Biomedical subjects

S Zucoloto

Publications and source records attributed to S Zucoloto.

At least 19 recordsLinked to original sources

PubMed2001

Laser enhancement in hepatic regeneration for partially hepatectomized rats.

BACKGROUND AND OBJECTIVE: The bio-stimulation effect of laser has been observed in many areas of Medicine. However, there are a few works which investigate its use for liver regeneration. Most of their results were inconclusive due to the use of high power lasers. This work was carried out to investigate the bio-stimulation effect of laser in liver regeneration using low power lasers. STUDY DESIGN/MATERIALS AND METHODS: We used Wistar male rats, which were irradiated with laser light (wavelength 590 nm and intensity of 50 mW/cm(2)) for 5 minutes after 70% hepatectomy. The respiratory mitochondrial activity, the serum level of aminotransferase and the PCNA were measured. RESULTS: Our results show a dramatic increase in the mitochondrial activity for the laser treated group at 24 hours after the hepatectomy. CONCLUSIONS: We conclude that the laser promotes a bio-stimulation effect on the early stages of liver regeneration without any detectable damage of the cells.

Animals↗

PubMed2001

Angiotensin-converting enzyme inhibition by lisinopril enhances liver regeneration in rats.

Bradykinin has been reported to act as a growth factor for fibroblasts, mesangial cells and keratinocytes. Recently, we reported that bradykinin augments liver regeneration after partial hepatectomy in rats. Angiotensin-converting enzyme (ACE) is also a powerful bradykinin-degrading enzyme. We have investigated the effect of ACE inhibition by lisinopril on liver regeneration after partial hepatectomy. Adult male Wistar rats underwent 70% partial hepatectomy (PH). The animals received lisinopril at a dose of 1 mg kg body weight(-1) day(-1), or saline solution, intraperitoneally, for 5 days before hepatectomy, and daily after surgery. Four to six animals from the lisinopril and saline groups were sacrificed at 12, 24, 36, 48, 72, and 120 h after PH. Liver regeneration was evaluated by immunohistochemical staining for proliferating cell nuclear antigen using the PC-10 monoclonal antibody. The value for the lisinopril-treated group was three-fold above the corresponding control at 12 h after PH (P<0.001), remaining elevated at approximately two-fold above control values at 24, 36, 48 (P<0.001), and at 72 h (P<0.01) after PH, but values did not reach statistical difference at 120 h after PH. Plasma ACE activity measured by radioenzymatic assay was significantly higher in the saline group than in the lisinopril-treated group (P<0.001), with 81% ACE inhibition. The present study shows that plasma ACE inhibition enhances liver regeneration after PH in rats. Since it was reported that bradykinin also augments liver regeneration after PH, this may explain the liver growth stimulating effect of ACE inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

Immunolocalisation of myosin-V in the enteric nervous system of the rat.

We show here the localisation of myosin-V in whole mount preparations of the mucous-submucous and the muscular layers of rat small intestine by using an affinity purified antibody specific to the tail domain of myosin-V. Myosin-V immunostaining was intense in the submucous and myenteric nervous plexuses, allowing the visualisation of neuronal cell bodies and fibres. Western blots of total muscle layers homogenates detected with the same antibody revealed a single band of the expected size for myosin-V. Understanding the cellular localisation and function of this class of myosin is an important challenge and the accessibility and simplicity of the enteric nervous system as compared to the central nervous system, makes the digestive tract an attractive model for studying possible functional roles of myosin-V in neurotransmission and neuroplasticity.

Animals↗

PubMed2000

Effect of myenteric denervation on intestinal epithelium proliferation and migration of suckling and weanling rats.

The effects of myenteric denervation on the cell kinetics of the intestinal epithelium of suckling and weanling rats were investigated. The myenteric plexus of an ileal segment was partially ablated by serosal application of benzalkonium chloride (BAC) in three groups of rats: those that underwent surgery at 13 days and were killed 15 (13/28-day-old) or 23 (13/36-day-old) days after treatment, and those that were operated at 21 days (21/36-day-old) and were killed 15 days after treatment. The extent of denervation was assessed in whole-mount preparations. The cell bodies of myenteric neurones were stained by NADH-diaphorase histochemical technique. Cell proliferation was estimated by the mitotic index (MI) and morphometric analysis of villus and crypt lengths using an image analysis system. Thickness of the muscle layers was also assessed by morphometry. Cell migration on the villi was estimated by the position of the leading labelled cell 24 h after tritiated thymidine injection. The number of neurones was reduced by around 80% in rats operated at 13 days, and reduced by 98% in those operated at 21 days. The thickness of the muscle layers was increased in all groups of treated animals. MI was significantly higher 15 days after BAC-treatment in the 13/28 group. Morphological changes in the intestinal mucosa were observed 15 days after BAC-treatment, when there was an increase in villus height (13/28 group) and crypt depth (13/28 and 21/36 groups). Cell migration rate was accelerated in the 21/36 group. No differences where found in the 13/36 group. These results show the strong effect of myenteric ablation on cell proliferation and migration in the ileal epithelium in the first 15 days of treatment in suckling and in weanling rats, and the subsequent recovery of intestinal mucosa homeostasis later on.

Animals↗

PubMed2000

Endocrine cells in the denervated intestine.

This study deals with the effects of myenteric denervation of the proximal jejunum on endocrine cell population of the crypt-villus unit, 5 months after treatment with benzalkonium chloride (BAC). Male Wistar albino rats weighing on average 100 g were allocated to two groups: the BAC group - the proximal jejunal serosa was treated with 2 mM BAC for 30 min, and the control group - treated with saline solution (0,9% NaCl). There was a significant reduction in neurone number in the jejunal myenteric plexus of the BAC group and the endocrine cell population (serotoninergic and argyrophilic cells) was significantly increased in this intestine segment. In conclusion, the present findings provide further evidence that the myenteric denervation induced by BAC may lead to the development of a local imbalance of the neurotransmitters, with a consequent induction of enteroendocrine cell (argyrophilic and serotoninergic cells) hyperplasia in the crypt and villus.

Animals↗

PubMed2000

Porphyria cutanea tarda in Brazilian patients: association with hemochromatosis C282Y mutation and hepatitis C virus infection.

OBJECTIVE: Porphyria cutanea tarda (PCT) is commonly associated with iron overload and hepatitis C virus (HCV) infection. Association between hemochromatosis C282Y or H63D mutations and PCT has been observed, although not uniformly, and iron overload is also commonly found in chronic HCV hepatitis. The aim of the present study was to investigate the frequency of C282Y and H63D mutations and HCV infection in Brazilian patients with PCT and their relationship with iron overload. METHODS: Twenty-three patients (19 men) aged 39.6 +/- 11.1 yr were studied. All had dermatological lesions of PCT and high levels of urinary uroporphyrin. HCV infection and iron overload were investigated. DNA samples were analyzed for the presence of HFE mutations. RESULTS: The frequency of C282Y was significantly higher in PCT patients than in 278 healthy individuals (17.4% vs 4%, odds ratio = 5.1, 95% confidence interval 1.5-17.6, p = 0.02), whereas no difference was observed regarding the H63D mutation (30.4% vs 31%, odds ratio = 1, 95% confidence interval 0.4-2.4, p = 1). Biochemical tests in PCT patients showed iron overload with transferrin saturation = 47.3 +/- 20.7% and ferritin = 566.8 +/- 425 ng/ml. Fifteen of 23 (65.2%) patients had HCV infection and alcohol ingestion was observed in 17 of 23 (73.9%). CONCLUSIONS: PCT patients exhibited evidence of iron overload, a high frequency of HCV, and an association with C282Y mutation. These data further support the notion that both acquired and inherited factors contribute to the occurrence of PCT, and indicate that screening for C282Y may be justified in PCT patients.

Adult↗

PubMed2000

Are haemochromatosis mutations related to the severity of liver disease in hepatitis C virus infection?

It has been proposed that iron overload may adversely affect liver disease outcome. The recent identification of 2 mutations in the HFE gene related to hereditary haemochromatosis (Cys282Tyr and His63Asp) provided an opportunity to test whether they are associated with hepatic iron accumulation and the activity and severity of liver disease in hepatitis C virus (HCV) infection. We investigated the prevalence of HFE mutations in 135 male patients with chronic HCV hepatitis, and correlated genotype distribution with different parameters of iron status and the activity and severity of liver disease. Of these 135 patients, 6 (4.4%) carried Cys282Tyr and 32 (23.7%) carried His63Asp, frequencies which were similar to those observed in healthy controls. Serum iron levels and transferrin saturation (but not ferritin levels or liver iron content) were significantly higher in carriers than in non-carriers of HFE mutations. No difference was observed in serum ALT, AST and GGT levels between carriers and non-carriers. Finally, scores for necroinflammatory activity and fibrosis in the liver were significantly higher in HFE carriers than in non-carriers. Patients with chronic HCV infection carrying HFE mutations tend to present more evident body iron accumulation and a higher degree of necroinflammatory activity and fibrosis in the liver. HFE gene mutations might be an additional factor to be considered among those implicated in the determination of a worse prognosis of the liver disease in chronic HCV infection.

Adolescent↗

PubMed1999

Nitric oxide is involved in the lesions of the peripheral autonomic neurons observed in the acute phase of experimental Trypanosoma cruzi infection.

Our aim was to investigate the possible involvement of nitric oxide (NO) in peripheral denervation during the acute phase of murine experimental Trypanosoma cruzi infection. Wistar male rats were infected with the Y strain of T. cruzi. One group of animals was also treated with the NO synthase inhibitor N-nitro-l-arginine. A group of uninfected animals was the control. At the 18th day of infection the animals were sacrificed. Quantification of neurons in the colon and heart and tissue parasitism in the heart was performed. Serum concentration of nitrate was measured and a histochemical technique for assessing NADPH-diaphorase activity in the colon was also performed. The infected animals presented a statistically significant decrease in the number of peripheral neurons in the colon and heart and a 2-fold increase in serum NO(3) concentration compared with controls. The animals treated with N-nitro-l-arginine showed almost an absence of NO(3) concentration in the serum and did not show loss of neurons compared with controls. These treated animals displayed a 15-fold increase in tissue parasitism compared with nontreated infected animals. The NADPH-diaphorase activity was much more intense in the muscle layers of the colon of the infected animals than in those of the controls. Taken together, these data suggest that NO is involved in the peripheral denervation observed in the acute phase of experimental T. cruzi infection.

Acute Disease↗

PubMed1999

Intrinsic myenteric denervation: a new model to increase the intestinal absorptive surface in short-bowel syndrome.

INTRODUCTION: Short-bowel syndrome (SBS) is caused by resection of massive portions of the small intestine and is characterized by symptoms related to malabsorption, of which severe weight loss is the most apparent. Surgical treatments for SBS are not yet satisfactory. In rats, the myenteric denervation by benzalkonium chloride (BAC) leads to development of megaileum with visceral dilatation and mucosal hyperplasia and increases the intestinal transit time. Such operation in the remaining intestinal segment after massive small bowel resection could increase the duration of contact between luminal nutrients and ileal mucosal epithelium, and furthermore, it could increase the superficial area of the mucosa. Thus, our aim in this study was to evaluate the epithelial morphology and body weight changes of animals after intrinsic ileal denervation associated with extensive small intestine resection. MATERIAL AND METHODS: Wistar rats were submitted to resection of 80% of small intestinal length (Group R). Another group (B) of animals also received topical serosal application of BAC 0.3%. Control animals were submitted to simulated surgery (Group C). Animals were weighed weekly and sacrificed after 90 days. Intestinal walls were collected for histological procedure and morphometry. RESULTS: At the end of the experimental period all groups showed weight increase, which was reduced in the R group (P < 0.01). Interestingly, the denervated Group B showed a marked increase in weight, similar to the control animals. Morphometric analysis of the mucosal layer area showed a major increase in mucosal surface area, mainly in Group B. CONCLUSIONS: Our results showed that the ileal intrinsic denervation associated with massive intestinal resection induced an increase in the superficial absorptive area and was able to improve the postsurgical conditions for the animals, with accentuated weight increase. This procedure may be a useful model for further studies related to the role of the enteric nervous system on intestinal adaptations after extensive resections and may provide a new approach for the surgical treatment of short-bowel syndrome.

Animals↗

PubMed1999

Abnormal uroporphyrin levels in chronic hepatitis C virus infection.

A strong association between hepatitis C virus (HCV) infection and porphyria cutanea tarda (PCT) has been observed, but the implications of the viral infection in the metabolism of porphyrins in patients without clinical manifestations of PCT are not known. The levels of porphyrin in plasma and uroporphyrin (URO) and coproporphyrin (COPRO) in 24-hour urine were measured in 156 patients with chronic HCV infection showing no clinical evidence of PCT. Levels of URO higher than the upper limit were observed in 35 of 156 patients (22.4%). The range and the mean values +/- standard deviation were 26-1,196 microg/24 hours and 82 +/- 204 microg/24 hours. Increased levels of COPRO and plasma porphyrin were observed in 12 of 156 patients (7.7%) and 2 of 156 patients (1.3%) respectively. There were no differences between patients with increased URO levels and patients with normal URO levels in terms of gender, age, risk factors for HCV infection, alcohol abuse, or hepatitis B viral infection. Transferrin saturation (p = 0.040), gamma glutamyl transpeptidase (p < 0.0001), aspartate aminotransferase (p = 0.006), and alanine aminotransferase (p = 0.040) were significantly higher in patients with abnormal URO than in patients with normal URO. The frequency of cirrhosis was higher, but not significantly different, in patients with increased URO (16.7%) compared with patients with normal URO (3.8%). The authors demonstrated that even without a clinical manifestation of PCT it is possible to detect abnormalities in the metabolism of porphyrins in patients with chronic HCV infection. The implications of these findings deserve additional investigation.

Adolescent↗

PubMed1998

Effect of a necrogenic dose of diethylnitrosamine on vitamin E-deficient and vitamin E-supplemented rats.

In order to evaluate the effects of a necrogenic dose of diethylnitrosamine (DEN) on vitamin E-deficient and vitamin E-supplemented rats, a single dose of the drug (200 mg/kg body weight) was injected intraperitoneally at the end of 10 weeks of treatment with the diets. The hepatic necrosis and lipoperoxidation provoked by DEN were evaluated 24, 48, 72 and 120 hours after the injection and were found to be more intense in the deficient group (thiobarbituric acid reactive substances (TBARS): 5.20 +/- 1.48 nmol/mg protein; necrosis volume: 68.99 +/- 8.36%; P < 0.05) during the second period. Also, in the same group and during the same period, mean plasma and hepatic vitamin E concentrations and mean liver glutathione concentration were the lowest detected, suggesting the occurrence of antioxidant consumption due to the toxic action of DEN. In contrast to vitamin E deficiency, which permitted the drug to exert stronger toxic effects, 20-fold supplementation with vitamin E did not provide additional protection against the lipoperoxidation and necrosis provoked by DEN (P < 0.05). The results suggest that other mechanisms in addition to lipoperoxidation provoked by free radicals originating from the metabolism of nitrosamines by the cytochrome P-450-dependent enzymatic system may be involved in the hepatotoxic action of these substances.

Animals↗

PubMed1998

Plasma-kallikrein clearance during liver regeneration after partial hepatectomy in the rat.

AIMS/BACKGROUND: The liver clears circulating plasma-kallikrein through a receptor-mediated endocytosis process: an initial fast phase is followed by a slow exponential phase. METHODS: To determine whether the clearance rate of plasma-kallikrein is affected during liver regeneration, we perfused isolated rat livers with rat plasma-kallikrein (rPK) at 0, 1, 2, 3 and 7 days after partial hepatectomy or sham operation. RESULTS: Liver regeneration was followed by the expression of the proliferating-cell nuclear antigen (PCNA) labeling index. The serum concentration of alpha2-macroglobulin, an acute phase protein in rats, was measured. At day 1, the fast phase of rPK clearance rate increased in hepatectomized rats when compared with day 0 (4.9+/-0.4 and 3.7+/-0.4 mU/g liver min, p<0.05). However, at day 2, the rPK fast phase clearance rate dropped significantly (2.6+/-0.2, p<0.05), when compared with day 1. No difference was found among the sham groups at different days of hepatectomy. These changes seem to be independent of the acute phase reaction. The regenerative liver weight increased continuously during the observation period. PCNA expression increased significantly after hepatectomy, with maximal PCNA-labeling indices at days 1 and 2, declining thereafter. CONCLUSION: The rPK fast phase clearance rate changes during liver regeneration, with a zenith occurring when PCNA labeling index is maximal (day 1) and a nadir occurring at the mitotic phase (day 2).

Animals↗

PubMed1997

Megaesophagus in rats.

The objective of this study was to determine whether myenteric denervation of the abdominal esophagus using benzalkonium chloride (BAC) leads to esophageal achalasia with changes of the muscle propria and epithelial cell proliferation. The treatment led to megaesophagus 3 months after BAC application. Denervation of the esophagus induced muscle hypertrophy and increased epithelial cell proliferation. The imbalance of the neurotransmitters may play a role in these morphokinetic changes.

Animals↗

PubMed1997

The relationship between myenteric neuronal denervation, smooth muscle thickening and epithelial cell proliferation in the rat colon.

The effects of myenteric neuronal denervation on smooth muscle thickening and epithelial cell proliferation were studied in the descending colon of rats treated by serosal application of 2 mM benzalkonium chloride (BAC) for 30 min. Control animals were treated with saline (0.9% NaCl). The animals were divided into six groups of 13 animals each and killed 10, 45 and 120 days after BAC treatment. A significant reduction in neuron number was observed in the myenteric plexus of animals treated with BAC, as well as smooth muscle thickening and an increase in crypt cell population, crypt cell production per crypt and a decrease in cell cycle time. These findings permit us to conclude that a relationship may exist between the increase of epithelial cell proliferation, smooth muscle thickening and myenteric neuron denervation in the descending colon caused by BAC, the latter probably playing an important role in the integration of the other two.

Animals↗

PubMed1997

Disaccharidase levels in normal epithelium of the small intestine of rats with iron-deficiency anemia.

Iron-deficiency anemia is the nutritional deficiency most frequently occurring throughout the world, which manifests as a complex systemic disease involving all cells, affecting enzyme activities and modifying protein synthesis. In view of these considerations, the objective of the present study was to determine the effects of iron-deficiency anemia on disaccharidases and on the epithelial morphokinetics of the jejunal mucosa. Newly weaned male Wistar rats were divided into 4 groups of 10 animals each: C6w received a standard ration containing 36 mg elemental iron per kg ration for 6 weeks; E6w received an iron-poor ration (5-8 mg/kg ration) for 6 weeks; C10w received an iron-rich ration (36 mg/kg ration) for 10 weeks; E10w received an iron-poor ration for 6 weeks and then an iron-rich ration (36 mg/kg) for an additional 4 weeks. Jejunal fragments were used to measure disaccharidase content and to study cell proliferation. The following results were obtained: 1) a significant reduction (P < 0.001) of animal weight, hemoglobin (Hb), serum iron and total iron-binding capacity (TIBC) in group E6w as compared to C6w; reversal of the alterations in Hb, serum iron and TIBC with iron repletion (E10w = C10w); animal weights continued to be significantly different in groups E10w and C10w. 2) Sucrase and maltase levels were unchanged; total and specific lactase levels were significantly lower in group E6w and this reduction was reversed by iron repletion (E10w = C10w). 3) The cell proliferation parameters did not differ between groups. On the basis of these results, we conclude that lactase production was influenced by iron deficiency and that this fact was not related to changes in cell population and proliferation in the intestinal mucosa.

Anemia, Iron-Deficiency↗

PubMed1996

The relationship between megacolon and carcinoma of the colon: an experimental approach.

'Carcinoma of the colon does not occur in cases of megacolon' is an axiom held by Brazilian physicians working in endemic areas for Chagas' disease. The objective of the present study was to test this axiom experimentally by submitting rats with experimental megacolon to a carcinogen which causes carcinoma of the colon. Eighty young male Wistar rats received serosal application of either saline (0.9% NaCl) or 2 mM benzalkonium chloride (BAC) to the distal colon. Ten months later randomly chosen saline and BAC rats were injected weekly with dimethylhydrazine (DMH) for 20 weeks. Non-DMH-treated rats from both original groups were maintained, for a total of four experimental groups. Three months after the injections all surviving rats were killed. At autopsy the presence of absence of carcinomas along the colon was recorded. The induction of megacolon was evaluated by morphometry of the wall from the distal colon and myenteric denervation was assessed by neuron counts. An increase of at least 2-fold in distal colon wall thickness confirmed the induction of megacolon in BAC-treated rats. Neuronal counts from BAC and control rats not treated with DMH showed an average denervation of 63%. The number of distal colon carcinomas in BAC+DMH-treated rats was significantly lower than that in DMH-treated rats. These findings appear to contradict the traditional concept of carcinogenesis of the colon. The clinical axiom was reproduced experimentally.

1,2-Dimethylhydrazine↗

PubMed1996

Effect of chronic ethanol consumption on the activities of residual small bowel brush-border enzymes after proximal jejunum resection in the rat.

Ethanol consumption has a toxic effect on the epithelium of the small bowel, but enterocyte maturity is very difficult to measure under these circumstances. However, when ethanol intake is combined with enterectomy, enterocyte immaturity is greater, permitting an easier separation of these two effects. In a group of rats (13 male Wistar rats weighing approximately 220 g) fed a liquid diet containing 35% ethanol for 4 weeks after resection of the proximal jejunum, the residual small intestine brush border maltase, sucrase, and lactase activities were similar to those of a pair-fed control group (13 animals). However, alkaline phosphatase activity was decreased in the mucosa and in the enterocyte brush border, probably because of the lower activity of this enzyme in the jejunum-ileum remnant of the alcoholic group.

Alcoholism↗

PubMed1996

Reduction of epidermal cell proliferation in skin lesions in lepromatous leprosy is greater than in indeterminate and tuberculoid leprosy lesions.

We have compared epidermal cell proliferation in skin biopsies from areas with lesions to contralateral areas without lesions in patients with indeterminate, tuberculoid and lepromatous leprosy. Cell proliferation was determined as the percentage of labeled cells in the basal and suprabasal epidermal layers, using autoradiographic preparations of skin biopsies taken 1 hr after a 3H-thymidine intradermal injection. We have found a significant reduction in epidermal cell proliferation in areas with lesions in the three groups of patients. The greatest reduction occurred in lepromatous patients. In lesions of patients with indeterminate or tuberculoid leprosy, the reduction was the same, and in both groups it was smaller than in lepromatous patients. In the areas without lesions, the index of labeled cells was similar to that of "normal" skin of nonleprosy patients. In the contralateral unaffected areas from leprosy patients and in "normal" skin from nonleprosy patients, as well as in affected areas from patients with indeterminate leprosy, epidermal cell labeling was greater in the suprabasal layer than in the basal layer. In lesions of lepromatous patients, cell labeling was greater in the basal layer than in the suprabasal layer. Our findings suggest that the reduction of epidermal cell proliferation in leprosy patients is restricted to the cell-mediated immune response, more intense in lepromatous leprosy. It does not seem to be related to denervation, which is greater in tuberculoid leprosy.

Adult↗