Disordered central cardiovascular regulation in portal hypertensive and cirrhotic rats.

Portal hypertension due to either prehepatic portal hypertension or cirrhosis is associated with cardiovascular derangement. We aimed to delineate regulatory mechanisms in the brain stem cardiovascular nuclei in rat models of prehepatic portal hypertension and cirrhosis. Neuronal activation in the nucleus of the solitary tract (NTS) and ventrolateral medulla (VLM) were assessed by immunohistochemical staining for the immediate-early gene product Fos. In the same sections, catecholaminergic neurons were counted by tyrosine hydroxylase (TH) staining. Ninety minutes after hypotensive hemorrhage (or no volume challenge), the animals were killed for Fos and TH medullary staining. These protocols were repeated after capsaicin administration. The NTS of unchallenged sham-operated rats had scant Fos-positive cells (3.6 +/- 0.4 cells/section), whereas hemorrhage significantly increased Fos staining (91.8 +/- 14). In contrast, the unchallenged portal hypertensive and cirrhotic groups showed increased Fos staining (14.3 +/- 5.8 and 32.8 +/- 2.8, respectively), which hemorrhage did not alter significantly. The numbers of TH-positive cells were similar in the three unchallenged groups; double labeling revealed that approximately 50% of TH-positive cells were activated by hemorrhage in the sham and cirrhotic rats but not the portal hypertensive rats. Similar patterns of Fos and TH staining were observed in the VLM. Capsaicin treatment not only significantly reduced the Fos-positive neuron numbers in portal hypertensive and cirrhotic rats but also attenuated hemorrhage-induced Fos and double-positive cells in both NTS and VLM. These results suggest that disordered trafficking in capsaicin-sensitive nerves and central dysregulation contribute to blunted cardiovascular responsiveness in cirrhosis and prehepatic portal hypertension.

Proteolytic activity of human non-Hodgkin's lymphomas.

This study was conducted to assess the net proteolytic activity of human non-Hodgkin's lymphomas (NHLs). We have compared the extracellular matrix (ECM)-degradative abilities of human NHLs, reactive lymphoid hyperplasias, and established lymphoid cell lines using Matrigel invasion and elastin degradation assays. The inhibition studies allowed identification of the classes of proteinases involved in ECM degradation. Our results indicate that lymphocytes and other leukocytes derived from both human NHLs and reactive lymphoid hyperplasias are capable of Matrigel penetration, but only cells derived from the high-grade human NHLs degrade elastin in vitro. Established lymphoid cell lines (both malignant and Epstein-Barr virus immortalized) do not produce MMP-9, do not penetrate the Matrigel, and do not degrade elastin. Moreover, in human NHLs, elastolytic activity is blocked by metalloproteinase inhibitors, while inhibitors of the other classes of proteolytic enzymes have only minor effects. This study identifies metalloproteinases as the most important class of proteinases involved in ECM degradation by NHLs. The previous studies suggest that, within this class, MMP-9 represents the key enzyme that plays a role in the biological aggressiveness of human NHLs.

Blunted responsiveness of the neuronal activation marker Fos in brainstem cardiovascular nuclei of cirrhotic rats.

Cardiovascular function in cirrhosis is deranged, with indirect evidence of abnormal central cardiovascular regulation. We aimed to elucidate the role of brainstem cardiovascular nuclei in hemodynamic regulation by examining the protein product, Fos, of the immediate-early gene c-fos, in cirrhotic rats. Cirrhosis was induced by chronic bile duct ligation (BDL) of 25-days duration, while controls underwent a sham operation. To examine the effects of jaundice per se in the absence of cirrhosis, a third group of 5-day BDL rats was also studied. All rats were anesthetized with pentobarbital, and catheters were inserted to measure baseline blood pressure and heart rate. Separate groups were then subjected to volume manipulation by a hypotensive hemorrhage or isotonic saline infusion, or no challenge. Ninety minutes after the volume manipulation, the animals were killed and the medulla sectioned and stained for Fos by immunohistochemisty. The nucleus tractus solitarius (NTS) of the sham-operated unchallenged rats showed scant Fos immunoreactivity (27.8 +/- 3.3 cells), but both hemorrhage and volume infusion significantly increased Fos staining (86.0 +/- 3.7 and 95.2 +/- 8.5, respectively). In contrast, the unchallenged cirrhotic rats showed markedly increased Fos in the NTS (154.6 +/- 27.0), but neither hemorrhage nor volume infusion significantly changed the amount of Fos staining. Fos staining in the ventrolateral medulla (VLM) followed a similar pattern with low staining in the unchallenged sham rats and increased staining in the other groups, but no differences between the unchallenged and the volume-manipulated cirrhotic groups. The 5-day BDL jaundiced rats showed no baseline increase in Fos staining, nor any significant increase after hemorrhage. These results showing baseline activation of central neuronal regions responsible for blood pressure homeostasis, but completely blunted responsiveness in cirrhotic rats, confirm a central origin of disordered cardiovascular regulation. The presence of jaundice may also contribute to the central cardiovascular hyporesponsiveness.

Interleukin-1 alpha induces corticotropin-releasing factor secretion and synthesis from NPLC-KC cells through various second messenger pathways.

Interleukin-1 (IL1) is a key messenger implicated in endocrine and immune systems that interact to mediate the stress response. Corticotropin-releasing factor (CRF) secretion and synthesis in the NPLC-KC human hepatoma cell line has been shown to respond to IL1 stimulation. We have studied how various inhibitors of second messenger pathways alter this IL1 effect. NPLC-KC cells were grown in six-well Costar plates and treated for 12 or 24 h with or without 500 pM IL1 (alpha form) in the presence of various inhibitors of second messenger pathways. Inhibitors included the protein kinase C (PKC) inhibitor, H-7; the protein kinase A inhibitor, IP20; or the cyclooxygenase inhibitor indomethacin (IND). Both cell extracts and secretion media were assayed for CRF-like immunoreactivity by radioimmunoassay. IP20, H-7, and IND all reduced basal CRF secretion at 24 h but not at 12 h. No effects were seen on basal CRF synthesis with these inhibitors. The three inhibitors also reduced IL1 effects on CRF secretion at 12 and 24 h. The reduction seen with all three inhibitors was statistically significant (P < 0.05) at 12 h. Although a reduction was seen with all three inhibitors at 24 h, a statistically significant reduction (P < 0.05) was demonstrable only for H-7. IL1 stimulated CRF synthesis in the NPLC-KC cells appears to only involve PKC pathways. Only the PKC inhibitor H-7 reduced the augmentation that IL1 produces on CRF synthesis. This effect was statistically significant at 12 and 24 h (P < 0.05).