, stratified into three groups: no cardiac disease (normal aging), chronic cardiac disease, and acute cardiac disease. Circulating cTnI and cTnT concentrations were measured blinded to clinical data using high-sensitivity assays (hs-cTnI-Architect, hs-cTnT-Elecsys) and their ratio calculated. Findings were validated using a second hs-cTnI assay (hs-cTnI-Clarity).

Results

Among 8719 individuals, 29% female, 10% had no known cardiac disease, 71% chronic cardiac disease, and 20% acute cardiac disease. Baseline characteristics including renal function were comparable between individuals with chronic and acute cardiac disease. Normal aging (without cardiac disease) was associated with a disproportional increase in cTnT versus cTnI (low cTnI/cTnT ratio, median 0.50, IQR 0.38–0.68). Although older, patients with chronic cardiac disease had a slightly higher cTnI/cTnT ratio (median 0.53, IQR 0.37–0.79, p&lt;0.05). In contrast, in patients with acute cardiac disease, cTnI concentrations were disproportionally elevated compared to cTnT concentrations, resulting in a cTnI/cTnT ratio of 1.96 (IQR 0.93–4.73, p&lt;0.001). Internal validation using a second hs-cTnI assay confirmed these findings.

Conclusion

These findings suggest relevant differences in the release of cTnI and cTnT with a greater release of cTnT versus cTnI in normal aging and a disproportional increase in cTnI versus cTnT in acute cardiac disease.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Swiss National Science Foundation

Renal failure: a non-cardiac source of high sensitivity cardiac troponin T

Background

Circulating high sensitivity cardiac troponin T (hs-cTnT) levels are frequently elevated in patients with end-stage renal disease (ESRD). The underlying pathophysiology is largely unknown. Currently, accumulation of hs-cTnT due to impaired renal clearance, as well as increased production caused by chronic cardiomyocyte injury is being discussed.

Purpose

The aim of this study was to assess the relative contribution of impaired renal clearance as a non-cardiac source of elevated hs-cTnT concentrations, using renal transplantation as an in vivo model of rapidly improved renal function and on a short-term basis rather unchanged cardiac pathology.

Methods

This single-centre study was a secondary analysis within a prospective active surveillance study program for perioperative myocardial infarction/injury (PMI). 42 consecutive high-risk patients undergoing renal transplantation without evidence of PMI were included. Serial creatinine and hs-cTnT (Elecsys, Roche) measurements were performed pre-transplant (baseline) and post-transplant on day (d) 1, between d2 and d5, and between d14 and d180. The effect of time and creatinine on hs-cTnT was estimated with a log-level non-linear mixed-effects model, where time and creatinine were treated as the fixed effects and subject as the random effect. Natural cubic splines were used to account for nonlinearity in the fixed effects.

Results

Baseline median serum creatinine concentration was 616 umol/L [interquartile range (IQR) 477–825], and significantly fell to 425 umol/L (IQR 313–619) on d1, 285 umol/L (IQR 194–509) on day2–5, and 116 umol/L (IQR 100–166) on d14–180 (p&lt;0.001, p&lt;0.001, and p=0.043, respectively; Figure 1A).

Pre-transplant hs-cTnT concentrations were above the 99th percentile (14ng/L) in all patients, median hs-cTnT concentration was 50 ng/L (IQR 35–70). In parallel to the fall in serum creatinine from baseline to d1, hs-cTnT concentrations significantly fell to 28 ng/L (IQR 15–40) on d1 (p&lt;0.001), and then remained constant on d2–5 (27 ng/L (IQR 18–35)), and on d14–180 (24 ng/L (IQR 19–28); Figure 1B).

The mixed-effect model showed a significant decrease of hs-cTnT between baseline and d1 (p&lt;0.001), whereas no significant change between d1 and d2 (p=0.82) occurred (Figure 2).

Conclusion

In contrast to the continuously falling serum creatinine levels, hs-cTnT concentrations reduced by about 50% only within the first 24 hours with a functional graft and then remained elevated above the 99th percentile. This suggests, that ESRD is a non-cardiac source of elevated circulating hs-cTnT concentrations, which contributes about 50%, while the other 50% seem related to chronic cardiomyocyte injury. Further studies assessing the long-term effect of renal transplantation on hs-cTnT levels and cardiac function are needed.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Swiss National Science FoundationSwiss Heart Foundation

POS1372 THE 2021 EULAR AND ACR POINTS TO CONSIDER FOR DIAGNOSIS, MANAGEMENT AND MONITORING OF THE IL 1 MEDIATED AUTOINFLAMMATORY DISEASES: CAPS, TRAPS, MKD, AND DIRA

Background

The Interleukin-1 (IL-1) mediated systemic autoinflammatory diseases (SAIDs), including the cryopyrin-associated periodic syndromes (CAPS), tumor necrosis factor receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency (MKD), and deficiency of the IL-1 receptor antagonist (DIRA) belong to a group of rare immunodysregulatory diseases that primarily present in early childhood with variable multiorgan involvement. When untreated, patients with severe clinical phenotypes have a poor prognosis, and diagnosis and management of these patients can be challenging. However, recently-approved treatments targeting the pro-inflammatory cytokine IL-1 have been life-changing and have significantly improved patient outcomes.

Objectives

We aimed to establish evidence-based recommendations on diagnosis, treatment, and monitoring to standardize the management of these patients.

Methods

A multinational, multidisciplinary task force consisting of physician experts including rheumatologists, patients or caregivers, and allied health care professionals was established. Evidence synthesis including systematic literature review and expert consensus (Delphi) via surveys were conducted. Consensus methodology was utilized to formulate and vote on statements to guide optimal patient care.

Results

The task force devised five overarching principles, 14 statements related to diagnosis, 10 on therapy, and 9 focused on long-term monitoring that were evidence and/or consensus-based for patients with IL-1 mediated diseases. An outline was developed for disease-specific monitoring of inflammation-induced organ damage progression and reported therapies of CAPS, TRAPS, MKD, and DIRA.

Conclusion

The 2021 EULAR/ACR points to consider provide state-of-the-art knowledge based on published data and expert opinion to guide diagnostic evaluation, treatment, and monitoring of patients with CAPS, TRAPS, MKD and DIRA, and inform the various stakeholders about optimized patient care to improve disease outcomes.

References

[1]Masters SL, Simon A, Aksentijevich I, et al. Horror autoinflammaticus: the molecular pathophysiology of autoinflammatory disease (*). Annu Rev Immunol 2009;27:621-68.

Disclosure of Interests

micol romano: None declared, Zehra Serap Arici: None declared, David Piskin: None declared, Sara Alehashemi: None declared, Daniel Aletaha Speakers bureau: Lilly, Merck, Pfizer, Roche, Sandoz, Consultant of: Abbvie, Amgen, Lilly, Merck, Novartis, Pfizer, Roche, Sandoz, Grant/research support from: Abbvie, Amgen, Lilly, Novartis, Roche, SoBi, Sanofi, Karyl Barron: None declared, Susa Benseler: None declared, Roberta Berard Consultant of: Sandoz and Roche, Lori Broderick Grant/research support from: Novartis and Regeneron, Fatma Dedeoglu Consultant of: Novartis, Michelle Diebold: None declared, Karen Durrant: None declared, Polly Ferguson Consultant of: Novartis, Grant/research support from: NIH, CARRA, Inc, Dirk Foell Speakers bureau: Novartis, Peer Voice and SoBi, Consultant of: Boehringer Ingelheim, Chugai-Roche, Merck, Novartis, SoBi, Grant/research support from: Novartis and SoBi, Jonathan Hausmann Consultant of: Novartis, Biogen and Pfizer, Grant/research support from: CARRA, SoBi, Olcay Jones: None declared, Daniel Kastner: None declared, Helen J. Lachmann: None declared, Ronald Laxer Consultant of: SoBi, Novartis, Sanofi, Dorelia Rivera: None declared, Nicolino Ruperto Speakers bureau: Eli-Lilly, GSK, Pfizer SoBi and UCB, Consultant of: Ablynx, Amgen, Astrazeneca-Medimmune, Aurinia, Bayer, Bristol Myers and Squib, Cambridge Healthcare research, Celgene, Domain therapeutic, Eli-Lilly, EMD Serono, GSK, Idorsia, Janssen, Novartis, SoBi, Pfizer and UCB, Anna Simon: None declared, Marinka Twilt: None declared, Joost Frenkel: None declared, Hal Hoffman Consultant of: Novartis, Regeneron, SoBi, Aclaris, Grant/research support from: Bristol-Meyer-Squib, Jecure, Takeda and Zomagen, Adriana de Jesus: None declared, Jasmin Kuemmerle-Deschner Speakers bureau: Novartis and SoBi, Consultant of: Novartis and SoBi, Grant/research support from: Novartis and SoBi, Seza Özen Speakers bureau: Novartis and SoBi, Marco Gattorno Speakers bureau: Novartis and SoBi, Grant/research support from: Novartis, Raphaela goldbach-mansky: None declared, Erkan Demirkaya Grant/research support from: Sobi

Prognostic value of self-reported subjective exercise capacity in patients with acute dyspnea

Background

Quantitative assessment of self-reported exercise capacity as provided by the Duke Activity Status Index (DASI) is a validated measure of exercise capacity in stable ambulatory patients.

Objectives

This study aimedto test whether the quantification of self-reported exercise capacityusing the DASI may aid physicians in the risk stratification of patients presenting with acute dyspnea to the emergency department (ED).

Methods

Basics in Acute Shortness of Breath EvaLuation (BASEL V) was a prospective cohort study recruiting dyspneic patients at the ED. The prognostic value and accuracy of theDASI assessed shortly after presentation were quantified using Cox regression analyses and the Area under the curve (AUC).

Results

Among 1019 patients eligible for this analysis 529 (51.9%) had an adjudicated final diagnosis of acute heart failure, 75 (7.4%) and 297 (29.1%) patients died within 90 and 720 days after presentation. Unadjusted hazard ratios (HR) and multivariable adjusted hazard ratios (aHR) for 90-day and 720-day mortality increased continuously from the fourth (best self-reported exercise capacity) to the first DASI-quartile (worst self-reported exercise capacity). For 720-day mortality in the first quartile theHR was 9.1 (95%-CI 5.5–14.9) (aHR 6.1 [95%-CI 3.7–10.1]), in the second quartile 6.4 (95%-CI 3.9–10.6) (aHR 4.4 [95%-CI 2.6–7.3]), while in the third quartile the HR was 3.2 (95%-CI 1.9–5.5) (aHR 2.4 [95%-CI 1.4–4.0]). The prognostic accuracy of the DASI was moderate-to-high and higher than that of B-type natriuretic peptide (BNP) and NT-proBNP (N-terminal pro-BNP) concentrations, e.g. for 720-day mortality prediction AUC 0.70 versus 0.64, p=0.020; 0.72 versus 0.68, p=0.074.

Conclusions

Quantification of self-reported subjective exercise capacityusing the DASI provides moderate-to-high prognostic accuracy in patients presenting with acute dyspnea to the ED and may aid physicians in further risk stratification.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union, the Swiss National Science Foundation. Duke Activity Status Index

Design, Synthesis, and Evaluation of WD-Repeat-Containing Protein 5 (WDR5) Degraders

Histone H3K4 methylation serves as a post-translational hallmark of actively transcribed genes and is introduced by histone methyltransferase (HMT) and its regulatory scaffolding proteins. One of these is the WD-repeat-containing protein 5 (WDR5) that has also been associated with controlling long noncoding RNAs and transcription factors including MYC. The wide influence of dysfunctional HMT complexes and the typically upregulated MYC levels in diverse tumor types suggested WDR5 as an attractive drug target. Indeed, protein-protein interface inhibitors for two protein interaction interfaces on WDR5 have been developed. While such compounds only inhibit a subset of WDR5 interactions, chemically induced proteasomal degradation of WDR5 might represent an elegant way to target all oncogenic functions. This study presents the design, synthesis, and evaluation of two diverse WDR5 degrader series based on two WIN site binding scaffolds and shows that linker nature and length strongly influence degradation efficacy.

Development and validation of an ECG-based cardiac syncope risk calculator

Background

The early diagnosis of cardiac syncope is often challenging. We therefore developed an ECG-based risk calculator as an aid for rapid rule-out or rule-in of cardiac syncope and aimed to validate this decision tool.

Methods

In a prospective diagnostic international multicenter study (derivation cohort), 2007 patients, 40 years or older, presenting with syncope to the emergency department were recruited. The primary diagnostic outcome, cardiac syncope, was centrally adjudicated by two independent cardiologists using all clinical information obtained during syncope work-up including 12-month follow up. 12-lead ECG was recorded at presentation and read by residents blinded to clinical information. Significant ECG predictors of cardiac syncope were identified using penalized backward selection. Findings were validated in an independent US multicenter cohort with 2'269 syncope patients.

Results

In the derivation cohort (median age 71 years, 40% women), centrally adjudicated cardiac syncope was present in 267 patients (16%). Seven ECG criteria (rhythm, heart rate, corrected QT-interval, ST-segment depression, atrioventricular-block, bundle-branch-block and ventricular extrasystole/non-sustained ventricular tachycardia) were identified as significant predictors for cardiac syncope and combined into the bAseL Ecg Risk calculaTor for Cardiac Syncope (ALERT-CS). Diagnostic accuracy of ALERT-CS for cardiac syncope, as quantified by the area under the receiver-operating characteristics curve (AUC), was high (0.80, 95%-confidence interval (CI) 0.77–0.83) and significantly higher compared to the EGSYS score (0.73, 95% CI 0.70–0.76, p&lt;0.001). In combination, ALERT-CS significantly increased the AUC of BNP (0.82, 95% CI 0.79–0.85 vs 0.77, 95% CI 0.74–0.81, p=0.003), hs-cTnT (0.84, 95% CI 0.0.81–0.87 vs 0.77, 95% CI 0.74–0.80, p&lt;0.001) and integrated clinical judgment in the ED (0.90, 95% CI 0.89–0.92 vs 0.87, 95% CI 0.84–0.90, p&lt;0.001).

A predicted probability for cardiac syncope below 5.5% by ALERT-CS identified 138 patients (8%) eligible for triage towards rapid rule-out of cardiac syncope with a sensitivity of 99%. A predicted probability above 37.5% identified 181 patients (11%) eligible for triage towards rapid rule-in of cardiac syncope with a specificity of 95%. Prognostic verification for 30-day major adverse cardiac events (MACE) showed a high rate of MACE in the rule-in group and a very low rate of MACE in the rule-out group (Figure).

External validation (median age 72 years, 48% women) showed similar diagnostic accuracy (AUC 0.76, 95% CI 0.73–0.79) and prognostic results.

Conclusion

Combining seven ECG criteria within the simple ALERT-CS may aid ED physicians in the early rule-out or rule-in of cardiac syncope.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Swiss National Science Foundation, Swiss Heart Foundation

PROTAC-mediated degradation reveals a non-catalytic function of AURORA-A kinase

The mitotic kinase AURORA-A is essential for cell cycle progression and is considered a priority cancer target. While the catalytic activity of AURORA-A is essential for its mitotic function, recent reports indicate an additional non-catalytic function, which is difficult to target by conventional small molecules. We therefore developed a series of chemical degraders (PROTACs) by connecting a clinical kinase inhibitor of AURORA-A to E3 ligase-binding molecules (e.g. thalidomide). One degrader induced rapid, durable and highly specific degradation of AURORA-A. In addition ,we found that the degrader complex was stabilized by cooperative binding between AURORA-A and CEREBLON. Degrader-mediated AURORA-A depletion caused an S-phase defect, which is not the cell cycle effect observed upon kinase inhibition, supporting an important non-catalytic function of AURORA-A during DNA replication. AURORA-A degradation induced rampant apoptosis in cancer cell lines, and thus represents a versatile starting point for developing new therapeutics to counter AURORA-A function in cancer.

Autoinhibition Mechanism of the Ubiquitin-Conjugating Enzyme UBE2S by Autoubiquitination

Ubiquitin-conjugating enzymes (E2s) govern key aspects of ubiquitin signaling. Emerging evidence suggests that the activities of E2s are modulated by posttranslational modifications; the structural underpinnings, however, are largely unclear. Here, we unravel the structural basis and mechanistic consequences of a conserved autoubiquitination event near the catalytic center of E2s, using the human anaphase-promoting complex/cyclosome-associated UBE2S as a model system. Crystal structures we determined of the catalytic ubiquitin carrier protein domain combined with MD simulations reveal that the active-site region is malleable, which permits an adjacent ubiquitin acceptor site, Lys⁺⁵, to be ubiquitinated intramolecularly. We demonstrate by NMR that the Lys⁺⁵-linked ubiquitin inhibits UBE2S by obstructing its reloading with ubiquitin. By immunoprecipitation, quantitative mass spectrometry, and siRNA-and-rescue experiments we show that Lys⁺⁵ ubiquitination of UBE2S decreases during mitotic exit but does not influence proteasomal turnover of this E2. These findings suggest that UBE2S activity underlies inherent regulation during the cell cycle.

A prospective, randomized clinical study of adjunctive peripheral parenteral nutrition in adult subacute care patients

BACKGROUND

A number of frail, older, undernourished patients cannot maintain adequate oral intake to meet protein-calorie needs after an illness, even when high-density nutritional supplements are added. Tolerance to enteral nutrition by gastric tube is poor in this group of patients. Peripheral parenteral nutrition is an effective method of administering nutritional support to patients with mild to moderate nutritional deficiencies who are unable to receive enteral nutrition or for whom enteral nutrition alone cannot meet energy needs. However, no data exists for the use of peripheral parenteral nutrition longer than two weeks and overall there are remarkably few studies on the efficacy of peripheral parenteral nutrition.

METHODS

A Phase 4, single center, prospective, randomized, parallel group design clinical trial was conducted to evaluate long-term safety of peripheral parenteral nutrition in post-acute patients receiving inadequate enteral nutrition. Nutritional status was measured by the Mini-Nutritional Assessment and functional status by the Functional Inventory Measure. Subjects received a mean duration for peripheral parenteral nutrition of 15.8 +/- 6.7 days (range 8-23).

RESULTS

The peripheral parenteral nutrition group demonstrated several trends towards improvement in prealbumin, CD4 cell count, and functional status compared to the untreated control group. Two patients in the peripheral parenteral nutrition group developed low-grade phlebitis; however, this did not result in discontinuing intravenous therapy. No other adverse events occurred. This study demonstrates that peripheral parenteral nutrition is feasible and safe in postacute care.

CONCLUSIONS

We conclude that peripheral parenteral nutrition can be safely administered in post-acute settings with a low rate of complications.

pH and concentration of bilirubin in feeding tube aspirates as predictors of tube placement

BACKGROUND

Currently available bedside methods for determining feeding tube placement often provide inconclusive results. Therefore, additional data are needed to assist nurses in making decisions regarding tube location.

OBJECTIVES

To describe the usual concentration of bilirubin in aspirates from newly inserted feeding tubes and to determine the extent to which these measures can contribute to pH alone in correctly predicting feeding tube location.

METHODS

Gastrointestinal samples for concurrent pH and bilirubin testing were obtained from adult, acutely ill patients with newly inserted small-bore feeding tubes (nasogastric, n = 209; nasointestinal, n = 228) within 5 minutes of radiographs taken to determine tube location. Respiratory samples were tested (tracheobronchial, n = 126; pleural, n = 24). pH was measured with a pH meter, and bilirubin content was assayed spectrophotometrically. Results from the pH and bilirubin tests were compared with tube location as determined by radiography.

RESULTS

Mean pH levels in the lung (7.73) and intestine (7.35) were significantly higher than the mean pH level in the stomach (3.90; p < .001 for each comparison). Mean bilirubin levels in the lung (.08 mg/dl) and stomach (1.28 mg/dl) were significantly lower than the mean bilirubin level in the intestine (12.73 mg/dl; p < .001 for each). By visually inspecting distribution overlap and mean differences by tube site, results were dichotomized so that a combination of pH and bilirubin values could be used to develop a predictive algorithm. A pH of >5 and a bilirubin value of <5 mg/dl correctly identified all respiratory cases, whereas a pH >5 coupled with a bilirubin level of > or =5 mg/dl correctly identified three fourths of the intestinal cases. A pH of < or =5 coupled with a bilirubin value of <5 correctly identified more than two thirds of the gastric cases.

CONCLUSIONS

Preliminary laboratory-based data indicate that appropriate use of the proposed algorithm could significantly reduce the number of x-rays needed to exclude respiratory placement and to distinguish between gastric and intestinal placement.

[How to optimize lymph node dissection in colorectal cancers. A technique for simple and efficacious clarification]

Studies relating to the prognosis of colorectal carcinomas insist on the quality of mesocolic examination and on the frequency of metastases in minute lymph nodes. The aim of our study was to evaluate an easy, rapid and new clearance method recently described by Koren et al. Twenty-one surgical specimens for colorectal carcinomas have been investigated. After lymph node examination with the traditional method, the mesocolic fat was immersed in a clearing solution. After 6 hours, lymph nodes stood out as white chalky nodules, and were dissected. By the traditional method 182 lymph nodes were detected and 89 additional lymph nodes after clearing. In one case, the detection of a metastasis in lymph node after clearing allowed to upstage the tumour from Dukes B (N0) to Dukes C (N+). This easy and inexpensive method allows the detection of minute lymph nodes and helps to establish a more accurate staging.

pH and concentrations of pepsin and trypsin in feeding tube aspirates as predictors of tube placement

BACKGROUND

The purpose of this study was to determine the extent to which pepsin and trypsin concentrations in feeding tube aspirates, in addition to pH, contribute to predicting feeding tube position.

METHODS

Aspirates from 742 feeding tubes (nasogastric, n = 343; nasointestinal, n = 399) were tested for pH and enzyme concentrations. Also tested were aspirates from two feeding tubes inadvertently positioned into the lung (one in the pleural space and one in the tracheobronchial tree) and 146 samples of tracheobronchial and pleural fluids collected by other methods. Enzyme assays were conducted in a research laboratory. Results of the pH and enzyme tests were compared with radiologic reports of tube location.

RESULTS

Gastric fluid had a mean low pH (4.06), a high mean pepsin concentration (349.1 micrograms/mL), and a low mean trypsin concentration (19.3 micrograms/mL). In contrast, intestinal fluid had a mean high pH (7.40), a high mean trypsin concentration (143.0 micrograms/mL), and a low mean pepsin concentration (24.2 micrograms/mL). Respiratory samples also had a high mean pH (7.89) but contained little or no pepsin or trypsin. Using a logistic regression equation with all three variables to differentiate between respiratory and gastrointestinal placement, it was possible to correctly classify 100% of the respiratory cases and 93.4% of the gastrointestinal cases. Another equation used to differentiate between gastric and intestinal sites was able to classify correctly 91.2% of the gastric cases and 91.5% of the intestinal cases.

CONCLUSIONS

The results clearly indicate that laboratory-determined enzyme concentrations in feeding tube aspirates are helpful in predicting tube location. Thus, it is desirable that inexpensive, simple bedside tests be developed so that they can be used in conjunction with pH measurements to help predict tube position.

Actions of 1,25-dihydroxyvitamin D3 on human mesangial cells

In the present study, we examined specific binding of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] by an effects of 1,25(OH)2D3 on human mesangial cells (hMC), obtained from healthy portions of tumor-bearing kidneys. Receptors for 1,25(OH)2D3 were characterized by (1) sucrose density gradient analysis, (2) Scatchard analysis, and (3) DNA affinity of the receptor molecule. Specific binding occurred by a single class of macromolecules, sedimenting with 3.5 S in sucrose density gradients (5% to 20%). Receptors showed high affinity (Kd, 1.39 x 10(-10)), and specific binding capacity (Nmax) of 821 binding sites per cell. 1,25(OH)2D3 (10(-6) to 10(-10)) reduced both DNA synthesis (by [3H]thymidine incorporation) and cell growth (by cell counting) throughout the log-phase and confluence. Further evidence of functional effects of 1,25(OH)2D3 on hMC is provided by ultrastructural studies, which showed rapid increase of electron-dense lysosomal particles in hMC exposed to 1,25(OH)2D3. The data identify actions of 1,25(OH)2D3, a molecule with recently recognized immunoregulatory roles, on hMC. The results are consistent with a role of 1,25(OH)2D3 in control of mesangial cell function.

Kinetics of synthesis and phosphorylation of respiratory syncytial virus polypeptides

The kinetics of synthesis of [35S]methionine-labelled respiratory syncytial virus-specific proteins were studied in CV-1 cells infected at high multiplicity. Immunoprecipitated viral proteins resolved by SDS-PAGE were quantified by scanning fluorographs of protein bands. The nucleocapsid (N) protein was detectable by 2 h post-infection (p.i.), whereas the phospho- (P), matrix (M) and fusion (Fo) proteins and Vp24 (a matrix-like protein) were first detected between 4 and 6 h p.i. Synthesis of the glyco- (G) protein was first detected at 6 h p.i. and reached its peak synthesis rate at 10 h p.i. Virus-specific P, M and Vp24 proteins were phosphorylated in infected cells. The P protein was highly phosphorylated in purified virions whereas phosphorylated species of the M and Vp24 proteins were minor components. The phosphorylated form of the P protein was detected by monoclonal antibody precipitation, confirming the identity of this protein. The N protein was not phosphorylated in infected cells or in virions. Synthesis of [35S]methionine-labelled proteins preceded detectable 32Pi labelling by several hours. The putative phosphorylated M protein was detected at 6 h p.i. before phosphorylated forms of P and Vp24 were seen. The timing of appearance of the phosphorylated species of P and Vp24 proteins in infected cells corresponded to the release of infectious virions from infected cell monolayers at 10 to 12 h p.i.