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Biomedical subjects

J Stauffer

Publications and source records attributed to J Stauffer.

17 recordsLinked to original sources
PubMed2003

Retinoic acid decreases targeting of p27 for degradation via an N-myc-dependent decrease in p27 phosphorylation and an N-myc-independent decrease in Skp2.

Poor prognosis neuroblastoma (NB) tumors are marked by amplification and overexpression of N-myc. Retinoic acid (RA) decreases N-myc levels and induces cell cycle arrest in vitro and increases event-free survival in advanced stage NB patients. In this study, we investigated the mechanism(s) by which RA regulates cell cycle and how N-myc affects NB cell cycle progression. Constitutive N-myc overexpression stimulates increases in cyclin E-dependent kinase activity and decreases in p27 resulting in increased DNA synthesis. N-myc regulates p27 levels through an increase in targeting of p27 to the proteasome via cyclin E kinase-dependent phosphorylation of p27 and its ubiquitination. N-myc also stimulates an increase in proteasome activity. In RA-treated cells in which N-myc levels decline as p27 levels increase, degradation of p27 is also decreased. However, RA does not affect the activity of proteasome. The decrease in the degradation of p27 in RA-treated cells is due in part to a decrease in the N-myc stimulated phosphorylation of p27. However, RA also decreases Skp2 levels thus impairing the ability of p27 to be ubiquitinated. Thus, RA induces both N-myc-dependent and -independent mechanisms to minimize the degradation of p27 and arrest NB cell growth.

Cell Cycle↗
PubMed2001

Bidirectional endoscopy in patients with fecal occult blood.

BACKGROUND: Current screening protocols for colorectal cancer depend primarily on fecal occult blood testing (FOBT). However, positive test results do not always indicate the presence of a colonic neoplasm. METHODS: We reviewed the results of 100 consecutive bidirectional (upper and lower) endoscopic procedures performed to evaluate positive FOBT results. Patients were excluded if they presented with gross bleeding, a history of bowel lesions, or previous intestinal operations. There were 31 women and 69 men whose mean age was 51 years. RESULTS: Major abnormalities were found on esophagogastroduodenoscopy (n = 24), colonoscopy (n = 13), or both studies (n = 2). Active bleeding was manifested in two patients, (Barrett's ulcer, duodenal arteriovenous malformation). Two other patients had malignancy: One had a cecal adenocarcinoma and the other a gastric adenocarcinoma. Various benign lesions also were identified in the stomach including esophagitis (n = 8), ulcers/erosions (n = 8) varices (n = 5), and arteriovenous malformations (n = 2). Colonic pathology included polyps (n = 8), arteriovenous malformations (n = 3), and rectal varices (n = 1). Diverticulosis and hemorrhoidal disease were present in 29 and 16 patients, respectively, but were not considered to be likely sources of a positive FOBT. CONCLUSION: Positive FOBT results may indicate the presence of either upper or lower intestinal pathology, and bidirectional endoscopy is an efficient and accurate technique for the comprehensive evaluation of occult bleeding.

Adenocarcinoma↗
PubMed1996

Transcriptional control of muscle plasticity: differential regulation of troponin I genes by electrical activity.

Plasticity of the skeletal muscle phenotype can result from the selective repression and activation of gene expression in response to innervation patterns. Motoneurons, eliciting different patterns of depolarization, regulate the contractile properties of the myofibers they innervate by selectively activating expression of genes encoding fiber-type-specific (fast vs. slow) contractile proteins. We have analyzed the regulation of the troponin I slow (TnIs) and fast (TnIf) genes as a model to study the molecular mechanisms regulating fiber-type plasticity. We found that expression of the two TnI isoforms is downregulated by denervation. Moreover, TnI expression is upregulated by specific patterns of electrical activity [10 Hz vs. 100 Hz] used to depolarize muscle. We previously isolated the rat TnIs gene and demonstrated that regulatory sequences reside in its upstream region and second intron [Banerjee-Basu S, Buonanno A (1993), Mol Cell Biol 12:5024-5032]. Using transgenic mice, we show that the upstream region of the TnIs gene extending from -949 to +50 is sufficient to confer transcription specifically in slowtwitch muscles. Serial deletions of the TnIs upstream and intronic regions were generated in a CAT reporter vector to delineate transcriptional regulatory elements in transiently transfected Sol8 myotubes. Sequences necessary to confer the highest levels of TnIs transcription mapped to the upstream region between -0.95 and -0.72 kb, and to a 56 bp sequence located in the second intron. Comparison of the at sequence between -0.95 and -0.72 to the human TnIs gene identified a highly homologous region of 128 bp that we named the TnI SURE (slow upstream regulatory element). Alignment of these two SURE sequences with the quail TnI fast intronic regulatory element identified common motifs, namely, two A/T-rich sequences (A/T1 and A/T2) with homology to homeotic protein and MEF2 binding sites, a CACC box, an E box, and a novel motif (GCAGGCA) that we denoted the CAGG box. Mutation of either the A/T2 site, E box, or CAGG box practically abolish the SURE function in transfected myotubes; mutation of the A/T1 and CACC sites has a lesser effect. Using competitive electrophoretic mobility shift assays with nuclear extracts derived from Sol8 myotubes, we demonstrate specific binding to these motifs. The A/T1 and A/T2 sites are shown to form different complexes. The A/T2 site, which bears extensive homology to a MEF2 site, forms complexes that are super shifted by MEF2A antisera and that are competed by a consensus MEF2 site present in the MCK enhancer. Our results demonstrate that the linear arrangement of DNA sequence motifs is conserved in the regulatory elements of the TnI slow and fast genes and suggest that the interaction of multiple protein-DNA complexes are necessary for enhancer function.

Animals↗
PubMed1996

Common core sequences are found in skeletal muscle slow- and fast-fiber-type-specific regulatory elements.

The molecular mechanisms generating muscle diversity during development are unknown. The phenotypic properties of slow- and fast-twitch myofibers are determined by the selective transcription of genes coding for contractile proteins and metabolic enzymes in these muscles, properties that fail to develop in cultured muscle. Using transgenic mice, we have identified regulatory elements in the evolutionarily related troponin slow (TnIs) and fast (TnIf) genes that confer specific transcription in either slow or fast muscles. Analysis of serial deletions of the rat TnIs upstream region revealed that sequences between kb -0.95 and -0.5 are necessary to confer slow-fiber-specific transcription; the -0.5-kb fragment containing the basal promoter was inactive in five transgenic mouse lines tested. We identified a 128-bp regulatory element residing at kb -0.8 that, when linked to the -0.5-kb TnIs promoter, specifically confers transcription to slow-twitch muscles. To identify sequences directing fast-fiber-specific transcription, we generated transgenic mice harboring a construct containing the TnIs kb -0.5 promoter fused to a 144-bp enhancer derived from the quail TnIf gene. Mice harboring the TnIf/TnIs chimera construct expressed the transgene in fast but not in slow muscles, indicating that these regulatory elements are sufficient to confer fiber-type-specific transcription. Alignment of rat TnIs and quail TnIf regulatory sequences indicates that there is a conserved spatial organization of core elements, namely, an E box, a CCAC box, a MEF-2-like sequence, and a previously uncharacterized motif. The core elements were shown to bind their cognate factors by electrophoretic mobility shift assays, and their mutation demonstrated that the TnIs CCAC and E boxes are necessary for transgene expression. Our results suggest that the interaction of closely related transcriptional protein-DNA complexes is utilized to specify fiber type diversity.

Animals↗
PubMed1996

Linkage of a gene for macular corneal dystrophy to chromosome 16.

Autosomal recessive macular corneal dystrophy (MCD) is a heterogeneous disorder leading to visual impairment. Sixteen American and Icelandic families (11 type I and 5 type II) were analyzed for linkage, by use of 208 polymorphic microsatellite markers. A significant maximum LOD score Zmax of 7.82 at a maximum recombination fraction (thetamax) of .06 was found with the 16q22 locus D16S518 for MCD type I. In addition, a peak LOD score of 2.50 at a recombination fraction of .00 was obtained for the MCD type II families, by use of the identical marker. These findings raise the possibility that MCD type II may be due to the same genetic locus that is involved in MCD type I.

Americas↗
PubMed1996

Squamous cell carcinoma of the esophagus.

The role of surgery as primary treatment for patients with squamous cell carcinoma of the esophagus (SCCE) has been challenged by an improved response rate for radiotherapy that is made possible by adding radiosensitizing chemotherapy. The purpose of our study was to review our institution's treatment results for SCCE and to compare results of radiation versus surgery as primary treatment of early stage disease. A retrospective chart review was done on 241 patients who were treated with SCCE at Kansas University Medical Center and affiliated hospitals between 1970 and 1990. Patients were divided into five groups based on treatment received: (A) No Treatment; (B) Surgery Only; (C) Surgery plus Adjuvant Chemoradiotherapy; (D) Radiation Therapy Only; and (E) Chemoradiotherapy. Surgical treatment groups B and C had the best overall survival of all groups. To reduce any bias due to stage differences in groups, survival of groups was assessed only for early stage disease patients (Stage I, IIa, IIb). For Stage I and II patients receiving surgery as primary treatment (groups B and C), 29 per cent had a survival at 5 years compared to patients receiving primary radiation treatment (groups D and E) who had a combined survival of only four per cent. Although attempting comparison of risk groups is always a problem in nonrandomized studies, it is significant that only one 5-year survivor was in the nonresection radiation treatment groups D and E. Surgical resection for SCCE had the best survival in our study, especially in patients with early stage disease.

Adult↗
PubMed1985

Comparative chromosome analysis of nine squamous cell carcinoma lines from tumors of the head and neck.

The chromosomes of nine cell lines from human squamous cell carcinomas of the head and neck were examined. Five of the lines were derived from patients who had received chemotherapy and radiotherapy, one line was derived from a lymph-node metastasis from one of these patients, and three lines were from patients who had not been treated. The cell lines from the untreated patients had lower modal chromosome numbers than those of all but one of the lines from the treated patients. A structural abnormality involving chromosome 1 with breakpoints located in p13, p22, q21, or q32 was found in all cases. The NRAS and SK oncogenes are located in or near some of these segments. In four of the cell lines the nucleolus organizer regions (NORs) were 10-30 times larger than the NORs of the normal human chromosomes. Double minutes (DM) and homogeneously staining regions (HSR) were found in four of the lines.

Carcinoma, Squamous Cell↗
PubMed1976

Human alpha-crystallin. I. The isolation and characterization of newly synthesized alpha-crystallin.

Studies of the incorporation of 14C amino acids into human lens proteins demonstrate that an alpha-crystallin fraction takes up more than six times as much radioactivity as any other lens protein. Based on analyses with a calibrated Bio-Gel A-1.5 m column, a molecular weight of 4.9 x 10(5) +/- 5 per cent was obtained for this protein while sedimentation equilibrium analyses indicated a weight average molecular weight, Mw, of 7.5 x 10(5) +/- 4 per cent at 10,000 r.p.m. Gel electrophoresis in sodium dodecyl sulfate revealed two components with molecular weights of 22,000 and 20,000, values similar to those found with calf alpha-crystallin. Alkaline urea gel electrophoresis indicated one major polypeptide with a mobility similar to the B2 chain of calf alpha-crystallin and two major bands with mobilities between those of the calf alpha-crystallin A2 and A1 chains. Amino acid analyses of this newly synthesized alpha-crystallin gave a composition which with a few exceptions is very similar to that of calf alpha-crystallin. All three major polypeptides contained 14C amino acids. However, from the present data, it cannot be determined whether the three polypeptides were independently synthesized or a rapid transformation produced one of the labeled polypeptides in the A region. There appears to be between three and four times as many presumptive A as B polypeptides.

Amino Acids↗
PubMedDate not supplied

Selection factors in the choice of immunoassay technology: implementing technology in the new era.

Centralized Laboratory Services, Inc. is a large, freestanding laboratory that underwent a major equipment reconfiguration for the performance of endocrine/tumor marker/anemia assays (N = 15) in August 1995. Before the transition these assays were done on six instruments, none of which were computer interfaced. All assays were subsequently consolidated on four ACS-180+ instruments (Chiron Diagnostics, Norwood, MA), which were interfaced to our laboratory information system (Cerner Corp, Kansas City, MO). Our experience suggests that significant increases in productivity and reductions in cost are possible through instrument upgrades. Both laboratory-specific and analytical system-specific factors were found to be important in the optimal selection of immunoassay technology. As laboratorians necessarily adjust to changing economic and organizational circumstances and are compelled to "do more with less," technology assessment will become an increasingly important function for senior laboratory management.

Clinical Laboratory Information Systems↗
PubMedDate not supplied

The role of reflexive (algorithmic) testing in laboratory medicine: adapting to the new era.

Centralized Laboratory Services, Inc. (CLS) is a large, freestanding laboratory that is an affiliate of the Health Insurance Plan of New York, a managed care organization with more than 1 million members in New York and New Jersey. The laboratory work for this membership is consolidated at CLS, which thus serves an ambulatory patient population. The Medical Director at CLS is charged with optimizing laboratory utilization by clinicians who are part of the system.

Algorithms↗
PubMedDate not supplied

Utilization management and information technology: adapting to the new era.

Overuse of clinical laboratory services has been written about for many years (1), but remedies that easily could be implemented and effective over the long term have been in short supply. This issue has been acute for CLS, Inc., which is wholly owned by a managed care organization (HIP Health Plan of New York). Because CLS is assessing the possibility of acquiring a new laboratory information system, we reviewed past reports on approaches to utilization management (UM) and considered how developments in information technology (IT) may affect the latter. We feel there is a distinct possibility for implementation of UM in real time, and we propose this as a new paradigm whose realization has implications for choice of IT and for how clinical laboratories operate in the future.

Clinical Laboratory Information Systems↗