Phase II study of pembrolizumab and lenvatinib in advanced well-differentiated neuroendocrine tumors

BACKGROUND

Immune checkpoint inhibitors (CPIs) have not been shown to be active in well-differentiated neuroendocrine tumors (NETs), with response rates <5%. Lenvatinib is a multitargeted tyrosine kinase inhibitor which binds to vascular endothelial growth factor and fibroblast growth factor receptors and has demonstrated efficacy in pancreatic and gastrointestinal NETs [44% and 16% objective radiographic response rate (ORR), respectively]. The combination of antiangiogenic and CPI therapies can be synergistic. We therefore evaluated the combination of lenvatinib and pembrolizumab in well-differentiated gastrointestinal (GI) and thoracic NETs.

PATIENTS AND METHODS

A prospective, phase II trial evaluated patients with advanced GI/thoracic NETs (pancreatic NETs were excluded due to high response rate of lenvatinib monotherapy in this patient population), with evidence of progression within 8 months of study entry and at least two prior lines of systemic therapy. Patients received lenvatinib 20 mg daily and pembrolizumab 200 mg intravenously every 3 weeks until unacceptable toxicity or progression of disease. Primary endpoint was objective response rate, and an interim analysis was planned once 20 patients were enrolled. Four ORRs were required to continue enrollment.

RESULTS

Twenty patients were enrolled on protocol from April 2021 to January 2022 (nine small intestine, five lung, two thymic, two unknown primary, one cecal, one presacral primaries). Two patients (10%) achieved a partial response (atypical lung and small intestinal primaries). Median progression-free survival (PFS) was 8 months (95% confidence interval 5.8-10.2 months). Twelve (60%) patients experienced probably or definitely associated grade 3 adverse events (10 hypertension). Fourteen patients (70%) required dose reductions or discontinued one of the medications. Two patients discontinued treatment before radiographic assessment.

CONCLUSIONS

The combination of pembrolizumab and lenvatinib did not show sufficient response in patients with NETs to warrant continued enrollment on trial.

Dissociative Identity Disorder in Schools Part II

Dissociation is a well-established outcome of early life trauma, but school nurses may not be aware of resources and recommendations available to support students who experience it. If dissociation or behaviors consistent with dissociation are present, trauma-informed care (TIC) principles can guide individualized care of the student. Part I of this two-part article provided a pertinent background on dissociation, dissociative identity disorder (DID), the effects of social media, and TIC. Part II offers specific recommendations for implementing these principles in school nursing practice and follows the student vignette through the school year. Due to their holistic approach to care and long-standing leadership in providing TIC, nurses can significantly affect health, safety, and access to learning for students expressing dissociative experiences at school.

Dissociative Identity Disorder in Schools Part I

Dissociation is a normal life adaptation that can become pronounced and disruptive in the setting of repeated or extreme exposure to trauma. Children and adolescents may experience dissociation due to a trauma or stressor-related disorder, anxiety, or depressive disorders. Children and adolescents also may mimic behavior they see online as a way of expressing internally painful and intolerable experiences. Myth and misinformation surround the diagnosis of dissociative identity disorder (DID), formerly multiple personality disorder. The purpose of this article is to provide school nurses with evidence-based information on DID and resources for practice regarding how to provide a secure, consistent approach to students who are being traumatized, misunderstood, or excluded at home or at school. Part 1 of this two-part series describes DID foundations and DID in school-aged children, reviews controversy spurred by social media representation, and presents the Trauma-Informed Care (TIC) model. TIC offers useful perspectives regardless of a student's presentation or diagnostic status. Part 2 will discuss recommendations for managing dissociative presentations using a team-based approach, focusing on the school nurse's roles and responsibilities.

OnabotulinumtoxinA for Pediatric Migraine

BACKGROUND

Migraine is a painful, prevalent, and problematic condition among children. Children need access to safe and effective treatment options to alleviate the impact of this chronic condition on their wellbeing.

CLINICAL IMPLICATIONS

Nurses have a crucial role in supporting patient access to BTX-A. Given the results of this and other studies demonstrating the safety and efficacy of BTX-A in children, nurses can support policy change for health plans to fund this intervention for pediatric migraineurs. Allowing children to receive the safe and effective BTX-A injections will lessen the already significant impact of chronic migraine on their physical, emotional and mental health. Nurses can also play a key role in providing education to patients regarding safe administration of BTX-A for migraine.

AIM

The objective of this study was to define the experiences, effects, and clinical response of children to onabotulinumtoxinA (BTX-A) for migraine prevention.

METHODS

Clinical documentation for patients aged 13-17 years presenting for BTX-A treatment for chronic migraine between 2016-2022 in a community-based specialty clinic within a large, urban, pediatric academic medical center were included. A series of one-way repeated measures (analysis of variance [ANOVA]) were conducted to compare headache frequency, severity, and duration at baseline, and following first and second injections of BTX-A.

RESULTS

Of 32 eligible participants, administration of BTX-A demonstrated a decrease in headache frequency and severity. Participants reported nearly seven fewer headache days per month. Participants reported neck stiffness, fever or flu-like symptoms, fatigue, and worsening pain following BTX-A administration.

CONCLUSIONS

Pediatric migraineurs need therapies that are safe, effective, and accessible. BTX-A was a safe and effective treatment for migraine among the children included in this study.

Food Allergies and Anaphylaxis in the Community: The School Nurse's Role

Food allergy prevalence in the United States has been increasing among school-aged children. Many community-based pediatric caregivers (e.g., camp staff, sports coaches) are not trained to prevent, recognize, or manage allergic reactions due to a lack of available training and standard policies on this topic. Epinephrine is the first-line of treatment for severe allergic reactions and delayed administration of this medication can result in poor health outcomes and death. School nurses may use their knowledge and expertise to educate community-based pediatric caregivers on allergy topics. Professional practice projects can be utilized by school nurses to help improve allergy and anaphylaxis confidence and knowledge among community-based pediatric caregivers. By educating community members on anaphylaxis management, it can improve health outcomes for children of the school community and result in saved lives.

Food insecurity in college students: A concept analysis

AIM

This concept analysis provides an analysis of the concept of food insecurity among college students. The purpose was to support improved identification of the population and allow for targeted assessment and intervention strategies.

BACKGROUND

Food insecurity is a problem among college students. College students experience this more than the general population and have a unique set of risk factors and consequences. This requires a comprehensive understanding of this concept to design effective interventions.

DESIGN

Concept analysis using Walker and Avant.

DATA SOURCES

Databases were searched for articles in English related to food insecurity among college students. Government reports and gray literature were also reviewed. No date limit was set.

REVIEW METHODS

Articles and reports were read and reviewed. Thirty-nine sources were included in the analysis.

RESULTS

Five defining attributes were identified: Lack of sufficient food, negative academic implications, negative physical health impacts, negative psychosocial health impacts, learning to identify, and use food resources. Definitions, antecedents, consequences, and empirical referents are described. Cases are presented.

CONCLUSIONS

The proposed definition expounds upon current definitions and identifies the unique experiences and needs of college students who experience the phenomenon. This allows for early identification and support of college students' needs regarding food.

The Lived Experience of Nurses Who Volunteered to Combat the COVID-19 Pandemic in South Korea: A Qualitative Phenomenological Study

Aim

To explore the motivation and lived experience of nurses responding to the COVID‐19 pandemic in South Korea.

Background

Identifying motivation, barriers and facilitators to nurses' willingness to work during a pandemic is necessary to prepare for future pandemic responses.

Methods

Ten individual interviews were conducted. Interviews were analysed and synthesized following Colaizzi's method.

Results

Six major themes identified: Decision to participate in the COVID‐19 response; Facing hardship; Distress due to the nature of COVID‐19; Overcoming hardship; Growing through the COVID‐19 response; and The need for reciprocity.

Conclusion

The increased demands for nursing care during the pandemic highlight the need for strong organisational support and effective workforce strategies. Our study results can inform the development of programmes and policies that are proactive, rather than reactive, to prepare for future pandemic situations.

Implications for Nursing Management

To recruit and manage nurses during a pandemic effectively, a safe work environment with proper resources should be established. Additionally, adequate education, training and compensation are needed.

Efficacy of ipilimumab and nivolumab in patients with high-grade neuroendocrine neoplasms

Background

Dual checkpoint inhibitor therapy with anti-programmed cell death protein 1 and anti-cytotoxic T-lymphocyte-associated protein 4 therapy has shown promising results in patients with high-grade neuroendocrine neoplasms (NENs), demonstrating varying response rates of 9%-44%. More data are needed to evaluate the true response in a real-world cohort of patients.

Patients and methods

We conducted a retrospective study of all patients with high-grade NENs treated at the Moffitt Cancer Center and Mayo Clinic between September 2017 and July 2020 who received combination therapy with ipilimumab and nivolumab.

Results

Thirty-four patients met the eligibility criteria. Patients had received an average of two prior lines of therapy, including at least one cytotoxic chemotherapy regimen. Twenty-seven (79.4%) patients had poorly differentiated neuroendocrine carcinomas, and seven (20.6%) had well-differentiated high-grade neuroendocrine tumors. The most common primary site (10, 29.4%) was pancreas; other primary sites of disease included colon (n = 5), endometrium (n = 3), anorectum (n = 2), esophagus (n = 2), cervix (n = 1), stomach (n = 1), small intestine (n = 1), and unknown primary (n = 9). Five patients (14.7%) exhibited a best response of partial response as per RECIST 1.1 criteria, 9 (26.5%) stable disease, and 17 (50%) progressive disease: 3 patients did not have a follow-up scan as they discontinued treatment shortly after initiation due to clinical progression. The objective response rate was 14.7%, and disease control rate was 41.2%. Median progression-free survival was 1 month [95% confidence interval (CI), 0.54-1.46 months]; median overall survival (OS) from time of treatment initiation was 5.0 months (95% CI, 4.07-5.93 months), and median OS from diagnosis was 14.0 months (95% CI, 11.79-16.21 months). The median duration of treatment was 1 month (range 0-10 months). Twenty-eight patients discontinued treatment for progression, four patients for toxicity, and two remain on treatment at the time of data cut-off. Twelve patients (35%) experienced grade 3 and 4 treatment-emergent toxicities.

Conclusions

The ipilimumab and nivolumab regimen has modest activity in aggressive and heavily pretreated high-grade NENs who have progressed on prior cytotoxic chemotherapy.

•

Dual checkpoint inhibitor therapy has shown promising results in high-grade NENs.

•

Thirty-four patients with progressive high-grade NENs were treated with ipilimumab and nivolumab.

•

The objective response rate was 14.7%; 35% of patients experienced grade 3-4 treatment-emergent toxicities.

•

The ipilimumab and nivolumab regimen has modest activity in aggressive and heavily pretreated high-grade NENs.

Analysis of potential response predictors to capecitabine/temozolomide in metastatic pancreatic neuroendocrine tumors

The capecitabine and temozolomide (CAPTEM) regimen is active in the treatment of metastatic pancreatic neuroendocrine tumors (pNETs), with response rates ranging from 30 to 70%. Small retrospective studies suggest that O(6)-methylguanine DNA methyltransferase (MGMT) deficiency predicts response to temozolomide. High tumor proliferative activity is also commonly perceived as a significant predictor of response to cytotoxic chemotherapy. It is unclear whether chromosomal instability (CIN), which correlates with alternative lengthening of telomeres (ALT), is a predictive factor. In this study, we evaluated 143 patients with advanced pNET who underwent treatment with CAPTEM for radiographic and biochemical response. MGMT expression (n=52), grade (n=128) and ALT activation (n=46) were investigated as potential predictive biomarkers. Treatment with CAPTEM was associated with an overall response rate (ORR) of 54% by RECIST 1.1. Response to CAPTEM was not influenced by MGMT expression, proliferative activity or ALT pathway activation. Based on these results, no biomarker-driven selection criteria for use of the CAPTEM regimen can be recommended at this time.

A phase II study of axitinib in advanced neuroendocrine tumors

Neuroendocrine tumors (NETs) are highly vascular neoplasms overexpressing vascular endothelial growth factor (VEGF) as well as VEGF receptors (VEGFR). Axitinib is a potent, selective inhibitor of VEGFR-1, -2 and -3, currently approved for the treatment of advanced renal cell carcinoma. We performed an open-label, two-stage design, phase II trial of axitinib 5mg twice daily in patients with progressive unresectable/metastatic low-to-intermediate grade carcinoid tumors. The primary end points were progression-free survival (PFS) and 12-month PFS rate. The secondary end points included time to treatment failure (TTF), overall survival (OS), overall radiographic response rate (ORR), biochemical response rate and safety. A total of 30 patients were enrolled and assessable for toxicity; 22 patients were assessable for response. After a median follow-up of 29months, we observed a median PFS of 26.7months (95% CI, 11.4-35.1), with a 12-month PFS rate of 74.5% (±10.2). The median OS was 45.3 months (95% CI, 24.4-45.3), and the median TTF was 9.6months (95% CI, 5.5-12). The best radiographic response was partial response (PR) in 1/30 (3%) and stable disease (SD) in 21/30 patients (70%); 8/30 patients (27%) were unevaluable due to early withdrawal due to toxicity. Hypertension was the most common toxicity that developed in 27 patients (90%). Grade 3/4 hypertension was recorded in 19 patients (63%), leading to treatment discontinuation in six patients (20%). Although axitinib appears to have an inhibitory effect on tumor growth in patients with advanced, progressive carcinoid tumors, the high rate of grade 3/4 hypertension may represent a potential impediment to its use in unselected patients.

Pelvic squamous cell carcinoma of unknown primary: a case report and review of the literature

Retroperitoneal squamous cell carcinoma (SCC) of unknown primary is very rare with variable survival rates. Standard optimal therapeutic management is not yet established.

Phase II clinical trial of pasireotide long-acting repeatable in patients with metastatic neuroendocrine tumors

Pasireotide long-acting repeatable (LAR) is a novel somatostatin analog (SSA) with avid binding affinity to somatostatin receptor subtypes 1, 2, 3 (SSTR1,2,3) and 5 (SSTR5). Results from preclinical studies indicate that pasireotide can inhibit neuroendocrine tumor (NET) growth more robustly than octreotide in vitro. This open-label, phase II study assessed the clinical activity of pasireotide in treatment-naïve patients with metastatic grade 1 or 2 NETs. Patients with metastatic pancreatic and extra-pancreatic NETs were treated with pasireotide LAR (60 mg every 4 weeks). Previous systemic therapy, including octreotide and lanreotide, was not permitted. Tumor assessments were performed every 3 months using Response Evaluation Criteria in Solid Tumors (RECIST) criteria. The primary endpoint was progression-free survival (PFS). The secondary endpoints included overall survival (OS), overall radiographic response rate (ORR), and safety. Twenty-nine patients were treated with pasireotide LAR (60 mg every 4 weeks) and 28 were evaluable for response. The median PFS was 11 months. The most favorable effect was observed in patients with low hepatic tumor burden, normal baseline chromogranin A, and high tumoral SSTR5 expression. Median OS has not been reached; the 30-month OS rate was 70%. The best radiographic response was partial response in one patient (4%), stable disease in 17 patients (60%), and progressive disease in ten patients (36%). Although grade 3/4 toxicities were rare, pasireotide LAR treatment was associated with a 79% rate of hyperglycemia including 14% grade 3 hyperglycemia. Although pasireotide appears to be an effective antiproliferative agent in the treatment of advanced NETs, the high incidence of hyperglycemia raises concerns regarding its suitability as a first-line systemic agent in unselected patients. SSTR5 expression is a potentially predictive biomarker for response.

Anatomic modeling from unstructured samples using variational implicit surfaces

We describe the use of variational implicit surfaces (level sets of an embedded generating function modeled using radial basis interpolants) in anatomic modeling. This technique allows the practitioner to employ sparsely and unevenly sampled data to represent complex biological surfaces, including data acquired as a series of non-parallel image slices. The method inherently accommodates interpolation across irregular spans. In addition, shapes with arbitrary topology are easily represented without interpolation or aliasing errors arising from discrete sampling. To demonstrate the medical use of variational implicit surfaces, we present the reconstruction of the inner surfaces of blood vessels from a series of endovascular ultrasound images.

Human casein kinase Idelta phosphorylation of human circadian clock proteins period 1 and 2

Casein kinase Iepsilon (CKIepsilon), a central component of the circadian clock, interacts with and phosphorylates human period protein 1 (hPER1) [Keesler, G.A. et al. (2000) NeuroReport 5, 951-955]. A mutation in CKIepsilon causes a shortened circadian period in Syrian Golden hamster. We have now extended our previous studies to show that human casein kinase Idelta (hCKIdelta), the closest homologue to hCKIepsilon, associates with and phosphorylates hPER1 and causes protein instability. Furthermore, we observed that both hCKIdelta and hCKIepsilon phosphorylated and caused protein instability of human period 2 protein (hPER2). Immunohistochemical staining of rat brains demonstrates that CKIdelta protein is localized in the suprachiasmatic nuclei, the central location of the master clock. These results indicate that CKIdelta may play a role similar to CKIepsilon, suggesting that it may also be involved in regulating circadian rhythmicity by post-translation modification of mammalian clock proteins hPER1 and 2.

Nickel subsulfide is similar to potassium dichromate in protecting normal human fibroblasts from the mutagenic effects of benzo[a]pyrene diolepoxide

The cellular response to multiple carcinogen treatment has not been extensively studied, even though the effect of individual carcinogens is, in many cases, well known. We have previously shown that potassium dichromate can protect normal human fibroblasts from the mutagenic effects of benzo[a]pyrene diolepoxide (BPDE), and that this effect may be via an oxidative stress mechanism [Tesfai et al. (1998) Mutat Res 416:159-168]. Here, we extend our previous work by showing that nickel subsulfide can produce the some effect. Normal human fibroblasts, preincubated with nickel subsulfide for 46 hr followed by a coincubation of nickel subsulfide and BPDE for 2 hr, showed a dramatic reduction in the mutant frequency of the hypoxanthine (guanine)phosphoribosyl-transferase (HPRT) gene when compared to cells treated only with BPDE. The preincubation period with nickel subsulfide was necessary to see the antagonistic effect, since it was not observed if the cells were simply incubated with both carcinogens for 2 hr. The extent of the antagonistic effect was nickel subsulfide dose-dependent and also appeared to be species-specific, since the effect was not observed when Chinese hamster fibroblasts were tested. Finally, the antagonistic effect of the nickel subsulfide was eliminated by vitamin E, suggesting that production of reactive oxygen species by the nickel may be required. This data, along with our previous work, suggest that the antagonistic effect we observe is not chromium-specific, and that it could be species-specific.

Cloning and sequencing of human gp330, a Ca(2+)-binding receptor with potential intracellular signaling properties

We present here the complete primary structure of human gp330, the human variant of the principal kidney autoantigen causing Heymann membranous glomerulonephritis in rats. The deduced 4655 amino acid residues give a calculated molecular mass of 519636 Da for the mature protein and consists of a probable 25-amino-acid N-terminal signal peptide sequence, an extracellular region of 4398 amino acids, a single transmembrane-spanning domain of 23 amino acids, and an intracellular C-terminal region of 209 amino acid residues. Three types of cysteine-rich repeats characteristic of the low density lipoprotein receptor (LDLR) superfamily are present in human gp330. In the extracellular region, there are a total of 36 LDLR ligand-binding repeats, comprising four distinct domains, 16 growth factor repeats separated by eight YWTD spacer regions, and one epidermal growth factor-like repeat. No consensus cleavage sequence for the processing endoprotease furin is detected in human gp330. The intracellular tail contains not only two copies of the F(X)NPXY coated-pit mediated internalization signal characteristic of LDLR superfamily members, but also intriguing and potentially functional motifs including several Src-homology 3 recognition motifs, one Src-homology 2 recognition motif for the p85 regulatory subunit of phosphatidylinositol 3-kinase, and additional sites for protein kinase C, casein kinase II and cAMP-/cGMP-dependent protein kinase. There is approximately 77% amino acid identity between human and rat gp330 with minor differences between the extracellular and intracellular regions. Recently gp330 has been implicated in Ca2+ regulation in the parathyroid, the placenta, and the renal tubule, but its overall physiological and pathological role still remains uncertain.

The cloning of a receptor-type protein tyrosine phosphatase expressed in the central nervous system

We have isolated cDNA clones and deduced the complete amino acid sequence of a large receptor-type protein tyrosine phosphatase containing 2307 amino acids. The human gene encoding this phosphatase, denoted RPTP beta (or PTP zeta), has been localized to chromosome 7q31-33. RPTP beta is composed of a large extracellular domain, a single transmembrane domain, and a cytoplasmic portion with two tandem catalytic domains. We have also cloned a variant of RPTP beta lacking 859 amino acids from the extracellular domain but with intact transmembrane and cytoplasmic domains. Interestingly, the amino-terminal region of the extracellular domain of RPTP beta contains a stretch of 266 amino acids with striking homology to the enzyme carbonic anhydrase. Immunoprecipitation experiments from a human neuroblastoma cell line indicate that the apparent molecular mass of the core and glycosylated forms of RPTP beta are approximately 250 and 300 kDa, respectively. Northern blot analysis shows that RPTP beta is strictly expressed in the central nervous system. In situ hybridization was used to further localize the expression to different regions of the adult brain including the Purkinje cell layer of the cerebellum, the dentate gyrus, and the subependymal layer of the anterior horn of the lateral ventricle. Hence, RPTP beta represents the first mammalian tyrosine phosphatase whose expression is restricted to the nervous system. The high level of expression of RPTP beta transcripts in the ventricular and subventricular zones of the embryonic mouse brain suggests the importance of this tyrosine phosphatase in the development of the central nervous system.

Modulation of mdr-1 expression by a H-ras oncogene in a human colon carcinoma cell line

In an established colon differentiation model, introduction of a c-H-ras-1 oncogene into a poorly differentiated human colon carcinoma cell line (Clone A) results in changes associated with the acquisition of a more differentiated phenotype. Down-regulation of mdr-1 mRNA was shown to accompany ras-related differentiation events resulting in decreased Pgp synthesis and a significant reduction in membrane Pgp as detected by immunoprecipitation, Western-blot and FACS analysis. Consistent with these observations was a reduction in Pgp-mediated drug resistance associated with Clone-A ras transfectants, with no alteration in drug sensitivity being observed with non-MDR drugs in these cells. An alternative differentiation model involves exposure of Clone-A cells to sodium butyrate. Under these conditions, differentiation-related changes resulted in up-regulation of mdr-1 mRNA and Pgp synthesis, although no alteration in drug sensitivity was recorded. In agreement with this observation, the levels of membrane-associated Pgp remained unchanged throughout the period of exposure to sodium butyrate. This study shows that modulation of Pgp expression in colon differentiation is dependent upon the differentiation induction agent used.

Constitutive expression of multidrug resistance in human colorectal tumours and cell lines

In this study we report detection of mdr1 gene expression in the liver metastases of 7/11 patients with colon carcinoma and characterise the MDR phenotype associated with a panel of 19 human colon carcinoma cell lines. Within this panel, mdr1 mRNA biosynthesis and surface localisation of Pgp were assessed with respect to MDR functionality where the cell lines are representative of different clinical stages of tumour progression, metastatic potential and differentiation. The data indicates that constitutive levels of mdr1 mRNA/Pgp expression may not necessarily result in the functional expression of the MDR phenotype. While low levels of mdr1 mRNA/Pgp were detected in 5/8 well differentiated colon cell lines, only 2/8 were functionally MDR. In contrast, 10/11 moderate and poorly differentiated lines expressed mdr1 mRNA/Pgp and of these, 9/11 were functionally MDR. The phosphorylation status of the mature 170 kD P-glycoprotein and the surface localisation of this glycoprotein showed the strongest correlation with functionality. Analysis of cell lines for cross-resistance and chemosensitivity profiles against a battery of chemotherapeutic drugs suggests multiple mechanisms, in addition to Pgp, contribute to the overall resistance of colorectal cancer.

Identification of a carbonic anhydrase-like domain in the extracellular region of RPTP gamma defines a new subfamily of receptor tyrosine phosphatases

The tyrosine phosphatase RPTP gamma is a candidate tumor suppressor gene since it is located on human chromosome 3p14.2-p21 in a region frequently deleted in certain types of renal and lung carcinomas. In order to evaluate its oncogenic potential and to explore its normal in vivo functions, we have isolated cDNAs and deduced the complete sequences of both human and murine RPTP gamma. The murine RPTP gamma gene has been localized to chromosome 14 to a region syntenic to the location of the human gene. Northern (RNA) blot analysis reveals the presence of two major transcripts of 5.5 and 8.5 kb in a variety of murine tissues. In situ hybridization analysis reveals that RPTP gamma mRNA is expressed in specific regions of the brain and that the localization of RPTP gamma changes during brain development. RPTP gamma is composed of a putative extracellular domain, a single transmembrane domain, and a cytoplasmic portion with two tandem catalytic tyrosine phosphatase domains. The extracellular domain contains a stretch of 266 amino acids with striking homology to the zinc-containing enzyme carbonic anhydrase (CAH), indicating that RPTP gamma and RPTP beta (HPTP zeta) represent a subfamily of receptor tyrosine phosphatases. We have constructed a model for the CAH-like domain of RPTP gamma based upon the crystal structure of CAH. It appears that 11 of the 19 residues that form the active site of CAH are conserved in RPTP gamma. Yet only one of the three His residues that ligate the zinc atom and are required for catalytic activity is conserved. On the basis of this model we propose that the CAH-like domain of RPTP gamma may have a function other than catalysis of hydration of metabolic CO2.

Timing of induction of tgf-alpha in ras induced human bladder neoplastic progression

Introduction of a H-ras oncogene into an SV-40 immortalized human urothelial cell lines (SV-HUC) results in morphologically altered cell clones which acquire tumorigenic potential following serial passaging in culture. Early and late passage cells, from individual ras transfected clones exhibiting different tumorigenic potential, display increased growth factor synthesis in mitogenic assays. Northern blot analysis revealed induction of TGF-alpha mRNA concomitant with the introduction of a H-ras oncogene with no modulation in EGF receptor expression observed throughout neoplastic progression. Consistent with completion of an autocrine loop, down modulation and activation of EGF receptors was observed in early passage cells coincident with TGF-alpha expression. In this human urothelial progression model TGF-alpha secretion follows the introduction of a H-ras oncogene prior to the acquisition of tumorigenic potential.

Cloning of the human serotonin 5-HT2 and 5-HT1C receptor subtypes

We report the cloning and the deduced amino acid sequence of cDNAs encoding both the human serotonin 5-HT2 and 5-HT1C receptors. The human 5-HT2 and 5-HT1C receptors shared 87% and 90% amino acid homology, respectively, with their rat counterparts. The most divergent regions of the 5-HT2 receptor between human and rat were the N-terminal extracellular domain (75% homology) and the C-terminal intracellular domain (67% homology between amino acids 426-474). The greatest variability between the human and rat 5-HT1C receptors were at the N-terminal extracellular domain (78% homology) and the third cytoplasmic loop (71% homology). The availability of the cloned human 5-HT2 and 5-HT1C receptors will help facilitate the further understanding of the molecular pharmacology and physiology of these receptors.

Characterization of a human recombinant receptor-linked protein tyrosine phosphatase

The receptor-linked tyrosine phosphatase RPTP alpha from human brain (Kaplan, R., Morse, B., Huebner, K., Croce, C., Howk, R., Ravera, M., Ricca, G., Jaye, M., and Schlessinger, J. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7000-7004) was expressed in insect cells following infection with recombinant baculovirus. Two major forms of the enzyme, with molecular sizes of 98 kDa and 114 kDa, were detected by immunoblot analysis. This heterogeneity could be ascribed to N-linked glycosylation on the basis of two lines of evidence; namely, blockage of glycosylation with tunicamycin in vivo and removal of carbohydrates by endoglycosidase F in vitro. The 114-kDa form was purified to homogeneity by chromatography on Superose 12 and Mono Q. Compared to the low Mr placenta and T-cell tyrosine phosphatases, RPTP alpha displayed a low optimum pH of 6 and a high Km in the micromolar range toward two artificial substrates (tyrosyl-phosphorylated myelin basic protein and modified lysozyme, respectively). Most effectors had a different and often an opposite influence on phosphatase activity depending on the nature of the substrate and the pH at which the assays were performed. Determination of Km and Vmax values for RPTP alpha suggests that the enzyme could exist in low and high substrate affinity states.

Receptor protein-tyrosine phosphatase gamma is a candidate tumor suppressor gene at human chromosome region 3p21

PTPG, the gene for protein-tyrosine phosphatase gamma (PTP gamma), maps to a region of human chromosome 3, 3p21, that is frequently deleted in renal cell carcinoma and lung carcinoma. One of the functions of protein-tyrosine phosphatases is to reverse the effect of protein-tyrosine kinases, many of which are oncogenes, suggesting that some protein-tyrosine phosphatase genes may act as tumor suppressor genes. A hallmark of tumor suppressor genes is that they are deleted in tumors in which their inactivation contributes to the malignant phenotype. In this study, one PTP gamma allele was lost in 3 of 5 renal carcinoma cell lines and 5 of 10 lung carcinoma tumor samples tested. Importantly, one PTP gamma allele was lost in three lung tumors that had not lost flanking loci. PTP gamma mRNA was expressed in kidney cell lines and lung cell lines but not expressed in several hematopoietic cell lines tested. Thus, the PTP gamma gene has characteristics that suggest it as a candidate tumor suppressor gene at 3p21.

Comparison of EGF receptor sequences as a guide to study the ligand binding site

While murine and human EGF-receptor (EGF-R) bind mammalian EGF with high affinity their chicken counterpart has approximately 300 fold reduced binding affinity towards mammalian EGF. We now cloned and sequenced the extracellular ligand binding domain of murine EGF-R in order to define the amino-acids which comprise the binding site for EGF. Comparison of human, murine and chicken EGF-R allows the identification of amino acid substitutions which are conservative and would not affect EGF binding, substitutions which are responsible for the low affinity binding of EGF to chicken EGF-R and those responsible for the high affinity binding of EGF to mammalian EGF-R. This analysis will enable future design of point mutations in the EGF-R which will restore the high affinity binding for EFG typical of human or murine EGF-R.

Cloning of three human tyrosine phosphatases reveals a multigene family of receptor-linked protein-tyrosine-phosphatases expressed in brain

A human brainstem cDNA library in bacteriophage lambda gt11 was screened under conditions of reduced hybridization stringency with a leukocyte common antigen (LCA) probe that spanned both conserved cytoplasmic domains. cDNA encoding a receptor-linked protein-tyrosine-phosphatase (protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48), RPTPase alpha, has been cloned and sequenced. Human RPTPase alpha consists of 802 amino acids. The extracellular domain of 150 residues includes a hydrophobic signal peptide and eight potential N-glycosylation sites. This is followed by a transmembrane region and two tandemly repeated conserved domains characteristic of all RPTPases identified thus far. The gene for RPTPase alpha has been localized to human chromosome region 20pter-20q12 by analysis of its segregation pattern in rodent-human somatic cell hybrids. Northern blot analysis revealed the presence of two major transcripts of 4.3 and 6.3 kilobases. In addition to RPTPase alpha, two other RPTPases (beta and gamma), identified in the same screen, have been partially cloned and sequenced. Analysis of sequence comparisons among LCA, the LCA-related protein LAR, and RPTPases alpha, beta, and gamma reveals the existence of a multigene family encoding different RPTPases, each containing a distinct extracellular domain, a single hydrophobic transmembrane region, and two tandemly repeated conserved cytoplasmic domains.

Somatic mutation and transcriptional deregulation of myc in endemic Burkitt's lymphoma disease: heptamer-nonamer recognition mistakes?

We examined the structure and expression of the myc protooncogene in DNA extracted from a primary (uncultured) endemic Burkitt's lymphoma sample designated eBL3. Dot and Northern (RNA) blot analyses demonstrated extreme levels of myc RNA in the eBL3 sample. Nearly complete sequence data of the altered myc locus isolated from eBL3 DNA demonstrated extensive mutations (duplications, insertions, and deletions) in critical myc regulatory regions. Taken together, the data support the idea that myc transcriptional deregulation in Burkitt's lymphoma disease may be a consequence of the position and number of mutations produced within and around the myc locus. Furthermore, the myc exon-1-intron-1 hypermutable PvuII site is part of a potential heptamer-nonamer recognition sequence, suggesting a mechanism for mutation in endemic Burkitt's lymphoma disease.

Insertional mutagenesis of the myc locus by a LINE-1 sequence in a human breast carcinoma

The proto-oncogene c-myc is the cellular homologue of the transforming sequence carried by the avian myelocytomastosis virus MC29. A growing body of evidence implicates structural and functional alterations in and around proto-oncogenes such as c-myc in tumorogenesis. Here we report that comparison of the structure of myc from a ductal adenocarcinoma of the breast and from normal breast tissue of the same patient (Sc) revealed a tumour-specific rearrangement of one myc locus and amplification of the other myc locus. (For myc reviews see refs 1-4; for myc involvement in breast neoplasia see refs 5-7.) Within the second intron of the rearranged locus was a non-myc sequence with nearly complete homology to a long interspersed repetitive element (a LINE-1 sequence or L1). In this case, the L1 sequence has functioned as a mobile genetic element to produce a somatic mutation.

Homologous recombination between autonomously replicating plasmids in mammalian cells

The ability of autonomously replicating plasmids to recombine in mammalian cells was investigated. Two deletion plasmids of the eukaryotic-prokaryotic shuttle vector pSV2neo were cotransfected into transformed monkey COS cells. Examination of the low molecular weight DNA isolated after 48 hr of incubation revealed that recombination between the plasmids had occurred. The DNA was also used to transform recA- E. coli. Yield of neoR colonies signified homologous recombination. Examination of the plasmid DNA from these colonies confirmed this view. Double-strand breaks in one or both of the input plasmids at the sites of deletion resulted in an enhancement of recombination frequency. The recombination process yielded monomeric and dimeric molecules. Examination of these molecules revealed that reciprocal recombination as well as gene conversion events were involved in the generation of plasmids bearing an intact neo gene. The COS cell system we describe is analogous to study of bacteriophage recombination and yeast random-spore analysis.

In-utero gunshot wound to the head. Use of intraoperative ultrasonography for localization of an intracerebral projectile

Approaching full gestational age, a 1700-g male fetus sustained a penetrating gunshot wound to the left parietal region of the head while in utero. The child was delivered by emergency caesarean section. Initially in profound fetal shock and with almost no neurological function, the child was eventually stabilized. A posttraumatic intracerebral porencephalic cyst developed, with the projectile moving freely within the confines of the cyst cavity. Six weeks after the initial injury, the patient underwent an operation for extraction of the projectile. The Neuro SectOR ATL ultrasound probe was used intraoperatively and was instrumental in determining the exact position of the intracerebral projectile.

Abdominal aspiration biopsies. Sonographic v computed tomographic guidance

One hundred eighty-four diagnostic aspirations performed on 169 patients were reviewed (1) to define the decision process regarding which guidance method (sonography v computed tomography) should be used on any given patient, and (2) to determine, once a guidance method was chosen, its accuracy and complication rate. Sonographic guidance (84%) proved to be an effective method for obtaining a correct diagnosis in 98% (110/112) of cystic masses and 79% (34/43) of solid masses. Computed tomography (16%) was used when sonography could not identify the mass or when the mass was small, deeply located, and often solid. Computed tomographic guidance provided a correct diagnosis in 100% (13/13) of cystic masses and 81% (13/16) of solid masses.

The role of percutaneous aspiration in the diagnosis of pancreatic abscess

Percutaneous aspiration should be performed on pancreatic/peripancreatic fluid collections when an abscess is suspected. Thirty-one percutaneous aspirations were performed on 21 such patients and seven (33%) proved to have an abscess. A Gram stain after the aspiration is important, as it can make an immediate diagnosis of an abscess. By helping make an early diagnosis, percutaneous aspiration might reduce the high mortality rate associated with a pancreatic abscess while avoiding surgery in those who have sterile fluid collections. Two complications (6%) occurred: superinfection of a pseudocyst and a hemoperitoneum.

Role of two-dimensional surface characteristics in pictorial depth perception

The purpose of the present experiment was to test the hypothesis that flat surface information for the plane of projection is the essential difference between ordinary and pictorial perception. Adults were asked to make relative size judgments of pairs of squares and triangles placed and pictured at various distances. The conditions were: real scene controls, life-size slides and prints, and real scenes viewed through clear glass, textured glass, a screen and a 50-mm lens. The error rate was significantly lower with real scenes than with either slides or prints which did not differ. The control data for real scenes were used for comparison to test for the effects of interposed flat surfaces on size judgments of real scenes. Viewing real scenes through either a clear glass pane or a 50-mm lens increased the error rate two and one-half times that of the controls for real scenes. Neither textured glass nor a screen significantly affected error rate. Results were interpreted as supporting the hypothesis that information about a flat surface for the plane of projection is the critical variable determining the special character of picture perception.

Erythrokinetics and ferrokinetics of a viral-induced murine erythroblastosis

A variant of Rauscher leukemia virus, designated RLV-A, induced a slow progressive impairment of erythropoiesis in BALB/c mice. Identified in this study were a shortened red cell 51-cr half-time, anemia with indices showing minimal but significant hypochromia, ineffective erythropoiesis, and infiltration of the liver, spleen, and peripheral blood with erythroid pecursors. Ferrokinetic studies indicated a normal plasma iron turnover in infected mice but a decreased red cell iron turnover. Large amounts of 59Fe were taken up by the enlarged liver and spleen. Peak splenic heme 59Fe synthesis was delayed 12 hr in the infected mice. The substantial increase in the splenic intraerythrocytic nonheme iron pool and the hypochromic indices indicate a process analogous to that seen in the sideroblastic anemias. The disease produced by this RLV-A variant may prove useful for studying various aspects of the preleukemic sideroblastic anemias and DiGuglielmo syndrome.