Great Debates: Surgery or Watch and Wait After Total Neoadjuvant Therapy for Rectal Cancer

Locally advanced rectal cancer has traditionally been treated with multimodal therapy including neoadjuvant chemoradiotherapy followed by surgical resection. More recent data suggests that in appropriate patients, total neoadjuvant treatment (TNT) makes it possible to adopt a "watch and wait" approach. Advocates for watch and wait argue that patients with a complete or near-complete clinical response to TNT have comparable overall and disease-free survival to their counterparts who undergo surgical resection, and also have a better quality of life, fewer complications, and potentially avoid a stoma. The dogma of surgery as regional curative intent therapy has been challenged by similar recurrence rates among those treated with total mesorectal excision (TME) and those treated with watch and wait. Furthermore, those who develop local recurrence in the watch and wait groups are equally salvageable, either by surgery, brachytherapy, or chemotherapy. While watch and wait is not appropriate in all patients, this manuscript highlights the benefits and drawbacks of both therapeutic modalities.

Renal point-of-care ultrasound performed by ED staff with limited training and 30-day outcomes in patients with renal colic

BACKGROUND AND AIM

Emergency Department (ED) renal point-of-care ultrasound (PoCUS) in renal colic by accredited specialists has good prognostic value. This may not be generalizable to under-resourced EDs. We investigated PoCUS in renal colic in our ED with lesser training.

METHODS

We performed a single-centre health records review of adult ED patients with renal colic and PoCUS. Patients were managed by a non-ED specialist/resident doctor with no POCUS accreditation in consultation with an attending. These doctors attended a 3.5-h training session conducted by accredited attendings to examine hydronephrosis. They needed to verify their PoCUS findings with an attending during the first two weeks of their six-month posting before performing it independently. The primary outcome was 30-day urological procedures in hydronephrotic vs. non-hydronephrotic groups. Secondary outcomes were the distribution of primary outcome with grades of hydronephrosis, 30-day ED nephrolithiasis-related reattendances in hydronephrotic vs. non-hydronephrotic groups and its distribution with grades of hydronephrosis. We compared outcomes using Fisher's exact test. We also reported crude odds ratio (COR) and 95% CI of primary outcome between hydronephrotic vs. non-hydronephrotic groups. p values ≤ 0.05 were significant.

RESULTS

We recruited 651 patients; 160 (24.6%) without and 491 (75.4%) with hydronephrosis. Rates of grades of hydronephrosis were: mild (76.6%), moderate (13.8%), severe (1.2%) and undifferentiated (8.4%). There was a difference in 30-day urological procedures (rates [95% CI]) in hydronephrotic vs. non-hydronephrotic groups, 11.2 [8.7-14.0]% vs. 2.5 [1.0-6.3]%; p < 0.001; COR (95% CI) 4.9 (1.8-13.8); p = 0.002. Increasing 30-day urological procedural rates were associated with increasing grade of hydronephrosis [no: 2.5%, mild: 7.7%, moderate: 23.5%, severe: 67.0% and undifferentiated: 14.6%; p < 0.001]. No differences occurred in other secondary outcomes.

CONCLUSIONS

Renal PoCUS could be performed by non-ED specialist/resident doctors to identify patients without hydronephrosis who rarely required urological intervention. Hydronephrotic patients could benefit from further risk stratification.

Ambient and personal dose assessment of a container inspection site using a mobile X-ray system

Ambient monitor and phantom studies of absorbed and effective doses by TLDs were carried out in a non-intrusive inspection station for containers, Terminal I, of Taichung harbor, Taiwan. The doses from the X-ray scan in the control room and driver waiting room, located outside of the radiation control area, were quite small and could not be distinguished from the natural background radiation. The doses in the driver cab and the inspector cab of the X-ray scan car were also within background radiation levels. The protection wall, a 40-cm thick concrete barrier, can effectively attenuate the intensity of the primary X-ray scan. The possible effective dose of a person in the container or trailer is about 3.15 ± 0.23 μSv/scan and 2.31 ± 0.38 μSv/scan. This dose is below the annual background dose. If someone was to be scanned by the X-ray, the effective dose would be at an acceptable level.

Mifepristone acts as progesterone antagonist of non-genomic responses but inhibits phytohemagglutinin-induced proliferation in human T cells

BACKGROUND

Progesterone is an endogenous immunomodulator that suppresses T cell activation during pregnancy. The stimulation of membrane progesterone receptors (mPRs) would seem to be the cause of rapid non-genomic responses in human peripheral T cells, such as an elevation of intracellular calcium ([Ca(2+)](i)) and decreased intracellular pH (pH(i)). Mifepristone (RU486) produces mixed agonist/antagonist effects on immune cells compared with progesterone. We explored whether RU486 is an antagonist to mPRs and can block rapid non-genomic responses and the induction by phytohemagglutinin (PHA) of cell proliferation.

METHODS

Human male peripheral T cell responses in terms of pH(i) and [Ca(2+)](i) changes were measured using the fluorescent dyes, 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) and fura-2, respectively. Expression of mPR mRNA was determined by RT-PCR analysis. Cell proliferation and cell toxicity were determined by [(3)H]-thymidine incorporation and MTT assay, respectively.

RESULTS

The mRNAs of mPRalpha, mPRbeta and mPRgamma were expressed in T cells. RU486 blocked progesterone-mediated rapid responses including, the [Ca(2+)](i) increase and pH(i) decrease, in a dose related manner. RU486 did not block, but enhanced, the inhibitory effect of progesterone on PHA induced cell proliferation. RU486 alone inhibited proliferation induced by PHA and at >25 microM seems to be cytotoxic against resting T cells (P < 0.01).

CONCLUSIONS

RU486 is antagonistic to the rapid mPR-mediated non-genomic responses, but is synergistic with progesterone with respect to the inhibition of PHA-induced cell proliferation. Our findings shine new light on RU486's clinical application and how this relates to the non-genomic rapid physiological responses caused by progesterone.

Cutting edge: systemic inhibition of angiogenesis underlies resistance to tumors during acute toxoplasmosis

The ability of various infections to suppress neoplastic growth has been well documented. This phenomenon has been traditionally attributed to infection-induced concomitant, cell-mediated antitumor immunity. We found that infection with Toxoplasma gondii effectively blocked neoplastic growth of a nonimmunogenic B16.F10 melanoma. Moreover, this effect was independent of cytotoxic T or NK cells, production of NO by macrophages, or the function of the cytokines IL-12 and TNF-alpha. These findings suggested that antitumor cytotoxicity was not the primary mechanism of resistance. However, infection was accompanied by strong, systemic suppression of angiogenesis, both in a model system and inside the nascent tumor. This suppression resulted in severe hypoxia and avascular necrosis that are incompatible with progressive neoplastic growth. Our results identify the suppression of tumor neovascularization as a novel mechanism critical for infection-induced resistance to tumors.

Cardiac output and renal function during insulin hypertension in Sprague-Dawley rats

Hyperinsulinemia has been reported to cause hypertension in rats; however, the renal and hemodynamic mechanisms are not known. In this study, changes in renal function, cardiac output (CO), and total peripheral resistance (TPR) were measured during chronic insulin infusion in eight rats (approximately 350 g). After a 4-day control period, a 7-day insulin infusion was begun (1.5 mU.kg-1.min-1 iv), together with glucose (22 mg.kg-1.min-1 iv) to prevent hypoglycemia. Mean arterial pressure (MAP), CO, TPR, and heart rate were measured 24 h/day. MAP increased from 92 +/- 1 to 100 +/- 2 mmHg on day 1 and was 108 +/- 4 mmHg by day 7 of insulin. CO tended to decrease during insulin infusion, although not significantly, averaging 94 +/- 4% of the control value of 121 +/- 7 ml/min. Heart rate did not change significantly from the control value of 384 +/- 8 beats/min. TPR increased significantly to 122 +/- 11% of control by day 7. In five rats, glomerular filtration rate and effective renal plasma flow decreased to 73 +/- 4 and 66 +/- 5% of control, respectively, during insulin. Urinary sodium excretion averaged 2.6 +/- 0.1 and 2.7 +/- 0.1 meq/day during the control and insulin-infusion periods, respectively. These results indicate that insulin hypertension in rats is initiated by an increase in TPR rather than by increased CO. Also, the fact that sodium balance was maintained at elevated arterial pressure suggests that the ability of the kidneys to excrete sodium was impaired chronically during insulin infusion.

The multiple-indicator dilution technique for characterization of normal and retrograde flow in once-through rat liver perfusions

The technique of normal and retrograde rat liver perfusion has been widely used to probe zonal differences in drug-metabolizing activities. The validity of this approach mandates the same tissue spaces being accessed by substrates during both normal and retrograde perfusions. Using the multiple-indicator dilution technique, we presently examine the extent to which retrograde perfusion alters the spaces accessible to noneliminated references. A bolus dose of 51Cr-labeled red blood cells, 125I-albumin, 14C-sucrose and 3H2O was injected into the portal (normal) or hepatic (retrograde) vein of rat livers perfused at 10 ml per min per liver. The outflow perfusate was serially collected over 220 sec to characterize the transit times and the distribution spaces of the labels. During retrograde perfusion, red blood cells, albumin and sucrose profiles peaked later and lower than during normal perfusion, whereas the water curves were similar. The transit times of red blood cells, albumin and sucrose were longer (p less than 0.005), whereas those for water did not change. Consequently, retrograde flow resulted in significantly larger sinusoidal blood volumes (45%), albumin Disse space (42%) and sucrose Disse space (25%) than during normal flow, whereas the distribution spaces for total and intracellular water remained unaltered. The distension of the vascular tree was confirmed by electron microscopy, by which occasional isolated foci of widened intercellular recesses and spaces of Disse were observed. Cellular ultrastructure was otherwise unchanged, and there was no difference found between normal and retrograde perfusion for bile flow rates, AST release, perfusion pressure, oxygen consumption and metabolic removal of ethanol, a substrate with flow-limited distribution, which equilibrates rapidly with cell water (hepatic extraction ratios were virtually identical: normal vs. retrograde, 0.50 vs. 0.48 at 6 to 7.4 mM input concentration). These findings suggest that the functional and metabolic capacities of the liver remain unperturbed during retrograde perfusion, rendering the technique suitable for the investigation of zonal differences in drug-metabolizing enzymes.

Effects of perfusate flow rate on measured blood volume, disse space, intracellular water space, and drug extraction in the perfused rat liver preparation: characterization by the multiple indicator dilution technique

The effect of hepatic blood flow on the elimination of several highly cleared substrates was studied in the once-through perfused rat liver preparation. A constant and low input concentration of ethanol (2.0 mM), [14C]-phenacetin and [3H]-acetaminophen (0.36 and 0.14 microM, respectively), or meperidine (8.1 microM) was delivered once-through the rat liver preparation in five flow periods (greater than 35 min each); control flow periods at 12 ml/min were interrupted by flow changes to 8 or 16 ml/min. The steady-state hepatic availabilities (F or outflow survivals) at 12 ml/min were ethanol, 0.075 +/- 0.038; [14C]-phenacetin, 0.15 +/- 0.059; [3H]-acetaminophen, 0.34 +/- 0.051; meperidine, 0.047 +/- 0.017. Flow-induced changes were different among the compounds: with reduced flow (8 ml/min), F was decreased for ethanol (0.061 +/- 0.032) and [3H]-acetaminophen (0.28 +/- 0.051), as expected, but was increased for [14C]-phenacetin (0.20 +/- 0.068) and meperidine (0.05 +/- 0.03); with an elevation of flow (to 16 ml/min), F was increased for all compounds, as expected of shorter sojourn times: ethanol, 0.13 +/- 0.065; [14C]-phenacetin, 0.22 +/- 0.062; [3H]-acetaminophen, 0.43 +/- 0.063; meperidine, 0.055 +/- 0.022. A marked increase in F for ethanol had occurred when flow changed from 12 to 16 ml/min due to nonlinear metabolism; the latter was confirmed by a reduction in the extraction ratios at increasing concentrations (1.8 to 11.4 mM); this condition was not present for the other compounds. In order to explain the observations, we used the multiple indicator dilution technique to investigate the flow-induced behaviors of tissue distribution spaces of vascular and intracellular references in the perfused rat liver preparation.