Biomedical subjects

R A Falcone

Publications and source records attributed to R A Falcone.

At least 19 recordsLinked to original sources

PubMed2001

cDNA microarray analysis of adapting bowel after intestinal resection.

BACKGROUND/PURPOSE: Studies of the genetic regulation of various physiologic processes have been hampered by methodologies that are limited to the analysis of individual genes. The advent of cDNA microarray technology has permitted the simultaneous screening of numerous genes for alterations in expression. In this study, cDNA microarrays were used to evaluate gene expression changes during the intestinal adaptive response to massive small bowel resection (SBR). METHODS: Male ICR mice (n = 20) underwent either a 50% SBR or sham operation and then were given either orogastric epidermal growth factor (EGF, 50 microg/kg/d) or saline. After 3 days, cDNA microarray analysis was performed on mRNA extracted from the remnant ileum. RESULTS: From over 8,700 different genes, the array identified 27 genes that were altered 2-fold or greater after SBR. Small proline-rich protein 2 (sprr2), the gene with the greatest expression change (4.9-fold), was further upregulated by EGF. This gene has never been characterized in the intestine or described in intestinal adaptation. CONCLUSIONS: cDNA microarray analysis showed enhanced expression of sprr2, a gene not previously known to be involved in the physiology of adaptation after SBR. This technology provides a more rapid and efficient means of dissecting the complex genetic regulation of gut adaptation.

Adaptation, Biological↗

PubMed2000

Epidermal growth factor alters the bax:bcl-w ratio following massive small bowel resection.

BACKGROUND: Following massive small bowel resection (SBR), the expression of bax and bcl-w is associated with increased enterocyte apoptosis. Epidermal growth factor (EGF) has been shown to enhance enterocyte proliferation and retard apoptosis in the adapting bowel. This study examined the effect of EGF on the expression of these bcl-2 family members during adaptation. MATERIALS AND METHODS: Mice (C57Bl/6; n = 38) underwent a 50% SBR or sham operation and then were randomized to receive twice-daily orogastric saline or EGF (50 microg/kg/day). After 3 days, the remnant ileum was removed, apoptotic index (No. apoptotic bodies/crypt) calculated, and expression of mRNA and protein for bax and bcl-w quantified. RESULTS: EGF prevented the expected increase in the apoptotic index after SBR and altered the ratio of bax to bcl-w in favor of cell survival. CONCLUSION: Following massive small bowel resection, EGF retards rates of enterocyte apoptosis and modifies the expression of bcl-2 family members. By decreasing bax and increasing bcl-w expression, the balance between pro- and anti-apoptotic genes is shifted in favor of cell survival. Alteration of bcl-2 family member expression may be an important mechanism by which EGF reduces the increased enterocyte apoptosis that occurs after massive small bowel resection.

Adaptation, Physiological↗

PubMed2000

p21 (WAF1/CIP1) is required for the mitogenic response to intestinal resection.

BACKGROUND: Increased enterocyte proliferation and apoptosis characterize the intestinal adaptive response to massive small bowel resection (SBR). Since p21 (WAF1/CIP1) has been implicated to play a role in cellular differentiation and apoptosis, this study tested the hypothesis that p21 is obligatory for adaptation to occur. MATERIALS AND METHODS: p21-null (n = 36) and wild-type (C57B1/6, n = 19) mice underwent a 50% SBR or sham operation. After 3 days, parameters of adaptation (ileal wet weight, villus/crypt morphology, and ileal protein content), an enterocyte proliferation index (PI), and an apoptotic index (AI) were determined in the residual ileum. In a separate set of experiments, p21-null (n = 11) and control (n = 20) mice underwent the aforementioned operative procedures and the remnant intestine was subjected to a reverse transcription polymerase chain reaction for p27 (KIP1). RESULTS: Both AI and PI increased after SBR in the wild-type mice. In the p21-null mice, SBR increased AI, but did not affect the PI. After SBR, adaptive parameters increased in the wild-type mice, but failed to increase in the p21-null mice. The absence of p21 caused a baseline increase in p27 mRNA, which did not change after SBR. CONCLUSION: p21 appears to be required to increase enterocyte proliferation and to augment the other parameters of intestinal adaptation. In the absence of p21, the proliferative and apoptotic responses to SBR are uncoupled. These results suggest a differential mechanism for the regulation of enterocyte proliferation and apoptosis in the adapting intestine.

Adaptation, Physiological↗

PubMed2000

Transesophageal echocardiographic findings in subcortical and cortical stroke.

Historically, subcortical stroke is believed to be secondary to intracranial small vessel disease. In this study, transesophageal echocardiographic findings such as aortic atherosclerotic disease and other potential cardiac sources of emboli were common in patients with subcortical stroke, supporting a multifactorial etiology for subcortical stroke and a role for transesophageal echocardiography in this patient population.

Aged↗

PubMed2000

Diminished epidermal growth factor levels in infants with necrotizing enterocolitis.

BACKGROUND/PURPOSE: Because epidermal growth factor (EGF) is trophic to the intestinal mucosa, and neonatal necrotizing enterocolitis (NEC) is associated with a disrupted intestinal mucosal barrier, the authors sought to determine whether diminished levels of EGF were present in infants with NEC. METHODS: Saliva, serum, and urine specimens were obtained from infants with NEC during a 3-year period (February 1995 to May 1998). Control patients without NEC were chosen based on similar postnatal age and birthweight. EGF levels were determined by enzyme-linked immunosorbent assay (ELISA). Differences between groups were compared using Mann-Whitney Rank sum test with P less than .05 considered significant. Results are presented as mean values +/-SEM. RESULTS: Twenty-five infants with NEC were compared with 19 control patients. Birth weight (1,616+/-238 g control v. 1,271+/-124 g NEC) and postnatal age (23+/-6 days control v. 22+/-3 days NEC) were similar. Infants with NEC had significantly lower levels of EGF in both saliva (590+/-80 pg/mL control v. 239+/-41 pg/mL NEC; P<.001) and serum (35+/-8 pg/mL control v. 5.6+/-1.9 pg/mL NEC; P<.001). Urinary EGF was also lower in the NEC group, but was not statistically significant. CONCLUSIONS: Premature infants with NEC have significantly diminished levels of salivary and serum EGF. Reduced levels of this growth factor may distinguish infants at risk for NEC and play a pivotal role in the pathogenesis of the perturbed intestinal mucosal barrier that is central to this condition.

Enterocolitis, Necrotizing↗

PubMed2000

Intestinal adaptation occurs independent of transforming growth factor-alpha.

BACKGROUND/PURPOSE: Signal transduction via the epidermal growth factor receptor (EGFR) is critical for intestinal adaptation after massive small bowel resection (SBR). Although it has been assumed that the major ligand for the EGFR during adaptation is EGF, the role for transforming growth factor-alpha (TGF-alpha), another major ligand for the EGFR is unknown. The purpose of this study was to test the hypothesis that TGF-alpha is an important ligand for the EGFR during intestinal adaptation. METHODS: Wild-type mice (C57BI/6) underwent a 50% proximal SBR or sham operation (bowel transection or reanastomosis) and were then assigned randomly to receive either intraperitoneal TGF-alpha or placebo. In a separate experiment, SBR or sham operations were performed in mice lacking TGF-alpha (Waved-1). After 3 days, adaptation was measured in the ileum. RESULTS: Exogenous TGF-alpha enhanced intestinal adaptation in the wild-type mice after SBR as shown by increased ileal wet weight and DNA content. Normal adaptation occurred in the mice lacking TGF-alpha as shown by increased ileal wet weight, protein and DNA content, proliferation, villus height, and crypt depth. CONCLUSIONS: Although exogenous TGF-alpha enhanced adaptation after massive SBR, adaptation was preserved in TGF-alpha-absent mice. These results refute TGF-alpha as an essential ligand for EGFR signaling during intestinal adaptation.

Adaptation, Physiological↗

PubMed2000

Bax is required for increased enterocyte apoptosis after massive small bowel resection.

BACKGROUND: Massive small bowel resection (SBR) increases rates of both enterocyte proliferation and apoptosis. Previous studies have demonstrated increased intestinal expression of proapoptotic bax mRNA and protein, as well as the appearance of an 18-kd bax cleavage product within 12 hours of SBR. This study tested the hypothesis that bax is required for postresection increases in enterocyte apoptosis. METHODS: Male bax-null and C57Bl/6 (control) mice underwent either a 50% proximal SBR or sham operation. After 3 days, the remnant ileum was harvested and weighed. Apoptotic indexes, proliferation indexes, villus heights, and crypt depths were determined. RESULTS: The usual adaptive increases in ileal wet weight, crypt depth, and rate of proliferation occurred in both the control and bax-null mice. Resection significantly increased the rate of apoptosis in the control mice; however, it failed to alter the apoptotic index in the bax-null mice. CONCLUSIONS: Bax is necessary for the increase in apoptosis that occurs after SBR, but its absence has no significant effect on short-term adaptation. These findings suggest that enterocyte proliferation and apoptosis are differentially regulated during intestinal adaptation.

Animals↗

PubMed2000

Salivary epidermal growth factor and intestinal adaptation in male and female mice.

Salivary epidermal growth factor (sEGF) levels are increased in male mice after small bowel resection (SBR) and may be important during intestinal adaptation. Since males have greater sEGF than females, the influence of sex on postresection adaptation was tested. Females had lower sEGF; however, sEGF substantially increased in both sexes after a massive (50%) SBR. Adaptive increases in DNA and protein content, villus height, and crypt depth, as well as crypt cell proliferation rates in the remnant ileum, were not different between males and females. Although significant postresection increases in sEGF were identified, EGF mRNA and protein did not change within the submandibular gland. Glandular kallikrein-13 and ileal EGF receptor expression were greater after SBR in female mice. Intestinal adaptation is equivalent in female and male mice after SBR. Despite lower sEGF, females demonstrated increased expression of a kallikrein responsible for sEGF precursor cleavage as well as amplified ileal EGF receptor expression. These results endorse an important differential response between sexes regarding sEGF mobilization and intestinal receptor availability during adaptation.

Adaptation, Physiological↗

PubMed2000

Cost-effective bariatric surgery in Germany today.

BACKGROUND: The reason for this inquiry was to assess the actual state of Bariatric Surgery in Germany, especially relating to the much discussed economic aspect. METHOD: A questionnaire was sent to those hospitals in Germany in which we knew that obesity surgery was performed, concerning the year 1997. RESULTS: To our regret, the feedback was only 37%, although this must be considered an adequate response for Germany. Nevertheless, some interesting trends are easily seen. CONCLUSION: Bariatric Surgery in Germany could pay for itself by saving the costs associated with conservative therapy and preventing co-morbidities in patients with morbid obesity.

Biliopancreatic Diversion↗

PubMed1999

Apoptosis and the pattern of DNase I expression following massive small bowel resection.

INTRODUCTION: Following massive small bowel resection (SBR), histologic evidence of increased enterocyte apoptosis has been demonstrated in several animal models. Deoxyribonuclease I (DNase I) is requisite for intranuclear cleavage of DNA during apoptosis; we therefore hypothesized that the expression of this gene would be increased following SBR. METHODS: Male ICR mice underwent either 50% proximal SBR or sham surgery (bowel transection/reanastomosis). After 12 h and 1, 3, and 7 days, rates of enterocyte proliferation and apoptosis were recorded as well as DNase I mRNA expression and activity. RESULTS: Adaptation after SBR was confirmed at each time point by increased proliferation. Enterocyte proliferation was increased by 12 h and apoptosis was increased by 24 h and remained elevated through Day 7. When compared with sham-operated mice, SBR resulted in a twofold increase in both DNase I expression and activity at 24 h postoperatively, which returned to baseline by Postoperative Day 3. CONCLUSIONS: DNase I expression and activity are increased early following massive SBR but return to baseline despite persistent increased rates of enterocyte apoptosis and proliferation. This enzyme may be important in the early induction of apoptosis following massive SBR, but not once a new set point has been established in the balance between the rate of enterocyte production and enterocyte loss.

Adaptation, Physiological↗

PubMed1999

Differential expression of ileal Na(+)/H(+) exchanger isoforms after enterectomy.

BACKGROUND: Na(+)/H(+) exchangers (NHE) are transporters involved in the absorption of NaCl along the gastrointestinal tract. The aim of this study was to determine the expression pattern of the intestinal brush border NHE isoforms 2 and 3 following massive small bowel resection (SBR). Additionally, the effect of epidermal growth factor (EGF) and salivarectomy (removal of the primary source of EGF) on the expression pattern was studied. MATERIALS AND METHODS: ICR mice underwent a proximal SBR or sham surgery and then received either orogastric saline or EGF (50 microg/kg/day). In separate experiments mice underwent salivarectomy followed by SBR or sham. Postoperatively the remaining ileum was isolated and levels of NHE-2 and NHE-3 mRNA and protein were resolved. RESULTS: Following SBR, the expression of both mRNA and protein for NHE-3 increased by approximately 2.5-fold. Treatment with EGF enhanced NHE-3 mRNA in sham animals with further elevation following SBR. The expression of NHE-2 mRNA demonstrated minimal change while protein marginally increased (40%) following SBR. EGF did not affect the expression of NHE-2 mRNA. Salivarectomy did not influence NHE-2 protein expression and inhibited the increased NHE-3 protein expression following SBR. CONCLUSIONS: Following SBR, the expression pattern for brush border NHE isoforms is distinctive. Increased expression of NHE-3 secondary to SBR and/or EGF treatment with loss of this increase following salivarectomy implies a common mechanism to enhance enterocyte proliferation and luminal absorption of NaCl and water. These results suggest that NHE-3 is an important ileal exchanger following SBR.

Animals↗

PubMed1999

A prospective comparison of laparoscopic ultrasound vs intraoperative cholangiogram during laparoscopic cholecystectomy.

BACKGROUND: The laparoscopic ultrasound (US) probe provides a new modality for evaluating biliary anatomy during laparoscopic cholecystectomy (LC). METHODS: We performed a laparoscopic US examination in 65 patients without suspected common bile duct (CBD) stones prior to the performance of a laparoscopic cholangiogram (IOC). We then compared the cost, time required, surgeon's assessment of difficulty, and interpretations of findings. RESULTS: There was a significant difference in the cost of US versus the cost of IOC ($362 +/- 12 versus $665 +/- 12; p < 0.05). Surgeons who had performed >10 US (EXP) were compared with those who had performed </=10 (NOV). There were significant differences between the EXP and NOV groups in ease of examination, visualization of biliary anatomy, and accuracy of measurement of the CBD. CONCLUSIONS: The use of laparoscopic US for the accurate evaluation of the CBD and biliary anatomy requires that the surgeon has surpassed the learning curve, which we have defined as having performed >10 US exams.

Adult↗

PubMed1999

The distribution of endogenous epidermal growth factor after small bowel resection suggests increased intestinal utilization during adaptation.

BACKGROUND/PURPOSE: Although exogenous epidermal growth factor (EGF) amplifies adaptation after massive small bowel resection (SBR), the role for endogenous EGF is unclear. The authors sought to determine whether SBR was associated with changes in the levels of EGF in the serum, saliva, or urine and EGF receptor (EGF-R) signaling in the ileum. METHODS: Male ICR mice underwent 50% proximal SBR or sham surgery bowel transection/reanastomosis). After 3 days, levels of EGF were measured by enzyme-linked immunosorbent assay (ELISA) in the serum, saliva, and urine. EGF-R activation was measured in isolated ileal enterocytes by probing an EGF-R immunoprecipitate with an antibody to phosphotyrosine. RESULTS: When compared with sham, SBR resulted in no change in serum, increased salivary (2209+/-266 nmol SBR v 1183+/-119 nmol sham, P<.05) and decreased urinary (417+/-58 nmol SBR v 940+/-143 nmol sham; P<.05) EGF levels. EGF-R activation increased 2.5-fold after SBR. CONCLUSIONS: Increased salivary and reduced urinary EGF linked with enhanced EGF-R activation suggests increased ileal utilization of EGF during adaptation. This observation, along with the known beneficial effects of exogenous EGF, infers a crucial role for endogenous EGF in the pathogenesis of intestinal adaptation after SBR.

Adaptation, Physiological↗

PubMed1999

The effect of epidermal growth factor on differentiation of isolated enterocytes after small bowel resection.

BACKGROUND/PURPOSE: In previous studies using mucosal scrapings or whole-bowel homogenates, epidermal growth factor (EGF) augments adaptation after massive small bowel resection (SBR). The purpose of this study was to determine directly the effect of adaptation and EGF on enterocyte differentiation using an explicit enterocyte cell population. METHODS: Male ICR mice underwent 50% proximal SBR or sham (bowel transection-reanastomosis) and were selected randomly to either orogastric saline or EGF (50 microg/kg/d). After 3 days, enterocytes were isolated from the remnant ileum by mechanical vibration and assayed for DNA and protein content as well as sucrase and alkaline phosphatase (AlkP) activity. RESULTS: Ileal wet weight, enterocyte protein, and DNA content were increased significantly after SBR and boosted even further with EGF. When normalized for protein, SBR caused an increase in AlkP and sucrase activity, and EGF treatment caused AlkP and sucrase activity to return to baseline. CONCLUSIONS: EGF enhances adaptation; however, when normalized for protein, the activity of two enterocyte-specific enzymes was not significantly altered by EGF. This analysis of an explicit enterocyte population supports the notion that the beneficial effects of EGF are more likely caused by increased numbers of enterocytes rather than an increase in the functional activity of each individual cell.

Adaptation, Physiological↗

PubMed1999

The expression and activation of EGF and c-NEU receptors are increased in enterocytes during intestinal adaptation.

BACKGROUND/PURPOSE: After massive small bowel resection (SBR), epidermal growth factor (EGF) and its intestinal receptor (EGF-R) play major roles during adaptation. The expression of a homologous enterocyte receptor termed c-neu (c-neu-R) is capable of forming heterodimers with EGF-R to facilitate cellular signaling. The purpose of this study was to determine the expression and activation of EGF-R and c-neu-R during the adaptive intestinal response to SBR. METHODS: Male ICR mice underwent either SBR or sham surgery. After 1, 3, and 7 days, enterocytes were isolated and protein immunoprecipitated with antibody to either EGF-R or c-neu-R. Receptor protein expression and activation status were determined. RESULTS: When compared with sham operation, the expression and activation status of both EGF-R (six- and twofold, respectively) and c-neu-R (nine- and twofold, respectively) were increased substantially in enterocytes from the adapting ileum after SBR by postoperative day 3. Minimal changes were appreciated for either EGF-R or c-neu-R expression or activation in the remnant bowel after enterocyte removal, liver, or kidney. CONCLUSIONS: Both the expression and activation status of EGF-R and c-neu-R are increased substantially in enterocytes from the adapting ileum by postoperative day 3 after massive SBR. These changes provide a unique mechanism for the enterocyte to enhance cellular signaling in response to EGF during intestinal adaptation.

Adaptation, Physiological↗

PubMed1999

The adaptive intestinal response to massive enterectomy is preserved in c-SRC-deficient mice.

BACKGROUND/PURPOSE: The Src family of protein tyrosine kinases has been implicated in the downstream mitogenic signaling of several ligands including epidermal growth factor (EGF). Because EGF likely plays a role in adaptation after massive small bowel resection (SBR), we tested the hypothesis that c-src is required for this important response. METHODS: A 50% proximal SBR or sham operation (bowel transection or reanastomosis alone) was performed on c-src-deficient (n = 14) or wild-type (C57bl/6) mice (n = 20). The ileum was harvested on postoperative day 3 and adaptive parameters determined as changes in ileal wet weight, protein and DNA content, proliferation index, villus height, and crypt depth. Comparisons were done using analysis of variance (ANOVA), and a Pvalue less than .05 was considered significant. Values are presented as mean +/- SEM. RESULTS: The activity of c-src was increased in the ileum of wild-type mice after SBR but remained unchanged in c-src-deficient mice. Despite this lack of increase, adaptation occurred after SBR in the c-src-deficient mice as demonstrated by increased ileal wet weight, protein and DNA content, proliferation index, villus height, and crypt depth similar to wild-type mice. CONCLUSIONS: The adaptive response of the intestine to massive SBR is preserved despite reduced activity of the c-src protein. The mitogenic signaling that characterizes intestinal adaptation and is associated with receptor activation by EGF or other growth factors probably occurs by mechanisms independent of c-src protein tyrosine kinase.

Adaptation, Physiological↗

PubMed1999

Helicopter transport of patients to tertiary care centers after cardiac arrest.

Air transport is commonly used to transfer survivors of cardiac arrest from rural hospitals to large tertiary-care centers, presumably to improve outcome. To examine this issue, a retrospective review of patients stabilized after a cardiac arrest was conducted; 157 transports were reviewed. The mean age of patients was 37.9 +/- 27.8 yrs, with a male to female ratio of 2.2:1. Survivors were significantly older than nonsurvivors. Thirty-one of 69 patients (45%) with primary cardiac disease were discharged alive from the hospital, 75% without neurological sequelae. Only a minority of patients with noncardiac medical illness (7%), electrical injury (33%), suffocation (15%), near-drowning (15%), and inhalation (0%) were discharged alive from the hospital. Outcomes for cardiac arrest in adult patients older than 65 years (32.3% survival) were similar to those for adult patients younger than 65 years (36.2% survival) (P = .887). These results show that survivors of a primary cardiac event have a favorable outcome when transferred by air to tertiary centers when compared with historical controls that were transported by ground. On the other hand, cardiac arrests from noncardiac medical illness, suffocation, near-drowning, and inhalation have a grim prognosis. Prospective studies should clarify the role of air transport in these patients.

Adolescent↗

PubMed1999

Intestinal overexpression of EGF in transgenic mice enhances adaptation after small bowel resection.

The effect of direct intestinal overexpression of epidermal growth factor (EGF) on postresection adaptation has been investigated by the production of transgenic mouse lines. A murine pro-EGF cDNA construct was produced, and expression of the EGF construct was targeted to the small intestine with the use of the rat intestinal fatty acid-binding protein promoter. An approximately twofold increase in intestinal EGF mRNA and protein was detected in heterozygous mice. No changes in serum EGF levels were noted. Except for a slightly shortened small intestine, no other abnormal phenotype was observed. Intestinal adaptation (increases in body weight, DNA, protein content, villus height, and crypt depth) was markedly enhanced after a 50% proximal small bowel resection in transgenic mice compared with nontransgenic littermates. This transgenic mouse model permits the study of intestinal adaptation and other effects of EGF in the small intestine in a more physiological and directed manner than has been previously possible. These results endorse a direct autocrine/paracrine mechanism for EGF on enterocytes as a means to enhance adaptation.

Adaptation, Physiological↗