DERIVATION AND VALIDATION OF A MACHINE LEARNING MODEL FOR THE PREVENTION OF UNPLANNED DIALYSIS

BACKGROUND

Approximately half of all patients with advanced chronic kidney disease (CKD) who progress to kidney failure initiate dialysis in an unplanned fashion which is associated with high morbidity, mortality, and healthcare costs. A novel prediction model designed to identify advanced CKD patients who are at high risk for developing kidney failure over short time frames (6-12 months) may help reduce the rates of unplanned dialysis and improve the quality of transitions from CKD to kidney failure.

METHODS

We performed a retrospective study employing machine learning random forest algorithms incorporating routinely collected age and sex data along with time-varying trends in laboratory measurements to derive and validate six- and 12-month kidney failure risk prediction models in the advanced CKD population. The models were comprehensively characterized in three independent cohorts in Ontario, Canada - derived in a cohort of 1,849 consecutive advanced CKD patients (mean [standard deviation] age 66 [15] years, eGFR 19 [7] mL/min/1.73m2), and validated in two external advanced CKD cohorts (n=1,356; age 69 [14] years, eGFR 22 [7] mL/min/1.73m2).

RESULTS

Across all cohorts, 55% of patients experienced kidney failure, of which 35% involved unplanned dialysis. The six- and 12-month models demonstrated excellent discrimination with area under the receiver operating characteristic curve of 0.88 (95%CI: 0.87-0.89) and 0.87 (95%CI: 0.86-0.87) along with high probabilistic accuracy with Brier scores of 0.10 (95%CI 0.09-0.10) and 0.14 (95%CI 0.13-0.14), respectively. The models were also well-calibrated and delivered timely alerts on a significant number of patients who ultimately initiated dialysis in an unplanned fashion. Similar results were found upon external validation testing.

CONCLUSION

These machine-learning models using routinely collected patient data accurately predict near-future kidney failure risk among the advanced CKD population, and retrospectively deliver advanced warning on a substantial proportion of unplanned dialysis events. Optimal implementation strategies still need to be elucidated.

Short Timeframe Prediction of Kidney Failure among Patients with Advanced Chronic Kidney Disease

BACKGROUND

Development of a short timeframe (6-12 months) kidney failure risk prediction model may serve to improve transitions from advanced chronic kidney disease (CKD) to kidney failure and reduce rates of unplanned dialysis. The optimal model for short timeframe kidney failure risk prediction remains unknown.

METHODS

This retrospective study included 1757 consecutive patients with advanced CKD (mean age 66 years, estimated glomerular filtration rate 18 mL/min/1.73 m2). We compared the performance of Cox regression models using (a) baseline variables alone, (b) time-varying variables and machine learning models, (c) random survival forest, (d) random forest classifier in the prediction of kidney failure over 6/12/24 months. Performance metrics included area under the receiver operating characteristic curve (AUC-ROC) and maximum precision at 70% recall (PrRe70). Top-performing models were applied to 2 independent external cohorts.

RESULTS

Compared to the baseline Cox model, the machine learning and time-varying Cox models demonstrated higher 6-month performance [Cox baseline: AUC-ROC 0.85 (95% CI 0.84-0.86), PrRe70 0.53 (95% CI 0.51-0.55); Cox time-varying: AUC-ROC 0.88 (95% CI 0.87-0.89), PrRe70 0.62 (95% CI 0.60-0.64); random survival forest: AUC-ROC 0.87 (95% CI 0.86-0.88), PrRe70 0.61 (95% CI 0.57-0.64); random forest classifier AUC-ROC 0.88 (95% CI 0.87-0.89), PrRe70 0.62 (95% CI 0.59-0.65)]. These trends persisted, but were less pronounced, at 12 months. The random forest classifier was the highest performing model at 6 and 12 months. At 24 months, all models performed similarly. Model performance did not significantly degrade upon external validation.

CONCLUSIONS

When predicting kidney failure over short timeframes among patients with advanced CKD, machine learning incorporating time-updated data provides enhanced performance compared with traditional Cox models.

The MedSafer Study-Electronic Decision Support for Deprescribing in Hospitalized Older Adults: A Cluster Randomized Clinical Trial

IMPORTANCE

Scalable deprescribing interventions may reduce polypharmacy and the use of potentially inappropriate medications (PIMs); however, few studies have been large enough to evaluate the impact that deprescribing may have on adverse drug events (ADEs).

OBJECTIVE

To evaluate the effect of an electronic deprescribing decision support tool on ADEs after hospital discharge among older adults with polypharmacy.

DESIGN, SETTING, AND PARTICIPANTS

This was a cluster randomized clinical trial of older (≥65 years) hospitalized patients with an expected survival of more than 3 months who were admitted to 1 of 11 acute care hospitals in Canada from August 22, 2017, to January 13, 2020. At admission, participants were taking 5 or more medications per day. Data analyses were performed from January 3, 2021, to September 23, 2021.

INTERVENTIONS

Personalized reports of deprescribing opportunities generated by MedSafer software to address usual home medications and measures of prognosis and frailty. Deprescribing reports provided to the treating team were compared with usual care (medication reconciliation).

MAIN OUTCOMES AND MEASURES

The primary outcome was a reduction of ADEs within the first 30 days postdischarge (including adverse drug withdrawal events) captured through structured telephone surveys and adjudicated blinded to intervention status. Secondary outcomes were the proportion of patients with 1 or more PIMs deprescribed at discharge and the proportion of patients with an adverse drug withdrawal event (ADWE).

RESULTS

A total of 5698 participants (median [range] age, 78 [72-85] years; 2858 [50.2%] women; race and ethnicity data were not collected) were enrolled in 3 clusters and were adjudicated for the primary outcome (control, 3204; intervention, 2494). Despite cluster randomization, there were group imbalances, eg, the participants in the intervention arm were older and had more PIMS prescribed at baseline. After hospital discharge, 4989 (87.6%) participants completed an ADE interview. There was no significant difference in ADEs within 30 days of discharge (138 [5.0%] of 2742 control vs 111 [4.9%] of 2247 intervention participants; adjusted risk difference [aRD] -0.8%; 95% CI, -2.9% to 1.3%). Deprescribing increased from 795 (29.8%) of 2667 control to 1249 (55.4%) of 2256 intervention participants [aRD, 22.2%; 95% CI, 16.9% to 27.4%]. There was no difference in ADWEs between groups. Several post hoc sensitivity analyses, including the use of a nonparametric test to address the low cluster number, group imbalances, and potential biases, did not alter study conclusions.

CONCLUSIONS AND RELEVANCE

This cluster randomized clinical trial showed that providing deprescribing clinical decision support during acute hospitalization had no demonstrable impact on ADEs, although the intervention was safe and led to improvements in deprescribing.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03272607.

ENZYMATIC ACTIVITY IN MICROSOMES, LIPID PEROXIDATION OF MICE HEPATOCYTES UNDER THE SODIUM FLUORIDE

Fluorine is one of the most widespread and necessary microelements for the body of animals and humans, which is necessary in a clearly limited amount. Different concentrations of fluorine can affect the state of lipid peroxidation, as well as the functional state of the microsomes of liver hepatocytes. The studies were carried out on mature Wistar rats weighing 180-220 g. Animals were inoculated with an aqueous solution of sodium fluoride once a day for 60 days at doses of 1/10, 1/100 and 1/1000 DL50, which was 20 mg/kg, 2 mg/kg and 0,2 mg/kg body weight. Control rats received drinking water. Each group consisted of 10 animals, the studies of indicators were carried out on days 10, 20, 30, 50 and 60. The induction of free radical processes by sodium fluoride was confirmed using a chemiluminescent reaction of blood serum, the amount of diene conjugates in rat liver tissue homogenates was assessed spectrophotometrically, the content of TBA reactants in rat liver tissue homogenates was determined by the reaction of malondialdehyde and thiobarbituric acid (TBA). The level of chiff bases was determined with a spectrofluorometer, subcellular fractions of the liver were isolated by the method of differentiated centrifugation. An increase in the level of the indicator at a dose of 1/10 and 1/100 DL50 of the intensity of lemiluminescence on the 30th day and its decrease on the 60th day was established.Increase in the activity of NAD (P) H-cytochrome c reductase in the microsomal fraction of the liver at the beginning of the study and a gradual decrease on the 50th and 60th days when using both dosages. The same dynamics was observed for NADH-cytochrome c reductase. With respect to diene conjugates of TBA-reactants and chiff bases, a tendency to increase was observed at all periods of the experiment. Indicators of cytochrome P-450 cytochrome b5 were increased up to 30 days and gradually decreased by 60 days. Long-term administration of sodium fluoride can cause the formation of toxic products and a decrease in the activity of enzymes of the microsomal membrane of hepatocytes.

COVID-SAFER: Deprescribing Guidance for Hydroxychloroquine Drug Interactions in Older Adults

BACKGROUND/OBJECTIVES

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection causes high morbidity and mortality in older adults with chronic illnesses. Several trials are currently underway evaluating the antimalarial drug hydroxychloroquine as a potential treatment for acute infection. However, polypharmacy predisposes patients to increased risk of drug‐drug interactions with hydroxychloroquine and may render many in this population ineligible to participate in trials. We aimed to quantify the degree of polypharmacy and burden of potentially inappropriate medications (PIMs) that older hospitalized adults are taking that would interact with hydroxychloroquine.

METHODS

We reanalyzed data from the cohort of patients 65 years and older enrolled in the MedSafer pilot study. We first identified patients taking medications with potentially harmful drug‐drug interactions with hydroxychloroquine that might exclude them from participation in a typical 2019 coronavirus disease (COVID‐19) therapeutic trial. Next, we identified medications that were flagged by MedSafer as potentially inappropriate and crafted guidance around medication management if contemplating the use of hydroxychloroquine.

RESULTS

The cohort contained a total of 1,001 unique patients with complete data on their home medications at admission. Of these 1,001 patients, 590 (58.9%) were receiving one or more home medications that could potentially interact with hydroxychloroquine, and of these, 255 (43.2%) were flagged as potentially inappropriate by the MedSafer tool. Common classes of PIMs observed were antipsychotics, cardiac medications, and antidiabetic agents.

CONCLUSION

The COVID‐19 pandemic highlights the importance of medication optimization and deprescribing PIMs in older adults. By acting now to reduce polypharmacy and use of PIMs, we can better prepare this vulnerable population for inclusion in trials and, if substantiated, pharmacologic treatment or prevention of COVID‐19. J Am Geriatr Soc 68:1636‐1646, 2020.

Building a CTU Orientation Handbook iPad® application for first-year residents

BACKGROUND

The General Internal Medicine Clinical Teaching Unit (CTU) is a challenging rotation for new residents and the optimal format of orientation has not been determined. We hypothesized that an iPad^® application (app) would be a useful reference tool after residents completed their traditional large group orientation.

METHODS

Postgraduate year 1 (PGY1) residents were sent a link to download the free app one week before the start of their rotation. A pre-usage survey at initial login collected basic demographics. Usage data was collected to determine the sections, duration, and the timeframe from which the app was utilized.

RESULTS

Pre-usage survey data revealed that 63% of participants were female, 69% felt the app would improve orientation, and 94% were comfortable using mobile technology for medical education. Usage data showed "Teaching Sessions and Schedules," "The Consult Note," and "Admission Orders" were the three sections most commonly used. The most usage was during the evening call shift (10pm to 6am), followed by the morning shift (6am to 5pm).

CONCLUSION

The CTU Orientation App was a useful supplement to the traditional orientation. Researchers may not be able to predict what content would be most valuable in an iPad^® app, thus pre-development needs-assessments and usage feedback are crucial.

Clinical factors contributing to high cost hospitalizations in a Canadian tertiary care centre

Background

Like much of the developed world, healthcare costs in Canada are rising. A small proportion of patients account for a large proportion of healthcare spending and much of this spending occurs in acute care settings. The purpose of our study was to determine potentially modifiable factors related to care processes that contribute to high-cost admissions.

Methods

Using a mixed-methods study design, factors contributing to high-cost admissions were identified from literature and case review. We defined pre- and post-admission factors contributing to high-cost admissions. Pre-admission factors included reason for admission (e.g. complex medical, elective surgery, trauma, etc.). Post-admission factors included medical complications, disposition delays, clinical services delays, and inefficient clinical decision-making. We selected a random sample of admissions in the top decile of inpatient cost from the Ottawa Hospital between January 1 and December 31, 2010. A single reviewer classified cases based on the pre- and post-admission factors. We combined this information with data derived from the Ottawa Hospital Data Warehouse to describe patient-level clinical and demographic characteristics and costs incurred.

Results

We reviewed 200 charts which represents ~5% of all high cost admissions within the Ottawa Hospital in 2010. Post-admission factors contributing to high-cost admissions were: complications (60%), disposition delays (53%), clinical service delays (39%), and inefficient clinical decision-making (13%). Further, these factors varied substantially across service delivery lines. The mean (standard deviation (SD)) cost per admission was $49,923 CDN ($45,773). The most common reason for admission was “complex medical” (49%) and the overall median (IQR) length of stay was 27 (18–48) days. Approximately 1 in 3 high cost admissions (29%) included time in the intensive care unit (ICU).

Conclusions

While high cost admissions often include time in ICU and have long lengths of stay, a substantial proportion of costs were attributable to complications and potentially preventable delays in care processes. These findings suggest opportunities exist to improve outcomes and reduce costs for this diverse patient population.

Effectiveness of an extended period of flashing lights and strategic signage to increase the salience of alcohol-gel dispensers for improving hand hygiene compliance

BACKGROUND

Multiple factors affect compliance with hand hygiene, including conspicuity of alcohol-gel dispensers. Previous studies have shown that flashing lights increase hand hygiene compliance; however, the durability of this effect has not been studied.

METHODS

We affixed flashing lights to hand sanitizer dispensers for a total of 6 weeks. Regression analysis was used to compare compliance rates between the beginning and end of the intervention. Our secondary objective was to determine whether compliance rates in cold weather could be improved by adding a sign separated in time and space from the dispensers.

RESULTS

Flashing lights improved hand hygiene compliance from 11.8% to 20.7%, and this effect was unchanged over the 6-week study period. Fully charged lights resulted in a greater compliance increase. A preemptive sign did not have a significant effect on hand hygiene rates nor did absolute temperatures.

CONCLUSIONS

Flashing lights are a simple, inexpensive way of improving hand hygiene. Brighter lights appear to have a greater effect; however, this must be balanced with annoyance in specific settings. Temperature did not have a significant effect; however, this may be because the relationship does not fit a linear model. Other interventions, such as signs, may need to be tailored specifically to individual hospital environments.

Gamma-secretase inhibitor does not modulate angiogenesis in colon adenocarcinoma in obese mice

BACKGROUND

Notch is a signaling molecule which plays a role in angiogenesis and γ-secretase is required for processing of Notch. In this study, we investigated the effect of γ-secretase inhibitor (DAPT) on tumor angiogenesis in diet-induced obese mice.

METHODS

18 mice were divided into three groups; control, obese (diet-induced) and obese+DAPT. After 15 weeks, the obese mice were subjected for tumor induction of CT26 colon adenocarcinoma cells (5 x 105 cells). When the tumor size reached approximately 350 ± 50 mm3, half of the obese animals received DAPT (10mg/kg/day) subcutaneously. Blood samples were taken after 14 days and the tumors harvested for immunohistochemical staining and capillary density were reported as CD31 positive cells/mm2.

RESULTS

The obese animals had higher serum leptin and NO concentrations, while, serum VEGF and VEGFR-1 concentrations were not different compare to control group. Administration of DAPT in obese mice significantly reduced serum VEGFR-1 and leptin concentrations and increased serum NO level (p < 0.05). Capillary density in the tumors of obese animals was not different compare to control groups. DAPT administration could not alter capillary density in the tumors.

CONCLUSION

Administration of DAPT in obese mice altered serum angiogenic factors, however, it could not modulate tumor angiogenesis in diet-induced obese mice (Fig. 4, Ref. 26).

Systemic administration of ghrelin did not restore angiogenesis in hindlimb ischemia in control and diet-induced obese mice

BACKGROUND

Ghrelin is a novel growth hormone releasing peptide that mainly regulates food intake and energy homeostasis, however, recently, it is indicated that it may be closely related with physiological and/or pathological angiogenesis.

OBJECTIVES

The objective of the present study was to evaluate the effect of systemic ghrelin administration on angiogenesis in hindlimb ischemia in normal and diet-induced obese mice.

METHODS

24 male C57BL/6 mice were fed with high-fat diet (HFD) or standard for 14 weeks. Then, the mice underwent unilateral hindlimb ischemia. Next, each group was divided into the two subgroups: treatment with ghrelin (100 µg/kg, twice daily, Sc) or without treatment. After 10 days, the animals were sacrificed, blood samples were taken and the gastrocnemius muscles removed.

RESULTS

There was no significant difference in capillary/fiber ratio in hind limb ischemia between obese and control groups. Administration of ghrelin reduced serum nitric oxide (NO) and leptin and increased vascular endothelial growth factor (VEGF) concentrations in obese mice, however, did not change the capillary/fiber ratio in ischemic legs.

CONCLUSION

Systemic administration of ghrelin did not restore angiogenesis in hindlimb ischemia in control and diet-induced obese mice (Fig. 4, Ref. 35).

A study of the efficacy of flashing lights to increase the salience of alcohol-gel dispensers for improving hand hygiene compliance

BACKGROUND

Many interventions have been implemented to improve hand hygiene compliance, each with varying effects and monetary costs. Although some previous studies have addressed the issue of conspicuousness, we found only 1 study that considered improving hand hygiene by using flashing lights.

METHOD

Our attention theory-based hypothesis tested whether a simple red light flashing at 2-3 Hz affixed to the alcohol gel dispensers, within the main hospital entrance, would increase hand hygiene compliance over the baseline rate. Baseline and intervention observations were completed over five 60-minute periods (Monday-Friday) from 7:30 to 8:30 AM using a covert observation method.

RESULTS

Baseline hand hygiene compliance was 12.4%. Our intervention increased compliance to 23.5% during cold weather and 27.1% during warm weather. Overall, our pooled compliance rate increased to 25.3% (P < .0001).

CONCLUSIONS

A simple, inexpensive flashing red light affixed to alcohol gel dispensers was sufficiently salient to approximately double overall hand hygiene compliance within the main hospital entrance. We hypothesize that our intervention drew attention to the dispensers, which then reminded employees and visitors alike to wash their hands. Compliance was worse during cold days, presumably related to more individuals wearing gloves.

The effect of mebudipine on cardiac function and activity of the myocardial nitric oxide system in ischaemia-reperfusion injury in rats

Objectives

Previous studies have suggested that failure of the synthesis of nitric oxide is involved in the pathophysiology of myocardial ischaemia–reperfusion injury. In this study, we investigated the effect of mebudipine, a new dihydropyridine calcium channel blocker, on cardiac function and activity of the myocardial nitric oxide system in ischaemia–reperfusion injury in isolated rat hearts.

Methods

Forty male Wistar rats (250–300 g) were divided into four groups (n = 10): sham, control, vehicle and drug groups. The animals were anesthetised with sodium pentobarbital (6 mg/kg intraperitoneal). The hearts were quickly removed, mounted on a Longendorff apparatus and perfused with Krebs-Henseleit solution under constant pressure at 37°C. After 20 min stabilisation period, the ischaemic groups received 30 min global ischaemia and 120 min reperfusion. For the drug and vehicle groups, before ischaemia the hearts were perfused with mebudipine (10^-3 µM) or ethanol-enriched solution (0.01%) for 25 min, respectively. Myocardial function, and creatine kinase, lactate dehydogenase and total nitric oxide metabolite (nitrite and nitrate) levels were analysed.

Results

Cardiac functions had recovered significantly in the mebudipine group (p < 0.01). Furthermore, mebudipine remarkably reduced the levels of lactate dehydogenase and creatine kinase in the coronary effluent and increased myocardial nitric oxide metabolite levels compared with the control group.

Conclusion

Our results indicate that mebudipine reduced the intensity of myocardial ischaemia–reperfusion injury, and that activation of the myocardial nitric oxide system played an important role in this regard.

Role of peroxisome proliferator-activated receptor β agonist on angiogenesis in hindlimb ischemic diabetic rats

INTRODUCTION

Studies indicated that PPARβ agonists play a role in modulation of angiogenesis. In this study, we evaluated the effect of specific PPARβ agonist, GW0742, on angiogenesis and serum vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2), and nitrite concentrations in hindlimb ischemia in normal and diabetic rats.

METHODS

Hindlimb ischemic rats were divided into four groups: control, diabetic, control, and diabetic treated with GW0742 (n=7 each). Diabetes was induced by injection of streptozotocin (55mg/kg, ip). GW0742 was injected 1day after surgery (1mg/kg, sc). After 21days, blood samples were taken, and gastrocnemius muscles were harvested for immunohistochemistry.

RESULTS

GW0742 significantly increased serum nitrite and VEGFR-2 concentrations and VEGF-to-VEGFR-2 ratio in control and diabetic rats. Capillary density was lower in diabetic animals compared to the control, and GW0742 significantly restored the capillary density in the control and diabetic hindlimb ischemic rats.

CONCLUSION

PPARβ agonists restore skeletal muscle angiogenesis and can be considered for prevention and/or treatment of peripheral vascular complications in diabetic subjects.

Tumor suppressor LATS1 is a negative regulator of oncogene YAP

LATS (large tumor suppressor) or warts is a Ser/Thr kinase that belongs to the Ndr/LATS subfamily of AGC (protein kinase A/PKG/PKC) kinases. It is a tumor suppressor gene originally isolated from Drosophila and recently isolated from mice and humans. Drosophila or mice mutant for LATS develop tumors in various tissues. Recent studies in Drosophila demonstrate that LATS is a central player of an emerging tumor suppressor pathway called the Hippo-LATS/Warts pathway that suppresses tumor growth by regulating cell proliferation, cell growth, and cell death. Although tremendous progress has been made toward understanding the roles of LATS in tumorigenesis, the kinase substrates of LATS or downstream target proteins mediating LATS function remain largely unknown. In this study, we have provided convincing evidence that the LATS1 tumor suppressor can bind to and phosphorylate transcription regulator and oncogene YAP in vitro and in vivo. We have also identified HX(R/H/K)XX(S/T) as the consensus phosphorylation sequence for LATS/Ndr kinase substrates. Significantly, we have discovered that LATS1 inactivates YAP oncogenic function by suppressing its transcription regulation of cellular genes via sequestration of YAP in the cytoplasm after phosphorylation of YAP. Finally, by using microarray analysis, we have also identified many oncogenes or tumor suppressor genes up-regulated or down-regulated by YAP. These research findings will have profound impacts on our understanding of the molecular mechanism of the LATS tumor suppressor and the emerging Hippo-LATS/Warts pathway.

Antimetastatic efficacy of adjuvant gemcitabine in a pancreatic cancer orthotopic model

Gemcitabine is a promising new agent that has been recently studied for palliation of advanced (stage IV) unresectable pancreatic cancer. We hypothesized that adjuvant gemcitabine would reduce recurrence and metastases following surgical resection of pancreatic cancer. To test this hypothesis, we evaluated gemcitabine on a green fluorescent protein (GFP) transductant of the human pancreatic cancer cell line BxPC-3 (BxPC-3-GFP) using surgical orthotopic implantation (SOI) in nude mice. GFP enabled high resolution fluorescent visualization of primary and metastatic growth. Five weeks after SOI, the mice were randomized into three groups: Group I received exploratory laparotomy only. Group II underwent surgical resection of the pancreatic tumor without further treatment. Group III underwent tumor resection followed by adjuvant treatment with gemcitabine, 100 mg/kg every three days for a total of four doses, starting two days after resection. The mice were sacrificed at thirteen weeks following implantation and the presence and location of recurrent tumor was recorded. Gemcitabine reduced the recurrence rate to 28.6% compared to 70.6% with resection only (P = 0.02) and reduced metastatic events 58% in the adjuvant group compared to resection only. This study, demonstrating that gemcitabine is effective as adjuvant chemotherapy post-pancreatectomy, suggests this new indication of the drug clinically.

A highly metastatic Lewis lung carcinoma orthotopic green fluorescent protein model

The Lewis lung carcinoma has been widely used for many important studies. However, the subcutaneous transplant or orthotopic cell-suspension injection models have not allowed the expression of its full metastatic potential. A powerful new highly metastatic model of the widely-used Lewis lung carcinoma is reported here using surgical orthotopic implantation (SOI) of tumor fragments and enhanced green fluorescent protein (GFP) transduction of the tumor cells. To achieve this goal, we first developed in vitro a stable high-expression GFP transductant of the Lewis lung carcinoma with the pLEIN retroviral expression vector containing the enhanced Aequorea victoria GFP gene. Stable high-level expression of GFP was found maintained in vivo in subcutaneously-growing Lewis lung tumors. The in vivo GFP-expressing tumors were harvested and implanted as tissue fragments by SOI in the right lung of additional nude mice. This model resulted in rapid orthotopic growth and extensive metastasis visualized by GFP-expression. 100% of the animals had metastases on the ipsilateral diaphragmatic surface, contralateral diaphragmatic surface, contralateral lung parenchima, and in mediastinal lymph nodes. Heart metastases were visualized in 40%, and brain metastases were visualized in 30% of the SOI animals. Mice developed signs of respiratory distress between 10-15 days post-tumor implantation and were sacrificed. The use of GFP-transduced Lewis lung carcinoma transplanted by SOI reveals for the first time the high malignancy of this tumor and provides an important useful model for metastasis, angiogenesis and therapeutic studies.

Efficacy of intra-hepatectomy 5-FU on recurrence and metastasis of human hepatocellular carcinoma in nude mice

A novel intra-operative chemotherapy nude mouse model for human hepatocellular carcinoma (HCC) has been developed. Intra-peritoneal (i.p.) administration of 5-fluorouracil (5-FU) was begun 2 hr before hepatic resection of HCC and then continued post-operatively for 4 consecutive days. This regime, termed intra-hepatectomy chemotherapy (IHC), significantly prolonged animal survival compared with pre-operative 5-FU, neoadjuvant therapy, 5-FU post-operative adjuvant therapy, surgery alone, 5-FU without surgery, and the untreated control. The median survival of the intra-operative 5-FU-treated group was 127 days compared with 78 days for the neoadjuvantly-treated animals and 53 days for the control group (p<0.006). When all animals with neoadjuvant 5-FU treatment had died, 60% of the animals in the IHC group were still alive (p<0.011). Survival of all other treatment groups, including 5-FU without surgery, surgery alone, and adjuvant post-operative chemotherapy, was not significantly different from the untreated control group. Five animals in the IHC group were free of tumor when sacrificed at day 150 post-surgically. While 100% of animals in the control group had lymph nodes draining the liver involved with metastases, only 20% of animals in the IHC group had lymph node metastases. These data suggested that IHC therapy increased survival by preventing metastases of cancer cells not removed in the liver resection procedure. The results of this study indicate that IHC therapy for resection of HCC should be investigated clinically.

An orthotopic mouse model of remetastasis of human colon cancer liver metastasis

Whether liver metastases from colon cancer are capable of metastasizing to other sites is an important question in surgical oncology. To answer this question, we have developed a highly metastatic orthotopic transplant model of a liver metastasis from a human colon cancer patient in nude mice that targets the liver and lymph nodes. The metastatic human tumor was transplanted in athymic nude mice by surgical orthotopic implantation (SOI) of a liver metastasis from a colon cancer patient. The human colon tumor was then subsequently implanted in the colon by SOI or, in an additional series of nude mice, in the liver by surgical hepatic implantation (SHI). The mice were then explored over time for lymph node involvement beginning 10 days after implantation. After SOI, 100% of the animals had liver metastasis within 10 days, and subsequently, 19 days after SOI, all lymph nodes draining the liver were involved with metastasis without any retroperitoneal or lung tissue involvement. After SHI, all sites of lymphatic drainage of the liver, including portal, celiac, and mediastinal lymph nodes, were massively involved by metastasis in 100% of the animals as early as 10 days after tumor implantation on the liver. The results of this study demonstrate that liver metastases from colon cancer are capable of remetastasizing to other sites. This study thus suggests that in colon cancer patients with liver metastasis, mediastinal, celiac, and portal lymph node metastases originate from the liver metastasis and not, as previously thought, from primary colon cancer.

Antimetastatic intraoperative chemotherapy of human colon tumors in the livers of nude mice

We have developed a new antimetastatic chemotherapeutic strategy for combination with hepatic resection of human colon cancers in a high-metastasis nude mouse model. The new procedure involves i.p. administration of 5-fluorouracil (5-FU) 2 h before hepatic resection of the human colon tumors, with therapy continued postoperatively for 4 consecutive days. We termed this strategy neo-neoadjuvant chemotherapy. The regime significantly prolonged animal survival compared with preoperative 5-FU neoadjuvant therapy, 5-FU postoperative adjuvant therapy, surgery alone, 5-FU without surgery, or the untreated control. The median survival of neo-neoadjuvant i.p. 5-FU-treated group was 81 days, compared with 27 days for the control group (P < 0.009). The median survival of animals in the neoadjuvant group was 37 days (P < 0.021 compared with the control group). There was also a significant difference between the median survival of neo-neoadjuvant, and the neoadjuvant group (P < 0.031). When all animals in the control group had died, 70% of animals with neo-neoadjuvant and 60% of animals with neoadjuvant 5-FU were still alive (P < 0.003 and P < 0.011, respectively). When all animals with neoadjuvant 5-FU treatment had died, 70% of animals with neo-neoadjuvant treatment were still alive (P < 0.003). Survival of all other treatment groups, including 5-FU without surgery, surgery alone, and adjuvant postoperative chemotherapy, was not significantly different from the untreated control group. Two animals in the neo-neoadjuvant group were free of tumors when sacrificed at days 154 and 165 post surgery. Whereas 100% of animals in the control, 90% in the 5-FU alone, 70% in the surgery alone, 60% in the 5-FU adjuvant, and 40% in the neoadjuvant groups had metastases in the lymph nodes draining the liver, only 10% of animals in the neo-neoadjuvant group had metastases. These data suggest that the neo-neoadjuvant therapy increased survival by preventing metastasis of cancer cells not removed in the liver resection procedure. The results of this study indicate that the neo-neoadjuvant treatment strategy for resection of colon cancer liver metastasis should be explored clinically.

Minimal liver resection strongly stimulates the growth of human colon cancer in the liver of nude mice

Partial hepatectomy has been widely employed in clinical practice as the therapy of choice for primary and metastatic liver tumors. However, the recurrence rate after the treatment remains high, which is most likely due to the growth of residual microscopic lesions. Previous studies in murine models demonstrated that a 70% hepatectomy significantly accelerated the growth of ectopically implanted tumors. In this study, we reported the effect of partial hepatectomy on the growth of two human colon cancers (Co-3 and AC3603) implanted in the liver of nude mice using the technique of surgical implantation of histologically intact tumor tissue. Our results showed a dramatic acceleration of tumor growth following 30% partial hepatectomy, which resembles clinical procedures. Tumor volumes were assessed with calipers on day-15 by abdominal palpation and on day-30 at autopsy by direct measurement. For both Co-3 and AC3603, tumor volumes in the hepatectomized animals were significantly larger than the control at the above two time points (P < 0.001). The results demonstrate the stimulating effect of partial hepatectomy directly on the tumor growth in the liver, in contrast to previous studies on ectopic tumors. Furthermore, since conservative partial hepatectomy (30%) is normally used in clinical practice for surgical treatment of liver metastasis, the animal models presented here should be useful for the clinical investigation of the high recurrence rate of liver metastasis following partial hepatectomy.

A nude mouse model of massive liver and lymph node metastasis of human colon cancer

Liver and lymph nodes metastasis are the main causes of treatment failure for advanced colon cancer. However, currently-available animal models of human colon cancer do not demonstrate sufficient metastasis to represent highly malignant colon cancer that extensively metastasizes to these sites. A liver metastasis from a patient with highly malignant, poorly differentiated adenocarcinoma of the colon was established in nude mice by surgical orthotopic implantation to the mouse colon. The human origin of the tumor growing in nude mice was confirmed by in situ hybridization of human DNA. After 20 passages from the first implantation, massive liver and lymph nodes metastasis, occurred in 100% of the transplanted animals. Lymph nodes metastasis were found at the sites of lymph node drainage of the liver: celiac, portal and mediastinal lymph nodes. However no mesenteric and retroperitoneal nodes or lung tissue metastases were observed. Our data suggest that the mediastinal, celiac and hepatic lymph nodes metastases are derived form the liver metastasis, confirming the concept of metastasis of metastases or "remetastasis" of colon cancer.

Efficacy of recombinant methioninase in combination with cisplatin on human colon tumors in nude mice

The present treatment of colon cancer is based on 5-fluorouracil (5-FU). Despite promising results of combining leucovorin or levamisole with 5-FU, the 5-year survival rate of patients with advanced colon cancer has not increased significantly. Colon tumors in vitro have been shown previously to have an elevated requirement for methionine, suggesting a new therapeutic target. In this study, targeting the methionine dependence of colon tumors is effected by recombinant methioninase (rMETase), alone and in combination with cisplatin (CDDP). In vitro results demonstrated that CDDP and rMETase act synergistically on the human colon cancer cell line SW 620, with a combination index (CI) of 0.45, as well as on the human colon cancer cell line Colo 205 with a CI of 0.7. Human colon cancer lines HCT 15, HT 29, Colo 205, and SW 620 growing in nude mice were treated with rMETase to determine an effective dose for depletion of tumor methionine. rMETase at 15 units/g/day for 5 days depleted tumor methionine in all four tumor types to approximately 30% of untreated control. rMETase alone arrested growth of HCT 15 and HT29 in nude mice for 1 week after treatment termination. Colo 205 and SW 620 were partially arrested by rMETase. However, CDDP in combination with rMETase resulted in tumor regression of Colo 205 and growth arrest of SW 620 in nude mice. The ratio of the treated:control group (T:C) tumor weights for Colo 205 was 8% when CDDP was given on day-5, followed by treatment on days 5-9 with rMETase. This treatment schedule resulted in two of the six animals having no detectable tumor when the experiment was terminated on day 16. SW620 was resistant to CDDP alone and only partially sensitive to rMETase alone. However, when SW 620 was treated with rMETase from days-5 to -9 and CDDP on day-5, tumor growth was arrested. The results demonstrate that rMETase used simultaneously in combination with CDDP had significant antitumor efficacy in colon cancer in vitro and in vivo. The data suggest a novel and promising therapeutic approach by targeting the elevated methionine dependence of colon cancer.

Factors predicting chronic hepatic encephalopathy after distal splenorenal shunt: a multivariate analysis of clinical and hemodynamic variables

BACKGROUND

This study was aimed at evaluating several factors that promote chronic hepatic encephalopathy by multivariate analysis of data for patients with cirrhosis with good or moderate liver function submitted to distal splenorenal shunts.

METHODS

The study group comprised 131 patients: 55 had alcoholic and 76 nonalcoholic cirrhosis. Seventy patients were in Child's class A and 61 in class B. Cerebral function was assessed by a complete neurologic examination. Angiography with venous phase was performed before and within 1 month after the shunt operation. In 84 cases the original Warren technique was used and in 20 cases a Britton's modified procedure was used. Twenty-seven patients had distal splenorenal shunts with a splenopancreatic disconnection. Statistical analysis was performed by two multivariate analyses based on stepwise selection.

RESULTS

Thirty-nine patients died during a follow-up period of 51 +/- 32 months. Chronic encephalopathy occurred in 18 patients (14%). According to the multivariate analysis of the preoperative prognostic factors, only age (p = 0.0001) and albumin values (p = 0.0002) were independent predictive risk factors for chronic encephalopathy. In the multivariate analysis concerning the hemodynamic consequences of the selective shunts, independent risk factors promoting chronic encephalopathy were postoperative portal perfusion (p = 0.0001), postshunt portal pressure (p = 0.001), and surgical disconnection (p = 0.0064).

CONCLUSIONS

Our study has shown that chronic encephalopathy after selective shunt surgery is promoted by both clinical and hemodynamic factors. A better selection of the candidates for shunt surgery and prevention of the development of portal malcirculation by accurate surgical disconnection should further decrease the risk of chronic encephalopathy.