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Biomedical subjects

R D Beauchamp

Publications and source records attributed to R D Beauchamp.

At least 73 records · Page 4Linked to original sources

Selective functional posterior rhizotomy for treatment of spastic cerebral palsy in children. Review of 50 consecutive cases.

Fifty consecutive children are described with spastic cerebral palsy treated with selective functional lumbar and sacral rhizotomy and followed for a minimum of 6 months. In all patients, spasticity improved postoperatively, but this was not necessarily accompanied by a functional improvement. Eighteen children who could not walk preoperatively were able to do so after rhizotomy. All 17 children who could walk preoperatively could do so following surgery, and in 15, gait was improved. Complications included transient urinary dysfunction in 4 children and sensory loss in 1. The operative procedure evolved with time: the technique of replacement laminotomy was refined; the electrophysiologic basis for selection of nerve rootlets changed after studies of nonspastic controls; smaller percentages of the L3 and L4 roots were sectioned in an attempt to prevent postoperative weakness of quadriceps, and there was a trend in the most recent patients to cut a smaller portion of all the posterior roots.

Adolescent↗

Phenotypic alterations in fibroblasts and fibrosarcoma cells that overexpress latent transforming growth factor-beta 1.

Mouse embryo-derived AKR-2B fibroblasts and murine fibrosarcoma cells (the 1591 cell line) were transfected with a murine transforming growth factor-beta 1 (TGF beta 1) cDNA under the transcriptional control of either the simian virus-40 early promoter or the cytomegalovirus promoter/enhancer. Selected clones secreted 2- to 4-fold more TGF beta-competing activity into their media than the parental cell line or neomycin-transfected controls. The TGF beta 1 released into the cell-conditioned medium was latent. Despite the latency of the overexpressed TGF beta 1, TGF beta 1-transfected cells exhibited phenotypic features of TGF beta 1-treated cells. When confluent, the TGF beta 1-transfected cells had the morphological characteristics of the parental cells that have been treated with active TGF beta 1. AKR-2B cells that expressed higher levels of TGF beta 1 also expressed high levels of c-sis and c-myc mRNAs and decreased TGF beta 2 and TGF beta 3 mRNAs in the same manner as parental AKR-2B cells that had been treated with active TGF beta 1. The transfected 1591 cells that overexpressed TGF beta 1 bound less [125I]TGF beta 1 than did parental 1591 cells, but after a mild acid wash demonstrated an increase in [125I]TGF beta 1 binding. Our results suggest that these TGF beta 1-transfected fibroblast and fibrosarcoma cells have the capacity to activate TGF beta; however, as very little activated TGF beta is detected in the medium, it is hypothesized that these cells activate latent TGF beta 1 and bind the activated TGF beta 1, thus acquiring a phenotype consistent with TGF beta 1-treated cells.

Animals↗

Posttranscriptional regulation of albumin and alpha-fetoprotein messenger RNA by transforming growth factor-beta 1 requires de novo RNA and protein synthesis.

Transforming growth factor-beta (TGF beta) has been implicated in the regulation of hepatocyte function. We have examined TGF beta 1 regulation of albumin and alpha-fetoprotein (AFP) mRNA levels in a well differentiated mouse hepatoma cell line (BWTG3). TGF beta 1 reversibly decreased steady state mRNA levels of both albumin and AFP. By nuclear run-on assays, we found that TGF beta 1 caused no significant change in transcription rates for albumin or AFP. Pretreatment with actinomycin-D prevented the TGF beta 1-induced decrease in albumin and AFP mRNA levels. Also, if cells were treated with actinomycin-D after a 12-h exposure to TGF beta 1, actinomycin-D abrogated the further decrease in albumin and AFP mRNA levels that occurred after treatment with TGF beta 1 alone. Cycloheximide pretreatment blocked the TGF beta 1-induced decrease in albumin and AFP mRNA levels. TGF beta 1 altered neither the rate of BWTG3 cell growth nor the levels of mRNA for the growth-associated protooncogene c-myc. These data suggest that TGF beta 1 has regulatory effects on specific hepatocyte functions that are independent of growth regulatory effects. The decrease in albumin and AFP mRNAs caused by TGF beta 1 is posttranscriptional and dependent upon de novo RNA and protein synthesis.

Albumins↗

Bombesin stimulates growth of human gastrinoma.

BACKGROUND: We have previously reported the first establishment and characterization of a functioning human gastrinoma (PT) xenograft. Bombesin, the equivalent of the mammalian gastrin-releasing peptide, has trophic effects on normal and neoplastic tissues of the gastrointestinal tract; the effects of gut hormones on the growth of gastrinoma are not known. The purpose of this study was twofold: (1) to determine the presence of various gut peptides in PT and (2) to determine the effect of bombesin on the growth of PT xenografts. METHODS: PT tumors were examined for expression (mRNA and protein) of various gut peptides by Northern hybridization and immunohistochemistry. In addition, PT xenografts were implanted as 3 mm2 pieces bilaterally subcutaneously in athymic nude mice. Mice were divided into two groups to receive either bombesin (5 micrograms/kg) or saline administered as intraperitoneal injections every 8 hours. Tumor area was measured twice weekly until mice were sacrificed (day 28), when tumor and normal pancreas were removed, weighed, and assayed for DNA and protein content. RESULTS: Both mRNAs and peptides of gastrin and chromogranin A were present in PT tumors. Bombesin significantly stimulated growth of PT tumors from day 18 until mice were sacrificed (day 28). As expected, bombesin stimulated pancreatic growth. CONCLUSIONS: We have demonstrated for the first time that bombesin is a trophic hormone for gastrinoma. The unique cell line PT contains gastrin and chromogranin A and will be a useful model to define the biologic mechanisms controlling the growth of human gastrinomas.

Animals↗

Human carcinoid cell production of paracrine growth factors that can stimulate fibroblast and endothelial cell growth.

A serotonin-secreting human pancreatic carcinoid cell line (BON) is demonstrated to express transcripts for all three mammalian types of transforming growth factor beta (TGF beta 1, 2, and 3). Similarly, freshly excised carcinoid tumors from six patients were also found to express mRNA for all three of the type-beta TGFs. Medium conditioned by BON cells had detectable TGF beta activity, although most of the activity was latent as determined by radioreceptor assay with and without prior acid treatment. However, nonactivated BON-conditioned medium stimulated DNA synthesis, soft agar growth, and an increase in TGF beta 1 and fibronectin mRNA expression in AKR-2B fibroblasts. In addition, BON-conditioned medium had a potent endothelial cell growth-stimulatory activity. Since the TGF beta s inhibit growth of endothelial cells, the presence of other growth factors was suspected. TGF alpha, c-sis, and basic fibroblast growth factor transcripts were also found to be expressed by the BON carcinoid cells. These data indicate that multiple peptide growth factors may have a paracrine role in the desmoplastic reaction accompanying carcinoid tumors.

Amino Acid Isomerases↗

Systemic alterations in ornithine decarboxylase activity caused by colon cancer in mice.

Tumors are known to cause profound changes in host biology, but the mechanisms responsible for these changes remain unclear. Ornithine decarboxylase (ODC) is a rate-limiting enzyme that catalyzes the biosynthesis of polyamines. The purpose of this study was to examine the effects of MC-26 tumor burden on ODC activity in the gastrointestinal tract, kidney and liver of mice. Forty-four Balb/c mice were randomly divided into 2 groups and the test group was pair-fed (to control). Group 1 was the tumor-free control. Group 2 was inoculated subcutaneously with 5 x 10(5) MC-26 cells. The ODC activity in the kidney and liver of tumor-bearing mice was significantly lower compared to tumor-free controls at sacrifice. ODC activity in the colon increased almost 4-fold. These results suggest that the presence of MC-26 tumor causes systemic effects that alter ODC activity. The tumor may elaborate a substance that suppresses ODC activity in some normal tissues while stimulating ODC activity in the tissue from which the tumor was derived.

Animals↗

Differential effects of sodium butyrate and hexamethylene bisacetamide on growth and secretion of cultured human endocrine tumor cells.

Advanced gastrointestinal endocrine tumors respond poorly to conventional chemotherapy. In this study we examined the effects of two agents that promote cellular differentiation, sodium butyrate and hexamethylene bisacetamide, on the in vitro growth and secretory responses of a human pancreatic carcinoid (BON) and human gastrinoma (PT-2 and PT-SM) cell lines that have been established in our laboratory. We found that both sodium butyrate and hexamethylene bisacetamide strongly inhibited growth of BON, PT-2, and PT-SM cells. With continuous exposure of BON cells to sodium butyrate (2 mmol/L), the doubling time was prolonged, from 60 hours in controls to 156 hours, and saturation density was reduced to 28% that of controls. Hexamethylene bisacetamide (4 mmol/L) reduced saturation density to 37% that of controls in BON cells and prolonged the doubling time, from 60 hours to 103 hours. Antiproliferative effects of similar magnitudes were observed in the gastrinoma cell lines. In contrast, differential effects were produced on amine biosynthesis in BON cells; sodium butyrate stimulated levels of 5-hydroxytryptamine in the cells, whereas hexamethylene bisacetamide caused a profound dose-dependent inhibition of amine biosynthesis. The significant antiproliferative activity of sodium butyrate and hexamethylene bisacetamide and the inhibitory effects of hexamethylene bisacetamide on amine biosynthesis warrant evaluation of these agents or analogues for treatment of metastatic carcinoid and gastrinoma.

5-Hydroxytryptophan↗

Vasoactive intestinal polypeptide inhibits c-myc expression and growth of human gastric carcinoma cells.

Vasoactive intestinal polypeptide (VIP) is a gut neuroendocrine polypeptide that increases cyclic adenosine monophosphate (cAMP) production in cells with VIP receptors. Some gastrointestinal cancer cells possess functional receptors for VIP; however, the role of VIP in regulation of growth of gastric cancer cells has not been determined. The purpose of this study was to determine whether VIP and other agents that increase cAMP regulate growth of a human gastric cancer cell line (AGS) and whether these agents regulate expression of c-myc proto-oncogene, which is required for cell proliferation. We measured levels of cAMP by radioimmunoassay, and we used Northern blot analysis to examine c-myc messenger RNA expression. Cell-growth studies were carried out in media supplemented with 3% serum, and cells were counted with a Coulter counter. We found that VIP significantly increased cAMP production of AGS cells in a dose-dependent manner, whereas secretin, glucagon, and peptide histidine methionine (PHM) did not stimulate cAMP production. Exogenous cAMP (8-bromo-cAMP) inhibited AGS cell growth in a dose-dependent manner. VIP acted synergistically with either isobutylmethyl-xanthine or forskolin to inhibit AGS cell proliferation. The increased c-myc expression, which was induced by serum, was inhibited by simultaneous treatment with VIP and isobutylmethyl-xanthine. We have found that AGS cells have specific, functional VIP receptors (activation of which are negatively correlated with cell growth) and that the mechanism by which VIP acts to inhibit cell growth appears to be due, in part, to cAMP-dependent regulation of c-myc proto-oncogene expression.

1-Methyl-3-isobutylxanthine↗

Osteomyelitis of the pelvis due to Fusobacterium nucleatum.

Anaerobic pelvic osteomyelitis occurs rarely in children. A case of Fusobacterium nucleatum osteomyelitis of the right ilium [correction of ileum] in a child without apparent risk factors is described. This case emphasizes the value of diagnostic aspirates. Therapy with a combination of intravenous and oral clindamycin led to successful resolution of the infection.

Child↗

Posttranscriptional regulation of neurotensin in the gut.

Previous studies have suggested an important role for neurotensin as an enterotrophic factor in the adaptive response of the gut. The purpose of this study was to determine the specific tissue distribution of neurotensin messenger RNA (mRNA) and to examine the molecular mechanisms that regulate intestinal neurotensin gene expression and content. In the first experiment, various segments of gut tissue from three Sprague-Dawley rats were harvested, and polyadenylated RNA was extracted for Northern hybridization with a rat neurotensin probe. In the second experiment, 32 Sprague-Dawley rats were fasted for 72 hours and then killed at 0, 3, 12, and 24 hours after refeeding (n = 8 rats/group). Rats fed ad libitum were killed before fasting (control, n = 8). Distal ileal segments (30 cm) were resected for measurement of neurotensin tissue concentration by radioimmunoassay and extraction of poly (A)+ RNA for Northern hybridization with a rat neurotensin complementary DNA probe. Blots were stripped and reprobed for beta-actin as a control for RNA loading. A nuclear run-on transcription assay was performed to determine the relative rate of neurotensin transcription. In the first experiment, neurotensin messenger RNA transcripts of 1.0 and 1.5 Kb sizes were found throughout the small intestine and proximal colon; the greatest abundance was found in the distal small intestine. In the second experiment, neurotensin tissue concentration was significantly reduced with fasting. Refeeding a diet for 24 hours returned neurotensin concentration to control levels. However, neither the amount of neurotensin messenger RNA nor its rate of transcription were altered by fasting and refeeding. These findings suggest that a posttranscriptional mechanism is responsible for regulation of neurotensin synthesis in gut mucosa.

Animals↗

A highly immunogenic tumor transfected with a murine transforming growth factor type beta 1 cDNA escapes immune surveillance.

A highly immunogenic C3H-derived UV-induced tumor was cotransfected with a murine transforming growth factor type beta 1 (TGF-beta 1) cDNA and a neomycin-resistance gene. Stable clones were isolated and used in vitro and in vivo to determine the effects of endogenously produced TGF-beta on cytolytic T-lymphocyte (CTL) responses. Tumor cells producing TGF-beta, though retaining expression for class I major histocompatibility complex molecules and the tumor-specific antigen, did not stimulate primary CTL responses in vitro and were not effective in vivo for directly stimulating primary CTL or in priming for CTL responses. Furthermore, TGF-beta-producing tumors grew progressively in transiently immunosuppressed mice without losing the tumor antigen; thus, TGF-beta produced by tumors may promote escape from immune surveillance.

Animals↗

Expression of and response to growth regulatory peptides by two human pancreatic carcinoma cell lines.

Two human pancreatic adenocarcinoma cell lines (PANC 1 and MIA PACA 2) were examined for expression of growth factors that could potentially play a role either in growth regulation of the tumor cells, or in cells that comprise the stromal elements of tumors. Both cell lines expressed transforming growth factor-alpha (TGF alpha), basic fibroblast growth factor (bFGF), c-sis (PDGF B chain), TGF beta 1, and TGF beta 3 mRNA by Northern blot analysis. Only the PANC 1 cells, however, expressed the TGF beta 2 transcript. TGF beta-like competing activity was found in medium conditioned by either cell line, but TGF alpha-like [epidermal growth factor (EGF)-competing] activity was not detected in the medium from either cell line by radioreceptor assay. TGF alpha and EGF caused concentration-dependent stimulation of soft agar colony growth of the MIA PACA 2 cells, while only TGF alpha caused a significant but less dramatic stimulation of soft agar growth of the PANC 1 cells. Insulin stimulated the anchorage-independent growth of MIA PACA 2 but not PANC 1 cells. Likewise, bFGF also caused a concentration-dependent stimulation of MIA PACA 2 but not PANC 1 growth in soft agar, and PDGF had no effect on the growth of either cell line. TGF beta had no inhibitory or stimulatory effect on soft agar colony growth of either the PANC 1 or the MIA PACA 2 cells, although both cell lines exhibited high affinity, saturable TGF beta binding sites, and TGF beta 1 was capable of autoinduction of TGF beta 1 mRNA expression in PANC 1 cells. The ability to continue to respond to positive growth regulatory factors coupled with the loss of responsiveness to negative growth factors may be important in the pathogenicity of these aggressive tumors.

Adenocarcinoma↗

Additive interactions of calcitonin gene-related peptide and calcitonin on pancreatic exocrine function in conscious dogs.

By convention, establishing a physiologic role for a gut peptide requires demonstration of biologic activity that can be reproduced by exogenous administration of the peptide in amounts that yield plasma concentrations that are not higher than those found after a meal. We have tested the hypothesis that the combined action of two inhibitory peptides may lower the effective doses of each. We further hypothesize that combined peptide responses may be responsible for the action of peptide hormones that have been difficult to demonstrate as physiologically relevant mediators, when examined as independently acting substances. In conscious dogs prepared with chronic pancreatic cannulas, stimulated pancreatic exocrine secretions were depressed in a dose-related manner by intravenous infusions of calcitonin (CT) and calcitonin gene-related peptide (CGRP). Doses of 2.0 nmol/kg/hr of both CT and CGRP yielded maximal inhibition of stimulated secretions of both bicarbonate (greater than 85% inhibition) and protein (greater than 55% inhibition). The lowest effective dose for either CT or CGRP, given alone, was 0.75 nmol/kg/hr, but when infused simultaneously, each at the subthreshold dose of 0.50 nmol/kg/hr, significant inhibition of protein and bicarbonate secretion was achieved. Combined infusions of the submaximal dose of 0.75 nmol/kg/hr resulted in an enhanced inhibitory response. To prove that this effect is not simply combined activation of a common receptor, we tested peptide YY (0.1 to 0.5 nmol/kg/hr) combined with CGRP and obtained similar results. Because a meal simultaneously releases a large number of active peptides, we speculate that such potentiated responses do occur physiologically. Cooperative interaction with other agents may be the primary mode of action for certain gut peptides.

Animals↗

Proglumide inhibits cholecystokinin and meal-stimulated pancreatic secretion and release of pancreatic polypeptide.

Exogenously administered cholecystokinin is a potent stimulant of pancreatic exocrine secretion and pancreatic polypeptide release. Release of cholecystokinin by amino acids and fats is strongly correlated with both pancreatic exocrine secretion and pancreatic polypeptide release. Despite this correlation, direct evidence that cholecystokinin is a physiologic mediator of these actions is not available. We have studied this problem in fasted dogs with chronic pancreatic fistulas by means of a specific cholecystokinin antagonist, proglumide, to inhibit the effect of cholecystokinin. Secretion, neurotensin (with secretin stimulation infusion), or cholecystokinin-octapeptide was infused intravenously, either with saline solution or with proglumide (300 mg/kg/hr). For endogenous release of cholecystokinin, intraduodenal infusions of phenylalanine and tryptophan or of sodium oleate were given with either intravenous saline solution or intravenous proglumide. Pancreatic secretion and release of cholecystokinin and pancreatic polypeptide were measured in plasma. Cholecystokinin-octapeptide stimulated pancreatic secretion of water and protein; both of these were significantly inhibited by proglumide. Intraduodenal amino acids and sodium oleate both caused significant release of cholecystokinin, which was not altered by proglumide; however, proglumide inhibited pancreatic secretion stimulated by intraduodenal amino acids and sodium oleate. Release of pancreatic polypeptide stimulated by amino acid and sodium oleate was also significantly inhibited by proglumide. Since proglumide appears to block actions of cholecystokinin, our results show that cholecystokinin is physiologically important for pancreatic secretion and for release of pancreatic polypeptide.

Amino Acids↗

Regulation of intestinal epithelial cell growth by transforming growth factor type beta.

A nontransformed rat jejunal crypt cell line (IEC-6) expresses transforming growth factor type beta 1 (TGF-beta 1) mRNA, secretes latent 125I-labeled TGF-beta 1 competing activity into culture medium, and binds 125I-labeled TGF-beta 1 to specific, high-affinity (Kd = 3.7 pM) cell surface receptors. IEC-6 cell growth is markedly inhibited by TGF-beta 1 and TGF-beta 2 with half-maximal inhibition occurring between 0.1 and 1.0 ng of TGF-beta 1 per ml. TGF-beta 1-mediated growth inhibition is not associated with the appearance of biochemical markers of enterocyte differentiation such as alkaline phosphatase expression and sucrase activity. TGF-beta 1 (10 ng/ml) increases steady-state levels of its own mRNA expression within 8 hr of treatment of rapidly growing IEC-6 cells. In freshly isolated rat jejunal enterocytes that are sequentially eluted from the crypt villus axis, TGF-beta 1 mRNA expression is most abundant in terminally differentiated villus tip cells and least abundant in the less differentiated, mitotically active crypt cells. We conclude that TGF-beta 1 is an autoregulated growth inhibitor in IEC-6 cells that potentially functions in an autocrine manner. In the rat jejunal epithelium, TGF-beta 1 expression is most prominently localized to the villus tip--i.e., the region of the crypt villus unit that is characterized by the terminally differentiated phenotype. These data suggest that TGF-beta 1 may function in coordination of the rapid cell turnover typical for the intestinal epithelium.

Animals↗

Localization of transforming growth factor alpha and its receptor in gastric mucosal cells. Implications for a regulatory role in acid secretion and mucosal renewal.

Transforming growth factor alpha (TGF alpha) shares with epidermal growth factor (EGF) structural homology (35%), a common cell-surface membrane receptor (TGF alpha/EGF receptor), and a nearly identical spectrum of biological activity, including inhibition of gastric acid secretion. Herein, we report expression of TGF alpha mRNA in normal gastric mucosa of the adult guinea pig, rat, and dog. TGF alpha mRNA was also detected in matched surgically resected gastric mucosa and adjacent gastric carcinoma from 10 patients, and in gastric mucosa adjacent to a benign ulcer from an additional patient. TGF alpha protein was quantitated by radioimmunoassay and was present in tumor and adjacent mucosa. TGF alpha/EGF receptor mRNA was also detected in gastric mucosa from all species studied. Localization of TGF alpha and TGF alpha/EGF receptor mRNA expression was examined in samples of unfractionated guinea pig gastric mucosa and from chief cell-enriched and parietal cell-enriched fractions. All samples exhibited TGF alpha and TGF alpha/EGF receptor expression. The TGF alpha signal was greatest in the parietal cell fraction (5.8-fold increase), but was also enhanced in the chief cell fraction (1.9-fold increase) relative to the unfractionated gastric mucosa. Like TGF alpha expression, TGF alpha/EGF receptor mRNA expression was most intense in the parietal cell-enriched fraction (7.8-fold increase), but was also increased in the chief cell-enriched fraction (2.7-fold increase) relative to the unfractionated guinea pig gastric mucosa. We conclude that TGF alpha and TGF alpha/EGF receptor genes are expressed in normal adult mammalian gastric mucosa. These findings, when interpreted in light of described actions of TGF alpha and EGF, provide evidence that local production of TGF alpha could play an important role in the regulation of acid secretion and mucosal renewal in the stomach.

Adult↗

Operative strategies in the management of mediastinal pancreatic pseudocyst.

Thirty-four cases of mediastinal pancreatic pseudocyst have been previously reported. Among the 32 previous reports with operative or autopsy analysis, communication has been identified in 30. Even when this communication has been quite small between the mediastinal fluid collection and the pancreas, the recommended operative strategy has been enteric drainage directly to this communicating tract. We report the case of a patient with a mediastinal pancreatic pseudocyst in whom the communication between the pancreas and the pseudocyst was not located. The condition was managed by drainage of the mediastinal pseudocyst with decompression of the main pancreatic duct by means of a longitudinal pancreaticojejunostomy in a patient with chronic pancreatitis.

Aged↗

Combined endoscopic and fluoroscopic balloon dilatation of a complex proximal jejunal stricture.

Dilatation of esophageal strictures has been practiced for many years. More recently, balloon dilatation, with endoscopic guidance, has been applied to the stomach and the colon. The small bowel has been less accessible to the endoscope, and, as far as we have been able to determine, balloon dilatation of jejunal strictures has not been reported. We present a patient who was referred to us after curative resection of two abdomino-pelvic malignancies, external beam irradiation to the abdomen and pelvis, and multiple later operations for bowel obstruction and dehiscence of intestinal anastomoses. The bowel obstruction and anastomotic dehiscence occurred during the present hospitalization and resulted finally in the development of a high-output proximal jejunal fistula. The area of stricture, as seen by means of barium contrast, had two separate components with an associated acute angulation. We report the combined use of endoscopic and fluoroscopic manipulation and balloon dilatation of this complex stricture.

Aged↗