Biomedical subjects

R J Bold

Publications and source records attributed to R J Bold.

46 records · Page 3Linked to original sources

PubMed1993

Biomolecular advances in gastrointestinal hormones.

Gastrointestinal hormones are chemical messengers that regulate a broad range of physiologic functions. Although primarily expressed within tissues of the gut, these peptide hormones are widely distributed throughout the body and act on multiple target tissues. Furthermore, these regulatory peptides can exist in multiple molecular forms that may bind to multiple cell-surface receptors coupled to one of several possible signal transduction systems leading to diverse biologic responses. With such an expansive field to study, it is not surprising that gut endocrinologists have embraced the new techniques that are emerging from the revolution of molecular biology. Beginning with the first construction of a recombinant DNA molecule by Paul Berg in 1971, molecular biology has developed many new techniques that have been rapidly adopted by gut endocrinologists to enable a more detailed understanding of gastrointestinal function. The merging of these two fields has led to a new area of research, molecular gut endocrinology, or the study of gut physiology and endocrinology at the level of individual molecules (ranging from polypeptide-surface receptors to small-molecule second messengers to DNA sequences). Gut cells are constantly bombarded by numerous hormones, and the tightly regulated physiologic status of each cell is becoming more clearly understood.

Animals↗

PubMed1993

Bombesin stimulates intracellular Ca2+ mobilization but not proliferation on human colon cancer cells.

Increases in intracellular Ca2+ ([Ca2+]i) levels mediated by bombesin (BBS) are believed to be important signals leading to stimulation of DNA synthesis and an increase in cellular proliferative rate. Since the role of BBS on growth of normal or malignant cells in the GI tract is still unclear, we examined whether BBS affects in vitro growth of human colon cancer cells (COLO 320, HCT116 and LoVo). We also examined the effect of BBS on intracellular Ca2+ levels to determine if the growth-regulatory effect of BBS is mediated through increases in [Ca2+]i. Levels of [Ca2+]i in response to BBS were measured by single cell fluorescence after loading with fura-2. BBS stimulated the mobilization of [Ca2+]i in COLO 320, LoVo, and HCT116 cells in a dose-dependent fashion, but did not affect in vitro growth. These findings suggest that the BBS-mediated increase in [Ca2+]i does not always correlate with the growth-regulatory effect of BBS.

Bombesin↗

PubMed1986

Functions of the mos oncogene family and associated gene products.

The mos oncogene present in Moloney murine sarcoma virus is one of the oldest known oncogenes, yet the identification of its biochemical function both in transformation and as a cellular proto-oncogene has been elusive. Only recently have low levels of c-mos transcripts been detected in a specific group of mouse tissues. The c-mos gene is implicated in tumorigenicity by its activation by the insertion of the intracisternal A particle genome in a mouse plasmacytoma. The murine c-mos gene is capable of oncogenic transformation when placed under the regulatory control of a long terminal repeat. The acquisition of the v-mos gene generated the transformation-competent Moloney murine sarcoma virus and several related strains. Myeloproliferative sarcoma virus is unique among the v-mos containing viruses in its ability to induce splenic foci and myeloproliferation in vivo in addition to the transformation of fibroblasts. The v-mos gene product, termed p37mos, is a cytoplasmic protein recently shown to possess serine kinase activity in immune complexes. Autophosphorylation of the mos gene product is not necessary for its biological activity as exemplified by the protein HT1-MSV which lacks phosphoserine residues. A transcriptional regulatory property has been attributed to the v-mos gene product during infection, which may play an essential role in subsequent transformation.

Animals↗

PubMed1985

Biologically active mutants with deletions in the v-mos oncogene assayed with retroviral vectors.

We have constructed retroviral expression vectors by manipulation of the Moloney murine leukemia virus genome such that an exogenous DNA sequence may be inserted and subsequently expressed when introduced into mammalian cells. A series of N-terminal deletions of the v-mos oncogene was constructed and assayed for biological activity with these retroviral expression vectors. The results of the deletion analysis demonstrate that the region of p37mos coding region upstream of the third methionine codon is dispensable with respect to transformation. However, deletion mutants of v-mos which allow initiation of translation at the fourth methionine codon have lost the biological activity of the parental v-mos gene. Furthermore, experiments were also carried out to define the C-terminal limit of the active region of p37mos by the construction of premature termination mutants by the insertion of a termination oligonucleotide. Insertion of the oligonucleotide just 69 base pairs upstream from the wild-type termination site abolished the focus-forming ability of v-mos. Thus, we have shown the N-terminal limit of the active region of p37mos to be between the third and fourth methionines, while the C-terminal limit is within the last 23 amino acids of the protein.

Amino Acid Sequence↗

PubMedDate not supplied

Local rotational flaps for breast conservation therapy as an alternative to mastectomy.

BACKGROUND: An anticipated poor cosmetic result has traditionally been deemed a relative contraindication for breast conservation therapy (BCT). We sought to determine whether a local rotational flap could achieve satisfactory cosmesis in patients who were anticipated to have a poor cosmetic result following standard segmental mastectomy but who nevertheless desired BCT. METHODS: Within the past 3 years, nine patients were treated with BCT using local rotational flap techniques. Their records were reviewed for patient characteristics, pre- and postoperative treatment, disease-free status, and patient satisfaction with cosmesis. RESULTS: The cosmetic outcome following a segmental mastectomy was anticipated to be unacceptable due to the following features: a large previous biopsy cavity with unknown or positive margins (three patients); initial large primary tumors with unknown extent of residual disease following induction chemotherapy (five patients); and pre-existing poor cosmesis (one patient). One patient had refused modified radical mastectomy and had satellitosis from inadequately treated primary tumor (excisional biopsy with positive margins and no further therapy). The median initial tumor size was 2.7 cm (range, 1.5 cm to 5.0 cm). Final resection margins were negative in all patients. Postoperative radiotherapy was given in seven patients; one patient did not receive radiotherapy because of a pre-lupus condition and one did not require radiotherapy because her pathologic diagnosis was Paget's disease without an invasive component. Cosmesis was judged to be good to excellent by eight of nine patients. The patient who refused mastectomy was dissatisfied with cosmesis because of mild asymmetry. With a median follow-up of 24 months, only one patient has developed a local recurrence. CONCLUSION: Local rotational flaps composed of adjacent breast tissue are an acceptable method of achieving satisfactory cosmesis in selected patients who desire BCT.

Adult↗

PubMedDate not supplied

Gemcitabine-induced programmed cell death (apoptosis) of human pancreatic carcinoma is determined by Bcl-2 content.

BACKGROUND: Gemcitabine is a new nucleoside analogue that produces a clinical response in 30% of patients with unresectable pancreatic carcinoma. The cytotoxic effects of many chemotherapeutic agents occur through induction of programmed cell death (apoptosis), which is controlled by the bcl-2 gene family. We determined whether induction of apoptosis by gemcitabine in pancreatic carcinoma is associated with cellular Bcl-2 content. METHODS: Four pancreatic carcinoma cell lines (MIA-PaCa-2, AsPC-1, Panc-1, and Panc-48) were screened by Western blotting for Bcl-2 protein expression. Dose-response relationships for the cytotoxic effects of gemcitabine were determined using methylthiotetrazole assays, and induction of apoptosis was confirmed by fluorescence-activated cell sorting analysis. MIA-PaCa-2 cells transfected with human bcl-2 were also analyzed for gemcitabine-induced apoptosis. RESULTS: Pancreatic cancer cell lines expressed varying amounts of Bcl-2, and the 50% lethal dose for gemcitabine-induced apoptosis was correlated with Bcl-2 content. Furthermore, Bcl-2 overexpression was associated with a significant increase in the 50% lethal dose for gemcitabine-induced apoptosis. CONCLUSIONS: Cellular Bcl-2 content was directly correlated with the cytotoxicity of gemcitabine in pancreatic carcinoma. Therefore, routine immunohistochemical analyses may be useful in predicting gemcitabine efficacy, and patients who would likely not benefit could be spared gemcitabine administration. Furthermore, the effectiveness of gemcitabine and other chemotherapeutic agents may be increased by gene therapy-mediated alteration of bcl-2 gene family members.

Adenocarcinoma↗

PubMedDate not supplied

Epidemiology and molecular genetics of colorectal cancer.

Colorectal cancer is among the most common cancers affecting the western world. By the age of 70 yr, at least 50% of the Western population will develop some form of colorectal tumor, spanning the spectrum from an early benign polyp to an invasive adenocarcinoma. It is estimated that approximately 10% of the benign polypoid lesions will progress to invasive carcinoma. The concept that serial genetic changes are responsible for the transition from benign to neoplastic disease is not new. The description of hereditary cancers and the demonstration of carcinogenic substances inducing DNA damage have provided the foundation for the field of molecular oncology. During the past three decades, our understanding of how genetic alterations culminate in cancer has progressed rapidly, though the complete process has not been fully defined. The research to date has spanned many oncologic diseases, but has been especially well defined in colorectal cancer. The knowledge of the genetic alterations that result in colorectal cancer has important ramifications for future prevention, detection, and treatment of this disease.

Adenomatous Polyposis Coli↗

PubMedDate not supplied

Major vascular resection as part of pancreaticoduodenectomy for cancer: radiologic, intraoperative, and pathologic analysis.

Intraoperative assessment is inaccurate in defining the relationship of a pancreatic head neoplasm to adjacent vascular structures. We evaluated the ability of preoperative contrast-enhanced CT to predict the need for vascular resection during pancreaticoduodenectomy and examined the resected vessels for histologic evidence of tumor invasion. During a 7-year period, 63 patients underwent pancreaticoduodenectomy with en bloc resection of adjacent vascular structures for a presumed pancreatic head malignancy. Clinical, radiologic, operative, and pathologic data were reviewed and analyzed. Fifty-six patients underwent resection of the superior mesenteric-portal vein confluence, three patients required inferior vena cava resection, and the hepatic artery was resected and reconstructed in eight patients. The operative mortality rate was 1.6%, and the overall complication rate was 22%. CT predicted the need for resection of the superior mesenteric or portal veins in 84% of patients. Pathologic analysis revealed tumor invasion of the vein wall in 71% of resected specimens. Tumor invasion of vascular structures adjacent to the pancreas can be predicted with preoperative CT and should alert the surgeon that vascular resection may be required. Histologic evidence of tumor cell infiltration of vessel walls was present in the majority of the resected specimens.

Adenocarcinoma↗

PubMedDate not supplied

Prognostic factors in resectable pancreatic cancer: p53 and bcl-2.

The p53 tumor suppressor gene and the Bcl-2 proto-oncogene regulate cell cycle progression and apoptosis. We evaluated the expression of these molecular markers with standard pathologic prognostic variables in patients who received multimodality therapy for resectable adenocarcinoma of the pancreas to study the effect of p53 and Bcl-2 on survival duration. Immunohistochemical staining of archival material was performed to determine levels of expression of p53 and Bcl-2 proteins in 70 patients with adenocarcinoma of pancreatic origin. All patients underwent a potentially curative pancreaticoduodenectomy and standardized pathologic analysis of resected specimens. Potential pathologic and molecular prognostic variables were assessed for their effect on survival duration. Nuclear staining for p53 was observed in 33 (47%) of 70 specimens. Immunostaining for Bcl-2 was observed in 23 specimens (33%). A trend toward improved survival duration was seen in patients whose tumors stained positive for either p53 or Bcl-2. Negative staining for both markers predicted short survival (P = 0.01). By univariate and multivariate analyses, no single pathologic factor was associated with survival duration. Immunohistochemical staging using both p53 and Bcl-2 significantly predicted survival duration by univariate and multivariate analysis; patients whose tumors stained positively for p53 and/or overexpressed Bcl-2 had a significantly longer survival than those whose tumors stained negative for both proteins.

Adenocarcinoma↗

PubMedDate not supplied

Bombesin stimulates in vitro growth of human breast cancer independent of estrogen receptors status.

BACKGROUND: Approximately 180,000 women will be found to have breast cancer this year in the United States. Chemotherapy has limited success in advanced disease and the effect of tamoxifen appears to require a functional estrogen-receptor (ER). Our aim was to determine whether bombesin (BBS) regulates growth of human breast cancer cells. METHODS: Estrogen-dependent (MCF-7), estrogen-responsive (ZR-75-1) and estrogen-independent (MDA-MB-231) human breast cancer cells were studied. Receptors were identified by cross-linking methods and radioligand binding assays; intracellular calcium ([Ca2+]i) was measured after BBS treatment to confirm functional status of the receptor; and the effect of BBS on cell growth was measured directly. RESULTS: All three cell lines had a high affinity BBS receptor (Kd = 1-7 nM; molecular weight 75 kDa). BBS stimulated [Ca2+]i levels as well as cell growth in all three cell lines; the trophic effect was blocked by BBS receptor antagonists. CONCLUSIONS: We conclude that BBS is trophic for human breast cancers independent of ER status, and that antagonism of the BBS receptor may be a useful target for hormonal therapy in ER-negative breast cancer.

Bombesin↗