Lymphangiogenesis occurs in upper tract urothelial carcinoma and correlates with lymphatic tumour dissemination and poor prognosis

OBJECTIVE

To describe the lymphatic vessel density and to determine the functional and prognostic significance of tumoral lymphatic vessels in upper tract urothelial carcinoma (UTUC).

PATIENTS AND METHODS

The study included 65 patients who had a radical nephroureterectomy (RNU) for UTUC between 1997 and 2004. All pathological slides were re-evaluated by one reference pathologist and clinical data were reviewed. Lymphatic endothelial cells (LECs) were stained immunohistochemically using D2-40. The lymphatic vessel density (LVD) was described in representative intratumoral (ITLVD), peritumoral (PTLVD) and non-tumoral (NTLVD) areas. Random samples were selected for double-immunostaining with D2-40 and CD-34 (to distinguish blood and lymphatic vessels) and the proliferation marker Ki-67 to detect lymphangiogenesis. The primary outcome measures were disease-specific survival (DSS) and disease recurrence (urothelial and/or distant).

RESULTS

The median (interquartile range) PTLVD was 4.0 (3.0-6.3), and significantly higher than that for ITLVD, of 0.3 (0-1.7) (P < 0.001), and NTLVD, of 3 (2.0-3.7) (P < 0.001). Both a higher ITLVD and PTLVD, the presence of lymphovascular invasion (LVI) (each P < 0.001) and a high tumour grade (P = 0.004) were associated with reduced DSS on univariate analysis. A higher PTLVD (P = 0.028) and the presence of LVI (P = 0.020) independently predicted reduced DSS on multivariate analysis. IT and PT lymphatic vessels showed proliferating LECs in all analysed samples.

CONCLUSION

Lymphangiogenesis is present in UTUC, as shown by a significantly increased PTLVD and proliferating LECs. Our findings suggest functional relevance of PT lymphatic vessels during lymphatic tumour spread. PTLVD is a potential novel prognostic factor for DSS in UTUC, and further prospective studies will be needed to determine the effect of its routine evaluation on clinical outcomes of this malignancy.

Risk stratification of patients with nodal involvement in upper tract urothelial carcinoma: value of lymph-node density

OBJECTIVE

To determine the risk factors associated with clinical outcome in patients with lymph node (LN)-positive urothelial carcinoma of the upper urinary tract (UTUC) treated with radical nephroureterectomy (RNU) and lymphadenectomy, focusing on the concept of LN density (LND).

PATIENTS AND METHODS

Patients undergoing RNU with regional lymphadenectomy were identified through multi-institutional databases. All pathology slides were re-evaluated by genitourinary pathologists unaware of the clinical data. The exposure variable used was LND (continuously coded and that of all possible thresholds) with recurrence-free and disease-specific survival (DSS) serving as the outcome measures.

RESULTS

Of 432 patients undergoing RNU with lymphadenectomy, 135 (31%) had LN metastases. Within a median follow-up of 4.1 years, 90 of the 135 patients with LN metastases (68%) had disease recurrence and 76 (58%) died from UTUC. The mean (sem) 5-year recurrence-free and DSS probabilities were 27 (4)% and 33 (5)%, respectively. The median (range) LND was 50 (3-100)%. The most informative threshold for LND in relation to outcome was 30%. In multivariable analyses that adjusted for the effects of tumour stage and grade, patients with a LND of > or =30% were at greater risk of both cancer recurrence, with 5-year rates of 25 (5)% vs 38 (8)% (hazard ratio 1.8, P = 0.021) and mortality, with 5-year rates of 30 (6)% vs 48 (9)% (1.7, P = 0.032) compared to those with a LND of <30%. Our results are primarily limited by a lack of standardization in the lymphadenectomy template.

CONCLUSION

We evaluated the concept of LND for the first time in UTUC. LND provides additional prognostic information in patients with node-positive disease after RNU. The use of LND in clinical trials might provide an additional insight into the value of LN dissection in patients undergoing RNU.

Evidence-based sex-related outcomes after radical nephroureterectomy for upper tract urothelial carcinoma: results of large multicenter study

OBJECTIVES

To assess the sex differences in the clinical and pathologic characteristics of upper tract urothelial carcinoma (UTUC) and to determine the effect on prognosis after radical nephroureterectomy (RNU) in a large multicenter series.

METHODS

The records of 1363 patients who had undergone RNU were reviewed from the UTUC Collaboration database. The median follow-up was 47 months (range 0-250). The pathologic slides were re-evaluated by genitourinary pathologists unaware of the original findings from the slides and the clinical outcomes. The endpoints were freedom from tumor recurrence and disease-specific survival.

RESULTS

The male-to-female ratio was 2.1:1. The women were older than the men at diagnosis (70 +/- 11 vs 68 +/- 11 years; P < .001). No significant sex-related differences were found in the presence of symptoms at presentation (P = .70), pathologic stage (P = .98), tumor grade (P = .28), tumor architecture (P = .27), presence of lymphovascular invasion (P = .42), presence of concomitant carcinoma in situ (P = .08), or the presence of lymph node metastases (P = .24). Recurrence developed in 379 patients (28%), and 313 patients (23%) died of their disease. Sex was not associated with disease recurrence (P = .07) or disease-specific survival (P = .13). An adjustment for the effects of the pathologic features did not change the lack of association of sex with the clinical outcomes.

CONCLUSIONS

To our knowledge, this is the largest series analyzing the effect of sex on the outcomes after RNU. No difference was found in the clinicopathologic features or prognosis between women and men treated with RNU for UTUC. The results of this large, international series show that RNU provides durable local control and disease-specific survival for both men and women with UTUC.

Topical chemotherapy in human urothelial carcinoma explants: a novel translational tool for preclinical evaluation of experimental intravesical therapies

BACKGROUND

Urothelial carcinoma (UC) is associated with a high local recurrence rate despite intravesical therapy. There is a lack of representative preclinical models for standardized testing of novel experimental therapies.

OBJECTIVE

To develop an ex vivo model for human UC and to evaluate its ability to generate reproducible and reliable results when testing cytotoxic agents.

DESIGN, SETTING, AND PARTICIPANTS

Normal human urothelium (NHU) and bladder UC explants were collected from patients treated at our institution. A total of 195 surgical explants were cultured on a gelatine matrix. Tissue viability was regularly assessed using nicotinamide adenine dinucleotide (NADH) diaphorase enzymehistochemistry. Topical paclitaxel (PTX) or mitomycin C (MMC) chemotherapy was performed in a subset of 45 UC specimens.

INTERVENTION

All patients underwent radical cystectomy (RC) or primary transurethral resection (TUR) of a bladder UC.

MEASUREMENTS

Triple immunofluorescence (pan-cytokeratin [pan-CK]; 4',6-diamidin-2'-phenylindol-dihydrochloride [DAPI]; terminal deoxynucleotidyl transferase biotin-dUTP nick-end labelling [TUNEL]) and caspase-3 staining of paraffin sections was performed. Proliferation rates were assessed using Ki-67 labelling indices. Apoptosis (percent) was quantified in representative tissue areas to characterize culture stability and to assess antineoplastic effects.

RESULTS AND LIMITATIONS

No signs of necrosis and no significant changes in apoptosis were observed during the first 12 d of culture. Of all explants, 88.5% were vital after 20 d. In a highly reproducible fashion, topical chemotherapy resulted in significantly increased apoptosis (37.4% [19.0-75.0%] for PTX and 36.2% [18.8-46.7%] for MMC) compared with controls (7.5% [3.0-26.8%]; p<0.001]). No statistically significant difference was observed regarding the effects of the two chemotherapeutic agents (p=0.119).

CONCLUSIONS

The presented human ex vivo model takes UC heterogeneity into account and serves as a valuable translational tool. It offers an attractive alternative to preclinical cell line experiments or animal models and may even be used for prospective toxicity and drug efficacy tests in individual patients.

Prognostic implications of lymphangiogenesis in muscle-invasive transitional cell carcinoma of the bladder

OBJECTIVES

Aim of the study was to describe and evaluate the association of lymph vessel density with clinicopathological parameters and survival in patients with muscle-invasive transitional cell carcinoma (TCC) of the bladder.

METHODS

The data on 108 patients with muscle-invasive bladder TCC, who underwent radical cystectomy, were reviewed retrospectively. Sections were analysed immunohistochemically for D2-40, a specific lymphatic endothelial cell (LEC) marker. Counts of lymph vessels were taken in intratumoural and peritumoural areas as well as in normal tissue. To detect proliferating LECs, we performed a double immunostaining for D2-40 and the proliferation marker Ki-67.

RESULTS

Peritumoural vessels were observed in 105 (97.2%) sections and intratumoural vessels in 65 (60.2%). Higher intratumoural lymph vesseI density (LVD) correlated significantly with poor histological differentiation (p=0.01). Higher peritumoural LVD showed a significant association with the presence of lymph node metastasis (p=0.0004). However, LVDs had no statistically significant influence on survival. Intratumoural and peritumoural lymph vessels showed proliferating LECs in varying proportions in all examined samples.

CONCLUSIONS

The present study is the first to suggest the existence of proliferating lymph vessels, and, therefore, of lymphangiogenesis in bladder TCC. To our knowledge, it is also the first to confirm a strong correlation of higher peritumoural LVD with the presence of lymph nodes in clinically localized invasive bladder TCC. These findings indicate that lymphangiogenesis may contribute to tumour dissemination and thus provide a potential target for bladder cancer therapy.

The Internet as recruitment tool for HIV studies: viable strategy for reaching at-risk Hispanic MSM in Miami?

Although use of the Internet as a vehicle for HIV/STI research is increasing, its viability to recruit at-risk populations such as Hispanic men who have sex with men (HMSM) to participate in community-based HIV studies is in its infancy. We report on the first 171 participants enrolled in an ongoing study exploring use of the Internet to recruit Hispanic men who have sex with men (HMSM) living in Miami-Dade County, Florida to participate in community-based studies. We report our initial success with chat-room recruitment and describe the sexual and drug use practices of the initial set of participants who were recruited through the Internet. In addition, we describe the formative work conducted to develop the Internet recruitment procedures we are testing. In two months, we spent 211 hours recruiting in chat-rooms and engaged 735 chatters. One hundred and seventy-six men came to our community sites; 172 (98%) were eligible and completed an audio computer-assisted self-interview. In the previous six months, 94.7% of participants had anal sex; 48.9% did not use condoms for anal sex or used them inconsistently; and 48.5% had used club drugs. Six-month use rates for individual drugs were: poppers (31.6%), cocaine (15.8%), ecstasy (14%) and crystal methamphetamines (11.7%). Use of club drugs was significantly associated with unprotected insertive and unprotected receptive anal sex. These initial findings point to the Internet's potential as a tool for recruiting at-risk Hispanic MSM for community studies.

[New trends in the evaluation of mathematics learning disabilities. The role of metacognition]

INTRODUCTION

The current trends in the evaluation of mathematics learning disabilities (MLD), based on cognitive and empirical models, are oriented towards combining procedures involving the criteria and the evaluation of cognitive and metacognitive processes, associated to performance in mathematical tasks.

AIMS

The objective of this study is to analyse the metacognitive skills of prediction and evaluation in performing maths tasks and to compare metacognitive performance among pupils with MLD and younger pupils without MLD, who have the same level of mathematical performance. Likewise, we analyse these pupils' desire to learn. Subjects and methods. We compare a total of 44 pupils from the second cycle of primary education (8-10 years old) with and without mathematics learning disabilities.

RESULTS

Significant differences are observed between pupils with and without mathematics learning disabilities in their capacity to predict and assess all of the tasks evaluated. As regards their 'desire to learn', no significant differences were found between pupils with and without MLD, which indicated that those with MLD assess their chances of successfully performing maths tasks in the same way as those without MLD. Finally, the findings reveal a similar metacognitive profile in pupils with MLD and the younger pupils with no mathematics learning disabilities.

CONCLUSIONS

In future studies we consider it important to analyse the influence of the socio-affective belief system in the use of metacognitive skills.

On the kinetics and energetics of one-electron oxidation of 1,3,5-triazines

One-electron oxidation of 1,3,5-triazines is observed with both excited uranyl ion (*UO2(2+)) and sulfate radical anion (SO4.-) in aqueous solution, but not with Tl2+, indicating that the standard reduction potentials E degree of 1,3,5-triazine radical cations are = 2.3 +/- 0.1 V vs. NHE, consistent with theoretical calculations; this suggests that if triazines inhibit electron transfer during photosynthesis, they would need to act on the reductive part of the electron transport chain.

To test or not to test: are Hispanic men at highest risk for HIV getting tested?

This study examined how HIV testing history and future testing intentions were related to sexual risk and perceptions of risk in a community sample of 1,052 Hispanic men. This sample is noteworthy in its diverse representation of Hispanics, its high ratio of participants born outside the USA, and its inclusion of heterosexuals and men who have sex with men (MSM). We used area-based sampling to recruit participants at public venues. Data were collected via anonymous, structured interviews from December 1999 to February 2001. Lifetime testing rates were high (76%), but only 45% had been tested in the last 12 months. Results indicate that men at highest risk-those who were MSM, had more partners and had STDs-were more likely to have been tested, and to have been tested recently, than men with lower risk. Being MSM and having been previously tested predicted future testing intentions. Inconsistent condom users with more than five partners were less likely to intend to be tested than men with more than five partners who used condoms consistently. Studying men who have successfully routinized HIV prevention practices (including testing) will assist in the development of interventions for those who remain at risk.

Intracellular oxidation of dipeptides. Base-promoted elimination from N-halodipeptides to 2-[N-alkyl-N-(2-N-alkylimino-2-alkyl-ethanoyl)amino]-2,2-dialkylethanoic acids

One of the possible ways of intracellular oxidation of peptides is via the formation of the corresponding (N-X)-dipeptides, that then undergo base-promoted elimination to yield intermediate 2-[N-alkyl-N-(2-N-alkylimino-2-alkylethanoyl)amino]-2,2-dialkylethanoic acids, which subsequently hydrolyze. Such an elimination process is general-base catalyzed, with Brønsted beta values ranging from 0.26 to 0.31, which suggests an essentially constant degree of proton transfer at the TS. For (N-X)-dipeptides, the ratio k(N-Br)/k(N-Cl) ranges from 2.5 to 15, suggesting a structural dependence of the degree of N-X bond breaking at the TS. The values of beta and k(N-Br)/k(N-Cl) support a concerted asynchronous A(xh)D(H)D(N) mechanism, its TS changing from reactant-like to slightly nitrenium-like depending on the structure of the starting dipeptide. As a consequence of the antiperiplanarity requirements of the reaction, the steric interaction between the leaving group and the substituent on the C bearing the H to be eliminated controls the reaction rate. Such steric interaction is rather important, as indicated by the steric crossed-interaction coefficient (p(ssy') = 0.33). Semiempirical calculations show that bulky substituents in the vicinity of the reaction center imply additional energy requirements for the system to achieve the antiperiplanarity needed at the TS for the reaction to proceed. From the observations reported it follows that (N-X)-dipeptides lose their oxidizing power more readily than analogous (N-X)-amino acids or (N-X)-amines, opening a possible pathway to lessen intracellular halogen-based oxidative stress.

New mothers' knowledge and attitudes about perinatal human immunodeficiency virus infection

OBJECTIVES

To assess new mothers' attitudes toward perinatal human immunodeficiency virus (HIV) testing, their knowledge about perinatal HIV, and their trust of government and scientists.

METHODS

In a cross-sectional survey of 1362 postpartum women at four United States locations in 1997, a standardized interview was administered to new mothers 24-48 hours postpartum to determine their HIV test acceptance, attitudes, and knowledge.

RESULTS

Seventy-five percent of women who were offered HIV tests reported being tested. Although 95% of women were aware of perinatal HIV transmission, only 60% knew that HIV can be transmitted through breast-feeding, and only 51% knew of medication to prevent perinatal transmission. Eighty-four percent of women thought that all pregnant women should be tested for HIV, and 60% thought that prenatal HIV testing should be legally mandated. Twenty percent of women indicated mistrust of government and scientists regarding origins of HIV and potential cures for AIDS. Knowledge about perinatal transmission was unrelated to receipt of prenatal HIV tests. When other factors were controlled for, mistrust was not significantly associated with getting tested.

CONCLUSION

Incomplete knowledge of prevention of perinatal HIV transmission and mistrust were prevalent among new mothers. Knowledge deficits or mistrust did not appear to reduce reported prenatal test rates, but our data suggest that future public health efforts need to educate women about methods of preventing perinatal HIV transmission and at enhancing their trust in the public health system.

Chronic diarrhea impairs intestinal antioxidant defense system in rats at weaning

The aim of the present study was to evaluate the influence of severe protein-energy malnutrition on the antioxidant defense system in the small and large intestine in rats at weaning. Chronic diarrhea and the subsequent malnutrition were induced by oral intake of a lactose-enriched diet. Twenty rats were weaned at 21 days of age, and the control group was fed a semipurified synthetic diet for two weeks. The malnourished group was fed the same diet but carbohydrates were replaced by lactose, and they developed diarrhea one day after. Rats were killed, and macroscopic and histological features were analyzed, DNA content was measured, and alkaline phosphatase, myeloperoxidase, and gamma-glutamyltranspeptidase activities were determined to assess the degree of intestinal injury. Glutathione levels as well as the activities of intestinal glutathione transferase, glutathione reductase, total glutathione peroxidase, selenium-dependent glutathione peroxidase, superoxide dismutase, and catalase were measured to study the antioxidant defense system. Malnourished rats showed loss of body weight and an increase in length and weight in jejunum and ileum, while no significant changes were observed in colon. Epithelial cells showed fewer and shorter microvilli, larger mitochondria with low inner density and loss of cristae, dilated endoplasmic reticulum, and Golgi apparatus. The protein-to-DNA ratio was higher in the jejunum, ileum, and colon of malnourished rats. Glutathione levels decreased 40% in jejunum and 50% in colon of malnourished rats. A 40-50% decrease in the activity of all the enzymes of the antioxidant defense system was observed in the jejunum and ileum of malnourished rats, while only catalase and glutathione transferase activities decreased 50% in colon. These results suggest that early chronic diarrhea and severe protein-energy malnutrition impair the antioxidant defense system in both the small and large intestine, which may have a role in the pathogenesis and maintenance of the vicious circle of malabsorption-diarrhea-malnutrition in infancy.

Experimental ulcerative colitis impairs antioxidant defense system in rat intestine

Increasing attention has been given recently to the role of free radicals in the pathogenesis of ulcerative colitis, since the inflamed intestine is exposed to oxidative stress generated by infiltrating macrophages and neutrophils within the lamina propia. The overall goal of this study was to evaluate whether experimental ulcerative colitis induces significant changes in the antioxidant defense system in an experimental model induced by the intrarectal administration of 2,4,6-trinitrobenzenesulfonic acid. Twenty rats were treated with 80 mg/kg body weight of trinitrobenzenesulfonic acid and 20 with the same volume of 0.9% NaCl. Rats were killed at one and two weeks after treatment to evaluate colon damage by light and electron transmission microscopy. The degree of tissue injury and inflammation was determined by measuring alkaline phosphatase, gamma-glutamyltranspeptidase, and myeloperoxidase activities and prostaglandin E2 and leukotriene B4. Glutathione levels and the activity of the enzymes of the antioxidant defense system were determined. Enzymatic markers of colon injury showed higher activities in rats with ulcerative colitis. Concentrations of prostaglandin E2 and leukotriene B4 were higher in the groups treated for one week with trinitrobenzenesulfonic acid and markers decreased after two weeks of treatment. All antioxidant enzyme activities were higher at one and two weeks after treatment; however, a significant decrease in total glutathione content was also observed. In conclusion, ulcerative colitis induced by trinitrobenzenesulfonic acid damages the intestinal mucosa and is accompanied by a shift in the antioxidant enzyme activities, and low levels of glutathione. This deficiency in glutathione could be a target for new therapies to treat ulcerative colitis.

Acceptance of HIV testing during prenatal care. Perinatal Guidelines Evaluation Project

OBJECTIVE

The purpose of this study was to assess the factors associated with acceptance of HIV testing during pregnancy on the part of women receiving prenatal care at public clinics.

METHODS

Trained interviewers recruited and interviewed 1,357 women receiving prenatal care at clinics in Florida, Connecticut, and New York City.

RESULTS

Eighty-six percent of participants reported having been tested or having signed a consent form to be tested. Acceptance of testing was found to be related to strong beliefs about the benefits of testing, knowledge about vertical transmission, perceived provider endorsement of testing, and social support. Women who declined testing said they did so because they did not perceive themselves to be at risk for HIV (21%) or they faced administrative difficulties (16%) with some aspect of the testing process (for example, scheduling, limited availability of pre-test counselors).

CONCLUSIONS

Acceptance rates can be increased when women understand the modes of vertical transmission and the role of medication regimens in preventing transmission; believe that prenatal identification of HIV can promote the health of mother and child; and perceive their providers as strongly endorsing testing. These points can be woven into a brief pre-test counseling message and made a routine component of prenatal care.

Experimental colitis induced by trinitrobenzenesulfonic acid: an ultrastructural and histochemical study

Inflammatory bowel disease (IBD) of humans is a chronic and devastating disease of unknown etiology. Models of acute colitis in animals have been achieved by intrarectal administration of agents such as 2,4,6-trinitrobenzenesulfonic acid (TNBS) into rat colon. This agent induces focal inflammation and alterations in the colon with features similar to those found in chronic inflammatory diseases in humans. The aim of this study was to assess the effect of TNBS administration on histological and ultrastructural features of the rat colon, especially in areas not affected by transmural inflammation. Also in areas without transmural inflammation, we observed a significant increase in crypt diameter and in the number and area of the goblet cells, as well as alterations in the contents of mucin in goblet cells. We conclude that TNBS treatment in rats led to severe changes in normal architecture of the colon and also in damaged areas where no direct inflammation was produced.

[The self-measurement of blood glucose and mean glycemias in patients with diabetes mellitus]

OBJECTIVE

To assess the influence that self-measurement of capillary blood glucose (SMBG) has on glucaemia control in patients with diabetes mellitus.

DESIGN

Quasi-experimental before and after study.

SETTING

Semi-urban health centre.

PATIENTS

All diabetic patients, with at least two years of evolution, who used reactive strips for SMBG in 1996.

MEASUREMENTS AND MAIN RESULTS

Mean values of base glucaemia in the SMBG study year were compared with those of the year before in 85 patients, 33 men and 52 women, with average age 62.38. Thirteen were type 1 and 72 type 2 diabetics, with a mean 15.61 years of evolution of the disease. A drop of -11.47 mg/dl (SD 44.32) was observed, which was significant (p < 0.05, CI 95%) in the overall results. In all the subgroups, except those treated with non-pharmacological measures, there were drops, ranging between -2.17 mg/dl and -17.01 mg/dl, which were significant in women, in patients with type 2 diabetes, in those who had received health education and in those treated with non-pharmacological measures plus insulin.

CONCLUSIONS

Despite the limitations of this kind of study, our findings point towards a slightly better control of glucaemia levels in diabetic patients after SMBG. It is very doubtful whether it signifies any real improvement in managing the illness.

Lead content in edible wild mushrooms in northwest Spain as indicator of environmental contamination

Lead content was determined in wild growing mushrooms collected from two different areas in the Province of Lugo (NW Spain). It has been analyzed by graphite furnace atomic absorption spectrometry in 95 samples of 13 species (7 mycorrhizals and 6 saprophites). In an assessment of lead concentrations, the following factors have been considered: species and ecology, morphological portion, and traffic pollution. The average lead concentration of the samples was 1 ppm dry weight (dw). Saprophite species presented higher levels than mycorrhizal ones (< 1 ppm), Coprinus comatus reaching the maximum mean concentration with 2.06 and 2.79 ppm of dw in the hymenophore and the rest of the fruit body. Morphological portion, statistically, did not show significant difference between the two portions; however, Macrolepiota procera always presented lead high levels in the hymenophore in all samples. The effect due to traffic pollution has been specially observed in Coprinus comatus, presenting the highest concentration with values of 6.51 and 10.43 ppm, respectively, in samples collected in the city center. This species, as other researchers have indicated, could be considered as an indicator by lead contamination. The contribution of mushrooms to the weekly intake of lead was calculated and the possible health risk for the consumer is pointed out. These data are of great importance in view of toxicology and partly environmental protection.

Severe malnutrition alters lipid composition and fatty acid profile of small intestine in newborn piglets

The goal of this study was to evaluate the influence of severe protein-energy malnutrition (PEM) on lipid composition and fatty acid profile in the small intestinal mucosa of lactating pigs. Malnutrition was achieved by 80% protein-energy restriction for 30 d (20% of the food intake in the control group) in 7-d-old newborn piglets. Malnourished piglets had significantly lower concentrations of cholesterol, phospholipid and triglycerides in the jejunum and ileum compared with freely fed controls. Fatty acid composition of the intestinal mucosa was severely affected by malnutrition. A sharp decline in the relative percentages of (n-3) and (n-6) long-chain polyunsaturated fatty acids (LC-PUFA) in malnourished piglets paralleled higher (n-9) fatty acid proportions in the total mucosa, microsomes and phospholipids of the jejunum. The structure of the small intestine was severely affected as assessed by light and electron microscopy, and alkaline phosphatase and disaccharidase activities in the intestinal mucosa were also significantly impaired. Plasma from malnourished piglets had significantly lower concentrations of (n-3) and (n-6) LC-PUFA than that of control piglets; however, the fatty acid composition of red blood cell membrane was unaffected. Our results suggest that early severe PEM dramatically modifies intestinal membrane lipid composition. Changes in the lipid composition of the small intestinal mucosa and in phospholipid distribution as well as in the fatty acid profile may alter membrane fluidity and organization. These alterations appear to affect the activity of membrane-bound hydrolytic enzymes.

Dietary nucleotides have cytoprotective properties in rat liver damaged by thioacetamide

Liver cirrhosis has been induced with thioacetamide administered via different routes in rats and other species. The oral intake of thioacetamide causes nodular liver cirrhosis in rats characterized by extensive fibrosis occupying most of the hepatic parenchyma. To characterize the cytological features of cirrhosis induced by thioacetamide, and the degree of recovery obtained with dietary nucleotides, we made a morphometric study of the hepatocytes in rats administered 300 mg/l of thioacetamide for 4 months, and in rats receiving the same hepatotoxic treatment but allowed a 2-weeks recovery period on a nucleotide-free diet or a 250 mg/100 g nucleotide-supplemented diet. Thioacetamide caused to cell damage and affected the ultrastructure of hepatocytes leading to a decrease in cytoplasmic area together with increased nuclear and nucleolar size. Dietary supplementation with nucleotides favoured recovery, restoring the cytoplasmic (TN=491.7+/-9.6 vs TAA=305.1+/-3.7), nuclear (73.6+/-2.8 vs 97.4+/-2.9), and nucleolar area of damaged hepatocytes (5.6+/-0.3 vs 14.0+/-0.9). The injury from thioacetamide intake increased liver collagen, but dietary nucleotides prevented hepatic deposition of this protein. This study supports the hypothesis that dietary supplementation with nucleotides is decisive in ensuring hepatocyte recovery after thioacetamide-induced liver damage, and that dietary nucleotides have antifibrotic properties.

Hepatotoxic agent thioacetamide induces biochemical and histological alterations in rat small intestine

We have assessed the effect of the oral ingestion of thioacetamide on small intestine structure and function. Thioacetamide-treated rats showed diminished mucosa weight; protein, DNA, and RNA content; and leucine aminopeptidase activity as compared to controls in both jejunum and ileum. In the jejunum, there was a reduction in the activities of alkaline phosphatase, ATPase, glucose-6-phosphatase, and myeloperoxidase, whereas in the ileum, maltase, lactase, and gamma-glutamyltranspeptidase were reduced. In both jejunum and ileum we found enlarged intercellular spaces, dark epithelial enterocytes, and lymphocyte infiltration. Enterocytes showed lobulated nuclei, deranged mitochondria with loss of their cristae, dilated rough endoplasmic reticulum containing dense material, and vesiculation of the smooth endoplasmic reticulum and the Golgi apparatus. Smooth muscle cells of the intestine exhibited ultrastructural alterations. These findings indicate that chronic oral intake of thioacetamide mimics not only hepatic alterations but also small intestine alterations normally associated with human cirrhosis.

Steatosis and collagen content in experimental liver cirrhosis are affected by dietary monounsaturated and polyunsaturated fatty acids

BACKGROUND AND METHODS

We used thioacetamide administered orally to induce cirrhosis in rats, and after these had recovered for 1 and 2 weeks we examined the effects of dietary supplementation with monounsaturated and n-3 polyunsaturated fatty acids, or with a combination of n-3 and n-6 polyunsaturated fatty acids, on the extent of steatosis and collagen content in the liver.

RESULTS

Nodular cirrhosis, increased collagen content, and lipid accumulation were established after 4 months of treatment with thioacetamide. When the animals were fed a diet rich in oleic acid for 2 weeks, the steatosis and fibrosis decreased. Supplementation with n-3 polyunsaturated fatty acids favored reductions in collagen content but did not reduce the fat accumulation. With a diet supplemented with a mixture of n-3 and n-6 fatty acids we found no reduction in either lipid accumulation or collagen content.

CONCLUSIONS

Fibrosis and steatosis may be influenced by dietary fat, and monounsaturated fat appears to influence favorably the histologic recovery of the damaged liver.