Publications by authors named "Constance Chik"

Article Synopsis
  • Multiple endocrine neoplasia type 1 (MEN1) is a genetic disorder that leads to tumors in the pituitary gland, parathyroid glands, and digestive tract, affecting roughly 40% of cases with pituitary tumors (PitNETs) showing a slight female bias.* -
  • Functional PitNETs (FPitNETs), especially prolactinomas, are more common than non-functional types, and MEN1-related tumors tend to be larger, more invasive, and sometimes plurihormonal compared to sporadic tumors.* -
  • When considering treatment, MEN1-related PitNETs are managed similarly to sporadic ones, and in patients with symptoms resembling MEN1 but with negative genetic tests, MEN
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Aggressive pituitary neuroendocrine tumors (PitNETs) present significant morbidity, and multimodal therapies including surgery, radiotherapy, and medications are frequently required. Chemotherapy, particularly temozolomide, is often pursued for tumors that progress despite these treatments. Although peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogs is approved for the treatment of well-differentiated gastrointestinal neuroendocrine tumors, its use in aggressive PitNETs is limited.

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Pituitary tumors (PTs) represent about 10% of all intracranial tumors, and most are benign. However, some PTs exhibit continued growth despite multimodal therapies. Although temozolomide (TMZ), an alkylating chemotherapeutic agent, is a first-line medical treatment for aggressive PTs, some PTs are resistant to TMZ.

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Summary: Non-islet cell tumour hypoglycemia (NICTH), typically mediated by insulin-like growth factor 2 (IGF-2), is a rare but highly morbid paraneoplastic syndrome associated with tumours of mesenchymal or epithelial origin. Outside of dextrose administration and dietary modification which provide transient relief of hypoglycemia, resection of the underlying tumour is the only known cure for NICTH. Available medical therapies to manage hypoglycemia include glucocorticoids, recombinant growth hormone, and pasireotide.

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Pituitary neuroendocrine tumors (PitNETs) are the third most frequently diagnosed intracranial tumors, with nonfunctioning PitNETs (nfPitNETs) accounting for 30% of all pituitary tumors and representing the most common type of macroPitNETs. NfPitNETs are usually benign tumors with no evidence of hormone oversecretion except for hyperprolactinemia secondary to pituitary stalk compression. Due to this, they do not typically present with clinical syndromes like acromegaly, Cushing's disease or hyperthyroidism and instead are identified incidentally on imaging or from symptoms of mass effects (headache, vision changes, apoplexy).

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Context: Patients with acromegaly (PWA) experience balance issues, despite achieving biochemical remission, that may significantly impair their quality of life.

Objective: We sought to assess the prevalence of falls and balance self-confidence in PWA in comparison with a control group. Furthermore, we investigated the effect of joint pain and function as predictors for their balance self-confidence.

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Context: The COVID-19 pandemic challenged undertaking gradual educational activities for residency and fellowship trainees. However, recent technological advances have enabled broadening active learning opportunities through international online conferences.

Objective: The format of our international online endocrine case conference, launched during the pandemic, is introduced.

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Object Exclusively dopamine-producing pheochromocytoma/paraganglioma (PPGL) is an extremely rare subtype. In this condition, intratumoral dopamine β-hydroxylase (DBH), which controls the conversion of norepinephrine from dopamine, is impaired, resulting in suppressed norepinephrine and epinephrine production. However, the rarity of this type of PPGL hampers the understanding of its pathophysiology.

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Pituitary adenomas are benign tumours that can cause an individual various clinical manifestations including tumour mass effects and/or the diverse effects of abnormal pituitary hormone secretion. Given the morbidity and limited treatment options for pituitary adenomas, there is a need for better biomarkers and treatment options. One molecule that is of specific interest is the signal transducer and activator of transcription 3 (STAT3), a transcription factor that plays a critical role in mediating cytokine-induced changes in gene expression.

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The papillary subtype of craniopharyngioma (CP) rarely occurs in children and commonly presents as a suprasellar lesion. Patients with papillary CPs frequently harbor the -V600E mutation, and treatment with a BRAF inhibitor results in tumor shrinkage in several patients. Herein, we report a patient with childhood-onset papillary CP treated with vemurafenib for 40 months after multiple surgeries.

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Objectives: In this study, we evaluated the feasibility of a nurse practitioner-led outpatient clinic (NPC) to facilitate the safe transition of patients with diabetes receiving insulin therapy between hospital and the community.

Methods: An NPC was set up to manage patients who had diabetes education in hospital and who were discharged on insulin. In addition to patient demographics and admission diagnosis, days seen postdischarge, duration of follow up, diabetes interventions and discharge care plan were recorded.

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Corticotroph carcinomas and aggressive corticotroph tumors can be resistant to conventional therapy, including surgery, radiotherapy, and medical treatment. Recent evidence suggests that temozolomide (an oral alkylating agent) administered with capecitabine (pro-drug of 5-fluorouracil) may improve progression-free survival in patients with high-risk corticotroph tumors and carcinomas. This led to the use of capecitabine and temozolomide (CAPTEM) in two patients, one with a corticotroph carcinoma and the other with an aggressive corticotroph tumor, as well the in vitro analysis of capecitabine and 5-fluorouracil on cell growth and hormone production.

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Pituitary tumors (PTs) can cause significant mortality and morbidity due to limited therapeutic options. L-type amino acid transporters (LATs), in particular, the LAT1 isoform, is expressed in a variety of tumor cells. Pharmacological inhibition or genetic ablation of LAT1 can suppress leucine transport into cancer cells, resulting in suppression of cancer cell growth.

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Previous studies have linked systemic glucocorticoid use with intestinal perforation. However, the association between intestinal perforation and endogenous hypercortisolism has not been well described, with only 14 previously published case reports. In this study, we investigated if intestinal perforation occurred more frequently in patients with ectopic ACTH syndrome and in those with a greater than 10-fold elevation of 24-hour urinary free cortisol level.

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To clarify the selection of medical therapy following transsphenoidal surgery in patients with acromegaly, based on growth hormone (GH)/insulin-like growth factor 1 (IGF-1) response and glucometabolic control. We carried out a systematic literature review on three of the best studied and most practical predictive markers of the response to somatostatin analogues (SSAs): somatostatin receptor (SSTR) expression, tumor morphologic classification, and T2-weighted magnetic resonance imaging (MRI) signal intensity. Additional analyses focused on glucose metabolism in treated patients.

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Tumors of hypothalamic neurons that produce vasopressin are rare. We retrieved all cases of vasopressin-positive tumors in the sellar region from the database of the Department of Pathology. Five cases fulfilled the selection criteria, representing the first series of such tumors.

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Background And Objective: Gestational diabetes (GDM) occurs more often in women from certain ethnic groups and is also associated with fetal macrosomia. In this study, we investigated the ability of a gestational diabetes screening test (GDS), the 2 h 75 g-Oral Glucose Tolerance Test (OGTT), and glycated hemoglobin (HbA1c) in predicting postpartum dysglycemia and fetal macrosomia in women of Caucasian, Filipino, Chinese and South-Asian descent.

Methods: 848 women diagnosed with carbohydrate intolerance in pregnancy who completed a 2 h 75 g- OGTT within 6 months postpartum, were included in the study.

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Objective: To determine the benefits of diabetes nurse practitioner (DNP) intervention on glycemic control, quality of life and diabetes treatment satisfaction in patients with type 2 diabetes (T2DM) admitted to cardiology inpatient services at a tertiary centre.

Patients And Methods: Patients admitted to the cardiology service with T2DM who had suboptimal control (HbA1c >6.5%) were approached for the study.

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Vascular dysfunction has been described in women with a history of gestational diabetes mellitus. Furthermore, previous gestational diabetes mellitus increases the risk of developing Type 2 diabetes mellitus, a risk factor for cardiovascular disease. Factors contributing to vascular changes remain uncertain.

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Aims: Previous gestational diabetes (GDM) is a risk factor for type 2 diabetes and increased metabolic risk, but the link with vascular dysfunction is not clear. This study examined vascular function in women 4-10 years after a diagnosis of GDM who had a normal oral glucose tolerance test (OGTT) in the first postpartum year.

Methods: We studied 90 women with a history of GDM and 59 age-matched controls, examining differences in insulin resistance as measured by the Homeostatic Model Assessment (HOMA-IR) and glucose responses during an OGTT, adiposity, lipid profile and C-reactive protein (CRP).

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Tumor immune microenvironment has been gradually recognized as a key contributor to tumor development, progression, and control. Immune cell infiltrates in brain tumors have been increasingly studied, but few have published on immune cell infiltrates in pituitary adenomas. We quantitatively assessed the infiltration of macrophages and lymphocytes in 35 pituitary adenomas, including 9 densely granulated growth hormone (DG-GH), 9 sparsely granulated growth hormone (SG-GH), 9 null cell (NC), and 8 adrenocorticotropic hormone (ACTH) adenomas.

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Background: The risk and mortality due to cancer in patients with acromegaly have been previously investigated. Although GH/IGF-1 excess provides a probable pathophysiological explanation, the degree of IGF-1 excess and the role in acromegaly-associated neoplasms of diabetes, a common comorbidity in acromegaly with known association with cancer, remains unclear.

Methods: Acromegalic patients treated in three Canadian referral centers (Toronto, Montreal, Edmonton) were included.

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Objective: Depressive symptoms are common and, when coexisting with diabetes, worsen outcomes and increase health care costs. We evaluated a nurse case-manager-based collaborative primary care team model to improve depressive symptoms in diabetic patients.

Research Design And Methods: We conducted a controlled implementation trial in four nonmetropolitan primary care networks.

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Objectives: The incidence of gestational diabetes mellitus (GDM) is increasing. However, less is known about the incidence of preeclampsia (PE) and whether it is affected by the presence of GDM. We sought to document the population-level incidence of GDM and PE during the last decade and examine the association between GDM and PE after accounting for established risk factors.

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Objective: To evaluate demographic data and quality of care of patients with acromegaly in Canada and their evolution over time and secondly, to evaluate predictors of co-morbidities and treatment outcomes.

Design And Patients: Retrospective analyses of clinical, biochemical and treatment outcome data of 649 patients with acromegaly (males: 50·7%) followed from 1980 to 2010 (mean 10·2 years, SD 13·7) in eight tertiary care centres from six Canadian provinces.

Results: In comparison to 1980-1994, the number of patients referred with acromegaly in the last 15 years was higher with female preponderance (52·8% vs 41·4%, P = 0·01) and an older age at diagnosis (46·4 ± 14 vs 41·3 ± 12 years, P < 0·0001).

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Synopsis of recent research by authors named "Constance Chik"

  • - Constance Chik's research primarily focuses on pituitary neuroendocrine tumors (PitNETs) and their treatment strategies, highlighting the complexity of aggressive types that often require multimodal therapies and innovative treatments such as peptide receptor radionuclide therapy.
  • - Her studies have also explored the prevalence, diagnosis, and management of nonfunctioning PitNETs, emphasizing their often benign nature while noting significant challenges in detecting and managing these tumors due to their lack of overt hormonal symptoms.
  • - Additionally, Chik's work investigates the intersection of endocrine disorders with other health issues such as joint pain and balance self-confidence in acromegaly patients, reflecting her commitment to improving quality of life outcomes in individuals with hormonal imbalances.