Clinical Bootcamp: Moving toward competency outside of the clinic

The COVID-19 Pandemic placed many challenges on the healthcare system. As healthcare providers were stretched thin and clinics were closed to any non-essential personnel, including learners, educational programs across the country scrambled to meet the needs of their students. In response to restrictions placed on traditional in-person clinical training, the University of Michigan Genetic Counseling Program (UMGCP) designed a Clinical Bootcamp (Bootcamp); a two-weeklong, blended educational activity using a framework of case-based learning (CBL) (McLean, 2016). Journal of Medical Education and Curricular Development, 3, JMECD.S20377). Herein is a description of the theory behind the design as well as specific details of the activities and evaluations to aid implementation and ideas for future applications. Activities developed for the Clinical Bootcamp retain relevance when clinical sites and experienced clinical supervisors are limited resources. We believe the Bootcamp can serve as a tool to expedite the transition of clinical skills to a new setting, allowing students to engage more fully upon entering a new clinical space, leading to optimal use of supervisors' time and experience, and allowing students to maximize the benefit of their time in clinic.

Entrustment decision-making in genetic counseling supervision: Exploring supervisor and student perspectives to enhance training practices

Entrustment decisions are an essential part of genetic counseling supervision and have the potential to influence a student's progression toward autonomy. However, there is often uncertainty among supervisors regarding how and when to make these decisions and very few studies have examined the impact of these decisions on students. This study utilized a mixed methods approach including surveys of genetic counseling supervisors (n = 76) and students (n = 86) as well as qualitative interviews with genetic counseling supervisors (n = 20) and students (n = 20) that explored factors that influence the entrustment decisions of genetic counseling supervisors and their effect on genetic counseling students. Genetic counseling supervisors and students were recruited from various organizations across the United States and Canada and represented a range of geographic regions, hospital systems, and genetic counseling programs. A hybrid process of deductive and inductive coding and thematic analysis was used to evaluate and interpret transcripts from the supervisor and student interviews. All participants identified advantages of increased autonomy during training. However, many supervisors reported low entrustment, seldom allowing students to complete unsupervised sessions or supervised cases without interruption. Entrustment decisions were heavily influenced by student ability and confidence, as well as patient feedback. Students emphasized the negative impact of decreased entrustment on their confidence and described clear benefits to increased autonomy before, during, and after the genetic counseling appointment. Supervisors identified various barriers to entrustment pertaining to the student, clinical setting, and the patient, whereas students more often emphasized barriers pertaining to themselves. Our results highlight a tension between the clear advantages of increased entrustment and autonomy and various barriers to the provision of these opportunities. Additionally, our data suggest several ways to enhance the supervisor-student relationship and promote additional learning opportunities to support student-centered supervision.

Disclosure of genetic risk to dating partners among young adults with von Hippel-Lindau disease

Individuals with genetic disease face unique challenges related to navigating dating relationships. While previous studies have explored the impact of hereditary breast and ovarian cancer syndrome on dating, research investigating psychosocial implications for young adults with early-onset multi-organ tumor predisposition syndromes such as von Hippel-Lindau disease (VHL) is scarce. This study assessed young adults' attitudes towards dating and decisions related to disclosing a diagnosis of VHL to a dating partner. Twenty-six young adults with VHL participated in semi-structured interviews exploring this issue, using a guide informed by the literature in consultation with providers and an individual with VHL. Interviews were coded with a primarily deductive approach using codes derived from the literature, with inductive coding employed for perspectives unique to VHL. Our results support previous findings that genetic disease contributes to fear of rejection due to decreased desirability. However, participants report that partners' reactions to VHL uniquely exacerbate this concern due to unfamiliarity with VHL and a perception that it is exceptionally serious, leading to different strategies in disclosure. While many cited negative reactions from partners, participants also described how disclosure can strengthen relationships by deepening trust. Participants discussed a desire for healthcare providers to offer support in this context and described the benefit of speaking with peers about their dating experiences and approaches to disclosure. Our findings provide insight into the diverse needs of young adults with VHL as they approach romantic relationships and decision-making regarding disclosure and highlight the importance of patient-centered support from providers and patient organizations.

Motivational interviewing for genetic counseling: A unified framework for persuasive and equipoise conversations

Genetic counselors (GCs) have traditionally been trained to adopt a position of equipoise or clinical neutrality. They provide information, answer questions, address barriers, and engage in shared decision-making, but generally, they do not prescribe a genetic test. Historically, GCs have generally been trained not to persuade the ambivalent or resistant patient. More recently, however, there has been discussion regarding when a greater degree of persuasion or directionality may be appropriate within genetic counseling (GC) and what role MI may play in this process. The role for "persuasive GC" is based on the premise that some genetic tests provide actionable information that would clearly benefit patients and families by impacting treatment or surveillance. For other tests, the benefits are less clear as they do not directly impact patient care or the benefits may be more subjective in nature, driven by patient values or psychological needs. For the former, we propose that GCs may adopt a more persuasive clinical approach while for the latter, a more traditional equipoise stance may be more appropriate. We suggest that motivational interviewing (MI) could serve as a unifying counseling model that allows GCs to handle both persuasive and equipoise encounters. For clearly beneficial tests, while directional, the MI encounter can still be non-directive, autonomy-supportive, and patient-centered. MI can also be adapted for equipoise situations, for example, placing less emphasis on eliciting and strengthening change talk as that is more a behavior change strategy than a shared decision-making strategy. The core principles and strategies of MI, such as autonomy support, evocation, open questions, reflective listening, and affirmation would apply to both persuasive and equipoise encounters. Key issues that merit discussion include how best to train GCs both during their initial and post-graduate education.

A-19 Inhibition in Metabolic Syndrome and its Relationship to Orbitofrontal Cortex Activation During Sucrose Evaluation

Objective

Metabolic syndrome(MetS) is associated with disinhibited eating,executive dysfunction,and increased risk of dementia. The orbitofrontal cortex(OFC) has been implicated in literature as an area involved with decision making and reward. Decreased OFC volume has been linked to disinhibited eating and poorer executive functioning skills.However,research examining executive functioning in individuals with MetS fails to address the role of inhibition as it pertains to consumption and risk of developing MetS. We examined the relationship between neuropsychological performance and OFC activation after receiving and rating a sucrose stimulus to determine if OFC activation is associated with executive functioning deficits that may lead to developing MetS.

Method

Participants were categorized by MetS status(n = 46) and Control(n = 34) with mean age of 49.13±20.29years. During an fMRI session, the Blood-Oxygenation-Level-Dependent(BOLD) response of OFC was recorded while participants rated the pleasantness of an aqueous sucrose solution. Participants were administered the Color-Word Interference Test outside the scanner. Partial Correlation analyses controlling for age examined the relationship between OFC activation during hedonic ratings of sucrose and cognitive performance.

Results

There was a significant negative relationship between left OFC activity and Color-Word Interference:Inhibition performance for Controls(r(42) = -.365, p = .015) as compared to MetS(r(30) = .141,p > .05).

Conclusions

Less activity in the OFC during sucrose hedonic rating was associated with better performance on the Inhibition condition for Controls. We speculate that decreased activation in the OFC after sucrose consumption reflects intact executive functioning and perhaps even a preventative factor to developing MetS. Alternatively, it could indicate that Controls are actively inhibiting hedonic responses to sucrose which improves their ability on a test of inhibition.

Evaluating and improving the implementation of a community-based hereditary cancer screening program

Healthcare disparities exist in the provision of cancer genetic services including genetic counseling and testing related to BRCA1/2 mutations. To address this in a community health setting a screening tool was created to identify high-risk women. This study evaluates the implementation of the tool and identifies opportunities for improved cancer genetic screening, including regular clinician education. A mixed-method approach was used to evaluate clinician utilization of the screening tool at Planned Parenthood affiliates. Novel surveys that evaluated acceptance and implementation were administered to clinicians (n = 14) and semi-structured interviews (n = 6) were used to explore clinicians' perspectives and identify gaps in its utilization. Educational modules that addressed gaps were developed, implemented, and evaluated using a post-education survey (n = 8). Clinicians reported confidence in administering and interpreting the screening tool, but reported less confidence in their knowledge of cancer genetics and ability to connect clients with genetic counseling and testing (p = .003). Educational modules resulted in significant gains in clinician knowledge on genetic topics (p < .05) and increased self-reported confidence in connecting clients with genetic services. The modules reinforced the belief that genetic testing is beneficial for patients at increased risk (p = .001) and is important to inform subsequent medical management (p = .027). While building community clinicians' capacity to connect clients with genetic services is crucial, it is challenged by knowledge and confidence gaps in discussions of genetic services with clients. Consistent genetic-focused education with non-genetic clinicians can improve confidence and knowledge, enabling a more effective screening program in community health settings.

Subjective and Objective Risks of Carrying a BRCA1/2 Mutation in Individuals of Ashkenazi Jewish Descent

This repeated measures study examines (1) the change in subjective risk of mutations pre- to postcounseling, (2) the accuracy of BRCAPRO estimates of mutations, and (3) the discrepancy between subjective risk and BRCAPRO estimates of mutations before and after genetic counseling. Ninety-nine Ashkenazi Jewish individuals pursued testing for BRCA1/2 mutations. Most had a personal cancer history (N = 51; family only: N = 48); and received uninformative negative results (N = 66; positives: N = 23; informative negative: N = 10). The coping strategy of defensive pessimism predicts that individuals will believe the worst case scenario to better cope with a potential negative outcome. Consistent with this, most felt they would have a mutation, if not mutations in both genes. The BRCAPRO model appeared to overestimate risk of having a mutation in this sample (p < .001). BRCAPRO overestimates notwithstanding, genetic counseling increased accuracy of subjective risk (p < .01). Individuals with a family-only cancer history had the least accurate estimates of risk (p < .05) and may need further intervention to either manage anxiety or improve knowledge.

Screening for germline mismatch repair mutations following diagnosis of sebaceous neoplasm

IMPORTANCE Sebaceous neoplasms (SNs) define the Muir-Torre syndrome variant of Lynch syndrome (LS), which is associated with increased risk for colon and other cancers necessitating earlier and more frequent screening to reduce morbidity and mortality.Immunohistochemical (IHC) staining for mismatch repair (MMR) proteins in SNs can be used to screen for LS, but data on subsequent germline genetic testing to confirm LS diagnosis are limited.OBJECTIVE To characterize the utility of IHC screening of SNs in identification of germline MMR mutations confirming LS.DESIGN, SETTING, AND PARTICIPANTS Retrospective study at 2 academic cancer centers of 86 adult patients referred for clinical genetics evaluation after diagnosis of SN.MAIN OUTCOMES AND MEASURES Results of tumor IHC testing and germline genetic testing were reviewed to determine positive predictive value and sensitivity of IHC testing in diagnosis of LS. Clinical variables, including age at diagnosis of SN, clinical diagnostic criteria for LS and Muir-Torre syndrome, and family history characteristics were compared between mutation carriers and noncarriers.RESULTS Of 86 patients with SNs, 25 (29%) had germline MMR mutations confirming LS.Among 77 patients with IHC testing on SNs, 38 (49%) had loss of staining of 1 or more MMR proteins and 14 had germline MMR mutations. Immunohistochemical analysis correctly identified 13 of 16 MMR mutation carriers, corresponding to 81% sensitivity. Ten of 12 patients(83%) with more than 1 SN had MMR mutations. Fifty-two percent of MMR mutation carriers did not meet clinical diagnostic criteria for LS, and 11 of 25 (44%) did not meet the clinical definition of Muir-Torre syndrome. CONCLUSIONS AND RELEVANCE Immunohistochemical screening of SNs is effective in identifying patients with germline MMR mutations and can be used as a first-line test when LSis suspected. Abnormal IHC results, including absence of MSH2, are not diagnostic of LS and should be interpreted cautiously in conjunction with family history and germline genetic testing. Use of family history to select patients for IHC screening has substantial limitations,suggesting that universal IHC screening of SNs merits further study. Clinical genetics evaluation is warranted for patients with abnormal IHC test results, normal IHC test results with personal or family history of other LS-associated neoplasms, and/or multiple SNs.

Donor screening for human T-cell lymphotrophic virus 1/2: changing paradigms for changing testing capacity

Organ Procurement and Transplant Network (OPTN) policy currently requires the testing of all potential organ donors for human T-cell lymphotrophic virus (HTLV)-1/2. Most Organ Procurement Organizations (OPO) use the Abbott HTLV-I/HTLV-II Enzyme Immunoassay (EIA). This assay will no longer be manufactured after December 31, 2009; the only commercially available FDA-licensed assay will be the Abbott PRISM HTLV-I/II assay which poses many challenges to OPO use for organ donor screening. As a result, screening donors for HTLV-1/2 in a timely manner pretransplant after December 31, 2009 will be challenging. The true incidence of HTLV-1 in United States (U.S.) organ donors is not well described but appears to be low ( approximately 0.03-0.5%). HTLV-1 is associated with malignancy and neurological disease; HTLV-2 has not been convincingly associated with disease in humans. Donors that are HTLV-1/2 seropositive are infrequently used despite most results being either false positive or resulting from HTLV-2 infection. There is urgent need to encourage the development of assays, instruments and platforms optimized for organ donors that can be used to screen for transmissible disease in donors; these must have appropriate sensitivity and specificity to identify all infections while minimizing organ loss through false positive testing.

Cancer genetics knowledge and beliefs and receipt of results in Ashkenazi Jewish individuals receiving counseling for BRCA1/2 mutations

BACKGROUND

Genetic counseling for BRCA1 and BRCA2 mutations (mutations associated with increased risk of breast-ovarian cancer) endeavors to communicate information that will help individuals make informed decisions regarding genetic testing.

METHODS

This repeated-measures study examined cancer genetics knowledge and beliefs before and after counseling and their relationship to receipt of results for BRCA1/2 mutations in 120 highly educated Ashkenazi Jewish individuals.

RESULTS

A repeated-measures analysis examined change in knowledge and beliefs regarding personal behavior, mechanisms of cancer inheritance, meaning of a positive result, practitioner knowledge, frequency of inherited cancer, and meaning of a negative result from pre- to post-counseling with the between subjects variables of education (with/without graduate training) and personal history of breast or ovarian cancer (yes/no), and risk of having a mutation entered as a covariate. Mechanisms of cancer inheritance, meaning of a positive result, and practitioner knowledge increased from pre- to post-counseling. Those with graduate training had higher ratings of mechanisms of cancer inheritance ratings and lower ratings of frequency of inherited cancers than those without. Mann-Whitney U tests found those testing had higher ratings in mechanisms of cancer inheritance, specifically in the association of multiple primary cancers with hereditary cancer, than those not testing.

CONCLUSIONS

Genetic counseling is helpful in improving overall knowledge of cancer genetics even for highly educated individuals. Particular areas of knowledge improvement should be explored in relation to receipt of results, especially to further elucidate the relationship of knowledge of the association of multiple primary cancers with hereditary cancer to receipt of test results.

Subjective and objective risk of breast cancer in Ashkenazi Jewish individuals at risk for BRCA1/2 mutations

The aims of the study were to (1) examine the differences between subjective and objective estimates of the risk of breast cancer in those being tested for BRCA1/2 mutations, (2) explore new ways to conceptualize risk, and (3) examine the change in subjective risk of developing breast cancer throughout the process of genetic counseling and testing. Participants were 86 Ashkenazi Jewish women with a family or personal history indicating risk for BRCA1/2 mutations. Surveys to assess subjective risk of breast cancer (percentage risk, projected age of onset, and survival time) were administered before counseling, after counseling, and after receipt of test results. Subjective percentage risk of breast cancer was compared to estimated objective risk to determine accuracy. Those with no personal history of cancer receiving positive results became more accurate from post-counseling to post-result. Those receiving positive results increased their estimate of their percentage risk, and those receiving uninformative negative results decreased their estimate of their percentage risk from post-counseling to post-result. Those without a personal history of cancer decreased in perceived risk from post-counseling to post-result. No change in projected age of onset of breast cancer or survival time with breast cancer was seen from pre- to post-counseling or from post-counseling to post-result, and no change in accuracy or in percentage risk of breast cancer was seen from pre- to post-counseling. Individuals use information from genetic counseling to form estimates of percentage risk following receipt of test results; however, projected age of onset and survival time with breast cancer, areas not targeted by genetic counseling that may be more closely linked to health behavior, do not change.

The Decision to Test in Women Receiving Genetic Counseling for BRCA1 and BRCA2 Mutations

Functions of genetic counseling include provision of risk information and provision of support in an effort to assist with decision making. This study examines (1) the relationship among intentions to test, self-reported provision of blood sample, and receipt of test results; (2) the impact of genetic counseling on distress specific to gene status, perceived risk of developing breast and ovarian cancer in the context having BRCA1/2 mutations (mutations predisposing to increased risk of breast-ovarian cancer), and perceived risk factors for breast cancer; and (3) the clinical profile of those receiving/not receiving results. Intentions to test for BRCA1/2 mutations, self-reported provision of blood sample immediately after counseling, and receipt of test results were statistically different but highly correlated, and intentions to test increased from pre- to postcounseling. A repeated measures ANOVA found distress specific to gene status and perceived risk factors decreased from pre- to postcounseling. Further, two clinical profiles of consultands emerged: (1) those receiving results with change in intentions to test having lower levels of distress and (2) those not receiving results and those receiving results with no change in intentions to test with higher levels of distress. Our findings are consistent with the function of genetic counseling-to provide information and support to those with familial cancer, as well as to assist in decision making. The provision of support is important as distress specific to gene status may impede flexible decision making about genetic testing.

Using the common sense model to understand perceived cancer risk in individuals testing for BRCA1/2 mutations

The common sense model posits that individuals' understanding of illness is based upon somatic symptoms and life experiences and thus may differ significantly from the biomedical view of illness. The current study used the common sense model to understand cancer risk perceptions in 99 individuals testing for BRCA1/2 mutations. Specifically, we examined change from post-counseling to post-result in (1) absolute risk (risk of developing cancer in one's lifetime) and (2) comparative risk (risk relative to the general population). Results indicated that absolute risk showed a trend such that those with a personal history of cancer receiving uninformative negative results reported decreased absolute risk. Further, individuals receiving uninformative negative results reported decreased comparative risk. Those with no personal cancer history receiving informative negative results did not decrease in risk over time nor did their risk differ from those with a personal cancer history, evidencing unrealistic pessimism regarding their risk of cancer. The reasons provided for individuals' risk perceptions could be classified in terms of attributes of the common sense model and included the: (1) causes of cancer (e.g. family history, mutation status); (2) control or cure of cancer through health behaviors and/or surgery; and (3) perceived timeline for developing cancer (e.g. time left in life to develop cancer). We conclude that key to developing interventions to improve understanding of cancer risk and promoting effective cancer control mechanisms is an understanding of the specific reasons underlying individuals' perceptions of cancer risk.

Genetic testing for hereditary nonpolyposis colorectal cancer

Approximately 80 per cent of patients with colorectal cancer have sporadic disease whereas the remaining 20 per cent seem to have a genetic component. Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common autosomal dominant hereditary syndrome predisposing to colorectal cancer. Various methods have been described to screen for HNPCC and to directly test for mismatch repair gene mutations. This study evaluates the initial results of 1) microsatellite instability (MSI) and immunohistochemistry (IHC) staining of tumors and 2) genetic sequencing for mismatch repair gene mutations in patients suspected to have HNPCC. Appropriate patients for HNPCC testing were identified through a high-risk colorectal cancer clinic. Of those patients screened only those who met Amsterdam criteria (AC) for HNPCC or were young age onset (YAO) (<40 years of age) were eligible for testing. The tumors underwent testing for MSI and had IHC performed in those patients with available tumor specimens. MSI was performed on the five markers approved by the NIH consensus conference. MSI-High (MSI-H) was defined as two or more markers being unstable. IHC was done with commercially available stains for MLH1 and MSH2. All patients had sequencing of the MLH1 and MSH2 genes performed to search for mutations by a commercial laboratory. Genetic counseling was provided and written informed consent was obtained. Fourteen patients were part of kindreds that met the AC. An additional 10 patients were <40 years of age at diagnosis of colorectal cancer but lacked any family history. Testing for MSI and IHC was performed on those available tissue blocks. Of the AC patients five had MSH2 mutations and two had MLH1 variants. Of the five with MSH2 mutations three of four had MSI-H tumors and all four had loss of expression of MSH2 on IHC. Of the MLH1 variants only one had MSI-H tumor and lacked expression of MLH-1 on IHC. Of those patients with no mutation identified three of six had MSI-H tumors. For those patients YAO no genetic mutations were identified. Two of the seven had MSI-H tumors. Genetic testing for HNPCC even in those patients fulfilling the rigid AC yielded mutations in only five of 14 patients with variants of unknown significance being found in an additional two patients. Only one MSH2 variant of unknown significance was identified in the 10 YAO patients, which would suggest that screening in this group of patients with MSI and/or IHC would be appropriate.

Genetic Testing for Hereditary Nonpolyposis Colorectal Cancer

Approximately 80 per cent of patients with colorectal cancer have sporadic disease whereas the remaining 20 per cent seem to have a genetic component. Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common autosomal dominant hereditary syndrome predisposing to colorectal cancer. Various methods have been described to screen for HNPCC and to directly test for mismatch repair gene mutations. This study evaluates the initial results of 1) microsatellite instability (MSI) and immunohistochemistry (IHC) staining of tumors and 2) genetic sequencing for mismatch repair gene mutations in patients suspected to have HNPCC. Appropriate patients for HNPCC testing were identified through a high-risk colorectal cancer clinic. Of those patients screened only those who met Amsterdam criteria (AC) for HNPCC or were young age onset (YAO) (<40 years of age) were eligible for testing. The tumors underwent testing for MSI and had IHC performed in those patients with available tumor specimens. MSI was performed on the five markers approved by the NIH consensus conference. MSI-High (MSI-H) was defined as two or more markers being unstable. IHC was done with commercially available stains for MLH1 and MSH2. All patients had sequencing of the MLH1 and MSH2 genes performed to search for mutations by a commercial laboratory. Genetic counseling was provided and written informed consent was obtained. Fourteen patients were part of kindreds that met the AC. An additional 10 patients were <40 years of age at diagnosis of colorectal cancer but lacked any family history. Testing for MSI and IHC was performed on those available tissue blocks. Of the AC patients five had MSH2 mutations and two had MLH1 variants. Of the five with MSH2 mutations three of four had MSI-H tumors and all four had loss of expression of MSH2 on IHC. Of the MLH1 variants only one had MSI-H tumor and lacked expression of MLH-1 on IHC. Of those patients with no mutation identified three of six had MSI-H tumors. For those patients YAO no genetic mutations were identified. Two of the seven had MSI-H tumors. Genetic testing for HNPCC even in those patients fulfilling the rigid AC yielded mutations in only five of 14 patients with variants of unknown significance being found in an additional two patients. Only one MSH2 variant of unknown significance was identified in the 10 YAO patients, which would suggest that screening in this group of patients with MSI and/or IHC would be appropriate.

Re-expression of the intermediate filament nestin in reactive astrocytes

The intermediate filament nestin is highly expressed in multipotential stem cells of the developing central nervous system (CNS). During neuro- and gliogenesis, nestin is replaced by cell type-specific intermediate filaments, e.g. neurofilaments and glial fibrillary acidic protein (GFAP). In this study, we demonstrate that nestin expression is re-induced in reactive astrocytes in the lesioned adult brain. Following ischaemic and mechanical lesioning, a strong and sustained expression of nestin was noted in GFAP-positive cells surrounding the lesion site. Lesion experiments in transgenic mice carrying the lacZ gene under control of regulatory sequences from the nestin gene suggested that the upregulation of nestin in reactive astrocytes is mediated via the same sequences that control nestin expression during CNS development. These observations and recent data on the co-expression of glial and neuronal marker antigens in reactive astrocytes point to a close relationship between proliferating astrocytes and neuroepithelial precursor cells.

Monoclonal antibodies to a rat nestin fusion protein recognize a 220-kDa polypeptide in subsets of fetal and adult human central nervous system neurons and in primitive neuroectodermal tumor cells

Nestin is the major intermediate filament protein of embryonic central nervous system (CNS) progenitor cells. To identify proteins involved in early stages of lineage commitment in the developing human CNS we generated monoclonal antibodies to a TrpE-rat nestin fusion protein. This resulted in a monoclonal antibody (designated NST11) that did not recognize authentic human nestin, but did recognize a novel neuron-specific human polypeptide expressed in a subset of embryonic and adult CNS neurons as well as in medulloblastomas. NST11 immunoreactivity was abundant in developing spinal cord motor neurons, but was extinguished in these neurons by 17 weeks gestation. NST11 also labeled Purkinje cells at 17 weeks gestation, but Purkinje cells continued to express the NST11 antigen throughout gestation as well as in the adult cerebellum, and NST11 immunoreactivity was more abundant in Purkinje cells than in any other human CNS neurons. No NST11 immunoreactivity was detected in cells of the adult human peripheral nervous system or in a variety of adult non-neural human tissues. Further, NST11 almost exclusively stained cerebellar medulloblastomas. In Western blots of immature and mature human cerebral and cerebellar extracts, NST11 did not bind human nestin, but did detect an immunoband with a molecular weight of 220 kd. A similar immunoband was detected in medulloblastoma-derived cell lines with a neuron-like phenotype. These findings suggest that the NST11 monoclonal antibody recognizes a novel protein expressed by a subpopulation of immature and mature human CNS neurons, medulloblastomas, and medulloblastoma-derived cell lines.

Multipotential stem cells in the vertebrate CNS

The functional differences between the many mature neuronal types make the origins of cellular diversity in the nervous system one of the most intriguing problems in biology. This paper discusses recent experiments which explore the mechanisms generating cell diversity in the vertebrate central nervous system, focusing particularly on the immediate precursor to neurons and on neuronal differentiation. Transplantation experiments have been used to explore regional and temporal differences in the cells of the neuroepithelium. The effects of specific genes on neuronal development have been examined by mutational analysis in transgenic mice and in established neuronal stem cell lines. The combination of methods now available allow increasingly powerful dissection of the molecular and cellular mechanisms that generate the large number of different neurons in the vertebrate brain.

Nestin expression in embryonic human neuroepithelium and in human neuroepithelial tumor cells

Nestin is a recently described member of the intermediate filament (IF) protein family that is especially abundant in neuroepithelial stem cells of the rat. The studies described here examine this class VI IF protein in the normal human developing central nervous system (CNS), human brain tumor-derived cell lines, and tissue samples of human CNS tumors. Human nestin exhibited biochemical and immunochemical properties similar to those of rat nestin. Further, as in the rat, nestin was detected immunohistochemically in several different types of immature human CNS cells, i.e. germinal matrix cells, neuroepithelial cells lining the central canal, radial glia and vascular cells. Nestin appeared in these cells at the earliest gestational age (i.e., 6 weeks) examined here and then it declined in all but the vascular cells at later embryonic stages. Nestin also was detected by immunocytochemistry in 6 of 7 primitive neuroectodermal tumor cell lines and in both of 2 malignant glioma cell lines examined. In these cell lines, nestin co-localized incompletely with bundles of IFs containing other IF proteins (i.e., vimentin, glial filament, neurofilament). Nestin was ubiquitous in a wide variety of brain tumors, but was most prominent in gliomas. The transient expression of nestin in primitive neuroepithelial cells at early stages of human embryogenesis and its abundance in neuroepithelial tumors suggest a role for nestin IFs in cellular events that precede the exit of embryonic CNS stem cells from the cell cycle and the commitment of the progeny of these stem cells to a specific lineage. The subsequent induction of different members of the IF protein family in phenotypically distinct CNS cells (i.e. neurons, glia) and the elimination of nestin from almost all differentiated CNS cells, imply that different classes of IFs subserve functions that are closely linked to the maturational state, as well as the lineage, of CNS cells.

Effects of tamoxifen and somatostatin analogue on growth of human medullary, follicular, and papillary thyroid carcinoma cell lines: tissue culture and nude mouse xenograft studies

The knowledge that (1) the normal thyroid contains somatostatin, (2) polypeptide growth factors influence thyroid cell function, and (3) thyroid cells contain steroid hormone receptors prompted us to add somatostatin analogue No. 201-995 (SMS) (5 ng/ml) and/or tamoxifen citrate (TAM) (5 mumol/L) to 7-day monolayer cultures (50,000 cells/well) of three separate human thyroid carcinoma cell lines: DR081 (medullary), WR082 (follicular), and NPA'87 (papillary). Results, tabulated as cell numbers/well (X10(5) on day 7, revealed that TAM inhibited growth of medullary and follicular cells and that TAM plus SMS inhibited growth of papillary cells. In vivo studies of subcutaneous tumor cell xenografts in nude mice have documented that TAM (5 mg subcutaneous pellet) significantly inhibits the growth of medullary implants. Flow cytometric DNA studies of medullary cell cultures demonstrated a reduced G2 + M phase with TAM treatment. For papillary cell implants, TAM plus SMS (5 micrograms subcutaneously, twice daily) did not suppress tumor growth. All three cell lines were negative for estrogen receptor; addition of estradiol (5 ng/ml) to medullary cell cultures neither stimulated replication nor reversed the inhibitory effects of TAM in vitro. We conclude that (1) TAM slowed the growth of a cell line of human medullary carcinoma, both in vitro and in vivo; (2) this effect was not reversed by estradiol; (3) TAM plus SMS inhibited replication of a papillary carcinoma cell line in vitro, but not in vivo; and (4) TAM alone and TAM plus SMS inhibited replication of cultures of a human follicular thyroid carcinoma cell line. TAM and SMS may be useful in treatment of some human thyroid carcinomas.

Interaction of gelatin with stereospecific binding proteins and its enhancement of competitive binding assays

The effect of gelatin (0.5 g/l) on binding curves at high dilution of three classes of stereo-specific binding proteins was studied. These included two antibodies (to oestradiol and aldosterone), six transins (horse and dog transcortins, human thyroxine-binding globulin, human sex steroid-binding globulin, and guinea pig transprogestin), and one receptor (bovine adrenal protein kinase). Gelatin increased the apparent binding of all these proteins, particularly at the highest dilutions and sometimes in a striking manner. While much of this action can be attributed to its decreasing the adhesion of the dilute binding protein to glass, gelatin also increased the apparent uptake of some tracers by certain adsorbents. Similar findings were obtained using human gamma globulin (2 g/l). These effects resulted in increased sensitivity and improved reproducibility in the assays employing them.