Predicting factors of patient satisfaction after varicose vein surgery at a university hospital in Nepal

INTRODUCTION

Varicose veins are a common vascular problem with a high prevalence, yet they are often neglected. The main objective of this study was to explore the patient satisfaction after varicose vein surgery, along with its predicting factors. To our knowledge, no similar study has been conducted in Nepal to date.

METHODOLOGY

This retrospective cross-sectional study included patients who underwent varicose vein surgery at Dhulikhel Hospital from September 2019 to February 2020. The satisfaction level after the surgery was assessed using a 10-point Likert scale questionnaire during a telephone interview with their verbal consent. Descriptive statistics and linear regression were performed to identify the predicting factors of patient satisfaction.

RESULTS

Among a total of 84 patients interviewed, 53.6% were male. The mean age of the participants was 43.13 ± 13.62 years. The mean patient satisfaction score was 42 ± 5.5, with nursing service, discharge teaching and hospital service being the highest scoring items in terms of patient satisfaction. Linear regression revealed age ≤40 years as a predictor of higher patient satisfaction (β=0.258, p=0.015) while early stage of varicose veins (β=-0.233, p=0.026) and duration of post-operative follow-up (β=-0.25, p=0.021) were negative predictors of patient satisfaction. This means that patients with C2-C3 venous disease and longer duration of postoperative follow-up tended to have lower satisfaction scores.

CONCLUSION

The overall patient satisfaction following varicose vein surgery was very good, and the major predictors of better satisfaction were age ≤40 years, C4-C6 clinical classification of venous disease and the shorter duration of follow-up after surgery.

Identification and risk stratification of coronary disease by artificial intelligence-enabled ECG

Background

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death worldwide, driven primarily by coronary artery disease (CAD). ASCVD risk estimators such as the pooled cohort equations (PCE) facilitate risk stratification and primary prevention of ASCVD but their accuracy is still suboptimal.

Methods

Using deep electronic health record data from 7,116,209 patients seen at 70+ hospitals and clinics across 5 states in the USA, we developed an artificial intelligence-based electrocardiogram analysis tool (ECG-AI) to detect CAD and assessed the additive value of ECG-AI-based ASCVD risk stratification to the PCE. We created independent ECG-AI models using separate neural networks including subjects without known history of ASCVD, to identify coronary artery calcium (CAC) score ≥300 Agatston units by computed tomography, obstructive CAD by angiography or procedural intervention, and regional left ventricular akinesis in ≥1 segment by echocardiogram, as a reflection of possible prior myocardial infarction (MI). These were used to assess the utility of ECG-AI-based ASCVD risk stratification in a retrospective observational study consisting of patients with PCE scores and no prior ASCVD. The study period covered all available digitized EHR data, with the first available ECG in 1987 and the last in February 2023.

Findings

ECG-AI for identifying CAC ≥300, obstructive CAD, and regional akinesis achieved area under the receiver operating characteristic (AUROC) values of 0.88, 0.85, and 0.94, respectively. An ensembled ECG-AI identified 3, 5, and 10-year risk for acute coronary events and mortality independently and additively to PCE. Hazard ratios for acute coronary events over 3-years in patients without ASCVD that tested positive on 1, 2, or 3 versus 0 disease-specific ECG-AI models at cohort entry were 2.41 (2.14-2.71), 4.23 (3.74-4.78), and 11.75 (10.2-13.52), respectively. Similar stratification was observed in cohorts stratified by PCE or age.

Interpretation

ECG-AI has potential to address unmet need for accessible risk stratification in patients in whom PCE under, over, or insufficiently estimates ASCVD risk, and in whom risk assessment over time periods shorter than 10 years is desired.

Funding

Anumana.

Development of Electronic Health Record-Based Machine Learning Models to Predict Barrett's Esophagus and Esophageal Adenocarcinoma Risk

INTRODUCTION

Screening for Barrett's esophagus (BE) is suggested in those with risk factors, but remains underutilized. BE/esophageal adenocarcinoma (EAC) risk prediction tools integrating multiple risk factors have been described. However, accuracy remains modest (area under the receiver-operating curve [AUROC] ≤0.7), and clinical implementation has been challenging. We aimed to develop machine learning (ML) BE/EAC risk prediction models from an electronic health record (EHR) database.

METHODS

The Clinical Data Analytics Platform, a deidentified EHR database of 6 million Mayo Clinic patients, was used to predict BE and EAC risk. BE and EAC cases and controls were identified using International Classification of Diseases codes and augmented curation (natural language processing) techniques applied to clinical, endoscopy, laboratory, and pathology notes. Cases were propensity score matched to 5 independent randomly selected control groups. An ensemble transformer-based ML model architecture was used to develop predictive models.

RESULTS

We identified 8,476 BE cases, 1,539 EAC cases, and 252,276 controls. The BE ML transformer model had an overall sensitivity, specificity, and AUROC of 76%, 76%, and 0.84, respectively. The EAC ML transformer model had an overall sensitivity, specificity, and AUROC of 84%, 70%, and 0.84, respectively. Predictors of BE and EAC included conventional risk factors and additional novel factors, such as coronary artery disease, serum triglycerides, and electrolytes.

DISCUSSION

ML models developed on an EHR database can predict incident BE and EAC risk with improved accuracy compared with conventional risk factor-based risk scores. Such a model may enable effective implementation of a minimally invasive screening technology.

Massive Hemoptysis and Pulmonary Thromboembolism in a Patient with Pulmonary Tuberculosis: A Therapeutic Conundrum Managed with Bronchial Artery Embolization

Hemoptysis is a crucial entity taking into account its morbidity and mortality. Pulmonary tuberculosis is the leading cause for massive hemoptysis in our part of the world, which if left untreated may be life threatening. We present a case of a 37-year-old male patient with pulmonary tuberculosis with concurrent pulmonary thromboembolism presenting with massive hemoptysis, which was successfully managed with Bronchial Artery Embolization. This case represents that this measure can be a viable therapeutic choice for a patient with a severe lifethreatening hemoptysis, particularly when other treatment options are unavailable or ineffective.

Analysis of the Effectiveness of the Ad26.COV2.S Adenoviral Vector Vaccine for Preventing COVID-19

IMPORTANCE

Continuous assessment of the effectiveness and safety of the US Food and Drug Administration-authorized SARS-CoV-2 vaccines is critical to amplify transparency, build public trust, and ultimately improve overall health outcomes.

OBJECTIVE

To evaluate the effectiveness of the Johnson & Johnson Ad26.COV2.S vaccine for preventing SARS-CoV-2 infection.

DESIGN, SETTING, AND PARTICIPANTS

This comparative effectiveness research study used large-scale longitudinal curation of electronic health records from the multistate Mayo Clinic Health System (Minnesota, Arizona, Florida, Wisconsin, and Iowa) to identify vaccinated and unvaccinated adults between February 27 and July 22, 2021. The unvaccinated cohort was matched on a propensity score derived from age, sex, zip code, race, ethnicity, and previous number of SARS-CoV-2 polymerase chain reaction tests. The final study cohort consisted of 8889 patients in the vaccinated group and 88 898 unvaccinated matched patients.

EXPOSURE

Single dose of the Ad26.COV2.S vaccine.

MAIN OUTCOMES AND MEASURES

The incidence rate ratio of SARS-CoV-2 infection in the vaccinated vs unvaccinated control cohorts, measured by SARS-CoV-2 polymerase chain reaction testing.

RESULTS

The study was composed of 8889 vaccinated patients (4491 men [50.5%]; mean [SD] age, 52.4 [16.9] years) and 88 898 unvaccinated patients (44 748 men [50.3%]; mean [SD] age, 51.7 [16.7] years). The incidence rate ratio of SARS-CoV-2 infection in the vaccinated vs unvaccinated control cohorts was 0.26 (95% CI, 0.20-0.34) (60 of 8889 vaccinated patients vs 2236 of 88 898 unvaccinated individuals), which corresponds to an effectiveness of 73.6% (95% CI, 65.9%-79.9%) and a 3.73-fold reduction in SARS-CoV-2 infections.

CONCLUSIONS AND RELEVANCE

This study's findings are consistent with the clinical trial-reported efficacy of Ad26.COV2.S and the first retrospective analysis, suggesting that the vaccine is effective at reducing SARS-CoV-2 infection, even with the spread of variants such as Alpha or Delta that were not present in the original studies, and reaffirm the urgent need to continue mass vaccination efforts globally.

Cerebral Venous Sinus Thrombosis is not Significantly Linked to COVID-19 Vaccines or Non-COVID Vaccines in a Large Multi-State Health System

Objective

To assess the association of COVID-19 vaccines and non-COVID-19 vaccines with cerebral venous sinus thrombosis (CVST).

Materials and method

We retrospectively analyzed a cohort of 771,805 vaccination events across 266,094 patients in the Mayo Clinic Health System between 01/01/2017 and 03/15/2021. The primary outcome was a positive diagnosis of CVST, identified either by the presence of a corresponding ICD code or by an NLP algorithm which detected positive diagnosis of CVST within free-text clinical notes. For each vaccine we calculated the relative risk by dividing the incidence of CVST in the 30 days following vaccination to that in the 30 days preceding vaccination.

Results

We identified vaccination events for all FDA-approved COVID-19 vaccines including Pfizer-BioNTech (n = 94,818 doses), Moderna (n = 36,350 doses) and Johnson & Johnson - J&J (n = 1,745 doses). We also identified vaccinations events for 10 common FDA-approved non-COVID-19 vaccines (n = 771,805 doses). There was no statistically significant difference in the incidence rate of CVST in 30-days before and after vaccination for any vaccine in this population. We further found the baseline CVST incidence in the study population between 2017 and 2021 to be 45 to 98 per million patient years.

Conclusions

This real-world evidence-based study finds that CVST is rare and is not significantly associated with COVID-19 vaccination in our patient cohort. Limitations include the rarity of CVST in our dataset, a relatively small number of J&J COVID-19 vaccination events, and the use of a population drawn from recipients of a SARS-CoV-2 PCR test in a single health system.

Mapping each pre-existing condition's association to short-term and long-term COVID-19 complications

Understanding the relationships between pre-existing conditions and complications of COVID-19 infection is critical to identifying which patients will develop severe disease. Here, we leverage ~1.1 million clinical notes from 1803 hospitalized COVID-19 patients and deep neural network models to characterize associations between 21 pre-existing conditions and the development of 20 complications (e.g. respiratory, cardiovascular, renal, and hematologic) of COVID-19 infection throughout the course of infection (i.e. 0–30 days, 31–60 days, and 61–90 days). Pleural effusion was the most frequent complication of early COVID-19 infection (89/1803 patients, 4.9%) followed by cardiac arrhythmia (45/1803 patients, 2.5%). Notably, hypertension was the most significant risk factor associated with 10 different complications including acute respiratory distress syndrome, cardiac arrhythmia, and anemia. The onset of new complications after 30 days is rare and most commonly involves pleural effusion (31–60 days: 11 patients, 61–90 days: 9 patients). Lastly, comparing the rates of complications with a propensity-matched COVID-negative hospitalized population confirmed the importance of hypertension as a risk factor for early-onset complications. Overall, the associations between pre-COVID conditions and COVID-associated complications presented here may form the basis for the development of risk assessment scores to guide clinical care pathways.

Building a best-in-class automated de-identification tool for electronic health records through ensemble learning

The presence of personally identifiable information (PII) in natural language portions of electronic health records (EHRs) constrains their broad reuse. Despite continuous improvements in automated detection of PII, residual identifiers require manual validation and correction. Here, we describe an automated de-identification system that employs an ensemble architecture, incorporating attention-based deep-learning models and rule-based methods, supported by heuristics for detecting PII in EHR data. Detected identifiers are then transformed into plausible, though fictional, surrogates to further obfuscate any leaked identifier. Our approach outperforms existing tools, with a recall of 0.992 and precision of 0.979 on the i2b2 2014 dataset and a recall of 0.994 and precision of 0.967 on a dataset of 10,000 notes from the Mayo Clinic. The de-identification system presented here enables the generation of de-identified patient data at the scale required for modern machine-learning applications to help accelerate medical discoveries.

Spleen in the thorax: A case report on traumatic diaphragmatic rupture

•

Diaphragmatic rupture is a rare complication of abdominal trauma.

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Herniation of abdominal contents can occur following diaphragmatic rupture.

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Spleen was present in the thorax in a case following blunt abdominal trauma.

•

Care should be taken when inserting a chest tube in suspected cases.

•

Treatment is surgical via Laparotomy or Thoracotomy.

Introduction

Most of the cases of diaphragmatic rupture occur following abdominal trauma and herniation of abdominal organs into the thorax can occur.

Presentation of case

Twenty three years old male presented after a blunt abdominal trauma following a road traffic accident. Investigations revealed a left sided diaphragmatic rupture with herniation of spleen and stomach into the left hemithorax. Surgical repair of the defect was done and splenectomy had to be done due to extensive splenic laceration. Two third of the spleen was found in the left hemithorax.

Discussion

Diagnosis of diaphragmatic rupture can be missed in cases of polytrauma. High clinical suspicion with aids from imaging modalities help in the diagnosis. In suspicion of herniation of abdominal contents into the thorax, one should be careful in insertion of chest tube in view of damaging the herniated organs. Treatment is surgical repair and reduction of herniated contents.

Conclusion

Although a rare entity, diaphragmatic rupture can occur in cases of abdominal trauma. High clinical suspicion with imaging helps in the diagnosis.

Augmented curation of clinical notes from a massive EHR system reveals symptoms of impending COVID-19 diagnosis

Understanding temporal dynamics of COVID-19 symptoms could provide fine-grained resolution to guide clinical decision-making. Here, we use deep neural networks over an institution-wide platform for the augmented curation of clinical notes from 77,167 patients subjected to COVID-19 PCR testing. By contrasting Electronic Health Record (EHR)-derived symptoms of COVID-19-positive (COVIDpos; n = 2,317) versus COVID-19-negative (COVIDneg; n = 74,850) patients for the week preceding the PCR testing date, we identify anosmia/dysgeusia (27.1-fold), fever/chills (2.6-fold), respiratory difficulty (2.2-fold), cough (2.2-fold), myalgia/arthralgia (2-fold), and diarrhea (1.4-fold) as significantly amplified in COVIDpos over COVIDneg patients. The combination of cough and fever/chills has 4.2-fold amplification in COVIDpos patients during the week prior to PCR testing, in addition to anosmia/dysgeusia, constitutes the earliest EHR-derived signature of COVID-19. This study introduces an Augmented Intelligence platform for the real-time synthesis of institutional biomedical knowledge. The platform holds tremendous potential for scaling up curation throughput, thus enabling EHR-powered early disease diagnosis.

Augmented curation of clinical notes from a massive EHR system reveals symptoms of impending COVID-19 diagnosis

Understanding temporal dynamics of COVID-19 symptoms could provide fine-grained resolution to guide clinical decision-making. Here, we use deep neural networks over an institution-wide platform for the augmented curation of clinical notes from 77,167 patients subjected to COVID-19 PCR testing. By contrasting Electronic Health Record (EHR)-derived symptoms of COVID-19-positive (COVID_pos; n = 2,317) versus COVID-19-negative (COVID_neg; n = 74,850) patients for the week preceding the PCR testing date, we identify anosmia/dysgeusia (27.1-fold), fever/chills (2.6-fold), respiratory difficulty (2.2-fold), cough (2.2-fold), myalgia/arthralgia (2-fold), and diarrhea (1.4-fold) as significantly amplified in COVID_pos over COVID_neg patients. The combination of cough and fever/chills has 4.2-fold amplification in COVID_pos patients during the week prior to PCR testing, in addition to anosmia/dysgeusia, constitutes the earliest EHR-derived signature of COVID-19. This study introduces an Augmented Intelligence platform for the real-time synthesis of institutional biomedical knowledge. The platform holds tremendous potential for scaling up curation throughput, thus enabling EHR-powered early disease diagnosis.

Case report of eventration of diaphragm due to an unknown febrile illness causing phrenic nerve palsy and other multiple nerve palsies

INTRODUCTION

Diaphragmatic eventration can be congenital or acquired. Diagnosis is delayed due to no symptoms or very mild ones and is generally done by imaging modalities. This condition is managed by plication of the affected part of diaphragm by various surgical approaches.

PRESENTATION OF CASE

A forty seven years lady presented with one year long history of abdominal pain, bloating and fullness after meals who was being treated in line of peptic acid disorder. She had developed bilateral foot drop after typhoid fever at seventeen years of age. Clinical examination and imaging with chest x-ray, chest ultrasound and computed tomography scan suggested eventration of left hemidiaphragm. Plication of eventration of left hemidiaphragm was done via mini thoracotomy of the left thorax. There were no postoperative complications and she was discharged on the sixth postoperative day.

DISCUSSION

Acquired eventration of diaphragm is commonly due to traumatic phrenic nerve palsy but rarely can be associated with a history of infection causing nerve palsies. Thoracic ultrasound is an emerging modality for diagnosis supporting X-rays and CT Scans. Plication of eventration with minimally invasive techniques has less number of hospital stay and less pain compared to open approaches.

CONCLUSION

Non-traumatic diaphragmatic eventration due to acquired phrenic nerve palsy following an unknown febrile illness is a rare case to be reported in Nepal. The aim of treatment is expansion of intra-thoracic space which is done by plication of the diaphragm.

Identification of immunohistochemical prognostic markers for survival after resection of pulmonary metastases from colorectal carcinoma

BACKGROUND

Although aggressive resection of pulmonary metastases prolongs the survival of patients with metastatic colorectal cancer, there is a need for predictive pathologic parameters to understand the key molecular events of metastatic progression. The aim of this study was to verify immunohistochemical markers in addition to established clinical parameters after surgery.

METHODS

From our subset of patients undergoing resection of pulmonary metastases from metastatic colorectal carcinoma, we analyzed 39 patients (23 men and 16 women) between 2003 and 2007. Only patients who met the criteria for a potentially curative operation were included. All patients were analyzed with regard to age and sex, primary tumor location, stage of the primary tumor, history of hepatic metastases, number of pulmonary metastases, pre-thoracotomy carcinoembryonic (CEA) serum antigen level, and the presence of thoracic lymph node metastasis. Furthermore, we immunohistochemically investigated the expression of vascular endothelial growth factor (VEGF)-D, FBJ murine osteosarcoma viral oncogene homolog B (FOS-B), and melanoma antigen (MAGE)-A in the surgical specimens of pulmonary metastatic lesions.

RESULTS

The overall 3-year survival was 50.6 %. A significantly longer survival was observed with multivariate analysis in patients with a pre-thoracotomy serum carcinoembryonic antigen level of no more than 4.2 ng/mL ( P = 0.001), and Dukes stage A or B primary tumor ( P = 0.001). A significantly longer recurrence-free survival was observed with multivariate analysis in patients without thoracic lymph node involvement compared to patients with pulmonary and/or mediastinal lymph node metastases ( P = 0.006). The stage of the primary tumor remained significant ( P = 0.029), and FOS-B expression in tumor cells showed a trend towards favorable recurrence-free survival after pulmonary metastasectomy ( P = 0.059). No statistically significant difference was found in the overall survival rate or recurrence-free survival rate of patients with expression of VEGF-D or MAGE-A antigen in pulmonary metastatic tumor cells.

CONCLUSIONS

Our results suggest that in addition to clinically prognostic factors, FOS-B expression has a debatable impact on patient survival. We conclude that the evaluation of molecular and clinical prognostic parameters at the time of pulmonary metastasectomy offers a greater understanding of the metastatic process and provides important information for patient selection.

3. Internationales Symposium: „Autologe Transfusion - Von der Euphorie zur Ratio: Praktisches Handeln aus wissenschaftlicher Sicht” (Teil III)Does Hemodilution Enhance Coagulability?

Recent publications reported enhanced coagulability in hemodilution determined by TEG. In contrast, earlier reports have shown prolongation of in-vivo bleeding time in anemia. In order to take a closer look at this discrepancy undiluted and diluted anticoagulated blood samples (20 % with saline solution, hydroxyl-ethyl starch 6 % (HES), autologous platelet poor plasma (PPP)) were investigated by TEG (n = 10), ball (n = 10), and hook coagulometer (n = 15) as well as tests simulating primary hemostasis ex vivo (Platelet Function Analyzer PFA-100, n = 10).

RESULTS

Dilution with plasma changed TEG parameters in a way, when started by recalcification of the blood sample, which is characteristic of enhanced coagulability (r decreased in all and k in 8 of 10 samples, maximal amplitude increased in 9 out of 10). With HES, changes in TEG parameters mainly indicated reduced coagulability (k increased in 7 out of 10, MA decreased in 10 out of 10). When the coagulation was additionally activated by PTT reagent (InTEG) the TEG parameters also mainly showed hypocoagulation with the three dilution solutions. Coagulation times with ball and hook coagulometers were significantly prolonged by dilution especially with saline (+ 25 % and + 17 %, p < 0.001). Dilution always significantly (often abnormally) prolonged closure time in PFA-100 (saline + 41 +/- 18 %, PPP + 37 +/- 20 %, HES + 69 +/- 24 %) demonstrating disturbance of primary hemostasis, particularly with HES.

CONCLUSIONS

From the results obtained it can be concluded that the changes in the classical TEG (without addition of PTT-reagent), suggesting an enhanced coagulability, may be caused methodically as they are also found with autologous PPP. On the other hand, a disturbance of the primary hemostasis in hemodilution has to be taken into account from the results seen with the PFA-100 and a number of published data.

Measurement of primary haemostasis using a pressure clamp technique

With the PFA-100 a sensitive and specific screening test for primary haemostasis has recently become available. An important part of the device is a capillary, providing a defined haemodynamic resistance for the perfusion of the aperture. A modified method to measure platelet function (VCP2) is presented in which the capillary essentially is replaced with an 'electronic capillary' by clamping the pressure/flow relationship.

RESULTS AND CONCLUSION

Closure time (CT) and blood volume (BV) as determined by PFA-100 and VCP2 correlated well within (r = 0.922 - 0.952) and between the two methods (r = 0.86). The test variability (CV) of CT could be significantly reduced in the VCP2 method (collagen/epi 3.9 vs. 5.9%, p<0.05; collagen/ADP 3.3 vs. 6.9%, p<0.001), thus considerably increasing test reliability and reducing test variance. In preliminary clinical studies the VCP2 system showed comparable sensitivity for vWD and slightly less sensitivity regarding ASA ingestion. The test spectrum of VCP2 could be extended to more thrombocytopenic samples (< or =20 000/microl) even in combination with low haematocrit levels (20%), thus perhaps permitting the determination of the bleeding risk in bone marrow hypoplasia. Additionally, the sensitivity and applicability can easily be adapted to the desired need only by software modifications.

Proteolysis of SNAP-25 isoforms by botulinum neurotoxin types A, C, and E: domains and amino acid residues controlling the formation of enzyme-substrate complexes and cleavage

Tetanus toxin and the seven serologically distinct botulinal neurotoxins (BoNT/A to BoNT/G) abrogate synaptic transmission at nerve endings through the action of their light chains (L chains), which proteolytically cleave VAMP (vesicle-associated membrane protein)/synaptobrevin, SNAP-25 (synaptosome-associated protein of 25 kDa), or syntaxin. BoNT/C was reported to proteolyze both syntaxin and SNAP-25. Here, we demonstrate that cleavage of SNAP-25 occurs between Arg198 and Ala199, depends on the presence of regions Asn93 to Glu145 and Ile156 to Met202, and requires about 1,000-fold higher L chain concentrations in comparison with BoNT/A and BoNT/E. Analyses of the BoNT/A and BoNT/E cleavage sites revealed that changes in the carboxyl-terminal residues, in contrast with changes in the amino-terminal residues, drastically impair proteolysis. A proteolytically inactive BoNT/A L chain mutant failed to bind to VAMP/synaptobrevin and syntaxin, but formed a stable complex (KD = 1.9 x 10(-7) M) with SNAP-25. The minimal essential domain of SNAP-25 required for cleavage by BoNT/A involves the segment Met146-Gln197, and binding was optimal only with full-length SNAP-25. Proteolysis by BoNT/E required the presence of the domain Ile156-Asp186. Murine SNAP-23 was cleaved by BoNT/E and, to a reduced extent, by BoNT/A, whereas human SNAP-23 was resistant to all clostridial L chains. Lys185Asp or Pro182Arg mutations of human SNAP-23 induced susceptibility toward BoNT/E or toward both BoNT/A and BoNT/E, respectively.

New NO-donors with antithrombotic and vasodilating activities, Part 17. Arylazoamidoximes and 3-arylazo-1,2,4-oxadiazol-5-ones

Seven arylazoamidoximes (3), six phenoxycarbonyl derivatives (4), and six 1,2,4-oxadiazol-5-ones (5) have been prepared and their structure and purity established by spectroscopy and elemental analysis. In the EI mass spectra ready elimination of NO from the title amidoximes was observed. A new addition reaction of 3a with hydrochloric acid to 4-chlorophenylhydro-azoamidoxime 7 is described. The compounds were tested for nitric oxide dependent biological properties, i.e. platelet aggregation, antithrombotic effects, and decrease in blood pressure. In arterioles of rats 5/19 compounds inhibited the formation of thrombi with a laser beam by > or = 20% 2 h after oral administration of 60 mg/kg. Among these are three amidoximes (3a, 3e, 3f), one phenoxycarbonyl derivative (4a), and one oxadiazolone (5a). With the 4-chlorophenylazoamidoxime 3c a long lasting (24 h) decrease of blood pressure in spontaneously hypertensive rats was observed. Microsomal fractions of rat liver oxidize arylazoamidoximes and generate nitric oxide (e.g. 3a and 3b). NO was measured by the oxyhemoglobin assay. The influence of SOD, pretreatment of the rats with dexamethasone, as well as kinetic parameters were determined. Type 3 compounds, therefore, are a new class of NO donors. Type 4 and 5 compounds function as their prodrugs.

Loss of in vitro cytotoxicity of cisplatin after storage as stock solution in cell culture medium at various temperatures

BACKGROUND

Cisplatin (cis-dichlorodiammineplatinum [II]) is one of the most potent and widely used cytotoxic drugs in cancer therapy. However, in vitro cytotoxicity assays often yield diverging results. Therefore, it is believed by many investigators that cisplatin is not effective in vitro. The authors investigated whether the experimental conditions used could be responsible for the diverging results.

METHODS

In vitro cytotoxicity assays were performed using the original cisplatin solution as distributed by the manufacturer or a 5-fold dilution of this in cell culture medium after storage for 2 weeks or 1 month at various temperatures (room temperature, 4 degrees C, and -20 degrees C).

RESULTS

The original solution of cisplatin retained the full cytotoxic potency for at least 1 month under all storage conditions tested. The highest loss of cytotoxicity resulted from storage of cisplatin in cell culture medium in which a >7-fold increase in the concentration that inhibits 50% occurred after 2 weeks' storage at room temperature. Solutions stored in culture medium at -20 degrees C retained full cytotoxic potency.

CONCLUSIONS

Cisplatin is a potent cytotoxic drug in vitro when stored under appropriate conditions. These findings are of relevance for in vitro studies with cisplatin.

New NO-donors with antithrombotic and vasodilating activities, Part 16. 3-Amino-1,2,4-oxadiazol-5-ones as prodrugs for hydroxyguanidines

Nineteen 4-substituted 1,2,4-oxadiazol-5-ones (6a-s) were prepared as prodrugs for lipophilic hydroxyguanidines which should be metabolized in vivo to nitric oxide. This hypothesis was tested indirectly by measuring the antithrombotic properties of these compounds 2 h after oral administration to rats (60 mg/kg). In mesenteric arterioles seven compounds moderately (> or = 10%) inhibited the formation of thrombi by a laser beam. Maximum effects were observed in 6c (4-pentyl) and 6f (4-benzyl). The lack of activity in the corresponding 2-pentyloxadiazolone 10c, where no formation of nitric oxide seems possible, indirectly suggests that the antithrombotic properties of the title compounds could be mediated by the in vivo formation of nitric oxide.