Liver exhibits thermal variations according to the stage of fibrosis progression: A novel use of modulated-differential scanning calorimetry for research in hepatology

AIM

Liver fibrosis results in a disproportion of the hepatic composition and architecture, characterized by a progressive accumulation of fibrillar proteins at the liver parenchyma. Modulated-differential scanning calorimetry (mDSC) is an experimental methodology able to determine the specific thermal signature from any biological substance, based on the variation in heat flow and heat capacity. As these physicochemical properties are directly influenced by compositional and structural changes, we decided to study the thermal behavior of the liver during fibrosis using mDSC.

METHODS

Liver fibrosis was induced in rats by bile duct ligation or carbon tetrachloride administration. Degree of liver fibrosis was determined by histological examination using the Masson-trichrome stain, accompanied by hepatic expression of α-smooth muscle actin. The thermal analysis was performed in a modulated-differential scanning calorimeter using 20 mg of fresh liver mass.

RESULTS

The liver showed a characteristic thermal signature in control animals, which progressively differed among mild (F1), moderate (F2) and advanced (F3-F4) liver fibrosis. For heat flow, the hepatic thermal signature from F3-F4 rats exhibited significant differences when compared with F1, F2 and controls. In terms of heat capacity, liver specimens provided a specific thermal signature for each stage of disease, characterized by a transition temperature onset at 95°C for controls, whereas in F1, F2 and F3-F4 animals this temperature significantly decreased to 93°C, 84°C and 75°C, respectively.

CONCLUSION

Because the liver shows a differential thermal signature according to the degree of fibrosis, mDSC could be a novel tool in the study of liver fibrosis progression.

Prevalence and severity of atherosclerosis in different arterial territories and its relation with obesity

BACKGROUND

There is uneven association between obesity, traditional risk factors, and cardiovascular events. We aimed to analyze the relation between cardiovascular risk factors, including obesity, with the severity of atherosclerosis in different arterial territories.

METHODS

Arteries from five territories (circle of Willis, carotids, coronaries, aorta, and renal) were taken from 185 persons, newborn to 90 years undergoing autopsy in the Forensic Medical Service in Mexico City, to determine atherosclerotic lesions by histopathological study. Lesions were classified according to the American Heart Association grading system as early (types I-III) and advanced (types IV-VI). The degree of atherosclerosis was correlated with arterial territories and risk factors.

RESULTS

Frequencies of advanced lesions according to arterial territories were as follows: circle of Willis, 28%; right carotid, 36%; left carotid, 25%; right coronary, 71%; left coronary, 85%; right renal, 26%; left renal, 29%; and aorta, 52%; P=.0001, for all analyses. There was a higher risk for advanced lesions with increasing body mass index (BMI) (P=.004). However, after adjusting for age, gender, smoking status, hypertension, and diabetes mellitus, BMI was not independently associated with advanced lesions.

CONCLUSIONS

Coronary arteries are significantly more affected than other arterial territories regardless of risk factors, showing the effect of local and systemic factors in the severity of atherosclerosis. We did not find an independent association between advanced atherosclerotic lesions and obesity.

[Ovarian pregnancy. Case report and review of the subject]

A case of a 21-year-old single woman with an acute abdomen, vaginal bleeding and an anemic syndrome is presented. Physical examination and ultrasonography showed an enlarged uterus and a little mass in the right ovary, which was thought to be a fibroma versus pregnancy. Serum levels of chorionic gonadotropin were increased. Abundant black blood loose was found in the peritoneal cavity in the surgery performed. Through a wedge resection, a small hemorrhagic nodule was removed from the surface of the right ovary. Microscopic examination showed ovarian stroma, immature chorionic villi and intermediate extravillous trophoblast, which supported the diagnosis of ectopic ovarian pregnancy. This complication requires an opportune diagnosis, because it continues to be one of the leading risk factors in surgical gynecological emergencies and the first cause of maternal death during the first trimester of pregnancy. A brief review on the subject is presented.

Th2-associated alternative Kupffer cell activation promotes liver fibrosis without inducing local inflammation

Cirrhosis is the final outcome of liver fibrosis. Kupffer cell-mediated hepatic inflammation is considered to aggravate liver injury and fibrosis. Alternatively-activated macrophages are able to control chronic inflammatory events and trigger wound healing processes. Nevertheless, the role of alternative Kupffer cell activation in liver harm is largely unclear. Thus, we evaluated the participation of alternatively-activated Kupffer cells during liver inflammation and fibrosis in the murine model of carbon tetrachloride-induced hepatic damage. To stimulate alternative activation in Kupffer cells, 20 Taenia crassiceps (Tc) larvae were inoculated into BALBc/AnN female mice. Six weeks post-inoculation, carbon tetrachloride or olive oil were orally administered to Tc-inoculated and non-inoculated mice twice per week during other six weeks. The initial exposure of animals to T. crassiceps resulted in high serum concentrations of IL-4 accompanied by a significant increase in the hepatic mRNA levels of Ym-1, with no alteration in iNOS expression. In response to carbon tetrachloride, recruitment of inflammatory cell populations into the hepatic parenchyma was 5-fold higher in non-inoculated animals than Tc-inoculated mice. In contrast, carbon tetrachloride-induced liver fibrosis was significantly less in non-inoculated animals than in the Tc-inoculated group. The latter showed elevated IL-4 serum levels and low IFN-γ concentrations during the whole experiment, associated with hepatic expression of IL-4, TGF-β, desmin and α-sma, as well as increased mRNA levels of Arg-1, Ym-1, FIZZ-1 and MMR in Kupffer cells. These results suggest that alternative Kupffer cell activation is favored in a Th2 microenvironment, whereby such liver resident macrophages could exhibit a dichotomic role during chronic hepatic damage, being involved in attenuation of the inflammatory response but at the same time exacerbation of liver fibrosis.

[Concordance between pathologists in the diagnosis of gastric atrophy according with the OLGA system]

BACKGROUND

The intestinal gastric cancer is preceded by a sequence of pathological changes whose link is mucosal atrophy. The modified Sydney system for atrophy is a parameter not reproducible among pathologists.

AIM

To know the interobserver variability using the OLGA system (Operative Link on Gastritis Assessment).

METHODS

We selected 116 histologic slides. Sixty cases of both types of atrophy and 56 without atrophy were included. Three general pathologists, interested in gastrointestinal biopsies independently review the slides and established a diagnosis. For statistical analyses we employed singles frequencies in order to describe the individual diagnosis and the kappa test for evaluate the concordance between 2 and 4 observers with 2 and 3 categories.

RESULTS

The global concordance has a kappa index of 0.48 (IC 95% 0.4-0.57). When we compared two pathologists the kappa index varies from 0.82(IC 95% 0.73-0.91) to 0.36 (IC 95% 0.22-0.5). The consensus among three pathologists was achieved in 25 out 30 slides in the metaplastic variety and 11 out 30 for the non-metaplastic type. The concordance for the atrophy scale has a kappa index between 0.2 and 0.5.

CONCLUSION

The problematic atrophic evaluation with the Sydney system justify every effort to improve the interobserver evaluation. The OLGA system seems reproducible, although laborious,it requires a careful application, but with daily practice it could be applied easier. The clinician acceptation becomes crucial.

Age and severity of mucosal lesions influence the performance of serologic markers in Helicobacter pylori-associated gastroduodenal pathologies

OBJECTIVE

The course of Helicobacter pylori infection and antibody response to CagA in patients with preneoplastic lesions and gastric cancer has not been thoroughly studied. We aimed to study H. pylori infection and antibody response to CagA in patients with non-atrophic gastritis, preneoplastic lesions, and gastric cancer.

METHODS

We studied patients attending one Oncology Hospital and one General Hospital in Mexico City. Diagnosis was based on endoscopy and histopathology in biopsies from six stomach regions. H. pylori infection was assessed by histology and serology, and antibodies against CagA were measured with immunoassay.

RESULTS

We included 618 patients, 368 with non-atrophic gastritis, 126 with precancerous lesions, and 65 with gastric cancer; in addition, 59 patients with duodenal ulcer were studied. Detection of infection and IgG against CagA had a significant increase from non-atrophic gastritis to mild and up to advanced stages of metaplasia (P < 0.05), followed by decreased infection and IgG to CagA in patients with gastric cancer (P < 0.05). However, infection and CagA antibodies were associated with young gastric cancer cases. Duodenal ulcer showed a significant association with infection detected by histology and serology, particularly among women, and a trend to associate with IgG to CagA.

CONCLUSIONS

This study shows that H. pylori infection and CagA are risk markers for intestinal metaplasia. The prevalence of these risk markers decreases in gastric cancer, probably reflecting that infection decreases after advanced atrophy and metaplasia in the gastric mucosa. State of the disease, age, and sex influence the association of H. pylori infection and IgG response to CagA with gastroduodenal diseases.

Celecoxib induces regression of putative preneoplastic lesions in rat liver

BACKGROUND

Celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, may reduce the risk and mortality of certain types of human cancer. The chemopreventive effect of celecoxib on preneoplastic lesions induced by chemical hepatocarcinogenesis was investigated.

MATERIALS AND METHODS

Male Sprague Dawley rats were fed a celecoxib-supplemented diet between days 18 and 26 post-initiation (1500 ppm) and sacrificed on day 26. The effects of celecoxib on proliferation, apoptosis, COX-2 activity and liver function were evaluated by immunohistochemistry, TUNEL assay, enzyme-immunoassay and spectrophotometry, respectively.

RESULTS

Celecoxib decreased, in area and number, gamma-glutamyltranspeptidase and glutathione S-transferase placental-positive lesions, below levels found after 18 days, by 55.2% and 62.2%, and by 50.5% and 71.1%, respectively, (p < 0.05). Celecoxib neither induced apoptosis nor altered the levels of prostaglandin E2, bilirubin or alanine aminotransferase in the plasma; however, proliferating cell nuclear antigen and cyclin D1 decreased by 77.7% and 94.9%, respectively, (p < 0.05).

CONCLUSION

Celecoxib regresses existing preneoplastic liver lesions through antiproliferative processes, without altering liver function.

[Clinicopathologic cases]

The clinicopathologic conference (CPC) was introduced by Dr. Richard C. Cabot at the Massachusetts General Hospital in the U.S. early in the past century. In a short time, it became one of the most popular medical teaching tools in the world. Despite certain differences between beside diagnosis and CPC diagnosis, the latter is a valuable teaching exercise. During the past few decades, interest in CPCs has declined due to several issues: excessive concern with anatomic diagnosis at the expense of molecular pathogenesis and pathophysiology; emphasis on uncommon diseases; the pathologist being considered an adversary who enjoys demonstrating clinical discussion errors; autopsies failing to reveal abnormalities in physiopathologic disorders and it is not rare to fail to reveal cause of death, and the fact that very few cases are true diagnostic problems, due to advances in diagnostic techniques. In addition, with the decline of interest in autopsies during the past years, in several CPCs, many final diagnosis is performed by biopsy, laboratory tests, or imaging studies. The ideal CPC case to conserve the educational role of this exercise is an autopsy case with adequated clinical, laboratory and/or imaging studies.

Entamoeba histolytica: acute granulomatous intestinal lesions in normal and neutrophil-depleted mice

To study the role of neutrophils in the innate resistance to Entamoeba histolytica intestinal infection in mice, animals were treated with anti-neutrophil monoclonal antibodies prior to intracecal parasite inoculation and the resulting lesions were compared with normal mice that had been equally infected. In contrast to our previous finding that neutrophils are critical in eliminating E. histolytica infection in the liver, we show here that neutrophils are not absolutely required to eliminate E. histolytica infection from the intestine. Although the neutrophils are not critical for resolution of the E. histolytica infection, neutrophils do appear to provide some measure of protection as the intestinal amoeba burden was higher at early timepoints after infection in the neutropenic animals. In addition, we found that while both the normal and the neutrophil-depleted mice developed ulcerative lesions in the colon, the neutropenic mice had an increased frequency of granulomas that formed around the amoeba. Thus, our findings appear to be the first evidence showing that granulomatous inflammation can occur after intestinal infection in mice using axenically cultured amoeba.

The histopathology and biologic prognostic factors of Barrett's esophagus: a review

In Barrett's esophagus, stratified squamous mucosa of the lower third of the esophagus is replaced by columnar mucosa, as a complication of chronic gastroesophageal reflux. The presence of Barrett's esophagus appears to be a major factor in the progression to adenocarcinoma of the lower third of the esophagus. Therefore it is crucial to identify the subset of patients at risk for the development of adenocarcinoma. Dysplasia is an important histologic feature to evaluate because it identifies those patients who require follow-up. The diagnosis of biopsies with lesser degrees of abnormalities, however, makes microscopic evaluation less helpful in identifying patients who need more frequent endoscopic biopsy surveillance. DNA ploidy and the use of monoclonal antibodies, such as suppressor gene product p53, oncogene cerbB-2, and Ki-67, have added dramatically to our understanding of the biology of Barrett's metaplasia and have given us objective indicators to predict the presence of an increased risk of developing cancer.

[Morphological abnormalities in liver cirrhosis]

Cirrhosis is the consequence of diverse and repeated insults to the liver which induce hepatocellular necrosis and degeneration. Hepatic cirrhosis is the end-stage of several hepatopathies and represents a good example of abnormal regeneration and healing. In this manuscript, the author describe and analyze the so-called micro and macro nodular cirrhosis and the differential diagnosis among congenital hepatic fibrosis, alcoholic diffuse interstitial fibrosis, nodular regenerative hyperplasia, and idiopathic portal hypertension.

[Histological abnormalities in acute and chronic hepatitis]

Liver damage induced by the hepatitis virus can be classified in acute, fulminant, chronic persistent and chronic active, according with the point of view of the pathologist. In this manuscript, the author reviews and carefully describes the histological patterns in each of the viral hepatitis forms. Difficulties in histological differential diagnosis, small size biopsy limitations and modifications induced by ingestion of corticosteroids and immunosupprevisive drugs are commented.