Biomedical subjects

Giovanni Latella

Publications and source records attributed to Giovanni Latella.

6 recordsLinked to original sources

PubMed2006

Smad3 knock-out mice as a useful model to study intestinal fibrogenesis.

AIM: To evaluate the possible differences in morphology and immunohistochemical expression of CD3, transforming growth factor beta1 (TGF-beta1), Smad7, alpha-smooth muscle actin (alpha-Sma), and collagen types I-VII of small and large intestine in Smad3 null and wild-type mice. METHODS: Ten null and ten wild-type adult mice were sacrificed at 4 mo of age and the organs (esophagus, small and large bowel, ureters) were collected for histology (hematoxylin and eosin, Masson thrichrome, silver staining), morphometry and immunohistochemistry analysis. TGF-beta1 levels of intestinal tissue homogenates were assessed by ELISA. RESULTS: No macroscopic intestinal lesions were detected both in null and wild-type mice. Histological and morphometric evaluation revealed a significant reduction in muscle layer thickness of small and large intestine in null mice as compared to wild-type mice. Immunohistochemistry evaluation showed a significant increase of CD3+ T cell, TGF-beta1 and Smad7 staining in the small and large intestine mucosa of Smad3 null mice as compared to wild-type mice. Alpha-Sma and collagen I-VII staining of small and large intestine did not differ between the two groups of mice. TGF-beta1 levels of colonic tissue homogenates were significantly higher in null mice than in wild-type mice. In preliminary experiments a significant reduction of TNBS-induced intestinal fibrosis was observed in null mice as compared to wild-type mice. CONCLUSION: Smad3 null mice are a useful model to investigate the in vivo role of the TGF-beta/Smad signalling pathway in intestinal inflammation and fibrosis.

Actins↗

PubMed2005

Role of nitric oxide in the impairment of circular muscle contractility of distended, uninflamed mid-colon in TNBS-induced acute distal colitis in rats.

AIM: To evaluate the role of nitric oxide (NO) in the motor disorders of the dilated uninflamed mid-colon (DUMC) from trinitrobenzene sulfonic acid (TNBS)-induced acute distal colitis in rats. METHODS: Colitis was induced in male Sprague-Dawley rats by a single intracolonic administration of TNBS. Control rats received an enema of 0.9% saline. The rats were killed 48 h after TNBS or saline administration. Macroscopic and histologic lesions of the colon were evaluated. Myeloperoxidase (MPO) and nitric oxide synthase (NOS) activity were measured on the colonic tissue. In TNBS rats, we evaluated spontaneous and evoked contractile activity in circular muscle strips derived from DUMC in comparison to the same colonic segment of control rats, both in the presence and in the absence of a non-selective NOS isoforms inhibitor N-nitro-L-arginine (L-NNA). Pharmacological characterization of electric field stimulation (EFS)-evoked contractile responses was also performed. RESULTS: In TNBS rats, the distal colon showed severe histological lesions and a high MPO activity, while the DUMC exhibited normal histology and MPO activity. Constitutive NOS activity was similar in TNBS and control rats, whereas inducible NOS activity was significantly increased only in the injured distal colon of TNBS rats. Isometrically recorded mechanical activity of circular muscle strips from DUMC of TNBS rats showed a marked reduction of the force and frequency of spontaneous contractions compared to controls, as well as of the contractile responses to a contracting stimulus. In the presence of L-NNA, the contractile activity and responses displayed a significantly greater enhancement compared to controls. The pharmacological characterization of EFS contractile responses showed that a cooperative-like interaction between cholinergic muscarinic and tachykinergic neurokinin 1 and 2 receptors mediated transmission in DUMC of TNBS rats vs a simple additive interaction in controls. CONCLUSION: The results of this study show that, during TNBS-induced acute distal colitis, circular muscle intrinsic contractile mechanisms and possible enteric neural excitatory activity are inhibited in the distended uninflamed mid-colon. Suppression of NO synthesis markedly improves spontaneous and evokes muscle contractions, in spite of any evident change in local NO activity.

Animals↗

PubMed2004

Prevention of fibrosis in experimental colitis by captopril: the role of tgf-beta1.

BACKGROUND & AIMS: There is a body of evidence to suggest that the local activation of angiotensin II (ANG II) plays a pivotal role in fibrogenic response involving the kidney, heart, lung, pancreas and liver. In such conditions, fibrosis is mediated, at least partially, through ANG II induction of the cytokine transforming growth factor-beta1 (TGF-beta1). Both ANG II and TGF-beta1 also seem to be involved in intestinal fibrosis and stenosis, particularly in Crohn's disease. The aim of the present study was, firstly, to determine the effects of the angiotensin-converting enzyme inhibitor, captopril, on colonic fibrosis in experimental colitis in rats and, secondly, to check the role of TGF-beta1 on these effects. METHODS: Colitis was induced in rats by intracolonic administration of TNBS. Colonic fibrosis was assessed 21 days later by macroscopic and microscopic evaluation. Levels of collagen alpha1 gene expression, hydroxyproline, angiotensin II and TGF-beta1 proteins, and TGF-beta1 mRNA were measured on the colonic tissue. RESULTS: In chronic colitis, captopril significantly reduced the score of macroscopic and histologic lesions, as well as the colonic tissue levels of collagen alpha1, hydroxyproline, ANG II and TGF-beta1 proteins, and TGF-beta1 mRNA. CONCLUSIONS: These data demonstrate for the first time that the prophylactic administration of captopril is effective in preventing colonic fibrosis in TNBS-induced colitis. The antifibrotic action of captopril could be due to the blockade of TGFbeta-1 overexpression, and/or to a direct down-regulation of TGFbeta-1 transcript.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2002

Rifaximin improves symptoms of acquired uncomplicated diverticular disease of the colon.

BACKGROUND AND AIMS: We examined the efficacy of cyclic long-term administration of rifaximin, a broad spectrum, poorly absorbable antibiotic, in obtaining symptom relief in a large series of patients with uncomplicated diverticular disease, and compared the incidence of episodes of diverticulitis in the group treated with rifaximin to that in a group receiving fiber supplementation only. PATIENTS AND METHODS: In a multicenter, prospective, open trial, 968 outpatients with uncomplicated symptomatic diverticular disease were randomized to either fiber supplementation with 4 g/day glucomannan plus 400 mg rifaximin twice daily for 7 days every month ( n=558) or 4 g/day glucomannan alone ( n=346). Clinical evaluation was performed on admission and at 4-month intervals for 12 months. RESULTS: After 12 months the group treated with glucomannan + rifaximin showed fewer symptoms (abdominal pain/discomfort, bloating, tenesmus, diarrhea, abdominal tenderness) and a lower global symptomatic score. Overall 56.5% of the patients treated with glucomannan + rifaximin and 29.2% of those treated with glucomannan alone were asymptomatic at 12 months ( P<0.001). The rate of complications (diverticulitis and rectal bleeding) was 1.34% in the rifaximin + glucomannan group and 3.22% in the glucomannan alone group ( P<0.05). CONCLUSION: Cyclic administration of rifaximin is effective in obtaining symptom relief in uncomplicated diverticular disease of the colon. The incidence of episodes of diverticulitis in the group treated with rifaximin was lower than that in the group treated with glucomannan alone.

Adult↗

PubMed2002

Increased proliferation and apoptosis of colonic epithelial cells in dextran sulfate sodium-induced colitis in rats.

We have evaluated morphologic alterations and epithelial cell apoptosis and proliferation of colonic mucosa in the acute and chronic phases of DSS-induced colitis. Colitis was induced in Sprague-Dawley rats by 7 days of 4% DSS oral administration followed by 7 days of tap water for one, two, and three cycles. Control rats receved tap water only. Morphological changes in colonic mucosa were evaluated and scored by light and scanning electron microscopy. Apoptosis was studied by TUNEL assay and cell proliferation by Ki-67 immunoreaction. The expression of both proapoptotic (Fas, FasL, Bax, p53) and antiapoptotic (Bc12) cellular proteins was determined by immunohistochemistry. Morphologic assessment showed the most severe colonic epithelial lesions and inflammation in the distal colon with a trend to increasing severity from the first to the third DSS cycle. In DSS rats, the epithelial apoptotic index increased 20-fold after the first cycle and 120-fold after the second and third cycles compared with the controls; in the same way, the expression index of proapoptotic proteins (Fas, FasL, Bax, p53) dramatically increased. The proliferative index increased about 40 to 60-fold compared to controls, with no difference among the three DSS cycles. In conclusion, DSS-induced colitis in rats, which has many structural and ultrastructural features similar to those seen in human ulcerative colitis, is a suitable model for studying increased epithelial apoptosis and proliferation. Further studies employing this model will permitt two hypotheses to be tested. (1) Increased apoptosis may lead to a breakdown of the epithelial barrier function and facilitate the mucosal invasion of intraluminal microorganisms and/or antigens. (2) Abnormal and persistent epithelial hyperproliferation could be causally related to the development of colorectal cancers in the setting of chronic colonic inflammation.

Animals↗

PubMed2002

GI distension in severe ulcerative colitis.

OBJECTIVES: In previous retrospective studies in patients with severe ulcerative colitis (UC), small bowel distension was found to characterize a subgroup of patients at higher risk for both toxic megacolon (TMC) and multiple organ dysfunction syndrome (MODS). In this study we prospectively evaluated the prevalence of GI distension and its relationship to clinical outcome in patients with severe UC. METHODS: Of 109 consecutive inpatients with acute UC (admitted to the GI Unit of the University of Rome during the period 1995-2000), 45 had severe colitis. Routine blood tests and acid-base balance and plain abdominal film evaluations were performed upon admission and repeated every 1-3 days. The gas content of the stomach and small and large intestines was evaluated on plain abdominal films. All patients were submitted to the standard Oxford intensive medical regimen; clinical improvement, occurrence of major complications, need for surgery, and mortality were evaluated. Statistical analysis was carried out using Student's t, chi2, Fisher's exact, Mann-Whitney, and Wilcoxon rank sum tests, when appropriate. RESULTS: Of 45 patients with severe UC, 24 (53%) had GI distension. Three of these 24 patients had TMC on admission (all underwent surgery and survived), 21 showed increased GI gas content (four developed TMC 1-4 days after the detection of GI distension and were operated on, two developed MODS and died, and eight did not improve but were submitted to surgery and survived). None of the 21 patients with normal GI gas content had complications; all survived (five did not improve and required surgery). CONCLUSIONS: In severe UC, persistent GI distension characterized a subgroup of patients with poor response to medical therapy and at higher risk for TMC and of need for surgery. The development of MODS was the most important predicting factor for fatal outcome.

Adult↗