A Canadian Provincial Screening Program for Lynch Syndrome.

INTRODUCTION: Manitoba implemented the first Canadian provincial program of reflex screening through mismatch repair immunohistochemistry (MMR-IHC) for all colorectal cancers diagnosed at age 70 years or younger in December 2017. We evaluated compliance to universal reflex testing and for referrals to Genetics for individuals with MMR-deficient tumors. METHODS: We searched the provincial pathology database with "adenocarcinoma" in the colorectal specimen pathology reports between March 2018 and December 2020. We cross-referenced with paper and electronic records in the Program of Genetics and Metabolism to determine whether patients with MMR-deficient tumors had been referred for Genetic assessment and what proportion of patients and first-degree relatives accepted an appointment and genetic testing. We performed logistic regression analysis to identify predictors of testing. RESULTS: We identified 3,146 colorectal adenocarcinoma specimens (biopsies and surgical resections) from 1,692 unique individuals (mean age 68.66 years, male 57%). Of those aged 70 years or younger (n = 936), 89.4% received MMR-IHC screening. Individual pathologists (categorized by the highest, average, and lowest screening rates) were the biggest predictors of MMR-IHC screening on multivariable analysis (highest vs lowest: odds ratio 17.5, 95% confidence interval 6.05-50.67). While only 53.4% (n = 31) of 58 screen-positive cases were referred by pathologists for genetic assessment, other clinicians referred an additional 22.4% (n = 13), resulting in 75.8% overall referral rate of screen-positive cases. Thirteen (1.4%) patients (1.1%, aged 70 years or younger) were confirmed to experience Lynch syndrome through germline testing, and 8 first-degree relatives (an average of 1.6 per patient) underwent cascade genetic testing. DISCUSSION: The first Canadian Lynch syndrome screening program has achieved high rates of reflex testing.

Acute selective serotonin reuptake inhibitors regulate the dorsal raphe nucleus causing amplification of terminal serotonin release.

Selective serotonin reuptake inhibitors (SSRIs) were designed to treat depression by increasing serotonin levels throughout the brain via inhibition of clearance from the extracellular space. Although increases in serotonin levels are observed after acute SSRI exposure, 3-6 weeks of continuous use is required for relief from the symptoms of depression. Thus, it is now believed that plasticity in multiple brain systems that are downstream of serotonergic inputs contributes to the therapeutic efficacy of SSRIs. The onset of antidepressant effects also coincides with desensitization of somatodendritic serotonin autoreceptors in the dorsal raphe nucleus (DRN), suggesting that disrupting inhibitory feedback within the serotonin system may contribute to the therapeutic effects of SSRIs. Previously, we showed that chronic SSRI treatment caused a frequency-dependent facilitation of serotonin signaling that persisted in the absence of uptake inhibition. In this work, we use in vivo fast-scan cyclic voltammetry in mice to investigate a similar facilitation after a single treatment of the SSRI citalopram hydrobromide. Acute citalopram hydrobromide treatment resulted in frequency-dependent increases of evoked serotonin release in the substantia nigra pars reticulata. These increases were independent of changes in uptake velocity, but required SERT expression. Using microinjections, we show that the frequency-dependent enhancement in release is because of SERT inhibition in the DRN, demonstrating that SSRIs can enhance serotonin release by inhibiting uptake in a location distal to the terminal release site. The novel finding that SERT inhibition can disrupt modulatory mechanisms at the level of the DRN to facilitate serotonin release will help future studies investigate serotonin's role in depression and motivated behavior. In this work, stimulations of the dorsal raphe nucleus (DRN) evoke serotonin release that is recorded in the substantia nigra pars reticulata (SNpr) using in vivo fast-scan cyclic voltammetry. Systemic administration of a selective serotonin reuptake inhibitor (SSRI) causes both an increase in t1/2 and an increase in [5-HT]max in the SNpr. Local application of SSRI to the DRN recapitulates the increase in [5-HT]max observed in the SNpr without affecting uptake. Thus, SSRIs increase serotonin signaling via two distinct SERT-mediated mechanisms.

Radiographic predictors of muscle-invasive upper tract urothelial cancer: A Canadian cohort.

INTRODUCTION: Accurate diagnostic staging of upper tract urothelial cancer (UTUC) is challenging. Endoscopic staging is limited by its ability to provide adequate sampling of deeper layers of the ureter and renal pelvis. Further ability to accurately predict invasive disease would aid in better selecting the appropriate treatment for patients. We aimed to analyze the ability of preoperative cross-sectional radiologic findings to predict pathologic outcomes, including tumor grade, muscle-invasive disease, and presence of lymphovascular invasion (LVI). METHODS: All patients diagnosed with localized UTUC (cN0M0) who underwent nephroureterectomy between February 2012 and December 2018 in Manitoba, Canada, were identified. Preoperative radiologic characteristics, including the presence and severity of hydronephrosis, as well as tumor location were recorded. Patients' and pathologic characteristics were also recorded. Logistic regression analysis was used to assess the association between radiologic variables and pathologic outcomes at radical surgery. RESULTS: A total of 112 pathology reports of patients with UTUC were obtained. The median age was 70 years (range 50-87), and 58.8% of patients were men. On univariate analysis, ureteric location on computed tomography (odds ratio [OR] 2.240, 95% confidence interval [CU] 1.049- 4.783, p=0.037) and presence of hydronephrosis (OR 2.455, 95% CI 1.094-5.506, p=0.0029) were each independently associated with locally invasive disease (>pT2). No radiologic variables were found to be a predictor of adverse pathology on multivariable analysis. Only the presence of hydronephrosis was associated with high-grade disease on univariate analysis (OR 2.533, 95% CI 1.083-5.931, p=0.032). CONCLUSIONS: Our findings suggest a limited role for cross-sectional imaging in predicting the presence of high-grade disease, LVI, or locally advanced disease in UTUC.

Prostate Cancer Metastasis to Stomach: A Case Report and Review of Literature.

Metastatic prostate cancer is a common diagnosis with a protracted but terminal course. Gastrointestinal (GI) tract involvement is extremely rare, and reportedly portends a poor prognosis. It can present years after the initial prostate cancer diagnosis. Only fifteen cases of prostate cancer metastasis to the stomach have been reported in the literature. We report a case of a 72-year-old man with metastatic castration-resistant prostate cancer and extensive bony involvement. He presented a decade after the diagnosis of prostate cancer with signs of heartburn; a gastric biopsy was initially believed to represent primary gastric carcinoma, but subsequently a diagnosis of prostate cancer metastatic to the stomach was confirmed. This case highlights the importance of the provision of a pertinent clinical history and clinical differential diagnosis at the time of submission of surgical pathology specimens, as well as highlighting the need to have a low index of suspicion to pursue additional pathologic markers whenever a presumed second adenocarcinoma is noted in the context of a patient having a history of current or prior advanced-stage adenocarcinoma of another site. The correct diagnosis can shield the patient from the morbidity of inappropriate surgical or medical management.

Pathological reassessment of hyperplastic colon polyps in a city-wide pathology practice: implications for polyp surveillance recommendations.

BACKGROUND: Sessile serrated adenomas (SSAs) and hyperplastic polyps (HP) are the two most common types of serrated colon polyps (SCPs). SSAs are suspected to be the precursor lesions for many colorectal cancers, and hence there is an emphasis on their detection and removal. On the other hand, recent guidelines such as those from the European Union consider HPs of limited clinical significance. OBJECTIVE: Evaluate the reclassification rate of recently diagnosed HPs to SSAs and the predictors of such reclassification. DESIGN, SETTING, INTERVENTION, MAIN OUTCOME MEASUREMENTS: The provincial pathology database was searched for all colon polyps reported in the 6 pathology laboratories in the city of Winnipeg in 2009. All retrieved pathology slides for previously reported right-sided HPs and a 20% random sample of left-sided HPs were reassessed by two pathologists with a special interest in GI pathology. Polyp size, colon location, and age and sex of the study participants were evaluated as potential predictors of reclassification. RESULTS: A total of 4096 pathology reports by 25 different pathologists were reviewed. Twenty percent of the polyps were reported as SCPs. Seventeen percent of right-sided previously reported HPs and 20% of those >5 mm were reclassified as SSAs. Size >5 mm (odds ratio [OR] 4.2; 95% confidence interval [CI], 1.5-11.4) and location in the right side of the colon (OR 4.7; 95% CI, 1.4-15.4) were independent predictors of reclassification. LIMITATIONS: Retrospective review. CONCLUSION: A significant proportion of recently reported right-sided HPs may be SSAs. Surveillance recommendations for SCPs should consider the size and location of SCPs and not just the reported type.

In vivo electrochemical evidence for simultaneous 5-HT and histamine release in the rat substantia nigra pars reticulata following medial forebrain bundle stimulation.

Exploring the mechanisms of serotonin [5-hydroxytryptamine (5-HT)] in the brain requires an in vivo method that combines fast temporal resolution with chemical selectivity. Fast-scan cyclic voltammetry is a technique with sufficient temporal and chemical resolution for probing dynamic 5-HT neurotransmission events; however, traditionally it has not been possible to probe in vivo 5-HT mechanisms. Recently, we optimized fast-scan cyclic voltammetry for measuring 5-HT release and uptake in vivo in the substantia nigra pars reticulata (SNR) with electrical stimulation of the dorsal raphe nucleus (DRN) in the rat brain. Here, we address technical challenges associated with rat DRN surgery by electrically stimulating 5-HT projections in the medial forebrain bundle (MFB), a more accessible anatomical location. MFB stimulation elicits 5-HT in the SNR; furthermore, we find simultaneous release of an additional species. We use electrochemical and pharmacological methods and describe physiological, anatomical and independent chemical analyses to identify this species as histamine. We also show pharmacologically that increasing the lifetime of extracellular histamine significantly decreases 5-HT release, most likely because of increased activation of histamine H-3 receptors that inhibit 5-HT release. Despite this, under physiological conditions, we find by kinetic comparisons of DRN and MFB stimulations that the simultaneous release of histamine does not interfere with the quantitative 5-HT concentration profile. We therefore present a novel and robust electrical stimulation of the MFB that is technically less challenging than DRN stimulation to study 5-HT and histamine release in the SNR.

Two Cases of Sporadic Eosinophilic Solid and Cystic Renal Cell Carcinoma in Manitoba Population.

Two sporadic cases of eosinophilic solid and cystic renal cell carcinoma (ESC RCC), at our institution, are presented in this study to contribute to the growing literature on this novel renal neoplasm. The first patient was a 38-year-old female with two synchronous renal masses measuring 3.5 and 1.9 cm on preoperative imaging. The second patient was a 44-year-old female with an incidental renal mass measuring 4 cm. Both patients underwent uncomplicated radical nephrectomies. The 1.9 cm mass in the first patient was consistent with clear cell RCC. The dominant mass in the first patient and the tumor in the second patient had microscopic and macroscopic findings in keeping with ESC RCC including a tan appearance, abundant eosinophilic cytoplasm, and CK20+ and CK7- staining. Both patients had an uncomplicated course following surgery with no evidence of local recurrence or distant metastatic disease for 1 and 2 years for the first and second patient accordingly. These cases contribute to a growing body of literature regarding ESC RCC including, to our knowledge, the first reported case of synchronous ESC RCC and clear cell RCC. Further research about this novel renal neoplasm is needed.

Characterizing Microsatellite Instability and Chromosome Instability in Interval Colorectal Cancers.

There are a substantial portion of colorectal cancers (CRCs), termed interval CRCs (I-CRCs), that are diagnosed shortly after a negative colonoscopy (i.e., no detectable polyps or CRC) and before recommended follow-up screening. The underlying cause(s) accounting for I-CRCs remain poorly understood, but may involve aberrant biology that drives genome instability. Genetic defects inducing genome instability are pathogenic events that lead to the development and progression of traditional sporadic (Sp-) CRCs. Classically, there are two genome instability pathways that give rise to virtually all Sp-CRCs, chromosome instability (CIN; ~85% of Sp-CRCs) and microsatellite instability (MSI; ~15% of Sp-CRCs); however, the contribution MSI and CIN have in I-CRCs is only beginning to emerge. To date, no study has simultaneously evaluated both MSI and CIN within an I-CRC cohort, and thus we sought to determine and compare the prevalence of MSI and/or CIN within population-based I-CRC and matched Sp-CRC cohorts. MSI status was established using a clinically validated, immunohistochemical approach that assessed the presence or absence of four proteins (MLH1, MSH2, MSH6 and PMS2) implicated in MSI. By combining the MSI results of the current study with those of our previous CIN study, we provide unprecedented insight into the prevalence of MSI and/or CIN between and within Sp- and I-CRCs. Our data show that MSI+ tumors are 1.5-times more prevalent within I-CRCs than Sp-CRCs in a population-based setting and further show that CIN+/MSI+ I-CRCs occur at similar frequency as CIN+/MSI+ Sp-CRCs.

Improved techniques for examining rapid dopamine signaling with iontophoresis.

Dopamine is a neurotransmitter that is utilized in brain circuits associated with reward processing and motor activity. Advances in microelectrode techniques and cyclic voltammetry have enabled its extracellular concentration fluctuations to be examined on a subsecond time scale in the brain of anesthetized and freely moving animals. The microelectrodes can be attached to micropipettes that allow local drug delivery at the site of measurement. Drugs that inhibit dopamine uptake or its autoreceptors can be evaluated while only affecting the brain region directly adjacent to the electrode. The drugs are ejected by iontophoresis in which an electrical current forces the movement of molecules by a combination of electrical migration and electroosmosis. Using electroactive tracer molecules, the amount ejected can be measured with cyclic voltammetry. In this review we will give an introduction to the basic principles of iontophoresis, including a historical account on the development of iontophoresis. It will also include an overview of the use of iontophoresis to study neurotransmission of dopamine in the rat brain. It will close by summarizing the advantages of iontophoresis and how the development of quantitative iontophoresis will facilitate future studies.

Advances in studying phasic dopamine signaling in brain reward mechanisms.

The last sixty years of research has provided extraordinary advances of our knowledge of the reward system. Since its discovery as a neurotransmitter by Carlsson and colleagues (1), dopamine (DA) has emerged as an important mediator of reward processing. As a result, a number of electrochemical techniques have been developed to measure DA in the brain. Together, these techniques have begun to elucidate the complex roles of tonic and phasic DA signaling in reward processing and addiction. In this review, we will first provide a guide for the most commonly used electrochemical methods for DA detection and describe their utility in furthering our knowledge about DA's role in reward and addiction. Second, we will review the value of common in vitro and in vivo preparations and describe their ability to address different types of questions. Last, we will review recent data that has provided new mechanistic insight of in vivo phasic DA signaling and its role in reward processing and reward-mediated behavior.

The importance of recognizing increased cecal inflammation in health and avoiding the misdiagnosis of nonspecific colitis.

BACKGROUND: An inherent degree of nonpathological mild inflammation in the cecum has been described informally among pathologists. This low-grade inflammation is often reported as "nonspecific colitis," which can confuse clinicians. Our objective was to characterize and quantify inflammatory changes in the cecum and rectum of healthy adults in a blinded study. METHODS: A total of 85 adults free of gastrointestinal symptoms and history of disease underwent colonoscopy plus cecal and rectal biopsies as part of a case control study. Slides were scored independently by two observers. Histology scores 0 (none) to 3 (severe) were assigned for: epithelial injury, crypt architecture, lamina propria cellularity, subcryptal cellularity, and cryptitis. Slides were scored in a blinded fashion. Biopsy slides of cecum and rectum from fifteen patients with ulcerative colitis were randomly distributed within our sample to limit observer bias. RESULTS: Scores for inflammation were greater in the cecum versus rectum for: epithelial injury (0.45 vs 0.26, P= 0.03), crypt architecture distortion (0.25 vs 0.09, P= 0.03), lamina propria cellularity (1.13 vs 0.34, P < 0.001), and cryptitis (0.40 vs 0.11, P < 0.001). CONCLUSIONS: Increased microscopic inflammation of the cecum is present in healthy individuals, compared to the rectum. Caution should be used when describing "colitis" in cecal biopsies. Clinicians should be cautious in their response to biopsy reports identifying patients as having clinically significant "colitis" that is limited to the cecum.